Charger overview


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Charger overview

Now, with the watch, smart phone, telephone, television, DVD player, video recorder, mobile communication products and other common small household appliances widely used, charger will naturally become every family essential goods, can be recharged the use of nickel-cadmium battery has been reused. The role of the charger is to restore the discharge capacity of the battery after discharge. Charger variety, civil, industrial use; There are nickel-cadmium battery charger, also have lead-acid battery charger and so on.
Chargers generally work by turning alternating current into pulsating direct current, which changes in size but direction. Correct charging is one of the important conditions to ensure battery life and performance. Commonly used charging methods include constant current charging and constant voltage charging, or a combination of the two methods can be adopted, that is, improved constant voltage charging or current limiting constant voltage charging, which actually starts with constant current charging and ends with constant voltage charging.
Constant current charge is a charge in which the current is maintained at a constant value. Is a widely used charging method. The initial charge of the battery, the operation of the capacity of the battery check, the operation of traction battery charging and battery plate into charge, more use of constant current or phase constant current charge. The advantage of this method is that the charging current value can be determined according to the capacity of the battery, the charging amount can be calculated directly and the charging time can be determined. That is, in the charging process always maintain the charging current unchanged method. It has the following types:
(1) slipstream charging, maintaining the full charging state of the battery, is just a charging method that can offset the self-discharge of the battery. Such charging rate is harmless to the long-term charging of the fully charged battery, but the current is too small for the charging of the fully discharged battery.
(2) minimum charge: the charging current should be reduced to the minimum as far as possible on the premise that the battery with deep discharge can effectively restore the battery capacity.
(3) standard charging, using standard rate charging, charging time is 14 hours or overnight.
(4) high rate charging, charging the battery within 3 hours of the method, this charging method needs automatic control circuit, battery protection.
Before charging, adjust the voltage of the charger to a certain value according to the number of batteries in series. During the charging process, the voltage of the charger is always kept the same. The charging current starts to be very large. The voltage and time selected by common constant voltage charging methods are as follows:
(1) buffer charge, which is used to maintain the fully charged state of the battery and offset the self-discharge of the battery
Charging voltage: 1. 55V(per battery)
Time: long-term
(2) floating charging. The battery is connected with the load in parallel. On the one hand, the battery discharges the load and on the other hand, it accepts the charger for charging.
Charging voltage: 1. 35V(per battery)
Time: long-term
(3) constant voltage charging, charging the fully discharged battery.
Charging voltage: 1. 40-1. 42V(per battery)
Time: charge 80% battery capacity in 40 minutes and 120% battery capacity in 2 hours.
High charger voltage will cause serious overcharge of the battery, and low charger voltage will cause insufficient charge of the battery. To prevent excessive current at the beginning of charging, the improvement of constant voltage charging is called current limiting constant voltage charging.
Charging voltage: 1. 65V(highest for each battery)
Time gate 2 hours charge 120% battery capacity
General charger circuit is divided into direct charge and with overvoltage, undervoltage protection circuit, battery reverse protection circuit automatic charger. There are two forms of buck circuit: capacitor buck and transformer buck. Rectifying circuit has unidirectional half wave, full wave, bridge full wave rectifying, half controlled bridge rectifying and so on. Charging switch control circuit and protection circuit of various components are varied, have, field effect transistor, single junction transistor, darlington tube, SCR, high-power switch integrated circuit TWH8751, TWH8778, 555 time-base circuit, programmable control voltage regulator TL431, op-amp bistable comparator LM358 and charging control LZll0 application-specific integrated circuit, etc. Each charger has its own characteristics and USES different unit circuits.
The circuit structure of pulse charger consists of the following parts: circuit filter, primary rectification filter, PWM transform, secondary rectification filter, pulse circuit, charge and discharge circuit and feedback control. Compared with ordinary switching power circuit, this circuit has more pulse generation circuit and charging and discharging circuit. In order to improve the conversion efficiency of the circuit, PWM control adopts integrated control device specially developed by guizhong power. The pulse generation circuit adopts 555 time base circuit and decimal counter/frequency division circuit. DC/DC conversion part is the use of your generation power dedicated research and development of flyback circuit. In addition to the characteristics of PWM control itself, such as working in quasi-resonant mode, no load down frequency, dynamic self-power supply, no load power consumption low characteristics, are similar to the conventional flyback circuit.

| release time：2019.09.05 Source：

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Charger overview