ABSTRACT:
A Zero-Voltage-Switching (ZVS) sinusoidal pulse width
modulation (SPWM) method for three-phase four-wire inverter is proposed in
order to achieve higher efficiency and power density. With the proposed
modulation scheme, the ZVS operation of all switches including the main
switches and the auxiliary switch can be realized. Besides, all seven switches operate
at a fixed frequency. The ZVS SPWM scheme is introduced by considering the
various combinations of the polarities in three-phase filter inductors currents
and analysis of operating stages is presented. ZVS condition of the ZVS SPWM scheme
is derived and discussions of ZVS condition for typical three-phase loads are
also provided. In addition, the resonant parameters design and loss analysis
are briefly investigated. Finally the proposed ZVS SPWM scheme is verified on a
10 kW inverter prototype with SiC MOSFET devices.
KEYWORDS:
1.
Zero-Voltage-Switching
(ZVS)
2.
Sinusoidal
pulse width modulation (SPWM)
3.
Three-phase
four-wire inverter
SOFTWARE: MATLAB/SIMULINK
CIRCUIT DIAGRAM:
Fig.
1. ZVS three-phase four-wire inverter.
EXPECTED SIMULATION RESULTS:
(a) (b)
(c)
(d)
Fig.
2. Three-phase load voltages and filter inductors currents of the ZVS inverter
under balanced resistive load: (a) Three-phase load voltage, (b) load voltage
and filter inductor current of phase A, (c) load voltage and filter inductor
current of phase B, and (d) load voltage and filter inductor current of phase
C.
(a)
(b)
(c) (d)
Fig.
3. Three-phase load voltages and filter inductors currents of the ZVS inverter
under unbalanced resistive load: (a) Three-phase load voltage, (b) load voltage
and filter inductor current of phase A, (c) load voltage and filter inductor
current of phase B, and (d) load voltage and filter inductor current of phase C.
(a)
(b)
(c) (d)
Fig.
4. Three-phase load voltages and filter inductors currents of the ZVS inverter
under unbalanced inductive load: (a) Three-phase load voltage, (b) load voltage and filter inductor current of
phase A, (c) load voltage and filter inductor current of phase B, and (d) load
voltage and filter inductor current of phase C.
CONCLUSION:
A
ZVS SPWM method combining with aligned turn on gate signals and extra short
circuit stage is proposed for three-phase four-wire inverter. The generalized
ZVS condition of the ZVS SPWM scheme is derived and the discussions of ZVS
condition for some typical three-phase loads are provided. For balanced resistive
load, balanced inductive load and unbalanced resistive load, short circuit
stage is required. The short circuit stage may not be needed during several
intervals for some kinds of unbalanced inductive load. The estimated loss
analysis show that significant efficiency advantages can be obtained by ZVS three-phase
four-wire inverter at high switching frequency in comparison with the hard
switching three-phase four-wire inverter.
The ZVS turn-on of all switches, including the main
switches and auxiliary switch under both balanced and unbalanced resistive load
are achieved in the complete fundamental period with experimental verification.
Besides, the ZVS SPWM inverter shows significant efficiency advantage. The
measured highest conversion efficiency of the ZVS SPWM inverter is 98.3 % and
1.7 % higher than that of the hard switching inverter. At full load, the ZVS
SPWM inverter has 2.1 % higher efficiency than the hard switching inverter.
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