In this article, an improved inertia disturbance suppression method is proposed for permanent magnet synchronous motor (PMSM) based on disturbance observer and two-degree-of-freedom PI controller (DOB-2DoFC). The DOB-2DoFC is proposed to enhance the speed control performance with variation of inertia caused by load changing. The traditional two-degree-of-freedom controller (2DoFC) is first introduced and the influence of inertia disturbance on 2DoFC is analyzed. Then, the disturbance observer (DOB) is designed to combine with 2DoFC for inertia disturbance suppression. Furthermore, the discretization of DOB-2DoFC is implemented and the impact of discretization is also analyzed, in the meanwhile, the parameters of DOB- 2DoFC is designed based on the premise of stability and good speed control performance. With the designed parameters, better speed control performance can be maintained without tuning any controller coefficients even when the actual inertia is 20 times the controller inertia. Finally, the effectiveness and the correctness of the proposed DOB-2DoFC are verified with experiments on a 400 W PMSM drive platform in two modes.

Traditional ultralocal model-based predictive current control (UL-PCC) method has strong robustness on current control; however, the UL-PCC still relies on inductance to design the controller gain, which really deteriorates its robustness on parameter. To solve it, a parameter-free ultralocal model-based deadbeat predictive current control (PF-DPCC) method using finite-time gradient method (FGM) is proposed in this article for permanent magnet vernier motor (PMVM) drives. The UL-PCC is first modified considering rotor speed without any extra parameter. Then, the impact of initial controller gain on robustness is analyzed and an extreme low duty-cycle current signal which has negligible impact on current is injected to estimate the controller gain of PF-DPCC adaptively on the basis of the deadbeat concept and the FGM. Hence, all motor parameters are not required in advance and the initial controller gain can be set as 1 directly. Then, the robustness can be effectively improved and the dependence on initial value of controller gain can be eliminated. Finally, the effectiveness and the correctness of the proposed PF-DPCC are experimentally verified on a 400-W PMVM drive platform.

This article proposes a pseudo-random high-frequency triangular-wave current signal injection (PR-HFTCI) based sensorless control scheme for synchronous reluctance motor (SynRM) drives at zero-low speed domain to suppress the high-frequency (HF) loss and the HF audible noise which are introduced by the significant nonlinearities of SynRMs and the traditional constant amplitude HF square-wave voltage injection method. The pseudo-random HF triangular-wave current signal with random frequency and random phase is injected to eliminate the discrete spectrum of the current power spectra density (PSD) and the corresponding current PSD analysis is performed to evaluate it. In addition, the HF component amplitude of the d -axis voltage reference can be adjusted adaptively with the variation of load to maintain the HF current amplitude constant, it is easy to implement and does not require any extra regulator and signal processing. Hence, the HF loss and the HF torque ripple can be effectively reduced under the heavy load. Finally, the effectiveness and the correctness of the proposed PR-HFTCI based sensorless control scheme are validated with experiments on a 1.5-kW SynRM drive platform.

The adaptive filters (ANF) have been commonly used in current harmonic suppression. However, the digital delay will narrow the stability region and its harmonic suppression performance will be deteriorated at high-speed region. To overcome this problem, this paper proposed two modified ANF. Combining with the deadbeat current (DBC) controller, the effect of digital delay on ANF is analyzed. A simple one step harmonic prediction method (OSPANF) is proposed to replace the traditional steepest gradient method (SGM). Based on the OSPANF, the current can be controlled stably in the high-speed area and the harmonic suppression effect is better than the traditional notch filter. Through bode diagram analysis, OSPANF will have a harmonic amplification peak near the set notch frequency, which may bring additional disturbances. Thus, a two steps prediction adaptive notch filter (TSPANF) is implemented. Through the Experimental results, it can be proved that the proposed TSPANF method has better harmonic suppression effect in the high-speed area than OSPANF and the stability region of the proposed two methods is larger than the traditional method.

Due to the complex boundary conditions of the thermal analysis method (AM), the error of the calculation results is large, and the lumped-parameter thermal network (LPTN) mostly focuses on the solution of the average temperature. This paper proposes a thermal analytical model for wheel-motor windings, which includes LPTN and AM to solve the problems of boundary condition extraction and maximum temperature solution in AM. The heat transfers between the end caps of electric vehicle wheels and the outside air are considered by the model. The node temperature of LPTN can be adopted as the boundary condition of the proposed analytical method to predict and calculate the maximum temperature and average temperature of the wheel motor and improve the accuracy of temperature rise calculation. To further analyze the winding temperature, the armature winding is divided into active winding and end winding for calculation respectively. In the calculation of active winding, based on the equivalent area method, the active winding and other materials are layered into a series of equal-width rectangular rings through a novel layered strategy. The compensated thermal resistance (TR) is introduced into the analytical model of end winding, and the accuracy of the end temperature solution is improved by the iteration of compensated TR. Finally, the effectiveness and correctness of the proposed analytical thermal model for motor temperature rise prediction are verified on a 2kW distributed double-layer winding wheel motor.

A radial-axial consequent pole hybrid excitation machine (RACP-HEM) with the advantages of interior permanent magnet synchronous machine (IPMSM) and electric excitation machine is studied, which has high torque output and wide speed range for electric vehicles (EVs). The radial-axial d-q axis model is established to solve the problem that the inherent asymmetry of the airgap density of consequent pole leads to difficult mathematical modeling. The current region control strategy with torque and speed as the criteria is proposed to efficiently improve operation performance of the RACP-HEM, which divides the operation region into different modes to realize high output torque and wide speed region. The maximum torque per ampere (MTPA) control of armature and excitation currents is integrated with the advantages of AC excitation and compared with i_d =0 control for low-speed region to obtain higher output torque. In high-speed region, the hybrid advanced angle field weakening control with three-dimensional (3-D) current vector is adopted to utilize the excitation current to solve the problem of the field weakening out of control caused by the traditional voltage feedback field weakening control to achieve higher speed. Finally, the simulation results and prototype experiments verify the effectiveness of the proposed control strategy for RACP-HEM.