JP2015167448A - Motor device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor device for vehicle in which an inverter for driving an induction motor used for rear wheel driving can be reduced in capacity and size, while reducing the cost, in a vehicle capable of four-wheel drive.SOLUTION: A motor device 1 for vehicle is mounted on a vehicle and used as a drive source of a rear wheel driver generating a driving force, and includes an induction motor 8 of three-phase winding, a battery 2, and an ECU 13. The ECU 13 includes an inverter 3 and a control circuit 6, the inverter 3 is connected with the rotor winding of the induction motor 8, and rotary driving the induction motor 8 by generating an AC voltage from th DC power of the battery 2. The control circuit 6 detects the rotational speed of the induction motor 8, and gives the output frequency of the inverter 3 by adding a slip frequency to the rotational frequency. Three-phase primary power is supplied from a generator 15 to the stator winding of the induction motor 8, and three-phase secondary power is supplied from the inverter 3 to the rotor winding. By this double feeding, rotational speed control of the induction motor 8 can be carried out.

Description

  The present invention relates to a vehicle motor device, and more particularly to a motor device mounted on a vehicle with an induction motor that drives a rear wheel.

  In recent years, hybrid vehicles, electric vehicles, and the like that travel with driving force from an electric motor have been attracting attention and put into practical use as environmentally friendly vehicles. For example, in addition to a conventional gasoline engine, a hybrid vehicle is a vehicle that uses a direct current power source (hereinafter referred to as a battery), an inverter, and an electric motor driven by the inverter as power sources. That is, a power source is obtained by driving a gasoline engine, a DC voltage from a DC power source is converted into an AC voltage by an inverter, and a power source is further obtained by rotating the electric motor by the converted AC voltage. It is.

  On the other hand, vehicles capable of four-wheel drive using hybrid vehicle technology have also been proposed. In such an electric four-wheel drive vehicle, an electric motor is disposed in the power system of the rear wheel, and an output shaft coupled to the rotor of the electric motor includes a rear wheel via a differential gear (reduction gear). It is connected to the rear axle. The stator of the electric motor is fixed to the vehicle body case. The electric motor is configured as a motor generator (synchronous motor generator), and is electrically connected to the battery via a drive circuit (an inverter in the case of an AC motor) (see, for example, Patent Document 1). In addition, a front and rear wheel drive vehicle is disclosed in which an induction motor is mounted as a rear wheel drive means to drive a rear wheel (see, for example, Patent Document 2). This induction motor is connected to an inverter as input means for converting a direct current supplied from a battery as a power source into an alternating current.

JP 11-299007 A JP-A-3-159502

  For example, the above-described electric four-wheel drive vehicle is an automobile provided with an electric motor for driving rear wheels with a relatively large output (for example, several tens of kW) such as use when traveling on a slope. For this reason, the motor drive circuit provided with the large capacity | capacitance driver according to the output of the electric motor as an inverter is needed. However, when the capacity of the driver increases, the size of the inverter increases, which increases the mounting space and requires the installation of a cooling device, which may increase the cost.

  The present invention has been made in order to solve the above-mentioned problems, and its object is to reduce the size and size of an inverter for driving an induction motor used for rear wheel drive in a vehicle capable of four-wheel drive. An object of the present invention is to provide a vehicle motor device capable of reducing costs.

  In order to solve the above-mentioned problems, an invention according to claim 1 is directed to an electric motor mounted on a vehicle for driving a rear wheel in a vehicle motor device, and a primary electric power connected to an engine connected to an engine. Including a generator, a high-voltage DC power source for driving the electric motor, and a plurality of switching elements connected to the DC power source, and supplying secondary power to the rotor of the electric motor based on a command value And a control circuit for controlling the inverter, wherein the electric motor is composed of a three-phase winding type induction motor having a winding on the rotor.

  According to the above configuration, primary power is supplied from the generator connected to the engine to the stator winding of the three-phase winding type induction motor, and 2 is supplied from the DC power source to the rotor winding of the induction motor via the inverter. When the induction motor is rotationally driven by supplying the next power, it can be operated as a normal synchronous motor that apparently rotates at a synchronous speed with the rotating shaft coupled to the rotor. As a result, the rotational speed can be controlled using an induction motor as an electric motor for driving the rear wheels. In addition, since the secondary power flow becomes reversible by performing double feeding (super synchronous Serbius method) using an inverter, the regenerative operation of the induction motor can be easily performed, leading to improvement in energy efficiency.

