Abstract
6.5 kV level IGBT (Insulated Gate Bipolar Transistor) modules are widely applied in megawatt locomotive (MCUs) traction converters, to achieve an upper 3.5 kV DC link, which is beneficial for decreasing power losses and increasing the power density. Reverse Conducting IGBT (RC-IGBT) constructs the conventional IGBT function and freewheel diode function in a single chip, which has a greater flow ability in the same package volume. In the same cooling conditions, RC-IGBT allows for a higher operating temperature. In this paper, a mathematic model is developed, referring to the datasheets and measurement data, to study the 6.5 kV/1000 A RC-IGBT switching features. The relationship among the gate desaturated pulse, conducting losses, and recovery losses is discussed. Simulations and tests were carried out to consider the influence of total losses on the different amplitudes and durations of the desaturated pulse. The RC-IGBT traction converter system with gate pulse desaturated control is built, and the simulation and measurements show that the total losses of RC-IGBT with desaturated control decreased comparing to the RC-IGBT without desaturated control or conventional IGBT. Finally, a proportional small power platform is developed, and the test results prove the correction of the theory analysis.
Highlights
The traction converter system of a modern electric locomotive and high speed train (EMU) is a voltage type traction converter composed of a four-quadrant converter and PWM inverters
VCE IC ton + VCE IRM trr − VCE IRM rr ton. It can be seen from the above equation that the application of the desaturation pulse will result in a decrease in the reverse recovery current peak value and the recovery time tA, thereby achieving a corresponding reduction in the Reverse Conducting IGBT (RC-IGBT) turn-on loss
The total loss of the RC-IGBT in RCDC control is reduced by 5% compared to that of the conventional IGBT
Summary
The traction converter system of a modern electric locomotive and high speed train (EMU) is a voltage type traction converter composed of a four-quadrant converter and PWM inverters. 6500 V IGBTs to achieve a 3600 V intermediate DC voltage in the two-level converter circuit, and the selection of devices is narrow [6,7,8,9]. Reference [23] shows a 6.5 kV RC-IGBT being applied to the method of the pulse control and the loss analysis of traction converters. It does not study the optimization of the desaturation pulse time, but instead selects a compromise time according to the manufacturer or its system. Reference [9] describes a double pulse test performed for various 6.5 kV RC-IGBT desaturation schemes, and compares the loss characteristics, but the study lacks quantitative analysis and optimization. A specific application of the environmental parameters of the experimental analysis and loss calculation is performed to verify the effectiveness of the strategy of RC-IGBT desaturation control to reduce the loss
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