With the rapid development of power electronics technology, the application of inverter-powered AC motor variable frequency speed control technology is becoming increasingly widespread. Currently, the modulation frequency of inverters is getting higher and higher (the modulation frequency of practical ultra-quiet IGBT inverters has reached around 15kHz). With the realization of soft-switching technology, the modulation frequency of inverters will be further increased. For general sinusoidal modulation inverters, the frequency of the main harmonic components of their output is 2 to 3 times the modulation frequency. Since the inverter output usually contains considerable harmonics, it will have many adverse effects on the operation of AC motors. Different types of inverters have different effects on motors, but they will have a significant impact on the operation of squirrel-cage induction motors. It will increase motor losses, reduce efficiency, and increase temperature rise. High temperatures accelerate the volatilization and degradation of insulation, rapidly reducing dielectric strength and volume resistivity, potentially leading to insulation carbonization and loss of function. In inverter-powered motors, the magnetic field generated by harmonic currents rotates at high speed relative to the shaft, resulting in a high shaft potential that can rupture the bearing oil film, causing shaft current to flow through the bearing and damaging it (such accidents frequently occur with IGBT inverters). Due to the distributed capacitance between the motor coils, the voltage distribution among the coils is uneven when high-order harmonic voltages are input, with approximately 40% of the voltage often borne by the first coil. The insulation of this coil, subjected to such high voltage repeatedly over a long period, is prone to aging, making the first turn of the coil a frequent point of insulation damage in the motor. The output voltage amplitude of the inverter relative to ground is approximately three times the standard voltage, and the inverter voltage has a high rate of change, causing oscillations that result in high voltage stress. The motor terminal voltage will exhibit three-phase imbalance due to zero-point drift. Furthermore, the connecting cable between the frequency converter and the motor also becomes part of the system. When the switching frequency is high, the long cable will generate standing waves between the frequency converter and the motor, which will double the motor's terminal voltage. This causes the motor windings to withstand voltages higher than those supplied by the mains, and will also lead to a decrease in motor insulation. To improve the service life of the motor and ensure its reliable operation, the cable length connecting the motor and the frequency converter should be shortened for motors equipped with frequency converters. It is essential to select frequency converters that are less prone to high reflected voltage output and to use dedicated variable frequency drive motors or filters. Some of these filters are connected at the motor end, called motor-end filtering; others are connected at the inverter output end, called inverter output filtering. [b][align=center]For more details, please click: Eliminating the Influence of Frequency Converters on Motors Using Filtering Technology[/align][/b]