JP6241098B2 - In-vehicle motor controller - Google Patents

Description

  The present invention relates to an in-vehicle motor control device.

  Conventionally, in an electric vehicle that travels by driving an electric motor with an alternating current converted by an inverter (for example, a hybrid vehicle or an electric vehicle), the electric motor is connected to a high-voltage inverter. In this in-vehicle motor control device, it is necessary to detect an abnormality caused by a failure of a switching power element of an inverter, a grounding of a motor wiring and a motor coil, and prevent leakage and electric shock. For this reason, various detection methods for detecting an abnormality in the inverter and the electric motor by providing a current detector for detecting the current amount of the electric motor in each phase have been proposed (for example, see Patent Document 1).

JP 2007-60866 A

  Normally, such abnormality detection is performed by current detection using current detectors provided for all phases (three phases), and the total value of the three-phase currents is zero when normal, whereas in any phase When the entanglement occurs, an abnormality is detected because the total value of the three-phase current does not become zero. However, in a high-voltage, high-current inverter, as a current detector, for example, a method of capturing a magnetic flux generated when a current flows through a current path by a Hall element and measuring the amount of current in a non-contact manner based on the amount of the magnetic flux May be used. For this reason, an expensive current detector with an insulation function is required for all phases, which increases the number of peripheral circuits, increases the complexity and size of the motor controller, increases costs, and always adds the three-phase current. There is a possibility that the efficiency and reliability of the entire system may be reduced due to the generation of computation load.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a vehicle-mounted motor control device that can detect a ground fault of an inverter and an electric motor using a magnetic detection element, and can be reduced in size and cost. Is to provide.

In order to solve the above-mentioned problem, the invention described in claim 1 includes a plurality of switching elements, an inverter that supplies a drive current to the electric motor, and a direct current power source that drives the electric motor, And a control circuit for controlling the inverter, wherein the power circuit opens and closes a connection between the DC power source and the inverter, and a converter supplies power to the inverter. A current ripple absorbing smoothing capacitor, a plurality of bus bars electrically connected to the electrodes of the DC power supply and serving as a power supply circuit, and a magnetic detection element for detecting a magnetic component in a predetermined direction. The magnetic detection element includes a distance between the magnetic detection element and each bus bar between the positive and negative bus bars arranged in parallel. It is attached to a position equal to the gist that you detect the ground fault occurs when the resistance change rate of the magnetic detecting element is outputted decreases.

  According to the above configuration, since the magnetic detection elements are arranged at equidistant positions between the bus bars electrically connected to the positive and negative electrodes of the DC power supply, the current flowing on the negative side of the power supply circuit is changed to the current flowing on the positive side. If the comparison is reduced, the magnetic flux density of the magnetic flux passing through the inside of the magnetic detection element is reduced, and the resistance value output from the magnetic detection element is changed. Thereby, it is possible to detect a leakage in the inverter or a ground fault in the inverter output unit and the motor wiring. As a result, an expensive insulation type current detector for ground fault detection and peripheral circuits added for three-phase current detection can be reduced, and the motor control device can be reduced in size and cost. . Further, since the current calculation load of the motor control device for detecting leakage can be reduced, the efficiency and reliability of the entire system can be improved.

According to a second aspect of the present invention, in the in-vehicle motor control device according to the first aspect, when the resistance change rate of the magnetic detection element is reduced and output , the power relay is shut off and the inverter is connected to the inverter. The gist is to stop the power supply. According to the said structure, when the generation | occurrence | production of the electric leakage by a ground fault is detected using a magnetic detection element, the power supply to an inverter can be stopped and an inverter can be protected by interrupting | blocking a power supply relay.

  According to a third aspect of the present invention, in the in-vehicle motor control device according to the first or second aspect, the magnetic detection element is a magnetoelectric conversion element that detects a power supply current of the power supply circuit using a magnetoresistive effect. This is the gist. According to the above configuration, since the magnetoelectric transducer that detects the change in the resistance value using the magnetoresistive effect is attached as the magnetic detection element, the power supply current is detected in a non-contact and insulated state, and the change in the resistance value is caused by the ground fault. The occurrence of electric leakage can be detected and the inverter can be protected.

