JPH07115736A - Charging device for electric rolling stock - Google Patents

Abstract

PURPOSE:To achieve light weight by using a high frequency transformer, to obtain a level, at which vehicle mounting is possible, and to perform the control so that a power factor is made to approach 1. CONSTITUTION:The waveform of the command current of a current control circuit is made analogous to the waveform on an input voltage for a voltage detecting circuit 17. When the voltage is lower than a battery voltage, a circuit 13 for shorting a reactor 8 is provided. The signals from a voltage comparing circuit 19 and a gate circuit 23 are inputted into an AND circuit 22, and obtained signal with the AND circuit is applied in this constitution. Thus, the control can be performed so that the waveform of the current is made analogous to the waveform of the input voltage. Therefore, the power factor is approximately close to 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery charger for an electric vehicle, and more particularly to a control used at a high frequency in order to miniaturize an insulation transformer. The content of control is to bring a power factor of an input current close to 1. It is about control.

[0002]

2. Description of the Related Art As a conventional technique, Japanese Patent Application Laid-Open No. 59-61402 discloses a technique of connecting a transformer to an electric vehicle having a three-phase AC motor, an inverter and a battery to charge the electric vehicle.

The transformer is installed outside the vehicle. This is because the weight of the transformer is large and it is not suitable for mounting on a vehicle.

A possible method for this is to use a transformer at a high frequency. This is shown in the charging circuit when the high frequency transformer of FIG. 2 is used. That is, the semiconductor switch of the bridge circuit is turned on and off so that the primary side of the transformer is rectified, and then the polarity of the primary side of the transformer is changed at a high frequency (conduction rate: approximately 50%), and the voltage generated by the secondary side coil is changed. Is full-wave rectified and applied to the inverter.

According to this method, the input voltage and the battery charging circuit can be insulated, and the transformer can be made compact.

However, since the current control is performed by the inverter section mounted on the vehicle, there is a problem that the control for making the input current waveform similar to the input voltage waveform becomes complicated: the control circuit for bringing the power factor close to 1 becomes complicated. .

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the size by using a high frequency transformer so that it can be mounted on a vehicle and to control the power factor close to 1.

[0008]

The AC power supply is rectified, the semiconductor switch of the bridge circuit is turned on / off, and the full-wave rectification circuit of the secondary coil is connected, which is the same as the conventional method.

A full-wave rectifier circuit connected to the secondary coil of the transformer is provided with a semiconductor element for short-circuiting the reactor and a circuit in which a diode is inserted between the reactor and the battery.

A voltage comparison circuit for comparing the battery voltage with the full-wave rectification circuit voltage on the secondary side of the transformer is provided.

It is composed of a current control circuit that uses a voltage proportional to the input voltage as a control command current, a current sensor that detects the input current, and a control circuit that feeds back this signal to the current control circuit.

[0012]

The transformer secondary coil voltage is the input voltage multiplied by the turns ratio, and the turns ratio is determined. Therefore, by comparing the input voltage and the battery voltage (Vb), it becomes possible to compare the battery voltage and the output voltage (Vd) of the full-wave rectification circuit on the secondary side of the transformer.

The output voltage (Vd) is (Vb)
When it is larger, the battery current can directly flow, so that the semiconductor element of the bridge circuit can be turned on / off to control the current.

Next, the output voltage (Vd) is (Vb)
If it is smaller, the output signal of the voltage comparison circuit is generated, and thereby, in synchronization with the semiconductor ON signal of the bridge circuit,
Turn on the semiconductor element for the reactor short circuit. As a result, a current from the AC power supply flows, and when the fed-back current becomes larger than the command value, all semiconductor elements are turned off. Then, as for the energy stored in the reactor, an alternating current flows through the diode inserted in series with the battery. Similarly, the input current waveform can be similar to the input voltage waveform. In other words, it became possible to bring the power factor close to 1.

[0015]

Embodiments will be described below with reference to the drawings.

FIG. 1 shows a charge control circuit and a block diagram.

A first full-wave rectifier circuit 2 composed of diodes D1 to D4 is connected from an AC power supply 1, and the rectified voltage is applied to a bridge circuit 6 composed of IGBT1 to IGBT4 to generate a high frequency wave. The primary coil 4 of the transformer 3 is energized.

The secondary coil 5 of the high frequency transformer is connected to the second full-wave rectifying circuit 7 composed of the diodes D5 to D8, and the reactor 8 and the diode D9 are connected in series to the battery 10.

A short-circuiting semiconductor element (IGBT 5) 13 is connected to the connection point between the reactor 8 and the diode D9 and the battery (10) (-) electric wire 12.

In order to detect the input current, the current sensor 14
Is inserted into the input of the AC power supply 1 or the input / output line of the first full-wave rectifier circuit 2.

