CN216485243U - Frequency detection device and electrical equipment - Google Patents
Frequency detection device and electrical equipment Download PDFInfo
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- CN216485243U CN216485243U CN202122901681.7U CN202122901681U CN216485243U CN 216485243 U CN216485243 U CN 216485243U CN 202122901681 U CN202122901681 U CN 202122901681U CN 216485243 U CN216485243 U CN 216485243U
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Abstract
The utility model discloses a frequency detection device and electrical equipment. The frequency detection device includes: the device comprises a voltage sampling module, a duty ratio adjusting module and a main control module; the input end of the voltage sampling module is connected to three-phase power, the input end of the duty ratio adjusting module is connected to the output end of the voltage sampling module, and the output end of the duty ratio adjusting module is connected to the main control module; the voltage sampling module is used for sampling a first voltage signal and a second voltage signal in three-phase power; the duty ratio adjusting module is used for integrating the first voltage signal and the second voltage signal into a reference signal; the main control module is used for carrying out frequency detection according to the frequency and the duty ratio of the reference signal. The utility model can effectively detect the frequency change of two paths of signals, the double wave detection more accurately reflects the frequency change of three-phase electricity, the frequency detection precision is effectively improved, and the timeliness of three-phase electricity frequency protection is improved, thereby improving the use safety and stability of equipment, saving a main control port and improving the utilization rate of a chip.
Description
Technical Field
The utility model relates to the technical field of frequency detection, in particular to a frequency detection device and electrical equipment.
Background
At present, with the continuous progress and use of power electronic devices, the power utilization is more and more intelligent and diversified. The quality of the power grid directly affects the equipment safety and control logic.
For a three-phase circuit power supply system, three-phase power has phase difference, the existing power grid frequency detection is generally single-circuit frequency monitoring, namely the frequency of any phase in A, B, C is detected, and under the condition that the three-phase frequency of a power grid is inconsistent, the real power grid frequency cannot be detected, so that the frequency detection is inaccurate. And if the detection circuit detects the A phase, the burst frequency fault occurs just after the A phase frequency is detected once, and then the next frequency detection just needs one detection period, so that the three-phase power grid is not protected timely.
SUMMERY OF THE UTILITY MODEL
The embodiment of the utility model provides a frequency detection device and electrical equipment, which are used for at least solving the problems of inaccurate frequency detection and untimely frequency protection caused by single-path frequency detection in the prior art.
In order to solve the above technical problem, an embodiment of the present invention provides a frequency detection apparatus, including: the device comprises a voltage sampling module, a duty ratio adjusting module and a main control module;
the input end of the voltage sampling module is connected to three-phase power, the input end of the duty ratio adjusting module is connected to the output end of the voltage sampling module, and the output end of the duty ratio adjusting module is connected to the main control module;
the voltage sampling module is used for sampling a first voltage signal and a second voltage signal in the three-phase power;
the duty ratio adjusting module is used for integrating the first voltage signal and the second voltage signal into a reference signal;
and the main control module is used for carrying out frequency detection according to the frequency and the duty ratio of the reference signal.
Optionally, the voltage sampling module includes: a first comparator and a second comparator;
the non-inverting input end of the first comparator is connected to the first phase line through a first resistor, the inverting input end of the first comparator is connected to the second phase line through a second resistor, the output end of the first comparator is connected to the first input end of the duty ratio adjusting module, and the output end of the first comparator outputs a square wave signal corresponding to the first voltage signal;
the non-inverting input end of the second comparator is connected to the second phase line through a third resistor, the inverting input end of the second comparator is connected to the third phase line through a fourth resistor, the output end of the second comparator is connected to the second input end of the duty ratio adjusting module, and the output end of the second comparator outputs a square wave signal corresponding to the second voltage signal.
Optionally, the duty cycle adjusting module includes: the first switch tube and the second switch tube;
a first end of the first switching tube is used as a first input end of the duty ratio adjusting module, a second end of the first switching tube is connected to a power supply through a fifth resistor, and a third end of the first switching tube is connected to a second end of the second switching tube;
the first end of the second switch tube is used as the second input end of the duty ratio adjusting module, the second end of the second switch tube is connected to the third end of the second switch tube through a sixth resistor, the third end of the second switch tube is grounded, and the second end of the second switch tube is further connected to the receiving port of the main control module through a seventh resistor.