  ADVANTAGE OF THE INVENTION According to this invention, the ground fault detection of an inverter and an electric motor can be performed using a magnetic detection element, and the vehicle-mounted motor control apparatus which can be reduced in size and cost can be provided.

The figure which shows schematic structure of the vehicle carrying the vehicle-mounted motor control apparatus which concerns on embodiment of this invention. The figure which shows the circuit structure of the vehicle-mounted motor control apparatus of FIG. The figure which shows schematic circuit structure of the magnetic detection element and inverter which concern on embodiment of this invention. (A) is a circuit diagram which shows the output of a magnetic detection element, (b) is a figure which shows the relationship between magnetic flux density and the resistance change rate of a magnetic detection element. (A) is a figure which shows the relationship between the magnetic flux which generate | occur | produces with the bus bar at the time of normal, and a magnetic detection element, (b) is a figure which shows the relationship between the magnetic flux which generate | occur | produces with the bus bar at the time of a ground fault, and a magnetic detection element. (A) is a figure which shows schematic structure of the magnetic detection element and bus bar which concern on other embodiment of this invention, (b) is generate | occur | produced with the bus bar at the time of the occurrence of a ground fault concerning other embodiment of this invention. The figure which shows the relationship between magnetic flux and a magnetic detection element.

Next, an in-vehicle motor control device mounted on a vehicle according to an embodiment of the present invention will be described based on the drawings.
FIG. 1 is a diagram showing a schematic configuration of a vehicle on which an in-vehicle motor control device (ECU, hereinafter referred to as a motor control device) 1 according to an embodiment of the present invention is mounted. As shown in FIG. 1, a vehicle (for example, a hybrid vehicle or an electric vehicle) drives a DC power source (hereinafter referred to as a high voltage battery) 6, a vehicle control unit 16, a rear wheel drive unit 18, and a rear wheel 17. And a motor control device 1 that controls the electric motor 8 to be used. The rear wheel drive unit 18 includes an electric motor 8, a reduction gear (differential gear) 4, and a clutch 5, and the clutch 5 is installed at the final stage of the reduction gear 4. For example, a three-phase brushless motor is used as the electric motor 8 for the drive source. The electric motor 8 is a permanent magnet type such as an IPM motor including an embedded magnet type rotor in which a permanent magnet is embedded and fixed in a rotor core, and an SPM motor including a surface magnet type rotor in which a permanent magnet is fixed to the surface of the rotor core. A synchronous motor is used.

  The high-voltage battery 6 is a high-voltage (for example, 245 V) DC power source, and is composed of, for example, a chargeable / dischargeable secondary battery such as nickel metal hydride or lithium ion, and is disposed behind the rear seat of the vehicle. The motor control device 1 boosts the DC voltage received from the high-voltage battery 6 to a higher voltage (for example, 500 V, etc.) by the power supply circuit 2 according to the specifications of the inverter 3 that is a motor drive circuit (or remains unboosted) ) And supply to the inverter 3. Further, the motor control device 1 supplies and charges the high-voltage battery 6 with the electric power generated by the electric motor 8 during regenerative braking of the electric motor 8. The motor control device 1 is mounted, for example, under the rear seat of the vehicle.

  Furthermore, the motor control device 1 includes a control circuit (signal processing circuit) 9 that controls the rear wheel drive unit 18 and the like. The control circuit 9 is connected to an auxiliary power source (hereinafter referred to as a low voltage battery) 7 having a low voltage (for example, 12V), receives a command from the vehicle control unit 16 that controls driving of the vehicle, and is connected to the clutch 5. Thus, the driving force generated by driving the electric motor 8 is transmitted to the rear wheel 17. Further, when a higher DC voltage is required, the motor control device 1 boosts the DC voltage of the high voltage battery 6 by the boost converter 19 (see FIG. 2) and stabilizes it by the smoothing capacitor 15 (see FIG. 2). The power supply circuit 2 to be operated, the control circuit 9, and the inverter 3 are included.

