Circuit for diagnosing fault of three-phase coil of brushless motor

Abstract

The utility model discloses a circuit for diagnosing faults of a three-phase coil of a brushless motor. The three coil connection modules are connected to a three-phase coil of the brushless motor, the MCU is connected with the three coil connection modules and the composite triode U5, and the composite triode U5 is connected to one coil connection module; in the coil connection module, a resistor and a capacitor are connected in parallel and then are connected in series with another resistor between the coils of the brushless motor and the ground, and the three-phase coils are connected together; and the resistors are led out and connected to a micro control unit (MCU). According to the utility model, various faults of the three-phase coil of the brushless motor can be diagnosed and identified, the use safety of the brake-by-wire system is improved, and the load of the controller is forcibly turned off in an active or passive manner, so that the load is powered off and does not act, and the functional safety level is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of automobile electronic circuits, in particular to a circuit for diagnosing three-phase coil faults of brushless motors. Background Art

[0002] Brushless motors have the advantages of simple control, suitable for high-frequency PWM control, fast response speed, and precise control. Therefore, brushless motors are widely used in electronic power-assisted braking systems.

[0003] In the electronic power-assisted braking system, the controllability of the power-assisted motor is one of the most important indicators for safety. Therefore, when the system fails, if the power-assisted motor cannot be diagnosed, it will have a significant impact on driving safety. Utility Model Content

[0004] In order to solve the problems existing in the background technology, the utility model proposes a circuit for diagnosing the fault of the three-phase coil of the brushless motor, which solves the technical problem that the three-phase coil of the brushless motor cannot be diagnosed in real time.

[0005] The technical solution of the utility model is achieved in this way:

[0006] The utility model comprises a micro-control unit MCU, a composite triode U5 and three coil connection modules, the three coil connection modules are respectively connected to the three-phase coils of the brushless motor, the micro-control unit MCU is respectively connected to the three coil connection modules and the composite triode U5, and the composite triode U5 is connected to one coil connection module among the three coil connection modules.

[0007] Each coil connection module includes two resistors and a capacitor, one resistor and a capacitor are connected in parallel and then connected in series with another resistor between one end of the coil of the brushless motor and the ground, and the other ends of the three-phase coils of the brushless motor are connected together; the leads between the two resistors are connected to the microcontroller unit MCU.

[0008] The composite triode U5 is mainly composed of two triodes connected, the emitter of the first triode of the composite triode U5 is grounded, the base of the first triode is connected to the drive signal output port M_DRV_COIL of the micro-control unit MCU, the collector of the first triode is connected to the base of the second triode, the emitter of the second triode is connected to the power supply voltage, and the collector of the second triode is connected to one end of one coil of the brushless motor through a diode D3 and a resistor R19 in sequence.

[0009] The three coil connection modules are:

[0010] The first coil connection module includes a resistor R17, a resistor R18 and a capacitor C6. The resistor R17 and the capacitor C6 are connected in parallel and then connected in series with the resistor R18 between one end of the coil L1 of the brushless motor and the ground. An analog-to-digital conversion port M_AD_SH1 connected to the microcontroller unit MCU is led out between the resistor R17 and the resistor R18.

[0011] The second coil connection module includes a resistor R20, a resistor R21 and a capacitor C7. The resistor R20 and the capacitor C7 are connected in parallel and then connected in series with the resistor R21 between one end of the coil L1 of the brushless motor and the ground. An analog-to-digital conversion port M_AD_SH2 connected to the microcontroller MCU is connected between the resistor R20 and the resistor R21.

[0012] The third coil connection module includes a resistor R30, a resistor R31 and a capacitor C9. The resistor R30 and the capacitor C9 are connected in parallel and then connected in series with the resistor R31 between one end of the coil L2 of the brushless motor and the ground. A lead is connected between the resistor R30 and the resistor R31 to the analog-to-digital conversion port M_AD_SH3 of the micro-control unit MCU.

