Motor control circuit and system

Abstract

According to the motor control circuit and system provided by the embodiment of the utility model, the temperature of the stator coil of the motor is sensed through the thermosensitive temperature switch, when the temperature of the stator coil of the motor is greater than or equal to the preset temperature, the power supply path of the first power supply voltage is cut off, and the DC bus voltage output by the switching module is reduced to perform motor overheating protection; the first voltage sampling module outputs first sampling voltage representing motor overheating, the second sampling voltage outputting second sampling voltage representing motor overheating, the first voltage sampling module outputs first sampling voltage representing motor overheating, and the control module outputs a second control signal to control the motor to stop; and when the direct-current bus voltage is reduced to the working voltage of the power conversion module, the control module is reset, and the motor stops. According to the mode of controlling the motor to stop, multi-stage protection of motor overheating can be realized, and the reliability of a motor control circuit and system is improved. In addition, compared with a mode that a thermocouple is used for controlling motor drive closing, the thermosensitive temperature switch is low in cost and small in size, and the internal space of the motor is enlarged.

Description

Technical Field

[0001] The utility model relates to the field of motors, and in particular to a motor control circuit and system. Background Art

[0002] The use of motors has penetrated almost into all walks of life. However, motor burnout and even safety accidents may occur during the use of motors. The shutdown will cause economic losses. Therefore, good protection of motors is of great significance to improve production efficiency, increase economic benefits and ensure safe production.

[0003] The overheat protection in motor protection is a protective measure implemented to prevent the motor from burning out due to long-term operation. In the prior art, a thermocouple is connected in series in the middle of the motor phase line to directly measure the temperature for motor overheat protection. However, the cost of using thermocouples is high, and being set in the middle of the motor phase line causes tight space inside the motor. Utility Model Content

[0004] The utility model provides a motor control circuit and system, which are used to solve the problem in the prior art that thermocouples are used to protect the motor in the motor control system from over-temperature, resulting in tight internal space of the motor in the motor control system and high use cost.

[0005] In a first aspect, the utility model provides a motor control system, including: a thermistor temperature switch, a switching module, a power conversion module, a motor drive module, a first voltage sampling module and a control module;

[0006] The thermistor temperature switch receives a first supply voltage and outputs a protection signal according to the detected motor temperature;

[0007] The switching module receives the protection signal, the first control signal and the power input signal, and outputs a DC bus voltage;

[0008] The power conversion module converts the received DC bus voltage into a first power supply voltage and a second power supply voltage, wherein the first power supply voltage is provided to the switching module for power supply, and the second power supply voltage is provided to the control module for power supply;

[0009] The first voltage sampling module samples the DC bus voltage and outputs a first sampled voltage;

[0010] The control module outputs the first control signal and the second control signal according to the first sampled voltage;

[0011] The motor driving module receives the DC bus voltage and the second control signal to control the motor;

[0012] The thermistor temperature switch is turned on when it is detected that the temperature of the motor is normal, and outputs a protection signal for providing the first power supply voltage. The switching module receives the first power supply voltage, and the motor works normally.

[0013] The thermistor temperature switch is turned off when abnormal motor temperature is detected, disconnecting the power supply path provided by the first power supply voltage to the switching module, outputting a protection signal for disconnecting the power supply, and performing motor overheat protection.

[0014] In a possible implementation, the motor control circuit further includes an energy storage module connected between the DC bus voltage and the ground terminal; the switching module includes:

[0015] Relay, including a relay coil and a relay switch;

[0016] A current limiting module is connected in parallel with the relay switch and receives the power input signal, and an output end of the current limiting module is connected to the power conversion module;

[0017] A relay control module receives the first control signal;

[0018] When the motor control circuit is powered on and started, the power input signal outputs the DC bus voltage through the current limiting module, and the DC bus voltage charges the energy storage module. After the energy storage module reaches a threshold, the control module outputs the first control signal, and the first control signal controls the switch in the relay control module to turn on, so as to turn on the current path between the relay coil and the ground terminal. The relay switch is turned on, the DC bus voltage is output via the relay switch, and the DC bus voltage increases.

[0019] In one possible implementation, when the thermistor temperature switch detects abnormal motor temperature, the thermistor temperature switch is turned off, disconnecting the power supply path provided by the first power supply voltage to the switching module, and the current path between the relay coil and the ground terminal is turned off. The DC bus voltage is output through the current limiting module, and the DC bus voltage is reduced, thereby performing overheat protection on the motor.

[0020] In one possible implementation, when the thermistor temperature switch detects abnormal motor temperature, the first voltage sampling module samples the DC bus voltage output by the switching module and outputs the first sampled voltage, the control module receives the first sampled voltage and outputs the second control signal to the motor drive module, and the motor drive module controls the motor to stop.

[0021] In one possible implementation, when the thermistor temperature switch detects abnormal motor temperature, the DC bus voltage output by the switching module drops to below the operating voltage of the power conversion module, the power conversion module stops voltage conversion, the control module is reset, and the motor stops.

[0022] In one possible implementation, the motor control circuit also includes a second voltage sampling module, which is connected between the thermistor temperature switch and the control module, samples the protection signal, and outputs a second sampling voltage; when the thermistor temperature switch detects abnormal motor temperature, the control module receives the second sampling voltage and outputs the second control signal to control the motor to stop.

[0023] In a possible implementation, the thermistor temperature switch senses the temperature of the stator coil of the motor, and when the temperature of the stator coil of the motor is greater than or equal to a preset temperature, the thermistor temperature switch detects that the motor temperature is abnormal.

[0024] In a possible implementation, the power input signal is an AC power input signal or a DC power input signal.

