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This paper focuses on an analysis of technical requirements for the design of a permanent magnet type electric variable transmission (PM-EVT), which is a novel series-parallel hybrid electric vehicle (HEV) powertrain concept. Similar to the planetary gear train used in the Toyota Prius II, the EVT also realizes the power split function. However, it is implemented in an electromagnetic way rather than in a mechanical way, as is the case for the Prius II with a planetary gear. In this paper, a procedure to define the technical requirements of an EVT is presented. Since the Toyota Prius II is a well-known series-parallel HEV, this vehicle is chosen as a reference. The engine, the battery and other necessary components are kept as input data. A dynamic simulation was performed in order to take into account different driving cycles. Then, based on an analysis of the simulation results (torque, speed and power) the technical requirements of the PM-EVT are defined. Finally, the PMEVT machine is designed. The PM-EVT design results are presented and validated using the finite element method. Author Keywords: Electric variable transmission , Permanent magnet machine , Planetary gear , Series-parallel HEV

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Theoretical analysis and experimental tests indicate that single-phase full-bridge Z-Source inverter, compared to its three-phase counterpart, suffers greatly from low-frequency output harmonic distortion due to the 2nd harmonic component of the current drawn by the inverter bridge from the DC side. Analytic relationship between low-frequency capacitor voltage and inductor current ripple factors and ZSource network parameters of single-phase Z-Source inverter under Simple Boost Control is derived in this paper. In addition, one novel Low-frequency Harmonics EliminationPulse Width Modulation technique is presented, which could greatly reduce low-frequency capacitor voltage ripple for given Z-Source network. The theoretical analyses and proposed modified pulse width modulation technique have been confirmed by computer simulation and laboratoryimplemented prototype.

To enhance the performance of hybrid electric vehicle and continuously variable transmission, and to achieve more varied operation modes, a novel breed of integrated electromechanical converter is presented, such as electrical variable transmission (EVT) and four-quadrant transducer. Synthesizing two electric machines, they are essentially electromagnetic theory-based converters with the function of speed, torque, and energy regulation. The feature of flexible and variable control makes them very suitable for use in automobiles, especially in hybrid electric vehicles, as a continuously variable transmission and integrated starter and generator. Furthermore, the operation of the internal combustion engine is optimized, and the reduction of fuel consumption and the improvement of vehicle performance are also achieved. Corresponding to different road loads and driver demands, several operating states and control strategies are possible. Based on a simplified structure, the mathematical model of the EVT has been built, and its power flow and control strategies under different operation modes, are also analyzed.Index Terms-Continuously variable transmission, control strategy, electric machine, hybrid electric vehicle, starter and generator.

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In order to not change the space vector pulse width modulation (SVPWM) control strategy during one phase fault, the five-phase six-bridge arm SVPWM fault tolerant control method for fifteen-phase permanent magnet synchronous motor (PMSM) is proposed in this paper, and the thermal stress of fifteen-phase PMSM under different fault-tolerant operations is analyzed. Firstly, the control model of the fifteen-phase PMSM based on three dq axes is established, the generation mode of the SVPWM is analyzed, and the speed and current loop PI regulators of the control system are designed. Secondly, the fault-tolerant control principle of the five-phase six-bridge arm is analyzed and compared with the hysteresis control strategy of equal amplitude and minimum stator loss. Thirdly, the 3D model of the fifteen-phase PMSM is established, the steady-state temperature and the transient temperature rise considering operating conditions under different fault tolerant operations are analyzed, and corresponding temperature rise results of the stator armature windings are compared separately. Finally, the experimental platform is established, the phase current waveforms tested under load conditions confirm the theoretical analysis of five-phase six-bridge arms and hysteresis control, and the test results of steady-state and transient temperature rise confirm the correctness of the simulation prediction.