[0013] Beneficial effects of the utility model:

[0014] The utility model circuit can diagnose and identify the faults such as open circuit of nodes, short circuit to power supply, short circuit to ground and the like of the three-phase coil of the brushless motor, thereby improving the use safety of the wire control brake system.

[0015] Moreover, the utility model can forcibly shut down the load of the controller in an active or passive manner, so that the load is powered off and does not operate. This circuit design improves the functional safety level of vehicle use. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The schematic diagram of a circuit for diagnosing three-phase coil faults of a brushless motor is shown in FIG. DETAILED DESCRIPTION

[0017] The utility model is further described below in conjunction with the accompanying drawings and embodiments.

[0018] like Figure 1 As shown, the specifically implemented circuit includes a micro-control unit MCU, a composite transistor U5 and three coil connection modules. The three coil connection modules are respectively connected to the three-phase coils of the brushless motor. The micro-control unit MCU is respectively connected to the three coil connection modules and the composite transistor U5. The composite transistor U5 is connected to one of the three coil connection modules.

[0019] Each coil connection module includes two resistors and a capacitor, one resistor and a capacitor are connected in parallel and then connected in series with another resistor between one end of a coil of the brushless motor and the ground, and the other ends of the three-phase coils of the brushless motor are connected together; the leads between the two resistors are connected to the microcontroller unit MCU.

[0020] The composite transistor U5 is mainly composed of two transistors connected together. The emitter of the first transistor of the composite transistor U5 is grounded, the base of the first transistor is connected to the drive signal output port M_DRV_COIL of the micro-control unit MCU, the collector of the first transistor is connected to the base of the second transistor, the emitter of the second transistor is connected to the power supply voltage 5V, and the collector of the second transistor is connected to one end of one coil of the brushless motor through a diode D3 and a resistor R19 in sequence.

[0021] Moreover, the anode of the diode is connected to the collector of the second transistor, and the cathode is connected to the coil of the brushless motor.

[0022] The other ends of the coils L1 , L2 , and L3 of the brushless motor are connected together.

[0023] like Figure 1 As shown, in a specific implementation, the three coil connection modules are:

[0024] The first coil connection module includes a resistor R17, a resistor R18 and a capacitor C6. The resistor R17 and the capacitor C6 are connected in parallel and then connected in series with the resistor R18 between one end of the coil L1 of the brushless motor and the ground. An analog-to-digital conversion port M_AD_SH1 connected to the microcontroller unit MCU is led out between the resistor R17 and the resistor R18.

[0025] The second coil connection module includes a resistor R20, a resistor R21 and a capacitor C7. The resistor R20 and the capacitor C7 are connected in parallel and then connected in series with the resistor R21 between one end of the coil L1 of the brushless motor and the ground. An analog-to-digital conversion port M_AD_SH2 connected to the microcontroller MCU is connected between the resistor R20 and the resistor R21.

[0026] The third coil connection module includes a resistor R30, a resistor R31 and a capacitor C9. The resistor R30 and the capacitor C9 are connected in parallel and then connected in series with the resistor R31 between one end of the coil L2 of the brushless motor and the ground. A lead is connected between the resistor R30 and the resistor R31 to the analog-to-digital conversion port M_AD_SH3 of the micro-control unit MCU.

[0027] In the specific implementation, the resistance value of resistors R30, R17, and R20 is 30K, the resistance value of resistors R21, R18, and R31 is 10K, the capacitance value of capacitors C9, C6, and C7 is 100nF, the resistance value of resistor R19 is 1K, the model of diode D3 is S-LBAS21HT1G, and the model of composite transistor U5 is: PUMD16-Q.