[0025] In a possible implementation, the first voltage sampling module includes a first resistor, a second resistor, a third resistor and a first capacitor;

[0026] The first end of the first resistor is electrically connected to the positive electrode of the energy storage module and inputs the DC bus voltage, and the second end of the first resistor is electrically connected to the first end of the second resistor and the first end of the third resistor;

[0027] The second end of the second resistor is electrically connected to the first end of the first capacitor and the ground end;

[0028] The second end of the third resistor is electrically connected to the second end of the first capacitor and the control module to output the first sampling voltage.

[0029] In a possible implementation, the first voltage sampling module further includes a first diode;

[0030] An anode of the first diode is electrically connected to the second end of the third resistor, and a cathode of the first diode is electrically connected to a power supply end of the control module.

[0031] In a possible implementation, the relay control module includes: a third diode, a seventh resistor, an eighth resistor, a third capacitor and a first transistor;

[0032] The cathode of the third diode is electrically connected to one end of the relay coil, and the anode of the third diode is electrically connected to the other end of the relay coil and the collector of the first transistor;

[0033] The base of the first transistor is electrically connected to the first end of the seventh resistor, the first end of the eighth resistor and the first end of the third capacitor, and the emitter of the first transistor is electrically connected to the second end of the seventh resistor, the second end of the third capacitor and the ground end;

[0034] The second end of the eighth resistor is electrically connected to the control module to receive the first control signal.

[0035] In a possible implementation, the second voltage sampling module includes a fourth resistor, a fifth resistor, a sixth resistor, and a second capacitor;

[0036] The first end of the fourth resistor is electrically connected to the power supply end of the relay control module, and the second end of the fourth resistor is electrically connected to the first end of the fifth resistor and the first end of the sixth resistor;

[0037] The second end of the fifth resistor is electrically connected to the first end of the second capacitor and the ground end;

[0038] The second end of the sixth resistor is electrically connected to the second end of the second capacitor and the control module.

[0039] In a possible implementation, the second voltage sampling module further includes a second diode;

[0040] An anode of the second diode is electrically connected to the second end of the sixth resistor, and a cathode of the second diode is electrically connected to a power supply end of the control module.

[0041] In a second aspect, the utility model provides a motor control system, comprising:

[0042] AC power supply, providing AC power;

[0043] A rectifier module, wherein the input end of the rectifier module is connected to the AC power supply, and the output end of the rectifier module is connected to the current limiting module, or the input end of the rectifier module is connected to the current limiting module, and the output end of the rectifier module is connected to the power conversion module;

[0044] A motor, and a motor control circuit as described in any one of the first aspects.

[0045] In a third aspect, the utility model provides a motor control system, comprising:

[0046] A DC power supply, providing DC power, wherein an output end of the DC power supply is connected to a current limiting module;

[0047] A motor, and a motor control circuit as described in any one of the first aspects.

[0048] The beneficial effects of the utility model are as follows:

[0049] The utility model provides a motor control circuit and system, wherein a thermistor temperature switch receives a first power supply voltage and outputs a protection signal according to the detected motor temperature. The thermistor temperature switch is turned on when the motor temperature is detected to be normal, and outputs a protection signal for providing the first power supply voltage. The switching module receives the first power supply voltage, and the motor works normally. The thermistor temperature switch is turned off when the motor temperature is detected to be abnormal, and disconnects the power supply path provided by the first power supply voltage to the switching module, and outputs a protection signal for disconnecting the power supply, thereby performing motor overheat protection. The thermistor temperature switch is used to protect the motor. Compared with the use of thermocouples, the thermistor temperature switch has low cost and small size, thereby increasing the space inside the motor.

[0050] In addition, the switching module includes a relay, a current limiting module and a relay control module. When the motor control circuit is powered on and started, the current path between the relay coil and the ground terminal is turned on, the relay switch is turned on, the DC bus voltage is output via the relay switch, and the DC bus voltage increases. When the thermistor temperature switch detects abnormal motor temperature, the thermistor temperature switch is turned off, disconnecting the first power supply voltage from providing the power supply path to the switching module, the current path between the relay coil and the ground terminal is turned off, the DC bus voltage is output via the current limiting module, and the DC bus voltage decreases, thereby performing motor overheat protection; when the thermistor temperature switch detects abnormal motor temperature, the first voltage sampling module samples the DC bus voltage output by the switching module and outputs the first sampling voltage, the control module receives the first sampling voltage, and outputs the second control signal to the motor drive module, and the motor drive module controls the motor to stop; when the thermistor temperature switch detects abnormal motor temperature, the DC bus voltage output by the switching module drops to a level lower than the working voltage of the power conversion module, the power conversion module stops voltage conversion, the control module resets, and the motor stops. Through the above-mentioned method of controlling the motor to stop, multi-level overheat protection of the motor can be achieved, and the reliability of the motor control circuit and system can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0052] Figure 1 A schematic diagram of the structure of a motor control circuit provided by an embodiment of the utility model;

[0053] Figure 2 A schematic diagram of the structure of another motor control circuit provided by an embodiment of the utility model;

[0054] Figure 3 A circuit diagram of a relay control module provided by an embodiment of the utility model;

[0055] Figure 4 A circuit diagram of a first voltage sampling module provided by an embodiment of the utility model;

[0056] Figure 5 A schematic diagram of the structure of another motor control circuit provided by an embodiment of the utility model;

[0057] Figure 6 A circuit diagram of a second voltage sampling module provided by an embodiment of the utility model;

[0058] Figure 7 A schematic diagram of the structure of another motor control circuit provided by an embodiment of the utility model;

[0059] Figure 8 A schematic diagram of the structure of another motor control circuit provided by an embodiment of the utility model;

[0060] Fig. 9 A schematic diagram of the structure of another motor control system provided by an embodiment of the utility model;

[0061] Fig.10 A schematic diagram of the structure of another motor control system provided in an embodiment of the utility model. DETAILED DESCRIPTION

[0062] In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model will be further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0063] In the description of the embodiments of the present application, the terms "first" and "second" are used for descriptive purposes only and should not be understood as suggesting or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0064] As the application of motors becomes more and more widespread, motor burnout and even safety accidents caused by motor use are common, so it is of great significance to protect motors. Overheat protection in motor protection is a protective measure implemented to prevent the motor from burning due to long-term operation. In related technologies, thermocouples are connected in series in the middle of the motor phase line to directly measure the motor temperature for motor overheat protection. However, the cost of using thermocouples is high, and the setting in the middle of the motor phase line causes tight space inside the motor.

