Digital Control of Four-Quadrant PWM Rectifier for High Speed Railway Traction Converter

Nowadays, most of the electrical railway tractions, especially the high-speed tractions are using AC-DC-AC power driving system. The best choice for the AC-DC link is four-quadrant PWM rectifier, which can provide controllable DC link voltage and better power factor for the grid. In high power drive applications, the switch frequency of the power semiconductor device cannot be very high, usually less than 1000 Hz. This paper gives a digital control strategy of high power four-quadrant PWM rectifier for high speed railway traction at a low switching frequency using resonance controller for current loop, and carrier phase-shifting for the harmonic current elimination method at low switching frequency situation .