Protection method and device for IGBT, frequency converter, air conditioner, medium and product

Abstract

The application belongs to the technical field of power electronic systems, and discloses an IGBT protection method, device, frequency converter, air conditioner, storage medium and computer program product, which are applied to protecting IGBT based on the power voltage of the device where the IGBT is located; the method comprises the following steps: continuously sampling the AC voltage signal of the device at a set sampling frequency within a set sampling time to obtain the power voltage of the device; determining whether the preset low-voltage reset function needs to be started according to the power voltage of the device obtained by continuous sampling within the set sampling time; if it is determined that the preset low-voltage reset function needs to be started, the preset low-voltage reset function is started to protect the driving signal of the IGBT. According to the scheme, the voltage detection value of the low voltage in the power system is subjected to optimized operation, and whether the preset low-voltage protection mechanism is triggered is determined based on the optimized operation result, so as to protect the IGBT and improve the safety of the IGBT.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of power electronic systems, and particularly relates to an IGBT protection method and device, a frequency converter, an air conditioner, a storage medium and a computer program product, in particular to a low-voltage detection and IGBT protection method and device, a frequency converter, an air conditioner, a storage medium and a computer program product. BACKGROUND

[0002] In modern power electronic systems, Insulate Gate Bipolar Transistor (IGBT) is widely used in new energy power generation, electric vehicles, industrial frequency converters and other fields as a high-efficiency and fast power semiconductor device. The normal operation of IGBT is crucial to the stability and reliability of the entire system. However, the inevitable low voltage phenomenon in the power system can pose a serious threat to IGBT and affect the safety of IGBT.

[0003] The above content is only used to assist in understanding the technical solutions of the present application and does not represent the acknowledgement of the above content as prior art. SUMMARY

[0004] The purpose of the present application is to provide an IGBT protection method, device, frequency converter, air conditioner, storage medium and computer program product to solve the problem of low voltage phenomenon in the power system which can pose a serious threat to IGBT and affect the safety of IGBT, achieve the effect of optimizing the operation of the voltage detection value of the low voltage in the power system (such as the voltage detection value of the air conditioner power supply voltage), determining whether to trigger the preset low voltage protection mechanism based on the optimization operation result, protecting the IGBT and improving the safety of the IGBT.

[0005] The present application provides an IGBT protection method applied to protecting the IGBT based on the power supply voltage of the device where the IGBT is located; the IGBT protection method comprises: continuously sampling the AC voltage signal of the device at a set sampling frequency within a set sampling time to obtain the power supply voltage of the device; according to the power supply voltage of the device obtained by continuous sampling within the set sampling time, integrating and summing the voltage detection value of the power supply voltage of the device where the IGBT is located at a set integral proportion coefficient to realize optimization operation, determining whether to start the preset low voltage reset function based on the optimization operation result; if it is determined that the preset low voltage reset function needs to be started, the preset low voltage reset function is started to protect the driving signal of the IGBT.

[0006] In some embodiments, the sampling of the AC voltage signal of the device at a set sampling frequency within a set sampling time to obtain the power supply voltage of the device comprises: adjusting the AC voltage signal of the device to a preset input voltage range of an ADC module to obtain an AC adjusted voltage of the device; and sampling the AC adjusted voltage of the device at the set sampling frequency within the set sampling time by using the preset ADC module to obtain the power supply voltage of the device.

[0007] In some embodiments, the integral summation of the voltage detection value of the power supply voltage of the device in which the IGBT is located at a set integral proportion coefficient to achieve an optimization operation based on the power supply voltage of the device sampled continuously within a set sampling time comprises: integral summation of the power supply voltage of the device obtained continuously within the set sampling time at the set integral proportion coefficient to obtain an integral value of the power supply voltage of the device; determining whether the integral value of the power supply voltage of the device is less than a set threshold value; and determining that the preset low-voltage reset function needs to be started if the integral value of the power supply voltage of the device is determined to be less than the set threshold value.

[0008] In some embodiments, the starting of the preset low-voltage reset function to protect the drive signal of the IGBT comprises: starting the preset low-voltage reset function to start a preset low-voltage protection mechanism and cutting off the drive signal of the IGBT.

[0009] In some embodiments, it further comprises: determining whether the power supply voltage of the device has returned to a preset normal voltage range after a set reset time when the preset low-voltage reset function has been started; and closing the preset low-voltage reset function to control the device to restart and run if it is determined that the power supply voltage of the device has returned to the preset normal voltage range.

[0010] According to the method, the application provides an IGBT protection device for protecting an IGBT based on a power supply voltage of a device in which the IGBT is located. The IGBT protection device comprises a sampling unit configured to continuously sample an AC voltage signal of the device at a set sampling frequency within a set sampling time to obtain a power supply voltage of the device; and a control unit configured to integrate a voltage detection value of the power supply voltage of the device in which the IGBT is located at a set integral proportion coefficient based on the power supply voltage of the device continuously sampled within the set sampling time to perform an optimization operation, and determine whether the preset low-voltage reset function needs to be started based on a result of the optimization operation. The control unit is further configured to start the preset low-voltage reset function to protect a driving signal of the IGBT if it is determined that the preset low-voltage reset function needs to be started.

[0011] In some embodiments, the sampling unit is configured to continuously sample an AC voltage signal of the device at a set sampling frequency within a set sampling time to obtain a power supply voltage of the device, including adjusting the AC voltage signal of the device to be within a preset input voltage range of an ADC module to obtain an AC adjusted voltage of the device, and continuously sampling the AC adjusted voltage of the device at the set sampling frequency within the set sampling time by using the preset ADC module to obtain the power supply voltage of the device.

