CN111896796B

CN111896796B - Current oscillation detection device and method of PFC circuit and power supply system

Info

Publication number: CN111896796B
Application number: CN202010767001.4A
Authority: CN
Inventors: 陈名才; 华洪香
Original assignee: Gree Electric Appliances Inc of Zhuhai
Current assignee: Gree Electric Appliances Inc of Zhuhai
Priority date: 2020-08-03
Filing date: 2020-08-03
Publication date: 2021-07-20
Anticipated expiration: 2040-08-03
Also published as: CN111896796A

Abstract

The invention discloses a current oscillation detection device, a current oscillation detection method and a power supply system of a PFC circuit, wherein the device comprises the following components: the device comprises a zero-crossing detection unit, a current detection unit, a detection unit and a control unit; the zero-crossing detection unit is used for detecting the zero position of the alternating-current voltage of the PFC circuit; the current detection unit is used for detecting a sampling voltage signal of the power supply current of the PFC circuit at the zero point of the alternating-current voltage of the PFC circuit; the detection unit is used for detecting an oscillation signal in the sampling voltage signal and converting the oscillation signal into a digital level signal; and the control unit is used for judging whether the power supply current of the PFC circuit has oscillation phenomenon according to the digital level signal. The scheme of the invention can solve the problem that the power supply reliability of the power supply system is influenced because the current oscillation phenomenon generated when the adjustment parameter of the PFC circuit is not matched with the power supply system can not be identified, and achieves the effect of improving the power supply reliability of the power supply system.

Description

Current oscillation detection device and method of PFC circuit and power supply system

Technical Field

The invention belongs to the technical field of power electronics, and particularly relates to a current oscillation detection device and method for a PFC (power factor correction) circuit and a power supply system, and particularly relates to a circuit and method for detecting power supply current oscillation and a power supply system.

Background

With the wide application of various power electronic devices in various fields such as power systems, traffic, industry, household and the like, the problem that the generated current harmonic interference pollutes the power grid is increasingly prominent, and the harmonic interference brings a series of hazards to the system and the use environment of the power grid, so that the problem of power grid pollution gradually draws attention of people. In order to suppress the current harmonics generated by the power device and reduce the pollution of the power grid, some schemes may add a Power Factor Correction (PFC) circuit to the higher power equipment or electrical product to improve the harmonic interference generated by the equipment or electrical product itself. However, when the PFC circuit is working, a current oscillation phenomenon may occur when the adjustment parameter of the PFC circuit is not matched with the power supply system, and if the current oscillation phenomenon cannot be identified and suppressed, the power supply reliability of the PFC circuit may be affected.

The above is only for the purpose of assisting understanding of the technical aspects of the present invention, and does not represent an admission that the above is prior art.

Disclosure of Invention

The invention aims to provide a current oscillation detection device and method of a PFC circuit and a power supply system, so as to solve the problem that the power supply reliability of the power supply system is influenced because the current oscillation phenomenon generated when the adjustment parameter of the PFC circuit is not matched with the power supply system cannot be identified, and achieve the effect of improving the power supply reliability of the power supply system.

The invention provides a current oscillation detection device of a PFC circuit, comprising: the device comprises a zero-crossing detection unit, a current detection unit, a detection unit and a control unit; the zero-crossing detection unit is used for detecting the zero position of the alternating-current voltage of the PFC circuit; the current detection unit is used for detecting a sampling voltage signal of the power supply current of the PFC circuit at the zero point of the alternating-current voltage of the PFC circuit; the detection unit is used for detecting an oscillation signal in the sampling voltage signal and converting the oscillation signal into a digital level signal; and the control unit is used for judging whether the power supply current of the PFC circuit has oscillation phenomenon according to the digital level signal.

Optionally, the current detection unit includes: the device comprises a sampling module and a conversion module; wherein, the current detection unit detects the sampling voltage signal of the supply current of the PFC circuit, including: the sampling module is used for converting the power supply current of the PFC circuit into a voltage signal; and the conversion module is used for amplifying the voltage signal to obtain the sampling voltage signal.

Optionally, the wave detection unit includes: a filtering module and a comparing module; wherein, the detection unit detects the oscillation signal in the sampling voltage signal and converts the oscillation signal into a digital level signal, and the detection unit comprises: the filtering module is used for filtering set frequency components in the sampling voltage signal and taking the residual signal as the oscillation signal; and the comparison module is used for converting the oscillation signal into a digital level signal with the same set oscillation frequency.

Optionally, wherein the filtering module includes: a low-pass filter circuit; the low-pass filter circuit comprises: an active low-pass filter circuit composed of operational amplifiers; and/or, the comparison module comprises: the device comprises a comparator, a first isolation module, a second isolation module, a phase-shifting module and an output module; wherein, the comparing module converts the oscillation signal into a digital level signal with the same set oscillation frequency, and the comparing module comprises: the first isolation module and the second isolation module are respectively arranged at the inverting input end and the non-inverting input end of the comparator and are used for isolating input signals of the inverting input end and the non-inverting input end of the comparator to obtain a first isolation signal and a second isolation signal; the phase shifting module is arranged between the first isolation module and the inverting input end of the comparator and is used for enabling the first isolation signal to generate a phase shift with a set phase difference to obtain a phase shift signal; the output module is arranged at the output end of the comparator and used for outputting the digital level signal after the comparator compares the phase shift signal with the second isolation signal.

Optionally, the determining, by the control unit, whether an oscillation phenomenon exists in the power supply current of the PFC circuit according to the digital level signal includes: under the condition that the alternating-current voltage of the PFC circuit is determined to be at the zero position, starting timing of second set time after delaying the first set time, and determining whether the digital level signal is received or not; if the digital level signal is received, accumulating the signal times of the digital level signal, and continuously judging whether the power supply current of the PFC circuit has oscillation phenomenon according to the accumulated signal times; and if the digital level signal is not received, continuously judging whether the power supply current of the PFC circuit has oscillation phenomenon or not according to whether the timing time of the second set time is up or not.

Optionally, the continuously determining whether the power supply current of the PFC circuit has an oscillation phenomenon according to the accumulated number of times of the signal includes: determining whether the accumulated number of times of the signals is 1; if the accumulated signal frequency is 1, starting timing of third set time, determining whether the timing time of the second set time is up, and continuously judging whether the power supply current of the PFC circuit has oscillation phenomenon according to whether the timing time of the second set time is up; if the accumulated signal frequency is not 1, determining whether the timing time of the third set time is up, and continuously judging whether the power supply current of the PFC circuit has oscillation phenomenon according to whether the timing time of the third set time is up; and/or, continuously judging whether the power supply current of the PFC circuit has oscillation phenomenon according to whether the timing time of the second set time is up, including: determining whether the timing time of the second set time is up; re-determining whether the digital level signal is received or not if the timing time of the second set time is not up; and resetting the timing time of the second set time when the timing time of the second set time is up, resetting the accumulated signal times, and then re-determining whether the alternating-current voltage of the PFC circuit is at the zero position.

Optionally, the continuously determining whether the power supply current of the PFC circuit has an oscillation phenomenon according to whether the timing time of the third set time is up includes: determining whether the timing time of the third set time is up; if the timing time of the third set time is up, determining whether the accumulated signal times is greater than a first set time and less than a second set time; if the accumulated signal times are greater than a first set time and less than a second set time, determining that the power supply current of the PFC circuit has an oscillation phenomenon; otherwise, resetting the timing time of the second set time, the timing time of the third set time and the accumulated signal times and then re-determining whether the alternating-current voltage of the PFC circuit is at the zero position; and if the timing time of the third set time is not up, continuously judging whether the power supply current of the PFC circuit has oscillation phenomenon or not according to whether the timing time of the second set time is up or not.