[0028] When the micro-control unit MCU drives the signal output port M_DRV_COIL to output a high level, real-time detection is performed through the three analog-to-digital conversion ports of the micro-control unit MCU:

[0029] A) If the voltages detected by the analog-to-digital conversion ports M_AD_SH1, M_AD_SH2, and M_AD_SH3 are not zero and are respectively the values ​​of the following formulas, then the three-phase coils are not faulty:

[0030] U SH1 =(U1-U2)*(R18 / (R18+R17))

[0031] U SH2 =(U1-U2)*(R20 / (R20+R21))

[0032] U SH3 =(U1-U2)*(R30 / (R30+R31))

[0033] Among them, U SH1 , U SH2 , U SH3 Indicates the voltage detected by the analog-to-digital conversion port M_AD_SH1, the analog-to-digital conversion port M_AD_SH2, and the analog-to-digital conversion port M_AD_SH3, U1 indicates the voltage value of the power supply voltage, and U2 indicates the voltage drop of the diode D3;

[0034] B) If the voltages detected by the analog-to-digital conversion ports M_AD_SH1, M_AD_SH2, and M_AD_SH3 are all zero, the three-phase coils are short-circuited to the ground;

[0035] C) If the voltages detected by the analog-to-digital conversion ports M_AD_SH1, M_AD_SH2, and M_AD_SH3 are all the values ​​of the following formulas at the same time, the three-phase coil is short-circuited to the power supply:

[0036] U SH1 =U3*R18 / (R18+R17)

[0037] U SH2 =U3*R20 / (R20+R21)

[0038] U SH3=U3*R30 / (R30+R31)

[0039] Among them, U SH1 , U SH2 , U SH3 Indicates the voltage detected by the analog-to-digital conversion port M_AD_SH1, the analog-to-digital conversion port M_AD_SH2, and the analog-to-digital conversion port M_AD_SH3, and U3 indicates the voltage value of the vehicle voltage;

[0040] D) If among the voltages detected by the analog-to-digital conversion ports M_AD_SH1, M_AD_SH2, and M_AD_SH3, only the voltage detected by the analog-to-digital conversion port M_AD_SH1 corresponding to the coil connection module directly connected to the micro-control unit MCU is the value of the following formula, and the voltages detected by the other two analog-to-digital conversion ports M_AD_SH2 and M_AD_SH3 are both zero, then the node SH1 of the coil of the phase where the coil connection module directly connected to the micro-control unit MCU is located is open:

[0041] U SH1 =(U1-U2)*(R18 / (R18+R17))

[0042] Among them, U SH1 It represents the voltage detected by the analog-to-digital conversion port M_AD_SH1, U1 represents the voltage value of the power supply voltage, and U2 represents the voltage drop of the diode D3;

[0043] If the voltage detected by the analog-to-digital conversion port M_AD_SH1, the analog-to-digital conversion port M_AD_SH2, and the analog-to-digital conversion port M_AD_SH3 is the value of the following formula, and one of the voltages detected by the other two analog-to-digital conversion ports M_AD_SH2 and the analog-to-digital conversion port M_AD_SH3 is zero, then the node of the coil of the phase corresponding to the coil connection module of the analog-to-digital conversion port M_AD_SH3 where the voltage is zero is open:

[0044] U SH1 =(U1-U2)*(R18 / (R18+R17))

[0045] Among them, U SH1 It represents the voltage detected by the analog-to-digital conversion port M_AD_SH1, U1 represents the voltage value of the power supply voltage, and U2 represents the voltage drop of the diode D3.

[0046] In specific implementation, the circuit diagnosis is performed under the premise that the three-phase coil is not energized: the specific diagnostic modes are divided into the following types: no-fault mode, the three-phase coil is short-circuited to the ground, the three-phase coil is short-circuited to the power supply, the node SH1 of coil L3 is open, the node SH2 of coil L1 is open, and the node SH3 of coil L2 is open.

[0047] Three-phase coil fault-free mode: The output of the drive signal port M_DRV_COIL is high level (5V), at this time, the composite transistor U5 is turned on, and the voltage of the pin 4 of the composite transistor U5 is loaded on the pin 3. At this time, the voltage of the analog-to-digital conversion port M_AD_SH1 is equal to:

[0048] (U1-U2)*(R18 / (R18+R17))=(5V-0.7V)*10K / (10K+30K)=4.3V*0.25=1.075V

[0049] Because the three-phase coils are interconnected at one node, the wires inside are similar to a short circuit.

