Compact design of PWM inverter-mounted induction motor system

This paper describes a compact design and control method of a PWM inverter-mounted on an induction motor especially designed for reducing the size and weight considerably, which may be applied to the speed control systems for air conditioners, conveyors and textile mills, etc. As the inverter circuit is mounted on an induction motor in a housing, so a unified design for both inverter and induction motor is indispensable. To obtain higher power density without derating performances, a new mechanical configuration unifying the inverter circuit and motor is proposed. Also, through the use of the current minimization control method during V/f operation it is possible to reduce the size of the heat-sink related to the losses of the power circuit. By the proposed design method, a compact inverter-mounted induction motor system of 1 HP is built and its validity is verified through the experimental results