[0065] Based on the above problems, the present invention provides a motor control circuit. Figure 1 , which is a schematic diagram of the structure of a motor control circuit disclosed in an embodiment of the utility model, the motor control circuit includes a thermistor temperature switch 109, a switching module 111, a power conversion module 105, a motor drive module 106, a first voltage sampling module 107 and a control module 108;

[0066] The thermistor temperature switch 109 receives the first supply voltage VDD1 and outputs a protection signal according to the detected motor temperature;

[0067] The switching module 111 receives a protection signal, a first control signal CTRL-RELAY and a power input signal, and outputs a DC bus voltage Vin;

[0068] The power conversion module 105 converts the received DC bus voltage Vin into a first power supply voltage VDD1 and a second power supply voltage VDD2, wherein the first power supply voltage VDD1 is provided to the switching module 111 for power supply, and the second power supply voltage VDD2 is provided to the control module 108 for power supply;

[0069] A first voltage sampling module 107, which samples a DC bus voltage Vin and outputs a first sampling voltage V1;

[0070] The control module 108 outputs a first control signal CTL-RELAY and a second control signal Vctrl according to the first sampling voltage V1;

[0071] The motor driving module 106 receives the DC bus voltage Vin and the second control signal Vctrl to control the motor;

[0072] The thermistor temperature switch 109 is turned on when it is detected that the temperature of the motor is normal, and outputs a protection signal for providing the first power supply voltage VDD1. The switching module 111 receives the first power supply voltage VDD1, and the motor works normally.

[0073] The thermistor temperature switch 109 is turned off when abnormal motor temperature is detected, disconnecting the power supply path provided by the first power supply voltage VDD1 to the switching module 111, and outputting a protection signal for disconnecting the power supply to perform motor overheat protection.

[0074] An embodiment of the utility model provides a motor control circuit, in which the thermistor temperature switch is turned on when it detects that the motor temperature is normal, and outputs a protection signal for providing a first power supply voltage. The switching module receives the first power supply voltage, and the motor works normally; the thermistor temperature switch is turned off when it detects that the motor temperature is abnormal, disconnects the power supply path provided by the first power supply voltage to the switching module, outputs a protection signal for disconnecting the power supply, and performs motor overheat protection. The thermistor temperature switch is used to protect the motor. Compared with the use of thermocouples, the thermistor temperature switch has low cost and small size, thereby increasing the space inside the motor.

[0075] In a specific implementation, the control module 108 may be a MCU (Microcontroller Unit).

[0076] The motor control circuit provided in the embodiment of the utility model may further include an energy storage module, and the switching module may include a relay, a current limiting module and a relay control module, such as Figure 2 As shown, the motor control circuit further includes an energy storage module 104 connected between the DC bus voltage and the ground terminal; the switching module 111 includes:

[0077] Relay K1, including a relay coil and a relay switch;

[0078] The current limiting module 103 is connected in parallel with the relay switch and receives a power input signal. The output end of the current limiting module 103 is connected to the power conversion module 105;

[0079] The relay control module 102 receives a first control signal CTL-RELAY;

[0080] When the motor control circuit is powered on and started, the power input signal outputs a DC bus voltage Vin through the current limiting module 111, and the DC bus voltage Vin charges the energy storage module 104. After the energy storage module 104 reaches the threshold, the control module 108 outputs a first control signal CTL-RELAY, and the first control signal CTL-RELAY controls the switch in the relay control module 102 to turn on, so as to turn on the current path between the relay coil and the ground terminal. The relay switch is turned on, and the DC bus voltage Vin is output through the relay switch, and the DC bus voltage Vin increases.

[0081] Since the DC bus voltage is output via the relay switch, it is no longer limited by the current limiting module 103, so the driving capability of the motor control circuit is enhanced.

[0082] like Figure 3 As shown, it is a circuit diagram of a relay control module provided by an embodiment of the utility model, from Figure 3It can be seen that the relay control module 102 includes: a third diode D3, a seventh resistor R7, an eighth resistor R8, a third capacitor C3, and a first transistor Q1;

[0083] The cathode of the third diode D3 is electrically connected to one end of the relay coil, and the anode of the third diode D3 is electrically connected to the other end of the relay coil and the collector of the first transistor Q1;

[0084] The base of the first transistor Q1 is electrically connected to the first end of the seventh resistor R7, the first end of the eighth resistor R8 and the first end of the third capacitor C3, and the emitter of the first transistor Q1 is connected to the second end of the seventh resistor R7, the second end of the third capacitor C3 and the ground end;

[0085] A second end of the eighth resistor R8 is electrically connected to the control module 108 and receives the first control signal CTL-RELAY.

[0086] The third diode D3 is used to discharge the relay coil.

[0087] In a specific embodiment, when the motor control circuit is powered on and started, the first control signal CTL-RELAY output by the control module 108 is at a low level, and the first control signal CTL-RELAY is input to the base of the first transistor Q1 through the eighth resistor R8, and the first transistor Q1 is turned off, the path between the relay coil and the ground terminal of the relay control module 102 is turned off, and the relay switch is turned off; after the energy storage module 104 is fully charged, the first control signal CTL-RELAY output by the control module 108 is at a high level, and the first control signal CTL-RELAY is input to the base of the first transistor Q1 through the eighth resistor R8, and the first transistor Q1 is turned on, the path between the relay coil and the ground terminal of the relay control module 102 is turned on, and the relay switch is turned on.

