Search

The open-winding permanent magnet synchronous motor (OWPMSM) system is a novel high-cost system that uses dual-inverters to control both sides of the stator to improve the performance of the motor. To save the system cost, the three-phase four-switch open-winding permanent magnet synchronous motor (TPFS-OWPMSM) system is proposed to replace the general three-phase six-switch OWPMSM system, but it brings the problem of bridge arm capacitor voltage offset. To solve the instability problem caused by capacitance, this paper carries out the state analysis and offset source analysis of the inverter capacitor voltage, and proposes a dual-inverters capacitor voltage balance control strategy. The capacitor balance control converts unstable capacitor offset voltage into current and injects the currents into the stator current loop through closed-loop correction. And this strategy includes the optimal control of different capacitors under dual-inverters with the goal of system stability. The effectiveness of the balancing strategy is verified by the simulation of various motor working conditions. [ABSTRACT FROM AUTHOR]

Featured Application: First, this article proposes a topology of a secondary reconfigurable inverter. When the power semiconductor devices in the three-phase six-switch (TPSS) inverter is faulty, removing the faulty IGBT (Insulated Gate Bipolar Transistor), the remaining power switches and the DC side powers can be reconstructed as the three-phase four-switch (TPFS) structure. If another power switch in the reconfigured inverter is faulty, the reconfigured inverter can be reconfigured again. The fault-tolerant space is much larger than that of a traditional inverter. Second, this article proposes a switch-pulse-resetting algorithm. The general control strategy connects the constant-voltage, constant-frequency control with the switch pulse resetting algorithm. It need not change the control algorithm when the proposed reconfigurable inverter transforms the normal running state into the faulty running state. This article proposes a topology of the secondary reconfigurable inverter and the corresponding fault-tolerant control strategy. When the secondary reconfigurable inverter is operating normally, its topology structure is the TPSS circuit. When the power semiconductor devices in the inverter are faulty, the inverter circuit needs to be reconfigured. After removing the faulty power semiconductor devices, the remaining power semiconductor devices and the DC side powers are reconstructed as the TPFS structure to keep the system running normally. This article also proposes a switch-pulse-resetting algorithm. This paper adopts the control strategy connecting the constant-voltage, constant-frequency control method with the switch pulse resetting algorithm. It need not change the control algorithm when the proposed reconfigurable inverter is transformed from the normal running state into the faulty running state. The inverter dependability is greatly improved. Finally, the feasibility and effectiveness of the proposed second reconfigurable inverter topology and control strategy are verified by simulation and experiment. [ABSTRACT FROM AUTHOR]

In order to solve problem of fault diagnosis of IGBT open-circuit of three-phase four-switch active power filter system, a fault diagnosis method of IGBT open-circuit based on voltage detection was put forward. This method only need to sample a line voltage signal, and combines with current and IGBT switching signals detected by system controllers, then it can quickly and accurately diagnose failure and determine the fault location. Meanwhile, the diagnosis method is suitable for IGBT open-circuit fault diagnosis of single tube and multi-ube. The simulation and experimental results verify the validity and reliability of the diagnosis method.

This article proposes a topology of the secondary reconfigurable inverter and the corresponding fault-tolerant control strategy. When the secondary reconfigurable inverter is operating normally, its topology structure is the TPSS circuit. When the power semiconductor devices in the inverter are faulty, the inverter circuit needs to be reconfigured. After removing the faulty power semiconductor devices, the remaining power semiconductor devices and the DC side powers are reconstructed as the TPFS structure to keep the system running normally. This article also proposes a switch-pulse-resetting algorithm. This paper adopts the control strategy connecting the constant-voltage, constant-frequency control method with the switch pulse resetting algorithm. It need not change the control algorithm when the proposed reconfigurable inverter is transformed from the normal running state into the faulty running state. The inverter dependability is greatly improved. Finally, the feasibility and effectiveness of the proposed second reconfigurable inverter topology and control strategy are verified by simulation and experiment.

This paper proposes a model predictive direct power control scheme for nonredundant fault tolerant grid-connected bidirectional voltage source converter (BVSC) with balanced dc-link split capacitor voltage and high reliability. Based on the operation analysis of fault-tolerant BVSC with phase leg faults, a power predictive model of three-phase four-switch fault-tolerant topology in αβ coordinates is established, and the space voltage vectors with unbalanced dc-link split capacitor voltage are analyzed. According to the power predictive model and cost function, the optimal space voltage vector is selected to achieve a flexible, smooth transition between inverter and rectifier mode with direct power control. Pulse width modulation and phase locked loop are not required in the proposed method. The constraint of dc-link voltage constraint is designed for the cost function to achieve a central point of dc-link voltage offset suppression, which can reduce the risk of electrolytic capacitor failure for over-voltage operation. With the proposed control method, the converter can work continuously in both inverter mode and rectifier mode, even if phase leg faults occur. The simulation and experimental results show good steady-state and dynamic performance of the proposed control scheme to enhance the reliability of bidirectional power conversion. [ABSTRACT FROM AUTHOR]

This paper proposes a constant-frequency model predictive direct power control (CF-MPDPC) method for a fault-tolerant bidirectional voltage-source converter (BVSC). The method can enhance the reliability and fault-tolerant operation capability of BVSCs in the condition of bridge-arm fault. Through the analysis of a fault-tolerant three-phase four-switch (TPFS) structure and the voltage vectors in the αβ stationary frame, the predictive power model and DC-link midpoint voltage offset suppression are established. According to model-predictive theory, fault-tolerant TPFS, and multivector control, the CF-MPDPC method for fault-tolerant BVSC is presented. The method realizes direct power control based on three output vectors with constant frequency, which can track the optimal vector more accurately and reduce current harmonics. Furthermore, the balanced control of DC-link capacitor voltages is also achieved by adding the term of DC-link midpoint voltage offset into the cost function. The balanced capacitor voltages protect the converter against the second faults caused by over-voltage operation of electrolytic capacitor. The simulation and experimental results prove that the fault-tolerant BVSC controlled by proposed method can maintain the continuous operation when the switching devices have fault. Low current harmonic content and stable output power exhibit good reliability and dynamic performance of the proposed CF-MPDPC for a fault-tolerant BVSC with a phase fault.

This paper proposes a constant-frequency model predictive direct power control (CF-MPDPC) method for a fault-tolerant bidirectional voltage-source converter (BVSC). The method can enhance the reliability and fault-tolerant operation capability of BVSCs in the condition of bridge-arm fault. Through the analysis of a fault-tolerant three-phase four-switch (TPFS) structure and the voltage vectors in the αβ stationary frame, the predictive power model and DC-link midpoint voltage offset suppression are established. According to model-predictive theory, fault-tolerant TPFS, and multivector control, the CF-MPDPC method for fault-tolerant BVSC is presented. The method realizes direct power control based on three output vectors with constant frequency, which can track the optimal vector more accurately and reduce current harmonics. Furthermore, the balanced control of DC-link capacitor voltages is also achieved by adding the term of DC-link midpoint voltage offset into the cost function. The balanced capacitor voltages protect the converter against the second faults caused by over-voltage operation of electrolytic capacitor. The simulation and experimental results prove that the fault-tolerant BVSC controlled by proposed method can maintain the continuous operation when the switching devices have fault. Low current harmonic content and stable output power exhibit good reliability and dynamic performance of the proposed CF-MPDPC for a fault-tolerant BVSC with a phase fault. [ABSTRACT FROM AUTHOR]