JPH0965666A - Battery charger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize, with a simplified structure, a battery charger which executes, at the time of charging, both voltage boosting chopper and voltage falling chopper. SOLUTION: At a charging arm IV, transistors Q7 and Q8 as the switching elements are provided. On the occasion of driving a motor 10 with an output of a battery 12, thyristors Q9 and Q10 are turned on for power conversion using power conversion arms I to III. When a battery 12 is to be charged with a charging power supply 18, the transistors Q1 to Q4 and thyristors Q8, Q9 are turned off. When voltage boosting is necessary during the charging operation, the transistors Q7 and Q8 are turned off and voltage boosting chopping is executed with transistors Q5 and Q6. The voltage falling is required, the voltage falling chopping is executed with the transistors Q5 to Q8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery charger which charges a battery by using a motor winding as an energy storage inductor and an inverter circuit as a chopper circuit, respectively.

[0002]

2. Description of the Related Art In an electric vehicle that uses an AC motor as a running motor, the discharge output of a battery is converted from DC to AC and supplied to the running motor, and braking energy regenerated by the running motor is converted into an AC. In general, an inverter circuit is used to convert from DC to DC for supply to a battery. On the other hand, in an electric vehicle, it is necessary to charge a vehicle-mounted battery, which is discharged as the vehicle travels, at a predetermined frequency. Therefore, it is also necessary to mount a battery charger on the vehicle. In the battery charging device for an electric vehicle disclosed in JP-A-6-133564, a charging arm is newly added to the inverter circuit in addition to the power conversion arm. That is, when the battery is charged by the charging power source, the switching element forming the power conversion arm is selectively turned off, so that the charging arm is included and the motor winding is used as the energy storage inductor. The existing chopper circuit is formed using the inverter circuit. According to Japanese Patent Laid-Open No. 6-133564, the battery charging device and the inverter circuit are used in common, and the system is downsized.

[0003]

However, Japanese Patent Application Laid-Open No.
The charging arm added in Japanese Patent No. 33564 is composed only of a diode. Therefore, only by adding one charging arm, only the boost chopper circuit can be realized (see FIG. 1 of the publication). In order to realize a step-down chopper circuit, it is necessary to add a plurality of charging arms and to provide a contactor for cutting the DC bus of the chopper bridge in order to form a full-wave rectifier circuit (see FIG. (See (a)). These lead to complicated circuit structure, large size, low efficiency, and high cost and low reliability due to increased number of parts. In particular, reliability and durability of the contactor become a problem in an application such as an electric vehicle where vibration or impact may be applied to an electric circuit.

The present invention has been made to solve the above problems, and by improving the charging arm, it becomes unnecessary to provide a plurality of charging arms and a contactor for disconnecting the battery wiring. The purpose is to realize the simplification, miniaturization, efficiency improvement, cost reduction and high reliability of the circuit configuration. It is another object of the present invention to provide a battery charger suitable for an application such as an electric vehicle in which vibration or impact may be applied to an electric circuit by achieving this object.

[0005]

In order to achieve such an object, a first structure of the present invention includes a switching element which is turned on / off in response to a command and is provided between a corresponding phase motor winding and a battery. A plurality of intervening power conversion arms,
A charging arm interposed between the battery and the charging power source,
When charging the battery with the charging power source, one end of the charging power source is connected to a connection point between any one of the power conversion arms and the motor winding of the phase corresponding to the one of the power conversion arms, Further, in a battery charger in which the other end of the charging power source is connected to the charging arm, the charging arm includes a switching element that turns on and off according to a command, and the switching element of the power conversion arm and the switching of the charging arm. The elements are connected to each other so as to form both a step-up chopper circuit and a step-down chopper circuit. Thus, in this configuration,
The charging arm includes a switching element that turns on and off according to a command. Therefore, both the step-up chopper circuit and the step-down chopper circuit can be realized by using the power conversion arm and the charging arm. At that time, it is not necessary to provide a plurality of charging arms or a contactor.