In accordance with another aspect of the present invention, there is provided a power supply system including: the current oscillation detection device of the PFC circuit described above.

In another aspect, the present invention provides a method for detecting current oscillation of a PFC circuit of a power supply system, including: detecting the zero position of the alternating voltage of the PFC circuit; detecting a sampling voltage signal of power supply current of the PFC circuit at the zero point of alternating voltage of the PFC circuit; detecting an oscillation signal in the sampling voltage signal and converting the oscillation signal into a digital level signal; and judging whether the power supply current of the PFC circuit has oscillation phenomenon or not according to the digital level signal.

Optionally, wherein the detecting a sampled voltage signal of a power supply current of the PFC circuit includes: converting the power supply current of the PFC circuit into a voltage signal; amplifying the voltage signal to obtain the sampling voltage signal; and/or, the detecting the oscillation signal in the sampling voltage signal and converting the oscillation signal into a digital level signal comprises: filtering out set frequency components in the sampling voltage signal, and taking a residual signal as the oscillation signal; and converting the oscillation signal into a digital level signal with the same set oscillation frequency.

Optionally, the converting the oscillation signal into a digital level signal with the same set oscillation frequency includes: isolating input signals of an inverting input end and a non-inverting input end of the comparator to obtain a first isolation signal and a second isolation signal; enabling the first isolation signal to generate a phase shift with a set phase difference to obtain a phase shift signal; outputting the digital level signal after the comparator compares based on the phase shifted signal and the second isolated signal.

Optionally, the determining whether the power supply current of the PFC circuit has an oscillation phenomenon according to the digital level signal includes: under the condition that the alternating-current voltage of the PFC circuit is determined to be at the zero position, starting timing of second set time after delaying the first set time, and determining whether the digital level signal is received or not; if the digital level signal is received, accumulating the signal times of the digital level signal, and continuously judging whether the power supply current of the PFC circuit has oscillation phenomenon according to the accumulated signal times; and if the digital level signal is not received, continuously judging whether the power supply current of the PFC circuit has oscillation phenomenon or not according to whether the timing time of the second set time is up or not.

Therefore, according to the scheme of the invention, the problem that the power supply reliability of the power supply system is influenced due to the fact that the current oscillation phenomenon generated when the adjustment parameter of the PFC circuit is not matched with the power supply system cannot be identified is solved by detecting the oscillation signal of the power supply current and converting the oscillation signal into the digital level signal with the same frequency as the oscillation current and accurately identifying the power supply oscillation phenomenon by combining a software algorithm, and the effect of improving the power supply reliability of the power supply system is achieved.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.

Drawings

Fig. 1 is a schematic structural diagram of a current oscillation detection apparatus of a PFC circuit according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of an embodiment of a circuit for detecting power supply current oscillation in the solution of the present invention, specifically, a schematic control structural diagram in the application of the solution of the present invention in a PFC circuit;

FIG. 3 is a diagram illustrating an oscillation curve of a power supply current oscillation phenomenon;

FIG. 4 is a schematic control flow diagram of the oscillation current identification logic in an embodiment of the present invention;

FIG. 5 is a schematic diagram of an embodiment of a detector circuit module (i.e., a detector circuit) according to the present invention;

FIG. 6 is a graph illustrating the comparison of the power oscillation current detection signal effect in the solution of the present invention, wherein the waveform S1 is the power current that has generated oscillation, and the waveform S2 is the output signal after passing through the detection circuit module (i.e. the detection circuit);

fig. 7 is a schematic diagram of a comparison curve of input and output signals of a mid-wave circuit in a mid-wave circuit module (i.e., a detection circuit), i.e., a schematic diagram of a comparison curve of a filtering effect of a filtering circuit on signals, in the scheme of the present invention, where a waveform S3 is a waveform of a current sampling amplification signal before filtering, and includes a high-frequency switching current component with a smaller amplitude and a low-frequency oscillation current component with a larger amplitude, and a waveform S4 is a waveform of a current sampling amplification signal after filtering, and only a signal of the low-frequency oscillation current component is retained;

FIG. 8 is a schematic diagram showing a comparison curve of input and output signals of the comparing and detecting circuit in the detecting circuit module according to the present invention, wherein the waveform S5 is a low-pass filtered current sample signal, the waveform S6 is a positive phase input signal of the comparator, and the waveform S7 is a phase-shifted negative phase input signal of the comparator;

FIG. 9 is a schematic view of the oscillation curve of the detection time in the embodiment of the present invention;

fig. 10 is a flowchart illustrating a method for detecting current oscillation of a PFC circuit according to an embodiment of the present invention;

FIG. 11 is a flowchart illustrating an embodiment of detecting a sampled voltage signal of a power supply current of a PFC circuit according to the method of the present invention;

FIG. 12 is a flowchart illustrating an embodiment of detecting an oscillation signal in the sampled voltage signal and converting the oscillation signal into a digital level signal according to the method of the present invention;

FIG. 13 is a flowchart illustrating an embodiment of the method of the present invention for converting the oscillation signal into a digital level signal having the same oscillation frequency as the set oscillation frequency;

fig. 14 is a schematic flow chart illustrating an embodiment of determining whether the power supply current of the PFC circuit oscillates according to the digital level signal in the method of the present invention;

fig. 15 is a schematic flow chart illustrating an embodiment of continuously determining whether the power supply current of the PFC circuit oscillates according to the accumulated signal times in the method of the present invention;

fig. 16 is a schematic flow chart illustrating an embodiment of continuously determining whether the power supply current of the PFC circuit oscillates according to whether the timing time of the second set time is up;

fig. 17 is a flowchart illustrating an embodiment of continuously determining whether the power supply current of the PFC circuit oscillates according to whether the timing time of the third setting time is up.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail and completely with reference to the accompanying drawings. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

According to an embodiment of the present invention, there is provided a current oscillation detection apparatus of a PFC circuit. Referring to fig. 1, a schematic diagram of an embodiment of the apparatus of the present invention is shown. The current oscillation detection device of the PFC circuit may include: the current oscillation detection device of the PFC circuit in the power supply system can comprise: the device comprises a zero-crossing detection unit (such as a power voltage zero-crossing detection module), a current detection unit (such as a current sampling resistor R and a current sampling amplification module), a detection unit (such as a detection circuit module) and a control unit (such as an MCU). For example: the circuit for detecting the power supply current oscillation at least comprises a current sampling signal amplification module, a detection circuit module (namely a detection circuit) and a power supply voltage zero-crossing detection module.

Specifically, the zero-cross detection unit is disposed between an ac power supply of the PFC circuit and the MUC, and may be configured to detect a zero-point position of an ac voltage of the PFC circuit.

For example: in order to more accurately and effectively identify the current oscillation phenomenon, signal detection and judgment can be carried out only near the position of the wave crest or the wave trough of the power supply through software setting. For example, the power supply voltage zero-crossing detection module may be configured to detect a zero position of the current ac voltage, detect a zero position of the input ac voltage, and transmit the zero position to the MCU, so as to determine a peak position of the power supply.

For example: the power supply voltage zero-crossing detection module detects a power supply input voltage zero-crossing signal and judges whether the detected power supply input voltage zero-crossing signal is an input voltage zero point or not, if so, the detected power supply input voltage zero-crossing signal is an input voltage zero point, and if not, the power supply voltage zero-crossing detection module is returned to be continuously controlled to detect the power supply input voltage zero-crossing signal.

Specifically, the current detection unit is disposed between a power switching tube of the PFC circuit and the MCU, and may be configured to detect a sampling voltage signal of a power supply current of the PFC circuit at a zero point of an ac voltage of the PFC circuit.

