JP5155576B2 - Electric vehicle drive - Google Patents

Description

  The present invention relates to an electric vehicle drive device using an electric motor as a drive source.

Conventionally, there is an electric motorcycle using an electric motor as a drive device as an electric vehicle. As the drive device, for example, a continuously variable transmission is provided between the motor and the wheels (reduction gear + drive wheel), pulleys are provided on the output shaft of the motor and the input shaft of the reduction device, and a V belt is provided between both pulleys. (For example, see Patent Document 1).
Japanese Patent Laid-Open No. 5-221374

  In the drive device having the above-described structure, since the transmission is provided, the motor output can be transmitted from the low rotation / high torque to the wheel as the high rotation / low torque. However, in the case of using a V-belt as described above, the transmission efficiency is extremely poor, and there is a problem that the output is reduced and the power consumption becomes excessive to be adopted in an electric vehicle using an electric motor as a drive source instead of an internal combustion engine. was there. Therefore, in an electric vehicle (especially an electric motorcycle), the transmission efficiency can be prevented from deteriorating as a one-speed fixed type without a transmission that takes advantage of the motor characteristics that increase the torque as the speed decreases. Because there is no machine, the speed range suitable for operation is biased to the low speed side or the high speed side from the viewpoint of the motor characteristics, so that the speed range where the electric motor can be used efficiently is narrower than when using a transmission. There is. There is also a problem that a larger electric motor must be used to compensate for this.

In order to solve such a problem and achieve a wide range of speed adjustment without providing a speed change mechanism and achieve high efficiency, in the present invention, the electric motor and the driving force of the electric motor are combined. Driving force transmission means for transmitting to the drive wheels at a fixed gear ratio, wherein the electric motor is a stator, a rotor provided coaxially and rotatably with respect to the stator, and a magnetic flux of the stator and the rotor passes. Moving means for allowing either one of the stator and the rotor to move in the axial direction of the rotor in order to make the opposing area of the surface variable, and the stator is provided with a coil winding, and the coil winding is A variable field motor having a permanent magnet disposed on the rotor facing the stator core, a drive current supply circuit for supplying a drive current to the coil winding, and the drive current Control means for outputting a pulse width modulated control signal serving as a reference for the supply to the supply circuit, and the control means performs pulse width modulation control based on a target current corresponding to an operation signal for the electric motor. A duty signal determining means for determining a duty ratio of the signal; and a pulse width modulation signal generating means for supplying a control signal, which is pulse width modulated based on the duty signal by the duty determining means, to the drive current supply circuit. , said duty ratio reaches a preset duty limit value, when said by the moving means performs control to reduce the facing area of the stator and the rotor as to prohibit the control of the duty signal determining means did.

  In particular, the driving force transmission means may be a chain, a gear or a belt.

  As described above, according to the present invention, since the electric motor and the driving wheel are connected via the driving force transmission means having a fixed gear ratio, the driving force transmission system has a transmission portion such as a conventional continuously variable transmission. So that high transmission efficiency can be ensured, and when the duty ratio when performing duty control reaches a preset duty limit value, the opposed area of the stator and the rotor is reduced to reduce the effective magnetic flux. Since the field weakening control is performed, a larger amount of current can flow even when the duty ratio remains at the duty limit value, and the motor characteristics can be made high-speed. Accordingly, variable speed performance equivalent to that of a drive device using the speed change mechanism can be achieved without providing any speed change mechanism, and efficiency deterioration due to the speed change mechanism can be prevented.

  In particular, since the driving force transmission means is a chain, a gear, or a belt, a fixed transmission ratio can be obtained with a simple structure, and mechanical efficiency is hardly deteriorated due to the simple structure.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. For example, as shown in FIG. 1, the present driving device can be applied as a driving device for an electric motorcycle. The drive device according to the present invention is not limited to a motorcycle, and can be applied as a drive device for an automobile including four wheels.

  In the motorcycle shown in the figure, a vehicle body frame 1, a front wheel WF serving as a steering wheel and a rear wheel WR serving as a driving wheel before and after the traveling direction of the body frame 1, and a drive device for driving the rear wheel WR 2 and the drive device 2 is based on the electric drive device constructed according to the present invention.

  Next, the drive device 2 will be described with reference to FIG. In the present drive device 2, main structural mechanisms are housed in a casing 3 formed in a box shape that is long in the longitudinal direction of the vehicle body. An axle 4 is rotatably supported at a rear portion of the vehicle body of the casing 3 through both bearings that extend in the longitudinal direction of the casing 3 and are provided on both side walls facing each other. A rear wheel WR having a hub fixed to a portion protruding outward of 3 is coaxially supported.

