MOTOR CONTROL DEVICE AND METHOD FOR STARTING MOTOR CONTROL DEVICE

Abstract

To provide a motor control device capable of reducing relative variations in detection accuracy when a plurality of voltages is detected, and a method for starting the same.SOLUTION: A voltage detection circuit 25 detects a battery voltage Vbat of a battery 30 and a capacitor voltage Vc of a capacitor C1. A selection circuit 26 selects the battery voltage Vbat or the capacitor voltage Vc to be input to the voltage detection circuit 25. Before a relay 17 is controlled to turn on, a controller 16 controls a charging switch PSW to turn on until the capacitor voltage Vc reaches a charging end voltage determined with the battery voltage Vbat being a reference based on detection results of the voltage detection circuit 25.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a motor controller and a start-up method for the motor controller, and in particular to technology for electric vehicles. [Background technology]

[0002] Patent Document 1 shows a regenerative charging control device for an electric vehicle that can control the regenerative voltage from the motor so that it does not become excessive even when the power is off. The device has a non-insulated DC / DC converter that is connected to the power line of the battery without a main switch, and a hardware regulator that operates with power from the non-insulated DC / DC converter and includes a voltage detection unit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-147237 A Summary of the Invention [Problem to be solved by the invention]

[0004] For example, an electric vehicle (EV) is equipped with a motor attached to the wheels and an inverter that drives the motor using a battery as a power source. Power is supplied to the inverter from the battery via a contactor, which is a type of relay. In addition, a large-capacity electrolytic capacitor or the like is usually connected to the inverter's power source for stabilization. In such a configuration, when power is applied to the inverter, an inrush current may flow from the battery to the electrolytic capacitor via the contactor. In this case, for example, deterioration of the electrolytic capacitor or welding of the contactor contacts may occur.

[0005] Therefore, for example, it is conceivable to provide a mechanism in which the voltages of the battery and electrolytic capacitor are detected by individual detection circuits, the electrolytic capacitor is gradually charged through a path different from the contactor, and then the contactor is turned on. However, if the voltages of the battery and electrolytic capacitor are detected by individual detection circuits, there is a risk that relative variations in detection accuracy will occur between the detection circuits. As a result, there is a risk that the electrolytic capacitor and the relay cannot be sufficiently protected.

[0006] The present invention has been made in consideration of the above, and one of its objects is to provide a motor control device and a start-up method for a motor control device that are capable of reducing the relative variation in detection accuracy when detecting multiple voltages. [Means for solving the problem]

[0007] The motor control device of the present invention has an inverter that supplies power to a motor, a capacitor connected to a power supply node of the inverter, a relay that connects a battery power supply node and a power supply node of the inverter when controlled on, a charging switch that forms a charging path from the battery to the capacitor when controlled on, a limiting element inserted in the charging path from the battery to the capacitor and limits a charging current, a voltage detection circuit, a selection circuit, and a controller, wherein the voltage detection circuit detects a battery voltage of the battery and a capacitor voltage of the capacitor, the selection circuit selects whether to input the battery voltage or the capacitor voltage to the voltage detection circuit, and the controller is configured to control the charging switch to be on until the capacitor voltage reaches a charging termination voltage determined based on the battery voltage based on the detection result of the voltage detection circuit before controlling the relay to be on. Effect of the Invention

[0008] According to the present invention, it is possible to reduce the relative variation in detection accuracy when detecting a plurality of voltages. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing a configuration example of main parts around a motor control device according to an embodiment of the present invention; [Diagram 2] 2 is a schematic diagram showing a configuration example of a main part of a controller appearing in FIG. 1. [Diagram 3] 3 is a flow chart showing an example of processing contents in a controller of FIG. 2. [Figure 4] FIG. 2 is a schematic diagram showing a configuration example of main parts around a motor control device serving as a comparative example of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0011] Overview of the motor control device Fig. 1 is a schematic diagram showing an example of the configuration of the main parts around a motor control device according to an embodiment of the present invention. Fig. 2 is a schematic diagram showing an example of the configuration of the main parts of the controller in Fig. 1. Fig. 1 shows a motor control device 10, a main switch MSW, a battery 30, and a motor 40. This configuration is mounted on an electric vehicle (EV), in particular, on an electric motorcycle or the like. The motor 40 is, for example, a three-phase (u-phase, v-phase, w-phase) brushless DC motor or the like, and is attached to the wheels of the vehicle.

