A protection device, motor controller, frequency converter, motor and air conditioner

Abstract

The application belongs to the technical field of electric machines, and discloses a protection device, an electric machine controller, a frequency converter, an electric machine and an air conditioner, which comprises a sampling module, a comparison module and a protection module; the sampling module samples a sampling current from a three-phase inverter negative terminal of an IPM module; the comparison module compares the sampling current with a reference threshold to obtain a comparison result; the comparison result is a first result when the sampling current does not overcurrent or a second result when the sampling current overcurrent; the protection module outputs a first protection signal when the comparison result is the first result, outputs a second protection signal when the comparison result is the second result and outputs the first protection signal again after setting a time; and the switch module controls a driving control chip to work when the first protection signal is received and controls the driving control chip to stop working when the second protection signal is received. According to the scheme, the overcurrent timing shutdown and self-starting function circuit is arranged between the three-phase inverter negative terminal of the IPM module and the driving control special chip, the protection of the IPM module is realized, and the safety is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electric machines, and particularly relates to a protection device, an electric machine controller, a frequency converter, an electric machine and an air conditioner, in particular to an application device of a circuit with overcurrent timing shutdown and self-starting function on a driving control special chip of an electric machine, an electric machine controller, a frequency converter, an electric machine and an air conditioner. BACKGROUND

[0002] In the field of driving control of electric machines (such as brushless direct current electric machines), driving control special chips are often used, which are highly integrated circuit chips specially designed for specific electric machine driving control tasks. Driving control special chips have high performance, low power consumption, high reliability, simple development and many other advantages and are widely used. However, the driving control special chip of the electric machine in the related scheme does not have an overcurrent protection locking function, which can cause damage to power devices in the driving control circuit of the electric machine, and even cause safety accidents.

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

[0004] The purpose of the application is to provide a protection device, an electric machine controller, a frequency converter, an electric machine and an air conditioner, to solve the problem that the driving control special chip of the electric machine in the related scheme does not have an overcurrent protection locking function, which can cause damage to power devices in the driving control circuit of the electric machine, and even cause safety accidents, to achieve the effect of protecting the IPM module and improving safety by setting a circuit with overcurrent timing shutdown and self-starting function between the three-phase inverter negative terminal of the electric machine IPM module and the driving control special chip of the electric machine without overcurrent protection locking function.

[0005] The application provides a protection device applied to driving control of a motor, which is arranged between three-phase inverter negative terminals of an IPM module of the motor and an enable pin of a driving control chip of the motor; the protection device comprises a sampling module, a comparison module, a protection module and a switching module; the sampling module is used for sampling current from the three-phase inverter negative terminals of the IPM module to obtain sampling current of the IPM module; the comparison module is used for setting a reference threshold and comparing the sampling current of the IPM module with the reference threshold to obtain a comparison result; the comparison result is a first result that the sampling current of the IPM module does not overcurrent or a second result that the sampling current of the IPM module overcurrent; the protection module is used for outputting a first protection signal when the comparison result is the first result, outputting a second protection signal when the comparison result is the second result, and outputting the first protection signal again after a set time of outputting the second protection signal; and the switching module is used for controlling the driving control chip to work when the first protection signal is received and controlling the driving control chip to stop working when the second protection signal is received.

[0006] In some embodiments, the sampling module comprises a first resistance module, a second resistance module and a first capacitance module; the three-phase inverter negative terminals of the IPM module are connected to ground through the first resistance module; the three-phase inverter negative terminals of the IPM module are also connected to ground through the second resistance module and the first capacitance module; and the common end of the second resistance module and the first capacitance module can output the sampling current of the IPM module to the comparison module.

[0007] In some embodiments, the comparison module comprises a third resistance module, a fourth resistance module, a second capacitance module and a first comparison module; a preset positive direct current power supply is connected to ground through the third resistance module and the fourth resistance module; the common end of the third resistance module and the fourth resistance module is connected to ground through the second capacitance module; the common end of the third resistance module and the fourth resistance module can output the reference threshold to the same-phase input end of the first comparison module; the sampling current of the IPM module output by the sampling module can be input to the opposite-phase input end of the first comparison module; and the output end of the first comparison module can output the comparison result to the protection module.

[0008] In some embodiments, the protection module comprises: a fifth resistor module, a sixth resistor module, a third capacitor module, a fourth capacitor module, and a second comparison module; wherein the comparison result output by the comparison module can be input to the inverting input terminal of the second comparison module; a preset positive direct current power supply is connected to ground through the fifth resistor module and the third capacitor module; the common terminal of the fifth resistor module and the third capacitor module is connected to the inverting input terminal of the second comparison module; a preset positive direct current power supply is connected to ground through the sixth resistor module and the fourth capacitor module; the common terminal of the sixth resistor module and the fourth capacitor module is connected to the non-inverting input terminal of the second comparison module; and the output terminal of the second comparison module can output the first protection signal or the second protection signal to the control terminal of the switch module.

[0009] In some embodiments, the protection module further comprises at least one of a seventh resistor module and a fifth capacitor module; wherein the seventh resistor module is arranged between the common terminal of the sixth resistor module and the fourth capacitor module and the ground; and the fifth capacitor module is arranged between the power supply terminal of the second comparison module and the ground.

[0010] In some embodiments, the switch module comprises: an eighth resistor module and a switch tube; wherein the first protection signal or the second protection signal output by the protection module can be input to the control terminal of the switch tube; a preset positive direct current power supply is connected to the control terminal of the switch tube through the eighth resistor module; the first connection terminal of the switch tube is connected to the enable pin of the drive control chip of the motor; and the second connection terminal of the switch tube is connected to the ground.

[0011] In order to match the above device, the present application further provides a motor controller comprising the above protection device.

[0012] In order to match the above device, the present application further provides a frequency converter comprising the above protection device.

[0013] In order to match the above device, the present application further provides a motor comprising the above protection device, or the above motor controller, or the above frequency converter.

[0014] In order to match the above device, the present application further provides an air conditioner comprising the above protection device, or the above motor controller, or the above frequency converter, or the above motor.

[0015] Therefore, the scheme of the present application, for the drive control of the motor, the drive control special chip of the motor without over-current protection locking function, between the three-phase inverter negative terminal of the IPM module of the motor and the special chip, is provided with an over-current timing shutdown and self-starting function circuit composed of a current sampling unit, an over-current comparison unit (specifically, an over-current comparison unit with over-current comparison function, shutdown locking function and self-starting function) and a switch control unit, the current of the three-phase inverter negative terminal of the IPM module is sampled by the current sampling unit, whether the current is over-current is judged by the over-current comparison unit, and according to the judgment result, the special chip is controlled by the switch control unit to realize over-current shutdown protection, shutdown locking and recovery of self-starting; thereby, by setting the over-current timing shutdown and self-starting function circuit between the three-phase inverter negative terminal of the IPM module of the motor and the drive control special chip of the motor without over-current protection locking function, the protection of the IPM module is realized, and the safety is improved.

