Motor short circuit protection device and system

Abstract

The invention discloses a motor short circuit protection device and system. The device comprises a short circuit protection unit; the input end of the short-circuit protection unit is connected with at least two phases of the three-phase power supply end of the motor, and the output end of the short-circuit protection unit is connected with the control ends of three first driving tubes in three first bridge arms in the motor driving circuit; or the output end of the short circuit protection unit is connected with the control ends of three second driving tubes in three second bridge arms in the motor driving circuit; the short-circuit protection unit is configured to output an active short-circuit signal to the control end of the first driving tube or the second driving tube when the voltage of the three-phase power supply end exceeds a preset voltage; the rotating speed of the motor exceeds the preset maximum rotating speed; and the voltage of the three-phase power supply end exceeds the preset voltage.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of motor control, and in particular, to a motor short - circuit protection device and system. Background Art

[0002] During the operation of a motor, a "runaway" phenomenon may occur, that is, the speed of the motor exceeds the normal operating range. When the motor runs away, active short - circuit (ASC) protection technology is required to prevent the power module from being over - voltage breakdown.

[0003] Taking a motor system equipped with a three - phase IGBT power module as an example, by turning off the three upper - arm transistors of the IGBT and simultaneously turning on the three lower - arm transistors, or turning on the three upper - arm transistors of the IGBT and simultaneously turning off the three lower - arm transistors, the motor drive system can be brought into the active short - circuit protection state. When in the active short - circuit protection state, the stator winding of the motor and the IGBT of the lower arm form a closed - loop circuit, and the back - electromotive - force energy generated by the motor is released through the stator winding, and a corresponding braking torque is generated at the output end of the motor.

[0004] In the prior art, it is usually necessary to perform software condition judgment to determine whether to enter the short - circuit protection state, and rely on software control to enter the short - circuit protection state. This also means that when it is necessary to enter the short - circuit protection state, the low - voltage power supply and control of the controller must be in good condition. Summary of the Invention

[0005] The present invention provides a motor short - circuit protection device and system, so as to achieve the purpose of realizing short - circuit protection control through a pure hardware circuit. Even when the power supply and control of the controller are interrupted, it can ensure that the controller enters the short - circuit protection state, avoiding the system from outputting too high a voltage, causing personal injury and secondary damage to the electric drive system.

[0006] In a first aspect, an embodiment of the present invention provides a motor short - circuit protection device, including: a short - circuit protection unit;

[0007] The input end of the short - circuit protection unit is connected to at least two phases of the three - phase power supply end of the motor, and the output end of the short - circuit protection unit is connected to the control ends of three first drive transistors in three first bridge arms in the motor drive circuit;

[0008] Alternatively, the output end of the short - circuit protection unit is connected to the control ends of three second drive transistors in three second bridge arms in the motor drive circuit;

[0009] The short - circuit protection unit is configured to output an active short - circuit signal to the control end of the first drive transistor or the second drive transistor when the voltage at the three - phase power supply end exceeds a preset voltage;

[0010] When the rotational speed of the motor exceeds the preset maximum rotational speed and the voltage at the three-phase power supply terminal exceeds the preset voltage.

[0011] Optionally, the output terminal of the short-circuit protection unit is also connected to the fault pin of the drive chip;

[0012] The drive chip is configured to drive the motor drive circuit and enter a fault state when receiving the active short-circuit signal, and stop outputting the drive signal.

[0013] Optionally, the input terminal of the short-circuit protection unit is connected to two phases of the three-phase power supply terminal of the motor.

[0014] Optionally, the short-circuit protection unit includes: a rectification module and a voltage conversion module;

[0015] At least two phases of the three-phase power supply terminal are connected to the input terminal of the rectification module, the rectification module is connected to the voltage conversion module, and the output terminal of the voltage conversion module serves as the output terminal of the short-circuit protection unit.

[0016] Optionally, the preset voltage is configured as the minimum startup voltage of the voltage conversion module.