  According to a second aspect of the present invention, in the vehicular motor device according to the first aspect, the electric motor has a rotation speed by changing a frequency of the secondary power supplied from the inverter to the rotor. The gist is to be controlled.

  According to the above configuration, in the winding induction motor driven by the double feed, since the variable frequency power is applied from the inverter to the rotor winding, the rotation speed is controlled by changing the slip frequency of the inverter. can do. As a result, the rotational speed can be controlled using the induction motor as the electric motor for driving the rear wheels.

  According to a third aspect of the present invention, in the vehicle motor device according to the first or second aspect, the inverter has a capacity formed by a product of a rated output of the electric motor and a predetermined slip. This is the gist.

  According to the above configuration, the secondary power for controlling the rotational speed of the induction motor only needs to supply a capacity that is represented by the product of the motor rated output and the slip, so that the capacity of the driver provided in the inverter is reduced. can do. This makes it possible to reduce the size of the inverter, reduce the mounting space, and eliminate the need for a cooling device, thereby reducing costs.

  According to the present invention, in a vehicle capable of four-wheel drive, it is possible to provide a vehicle motor device that can reduce the capacity and reduce the cost of an inverter that drives an induction motor used for rear wheel drive.

1 is a block diagram showing a schematic configuration of an electric four-wheel drive vehicle equipped with a vehicle motor device according to an embodiment of the present invention. The figure explaining schematic structure of the drive circuit of the motor apparatus for vehicles of FIG. The figure which shows the flow of the electric power in the drive and braking operation | movement of an electric motor. The figure for demonstrating the rotational speed control of an electric motor.

Embodiments of the present invention will be specifically described below with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of an electric four-wheel drive vehicle equipped with a vehicle motor device 1 according to an embodiment of the present invention.

  As shown in FIG. 1, this vehicle is equipped with a gasoline engine (hereinafter referred to as an engine) 15 as a driving source for traveling, and a transmission 14 as a front wheel transmission is connected to the output shaft of the engine 15. ing. An engine 15 and a generator 16 as a generator are connected by a transmission 14, and an output shaft of the transmission 14 is connected to a front wheel 17. Further, as a rear wheel drive system for an electric four-wheel drive vehicle (electric 4WD), a rear wheel drive for driving and controlling a rear wheel drive device 12 and a rear wheel drive induction motor (electric motor) 8 in the rear wheel drive device 12. Control device (hereinafter referred to as ECU) 13. Here, the generator 16, the rectifier 19, the battery (DC power supply) 2, the ECU 13, and the induction motor 8 constitute the vehicle motor device 1.

  The driving force of the engine 15 is transmitted to the front wheels 17 via the transmission 14 and drives the front wheels 17. The output of the engine 15 is controlled by a command from an engine ECU (not shown), and not only drives the front wheels 17 but also drives the generator 16. When regenerative braking is performed by the front wheels 17, regenerative power obtained by the generator 16 is supplied to the battery 2 via the rectifier 19 and charged. The rectifier 19 is an AC / DC converter that converts AC power into DC power. When generating power, the generator 16 uses the power of the engine 15 to output AC power as a generator. Further, the generator 16 supplies three-phase driving power to the stator winding on the primary side of the induction motor 8 for driving the rear wheels.

  The rear wheel drive device 12 includes an induction motor 8, a reduction gear (hereinafter referred to as a differential gear) 4, and a clutch 5, and the clutch 5 is installed at the final stage of the differential gear 4. As the induction motor 8 for the drive source, for example, a three-phase winding induction motor is used. A wound induction motor is an induction motor in which a three-phase wire-wound rotor is connected to an external circuit (for example, an inverter or a secondary resistor) via a slip ring and a brush.

  The driving force of the induction motor 8 is transmitted to the rear wheel 7 via the differential gear 4 and the clutch 5 to drive the rear wheel 7. When the clutch 5 is connected, the rear wheel 7 is driven by the rotational force of the induction motor 8. When the clutch 5 is released, the induction motor 8 is mechanically disconnected from the rear wheel 7, and the rear wheel 7 does not transmit driving force to the road surface.

