CN110995220B

CN110995220B - IGBT current protection control method

Info

Publication number: CN110995220B
Application number: CN201911117031.4A
Authority: CN
Inventors: 黄宁
Original assignee: Aux Air Conditioning Co Ltd; Ningbo Aux Electric Co Ltd
Current assignee: Aux Air Conditioning Co Ltd; Ningbo Aux Electric Co Ltd
Priority date: 2019-11-15
Filing date: 2019-11-15
Publication date: 2021-12-31
Anticipated expiration: 2039-11-15
Also published as: CN110995220A

Abstract

The invention provides an IGBT current protection control method, which adopts a multiple protection mechanism for the instant current protection of an IGBT, thereby protecting devices while ensuring harmonic waves and voltage mutation. Meanwhile, PFC protection is only stopped for a short time and is not performed synchronously with compressor protection, so that the operation of the whole variable frequency air conditioner is ensured to the maximum extent. Therefore, the key devices in the PFC circuit are effectively protected, the operation of the whole PFC circuit is prevented from being influenced, and the operation reliability is improved.

Description

IGBT current protection control method

Technical Field

The invention relates to the field of air conditioning, in particular to a control method for IGBT current protection.

Background

In order to improve the Power Factor, the household variable frequency electrical appliance adopts a Power Factor Correction (PFC) circuit. The main devices include a PFC inductor, an Insulated Gate Bipolar Transistor (IGBT) and a fast recovery diode. The IGBT is a key device for correcting current waveform and improving power factor. In the actual use process, due to sudden change of input voltage or harmonic interference of an Alternating Current (AC) power supply, large Current can be generated on the IGBT, and thus the device is damaged.

Disclosure of Invention

In order to solve at least one of the above problems, an aspect of an embodiment of the present invention provides a method for controlling IGBT current protection, including sampling an ac current of an IGBT in real time, and controlling a PWM output state of the IGBT based on the ac current. Therefore, key devices in the PFC circuit are effectively protected, and the PFC circuit is low in cost and high in efficiency.

Preferably, the current control circuit includes a first current protection configured to stop the output in the current PWM period and memorize the current duty ratio when the instantaneous current of the alternating current exceeds a first current threshold V1, and to output the current PWM period while maintaining the previous PWM duty ratio in the next PWM period.

Preferably, a first trigger time of the first current protection is recorded, and when the first trigger time reaches a first time threshold, the PWM output is stopped, and the PFC output function is stopped at the same time.

Preferably, the input voltage of the IGBT is detected, a zero crossing point is judged according to the input voltage waveform, the PWM output is recovered in the next ac voltage cycle, a second trigger time for stopping the PFC output function is recorded, and when the second trigger time reaches a second time threshold, the PFC fault is reported and shutdown protection is performed.

Preferably, a second current protection is included, the second current protection being configured to stop the PWM output and simultaneously stop the PFC output function when the instantaneous current of the alternating current exceeds a second current threshold V2, wherein the first current threshold V1 is less than the second current threshold V2.

Preferably, the input voltage of the IGBT is detected, a zero crossing point is judged according to the input voltage waveform, the PWM output is recovered in the next ac voltage cycle, a third trigger time for stopping the PFC output function is recorded, and when the third trigger time reaches a third time threshold, the PFC fault is reported and shutdown protection is performed.

Preferably, the protection circuit comprises a third current protection, wherein the third current protection is configured to stop the PWM output and simultaneously stop the PFC output function when the instantaneous current of the alternating current exceeds a third current threshold V3, report the PFC fault and perform shutdown protection, wherein the second current threshold V2 is smaller than the third current threshold V3.

Another aspect of the embodiments of the present invention provides an IGBT current protection control device, including a PWM control module of an IGBT, a current sampling module of an ac current, and a PFC protection module, where the control device implements the IGBT current protection control method.

Another aspect of the embodiments of the present invention provides a computer-readable storage medium, which stores a computer program, where the computer program is read and executed by a processor, and implements the above-mentioned IGBT current protection control method.