  An electric motor M as a drive source is provided at the front portion of the casing 3 in the vehicle body. The electric motor M in the illustrated example is an outer rotor type, but is not limited to the outer rotor type. As shown in the figure, there is provided a fixed support shaft 5 that is spanned and fixed between the opposite side walls of the casing 3, and a rotor 6 is coaxially provided on the fixed support shaft 5. The rotor 6 integrally includes a cylindrical boss rotatably supported on a fixed support shaft 5 via a pair of bearings and a flat bottomed cylindrical portion having an outer peripheral wall that coaxially surrounds the cylindrical boss. It is formed in the shape to have.

  A plurality of magnets (permanent magnets) 7 having N and S poles arranged in the circumferential direction are arranged on the inner peripheral surface of the outer peripheral wall of the bottomed cylindrical portion of the rotor 6. Further, in the space surrounded by the boss-like portion of the rotor 6 and the bottomed cylindrical portion, the side opposite to the bottom of the bottomed cylindrical portion is open, and the stator 8 is provided in the space. Yes.

  A guide member 9 adapted to protrude into the space of the rotor 6 is fixed to a portion of the casing 3 corresponding to the open surface of the rotor 6 so as to be cantilevered. The guide member 9 supports a slide member 10 that is movable in the axial direction of the fixed support shaft 5 by, for example, serration. A stator 8 is provided on the outer peripheral surface of the slide member 10. The stator 8 has an annular portion formed of laminated steel plates, a core 8a having a plurality of teeth projecting radially outward from the annular portion, and a coil 11 as a coil winding wound around the teeth. As described above, the annular portion of the core 8a integrated with the slide member 10 is screwed in place. The stator 8 thus configured and the rotor 6 constitute a portion that becomes a motor M to which the present invention is applied.

  The slide member 10 is driven to reciprocate in the axial direction of the fixed support shaft 5 by a motor rotation type electric actuator 12, and the integral stator 8 also reciprocates. In the illustrated example, the actuator 12 is fixed in a small casing 3 a provided integrally on the back side of the portion of the casing 3 that supports the fixed support shaft 5, and meshes with a large gear provided on the rotation shaft of the actuator 12. A drive shaft 13 having a small gear coaxially is pivotally supported by a pivotal support member fixed to the casing 3 so as to extend in the moving direction of the slide member 10. For example, a trapezoidal screw portion 13 a is provided on the slide member 10 side of the drive shaft 13, and a nut portion that engages with the trapezoidal screw portion 13 a is formed in the slide member 10. Thus, the moving means of the stator 8 is configured.

  The effective magnetic flux of the motor M can be adjusted by this moving means. That is, when the actuator 12 is driven to rotate, the drive shaft 13 rotates, and the slide member 10 screwed into the screw portion 13a moves in the axial direction of the drive shaft 13, so that the core 8a integral with the slide member 10 is provided. Can move in the axial direction of the fixed support shaft 5 which is parallel to the drive shaft 13. As a result, the area of the teeth protruding end surface of the core 8a facing the magnetic pole surface of the magnet 7 changes, and the magnetic flux between the magnet 7 and the core 8a increases or decreases, so that a variable field brushless motor is configured. In the drawing, the sensor unit for detecting the rotor position constituting the brushless motor is omitted.

  One end portion of the cylindrical boss of the rotor 6 protrudes from the bottomed cylindrical portion to the side opposite to the stator 8 side, and a drive gear 14a is integrally provided on the outer peripheral surface of the protruding portion. A driven gear 14b is fixed to a portion of the axle 4 in the casing 3, and a chain 15 is wound between the gears 14a and 14b. Therefore, in the illustrated example, the motor M and the rear wheel WR transmit and receive the rotational force via the chain 15, but as a rotational force transmission means between the motor M and the rear wheel WR, FIG. The chain 15 is not limited to the illustrated example, and a pulley and an endless belt may be used. Further, a gear train may be used.

  Next, the control procedure according to the present invention will be described with reference to the block circuit diagram of FIG. Note that the basic form of the motor M in the illustrated example may be the same as a three-phase brushless motor.

  In the illustrated example, each phase coil 11 of the motor M is connected to an in-vehicle battery BT as a power source via an inverter 21 as a drive current supply circuit in which a bridge circuit using an FET is configured. Note that a current detection sensor 22 is provided on the power supply line connecting the battery BT and the inverter 21, and a current detection signal detected thereby is input to the current detection circuit 25 of the control circuit ECU constituting the control means. It is supposed to be. The motor M is provided with a rotation angle sensor 24 that detects the rotation angle of the rotor 6 with respect to the stator 8, and the rotation angle signal is input to the rotation angle detection circuit 27, and the rotation angle detection circuit 27 rotates the rotation position of the rotor 6. And the rotation speed (rotation speed) is calculated. In this way, the rotation angle detection means is configured.