The primary side of the measuring transformer 15 is connected to an AC power source, the input power source waveform detecting coil 16 is full-wave rectified by a voltage detecting circuit 17, and the battery voltage detecting circuit 18 is a (+) electric wire of the battery 10. It detects the voltage between the (-) and (-) electric wires and serves as an input signal to the voltage comparison circuit 19.

In the voltage comparison circuit 19, when the voltage is smaller than the battery voltage, the output signal becomes H, and a signal for turning on / off the short-circuiting semiconductor element 13 via the AND circuit 22 with the ON / OFF signal of the bridge circuit 6. And

The output of the current sensor 14 is the current detection circuit 20.
And becomes a feedback signal of the current control circuit 21. Then, the gate circuit 23 turns on / off the bridge circuit 6. The capacitors C1 and C2 are for absorbing ripples and reduce noise generation. The capacitor C3 reduces the pulsation of the load charging current.

The measuring transformer 15 includes a gate circuit 23.
There is a power supply coil 24 for control circuit power supply coil 25.

FIG. 3 illustrates this operation.

The output voltage (V from the second full-wave rectifier circuit 7)
When d) is higher than the battery voltage (Vb), only the bridge circuit 6 is used, and when Vd is lower than Vb, the reactor short-circuit semiconductor element 13 is turned on / off.

FIG. 4 is a circuit showing the block diagram of FIG. 1 in detail.

The voltage detection circuit 17 is full-wave rectified and C
The size is changed and output from the / A conversion element and OPAMP (operational amplifier). Full-wave rectified is the current sensor 1
The reason is that the voltage of the voltage detection coil 16 is applied if an AC waveform is applied.

The current control circuit 21 uses a switching regulator element, and an on / off output signal is applied to the gate circuit 23 by comparison in an error amplifier (EA).

FIG. 5 shows the power supply coil section of the control circuit of FIG. 1 in detail. The auxiliary battery 26 is used as a power source for the control circuit 27 via the diode D10.

The relay 28 is turned on at the time of charging so that the auxiliary battery 26 can be charged. Even if the input voltage is cut off due to a power failure, power is supplied to the control circuit 27 via the auxiliary battery 26, so that there is no problem that the control sequence is broken.

[0032]

Since the charging current can be made similar to the input power supply waveform, the power factor approaches 1 and the input power can be effectively used.

[Brief description of drawings]

FIG. 1 is a block diagram of a charging control circuit according to the present invention.

FIG. 2 is a charging circuit diagram when a high frequency transformer is used.

FIG. 3 is a diagram for explaining the operation of FIG.

FIG. 4 is a circuit diagram showing details of FIG.

5 is a diagram showing a measuring transformer unit of FIG. 1. FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... AC power supply, 2 ... 1st full wave rectification circuit, 3 ... High frequency transformer, 4 ... Primary coil, 5 ... Secondary coil, 6 ... Bridge circuit, 7 ... 2nd full wave rectification circuit, 8 ... Reactor , 9
… Diode, 10… Battery, 11… (+) electric wire, 1
2 ... (-) electric wire, 13 ... Short-circuit semiconductor element, 14 ... Current sensor, 15 ... Measuring transformer, 16 ... Voltage detection coil, 17 ... Voltage detection circuit, 18 ... Battery voltage detection circuit, 19 ... Voltage comparison circuit, 20 ... Current detection circuit, 21 ...
Current control circuit, 22 ... AND circuit, 23 ... Gate circuit,
24 ... Gate power supply coil, 25 ... Control circuit power supply coil, 26 ... Auxiliary battery, 27 ... Control circuit, 28 ... Relay.

Claims (1)

[Claims] 1. A battery charger in which an AC power supply is composed of a first full-wave rectification circuit, a high-frequency transformer, a bridge circuit, a second full-wave rectification circuit, a reactor, and a battery, and the AC power supply is insulated by a high-frequency transformer. A semiconductor element that short-circuits the diode, a diode is connected from the reactor in the direction of the battery, a current sensor that detects the current flowing from the first full-wave rectifier circuit to the bridge circuit is connected, and the voltage of the second full-wave rectifier circuit and the battery When the voltage comparison circuit that compares the voltages outputs a signal that the voltage of the second full-wave rectifier circuit is higher than the battery voltage, the conduction ratio of the bridge circuit is adjusted, and the voltage of the second full-wave rectifier circuit is changed to the battery voltage. When a signal that is smaller than that is output, the semiconductor elements that short-circuit the reactor as well as the bridge circuit are made conductive, and these energizing currents are proportional to the input voltage of the AC power supply. It was composed of a current control circuit according to the electric vehicle battery charger according to claim.