dq-control of high-power current source rectifiers utilizing Selective Harmonic Elimination

Selective harmonic elimination (SHE) is usually the preferred modulation technique for high power converters. When such modulation is used with current source rectifiers (CSR), control of the DC-link current and of the input displacement power factor is typically achieved by adjusting the amplitude and phase of the CSR modulation index. In this paper control of an SHE modulated CSR is achieved by adjusting the d and q components of the modulation index in a frame synchronous with the input filter capacitor voltage. The DC-link current is regulated by closed loop control and regulation of the supply current reactive component is achieved with feedforward control. The proposed control scheme yields several advantages over traditional control strategies, such as inherently bidirectional power flow capability, smooth transition between motoring and regenerative braking, reduced cross-coupling between the two control schemes and the possibility of regulating the reactive component of the supply current. Results from a 160 kVA experimental rig are included in the paper.