[0012] The main switch MSW is a start button or the like that is operated by the user to start the motor 40. In response to this user operation, the main switch MSW outputs a start signal STR for the motor 40 to the motor control device 10. The motor control device 10 is configured by a wiring board or the like on which various internal components are mounted as shown in Fig. 1. The internal configuration of the motor control device 10 will be described below.

[0013] The inverter 15 includes three-phase high-side switching elements HSu, HSv, and HSw and three-phase low-side switching elements LSu, LSv, and LSw, and supplies power (here, three-phase AC power) to the motor 40. The capacitor C1 is, for example, an electrolytic capacitor, and is connected to a power supply node Nc of the inverter 15 to stabilize the power supply of the inverter 15. The contactor 17 is a type of relay, and when controlled to be on, connects the power supply node Nb of the battery 30 and the power supply node Nc of the inverter 15. The contactor switch CSW controls the on / off of this contactor (relay) 17.

[0014] When the charge switch PSW is controlled to be on, it forms a charge path from the battery 30 to the capacitor C1. When the discharge switch DSW is controlled to be on, it forms a discharge path from the capacitor C1 to the ground power supply GND. The resistance element R1 is inserted at the overlapping portion of the charge path and the discharge path, and functions as a limiting element that limits the charge current and the discharge current. For example, the charge switch PSW is composed of a high-voltage p-channel MOSFET (Metal Oxide Semiconductor Field Effect Transistor) or the like, and the discharge switch DSW is composed of a high-voltage n-channel MOSFET or the like.

[0015] The diode D1 is inserted into the power supply node Nb of the battery 30 with the battery 30 side as the anode and the internal side of the motor control device 10 as the cathode. The diode D1 serves to cut off the current flowing into the power supply node Nb when the battery 30 is connected with reverse polarity. The voltage detection circuit 25 detects the battery voltage Vbat of the battery 30 and the capacitor voltage Vc of the capacitor C1. At this time, the selection circuit 26 selects whether to input the battery voltage Vbat or the capacitor voltage Vc to the voltage detection circuit 25.

[0016] In detail, the voltage detection circuit 25 includes a voltage divider circuit 19, an isolation amplifier 18, and an analog-to-digital converter ADC. The voltage divider circuit 19 includes, for example, a plurality of voltage dividing resistor elements and divides the input voltage of the input node Nin, that is, the voltage selected by the selection circuit 26. The isolation amplifier 18 includes, for example, a photocoupler or a transformer, and a predetermined internal circuit, and transmits the output voltage of the voltage divider circuit 19 to the controller 16.

[0017] In the isolation amplifier 18, the battery voltage Vbat is supplied to the input side of the photocoupler, etc., and the control voltage Vdd is supplied to the output side. A predetermined internal circuit controls the input of the photocoupler, etc., according to the output voltage of the voltage divider circuit 19, so that the photocoupler, etc., outputs a detection voltage Vdet that reflects the magnitude of the input voltage at the input node Nin, in the range of the control voltage Vdd.

[0018] The battery voltage Vbat is, for example, several tens of volts to several hundreds of volts. The control voltage Vdd is a power supply voltage of the controller 16, and is, for example, 3.3 V or 5 V. As described above, there is a large potential difference between the battery voltage Vbat and the control voltage Vdd. For this reason, an isolation amplifier 18 is provided. In this example, an analog-to-digital converter ADC is provided in the controller 16, and converts the detection voltage Vdet from the isolation amplifier 18 into a digital value. The control voltage Vdd is generated, for example, based on the battery voltage Vbat using a power regulator (not shown).