Optionally, the first switching tube is an MOS tube or a triode, and the second switching tube is an MOS tube or a triode.
Optionally, the frequency detection apparatus further includes: and the clamping circuit is connected to the output end of the duty ratio adjusting module and connected to the receiving port of the main control module.
Optionally, the clamping circuit includes: the power supply comprises a first diode and a second diode which are connected in series, wherein the anode of the first diode is connected to a power supply, the cathode of the first diode is connected to the anode of the second diode, the cathode of the second diode is grounded, and the connecting point of the first diode and the second diode is connected with the output end of the duty ratio adjusting module and the receiving port of the main control module.
Optionally, the frequency detection apparatus further includes: and the protection module is connected to the main control module and used for executing a frequency fault protection action when the frequency of the reference signal is abnormal and executing a three-phase frequency unbalance protection action when the frequency of the reference signal is normal and the duty ratio of the reference signal is abnormal.
An embodiment of the present invention further provides an electrical device, including: the frequency detection device of the embodiment of the utility model.
By applying the technical scheme of the utility model, two voltage signals in three-phase power are collected by the voltage sampling module, two voltage signals are integrated into one reference signal by the duty ratio adjusting module, the frequency change of the two signals can be effectively detected according to the frequency and the duty ratio of the reference signal, the double-wave detection more accurately reflects the frequency change of the three-phase power, the frequency detection precision and reliability are effectively improved, and the timeliness of the frequency protection of the three-phase power is improved, so that the use safety and the stability of equipment are improved, and the problems of inaccurate frequency detection and untimely frequency protection caused by single-circuit frequency detection are solved. And the duty ratio adjusting module transmits a reference signal to the main control module, and only one port of the main control module is occupied, so that the main control port is saved, and the utilization rate of a chip is improved.
Drawings
Fig. 1 is a first schematic diagram of a frequency detection apparatus according to an embodiment of the present invention;
fig. 2 is a second schematic diagram of a frequency detection apparatus according to an embodiment of the present invention;
fig. 3 is a third schematic diagram of a frequency detection apparatus provided in an embodiment of the present invention;
FIG. 4 is a schematic diagram of waveforms of output signals of comparators L1 and L2 according to an embodiment of the present invention;
fig. 5 is a flowchart of a frequency detection method provided by an embodiment of the present invention;
figure 6 is a flow chart of duplex wave check frequency detection provided by an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail with reference to the accompanying drawings, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. 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.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the utility model described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
The embodiment of the utility model provides a frequency detection device which can be used for detecting the frequency of three-phase power, for example, the frequency detection device can be suitable for detecting the frequency of a three-phase power grid or a three-phase power supply and the like, and can realize high-precision frequency detection and timely protection for the three-phase power with any frequency. As shown in fig. 1, the frequency detecting apparatus includes: the device comprises a voltage sampling module 10, a duty ratio adjusting module 20 and a main control module 30.
The input end of the voltage sampling module 10 is connected to the three-phase power, the input end of the duty ratio adjusting module 20 is connected to the output end of the voltage sampling module 10, and the output end of the duty ratio adjusting module 20 is connected to the main control module 30.
The voltage sampling module 10 is used for sampling a first voltage signal and a second voltage signal in three-phase power. The first voltage signal and the second voltage signal are voltages between two adjacent phases in a three-phase power, for example, for the abc three-phase, the first voltage signal is a voltage Ubc between the b-phase and the c-phase, and the second voltage signal is a voltage Uca between the c-phase and the a-phase, or the first voltage signal is a voltage Uab between the a-phase and the b-phase, and the second voltage signal is a voltage Ubc between the b-phase and the c-phase.
The duty ratio adjusting module 20 is configured to integrate the first voltage signal and the second voltage signal into a reference signal. The reference signal can reflect the frequency condition of three-phase power. Specifically, the voltage signal in the three-phase power is an alternating current sinusoidal signal, the voltage sampling module 10 samples the alternating current sinusoidal signal to obtain a square wave signal, and the reference signal output by the duty ratio adjusting module 20 is a rectangular wave signal.
The main control module 30 is configured to perform frequency detection according to the frequency and the duty ratio of the reference signal. The master control module 30 may be a DSP chip.
