JPH0511748U - Constant current charging circuit loop - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a constant current battery charging circuit. [Constitution] The constant current charging circuit is formed by a rectifying bridge, an interconnection filter circuit, a feedback amplification circuit, a pulse width modulation and switch control circuit, and a differential amplifier. The charge signal is fed back to the separated comparison amplifier circuit by the feedback amplifier circuit to change the output operating frequency pulse width size of the pulse width modulation and switch control circuit, and the charging voltage to achieve the efficiency of battery current charging. It feeds back the operating frequency range of the controlled recycle output.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a constant current charging circuit, and more particularly to a charging circuit that feeds a charging signal back to a comparison and amplification circuit.

[0002]

[Prior art and problems]

 As is well known, various types of rechargeable batteries are commercially available. In these battery charging methods, when the charging voltage of the battery increases, the charging current decreases, and as a result, the maximum charging efficiency cannot be achieved, and the charging time must be lengthened to charge the battery voltage to the maximum value. I won't.

Therefore, there is a need for a charging means that solves the above problems and is applicable to all types of rechargeable batteries on the market.

[0004]

[Outline of the present invention]

 An object of the present invention is to provide a constant current charging circuit for fast charging a rechargeable battery.

Another object of the present invention is to provide a constant current charging circuit.

Yet another object of the present invention is to provide a configuration of a constant current charging circuit.

[0007]

【Example】

 FIG. 1 is a block diagram of a constant current battery charging circuit according to the present invention. This circuit includes a bridge rectifier filter circuit, a filter circuit, a feedback amplifier circuit, a pulse width modulation and switch control circuit, and a differential amplifier.

FIG. 2 is a detailed view of the constant current battery charging circuit of the present invention. The function of this circuit is described below.

The applied AC voltage of 110 V or 220 V is rectified by the rectifying diode D1 of the bridge circuit 1 and smoothed by the converter C1. A resistor R1 in parallel with capacitor C1 provides a discharge circuit for capacitor C1 and couples it to the secondary input terminal by the primary and secondary internal links of step-down transformer T1.

When this AC voltage is applied to this transformer through the bridge circuit 1 to give an operating voltage, the differential amplifier (ERROR AMP) OP2 of the comparison circuit 5 operates to detect the difference between the voltage at the input terminal and the reference voltage V _ref. The voltage is detected to control the pulse width modulation and duty cycle of the switching circuit 2, the conduction time of the transistor Q1 of the switching element is controlled, and the secondary output voltage of the transformer is changed to obtain a constant current.

During the on-duty of the duty cycle given by the reference voltage, the filter circuit 3 formed by the diode D2 and the filter capacitor rectifies the secondary voltage of the transformer T1 and the resistor R2 and the switch S1 connect the battery 6 to the battery 6. To charge. The battery total voltage detection device 7 is used to detect the state of the battery 6 during charging. When the charging potential reaches the charging voltage, the charging switch S1 is opened and charging is stopped.

When an external power source charges this battery, both ends of the resistor R2 are connected to the two input terminals of the operational amplifier OP1 via the resistors R3 and R4, and the resistors R3, R4, R5 and R6 and the operational amplifier OP1 are connected. Form the feedback amplifier circuit 4. The photodiode of the optocoupler OPTO1 in series with the current limiting resistor R7 is controlled by the signal output of the feedback amplifier circuit 4, the brightness of the photodiode changes, and therefore, the current transfer rate of the transistor is changed to make the differential. The voltage at the negative terminal of the amplifier OP2 is indirectly controlled, and the input terminal of the amplifier OP2 is compared by the comparator 5 with the reference voltage V _ref . Next, it controls the size of the circuit pulse of the pulse width modulation and switching control circuit and guides the current transfer rate of the switching control transistor Q1. Charging is performed in the operation period of the pulse width modulation and switching control circuit 2, and this is repeated until the battery to be charged is completely charged. When the battery 6 is fully charged, the pulse width modulation and switch control circuit shuts off.

[Brief description of drawings]

FIG. 1 is a block diagram of a constant current battery charging loop according to the present invention.

FIG. 2 is a detailed view of the block diagram of FIG.

[Explanation of symbols]

 1 bridge rectification circuit 2 pulse width modulation and switching circuit 3 filter circuit 4 feedback amplification circuit 5 comparison circuit 6 battery 7 battery full voltage detection device

Claims (1)

Claims for utility model registration: 1. A bridge rectifier circuit, a filter circuit connected to the rectifier circuit, a feedback amplifier circuit, a pulse width modulation and switching control circuit, and a differential amplifier.
Further, a constant current battery charging circuit which includes the following requirements: (a) The bridge rectifying circuit includes four rectifying diodes and a capacitor C as a smoothing element, and full-wave rectifies an AC input; ) The filter circuit is composed of a transformer T1, a rectifying diode D2 and a filter capacitor C2; (c) The feedback amplifier circuit is composed of a resistor and an operational amplifier OP1 and continuously detects and amplifies a battery charge signal. And outputs it to the separated optical coupler OPT01 to control the current transfer speed so as to change the voltage signal at the negative terminal of the differential amplifier OP2; (d) The separated optical coupler OPTO1 and the differential amplifier O2.
A comparator circuit formed from P2 and receiving an accurate detection signal from the feedback amplifier circuit and comparing it with a reference voltage to control the adjustment of the on-time duty cycle of the charging circuit; (e) the pulse width The modulation and switching circuit is composed of a pulse oscillator and a switch transistor Q1,
The duty cycle of the charging circuit is controlled according to the output of the comparison circuit; (f) formed by a control charging switch and a battery potential detecting device, detects the voltage state of the battery being charged, and charges the battery. A battery charge detection switch control device that turns off the charge switch when the end voltage is reached is provided.