Motor Drive Unit

Abstract

To provide a motor drive device capable of driving a motor relay with a simple construction.SOLUTION: A three-phase pre-driver circuit 40 of a motor drive device 101, is operated by a voltage supplied from a battery 15 to drive a plurality of switching elements 61 to 66 of an inverter 60. A plurality of motor relays 71, 72, and 73 constructed by a semiconductor switching element, are provided between arm inter-connection points Nu, Nv, and Nw of each phase and each of phase windings 81, 82, and 83 of a polyphase motor, and disconnect a current to the inverter 60 side from a three-phase motor 80 side at the time of OFF. The three-phase pre-driver circuit 40 includes a charge pump 43 for rising the voltage of the battery 15. An output end of the charge pump 43 is connected to a gate of the motor relays 71, 72, and 73 of each phase. In an operation of the charge pump 43, the motor relays 71, 72, and 73 of each phase are turned ON by the output voltage of the charge pump 43 except when a command is sent from a control part 30.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a motor drive device. [Background technology]

[0002] 2. Description of the Related Art Conventionally, there has been known a motor drive device that converts DC power from a battery using an inverter and supplies the converted power to a polyphase motor.

[0003] For example, the electric motor drive device disclosed in Patent Document 1 is provided with a plurality of motor relays capable of interrupting a current path connecting an inter-arm connection point of each phase of an inverter with a motor winding. The plurality of motor relays are driven by a driver circuit common to the reverse connection protection relay. By reducing the number of driver circuits, the device can be made more compact and highly integrated. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-45576 A Summary of the Invention [Problem to be solved by the invention]

[0005] Conventionally, drive devices for auxiliary motors mounted on vehicles have generally been designed assuming a battery voltage of 12V. In the future, the battery voltage for auxiliary devices in electric vehicles is expected to be increased to 24V or 48V, which will exceed the voltage resistance of conventional drive circuits with a 12V specification. Therefore, in addition to an inverter that can be driven at high voltage, a driver circuit to drive the motor relay will be required, which will be an obstacle in terms of miniaturization and high integration of motor drive devices.

[0006] The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a motor drive device capable of driving a motor relay with a simple configuration. [Means for solving the problem]

[0007] The motor drive device of the present invention comprises: Applied to electric vehicles, An inverter (60), a multi-phase pre-driver circuit (40), a control unit (30), and a plurality of motor relays (71, 72, 73), one or more gate shutoff switches (47, 471, 472, 473), a reverse polarity protection relay (52), The inverter comprises: 24V or 48V The inverter includes upper and lower arm switching elements (61-66) of multiple phases connected in series between a power supply line (Lp) connected to a battery (15) and a ground line (Lg), and converts the DC power of the battery and supplies it to a polyphase motor (80).

[0008] The multi-phase pre-driver circuit operates on the voltage supplied from the battery and drives multiple switching elements of the inverter. The circuit has a charge pump (43) that boosts the battery voltage. The control unit issues a drive signal to the multi-phase pre-driver circuit to control the supply of current from the inverter to the multi-phase motor.

[0009] A plurality of motor relays each composed of a semiconductor switching element are provided between inter-arm connection points (Nu, Nv, Nw) which are connection points of the switching elements of the upper and lower arms of each phase and each phase winding (81, 82, 83) of the polyphase motor; The output of the charge pump is connected to the gate of each phase. When turned off, it cuts off the current from the polyphase motor to the inverter. The gate cutoff switch cuts off the gate voltage supplied from the output terminal of the charge pump to the motor relay when a cutoff signal is input from the control unit.

[0010] The reverse connection protection relay has a return diode connected in parallel that conducts current from the battery side to the inverter side, and the output terminal of the charge pump is connected to its gate. When the relay is turned off, it cuts off the current from the inverter side to the battery side. During charge pump operation, the motor relays of each phase are turned on unless a command is received from the control unit. and reverse connection protection relay is turned on by the output voltage of the charge pump.