[0016] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application.

[0017] The technical scheme of the present application will be further described in detail below with the help of drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The structural schematic diagram of an embodiment of the protection device of the present application;

[0019] Figure 2 The flowchart of the over-current shutdown protection process;

[0020] Figure 3 The flowchart of the over-current shutdown locking / self-starting process;

[0021] Figure 4 The structural schematic diagram of the over-current timing shutdown and self-starting function circuit. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical scheme and advantages of the present application more clear, the technical scheme of the present application will be described clearly and completely below by combining the specific embodiments of the present application with corresponding drawings. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0023] In view of the fact that the drive control special chip of the motor in the related scheme does not have an overcurrent protection locking function, damage to the power device in the drive control circuit of the motor can be caused, and even a safety accident can be caused. Specifically, when overcurrent occurs in the motor, although shutdown protection can be achieved (for example, overtemperature protection, when overcurrent occurs, the current rapidly increases, the current increase causes the temperature of the power module to increase, and when the overtemperature protection point is reached, the motor stops running, the overtemperature process is relatively slow, and the overcurrent is emitted quickly), but before the overcurrent fault is resolved, oscillation and repeated restart can occur in a short time, thereby damaging the normal start-stop power sequence, and thus causing permanent damage to the related power device, and even causing a serious safety accident.

[0024] Therefore, the scheme of the present application proposes a protection device, in particular, an application device of a circuit with overcurrent timing shutdown and self-starting function on a drive control special chip of a motor. Through the circuit with overcurrent timing shutdown and self-starting function, the current change of the three-phase inverter negative terminal of the power module of the motor can be monitored, and whether to shutdown is determined according to the current size change; when shutdown is determined, shutdown is controlled, and shutdown locking is performed to avoid damage caused by oscillation and repeated restart when overcurrent is not resolved; after shutdown locking, shutdown self-starting can be performed to automatically recover normal operation when the fault is resolved, to ensure normal operation and improve reliability.

[0025] According to an embodiment of the present application, a protection device is provided. Referring to Figure 1 the structural schematic diagram of an embodiment of the device of the present application. The protection device is applied to the drive control of a motor, the protection device is arranged between the three-phase inverter negative terminal of the IPM module of the motor and the enable pin of the drive control chip of the motor; the three-phase inverter negative terminal of the IPM module is the output terminal of the lower bridge of the three-phase inverter bridge in the IPM module, such as the terminal NU or the terminal NV or the terminal NW of the IPM module, and the drive control chip of the motor does not have an overcurrent protection locking function. In the scheme of the present application, as shown in Figure 1 the protection device includes a sampling module, a comparison module, a protection module, and a switching module, Figure 4 a structural schematic diagram of an overcurrent timing shutdown and self-starting function circuit, the current sampling unit is as shown in Figure 2 and Figure 4 the current sampling unit, the overcurrent comparison unit is as shown in Figure 2 and Figure 4 the overcurrent comparison unit, the shutdown locking function module and the self-starting function release module are as shown in Figure 2 and Figure 4 the shutdown locking function module and the self-starting function release module, and the switching control unit is as shown in Figure 2 and Figure 4 the switching control unit.

[0026] The sampling module is arranged at three-phase inverter negative terminals of an IPM module of the motor, and is configured to sample current from the three-phase inverter negative terminals of the IPM module to obtain a sampling current of the IPM module.

[0027] The comparison module is arranged at an output end of the sampling module, and is configured to set a reference threshold value, and compare the sampling current of the IPM module with the reference threshold value to obtain a comparison result.

[0028] The protection module is arranged at an output end of the comparison module, and is configured to output a first protection signal when the comparison result is the first result, output a second protection signal when the comparison result is the second result, and output the first protection signal again after a set time of outputting the second protection signal when the comparison result is the second result.

[0029] The switch module is arranged at an output end of the protection module, and is configured to control the drive control chip to work to make the drive control chip continue to output a PWM signal to a power device in the IPM module when the first protection signal is received, and control the drive control chip to stop working to make the drive control chip stop outputting the PWM signal to the power device in the IPM module when the second protection signal is received.

[0030] The present application aims to provide a more secure and reliable over-current protection function implementation scheme, and the over-current problem is not solved, and the phenomenon of shock and repeated restart may occur in a short time, and the timing shutdown can prevent the power device from being damaged due to shock (current fluctuation) within a certain time range; when the over-current problem is solved, the shutdown locking is ended, and the motor returns to normal operation, so as to avoid causing damage to the power device in the drive control circuit of the motor and even causing a safety accident, and improve the safety. The power device in the drive control circuit of the motor, such as an insulated gate bipolar transistor (IGBT tube), an insulated gate field effect tube (MOS tube), etc.

[0031] In some embodiments, the sampling module comprises a first resistance module, a second resistance module and a first capacitance module, the first resistance module is a parallel resistance RX1, a resistance RX2 and a resistance RX3 as shown in the figure, the second resistance module is a resistance R3 as shown in the figure, and the first capacitance module is a capacitance C2 as shown in the figure. Figure 4 Figure 4 Figure 4

[0032] ​​​The three-phase inverter negative terminal of the IPM module is connected to the ground through the first resistor module. The three-phase inverter negative terminal of the IPM module is also connected to the ground through the second resistor module and the first capacitor module. The common terminal of the second resistor module and the first capacitor module can output the sampling current of the IPM module to the comparison module.

[0033] In Figure 4 the example shown, the resistor RX1, the resistor RX2, the resistor RX3, the resistor R3 and the capacitor C2 constitute a current sampling unit. Figure 2 The current sampling unit is responsible for collecting the three-phase current of the power module, that is, collecting the current of the three-phase inverter negative terminal (such as terminal NU or terminal NV or terminal NW) of the IPM module.

[0034] Figure 2 It is a flowchart of the overcurrent shutdown protection process. As shown in Figure 2 , the three-phase inverter negative terminal of the power module outputs current to the current sampling unit. The overcurrent comparison unit can complete the overcurrent lock shutdown and the self-start function after the overcurrent is removed according to the current sampled by the current sampling unit. The switch control unit sends instructions to the special chip processing unit according to the instructions sent by the overcurrent comparison unit, solves the defect that the special chip for driving and controlling the motor has no overcurrent protection function, avoids the problems such as short circuit, breakdown and burst of the power module caused by overcurrent, and improves the safety.

