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This paper presents a new design for general inverter using line voltage direct PWM technique. This new scheme is different from the conventional inverter basing on the SPWM technique. This new scheme doesn't using high frequency signal injection method to improve the DC voltage utility of inverter, so the algorithm is very simple contrast to the SPWM technique. The system is very clear and suitable for realization. The DC-link voltage utilization ratio of inverter is the highest. This paper designs a hardware platform using DSP. The debug of the hardware system have been done. Satisfactory experiment results have been presented.

The structure of Direct Torque Control system of induction motor is complex. Aiming at this issue, a new scheme of induction motor drive is proposed. This new control system doesnpsilat need the stator flux model, so the system is very simple. The detailed theory of the stator current vector orientation control is described. The core idea is controlling the angle between the stator current vector and the rotor flux vector. The system will obtain quick torque response by this way, which is different from the Direct Torque Control (DTC). The experiments of new torque control strategy have been done. Experiment results have confirmed that the control method based on stator current vector orientation is valid and feasible.