逆变器开关管变驱动电流技术研究

传统的逆变器驱动电路中,驱动电流是按开关管最大关断电流下的最高电压尖峰来设计且是固定的,但在最大关断电流以下的工作状态,关断电压尖峰较小,IGBT有较大的安全电压裕量,牺牲了器件效率。为此提出一种逆变器变驱动电流技术及电路。该电路的驱动关断电流随开关管关断电流的下降而上升,提高了开关管在全负载范围下的关断速度,降低了IGBT的关断损耗。设计的原则是,关断电压尖峰不会超过最大允许值,且调节是实时进行的。讨论了关断电压尖峰与关断电流、驱动电流和漏感之间的关系。在一个230 V DC输入/80 V AC交流输出/500 W额定负载的单相半桥逆变器上进行测试,结果表明采用所提驱动电路,额定负载下效率较传统驱动提升近0.7%,实现了驱动电路的优化。

Research on Changeable Driving-current Technology of Switches for Inverters

In the traditional inverter drive circuit, the driving current is designed according to the spike voltage as the power switch is turned off at the maximum value, and the value of current is fixed. However, under the working condition where the current is below its maximum turn-off value, the spike of turn-off voltage will be smaller, thus IGBT will have a larger voltage margin at the cost of the device''s efficiency. To solve this problem, a changeable drivingcurrent technology for inverters and the corresponding circuit are proposed. The turn-off current of the drive circuit increases with the decrease in the power switch''s turn-off current, thus improving the power switch''s turn-off speed under a full-load condition and reducing the turn-off loss of IGBT. The principle is that the spike of turn-off voltage will not exceed the maximum allowable value, while the regulation is conducted in real time. In addition, the relations of the spike of turn-off voltage versus turn-off current and the drive current versus leakage inductance are discussed. Finally, tests were conducted on a single-phase half-bridge converter with 230 V DC input voltage, 80 V AC output voltage, and 500 W rated load. Results show that using the proposed drive circuit, the converter''s efficiency under rated load rose by about 0.7% compared with that when using the traditional drive method.