What is an electric vehicle motor
What is an electric vehicle motor?
Table of Contents
- What is an electric vehicle motor?
- Classification of electric vehicle motors
- Performance requirements of electric vehicle motor
- Working principle of electric vehicle motor
- Maintenance of electric vehicle motor
- Trouble shooting of electric vehicle motor
- Development prospect of electric vehicle motor
An electric vehicle motor refers to a kind of electromagnetic device that realizes the conversion or transmission of electric energy according to the law of electromagnetic induction. Permanent magnet motor is represented by the letter “M” in the circuit (old standard “D”). Its main function is to generate driving torque, as the power source of electric vehicles.
Classification of electric vehicle motors
Electric vehicle motor can be divided into AC motor, DC motor, AC / DC dual-purpose motor, control motor (including stepping motor, speed measuring motor, servo motor, self-adjusting motor, etc.), switched reluctance motor and signal motor, etc. The motors suitable for electric drive can be divided into DC motors
There are two kinds of electric motors: electric motors that convert direct current energy into mechanical energy and AC motors that convert alternating current energy into mechanical energy. DC motor, AC induction motor, permanent magnet brushless motor, switched reluctance motor and so on have been applied in electric vehicles.
Performance requirements of electric vehicle motor
The characteristics of automobile driving are frequent starting, accelerating, decelerating and stopping. High torque is required at low speed or climbing, and low torque is required at high speed. The speed range of the motor should be able to meet the requirements of the vehicle from zero to the maximum speed, that is, the motor should have high specific power and power density. The main requirements of electric vehicle motor can be summarized into the following 10 aspects:
- (1) High voltage. In the allowable range, the use of high voltage as far as possible can reduce the size of motor and wire, especially the cost of inverter. The working voltage is increased from 274 V of th to 500 V of th B; Under the same size condition, the maximum power is increased from 33 kW to 50 kW, and the maximum torque is increased from 350 n “m to 400 on” M. It can be seen that the application of high voltage system is very beneficial to the improvement of vehicle power performance.
- (2) High speed. The speed of induction motor used in electric vehicle can reach 8 000-12 000 R / min. the high speed motor has small volume and light weight, which is conducive to reducing the quality of loading equipment.
- (3) Light weight and small volume. The quality of the motor can be reduced by using aluminum alloy shell. The materials of various control devices and cooling system should also be light materials. The driving motor of electric vehicle requires high specific power (output power per unit mass) and high efficiency in a wide range of speed and torque, so as to reduce vehicle weight and extend driving range; Industrial drive motors usually consider the power, efficiency and cost comprehensively, and optimize the efficiency near the rated working point.
- (4) The motor shall have large starting torque and wide range of speed regulation performance to meet the power and torque required for starting, acceleration, driving, deceleration and braking. The motor should have the function of automatic speed regulation, so as to reduce the driver’s control intensity, improve the driving comfort, and achieve the same control response as the accelerator pedal of internal combustion engine vehicle.
- (5) In order to meet the requirements of short-time acceleration and maximum gradient, the electric vehicle drive motor needs to have 4-5 times of overload, while the industrial drive motor only needs to have 2 times of overload.
- (6) Electric vehicle drive motor should have high controllability, steady-state accuracy and dynamic performance to meet the coordinated operation of multiple motors, while industrial drive motor only needs to meet a specific performance.
- (7) The motor shall have high efficiency and low loss, and can recover braking energy when the vehicle decelerates.
- (8) The safety of electrical system and control system shall meet relevant standards and regulations. The working voltage of various power batteries and motors of electric vehicles can reach more than 300 V, so high voltage protection equipment must be equipped to ensure safety.
- (9) It can work reliably under harsh conditions. The motor shall have high reliability, temperature and humidity resistance, low noise during operation, and be able to work in harsh environment for a long time.
- (10) Simple structure, suitable for mass production, convenient use and maintenance, low price, etc.
Working principle of electric vehicle motor
1. What is a motor?
A: motor is a part that converts battery power into mechanical energy, which drives the wheels of electric vehicles to rotate.
2. What is stator?
A: the part that does not rotate when the brush or the brush free motor is working. The shaft of the motor with brush or toothless motor with hub is called stator, which can be called internal stator motor.
3. What is a rotor?
A: the part that is rotating when the brush or the brush free motor is working. The case of the hub type brush or toothless motor is called rotor, which can be called external rotor motor.
