In-wheel motor technology is also known as wheel-mounted motor technology. Its biggest feature is the integration of power, transmission and braking devices into the wheel hub, thus greatly simplifying the mechanical parts of electric vehicles. In daily life, the hub motor will generate heat, mainly due to the following situations
1. The load of the hub motor is too large
Since the load power of the wheel hub motor is basically constant, when the voltage is higher than 10% of the rated value, the magnetic field strength of the stator and rotor will increase, and the motor will be overloaded. Or the bearing of the motor is broken, which increases the load of the motor, causing the temperature of the motor to rise and the hub motor to generate heat.
2. Problems with the motor wiring system
The welding of the lead wire of the hub motor with this wire, the connection of the lead wire and the terminal, the diameter of the lead wire core, etc., may cause the wiring system to heat up, and directly affect the temperature of the hub motor winding, thereby affecting the motor heating. When this kind of problem is more serious, it will cause partial burnout of the motor in a short time, or it may spread directly to the stator winding.
3. Rotor defects cause heating
This problem mostly occurs in in-wheel motors with relatively large power and relatively long rotors. It is due to the casting defects of the motor rotor itself, such as thin or broken bars on the rotor guide bar. The rotor will generate severe heat and heat during the operation of the motor. It will naturally spread to the hub motor, which will cause the hub motor to heat up.
4. Problems with motor bearing system
Under normal circumstances, the temperature of the hub motor bearing system is controlled at a relatively stable limit, generally controlled at 95 degrees. The actual inspection process found that when the temperature of the bearing system is high, its heat will also be conducted to the hub motor and the winding temperature When it rises, it will adversely affect the bearing system. The superposition of the two problems will cause problems in the motor in a short time.
5. Poor or invalid grease
Poor or ineffective grease can also easily cause the in-wheel motor to heat up. Except for wheel hub motors running in special high-temperature environments, most motors operate at temperatures below 70 degrees. If the grease is poor or fails, they will face the problem of excessively high temperature of the hub motor, which will cause the bearing to fall apart and lock up.
6. Sweeping the bore of the stator and rotor
In the normal operation of the in-wheel motor, the air gap between the stator and the rotor should be kept in a relatively uniform and stable state, and for some reasons (such as bearing system problems, debris problems) there is a virtual or real friction between the stator and the rotor. This is what we call the sweeping bore. At this time, the friction part will heat up, causing the temperature of the motor winding to increase from a local to an overall increase.
7. Poor heat dissipation of the motor
In most cases, the supporting equipment will meet the heat dissipation environment necessary for the operation of the in-wheel motor, and sometimes the wheel hub motor may be in an airtight environment, or the environment may be too small, and the heat emitted by the motor cannot be exchanged. Naturally, the temperature rise of the motor is increased. Another situation is that the heat dissipation of the hub motor is damaged, or the heat dissipation air duct is blocked, resulting in poor heat dissipation and heating of the hub motor.
8. The quality of the motor itself
In order to save costs, some manufacturers will reduce the number or size of radiating ribs, resulting in a reduction in the radiating area of the motor, and producing unqualified in-wheel motors. This is also an unavoidable problem. Or the foundation of the wheel hub motor is not firmly installed, causing vibration and heating of the friction sassafras.