适用于变频控制类芯片的新型光电耦合隔离电路

New Optocoupler Isolation Circuit for Variable-frequency Control Chips

电力电子设备主回路与控制芯片间的电气隔离是保护芯片并阻隔干扰的常规手段。光电耦合器因其具有体积小、寿命长和输入输出间绝缘等优点,已成为实现主回路与控制芯片间隔离的主要选择。然而考虑到光电耦合器输出侧电流及寄生电容的不利影响,变频控制类芯片(如UBA2032等)通常采用变压器隔离主回路,这与电力电子设备高功率密度的发展趋势不符。深入研究以光电耦合器和变压器为核心器件的用于实现主回路与控制芯片间隔离的常规电路,分析指出采用光电耦合器隔离主回路与变频控制类芯片时存在的技术问题,提出一种可有效应对上述问题的新型光电耦合隔离电路并给出该电路参数的计算方法。仿真及实验结果验证了所提出的光电耦合隔离电路的优越性及有效性。

The galvanic isolation between the main circuit and control chip of the power electronic equipment is necessary to protect the control chip and reduce the interferences. With the following advantages such as small size,long life and the insulation between the input and output side,the optocoupler has become the most widely used component to isolate the main circuit and control chip. However,given the adverse effects of the current and parasitic capacitance on the optocoupler output,transformers are generally used in variable-frequency control chips（ such as UBA2032） to isolate the main circuits. That doesn＇t correspond with future development trends of high power density for power electronic equipment. The conventional circuits whose main circuit and control chip being isolated with the core components such as optocoupler and transformer are studied and analyzed in this paper. Technical difficulties of applying the optocoupler to isolate the main circuit and variable-frequency control chips were pointed out. To deal with the difficulties,a new optocoupler isolation circuit and the corresponding calculation method of the circuit parameters were proposed.Simulation and experimental results verified the superiority and effectiveness of the proposed isolation circuit.