Design Analysis Of High-power BLDC In Electric Vehicles

Nowadays, energy shortage and environment pollution are urgent problemsneeded to resolve. As people’s indispensable travel tools, the number of cars has beenincreasing tremendously, however, the energy consumption and environmentalpollution become more and more serious, therefore, Electric Vehicle(EV) is gettingmore and more attention from people as a travel tool of energy conservation andenvironmental protection. EV is becoming the main development direction of China’snew energy vehicles. Driving motor is one of the core technologies in EV, and it willplay a big part in the vehicle performance. The driving motor should have high powerdensity, high torque density, high efficiency, wide range of speed and overload abilityetc. The main task of this paper is to design a high-power BLDC of30kW to meet theperformance requirements of the electric vehicle, and then optimize the structure of it.This paper first introduces the importance of R&D and research status at homeand abroad of electric cars, introduces and compares the advantages anddisadvantages of several commonly used driving motor, and ultimately choose SPMBLDC as electric vehicle’s drive motor for design research. Then the the basicstructure and working principle of BLDC is introduced, according to the performancerequirements of electric vehicles, the main technical parameters of the drive motor isdetermined, then conduct noumenon design of motor, and present the calculationprocedure and example analysis.This paper conduct the optimization design for motor, for high-power BLDCexist the problems of low-speed torque ripple. Aiming at reducing the cogging torque,the structure optimization design should conduct under the precondition of trying notto damage trapezoidal wave of back-EMF.Mainly adopting two kinds of optimizationmethod, one is to optimize the shift angle of stator slot opening and slot openingwidth, another is to optimize the slot opening tilt angle and slot opening width.Through the Response Surface Methodology (RSM) optimization, finally the coggingtorque is effectively reduced, furthermore, the wave form of back EMF is stilltrapezoidal wave.As the field-weakening capacity of SPM BLDC is limited, in this paper, itintroduced the principle of field-weakening of BLDC and mainly introduced twokinds of rotor structure, and compared the field-weakening capacity of them, furthermore, the applicable rotor structure of BLDC designed in the paper isdetermined.