Optionally, the current detection unit may include: a sampling module (such as a current sampling resistor R) and a conversion module (such as a current sampling amplification module).

The detecting, by the current detecting unit, a sampling voltage signal of the power supply current of the PFC circuit at a zero point of the ac voltage of the PFC circuit may include:

the sampling module is arranged between an emitter of a power switching tube of the PFC circuit and a rectifier bridge and can be used for converting power supply current of the PFC circuit into a voltage signal. The node position of the current sampling resistor R in the topological circuit is to ensure that the main operation current of the product can flow through the current sampling resistor R. The current sampling resistor R may be used to convert the supply current signal into a voltage signal.

The conversion module is arranged between the sampling module and the detection module, and can be used for amplifying the voltage signal to obtain the sampling voltage signal. For example: the current sampling amplifying module can be used for amplifying the voltage small signal flowing through the current sampling resistor R into a voltage signal which can be detected conveniently. The current sampling signal amplifying module converts and amplifies a current signal flowing through the current sampling resistor R to output a voltage signal convenient for detection, i.e., a voltage sampling signal, and the amplified voltage sampling signal is input to the detector circuit module (i.e., a detector circuit).

Therefore, the power supply current is sampled by the sampling module and the conversion module, so that a power supply current signal can be conveniently and accurately obtained, and an accurate judgment basis can be provided for judging whether the power supply current oscillates.

Specifically, the detection unit is disposed between the output end of the current detection unit and the MCU, and can be configured to detect an oscillation signal in the sampled voltage signal and convert the oscillation signal into a digital level signal. For example: the detection module can be used for detecting and converting the oscillation signal component of a certain frequency band in the amplified voltage signal into a digital level signal.

In an alternative example, the detection unit may include: a filtering module (e.g., a low pass filter circuit) and a comparing module (e.g., a comparison detection circuit). For example: the detection circuit module can comprise a low-pass filter circuit and a comparison detection circuit which are connected in sequence. The low-pass filter circuit can select a passive filter circuit scheme or an active filter circuit scheme, the active low-pass filter circuit can also select a passive filter circuit or an active band-pass filter circuit, and meanwhile, a proper filter frequency range can be selected according to the application requirements of a specific product scheme.

The detecting unit detects an oscillation signal in the sampled voltage signal and converts the oscillation signal into a digital level signal, and may include:

the filtering module may be configured to filter out a set frequency component in the sampled voltage signal, and use a residual signal as the oscillation signal.

More optionally, the filtering module may include: a low pass filter circuit. The low-pass filter circuit may include: and the active low-pass filter circuit consists of an operational amplifier.

For example: a low pass filter circuit, may include: the circuit comprises an operational amplifier U2A, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a third capacitor C3 and a fourth capacitor C4. The inverting input terminal of the operational amplifier U2A is grounded through the eighth resistor R8, and is connected to the output terminal of the operational amplifier U2A through the ninth resistor R9. The non-inverting input terminal of the operational amplifier U2A is connected to the input signal through the third capacitor C3, the seventh resistor R7 and the sixth resistor R6. The common terminal of the seventh resistor R7 and the sixth resistor R6 is connected to the output terminal of the operational amplifier U2A through the fourth capacitor C4. The output terminal of the operational amplifier U2A is connected to the comparison detection circuit. Active filter circuits can be used primarily to filter out unwanted high frequency signals, so in principle the circuit gain is set close to 1.

Therefore, an active low-pass filter circuit composed of an operational amplifier can separate an abnormal oscillation current component of 2-5 kHz from a normal switching tube switching current signal of more than 20kHz and other unnecessary high-frequency interference signals.

The comparison module may be configured to convert the oscillation signal into a digital level signal having the same set oscillation frequency.

For example: a low-pass filter circuit in a detection circuit module (namely a detection circuit) filters high-frequency components in the voltage sampling signal, then the high-frequency components are transmitted to a comparison detection circuit to convert a low-frequency oscillation signal in the voltage sampling signal into a digital level signal with the same oscillation frequency, and finally the digital level signal is transmitted to an MCU chip.

Therefore, the oscillation signal in the sampling voltage signal is detected by the filtering module and the comparing module and is converted into the digital level signal, the structure is simple, and the oscillation signal of the more accurate power current can be obtained.

More optionally, the comparing module may include: a comparator (e.g., comparator U1), a first isolation block (e.g., first diode D1), a second isolation block (e.g., second diode D2), a phase shift block, and an output block.

The comparing module converts the oscillation signal into a digital level signal having the same frequency as the set oscillation frequency, and may include:

the first isolation module and the second isolation module are respectively arranged at the inverting input end and the non-inverting input end of the comparator, and can be used for isolating input signals of the inverting input end and the non-inverting input end of the comparator to obtain a first isolation signal and a second isolation signal. For example: the first diode D1 and the second diode D2 can isolate the positive and negative input signals of the comparator U1, and the first diode D1 and the second diode D2 preferentially select the diode with low conduction voltage drop, so that the current oscillation detection range of the signal PFC circuit can be maximally improved.

The phase shifting module is arranged between the first isolation module and the inverting input end of the comparator and can be used for enabling the first isolation signal to generate phase shift of a set phase difference, even if the oscillation signal isolated by the first isolation module generates the phase shift of the set phase difference, the phase shift signal is obtained.

The output module is disposed at an output end of the comparator, and may be configured to output the digital level signal after the comparator compares the phase shift signal with the second isolation signal.

For example: the circuit composed of the first resistor R1, the second resistor R2 and the first capacitor C1 can shift the phase of the inverted input signal of the comparator U1, so that the oscillation signal is shifted in phase while the distortion of the oscillation signal is reduced as much as possible in the parameter selection, and the absolute phase difference is 30 ° or more. The second resistor R2 is basically the same as or similar to the first resistor R1, so that the overall voltage amplitudes of the positive and negative phase input signals of the comparator U1 are ensured to be the same. When the input signal oscillates, the positive and negative input signals of the comparator U1 continuously cross each other due to their equal amplitudes and phase differences, and the cross-over frequency is the same as the oscillation frequency, and the comparator U1 outputs a high/low level signal with the same cross-over frequency.

Therefore, the oscillation signal is converted into a digital level signal with the same set oscillation frequency through the comparator, the first isolation module, the second isolation module, the phase shift module and the output module, the low-frequency oscillation signal can be processed to obtain the digital level signal, and the MCU can accurately judge whether the power supply current has the vibration phenomenon or not based on the digital level signal.

Specifically, the control unit may be configured to determine whether a power supply current of the PFC circuit has an oscillation phenomenon according to the digital level signal, so as to perform suppression in time when it is determined that the power supply current of the PFC circuit has the oscillation phenomenon. For example: and the MCU chip identifies the digital level signal according to a preset algorithm and judges whether the current power supply current has an oscillation phenomenon.

Therefore, the power supply current waveform is sampled at the zero point position of the alternating voltage, the current waveform signal is filtered, the current oscillation signal is converted into a high-level signal which can be digitally detected, and finally, the oscillation information of the power supply current is identified by combining a software algorithm, so that whether the power supply current vibrates or not can be accurately judged, and the power supply reliability of a power supply system is improved by timely restraining when the power supply current is determined to vibrate.

Optionally, the determining, by the control unit, whether the power supply current of the PFC circuit has an oscillation phenomenon according to the digital level signal may include: under the condition that the zero-crossing detection unit detects the zero position of the alternating-current voltage of the PFC circuit, namely under the condition that the alternating-current voltage of the PFC circuit is determined to be at the zero position, timing of second set time is started after first set time is delayed, and whether the digital level signal is received or not is determined; within the timing time of the second set time, if the digital level signal is received, accumulating the signal times of the digital level signal, and continuously judging whether the power supply current of the PFC circuit has oscillation phenomenon according to the accumulated signal times; and if the digital level signal is not received within the timing time of the second set time, continuously judging whether the power supply current of the PFC circuit has oscillation phenomenon or not according to whether the timing time of the second set time is up or not.