[0012] In some embodiments, the control unit is configured to integrate a voltage detection value of the power supply voltage of the device in which the IGBT is located at a set integral proportion coefficient based on the power supply voltage of the device continuously sampled within the set sampling time to perform an optimization operation, and determine whether the preset low-voltage reset function needs to be started based on a result of the optimization operation, including integrating the power supply voltage of the device continuously obtained within the set sampling time at the set integral proportion coefficient to obtain an integral value of the power supply voltage of the device, determining whether the integral value of the power supply voltage of the device is less than a set threshold value, and determining that the preset low-voltage reset function needs to be started if it is determined that the integral value of the power supply voltage of the device is less than the set threshold value.

[0013] In some embodiments, the control unit is configured to start the preset low-voltage reset function to protect a driving signal of the IGBT, including starting the preset low-voltage reset function to start a preset low-voltage protection mechanism and simultaneously cutting off the driving signal of the IGBT.

[0014] In some embodiments, the control unit is further configured to, in the case that the preset low-voltage reset function has been turned on, determine whether the power supply voltage of the device returns to the preset normal voltage range after a set reset time; and the control unit is further configured to, in the case that it is determined that the power supply voltage of the device has returned to the preset normal voltage range, turn off the preset low-voltage reset function to control the device to restart and run.

[0015] In another aspect, the present application provides a frequency converter, comprising the IGBT protection device described above.

[0016] In another aspect, the present application provides an air conditioner, comprising the IGBT protection device described above, or the frequency converter described above.

[0017] In another aspect, the present application provides a storage medium, comprising a stored program, wherein the program controls the device in which the storage medium is located to perform the steps of the IGBT protection method described above when the program is executed.

[0018] In another aspect, the present application provides a computer program product, comprising a computer program which, when executed by a processor, implements the steps of the IGBT protection method described above.

[0019] Therefore, the scheme of the present application, for the IGBT in a device (such as an air conditioner frequency converter), in the case that the device is running, detects the power supply voltage of the device at a set sampling frequency (such as sampling frequency m) within a continuous set time (such as sampling time a); integrates and sums the power supply voltage of the device detected within the continuous set time (such as sampling time a) according to a set integral coefficient (such as integral comparison coefficient b) to obtain the integral value of the power supply voltage of the device detected within the continuous set time (such as sampling time a); compares the integral value of the power supply voltage of the device with a set threshold value (such as threshold value c), and in the case that the integral value of the power supply voltage of the device is less than the set threshold value (such as threshold value c), triggers a preset low-voltage protection mechanism to cut off the driving signal of the IGBT to disconnect the switching signal of the IGBT; until in the case that the integral value of the power supply voltage of the device is greater than or equal to the set threshold value (such as threshold value c), the preset low-voltage protection mechanism is released to reset the IGBT to make the device restart and run; thereby, through optimized operation on the voltage detection value of the power supply voltage (such as the air conditioner power supply voltage) of the device in which the IGBT is located, it is determined whether to trigger the preset low-voltage protection mechanism based on the optimized operation result to protect the IGBT and improve the safety of the IGBT.

[0020] Other features and advantages of the present application will be set forth in the following description, and in part will be apparent from the description, or can be learned by practice of the application.

[0021] The technical solutions of the present application are described in further detail below with the help of the accompanying drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 Flowchart of an embodiment of the method for protecting IGBTs of the present application;

[0023] Figure 2 Flowchart of an embodiment of the method for continuously sampling the AC voltage signal of the device at a set sampling time in the method of the present application;

[0024] Figure 3 Flowchart of an embodiment of the method for determining whether the preset low-voltage reset function needs to be turned on in the method of the present application;

[0025] Figure 4 Flowchart of an embodiment of the method for turning off the preset low-voltage reset function in the method of the present application;

[0026] Figure 5 Structural diagram of an embodiment of the protection device for IGBTs of the present application;

[0027] Figure 6 Waveform diagram of the driving IGBT signal in the reset process;

[0028] Figure 7 Structural diagram of the main chip controlling the IGBT circuit;

[0029] Figure 8 Flowchart of the main program logic.

[0030] In combination with the accompanying drawings, the reference signs in the embodiments of the present application are as follows:

[0031] 102 - sampling unit; 104 - control unit. DETAILED DESCRIPTION

[0032] In order to make the objectives, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described in detail below with the help of specific embodiments of the present application and corresponding drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0033] Considering that the low voltage phenomenon in the power system will pose a serious threat to the IGBT, affecting the safety of the IGBT, such as causing the device to overcurrent, overheat or even permanent damage, thereby triggering system failure.

[0034] The low voltage phenomenon is usually caused by factors such as grid fluctuation, load mutation, short circuit fault or system switching. Under the low voltage working condition, the switching characteristics of the IGBT will change significantly, causing an increase in current stress and thermal stress. If protective measures are not taken in time, the IGBT may be out of control or breakdown, causing equipment damage and system downtime. Therefore, how to accurately detect the low voltage state and take effective protection measures has become a key problem in the design of power electronic systems.

[0035] The low voltage protection method in the related scheme mainly relies on a simple voltage threshold judgment, that is, by comparing the power supply voltage sampling value with the set threshold voltage, such as directly comparing the AC (i.e. alternating current) sampling voltage with the set threshold, if the AC sampling voltage is less than the set threshold, the reset is started. However, this method has the problems of slow response speed, low detection accuracy, and single protection strategy. In actual application, the complex grid environment and dynamic changing load conditions make the low voltage detection more difficult. At the same time, it is found through continuous experiments that since the switching signal for driving the IGBT is a closed-loop control, when the voltage continues to decrease, the time of IGBT conduction will continue to increase due to the feedback effect of the closed-loop control, which has great safety hazards. In summary, the protection of the IGBT needs to consider multiple factors such as its working state, environmental temperature, current stress, etc., and it is difficult to achieve comprehensive protection by relying solely on voltage detection.