In the battery charger according to the second structure of the present invention, by controlling the switching element of the power conversion arm when supplying power from the battery to the motor or from the motor to the battery in the first structure. A means for converting the power related to the supply from direct current to alternating current or from alternating current to direct current, and by turning off the switching element of any one of the above power conversion arms when charging the battery with the output of the charging power source. A motor winding is inserted between the charging power source and the inverter circuit, and at least another switching element of the power conversion arm is turned on / off, whereby the inverter circuit functions as a chopper circuit, and the output of the charging power source. If it is necessary to boost the voltage when charging the battery at, the other switching element of the power conversion arm When the step-down is required, the switching elements of the other power conversion arm and the charging arm are turned on / off respectively, so that the function of the chopper circuit can be selectively applied to either the step-up chopper or the step-down chopper. And a switching means. As described above, in this configuration, the step-up chopper circuit and the step-down chopper circuit are selectively realized by using the power conversion arm and the charging arm.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of an electric vehicle according to an embodiment of the present invention. In this embodiment, a three-phase AC motor is used as the traveling motor 10, and a battery 12 is mounted as its driving power source. The inverter circuit 14 is a circuit that converts the output of the battery 12 from DC to three-phase AC when the motor 10 is driven,
It is also used to convert the braking energy regenerated by the motor 10 from three-phase alternating current to direct current. The charging connector 16 is a connector that is connected when the battery 12 is charged by the output of a charging power source (here, a single-phase AC power source) 18 outside the vehicle. In the figure, C is the battery 1 when charging
2 is a capacitor for smoothing the voltage input to 2.

Each of the inverter circuits 14 has a power conversion arm I-II connected between the positive and negative ends of the battery 12.
I and charging arm IV. The power conversion arms I to III are respectively connected to the U, V, and W phase windings of the motor 10, and cooperate to form a three-phase inverter. On the other hand, the charging arm IV is connected to the charging connector 16, so that when the charging connector 16 is connected, one end of the charging power supply 18 is connected to the charging arm IV.
When the charging connector 16 is connected, the other end of the charging power supply 18 is connected to one end of the W-phase winding of the motor 10. Further, each arm of the inverter circuit 14 has a configuration in which two transistors (eg, IGBT) are connected in series, and a diode is reversely connected between the collector and emitter of each transistor. However, in the arm I, a thyristor is used instead of the diode. This is to prevent a large current from flowing in the arm I during step-down chopping described later.

The controller 20 includes an inverter circuit 14
Is a means for controlling the operation of. As shown in FIG.
The controller 20 first detects the connection state of the charging connector 16 based on, for example, the potential of the charging connector 16 (100). When the charging connector 16 is open, the controller 20 turns off the transistors Q7 and Q8 and turns on the thyristors Q9 and Q10 (102). By turning on the thyristors Q9 and Q10, the power conversion arm I is changed to another power conversion arm II.
And III, so that a circuit similar to a normal inverter is equivalently formed by the power conversion arms I to III. Further, by turning off the transistors Q7 and Q8, conduction to the charging arm IV can be cut off. In this state, the controller 20 sets the transistor Q1
By switching Q6 to Q6, the inverter function is exhibited by the inverter circuit 14 (104).
More specifically, the controller 20 supplies the required drive current to the motor 10 by switching the transistors Q1 to Q6 according to the accelerator pedal depression state and the like.
In addition, the transistors Q1 to
The motor 10 regeneratively brakes the vehicle by switching Q6.

When the charging connector 16 is connected (100), the controller 20 controls the transistors Q1 to Q.
4 is turned off and thyristors Q9 and Q10 are turned off (106). As a result, conduction in the power conversion arms I and II is cut off. The controller 20
Next, the voltage required for charging the battery 12 is compared with the voltage of the charging power source 18 defined by the standard or the specification (108). As a result, when the voltage of the charging power source 18 is lower, the controller 20 turns off the transistors Q7 and Q8 (110) and executes switching control of the transistors Q5 and Q6 (11).
2) On the contrary, when the voltage of the charging power source 18 is higher, switching control of the transistors Q5 to Q8 is executed (114). Since the equivalent circuit of the inverter circuit 14 in steps 110 and 112 is a circuit as shown in FIG. 3, full-wave rectification of the output of the charging power source 18 and the U-phase and W-phase windings are used as inductors for energy storage. The boost chopping used can be executed. Since the equivalent circuit of the inverter circuit 14 in step 114 becomes a circuit as shown in FIG. 4, full-wave rectification of the output of the charging power supply 18 and the U-phase and W-phase windings were used as inductors for energy storage. Can perform buck chopping.