Two way voltage signal in the three-phase electricity is gathered through voltage sampling module 10 to this embodiment, it is integrated as reference signal all the way with two way voltage signal through duty ratio adjusting module 20, the frequency variation of two way signals can effectively be detected according to the frequency and the duty ratio of this reference signal, two ripples detect the frequency variation that more accurately reflects the three-phase electricity, effectively improve frequency detection precision and reliability, improve the promptness of three-phase electricity frequency protection, thereby equipment safety in utilization and stability have been improved, the problem that single-circuit frequency detection leads to the frequency to detect inaccurate and frequency protection untimely has been solved. In addition, the duty ratio adjusting module 20 transmits one path of reference signal to the main control module 30, and only one port of the main control module 30 needs to be occupied, so that the main control ports are saved, and the chip utilization rate is improved.
The voltage sampling module 10 includes: a first comparator L1 and a second comparator L2.
The non-inverting input terminal of the first comparator L1 is connected to the first phase line through a first resistor R1, the inverting input terminal of the first comparator L1 is connected to the second phase line through a second resistor R2, the output terminal of the first comparator L1 is connected to the first input terminal of the duty ratio adjusting module 20, and the output terminal of the first comparator L1 outputs a square wave signal corresponding to the first voltage signal.
The non-inverting input terminal of the second comparator L2 is connected to the second phase line through a third resistor R3, the inverting input terminal of the second comparator L2 is connected to the third phase line through a fourth resistor R4, the output terminal of the second comparator L2 is connected to the second input terminal of the duty ratio adjusting module 20, and the output terminal of the second comparator L2 outputs a square wave signal corresponding to the second voltage signal.
The first phase line, the second phase line and the third phase line are three phase lines in three-phase power respectively. For example, if the first phase line is the a-phase line, the second phase line is the b-phase line, and the third phase line is the c-phase line, the first voltage signal is Uab, and the second voltage signal is Ubc. As shown in fig. 2, the first comparator L1 outputs a square wave signal corresponding to Uab, and the second comparator L2 outputs a square wave signal corresponding to Ubc.
The resistances of the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 can be set according to actual requirements, the resistances of the first resistor R1 and the second resistor R2 are different, and the resistances of the third resistor R3 and the fourth resistor R4 are different. In practical applications, the first comparator L1 and the second comparator L2 may be comparators with identical configurations, that is, the power supply voltages of the two comparators are identical, the resistances of the first resistor R1 and the third resistor R3 are identical, and the resistances of the second resistor R2 and the fourth resistor R4 are identical.
If the value of the non-inverting input end of the comparator is larger than the value of the inverting input end, the comparator outputs a high level; if the value of the non-inverting input terminal of the comparator is smaller than the value of the inverting input terminal, the comparator outputs a low level.
In the embodiment, zero-crossing detection is realized through the first comparator L1 and the second comparator L2, and an alternating current sinusoidal signal with a certain frequency is converted into a corresponding square wave signal, so that voltage signal sampling is realized.
Referring to fig. 2, the duty cycle adjusting module 20 includes: a first switching tube G1 and a second switching tube G2.
A first terminal of the first switching tube G1 serves as a first input terminal of the duty cycle adjusting module 20, a second terminal of the first switching tube G1 is connected to the power Vcc through a fifth resistor R5, and a third terminal of the first switching tube G1 is connected to a second terminal of the second switching tube G2.
A first end of the second switching tube G2 serves as a second input end of the duty cycle adjusting module 20, a second end of the second switching tube G2 is connected to a third end of the second switching tube G2 through a sixth resistor R6, a third end of the second switching tube G2 is grounded, and a second end of the second switching tube G2 is further connected to a receiving port of the main control module 30 through a seventh resistor R7. The end connected to the main control module 30 is the output end of the duty ratio adjusting module 20. The resistance of the sixth resistor R6 is much larger than that of the fifth resistor R5.
In this embodiment, two paths of voltage signals are processed through the first switch tube G1 and the second switch tube G2, and a path of rectangular wave signal (i.e., the reference signal Uout0) is obtained and transmitted to the main control module 30, so that the frequency detection accuracy can be improved by monitoring the duty ratio and the frequency of the reference signal, frequency fault protection and three-phase frequency imbalance processing can be performed quickly, a main control interface can be saved, and the chip utilization rate can be improved.
The first switch tube G1 may be a MOS transistor or a transistor, and the second switch tube G2 may be a MOS transistor or a transistor. Specifically, the first end of the switching tube may be a base of a triode or a gate of an MOS tube; the second end of the switching tube can be a collector of the triode or a drain of the MOS tube; the third end of the switching tube can be an emitter of a triode or a source of a MOS tube.
