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Abstract: This paper introduces the current development of pure electric vehicles, and describes the characteristics of different types of pure electric vehicle drive motors and related control methods. The main contents and related problems of some widely used drive motor control methods are introduced

due to the increasing attention of consumers and governments to environmental protection and the rising energy prices, automobile manufacturers all over the world have increased the development of new energy vehicles. Due to the impact of the financial crisis last year, since this year, most of the world's mainstream car parks have declined, especially the two major car parks represented by the United States and Japan have experienced sharp car slides, which makes the American and Japanese car manufacturers have to speed up their original conservative plans, thereby re stimulating the original core markets such as the United States and Japan. Electric vehicles, which use electric energy as energy, have the outstanding advantages of zero emissions and no pollution, so they are highly respected by the automotive industry. In China, the government has also launched various policies to promote the development of pure electric vehicles this year. Looking back on the development history of electric vehicles in the world, at least four times this time, the world automotive industry has failed to start pure electric vehicles for the first three times. The first three failures were mainly due to the battery. The first three times are basically based on lead-acid battery. Because its specific energy and specific price are relatively poor, it has not been promoted. Now with the continuous development of battery technology, the promotion of pure electric vehicles can be achieved. Now pure electric vehicles mainly use lithium batteries. The specific energy of lithium batteries is eight to ten times that of lead-acid batteries, and they are light in weight. BYD, Toyota, Chery and other auto companies will launch their own pure electric vehicles this year. And electric vehicles will gradually become a trend and necessity of automobile development

1. Performance of various electric vehicle drive motors

the key difficulties of pure electric vehicles lie in battery technology and drive motors. Battery technology has made a breakthrough to a certain extent. The next

mainly discusses the relevant conditions of the drive motor of a car

(1) the key problem of electric vehicle drive motor control

electric vehicle is a vehicle powered by on-board power supply and driven by motor. The motor and its drive system are one of the core components of electric vehicles. Due to the frequent starting and acceleration and deceleration operations during the operation of electric vehicles, there is a high demand for the drive system

car question mainly expounds some key problems in the control process:

(1) the motor used in electric vehicles has the characteristics of large instantaneous power, strong overload capacity (overload 3 ~ 4 times), good acceleration performance and long service life

(2) the speed regulation range of electric vehicle motor should be wide, including constant torque area and constant power area. It is required that large constant torque can be output at low speed to meet the requirements of fast start, acceleration, load climbing, etc; At high speed, it can output constant power and have a large speed regulation range to meet the requirements of high-speed driving such as flat road and overtaking

(3) when the vehicle decelerates, the electric motor for electric vehicles should be able to realize regenerative braking, recover and feed back the energy to the battery, so that the electric vehicle has the best utilization rate of energy

(4) within the operation range of the national advanced unit of circular economy, the motor for electric vehicles should optimize the efficiency of the drive system, so as to reduce the loss of the drive system and improve the driving range of one-time charging

(5) it is required that the motor used in electric vehicles has good reliability, can work in a harsh environment for a long time, simple structure, adapts to mass production, low noise during operation, convenient use and maintenance, low price, small volume, light weight, maintenance saving, anti vibration, etc

(2) types of drive motors

the research of electric vehicle drive system focuses on various types of drive motors and their control. According to the type of motor, electric drive system

can be divided into DC drive system and AC drive system. Since DC motor control was relatively simple in the early days, most electric vehicles used DC motors. However, with the development of modern AC speed regulation technology, its dynamic performance has reached or exceeded the level of DC motor, and AC motor itself has the advantages of small size, large power, high efficiency, simple structure, easy maintenance and so on. Because the AC motor has no brushes and slip rings, and overcomes the shortcomings brought by the large commutator of DC motor, the AC drive system will gradually become the mainstream drive system of electric vehicles. In AC drive, the drive motor mainly adopts asynchronous motor, hydro magnetic synchronous motor (including DC motor) and switched reluctance motor

(3) in the early days of DC brush motor

the control method and structure of DC motor were simple, only voltage control was needed, and the magnetic pole position did not need to be measured. In addition, the small capacity system

had low cost and mature technology, and its electromagnetic torque control characteristics were incomparable to that of AC electric machine, so DC motor was widely used in electric vehicles; However, due to the high price, large volume and mass of DC motor, its application in electric vehicles has been limited. At present, electric vehicles have been rarely used, but some electric vehicles still use DC motor drive system. For example, uot electric vehicle of Tokyo University in Japan adopts DC series excitation motor, 900e/E2 electric vehicle of Fiat company in Italy uses DC shunt excitation motor to drive, and bang0 electric vehicle of Mazda Automobile Company in Japan adopts DC shunt excitation motor

(4) AC induction motor (three-phase asynchronous motor)

three-phase asynchronous motor rotor joint plastic tension machine rubber tension mechanism is simple, and there is no direct contact part with stator, It has reliable operation, high speed and low cost. When the vehicle is powered by battery, it can realize quadrant operation. Therefore, at present, AC asynchronous motor is widely used in electric vehicles. Induction motor drive is widely used in electric vehicles made in the United States, such as epicvan produced by chryslet company; Rmnger EV produced by Ford company, impact and evi electric vehicles produced by General Motors

vehicle company. Induction motors are also used as the driving motors of electric vehicles in China, such as

Shengli sl6700dd electric bus, Zhengzhou Hualian Z, that is, the standard tension sample is in tension k6820hg-1 electric light bus. The research focus of induction motor system for electric vehicle is mainly on control. Its control methods include vector control, fuzzy logic control, vector control of series iron loss model and maximum efficiency control

(5) switched reluctance motor with a diameter of only one hair of 1 nanometer, which is 60000

switched reluctance motor has the advantages of simple structure and control, large output, high reliability, low cost, good starting and braking performance, high operation efficiency, high noise, serious torque ripple and serious nonlinearity. It has both advantages and disadvantages in the drive of electric vehicles. At present, electric vehicles are rarely used. Its main research direction is model research

(6) brushless DC motor and permanent magnet synchronous motor

hydro magnetic synchronous motor has the advantages of small volume, light weight, high power density, large low-speed output torque, high precision, high efficiency, low noise, simple maintenance. Therefore, it is applied in all countries. However, it is more complex than asynchronous motor in high-speed operation, and it needs to detect the rotor pole position. In addition, the water magnet has demagnetization problems, and the cost is also high. The main research focuses on position detection, commutation and control, which can be shown in the following aspects: analysis and determination of commutation logic, weakening of pulsating torque, no position sensing system, new control strategy. The research of control strategy includes variable structure control, the combination of fuzzy control and PID control, and the combination of various global optimization methods and fuzzy control methods