Improvement of a Three-Phase Z-Source Inverter Performance

In this paper a mathematical design and simulation model of a Z-source inverter (ZSI) is presented. Three pulse width modulation (PWM) techniques viz. simple boost control (SBC), constant boost control (CBC) and the maximum boost control (MBC), are developed and applied to the designed ZSI and the critical performance parameters are analyzed under each of these PWM switching techniques. These critical performance parameters include the boost factor (B), DC-link voltage (V
dc-link
), percentage of total harmonics distortion (%THD), modulation index (m) and the voltage stress across the IGBT/MOSFET switching components (V
stress-ratio
). A different topology, the Capacitor-Boosted Z-Source Inverter (CB-ZSI) is then proposed. This different architecture is formed by addition of two parallel capacitors C
p1
and C
p
2 across inductors L
1
and L2 respectively on a classical ZSI topology and has proven an improved performance when comparing the critical performance parameters of a CB-ZSI to those of a classical ZSI. The boost factor of CB-ZSI is increased by more than 56% at SBC technique, more than 25% at CBC technique and more than 14% at MBC technique on average. The voltage stress ratio across the switching devices of a CB-ZSI is reduced by more than 40% at MBC technique, more than 5% at CBC control and increased by 1.7% for MBC PWM control technique on average. %THD for CB-ZSI is reduced by more than 112% for SBC technique, more than 16.8% for CBC and increased by more than 24% for MBC technique on average.