[0036] Therefore, in view of the above-mentioned situation that the IGBT is prone to overheat and overcurrent damage under voltage mutation, and the situation of continuous long-time conduction due to closed-loop control, the scheme of the present application proposes an IGBT protection method, specifically a low voltage detection and IGBT protection method, which can cope with different voltage changes and reset in time to prevent IGBT damage.

[0037] According to an embodiment of the present application, an IGBT protection method is provided, as shown in Figure 1 The flowchart of an embodiment of the method of the present application. The IGBT protection method is applied to protect the IGBT based on the power supply voltage of the device where the IGBT is located; in the scheme of the present application, as shown in Figure 1 The IGBT protection method comprises steps S110 to S130.

[0038] At step S110, the AC voltage signal of the device is continuously sampled at a set sampling frequency within a set sampling time to obtain the power supply voltage of the device.

[0039] At step S120, the voltage detection value of the power supply voltage of the device where the IGBT is located is integrated at a set integral proportion coefficient based on the power supply voltage of the device continuously sampled within the set sampling time to achieve optimization operation, and whether the preset low-voltage reset function needs to be started is determined based on the optimization operation result.

[0040] At step S130, if it is determined that the preset low-voltage reset function needs to be started, the preset low-voltage reset function is started to protect the driving signal of the IGBT.

[0041] The improved low-voltage reset detection scheme (i.e., low-voltage detection and IGBT protection scheme) provided by the scheme of the application further optimizes the control logic of the IGBT on the basis of the threshold detection algorithm in the optimization related scheme. By implementing the lock protection strategy for the IGBT during the chip reset process, not only the problem of accidental power failure caused by improper threshold setting is avoided, but also the anti-interference ability of the system under the condition of voltage mutation is significantly improved. At the same time, the output of the IGBT is forcibly turned off within the reset time, which can reduce the risk caused by the continuous conduction of the IGBT due to the closed loop, so as to better protect the IGBT from damage, cope with different voltage change conditions, reset in time to prevent IGBT damage and improve the reliability of the air conditioner mainboard.

[0042] In some embodiments, the specific process of continuously sampling the AC voltage signal of the device at a set sampling frequency within a set sampling time to obtain the power supply voltage of the device in step S110 is described in the following exemplary description.

[0043] The following will be further described in combination with Figure 2 The embodiment flowchart of continuously sampling the AC voltage signal of the device within a set sampling time in the method of the application shown in FIG. 10 further illustrates the specific process of continuously sampling the AC voltage signal of the device within a set sampling time in step S110, which includes steps S210 to S220.

[0044] In step S210, the AC voltage signal of the device is adjusted to the input voltage range of the preset ADC module to obtain the AC adjusted voltage of the device.

[0045] In step S220, the AC adjusted voltage of the device is continuously sampled by the preset ADC module at a set sampling frequency within a set sampling time to obtain the power supply voltage of the device.

[0046] Figure 7 The structure diagram of the IGBT circuit controlled by the main chip. Figure 7 As shown in the figure, the scheme of the present application designs a low-voltage detection protection system for detecting whether the air conditioner power voltage is lower than the safe working range, and triggering the protection mechanism when low voltage is detected, cutting off the driving signal of IGBT to prevent equipment damage caused by low voltage. The system is composed of a voltage sampling module, a main chip module and an IGBT driving module. Among them, the main chip module is like a microcontroller (MCU), and the MCU is responsible for implementing signal processing and output control logic.

[0047] As shown in the figure, Figure 7 The output end of the MCU outputs a pulse width modulation (PWM) signal to the driving module, and the driving signal output by the driving module is output to the gate G of the IGBT after passing through the resistor R1; the collector C of the IGBT is connected to the anode of the diode D1, and the cathode of the diode D1 is connected to the ground through the capacitor C1. The emitter of the IGBT is connected to the ground through the resistor Rs. The ground end of the MCU is grounded, and the input end of the MCU receives the air conditioner power voltage sampled by the voltage sampling module from the common end between the capacitor C1 and the cathode of the diode D1. The diode D1 plays a role in freewheeling protection, and when the IGBT is off, the capacitor C1 will store energy. If the IGBT is on at this time, the diode D1 can be forward biased to reduce the voltage to avoid the capacitor C1 being directly connected to the ground and thus being burned out.

[0048] In the example shown in the figure, Figure 7 The voltage sampling module: mainly used for collecting rectified DC voltage signals, and realizing linear adjustment of voltage amplitude through a precision resistor voltage dividing network. The voltage sampling module includes an RC low-pass filter circuit (i.e. a resistance-capacitance filter circuit), which effectively eliminates high-frequency interference signals and improves sampling accuracy. The filtered voltage signal is then transmitted to the MCU for subsequent processing to ensure that the system obtains high-quality voltage data. The resistor voltage dividing network is generally a series of resistors connected in series for voltage division, which facilitates sampling by the main chip. A potentiometer is included in the voltage dividing network, which can be adjusted by adjusting the angle of the potentiometer to linearly adjust the voltage. Among them, the sampled AC voltage is a DC voltage after rectification by the rectifier bridge.

[0049] The scheme of the present application combines high-precision voltage sampling, fast signal processing and reliable protection mechanism, and provides an important guarantee for the safe operation of the air conditioner system.

[0050] In some embodiments, the voltage detection value of the power supply voltage of the device where the IGBT is located is integrated with a set integral proportion coefficient to achieve an optimization operation according to the power supply voltage of the device obtained by continuous sampling within a set sampling time, and the specific process of determining whether the preset low-voltage reset function needs to be started based on the optimization operation result is described below with reference to the exemplary description.