  The battery 2 is a high-voltage (for example, 100 V or higher, 250 V, etc.) DC power source, and is composed of, for example, a secondary battery such as chargeable / dischargeable nickel hydride or lithium ion. The battery 2 supplies DC power to the ECU 13 and is charged by DC power from the ECU 13.

  The ECU 13 includes a control circuit 6 and an inverter 3, and is connected to the rear wheel drive device 12. The control circuit 6 is connected to an auxiliary power source (not shown) having a low voltage (for example, 12 V) and receives a command from the vehicle control unit 18 that controls driving of the vehicle, and controls the rear wheel driving device 12 and the like. A relay (not shown) is provided between the inverter 3 and the battery 2, and the high voltage is cut off when the vehicle is not in operation.

  The inverter 3 is provided so that the required power can be controlled arbitrarily in the induction motor 8 based on a command from the control circuit 6. In the present embodiment, the inverter 3 functions as a variable frequency power source, converts the DC power stored in the battery 2 into three-phase AC power, and supplies it to the rotor winding on the secondary side of the induction motor 8. At the time of braking of the vehicle, the induction motor 8 is regenerated by the regenerative torque from the rear wheel 7, and regenerative power can be obtained.

  Further, the vehicle control unit 18 is connected to an engine ECU (not shown) and a communication means such as a control circuit 6 and CAN, and controls the entire drive system such as calculation of a command value to the induction motor 8 for driving the rear wheels. It is a controller to perform. Based on the engine speed and torque command obtained from the vehicle control unit 18, the control circuit 6 controls the inverter 3 and the induction motor 8.

Next, FIG. 2 is a diagram illustrating a schematic configuration of a drive circuit of the vehicle motor device 1 of FIG.
The vehicle motor device 1 is used as a drive source such as a rear wheel drive device 12 that is mounted on the electric four-wheel drive vehicle shown in FIG. As shown in FIG. 2, the vehicle motor apparatus 1 includes a three-phase winding type induction motor 8, a battery 2, and an ECU 13 as a drive circuit. The ECU 13 includes an inverter 3 and a control circuit 6 and is connected between the battery 2 and the induction motor 8 and supplies AC power as a secondary power source to the rotor winding. A generator 16 is connected to the stator winding of the induction motor 8 and supplies AC power as a primary power source of the induction motor 8.

  The inverter 3 generates an AC voltage from the DC power of the battery 2 and is connected to the rotor winding of the induction motor 8 to rotate the induction motor 8. The inverter 3 includes a plurality (six in this embodiment) of switching elements (eg, MOSFET, IGBT, etc.) U1, U2, V1, V2, W1, and W2. In the present embodiment, each of the switching elements U1 to W2 is an N-channel type MOSFET and incorporates a PN junction diode. The anode of the built-in diode is electrically connected to the source of the corresponding switching element, and the cathode is electrically connected to the drain of the corresponding switching element.

  Three DC circuits (hereinafter referred to as arms) formed by connecting two of these six switching elements U1 to W2 of the inverter 3 in series are provided in parallel between the power line and the ground line of the DC bus. It has been. The connection points U, V, and W of the arm switching elements U1 to W2 (for example, the connection points of the switching elements U1 and U2 corresponding to the U phase) are the rotor windings (U phase winding, It is directly connected to one end of a V-phase winding, a W-phase winding (not shown). The other ends of the three-phase rotor windings are connected to a common connection point (neutral point, not shown).

The control circuit 6 detects the rotation speed (rotation angular frequency fm) of the induction motor 8 and performs control so that the induction motor 8 becomes the target rotation speed (target rotation angular frequency fm ^* ). That is, control is performed so that the output frequency (= slip frequency) fs of the inverter 3 becomes fs = fg−fm ^* . Here, fg is the frequency of the AC power supplied from the generator 16 to the induction motor 8 as the primary power. For example, the control circuit 6 can obtain the rotation speed via a speed detector (for example, a rotation angle sensor) attached to the rotation shaft 11 (see FIG. 3) of the induction motor 8. A calculation is performed based on these data to generate a PWM duty control signal (hereinafter referred to as a PWM signal), the inverter 3 is operated to supply secondary power to the induction motor 8, and the induction motor 8 is rotationally driven. . The PWM signal of each phase output from the control circuit 6 is connected to the gate terminals of the six switching elements U1 to W2 included in the inverter 3, respectively.

