JPH0549110A - Battery charger for electric automobile - Google Patents

Abstract

PURPOSE:To provide a light and downsized battery charger for electric automobile with low manufacturing cost. CONSTITUTION:An AC three-phase motor 1 for traveling a vehicle is subjected to rotational speed control through a motor controller 3 (comprising an inverter 5 and an electronic control circuit 6) for controlling the operating state of six switching elements 4a-4f. Charger of a battery 2 for feeding power to the motor 1 comprises a power supply section 9 receiving three-phase commercial power of 200V and a low voltage rectifying means 10 for converting AC power into DC power through a diode bridge. Thus converted DC power is then inverted into high frequency pseudo-AC voltage through a high frequency oscillation means 11 provided in the motor controller 3. Thus produced AC voltage is then boosted through a small transformer 12 and further converted through a high voltage rectifying means 13 into DC voltage for charging the battery 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for charging a battery mounted on an electric vehicle with a commercial low voltage alternating current.

[0002]

2. Description of the Related Art A device for charging a running battery for driving a motor of an electric vehicle using a commercial 100V or 200V AC current boosts a commercial 100V or 200V AC current to a high voltage. I was using a transformer. Since this transformer uses a low frequency, it becomes large in size, it is difficult to secure a mounting space, and there are problems such as an increase in weight and an increase in manufacturing cost. .. In contrast to the above technique, there is known a switching regulator system in which a transformer can be downsized by first converting a commercial power source into a direct current, then converting into a high frequency alternating current and boosting the voltage.

[0003]

The above-mentioned switching regulator type charging device requires a switching element for converting a direct current into a high frequency alternating current, and a radiator for releasing the heat generated by the switching element. Becomes Therefore, by adopting the switching regulator method for the charging device, the physical size of the charging device can be reduced, but the manufacturing cost of the charging device becomes high.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a battery charger for an electric vehicle which is lightweight, small in size, and inexpensive in manufacturing.

[0005]

The battery charger for an electric vehicle of the present invention employs the following technical means. The electric vehicle includes a motor for driving the vehicle, a battery that stores electric power for driving the motor, and a switching element that supplies the electric power stored in the battery to the motor, and controls the operating state of the switching element, And a motor control device that controls the rotation speed of the motor. Then, the battery charging device for an electric vehicle, a power supply unit that receives an alternating current of a low voltage from the outside of the vehicle, a low voltage alternating current supplied from the power supply unit, a low voltage rectifying means for converting to a direct current, When charging the battery, a high-frequency oscillating means for converting a direct current supplied through the low-voltage rectifying means into a high-frequency oscillating voltage using the switching element, and a high-frequency oscillating means converted by the high-frequency oscillating means. And a high-voltage rectifying means for converting the high-voltage alternating current transformed by the transformer into a direct current and applying it to the battery.

The battery charging device for an electric vehicle of the present invention can employ the following technical means. The high frequency oscillation means
It is provided in the motor control device. The motor is an AC motor, and the motor control device is an inverter type motor control device. The motor is a DC motor, and the motor control device is a chopper type motor control device.

[0007]

When the vehicle is running, the motor control device controls the operating state of the switching element. Then, the electric power stored in the battery is supplied to the motor according to the operating state of the switching element, and the motor is rotationally driven. During charging, the low-voltage AC current received by the power supply unit is converted into DC current by the low-voltage rectifying means. This direct current is converted into a high frequency oscillation voltage by the high frequency oscillation means using a switching element for motor control. This high-frequency oscillating voltage is applied to the transformer and converted into a high-voltage alternating current by the transformer. Then, this high-voltage alternating current is converted into direct current by the high-voltage rectifying means and applied to the battery to charge the battery.

[0008]

The switching element for controlling the motor has a large power withstanding capacity and a large heat radiating capacity so as to withstand the excessive electric power applied to the motor. Therefore, the switching element for controlling the motor can be shared for high-frequency oscillation of the charging current. By sharing the switching element for controlling the motor for high-frequency oscillation of the charging current, the switching element dedicated to charging and the radiator of the switching element are not required. In addition, since the transformer changes the voltage by high frequency,
Can be miniaturized. As a result, the size of the device for charging the battery for an electric vehicle can be made smaller and the weight can be reduced, and the charging device manufacturing cost can be kept low by eliminating the need for a charging-dedicated switching element and its radiator. You can

