Search

Compared with the traditional control method, the direct torque control and direct force control method significantly reduces the torque ripple and the root-mean-square current of the phase winding in the single-winding bearingless switched reluctance motor. However, due to the unreasonable selection of voltage vectors and full cycle control, this method has some problems, such as too many control objects, excessive switching times, and low torque–ampere ratio. This article proposes an improved method for the abovementioned problems. First, the turn-on angle and conduction region of each phase winding are chosen as the control targets, and the operation principle is introduced accordingly. Second, according to the difference of the torque generated by the neighboring phases, the output torque can be distributed more properly to obtain the higher torque–ampere ratio in the commutation region. Finally, the sectors divided in the electrical space are reorganized and the corresponding voltage vectors are optimized. Experimental results show that the proposed method can secure lower torque ripples, fewer switching times, and copper loss. In addition, the torque–ampere ratio is improved as well. [ABSTRACT FROM AUTHOR]

Multiphase dc-excited Vernier reluctance machine (DC-VRM) exhibits the merits of robust structure, small torque ripple, and good fault-tolerant ability. Developing advanced sensorless drive methods can further promote its application in the safety-critical system. In this article, pulse injection sensorless drive methods are optimized in a six-phase DC-VRM parallel H-bridge drive system to strengthen their acceleration performance and fault-tolerant ability. The acceleration performance studied in this article corresponds to the acceleration speed during the startup stage. By the full-phase alternative pulse injection method (APIM), each phase can be excited independently to avoid mutual-inductance influence on position estimation, but this method suffers from a long communication delay and relatively poor acceleration performance. A reduced-phase APIM can reduce detection time, but the lack of detected phase may influence position estimation accuracy and fault-tolerant ability. To solve these problems, a novel vertical-axis synchronous pulse injection method is proposed and compared with previous methods in this article. The key is to inject detection pulses into vertical-axis phases simultaneously, thus reducing the detection time and improving the torque generation. It is proved that the influence of mutual inductance on position estimation can be ignored, and the detection accuracy and acceleration performance can be improved without deterioration of fault-tolerant ability. [ABSTRACT FROM AUTHOR]

High gradability and wide operating speed range are critical requirements for heavy-duty trucks and off-road electric vehicles. The motor power rating used for such applications can be reduced by selecting a motor with a wide constant power speed range (CPSR). However, permanent magnet synchronous motors (PMSMs) with wide CPSR have limited overloading capability. The operating speed range, as well as the overloading capability, can be improved by increasing the base speed of a low CPSR three-phase PMSM, which results in overdesign. Further, using multigear transmission to achieve a wide operating speed range with a low power motor increases system weight, drivetrain complexity, and maintenance requirement. This article proposes a dual three-phase interior PMSM with an unequal split winding configuration and zero degree winding displacement (uneq0-PMSM) to extend the constant power region and improve the overloading capability without any machine overdesign. The winding split ratio for the proposed configuration is decided to achieve the desired torque-speed characteristic shape for a given requirement. Further, a transition algorithm for smooth changeover between two-winding operation during low-speed and one-winding operation for high-speed is also proposed. The proposed concepts are experimentally validated on a 1.5-kW uneq0-PMSM with 1:3 winding split ratio. [ABSTRACT FROM AUTHOR]

This article studies the rotational movement and charging torque in a new reconfigured on-board charger during the charging process. Recently, the reconfigured on-board charger becomes attractive because the propulsive units are engaged in the charging system to reduce the cost and volume. Since the unbalanced currents flow through the three-phase permanent-magnet synchronous machine, the rotational movement and charging torque are generated. The charging torque may be equal to the rated propulsive torque at some special rotor positions, which is unsafe and may lead to the rotational movement, extra noise, and motor wear. In order to reduce the influence of charging torque and rotational movement during the charging process, the charging torque is analyzed based on the magnetic coenergy. It is found that the charging torque is related to the unbalanced current, differential-mode current, and current ripple in motor windings. Thus, the mutual inductances of motor windings during the charging process are decoupled into the differential-mode and common-mode inductances. Furthermore, a solution is provided to significantly minimize the charging torque based on the control methods of the ac/dc side and dc/dc side. Finally, the experimental results are provided to verify the correctness of the suppression of rotational movement and the charging performance. [ABSTRACT FROM AUTHOR]

