Method and device for preventing electronic switch from working in linear amplification region

Abstract

The invention relates to the field of motor control, and provides a method and a device for preventing an electronic switch from working in a linear amplification region in order to prevent the electronic switch from working in the linear amplification region. The turn-off control unit outputs a control signal to the drive control unit, so that the electronic switch stops working immediately, and the electronic switch is prevented from working in a linear amplification region to cause device failure.

Description

Technical Field

[0001] The present invention relates to the field of electronic switch control, and in particular to a method and a device for preventing an electronic switch from operating in a linear amplification region. Background Art

[0002] Depend on Figure 1 As can be seen, in the use of electronic switches (IGBT / MOS), the control signal is usually output by the MCU. This control signal has insufficient driving power and cannot directly drive the electronic switch to open or close. The control signal output by the MCU must first be sent to the driver chip (Driver), which then outputs a drive signal with a strong drive voltage or drive current to control the opening and closing of the electronic switch. When an abnormality occurs in the drive power supply system, resulting in unstable power supply or reduced supply voltage, the voltage of the drive signal output by the driver chip is too low, causing the electronic switch to operate in the linear amplification region, which can cause the electronic switch to overheat and fail. Summary of the Invention

[0003] In order to prevent an electronic switch from operating in a linear amplification region, the present invention provides a method and a device for preventing an electronic switch from operating in a linear amplification region.

[0004] The technical solution adopted by the present invention to solve the above problems is:

[0005] A device for preventing an electronic switch from operating in a linear amplification region comprises: a low-voltage power supply system, a control unit, a drive power supply system, a drive control unit, and an electronic switch, wherein the low-voltage power supply system supplies power to the control unit and the drive control unit, the drive power supply system supplies power to the electronic switch, the control unit controls the electronic switch via the drive control unit, and further comprises a drive power supply system voltage detection unit. When the drive power supply system voltage detection unit detects that the voltage value of the drive power supply system is lower than a protection threshold, the control signal output by the control unit to the drive control unit is shut down.

[0006] Furthermore, the control unit is an MCU, the driving power supply system voltage detection unit includes a first resistor and a second resistor, the ADC module of the MCU is connected to one end of the first resistor and the second resistor respectively, the other end of the first resistor is connected to the driving power supply system, and the other end of the second resistor is grounded.

[0007] The invention discloses a method for preventing an electronic switch from operating in a linear amplification region, which is applied to a device for preventing an electronic switch from operating in a linear amplification region. The method comprises: collecting the voltage value of a driving power supply system in real time; if the voltage value is lower than a protection threshold, shutting down the control signal output by the control unit to the driving control unit.

[0008] Furthermore, the control unit is an MCU, and the ADC module of the MCU is used to perform voltage sampling on the driving power supply system.

[0009] Furthermore, the ADC module of the MCU performs periodic voltage sampling on the drive power supply system and stores it in a buffer array. After a sampling cycle is completed, if the sampled voltage in the buffer array is lower than the protection threshold for a preset proportion of times, the MCU immediately stops outputting the control signal to the drive control unit.

[0010] Furthermore, the protection threshold is 12V.

[0011] Furthermore, the size of the buffer array is determined according to system requirements and characteristics of the electronic switch.

[0012] Furthermore, the ADC channel 1 of the ADC module of the MCU performs periodic voltage sampling on the drive power supply system.

[0013] Use the comparison function of the ADC module to set the maximum and minimum comparison values.

[0014] After each voltage sampling of ADC channel 1 is completed, it is compared with the set maximum and minimum values.

[0015] When the sampled value is greater than the maximum value or less than the minimum value, the ADC comparison interrupt service routine is triggered, and the voltage of the drive power supply system is sampled again using ADC channel 2 to ADC channel N. After the sampling is completed, if the sampled voltage is lower than the protection threshold for a preset number of times, the MCU immediately stops outputting the control signal to the drive control unit.

[0016] Furthermore, the minimum value is smaller than the protection threshold, and the maximum value is the ADC sampling maximum value or the threshold voltage of the overvoltage protection.

[0017] Furthermore, the protection threshold is 11V.