[0051] The specific process of determining whether the preset low-voltage reset function needs to be started in step S120 is further described below with reference to the embodiment flowchart of determining whether the preset low-voltage reset function needs to be started in the method of the application shown in Figure 3 The specific process of determining whether the preset low-voltage reset function needs to be started in step S120 is further described below with reference to the embodiment flowchart of determining whether the preset low-voltage reset function needs to be started in the method of the application shown in

[0052] In step S310, the integral value of the power supply voltage of the device is obtained by integrating the power supply voltage of the device obtained by continuous acquisition within a set sampling time with a set integral proportion coefficient; wherein the set integral proportion coefficient is, for example, coefficient b.

[0053] In step S320, it is determined whether the integral value of the power supply voltage of the device is less than a set threshold value; wherein the set threshold value is, for example, threshold value c.

[0054] In step S330, if it is determined that the integral value of the power supply voltage of the device is less than the set threshold value, it is determined that the preset low-voltage reset function needs to be started.

[0055] Figure 8 The flowchart of the main program logic is shown in FIG. 1. As shown in Figure 8 The low-voltage detection and IGBT protection method proposed by the application includes the following steps:

[0056] In step 1, the voltage sampling module collects the AC voltage, and then step 2 is performed.

[0057] In step 1, the sampling frequency is set to m and the sampling time is set to a. m is generally 10 kHz to 40 kHz, and a is generally 10 ms to 40 ms.

[0058] Continuous AC voltage detection: a high-speed analog-to-digital converter (ADC) is used to sample the AC voltage signal from the power grid. Before sampling, the AC voltage signal is adjusted by a voltage sampling module (such as a resistance divider network) to ensure that the input voltage is within the input range of the ADC.

[0059] In step 2, the AC voltage collected within a time a is continuously operated, and then step 3 is performed.

[0060] Threshold calculation and comparison: voltage normal cycle sampling, the sampling value integral is about b*AC voltage effective value. Set threshold c as the threshold of b*AC voltage effective value (c is b*AC effective value, and c is called threshold). The integral value is calculated by integrating and summing the sampling values in continuous a time. B is the integral comparison coefficient, and the range is 0~1.

[0061] The AC voltage collected in a time is continuously operated, and specifically, the total sum of continuous operation is n, the AC sampling value is Kt each time, t=1, 2, 3,..., ma, and ma is the total sampling number. N=1 / m*K1+1 / m*K2+...+1 / m*Kma.

[0062] Step 3, judge whether the running voltage sampling value is less than the set threshold c: if yes, execute step 4, otherwise return to step 1.

[0063] In step 3, the integral sum result obtained by integrating and summing the sampling values in continuous a time is compared with the set threshold c: if the integral sum result is less than the set threshold c, the low voltage protection mechanism is triggered; otherwise, continue normal operation. C is a set threshold range of 100V~200V.

[0064] The scheme of the application is that the power supply voltage of the device is continuously sampled in the set sampling time, the voltage detection value of the power supply voltage of the device where the IGBT is located is integrated and summed according to the set integral proportion coefficient to realize optimized operation, whether the preset low voltage reset function needs to be started is determined based on the optimized operation result, the protection mechanism can be triggered quickly when low voltage is detected, the driving signal of the IGBT is cut off, and the damage of the device caused by low voltage is prevented.

[0065] In some embodiments, the preset low voltage reset function is started in step S130 to protect the driving signal of the IGBT, including: starting the preset low voltage reset function to start the preset low voltage protection mechanism, and cutting off the driving signal of the IGBT.

[0066] As shown in Figure 8 The low voltage detection and IGBT protection method proposed by the scheme of the application further includes: step 4, starting low voltage reset, cutting off the IGBT switch signal, and then executing step 5.

[0067] In step 4, when the low voltage protection mechanism is triggered: through the control logic module, the reset command is executed, the whole system is reset after time d, and then the air conditioner compressor and other loads stop running. At the same time of triggering the low voltage protection mechanism, the MCU immediately cuts off the signal output to the IGBT driving module to prevent it from continuing to work in the low voltage state. At the same time, the buzzer gives a low voltage warning to warn the user. D is generally 13ms.

[0068] In which, the reset is specifically: after the low voltage detection mentioned above is executed, the reset pin output is pulled low after the reset condition is met, and then the reset is started, the CPU clears the register, resets the counter, initializes the peripheral module (i.e. load), etc.

[0069] The low voltage reset and the main chip are set to low level according to the software running logic reset pin, so as to reset. The initialization peripheral, all loads are turned off to prevent abnormal voltage from damaging the load. The low voltage protection mechanism is the protection scheme of the IGBT proposed by the scheme of the application, and the main chip cuts off the driving signal of the IGBT output by the MCU at the same time of low voltage reset.

[0070] The scheme of the application proposes a low voltage reset detection scheme (i.e. low voltage detection and IGBT protection scheme), which optimizes the operation according to the voltage detection value of the power supply voltage (such as the air conditioner power supply voltage) of the device where the IGBT is located, compares and analyzes the operation result with the set value, judges whether the low voltage reset needs to be started, and at the same time locks the switch signal input of the IGBT after starting the reset, reduces the influence of closed loop control on the conduction state of the IGBT, so as to achieve the purpose of protecting the IGBT.

[0071] Figure 6 The waveform diagram of the driving IGBT signal in the reset process. Figure 6 In which, the green color represents the voltage between the C poles of the IGBT, the blue color represents the chip reset pin signal, the yellow color represents the CE pole current of the IGBT, and the pink color represents the signal of driving the IGBT switch. The IGBT driving signal (the signal represented by red color) has a long time high level at last, which will cause the IGBT to be continuously turned on, and the risk of IGBT damage is very high.

[0072] In some embodiments, the IGBT protection method of the scheme of the application further includes: a process of closing the preset low voltage reset function.

[0073] The following will be combined Figure 4 The embodiment flowchart of the process of closing the preset low voltage reset function in the method of the application is shown in the figure, which further illustrates the specific process of closing the preset low voltage reset function, including: step S410 to step S420.

