This paper proposes an adaptive super-twisting algorithm based sliding-mode observer (STA-SMO) for surface-mounted permanent magnet synchronous machine (PMSM) sensorless control, in which voltage source inverter (VSI) nonlinearity is taken into consideration. An adaptive algorithm for online tuning the sliding-mode coefficients of STA-SMO is proposed based on the existing stable conditions. Thus, position estimation error can be reduced by the proposed adaptive algorithm in wide-speed range. Furthermore, voltage distortion due to VSI nonlinearity is online compensated to improve the accuracy of PMSM model. Because mismatch between reference and actual voltage due to VSI nonlinearity may bring large rotor position and speed estimation error, especially in low-speed range where distorted voltages may become dominant compared to actual voltages. Thus, a STA-SMO with adaptive sliding-mode coefficients and accurate voltage value could be obtained. Finally, the effectiveness of the proposed adaptive STA-SMO with online VSI nonlinearity compensation is verified on a surface-mounted PMSM by experiments.

This paper proposes a modular multilevel converter (MMC)-based switched reluctance motor (SRM) drive with decentralized battery energy storage system (BESS) for hybrid electric vehicle (HEV) applications. In the proposed drive, a battery cell and a half-bridge converter is connected as a submodule (SM), and multiple SMs are connected together for the MMC. The modular full-bridge converter is employed to drive the motor. Flexible charging and discharging functions for each SM are obtained by controlling switches in SMs. Multiple working modes and functions are achieved. Compared to conventional and existing SRM drives, there are several advantages for the proposed topology. A lower dc bus voltage can be flexibly achieved by selecting SM operation states, which can dramatically reduce the voltage stress on the switches. Multilevel phase voltage is obtained to improve the torque capability. Battery state-of-charge (SOC) balance can be achieved by independently controlling each SM. Flexible fault-tolerance ability for battery cells is equipped. The battery can be flexibly charged in both running and standstill conditions. Furthermore, completely modular structure is achieved by using standard half-bridge modules, which is beneficial for market mass production. Experiments carried out on a three-phase 12/8 SRM confirm the effectiveness of the proposed SRM drive.

This paper presents a technical overview for fault diagnosis and fault-tolerant strategies of switched reluctance machine (SRM) systems. With the widespread utilization of electrical motors, stability and reliability become the most important considerations for safety. SRMs are famous for their great robustness, wide speed range, and high fault-tolerant capability, which are much suitable for high-speed and safety-critical applications. Although the SRM drive have some fault tolerance ability, the fault still seriously affects the system performance. The faults happening in different parts, such as converter, motor winding, sensors, and rotor, may lead to low torque, large torque ripple, overcurrent, insulation damage, and even system broken-down, without any fault-tolerant consideration. Therefore, it is important and urgent to improve the motor system reliability and robustness for SRM drives. Aiming at offering novel solutions to the faults in SRM drives, this paper begins with mathematical modeling of the SRM, and then concentrates on the state-of-art fault diagnosis and fault tolerance techniques to enhance the fault ride-through ability. Two categories, containing fault diagnosis and fault tolerance technologies are emphasized for fast faults locating and stable post-fault operation. Advanced technologies are reviewed, classified, and compared comprehensively. Besides, several fault diagnosis and tolerance schemes that have been developed by authors are presented and discussed as well. Finally, the research status and outlooks on this topic are put forward. It is our target to offer a global vision on fault-related strategies and bring out promising ideas about fault-related techniques in SRM drives.

This article presents an improved lumped parameter thermal network (LPTN) based online temperature prediction method of permanent magnet (PM) machines by global parameter identification. The proposed global parameter identification incorporates not only the loss but also the magnetic information into a fifth-order LPTN and identifies the multiphysical magneto-thermal parameters as a whole. In the identification process, the nonlinear characteristics, including the magnetic saturation, the cross-saturation, the strand skin effect, and the speed-dependent convective heat transfer, are all considered. It can eliminate the cumbersome magnetic and loss measurement efforts and improve the overall identification accuracy compared with the traditional step by step identification method. Based on the identified multiphysical magneto-thermal model, the critical temperatures of the PM machines, together with the online losses and torque, can then be predicted in real time. The experimental results show that the proposed online temperature prediction method can track the real temperature variation with errors within 5 °C.

Hybrid electric bus (HEB) presents an emerging solution to exhaust gas emissions in urban transport. This paper proposes a multiport bidirectional switched reluctance motor (SRM) drive for solar-assisted HEB (SHEB) powertrain, which not only improves the motoring performance, but also achieves flexible charging functions. To extend the driving miles and achieve self-charging ability, photovoltaic (PV) panels are installed on the bus to decrease the reliance on fuels/batteries and charging stations. A bidirectional front-end circuit with a PV-fed circuit is designed to integrate electrical components into one converter. Six driving and five charging modes are achieved. The dc voltage is boosted by the battery in generator control unit (GCU) driving mode and by the charge capacitor in battery driving mode, where the torque capability is improved. Usually, an extra dc-dc converter is needed to achieve battery charging. In this paper, the battery can be directly charged by the demagnetization current in GCU or PV driving mode, and can be quickly charged by the PV panels and GCU/AC grids at SHEB standstill condition, by utilizing the traction motor windings and converter circuit, without external charging converters. Experiments on a three-phase 12/8 SRM confirm the effectiveness of the proposed drive and control scheme.

A bearingless synchronous motor (BLSM) is a special type of electric machine that integrates the functions of traditional synchronous motors and magnetic bearings. It not only has the advantages of magnetic bearings, such as no friction, pollution-free, and maintenance-free, but it also realizes the high integration and system simplification. Therefore, the BLSM is becoming increasingly attractive in applications such as rotating stages, compressors, artificial hearts, and centrifugal pumps. This article provides a comprehensive review of the BLSM topologies after a brief introduction to the basic suspension force generation principles and the typical BLSM mathematical models. The recent BLSM topologies are classified based on the features of the suspension force generation principle. Moreover, the advantages and disadvantages of each BLSM type are discussed and compared in detail. Future potential BLSM applications in aircraft, aerospace, and flywheel energy storage systems are discussed after a short description of the BLSM application status. Several potential topology development directions are presented based on the requirements of the potential application.