This paper investigates a novel direct torque control (DTC) for a
sensorless interior permanent magnet synchronous motor (PMSM) based
on a sliding mode technique (SMC). The speed and position of the
interior PMSM are estimated online based on active flux concept. To
overcome the large ripple content associated with the direct torque, a
torque/flux sliding mode controller has been employed. Two integral
surface functions are used to construct the sliding mode controller
(SMC). The command voltage is estimated from the torque and flux
errors based on the two switching functions. The idea of total sliding
mode is used to eliminate the problem of reaching phase stability. The
space vector modulation (SVM) is combined with the sliding mode
controller to ensure minimum torque and flux ripples and provides high
resolution voltage control. The proposed scheme has the advantages of
simple implementation, and does not require an external signal injection.
In addition, it combines the merits of the direct torque control, sliding
mode controller, and space vector modulation beside the sensorless
control.
Simulation works are carried out to demonstrate the ability of the
proposed scheme at different operating conditions. The results confirm
the high performance of the proposed scheme at standstill, low and high
speeds including load disturbances and parameters variation.