For example: after detecting the trigger signal of the power supply voltage zero-crossing detection module, the MCU executes a first set time T1 for time delay, starts to execute a second set time T2 for timing after the first set time T1 is delayed, and simultaneously starts to receive the trigger signal output by the detection circuit module; after the MCU receives the trigger signal of the detection circuit, the times of the trigger signal are accumulated, and if the trigger signal of the detection circuit is received for the first time, the MCU simultaneously starts to execute timing of third set time T3 until timing of second set time T2 or third set time T3 is finished, if the timing of T3 is finished, the MCU judges whether the received times N of the trigger signal of the detection circuit module meets N2 > N > N1, if the times N meets the conditions, the MCU judges that the oscillation phenomenon of the power current occurs at the moment, and if the times N does not meet the conditions, the MCU returns to detect again.

Therefore, whether the power supply current of the PFC circuit has the oscillation phenomenon or not is judged under the condition that the digital level signal is determined by delaying the time when the alternating-current voltage of the PFC circuit is at the zero position, and whether the power supply current of the PFC circuit has the oscillation phenomenon or not is judged more accurately and timely.

More optionally, the continuously determining whether the power supply current of the PFC circuit has the oscillation phenomenon according to the accumulated number of times of the signal may include: determining whether the accumulated number of times of the signals is 1; if the accumulated signal frequency is 1, starting timing of third set time, determining whether the timing time of the second set time is up, and continuously judging whether the power supply current of the PFC circuit has oscillation phenomenon according to whether the timing time of the second set time is up; and if the accumulated signal frequency is not 1, determining whether the timing time of the third set time is up, and continuously judging whether the power supply current of the PFC circuit has oscillation phenomenon according to whether the timing time of the third set time is up.

Therefore, whether the power supply current of the PFC circuit has the oscillation phenomenon or not is continuously judged according to the accumulated signal times, whether the power supply current of the PFC circuit has the oscillation phenomenon or not can be judged under the condition of timing and counting the signal times of the received digital level signal, and the efficiency of judging whether the power supply current of the PFC circuit has the oscillation phenomenon or not is improved.

Still further optionally, the continuously determining whether the power supply current of the PFC circuit has the oscillation phenomenon according to whether the timing time of the third setting time is up may include: determining whether the timing time of the third set time is up; if the timing time of the third set time is up, determining whether the accumulated signal times is greater than a first set time and less than a second set time; if the accumulated signal times are greater than a first set time and less than a second set time, determining that the power supply current of the PFC circuit has an oscillation phenomenon; otherwise, resetting the timing time of the second set time, the timing time of the third set time and the accumulated signal times and then re-determining whether the alternating-current voltage of the PFC circuit is at the zero position; and if the timing time of the third set time is not up, continuously judging whether the power supply current of the PFC circuit has oscillation phenomenon or not according to whether the timing time of the second set time is up or not.

Therefore, whether the power supply current of the PFC circuit has the oscillation phenomenon or not can be continuously judged according to whether the timing time of the third set time is up or not, the secondary timing can be carried out after the time delay to judge whether the power supply current of the PFC circuit has the oscillation phenomenon or not, and the efficiency of judging whether the power supply current of the PFC circuit has the oscillation phenomenon or not is improved.

More optionally, the continuously determining whether the power supply current of the PFC circuit has the oscillation phenomenon according to whether the timing time of the second set time is up may include: determining whether the timing time of the second set time is up; re-determining whether the digital level signal is received or not if the timing time of the second set time is not up; and resetting the timing time of the second set time when the timing time of the second set time is up, resetting the accumulated signal times, and then re-determining whether the alternating-current voltage of the PFC circuit is at the zero position.

Therefore, whether the power supply current of the PFC circuit has the oscillation phenomenon or not can be judged by continuously judging whether the power supply current of the PFC circuit has the oscillation phenomenon or not according to whether the timing time of the second set time is up or not, timing can be carried out once after time delay to judge whether the power supply current of the PFC circuit has the oscillation phenomenon or not, and the efficiency of judging whether the power supply current of the PFC circuit has the oscillation phenomenon or not is improved.

Through a large number of tests, the technical scheme of the invention detects the oscillation signal of the power supply current and converts the oscillation signal into the digital level signal with the same frequency as the oscillation current, and then accurately identifies the power supply oscillation phenomenon by combining a software algorithm, so that the problem that the current oscillation phenomenon generated when the adjustment parameter of the PFC circuit is not matched with a power supply system can be solved, and the power supply reliability of the power supply system can be improved.

According to the embodiment of the invention, a power supply system corresponding to the current oscillation detection device of the PFC circuit is also provided. The power supply system may include: the current oscillation detection device of the PFC circuit described above.

Some variable frequency air conditioner products mainly adopt digital technology chips such as DSP/MCU to carry out PFC circuit technical scheme based on digital algorithm control, compared with the PFC scheme of the traditional analog control technology, the PFC scheme of the digital control technology can flexibly realize more efficient and lower-cost product system design in product application through a complex control algorithm. However, when the PFC circuit works, the power switching tube needs to be controlled to be turned on and off at a high frequency to realize an inductor charging and discharging process, a large switching current is generated in a power supply loop in the switching process of the power switching tube, when a power supply is unstable or the power supply capacity is not matched with PFC control adjustment parameters of a product, the power supply current is easy to oscillate when the product works, the oscillation frequency is generally 2-5 kHz, the oscillation current easily affects the operation reliability of the product, may affect the stability and reliability of a power supply system, and may even have a large effect on other electric equipment in the same power supply system network, so that only if the product timely recognizes the oscillation current, corresponding suppression control can be performed.

However, in some PFC technical solutions, due to the circuit structure and the current sampling manner, it is impossible to accurately determine whether the current power supply current oscillates through current sampling.

In an optional embodiment, the scheme of the invention provides a circuit for detecting power supply current oscillation, which can solve the problem that the current oscillation phenomenon generated when the adjustment parameter of a PFC circuit is not matched with a power supply system cannot be accurately identified, and is beneficial to improving the power supply reliability of the power supply system.

Specifically, according to the scheme of the invention, a detection circuit module (namely a detection circuit) is designed to detect the oscillation signal of the power supply current and convert the oscillation signal into a digital level signal with the same frequency as the oscillation current, and then the power supply oscillation phenomenon is accurately identified by combining a software algorithm.

Therefore, according to the scheme of the invention, the power supply current waveform is sampled, then the current waveform signal is filtered, the current oscillation signal is converted into a high-level signal capable of being digitally detected, and finally the oscillation information of the power supply current is identified by combining a software algorithm, so that the problem that the power supply current oscillation cannot be detected is solved on the whole, and the technical effect of detecting whether the product is in a normal operation state can be achieved.

In an alternative embodiment, a specific implementation process of the scheme of the present invention may be exemplarily described with reference to the examples shown in fig. 2 to fig. 9.

Fig. 2 is a schematic structural diagram of an embodiment of a circuit for detecting power supply current oscillation in the solution of the present invention. The circuit for detecting the power supply current oscillation as shown in fig. 2 should at least comprise a current sampling signal amplifying module, a detector circuit module (i.e. a detector circuit) and a power supply voltage zero-crossing detecting module, wherein the node position of a current sampling resistor (e.g. a resistor R in fig. 2) in the topology circuit should ensure that the main operation current of the product can flow through the current sampling resistor R. As shown in fig. 2, the circuit for detecting the oscillation of the power supply current may include: alternating voltage AC, rectifier bridge DB1, inductance L, diode D, electric capacity C, triode Q, resistance R, mains voltage zero passage detection module, drive module, current sampling amplifier module, detection module and MCU.