[0011] As a result, the present invention does not require a dedicated driver circuit for the motor relay. Therefore, the motor relay can be driven with a simple configuration. In addition, when the battery voltage is increased from 12V to 24V or 48V, the charge pump voltage for driving the inverter is increased, and the motor relay can be driven accordingly. [Brief description of the drawings]

[0012] [Figure 1]FIG. 1 is a configuration diagram of a motor drive device according to a first embodiment. [Diagram 2] FIG. 2 is a circuit diagram showing a motor relay drive configuration in the motor drive device of the first embodiment. [Diagram 3] FIG. 11 is a circuit diagram showing a motor relay drive configuration in a motor drive device according to a second embodiment. [Figure 4] FIG. 11 is a circuit diagram showing a motor relay drive configuration in a motor drive device according to a third embodiment. [Diagram 5] FIG. 13 is a circuit diagram showing a motor relay drive configuration in a motor drive device according to a fourth embodiment. [Figure 6] FIG. 4 is a configuration diagram of a motor drive device of a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] A motor drive device according to multiple embodiments of the present invention will be described with reference to the drawings. In multiple embodiments, substantially the same configurations are given the same reference numerals and descriptions thereof will be omitted. The first to fourth embodiments are collectively referred to as "the present embodiment." In the present embodiment, the "polyphase motor" is a three-phase motor, and the "polyphase pre-driver circuit" is a three-phase pre-driver circuit. The motor drive device of the present embodiment converts DC power of a battery in an electric power steering device and supplies it to a steering assist motor. The steering assist motor is composed of a three-phase brushless motor.

[0014] In addition, while the voltage of auxiliary batteries mounted on vehicles has generally been 12V in the past, this embodiment mainly assumes 24V or 48V, which are expected to be adopted in electric vehicles in the future. In the drawings and the following specification, "24V / 48V" means "24V or 48V". However, the configuration of this embodiment is basically the same even when a 12V battery is used. This embodiment may be applied not only to electric vehicles but also to engine vehicles.

[0015] Specifically, the ECU of the electric power steering device functions as the motor drive device. The ECU is composed of a microcomputer or a customized integrated IC, and includes a CPU, ROM, RAM, I / O, and bus lines connecting these components (not shown). The ECU executes software processing by having the CPU execute a program stored in advance in a physical memory device (i.e., a readable non-transitory tangible recording medium) such as a ROM, or executes control through hardware processing using a dedicated electronic circuit.

[0016] (First embodiment) Fig. 1 shows the configuration of a motor drive device 101 of the first embodiment. The motor drive device 101 includes an inverter 60, a three-phase pre-driver circuit 40, a microcomputer 30 as a "controller", and multiple motor relays 71, 72, 73, etc. Fig. 1 shows the configuration of a single-system motor drive device 101, but a redundant configuration of two or more systems may also be used. For example, in a two-system motor drive device, power is supplied from two inverters to a double-winding motor having two winding sets.

[0017] The inverter 60 is provided between a power supply line Lp connected to the positive electrode of the battery 15 and a ground line Lg connected to the negative electrode of the battery 15. The inverter 60 includes three-phase upper and lower arm switching elements 61-66 connected in series between the power supply line Lp and the ground line Lg. More specifically, the upper arm switching elements 61, 62, 63 and the lower arm switching elements 64, 65, 66 of the U-phase, V-phase, and W-phase are bridge-connected. In this embodiment, MOSFETs are used as the switching elements 61-66 of the inverter 60. The MOSFETs used in this embodiment are basically N-channel type.

[0018] The connection points of the switching elements of the upper and lower arms of each phase are defined as "inter-arm connection points Nu, Nv, Nw." The inter-arm connection points Nu, Nv, Nw are connected to three-phase windings 81, 82, 83 of a motor 80, respectively. The inverter 60 converts DC power of the battery 15 and supplies it to the three-phase windings 81, 82, 83. For example, in the case of a Y-connected motor 80, the three-phase windings 81, 82, 83 are connected at a neutral point Nm. The three-phase windings 81, 82, 83 may be Δ-connected.

[0019] The inverter capacitor 56 is connected in parallel with the inverter 60 between the power supply line Lp and the ground line Lg, and is charged with the voltage applied to the inverter 60. During normal operation of the motor driving device 101, the inverter capacitor 56 functions as a smoothing capacitor.

[0020] A filter capacitor 16 and a choke coil (inductor) 17 that configure a noise suppression LC filter circuit are provided on the battery 15 side of the inverter 60. The filter capacitor 16 and the inverter capacitor 56 are, for example, polarized aluminum electrolytic capacitors. The choke coil 17 is provided on the power supply line Lp.

[0021] 1, a reverse connection protection relay 52 is connected to a power supply line Lp between the choke coil 17 and the inverter 60. A freewheel diode that conducts a current from the battery 15 side to the inverter 60 side is connected in parallel to the reverse connection protection relay 52, and when the reverse connection protection relay 52 is turned off, the reverse connection protection relay 52 cuts off the current from the inverter 60 side to the battery 15 side. For example, in the reverse connection protection relay 52 that is made up of a MOSFET, a parasitic diode of the MOSFET functions as the freewheel diode. In another configuration example, the reverse connection protection relay 52 may be provided on the ground line Lg.