4. What is a carbon brush?
A: the brush motor is top on the surface of the phase changer. When the motor is rotating, the electric energy is transmitted to the coil through the phase changer. Because its main component is carbon, it is called carbon brush, which is easy to wear. The replacement shall be maintained regularly and the carbon deposit shall be cleaned.
5. What is brush grip?
A: mechanical guide groove for holding and holding the position of brush in the brush motor.
6. What is a phase changer?
A: in the brush motor, there are strip metal surfaces with mutual insulation. When the motor rotor rotates, strip metal contacts the positive and negative poles of the brush alternately, realizing the alternating change of the current direction of the motor coil and the commutation of the coil of the brush motor.
7. What is phase order?
A: the arrangement sequence of the coils of the brush less motor.
8. What is magnetic steel?
A: it is generally used to call high magnetic field strength magnetic materials. Electric motor adopts NdFeB rare earth magnetic steel.
9. What is a brush motor?
A: when the motor works, the coil and commutator rotate, the magnetic steel and carbon brush do not rotate. The alternating change of coil current direction is * the commutation and brush that follow the motor rotation are completed. In the electric vehicle industry, brush motor can be divided into high speed brush motor and low speed brush motor. There are many differences between brush motor and brush motor. It can be seen from the name that there are brush motors with carbon brushes, and the brush motor has no brushes.
10. What is a brush free motor?
A: the controller provides DC current in different current directions to achieve alternating changes of coil current direction in the motor. There is no brush and phase changer between rotor and stator of brush motor.
11. How to realize phase change of motor?
A: when the brush free or brush motor is rotating, the direction of power on of the coil inside the motor needs to be alternately changed to achieve the continuous rotation of the motor. The commutation * phase changer and brush of the brush motor are completed together, and the controller of the brush free motor * is completed.
12. What is lack of phase?
A: one phase of the three-phase circuit of the BLDCM or the bldcontractor cannot work. The phase is divided into main phase and hall phase. It is shown that the motor jitter can not work, or the motor can not rotate powerfully and the noise is large. It is easy to burn down the controller when it is in phase short state.
13. What are the common types of motors?
A: common motors are: toothed hub motor, brush toothless hub motor, brush free toothless hub motor, brush free toothed hub motor, side hanging motor, etc.
14. How to distinguish high and low speed motors from the types of motors?
A: a brush with gear hub motor, brush free toothed hub motor belongs to high-speed motor;
B the brush toothless hub motor and the toothless hub motor belong to the low-speed motor.
15. How is the efficiency of the motor defined?
A: the efficiency of the motor refers to the ratio of the mechanical energy output by the motor to the power supply. It is represented by the letter “り”.
16. How is the brush free motor classified?
A: from the angle of phase, it can be divided into two categories, namely, 60 ° And 120 ° The brush less motor with phase angle; According to the speed, it can be divided into high speed brush motor and low speed brush less motor; According to whether the motor has position sensor, it can be divided into position sensor and position sensor.
17. What is a position sensorless brush less motor?
Answer: for the sensorless brush motor, the motor must be pedaled first to make the motor have a certain rotation speed, and then the controller can recognize the phase of the brush free motor, and then the controller can supply power to the motor. Because it can not realize zero speed start, it is seldom used. But because there is no sensor, all of them have one less failure point, and the cost is lower.
18. What is the approximate range of hall power consumption of BLDCM?
A: the power consumption of hall of BLDCM is about 6ma-20ma.
19. What is the voltage range of hall for BLDCM?
A: the voltage range of hall of BLDCM is generally 3-24v.
20. What temperature can the general motor work normally? What temperature can the motor withstand at most?
A: if the temperature of the motor cover is measured more than 25 degrees above the ambient temperature, it indicates that the temperature rise of the motor has exceeded the normal range, and the temperature rise of the general motor should be below 20 degrees. Generally, the motor coil is made of enameled wire. When the temperature of the coating wire is higher than 150 ℃, the paint film will fall off due to the high temperature, which causes the coil short circuit. When the coil temperature is above 150 ℃, the temperature of the motor shell is about 100 degrees, so if the temperature of the motor is based on the temperature of the shell, the maximum temperature of the motor is about 100 degrees.
21. The temperature rise of the motor shall be below 20 ℃, that is, the temperature of the motor end cover shall be less than 20 ℃ when the temperature exceeds the ambient temperature, but what is the reason why the motor heat exceeds 20 ℃?
A: the direct reason for the motor heating is caused by the high current. Generally, it may be caused by short circuit or open circuit of coil, low efficiency of motor in demagnetization of magnetic steel, and the motor operates for a long time and large current.
