Constant Current Source Of Testing Supercapacitor

Supercapacitor is a novel energy storage component between batteries and electrostatic capacitors. It integrates the advantages, such as the high power density characterized by conventional electrostatic capacitor, the energy density characterized by battery, the fast charge-discharge performance, no pollution and the long life, thus the component is expected to be a novel green power source.This thesis is to design a supercapacitor charger-discharger which is composed of main circuit that is based on the BUCK convertor and control circuit that is based on the chip 89C51. This system is fulfilled through monitoring supercapacitor voltage, current 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 dutycycle is controlled by 89C51 and DAC0832. This system uses the different-step current with intelligent fuzzy-control algorithm to charge supercapacitor. This method can choose the proper charge current according with the state of supercapacitor to guarantee the supercapacitor safely.The system adopts constant current charge-discharge measurement, the measurement curves show linearity. According to experimental results, the charger can provide different condition of supercapacitor current to escape high current charging to damage supercapacitor through fuzzy-control.Several problems about anti-jamming on electromagnetic compatibility in the design of the hardware circuit and software of the charge-discharge equipment are discussed. It can prevent errors from jamming and can improve the security and stability of the system.