Dual Sequence Discrete-Time Voltage Controller for LC-Filtered Voltage Source Inverter

In this paper, a positive- and negative- sequence voltage controller is proposed in the discrete-time domain for voltage source inverters with output LC filter. The state-space voltage controller is designed based on the complex variable resonant control (CVRC) in the stationary reference frame. The dual-sequence voltage controller provides not only excellent reference tracking performance but also high load current disturbance rejection capability even under unbalanced load conditions. Moreover, the discrete-time voltage controller considers a resonance of LC filter and a digital delay of PWM inverter, which can be operated in the low switching frequency system. The proposed controller gains are derived by the dominant pole elimination method to improve the dynamic performance. The effectiveness of the proposed voltage controller is verified by experimental results.