Abstract
As high-capacity alternating current/direct current (ac/dc) power conversion systems, single-phase pulse-width modulation (PWM) converters used in high-speed railway propulsion systems adopt high-voltage Insulated-Gate Bipolar Transistors (IGBTs) as switching elements. Due to their high breakdown voltage characteristics, the switching dynamics are inferior to those of low-voltage IGBTs and switching losses are more dominant than conduction losses despite operating at relatively low switching frequencies of hundreds to several kHz. To solve this problem, this paper proposes ± 180° discontinuous PWM (DPWM) suitable for a single-phase circuit. With the simple addition of offset voltages, the proposed DPWM method can be implemented easily and switching losses can be reduced by half by clamping the switching legs of the H-bridge converter to the positive or negative dc rail during every half cycle. In addition, temperature deviation between the power stacks can be minimized by using selective application of clamping modes. The validity and effectiveness of the proposed DPWM are verified through simulations and experiments of a prototype converter.
Highlights
The number of personal vehicles globally has been increasing rapidly due to expeditious industrialization and urbanization, causing traffic congestion and environmental pollution
We propose an effective ± 180◦ discontinuous PWM (DPWM) that is simple to implement and reduces switching loss by 50% compared to the existing carrier-based sinusoidal pulse-width modulation (CB-SPWM)
A novel ± 180° DPWM is proposed to reduce switching losses of single‐phase converters used in high-speed railway (HSR) propulsion systems
Summary
The number of personal vehicles globally has been increasing rapidly due to expeditious industrialization and urbanization, causing traffic congestion and environmental pollution. Multi-level converters have the advantage of having a high-power quality at relatively low switching frequencies due to their natural step-wise voltage waveform as well as the use of low breakdown voltage devices, but there are issues of increased circuit complexity and troublesome voltage balancing control. The switching losses of power systems using simple two-level based high-voltage Si-IGBTs, such as HSR propulsion systems, should be reduced in different ways. An application of DPWM for a single-phase PWM converter has been reported [20] It can reduce switching losses by clamping the leg voltage for one third of a period, like the three-phase inverter, which has the advantage of distributed losses among switches and diodes.
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