[0074] Step S410, in the case that the preset low voltage reset function has been started, after the set reset time (such as time d), it is determined whether the power supply voltage of the device returns to the preset normal voltage range; wherein, the set reset time is, for example, time d.

[0075] Step S420, if it is determined that the power supply voltage of the device has recovered to the preset normal voltage range, the preset low voltage reset function is closed to control the device to restart and run.

[0076] As shown in Figure 8 The scheme of the present application proposes a low voltage detection and IGBT protection method, which further comprises:

[0077] Step 5, after resetting successfully at time d, continue to detect the AC voltage, and judge whether the AC voltage has recovered to normal: if yes, restart the compressor, otherwise return to step 1.

[0078] Referring to Figure 7 and Figure 8 The MCU will immediately trigger the low voltage protection mechanism to cut off the control driving signal (such as PWM signal) when detecting that the voltage value meets the reset condition, so that the driving module stops outputting, and then the switch signal of the IGBT is disconnected. In this state, the system will continue to monitor the power supply voltage state and wait for it to recover to the safe working range. Once it is detected that the power supply voltage has recovered to the normal working range, the system will automatically release the protection state, complete the reset operation, and restart the system operation. The detected voltage value is the voltage value obtained after sampling and operation. The voltage value after sampling and operation is compared with the set threshold value, if the voltage value after sampling and operation is less than the set threshold value, the main chip actively resets, triggers the low voltage protection to cut off the PWM output, so that the IGBT is continuously turned off during the reset; if the PWM is not cut off, the control IGBT pin signal will continuously output high level during the main chip reset, causing the IGBT to continuously conduct, and if there is a large current signal (air conditioner suddenly starts) at this time, the IGBT is easy to burn out.

[0079] In the scheme of the present application, the protection mode is to judge whether the AC current exceeds the threshold + forcibly turn off the IGBT control signal during the reset period; the detection mode is to continuously sample the DC bus voltage, compare the sampled data with the set threshold value, and open the low voltage reset if the condition is met. Through the above implementation scheme, the air conditioner low voltage detection protection system can quickly trigger the protection mechanism to cut off the driving signal of the IGBT when detecting low voltage, preventing the device from being damaged due to low voltage. At the same time, the system can automatically detect voltage recovery and restart the air conditioner after the voltage recovers to normal, ensuring the stable operation of the system.

[0080] The technical scheme of the embodiment is adopted, the IGBT in the equipment (such as an air conditioner frequency converter) is detected at a set sampling frequency (such as a sampling frequency m) in a continuous set time (such as a sampling time a) under the condition that the equipment is running; the integral value of the power supply voltage of the equipment detected in the continuous set time (such as the sampling time a) is obtained by integrating and summing the power supply voltage of the equipment detected in the continuous set time (such as the sampling time a) according to a set integral coefficient (such as an integral comparison coefficient b); the integral value of the power supply voltage of the equipment is compared with a set threshold value (such as a threshold value c), and the preset low-voltage protection mechanism is triggered under the condition that the integral value of the power supply voltage of the equipment is less than the set threshold value (such as the threshold value c), the driving signal of the IGBT is cut off, and the switching signal of the IGBT is disconnected; until under the condition that the integral value of the power supply voltage of the equipment is greater than or equal to the set threshold value (such as the threshold value c), the preset low-voltage protection mechanism is released, the IGBT is reset, and the equipment is restarted and runs; thereby, the voltage detection value of the power supply voltage (such as the air conditioner power supply voltage) of the equipment where the IGBT is located is optimized and operated, and whether the preset low-voltage protection mechanism is triggered is determined based on the optimization operation result, so as to protect the IGBT and improve the safety of the IGBT.

[0081] According to the embodiment of the application, an IGBT protection device corresponding to the protection method of the IGBT is also provided. Referring to Figure 5 The structure schematic diagram of an embodiment of the device of the application is shown. The IGBT protection device is applied to protecting the IGBT based on the power supply voltage of the equipment where the IGBT is located; in the scheme of the application, as Figure 5 The IGBT protection device includes a sampling unit 102 and a control unit 104.

[0082] The sampling unit 102 is configured to continuously sample the AC voltage signal of the equipment at a set sampling frequency in a set sampling time to obtain the power supply voltage of the equipment; the set sampling frequency is, for example, the frequency m, and the set sampling time is, for example, the time a. The specific functions and processes of the sampling unit 102 are described with reference to step S110.

[0083] The control unit 104 is configured to integrate and sum the voltage detection value of the power supply voltage of the equipment where the IGBT is located according to the power supply voltage of the equipment continuously sampled in the set sampling time to realize optimization operation, and determine whether the preset low-voltage reset function needs to be started based on the optimization operation result. The specific functions and processes of the control unit 104 are described with reference to step S120.

[0084] The control unit 104 is further configured to start the preset low-voltage reset function to protect the driving signal of the IGBT if it is determined that the preset low-voltage reset function needs to be started. The specific functions and processes of the control unit 104 are also described in step S130.

[0085] The improved low-voltage reset detection scheme (i.e., the low-voltage detection and IGBT protection scheme) provided by the scheme of the present application further optimizes the control logic of the IGBT on the basis of optimizing the threshold detection algorithm in the related scheme. By implementing the lock protection strategy for the IGBT during the chip reset process, not only the problem of unexpected power failure caused by improper threshold setting is avoided, but also the anti-interference ability of the system under the condition of voltage mutation is significantly improved. At the same time, the output of the IGBT is forcibly turned off within the reset time, which can reduce the risk of continuous conduction of the IGBT due to closed loop, thereby better protecting the IGBT from damage to cope with different voltage changes, reset in time to prevent IGBT damage and improve the reliability of the air conditioner mainboard.