[0088] Specifically, the relay control module 102 turns on or off the path between the relay coil and the ground terminal of the relay control module 102 according to the received first control signal CTL-RELAY; if the first control signal CTL-RELAY input by the control module 108 to the relay control module 102 is low level, the relay switch is in an open state, and the DC bus voltage passes through the current limiting module 103 to charge the energy storage module 104; if the first control signal CTL-RELAY input by the control module 108 to the relay control module 102 is high level, the relay switch is in a closed state, the DC bus voltage passes through the relay switch of the relay K1, and the current is no longer limited by the current limiting module 103.

[0089] It should be noted that, in the initial state of power-on, the temperature of the stator coil of the motor is lower than the preset temperature, and the thermistor temperature switch 109 is in a closed state.

[0090] When the energy storage module 104 is fully charged, the first control signal CTL-RELAY output by the control module 108 is at a high level, the relay switch is turned on, the path resistance of the relay K1 is close to 0, the power input signal passes through the relay switch, and the current is no longer limited by the current limiting module 103. The control module 108 outputs the second control signal Vctrl to the motor drive module 106. The motor drive module 106 receives the second control signal Vctrl to enable the motor to obtain driving capability.

[0091] When the thermistor temperature switch 109 detects abnormal motor temperature, the thermistor temperature switch 109 is turned off, disconnecting the power supply path provided by the first power supply voltage VDD1 to the switching module 111, and the current path between the relay coil and the ground terminal is cut off. The relay switch is turned off, and the DC bus voltage Vin enters the current limiting module 103 output, and the DC bus voltage Vin is reduced, thereby performing motor overheat protection.

[0092] Specifically, the first voltage sampling module 107 samples the DC bus voltage Vin. If the DC bus voltage Vin is output by the current limiting module 103, the first voltage sampling module 107 outputs the first sampling voltage V1. The control module 108 receives the first sampling voltage V1 and outputs the second control signal Vctrl to the motor driving module 106, which can make the motor driving module 106 control the motor to stop and realize the motor overheat protection. If the DC bus voltage Vin is output by the relay switch, the motor driving module 106 will not control the motor to stop.

[0093] The DC bus voltage Vin output by the current limiting module 103 decreases, that is, the DC bus voltage Vin drops. When the DC bus voltage Vin drops below the working voltage of the power conversion module 105, the power conversion module 105 stops voltage conversion, the control module 108 resets, and the motor stops, thereby realizing motor overheat protection;

[0094] In one embodiment, if Figure 4 As shown, the first voltage sampling module 107 includes a first resistor R1, a second resistor R2, a third resistor R3 and a first capacitor C1;

[0095] A first end of the first resistor R1 is electrically connected to the positive electrode of the energy storage module 104, and a second end of the first resistor R1 is electrically connected to a first end of the second resistor R2 and a first end of the third resistor R3;

[0096] The second end of the second resistor R2 is electrically connected to the first end of the first capacitor C1 and the ground end;

[0097] The second end of the third resistor R3 is electrically connected to the second end of the first capacitor C1 and the control module 108 .

[0098] In a specific embodiment, the control module 108 samples the voltage of the positive electrode of the energy storage module 104, that is, the DC bus voltage Vin, through the first voltage sampling module 107. The first resistor R1 and the second resistor R2 divide the sampled voltage, and then filter the divided voltage through the third resistor R3 and the first capacitor C1 to obtain the first sampled voltage V1.

[0099] like Figure 4 As shown, the first voltage sampling module 107 may further include a first diode DS1;

[0100] An anode of the first diode DS1 is electrically connected to the second end of the third resistor R3 , and a cathode of the first diode DS1 is electrically connected to a power supply end of the control module 108 .

[0101] In a specific embodiment, the first diode DS1 may be a voltage clamping diode, which is used to limit the first sampling voltage V1 to be less than the voltage of the power supply terminal of the control module 108, so as to prevent the first sampling voltage V1 from damaging the control module 108 due to excessive voltage, and the first diode DS1 plays the role of voltage clamping. The maximum clamping voltage is the sum of the power supply voltage of the control module 108 and the conduction voltage drop of the first diode DS1.

[0102] For example, the temperature of the stator coil of the motor rises. When the thermistor temperature switch 109 senses that the temperature of the stator coil of the motor reaches a preset temperature, the thermistor temperature switch 109 is disconnected, and the path between the relay power supply end and the power supply end of the relay K1 is disconnected, causing the relay K1 to lose the voltage at the power supply end. The switch of the relay K1 is in the disconnected state, and the current passes through the current limiting module 103, causing the current limiting module 103 to heat up rapidly, and causing the voltage drop of the current limiting module 103 to rise rapidly, and the DC bus voltage Vin is reduced, thereby performing motor overheat protection, and the voltage difference between the two ends of the current limiting module 103 becomes larger, causing the voltage of the positive electrode of the energy storage module 104 to drop rapidly. Since the first voltage sampling module 107 samples the DC bus voltage output by the switching module 111 and outputs the first sampling voltage V1, the control module 108 determines that the first sampling voltage V1 is less than the first preset voltage based on the first sampling voltage V1 obtained by sampling, and outputs the second control signal Vctrl to the motor driving module 106, and the motor driving module 106 controls the motor to stop.

[0103] In one embodiment, if Figure 5 As shown, the motor control circuit provided by the embodiment of the utility model further includes: a second voltage sampling module 301, and the second voltage sampling module 301 is connected between the thermistor temperature switch 109 and the control module 108;

[0104] The second voltage sampling module 301 samples the protection signal and outputs a second sampling voltage V2 to the control module 108;

[0105] When the thermistor temperature switch 109 detects that the motor temperature is abnormal, the control module 108 receives the second sample voltage V2 and outputs a second control signal Vctrl to control the motor to stop.

