Ikuo Yasuoka

Improvement of re-adhesion for commuter trains with vector control traction inverter

The authors developed a re-adhesion control algorithm for a traction inverter system with vector control for commuter train applications. The re-adhesion algorithm consists of creep control, estimated traction force control, oscillation suppression control and all wheel slip suppression control. As the result of the running tests with new control, the adhesion performance was improved by more than 20% and passenger comfort was greatly improved, regardless of the conditions of the rail, gradient and kind of rolling stock.

Application of speed sensorless control to railway traction field

We have developed a novel drive system without using speed sensors in the railway traction field. In this time, we carried out some running tests in the field using an actual train to verify the total stability and performance of the proposed system. Especially, these experiments were executed under 4 induction motors driven in parallel by only one VVVF inverter. It is concluded that the proposed system was so stable in all speed regions including wide flux weakening region using 1 pulse mode, and its adhesion control performance was almost at the same level as the conventional drive system.

The proposal of wheel slip control method with peak point search and the test result

A novel anti-slip control method to seek the peak point of the tangential force between wheel and rail is proposed in this paper. The validity is verified with Real Time Simulator to simulate the various commands/feedbacks to/from a traction inverter and an induction motor. The validity is also verified on the actual electric locomotive with 6 traction inverters and 6 induction motors that the maximum tangential force is obtained with the proposed method.

Inverter circuit with the regenerative passive snubber

This paper presents an inverter circuit using a snubber circuit to achieve soft switching. This snubber circuit has a transformer-based energy regenerative circuit. This circuit has no additional switching device, and the cost is low. In this paper, this circuit was examined and evaluated by single shot test and PWM drive test. By single shot test, turn-on and turn-off waveforms were measured and we verified that the loss of the switching devices was decreased. Moreover by PWM drive test, the temperature under switching devices with snubber was lower than that of snubberless main circuit. Calculating the loss from the temperature, we verified that the total loss of the switching devices decreased to 72%. This decrease of the switching loss will make it possible to raise switching frequency. Therefore, we can reduce the weight of the filter reactor

Development of Power Unit for the Train Drive System using Low Loss IGBT

In this paper, we have shown the concepts behind designing an inverter power unit for train applications. We have also discussed about low-loss power units by using trench structure low-loss IGBT and compared it with planar structure IGBT. Also by using power unit with low-loss IGBT and performing temperature simulation and data measured from test runs, we were able to confirm on the effect of low-loss IGBTs. To conclude, we have shown the possibility and expectation that the use of low-loss IGBT will lead to smaller cooling devices, increase in output current, and the use of higher frequencies in PWM carrier which would all lead to improvements on the main circuit converter unit.

Locomotives harmonic compensation by SiC auxiliary converter with active filter function

This paper presents a method of active filter applied to auxiliary four- quadrant converter of electric locomotive or high speed train. In this technique, auxiliary power supply system is designed to generate an inverse harmonic current at AC side to produce the high frequency compensating current. So the auxiliary four- quadrant converter should operate at a high speed with the application of SiC devices. The results and effectiveness of the scheme is verified by simulation.

Study of EMI for Direct Drive Motor system in railway traction

We had developed a high efficiency motor drive system, that is, Direct Drive Motor (DDM) system in railway traction. However the wheel shaft voltage induced EMI problem. To solve this, we executed several tests and analysis, and it was concluded that the normal mode current of motor caused the wheel shaft voltage. Only the normal mode filter suppresses the wheel shaft voltage effectively. In this paper, we will explain about this new EMI mode particular to the DDM structure.