[0017] Optionally, the short-circuit protection unit further includes: a transformer module and a voltage stabilization module;

[0018] At least two phases of the three-phase power supply terminal are connected to the input terminal of the transformer module, the transformer module is connected to the rectification module, and the rectification module is connected to the voltage conversion module through the voltage stabilization module.

[0019] Optionally, a first diode is further configured at the output terminal of the short-circuit protection unit.

[0020] Optionally, when the drive chip receives the active short-circuit signal and enters a fault state and stops outputting the drive signal, the active short-circuit signal controls three of the first drive tubes or three of the second drive tubes to conduct.

[0021] In a second aspect, an embodiment of the present invention further provides a system, including any one of the motor short-circuit protection devices described in the embodiments of the present invention.

[0022] Optionally, the motor drive circuit is configured with a drive chip, and the output terminal of the drive chip is connected to the control terminal of the motor drive circuit through a second diode.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a motor short-circuit protection device, which includes a short-circuit protection unit. The short-circuit protection unit is configured to obtain power from the three-phase power supply terminals of the motor, and the output terminal of the short-circuit protection unit is connected to the control terminal of the driving transistor in the upper three-arm or the lower three-arm of the motor driving circuit. When the voltage at the three-phase power supply terminals exceeds a preset voltage, the short-circuit protection unit outputs an active short-circuit signal to control the conduction of the connected driving transistor. When the driving transistor in the upper three-arm is turned off, the short-circuit protection mode is entered. In this solution, the back electromotive force generated by the rotation of the motor is corresponding to the motor speed. Whether the motor is overspeed is judged from the back electromotive force, and then power is taken from the back electromotive force in the overspeed state of the motor to generate an active short-circuit signal for specifying the conduction of the driving transistor, so as to enable the specified controller or motor driving circuit to enter the short-circuit protection mode and avoid overvoltage damage to the device. When the short-circuit protection is realized through the short-circuit protection unit in this solution, software control is not required throughout the process, and the short-circuit protection unit does not require external power supply. Regardless of the working state of the motor controller, as long as the motor exceeds the preset maximum speed, the short-circuit protection of the motor controller can be completely realized by relying on a pure hardware circuit, and the reliability is higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is the structural block diagram of the motor short-circuit protection device in the embodiment;

[0025] Figure 2 is the structural block diagram of another motor short-circuit protection device in the embodiment;

[0026] Figure 3 is the structural block diagram of yet another motor short-circuit protection device in the embodiment;

[0027] Figure 4 is the system structural block diagram in the embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The present invention will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. In addition, it should be noted that for the sake of description, only parts related to the present invention are shown in the drawings, not all structures.

[0029] Embodiment 1

[0030] Figure 1 is the structural block diagram of the motor short-circuit protection device in the embodiment. Refer to Figure 1 , the motor short-circuit protection device includes: a short-circuit protection unit 100;

[0031] The input end of the short - circuit protection unit 100 is connected to at least two of the three - phase power supply terminals of the motor 1, and the output end of the short - circuit protection unit 100 is connected to the control ends of the three first driving transistors in the three first bridge arms in the power module 2;

[0032] Alternatively, the output end of the short - circuit protection unit 100 is connected to the control ends of the three second driving transistors in the three second bridge arms in the power module 2.

[0033] Exemplarily, in this solution, the functions of the short - circuit protection unit 100 at least include rectification and voltage conversion. Among them, rectification is mainly used to convert the alternating current obtained from the three - phase power supply terminal into direct current;

[0034] Voltage conversion is mainly used to convert the above - mentioned direct current into a control signal that can adapt to the driving transistors in the power module 2.

[0035] Exemplarily, in this solution, there is no specific limitation on the design method of the short - circuit protection unit 100 (including the selected chip model and circuit design method), and it can be freely selected according to requirements.

[0036] Exemplarily, in this solution, the power module 2 is used to realize the drive (power) control of the motor 1 to control the operation of the motor 1;

[0037] Among them, the drive chip 3 is configured to generate and output a drive control signal acting on the power module 2 to realize the on - off control of the driving transistors in the power module 2 as required.

[0038] In this solution, the short - circuit protection unit 100 is configured to output an active short - circuit signal to the control end of the first driving transistor or the second driving transistor when the voltage at the three - phase power supply terminal exceeds a preset voltage.

