In this article, a minimum-copper-loss fault-tolerant control scheme is proposed for open-phase fault and open-switch fault of dual three-phase permanent magnet synchronous motor (DT-PMSM) drives. Both the winding configurations of isolated neutral points and connected neutral points are studied in this article. In conventional minimum-copper-loss fault-tolerant control schemes, the constraints of sinusoidal phase currents result in insufficient copper-loss reduction. Different from them, the current references with the theoretically lowest copper losses are first derived and applied for different fault cases of DT-PMSM drives without using any unnecessary constraints in the proposed fault-tolerant control scheme. Thus, all phase currents in the proposed minimum-copper-loss fault-tolerant control scheme are optimized to be nonsinusoidal waveforms. Besides, the copper losses are further reduced by fully utilizing the remaining healthy switch in the faulty inverter leg for the open-switch fault of DT-PMSM drives with the proposed scheme. It has been theoretically and experimentally proved that the proposed fault-tolerant control scheme can reduce copper losses than all existing fault-tolerant schemes for both open-phase fault and open-switch fault in typical two-level voltage-source-inverter-fed DT-PMSM drives.

The traditional fault-tolerant procedure usually comprises fault detection and fault tolerance. Fault detection is adopted to locate the specific fault, which increases the complexity and misdiagnosis risk of fault-tolerant systems. This article introduced an adaptive fault-tolerant control for open-phase faults and open-switch faults in dual three-phase permanent magnetic synchronous machine (PMSM) drives. The proposed fault-tolerant scheme is fulfilled by going through three operation states: healthy operation, transient xy open-loop faulty operation, and fault-tolerant operation. The angle of fault-tolerant reference currents on xy plane is obtained from the transient xy open-loop faulty operation. Unified fault-tolerant reference currents of open-circuit faults are built up by using the above reference angle. After the open-circuit faults occur, the unified fault-tolerant reference currents are directly applied to the drive system without fault localization. Experimental results demonstrate a very smooth switching capability of the developed adaptive fault-tolerant control from the faulty operation to the fault-tolerant operation without extra hardware.

This letter proposes a novel three-phase hybrid rectifier topology and control method for high power electrolytic hydrogen production application. It is composed of a primary rectifier, i.e., a six-pulse silicon controlled rectifier (SCR) and an auxiliary converter, including a pulsewidth modulation (PWM) voltage source converter and a phase-shift-full-bridge converter. SCR undertakes most of the power consumed by electrolysis cell, and the auxiliary converter can compensate dc current ripples and absorb ac current harmonics of primary rectifier simultaneously. Compared with high power PWM rectifier, the proposed hybrid rectifier can keep the main benefits of PWM rectifier, such as the low dc current ripple to realize improved efficiency of electrolytic hydrogen production and high grid current quality at ac side while significantly reducing the cost. The effectiveness of the proposed hybrid rectifier is verified by the simulation as well as experimental results.

To make full use of the advantages of dual three-phase PMSM (DTP-PMSM) and three-phase open-winding PMSM (OW-PMSM), this paper proposed a novel typology of motor drive which can switch between dual three-phase (DTP) structure and three-phase open-winding (OW) structure online. On this basis, the basic control and fault-tolerant control are studied to explore the superiority of the proposed typology. Under healthy conditions, no adjustment is required for the modulation method of the proposed control scheme when switching between DTP mode and OW mode. By using two bidirectional thyristors, smooth switching between the two modes can be guaranteed. Besides, the power weight of two inverters can be adjusted by changing the current ratio in DTP mode and changing the voltage ratio in OW mode. For the fault-tolerant control, when an open-phase fault occurs, DTP mode will be used to provide sufficient dimensions of current control and the fault-tolerant scheme can be realized through current compensation without changing the control framework. When an open-switch fault or short-switch fault occurs, OW mode will be adopted to guarantee symmetrical phase currents, and the remaining healthy switches in the faulty inverter are fully used to share the loss of the healthy inverter. The experiment has been conducted to prove the feasibility and superiority of the proposed typology and control scheme.

Conventional buck power factor correction (PFC) converter has the disadvantage of high harmonic currents, which limits its applications. In this paper, a buck type single-switch integrated PFC converter is presented and analyzed. It is composed of buck and flyback PFC converters by using only one active switch, which benefits from simple control. The buck and flyback PFC converters are input-parallel and output-parallel connected. With critical conduction mode (CRM) constant on time (COT) control, the effect of dead zone of buck input current is eliminated by flyback unit. Therefore, the input harmonic currents of the proposed converters can easily meet IEC61000-3-2 Class C limits. With the advantages of buck and flyback PFC converters, the proposed converter can achieve high efficiency and low total harmonic distortion (THD) in universal-input applications. Simplified steady-state analysis and design considerations are introduced in this paper. Finally, a 96W prototype with 94.5% peak efficiency is built to verify the analysis results.

This study proposed a universal model predictive control (MPC) strategy for dual inverters fed open-winding permanent magnet synchronous motor (OW-PMSM) drives where two isolated buses have arbitrary DC voltages. Diverse and unordered space vector distribution caused by different voltage ratios of DC buses that greatly increases the calculation burden for the conventional MPC algorithm is analyzed in detail. Based on this, a novel MPC strategy that is universally applicable to any voltage ratio is put forward, which could decrease the number of candidate vectors from 49 to less than 15 in every cycle. Although the computational burden is reduced, the output power quality is unaffected owing to the effective simplification of the vectors. Besides, an optimized switching algorithm is designed to adapt to the situation when the voltage ratio changes during the operation state. The experimental results are presented to verify the effectiveness of the proposed method.