[0019] The selection circuit 26 includes an on-off switch SW1 and a rectifier element 21. The on-off switch SW1 is configured, for example, by a high-voltage MOSFET or the like, and is connected between a power supply node Nb of the battery 30 and an input node Nin of the voltage detection circuit 25. The rectifier element 21 is connected between a power supply node Nc of the inverter 15 and an input node Nin of the voltage detection circuit 25, and blocks a current in a direction from the input node Nin of the voltage detection circuit 25 toward the power supply node Nc of the inverter 15. In this example, the rectifier element 21 is configured as a diode with the power supply node Nc side as the anode and the input node Nin side as the cathode.

[0020] Here, when the on-off switch SW1 is controlled to be on, the battery voltage Vbat is input to the voltage detection circuit 25. At this time, the battery voltage Vbat transmitted to the input node Nin of the voltage detection circuit 25 is at least equal to or greater than the capacitor voltage Vc at the power supply node Nc of the inverter 15. Therefore, the rectifier element 21 blocks an unintended charging path from the input node Nin to the power supply node Nc, i.e., a charging path that does not pass through the charging switch PSW. On the other hand, when the on-off switch SW1 is controlled to be off, the capacitor voltage Vc is input to the voltage detection circuit 25 via the rectifier element 21 and the like.

[0021] Selection circuit 26 is not limited to this configuration, and may be configured to include a switch similar to on-off switch SW1 instead of rectifier element 21 and control each switch exclusively. However, by providing on-off switch SW1 on the high voltage side and rectifier element 21 on the low voltage side as in Fig. 1, the configuration and control can be simplified compared to the case where two switches are provided in this way.

[0022] The reverse current prevention circuit 20 is inserted in series with the rectifier element 21 between the input node Nin of the voltage detection circuit 25 and the power supply node Nc of the inverter 15. Depending on the configuration of the isolation amplifier 18, for example, when the isolation amplifier 18 is not powered on, a current may flow from the battery 30 to the power supply of the isolation amplifier 18 via a predetermined internal circuit in the isolation amplifier 18. The reverse current prevention circuit 20 is provided to prevent such a current from flowing in.

[0023] The controller 16 is configured, for example, by a microcontroller or the like, and controls the entire motor control device 10. As shown in Fig. 2, the controller 16 includes a precharge control unit 160, a fault detection unit 161, a PWM (Pulse Width Modulation) control unit 162, and the analog-to-digital converter ADC in the voltage detection circuit 25 described above.

[0024] The precharge control unit 160 and the fault detection unit 161 are realized, for example, by a processor in the microcontroller executing a program stored in a memory in the microcontroller. The PWM control unit 162 is realized, for example, by using a PWM timer in the microcontroller. However, the precharge control unit 160, the fault detection unit 161, and a part or all of the PWM control unit 162 are not limited to being realized by a microcontroller, and may be realized by hardware such as a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC).

[0025] The pre-charge control unit 160 pre-charges the capacitor C1 before controlling the contactor (relay) 17 to be turned on when the motor control device 10 is started. That is, if the contactor (relay) 17 is controlled to be turned on when the capacitor C1 is not charged when the motor control device 10 is started, a large inrush current may flow from the battery 30 to the capacitor C1 via the contactor 17. In this case, for example, deterioration of the capacitor C1 or welding of the contacts of the contactor 17 may occur.

[0026] Therefore, the precharge control unit 160 is provided. The main operation of the precharge control unit 160 is to control the charging switch PSW to be on based on the detection result of the voltage detection circuit 25, i.e., the output of the analog-digital converter ADC, until the capacitor voltage Vc reaches a charging end voltage determined based on the battery voltage Vbat. Accordingly, the capacitor C1 is gradually charged toward the charging end voltage with an RC time constant associated with the resistor element R1 and the capacitor C1.

[0027] The precharge control unit 160 outputs an on-off switch control signal SON, a charge switch control signal PON, a discharge switch control signal DON, and a contactor switch control signal CON. The on-off switch SW1 in Fig. 1 is controlled by the on-off switch control signal SON, and the contactor switch CSW, and hence the contactor 17, are controlled by the contactor switch control signal CON. The charge switch PSW in Fig. 1 is controlled by the charge switch control signal PON, and the discharge switch DSW is controlled by the discharge switch control signal DON.