[0039] In this solution, the output end of the short - circuit protection unit 100 is directly connected to the control end of the driving transistor in the power module 2, that is, the active short - circuit signal output by the short - circuit protection unit 100 can directly control the conduction of the corresponding driving transistor.

[0040] In this solution, the first bridge arm can be the upper bridge arm in the motor drive circuit, the first driving transistors include all the driving transistors in the upper bridge arm, the second bridge arm can be the lower bridge arm in the motor drive circuit, and the second driving transistors include all the driving transistors in the lower bridge arm.

[0041] Exemplarily, in this solution, the circuit structure of the (three - phase) motor drive circuit is the same as that of the prior art, and its specific content will not be elaborated here.

[0042] In this solution, it is set that when the voltage at the three - phase power supply terminal exceeds the preset voltage, the speed of the motor 1 exceeds the preset maximum speed.

[0043] In this solution, the preset voltage and the preset maximum speed can be determined through calibration tests, experience, etc. Among them, when the speed of the motor 1 is set to exceed the preset maximum speed, the short-circuit protection for the power module 2 should be activated to prevent the devices in the power module 2 from being broken down due to overvoltage.

[0044] In this solution, the active short-circuit signal is used to control the conduction of the driving transistors in the upper bridge arm or the lower bridge arm when the speed of the motor 1 exceeds the preset maximum speed, so as to achieve the short-circuit protection for the power module 2. Specifically:

[0045] It is set that the starting voltage of the short-circuit protection unit 100 is obtained by rectifying and regulating the line voltages of two or three phases in the three-phase AC line;

[0046] The increase in the motor speed will cause the back electromotive force of the motor to increase. The increase in the back electromotive force of the motor will cause the line voltages of the three-phase AC line of the motor to increase, and the DC voltage obtained after rectifying and regulating will also increase simultaneously. Therefore, this DC voltage can be used to reflect the speed of the motor;

[0047] That is, when the DC voltage reaches the starting voltage of the short-circuit protection unit 100, the short-circuit protection unit 100 generates an active short-circuit signal;

[0048] When the driving chip 3 stops working due to low-voltage power failure and there is no driving signal output for the upper and lower bridge arms and the switching transistors are not conducting;

[0049] Taking the connection between the short-circuit protection unit 100 and the lower bridge arm as an example when the motor is overspeed, there is no driving signal output for the upper bridge arm and the switching transistor is not conducting, and the lower bridge arm is driven by the short-circuit protection unit 100 to make the switching transistor conduct. At this time, the power module 2 enters the short-circuit protection mode, and the back electromotive force generated by the motor overspeed will not cause the overvoltage breakdown of the devices.

[0050] This embodiment provides a motor short-circuit protection device, which includes a short-circuit protection unit. It is set that the short-circuit protection unit draws power from the three-phase power supply terminals of the motor, and the output terminal of the short-circuit protection unit is connected to the control terminal of the driving transistor in the upper half-bridge arm or the lower half-bridge arm in the motor driving circuit. It is set that when the voltage at the three-phase power supply terminals exceeds the preset voltage, the short-circuit protection unit outputs an active short-circuit signal to control the conduction of the connected driving transistor. Then, when the driving transistor in the other half-bridge arm is turned off, it enters the short-circuit protection mode;

[0051] In this solution, the back electromotive force generated by the rotation of the motor is made corresponding to the motor speed. Whether the motor is overspeed is judged from the back electromotive force, and then power is drawn from the back electromotive force in the overspeed state of the motor to be used for generating an active short-circuit signal for making a specified driving transistor conduct, so as to make the specified controller or the motor driving circuit enter the short-circuit protection mode and prevent the devices from being damaged due to overvoltage;

[0052] When the short - circuit protection is realized through the short - circuit protection unit in this solution, the whole process does not require software control, and the short - circuit protection unit does not require external power supply. Regardless of the working state of the motor controller, as long as the motor exceeds the preset maximum speed, the over - voltage protection of the motor controller can be completely realized by relying on a pure hardware circuit, with higher reliability and lower cost.