[0022] In another configuration example, a power supply relay may be provided at the position X indicated by the two-dot chain line, i.e., on the battery 15 side of the reverse connection protection relay 52. ​​In this case, the power supply relay has a free wheel diode connected in parallel to it, which conducts current from the inverter 60 side to the battery 15 side, and cuts off the current from the battery 15 side to the inverter 60 side when it is OFF.

[0023] The motor relays 71, 72, 73 are provided in motor current paths between the inter-arm connection points Nu, Nv, Nw of each phase and the three-phase windings 81, 82, 83. The motor relays 71, 72, 73 are composed of MOSFETs which are semiconductor switching elements. Parasitic diodes conduct current from the inter-arm connection points Nu, Nv, Nw to the three-phase windings 81, 82, 83. When the motor relays 71, 72, 73 are turned off, they cut off the current from the motor 80 side to the inverter 60 side.

[0024] Although not shown, a current sensor for detecting phase current is provided in the inverter 60 or in the motor current path of each phase. During normal operation of the motor drive device 101, the microcomputer (controller) 30 calculates a drive signal for the inverter 60 by current feedback control based on the phase current detection value and the motor rotation angle so that the motor 80 outputs a command torque. Note that an integrated IC may take on some of the functions of the microcomputer 30 as the control unit. In addition, in the case of a two-system configuration, control information may be mutually communicated between the microcomputers of each system.

[0025] Next, FIG. 2 will be referred to together with FIG. 2 particularly shows the configuration of the three-phase pre-driver circuit 40 and the drive configuration of motor relays 71, 72, and 73. The three-phase pre-driver circuit 40 operates with voltage supplied from the battery 15, and drives a plurality of switching elements 61-66 of the inverter 60. The microcomputer 30 issues a drive signal to the three-phase pre-driver circuit 40 to control the supply of electricity from the inverter 60 to the three-phase motor 80.

[0026] A power supply voltage of 24V / 48V is supplied to the three-phase pre-driver circuit 40 from the power supply line Lp after the choke coil 17. In FIG. 2, the power supply voltage of 24V / 48V is indicated as "PIG." A power supply voltage of 12V is also supplied from the power supply line Lp via a step-down regulator 18. If the battery voltage is 12V, the step-down regulator 18 is not necessary.

[0027] The three-phase pre-driver circuit 40 has a charge pump 43 that boosts the battery voltage. The output voltage of the charge pump 43 is referred to as a charge pump voltage Vcp. The voltage of 12V input via the step-down regulator 18 is referred to as a non-boosted voltage Vnb. The charge pump voltage Vcp is output to the gates of the upper arm (high side) switching elements 61-63. The non-boosted voltage Vnb is output to the gates of the lower arm (low side) switching elements 64-66. In the figure, "HS" stands for high side, and "LS" stands for low side.

[0028] While the power supply voltage is being supplied to the three-phase pre-driver circuit 40, the charge pump 43 superimposes the voltage charged in the capacitor Ccp and basically continues to output a constant voltage at all times. If the supply of the power supply voltage to the three-phase pre-driver circuit 40 is interrupted, or if the charge pump voltage Vcp exceeds an upper limit threshold or falls below a lower limit threshold, the operation of the charge pump 43 is stopped by a logic circuit in the three-phase pre-driver circuit 40.

[0029] In this embodiment, the output terminal of the charge pump 43 is connected to the gates of the motor relays 71, 72, and 73 of the respective phases. For example, in the configuration of the first embodiment, charge pump voltage paths 461, 462, and 463 of the respective phases branch off from the charge pump voltage path 46 common to the three phases, which is connected to the output terminal of the charge pump 43, and are connected to the gates of the motor relays 71, 72, and 73 of the respective phases.

[0030] As a result, during operation of the charge pump 43, except when there is a command (i.e., a shutoff signal described below) from the microcomputer 30, the motor relays 71, 72, 73 of each phase are turned ON by the output voltage Vcp of the charge pump 43. In other words, the motor relays 71, 72, 73 can be turned ON by utilizing the charge pump voltage Vcp required to drive the upper arm switching elements 61-63 of the inverter 60, without using a driver circuit dedicated to the motor relays.