[0028] The fault detection unit 161 detects, for example, an abnormality in the battery voltage Vbat or the capacitor voltage Vc as a fault based on the output of the analog-digital converter ADC, i.e., the detection voltage Vdet from the voltage detection circuit 25. The fault detection unit 161 may output an on-off switch control signal SON to switch the detection target. The PWM control unit 162 controls the switching of each switching element in the inverter 15 with three-phase PWM signals PWMu, PWMv, and PWMw.

[0029] 1, an insulating buffer 22 in the motor control device 10 receives an on-off switch control signal SON, a charge switch control signal PON, a discharge switch control signal DON, etc. from the controller 16, and outputs each control signal to the on-off switch SW1, the charge switch PSW, the discharge switch DSW, etc. The insulating buffer 22 includes, for example, a photocoupler or a transformer, and converts a control signal at the level of the control voltage Vdd into a control signal at the level of the battery voltage Vbat.

[0030] Controller Details Fig. 3 is a flow chart showing an example of the processing contents in the controller of Fig. 2. Fig. 3 can be roughly divided into steps S101 to S103 as a first step for detecting the battery voltage Vbat, steps S108 to S110 as a second step for charging the capacitor C1, and steps S105 to S107 performed between the first and second steps as a third step for discharging the capacitor C1.

[0031] 3, first, after the key switch of the vehicle is controlled to be on, the pre-charge control unit 160 controls the on-off switch SW1 to be on using the on-off switch control signal SON (step S101). As a result, the pre-charge control unit 160 causes the selection circuit 26 to select the battery voltage Vbat. The key switch is a switch for turning on the power supply to the vehicle before starting the motor 40.

[0032] Next, the precharge control unit 160 causes the voltage detection circuit 25 to detect the battery voltage Vbat (step S102) during the period until the main switch MSW for starting the motor 40 is turned on, that is, during the period before the start signal STR is input from the main switch MSW (step S103). Specifically, the precharge control unit 160 obtains a digital value from the analog-to-digital converter ADC.

[0033] Thereafter, when a start signal STR of the motor 40 is input, the pre-charge control unit 160 controls the on-off switch SW1 to be off using the on-off switch control signal SON (step S104). As a result, the pre-charge control unit 160 causes the selection circuit 26 to select the capacitor voltage Vc. Then, while causing the voltage detection circuit 25 to detect the capacitor voltage Vc (step S105), the pre-charge control unit 160 controls the discharge switch DSW to be on until the capacitor voltage Vc reaches a predetermined charging start voltage Vst (steps S106, S107).

[0034] Specifically, the precharge control unit 160 controls the discharge switch DSW to be on by using the discharge switch control signal DON until the capacitor voltage Vc becomes equal to or lower than the charging start voltage Vst while acquiring a digital value from the analog-digital converter ADC. When the discharge switch DSW is controlled to be on, the capacitor voltage Vc gradually decreases with an RC time constant toward the charging start voltage Vst.

[0035] Here, when the main switch MSW is controlled to be on in step S103, the capacitor C1 may still have charge remaining from the previous time the motor 40 was started. In this case, there is a risk that this may affect the subsequent charging operation (steps S108 to S110). Therefore, the pre-charge control unit 160 ensures that the capacitor voltage Vc is equal to or lower than the charging start voltage Vst in steps S105 to S107.

[0036] After steps S105 to S107, the precharge control unit 160 controls the charging switch PSW to be on (steps S109, S110) while continuing to cause the voltage detection circuit 25 to detect the capacitor voltage Vc (step S108) until the capacitor voltage Vc reaches the charging end voltage Ved. Specifically, while acquiring a digital value from the analog-to-digital converter ADC, the precharge control unit 160 controls the charging switch PSW to be on using the charging switch control signal PON until the capacitor voltage Vc becomes equal to or higher than the charging end voltage Ved. When the charging switch PSW is controlled to be on, the capacitor voltage Vc gradually rises with an RC time constant toward the charging end voltage Ved.

[0037] When the capacitor voltage Vc becomes equal to or higher than the charging end voltage Ved, the pre-charge control unit 160 controls the charging switch PSW to be turned off, and controls the contactor switch CSW, and therefore the contactor (relay) 17, to be turned on using the contactor switch control signal CON (step S111). As a result, it becomes possible to prevent an inrush current from the battery 30 to the capacitor C1 via the contactor 17. The charging end voltage Ved is determined based on the battery voltage Vbat detected in step S102, and is determined to be, for example, about 90% of the battery voltage Vbat. The charging start voltage Vst in step S106 is determined to be a value lower than the charging end voltage Ved.