[0053] Exemplarily, in this embodiment, one path is output from the output end of the short - circuit protection unit to the fault terminal of the drive circuit to make the drive circuit enter the fault state and stop output. Further, all six - phase bridge arms are turned off, and the output end of the short - circuit protection unit directly drives the lower three - phase bridge (or the upper three - phase bridge) to make the lower three - phase bridge (or the upper three - phase bridge) conduct, and the controller enters the active short - circuit protection state.

[0054] Reference Figure 1 , on the basis of the foregoing solution, in an implementable solution, the output end of the short - circuit protection unit 100 is also connected to the fault pin of the drive chip 3;

[0055] The drive chip 3 is configured to drive the power module 2 and stop working when receiving the active short - circuit signal.

[0056] Exemplarily, in this solution, it is set that the drive chip 3 receives the active short - circuit signal through the fault pin and stops working when receiving the active short - circuit signal.

[0057] In this solution, when the controller fails and cannot control the motor, if the motor is overspeed at this time, the drive chip 3 receives the active short - circuit signal, reports the fault and stops working, so that there is no drive signal output for the upper and lower bridge arms and the switching tubes do not conduct;

[0058] The lower bridge arm is driven by the short - circuit protection unit 100 to conduct. At this time, the power module 2 enters the short - circuit protection mode, and the back electromotive force generated by the overspeed of the motor at this time will not cause over - voltage breakdown of the device.

[0059] Further, on the basis of the solution where the output end of the short - circuit protection unit 100 is connected to the fault pin of the drive chip 3, after configuring the drive chip 3 to stop working when receiving the active short - circuit signal, the active short - circuit signal controls the first drive tube or the second drive tube to conduct.

[0060] Exemplarily, in this solution, a corresponding control chip can be configured in the short - circuit protection unit 100, and the control chip is used to control the active short - circuit signal to be output to the drive chip 3 first, and then the active short - circuit signal is output to the first drive tube or the second drive tube.

[0061] Exemplarily, in this solution, when the motor overspeed occurs, first control the drive chip 3 to stop working, thereby turning off the first drive transistor and the second drive transistor, and then control the first drive transistor or the second drive transistor to conduct to achieve short-circuit protection control, which can effectively achieve active short-circuit protection for the power module 2.

[0062] Based on the Figure 1 solution shown, in an implementable solution, the input end of the short-circuit protection unit is connected to two phases of the three-phase power supply end of the motor.

[0063] In this solution, configure the short-circuit protection unit to convert two-phase alternating current into direct current, which can reduce the design difficulty of the short-circuit protection unit and reduce costs.

[0064] Figure 2 is another structural block diagram of the motor short-circuit protection device in the embodiment. Refer to Figure 2 , the short-circuit protection unit includes: a rectification module 101 and a voltage conversion module 102;

[0065] At least two phases of the three-phase power supply end are connected to the input end of the rectification module 101. The rectification module 101 is connected to the voltage conversion module 102, and the output end of the voltage conversion module 102 serves as the output end of the short-circuit protection unit.

[0066] Exemplarily, in this solution, the rectification module 101 can rectify based on an uncontrolled method or other controllable rectification methods can also be used for rectification.

[0067] Exemplarily, in this solution, the voltage conversion module 102 is used to achieve voltage conversion and voltage stabilization for the direct current output by the rectification module 101.

[0068] Furthermore, in this solution, configure the preset voltage to be the minimum startup voltage of the voltage conversion module 102, that is, when the (alternating current) voltage at the three-phase power supply end exceeds the preset voltage, the voltage conversion module 102 starts to work and generates and outputs an active short-circuit signal.

[0069] Figure 3 is yet another structural block diagram of the motor short-circuit protection device in the embodiment. Refer to Figure 3 , based on the Figure 2 solution shown, in an implementable solution, the short-circuit protection unit further includes: a transformer module 103 and a voltage stabilization module 104;

[0070] At least two phases of the three-phase power supply end are connected to the input end of the transformer module 103. The transformer module 103 is connected to the rectification module 101, and the rectification module 101 is connected to the voltage conversion module 102 through the voltage stabilization module 104.