[0106] When the stator coil temperature of the motor is greater than or equal to the preset temperature, the thermistor temperature switch 109 detects that the motor temperature is abnormal, the thermistor temperature switch 109 is turned off, disconnecting the power supply path provided by the first power supply voltage VDD1 to the switching module 111, and the second voltage sampling module 301 samples the protection signal and outputs the second sampling voltage V2. After receiving the second sampling voltage V2, the control module 108 outputs the second control signal Vctrl to the motor drive module 106, and the motor drive module 106 controls the motor to stop, thereby realizing motor overheat protection.

[0107] In a specific embodiment, Figure 6 As shown, the second voltage sampling module 301 includes a fourth resistor R4, a fifth resistor R5, a sixth resistor R6 and a second capacitor C2;

[0108] A first end of the fourth resistor R4 is electrically connected to the thermistor temperature switch 109, and a second end of the fourth resistor R4 is electrically connected to a first end of the fifth resistor R5 and a first end of the sixth resistor R6;

[0109] The second end of the fifth resistor R5 is connected to the first end of the second capacitor C2 and the ground end;

[0110] The second end of the sixth resistor R6 is electrically connected to the second end of the second capacitor C2 and the control module 108 to output the second sampling voltage V2.

[0111] In the embodiment of the utility model, the second voltage sampling module 301 samples the protection signal output by the thermistor temperature switch 109, and the fourth resistor R4 and the fifth resistor R5 divide the sampled voltage, and then filter the divided voltage through the sixth resistor R6 and the second capacitor C2 to obtain the second sampled voltage V2. When the thermistor temperature switch 109 is turned off, the second sampled voltage V2 sampled by the second voltage sampling module 301 indicates that the motor is overheated. After receiving the second sampled voltage V2 indicating that the motor is overheated, the control module 108 outputs the second control signal Vctrl to the motor drive module 106, and the motor drive module 106 controls the motor to stop.

[0112] In one embodiment, if Figure 6 As shown, the second voltage sampling module 301 may further include a second diode DS2;

[0113] An anode of the second diode DS2 is electrically connected to the second end of the sixth resistor R6 , and a cathode of the second diode DS2 is electrically connected to the power supply end of the control module 108 .

[0114] Specifically, the second diode DS2 may be a voltage clamping diode, and the second diode DS2 is used to limit the second sampling voltage V2 to be less than the voltage at the power supply end of the control module 108, so as to prevent the second sampling voltage V2 from damaging the control module 108 due to excessive voltage, and the second diode DS2 plays the role of voltage clamping. The maximum clamping voltage is the sum of the power supply voltage of the control module 108 and the conduction voltage drop of the second diode DS2.

[0115] For example, the temperature of the stator coil of the motor rises. When the thermistor temperature switch 109 senses that the temperature of the stator coil of the motor reaches a preset temperature, the thermistor temperature switch 109 is turned off, and the second voltage sampling module 301 samples the protection signal output by the thermistor temperature switch 109 and outputs a second sampling voltage V2. The control module 108 receives the second sampling voltage V2 and determines whether the second sampling voltage V2 is less than the second preset voltage. If the second sampling voltage V2 is less than the second preset voltage, the motor over-temperature protection mechanism is started, that is, the control module 108 outputs the second control signal Vctrl to the motor drive module 106, and the motor drive module 106 controls the motor to stop.

[0116] In a specific implementation, if the second voltage sampling module 301 is abnormal, that is, when the temperature of the stator coil of the motor is greater than or equal to the preset temperature, the control module 108 cannot receive the second sampling voltage V2 indicating that the motor is overheated. At this time, since the thermistor temperature switch 109 senses the temperature of the stator coil of the motor, when the temperature of the stator coil of the motor is greater than or equal to the preset temperature, the thermistor temperature switch 109 detects that the motor temperature is abnormal, the thermistor temperature switch 109 is turned off, the power supply path of the first power supply voltage VDD1 is turned off, the switch of the relay K1 is in an off state, and the DC bus voltage Vin is output through the current limiting module 103. The current passes through the current limiting module 103, causing the current limiting module 103 to heat up rapidly and the voltage drop of the current limiting module 103 to rise rapidly, resulting in the output current rapidly decreasing, the voltage across the current limiting module 103 increasing, and the voltage of the positive electrode of the energy storage module 104 rapidly decreasing, that is, the DC bus voltage Vin is reduced. Since the first voltage sampling module 107 collects the DC bus voltage Vin output by the switching module 111, when the DC bus voltage Vin drops, the first voltage sampling module 107 outputs the first sampling voltage V1 indicating motor overheating, and the control module 108 determines that the first sampling voltage V1 is less than the first preset voltage based on the received first sampling voltage V1 indicating motor overheating, and starts the motor overtemperature protection mechanism, that is, the control module 108 outputs the second control signal Vctrl to the motor driving module 106, and the motor driving module 106 controls the motor to stop.

[0117] In implementation, if both the first voltage sampling module 107 and the second voltage sampling module 301 are abnormal, that is, when the temperature of the stator coil of the motor is greater than or equal to the preset temperature, the first voltage sampling module 107 cannot output the first sampling voltage V1 representing motor overheating, and the second voltage sampling module 301 cannot output the second sampling voltage V2 representing motor overheating. Therefore, the control module 108 cannot output the second control signal Vctrl according to the first sampling voltage V1 representing motor overheating, nor can it output the second control signal Vctrl according to the second sampling voltage V2 representing motor overheating. At this time, due to the rapid drop in the DC bus voltage Vin, when the DC bus voltage Vin is lower than the operating voltage of the power conversion module 105, the power conversion module 105 stops voltage conversion and cannot provide power to the control module 108. The control module 108 is reset, and the motor drive is turned off to achieve over-temperature protection of the motor.

