Generally speaking, the variable-frequency drive (VFD) will inevitably have some problems during the working process, such as vibration and noise, which are common problems in VFD work. So, what causes vibration and noise in a VFD? What is the solution to these problems? The following are the causes and treatment methods of VFD vibration and noise.

The reason for the vibration and noise is that when the VFD is working, the magnetic field generated by the high-order harmonics in the output waveform generates electromagnetic actuation force on many mechanical parts. The frequency of the actuation force is always close to or coincides with the natural frequency of some mechanical parts, resulting in resonance.

why the vfd vibrates

The high-order harmonics that have a greater impact on vibration are mainly low-order harmonic components, which have a greater impact in PAM (PulseAmplitudeModulation) mode and square wave PWM mode. However, when the sine wave PWM method is adopted, the low-order harmonic components are small, and the influence becomes smaller. When the motor is driven by a VFD, the output voltage and current contain high-order harmonic components, and the high-order harmonic magnetic flux of the air gap increases, so the noise increases. The World Network of Electromagnetic Instruments gives the following characteristics: Since the low-order harmonic components in the VFD resonate with the natural mechanical frequency of the rotor, the noise near the natural frequency of the rotor increases. The high-order harmonic component in the VFD output resonates with the bearing frame of the iron core shell, etc. , and the noise increases around the corresponding natural frequencies of these components. The noise generated by the VFD driven motor, especially the harsh noise, is related to the switching frequency of the PWM control, especially in the low frequency region. When VFD is used for speed regulation, noise and vibration will be generated, which are caused by high-order harmonic components in the VFD output waveform. As the operating frequency changes, both the fundamental wave component and the higher harmonic component change in a large range, and may resonate with various parts of the motor.

Vibration and noise treatment In order to reduce or eliminate vibration, an AC reactor can be connected to the VFD output to absorb the high-order harmonic current component in the VFD output current.

When using PAM mode or square wave PWM mode VFD, you can use sine wave PWM mode VFD to reduce the ripple torque. In order to prevent the vibration of the mechanical system composed of the motor and the load, the whole system must not resonate with the electromagnetic force generated by the motor. Generally, the following measures are adopted to suppress and reduce noise: connect an AC reactor on the output side of the VFD. If there is an electromagnetic torque margin, U/f can be set smaller. If a special motor is used, resonance with the natural frequency of the shaft system (including the load) should be checked if the amount of noise at lower frequencies is severe.

Generally speaking, the variable-frequency drive (VFD) will inevitably have some problems during the working process, such as vibration and noise, which are common problems in VFD work. So, what causes vibration and noise in a VFD? What is the solution to these problems? The following are the causes and treatment methods of VFD vibration and noise.

The reason for the vibration and noise is that when the VFD is working, the magnetic field generated by the high-order harmonics in the output waveform generates electromagnetic actuation force on many mechanical parts. The frequency of the actuation force is always close to or coincides with the natural frequency of some mechanical parts, resulting in resonance.

why the vfd vibrates

The high-order harmonics that have a greater impact on vibration are mainly low-order harmonic components, which have a greater impact in PAM (PulseAmplitudeModulation) mode and square wave PWM mode. However, when the sine wave PWM method is adopted, the low-order harmonic components are small, and the influence becomes smaller. When the motor is driven by a VFD, the output voltage and current contain high-order harmonic components, and the high-order harmonic magnetic flux of the air gap increases, so the noise increases. The World Network of Electromagnetic Instruments gives the following characteristics: Since the low-order harmonic components in the VFD resonate with the natural mechanical frequency of the rotor, the noise near the natural frequency of the rotor increases. The high-order harmonic component in the VFD output resonates with the bearing frame of the iron core shell, etc. , and the noise increases around the corresponding natural frequencies of these components. The noise generated by the VFD driven motor, especially the harsh noise, is related to the switching frequency of the PWM control, especially in the low frequency region. When VFD is used for speed regulation, noise and vibration will be generated, which are caused by high-order harmonic components in the VFD output waveform. As the operating frequency changes, both the fundamental wave component and the higher harmonic component change in a large range, and may resonate with various parts of the motor.

Vibration and noise treatment In order to reduce or eliminate vibration, an AC reactor can be connected to the VFD output to absorb the high-order harmonic current component in the VFD output current.

When using PAM mode or square wave PWM mode VFD, you can use sine wave PWM mode VFD to reduce the ripple torque. In order to prevent the vibration of the mechanical system composed of the motor and the load, the whole system must not resonate with the electromagnetic force generated by the motor. Generally, the following measures are adopted to suppress and reduce noise: connect an AC reactor on the output side of the VFD. If there is an electromagnetic torque margin, U/f can be set smaller. If a special motor is used, resonance with the natural frequency of the shaft system (including the load) should be checked if the amount of noise at lower frequencies is severe.

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