[0035] In some embodiments, the comparison module comprises a third resistor module, a fourth resistor module, a second capacitor module and a first comparison module, the third resistor module is a resistor R1 as shown in Figure 4 , the fourth resistor module is a resistor R2 as shown in Figure 4 , the second capacitor module is a capacitor C1 as shown in Figure 4 , and the first comparison module is a comparator U1-B as shown in Figure 4 .

[0036] The preset positive direct current source is connected to the ground through the third resistor module and the fourth resistor module. The common terminal of the third resistor module and the fourth resistor module is connected to the ground through the second capacitor module. The common terminal of the third resistor module and the fourth resistor module can output the reference threshold to the non-inverting input terminal of the first comparison module. The sampling current of the IPM module output by the sampling module can be input to the inverting input terminal of the first comparison module. The output terminal of the first comparison module can output the comparison result to the protection module.

[0037] In Figure 4 the example shown, the comparator U1-B, the resistor R1, the resistor R2 and the capacitor C1 constitute a comparison module. Figure 2The overcurrent comparison unit is shown. The overcurrent comparison unit is responsible for determining the current size of the motor in operation, specifically determining the size of the current collected at the three-phase inverter negative terminal (such as terminal NU or terminal NV or terminal NW) of the IPM module; when the overcurrent of the three-phase inverter negative terminal (such as terminal NU or terminal NV or terminal NW) of the IPM module is determined, the output of the comparator U1-B is flipped to output low level, and the motor stops running.

[0038] Figure 3 The flowchart of the overcurrent shutdown locking / self-starting process is shown. As shown in Figure 3 The current sampling unit, overcurrent comparison unit, switch control unit and special chip processing unit shown in Figure 2 When overcurrent occurs, the shutdown locking function is executed, and when the overcurrent is removed, the self-starting operation is restored, avoiding problems such as power module short circuit, breakdown and explosion caused by overcurrent, and improving safety.

[0039] In some embodiments, the protection module comprises a fifth resistance module, a sixth resistance module, a third capacitance module, a fourth capacitance module and a second comparison module, the fifth resistance module is a resistance R4 as shown in Figure 4 The sixth resistance module is a resistance R5 as shown in Figure 4 The third capacitance module is a capacitor C3 as shown in Figure 4 The fourth capacitance module is a capacitor C4 as shown in Figure 4 The second comparison module is a comparator U1-A as shown in Figure 4

[0040] The comparison result output by the comparison module can be input to the inverting input end of the second comparison module; the preset positive direct current power supply is grounded through the fifth resistance module and the third capacitance module; the common end of the fifth resistance module and the third capacitance module is connected to the inverting input end of the second comparison module.

[0041] The preset positive direct current power supply is grounded through the sixth resistance module and the fourth capacitance module; the common end of the sixth resistance module and the fourth capacitance module is connected to the non-inverting input end of the second comparison module; the output end of the second comparison module can output the first protection signal or the second protection signal to the control end of the switch module.

[0042] ​The overcurrent timing shutdown and self-start function circuit provided by the present invention controls the timing of the MOS transistor U2 by setting the charging and discharging time composed of a comparator and resistors and capacitors. This allows for real-time detection and adjustment of the output current value of the power module. Based on the change in current magnitude, a decision is made on whether to shut down. When shutdown is determined, the circuit controls the shutdown and locks it. After shutdown locking, it can perform automatic restart, providing effective overcurrent control and protection for the power module, ensuring normal operation and safety, and improving reliability.

[0043] In some embodiments, the protection module further includes at least one of a seventh resistor module and a fifth capacitor module, wherein the seventh resistor module is as follows: Figure 4 The resistor R6 shown, and the fifth capacitor module as shown Figure 4 The capacitor C5 is shown.

[0044] The seventh resistor module is disposed between the common terminal of the sixth resistor module and the fourth capacitor module and ground; the fifth capacitor module is disposed between the power supply terminal of the second comparator module and ground.

[0045] Figure 4 The overcurrent timed shutdown and self-start function circuit shown is located between the three-phase inverter negative terminal of the IPM module (such as terminal NU, terminal NV, or terminal NW) and the enable terminal EN of the dedicated motor drive control chip that lacks overcurrent protection lockout function. This can compensate for the deficiency of the dedicated motor drive control chip in related solutions that lacks overcurrent protection lockout function. Specifically, the dedicated motor drive control chip lacks overcurrent protection lockout function. For example, the ROHM BD62011FS brushless DC motor drive control chip does not have overcurrent protection (OCP) detection function. When the six PWM signals are turned off, only the three signals of the upper bridge arm can be turned off; the three signals of the lower bridge arm cannot be turned off. When an overcurrent occurs, if there is no time delay lockout, the IPM module may be burned out at the moment the upper bridge arm is turned off.

[0046] The negative terminal of the three-phase inverter power module of the motor is the output terminal of the lower tube of the three bridge arms in the three-phase inverter bridge, that is, the grounding terminal of the lower tube of the three bridge arms, such as the output terminal NU of the lower tube of the U-phase bridge arm, or the output terminal VU of the lower tube of the V-phase bridge arm, or the output terminal WU of the lower tube of the W-phase bridge arm. The terminals NU, NV, and NW are respectively grounded by connecting sampling resistors such as resistor RX1, resistor RX2, and resistor RX3.

[0047] exist Figure 4 In the example shown, resistor R4, capacitor C3, resistor R5, resistor R6, and capacitor C4 constitute... Figure 2The stop locking function module in the power module is provided with a resistor R4, a capacitor C3, a resistor R5, a resistor R6 and a capacitor C4.

[0048] In the example shown in the figure, the resistor R4, the capacitor C3, the resistor R5, the resistor R6 and the capacitor C4 also constitute a self-starting function module in the power module. Figure 4 The self-starting function module in the power module is provided with a resistor R4, a capacitor C3, a resistor R5, a resistor R6 and a capacitor C4. Figure 2 The self-starting function module in the power module is provided with a resistor R4, a capacitor C3, a resistor R5, a resistor R6 and a capacitor C4.

[0049] Figure 4 The overcurrent timing stop and self-starting function circuit shown in the figure can detect the current change of the three-phase inverter negative terminal of the IPM module, and make a judgment on whether to stop according to the current size of the three-phase inverter negative terminal of the IPM module, such as overcurrent of the three-phase inverter negative terminal of the IPM module and overcurrent not being removed, which can be stopped for a certain time to prevent the expansion of the fault and cause a major accident, and improve the safety; when the overcurrent problem of the three-phase inverter negative terminal of the IPM module is removed, the stop locking is ended, and the motor resumes normal operation to ensure normal operation.