[0038] <<Major Effects of the Embodiments>> Fig. 4 is a schematic diagram showing an example of the configuration of the main parts around a motor control device as a comparative example of the present invention. The motor control device 10' shown in Fig. 4 is different from the motor control device 10 shown in Fig. 1 in that it has two voltage detection circuits 25a and 25b. The voltage detection circuit 25a includes a voltage divider circuit 19a, an insulating amplifier 18a, and an analog-digital converter ADCa, and detects the battery voltage Vbat transmitted via the backflow prevention circuit 20a. On the other hand, the voltage detection circuit 25b includes a voltage divider circuit 19b, an insulating amplifier 18b, and an analog-digital converter ADCb, and detects the capacitor voltage Vc transmitted via the backflow prevention circuit 20b.

[0039] The analog-to-digital converters ADCa and ADCb are provided in the controller 16', as in the case of Fig. 1. The insulating buffer 22' transmits the charge switch control signal PON and the discharge switch control signal DON from the controller 16' to the charge switch PSW and the discharge switch DSW, respectively, as in the case of Fig. 1. The other configurations are also the same as those in Fig. 1.

[0040] However, as shown in FIG. 4, when the battery voltage Vbat and the capacitor voltage Vc are detected by the individual voltage detection circuits 25a and 25b, there is a possibility that relative variations in detection accuracy may occur between the voltage detection circuits 25a and 25b. For example, if the detection variation of the voltage detection circuit 25a is +6% and the detection variation of the voltage detection circuit 25b is -6%, a relative variation of up to 12% may occur. Such detection variations can occur particularly due to the performance of the isolation amplifiers 18a and 18b.

[0041] As a result, for example, the comparison determination between the capacitor voltage Vc and the charge completion voltage Ved in step S109 of FIG. 3 may become inaccurate. As a specific example, a situation may occur where, although actually Vc≧Ved, it is always determined that Vc<Ved and the loop of steps S108 to S110 cannot be exited. Also, a situation may occur where, although actually Vc<Ved, it is determined that Vc≧Ved and the inrush current associated with step S111 increases significantly more than the original design value. Furthermore, in addition to such a problem with the pre-charge control unit 160, the fault detection accuracy by the fault detection unit 161 in FIG. 2 may also decrease.

[0042] On the other hand, when using the configuration example of FIG. 1, since the voltage detection circuit 25 is shared, it becomes possible to reduce the relative variations in detection accuracy when detecting a plurality of voltages. As a result, the operation of the pre-charge control unit 160 can be accurately performed, and the inrush current can be set as per the original design value. Also, it becomes possible to improve the fault detection accuracy by the fault detection unit 161. Furthermore, as another effect, the circuit area can be reduced by sharing the voltage detection circuit 25. Also, the requirements for the accuracy of the isolation amplifier 18 or the voltage dividing circuit 19 can be relaxed. As a result of these, it becomes possible to reduce the cost of the motor control device 10.

[0043] The present invention is not limited to the above-mentioned embodiments, and various modifications are possible without departing from the spirit of the present invention. In addition, the material, shape, size, number, installation location, etc. of each component in each of the above-mentioned embodiments are arbitrary as long as the present invention can be achieved, and are not limited to each of the above-mentioned embodiments. [Explanation of symbols]