For example: the resistor R is set at a node position such that the total current input to the power supply loop flows through the resistor.

Wherein a first output terminal of the alternating voltage AC is connected to a first input terminal of the rectifier bridge DB1, and a second output terminal of the alternating voltage AC is connected to a second input terminal of the rectifier bridge DB 1. The first output end of the rectifier bridge DB1 is connected to the anode of the diode D through the inductor L, the cathode of the diode D is connected to the load, and the cathode of the diode D is grounded through the capacitor C. The second output end of the rectifier bridge DB1 is connected to the emitter of the triode Q through a resistor R, and the second output end of the rectifier bridge DB1 is further connected to the input end of the current sampling amplifying module. And the base electrode of the triode Q is connected to the output end of the driving module, and the collector electrode of the triode Q is connected to the anode of the diode D. The first output end of the current sampling amplification module is connected to the first input end of the MCU after passing through the detection module, the second output end of the current sampling amplification module is connected to the second input end of the MCU, the first output end of the MCU is connected to the input end of the driving module, and the second output end of the MCU is connected to the load. And a second input end of the alternating current voltage AC is connected to a third input end of the MCU after passing through the power voltage zero-crossing detection module.

In fig. 2, a rectifier bridge DB1 is used to rectify ac power to dc power. The inductor L is the energy storage inductor of the PFC circuit. Diode D is an isolation diode of the PFC circuit. And the triode Q is a power switch tube of the PFC circuit. The driving module is used for controlling the PFC circuit to work. The power supply voltage zero-crossing detection module is used for detecting the zero position of the current alternating voltage so as to judge the peak position of the power supply. The current sampling resistor R is used to convert the power supply current signal into a voltage signal. The current sampling amplification module is used for amplifying the voltage small signal flowing through the current sampling resistor R into a voltage signal which can be detected conveniently. The detection module is used for detecting and converting the oscillation signal component of a certain frequency band in the amplified voltage signal into a digital level signal.

In the example shown in fig. 2, the power supply voltage zero-crossing detection module detects a zero point position of the input ac voltage and transmits the zero point position to the MCU; meanwhile, the current sampling signal amplifying module converts and amplifies a current signal flowing through the current sampling resistor R to output a voltage signal which is convenient to detect, namely a voltage sampling signal, the amplified voltage sampling signal is input to the detection circuit module (namely a detection circuit), a low-pass filter circuit in the detection circuit module (namely the detection circuit) filters out high-frequency components in the voltage sampling signal, then the low-frequency component is transmitted to the comparison detection circuit to convert a low-frequency oscillation signal in the voltage sampling signal into a digital level signal with the same oscillation frequency, and finally the digital level signal is transmitted to the MCU chip, and the MCU chip identifies the digital level signal according to a preset algorithm and judges whether the current power supply current has an oscillation phenomenon.

Fig. 5 is a schematic structural diagram of an embodiment of a detector circuit module (i.e., a detector circuit) in the solution of the present invention. As shown in fig. 5, the detector circuit module may include a low-pass filter circuit and a comparison detection circuit connected in sequence.

In the scheme of the invention, the PFC circuit is generally a digital control technology PFC scheme, the circuit working mode is CCM (namely a current continuous mode), the switching frequency of a power switching tube of the PFC circuit is generally 20kHz or above, and when the PFC circuit scheme is not matched with a power supply, oscillation current with the frequency of 2-5 kHz is easily generated.

Optionally, a low-pass filter circuit in the detector circuit module (i.e., the detector circuit) in the scheme of the present invention may select a passive filter circuit scheme or an active filter circuit scheme, and simultaneously, a suitable filter frequency range may be selected according to the application requirements of a specific product scheme. The active low-pass filter circuit can also select a passive filter circuit or an active band-pass filter circuit. In the scheme of the invention, an active low-pass filter circuit composed of an operational amplifier is preferably selected, and the normal switching current frequency of a PFC circuit power switching tube in a CCM mode is generally 20kHz or more, while the abnormal oscillation current frequency is generally 2-5 kHz, so the cut-off frequency of the low-pass filter circuit is set to be 10kHz or less, thereby the abnormal oscillation current component of 2-5 kHz can be separated from the normal switching current signal of the switching tube of 20kHz or more and other unnecessary high-frequency interference signals. The role of the active filter circuit in the solution of the invention is mainly to filter out unwanted high frequency signals, so in principle the circuit gain is set close to 1.

For example: when a passive filter circuit scheme is selected or an active filter scheme is selected, a passive filter circuit can be selected under the conditions that the required filter frequency range is wide and the requirement on signal attenuation is not high; if the required filtering frequency range is narrow and the requirement is met on signal attenuation, an active filtering circuit is preferably selected; the passive filter circuit is simple, the cost is low, the difficulty of parameter type selection is high, the active filter circuit is complex, the cost is high, but the parameter type selection is simple;

for example: selecting a suitable filtering frequency range according to the application requirements of a specific product scheme can include: in practical application of different products, normal switching frequencies of PFC circuits are not completely the same, but are much higher than current oscillation frequencies, so that when a filtering frequency range is determined, a switching signal with a normal frequency is filtered, and a signal with an oscillation frequency is reserved, so that a later-stage detection can be carried out, for example, a normal switching frequency signal above 20kHz is filtered, and an oscillation frequency signal of 2-5 kHz is reserved.

As shown in fig. 5, the low pass filter circuit may include: the circuit comprises an operational amplifier U2A, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a third capacitor C3 and a fourth capacitor C4. The inverting input terminal of the operational amplifier U2A is grounded through the eighth resistor R8, and is connected to the output terminal of the operational amplifier U2A through the ninth resistor R9. The non-inverting input terminal of the operational amplifier U2A is connected to the input signal through the third capacitor C3, the seventh resistor R7 and the sixth resistor R6. The common terminal of the seventh resistor R7 and the sixth resistor R6 is connected to the output terminal of the operational amplifier U2A through the fourth capacitor C4. The output terminal of the operational amplifier U2A is connected to the comparison detection circuit.

Optionally, the comparison detecting circuit may include: the circuit comprises a comparator U1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first capacitor C1, a second capacitor C2, a first diode D1 and a second diode D2. The inverting input terminal of the comparator U1 is grounded after passing through the first capacitor C1, and is connected to the cathode of the first diode D1 after passing through the second resistor R2, and the cathode of the first diode D1 is grounded after passing through the first resistor R1. The anode of the first diode D1 is connected to the output of the low-pass filter circuit. The non-inverting input terminal of the comparator U1 is grounded through a third resistor R3, and is further connected to the cathode of the second diode D2. The anode of the second diode D2 is connected to the output of the low pass filter circuit. The output terminal of the comparator U1 is connected to the power source VCC through the fourth resistor R4, and is also connected to the signal output terminal of the comparison detection circuit through the fifth resistor R5. The signal output end of the comparison detection circuit is grounded after passing through a second capacitor C2.

