JPH0677447U - Battery charger - Google Patents

Abstract

(57) [Abstract] [Purpose] To prevent a transformer from being damaged by a high temperature in a battery charger, and also to make a charging time relatively short. [Configuration] A transformer 1 is provided with a thermistor 4, and a transformer temperature T detected by the thermistor 4 is a predetermined upper limit temperature T.
When it becomes 1, a charge control circuit for controlling the charging current I supplied to the battery to decrease until it reaches a predetermined lower limit temperature T2 is provided.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a battery charger, and an object thereof is to prevent a transformer from overheating during charging.

[0002]

[Prior art]

 The two-stage constant current charging method is an ideal charging method in terms of battery life and charging characteristics. This charging method is a charging method that performs strong charging with a relatively large current from the start of charging to the end of charging and weak charging with a small current from the end of charging to completion. Also, after changing the AC power supply to the required voltage and current values with a transformer, it is rectified and energized to the battery for charging.

[0003]

[Problems to be solved by the device]

 For example, when a battery installed in an electric wheelchair is charged with domestic power during the daytime in the summer, the transformer may generate heat and reach a high temperature, possibly exceeding the maximum allowable temperature and destroying the transformer.

[0004]

[Means for Solving the Problems]

 Therefore, in the present invention, in the battery charger for supplying the charging current (I) to the battery 3 by rectifying the current of the AC power source by the transformer 1 and then rectifying it by the rectifier circuit 2, the thermistor 4 is provided in the transformer 1. When the transformer temperature T 1 detected by the thermistor 4 reaches a predetermined upper limit temperature T1, the charging current I is reduced, and when it reaches a predetermined lower limit temperature T 2, the charging control circuit 5 is controlled to change the charging current I to the original charging current I again. It was provided to configure the battery charger.

[0005]

[Operation and effect of the device]

 Overheating of the transformer 1 occurs during strong charging in the two-step constant current charging method, but the detected temperature T of the thermistor 4 that detects the temperature of the transformer 1 reaches a predetermined upper limit temperature T1 that does not exceed the maximum allowable temperature of the transformer 1. When it reaches, the charging current I is reduced to suppress the amount of heat generation, and when the temperature T of the thermistor 4 reaches the predetermined lower limit temperature T2, the original charging current I for strong charging is restored and charging is performed. Therefore, the temperature that exceeds the maximum allowable temperature at which the transformer 1 is destroyed does not reach, and since the transformer 1 is charged with the low charging current I even while it is cooled, it takes a long time to complete the charging. It will never happen.

[0006]

【Example】

 As shown in FIG. 2, for example, the charging device of the present invention includes a transformer 1 connected to an AC power source 9 via a switch 8, a rectifier circuit 2 connected to the secondary side of the transformer 1, and an output of the rectifier circuit 2. A battery 3 connected in series to a terminal via a switching element 7, a chopping pulse circuit 6 for ON / OFF control of the switching element 7, a thermistor for detecting a terminal voltage measurement value V of the battery 3 and a coil temperature of the transformer 1. A charging control circuit 5 for controlling the chopping pulse circuit 6 by receiving the temperature T from 4 and processing as shown in FIG. 1 is provided. The charging current I is controlled by a two-stage constant current charging method in which a strong current is charged from the beginning until the end of charging is reached, and then a weak current is used for charging for a predetermined time. The switching to the weak charge is performed by sensing that the terminal voltage V of the battery has reached the end-of-charge voltage VE.

Next, as a specific example, the transformer 1 uses an E-type isolation transformer with a maximum allowable temperature of 120 ° C., and the battery 3 is a lead battery having a battery capacity of 35 Ah / 5HR and shows a control state. This will be described with reference to 1. The charging current I is 5 amps in the strong charging control, and 2 amps in the weak charging control. During the strong charge control, the battery terminal voltage V is read, and the strong charge control is continued until the terminal voltage V of the battery 2 reaches the end-of-charge voltage VE, but the temperature T of the transformer 1 detected by the thermistor 4 is detected. 5 ampere charging is continued until the temperature reaches the upper limit temperature (T1 = 110 ° C.), and when the upper limit temperature T1 is exceeded, the charging current I is reduced to 3 amperes, and the transformer temperature T becomes the lower limit temperature (T2 = 100 ° C.). C) When it becomes below, it returns to the strong charge control of 5 amps again. In this control, the state in which the current I is lowered, that is, whether the transformer temperature T is between the upper limit temperature T1 and the lower limit temperature T2 is determined by whether the flag F is 1.

The graph shown in FIG. 3 shows the relationship between the charging time and the transformer temperature T and the effective charging current I. When the control state of the present invention is reached at the end of the strong charging control (the ambient temperature is If high).

[Brief description of drawings]

FIG. 1 is a flow chart diagram.

FIG. 2 is a circuit diagram of a charging device.

FIG. 3 is a graph showing a charging progress state.

[Explanation of symbols]

 1 Transformer 2 Rectifier Circuit 3 Battery 4 Thermistor 5 Charge Control Circuit 9 AC Power Supply I Charging Current T Transformer Temperature T1 Upper Limit Temperature T2 Lower Limit Temperature

Claims (1)

[Scope of utility model registration request] 1. A transformer (1) for supplying a current of an AC power supply (9).
In the battery charging device for rectifying the voltage by the rectifying circuit (2) and supplying the charging current (I) to the battery (3), the thermistor (4) is provided in the transformer (1),
When the transformer temperature (T) detected by the thermistor (4) reaches a predetermined upper limit temperature (T1), the charging current (I) is lowered, and when it reaches a predetermined lower limit temperature (T2) thereafter, the original charging current (I) is returned again. ) A charging device for a battery, which is provided with a charging control circuit (5) for controlling to change the charging method to (5).