[0086] In some embodiments, the sampling unit 102 continuously samples the AC voltage signal of the device at a set sampling frequency within a set sampling time to obtain the power voltage of the device, including:

[0087] The sampling unit 102 is specifically further configured to adjust the AC voltage signal of the device to the input voltage range of the preset ADC module to obtain the AC adjusted voltage of the device. The specific functions and processes of the sampling unit 102 are also described in step S210.

[0088] The sampling unit 102 is specifically further configured to use the preset ADC module to continuously sample the AC adjusted voltage of the device at a set sampling frequency within a set sampling time to obtain the power voltage of the device. The specific functions and processes of the sampling unit 102 are also described in step S220.

[0089] Figure 7 The structure diagram of the main chip controlling the IGBT circuit. As shown in Figure 7 The scheme of the present application designs a low-voltage detection protection system for detecting whether the air conditioner power voltage is lower than the safe working range, and triggering the protection mechanism when low voltage is detected to cut off the driving signal of the IGBT to prevent damage to the device caused by low voltage. The system is composed of a voltage sampling module, a main chip module and an IGBT driving module. Among them, the main chip module is like a microcontroller (MCU), and the MCU is responsible for implementing signal processing and output control logic.

[0090] As shown in Figure 7As shown, the output end of the MCU outputs a pulse width modulation (PWM) signal to the driving module, and the driving signal output by the driving module is output to the gate G of the IGBT through the resistor R1; the collector C of the IGBT is connected to the anode of the diode D1, and the cathode of the diode D1 is connected to the ground through the capacitor C1. The emitter of the IGBT is connected to the ground through the resistor Rs. The ground end of the MCU is grounded, and the input end of the MCU receives the air conditioner power voltage sampled by the voltage sampling module from the common end between the capacitor C1 and the cathode of the diode D1.

[0091] In Figure 7 In the example shown, the voltage sampling module is mainly used to collect the rectified DC voltage signal, and the linear adjustment of the voltage amplitude is realized through a precise resistance voltage dividing network. The voltage sampling module includes an RC low-pass filter circuit (i.e., a resistance-capacitance filter circuit), which effectively eliminates high-frequency interference signals and improves sampling accuracy. The filtered voltage signal is then transmitted to the MCU for subsequent processing to ensure that the system obtains high-quality voltage data. The resistance voltage dividing network is generally a plurality of resistors connected in series for voltage division, which facilitates sampling by the main chip. The resistance voltage dividing network includes a potentiometer, which can be adjusted to linearly adjust the voltage by adjusting the angle of the potentiometer.

[0092] The scheme of the present application combines high-precision voltage sampling, fast signal processing, and reliable protection mechanisms, providing an important guarantee for the safe operation of the air conditioning system.

[0093] In some embodiments, the control unit 104 integrates the voltage detection value of the power voltage of the device in which the IGBT is located according to the power voltage of the device continuously sampled within a set sampling time, and performs optimization operation on the integrated sum of the voltage detection value of the power voltage of the device in which the IGBT is located according to a set integral proportion coefficient, determines whether the preset low-voltage reset function needs to be started based on the optimization operation result, and includes:

[0094] The control unit 104 is specifically configured to integrate and sum the power voltage of the device continuously acquired within a set sampling time according to a set integral proportion coefficient, to obtain the integral value of the power voltage of the device; wherein the set integral proportion coefficient is, for example, coefficient b. The specific functions and processes of the control unit 104 are also described in step S310.

[0095] The control unit 104 is specifically configured to determine whether the integral value of the power voltage of the device is less than a set threshold value; wherein the set threshold value is, for example, threshold value c. The specific functions and processes of the control unit 104 are also described in step S320.

[0096] The control unit 104 is further configured to determine that the preset low voltage reset function needs to be started if it is determined that the integral value of the power supply voltage of the device is less than a set threshold value. The specific functions and processes of the control unit 104 are also described in step S330.

[0097] Figure 8 The flowchart of the main program logic is shown in the figure. Figure 8 As shown in the figure, the low voltage detection and IGBT protection method provided by the scheme of the application includes the following steps:

[0098] Step 1: The voltage sampling module collects AC voltage, and then step 2 is performed.

[0099] In step 1, the sampling frequency is set to m and the sampling time is set to a. m is generally 10 kHz to 40 kHz, and a is generally 10 ms to 40 ms.

[0100] Continuous AC voltage detection: a high-speed analog-to-digital converter (ADC) is used to sample the AC voltage signal from the power grid. Before sampling, the AC voltage signal is adjusted by a voltage sampling module (such as a resistor divider network) to ensure that the input voltage is within the input range of the ADC.

[0101] Step 2: The AC voltage collected in a time is continuously operated, and then step 3 is performed.

[0102] Threshold calculation and comparison: voltage normal period sampling, the integral of the sampling value is about b x AC voltage effective value. Set the threshold value c as the threshold value of b x AC voltage effective value. The integral value is calculated by integrating the sampling values in a continuous time. b is the integral comparison coefficient, ranging from 0 to 1.

[0103] Step 3: Determine whether the running voltage sampling value is less than the set threshold value c: if yes, execute step 4, otherwise return to step 1.

[0104] In step 3, the integral sum result obtained by integrating the sampling values in a continuous time is compared with the set threshold value c: if the integral sum result is less than the set threshold value c, the low voltage protection mechanism is triggered; otherwise, continue normal operation. c is the set threshold value, ranging from 100 V to 200 V.

[0105] The scheme of the application integrates the voltage detection value of the power supply voltage of the device where the IGBT is located according to the power supply voltage of the device obtained by continuous sampling in a set sampling time, and performs integral summation on the voltage detection value of the power supply voltage of the device where the IGBT is located according to a set integral proportion coefficient to realize optimized operation. Based on the optimized operation result, it is determined whether the preset low voltage reset function needs to be started. When low voltage is detected, the protection mechanism can be triggered quickly to cut off the driving signal of the IGBT, preventing damage to the device caused by low voltage.

