Power loss reduction of three-phase inverter in electric vehicle using variable switching frequency hybrid PWM

• Explain a method to manipulate the switching frequency and modulation strategy for reduced switching loss of traction inverters. • Suggest a method to vary the location of the clamping duration during discontinue modulation employment to align the motor peak current duration. • Validate the feasibility of the clamping duration adjustment in relation to the motor power factor. • The validity of the switching frequency and modulation strategy manipulation is verified over a wide torque and speed range. As the requirements for lower emissions and better fuel economy continues to grow, car manufacturers become increasingly interested in developing electric vehicles (EV's). The main requirements for EV include high efficiency for improved vehicle mileage and high reliability of its components. For power electronics, the two requirements can be achieved by lowering the power losses, since the reliability of power semiconductor devices is highly linked with the temperature which, in turn, depends on the power losses. The aim of this paper is to analyse the capability of the variable switching frequency hybrid pulse width modulation (VSF-HPWM) strategy for reducing the inverter power losses. In contrast to other PWM methods which only target the manipulation of one parameter (i.e., switching frequency or modulation strategy) for loss minimization, the VSF-HPWM target the manipulation of the two parameters together enabling higher loss reduction capability. The capability of the VSF-HPWM is analysed in comparison with the conventional space vector PWM as well as to other loss reduction PWM through MATLAB Simulink environment. The most important observation is that the VSF-HPWM is capable of increasing the efficiency of the traction inverter by 1-2 % compared to SVPWM during high speed and low torque operation, which is a typical operation condition in highway driving.