级联H桥型高压变频器中脉冲编解码技术研究

Research on Encoding/Decoding Techniques of Pulse Signals in Cascade H-bridge Converters

级联H桥型高压变频器在轧钢、冶金、矿井提升、机车牵引以及电力系统有源滤波和无功功率补偿等场合都得到了广泛的应用。在6 k V及以上的工业应用场合,采用级联H桥型技术方案构成的变频器在成本、可靠性、电压谐波质量等方面具有相当的竞争性。在级联H桥型变频器中,各H桥单元的电压处于浮动状态,出于高压隔离的目的,一般采用光纤传输驱动脉冲信号。由于变频器中H桥单元个数众多,驱动脉冲数量庞大,为减少光纤使用数量,降低系统成本,提高系统可靠性,采用一条光纤信号进行脉冲传输成为一种可行的技术方案。分析了对脉冲信号进行编解码的技术方案,并将其成功应用于一台6 k V,600 k W高压变频器中,实验结果验证了所提的脉冲编解码方案的正确性与可行性。

Cascade H-Bridge converters have been widely used in many industrial occasions such as steel rolling,metallurgy,mine hoisting,locomotive traction and power systems. In the occasions where the voltage is above 6 kV,cascaded H-bridge converters have many advantages because of the low cost,high reliability and low total harmonicdistortion（THD）. Fiber- optical is applied to transmit the pulse signals of the switches in the converter,which isnecessary because the ground of each H-bridge is floating. And since there are lots of pulse signals in the system,it ispractical to encode the signals firstly,and then transmit it by one fiber,which will decrease the number of the fibers,lower the cost and improve the reliability. The technique of how to encode and decode the pulse signals was analyzed,which is validated in a 6 kV/600 kW cascaded H-bridge converter.