The Design Of Charge-Pump Used For Bypass Switch

Because the modern demand of the greener, more energy-efficient products continues to increase, the using of solar energy has been more attention. The solar energy projects especially the distributed PV projects applications is becoming increasingly widespread. Bypass switch can be used in solar photovoltaic cells. The photovoltaic panel is impacted for the using of the environment, some batteries cell may be under load-state because the photovoltaic panels is obscured, at this time the bypass switch can be split the current which generated by other batteries cell, avoid breakdown or burning the load-state cell because the current flowing through the load-state cell directly and generated the overvoltage.This paper presents a Charge-Pump circuit which used for a new bypass switch. This new bypass switch is different from traditional bypass switch, it is consists of three parts, the Charge-Pump circuit, the VDMOS and the small ceramic capacitors. Several parts of the above can be achieved integrated package so it’s easy to use. Compared with the traditional Schottky diode which use as the bypass switch, it has a lower forward voltage drop, low leakage current, low power and long life, has a large advantage in application.The main works of this paper as follows:1. Describe the actual application environment about the new bypass switch which constituted of the Charge-Pump, give its particular topology, and focus description how it works. Through analysis its several major technical indicators such as the average voltage drop carefully, and derive their theoretical formula. Finally, according to the above points illustrate the advantage which compared to conventional Schottky diodes in photovoltaic applications.2. Design the Charge-Pump circuit in the 0.18μm CMOS technology platform. The Charge-Pump circuit consists of five sub-modules, namely: the basic charge pump unit, the oscillator, the voltage detector, the logic control unit and the drive unit. Use the EDA software Candence to simulation the whole circuit and each sub-module during the design process of the Charge-Pump circuit structure. Simulation results show that in a typical application environment(when current is 8 A), the voltage drop of this new bypass switch is 62 mV, is twenty percent below than the conventional Schottky diode, the leakage current about 9.7 μA, batter than the conventional Schottky diodes, the reverse voltage is 45.5 V, meet the needs of practical application, basic to meet the design specifications and design specifications.3. After the design of Charge-Pump circuit is complete, adjusting the design and optimize the circuit structure based on the characteristics of the process,finalize the layout. Make a good foundation for the follow work such as tapeout and test.