In one embodiment, the frequency detection apparatus may further include: and the clamping circuit is connected to the output end of the duty ratio adjusting module 20 and connected to the receiving port of the main control module 30. The main control module 30 has an input voltage range requirement, and the clamp circuit is used for limiting the input voltage of the receiving port of the main control module 30, so that the voltage input to the main control module 30 is ensured not to exceed the range and be stable, and the main control module 30 is protected.
As shown in fig. 2, the clamp circuit includes: the first diode D1 and the second diode D2 are connected in series, the anode of the first diode D1 is connected to the power supply, the cathode of the first diode D1 is connected to the anode of the second diode D2, the cathode of the second diode D2 is grounded, and the connection point of the first diode D1 and the second diode D2 is connected with the output end of the duty ratio adjusting module 20 and the receiving port of the main control module 30. Of course, the clamp circuit in fig. 2 is only an example, and other devices may be used to constitute the clamp circuit.
As shown in fig. 3, the frequency detection apparatus may further include: and the protection module 40 is connected to the main control module 30 and is configured to perform a frequency fault protection action when the frequency of the reference signal is abnormal, and perform a three-phase frequency imbalance protection action when the frequency of the reference signal is normal and the duty ratio of the reference signal is abnormal. In fig. 3, the voltage sampling module 10 includes: a first voltage signal sampling unit 11 and a second voltage signal sampling unit 12, the first voltage signal sampling unit 11 being configured to sample a first voltage signal and corresponding to the first comparator L1; the second voltage signal sampling unit 12 is used for sampling a second voltage signal, and corresponds to the second comparator L2.
The reference signal corresponds to a standard frequency and a duty ratio, and may be set according to an actual condition of the detected three-phase power, for example, the standard frequency is 50Hz, and the standard duty ratio is 33.33%. In order to determine whether the frequency and the duty ratio of the reference signal are normal, a certain fluctuation is allowed on the basis of the standard frequency and the standard duty ratio to obtain a preset frequency range and a preset duty ratio range, for example, the preset frequency range is 50Hz ± 2Hz, and the preset duty ratio range is 33.33% ± 1.3%. The frequency of the reference signal is not in a preset frequency range, and the frequency of the reference signal is abnormal; the duty ratio of the reference signal is not in the preset duty ratio range, and the duty ratio of the reference signal is abnormal.
As shown in fig. 4, L1_ out represents the L1 output signal and L2_ out represents the L2 output signal.
At t1, G1 is turned on, G2 is turned off, R5 and R6 divide the voltage, R7 plays a role of limiting the current, Uout0 is Vcc × R6/(R6+ R5), R6 is much larger in resistance than R5, and Uout0 is high. For example, R5 is 1k Ω, R6 is 100k Ω, Uout0 is 3.3 × 100/101, and is approximately 3.3V, and for the main control module 30, more than 1.2V is high.
At t2, G1 and G2 are both on, Uout0 is directly connected to the 0V potential point, Uout0 output is G2 tube drop, Uout0 is approximately equal to 0V, and Uout0 is low.
At t3, G1 is turned off, G2 is turned on, and Uout0 is pulled down to ground through R6, and Uout0 is low.
At t4, G1 and G2 are both off, and Uout0 pulls down to ground through R6, and Uout0 is low.
It can be seen that the L1 output signal and the L2 output signal together form the reference signal Uout0, and Uout0 is high at t1 and low at t2, t3 and t4, regardless of the change in the waveform of the L2 output signal, as long as the frequency of the L1 output signal is determined. That is, regardless of the change in the waveform of the output signal of L2, Uout0 certainly has four periods t1 to t4, and four periods t1 to t4 constitute a cycle, which is exactly the same as the cycle of the output signal of L1. Therefore, the frequency of Uout0 is the same as the frequency of the L1 output signal, and the waveform change of the L2 output signal only affects the duty cycle of Uout 0.
For example, for a three-phase power grid, Uab and Ubc are sinusoidal signals with a certain frequency, and corresponding square wave signals are obtained through the first comparator L1 and the second comparator L2, if the power grid is normal, the output signals of L1 and L2 are square wave signals with a phase angle of 120 °, and the frequencies are both the power grid frequency, and further the standard frequency of the reference signal Uout0 is the power grid frequency, and the standard duty ratio is 33.33%, which allows certain fluctuation. Uab affects the frequency of the detected reference signal and Ubc affects the duty cycle of the detected reference signal.
