Identification of the stator d-axis and q-axis inductances is essential for interior permanent magnet synchronous motor (IPMSM) sensorless control system. The signal injection method is an effective way to identify the inductance parameters, however, it requires the rotor position to ensure the accuracy of the injection reference position. To overcome the dependence on the rotor position, a sequence-pulse voltage signal injection method is presented. The matrix least-square fitting algorithm is utilized to fit the current responses for inductance identification. Based on the fitting method, the discrete standard orthogonal polynomial with look-up table is introduced to reduce the computation complexity. To reduce the disturbance of the injected signal to the rotor position during the identification process, a double-direction injection position trajectory planning is presented. In addition, the saturation effect on the identification method is also analyzed. The proposed method is verified via a 3.0 kW IPMSM motor drive platform. The identification results are compared with those measured by standard method and experiment results show that the proposed method can identify the inductance parameters with acceptable accuracy without obtaining rotor position information.

This paper proposes an indirect input-series output-parallel (I2SOP) dc-dc full-bridge converter system based on asymmetric PWM (APWM) control strategy for high input-voltage applications. When a short-circuit fault occurs in the high input-voltage dc bus, the proposed I2SOP system can disconnect from the dc bus effectively and avoid the input filter capacitors of constituent modules discharge compared with the traditional ISOP system, facilitating the fault handling and protecting the input filter capacitors. Moreover, with the proposed I2SOP structure, it is easy to achieve redundancy design when one or a few constituent modules fail. The APWM control strategy is introduced to the I2SOP system rather than the classical phase-shifted control strategy for the basic full-bridge module to reduce the voltage stress of power switch and reduce the filter requirement. The characteristics of input voltage sharing and output current sharing of the I2SOP system are also analyzed. A three-module I2SOP system prototype was built and the experimental results verify the correctness and effectiveness of the proposed solution.

In this article, an extended two-state observer (ETSO) is proposed for the permanent magnet synchronous motor (PMSM) with the uncertainties of system parameters and load torque. First, the ETSO is designed to estimate the two extended states, namely control input gain and lumped disturbance. The control input gain includes moment of inertia and stator flux linkage. Then, a speed controller with online adjustment for the control input gain is designed by using the estimates obtained from the ETSO to improve the speed tracking performance of PMSM. The convergence of the ETSO and the speed controller is analyzed by Lyapunov theory. Finally, simulations and experiments are carried out to verify the effectiveness of the proposed control scheme. The results demonstrate that the control input gain and the lumped disturbance are effectively estimated, and the speed tracking performance of the PMSM with the uncertainties of moment of inertia, stator flux linkage, and load torque is significantly improved.

The principal methods of initial rotor position estimation of permanent magnet synchronous machine (PMSM), such as high-frequency rotating signal injection methods and high-frequency pulsating signal injection methods, are implemented by calculating the voltage equations of the stator winding. However, these methods have low adaptability to the PMSMs with different saliency properties and high sensitivity to electrical parameter variation. An initial rotor position estimation method based on the dynamical equations of the PMSM is proposed to solve the problems above. Firstly, a series of vibration signals of the PMSM is generated by applying a high-frequency voltage to the rotating virtual d-axis of the rotor. Then, the relationship between the vibration signals and the rotating virtual d-axis position is established. Next, the initial d-axis rotor position of the PMSM is estimated by analyzing the vibration response curve. At last, the rotor magnetic polarity is identified on account of the saturation saliency effect. The theoretical analysis and simulation, as well as experiments, are carried out to verify the effectiveness and accuracy of the innovation method. The results demonstrate that the proposed method has the advantages of easy to implement, high adaptability, and strong robustness.

This paper proposes an improved internal-model-control (IMC)-based proportional-integral (PI) current controller for a permanent magnet synchronous motor (PMSM) drive system to solve the parameter dependence problem. The parameter sensitivity of the conventional IMC-based PI controller is analyzed, which indicates that the parameters mismatch would cause oscillation or overshoot. Therefore, this paper utilizes an uncertainty and disturbance estimator to eliminate the impact of the parameters mismatch disturbance caused by the parameters variation. The proposed controller includes an IMC-based PI controller, which is responsible for tracking, and a disturbance estimator, which deals with other control difficulties. The performance and robustness are easily achieved by separately tuning the only two parameters (the desired closed-loop bandwidth and the estimator bandwidth). The frequency-domain characteristic of the proposed current controller indicates that it can effectively suppress the parameters mismatch disturbance. Simulations and experiments have verified the effectiveness of the proposed method.