  FIG. 2 is a diagram showing a circuit configuration of the motor control device 1 of FIG. As shown in FIG. 2, the motor control device 1 boosts the DC voltage of the high voltage battery 6 connected to the power relay 14 by the boost converter 19 and stabilizes it by the smoothing capacitor 15, the control circuit 9, The inverter 3 is included. Boost converter 19 includes, for example, a reactor (not shown), a switching element (for example, a MOSFET), and a smoothing capacitor. The smoothing capacitor 15 is connected between the power supply line P1 on the output side of the boost converter 19 connected to the high voltage battery 6 and the ground line P2. The smoothing capacitor 15 accumulates charges, and discharges the accumulated charges when the current flowing from the high voltage battery 6 to the inverter 3 is insufficient. As described above, the smoothing capacitor 15 functions as a capacitor that absorbs current ripple and smoothes the power supply voltage for driving the electric motor 8.

  The power supply circuit 2 includes a discharge resistor (not shown) and a drive circuit (for example, a MOSFET) that discharge the electric charge of the smoothing capacitor 15, and a regenerative resistor (not shown) that consumes power during regenerative braking (deceleration) of the electric motor 8. The drive circuit (for example, MOSFET etc.) is included. Furthermore, a snubber capacitor (not shown) is connected to both ends of the power supply of the power transistor (switching element) of the inverter 3 for use in a snubber for suppressing a surge voltage applied to the power transistor and protecting the power transistor. Here, as the smoothing capacitor 15 or the snubber capacitor, for example, a large film capacitor capable of handling a high voltage and a large current is used.

  The inverter 3 has U-phase, V-phase, and W-phase arms connected in parallel between the power supply line P1 and the ground line P2. And the connection point of each power transistor in each phase arm is connected to the coil end opposite to the neutral point of each phase coil (see FIG. 3) of the electric motor 8. As the power transistor, for example, an IGBT or a MOSFET is used.

  Further, the motor control device 1 is connected with a power relay 14, two phase current detectors 12 for detecting the phase current, and a power source current detector 13 for detecting the power current. The power relay 14 is a power switch that switches whether the smoothing capacitor 15 and the inverter 3 are connected to the high voltage battery 6 disposed outside the motor control device 1. The power relay 14 is turned on (conductive state) when the rear wheel drive unit 18 (see FIG. 1) is operated, and is turned off (non-conductive state) when stopped.

  The control circuit 9 controls the six power transistors included in the inverter 3. More specifically, various data used for current command value calculation are input to the control circuit 9, and a three-phase (U, V, W phase) drive current (U-phase current) to be supplied to the electric motor 8. , V-phase current, and W-phase current) target values (target currents) are determined, and PWM signals for matching the currents (phase current values) detected by the phase current detector 12 with the target currents are output. The PWM signal of each phase output from the control circuit 9 is supplied to the gate terminals of the six power transistors included in the inverter 3.

  A control voltage (for example, 12V) serving as a power source for the control circuit 9 is supplied from a low-voltage battery (for example, 12V) 7, and an auxiliary battery is mounted as the low-voltage battery 7. Alternatively, the low voltage battery 7 may be charged from the high voltage battery 6 via a DC / DC converter or the like.

  Next, FIG. 3 is a diagram showing a schematic circuit configuration of the magnetic detection element 10 and the inverter 3 according to the embodiment of the present invention. Here, as shown in FIG. 3, the DC voltage between the positive electrode (power supply side) P and the negative electrode (ground side) N is non-boosted (no boost converter 19 is provided).

  In FIG. 3, the electric motor 8 is a three-phase brushless motor having three-phase windings (a U-phase winding 8u, a V-phase winding 8v, and a W-phase winding 8w).