Another aspect of an embodiment of the present invention provides an air conditioner including: the air conditioner comprises a computer readable storage medium, a processor and an IGBT current protection control device, wherein the air conditioner implements the IGBT current protection control method.

Therefore, the embodiment of the invention adopts a multiple protection mechanism for the instant current protection of the IGBT, thereby protecting the device while ensuring harmonic waves and voltage mutation. Meanwhile, PFC protection is only stopped for a short time and is not performed synchronously with compressor protection, so that the operation of the whole variable frequency air conditioner is ensured to the maximum extent. Therefore, the key devices in the PFC circuit are effectively protected, the operation of the whole PFC circuit is prevented from being influenced, and the operation reliability is improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. It should be apparent that the drawings in the following description are merely exemplary, and that other embodiments can be derived from the drawings provided by those of ordinary skill in the art without inventive effort.

Fig. 1 is a diagram of a PFC circuit according to an embodiment of the present invention;

fig. 2 is a flowchart of an IGBT current protection control method according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.

It is noted that relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element. In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

One aspect of the embodiment of the present invention provides a circuit protection method, a circuit block diagram is shown in fig. 1, a PFC circuit is a Boost type PFC circuit, and the PFC circuit mainly includes three devices, namely a PFC inductor L1, an IBGT, and a fast recovery diode D1. In order to improve the power factor, the control requires that the current waveform is as close to the voltage waveform as possible, but when the power voltage waveform has harmonic waves or voltage sudden change, the current follows the voltage waveform, so that a large current is generated on the IGBT, no effective current protection measures are provided, and the IGBT can be damaged in serious conditions.

The control device comprises a Pulse Width Modulation (PWM) control module of the IGBT, an alternating current (Iac) current sampling module and a PFC protection module.

After the PFC function is started, the PWM control module outputs a PWM signal to control the output voltage according to the normal voltage requirement. As shown in fig. 2, the instantaneous current of Iac is sampled in real time, and when the instantaneous current of Iac exceeds the software first protection current threshold value V1, the current PWM period output is stopped, and the current duty ratio is memorized. In the next PWM period, the last PWM duty is maintained for output. If the protection of the first current threshold V1 is satisfied for X1 times in succession, the PWM output is stopped, and the PFC output function is stopped at the same time. And judging a zero crossing point according to the input voltage waveform, recovering PWM (pulse width modulation) output in the next AC voltage period, and reporting PFC faults for shutdown protection if PFC output is stopped for X times continuously.

When the instantaneous current of the Iac exceeds the software second protection current threshold value V2, the PWM output is stopped, and the PFC output function is stopped. And judging a zero crossing point according to the input voltage waveform, recovering PWM output in the next AC voltage period, and reporting PFC faults for shutdown protection if PFC output is continuously stopped for X1 times.

And when the instantaneous current of the Iac exceeds the hardware protection current threshold value V3, stopping PWM output and stopping the PFC output function. Reporting PFC faults to carry out shutdown protection.

Wherein the software first protection current threshold V1 is smaller than the software second protection current threshold V2 is smaller than the hardware protection current threshold V3.

The IGBT has a high PWM output frequency of generally 15K or more, and the power supply has a frequency of 50HZ and is rectified to 100 HZ. Therefore, there are a plurality of PWM outputs in one AC voltage period, and the thresholds V1, V2, and V3 wait for how long to recover the PWM outputs after distinguishing the abnormality according to the current levels, and stop the current PWM outputs after detecting the current abnormality.

When the current exceeds the threshold value V1, the PWM output of the current period is stopped, and the output is recovered in the next PWM period. Wherein the interval time is the inverse of the output frequency. For example, 20K for 50 us.

When the current exceeds the threshold value V2, the PWM output of the current period is stopped, and the output is recovered in the next AC voltage period. Wherein the interval time is 10 ms.

And when the current exceeds a threshold value V3, stopping PWM output in the current period, reporting fault protection, and recovering output after the fault is cleared.