[0050] At this time, the voltage of the analog-to-digital conversion port M_AD_SH2 is equal to:

[0051] (U1-0.7V)*(R20 / (R20+R21))=(5V-0.7V)*10K / (10K+30K)=4.3V*0.25=1.075V At this time, the voltage of the analog-to-digital conversion port M_AD_SH3 is equal to:

[0052] (U1-0.7V)*(R30 / (R30+R31))=(5V-0.7V)*10K / (10K+30K)=4.3V*0.25=1.075V, thus, no fault detection is performed.

[0053] Fault mode 1: Three-phase coil short circuit to ground

[0054] The output of the driving signal port M_DRV_COIL is a high level (5V). Since the three-phase coils are interconnected at one node, the wires inside are similar to a short circuit.

[0055] The voltage of the analog-to-digital conversion port M_AD_SH1 is equal to: 0V

[0056] The voltage of the analog-to-digital conversion port M_AD_SH2 is equal to: 0V

[0057] The voltage of the analog-to-digital conversion port M_AD_SH3 is equal to: 0V

[0058] Based on this, it was detected that the three-phase coil was short-circuited to ground.

[0059] Fault mode 2: The three-phase coil is short-circuited to the power supply and short-circuited to the vehicle voltage

[0060] The vehicle voltage is 12V. When the power supply is short-circuited, 12V will be connected and applied to the three SH nodes in the figure, namely SH1, SH2, and SH3.

[0061] The output of the drive signal port M_DRV_COIL is high level (5V), and the voltage of the analog-to-digital conversion port M_AD_SH1 is equal to:

[0062] 12V*(R18 / (R18+R17))=12*10K / (10K+30K)=12V*0.25=3V.

[0063] Since the three-phase coils are interconnected at one node, the wires inside are similar to a short circuit.

[0064] At this time, the voltage of the analog-to-digital conversion port M_AD_SH2 is equal to:

[0065] 12V*R20 / (R20+R21)=12*10K / (10K+30K)=12V*0.25=3V

[0066] At this time, the voltage of the analog-to-digital conversion port M_AD_SH3 is equal to:

[0067] 12V*R30 / (R30+R31)=12*10K / (10K+30K)=12V*0.25=3V

[0068] Based on this, it was detected that the three-phase coil was short-circuited to the power supply.

[0069] Failure Mode 3:

[0070] If the coil L1 and its node SH1 are open, the drive signal port M_DRV_COIL outputs a high level (5V), and the M_AD_SH1 voltage is equal to:

[0071] (5V-0.7V)*(R18 / (R18+R17))=(5V-0.7V)*10K / (10K+30K)=4.3V*0.25=1.075V

[0072] Since the coil L1 and its node SH1 are open, the voltage of the analog-to-digital conversion port M_AD_SH2 is equal to 0V, and the voltage of the analog-to-digital conversion port M_AD_SH3 is also equal to 0V.

[0073] Failure Mode 4:

[0074] If the coil L2 and its node SH2 are open, the drive signal port M_DRV_COIL outputs a high level (5V), and the M_AD_SH1 voltage is equal to:

[0075] (5V-0.7V)*(10K / 10K+30K)=4.3V*0.25=1.075V

[0076] At this time, the voltage of the analog-to-digital conversion port M_AD_SH2 is equal to 0V;

[0077] The voltage of the analog-to-digital conversion port M_AD_SH3 is equal to:

[0078] (5V-0.7V)*(R30 / (R30+R31))=(5V-0.7V)*(10K / 10K+30K)=4.3V*0.25=1.075V Based on this, it is detected that the coil L2 is open.

[0079] Failure Mode 5:

[0080] If the coil L3 and its node SH3 are open, the drive signal port M_DRV_COIL outputs a high level (5V), and the M_AD_SH1 voltage is equal to:

[0081] (5V-0.7V)*(10K / 10K+30K)=4.3V*0.25=1.075V

[0082] At this time, the voltage of the analog-to-digital conversion port M_AD_SH3 is equal to 0V;

[0083] The voltage of the analog-to-digital conversion port M_AD_SH2 is equal to:

[0084] (5V-0.7V)*(R20 / (R20+R21))=(5V-0.7V)*(10K / 10K+30K)=4.3V*0.25=1.075V Based on this, it is detected that the coil L3 is open.

