THE INFLUENCE OF PERIPHERAL AND ROTATION SPEED ON THE DESIGN, COOLING SYSTEM, AND CHARACTERISTICS OF AN ELECTRIC MACHINE IN A HYBRID SYSTEM

The article presents an analysis of the electric machine with an external rotor design with a power of 200 kW, providing high specific properties and intended for use as part of hybrid propulsion systems. The design of a high-speed synchronous electric machine with excitation from permanent magnets and an external rotor was chosen as the most promising from the point of view of achieving the required specific properties. The main limitation for obtaining the maximum power density in such designs is the rotor strength reliability. In order to determine the achievable level of electric machines specific power at the existing technology level, an analysis of the electromagnetic and strength characteristics of the design with different peripheral speeds at the periphery (u=200–300 m/s) and rotor speeds (n=20000–30000 rpm) was carried out. During the calculation and analytical study, the following was established: to minimize torque pulsation and tooth torque, it is recommended to ensure a peripheral speed of more than 230 m/s; the optimal ratio of the machine active part length to its diameter is 0,24–0,26; it is advisable to use a titanium alloy as a rotor material. The ratio of peripheral speed and rotational speed has been determined, providing maximum values of specific power (11 kW/kg) and efficiency of the electric machine (92,653%) are ensured with the following. To obtain the specified values of specific properties, the design of the cooling system was determined and the power consumption for it was taken into account.