Control of a high power PWM current source rectifier

This paper describes the design of a digital control for PWM current source rectifiers (CSRs) in the range of 1 - 10MVA. A cascaded control structure is proposed: the inner loop controls the grid currents and the outer loop controls the dc-link current. The proposed grid-current control combines sta...

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Bibliographic Details
Main Authors: Richter, Sebastian A, Bader, Benjamin, De Doncker, Rik W
Format: Conference Proceeding
Language:English
Subjects:
Damping
Digital control
Error correction
Pulse width modulation
Rectifiers
Robust control
Servomechanisms
State feedback
Steady-state
Voltage
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Summary:This paper describes the design of a digital control for PWM current source rectifiers (CSRs) in the range of 1 - 10MVA. A cascaded control structure is proposed: the inner loop controls the grid currents and the outer loop controls the dc-link current. The proposed grid-current control combines state feedback for active damping of the LC-filter with a servo compensator to increase robustness and guarantee zero steady-state error. It is implemented in the stationary reference frame, which avoids cross coupling as introduced by rotating reference frame transformation. The servo compensator contains a digital resonator and an integrator that eliminates offset currents. It is efficiently implemented as digital filter. The time varying reference for the instantaneous grid current is generated by a disturbance observer for grid voltage. This closed-loop technique inherently compensates the voltage drop across the filter inductance. DC-link current is controlled by a PI-controller. The power factor of the CSR is dynamically adjustable. The proposed control design is verified using a CSR prototype with 11 kVA rated output power. Experimental results are given.
DOI:10.1109/IPEC.2010.5543477