  Further, in the control circuit ECU, a driving operation input circuit 28 for inputting a driving operation signal which may be a signal from an external accelerator opening sensor (not shown), for example, and an output signal from the driving operation input circuit 28 are provided. Output current command circuit 29, a current comparison circuit 31 to which each output signal from output current command circuit 29 and current detection circuit 25 is input, and duty determination means to which an output signal from current comparison circuit 31 is input. The output duty determination circuit 33, the duty 100% determination circuit 36 as duty determination means to which the output signal from the output duty determination circuit 33 is input, and the pulse width modulated based on the output signal from the output duty determination circuit 33 and the duty ratio As a pulse width modulation signal generating means for outputting a PWM signal as a control signal corresponding to the output to the inverter 21 The position of the stator 8 is determined based on output signals from the WM signal generation circuit 38, the operation operation input circuit 28, the current comparison circuit 31, the duty 100% determination circuit 36, or an external stator position operation means (not shown). A stator position control circuit 39 to be determined, a position drive circuit 40 as movement control means for outputting a drive signal to the actuator 12 based on a stator position signal from the stator position control circuit 39, and a stator position signal from the stator position control circuit 39 The prohibition circuit 42 is provided as prohibition means for prohibiting the output of changing the duty ratio by the output duty determination circuit 33 based on the above.

  In the duty 100% determination circuit 36, if it is determined that the duty ratio by the output signal from the output duty determination circuit 33 has reached 100% as the duty limit value, the result is output to the stator position control circuit 39. . Further, the stator position control circuit 39 may set the priority order or combination of each input signal and output the stator position signal accordingly. Each circuit may include a circuit configured using an IC and a circuit configured by CPU program control. Further, detailed description of the parts understood by the illustrated circuit names and signal lines will be omitted.

  The stator position control circuit 39 calculates a set position (target position) of the stator 8 (core 8a), and a position control signal corresponding to the calculated position is output from the position drive circuit 40 to the actuator 12. 8a) is driven and stopped at the target position. As a result, as described above, the opposing area between the magnetic pole surface of the magnet 7 and the teeth projecting end face of the core 8a increases and decreases, and the effective magnetic flux passing through the opposing area increases and decreases. When it is increased, it can be a low-rotation / high-torque type.

  Next, the drive control procedure based on this invention is shown below with reference to FIG. Note that a known PWM is used in that an operation signal is output from the driving operation input circuit 28 to the output current command circuit 29 in accordance with the accelerator operation amount in the two-wheeled vehicle, and acceleration / deceleration control is performed by the duty ratio in accordance with the operation signal. It may be the same as the control, and detailed description thereof is omitted.

  When drive (acceleration) control is performed in the driving operation input circuit 28, the current value is read by the current detection sensor 22 in step ST1 of FIG. 4, and the target drive is performed by the current comparison circuit 31 in the next step ST2. The current (output value of the output current command circuit 29) is compared with the current drive current (output value of the current detection circuit 25), and if it is determined that the target value is larger than the current value, the process proceeds to step ST3. In step ST3, the duty determination circuit 36 determines whether or not the duty ratio (hereinafter referred to as DUTY) has reached a value MAX as a duty limit value. In the illustrated example, the first value MAX is set to 100%, but it is not necessarily 100% depending on the characteristics of the motor and the usage environment. Further, DUTY is a value determined by the output duty determination circuit 33, but as shown in the block diagram of FIG. 3, the output current command value set based on the operation amount is compared with the current detection value ( For example, it is determined according to the difference.

  If it is determined in step ST3 that DUTY has reached the duty limit value MAX, the process proceeds to step ST4. If the process proceeds to step ST4, the duty ratio is maximum (100%) and the drive current is to be increased. When the control for increasing the current due to the increase in the duty ratio reaches its peak, the current can be increased by reducing the effective magnetic flux. When the duty ratio is maximized, there is a case where the motor rotates at a high speed. With such a high speed rotation, it becomes impossible to flow a larger amount of current due to an increase in the counter electromotive force. However, by reducing the facing area between the stator 8 and the rotor 6 as shown in the example, that is, by reducing the effective magnetic flux, the back electromotive force is reduced, and more current can be passed. Note that the current increase / decrease control can be performed by advance angle control that changes the advance angle, but it is more efficient to insert and remove the core 8a. Thereby, higher speed rotation is possible.

  For this reason, control for removing the core 8a is performed in step ST4, but at the same time, for example, using the signal during the core movement control, the prohibition circuit 42 prohibits the duty control for the output duty determination circuit 33 and returns to step ST1. As described above, when the movement control of the core 8a is performed, the duty control is surely prohibited, thereby clarifying the control target, simplifying the control program, and effective driving control as described above. Can be provided at low cost. Further, when the duty limit value MAX is 100%, an operation region of 100% duty with a small switching loss is widened, and high-efficiency driving is possible.