[0106] In some embodiments, the control unit 104 is configured to start the preset low-voltage reset function to protect the driving signal of the IGBT, and the control unit 104 is specifically configured to start the preset low-voltage reset function to start the preset low-voltage protection mechanism and cut off the driving signal of the IGBT.

[0107] As shown in Figure 8 The low-voltage detection and IGBT protection method provided by the scheme of the application further includes: step 4, starting low-voltage reset and cutting off the IGBT switch signal, and then performing step 5.

[0108] In step 4, when the low-voltage protection mechanism is triggered: the reset command is executed through the control logic module, and the entire system is reset after a time d, and then the air conditioner compressor and other loads stop running. At the same time of triggering the low-voltage protection mechanism, the MCU immediately cuts off the signal output to the IGBT driving module to prevent it from continuing to work in the low-voltage state. At the same time, a low-voltage warning is issued through the buzzer to alert the user. d is generally 13 ms.

[0109] The low-voltage reset detection scheme (i.e. the low-voltage detection and IGBT protection scheme) provided by the scheme of the application performs optimized operation on the voltage detection value of the power supply voltage (such as the air conditioner power supply voltage) of the device where the IGBT is located, compares and analyzes the operation result with the set value, judges whether the low-voltage reset needs to be started, and at the same time locks the switch signal input of the IGBT after starting the reset, reduces the influence of closed-loop control on the conduction state of the IGBT, so as to achieve the purpose of protecting the IGBT.

[0110] Figure 6 The waveform diagram of the driving IGBT signal in the reset process is shown in the figure. Figure 6 In the figure, the signal represented by green color is the voltage between the C poles of the IGBT, the signal represented by blue color is the chip reset pin signal, the signal represented by yellow color is the CE pole current of the IGBT, and the signal represented by pink color is the driving IGBT switch signal.

[0111] In some embodiments, the IGBT protection method provided by the scheme of the application further includes: a process of closing the preset low-voltage reset function, and the process is specifically as follows:

[0112] The control unit 104 is further configured to, after the preset low-voltage reset function is started, determine whether the power supply voltage of the device returns to the preset normal voltage range after a set reset time, and the set reset time is, for example, time d. The specific functions and processes of the control unit 104 are further described in step S410.

[0113] The control unit 104 is further configured to close the preset low voltage reset function to control the device to restart and run if it is determined that the power supply voltage of the device has recovered to the preset normal voltage range. The specific functions and processes of the control unit 104 are also described in step S420.

[0114] As shown in Figure 8 The low voltage detection and IGBT protection method provided by the scheme of the present application further comprises:

[0115] Step 5, after the reset is successful at time d, continue to detect the AC voltage, and determine whether the AC voltage has recovered to normal: if yes, restart the compressor, and if not, return to step 1.

[0116] As shown in Figure 7 and Figure 8 When the MCU detects that the voltage value meets the reset condition, the system will immediately trigger the low voltage protection mechanism, cut off the control driving signal (such as the PWM signal), stop the output of the driving module, and then disconnect the switching signal of the IGBT. In this state, the system will continue to monitor the power supply voltage state and wait for it to recover to the safe working range. Once it is detected that the power supply voltage has recovered to the normal working range, the system will automatically release the protection state, complete the reset operation, and restart the system operation. The detected voltage value is the voltage value obtained after sampling and operation. After the voltage value after sampling and operation is compared with the set threshold value, if the voltage value after sampling and operation is smaller than the set threshold value, the main chip actively resets and triggers the low voltage protection to cut off the PWM output, so that the IGBT is continuously turned off during the reset; if the PWM is not cut off, the control signal of the IGBT pin will continuously output a high level during the reset of the main chip, causing the IGBT to be continuously turned on, and if there is a large current signal (the air conditioner is suddenly turned on) at this time, the IGBT is easy to burn out.

[0117] In the scheme of the present application, the protection mode is to determine whether the AC current exceeds the threshold + forcibly turn off the IGBT control signal during the reset period; the detection mode is to continuously sample the DC bus voltage, compare the sampled data with the set threshold value, and open the low voltage reset if the condition is met. Through the above implementation scheme, the air conditioner low voltage detection protection system can quickly trigger the protection mechanism when low voltage is detected, cut off the driving signal of the IGBT, and prevent the device from being damaged due to low voltage. At the same time, the system can automatically detect the voltage recovery and restart the air conditioner after the voltage recovers to normal, ensuring the stable operation of the system.

[0118] Since the processing and functions realized by the device of the present embodiment are basically corresponding to the embodiments, principles and examples of the foregoing method, the description of the present embodiment will not be described in detail, and the relevant description in the foregoing embodiments will be referred to, which will not be described herein.

[0119] According to an embodiment of the present application, a frequency converter corresponding to the IGBT protection device is also provided. The frequency converter can include the IGBT protection device described above.

[0120] Since the processing and functions realized by the frequency converter of the present embodiment are basically corresponding to the embodiments, principles and examples of the aforementioned device, the description of the present embodiment will not be elaborated on the related descriptions in the aforementioned embodiments.

[0121] According to an embodiment of the present application, an air conditioner corresponding to the IGBT protection device is also provided. The air conditioner can include the IGBT protection device described above, or the frequency converter described above.

[0122] Since the processing and functions realized by the air conditioner of the present embodiment are basically corresponding to the embodiments, principles and examples of the aforementioned device, the description of the present embodiment will not be elaborated on the related descriptions in the aforementioned embodiments.

[0123] According to an embodiment of the present application, a computer program product corresponding to the IGBT protection method is also provided, which includes a computer program, and the computer program realizes the steps of the IGBT protection method described above when executed by a processor.

