In the environment of environmental protection, electric vehicles have also become a hot spot in recent years. Electric vehicles can achieve zero or very low emissions in urban transportation, and have great advantages in the field of environmental protection. Countries are striving to develop electric vehicles. The electric vehicle is mainly composed of a motor drive system, a battery system and a complete vehicle control system. The motor drive system is a part that directly converts electric energy into mechanical energy, and determines the performance index of the electric vehicle. Therefore, the choice of the drive motor is particularly important.
Electric vehicle requirements for driving motors
At present, the evaluation of the performance of electric vehicles mainly considers the following three performance indicators:
(1) Maximum mileage (km): The maximum mileage of an electric vehicle after the battery is fully charged;
(2) Acceleration capacity (s): the minimum time required for an electric vehicle to accelerate from a standstill to a certain speed;
(3) Maximum speed (km/h): The highest speed that an electric car can reach.
Motors designed for the driving characteristics of electric vehicles have special performance requirements compared to industrial motors:
(1) Electric vehicle drive motors usually require high dynamic performance requirements for frequent start/stop, acceleration/deceleration, and torque control;
(2) In order to reduce the weight of the whole vehicle, the multi-speed transmission is usually cancelled, which requires the motor to provide higher torque at low speed or climbing, and generally can withstand 4-5 times overload;
(3) The speed regulation range is required to be as large as possible, and at the same time, it is necessary to maintain high operating efficiency throughout the speed regulation range;
(4) When designing the motor, try to design it as high rated speed, and try to use aluminum alloy shell as much as possible. The high speed motor is small in size, which is beneficial to reduce the weight of electric vehicles.
(5) Electric vehicles should have optimized energy utilization, with braking energy recovery function, and the energy recovered by regenerative braking should generally reach 10%-20% of the total energy;
(6) The working environment of the electric motor used in electric vehicles is more complicated and harsh. It requires the motor to have good reliability and environmental adaptability, and at the same time ensure that the cost of motor production cannot be too high.