22. How to measure the phase angle of the brush less motor?
A: turn on the controller power supply, and the controller supplies power to Hall components, and the phase angle of the brush free motor can be detected. The methods are as follows: use the +20v DC voltage range of multimeter, connect the red lead to the +5v line, and measure the high and low voltage of the three leads respectively (there is a skill in the usage of the red and black probes here). Press 60 ° And 120 ° The phase change table of the motor can be compared.
23. If 60 ° The brush free controller of is used in 120 ° What will be the condition on the BLDCM? What is the opposite?
A: all of them will lead to phase shortage and can not operate normally; But an intelligent brush less controller developed by Tianjin Songzheng can automatically identify 60 ° Motor or 120 ° The motor can be compatible with the two motors, making it easier to repair and replace.
24. What is the visual difference between the brush high speed motor and the brush low speed motor?
A. high speed motor has the function of overrunning clutch (like flywheel), easy to turn in one direction and hard to turn in the other direction; The two-way rotation of low speed motor is as easy.
B. The noise of the high-speed motor is larger when the car is rotating, and the noise of the low-speed motor is smaller. Experienced people are easy to recognize by their ears.
25. How is the starting current of the motor defined?
A: generally, the starting current of motor should not exceed 2-5 times of its rated current, which is an important reason why current limiting protection is done on the controller.
26. Why is the motor speed sold on the market getting higher and higher and what effect?
A. the supplier can reduce the cost by increasing the speed. It is also a low-speed motor. The speed is lower than the number of turns of the coil, and the number of silicon steel sheet and magnetic steel is also reduced. The buyer thinks that the speed is good.
B. When the rated speed is working, its efficiency is constant, but the efficiency is obviously low in the low speed zone, that is, the starting is weak.
C. The efficiency is low, it needs to be started with high current, and the riding current is also large. The current limit of the controller is high and the battery is not good.
27. How to repair the abnormal heating of the motor?
Answer: the maintenance treatment method is generally to replace the motor or carry out maintenance.
28. When the no-load current of the motor is greater than the limit data of the reference table, it indicates that the motor has failed, and what are the causes? How to repair?
A: the internal mechanical friction of the motor is large; Coil partial short circuit; Demagnetization of magnetic steel; Carbon deposition of DC motor commutation. The maintenance treatment method is generally to replace the motor, or replace the carbon brush, clean up the carbon deposit.
29. what is the maximum fault free maximum no-load current of various motors?
- When the rated voltage of motor type is 24V, the rated voltage is 36V.
- Side mounted motor 2.2a1.8a.
- High speed brush motor 1.7a1.0a.
- Low speed brush motor 1.0a0.6a.
- High speed brush less motor 1.7a0.6a.
- Low speed brush less motor 1.0a0.6a.
30. The feeling of slow speed and heavy stagnation is strong when riding by human
(1) Friction between front brake or holding brake (rising brake) and rotating part → adjust the clearance between front and rear brake and rotating parts, which not only makes the rotation flexible, but also ensures good braking performance.
(2) Chain too tight? Adjust the rear axle front and rear position.
(3) Front and rear axle gears and middle axle parts are too tight or parts are worn → loose fasteners or replace worn parts.
(4) Insufficient inflation of front and rear tires → tire inflation to full.
31. The two red lights will turn off when the battery is sufficient but the load is in the case
(1) Charger output voltage is low → troubleshooting according to charger maintenance method.
(2) Short battery charging time → recharge to extend charging time.
(3) Battery pack or one of them has decreased? Troubleshooting according to battery box maintenance method.
(4) Electrode damaged or poor contact? Replace electrode.
32. There are some feelings of stopping, slow and weak when driving
(1) Poor connection of seven core connection → replace seven core wire.
(2) Poor contact of hall power off brake handle → change hall power off brake handle.
33. The battery is sufficient, the display light is on, but the load hub is unable to rotate
(1) Gear wear and slip → replace gear.
(2) Hub motor winding part short circuit → replace motor.
(3) Bicycle assembly problem or parts wear → replace damping rubber.
34. Irregular stop of electric drive
(1) Loose or poor electrical conductivity between controller and electric hub connector → plug in the plug-in again or replace the plug-in.
(2) The carbon brush of the hub motor is in bad contact with the rotor → the fault is eliminated according to the maintenance method of the hub.
35. Electric drive noise
(1) Wheel hub gear oil shortage → open the hub and apply gear grease.