[0118] Reference Figure 1 to Figure 5 , the control module 108 is connected to the power conversion module 105;

[0119] The power conversion module 105 converts the DC bus voltage Vin into a first power supply voltage VDD1 and a second power supply voltage VDD2, wherein the first power supply voltage VDD1 supplies power to the relay K1 and the relay control module 102 via the thermistor temperature switch 109, and the second power supply voltage VDD2 supplies power to the control module 108. When the second power supply voltage VDD2 output by the power conversion module 105 is less than the power supply voltage of the control module 108, the control module 108 is reset and restarted to stop the motor from working, thereby realizing overheat protection of the motor.

[0120] In the embodiment of the present application, the power conversion module 105 provides the control module 108 with a second power supply voltage VDD2. When the motor is in an abnormal state, and when the circuits of the first voltage sampling module 107 and the second voltage sampling module 301 are abnormal, the control module 108 does not receive the first sampling voltage V1 indicating motor overheating and the second sampling voltage V2 indicating motor overheating, and does not output the second control signal Vctrl to control the motor drive to shut down, because the thermistor temperature switch 109 senses that the stator coil temperature of the motor is greater than or equal to the preset temperature, the thermistor temperature switch 109 is disconnected, the power supply path of the first power supply voltage VDD1 is cut off, the coil of the relay K1 loses power, the switch of the relay K1 is in an open state, and the current passes through the current limiting module 103. Under the current limiting effect of the current limiting module 103, the driving ability of the motor gradually decreases until the DC bus voltage output by the switching module 111 drops to a value lower than the working voltage of the power conversion module 105. When the power conversion module cannot supply power to the control module 108, the control module 108 is reset and restarted to stop the motor from working, thereby protecting the motor.

[0121] The control module 108 resets and restarts the control module 108 based on the voltage output by the power conversion module 105 being less than the power supply voltage of the control module 108, which can reduce the time that the current limiting module 103 is subjected to large current, reduce the heating time of the current limiting module 103, and increase the service life of the current limiting module 103.

[0122] It should be noted that, in the embodiment of the present invention, the control module 108 starts the motor over-temperature protection mechanism, that is, the control module 108 controls the motor drive unit 106 to control the motor to stop working.

[0123] In a specific implementation, the power input signal is an AC power input signal or a DC power input signal. If the power input signal is a DC power input signal, the DC power output by the DC power input signal is the DC bus voltage. If the power input signal is an AC power input signal, a rectifier module is required to convert the AC power input signal into a DC signal, and the DC signal converted by the rectifier module is the DC bus voltage.

[0124] In a specific implementation, the rectifier module may be a rectifier bridge.

[0125] When the power input signal is an AC power input signal, the rectifier module can be Figure 1 , Figure 2 and Figure 5 The connection shown in FIG. 1 is that the rectifier module is directly connected to the AC input terminal; the rectifier module can also be Figure 7 The connection shown in the figure, that is, the first input end of the rectifier module is connected to the AC power supply through the current limiting module 103, the second input end of the rectifier module is directly connected to the AC power supply, the first output end of the rectifier module is connected to the power conversion module 105, and the second output end of the rectifier module is connected to the ground end.

[0126] The specific structures of the power conversion module 105, the control module 108, the motor drive module 106 and the motor in the embodiment of the utility model can all refer to the specific structures provided in the relevant technology, and will not be repeated here.

[0127] like Figure 8 As shown, the motor control circuit provided by the embodiment of the utility model may further include a ninth resistor R9, and the first supply voltage VDD1 passes through the ninth resistor R9 and the thermistor temperature switch to provide power to the relay and the relay control module.

[0128] The ninth resistor R9 is used for current limiting, which can limit the current of the relay and protect the power supply.

[0129] The motor control circuit provided by the embodiment of the utility model, in the initial state of power-on, the temperature of the stator coil of the motor is less than the preset temperature, the thermistor temperature switch 109 is in a closed state, the first control signal CTL-RELAY output by the control module 108 is at a low level, and after the relay control module 103 receives the low-level first control signal CTL-RELAY, the path between the relay coil and the ground terminal of the relay control module 103 is disconnected, the switch of the relay K1 is in an open state, and the DC bus voltage passes through the current limiting module 103 to charge the energy storage module 104;

[0130] When the energy storage module 104 is fully charged, the first control signal CTL-RELAY output by the control module 108 is at a high level. After the control relay control module 103 receives the high-level first control signal CTL-RELAY, the path between the relay coil and the ground terminal of the relay control module 103 is turned on, the relay coil is energized, the switch of the relay K1 is in a closed state, and the DC bus voltage is output through the relay coil to supply power to the power conversion module 105 and the motor drive module 106. The power conversion module 105 provides the converted second power supply voltage VDD2 to the control module 108. After receiving the second power supply voltage VDD2, the control module 108 sends a drive signal to the motor drive module 106, and the motor drive module 106 controls the motor to run;

[0131] After the motor control circuit is powered on, the first voltage sampling module 107 samples the DC bus voltage output by the switching module 111 to obtain a first sampled voltage V1; the second voltage sampling module 301 samples the protection signal to obtain a second sampled voltage V2;

[0132] During the operation of the motor, if the motor is in an abnormal state due to overheating, the thermistor temperature switch 109 senses that the temperature of the stator coil of the motor is greater than or equal to the preset temperature, and the thermistor temperature switch 109 is turned off, disconnecting the power supply path provided by the first power supply voltage VDD1 to the switching module 111, and the current path between the relay coil and the ground terminal is cut off. The DC bus voltage is output through the current limiting module 111, and the DC bus voltage is reduced, thereby performing motor overheat protection. Motor overheat protection can specifically include the following methods:

[0133] The second voltage sampling module 301 samples the protection signal output by the thermistor temperature switch 109. When the thermistor temperature switch 109 is turned off, the second sampling voltage V2 output by the second voltage sampling module 301 is less than the second preset voltage. When the control module 108 determines that the second sampling voltage V2 is less than the second preset voltage, the second control signal Vctrl is output. After receiving the second control signal Vctrl, the motor driving module 106 controls the motor to stop, so as to realize the overheat protection of the motor.