[0018] Compared with the prior art, the present invention has the following advantages: by detecting the voltage value of the drive power supply system, when its voltage value is lower than the protection threshold, the control signal output by the control unit to the drive control unit is shut down, so that the electronic switch stops working immediately, thereby preventing the electronic switch from operating in the linear amplification region and causing device failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the existing electronic switch control structure;

[0020] Figure 2 Schematic diagram of the device structure for preventing the electronic switch from operating in the linear amplification region;

[0021] Figure 3 This is the schematic diagram corresponding to protection logic 1;

[0022] Figure 4 This is the schematic diagram corresponding to protection logic 2. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0024] like Figure 2 As shown, the device for preventing an electronic switch from operating in the linear amplification region includes: a low-voltage power supply system, a control unit, a drive power supply system, a drive control unit, and an electronic switch. The low-voltage power supply system supplies power to the control unit and the drive control unit, and the drive power supply system supplies power to the electronic switch. The control unit controls the electronic switch via the drive control unit. The device also includes a drive power supply system voltage detection unit. When the drive power supply system voltage detection unit detects that the voltage value of the drive power supply system is lower than a protection threshold, the control signal output by the control unit to the drive control unit is shut off. By sampling the voltage of the drive power supply system, the state of the drive power supply system is detected in real time, thereby protecting the IGBT / MOS and preventing it from operating in the linear amplification region, which could cause device failure.

[0025] Specifically, in this embodiment, the control unit is an MCU, and the drive power supply system voltage detection unit includes a first resistor and a second resistor. The MCU's ADC module is connected to one end of the first resistor and the second resistor, respectively. The other end of the first resistor is connected to the drive power supply system, and the other end of the second resistor is grounded. The MCU's ADC module is used to sample the drive power supply system voltage. The MCU is powered by a low-voltage power supply system, and the supply voltage is determined by the MCU's characteristics, typically 3.3V or 5V. The driver chip is powered by the drive power supply system, and the supply voltage is determined by the characteristics of the IGBT / MOS, typically 14V to 18V.

[0026] In actual operation, voltage ripple interference can cause inaccurate single-shot sampling. To prevent misoperation and improve system stability, filtering and de-jittering are required. The present invention uses the MCU's ADC module to periodically sample the drive power supply system's voltage. Based on this, this embodiment provides two protection logics.

[0027] Protection logic 1: If Figure 3As shown in the figure, the MCU's ADC module periodically samples the voltage of the drive power supply system, applies a first-order low-pass filter to each sampled voltage ADC signal, and stores the processed data in a buffer array. After each sampling cycle, the data in the buffer array is statistically processed. If the sampled voltage in the buffer array falls below the protection threshold voltage more than a certain percentage of times, the MCU immediately stops outputting control signals to the drive control unit. The size of the buffer array affects the speed at which the system shuts down the IGBT / MOS transistor for protection. Therefore, the buffer array size can be determined based on system requirements and the characteristics of the IGBT / MOS transistor.

[0028] Protection logic 2: If Figure 4 As shown, channel 1 (ADCH1) of the MCU's ADC module periodically samples the voltage of the drive power supply system. Using the ADC module's comparison function, the maximum (MaxValue) and minimum (MinValue) comparison values are set, and the ADC comparison function is enabled. After each voltage sampling, ADC channel 1 (ADCH1) compares the voltage with the set maximum (MaxValue) and minimum (MinValue) values of the comparison module. Whenever the sampled value exceeds the maximum (MaxValue) or falls below the minimum (MinValue), the ADC comparison interrupt service routine is triggered. Within the ADC comparison interrupt service routine, ADC channels 2 (ADCH2) through ADC channels N (ADCHN) are immediately used to sample the drive power supply system voltage again. The sampled data from ADC channels 2 (ADCH2) through ADC channels N (ADCHN) is statistically analyzed. If the sampled voltage falls below the protection threshold voltage for more than a certain percentage of the time, the MCU immediately stops outputting control signals to the drive control unit. For example, if 80% of the data falls below the protection threshold voltage, the MCU immediately stops outputting control signals, thereby protecting the IGBT / MOS from operating in the linear amplification region.