(2) Gear defect → replace gear.
(3) Damaged gear housing bearing? Replace bearing.
Before removing the motor, the lead wire of motor and controller shall be pulled out first. At this time, it is necessary to record the one-to-one correspondence between the color of motor lead and the color of controller lead.
Before opening the motor end cover, the site shall be cleaned to prevent sundries from being absorbed on the magnetic steel in the motor. Mark the relative position of end cover and hub. Note: it is necessary to loosen the screws diagonally to avoid deformation of motor housing.
Maintenance of electric vehicle motor
Electric vehicle motor maintenance and maintenance points:
- 1. Wiring of motor: four outgoing cables of motor are marked as follows: A1 – head end of armature winding, a2 – end of armature winding, D1 (D3) – head end of series excitation winding, D2 (D4) – end of series excitation winding. D2 is connected with A1, and the motor can rotate by applying voltage between D1 and A2. If you want to go back to D1, D2 or A1, A2 any group of transposition can be achieved.
- 2. There are four inspection windows at the motor commutator end for observing and maintaining the commutator and replacing the brush.
- 3. The minimum allowable insulation resistance of motor is (250V megohmmeter): 0.5m for motor below 45V Ω， 45-100v motor 1 m Ω.
- 4. If necessary, clean the groove between the commutators and the carbon powder on the commutator surface.
- 5. The motor is not allowed to start at high speed.
- 6. Open the shutter regularly to check whether the reversing part and brush are normal.
Trouble shooting of electric vehicle motor
(1) The instrument display of electric vehicle is normal and the motor does not run:
- ① Judgment of brake handle damage.
- ② Judging the damage of speed regulating handle.
- ③ Motor damage judgment.
- ④ The controller is damaged.
- ① Pull out the brake handle socket (normally open brake handle). If the motor is running, it is the brake handle fault, so the brake handle should be replaced.
- ② 5 V voltage of the handle source is normal. Detect the signal voltage of the handle. When the handle is turned, the signal voltage should change from low to high within 0.8 ~ 4.2 v. If the voltage does not change and is less than 1V, it means that the handle is faulty or the handle line is short circuited. If the voltage is greater than 1V and the change is normal, detect the motor Hall signal (yellow, green and blue lines). If the three-phase Hall signal line voltage is 5V and the contact is good, the motor Hall is damaged, and the motor or motor Hall element should be replaced.
- ③ Detect the hall signal line of the motor respectively, rotate the motor slowly by hand, and the voltage of each phase should change between 0-5V. If the voltage does not change, the motor Hall is damaged, and the motor or motor Hall element should be replaced. If the voltage transformation of each phase is normal and the power supply is normal, the controller will be damaged and replaced.
- ④ Use a multimeter to detect the voltage at the power input terminal of the controller. The voltage should be greater than 36V (the battery is fully charged). If there is no voltage, check the input line. Check the power supply voltage of the controller handle (connected with the red and black wires of the handle). The normal voltage is 5 ~ 6V. If there is no 5V voltage, unplug the handle socket, and the voltage recovers to 5V, it may be the short circuit of the motor Hall element. If there is still no 5V voltage, it is the controller fault, and the controller should be replaced.
- ⑤ First, check whether there is a short circuit between the speed regulating handle and the hall switch of the electric vehicle motor. Generally, it is easier to cause a short circuit of the connector after rain and damp. Therefore, pay attention to the waterproof of the handle connector. If the controller is damaged, check whether there is a short circuit between the handle and the hall switch of the motor before replacing it with a new controller? Otherwise, the replacement controller will be damaged continuously.
- ⑥ Or if the motor doesn’t work, check the hall switch and handle signal of the motor. If the power is on, the shell of the controller is very hot. Generally, if the power tube inside the controller is short circuited, the power supply should be cut off immediately.