[0134] The first voltage sampling module 107 samples the DC bus voltage Vin output by the switching module 111. When the thermistor temperature switch 109 is turned off, the DC bus voltage Vin output by the switching module 111 decreases. During the decrease of the DC bus voltage Vin, the first voltage sampling module 107 outputs a first sampling voltage V1 according to the sampled DC bus voltage Vin. At this time, the first sampling voltage V1 is less than the first preset voltage. When the control module 108 determines that the first sampling voltage V1 is less than the first preset voltage, the second control signal Vctrl is output. After receiving the second control signal Vctrl, the motor driving module 106 controls the motor to stop, so as to realize the overheat protection of the motor.

[0135] When the thermistor temperature switch 109 is turned off, the DC bus voltage Vin output by the switching module 111 decreases. When the DC bus voltage Vin drops below the operating voltage of the power conversion module 105, the power conversion module stops voltage conversion, the control module is reset, and the motor stops to achieve overheat protection of the motor.

[0136] The embodiment of the utility model can achieve multi-level protection against motor overheating through the above-mentioned method of controlling the motor to stop. When the detection circuit is disconnected or the detection fails, the motor overheating protection can also be achieved, thereby improving the reliability of the motor control circuit.

[0137] Based on the same disclosed concept, the motor control circuit described above in the embodiment of the utility model can also be implemented by a motor control system. The effect of the motor control system is similar to the above effect, which will not be described in detail here.

[0138] like Fig. 9 FIG. 1 is a schematic diagram of a motor control system provided by an embodiment of the utility model, and the motor control system includes:

[0139] An AC power supply 901, providing AC power;

[0140] A rectifier module 902, wherein the input end of the rectifier module is connected to the AC power supply, and the output end of the rectifier module is connected to the current limiting module, or the input end of the rectifier module is connected to the current limiting module, and the output end of the rectifier module is connected to the power conversion module;

[0141] A motor, and a motor control circuit 903 as described in any one of the above embodiments.

[0142] like Figure 1 , Figure 2 and Figure 5 As shown, the input end of the rectifier module is connected to the AC power supply, and the output end of the rectifier module is connected to the current limiting module, that is, the rectifier module is directly connected to the AC power supply;

[0143] like Figure 7As shown, the input end of the rectifier module is connected to the current limiting module 103, and the output end of the rectifier module is connected to the power conversion module 105, that is, the first input end of the rectifier module is connected to the AC power supply through the current limiting module 103, the second input end of the rectifier module is directly connected to the AC power supply, the first output end of the rectifier module is connected to the power conversion module 105, and the second output end of the rectifier module is connected to the ground end.

[0144] It should be noted that if the above-mentioned rectifier module is replaced with a three-phase rectifier module, the above-mentioned motor control system can also be applied to a three-phase power supply circuit.

[0145] In another embodiment, if Fig.10 As shown, the motor control system includes:

[0146] A DC power supply 1001 provides DC power, and an output end of the DC power supply is connected to a current limiting module;

[0147] A motor, and a motor control circuit 903 as described above.

[0148] The motor control circuit and system provided by the embodiment of the utility model, when the stator coil temperature of the motor is greater than or equal to the preset temperature, the thermistor temperature switch detects that the motor temperature is abnormal, the thermistor temperature switch is turned off, the power supply path of the first power supply voltage is turned off, the relay switch is turned off, the DC bus voltage is output via the current limiting module, the terminal voltage of the current limiting module increases, the DC bus voltage decreases, the first voltage sampling module samples the DC bus voltage output by the switching module, and outputs the first sampling voltage indicating motor overheating, the control module outputs the second control signal to the motor drive module according to the first sampling voltage indicating motor overheating output by the first voltage sampling module, and the motor drive module controls the motor to stop; when the DC bus voltage drops to a level lower than the working voltage of the power conversion module, the power conversion module stops voltage conversion, the control module is reset, and the motor is stopped; when the power supply path of the first power supply voltage is turned off, the second voltage sampling module outputs the second sampling voltage indicating motor overheating, the control module outputs the second control signal according to the second sampling voltage, and the motor drive module controls the motor to stop. By controlling the motor shutdown as described above, multi-level protection against motor overheating can be achieved. When the detection circuit is disconnected or the detection fails, for example, the first voltage sampling module and / or the second voltage sampling module is abnormal, the motor overheating protection can also be achieved, thereby improving the reliability of the motor control circuit and system. In addition, compared to the thermocouple used to control the motor drive shutdown, the thermistor temperature switch has low cost and small size, which increases the space inside the motor.

[0149] Those skilled in the art may make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include these modifications and variations.

Claims

1. A motor control circuit, characterized in that: include: Thermistor temperature switch, switching module, power conversion module, motor drive module, first voltage sampling module and control module; The thermistor temperature switch receives a first supply voltage and outputs a protection signal according to the detected motor temperature; The switching module receives the protection signal, the first control signal and the power input signal, and outputs a DC bus voltage; The power conversion module converts the received DC bus voltage into a first power supply voltage and a second power supply voltage, wherein the first power supply voltage is provided to the switching module for power supply, and the second power supply voltage is provided to the control module for power supply; The first voltage sampling module samples the DC bus voltage and outputs a first sampled voltage; The control module outputs the first control signal and the second control signal according to the first sampled voltage; The motor driving module receives the DC bus voltage and the second control signal to control the motor; The thermistor temperature switch is turned on when it is detected that the temperature of the motor is normal, and outputs a protection signal for providing the first power supply voltage. The switching module receives the first power supply voltage, and the motor works normally. The thermistor temperature switch is turned off when abnormal motor temperature is detected, disconnecting the power supply path provided by the first power supply voltage to the switching module, outputting a protection signal for disconnecting the power supply, and performing motor overheat protection.

