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This paper proposes a compensation strategy for the unwanted disturbance voltage due to inverter nonlinearity. We employ an emerging learning technique called support vector regression (SVR). SVR constructs a motor dynamic voltage model by a linear combination of the current samples in real time. The model exhibits fast observer dynamics and robustness to observation noise. Then the disturbance voltage is estimated by subtracting the constructed voltage model from the current controller output. The proposed method compensates for all of the inverter nonlinearity factors at the same time. All the processes in estimating distortions are independent of the dead time and power device parameters. From the analysis of the effect on current measurement errors, we confirmed that the sampling error had little negative impact on the proposed estimation method. Experiments demonstrate the superiority of the proposed method in suppressing voltage distortions caused by inverter nonlinearity. Index Terms--Current :measurement errors, disturbance voltage resulting from inverter nonlinearity, power device parameters, support vector regression (SVR).

The optimal flux-searching algorithms of an induction machine have reached a stage of development permitting maximum torque operation over an entire flux-weakening region. In the high-speed region, however, the sensitivity to parameter errors of an induction machine still remains a problem. This paper presents an approach that ensures maximum torque operation maintaining robustness to parameter error in the flux-weakening region. To guarantee the performance in the high-speed region, the machine leakage inductance is adapted on line, based on the injection of sinusoidal current. Also, the detuned effect on machine inductance is thoroughly analyzed to relate the sensitivity of parameters to the performance of the flux-weakening region. Experimental results demonstrate that the proposed adaptation scheme effectively selects the optimal flux level regardless of variation of leakage inductance. Index Terms: Flux-weakening, induction machine.

In the overmodulation region, the operation of the electrical drive system with a current controller is characterized by a rapid deterioration of motor torque and speed. It is desirable to use the overmodulation strategy, which guarantees the fast response even in transient state and satisfies the overall closed-loop control performance. In this paper, in order to improve the dynamic characteristics of the electrical drive, a new overmodulation technique is proposed. Considering the current transition characteristics, an efficient overmodulation strategy is introduced to achieve better transient performance through an adequate voltage selection. With the help of a new overmodulation strategy, required electrical torque can be directly produced as quickly as possible, and stable drive characteristics can be achieved in the transient condition. The proposed method has been implemented on an actual inverter system and thoroughly tested on a 900W interior permanent magnet synchronous machine (IPMSM) to confirm its feasibility. Index Terms - Current regulation, IPMSM, overmodulation.