[0124] Since the processing and functions realized by the product of the present embodiment are basically corresponding to the embodiments, principles and examples of the aforementioned method, the description of the present embodiment will not be elaborated on the related descriptions in the aforementioned embodiments.

[0125] According to an embodiment of the present application, a storage medium corresponding to the IGBT protection method is also provided, which includes a stored program, and the program controls the device where the storage medium is located to execute the steps of the IGBT protection method described above when running.

[0126] Since the processing and functions realized by the storage medium of the present embodiment are basically corresponding to the embodiments, principles and examples of the aforementioned method, the description of the present embodiment will not be elaborated on the related descriptions in the aforementioned embodiments.

[0127] In summary, those skilled in the art can easily understand that the above-mentioned advantageous modes can be freely combined and superimposed without conflict.

[0128] The above only describes the embodiments of the present application and is not intended to limit the present application. Those skilled in the art can make various modifications and changes to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the scope of the claims of the present application.

Claims

1. A method of protecting an IGBT, characterized by, The application is applied to the protection of the IGBT based on the power voltage of the device where the IGBT is located, such as an air conditioner frequency converter; the protection method of the IGBT comprises: sampling the AC voltage signal of the device continuously within a set sampling time at a set sampling frequency to obtain the power voltage of the device; integrating the voltage detection value of the power voltage of the device where the IGBT is located based on the power voltage of the device obtained by continuous sampling within the set sampling time at a set integral proportion coefficient to realize optimization operation, and determining whether the preset low-voltage reset function needs to be started based on the optimization operation result; if it is determined that the preset low-voltage reset function needs to be started, starting the preset low-voltage reset function to protect the driving signal of the IGBT; wherein the integral value of the power voltage of the device obtained by detecting the power voltage of the device within a continuous set time is obtained by integrating the power voltage of the device within the continuous set time at a set integral coefficient; the integral value of the power voltage of the device is compared with the set threshold value, and the preset low-voltage protection mechanism is triggered in the case that the integral value of the power voltage of the device is less than the set threshold value, the driving signal of the IGBT is cut off to disconnect the switching signal of the IGBT; until in the case that the integral value of the power voltage of the device is greater than or equal to the set threshold value, the preset low-voltage protection mechanism is released, the IGBT is reset, and the device is restarted and operated.

2. The method of protecting an IGBT according to claim 1, characterized by, sampling the AC voltage signal of the device continuously within a set sampling time at a set sampling frequency to obtain the power voltage of the device comprises: adjusting the AC voltage signal of the device to the input voltage range of the preset ADC module to obtain the AC adjustment voltage of the device; sampling the AC adjustment voltage of the device continuously within a set sampling time at a set sampling frequency by using the preset ADC module to obtain the power voltage of the device.

3. The method of protecting an IGBT according to claim 1, characterized by, integrating the voltage detection value of the power voltage of the device where the IGBT is located based on the power voltage of the device obtained by continuous sampling within the set sampling time at a set integral proportion coefficient to realize optimization operation, and determining whether the preset low-voltage reset function needs to be started based on the optimization operation result comprises: integrating the power voltage of the device obtained by continuous acquisition within the set sampling time at a set integral proportion coefficient to obtain the integral value of the power voltage of the device; determining whether the integral value of the power voltage of the device is less than the set threshold value; if it is determined that the integral value of the power voltage of the device is less than the set threshold value, it is determined that the preset low-voltage reset function needs to be started.

4. The method of protecting an IGBT according to claim 1, characterized by, starting the preset low-voltage reset function to protect the driving signal of the IGBT comprises: starting the preset low-voltage reset function to start the preset low-voltage protection mechanism and cut off the driving signal of the IGBT.

5. The method of protecting an IGBT according to any one of claims 1 to 4, characterized in that, further comprising: in the case that the preset low-voltage reset function has been started, determining whether the power voltage of the device returns to the preset normal voltage range after a set reset time; If it is determined that the power voltage of the device has returned to the preset normal voltage range, the preset low-voltage reset function is closed to control the device to restart and run.

6. A protection device for an IGBT, characterized by The application is applied to the protection of the IGBT based on the power voltage of the device such as the air conditioner frequency converter in which the IGBT is located. The sampling unit is configured to continuously sample the AC voltage signal of the device at a set sampling frequency within a set sampling time to obtain the power voltage of the device. The control unit is configured to integrate and sum the voltage detection value of the power voltage of the device in which the IGBT is located according to the power voltage of the device obtained by continuous sampling within the set sampling time at a set integral proportion coefficient to realize optimization operation, and determine whether the preset low-voltage reset function needs to be started based on the optimization operation result. The control unit is further configured to start the preset low-voltage reset function to protect the driving signal of the IGBT if it is determined that the preset low-voltage reset function needs to be started. The integral value of the device power voltage is obtained by integrating and summing the device power voltage detected within the continuous set time at a set integral coefficient, and the integral value of the device power voltage is compared with the set threshold value. In the case that the integral value of the device power voltage is less than the set threshold value, the preset low-voltage protection mechanism is triggered to cut off the driving signal of the IGBT to disconnect the switching signal of the IGBT. Until in the case that the integral value of the device power voltage is greater than or equal to the set threshold value, the preset low-voltage protection mechanism is released to reset the IGBT to restart and run the device.

7. A frequency converter, characterized in that The application comprises: The IGBT protection device according to claim 6.

8. An air conditioner characterized by comprising: The application comprises: The IGBT protection device according to claim 6 or the frequency converter according to claim 7.

9. A storage medium, characterized by The storage medium comprises a stored program, wherein when the program runs, the device in which the storage medium is located performs the IGBT protection method according to any one of claims 1 to 5.

10. A computer program product comprising a computer program, characterized in that, The computer program is executed by the processor to realize the steps of the IGBT protection method according to any one of claims 1 to 5.

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