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an electric vehicle battery charging device of the present invention will be described based on an embodiment shown in the drawings. [Structure of Embodiment] FIGS. 1 to 7 show an embodiment of the present invention. FIG. 1 is an electric circuit diagram of a battery charger for an electric vehicle. An electric vehicle controls a vehicle to drive a three-phase AC motor 1 for driving a vehicle, a battery 2 for storing electric power for driving the motor 1, and controls the electric power stored in the battery 2 to supply the electric power to the motor 1. An inverter type motor control device 3 for controlling the rotation speed is provided. The motor control device 3 includes six switching elements 4a to 4f for supplying the electric power stored in the battery 2 to the motor 1.
And an inverter 5 for controlling the amount and timing of energization to each coil of the motor 1, and an electronic control circuit 6 using a microcomputer for controlling the inverter 5 to control the rotation speed of the motor 1. Consists of. The inverter 5 controls the control signal (U,
V, W) to receive the six switching elements 4a-4f.
Drive circuit for driving the transistor bridge according to the above, processing circuit 7 for generating control signals of a total of 6 systems of three phases, and a drive which is a front drive circuit for energizing each of the switching elements 4a to 4f used. The circuit 8 is provided.
In addition, each switching element 4a of the transistor bridge
In order to withstand the excessive electric power applied to the motor 1 to 4f, the electric power withstanding capacity is large, and a radiator is provided to provide a large heat radiating capacity.

The electric vehicle also has a power supply unit 9 for receiving commercial power from outside the vehicle in order to charge the battery 2, a low-voltage rectifying means 10 for converting the supplied power into a DC current, and a DC current for oscillating a high frequency. A high frequency oscillating means 11 for producing an oscillating voltage, a transformer 12 for converting into a high voltage, and a high voltage rectifying means 13 for converting into a DC voltage and applying it to the battery 2 are provided.
The power supply unit 9 is an outlet connected to an outlet for supplying commercial power, and supplies 3-phase 200 V, 50/60 Hz (low voltage, low frequency alternating current) power through the outlet. receive. The low-voltage rectifying means 10 is a diode bridge that converts an alternating current supplied from the power supply unit 9 into a direct current. The high frequency oscillating means 11 is provided in common with the motor control device 3, and oscillates the current DC-converted by the low voltage rectifying means 10 using the switching elements 4a to 4f to convert it into a high frequency AC voltage. To do. The transformer 12 is a transformer that converts the high-frequency AC voltage oscillated by the high-frequency oscillator 11 into a high voltage. The high-voltage rectification means 13 is a diode rectification circuit for converting the high-voltage alternating current transformed by the transformer 12 into direct current and applying it to the battery 2. The electric circuit of the electric vehicle is provided with an interlock switch 14 for connecting and disconnecting the battery 2 and the inverter 5, and switching between the inverter 5 and the motor 1 or between the inverter 5 and the transformer 12. The interlocking switch 14 may be a manual switch that gives a charging instruction, or a relay switch or a semiconductor switch that automatically switches when a charging instruction is given.

The motor control device 3 which also functions as the high frequency oscillation means 11 will be described. The electronic control circuit 6 of the motor control device 3 inputs an accelerator opening degree, a motor rotation speed, and a motor current in order to control the rotation speed of the motor 1, and a charge instruction, a battery voltage, Charge current is input. Then, the electronic control circuit 6
Outputs a three-phase control signal (U, V, W) output to the processing circuit 7 in accordance with the input signal. In addition, the inverter 5
The processing circuit 7 is provided with a switching relay switch 15 for switching the driving states of the switching elements 4a to 4f in response to the input signal from the electronic control circuit 6. The changeover relay switch 15 is also switch-controlled by the electronic control circuit 6 so as to switch between charging and traveling.

The energization control of the motor 1 when the vehicle is traveling by the motor control device 3 will be described. When the vehicle is running, one of the interlocking switches 14 connects the battery 2 and the inverter 5, and the other of the interlocking switches 14 connects the inverter 5 and the motor 1.
And connect. As a result, the electric power of the battery 2 is connected to the motor 1 via the inverter 5. At this time, the switching relay switch 1 is controlled so that the motor 1 is energized by the three-phase control signal of the electronic control circuit 6.
5 is switched to the traveling side. The electronic control circuit 6
As shown in FIG. 2 and FIG. 3, a calculation unit 16 that calculates the cycle and amplitude of the sine wave from the feedback signals of the accelerator opening, the rotation speed of the motor 1, and the motor current is provided. The calculation result calculated by the calculation unit 16 is output to the sine wave oscillating unit 17, and a sine wave based on the calculation result is formed. The sine wave formed by the sine wave oscillator 17 is
The sine waves for three phases, which are output to the phase shift circuit and are shifted by 120 °, are created and output to the plus terminal of the comparator 18 for each phase (see the solid line B in FIG. 3). Comparator 1 for each phase
The triangle wave output from the triangle wave oscillator 19 is input to the minus terminal of 8 (see the solid line B in FIG. 3). And
Each control signal (U, V, W) indicated by the solid line A in FIG. 3 is output from each comparator 18 to the processing circuit 7 of the inverter 5. Then, the processing circuit 7 of the inverter 5 outputs each control signal (U, V, W) output from the electronic control circuit 6.
To generate six control signals for driving the six switching elements 4a to 4f. A solid line B in FIG. 3 indicates a control signal which is inverted by the inverting circuit of the processing circuit 7 and applied to the drive circuit 8. The control signal U drives the switching elements 4a and 4b, the control signal V drives the switching elements 4c and 4d, and the control signal W drives the switching elements 4e and 4f.