[0031] In order to intentionally turn off the motor relays 71, 72, and 73 while the charge pump 43 is in operation, in the first embodiment, a three-phase common gate cutoff switch 47 made of a MOSFET is provided between the three-phase common charge pump voltage path 46 and ground. In the first embodiment, when a cutoff signal common to the three phases is input from the microcomputer 30, the gate cutoff switch 47 turns on and grounds the charge pump voltage path 46. As a result, the gate voltage supplied from the output terminal of the charge pump 43 to the motor relays 71, 72, and 73 is cut off, and the motor relays 71, 72, and 73 are simultaneously turned off.

[0032] In normal operation of three-phase motor 80, current is simultaneously started and stopped to three-phase windings 81, 82, 83. When a back electromotive force generated by an external force is regenerated from motor 80 to battery 15 via inverter 60, it is considered that a regenerative current flows through the three phases at the same time. In such a case, it is effective to turn off motor relays 71, 72, 73 with a cutoff signal common to the three phases.

[0033] 1, the output terminal of the charge pump 43 is connected to the gate of the reverse connection protection relay 52 via another charge pump voltage path 45. Therefore, the reverse connection protection relay 52 can also be turned on by using the charge pump voltage Vcp without using a dedicated driver circuit. However, in this embodiment, the driving of the reverse connection protection relay 52 is a supplementary matter. In FIG. 2, the reverse connection protection relay 52 is not shown.

[0034] 6, the effects of the first embodiment will be described in comparison with a comparative motor drive device 109. The comparative motor drive device 109 includes a relay driver circuit 49 that can commonly drive the motor relays 71, 72, and 73 and the reverse connection protection relay 52 based on a drive signal from a microcomputer 30. The comparative motor drive device 109 is based on the conventional technology of Patent Document 1 (JP 2014-45576 A, corresponding US publication: US2014 / 055059A1).

[0035] In the comparative example, the motor relays 71, 72, and 73 and the reverse connection protection relay 52 share a common driver circuit, thereby achieving miniaturization and high integration, but the driver circuit dedicated to the relays is still required, which results in an increase in size and cost of the device.

[0036] In contrast, in the first embodiment, the motor relays 71, 72, and 73 are driven by the output voltage Vcp of the charge pump 43, so that a driver circuit dedicated to the motor relays is not required. Therefore, the motor relays 71, 72, and 73 can be driven with a simple configuration. In addition, when the battery voltage is increased from 12V to 24V / 48V, for example, the charge pump voltage Vcp for driving the inverter 60 is increased, and therefore the motor relays 71, 72, and 73 can also be driven.

[0037] Second embodiment A second embodiment will be described with reference to Fig. 3. Figs. 3 to 5, which will be referred to in the following second to fourth embodiments, show the drive configuration of motor relays 71, 72, and 73, similar to Fig. 2 of the first embodiment. In a motor drive device 102 of the second embodiment, gate cutoff switches 471, 472, and 473 are provided for each phase between charge pump voltage paths 461, 462, and 463 of each phase and ground.

[0038] Each of the gate cutoff switches 471, 472, 473 turns ON when a cutoff signal is input from the microcomputer 30, and turns OFF the motor relays 71, 72, 73 of each phase individually by grounding the charge pump voltage paths 461, 462, 463. In other words, based on the cutoff signal for each phase from the microcomputer 30, the gate cutoff switch 471 can individually cut off the gate voltage supplied to the U-phase motor relay 71, the gate cutoff switch 472 can individually cut off the gate voltage supplied to the V-phase motor relay 72, and the gate cutoff switch 473 can individually cut off the gate voltage supplied to the W-phase motor relay 73.

[0039] In the second embodiment, when the current supply to the three phases is normally stopped at the same time, the microcomputer 30 outputs a cutoff signal for the three phases at the same time. On the other hand, there is a technique for driving the two normal phases when, for example, an inverter switching element or a current sensor of one of the three phases fails. In that case, in the second embodiment, it is possible to individually cut off only the motor relay of the phase to be stopped from driving.

[0040] In a motor drive device having a redundant two-system configuration applied to an electric power steering device, when one phase of one system fails, the entire abnormal system is usually stopped and the drive is switched to the normal system. Therefore, switching from three-phase drive to two-phase drive is mainly useful in a motor drive device having a single system.

[0041] Third embodiment The third embodiment will be described with reference to Fig. 4. In a motor drive device 103 of the third embodiment, gate cutoff switches 471, 472, and 473 are provided in charge pump voltage paths 461, 462, and 463 of the respective phases. The gate cutoff switches 471, 472, and 473 can individually cut off motor relays 71, 72, and 73 of the respective phases by cutting off charge pump voltage paths 461, 462, and 463 based on a cutoff signal for each phase from the microcomputer 30. The third embodiment also provides the same effects as the second embodiment.