Development prospect of electric vehicle motor
The development history of electric vehicles is a history of spiral rise. In 1834, Davenport, an American, demonstrated his own small battery car on the streets of Brandon City. Electric vehicles gradually developed and flourished. At the end of the 19th century, automobile manufacturing was successful. Because the performance of automobile was much higher than that of electric vehicle, electric vehicle was excluded. In the 1960s, the automobile has become the main source of urban pollution. In the 1970s, there was an oil crisis, which made the electric vehicle get attention again. Governments around the world began to formulate laws and regulations to develop electric vehicles. Automobile industry has developed into a pillar industry of national economy, and automobile has become an indispensable part of people’s life; But at the same time, cars cause serious pollution to cities, and the world’s proven oil resources can only be developed and used for more than 40 years. Therefore, it is inevitable to study high-performance electric vehicles to replace automobiles. The development of electric vehicles in the world has transited from trial operation to popularization and application: Japan began to sell commercial vehicles to domestic users in 1996, and the United States began to sell commercial vehicles to American users in 1997. China’s electric vehicles are in the development stage. In order to promote international exchanges and cooperation, the State Science and Technology Commission and the Ministry of machinery industry held the 1996 Beijing international technical exchange, seminar and Exhibition on electric vehicles and alternative fuel vehicles from December 6 to 15, 1996. Various problems in the development of electric vehicles are discussed. At the same time, automobile manufacturers at home and abroad, as well as some domestic colleges and universities and scientific research institutions have exhibited their own electric vehicles. This conference reflects some of the latest research results of electric vehicles, from which we can see the development trend of electric motor for electric vehicles.
The key to restrict the development of electric vehicles
Compared with traditional fuel vehicle, electric vehicle is equivalent to replacing fuel with battery and engine with motor. Because the energy density of battery (WH / kg) is far lower than that of fuel, the performance of traditional structure motor can not be directly applied to electric vehicles. Therefore, battery and motor are not only the core of electric vehicles, but also the key to restrict the development of electric vehicles.
Development trend of motor for electric vehicle
Although a variety of driving motors have been well researched, they can not be directly applied to electric vehicles, because electric vehicles have their unique operating characteristics, so the motor used must meet these characteristics in order to obtain high performance.
Characteristics of electric vehicles
The most significant feature of electric vehicles is frequent start stop, acceleration and deceleration, rather than running at a constant speed. Electric vehicles are mainly used in fixed routes and some special occasions, such as airports, stations, docks, warehouses, tunnels and tourist areas, in large and medium-sized cities with serious pollution. People have certain requirements for the driving distance and the maximum speed of electric vehicles, but the requirements are not very high. Generally, driving 50-100km with one charge, and the maximum speed within 100km / h can meet the requirements. In the long run, if an electric vehicle wants to replace a fuel vehicle, its performance must be comparable to that of a fuel vehicle, so its driving distance and maximum speed on one charge should be greatly improved. In addition, people pay more attention to reliability and price.
Characteristics of motor for electric vehicle
Based on the characteristics of electric vehicles, the motor used should have certain requirements. In order to increase the maximum speed, the motor should have higher instantaneous power and power density (w / kg). In order to improve the driving distance of one-time charging, the motor should have higher efficiency, and the electric vehicle works with variable speed, so the motor should have higher comprehensive efficiency of high and low speed. The speed of starting and climbing is low, but the torque is high; The torque required for normal operation is small and the speed is very high, so the typical mechanical characteristic curve of the motor used for electric vehicles is shown in the attached figure. That is to say, it has constant torque characteristic at low speed and constant power characteristic at high speed, and the running speed range of the motor should be wide. In addition, the motor should be solid, reliable and low price.
Development trend of electric vehicle motor
In the early stage of the development of electric vehicles, DC motors are mostly used. Series motors are used in the trial production of buses, and shunt and compound motors are used in passenger cars and vans. With the development of permanent magnet materials, permanent magnet DC motor is also applied. The advantage of DC motor is that it has better control characteristics. But it is heavy, low efficiency, expensive, and because of the existence of brush and slip ring, need maintenance, brush wear will cause unsafe work. Therefore, with the development of power electronic devices, AC motor is gradually mature, and DC motor is gradually replaced by AC motor. The motors in this conference are mainly AC motors.
Asynchronous motor is the first choice for its low cost, high reliability, high speed, low torque ripple / noise and no position sensor. Vector controlled asynchronous motor has become the first choice for electric vehicles because of its excellent performance. The EVL of general motors, the Ranger eV of Ford Motor Company and the electric bus of Yuanwang company all adopt asynchronous motor. Take. EVL as an example, its visibility is attached table. EVL is a commercial vehicle of “impact” concept car which caused a sensation at the 1990 Chicago Auto Expo. It can be seen that its driving range and maximum speed have reached a very high value. But at the same time, it can be seen that the motor power is very high, the battery voltage is very high, and the ratio of its performance to motor power or battery voltage is not high. This is due to the large copper loss of asynchronous motor, which reduces the efficiency. Especially at low speed, the efficiency is lower, which is its fatal weakness.
