# Research on the High Reliable Electromagnetic Stirring Power Supply
## 3 Results and Discussion  
### Simulation and Analysis  
In order to verify the correctness and effectiveness of the reconstructing main circuit topology and the control strategy of the high-reliability electromagnetic stirring power supply presented in this paper, the proposed topology is modeled on PSim and simulation experiments are performed. When the system is running normally, the simulation circuit model is shown in Figure 1. The grid voltage is 380 V, 50 Hz. The filter inductance on the grid side is 0.5 mH. The DC side capacitance value is 5000 \(\mu\)F. The DC side voltage is 800 V. The inverter output side filter is 1 mH. The equivalent inductance of the electromagnetic stirrer is 10 mH, and the equivalent resistance is 0.1 \(\Omega\). In the working process of the electromagnetic stirrer, it usually runs in three working states of forward rotation, stop, and reverse rotation. When the electromagnetic stirring power supply works normally, the output currents, DC side output voltage and the power factor of the electromagnetic stirring power supply are shown in Figure 7.  
Figure 6: Reset rules of fault-tolerant pulse. Figure 7: Simulation results under the normal operation of electromagnetic stirring power supply. (**a**) Output currents; (**b**) DC side voltage; (**c**) power factor. From the Figure 7, if the electromagnetic stirring power supply works normally, the output currents are good sine waves. The amplitudes of phase \(\alpha\) and phase \(\beta\) are same, and the phase angle is 90 degrees between the two phases. The amplitude of phase \(w\) is greater because there is no inductance. The DC side voltage is stable at 800 V. The power factor keeps the value 0.93. If the current system does not have the reconstruction topology shown in the yellow box in Figure 1, and the simulation results of the failures of the back-stage inverter are shown in Figure 8.  
Four different faulty conditions are done without the proposed reconstruction topology in the paper. The single switch V\({}_{1}\) faults at t = 0.7 s. The two switches V\({}_{1}\) and V\({}_{4}\) are at t = 0.5 s for the first fault and t = 2.5 s for the second fault, respectively. Both V\({}_{1}\) and V\({}_{2}\) in the same bridge are faulty at t = 0.5 s. Both V\({}_{1}\) and V\({}_{4}\) in the different bridge are faulty at t = 0.5 s. The output currents of the back-stage inverter cannot get the correct waveform in above faulty conditions. The system cannot work normally if the power system does not have the reconstruction topology. The proposed reconstructed topology of the system is shown in the yellow box in Figure 1. The simulation results in four different fault conditions with the proposed reconstructed topology are shown in Figure 9 for single faulty switch, Figure 10 for second fault, Figure 11 for two fault switches in the same bridge, and Figure 12 for two fault switches in different bridges. The single switch V\({}_{1}\) faults at t = 0.7 s in Figure 9. The switch V\({}_{1}\) is at t = 0.5 s for the first fault and switch V\({}_{4}\) at t = 2.5 s for the second fault, respectively, in Figure 10. Both V\({}_{1}\) and V\({}_{2}\) in the same bridge are faulty at t = 0.5 s in Figure 11. Both V\({}_{1}\) and V\({}_{4}\) in the different bridge are faulty at t = 0.5 s in Figure 12. The output currents of the back-stage inverter cannot get the correct waveform in above faulty conditions. It can be seen from these figures that different faults are diagnosed correctly. The output current waveforms can track the given current waveforms and can keep good shapes before and after the fault through transient vibration of about 0.01 s. The power factors can be maintained stable before and after the fault. All waveforms are almost the same as Figure 7.0 The waveforms of the DC side voltage in different faulty conditions are the same as Figure 7b, which are not shown here in order to avoid repetition. Figure 7.1 Output currents of electromagnetic stirring power supply without fault tolerance.