As described above, according to this embodiment, any one of the step-up chopper circuit and the step-down chopper circuit is used by using the power conversion arms I to III and the charging arm IV and with a simple and highly reliable configuration. Can also be realized. Although the above description relates to application to electric vehicles, the present invention can be applied to other applications. Transistors Q1 to Q8
Alternatively, another type of switching element may be used, and instead of thyristors Q9 and Q10, another type of forward conduction switch element may be used.

[0013]

As described above, according to the first configuration of the present invention, since the charging arm includes the switching element that is turned on / off in response to the command, both the step-up chopper circuit and the step-down chopper circuit are provided. A feasible circuit can be provided.

According to the second aspect of the present invention, further, means for forming an inverter circuit using the power converting arm, means for forming a chopper circuit using at least the power converting arm, and step-up / step-down voltage. The power conversion arm or the charging arm is provided with means for selectively switching the function of the chopper circuit to either the step-up chopper or the step-down chopper according to the necessity of the power conversion arm and the charging arm. Both the step-up chopper circuit and the step-down chopper circuit can be realized by using. At that time, it is not necessary to provide a plurality of charging arms or a contactor. Therefore, it is possible to realize a simplified circuit configuration, downsizing, efficiency improvement, cost reduction, and high reliability, and a battery charger suitable for applications such as an electric vehicle where vibration or shock may be applied to the electric circuit. Can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing a system configuration of an electric vehicle and a circuit configuration of an inverter circuit according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a flow of operation of a controller in this embodiment.

FIG. 3 is a circuit diagram showing an equivalent circuit at the time of boost chopping.

FIG. 4 is a circuit diagram showing an equivalent circuit during step-down chopping.

[Explanation of symbols]

10 motor, 12 battery, 14 inverter circuit, 16 charging connector, 18 charging power source, 20
Controller, Q1 to Q8 transistors, Q9, Q1
0 Thyristor, D1-D6 diode, I-III
Power conversion arm, IV charging arm.

Claims (2)

[Claims] 1. A plurality of power conversion arms that include a switching element that turns on and off in response to a command and that are interposed between a corresponding phase motor winding and a battery, and a charging arm that is interposed between the battery and a charging power source. When charging the battery with the charging power supply, one end of the charging power supply is provided at a connection point between any one of the power conversion arms and the motor winding of the phase corresponding to the one of the power conversion arms. In addition, in the battery charger in which the other end of the charging power source is connected to the charging arm, the charging arm includes a switching element that turns on and off according to a command, and the switching element of the power conversion arm and the charging arm. 2. The battery charger according to claim 1, wherein the switching elements are connected to each other so as to form both a step-up chopper circuit and a step-down chopper circuit. 2. The battery charging device according to claim 1, wherein when power is supplied from the battery to the motor or from the motor to the battery, power is supplied from DC to AC by controlling a switching element of a power conversion arm. Or a means for converting from alternating current to direct current, and when charging the battery with the output of the charging power source, by turning off the switching element of any one of the above power conversion arms, the charging power source and the inverter circuit A means to make the inverter circuit function as a chopper circuit by inserting a motor winding between them and turning on and off at least other switching elements of the power conversion arm, and when charging the battery with the output of the charging power supply. If it is necessary to boost the voltage, it is necessary to lower the switching element of the other power conversion arm described above. In that case, switching elements of the other power conversion arm and charging arm,
A battery charger comprising: means for selectively switching the function of the chopper circuit to either a step-up chopper or a step-down chopper by turning them on and off.