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Traction motor for electric vehicle： induction motor, permanent magnet motor, who is the future direction?

In the era of fuel cars, we often hear the battle between natural inspirations and turbocharged engines. And in the era of electric cars, there is also a clear debate between electric motors. After the test of the market, there are two kinds of mainstream electric motors on the market at present, one is induction motor (also known as asynchronous ac motor), the other is permanent magnet motor. Induction motor is a kind of motor which has the rotor rotation powered by magnetic torque created by the physical interaction of stator winding magentic field and the induction current generated rotor magnetic field. Tesla Model S and Model X are representatives of induction motor applications. The permanent magnet motor mainly refers to the permanent magnet synchronous motor, and the biggest difference with the induction motor in structure is that the rotor is permanent magnet structure, rather than wound by the electric coil. Which is better, the induction motor or the permanent mag
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Brief introduction to electric cars

Electric car is a kind of electric vehicle. It refers to the car which is provided with full or partial power by on-board power supply and driven by electric motor to drive the wheel, meeting various requirements of road traffic and safety laws and regulations. This paper focuses on the composition, basic parameters and functions of several key components of pure electric vehicles, and briefly introduces the driving mode and classification of hybrid electric vehicles and fuel cell electric vehicles, striving to be easy to understand. Definition of battery electric vehicle Battery electric vehicle refers to the vehicle fully powered by on-board power supply and driven by electric motor to drive the wheels. Battery electric vehicle basic composition Battery electric vehicle mainly consists of three parts: power supply system, electric drive system and auxiliary system. When the car is running, the electric energy (current) output by the power battery drives the motor
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The general tests of electric motors：3

3. Voltage withstand test of the motor: Ac  voltage withstand test is the most direct method to identify the insulation strength of electrical equipment. It is of decisive significance to judge whether the electrical equipment can be put into operation. It is also an important means to ensure the insulation level of equipment and avoid insulation accidents. After the insulation treatment between the stator windings and each phase and the housing, the motor should be able to withstand a certain voltage without being broken down. Ac  voltage withstand test is the most direct method to identify the insulation strength of electrical equipment. It is of decisive significance to judge whether the electrical equipment can be put into operation, because ac voltage withstand test can fully reflect the actual situation of electrical equipment operating under ac voltage, and can truly and effectively find insulation defects. Ac  voltage withstand test is a destructive test, compressi
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The general tests of electric motors：2

2. Determination of dc resistance of winding: 1) Significance of dc resistance measurement: The dc resistance of the windings in cold state is one of the main parameters of three-phase asynchronous motors. By comparing the measured value of the resistance of the windings with the design value, it is possible to check whether the windings have broken wires and short-circuit between turns, whether the welding parts have virtual welding or open welding, whether the contact points have bad contact and other phenomena. 2) Dc resistance measurement method: Measuring the dc resistance of the motor should be done when the winding is cold. First, place the motor indoors for a period of time, and measure the temperature of the motor winding end or core with a thermometer. At this time, the measured temperature is the actual temperature of the winding in the cold state. If the temperature of the winding end or core cannot be measured, the temperature of the housing may be substituted
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The general tests of electric motors：1

The comprehensive inspection and maintenance of the motor not only includes the routine motor cleaning, the measurement of tolerance , the replacement of bearings, the inspection of leads, but also includes some test items. Below I make a simple summary of the general test items of the motor. The inspection test items of three-phase asynchronous motor include: insulation resistance measurement, winding dc resistance measurement, voltage withstand test and no-load test, etc. 1. Measurement of insulation resistance: Measuring the insulation resistance between each phase winding and each phase winding on the housing is the most convenient and non-destructive inspection of insulation.Though these inspection, it detect whether the winding insulation is seriously affected by moisture or has serious defects. The following defects can also be found effectively: the overall insulation quality is poor; Insulation become damp; There are penetrating conductive channels between the
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Interpretation of the standard of motor working system

1. Interpretation of the standard of motor working system The operating system of the motor indicates the permissible cycle time of the motor under different loads. The classification of the working system of the motor is the description of the load bearing condition of the motor, which includes the starting, electric braking, no-load, break-energy stopping and the duration and sequence of these stages. Iec60034-1 divides the working system into 10 categories. (1) continuous operation, S1. Continuous running S1 is an operation with constant load that lasts long enough to achieve thermal equilibrium. (2) short run, S2. A short run is a run with a load that is too short to achieve thermal balance. The interval (no voltage applied on the motor) is very long, which has actually reduced the motor temperature to the temperature of the cooling medium. The recommended duration of short operation is 10min, 30min, 60min and 90min. (3) start intermittent operation with no influ
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