The operation of the electronic control circuit 6 while the vehicle is running is shown in the flow chart of FIG.

Next, charging of the battery 2 by the motor control device 3 will be described. When charging the battery 2, one of the interlocking switches 14 disconnects the battery 2 and the inverter 5, and the other of the interlocking switches 14 separates the inverter 5 and the transformer 1.
Connect with 2. As a result, the electric power received by the electric power supply unit 9 is converted into the low-voltage rectifying means 10, the inverter 5, and the transformer 1.
2. The battery 2 is charged via the high-voltage rectification means 13 in a connected state. At this time, the changeover relay switch 15 is switched to the charging side so that the AC voltage is applied to the primary coil side of the transformer 12 by the three-phase control signal of the electronic control circuit 6. As shown in FIGS. 5 and 6, the electronic control circuit 6 includes a calculation unit 16 that calculates a PWM control voltage (Uc, Vc, Wc) for charge control from a charge instruction, a battery voltage, and a charge current. P calculated by this calculator 16
The WM control voltage (Uc, Vc, Wc) is output to the plus terminal of the comparator 18 for each phase. The high frequency triangular wave output from the triangular wave oscillator 19 is input to the negative terminal of the comparator 18 of each phase (see solid line B in FIG. 6). Then, the comparator 18 that outputs the control signal U
6 outputs the waveform shown by the solid line C in FIG. 6, and the comparator 18 that outputs the control signal V outputs the waveform shown by the solid line D in FIG.
The waveform indicated by the solid line E in FIG. 6 is output from the comparator 18 that outputs Then, the inverter 5 receives the control signal U output from the electronic control circuit 6 to drive the switching elements 4a and 4d, and the control signal V drives the switching elements 4b and 4c. Since the control signal W has a voltage of 0, the switching elements 4e and 4f are turned off. As described above, the high-frequency pseudo AC voltage shown by the solid line F in FIG. 6 is applied to the primary coil of the transformer 12. Then, this AC voltage is supplied to the battery 2 by the transformer 12.
The voltage is raised to a voltage required for charging, the high voltage rectifying means 13 converts the voltage into a direct current, and the direct current is applied to the battery 2 to charge the battery 2. The calculation unit 16 of the electronic control circuit 6 monitors the battery voltage and the charging current, and until the battery voltage reaches a predetermined voltage, the PWM control voltage (U
c, Vc) to change the control signal U, V
Is controlled so that the charging current is within a predetermined range. The charging is stopped when the battery voltage reaches a predetermined voltage.

The operation of the electronic control circuit 6 at the time of charging described above is shown in the flowchart of FIG.

[Operation of Embodiment] Next, the operation of the above embodiment will be briefly described. When the vehicle is running, the motor controller 3 calculates the required torque of the motor 1 from the accelerator opening, the rotation speed of the motor 1, and the motor current, and the transistor bridge is used so that the calculated torque is generated in the motor 1. The switching elements 4a to 4f are controlled. Then, the electric power charged in the battery 2 is supplied to the motor 1 according to the driving states of the switching elements 4a to 4f, and the motor 1 is rotationally driven. When charging the battery 2,
When the power supply unit 9 is connected to a commercial power source and a charging switch (not shown) is turned ON, the switching elements 4a to 4d are turned ON-O at a duty ratio according to the battery voltage and the charging current.
FF. On the other hand, the 200V three-phase alternating current supplied from the power supply unit 9 is converted into direct current by the low-voltage rectifying means 10.
Then, the electric power converted into the direct current by the low voltage rectifying means 10 is applied to the inverter 5 and the switching elements 4a to 4a.
It is converted into a high-frequency pseudo AC voltage by high-speed ON-OFF of 4d. This AC voltage is converted to DC by the high voltage rectifying means 13 and then applied to the battery 2 to charge the battery 2. In addition, the charging current is suppressed within a predetermined range,
The battery 2 is provided so as to prevent drainage of the battery 2 and deterioration of the electrodes. Then, when the battery voltage reaches a predetermined voltage, the charging of the battery 2 is stopped.