[0071] Exemplarily, in this solution, the voltage conversion module 102 uses a DCDC. In addition, the voltage conversion module 102 can also use a BUCK buck circuit topology, a flyback circuit topology, etc.

[0072] Based on the Figure 4 solution shown, in an implementable solution, the output end of the voltage conversion module is also connected to the fault pin of the drive chip;

[0073] The drive chip is configured to drive the motor drive circuit and stop working when receiving an active short circuit signal.

[0074] Exemplarily, in this solution, two phases of the three-phase alternating current are sent to the rectification module 101 for rectification after being converted by the transformer module 103. After rectification, it is regulated by the voltage regulation module 104. When the voltage after regulation reaches the minimum startup voltage of the voltage conversion module 102 (DCDC), the voltage conversion module 102 starts to work;

[0075] The voltage conversion module 102 converts the regulated voltage into the voltage required for the operation of the power module 2 and outputs it to the gate of the driving transistor in the lower bridge arm and the fault pin of the drive chip 3.

[0076] In this solution, the startup voltage of the DCDC is obtained by converting the line voltage of two phases in the three-phase alternating current through circuits such as rectification and voltage regulation;

[0077] The increase in the motor speed will cause the back electromotive force of the motor to increase. The increase in the back electromotive force of the motor will cause the line voltage of the three-phase alternating current of the motor to increase, and the voltage of the direct current obtained after rectification and voltage regulation will also increase simultaneously. Therefore, this direct current voltage can be used to reflect the motor speed;

[0078] According to the design parameters of the motor and the motor controller, the overspeed is determined, and thus the value of the direct current voltage after rectification and voltage regulation at the overspeed can be determined. This voltage value is set as the minimum startup voltage of the DCDC circuit. When the direct current voltage after rectification and regulation is higher than the minimum startup voltage, the DCDC circuit starts and outputs voltage to the gate of the lower bridge arm and the fault pin of the drive chip;

[0079] When problems such as low-voltage power-off occur in the (motor) controller, the drive chip 3 stops working due to low-voltage power-off, and no drive signals are output for the upper and lower bridge arms, and the switching tubes do not conduct;

[0080] At this time, if the motor is overspeed, no drive signal is output for the upper bridge arm and the switching tube does not conduct, and the lower bridge arm is driven by the active short circuit signal to turn on the switching tube, entering the ASC mode. At this time, the back electromotive force generated by the overspeed of the motor will not cause the controller to be damaged due to overvoltage breakdown;

[0081] When the controller fails and is unable to control the motor, if the motor is overspeed at this time, the active short - circuit signal first acts on the drive chip 3. The drive chip 3 reports a fault to stop working, so that there is no drive signal output for the upper and lower bridge arms and the switching tubes are not turned on;

[0082] The lower bridge arm is driven by the active short - circuit signal to turn on the switching tube and enter the ASC mode. At this time, the back electromotive force generated by the overspeed motor will not cause the controller to be damaged due to overvoltage breakdown.

[0083] Exemplarily, in this solution, the ASC mode is set as the active short - circuit protection mode. In this mode, the upper three bridges of the motor drive circuit are turned on and the lower three bridges are turned off, or the upper three bridges are turned off and the lower three bridges are turned on, which is a protection technology to prevent the power module from being broken down by overvoltage.

[0084] In Figure 1 On the basis of the solution shown, in an implementable solution, a first diode is also configured at the output end of the short - circuit protection unit 100.

[0085] Exemplarily, in this solution, the first diode is used for the unidirectional output of the active short - circuit signal to avoid signal interference between the short - circuit protection unit 100 and the drive chip 3.

[0086] Embodiment 2

[0087] This embodiment proposes a system, including any one of the motor short - circuit protection devices described in Embodiment 1.

