01-01-2013, 11:21 AM
Four-quadrant Zero-current-transition Converter-fed Dc Motor Drives for
Electric Propulsion
Four-quadrant Zero-current.pdf (Size: 864.12 KB / Downloads: 55)
Abstract
In this paper, a new four-quadrant (4Q) soft-switching converter for dc motor drives, namely the 4Q zero-currenttransition
(4Q-ZCT) converter, with the capabilities of 4Q power flow, and ZCT switching profile for dc motor
drives is proposed. It has some definite advantages over their hard-switching counterparts and other soft-switching
converters. Both the turn-on and turn-off losses of main switches are significantly reduced, while the auxiliary
switches can always operate with zero-current-switching (ZCS). It possesses the advantages of reduced switching
stresses, minimum voltage and current stresses as well as minimum circulating energy during both the motoring
and regenerating modes. It also offers simple circuit topology, minimum component count and low cost.
INTRODUCTION
Recently, a number of soft-switching techniques, providing
zero-voltage-switching (ZVS) or zero-currentswitching
(ZCS) condition, have been successfully developed
for switched-mode power supplies (SMPS)
[Canesin and Barbi, 1997; Chau, 1994; Mao et al., 1997;
Wei and Ioinovici, 1998; Zhang and Sen, 2003]. A general
assumption is that converters for SMPS can be directly
applied to dc motor drives. However, unlike
SMPS, dc motor drives, especially those used in electric
railways and battery-powered electric vehicles, desire
frequent regenerative braking. During braking, the
dc motor operates as a generator to convert kinetic energy
into electrical energy, and the converter must allow
for backward power flow to restore the electrical energy
to the power network or battery system. Thus, the
incorporation of soft-switching into regenerating braking
is particularly desirable for electric railways and
battery-powered electric vehicles.
PROPOSED 4Q-ZCT CONVERTER
Figure 3 shows the schematic diagram of the proposed
4Q-ZCT converter for dc motor drives. To achieve ZCS
operation, two resonant tanks are required. Firstly, a resonant
inductor La, resonant capacitor Ca, auxiliary switches
Sa and Sa' are added to allow for soft switching S1 and S4.
Secondly, resonant inductor Lb, resonant capacitor Cb,
auxiliary switches Sb and Sb' are added to allow for soft
switching S2 and S3. The dc motor can be considered to
be simultaneously fed by two 2Q-ZCT converters.
SIMULATION AND VERIFICATION
Different modes of operation of the proposed 4Q-ZCT
converter are PSpice-simulated. The corresponding results
are shown in Figures 16 to 19.
Figure 16 shows the simulated waveforms of the proposed
converter operating in the forward motoring mode.
Both Sa and Sb are switched together to allow soft switching
S1 and S2.
CONCLUSION
The principle of operation, characteristics, computer
simulation and experimental results of a novel 4Q-ZCT
converter for dc motor drives has been presented. It
possesses some definite advantages: both turn-on and
turn-off losses of main switches are significantly reduced,
the auxiliary switches can always achieve ZCS, while
the corresponding device voltage and current stresses
are kept minimum. Moreover, the proposed converter
provides reduced switching losses and stresses, minimum
voltage and current stresses, minimum circulating
energy, simple circuit topology and low cost, leading to
achieve high power density and high efficiency. Other
key features are the use of the same resonant tank for
both forward and backward power flows and the full
utilization of all diodes of the power switch packages,
thus minimizing the overall hardware count and cost.