| Ni-MH battery is a new kind of rechargeable battery with high energy rate, light weight and excellent temperature characteristics. It is called green battery because of less pollution than traditional batteries such as lead-acid battery and Ni-Cd battery. The expanding number of battery powered products has widely increased the use of sealed Ni-MH batteries.This thesis is to design a fuzzy-controlled rapid battery charger which is based on the chip 89C51. This system is fulfilled through monitoring Ni-MH battery voltage and temperature, which were analysed by the chip 89C51. To control DC output of the BUCK circuit, selecting the proper PWM pulse for driving the gate of MOSFET. Different DC output applies to different charge -current. Power MOSFET switches are supplied by the pulses from the chip TL494 .The pulse duty is controlled by 89C51 and DAC0832.This system uses the different-step current with intelligent fuzzy-control algorithm to charge battery. This method can choose the proper charger-current according with the state of battery to guarantee the battery be charged safely.According to experimental results, in the same condition of battery, the charge way that the thesis designed can achieve the goal of shorting the charge time and correct the temperature increased phenomenon, which is compared with the constant-voltage charge and constant-current charge. On the other hand, according to experimental results , the charger can provide different current in the different condition of battery escaped high current charging to damage battery. |
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