The first diode D1 and the second diode D2 can isolate the positive and negative input signals of the comparator U1, and the first diode D1 and the second diode D2 preferentially select the diode with low conduction voltage drop, so that the current oscillation detection range of the signal PFC circuit can be maximally increased. The circuit composed of the first resistor R1, the second resistor R2 and the first capacitor C1 can shift the phase of the inverted input signal of the comparator U1, so that the oscillation signal is shifted in phase while the distortion of the oscillation signal is reduced as much as possible in the parameter selection, and the absolute phase difference is 30 ° or more. The parameters are selected, and have a relation with the signal frequency and amplitude, such as R1, R3 preferably 20k omega, R2 preferably 1k omega, and C1 preferably 0.033 uF. The second resistor R2 is basically the same as or similar to the first resistor R1, so that the overall voltage amplitudes of the positive and negative phase input signals of the comparator U1 are ensured to be the same. When the input signal oscillates, the positive and negative input signals of the comparator U1 are continuously crossed because the positive and negative input signals have the same amplitude and phase difference, and the cross frequency is the same as the oscillation frequency, and the comparator U1 outputs a high-low level signal with the same cross frequency, as shown in fig. 7. The crossover frequency is a frequency point at which the vibration characteristic quantity is changed from one relation to another relation, and is determined by comprehensive factors such as the use environment of the product, the capability of the vibration table and the like. The amplitude is used as a control characteristic quantity below the crossover frequency, and the acceleration is used as a control characteristic quantity above the crossover frequency. Crossing means that the positive and negative signals are crossed at a certain point, for example, the positive signal changes from 1 to 0, and the negative signal changes from 0 to 1, and at a certain time, the two signals reach 0.5 at the same time, which means that the two signals are crossed at 0.5. At each crossing point, the output signal of the comparator will have high-low level inversion, and the high level will become low level, or the low level will become high level.

Generally, based on the operating principle of the CCM mode PFC circuit, the peak or valley position of the power supply voltage is closest to the PFC output voltage, and at this time, the current oscillation phenomenon is most likely to occur, as shown in fig. 3, so that in order to more accurately and effectively identify such current oscillation phenomenon, the signal detection and judgment can be performed only near the peak or valley position of the power supply by software setting.

Fig. 4 is a control flow diagram of the oscillation current identification logic in the solution of the present invention. Referring to the examples shown in fig. 4 and 9, the control flow of the oscillation current identification logic may include:

and step 1, the MCU controls the PFC to be started.

And 2, detecting a power supply input voltage zero-crossing signal by a power supply voltage zero-crossing detection module, judging whether the detected power supply input voltage zero-crossing signal is an input voltage zero point, if so, executing the step 3, and otherwise, returning to continuously control the power supply voltage zero-crossing detection module to detect the power supply input voltage zero-crossing signal.

And 3, the detected power supply input voltage zero-crossing signal is an input voltage zero point, namely after the MCU detects the power supply voltage zero-crossing detection module trigger signal, the MCU executes a first set time T1 for delaying.

For example: as shown in fig. 3, the abnormal oscillating current applied in this kind is generally most likely to appear at the position of the power peak or trough, and by detecting the zero crossing point of the power signal and setting T1 delay, it can be realized that the detection and the judgment of the current signal are started near the position of the power peak or trough, and then by setting T2 to finish timing, it can be realized that only the detection and the judgment of the power peak or trough are performed. By limiting the detection window time, the misjudgment at other positions of the power supply cycle can be avoided, and the accuracy of detection judgment is improved. By setting the timing of T3 and the number N of times of the trigger signal, the frequency of the oscillation signal can be indirectly determined, and if T3 is 2ms and N is 6, the oscillation frequency is about 3 kHz. The timing of T2 is the detection time window of each power cycle, the timing of T3 is started when the first trigger signal is detected, the timing of T3 is not fixed relative to T1 and T2, that is, the timing of T3 may be ended before the timing of T2 is closed, or the timing may not be ended and exit is cleared, and we only make frequency judgment on the number of times of trigger signals within the timing time of T3 within the detection time window of T2.

And 4, starting to execute timing of a second set time T2 after the first set time T1 is delayed, and simultaneously starting to receive a trigger signal output by a detection circuit module (namely, a detection circuit), namely judging whether the detection circuit outputs the trigger signal or not, executing the step 5 if the detection circuit outputs the trigger signal, and executing the step 6 if the detection circuit does not output the trigger signal.

And 5, after the MCU receives the trigger signal of the detection circuit, accumulating the times of the trigger signal, and judging that if the MCU receives the trigger signal of the detection circuit for the first time, simultaneously starting to execute timing of third set time T3 until timing of the second set time T2 or the third set time T3 is finished, if the timing of the third set time T3 is finished, the MCU judges whether the received times N of the trigger signal of the detection circuit module (namely the detection circuit) accords with N2 > N > N1, if the times N accords with N2 > N > N1, the MCU judges that the power supply current has oscillation phenomenon at the moment, and returns to detect again if the times N does not accord with N1. If the trigger signal of the detection circuit is not received for the first time, whether the timing time of the third set time T3 is up or not is judged, if yes, whether the signal frequency is greater than the first set frequency n1 is judged, and if not, whether the timing time of the second set time T2 is up or not is continuously judged. If the signal frequency is greater than the first set frequency n1, continuously judging whether the signal frequency is greater than the second set frequency n2, if so, resetting the timing of the second set time T2 and the third set time T3, and resetting the accumulated signal frequency; otherwise, judging that the oscillation phenomenon exists in the power supply current at the moment. If the number of times N of the signal is less than or equal to the first set number of times N1, the timings of the second set time T2 and the third set time T3 are cleared, and the accumulated number of times of the signal is cleared.

And 6, judging whether the timing time of the second set time T2 is up, if so, counting the time of T2 and clearing, returning to the step 3, and if not, returning to continuously judge whether the detection circuit has trigger signal output.

Generally, the first setting time T1 is delayed by no more than 1/4 power source cycles, the second setting time T2 detection time window is no less than 3ms, and the third setting time T3 determination period is less than the second setting time T2 detection time window, and can be adjusted appropriately according to different power source frequencies to meet practical applications. In the technical solution of the present invention, the first setting time T1 is 4ms, the second setting time T2 is 3ms, and the third setting time T3 is 2ms for the application of the 50Hz power frequency, and the first setting time T1 is 3.5ms, the second setting time T2 is 3ms, and the third setting time T3 is 2ms for the application of the 60Hz power frequency. In general, n1 and n2 may be set according to the oscillation frequency recognized by the actual demand, and in the present embodiment, since the oscillation phenomenon is mainly recognized in the frequency range of 2 to 5kHz, n1 is set to 6 and n2 is set to 15 in advance of the third set time T3 being 2 ms.

Since the processes and functions implemented by the power supply system of this embodiment substantially correspond to the embodiments, principles, and examples of the apparatus shown in fig. 1, reference may be made to the related descriptions in the foregoing embodiments without details in the description of this embodiment.

Through a large number of tests, the technical scheme of the invention detects the oscillation signal of the power supply current by designing the detection circuit module (namely the detection circuit) and converts the oscillation signal into the digital level signal with the same frequency as the oscillation current, and then accurately identifies the power supply oscillation phenomenon by combining a software algorithm, so that the problem that the current oscillation phenomenon generated when the adjustment parameter of the PFC circuit is not matched with the power supply system can be solved, and the power supply reliability of the power supply system is improved.

According to an embodiment of the present invention, there is also provided a current oscillation detection method for a PFC circuit of a power supply system corresponding to the power supply system, as shown in fig. 10, which is a schematic flow chart of an embodiment of the method of the present invention. The current oscillation detection method of the PFC circuit of the power supply system can comprise the following steps: the method for detecting the current oscillation of the PFC circuit in the power supply system can be applied to the aspect of detecting the current oscillation of the PFC circuit in the power supply system, and can comprise the following steps: step S110 to step S140.

At step S110, a zero point position of the ac voltage of the PFC circuit is detected.

Optionally, in step S110, a specific process of detecting a sampled voltage signal of the power supply current of the PFC circuit at a zero point of the ac voltage of the PFC circuit may be referred to as the following exemplary description.

