Three-phase multi-level PWM rectifier multi-carrier discontinuous voltage modulation strategy

Multi-level PWM rectifier requires fewer semiconductor switches compared with its bidirectional multi-level converter counterpart. Though three-level (multi-level) PWM rectifiers are known for more than 10 years, no multi-level PWM rectifier carrier based voltage modulation strategies were reported so far. After multi-level PWM rectifier topologies introduction and classification, the paper presents a three-phase multi-level PWM rectifier phase shifted multi-carrier voltage modulation strategy based on appropriate discontinuous voltage commands transformation. Suggested formalism naturally allows derivation of a multi-level PWM rectifier voltage amplitude (modulation index) vs. voltage-current phase angle operation envelope without making use of space vector calculus. PWM rectifier operation envelope becomes less restrictive with levels count increase and full utilization. Suggested approach is not limited to a three-phase case and is applicable to a general multi-phase case.