[0029] In engineering practice, the minimum value (MinValue) is usually selected to be slightly smaller than the protection threshold voltage; the maximum comparison value (MaxValue) can be set to 0x0FFF (the maximum value of a 12-bit ADC sampling, which is related to the ADC sampling accuracy). If overvoltage protection is required for the drive voltage, the maximum value (MaxValue) can be set to the overvoltage protection threshold voltage.

[0030] Protection Logic 2 is much more timely than Protection Logic 1. Usually, Protection Logic 1 requires multiple sampling cycles to determine whether to perform output signal shutdown protection, while Protection Logic 2 can perform output signal shutdown protection in one sampling cycle. Protection Logic 1 or Protection Logic 2 can be selected according to actual needs.

[0031] The protection threshold voltage of the drive power supply system is related to the characteristics of the IGBT / MOS used. The device datasheet provides information on the drive voltage and on-current characteristics of the IGBT / MOS, thereby determining the Vgc / Vge drive voltage protection threshold of the IGBT / MOS. For commonly used IGBT devices, the drive voltage falls below 10V, and the protection threshold voltage can be set to approximately 12V in protection logic 1, and approximately 11V in protection logic 2.

Claims

1. A device for preventing an electronic switch from operating in a linear amplification region, comprising: A low-voltage power supply system, a control unit, a drive power supply system, a drive control unit and an electronic switch. The low-voltage power supply system supplies power to the control unit and the drive control unit, the drive power supply system supplies power to the electronic switch, and the control unit controls the electronic switch through the drive control unit. The device is characterized in that it also includes a drive power supply system voltage detection unit. When the drive power supply system voltage detection unit detects that the voltage value of the drive power supply system is lower than the protection threshold, the control signal output by the control unit to the drive control unit is shut down.

2. The device for preventing an electronic switch from operating in a linear amplification region according to claim 1, wherein: The control unit is an MCU, the driving power supply system voltage detection unit includes a first resistor and a second resistor, the ADC module of the MCU is connected to one end of the first resistor and the second resistor respectively, the other end of the first resistor is connected to the driving power supply system, and the other end of the second resistor is grounded.

3. A method for preventing an electronic switch from operating in a linear amplification region, applied to the device for preventing an electronic switch from operating in a linear amplification region according to claim 1 or 2, characterized in that: include: The voltage value of the drive power supply system is collected in real time. If the voltage value is lower than the protection threshold, the control signal output by the control unit to the drive control unit is shut down.

4. The method for preventing an electronic switch from operating in a linear amplification region according to claim 3, wherein: The control unit is an MCU, and the ADC module of the MCU is used to sample the voltage of the drive power supply system.

5. The method for preventing an electronic switch from operating in a linear amplification region according to claim 4, wherein: The ADC module of the MCU performs periodic voltage sampling on the drive power supply system and stores it in a buffer array. After a sampling cycle is completed, if the sampled voltage in the buffer array is lower than the protection threshold for a preset proportion of times, the MCU immediately stops outputting control signals to the drive control unit.

6. The method for preventing an electronic switch from operating in a linear amplification region according to claim 5, wherein: The protection threshold is 12V.

7. The method for preventing an electronic switch from operating in a linear amplification region according to claim 5, wherein: The size of the buffer array is determined based on system requirements and the characteristics of the electronic switch.

8. The method for preventing an electronic switch from operating in a linear amplification region according to claim 4, wherein: ADC channel 1 of the ADC module of the MCU performs periodic voltage sampling on the drive power supply system. Use the comparison function of the ADC module to set the maximum and minimum comparison values. After each voltage sampling of ADC channel 1 is completed, it is compared with the set maximum and minimum values. When the sampled value is greater than the maximum value or less than the minimum value, the ADC comparison interrupt service routine is triggered, and the voltage of the drive power supply system is sampled again using ADC channel 2 to ADC channel N. After the sampling is completed, if the sampled voltage is lower than the protection threshold for a preset number of times, the MCU immediately stops outputting the control signal to the drive control unit.

9. The method for preventing an electronic switch from operating in a linear amplification region according to claim 8, wherein: The minimum value is less than the protection threshold, and the maximum value is the ADC sampling maximum value or the overvoltage protection threshold voltage.

10. The method for preventing an electronic switch from operating in a linear amplification region according to claim 8, wherein: The protection threshold is 11V.

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