State of the Art of Magnetic Gears, their Design, and Characteristics with Respect to EV Application

Abstract

This chapter briefly explains the advantage of using magnetic gears (MGs) for transportation applications. Usually, a traction EV unit consists of, besides the engine or motor, a mechanical gear. The drawbacks of using mechanical gears have been emphasized, especially with respect to high-speed motorization, where high transmission ratio can be reached only by connecting multiple gears in series. A magnetic gear is capable of overcoming these issues. The chapter presents a state of the art on the available MGs, with fixed or variable transmission ratio, pointing out their applicability. Next, the possible design approaches (harmonic, magnetic reluctance equivalent circuit, and vector potential) are introduced. Furthermore, the output performances (power and torque) of two types of studied MGs are evaluated, with emphasis on the main loss criteria: iron losses in all the active parts of the MG. Finally, the influence of several materials is observed by means of numerical computation in order to decide, based on specific configuration, the most suited variant for transportation and aeronautic applications.

State of the art of Multiport Electrical Machines and Magnetic Gears with respect to Wind Power Generation Application

“…In order to reduce the cogging torque, different techniques were analyzed, but the skew technique is preferred [35][36]. Also, in [37] it was introduced a cogging torque factor, kr, which gives a specific poles-pieces configuration to obtain smooth mechanical characteristics.…”

Novel Differential Evolutionary Optimization Approach for an Integrated Motor-Magnetic Gear Used for Propulsion Systems

“…Today, for a standard EV, the electric motor is connected to a mechanical cascaded gear system, which affects the overall efficiency of the transmission. In addition, the mechanical gear involves several well-known drawbacks: physical contact (friction) between the teeth, need for lubrication, local heat, material fatigue, and consequent mechanical losses [1]. In the case of magnetic gears (MGs), these drawbacks are avoided [2], [3], [4].…”

Design of a High-Speed Ferrite-Based Brushless DC Machine for Electric Vehicles

“…Alternatively, multiple mechanical gears with relatively low gear ratios may be employed, which are series-connected in order to enable a sequential reduction of HSEM speed. This configuration limits volume and weight increase compared to the previous solution, as pointed out in [5], but still suffers from efficiency issues due to high mechanical losses. A very promising solution consists of magnetic gears, which are characterized by high gear ratios, reduced volume and weight, as well as by high efficiency.…”

“…A very promising solution consists of magnetic gears, which are characterized by high gear ratios, reduced volume and weight, as well as by high efficiency. As a result, the use of HSEM combined with a suitable transmission system (seriesconnected and/or magnetic) allows a 20% reduction of volume and weight of Electric Vehicle (EV) propulsion system compared to those actually available on the market [5].…”