2. The motor control circuit according to claim 1, characterized in that: The motor control circuit further includes an energy storage module connected between the DC bus voltage and the ground terminal; the switching module includes: Relay, including a relay coil and a relay switch; A current limiting module is connected in parallel with the relay switch and receives the power input signal, and an output end of the current limiting module is connected to the power conversion module; A relay control module receives the first control signal; When the motor control circuit is powered on and started, the power input signal outputs the DC bus voltage through the current limiting module, and the DC bus voltage charges the energy storage module. After the energy storage module reaches a threshold, the control module outputs the first control signal, and the first control signal controls the switch in the relay control module to turn on, so as to turn on the current path between the relay coil and the ground terminal. The relay switch is turned on, the DC bus voltage is output via the relay switch, and the DC bus voltage increases.

3. The motor control circuit according to claim 2, characterized in that: When the thermistor temperature switch detects abnormal motor temperature, the thermistor temperature switch is turned off, disconnecting the power supply path provided by the first power supply voltage to the switching module, and the current path between the relay coil and the ground terminal is turned off. The DC bus voltage is output via the current limiting module, and the DC bus voltage is reduced, thereby performing overheat protection for the motor.

4. The motor control circuit according to claim 3, characterized in that: When the thermistor temperature switch detects abnormal motor temperature, the first voltage sampling module samples the DC bus voltage output by the switching module and outputs the first sampled voltage. The control module receives the first sampled voltage and outputs the second control signal to the motor drive module, and the motor drive module controls the motor to stop.

5. The motor control circuit according to claim 3, characterized in that: When the thermistor temperature switch detects abnormal motor temperature, the DC bus voltage output by the switching module drops to a level lower than the operating voltage of the power conversion module, the power conversion module stops voltage conversion, the control module is reset, and the motor stops.

6. The motor control circuit according to claim 3, characterized in that: The motor control circuit also includes a second voltage sampling module, which is connected between the thermistor temperature switch and the control module, samples the protection signal, and outputs a second sampling voltage; when the thermistor temperature switch detects abnormal motor temperature, the control module receives the second sampling voltage and outputs the second control signal to control the motor to stop.

7. The motor control circuit according to claim 1, characterized in that: The thermistor temperature switch senses the temperature of the stator coil of the motor. When the temperature of the stator coil of the motor is greater than or equal to a preset temperature, the thermistor temperature switch detects that the temperature of the motor is abnormal.

8. The motor control circuit according to claim 1, characterized in that: The power input signal is an AC power input signal or a DC power input signal.

9. The motor control circuit according to claim 2, characterized in that: The first voltage sampling module includes a first resistor, a second resistor, a third resistor and a first capacitor; The first end of the first resistor is electrically connected to the positive electrode of the energy storage module and inputs the DC bus voltage, and the second end of the first resistor is electrically connected to the first end of the second resistor and the first end of the third resistor; The second end of the second resistor is electrically connected to the first end of the first capacitor and the ground end; The second end of the third resistor is electrically connected to the second end of the first capacitor and the control module to output the first sampling voltage.

10. The motor control circuit according to claim 9, characterized in that: The first voltage sampling module also includes a first diode; An anode of the first diode is electrically connected to the second end of the third resistor, and a cathode of the first diode is electrically connected to a power supply end of the control module.

11. The motor control circuit according to claim 2, characterized in that: The relay control module includes: a third diode, a seventh resistor, an eighth resistor, a third capacitor and a first triode; The cathode of the third diode is electrically connected to one end of the relay coil, and the anode of the third diode is electrically connected to the other end of the relay coil and the collector of the first transistor; The base of the first transistor is electrically connected to the first end of the seventh resistor, the first end of the eighth resistor and the first end of the third capacitor, and the emitter of the first transistor is electrically connected to the second end of the seventh resistor, the second end of the third capacitor and the ground end; The second end of the eighth resistor is electrically connected to the control module to receive the first control signal.

12. The motor control circuit according to claim 6, characterized in that: The second voltage sampling module includes a fourth resistor, a fifth resistor, a sixth resistor and a second capacitor; The first end of the fourth resistor is electrically connected to the power supply end of the relay control module, and the second end of the fourth resistor is electrically connected to the first end of the fifth resistor and the first end of the sixth resistor; The second end of the fifth resistor is electrically connected to the first end of the second capacitor and the ground end; The second end of the sixth resistor is electrically connected to the second end of the second capacitor and the control module.

13. The motor control circuit according to claim 12, characterized in that: The second voltage sampling module also includes a second diode; An anode of the second diode is electrically connected to the second end of the sixth resistor, and a cathode of the second diode is electrically connected to a power supply end of the control module.

14. A motor control system, characterized in that: include: AC power supply, providing AC power; A rectifier module, wherein the input end of the rectifier module is connected to the AC power supply, and the output end of the rectifier module is connected to the current limiting module, or the input end of the rectifier module is connected to the current limiting module, and the output end of the rectifier module is connected to the power conversion module; A motor, and a motor control circuit according to any one of claims 1 to 13.

15. A motor control system, characterized in that: include: A DC power supply, providing DC power, wherein an output end of the DC power supply is connected to a current limiting module; A motor, and a motor control circuit according to any one of claims 1 to 13.

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