[0088] Figure 4 It is the system structure block diagram in the embodiment. Referring to Figure 4 , on the basis of the content described in Embodiment 1, in an implementable solution, the system includes:

[0089] The first drive chip 31, the second drive chip 32, the third drive chip 33, the fourth drive chip 34, the fifth drive chip 35, and the sixth drive chip 36;

[0090] Among them, it is set that the first drive chip 31, the second drive chip 32, and the third drive chip 33 are respectively connected to the gates of the drive tubes of the lower bridge arm in the power module 2 through a diode;

[0091] It is set that the fourth drive chip 34, the fifth drive chip 35, and the sixth drive chip 36 are connected to the gates of the drive tubes of the upper bridge arm in the power module 2;

[0092] It also includes a transformer module 103, a rectification module 101, a voltage - stabilizing module 104, and a voltage - conversion module 102. Among them, two phases of the three - phase alternating current are connected to the input end of the transformer module 103;

[0093] The transformer module 103 is connected to the voltage stabilizing module 104 through the rectification module 101, and the voltage stabilizing module 104 is connected to the voltage conversion module 102;

[0094] The output terminals of the voltage conversion module 102 are respectively connected to the gates of the driving transistors of the lower bridge arm in the power module 2 through a diode, and are connected to the fault pins of the first to sixth driving chips through a diode.

[0095] In this embodiment, the working mode and beneficial effects of the motor short-circuit protection device are the same as the corresponding content described in the first embodiment, and the specific content will not be elaborated here.

[0096] Note that the above is only the preferred embodiment of the present invention and the technical principles applied. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein. Various obvious changes, re-adjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments. Without departing from the concept of the present invention, more other equivalent embodiments can be included, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A motor short-circuit protection device, characterized in that: include: Short circuit protection unit; The input end of the short-circuit protection unit is connected to at least two phases of the three-phase power supply end of the motor, and the output end of the short-circuit protection unit is connected to the control ends of three first driving tubes in the three first bridge arms in the motor driving circuit; Alternatively, the output end of the short-circuit protection unit is connected to the control ends of three second driving transistors in three second bridge arms in the motor driving circuit; The short-circuit protection unit is configured to output an active short-circuit signal to the control end of the first drive tube or the second drive tube when the voltage of the three-phase power supply end exceeds a preset voltage; When the rotation speed of the motor exceeds the preset maximum rotation speed and the voltage of the three-phase power supply terminal exceeds the preset voltage.

2. The motor short-circuit protection device according to claim 1, characterized in that: The output end of the short circuit protection unit is also connected to the fault pin of the driver chip; The driving chip is configured to drive the motor driving circuit, and enter a fault state upon receiving the active short-circuit signal, and stop outputting the driving signal.

3. The motor short-circuit protection device according to claim 1, characterized in that: The input end of the short-circuit protection unit is connected to two phases of the three-phase power supply end of the motor.

4. The motor short-circuit protection device according to claim 3, characterized in that: The short-circuit protection unit includes: a rectifier module and a voltage conversion module; At least two phases of the three-phase power supply end are connected to the input end of the rectifier module, the rectifier module is connected to the voltage conversion module, and the output end of the voltage conversion module serves as the output end of the short-circuit protection unit.

5. The motor short-circuit protection device according to claim 4, characterized in that: The preset voltage is configured as the minimum starting voltage of the voltage conversion module.

6. The motor short-circuit protection device according to claim 4, characterized in that: The short-circuit protection unit also includes: a transformer module and a voltage stabilizing module; At least two phases of the three-phase power supply end are connected to the input end of the transformer module, the transformer module is connected to the rectifier module, and the rectifier module is connected to the voltage conversion module through the voltage stabilizing module.

7. The motor short-circuit protection device according to claim 1, characterized in that: The output end of the short-circuit protection unit is also configured with a first diode.

8. The motor short-circuit protection device according to claim 2, characterized in that: The driver chip is configured to enter a fault state when receiving the active short-circuit signal, and after stopping outputting the drive signal, the active short-circuit signal controls the three first drive tubes or the three second drive tubes to be turned on.

9. A system, characterized in that: A motor short-circuit protection device comprising any one of claims 1 to 8.

10. The system according to claim 9, characterized in that The motor driving circuit is provided with a driving chip, and the output end of the driving chip is connected to the control end of the motor driving circuit through a second diode.

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