This paper proposes a modular multilevel converter (MMC) based switched reluctance motor (SRM) drive with decentralized battery energy storage system for hybrid electric vehicle 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 balance can be achieved by independently controlling each SM. Flexible fault-tolerance ability for battery cells is equipped. The battery can be flexibly charged under both running and standstill conditions. Furthermore, a 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. [ABSTRACT FROM AUTHOR]

The 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 fuelsbatteries 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 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 GCUAC grids at SHEB standstill conditions, by utilizing the traction motor windings and integrated converter circuit, without external charging converters. Experiments on a three-phase 128 SRM confirm the effectiveness of the proposed drive and control scheme. [ABSTRACT FROM AUTHOR]

The mutually coupled dual three-phase switched reluctance motor (DTPSRM) is a new type of special 12/8 SRMs, which possesses high-reliability and fault-tolerant feature. In the past researches, the model, analysis, and fault-tolerant operation were mainly focused on the classical single three- and four-phase SRMs. This paper is mainly to analyze and investigate the fault-tolerant performances of a 12/8-pole mutually coupled DTPSRM drive under various open-circuit operations. First, the static magnetic characteristics of DTPSRM with single- and two-phase excitations are calculated by finite-element analysis. Then, the mathematic model of the DTPSRM drive under open-circuit condition is developed with a combination of state and fault functions. The simulation model of the DTPSRM drive system with a fault-tolerant control strategy is established for dynamic analysis. The faulty characteristics and fault-tolerant performances of the DTPSRM with diverse open circuits are predicted. Finally, a 12/8 DTPSRM is prototyped and an experimental setup is built for verification. The experimental normal results and diverse open-circuit operations and self-starting capability under lack of phases are presented, validating the accuracy of the analysis and simulation as well as fault-tolerant characteristics of the DTPSRM drive system. [ABSTRACT FROM AUTHOR]

Small variable speed drives intended for mass-market applications like hand-held power tools and household appliances have to be inexpensive and efficient. Doubly salient reluctance motors are known to be cheap and robust, but their use in such mass market applications has been hindered by the cost and limitations of their associated power converters. A new converter concept is proposed in this paper. The new converter has the ability to apply higher voltages across the machine windings than could be obtained with standard circuits to achieve high-speed operation. The demagnetization of the machine coils is load independent ensuring fast current decay and consequently a stable high-speed operation at higher loads. The fast rate of current decay allows a longer duration of positive torque pulses resulting in less pulsating torque. A detailed analysis of the proposed converter is presented and design guidelines are laid out. A 1-kW prototype converter is designed and constructed to experimentally validate the operation of the new circuit. [ABSTRACT FROM AUTHOR]

A bearingless switched-reluctance motor (BSRM) has a complicated nonlinear character; therefore, its control strategy is very important to a stable operation. This paper presents a new control strategy for rotating and levitating a 12/8 BSRM with two sets of windings. This strategy can enhance not only the availability of winding currents in producing the radial force to suspend a rotor, but also decrease the torque ripple and stator vibration. First, influences of different combinations of winding magnetomotive force on the radial suspension force and torque are analyzed, and the optimal combination of winding magnetomotive force is gained. Second, based on the optimal combination, the theoretical equations of winding currents are obtained. Consequently, this paper gives the flowchart to calculate the advanced angle and winding currents. Moreover, the torque ripple and stator vibration of BSRM in the new control strategy are analyzed. Finally, simulation model and control system of BSRM with 12/8 poles are designed. Dynamic simulation and experimental results proved the theoretic conclusions. [ABSTRACT FROM PUBLISHER]