The compactness, cost decrease, and reliability of the auxiliary drive permanent magnet synchronous motors (PMSMs) for battery electric commercial vehicles can be further improved by adopting the position sensorless control technique. The conventional extended back electromotive force (EEMF) based sensorless control algorithm usually requires a phase-locked loop (PLL) and low pass filter to postprocess the estimated rotor position, which deteriorates the transient response of the PMSM significantly. To solve this problem, this article proposes an active disturbance rejection control based EEMF sensorless control method. By designing an extended state observer (ESO) considering the differential term of the position estimation error, timely and accurate estimation of the load disturbance and rotor position can be achieved simultaneously. The adaptive mechanism of the ESO exhibits sound system antidisturbance performance. Moreover, a linear state error feedback controller and feedforward compensation of load disturbance can replace the speed loop PI controller accordingly. Through stability and tracking performance analysis, the proposed method is superior in both steady-state performance and transient-state performance. The proposed scheme is experimentally validated by a 3 kW automotive power steering oil pump motor drive system. The results show that the transient response characteristics are obviously enhanced compared with the conventional methods. ¹

Extended back electromotive force (EEMF)-based position sensorless field-oriented control (FOC) is widely utilized for ultra-high-speed surface-mounted permanent magnet synchronous motors (UHS-SPMSMs) driven fuel cell air compressors in medium-high speed applications. Unfortunately, the estimated position is imprecise due to too small EEMF under low speed operation. Hence, current-to-frequency (I-f) control is more suitable for startup. Conventional I-f methods rarely achieve the tradeoff between startup acceleration and load capacity, and the transition to sensorless FOC is mostly realized in the constant-speed stage, which is unacceptable for UHS-SPMSM considering the critical requirement of startup time. In this article, a new closed-loop I-f control approach is proposed to achieve fast and efficient startup. The frequency of reference current vector is corrected automatically based on the active power and the real-time motor torque, which contributes to damping effect for startup reliability. Moreover, an amplitude compensator of reference current vector is designed based on the reactive power, ensuring the maximum torque per ampere operation and higher efficiency. Furthermore, the speed PI controller is enhanced by variable bandwidth design for smoother sensorless transition. These theoretical advantages are validated through experiments with a 550 V, 35 kW UHS-SPMSM. The experimental results demonstrated the enhanced startup performance compared with conventional I-f control.

Sensorless control of permanent magnet synchronous motors is preferable in some applications due to cost and mounting space concerns. The performance of most existing position estimation methods greatly depends on the accuracy of the motor inductance. As the estimated position should not be involved in the parameter identification process in a sensorless control system, an online inductance identification method independent of the rotor position information is developed in this paper. The proposed method utilizes the recursive least square algorithm and the particle swarm optimization algorithm to realize real-time identification of the inductance along the direct axis and the quadrature axis, respectively, based on the deduced parametric equations without position information. The proposed method is efficient enough to be implemented within 0.2 ms and does not introduce any additional signal injection. A test bench is built to validate the characteristics of the method, and the experimental results show that the identified inductance can converge to the actual value rapidly and is robust to changes in the initial values and stator current. With the proposed method, accurate estimation of the rotor position and speed can be obtained using traditional model-based position estimators, and the stability of the sensorless control system can be improved significantly.

The complex vector current regulator (CVCR) has been increasingly applied in PMSM drives recently. Furthermore, the active damping compensation is introduced to improve the insufficient disturbance rejection ability of CVCR. However, conventional active damping methods usually set the damping term to a constant, and its performance will degrade as the switching-to-fundamental frequency ratio (f_ratio) decreases, which makes it difficult to meet the requirements of advanced driving systems such as ultra-high-speed PMSM. To solve such a problem, this article proposes a CVCR based on enhanced active damping function. First, the damping structure is reconstructed to fully determine the plant poles in the disturbance transfer function while keeping the structure as simple as possible without the lead operator. Second, the coefficients in the damping term are designed to ensure that the plant poles remain in the high-damping region even at high speeds and low f_ratio. Then, the CVCR is redesigned in the discrete-time domain to ensure satisfactory command tracking performance. Finally, the implementation form of the proposed method in digital systems is derived. The experimental results have verified the effectiveness of the proposed method and demonstrated its superiority over traditional methods.

Overmodulation method is an effective way to improve the voltage utilization for the PMSM drives, thus achieving higher efficiency and power capacity. However, the voltage jump between the output voltage vectors (OVVs) causes the deterioration of both phase voltage and current performance in the high overmodulation region. In order to eliminate the voltage jump, a novel variable-weight superposition theory (VWST) is proposed. Different from other methods, the phase angle of the reference voltage vectors (RVVs) is introduced to construct the variable-weight factor. This elaborate weight factor is assigned to the jump component with the variation of the phase angle. Eventually, the voltage jump is eliminated, and the total harmonic distortion (THD) of both phase voltage and current is decreased, which means smaller current ripple and torque jitter. In addition, the linearity of the modulation index is guaranteed by a convert block based on the Fourier analysis. With the help of the proposed method, the voltage jump can be eliminated, and better performance of phase voltage and current can be achieved. The effectiveness of the proposed method is verified by PMSM bench experiments.