If the frequency and the duty ratio of the reference signal are normal, the frequency of the first voltage signal and the frequency of the second voltage signal are normal. If the frequency of the reference signal is abnormal, the frequency of the first voltage signal is abnormal, and at this time, a frequency fault protection action can be executed. If the frequency of the reference signal is normal and the duty ratio is abnormal, the frequency of the second voltage signal is abnormal, the frequency of the three-phase power is unbalanced, and the three-phase frequency unbalance protection action can be executed at the moment.
The frequency fault protection action may include: and (4) disconnecting a main breaker connected with the three-phase power, stopping the system, and displaying frequency faults by fault codes. The three-phase frequency imbalance protection action may include: and (4) disconnecting a main breaker electrically connected with the three phases, stopping the system and reporting a fault code of unbalanced three-phase frequency.
According to the frequency and the duty ratio of the reference signal, the frequency abnormality can be effectively judged in time, the frequency is prevented from being detected in place, and corresponding protection actions are executed in time.
An embodiment of the present invention further provides an electrical device, including: the frequency detection apparatus according to the above embodiment. The frequency detection device can be applied to various power electronic frequency sampling occasions and electrical equipment, such as units like frequency converters or centrifuges, electrical equipment, automobiles and the like.
The embodiment of the utility model also provides a frequency detection method which is applied to the frequency detection device in the embodiment. The same or corresponding terms as those of the above-described embodiments are explained, and the description of the present embodiment is omitted.
Fig. 5 is a flowchart of a frequency detection method according to an embodiment of the present invention, and as shown in fig. 5, the method includes the following steps:
s501, sampling a first voltage signal and a second voltage signal in three-phase power.
S502, the first voltage signal and the second voltage signal are integrated into a reference signal.
And S503, carrying out frequency detection according to the frequency and the duty ratio of the reference signal.
The first voltage signal and the second voltage signal are voltages between two adjacent phases of the three-phase power, and the reference signal can reflect the frequency condition of the three-phase power.
According to the three-phase power supply frequency protection device, two paths of voltage signals in three-phase power are collected and integrated into one path of reference signal, frequency change of the two paths of signals can be effectively detected according to the frequency and the duty ratio of the reference signal, double-wave detection more accurately reflects frequency change of the three-phase power, frequency detection precision and reliability are effectively improved, timeliness of three-phase power frequency protection is improved, accordingly, equipment use safety and stability are improved, and the problems that frequency detection is inaccurate and frequency protection is not timely due to single-path frequency detection are solved.
The frequency detection is carried out according to the frequency and the duty ratio of the reference signal, and the method comprises the following steps: judging whether the frequency of the reference signal is in a preset frequency range or not; and if the frequency of the reference signal is not in the preset frequency range, determining that the frequency of the first voltage signal is abnormal, and executing a frequency fault protection action. Therefore, the frequency abnormity can be detected quickly and accurately, and protection is carried out in time.
The frequency detection is carried out according to the frequency and the duty ratio of the reference signal, and the method comprises the following steps: judging whether the duty ratio of the reference signal is in a preset duty ratio range or not; and if the duty ratio of the reference signal is not in the preset duty ratio range and the frequency of the reference signal is in the preset frequency range, determining that the frequency of the second voltage signal is abnormal, and executing a three-phase frequency unbalance protection action. Therefore, the frequency imbalance can be detected quickly and accurately, and protection is performed in time.
The frequency detection is carried out according to the frequency and the duty ratio of the reference signal, and the method comprises the following steps: and if the frequency of the reference signal is in the preset frequency range and the duty ratio of the reference signal is in the preset duty ratio range, determining that the frequencies of the first voltage signal and the second voltage signal are normal, and the system or the equipment operates normally.
The judging sequence of whether the frequency of the reference signal is normal and whether the duty ratio of the reference signal is normal can be set according to actual conditions, the frequency and the duty ratio can be judged at the same time, the duty ratio can be judged after the frequency is judged, and the frequency can be judged after the duty ratio is judged.
As shown in fig. 6, it is a flowchart of duplex check frequency detection, which includes the following steps:
s601, start.
And S602, detecting the power-on fault of the system.
