Minimum hardware solution for implementing a complete control algorithm for voltage source rectifiers

Voltage source rectifiers (VSR) among other alternatives, offer several advantages over line-commutated rectifiers. Advantages include displacement power factor control, reduced line current harmonic distortion and AC four-quadrant operation can be obtained. On its DC side, a DC-link unidirectional voltage is obtained and bidirectional power transfer capability is possible by reversing the flow direction of the DC-link current. This paper presents the analysis and design procedure for a VSR with the complete control algorithm implemented with minimum hardware. For this goal, a DSP-controller TMS320F240 has been used. All the functions have been programmed in a DSP, digital current and voltage controllers, decoupling of axis, space vector modulation, phase locked loop (PLL) for the synchronization with utility, and the acquirement of the phase currents and output voltage. It has been programmed a complete mathematical model of the rectifier in the synchronous reference frame. The actual currents and output voltage are acquired through the on-chip A/D converters. A space vector modulation has been implemented by using the PWM unit, a PLL has been implemented by using a look-up table and two capture inputs. Experimental results from a 1.5 kW VSR are presented.