The armature winding is the core part of the DC motor, which is a coil of copper enameled wire. When the armature winding rotates in the magnetic field of the motor, an electromotive force is generated.

The force field that occurs around the permanent magnet or electric current and the space or the range of magnetic force that can be reached by magnetic force.

Define the magnetic field intensity of an infinite wire carrying 1 ampere current at a distance of 1/2 meter from the wire as 1A/m (Ampere/meter, SI); in the CGS unit system (cm-gram-second) In, to commemorate Oersted’s contribution to electromagnetics, the magnetic field strength of an infinite wire carrying 1 ampere of current at a distance of 0.2 cm from the wire is defined as 10e (Oersted), 10e=1/4.103/m, magnetic field Intensity is usually expressed by H.

Hold the wire with your right hand and make the direction of the straight thumb match the direction of the current. Then the direction pointed by the four curved fingers is the direction of the magnetic line of induction.

The part that does not rotate when the brush or brushless motor is working. The motor shaft of a hub-type brushed or brushless gearless motor is called a stator, and this type of motor can be called an internal stator motor.

The part that rotates when a brush or brushless motor works. The shell of a hub-type brushed or brushless gearless motor is called a rotor, and this type of motor can be called an external rotor motor.

The inside of the brushed motor rests on the surface of the inverter. When the motor rotates, the electric energy is sent to the coil through the inverter. Since its main component is carbon, it is called carbon brush, which is easy to wear. Should be regularly maintained and replaced, and clean up carbon deposits.

The mechanical guide groove that holds and maintains the position of the carbon brush in the brush motor.

In the brush motor, there are mutually insulated strip metal surfaces. When the motor rotor rotates, the strip metal alternately contacts the positive and negative poles of the brush to realize the alternating positive and negative direction of the motor coil current to complete the brush motor coil Commutation.

The arrangement order of the brushless motor coils.

Generally used to refer to magnetic materials with high magnetic field strength, and the motors all use neodymium iron rare earth magnets.

It is produced by the rotor of the motor cutting the lines of magnetic force, and its direction is opposite to the external power supply, so it is called back electromotive force.

When the motor is working, the coil and commutator rotate, but the magnet and carbon brushes do not rotate. The alternating current direction of the coil is changed by the commutator and brushes that rotate with the motor. In the electric vehicle industry, brush motors are divided into high-speed brush motors and low-speed brush motors. There are many differences between brushed motors and brushless motors. It can be seen from the words that brushed motors have carbon brushes, and brushless motors do not have carbon brushes.

Because the controller provides direct current with different current directions to achieve the alternating current direction of the coil in the motor. There are no brushes and commutators between the rotor and stator of a brushless motor.

When the brushless or brushed motor is rotating, the energization direction of the coil in the motor needs to be alternately changed so that the motor can rotate continuously. The commutation of the brush motor is completed by the commutator and the brush, and the brushless motor is completed by the controller.

The power of a motor refers to the ratio of the mechanical energy output by the motor to the electrical energy provided by the power supply.

The choice of motor rated power is a very important and complicated issue. Under load, if the rated power of the motor is too large, the motor will often run at light load, and the capacity of the motor itself will not be fully utilized and become a "big horse-drawn cart". At the same time, the motor has low operating efficiency and poor performance, which will increase Operating expenses. Conversely, if the rated power of the motor is required to be small, it is a "small horse-drawn cart". The motor current exceeds the rated current, and the internal loss of the motor is increased, and the efficiency is low. The important thing is to affect the life of the motor, even if the overload is not too much. , The service life of the motor will be reduced more; more overload will damage the insulation performance of the motor insulation material or even burn. Of course, if the rated power of the motor is small, it may not be able to drag the load at all, which will cause the It is overheated and damaged during startup. Therefore, the rated power of the motor should be selected strictly according to the operating conditions of the electric vehicle.