The following further describes a specific process of detecting the sampled voltage signal of the power supply current of the PFC circuit in step S110 with reference to a flowchart of an embodiment of detecting the sampled voltage signal of the power supply current of the PFC circuit in the method of the present invention shown in fig. 11, where the specific process may include: step S210 and step S220.

Step S210, converting the power supply current of the PFC circuit into a voltage signal. The node position of the current sampling resistor R in the topological circuit is to ensure that the main operation current of the product can flow through the current sampling resistor R. The current sampling resistor R may be used to convert the supply current signal into a voltage signal.

Step S220, performing amplification processing on the voltage signal to obtain the sampling voltage signal. For example: the current sampling amplifying module can be used for amplifying the voltage small signal flowing through the current sampling resistor R into a voltage signal which can be detected conveniently. The current sampling signal amplifying module converts and amplifies a current signal flowing through the current sampling resistor R to output a voltage signal convenient for detection, i.e., a voltage sampling signal, and the amplified voltage sampling signal is input to the detector circuit module (i.e., a detector circuit).

At step S120, a sampled voltage signal of a power supply current of the PFC circuit is detected at a zero point position of an alternating voltage of the PFC circuit.

At step S130, an oscillation signal in the sampled voltage signal is detected and converted into a digital level signal. For example: the detection module can be used for detecting and converting the oscillation signal component of a certain frequency band in the amplified voltage signal into a digital level signal.

Optionally, with reference to a schematic flow chart of an embodiment of the method of the present invention shown in fig. 12, which detects the oscillation signal in the sampled voltage signal and converts the oscillation signal into the digital level signal, further describing a specific process of detecting the oscillation signal in the sampled voltage signal and converting the oscillation signal into the digital level signal in step S130, the method may include: step S310 and step S320.

Step S310, filtering out the set frequency component in the sampled voltage signal, and taking the residual signal as the oscillation signal.

Step S320, converting the oscillation signal into a digital level signal with the same frequency as the set oscillation frequency.

More optionally, referring to a flowchart of an embodiment of the method of the present invention shown in fig. 13, which is used to convert the oscillation signal into a digital level signal with the same set oscillation frequency, further describing a specific process of converting the oscillation signal into a digital level signal with the same set oscillation frequency in step S320, the specific process may include: step S410 to step S430.

Step S410, isolating the input signals of the inverting input terminal and the non-inverting input terminal of the comparator to obtain a first isolated signal and a second isolated signal. For example: the first diode D1 and the second diode D2 can isolate the positive and negative input signals of the comparator U1, and the first diode D1 and the second diode D2 preferentially select the diode with low conduction voltage drop, so that the current oscillation detection range of the signal PFC circuit can be maximally improved.

Step S420, a phase shift of the set phase difference is generated in the first isolation signal, even if the oscillation signal isolated by the first isolation module generates the phase shift of the set phase difference, so as to obtain a phase shift signal.

Step S430, after the comparator compares based on the phase shift signal and the second isolation signal, outputting the digital level signal.

At step S140, it is determined whether the power supply current of the PFC circuit has an oscillation phenomenon according to the digital level signal, so as to perform suppression in time when it is determined that the power supply current of the PFC circuit has a vibration phenomenon. For example: and the MCU chip identifies the digital level signal according to a preset algorithm and judges whether the current power supply current has an oscillation phenomenon.

Optionally, with reference to a flowchart of an embodiment of determining whether the power supply current of the PFC circuit oscillates according to the digital level signal in the method shown in fig. 14, a specific process of determining whether the power supply current of the PFC circuit oscillates according to the digital level signal in step S140 may include: step S510 to step S530.

In step S510, in a case where the zero-cross detection unit detects a zero-point position of the ac voltage of the PFC circuit, that is, in a case where it is determined that the ac voltage of the PFC circuit is at the zero-point position, timing of a second set time is started after delaying the first set time, and it is determined whether the digital level signal is received.

In step S520, if the digital level signal is received within the timing time of the second set time, accumulating the signal times of the digital level signal, and continuously determining whether the power supply current of the PFC circuit has oscillation phenomenon according to the accumulated signal times.

More optionally, referring to a flowchart of an embodiment of the method shown in fig. 15, which continuously determines whether the power supply current of the PFC circuit has the oscillation phenomenon according to the accumulated signal times, further describing a specific process of continuously determining whether the power supply current of the PFC circuit has the oscillation phenomenon according to the accumulated signal times in step S520, the process may include: step S610 to step S620.

Step S610, determining whether the accumulated number of times of the signal is 1.

Step S620, if the accumulated number of times of the signal is 1, starting timing of a third set time, determining whether the timing time of the second set time is up, and continuously determining whether the power supply current of the PFC circuit has an oscillation phenomenon according to whether the timing time of the second set time is up.

Step S630, if the accumulated number of times of the signal is not 1, determining whether the timing time of the third set time is up, and continuously determining whether the power supply current of the PFC circuit has an oscillation phenomenon according to whether the timing time of the third set time is up.

Further optionally, with reference to a flowchart of an embodiment of the method shown in fig. 17, in which whether the power supply current of the PFC circuit oscillates or not is continuously determined according to whether the timing time of the third set time is up, further describing a specific process of continuously determining whether the power supply current of the PFC circuit oscillates or not according to whether the timing time of the third set time is up in step S630, the specific process may include: step S810 to step S830.

Step S810, determining whether the counted time of the third setting time is up.

Step S820, if the timing time of the third setting time is up, determining whether the accumulated signal times is greater than a first setting time and less than a second setting time; if the accumulated signal times are greater than a first set time and less than a second set time, determining that the power supply current of the PFC circuit has an oscillation phenomenon; otherwise, resetting the timing time of the second set time, the timing time of the third set time and the accumulated signal times, and then re-determining whether the alternating-current voltage of the PFC circuit is at the zero position.

In step S830, if the timing time of the third setting time is not reached, whether the power supply current of the PFC circuit oscillates is continuously determined according to whether the timing time of the second setting time is reached.

In step S530, if the digital level signal is not received within the timing time of the second setting time, it is determined whether the power supply current of the PFC circuit oscillates according to whether the timing time of the second setting time is up.

More optionally, referring to a flowchart of an embodiment of the method shown in fig. 16, in which whether the power supply current of the PFC circuit oscillates or not is continuously determined according to whether the timing time of the second set time is up, further describing a specific process of continuously determining whether the power supply current of the PFC circuit oscillates or not according to whether the timing time of the second set time is up in step S530, the specific process may include: step S710 to step S730.

Step S710, determining whether the timing time of the second setting time is up.

Step S720, re-determining whether the digital level signal is received when the second set time is not counted.

Step S730, when the counted time of the second set time has arrived, clearing the counted time of the second set time, clearing the accumulated signal times, and then re-determining whether the ac voltage of the PFC circuit is at the zero point position.

Since the processes and functions implemented by the method of the present embodiment substantially correspond to the embodiments, principles and examples of the power system, reference may be made to the related descriptions in the embodiments without being detailed in the description of the present embodiment, which is not described herein again.

Through a large number of tests, the technical scheme of the embodiment is adopted, the power supply current waveform is sampled firstly, then the current waveform signal is filtered, the current oscillation signal is converted into a high-level signal capable of being digitally detected, finally the oscillation information of the power supply current is identified by combining a software algorithm, the problem that the power supply current oscillation cannot be detected is solved on the whole, and the technical effect of detecting whether the product is in a normal operation state can be achieved.

In summary, it is readily understood by those skilled in the art that the advantageous modes described above can be freely combined and superimposed without conflict.

