JPH08265986A - Inductive charging method - Google Patents

Abstract

PURPOSE: To shorten the charging time of battery while reducing power loss by regulating the frequency of power being supplied from a charging station to a battery through electromagnetic induction and charging the battery with constant current in the first half of charging operation while charging the battery with constant voltage in the second half of charging operation. CONSTITUTION: When an electric automobile is charged, power is fed through a frequency converter and a noncontact connector to the automobile side by electromagnetic induction and then it is fed through a rectifier to a battery. A charge controller for battery detects the charging current and voltage of battery and delivers the data thereof to the charging station side where the frequency of power to be fed is controlled depending on the data. In case of 8 hour charging, for example, the frequency is varied in the range of 200-30kHz for 5 hours after start of charging operation so that the battery is charged with a constant current and then the frequency is varied in the range of 200-10kHz for the remaining 3 hours so that the battery is charged with a constant voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of charging a battery such as an electric vehicle.

[0002]

2. Description of the Related Art As a method of charging a battery of an electric vehicle, for example, "rapid charging system and non-contact charging" ... Battery Technology Symposium (1994) pG5-4-1 ~ G
There is a contactless charging system, as shown in 5-4-9. This is a system that supplies power to a battery by electromagnetic induction from a charging station with a contactless connector. Conventionally, in this type of system, a method of supplying electric power of a constant frequency has been used.

[0003]

However, this charging method has the following problems. It is not the best power supply method to charge the battery, and the battery charging time becomes longer. That is, if the frequency is constant and the voltage is constant in the initial stage of charging, the charging time is longer than that when the voltage is changed. Since the electric power of the same frequency is always supplied, the generated electric power loss becomes large. That is, at the end of charging, power can be supplied even if the current is small, and the power loss is proportional to the square of the frequency. Therefore, lowering the frequency can reduce the loss.

[0004]

The present invention has been made to solve the above problems, and is characterized by an inductive charging method for supplying power to a battery by electromagnetic induction from a charging station having a non-contact connector. In the above, by adjusting the frequency of the supplied power, the first half of charging is constant current charging (changing the voltage so that the current is constant), and the latter half is constant voltage charging (current so that the voltage is constant). To change). At this time, it is preferable to wirelessly transmit the charging voltage and current value of the battery from the charging controller on the battery side to the charging station, and change the frequency of the supplied power in response to this signal.

[0005]

By changing the frequency of the supplied power, the current and voltage values can be adjusted, and the first half of charging can be constant current charging and the latter half can be constant voltage charging. Therefore, the charging time of the battery and the generated power loss can be reduced.

[0006]

Embodiments of the present invention will be described below by taking charging of an electric vehicle as an example. FIG. 1 is a block diagram of the method of the present invention. As shown in the figure, a frequency converter 1 is provided so that the frequency of the commercial frequency power can be converted. In this example, the frequency converter 1 controls the frequency of the supplied power to 10 kHz.
It is configured to be continuously variable from z to 300 kHz.

The electric power passing through the frequency converter 1 is supplied to the automobile side by electromagnetic induction through a connector 2 which is not in contact with the automobile side, and is supplied to the battery 4 through a rectifier 3. Here, the battery 4 includes a charge controller 5, which detects a charging current and a charging voltage of the battery 4 and transmits the data to the charging station side.
The charging station controls the frequency of the supplied power in response to this signal.

Using such a system, for example, 8
When charging for an hour, as shown in Fig. 2, the frequency is set to 200 kHz so that constant current charging is performed for 5 hours after the start of charging.
Change between ~ 300kHz and change between 200kHz ~ 10kHz so that constant voltage charging will be performed for the last 3 hours. Since electric power can be supplied at the end of charging even when the current is small, as described above, by lowering the frequency to reduce the power loss, efficient charging suitable for the charging characteristics of the battery can be performed.

[0009]

As described above, according to the method of the present invention, in inductive charging, the current and voltage values are adjusted by changing the frequency of the supplied power, and the battery charging time is shortened. Power loss can be reduced. In particular, if the charging current and the voltage value of the battery are wirelessly sent to the charging station and the frequency of the supplied power is changed in response to this signal, efficient charging suitable for the charging characteristics of the battery can be performed. Therefore,
It is effective when applied to the charging of electric vehicles.

[Brief description of drawings]

FIG. 1 is a block diagram of a method of the present invention.

FIG. 2 is a graph showing changes in current and voltage when charging is performed by the method of the present invention.

[Explanation of symbols]

1 Frequency converter 2 Connector 3 Rectifier 4 Battery 5 Charge controller

Claims (2)

[Claims] 1. An inductive charging method for supplying power to a battery by electromagnetic induction from a charging station having a non-contact connector, wherein the first half of charging is constant current charging and the second half is adjusted by adjusting the frequency of the supplied power. Is a constant voltage charging method. 2. The charging controller on the battery side wirelessly transmits the charging voltage and the current value of the battery to the charging station, and the frequency of the electric power to be supplied is changed in response to this signal. The described inductive charging method.