  According to the above configuration, the three-phase primary power is supplied from the generator 16 to the stator winding of the induction motor 8, and the three-phase secondary power is supplied from the inverter 3 to the rotor winding. Therefore, the winding induction motor 8 can be rotationally driven by applying this double feeding (super synchronous Serbius method).

Next, FIG. 3 is a diagram illustrating a flow of electric power in driving and braking operations of the induction motor 8.
As shown in FIG. 3, the three-phase AC power output from the generator 16 (see FIG. 2) is supplied as primary power Ps to the stator winding of the induction motor 8. When the mechanical output of the induction motor 8 is Pm, the secondary power supplied from the inverter 3 to the rotor winding is Pr, and the slip is S (= (synchronous speed−rotating shaft speed) / synchronous speed), The magnitude is expressed by the relationship of Ps = Pm / (1-S), Pr = SPs. During the power running operation by the motor drive, the flow of the secondary power Pr is in the direction indicated by a in the figure, and the power is supplied to the rotor winding. During the regenerative operation by motor braking, the flow of the secondary power Pr is in the direction indicated by b in the figure, and the electric power is supplied from the rotor winding to the battery 2 via the inverter 3 and charged.

Next, FIG. 4 is a diagram for explaining the rotational speed control of the induction motor 8.
As shown in FIG. 4, the AC voltage V1 corresponding to the primary power supply frequency (fg) is supplied to the three-phase stator winding of the induction motor 8, and the AC voltage V2 having the slip frequency fs is supplied to the three-phase rotor winding. Is supplied. Here, when the rotational speed of the rotating magnetic field of the stator winding is N1, the rotational speed of the rotating magnetic field of the rotor winding is N2, and the rotational speed of the rotating shaft 11 is Nr, the magnitude of each rotating speed is N1 = It is represented by the relationship of Nr + N2.

The rotational speed N2 of the rotating magnetic field in the rotor winding is added to the rotational speed Nr of the rotating shaft 11, and the rotating shaft 11 is rotating at a speed (apparently synchronous speed) N1 corresponding to the primary power supply frequency. . That is, the rotating shaft 11 coupled to the rotor 10 is variable in speed, but when viewed from the stator 9 side, it becomes a normal variable speed synchronous motor that is controlled to rotate at the synchronous speed N1 (for example, N1 = 1000min ^-1, when the Nr = 900 min ^-1, the N2 = 100 min ^-1 generated by the rotating magnetic field of the rotor winding).

  As described above, the rotational speed of the rotating shaft 11 in the high speed region can be controlled by connecting the inverter 3 having a relatively small capacity to the rotor winding of the induction motor 8 and supplying the secondary power of the variable frequency. become. In this case, the secondary power supplied from the inverter 3 to the rotor windings necessary for the rotational speed control may be about the rated output capacity of the induction motor 8 × the predetermined slip (normally, the slip is about several percent). ). For this reason, for example, when the maximum slip is set to 0.1 (10%), the inverter capacity can be suppressed to about 1/10 of the rated output capacity of the induction motor 8.

  Next, operations and effects of the vehicle motor device 1 according to the embodiment of the present invention configured as described above will be described.

  According to the above embodiment, primary power is supplied from the generator 16 connected to the engine 15 to the three-phase stator winding of the induction motor 8, and the three-phase of the induction motor 8 is supplied from the battery 2 via the inverter 3. When the induction motor 8 is rotationally driven by supplying secondary power to the rotor winding, it can be operated as a normal synchronous motor that apparently rotates at the synchronous speed of the rotating shaft 11 coupled to the rotor 10.

  In addition, in the induction motor 8 driven by double power feeding (supersynchronous Serbius method), since the variable power secondary power is applied from the inverter 3 to the rotor winding, the frequency of the rotating shaft 11 can be changed by changing the frequency. The rotation speed can be controlled. Further, since the secondary power for controlling the rotational speed of the induction motor 8 may be supplied to the inverter 3 with a capacity represented by the product of the rated output of the induction motor and the slip, the capacity of the driver provided in the inverter 3 Can be reduced.

