Causes and treatment methods for vibration and noise generated by the inverter
There are also some problems in the process of the inverter. For example, vibration and noise are the problems that often occur when the inverter is working. What is the cause of vibration and noise in the inverter? What are the problems? The solution is to introduce the causes and treatment methods of vibration and noise generated by the inverter.
The reason for vibration and noise is that when the inverter is working, the magnetic field caused by the higher harmonics in the output waveform generates electromagnetic force for many mechanical components. The frequency of the power can always be close to or coincide with the natural frequency of some mechanical components. Causes resonance.
The higher harmonics that have a large influence on the vibration are mainly lower harmonic components, and have a greater influence in the PAM (Pulse Amplitude Modulation), the pulse amplitude modulation method and the square wave PWM mode. However, when the sinusoidal PWM method is used, the low-order harmonic components are small and the influence is small. When the inverter is used to drive the motor, since the output voltage and current contain higher harmonic components, the higher harmonic flux of the air gap increases, so the noise increases. The electromagnetic noise instrumentation world network gives the following characteristics: Since the low-order harmonic component in the inverter output resonates with the rotor’s inherent mechanical frequency, the noise near the natural frequency of the rotor increases. The higher harmonic components in the inverter output resonate with the core housing and the like, and the noise near the respective natural frequencies of these components increases. The noise generated by the drive motor of the inverter, especially the harsh noise, is related to the switching frequency of the PWM control, especially in the low frequency region. Using frequency converter speed regulation will generate noise and vibration, which is the influence of high harmonic components in the output waveform of the inverter. As the operating frequency changes, the fundamental component and the higher harmonic components all vary over a wide range, which is likely to cause resonance with various parts of the motor.
Vibration and noise processing methods to reduce or eliminate vibration, you can connect the AC reactor on the output side of the inverter to absorb the higher harmonic current components in the inverter output current.
When using the PAM mode or the square wave PWM mode inverter, the sine wave PWM mode inverter can be used instead to reduce the ripple torque. In order to prevent the vibration of the mechanical system connected to the motor and the load, the entire system must not resonate with the electromagnetic force generated by the motor. The following measures are generally used to suppress and reduce noise: an AC reactor is connected to the output side of the inverter. If the electromagnetic torque has a margin, the U/f can be made smaller. When using a special motor, such as when the noise level of the lower frequency is more serious, check the resonance with the natural frequency of the shaft system (including the load).