S603, detecting whether the frequency of the reference signal is normal, if not, going to S604, and if so, going to S605.
And S604, performing frequency fault protection.
And S605, detecting whether the duty ratio of the reference signal is normal, if not, entering S606, and if so, entering S607.
And S606, performing three-phase frequency unbalance protection on the system.
And S607, the system operates normally.
And S608, ending.
According to the double-wave checking frequency detection scheme, frequency change of two paths of signals can be effectively detected through one path of signal collection, the function utilization rate of the main control chip is greatly improved, high-precision frequency detection is achieved, the frequency detection precision and the protection timeliness are improved, and the reliability of frequency detection and the safety and stability of the control device are improved. The method has the functions of checking and protecting various waveforms with different frequencies. The waveform of the reference signal Uout0 can be visually detected through an oscilloscope, and the Uout0 waveform can be monitored by inputting two paths of voltage samples, so that the duty ratio and the frequency change can be visually checked.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (8)
1. A frequency detection apparatus, comprising: the device comprises a voltage sampling module, a duty ratio adjusting module and a main control module;
the input end of the voltage sampling module is connected to three-phase power, the input end of the duty ratio adjusting module is connected to the output end of the voltage sampling module, and the output end of the duty ratio adjusting module is connected to the main control module;
the voltage sampling module is used for sampling a first voltage signal and a second voltage signal in the three-phase power;
the duty ratio adjusting module is used for integrating the first voltage signal and the second voltage signal into a reference signal;
and the main control module is used for carrying out frequency detection according to the frequency and the duty ratio of the reference signal.
2. The frequency detection device of claim 1, wherein the voltage sampling module comprises: a first comparator and a second comparator;
the non-inverting input end of the first comparator is connected to the first phase line through a first resistor, the inverting input end of the first comparator is connected to the second phase line through a second resistor, the output end of the first comparator is connected to the first input end of the duty ratio adjusting module, and the output end of the first comparator outputs a square wave signal corresponding to the first voltage signal;
the non-inverting input end of the second comparator is connected to the second phase line through a third resistor, the inverting input end of the second comparator is connected to the third phase line through a fourth resistor, the output end of the second comparator is connected to the second input end of the duty ratio adjusting module, and the output end of the second comparator outputs a square wave signal corresponding to the second voltage signal.
3. The frequency detection apparatus of claim 1, wherein the duty cycle adjustment module comprises: the first switch tube and the second switch tube;
a first end of the first switching tube is used as a first input end of the duty ratio adjusting module, a second end of the first switching tube is connected to a power supply through a fifth resistor, and a third end of the first switching tube is connected to a second end of the second switching tube;
the first end of the second switch tube is used as the second input end of the duty ratio adjusting module, the second end of the second switch tube is connected to the third end of the second switch tube through a sixth resistor, the third end of the second switch tube is grounded, and the second end of the second switch tube is further connected to the receiving port of the main control module through a seventh resistor.
4. The frequency detection device according to claim 3, wherein the first switch tube is a MOS tube or a triode, and the second switch tube is a MOS tube or a triode.
5. The frequency detection device according to claim 1, further comprising: and the clamping circuit is connected to the output end of the duty ratio adjusting module and connected to the receiving port of the main control module.
6. The frequency detection device of claim 5, wherein the clamp circuit comprises: the power supply comprises a first diode and a second diode which are connected in series, wherein the anode of the first diode is connected to a power supply, the cathode of the first diode is connected to the anode of the second diode, the cathode of the second diode is grounded, and the connecting point of the first diode and the second diode is connected with the output end of the duty ratio adjusting module and the receiving port of the main control module.
7. The frequency detecting device according to any one of claims 1 to 6, characterized by further comprising:
and the protection module is connected to the main control module and used for executing a frequency fault protection action when the frequency of the reference signal is abnormal and executing a three-phase frequency unbalance protection action when the frequency of the reference signal is normal and the duty ratio of the reference signal is abnormal.
8. An electrical device, comprising: the frequency detection device of any one of claims 1 to 7.
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| CN202122901681.7U CN216485243U (en) | 2021-11-24 | 2021-11-24 | Frequency detection device and electrical equipment |
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| CN202122901681.7U CN216485243U (en) | 2021-11-24 | 2021-11-24 | Frequency detection device and electrical equipment |
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| CN216485243U true CN216485243U (en) | 2022-05-10 |
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