Energy feedback device suppliers remind you that variable frequency speed regulating motors, abbreviated as variable frequency motors, are a general term for motors driven by frequency converters. Their advantage is that they have a starting function; Adopting electromagnetic design reduces the resistance of the stator and rotor; Adapt to frequent shifting under different working conditions; To some extent, it saves energy. At present, it has become the mainstream speed control scheme and can be widely applied to various industries of continuously variable transmission.
(1) The reactance of high-speed motors is small, and high-order harmonics will increase the current value. Therefore, when choosing a frequency converter for high-speed motors, the capacity of the frequency converter should be slightly larger than that for ordinary motors. When the GD2 of the drive system is constant, the speed range of high-speed motors is wide, and the time required for acceleration/deceleration is relatively long. Therefore, the acceleration/deceleration time should be set slightly longer.
(2) When a frequency converter is used for a variable pole motor, it can be used when the speed range of the frequency converter is wider, but full attention must be paid to selecting the capacity of the frequency converter so that the maximum rated current of the motor is below the rated output current of the frequency converter. In addition, when switching the number of poles during operation, please stop the motor first. If switching is done during operation, it may cause overvoltage protection or overcurrent protection to operate, resulting in the motor idling and serious damage to the frequency converter.
(3) When driving explosion-proof motors, the frequency converter should be placed outside of hazardous areas or inside explosion-proof enclosures due to the lack of explosion-proof structures.
(4) When using a frequency converter to drive a gear reduction motor, the range of use is limited by the lubrication method of the rotating parts of the gear. At high speeds above the rated speed, there is a risk of running out of lubricating oil, so the maximum allowable speed should not be exceeded. Attention should also be paid to the noise produced by the gears.
(5) When a frequency converter drives a wound rotor asynchronous motor during operation, due to the low impedance of the wound rotor asynchronous motor, overcurrent tripping caused by ripple current is prone to occur. Therefore, a frequency converter with slightly larger capacity than usual should be selected. Generally, wound rotor asynchronous motors are often used in situations where the flywheel torque GD2 is large, and attention should be paid to the setting of acceleration/deceleration time.
(6) When driving a synchronous motor, the output capacity will decrease by 10% compared to the power frequency power supply. The continuous output current of the frequency converter should be greater than the product of the rated current of the synchronous motor and the standard value of the synchronous traction current.
(7) For loads with large torque fluctuations such as compressors and vibrators, as well as peak loads such as hydraulic pumps, if the frequency converter is determined based on the rated current or power value of the motor, there is a possibility of overcurrent protection action due to peak current. A feasible approach is to observe the current waveform during power frequency operation and select a frequency converter with a rated output current greater than its maximum current.
(8) When driving a submersible pump motor with a frequency converter, the rated current of the frequency converter should be greater than that of the submersible pump motor because its rated current is higher than that of a general motor.
(9) Single phase motors are not suitable for driving with frequency converters. When using a capacitor based single-phase motor, the capacitor may be damaged due to the effect of high-frequency current.
During the operation of the variable frequency speed regulation system, some faults may be caused by the motor. Therefore, in addition to checking the frequency converter, it is also necessary to check whether each link of the motor is normal. Attention should also be paid to the maintenance of electric motors in daily work.