If the measured temperature of the motor cover exceeds the ambient temperature by more than 25 degrees, it indicates that the temperature rise of the motor has exceeded the normal range. Generally, the temperature rise of the motor should be below 20 degrees. Generally, the motor coil is wound by enameled wire, and when the temperature of the enameled wire is higher than about 150 degrees, the paint film will fall off due to the high temperature, causing the coil to short circuit. When the coil temperature is above 150 degrees, the temperature of the motor housing is about 100 degrees, so if the housing temperature is used as the basis, the maximum temperature the motor can withstand is 100 degrees.

When the motor is under load, there is power loss in the motor, which will eventually become heat energy, which will increase the temperature of the motor and exceed the ambient temperature. The value at which the motor temperature is higher than the ambient temperature is called temperature rise. Once the temperature rises, the motor must dissipate heat to the surroundings; the higher the temperature, the faster the heat dissipation. When the heat emitted by the motor per unit time is equal to the heat dissipated, the temperature of the motor no longer increases, but maintains a stable temperature, that is, in a state of heat and heat balance.

When the motor is running under load, start from exerting its function as much as possible. The larger the load, that is, the output power, the better (if the mechanical strength is not considered). But the greater the output power, the greater the power loss, and the higher the temperature. We know that the weakest thing in the motor is insulation materials, such as enameled wires. There is a limit to the temperature resistance of insulating materials. Within this limit, the physical, chemical, mechanical, and electrical properties of insulating materials are stable, and their working life is generally about 20 years. Beyond this limit, the life of the insulating material will be shortened drastically, or even burned. This temperature limit is called the allowable temperature of the insulating material. The allowable temperature of the insulating material is the allowable temperature of the motor; the life of the insulating material is generally the life of the motor.
The ambient temperature varies with time and location. When designing the motor, it is stipulated that 40 degrees Celsius is the standard ambient temperature in my country. Therefore, the allowable temperature of the insulating material or motor minus 40 degrees Celsius is the allowable temperature rise.
The allowable temperature of different insulating materials is different. According to the allowable temperature, the commonly used insulating materials for motors are A/105, E/120, B/130, F/155, H/180.

When the motor is running, if each physical quantity is the same as its rated value, it is called the rated operating state. Working under the rated operating state, the motor can run reliably and has the best comprehensive performance.

The rated torque output on the motor shaft can be expressed by T2n, which is the rated value of the output mechanical power divided by the rated value of the transfer speed, ie T2n=Pn where the unit of Pn is W and the unit of Nn is r/min 、 The unit of T2n is NM. If the unit of PNM is KN, the coefficient 9.55 is changed to 9550.
Therefore, it can be concluded that if the rated power of the motor is equal, the lower the motor speed, the greater the torque.

Generally, it is required that the starting current of the motor cannot exceed 2~5 times of its rated current. This is also an important reason why current limiting protection is used on the controller.

The supplier can reduce the cost by increasing the speed. The same is the low-speed motor. The higher the speed, the fewer coil turns, the saving of silicon steel sheets and the number of magnets. Buyers think that high speed is better.

The method of repair and treatment is generally to replace the motor or carry out repair guarantee.

The internal mechanical friction of the motor is large; the coil is locally short-circuited; the magnetic steel is demagnetized; the inverter of the DC motor is carbonized. The maintenance method is generally to replace the motor, or replace the carbon brush, and clean up the carbon deposits.

Place the multimeter in the 20A position and connect the red and black test leads to the power input of the controller. Turn on the power and record the maximum current A1 of the multimeter when the motor is not rotating. Turn the handle to make the motor run at a high speed and no-load for more than 10 seconds. After waiting for the motor speed to stabilize, start to observe and record the maximum value A2 of the multimeter at this time. Motor no-load current = A2-A1.

It is mainly the size of no-load current and running current, compared with the normal value, and the level of motor efficiency and torque, as well as the noise, vibration and heat generation of the motor. The best way is to test the efficiency curve with a dynamometer.