  Inverter 3 includes six power transistors Q1, Q2, Q3, Q4, Q5, and Q6 as switching elements. Three circuits (arms) formed by connecting two of these six MOSFETs in series are provided in parallel between the power supply line P1 and the ground line P2. Each connection point of power transistors Q1, Q2, Q3, Q4, Q5, and Q6 is directly connected to one end of U-phase winding 8u, V-phase winding 8v, and W-phase winding 8w. The other ends of the three-phase windings 8u, 8v, 8w of the electric motor 8 are connected to a common connection point (neutral point).

  A high voltage battery 6 (see FIG. 2) is connected to the input side of the inverter 3 via a power relay 14 and a smoothing capacitor 15 of the power circuit 2. Here, the connection part of the positive electrode P and the negative electrode N of the power supply circuit 2 to the high voltage battery 6 is formed by two bus bars 11 for the positive electrode P and the negative electrode N, for example. Both bus bars 11 are arranged in parallel to each other, and normally, currents of the same magnitude (indicated by broken arrows) flow in opposite directions.

  The magnetic detection element 10 is a magnetoelectric conversion element using a magnetoresistive effect, and is disposed at an intermediate position between the two bus bars 11. That is, the distances L1 and L2 between the magnetic detection element 10 and the bus bar 11 are set to be equal distances (L1 = L2), and the magnetic fluxes passing through the magnetic detection element 10 are added together to maximize the magnetic flux density (for one pole). Twice the magnetic flux density). In addition, when arrange | positioning on the intermediate line shown with a dashed-dotted line, the magnetic force to generate | occur | produce will become the same magnitude | size at the time of normal.

  In addition, two current detectors 12 are used for phase current detection (in normal motor drive control, current detection is performed for two phases), and one current detector 13 is provided on the negative electrode N side for power supply current detection. Is provided.

  Next, FIG. 4A is a circuit diagram showing the output of the magnetic detection element 10, and FIG. 4B is a diagram showing the relationship between the magnetic flux density and the resistance change rate of the magnetic detection element 10. As shown in FIG. 4A, the magnetic detection element 10 is connected between a DC voltage (for example, 5V) Vc−ground (0V), and the change in resistance value is changed as the change in the voltage Vout through the amplifier circuit 20. It is taken out and input to a CPU (not shown) in the control circuit 9 for processing. Here, as shown in FIG. 4B, the change in the resistance value of the magnetic detection element 10 changes (increases / decreases) in a non-linear manner at a low magnetic field with respect to the magnetic flux density. When the ground fault occurs (B), the resistance change rate decreases as the magnetic flux density decreases when the magnetic flux density and resistance change rate are normal (A).

Next, a specific example of the magnetic detection element 10 mounted on a substrate will be described.
FIG. 5A is a diagram showing the relationship between the magnetic flux generated by the bus bar 11 at normal time and the magnetic detection element 10, and FIG. 5B is the magnetic flux generated by the bus bar 11 when a ground fault occurs and the magnetic detection element. FIG. As shown in FIGS. 5A and 5B, the direction of the current flowing through the positive electrode P (power supply line P1) and the negative electrode N (ground line P2) is opposite. Magnetic fluxes generated from the respective bus bars 11 at normal times (indicated by a one-dot chain line and a two-dot chain line) are formed by magnetic lines of force having the same magnitude and opposite directions. On the other hand, a magnetic flux (indicated by a two-dot chain line) generated from the negative electrode N side bus bar 11 when a ground fault occurs is generated from the positive electrode P side bus bar 11 because the power supply current flowing through the negative electrode N side decreases due to a ground fault (leakage). And the total amount of magnetic flux that passes through the magnetic detection element 10 is reduced. For this reason, the magnetic flux density is reduced, and the resistance change rate of the magnetic detection element 10 is reduced and output.

