16、t and an external power supply is disconnected the battery is to put the state to provide protection, the charge and protection rolled into one to make the circuit to simplify and reduce valuable product waste of resources. Figure 1 is a specific application of this Ic in the photovoltaic power gene 。

17、ration system, but also the source of this design.Maintenance-free lead-acid battery life is usually the cycle life and float life factors affecting the life of the battery charge rate, discharge rate, and float voltage. Some manufacturers said that if the overcharge protection circuit, the charging 。

18、 rate can be achieved even more than 2C (C is the rated capacity of the battery), battery manufacturers recommend charging rate of C/20 C/3. Battery voltage and temperature, the temperature is increased by 1 C, single cell battery voltage drops 4 mV, negative temperature coefficient of -4 mV / C mea 。

19、ns that the battery float voltage. Ordinary charger for the best working condition at 25 C;
charge less than the ambient temperature of 0 C;
at 45 C may shorten the battery life due to severe overcharge. To make the battery to extend the working life, have a certain understanding and analysis of the 。

20、 working status of the battery, in order to achieve the purpose of protection of the battery. Battery, there are four states: normal state, over-current state over the state of charge, over discharge state. However, due to the impact of the different discharge current over-capacity and lifetime of t 。

21、he battery is not the same, so the battery over discharge current detection should be treated separately. When the battery is charging the state a long time, would severely reduce the capacity of the battery and shorten battery life. When the battery is the time of discharge status exceeds the allot 。

22、ted time, the battery, the battery voltage is too low may not be able to recharge, making the battery life is lower.Based on the above, the charge on the life of maintenance-free lead-acid batteries have a significant impact, while the battery is always in good working condition, battery protection。

23、circuit must be able to detect the normal working condition of the battery and make the action the battery can never normal working state back to normal operation, in order to achieve the protection of the battery.3.Units modular design3.1The charging moduleChip, charging module block diagram shown。

24、in Figure 2. The circuitry includes current limiting, current sensing comparator, reference voltage source, under-voltage detection circuit, voltage sampling circuit and logic control circuit.The module contains a stand-alone limiting amplifier and voltage control circuit, it can control off-chip dr 。

25、ive, 20 30 mA, provided by the drive output current can directly drive an external series of adjustment tube, so as to adjust the charger output voltage and current . Voltage and current detection comparator detects the battery charge status, and control the state of the input signal of the logic ci 。

26、rcuit. When the battery voltage or current is too low, the charge to start the comparator control the charging. Appliances into the trickle charge state when the cut-off of the drive, the comparator can output about 20 mA into the trickle charge current. Thus, when the battery short-circuit or rever 。

27、se, the charger can only charge a small current, to avoid damage to the battery charging current is too large. This module constitutes a charging circuit charging process is divided into two charging status: high-current constant-current charge state, high-voltage charge status and low-voltage const 。

28、ant voltage floating state. The charging process from the constant current charging status, the constant charging current of the charger output in this state. And the charger continuously monitors the voltage across the battery pack, the battery power has been restored to 70% to 90% of the released。

29、capacity when the battery voltage reaches the switching voltage to charge conversion voltage Vsam charger moves to the state of charge. In this state, the charger output voltage is increased to overcharge pressure Voc is due to the charger output voltage remains constant, so the charging current is。

30、a continuous decline. Current down to charge and suspend the current Ioct, the battery capacity has reached 100% of rated capacity, the charger output voltage drops to a lower float voltage VF.3.2 Protection ModuleChip block diagram of the internal protection circuit shown in Figure 3. The circuit i 。

31、ncludes control logic circuit, sampling circuit, overcharge detection circuit, over-discharge detection comparator, overcurrent detection comparator, load short-circuit detection circuit, level-shifting circuit and reference circuit (BGR).This module constitutes a protection circuit shown in Figure。

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标题：外文|外文翻译光伏系统中蓄电池的充电保护IC电路设计( 三 )