Therefore, the instantaneous current protection of the IGBT adopts a multiple protection mechanism, and the device is protected while harmonic waves and voltage sudden changes are ensured. Meanwhile, PFC protection is only stopped for a short time and is not performed synchronously with compressor protection, so that the operation of the whole variable frequency air conditioner is ensured to the maximum extent. Therefore, the key devices in the PFC circuit are effectively protected, the operation of the whole PFC circuit is prevented from being influenced, and the operation reliability is improved.

One aspect of the present embodiment provides an air conditioner, including a control device, where the control device includes a Pulse Width Modulation (PWM) control module of an IGBT, an alternating current (Iac) current sampling module, and a PFC protection module. Wherein the control device implements the circuit protection method.

In summary, embodiments of the present invention provide a circuit protection method, a control device and an air conditioner. The instantaneous current protection of the IGBT adopts a multiple protection mechanism, so that harmonic waves and voltage sudden change are ensured, and meanwhile, devices are protected. Meanwhile, PFC protection is only stopped for a short time and is not performed synchronously with compressor protection, so that the operation of the whole variable frequency air conditioner is ensured to the maximum extent. Therefore, the key devices in the PFC circuit are effectively protected, the operation of the whole PFC circuit is prevented from being influenced, and the operation reliability is improved.

In the embodiments provided in the present application, it should be understood that the disclosed apparatus and method can be implemented in other ways. The apparatus embodiments described above are merely illustrative, and for example, the flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

In addition, the functional modules in the embodiments of the present invention may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.

The functions, if implemented in the form of software functional modules and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.

Although the invention has been described in detail above with reference to a general description and specific examples, it will be apparent to one skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.

Claims

1. An IGBT current protection control method is characterized in that,

the alternating current of the IGBT is sampled in real time,

controlling a PWM output state of the IGBT based on the alternating current; the method specifically comprises the following steps:

comprising a first current protection, which is designed to,

when the instantaneous current of the alternating current exceeds a first current threshold value V1, stopping the current PWM period output, memorizing the current duty ratio and obtaining the current duty ratio

In the next PWM period, maintaining the last PWM duty ratio for output;

further comprising a second current protection, which is configured to,

when the instantaneous current of the alternating current exceeds a second current threshold value V2, stopping the PWM output and stopping the PFC output function,

wherein the first current threshold V1 is less than the second current threshold V2;

further comprising a third current protection, the third current protection being configured,

when the instantaneous current of the alternating current exceeds a third current threshold value V3, stopping the PWM output and the PFC output function, reporting the PFC fault and performing shutdown protection,

wherein the second current threshold V2 is smaller than the third current threshold V3.

2. The IGBT current protection control method of claim 1,

recording a first number of triggers of the first current protection,

and when the first triggering times reach a first time threshold value, stopping the PWM output and stopping the PFC output function.

3. The IGBT current protection control method of claim 2,

detecting the input voltage of the IGBT, judging a zero crossing point according to the input voltage waveform,

the PWM output is restored in the next ac voltage cycle, and,

recording the second triggering times of stopping the PFC output function,

when the second number of triggers reaches a second number threshold,

reporting the PFC fault and performing shutdown protection.

4. The IGBT current protection control method of claim 1,

the PWM output is restored in the next ac voltage cycle, and,

recording the third triggering times of stopping the PFC output function,

when the third number of triggers reaches a third number threshold,

reporting the PFC fault and performing shutdown protection.

5. An IGBT current protection control device is characterized by comprising,

the IGBT current protection control device comprises a PWM control module of the IGBT, a current sampling module of alternating current and a PFC protection module, wherein the control device implements the IGBT current protection control method according to any one of claims 1-4.

6. A computer-readable storage medium, characterized in that the computer-readable storage medium stores a computer program, which when read and executed by a processor, implements the IGBT current protection control method according to any one of claims 1 to 4.

7. An air conditioner, characterized in that the air conditioner comprises:

a computer readable storage medium, a processor, and an IGBT current protection control device,

wherein the air conditioner implements the IGBT current protection control method according to any one of claims 1 to 4.