  Next, the operation and effect of the vehicle-mounted motor control device 1 according to the present embodiment configured as described above will be described.

  According to the above configuration, the distances L1 and L2 between the magnetic detection element 10 and the bus bar 11 are equidistant at the intermediate position of the bus bar 11 electrically connected to both the positive electrode P and the negative electrode N of the high-voltage battery 6 ( The magnetic detection element 10 is arranged at a position of L1 = L2). Magnetic fluxes generated by currents flowing in the opposite directions of the positive and negative electrode bus bars 11 passing through the magnetic detection element 10 are added together, and the magnetic flux density is maximized in a normal state (twice the magnetic flux density of one pole). Here, since a magnetoelectric conversion element that detects a change in resistance value using the magnetoresistive effect is attached as the magnetic detection element 10, the magnetic detection element 10 flows through the bus bar 11 (or ground fault line P <b> 2) on the negative electrode N side of the power supply circuit 2. When the current is smaller than the current flowing through the bus bar 11 (or power supply line P1) on the positive electrode P side, the magnetic flux density of the magnetic flux passing through the magnetic detection element 10 is reduced, and the output of the resistance change rate of the magnetic detection element 10 is reduced. Arise. When the magnetic flux density is high, the output of the resistance change rate is large, and when the magnetic field is low and the magnetic flux density is low, the output of the resistance change rate is very small. Further, similarly to the insulation type current detector, it is possible to detect a current value flowing through the wiring of the inverter 3 and the electric motor 8 in a non-contact and insulated state.

  As a result, the power transistor (switching element, eg, IGBT, MOSFET, etc.) of the inverter 3 Q1, Q2, Q3, Q4, Q5, Q6, a short circuit or a ground fault, or the output part of the inverter 3 and the electric motor It is possible to detect a leakage due to a ground fault in the wiring of the motor 8 and the windings 8u, 8v, and 8w. For this reason, when a ground leakage occurs, the current flowing through the negative electrode N side of the power supply circuit 2 decreases and the current becomes unbalanced. Therefore, the power supply relay 14 is cut off when the ground fault is detected, thereby supplying power to the inverter 3. Can be stopped and the inverter 3 can be protected.

  As a result, it is possible to reduce expensive insulation-type current detectors for ground fault detection and peripheral circuits added for three-phase current detection, and suppress increase in size and cost of the motor control device 1. It becomes possible to do. In addition, since the load of CPU current calculation for detecting leakage can be reduced, the efficiency and reliability of the motor control device 1 and the entire system can be improved.

  As described above, according to the embodiment of the present invention, it is possible to provide a vehicle-mounted motor control device that can detect a ground fault of an inverter and an electric motor using a magnetic detection element, and can be reduced in size and cost.

  As mentioned above, although embodiment which concerns on this invention was described, this invention can also be implemented with another form.

  In the above embodiment, the example in which the magnetic detection element 10 is used for ground fault detection of the inverter 3 and the electric motor 8 has been described. However, the present invention is not limited to this, and the power source current detector 13 and the motor that detect the overcurrent of the power source circuit 2 are described. It can also be used as a substitute for the phase current detector 12 for detecting the phase current.

  In the above embodiment, the case where the magnetic detection element 10 is used for ground fault detection has been described. However, the present invention is not limited to this, and the present invention can be used for other abnormality detection (for example, vehicle collision detection). Thereby, a small and inexpensive detector can be configured.

  In the above embodiment, the case where the two bus bars 11 for the positive and negative electrodes P and N are arranged in parallel and the current flows through the respective bus bars 11 in the reverse direction has been described. The bus bar 11 may be reversely arranged in terms of structure so that FIG. 6A is a diagram showing a schematic configuration of a magnetic detection element 10 and a bus bar 11 according to another embodiment of the present invention, and FIG. 6B is a diagram showing a ground fault occurrence according to another embodiment of the present invention. It is a figure which shows the relationship between the magnetic flux generated by the bus bar 11 at the time, and the magnetic detection element 10. As shown in FIG. 6A, the positive and negative bipolar bus bars 11 are arranged so that currents (shown by broken arrows) flow in the same direction, and the magnetic detection element 10 is on the middle line of the two bus bars 11 indicated by the one-dot chain line. Placed in.