[0050] The scheme of the application provides a controller with an overcurrent timing stop and self-starting function circuit, which can monitor the current change of the three-phase inverter negative terminal of the power module of the motor, make a judgment on whether to stop according to the current size change of the three-phase inverter negative terminal of the power module of the motor, and protect reliably; can control the stop when determining the stop, and perform stop locking to avoid damage caused by oscillation and repeated restart when the overcurrent is not removed, and improve the safety; can perform stop self-starting after stop locking to automatically restore normal operation when the fault is removed, ensure normal operation, and improve the reliability.

[0051] In some embodiments, the switch module comprises an eighth resistance module and a switch tube, the eighth resistance module is as shown in the figure, and the switch tube is as shown in the figure. Figure 4 The resistor R7 is as shown in the figure, and the switch tube is as shown in the figure. Figure 4 The MOS tube U2 is as shown in the figure.

[0052] The first protection signal or the second protection signal output by the protection module can be input to the control end of the switch tube; a preset positive direct current power supply is connected to the control end of the switch tube through the eighth resistance module; the first connection end of the switch tube is connected to the enable pin of the driving control chip of the motor; and the second connection end of the switch tube is grounded. The switch tube is a MOS tube U2, the control end of the switch tube is the gate G1 of the MOS tube U2, the first connection end of the switch tube is the drain D of the MOS tube U2, and the second connection end of the switch tube is the source S of the MOS tube U2.

[0053] As shown in Figure 4 , the overcurrent timing shutdown and self-starting function circuit comprises: resistors RX1, RX2, RX3, R1, R2, R3, R4, R5, R6, R7, capacitors C1, C2, C3, C4, C5, comparators U1-A, U1-B, and a MOS tube U2. Figure 2 In the example shown in Figure 4 , the comparator U1-A, the capacitor C5, the resistor R7, and the MOS tube U2 constitute a switch control unit. The switch control unit controls the opening or closing of the MOS tube U2 according to whether the current is overflown, and sends a command to the EN pin of the special chip.

[0054] The three-phase inverter negative terminal (such as terminal NU or terminal NV or terminal NW) of the IPM module is connected to ground through the parallel connection of resistors RX1, RX2 and RX3. The three-phase inverter negative terminal (such as terminal NU or terminal NV or terminal NW) of the IPM module is also connected to the inverting input terminal of comparator U1-B through resistor R3. The inverting input terminal of comparator U1-B is also connected to ground through capacitor C2. The +5V power supply is connected to the first connection terminal of resistor R1; the second connection terminal of resistor R1 is connected to the non-inverting input terminal of comparator U1-B. The second connection terminal of resistor R1 is also connected to ground through resistor R2; the common terminal of resistor R1 and resistor R2 is denoted as point E. The second connection terminal of resistor R1 is also connected to ground through capacitor C1, and capacitor C1 is connected to the non-inverting input terminal of comparator U1-B. The +5V power supply is connected to ground through resistor R4 and capacitor C3; the output terminal of comparator U1-B is connected to the common terminal of resistor R4 and capacitor C3. The output terminal of comparator U1-B is also connected to the inverting input terminal of comparator U1-A. The +5V power supply is connected to ground through resistor R5 and resistor R6; the common terminal of resistor R5 and resistor R6 is denoted as point F. The common terminal of resistor R5 and resistor R6 is connected to ground through capacitor C4; the common terminal of resistor R5 and resistor R6 is also connected to the non-inverting input terminal of comparator U1-A. The +5V power supply is also connected to the power supply terminal of comparator U1-A; the ground terminal GND of comparator U1-A is connected to ground. The power supply terminal of comparator U1-A is also connected to ground through capacitor C5. The +5V power supply is connected to the output terminal of comparator U1-A through resistor R7; the output terminal of comparator U1-A is connected to the gate G1 of MOS transistor U2; the drain D of MOS transistor U2 is connected to the enable terminal EN of the motor driving control special chip without over-current protection locking function. The enable terminal EN of the motor driving control special chip without over-current protection locking function is active at low level. The source S of MOS transistor U2 is connected to ground.

[0055] Referring to Figure 4In the shown example, in normal condition, in the comparator U1-B, the E point (i.e. the common terminal of the resistor R1 and the resistor R2) is a fixed reference point voltage (about 0.6V), the voltage V+ of the non-inverting input of the comparator U1-B > the voltage V- of the inverting input of the comparator U1-B, the output of the comparator U1-B outputs high level; the +5V power supply charges the capacitor C3 through the resistor R4. In the comparator U1-A, the +5V power supply charges the capacitor C4 through the resistor R5, and after the charging is completed, the voltage of the F point (i.e. the common terminal of the resistor R5 and the resistor R6) is about 4.6V. Since the charging and discharging time τ1 (τ1=R4×C3) of the capacitor C3 is faster than the charging and discharging time τ2 (τ2=R5×C4) of the capacitor C4, τ1<τ2, the voltage V- of the inverting input of the comparator U1-A < the voltage V+ of the non-inverting input of the comparator U1-A, the output of the comparator U1-A outputs low level, the MOS transistor U2 is in the cut-off state, the EN pin of the special chip is set to high level (the EN pin low level is effective), and the motor normally operates. It can be seen that when the current of the three-phase inverter negative terminal (such as the terminal NU or the terminal NV or the terminal NW) of the IPM module does not overcurrent, the normal working state of the motor is not affected.

[0056] When the current of the three-phase inverter negative terminal (such as the terminal NU or the terminal NV or the terminal NW) of the IPM module overcurrent, in the comparator U1-B, the voltage V- of the inverting input of the comparator U1-B > the voltage V+ of the non-inverting input of the comparator U1-B, the output of the comparator U1-B flips, the output of the comparator U1-B outputs low level, and the capacitor C3 begins to discharge. In the comparator U1-A, the voltage V- of the inverting input of the comparator U1-A < the voltage V+ of the non-inverting input of the comparator U1-A, the output of the comparator U1-A outputs high level, the MOS transistor U2 is in the saturation state, the EN pin of the special chip is set to low level, and the motor stops operating. It can be seen that when the current of the three-phase inverter negative terminal (such as the terminal NU or the terminal NV or the terminal NW) of the IPM module overcurrent, the overcurrent timing stop and self-start function circuit can quickly respond, turn off the driving output signal of the special chip, stop the motor, and avoid the problems of power module short circuit, breakdown, and burst due to overcurrent.