  In addition, it expresses that the core 8a enters in the direction in which the core 8a is located as indicated by the solid line in FIG. 2, and for the direction in which the stator 8 is located as indicated by the two-dot chain line (only a part is shown). It is expressed that the core 8a is removed. The target position is the position of the core 8a set by the stator position control circuit 39. When the field weakening control is not performed, the maximum value is set (solid line in FIG. 1).

  If it is determined in step ST3 that the duty ratio has not reached the duty limit value MAX, the process proceeds to step ST5. In step ST5, control is performed to increase the drive duty by the PWM signal generation circuit 38 so that the duty ratio determined by the output duty determination circuit 33 is based on the comparison result of the current comparison circuit 31, and the process returns to step ST1. The inverter 21 is controlled by the increased DUTY, and the driving force of the motor M increases.

  If it is determined in step ST2 that the target value is equal to or less than the current value, the process proceeds to step ST6. In step ST6, it is determined whether or not the core 8a is in the most entered position (position where the effective magnetic flux is maximized). Proceed to step ST7. In step ST7, in this case, since the current drive current is too much with respect to the target value, control for inserting the core 8a is performed to reduce the current. The case where the process proceeds to step ST7 is a state in which the core 8a has been removed. This is a case where the duty ratio has reached the duty limit value MAX because the core 8a is removed when the above steps ST3 and 4 are performed. is there. In this state, the control for decreasing the target current is the control for decreasing the rotational speed from the high rotation side to the low rotation side, and the core 8a is inserted and the process returns to step ST1 contrary to the above step ST4. Also in this case, the duty control is prohibited.

  If it is determined in step ST6 that the core 8a is in the most inserted position, the process proceeds to step ST8. In this case, when the control without removing the core 8a is not performed, the prohibition of the duty control is canceled and the duty control is performed, and the duty ratio is controlled to be reduced as the current reduction control in the duty control. Return.

  Thus, by controlling the field magnitude as variable, it is possible to realize a drive device for an electric vehicle that can withstand general traveling without using a transmission.

  In the illustrated example, the transmission mechanism is the chain 14. However, the transmission mechanism is not limited to the chain transmission mechanism, and may be a gear train transmission mechanism or a belt transmission mechanism. When a transmission mechanism with a fixed reduction ratio is used in the case of a conventional non-variable field normal motor, acceleration / deceleration is performed only by the motor, so the speed adjustment range is narrow and the motor efficiency is poor.

  On the other hand, according to the present invention, the variable field type motor changes the characteristics of the variable field motor over a wide range from low rotation / high torque to high rotation / low torque. At the same time, the speed can be made variable without any problem. As a result, it is possible to realize an electric vehicle that is small, lightweight, highly efficient, and capable of a wide speed change without impeding normal driving.

  It may be combined with a manual transmission. Furthermore, a combination with a coil coiling type motor coil using an intermediate tap is also possible.

  The drive device for an electric vehicle according to the present invention can increase the output with respect to a motor having the same physique, and can provide variable speed performance equivalent to that of a drive device using the speed change mechanism without providing any speed change mechanism. Therefore, it is useful as an electric two-wheeled vehicle, an electric four-wheeled vehicle and the like.

1 is an overall view showing an electric motorcycle to which the present invention is applied. It is sectional drawing which shows the drive device based on this invention. It is a figure which shows the control block suitable for this drive device. It is a flowchart which shows the control point.

Explanation of symbols

2 Drive device 6 Rotor 7 Magnet 8 Stator 10 Slide member 11 Coil 12 Actuator 14a Drive gear 14b Driven gear 15 Chain ECU Control circuit M Electric motor

Claims (2)

An electric motor, and driving force transmission means for transmitting the driving force of the electric motor to the driving wheels at a fixed gear ratio,
The electric motor includes a stator, a rotor provided coaxially and rotatably with respect to the stator, and any one of the stator and the rotor so as to change an opposing area of a surface through which the magnetic flux of the stator and the rotor passes. Moving means for allowing one to move in the axial direction of the rotor,
A variable field motor in which a coil winding is provided on the stator, and a permanent magnet is disposed on the rotor so as to face a stator core on which the coil winding is formed,
A drive current supply circuit for supplying a drive current to the coil winding; and a control means for outputting a pulse width modulated control signal serving as a reference for the supply to the drive current supply circuit,
The control means determines a duty ratio of a control signal that is pulse width modulated based on a target current corresponding to an operation signal for the electric motor, and a pulse based on the duty signal by the duty determination means. width modulated control signal and a pulse width modulation signal generating means for supplying to said driving current supply circuit, the duty ratio reaches the preset duty limit value, the stator and the rotor by the moving means When the control for reducing the facing area is performed, the control of the duty signal determining means is prohibited .   The drive device for an electric vehicle according to claim 1, wherein the driving force transmission means is a chain, a gear, or a belt.

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