AC permanent magnet motor, represented by permanent magnet synchronous motor and brushless DC motor, is widely used in the field of electric vehicles because of its special advantages of low weight and high efficiency. The price of this kind of motor is on the high side, but with the further decline of mass production and permanent magnet material price, its price will fall. This kind of motor also has its weakness due to work.
The number of turns of primary winding should not exceed a certain value due to the limitation of power supply voltage. Therefore, it is very difficult for the motor to provide the required output power without increasing the rotation frequency and current. That is to say, if we want to provide enough output power at high speed, we must increase the current, which consumes a lot of power and reduces the efficiency; If the current is not increased, the output power will decrease and the electric vehicle will not run normally. The representative of permanent magnet synchronous motor used in this exhibition is the RAV4 eV of Toyota company of Japan.
Switched reluctance motor (SRM) has the advantages of simple structure, compactness, firmness, high efficiency, high torque at low speed, and simple driver structure. It has been predicted by experts as a black horse in the field of electric vehicles. The main disadvantages of this method are the large vibration and noise. The typical electric vehicle using switched reluctance motor in this exhibition is Fiat 500 electric vehicle of Fiat company of Italy, and its visibility is shown in the attached table. It can be seen that under a certain power, the maximum torque it can provide is larger, that is, the ratio between the maximum torque and power is larger.
It can be seen that all kinds of electric motors used in electric vehicles have their own advantages and disadvantages, so they are not completely suitable for electric vehicles. Therefore, it is still the task of the electrical workers to continue to develop the motor suitable for electric vehicles. The polymorphic motor researched by Harbin Institute of technology is such an attempt. This is a hybrid stepper motor and asynchronous motor structure in one, that is, in the traditional hybrid stepper motor rotor slot is equipped with a set of cage winding, the stator core is divided into two sections, between the two sections of the stator core is placed an axial electromagnetic excitation coil, the rest of the structure is the same as the hybrid stepper motor. When the speed is low, the power supply to the stator winding of the motor is in the form of hybrid stepping motor, and the motor operates as a hybrid stepping motor. At high speed, the power supply to the stator winding of the motor is in the form of asynchronous motor. At the same time, the axial electromagnetic excitation coil is energized to generate the axial magnetic field to demagnetize the magnetic steel, so that the magnetic steel has no or little influence on the operation of the motor. At this time, the motor operates as an asynchronous motor. In this way, the polymorphic motor has the advantages of high torque at low speed of hybrid stepping motor and high efficiency at high speed of asynchronous motor, and has high comprehensive performance at high speed and low speed and wide speed range. The ev96-1 electric car in this exhibition uses this kind of motor, which is still under development.
Development trend of driving mode
The drive system of traditional fuel vehicles includes engine, reducer and differential. This is because the speed range of internal combustion engine is narrow, so it is necessary to use reducer to expand the speed range. The differential is easy to steer. Reducer and differential are a series of transmission gears, which consume part of mechanical energy in the operation of the car, so that the power of the wheel is less than 2 / 3 of the engine power, greatly reducing the efficiency of the car. Due to the different characteristics of motor and engine, electric vehicles can adopt four driving modes: the same as traditional fuel vehicles; Omit the reducer; The differential is further omitted, and the motor drives the wheel coaxially, that is, the axle drive; The motor is directly installed in the wheel, namely wheel drive. As you can see. Wheel drive not only completely eliminates the mechanical wear in the transmission, improves the transmission efficiency, but also has the smallest volume, the lightest weight, and reduces the failure rate. Therefore, wheel drive is the best way to drive electric vehicles. There has been some research on wheel drive at home and abroad. For example, in the 26th Tokyo Motor exhibition, the IZA electric vehicle launched by Tokyo Electric Power Company adopted the four-wheel direct drive mode. Its maximum speed is 176km / h, and the driving distance for one charge is 548km (at constant speed of 40km / h). It uses nickel cadmium battery. It is the best electric vehicle at that time, which is undoubtedly related to the wheel drive mode.
- a. As the motor for electric vehicles, DC motor has been phased out.
- b. Asynchronous motor, AC permanent magnet motor and switched reluctance motor have been used to drive electric vehicles. They have their own advantages, but they also have their own weaknesses. They are not completely suitable for electric vehicles.
- c. It is the task of electrical workers to further study the motor which is more suitable for driving electric vehicles. Polymorphic motor is a promising motor.
- d. Wheel drive is the best way to drive electric vehicles.
Source: China Permanent Magnet Manufacturer – www.rizinia.com