[0057] Referring to Figure 2In the shown example, the shutdown lock is that when the motor stops running, in the comparator U1-B, the voltage V- of the inverting input terminal of the comparator U1-B approaches 0V, and the voltage V+ of the non-inverting input terminal of the comparator U1-B > the voltage V- of the inverting input terminal of the comparator U1-B. The +5V power supply charges the capacitor C3 through the resistor R4, and the voltage value of the capacitor C3 starts to slowly rise. The time period during which the voltage value of the capacitor C3 slowly rises to the voltage value of the capacitor C4 is the shutdown lock time, and the lock time is approximately equal to 3τ1 (τ1=R4xC3). It can be seen that before the overcurrent of the three-phase inverter negative terminal (such as the terminal NU or the terminal NV or the terminal NW) of the IPM module is removed, the shutdown lock is used to delay the start-up, so as to avoid the problems such as short circuit, breakdown and burst of the power module caused by the expansion of the fault due to the continuous overcurrent.

[0058] The recovery self-start is that in the shutdown lock stage, when the voltage value of the capacitor C3 slowly rises until greater than the voltage value of the capacitor C4, the comparator U1-A starts to recover to the low voltage output, the MOS tube U2 is in the cut-off state, the special chip EN pin is high, and the motor self-start recovers to the normal operation. It can be seen that after the overcurrent problem of the three-phase inverter negative terminal (such as the terminal NU or the terminal NV or the terminal NW) of the IPM module is removed, the shutdown lock is ended, and the motor recovers to the normal operation.

[0059] The overcurrent protection function provided by the scheme of the present application is mainly composed of a comparator, a resistor-capacitor and a MOS tube. The timing opening of the MOS tube is controlled by using the setting of the charging and discharging time difference of the resistor-capacitor, so that the output current value of the power module can be detected in real time, and the power module is effectively protected from overcurrent. The power module is, for example, a power device in a three-phase inverter bridge of a motor, or a power device in an intelligent power module (IPM module) of a motor, etc. The overcurrent protection provided by the scheme of the present application has the functions of lock and self-start, and has the characteristics of simple and reliable circuit design, low cost, easy implementation and promotion, etc.

[0060] By employing the technical solution of this invention, a dedicated drive control chip for motors lacking overcurrent protection and locking functions is provided. Between the three-phase inverter negative terminal of the motor's IPM module and this dedicated chip, an overcurrent timed shutdown and self-start function circuit is set up, consisting of a current sampling unit, an overcurrent comparison unit (specifically, an overcurrent comparison unit with overcurrent comparison, shutdown locking, and self-start release functions), and a switch control unit. The current sampling unit samples the current at the three-phase inverter negative terminal of the IPM module, the overcurrent comparison unit determines whether the current is overcurrent, and based on the determination result, the switch control unit controls the dedicated chip to achieve overcurrent shutdown protection, shutdown locking, and self-start recovery. Therefore, by setting up a circuit with overcurrent timed shutdown and self-start functions between the three-phase inverter negative terminal of the motor's IPM module and the dedicated drive control chip for motors lacking overcurrent protection and locking functions, protection of the IPM module is achieved, improving safety.

[0061] According to an embodiment of the present invention, a motor controller corresponding to the protection device is also provided. The motor controller may include the protection device described above.

[0062] Since the processing and functions implemented by the motor controller in this embodiment are basically the same as those in the embodiments, principles and examples of the device, any details not covered in this embodiment can be found in the relevant descriptions in the foregoing embodiments, and will not be repeated here.

[0063] According to an embodiment of the present invention, a frequency converter corresponding to a protection device is also provided. This frequency converter may include the protection device described above.

[0064] Since the processing and functions implemented by the frequency converter in this embodiment are basically the same as those in the embodiments, principles and examples of the device, any details not covered in this embodiment can be found in the relevant descriptions in the foregoing embodiments, and will not be repeated here.

[0065] According to an embodiment of the present invention, a motor corresponding to a protection device is also provided. This motor may include: the protection device described above, or the motor controller described above, or the frequency converter described above.

[0066] The protection device includes: a sampling module, a comparison module, a protection module, and a switching module. The sampling module is as follows: Figure 4 and Figure 2 The current sampling unit shown, the comparison module is as follows Figure 4 and Figure 2 The overcurrent comparator unit and protection module shown are as follows: Figure 4 and Figure 2 The stop lock function module and the auto-start release function module shown are as follows: [Switch module details omitted] Figure 4 and Figure 4The switch control unit shown.

[0067] The sampling module is arranged at three-phase inverter negative terminals of the IPM module of the motor, and is configured to sample current from the three-phase inverter negative terminals of the IPM module to obtain a sampling current of the IPM module.

[0068] The comparison module is arranged at an output end of the sampling module, and is configured to set a reference threshold value, and compare the sampling current of the IPM module with the reference threshold value to obtain a comparison result; the comparison result is a first result that the sampling current of the IPM module does not overcurrent, or a second result that the sampling current of the IPM module overcurrent.

[0069] The protection module is arranged at an output end of the comparison module, and is configured to output a first protection signal in a case that the comparison result is the first result; output a second protection signal in a case that the comparison result is the second result; and output the first protection signal again after a set time of outputting the second protection signal in the case that the comparison result is the second result.

[0070] The switch module is arranged at an output end of the protection module, and is configured to control the drive control chip to work in a case that the first protection signal is received, so that the drive control chip continues to output a PWM signal to a power device in the IPM module; and control the drive control chip to stop working in a case that the second protection signal is received, so that the drive control chip stops outputting the PWM signal to the power device in the IPM module.

[0071] In the scheme of the application, the phenomenon of oscillation and repeated restart may occur in a short time before the overcurrent problem is solved, and the timing shutdown can prevent the power device in the drive control circuit of the motor from being damaged due to the oscillation (current fluctuation) within a certain time range; when the overcurrent problem is solved, the shutdown locking is ended, and the motor resumes normal operation, so as to avoid causing damage to the power device in the drive control circuit of the motor and even causing a safety accident, and improve the safety. The power device in the drive control circuit of the motor includes an insulated gate bipolar transistor (IGBT tube), an insulated gate field effect transistor (MOS tube), and the like.

[0072] In some embodiments, the sampling module includes a first resistance module, a second resistance module, and a first capacitance module. Figure 4 The parallel resistors RX1, RX2, and RX3 shown in the figure, the second resistance module is a resistor R3 shown in the figure. Figure 4 The first capacitance module is a capacitor C2 shown in the figure. Figure 2 The first capacitance module is a capacitor C2 shown in the figure.

[0073] The three-phase inverter negative terminal of the IPM module is connected to the ground through the first resistor module. The three-phase inverter negative terminal of the IPM module is also connected to the ground through the second resistor module and the first capacitor module. The common terminal of the second resistor module and the first capacitor module can output the sampling current of the IPM module to the comparison module.