  As a result, the rotational speed can be controlled using the induction motor 8 as an electric motor for driving the rear wheels. As a result, the inverter 3 can be downsized and no cooling device is required, so that it is possible to reduce the mounting space and cost. Moreover, since the flow of secondary power becomes reversible by performing double feeding using the inverter 3, the regenerative operation of the induction motor 8 can be easily performed, leading to improvement in energy efficiency.

  As described above, according to the embodiment of the present invention, in a vehicle capable of four-wheel drive, the capacity of an inverter that drives an induction motor used for rear wheel drive can be reduced, and the vehicle motor device can be reduced in size and cost. Can provide.

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

  In the above-described embodiment, the case where double power feeding (supersynchronous Serbius method) is performed using the inverter 3 has been described. An apparatus (for example, a cycloconverter) may be used.

  In the above-described embodiment, the case of driving only at the rotational speed in the high speed region below the synchronous speed (slip S> 0) has been described. Since the flow is reversible, rotation control at a rotation speed equal to or higher than the synchronization speed (S <0) is also possible.

  In the above embodiment, the electric four-wheel drive vehicle including the engine 15 as the front wheel drive source and the induction motor 8 as the rear wheel drive source has been described. However, the present invention is not limited to this, and has other configurations. You may use for vehicles. For example, the present invention can be applied to a hybrid vehicle that travels by driving an electric motor (for example, a series / parallel hybrid system).

  In this hybrid vehicle, the driving force of the engine and the motor generator, which is a motor generator, is transmitted to the front wheels via the transmission to drive the front wheels. The engine output is controlled by a command from the engine ECU, and not only the front wheels are driven, but also the motor generator may be driven. When the motor generator functions as a generator or functions as a motor according to the running state of the vehicle to drive the front wheels, the motor generator uses the electric power stored in the battery to drive the motor through the inverter. To drive. When regenerative braking is performed by the front wheels, regenerative power obtained by the motor generator is supplied to the battery via the inverter and charged.

  In the above embodiment, the battery 2 has been described as a high-voltage DC power supply, but the present invention is not limited to this. Also good.

  In the above embodiment, the case where the vehicle motor device 1 provided with the winding induction motor 8 is used for the rear wheel drive device 12 mounted on the electric four-wheel drive vehicle has been described. However, the present invention is not limited to this. The present invention can also be applied to motor devices such as transportation equipment that uses a three-phase wound induction motor and other various industrial machines.

1: vehicle motor device, 2: battery (DC power supply), 3: inverter,
4: differential gear, 5: clutch, 6: control circuit, 7: rear wheel,
8: Winding type induction motor (electric motor), 9: stator, 10: rotor, 11: rotating shaft,
12: Rear wheel drive device, 13: ECU, 14: Transmission, 15: Engine,
16: Generator (generator), 17: Front wheel, 18: Vehicle control unit,
19: Rectifier
S: slip, Ps: primary power, Pr: secondary power, Pm: motor mechanical output,
V1: primary side voltage, V2: secondary side voltage, fs: slip frequency, fm: rotation angle frequency,
fm ^* : target rotation angular frequency, fg: induction motor primary side power supply frequency,
N1: Synchronous speed (rotating magnetic field speed of the stator winding), N2: Rotating magnetic field speed of the rotor winding,
Nr: Rotating shaft speed

Claims (3)

An electric motor mounted on the vehicle for driving the rear wheels;
A generator connected to the engine for supplying primary power to the stator of the electric motor;
A high voltage DC power source for driving the electric motor;
An inverter connected to the DC power supply, including a plurality of switching elements, and supplying secondary power to the rotor of the electric motor based on a command value;
A control circuit for controlling the inverter,
The electric motor comprises a three-phase winding type induction motor having a winding on the rotor. The vehicle motor device according to claim 1,
The vehicle motor apparatus according to claim 1, wherein the electric motor has a rotation speed controlled by changing a frequency of the secondary power supplied from the inverter to the rotor. In the vehicle motor device according to claim 1 or 2,
The vehicle motor device according to claim 1, wherein the inverter has a capacity formed by a product of a rated output of the electric motor and a predetermined slip.

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