  As a result, since currents of the same magnitude flow in the same direction on the positive electrode P side and the negative electrode N side in the normal state, magnetic fluxes generated from the respective bus bars 11 are formed by magnetic lines of force having the same magnitude and the same direction. As a result, the magnetic fluxes passing through the magnetic detection element 10 cancel each other, and the magnetic flux density is minimized (near 0). On the other hand, as shown in FIG. 6B, the magnetic flux generated from the bus bar 11 on the negative electrode N side when a ground fault occurs reduces the current flowing in the same direction on the negative electrode N side due to the ground fault. 11 and less than the magnetic flux generated in the same direction. For this reason, the total amount of magnetic flux passing through the magnetic detection element 10 increases. As a result, with respect to the normal magnetic flux density and resistance change rate, the resistance change rate of the magnetic detection element 10 is increased as the magnetic flux density increases when a ground fault occurs, contrary to the relationship shown in FIG. Increased output.

  In the said embodiment, although the example was shown about the case where a ground fault detection is carried out by the magnetic detection element 10 using the bus bar 11 arrange | positioned in parallel, not only this but another wiring member (for example, electric wire etc.) is used. You may comprise.

  In the above embodiment, the example in which the magnetic detection element 10 is used in the inverter 3 for the rear wheel drive unit 18 of the vehicle is shown. However, the present invention is not limited to this, for example, an inverter such as an electric power steering device or an electric brake device, or It may be used for other in-vehicle power converters.

1: Motor control unit (ECU) 2: Power supply circuit 3: Inverter 4: Reducer
5: clutch, 6: high voltage battery (DC power supply), 7: low voltage battery, 8: electric motor,
8u, 8v, 8w: motor winding, 9: control circuit, 10: magnetic detection element, 11: bus bar, 12: phase current detector, 13: power supply current detector, 14: power supply relay, 15: smoothing capacitor, 16 : Vehicle control unit, 17: rear wheel, 18: rear wheel drive unit,
19: Boost converter (converter unit), 20: Amplifier circuit,
Q1, Q2, Q3, Q4, Q5, Q6: power transistors (switching elements),
P: positive electrode, N: negative electrode, P1: power supply line, P2: ground line, Vc: control voltage,
Vout: magnetic detection element output voltage, L1, L2: distance between magnetic detection element and bus bar

Claims (3)

A motor drive circuit including a plurality of switching elements and supplying a drive current to the electric motor;
A power supply circuit connected to a DC power supply for driving the electric motor and supplying power to the motor drive circuit;
A control circuit for controlling the motor drive circuit,
The power supply circuit is
A power relay that opens and closes a connection between the DC power source and the motor drive circuit;
A converter for supplying power to the motor drive circuit;
A smoothing capacitor for absorbing current ripple;
A plurality of bus bars that are electrically connected to the electrodes of the DC power source and serve as a power supply circuit;
A magnetic detection element for detecting a magnetic component in a predetermined direction,
The magnetic detection element is
Between the positive and negative bus bars arranged in parallel, the distances between the magnetic detection elements and the bus bars are equal to each other, and the resistance change rate of the magnetic detection elements is reduced and output. vehicle motor control apparatus characterized that you detect the ground fault occurs Rutoki. In the vehicle-mounted motor control device according to claim 1,
When the resistance change rate of the magnetic detection element decreases and is output , the power supply relay is cut off and the power supply to the motor drive circuit is stopped. The in-vehicle motor control device according to claim 1 or 2,
The on-vehicle motor control device, wherein the magnetic detection element is a magnetoelectric conversion element that detects a power supply current of the power supply circuit using a magnetoresistive effect.

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