[0085] The specific overall diagnostic truth table is as follows:

[0086] Drive signal status (high) M_AD_SH1 M_AD_SH2 M_AD_SH3 Diagnosis M_DRV_COIL=1 1.075V 1.075V 1.075V No trouble M_DRV_COIL=1 0V 0V 0V Three-phase coil short circuit to ground M_DRV_COIL=1 3V 3V 3V Three-phase coil short circuit to power supply M_DRV_COIL=1 1.075V 0V 0V The SH1 node of the coil is open M_DRV_COIL=1 1.075V 0V 1.075V The SH2 node of the coil is open M_DRV_COIL=1 1.075V 1.075V 0V The SH3 node of the coil is open

[0087] As can be seen from the above table, the utility model can accurately, quickly and efficiently detect the three-phase coil fault of the brushless motor according to this logic.

[0088] The above specific implementation modes are used to explain the present invention rather than to limit the present invention. Any modification and change made to the present invention within the spirit of the present invention and the protection scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A circuit for diagnosing a three-phase coil fault of a brushless motor, characterized in that: It includes a micro-control unit MCU, a composite triode U5 and three coil connection modules. The three coil connection modules are respectively connected to the three-phase coils of the brushless motor. The micro-control unit MCU is respectively connected to the three coil connection modules and the composite triode U5. The composite triode U5 is connected to one of the three coil connection modules.

2. A circuit for diagnosing a three-phase coil fault of a brushless motor according to claim 1, characterized in that: Each coil connection module includes two resistors and a capacitor, one resistor and a capacitor are connected in parallel and then connected in series with another resistor between one end of the coil of the brushless motor and the ground, and the other ends of the three-phase coils of the brushless motor are connected together; the leads between the two resistors are connected to the microcontroller unit MCU.

3. A circuit for diagnosing a three-phase coil fault of a brushless motor according to claim 1, characterized in that: The composite triode U5 is mainly composed of two triodes connected, the emitter of the first triode of the composite triode U5 is grounded, the base of the first triode is connected to the drive signal output port M_DRV_COIL of the micro-control unit MCU, the collector of the first triode is connected to the base of the second triode, the emitter of the second triode is connected to the power supply voltage, and the collector of the second triode is connected to one end of one coil of the brushless motor through a diode D3 and a resistor R19 in sequence.

4. A circuit for diagnosing a three-phase coil fault of a brushless motor according to claim 1, characterized in that: The first coil connection module of the three coil connection modules includes a resistor R17, a resistor R18 and a capacitor C6. The resistor R17 and the capacitor C6 are connected in parallel and then connected in series with the resistor R18 between one end of the coil L1 of the brushless motor and the ground. An analog-to-digital conversion port M_AD_SH1 connected to the micro-control unit MCU is led out between the resistor R17 and the resistor R18.

5. A circuit for diagnosing a three-phase coil fault of a brushless motor according to claim 1, characterized in that: The second coil connection module of the three coil connection modules includes a resistor R20, a resistor R21 and a capacitor C7. The resistor R20 and the capacitor C7 are connected in parallel and then connected in series with the resistor R21 between one end of the coil L1 of the brushless motor and the ground. An analog-to-digital conversion port M_AD_SH2 connected to the micro-control unit MCU is led out between the resistor R20 and the resistor R21.

6. A circuit for diagnosing a three-phase coil fault of a brushless motor according to claim 1, characterized in that: The third coil connection module of the three coil connection modules includes a resistor R30, a resistor R31 and a capacitor C9. The resistor R30 and the capacitor C9 are connected in parallel and then connected in series with the resistor R31 between one end of the coil L2 of the brushless motor and the ground. An analog-to-digital conversion port M_AD_SH3 connected to the micro-control unit MCU is led out between the resistor R30 and the resistor R31.

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