Figure 4. Simulation diagram for three phases SRM.

Figure 5. Simulation diagram for proposed circuit.

the hysteresis band is chosen as ±10 A. The SRM is started by applying the step reference to the regulator input. The acceleration rate depends on the load characteristics. To shorten the starting time, a very light load was chosen. Since only the currents are controlled, the motor speed will increase according to the mechanical dynamics of the system. In current controlled mode, the average value of the developed torque is approximately proportional to the current reference. In addition to the torque ripple due to phase transitions, we note also the torque ripple created by the switching of the hysteresis regulator.

Comparative examination of the ordinary and proposed converter response are appeared in Figures 6-11 respectively. Figure 6 depicts the consequences of traditional converter at no load condition with turn ON angle

Figure 6. Traditional converter with Q_{ON} = 45˚, Q_{OFF} = 75˚, T_{L} = 0 NM.

Figure 7. Traditional converter with Q_{ON} = 45˚, Q_{OFF} = 75˚, T_{L} = 2.5 NM.

Figure 8. Traditional converter with Q_{ON} = 45˚, Q_{OFF} = 75˚, T_{L} = 5 N∙m.

Figure 9. Proposed converter with Q_{ON} = 45˚, Q_{OFF} =75˚, T_{L} = 0 N∙m.

45 degree and turn OFF angle 75 degree. It can be seen in Figure 6, the current overlap occurred between two successive phases. From the torque waveform we observe that the change in torque is 58 N×m and the mean torque is 21.66 N×m and the torque ripple is computed from the above data and torque ripple rate acquired as 2.688. Figure 7 depicts the consequences of traditional converter at T_{L} = 2.5 N×m. From the torque waveform we observe that change in torque is 57 N∙m and the average torque is 23.89 N∙m and the torque ripple is ascertained from the above data and torque ripple rate got as 2.396. Figure 8 depicts the consequences of traditional converter at T_{L} = 5 N∙m. From the torque waveform we observe that change in torque is 58 N∙m and the average torque is 26.79 N∙m and the torque ripple is ascertained from the above data and torque ripple rate acquired as 2.165. In proposed converter ,the presence of boost capacitor causes high demagnetisation voltage and also the fall time current get reduced to zero before the next phase is energised.

Figure 10. Proposed converter with Q_{ON} = 45˚, Q_{OFF} = 75˚, T_{L} = 2.5 N∙m.

Figure 11. Proposed converter with Q_{ON} = 45˚,Q_{OFF} = 75˚, T_{L} = 5 N∙m.

Figure 9 depicts the results of proposed converter at no load condition with turn ON angle 45 degree and turn OFF angle 75 degree. It can be seen in Figure 9, the current ovrlap get reduced. From the torque waveform we observe that change in torque is 66 N∙m and the average torque is 32.09 N∙m and the torque ripple is ascertained from the above data and torque ripple rate acquired as 2.056. Figure 10 shows the results of proposed converter at T_{L} = 2.5 N∙m. From the torque waveform we observe that change in torque is 70 N∙m and the average torque is 35.19 N∙m and the torque ripple is computed from the above data and torque ripplerate acquired as 1.932. Figure 11 depicts the results of proposed converter at T_{L} = 5 N∙m. From the torque waveform we observe that change in torque is 70 N∙m and the average torque is 38.22 N∙m and the torque ripple is computed from the above data and torque ripple rate got as 1.831. Table 1 depicts the comparison of traditional and proposed

Table 1. Comparison of traditional converter with proposed converter (switching angle Q_{ON} = 45˚, Q_{OFF} = 75˚).

A―load torque, B―change in torque, C―average torque, D―torque ripple.

converter at different switching angle. In proposed converter the current tracing effect is greater than ordinary converter. Henceforth dynamic performance is improved.

7. Conclusion

In this paper, a new front end capacitive switched reluctance motor drive has been introduced. This topology includes one boost capacitor and two diodes in addition to the traditional converter. The boost capacitor gives high magnetization and demagnetization voltage to the motor winding. The torque ripple is quite excessive and the current tracing effect is not very good for asymmetric converter. The proposed converter obtains faster excitation current during magnetization and quick demagnetization current for the duration of demagnetization period. So it will possibly also support current tracing effect, average torque, and reduce the torque ripple. It is well suited to electrical vehicle, electric traction and aerospace utility.

Cite this paper

S. Muthulakshmi,R. Dhanasekaran, (2016) A New Front End Capacitive Converter Fed Switched Reluctance Motor for Torque Ripple Minimization. *Circuits and Systems*,**07**,585-595. doi: 10.4236/cs.2016.75050

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