[0044] 10, 10': motor control device, 15: inverter, 16, 16': controller, 17: contactor (relay), 18, 18a, 18b: isolation amplifier, 19, 19a, 19b: voltage divider circuit, 20, 20a, 20b: reverse current prevention circuit, 21: rectifier element, 22, 22': isolation buffer, 25, 25a, 25b: voltage detection circuit, 26: selection circuit, 30: battery, 40: motor, 160: precharge control unit, 161: fault detection unit, 162: PWM control unit, ADC, ADCa, ADCb: analog-to-digital converter, C1: capacitor, CON: contactor switch control signal, CSW: contactor switch, D1; diode, DON: discharge switch control signal, DSW: discharge switch, HS(u,v,w): high-side switching element, LS(u,v,w): low-side switching element, MSW: main switch, Nb: power supply node, Nc: power supply node, Nin: input node, PON: charge switch control signal, PSW: charge switch, PWM(u,v,w): PWM signal, R1: resistive element, SON: on-off switch control signal, STR: start signal, SW1: on-off switch, Vbat: battery voltage, Vc: capacitor voltage, Vdd: control voltage, Vdet: detection voltage, Ved: charge end voltage, Vst: charge start voltage

Claims

1. An inverter that supplies power to the motor; a capacitor connected to a power supply node of the inverter; a relay that connects a power supply node of a battery and a power supply node of the inverter when the relay is controlled to be on; a charging switch that forms a charging path from the battery to the capacitor when the charging switch is turned on; a limiting element inserted in the charging path from the battery to the capacitor to limit a charging current; a voltage detection circuit, a selection circuit and a controller; having The selection circuit includes: selecting whether to input a battery voltage of the battery or a capacitor voltage of the capacitor to the voltage detection circuit; an on-off switch connected between a power supply node of the battery and an input node of the voltage detection circuit; a rectifying element connected between a power supply node of the inverter and an input node of the voltage detection circuit, for blocking a current in a direction from the input node of the voltage detection circuit toward the power supply node of the inverter; having a reverse current prevention circuit is connected in series to the rectifier between the input node of the voltage detection circuit and a power supply node of the inverter, the reverse current prevention circuit blocking a current in a direction from the power supply node of the inverter to the input node of the voltage detection circuit under a predetermined condition; The controller: before controlling the relay to be on, controlling the charging switch to be on until the capacitor voltage reaches a charging end voltage determined based on the battery voltage, based on a detection result of the voltage detection circuit; By controlling the on-off switch to an on state, the voltage detection circuit is caused to detect the battery voltage, and by controlling the on-off switch to an off state, the voltage detection circuit is caused to detect the capacitor voltage. Motor control device.

2. The voltage detection circuit includes: A voltage divider circuit that divides an input voltage; an isolation amplifier that transmits an output voltage of the voltage divider circuit to the controller; having The motor control device according to claim 1 .

3. 3. The motor control device according to claim 1, a discharge switch that forms a discharge path from the capacitor to a ground power supply when the discharge switch is controlled to be on; The limiting element is inserted at an overlapping portion of the charging path and the discharging path. Motor control device.

4. An inverter that supplies power to the motor; a capacitor connected to a power supply node of the inverter; a relay that connects a power supply node of a battery and a power supply node of the inverter when the relay is controlled to be on; a charging switch that forms a charging path from the battery to the capacitor when the charging switch is turned on; a limiting element inserted in the charging path from the battery to the capacitor to limit a charging current; a voltage detection circuit for detecting a battery voltage of the battery and a capacitor voltage of the capacitor; a selection circuit for selecting whether the battery voltage or the capacitor voltage is to be input to the voltage detection circuit; A method for starting a motor control device comprising: before controlling the relay to be on, controlling the charging switch to be on until the capacitor voltage reaches a charging end voltage determined based on the battery voltage, based on a detection result of the voltage detection circuit; a first step of causing the selection circuit to select the battery voltage in a period before a start signal for the motor is input in response to a user operation, thereby causing the voltage detection circuit to detect the battery voltage; a second step of controlling the charging switch to be on until the capacitor voltage reaches the charging end voltage while causing the selection circuit to select the capacitor voltage and causing the voltage detection circuit to detect the capacitor voltage during a period after the start signal of the motor is input; having A method for starting a motor control device.

5. 5. The method for starting a motor control device according to claim 4, the motor control device has a discharge switch that forms a discharge path from the capacitor to a ground power supply when the discharge switch is controlled to be on; a third step of controlling the discharge switch to be on until the capacitor voltage reaches a predetermined charging start voltage while causing the selection circuit to select the capacitor voltage and causing the voltage detection circuit to detect the capacitor voltage during a period between the first step and the second step; A method for starting a motor control device.

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