11-08-2012, 10:44 AM
Research on High Input Voltage DC-DC Converter with Low Voltage Stress on Switches
Input Voltage.pdf (Size: 56.21 KB / Downloads: 56)
ABSTRACT
This thesis presents research results on high input voltage DC-DC converter with low
switch stress. The voltage stress on the primary switches is only one-third of the input
voltage, so switches of low voltage rating and thus of low on-resistance can be used. This
leads to reduced conduction loss. By applying the asymmetrical duty cycle control of threephase
DC-DC converter, the converter achieves zero-voltage-switching (ZVS) for all the
switches, the switching loss can be reduced; And by using a novel phase shift pulse width
modulation (PWM) control, the converter achieves zero-voltage and zero-current switching
(ZVZCS), reduced the circulate energy loss during the freewheeling stage and increased the
soft switching range.
The contents of this thesis are as follows:
In Chapter 1, the need of using high frequency solutions in Medium Voltage (MV)
power conversion will be discussed. The existing topologies for high input voltage DC-DC
converter will be compared. The suitable application range for each topology will be
reviewed. Then, the need of a converter with six primary switches and each switch has the
voltage stress of one-third of input voltage will be discussed, followed by the proposed high
voltage three-phase DC-DC converter topology.
In Chapter 2, the operating principles of the proposed converter using asymmetrical
duty cycle control will be described. Different operating topologies will be discussed. The
steady-state voltages across capacitors will be analyzed. Also the input-to-output voltage
ratio and effective duty cycle will be studied and soft switching range will be evaluated.
Moreover the small-signal model will be given. The theoretical predictions will be verified
experimentally by a 5.1kWprototype with simplified design procedures .