[0074] In Figure 2 the example shown, the resistor RX1, the resistor RX2, the resistor RX3, the resistor R3 and the capacitor C2 constitute Figure 4 the current sampling unit. The current sampling unit is responsible for collecting the three-phase current of the power module, that is, collecting the current of the three-phase inverter negative terminal (such as terminal NU or terminal NV or terminal NW) of the IPM module.

[0075] As Figure 4 shown, the power module three-phase inverter negative terminal outputs current to the current sampling unit, and the overcurrent comparison unit can complete overcurrent locking shutdown and recovery self-starting function after overcurrent is removed according to the current sampled by the current sampling unit. The switch control unit gives instructions to the special chip processing unit according to the instructions issued by the overcurrent comparison unit, solves the defect that the motor drive control special chip has no overcurrent protection function, avoids problems such as power module short circuit, breakdown and burst caused by overcurrent, and improves safety.

[0076] In some embodiments, the comparison module comprises a third resistor module, a fourth resistor module, a second capacitor module and a first comparison module, the third resistor module is a resistor R1 as Figure 4 shown, the fourth resistor module is a resistor R2 as Figure 4 shown, the second capacitor module is a capacitor C1 as Figure 4 shown, and the first comparison module is a comparator U1-B as Figure 2 shown.

[0077] The preset positive direct current source is connected to the ground through the third resistor module and the fourth resistor module. The common terminal of the third resistor module and the fourth resistor module is connected to the ground through the second capacitor module. The common terminal of the third resistor module and the fourth resistor module can output the reference threshold to the non-inverting input terminal of the first comparison module. The sampling current of the IPM module output by the sampling module can be input to the inverting input terminal of the first comparison module. The output terminal of the first comparison module can output the comparison result to the protection module.

[0078] In Figure 3 the example shown, the comparator U1-B, the resistor R1, the resistor R2 and the capacitor C1 constitute Figure 2The overcurrent comparison unit is shown. The overcurrent comparison unit is responsible for determining the current size of the motor in operation, specifically determining the size of the current collected at the three-phase inverter negative terminal (such as terminal NU or terminal NV or terminal NW) of the IPM module; when the overcurrent at the three-phase inverter negative terminal (such as terminal NU or terminal NV or terminal NW) of the IPM module is determined, the output end of the comparator U1-B is flipped to output a low level, and the motor stops running.

[0079] As shown in Figure 4 As shown in Figure 4 The current sampling unit, overcurrent comparison unit, switch control unit and special chip processing unit are shown. When overcurrent occurs, the shutdown locking function is executed, and when the overcurrent is removed, the self-starting operation is restored, avoiding problems such as short circuit, breakdown and burst of the power module caused by overcurrent, and improving safety.

[0080] In some embodiments, the protection module comprises a fifth resistance module, a sixth resistance module, a third capacitance module, a fourth capacitance module and a second comparison module, the fifth resistance module is a resistance R4 as shown Figure 4 The sixth resistance module is a resistance R5 as shown Figure 4 The third capacitance module is a capacitor C3 as shown Figure 4 The fourth capacitance module is a capacitor C4 as shown Figure 4 The second comparison module is a comparator U1-A as shown Figure 4

[0081] The comparison result output by the comparison module can be input to the inverting input end of the second comparison module; the preset positive direct current power supply is grounded through the fifth resistance module and the third capacitance module; the common end of the fifth resistance module and the third capacitance module is connected to the inverting input end of the second comparison module.

[0082] The preset positive direct current power supply is grounded through the sixth resistance module and the fourth capacitance module; the common end of the sixth resistance module and the fourth capacitance module is connected to the non-inverting input end of the second comparison module; the output end of the second comparison module can output the first protection signal or the second protection signal to the control end of the switch module.

[0083] In the scheme of the application, the timing opening of the MOS tube U2 is controlled by the setting of the charging and discharging time composed of the comparator and the resistance and capacitance, so as to detect and adjust the output current value of the power module in real time, make a judgment on whether to stop according to the current size change, control the shutdown and perform the shutdown locking when the shutdown is determined, and perform the shutdown self-starting after the shutdown locking, effectively control and protect the overcurrent of the power module, ensure normal operation and safety, and improve reliability.

[0084] ​In some embodiments, the protection module further comprises at least one of a seventh resistance module and a fifth capacitance module, the seventh resistance module being a resistance R6 as shown in Figure 4 the fifth capacitance module being a capacitance C5 as shown in Figure 2 .

[0085] The seventh resistance module is arranged between the common terminal of the sixth resistance module and the fourth capacitance module and the ground; and the fifth capacitance module is arranged between the power terminal of the second comparison module and the ground.

[0086] Figure 4 The overcurrent timing shutdown and self-starting function circuit as shown in the figure is arranged between the three-phase inverter negative terminal (such as terminal NU or terminal NV or terminal NW) of the IPM module and the enable terminal EN of the driving control special chip of the motor without overcurrent protection locking function, so as to make up for the defect that the driving control special chip of the motor does not have the overcurrent protection locking function in the related scheme. The three-phase inverter negative terminal of the power module of the motor is, for example, the output terminal of the lower tube of the three bridge arms in the three-phase inverter bridge, that is, the ground terminal of the lower tube of the three bridge arms, such as the output terminal NU of the lower tube of the U-phase bridge arm, the output terminal NV of the lower tube of the V-phase bridge arm, or the output terminal NW of the lower tube of the W-phase bridge arm. The terminal NU, the terminal NV, and the terminal NW are respectively connected to the corresponding sampling resistors such as the resistor RX1, the resistor RX2, and the resistor RX3 and grounded.

[0087] In the example shown in Figure 2 , the resistance R4, the capacitance C3, the resistance R5, the resistance R6, and the capacitance C4 constitute a shutdown locking function module in Figure 4 . According to the principle of capacitance charging and discharging, when the motor stops running, the resistance R4 charges the capacitance C3, and the voltage value of the capacitance C3 starts to slowly rise. The time period during which the voltage value of the capacitance C3 slowly rises to the voltage value of the capacitance C4 is the shutdown locking time, which can avoid problems such as short circuit, breakdown, and burst of the power module caused by repeated starting of the motor for a short time.

[0088] In the example shown in Figure 4 , the resistance R4, the capacitance C3, the resistance R5, the resistance R6, and the capacitance C4 also constitute a recovery self-starting function module in Figure 4 . When the overcurrent problem of the three-phase inverter negative terminal (such as the terminal NU or the terminal NV or the terminal NW) of the IPM module is resolved, the recovery self-starting function module ends the shutdown locking and the motor resumes normal operation.