The above description is only an example of the present invention, and is not intended to limit the present invention, and it is obvious to those skilled in the art that various modifications and variations can be made in the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A current oscillation detection apparatus of a PFC circuit, comprising: the device comprises a zero-crossing detection unit, a current detection unit, a detection unit and a control unit; wherein,

the zero-crossing detection unit is used for detecting the zero position of the alternating voltage of the PFC circuit;

the current detection unit is used for detecting a sampling voltage signal of the power supply current of the PFC circuit at the zero point of the alternating-current voltage of the PFC circuit;

the detection unit is used for detecting an oscillation signal in the sampling voltage signal and converting the oscillation signal into a digital level signal;

the control unit is used for judging whether the power supply current of the PFC circuit has oscillation phenomenon according to the digital level signal, and comprises: under the condition that the alternating-current voltage of the PFC circuit is determined to be at the zero position, starting timing of second set time after delaying the first set time, and determining whether the digital level signal is received or not; if the digital level signal is received, accumulating the signal times of the digital level signal, and continuously judging whether the power supply current of the PFC circuit has oscillation phenomenon according to the accumulated signal times; and if the digital level signal is not received, continuously judging whether the power supply current of the PFC circuit has oscillation phenomenon or not according to whether the timing time of the second set time is up or not.

2. The current oscillation detection device of the PFC circuit of claim 1, wherein the current detection unit comprises: the device comprises a sampling module and a conversion module; wherein,

the current detection unit detects a sampling voltage signal of a power supply current of the PFC circuit, and comprises:

the sampling module is used for converting the power supply current of the PFC circuit into a voltage signal;

and the conversion module is used for amplifying the voltage signal to obtain the sampling voltage signal.

3. The current oscillation detecting apparatus of the PFC circuit of claim 1, wherein the wave detecting unit comprises: a filtering module and a comparing module; wherein,

the detection unit detects an oscillation signal in the sampling voltage signal and converts the oscillation signal into a digital level signal, and the detection unit comprises:

the filtering module is used for filtering set frequency components in the sampling voltage signal and taking the residual signal as the oscillation signal;

and the comparison module is used for converting the oscillation signal into a digital level signal with the same set oscillation frequency.

4. The current oscillation detecting apparatus of a PFC circuit of claim 3, wherein,

the filtering module includes: a low-pass filter circuit; the low-pass filter circuit comprises: an active low-pass filter circuit composed of operational amplifiers;

and/or the presence of a gas in the gas,

the comparison module comprises: the device comprises a comparator, a first isolation module, a second isolation module, a phase-shifting module and an output module; wherein,

the comparing module converts the oscillation signal into a digital level signal with the same set oscillation frequency, and comprises:

the first isolation module and the second isolation module are respectively arranged at the inverting input end and the non-inverting input end of the comparator and are used for isolating input signals of the inverting input end and the non-inverting input end of the comparator to obtain a first isolation signal and a second isolation signal;

the phase shifting module is arranged between the first isolation module and the inverting input end of the comparator and is used for enabling the first isolation signal to generate a phase shift with a set phase difference to obtain a phase shift signal;

the output module is arranged at the output end of the comparator and used for outputting the digital level signal after the comparator compares the phase shift signal with the second isolation signal.

5. The current oscillation detecting apparatus of a PFC circuit of claim 1, wherein,

continuously judging whether the power supply current of the PFC circuit has oscillation phenomenon according to the accumulated signal times, comprising the following steps:

determining whether the accumulated number of times of the signals is 1;

if the accumulated signal frequency is 1, starting timing of third set time, determining whether the timing time of the second set time is up, and continuously judging whether the power supply current of the PFC circuit has oscillation phenomenon according to whether the timing time of the second set time is up;

if the accumulated signal frequency is not 1, determining whether the timing time of the third set time is up, and continuously judging whether the power supply current of the PFC circuit has oscillation phenomenon according to whether the timing time of the third set time is up;

and/or the presence of a gas in the gas,

and continuously judging whether the power supply current of the PFC circuit has oscillation phenomenon according to whether the timing time of the second set time is up, comprising the following steps:

determining whether the timing time of the second set time is up;

re-determining whether the digital level signal is received or not if the timing time of the second set time is not up;

and resetting the timing time of the second set time when the timing time of the second set time is up, resetting the accumulated signal times, and then re-determining whether the alternating-current voltage of the PFC circuit is at the zero position.

6. The apparatus of claim 5, wherein the determining whether the power supply current of the PFC circuit oscillates according to whether the timing time of the third setting time is up further comprises:

determining whether the timing time of the third set time is up;

if the timing time of the third set time is up, determining whether the accumulated signal times is greater than a first set time and less than a second set time; if the accumulated signal times are greater than a first set time and less than a second set time, determining that the power supply current of the PFC circuit has an oscillation phenomenon; otherwise, resetting the timing time of the second set time, the timing time of the third set time and the accumulated signal times and then re-determining whether the alternating-current voltage of the PFC circuit is at the zero position;

and if the timing time of the third set time is not up, continuously judging whether the power supply current of the PFC circuit has oscillation phenomenon or not according to whether the timing time of the second set time is up or not.

7. A power supply system, comprising: the current oscillation detection device of the PFC circuit of any of claims 1 to 6.

8. A current oscillation detection method of a PFC circuit is characterized by comprising the following steps: the method comprises the following steps:

detecting the zero position of the alternating voltage of the PFC circuit;

detecting a sampling voltage signal of power supply current of the PFC circuit at the zero point of alternating voltage of the PFC circuit;

detecting an oscillation signal in the sampling voltage signal and converting the oscillation signal into a digital level signal;

judging whether the power supply current of the PFC circuit has oscillation phenomenon according to the digital level signal, comprising the following steps: under the condition that the alternating-current voltage of the PFC circuit is determined to be at the zero position, starting timing of second set time after delaying the first set time, and determining whether the digital level signal is received or not; if the digital level signal is received, accumulating the signal times of the digital level signal, and continuously judging whether the power supply current of the PFC circuit has oscillation phenomenon according to the accumulated signal times; and if the digital level signal is not received, continuously judging whether the power supply current of the PFC circuit has oscillation phenomenon or not according to whether the timing time of the second set time is up or not.

9. The method of claim 8, wherein the step of detecting the current oscillation in the PFC circuit comprises,

the detecting a sampling voltage signal of a power supply current of a PFC circuit includes:

converting the power supply current of the PFC circuit into a voltage signal;

amplifying the voltage signal to obtain the sampling voltage signal;

and/or the presence of a gas in the gas,

the detecting of the oscillation signal in the sampling voltage signal and the converting into the digital level signal includes:

filtering out set frequency components in the sampling voltage signal, and taking a residual signal as the oscillation signal;

and converting the oscillation signal into a digital level signal with the same set oscillation frequency.

10. The method of claim 9, wherein the step of detecting the current oscillation in the PFC circuit comprises the step of,

the converting the oscillation signal into a digital level signal with the same set oscillation frequency includes:

isolating input signals of an inverting input end and a non-inverting input end of the comparator to obtain a first isolation signal and a second isolation signal;

enabling the first isolation signal to generate a phase shift with a set phase difference to obtain a phase shift signal;

outputting the digital level signal after the comparator compares based on the phase shifted signal and the second isolated signal.

11. The method of claim 8, wherein the step of detecting the current oscillation in the PFC circuit comprises,

determining whether the accumulated number of times of the signals is 1;

and/or the presence of a gas in the gas,

determining whether the timing time of the second set time is up;

12. The method of claim 11, wherein determining whether the power supply current of the PFC circuit oscillates according to whether the timing time of the third setting time is up further comprises:

determining whether the timing time of the third set time is up;