[Effect of Embodiment] In this embodiment, the motor 1
Of the switching elements 4a to 4f that control the energization of
By sharing the switching elements 4a to 4d for high-frequency oscillation of the charging current, the charging-dedicated switching element and the radiator of the switching element can be eliminated. Moreover, since the transformer 12 changes the voltage by high frequency, it can be miniaturized. Further, by providing the high frequency oscillating means 11 for switching the switching elements 4a to 4f at high speed during charging in common with the motor control device 3, the size and weight of the device for charging the battery 2 can be reduced. As described above, the device for charging the battery 2 is downsized by eliminating the need for a switching element dedicated to charging and its radiator, downsizing the transformer 12, and sharing the high-frequency oscillator 11 and the motor control device 3. ,
Since the weight can be reduced and the switching element dedicated to charging and its radiator are not required, the manufacturing cost of the charging device can be kept low.

[Second Embodiment] FIG. 8 is an electric circuit diagram showing a second embodiment of the battery charging device for an electric vehicle. In this embodiment, a DC brush motor is used as the motor 1 for running the vehicle, and the rotation speed of the motor 1 is controlled by a chopper-type motor control device 3 that controls the switching element 4 at high speed. The motor control device 3 calculates an input signal when the vehicle is traveling, outputs a PWM signal having a duty ratio according to operating conditions to the drive circuit 8 and the switching element 4, and controls the amount of current applied to the motor 1, The rotation of the motor 1 is controlled. Also,
When a charging instruction is given, the motor control device 3 calculates the battery voltage and the charging current, and controls the duty ratio so that the switching element 4 operates at high speed so that a constant charging current is applied to the battery 2. It is turned on and off to convert the low-voltage direct current supplied through the low-voltage rectifying means into a high-frequency oscillation voltage, and adjust the voltage applied to the battery 2.

In this embodiment, the interlock switch 1 is provided in the electric circuit.
The present invention can be implemented in an electric vehicle using the chopper-type motor control device 3 only by adding No. 4 and calculation software for charging to the computer of the motor control device 3.

[Modification] In the above embodiment, the high frequency oscillating means for switching the switching element at high speed during charging is provided in common with the motor control device. However, the high frequency oscillating means is used as the motor control device. It may be provided separately.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram showing a first embodiment of a battery charging device for an electric vehicle.

FIG. 2 is an electric circuit diagram of an electronic control circuit used when the vehicle is traveling.

FIG. 3 is a time chart of signals generated by an electronic control circuit when the vehicle is traveling.

FIG. 4 is a flowchart showing the operation of an electronic control circuit when the vehicle is traveling.

FIG. 5 is an electric circuit diagram of an electronic control circuit used during charging.

FIG. 6 is a time chart of signals generated by an electronic control circuit during charging.

FIG. 7 is a flowchart showing the operation of the electronic control circuit during charging.

FIG. 8 is an electric circuit diagram showing a second embodiment of the battery charging device for an electric vehicle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 motor 2 battery 3 motor control device 4a-4f switching element 9 electric power supply part 10 low voltage rectification means 11 high frequency oscillation means 12 transformer 13 high voltage rectification means

Claims (4)

[Claims] 1. A motor for traveling a vehicle, a battery for storing electric power for driving the motor, and a switching element for supplying the electric power stored in the battery to the motor. The operating state of the switching element is controlled. A motor control device for controlling the rotation speed of the motor; a power supply unit for receiving a low-voltage alternating current from outside the vehicle; and a low voltage for converting the low-voltage alternating current supplied from the power supply unit into a direct current. Rectifying means, a high-frequency oscillating means for converting a direct current supplied through the low-voltage rectifying means into a high-frequency oscillating voltage when the battery is charged, and the high-frequency oscillating means A transformer that converts the converted high-frequency oscillation voltage into a high voltage, and the high-voltage alternating current that is transformed by this transformer is converted into a direct current. Electric vehicle battery charging apparatus comprising a high voltage rectifying means for applying to the battery. 2. The battery charging device for an electric vehicle according to claim 1, wherein the high-frequency oscillating means is provided in the motor control device. 3. The battery charging device for an electric vehicle according to claim 1, wherein the motor is an AC motor, and the motor control device is an inverter type motor control device. 4. The battery charging device for an electric vehicle according to claim 1, wherein the motor is a DC motor, and the motor control device is a chopper type motor control device.