What should I do when the high voltage motor whispers at high frequency?
The output cable contains a considerable amount of high-order wave voltage and current, so that the jade of the input of the motor is distorted, and the high-order wave of the stator and rotor electromotive force is further increased. As a result, the electromotive force is severely distorted, and the steering motor coil is severely heated and insulated. Or even penetrate.
In addition, due to the high-order harmonic generated by the high-order harmonics, the magnetic field generates an additional torch, which causes the motor to generate significant vibration and sharp noise. Higher harmonics greatly shorten the mechanical life and insulation life of the motor.
The harmonic output of the inverter is the main cause of the high-frequency howling of the motor. When the modulation pulse frequency of the power switch of the inverter is increased, the current that can be output is closer to the sine wave, which increases the frequency of the howling sound through the human ear. The audible sound wave range will greatly reduce the howling, but when the switching frequency of the IGBT is too high, the loss on the IGBT will increase. At this time, the inverter needs to be derated. When the switching frequency of the general IGBT is 4Khz, if the howling is heard, it is recommended to increase the switching frequency of the IGBT appropriately. Now the whistling sound of the high-voltage motor in operation often gives people an illusion, which is thought to be caused by frequency converter frequency modulation, but it is not necessarily. You should first confirm the source of the howling and then deal with it.
In one step, the inverter adopts V/F control to run the motor to high speed;
Two steps, operate the inverter's OFF2, free stop;
In three steps, the motor is discriminated as the speed decreases during the free stop process.
If the howling or vibration still exists, there is no control of the inverter. It is a problem in the production of the motor. There is a resonance point in the mechanical transmission. The explanation is a problem of mechanical manufacturing, not an electronic control problem.
If the motor runs smoothly during the free stop process, there is no howling, which is the problem of the control of the annoyed device. By adjusting the control parameters of the inverter, it can be solved. It is very important that the inverter is used to calculate the dynamic and static mathematical models of the motor. If the mathematical model established by the inverter is accurate, the running quality is good. Control the motor, its electromagnetic noise is fully acceptable. There is no doubt about it.
Knowledge extension Inverter and motor matching problems Choosing the right frequency converter for the entire motor motion system is a headache for engineers. In general, the selection of the frequency converter should be considered according to the type of the controlled object, the speed regulation range, the static speed accuracy, the starting torque, etc., so that it can be used and economical while satisfying the process and production requirements. .
The general experience is: how big a motor is to choose a large frequency converter, and sometimes a larger size. The high-power inverter has a low power factor, and an AC reactor is installed at the incoming end of the inverter. One is to increase the power factor, and the other is to suppress high frequency harmonics.
If the brake is frequently started, brake, install the brake unit and the brake resistor. If you need to reduce the noise, you can choose water-cooled inverter; if you need braking, you need to choose brake chopper and braking resistor, or you can choose four-quadrant products, you can feed back energy to the grid, save energy; For DC power supply, you can choose a simple inverter product (using DC power) to drive the motor.
The basis for selecting the inverter is that the current curve of the inverter includes the current curve of the mechanical load.