[0089] Figure 4The overcurrent timing shutdown and self-starting function circuit shown can detect the current change of the three-phase inverter negative terminal of the IPM module, and make a judgment on whether to shutdown according to the current size of the three-phase inverter negative terminal of the IPM module, such as the overcurrent of the three-phase inverter negative terminal of the IPM module and the overcurrent not being removed, which can shutdown and lock within a certain time to prevent the expansion of the fault and cause major accidents and improve safety; when the overcurrent problem of the three-phase inverter negative terminal of the IPM module is removed, the shutdown and locking is ended, and the motor resumes normal operation to ensure normal operation.

[0090] In the scheme of the application, the current change of the three-phase inverter negative terminal of the power module of the motor can be monitored, and a judgment on whether to shutdown is made according to the current size change of the three-phase inverter negative terminal of the power module of the motor to reliably protect; the shutdown can be controlled when it is determined to shutdown, and shutdown locking is performed to avoid damage caused by oscillation and repeated restart when the overcurrent is not removed, and safety is improved; the shutdown self-starting can be performed after shutdown locking to automatically resume normal operation when the fault is removed, normal operation is ensured, and reliability is improved.

[0091] In some embodiments, the switch module comprises an eighth resistance module and a switch tube, the eighth resistance module is as shown in Figure 2 The resistance R7 is shown, and the switch tube is as shown in Figure 4 The MOS tube U2 is shown.

[0092] The first protection signal or the second protection signal output by the protection module can be input to the control end of the switch tube; the preset positive direct current power supply is connected to the control end of the switch tube after passing through the eighth resistance module; the first connection end of the switch tube is connected to the enable pin of the drive control chip of the motor; and the second connection end of the switch tube is grounded. The switch tube is a MOS tube U2, the control end of the switch tube is the gate G1 of the MOS tube U2, the first connection end of the switch tube is the drain D of the MOS tube U2, and the second connection end of the switch tube is the source S of the MOS tube U2.

[0093] As shown in Figure 4 The overcurrent timing shutdown and self-starting function circuit comprises resistors RX1, RX2, RX3, R1, R2, R3, R4, R5, R6, R7, capacitors C1, C2, C3, C4, C5, comparators U1-A and U1-B, and a MOS tube U2. ​ In the example shown, the comparators U1-A, the capacitor C5, the resistance R7, and the MOS tube U2 constitute ​ The switch control unit shown. The switch control unit controls the opening or closing of the MOS tube U2 according to whether the overcurrent occurs, and sends instructions to the special chip EN pin.

[0094] The three-phase inverter negative terminal (such as terminal NU or terminal NV or terminal NW) of the IPM module is connected to ground through the parallel connection of resistors RX1, RX2 and RX3. The three-phase inverter negative terminal (such as terminal NU or terminal NV or terminal NW) of the IPM module is also connected to the inverting input terminal of comparator U1-B through resistor R3. The inverting input terminal of comparator U1-B is also connected to ground through capacitor C2. The +5V power supply is connected to the first connection terminal of resistor R1; the second connection terminal of resistor R1 is connected to the non-inverting input terminal of comparator U1-B. The second connection terminal of resistor R1 is also connected to ground through resistor R2; the common terminal of resistor R1 and resistor R2 is denoted as point E. The second connection terminal of resistor R1 is also connected to ground through capacitor C1, and capacitor C1 is connected to the non-inverting input terminal of comparator U1-B. The +5V power supply is connected to ground through resistor R4 and capacitor C3; the output terminal of comparator U1-B is connected to the common terminal of resistor R4 and capacitor C3. The output terminal of comparator U1-B is also connected to the inverting input terminal of comparator U1-A. The +5V power supply is connected to ground through resistor R5 and resistor R6; the common terminal of resistor R5 and resistor R6 is denoted as point F. The common terminal of resistor R5 and resistor R6 is connected to ground through capacitor C4; the common terminal of resistor R5 and resistor R6 is also connected to the non-inverting input terminal of comparator U1-A. The +5V power supply is also connected to the power supply terminal of comparator U1-A; the ground terminal GND of comparator U1-A is connected to ground. The power supply terminal of comparator U1-A is also connected to ground through capacitor C5. The +5V power supply is connected to the output terminal of comparator U1-A through resistor R7; the output terminal of comparator U1-A is connected to the gate G1 of MOS transistor U2; the drain D of MOS transistor U2 is connected to the enable terminal EN of the motor driving control special chip without over-current protection locking function. The enable terminal EN of the motor driving control special chip without over-current protection locking function is active at low level. The source S of MOS transistor U2 is connected to ground.

[0095] Referring to ​In the shown example, in normal condition, in the comparator U1-B, the E point (i.e. the common terminal of the resistor R1 and the resistor R2) is a fixed reference point voltage (about 0.6V), the voltage V+ of the non-inverting input of the comparator U1-B > the voltage V- of the inverting input of the comparator U1-B, the output of the comparator U1-B outputs high level; the +5V power supply charges the capacitor C3 through the resistor R4. In the comparator U1-A, the +5V power supply charges the capacitor C4 through the resistor R5, and after the charging is completed, the voltage of the F point (i.e. the common terminal of the resistor R5 and the resistor R6) is about 4.6V. Since the charging and discharging time τ1 (τ1=R4×C3) of the capacitor C3 is faster than the charging and discharging time τ2 (τ2=R5×C4) of the capacitor C4, τ1<τ2, the voltage V- of the inverting input of the comparator U1-A < the voltage V+ of the non-inverting input of the comparator U1-A, the output of the comparator U1-A outputs low level, the MOS transistor U2 is in the cut-off state, the EN pin of the special chip is set to high level (the EN pin low level is effective), and the motor normally operates. It can be seen that when the current of the three-phase inverter negative terminal (such as the terminal NU or the terminal NV or the terminal NW) of the IPM module does not overcurrent, the normal working state of the motor is not affected.

[0096] When the current of the three-phase inverter negative terminal (such as the terminal NU or the terminal NV or the terminal NW) of the IPM module overcurrent, in the comparator U1-B, the voltage V- of the inverting input of the comparator U1-B > the voltage V+ of the non-inverting input of the comparator U1-B, the output of the comparator U1-B flips, the output of the comparator U1-B outputs low level, and the capacitor C3 begins to discharge. In the comparator U1-A, the voltage V- of the inverting input of the comparator U1-A < the voltage V+ of the non-inverting input of the comparator U1-A, the output of the comparator U1-A outputs high level, the MOS transistor U2 is in the saturation state, the EN pin of the special chip is set to low level, and the motor stops operating. It can be seen that when the current of the three-phase inverter negative terminal (such as the terminal NU or the terminal NV or the terminal NW) of the IPM module overcurrent, the overcurrent timing stop and self-start function circuit can quickly respond, turn off the driving output signal of the special chip, stop the motor, and avoid the problems of power module short circuit, breakdown, and burst caused by overcurrent.

