An active magnetic bearing (AMB) is a kind of high-performance bearing that uses controllable electromagnetic force to levitate the rotor. Its control performance directly affects the operation characteristics of high-speed motors and other electromechanical products. The magnetic bearing control model is nonlinear and difficult to control. Sliding mode control algorithm can be used in the magnetic bearing control system, but the traditional sliding mode control has the problem of high-frequency chattering, which affects the operation stability of magnetic bearings. Based on the second-order sliding mode control algorithm, a new second-order sliding mode controller for active magnetic bearing control was designed, and the stability of the designed sliding mode control law was proven by Lyapunov criterion. On the basis of the established active magnetic bearing control model, the numerical analysis of the designed controller was carried out, and the control effect was compared with that obtained by the exponential reaching law for the sliding mode control algorithm. The experimental results show that the designed sliding mode controller has better dynamic performance and stability than the exponential reaching law for the sliding mode controller.

The in-wheel motor has received more attention owing to its simple structure, high transmission efficiency, flexible control, and easy integration design. It is difficult to achieve high performance with conventional motors due to their dimensions and structure. This paper presents a new dual-stator and dual-field-excitation permanent-magnet in-wheel motor (DDPMIM) that is based on the structure of the conventional in-wheel motor and the structure of both the radial and axial magnetic field motor. The finite element analysis (FEA) model of the DDPMIM is established and compared with that of the conventional in-wheel motor. The results show that the DDPMIM achieves a higher output torque at low speeds and that the flux-weakening control strategy is not needed in the full speed range.

The stator structure of a disc-type permanent-magnet synchronous motor is a printed circuit board (PCB). The design of stator windings has a direct influence on motor performance and the utilization rate of the stator. However, in some respects, PCB processing technology limits the development of the disc-type electric motor with a PCB stator. For example, the wiring of the stator winding and the connections of the ends are single. In this paper, an improved winding was designed to improve the output power. The analytic expressions for the back electromotive force (EMF) and other parameters such as power, winding resistance, and eddy loss are established, respectively. According to finite-element theory, the characteristics of the improved winding and distributed winding under no load and load were simulated and analyzed. It is concluded that the improved winding not only improves no-load back EMF, along with output power and efficiency under load, but also the utilization rate of the stator was greatly improved. Finally, a prototype was made to verify the design that has a certain reference value for the design of a disc-type permanent-magnet motor with a PCB stator.

The key to control the range extender generation system is to improve the efficiency and reduce the emissions of the electric vehicle (EV). In this paper, based on the purpose of efficiency optimization, both engine and generator are matched to get a public high efficiency region, and a partial power following control strategy was presented. The engine speed is constant in the defined power range, so the output power regulation of the range extender is only realized by the adjustment of the torque of the generator. Engine speed and generator torque were decoupled. An improved proportional resonant (PR) controller is adopted to achieve fast output power regulation. In order to ensure the response characteristics of the control system and to improve the robustness, the impacts on system’s characteristics and stability caused by PR controller and parameters in the inner-current loop were analyzed via frequency response characteristics. A pre-Tustin with deviation compensation is proposed for PR controller’s discretization. A stable and robust power following control method is obtained for the range extender control system. Finally, simulation and experiment of the proposed control strategy illustrated its feasibility and correctness.

The disc coreless permanent magnet synchronous machine (PMSM) has many advantages. The inductance is far lower than that of the machines with the core structure. However, the general converter is designed for general machines. The current fluctuations are large when the low-inductance PMSM (LIPMSM) is driven by the general converter. To solve the above problem, the integrated design concept is adopted to design the converter, including the modulation algorithm, control algorithm, and the corresponding topology. The joint modulation strategy is proposed to increase the modulation frequency, which adjusts the output voltage by using the bus circuit and inverter circuit. The model predictive current control (MPCC) algorithm based on the joint modulation strategy is proposed, which has a small computational burden and high control accuracy. The most important feature of the proposed MPCC is that it has a modulation algorithm. To further reduce the current fluctuations, the bus voltage is adjusted in real time according to the bus voltage optimization algorithm. A new topology of the converter is designed to implement the algorithm function. Finally, the correctness and feasibility of the proposed method are verified. Compared with the general converter, the new one has a great improvement on the LIPMSM.

Interior permanent magnet synchronous motors (IPMSMs) have some inherent disadvantages, such as high torque ripple and difficulty in optimizing design due to the complex rotor structure. To address these issues, this paper proposes a method for optimizing the rotor structure of IPMSMs to reduce torque ripple. The flux barriers in the rotor are abstracted as virtual slots, and the effect of the position of the virtual slots on torque ripple is studied. Based on this analysis, a general method for optimizing the rotor structure to reduce torque ripple is proposed. To demonstrate the proposed method's effectiveness, the original prototype's rotor structure is optimized using the proposed method. The electromagnetic performance of the prototype before and after optimization is calculated. The results show that the optimization can reduce the torque ripple without affecting other electromagnetic performance. Finally, the theoretical analysis and simulation results are validated by conducting a prototype test, which provides support for the proposed method of torque ripple reduction.