[0042] A common gate cutoff switch 47 in the same manner as in the third embodiment may be provided midway along the charge pump voltage path 46 common to the three phases in FIG. 1 of the first embodiment.

[0043] (Fourth embodiment) A fourth embodiment will be described with reference to FIG. 5. In a motor drive device 104 of the fourth embodiment, gate cutoff switches for motor relays 71, 72, and 73 are not provided. Instead, a signal to stop the operation of charge pump 43 is output from microcomputer 30. Charge pump 43 is configured so that no residual voltage remains after operation is stopped. By outputting a stop signal to charge pump 43, microcomputer 30 stops the operation of inverter 60 and simultaneously turns off motor relays 71, 72, and 73 of each phase. Even with this configuration, motor relays 71, 72, and 73 can be intentionally turned off.

[0044] (Other embodiments) (a) The motor drive device of the present invention does not need to include a reverse connection protection relay. Also, it is sufficient to drive the motor relays 71, 72, and 73 of each phase with the charge pump voltage Vcp, and it is not necessary to drive the reverse connection protection relay with the charge pump voltage Vcp.

[0045] (b) The motor relays 71, 72, 73 and the gate cutoff switches 47, 471, 472, 473 are not limited to MOSFETs and may be configured with other semiconductor switching elements such as bipolar transistors.

[0046] (c) The number of phases of the polyphase motor and the polyphase pre-driver circuit is not limited to three, but may be two, four or more.

[0047] (d) The motor drive device of the present invention may be applied to in-vehicle devices other than electric power steering devices, and to drive various types of polyphase motors other than devices mounted on vehicles.

[0048] The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit of the present invention.

[0049] The control unit and the method described in the present disclosure may be realized by a special-purpose computer provided by configuring a processor and a memory programmed to execute one or more functions embodied in a computer program. Alternatively, the control unit and the method described in the present disclosure may be realized by a special-purpose computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described in the present disclosure may be realized by one or more special-purpose computers configured by a combination of a processor and a memory programmed to execute one or more functions and a processor configured with one or more hardware logic circuits. In addition, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions executed by a computer. [Explanation of symbols]

[0050] 101-104 Motor drive device, 15 Battery, 30...Microcomputer (control unit), 40 Three-phase pre-driver circuit (multi-phase pre-driver circuit), 43 Charge pump, 60... Inverter, 61-66... ​​Switching element, 71, 72, 73: Motor relay, 80... Motor, three-phase motor (polyphase motor), 81, 82, 83... Winding, Lp...Power line, Lg...Ground line, Nu, Nv, Nw: Inter-arm connection points.

Claims

1. Applied to an electric vehicle, an inverter (60) including upper and lower arm switching elements (61-66) of multiple phases connected in series between a power supply line (Lp) connected to a 24V or 48V battery (15) and a ground line (Lg), which converts DC power of the battery and supplies the converted power to a polyphase motor (80); a multi-phase pre-driver circuit (40) that operates by a voltage supplied from the battery and drives a plurality of switching elements of the inverter, the multi-phase pre-driver circuit having a charge pump (43) that boosts the voltage of the battery; a control unit (30) that issues a drive signal to the multi-phase pre-driver circuit and controls current supply from the inverter to the multi-phase motor; a plurality of motor relays (71, 72, 73) each of which is composed of semiconductor switching elements and is provided between inter-arm connection points (Nu, Nv, Nw) which are connection points of the switching elements of the upper and lower arms of each phase and each phase winding (81, 82, 83) of the multi-phase motor, the output end of the charge pump being connected to the gate of each phase, and which cut off current from the multi-phase motor side to the inverter side when turned off; one or more gate cutoff switches (47, 471, 472, 473) for cutting off a gate voltage supplied from an output terminal of the charge pump to the motor relay when a cutoff signal is input from the control unit; a reverse connection protection relay (52) to which a return diode for conducting a current from the battery side to the inverter side is connected in parallel, an output terminal of the charge pump is connected to a gate, and which cuts off the current from the inverter side to the battery side when turned off; Equipped with The motor drive device wherein, during operation of the charge pump, the motor relay and the reverse connection protection relay of each phase are turned ON by the output voltage of the charge pump, except when there is a command from the control unit.

2. 2. The motor drive device according to claim 1, wherein the gate cutoff switch is provided for each phase and is capable of individually cutting off the gate voltage supplied to the motor relay of each phase based on a cutoff signal for each phase from the control unit.

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