[0097] Referring to ​In the shown example, when the motor stops running, the voltage V- of the inverting input terminal of the comparator U1-B approaches 0V, and the voltage V+ of the non-inverting input terminal of the comparator U1-B > the voltage V- of the inverting input terminal of the comparator U1-B. The +5V power supply charges the capacitor C3 through the resistor R4, and the voltage value of the capacitor C3 starts to slowly rise. The time period during which the voltage value of the capacitor C3 slowly rises to the voltage value of the capacitor C4 is the shutdown locking time, and the locking time is approximately equal to 3τ1 (τ1=R4xC3). It can be seen that, before the overcurrent of the three-phase inverter negative terminal (such as the terminal NU or the terminal NV or the terminal NW) of the IPM module is removed, the shutdown locking is used to delay the start-up, so as to avoid problems such as short circuit, breakdown and burst of the power module caused by the expansion of the fault due to the continuous overcurrent.

[0098] The self-starting is restored. In the shutdown locking stage, when the voltage value of the capacitor C3 slowly rises to be greater than the voltage value of the capacitor C4, the comparator U1-A starts to restore to the low voltage output, the MOS tube U2 is in the cut-off state, the EN pin of the special chip is in the high level, and the motor self-starting is restored to the normal operation. It can be seen that, after the overcurrent problem of the three-phase inverter negative terminal (such as the terminal NU or the terminal NV or the terminal NW) of the IPM module is removed, the shutdown locking is ended, and the motor is restored to the normal operation.

[0099] In the scheme of the present application, mainly composed of a comparator, a resistor capacitor and a MOS tube, the timing opening of the MOS tube is controlled by using the setting of the charging and discharging time difference of the resistor capacitor, so that the output current value of the power module can be detected in real time, and the power module is effectively protected. The power module is, for example, a power device in a three-phase inverter bridge of a motor, or a power device in an intelligent power module (IPM module) of a motor, etc. The overcurrent protection provided by the scheme of the present application has the functions of locking and self-starting, and has the characteristics of simple and reliable circuit design, low cost, easy implementation and promotion, etc.

[0100] Since the processing and functions realized by the motor of the present embodiment are basically corresponding to the embodiments, principles and examples of the device, the descriptions of the present embodiment that are not elaborated can be seen in the related descriptions in the foregoing embodiments, which will not be repeated here.

[0101] According to the embodiments of the present application, an air conditioner corresponding to the protection device is also provided. The air conditioner can include: the protection device described above, or the motor controller described above, or the frequency converter described above, or the motor described above.

[0102] 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 device, the descriptions of the present embodiment that are not elaborated can be seen in the related descriptions in the foregoing embodiments, which will not be repeated here.

[0103] In summary, the person skilled in the art can easily understand that the above-mentioned advantageous modes can be freely combined and superimposed without conflict.

[0104] The above merely provides an example of the present application, but is not intended to limit the present application. The present application can be variously changed and modified by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall fall within the scope of claims of the present application.

Claims

1. A protection device, characterized in that The protection device is arranged between three-phase inverter negative terminals of an IPM module of the motor and an enable pin of a driving control chip of the motor. The protection device comprises a sampling module, a comparison module, a protection module and a switch module. The sampling module is configured to sample current from the three-phase inverter negative terminals of the IPM module to obtain sampling current of the IPM module. The comparison module is configured to set a reference threshold and compare the sampling current of the IPM module with the reference threshold to obtain a comparison result. The protection module is configured to output a first protection signal when the comparison result is a first result that the sampling current of the IPM module does not exceed a threshold, output a second protection signal when the comparison result is a second result that the sampling current of the IPM module exceeds the threshold, and output the first protection signal again after a set time of outputting the second protection signal. The switch module is configured to control the driving control chip to work when the first protection signal is received and control the driving control chip to stop working when the second protection signal is received. The comparison module and the protection module have overcurrent comparison function, shutdown locking function and self-starting function.

2. The protection device according to claim 1, characterized in that The sampling module comprises a first resistor module, a second resistor module and a first capacitor module. The three-phase inverter negative terminals of the IPM module are connected to ground through the first resistor module. The three-phase inverter negative terminals of the IPM module are also connected to ground through the second resistor module and the first capacitor module.

3. The protection device of claim 1, wherein The comparison module comprises a third resistor module, a fourth resistor module, a second capacitor module and a first comparison module. A preset positive direct current power supply is connected to ground through the third resistor module and the fourth resistor module. The common terminal of the third resistor module and the fourth resistor module is connected to ground through the second capacitor module. The common terminal of the third resistor module and the fourth resistor module can output the reference threshold to the same-phase input terminal of the first comparison module. The sampling current output by the sampling module can be input to the opposite-phase input terminal of the first comparison module. The output terminal of the first comparison module can output the comparison result to the protection module.

4. The protection device of claim 1, wherein The protection module comprises a fifth resistor module, a sixth resistor module, a third capacitor module, a fourth capacitor module and a second comparison module; wherein, The comparison result output by the comparison module can be input to the inverting input end of the second comparison module; a preset positive direct current power supply is grounded through the fifth resistor module and the third capacitor module; the common end of the fifth resistor module and the third capacitor module is connected to the inverting input end of the second comparison module; A preset positive direct current power supply is grounded through the sixth resistor module and the fourth capacitor module; the common end of the sixth resistor module and the fourth capacitor module is connected to the non-inverting input end of the second comparison module; the output end of the second comparison module can output the first protection signal or the second protection signal to the control end of the switch module.

5. The protection device according to claim 4, characterized in that The protection module further comprises at least one of a seventh resistor module and a fifth capacitor module; wherein, The seventh resistor module is arranged between the common end of the sixth resistor module and the fourth capacitor module and the ground; The fifth capacitor module is arranged between the power supply end of the second comparison module and the ground.

6. The protection device of claim 1, wherein The switch module comprises an eighth resistor module and a switch tube; wherein, The first protection signal or the second protection signal output by the protection module can be input to the control end of the switch tube; a preset positive direct current power supply is connected to the control end of the switch tube through the eighth resistor module; The first connection end of the switch tube is connected to the enable pin of the drive control chip of the motor; the second connection end of the switch tube is grounded.

7. An electric machine controller characterized by The protection device comprises: The protection device according to any one of claims 1 to 6.

8. A frequency converter, characterized in that The protection device comprises: The protection device comprises:

9. An electric machine characterized by The protection device according to any one of claims 1 to 6, the motor controller according to claim 7, or the frequency converter according to claim 8. The protection device according to any one of claims 1 to 6, the motor controller according to claim 7, the frequency converter according to claim 8, or the motor according to claim 9.

10. An air conditioner characterized by comprising: ​ ​

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