Due to its low loss and high switching frequency, the silicon carbide metal oxide field effect transistors (SiC MOSFETs) are more suitable as switching devices in power inverter for electric vehicles (EVs). However, the power losses of power inverter would be dramatically increased with the rise of switching frequency, which would result in the limitation of using the high switching frequency performance of SiC MOSFET. In view of this case, this paper would systematically analyze the power losses distribution of power inverter and further optimize its efficiency under the high switching frequency. It is demonstrated that the power losses of power inverter are linearly increased with the rise of switching frequency, which is mainly caused by the switching losses of MOSFET chips increment. Based on this situation, an adaptive discontinuous pulse width modulation (ADPWM) is proposed to optimize the power inverter efficiency under the high switching frequency, which can effectively reduce the total power losses of power inverter and improve its efficiency compared with that of the conventional PWM strategies. Finally, the power losses and efficiency of power inverter with the proposed ADPWM strategy is verified by the experimental results.

The power loss is an important factor to be considered in the design stage of power inverter. However, there are a few literatures to systematically analyze the power losses of power inverter, especially for with Silicon Carbide Metallic Oxide semiconductor field effect transistors (SiC MOSFET). This paper investigates the power losses of power inverter based on SiC MOSFETs by considering various factors such as junction temperature, switching frequency, dead-time, PWM modulate mode, control strategies and operation conditions of motor. It can be founded that the total power losses of power inverter are linearly risen with the increase of switching frequency and are reached to the maximum value when the motor operates at the highest speed. From the perspective of power loss distribution of power inverter, the power losses of power inverter are mainly distributed in the power modules, and the power losses of SiC MOSFET chips in the power module account for more than 93.4% of the total power losses of power inverter. It has very important significance for the thermal design, reliability evaluation and parameters selection of power inverter.

Space vector pulse width modulation (SVPWM) is used in motor control because of its high dynamic response and flexible control. Maximum torque per ampere (MTPA) strategy has become the most commonly used choice for internal permanent magnet synchronous motor (IPMSM). However, complicated coordinate transformations are required in the usual SVPWM algorithm and the performance of the MTPA algorithm can be affected by the parameters variation. This paper proposes a voltage vector directional control (VVDC) method based on the MTPA strategy. The inverse Park transformation is avoided in the proposed control scheme. And the proposed algorithm not only is briefer and clearer in the sector judgment process but also has lesser calculation during the duty cycle generation. In order to realize the MTPA strategy, two voltage feedback closed loops are designed to compensate for the d -axis and q -axis currents. A simple and effective multi-parameter identification method is also presented to solve the parameters variation problem. The effectiveness of the proposed method is verified by simulation and experiments.

As a power hardware-in-the-loop (PHIL) technology, the power-stage motor emulator (ME) can be employed for the port characteristics emulation of motors. Meanwhile, the ripple current reproduction is one of the key technologies for achieving the high precision emulation of the port characteristics. Commonly, the high requirement for the hardware topology and the modulation strategy with rapid response and low harmonics are the main challenges. Aiming to obtain the precision ripple current, a ME scheme with dual-branch parallel topology is proposed in this paper, of which the equivalent switching frequency can be increased greatly by mean of interleaving switch. Furthermore, a new three-level space vector modulation strategy based on the idea of virtual transformation is presented. With the proposed strategy, the dual-branch parallel topology can be equivalently transformed into a specific three-phase three-level back-to-back topology. Finally, simulation and bench experiments have been conducted to validate the effectiveness of the proposed scheme. The results indicate that the proposed topology combined with the modulation strategy has a superior performance in improving the ripple current tracking accuracy of ME. Moreover, the proposed method can provide an excellent insight into improving the emulation accuracy of motor characteristics in practical applications.