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In the energy-saving technical renovation of electric drive systems, besides optimizing the design of the drive system devices, it is essential to vigorously promote the application of variable frequency speed regulation in electric drive systems. The frequency converter is a nonlinear device, and its operation inevitably generates high-order harmonics. When the frequency converter supplies power to the driven motor, it inevitably inputs harmonic currents rich in high-order components into the motor, thereby causing adverse effects on the motor. Therefore, when implementing variable frequency speed regulation technical renovation in electric drive systems, corresponding measures should be taken to eliminate the adverse effects of harmonics on the motor. Achieving variable frequency speed regulation for asynchronous motors has been the "world dream" that people have eagerly awaited since the invention of the asynchronous motor a century ago. Through the unremitting efforts of scientific and technical personnel, its speed regulation characteristics are by no means inferior; compared with DC speed regulation systems, it even surpasses DC speed regulation in some aspects. Since frequency itself is a digital quantity, it is possible to obtain very hard mechanical characteristics without the need for external feedback. It also has advantages such as high speed regulation accuracy, smoothness, stable performance, simple maintenance, and easy realization of automatic control in the production process. The asynchronous motor drive system can implement variable frequency speed regulation technical renovation without replacing the original motor, that is, by connecting a corresponding type of frequency converter between the motor and the power supply, the best speed regulation effect can be achieved. The low failure rate of the drive system is attributed to the simple structure of the asynchronous motor, where the electrical power in the rotor circuit does not need to be supplied externally, resulting in very low probability of failures. If the asynchronous motor adopts full-voltage direct starting, its starting current can reach 5-7 times the rated current, which will inevitably cause adverse effects on the drive system or the power grid. However, with variable frequency speed regulation starting, the starting current generally does not exceed 1.5 times the rated current. At the same time, the starting is smooth, without impact, achieving a true soft start for the asynchronous motor. The variable frequency speed regulation technology used in fans and pump loads can not only achieve speed adjustment according to load operation requirements but also has very low vibration and mechanical noise during the starting process. When variable frequency speed regulation is used in the electric drive of general production machinery, there is no vibration or impact during starting, stopping, deceleration, acceleration, and other working conditions, thereby extending the service life of equipment. The variable frequency speed regulation technology applied in the energy-saving renovation of conveyors, during operation, if the load needs to accelerate or decelerate, it has a good soft start effect and achieves smooth torque. Especially when starting under heavy load conditions, it can increase the output torque, which is an effect that ordinary starters cannot achieve. Asynchronous motors, due to their simple structure, reliable operation, and convenient maintenance, are widely used in electric drives in industrial and mining enterprises. Implementing variable frequency speed regulation technical renovation for asynchronous motors in electric drive systems can achieve speed adjustment without replacing the original motor. However, because the frequency converter is a nonlinear device, it will generate high-order harmonics during operation, which will inevitably have adverse effects on the driven motor, so corresponding measures must be taken to prevent them. Asynchronous motors designed according to conventional standards are usually designed to operate at rated frequency and rated voltage. Only when operating at rated frequency and voltage can the motor ensure that the output torque and power on the motor shaft reach the rated design values. However, for asynchronous motors operating under variable frequency speed regulation conditions, since the supply frequency is a variable, when selecting the capacity of the driven motor under different working conditions, this influencing factor must be fully considered. Commonly used asynchronous motors, when operating under rated power and temperature rise conditions, will not have their operating temperature exceed the design value. However, in variable frequency speed regulation drive systems, because the current input to the motor contains rich high-order harmonics, the harmonic currents cause additional losses in the motor. Even when operating at rated frequency for a long time, the influence of harmonic currents can cause abnormal conditions such as reduced output torque, decreased efficiency, and increased temperature rise. During the operation of asynchronous motors, if the temperature rise increases, it will accelerate the volatilization and degradation of coil insulation, reduce dielectric strength and volume resistivity, and may also cause carbonization of coil insulation and loss of insulation function. In asynchronous motors in variable frequency speed regulation drive systems, due to the influence of high-order harmonics, the magnetic field generated by harmonic currents rotates at high speed relative to the shaft, producing relatively high shaft potential, which may break down the bearing oil film, causing shaft current to flow through the bearings and cause harm to them. There are distributed capacitances between the coils of asynchronous motors. When high-order harmonic voltages are input, the voltage distribution among the coils is uneven, which often accelerates the insulation aging of coils bearing high voltage, making the first-turn coil the insulation damage point. In variable frequency speed regulation drive systems, the amplitude of the output voltage of the frequency converter is more than 3 times the standard voltage, and coupled with the high voltage change rate (du/dt) of the frequency converter, the oscillation it causes will make the stress on the motor greater, inevitably causing harm to the coils. Under conditions of very high switching frequency, if the connecting cable between the frequency converter and the motor is too long, standing waves will be generated, causing the motor terminal voltage to rise, resulting in the motor coils withstanding a terminal voltage higher than the grid voltage, which will inevitably accelerate the aging of coil insulation and affect the service life of the motor. To improve the operating efficiency of asynchronous motors in variable frequency speed regulation drive systems, it is necessary to use harmonic technology to eliminate harmonic effects. Harmonic filters connected at the motor input end are called motor terminal filters; those connected at the frequency converter output end are called frequency converter output filters. Motor terminal filters are divided into first-order RC series type and first-order RC parallel type filtering methods. That is, the neutral point of the star-connected resistor-capacitor circuit is connected to the neutral point of the DC bus of the frequency converter. This filter has small size, low loss, low cost, and is worth promoting; 3.1.4 LC and RLC two-stage series frequency converter output filters. Working principle of cable detector Shorten the length of the connecting cable between the frequency converter and the motor to avoid the impact caused by standing waves. Do not coil the excessively long part of the connecting cable into a circle and place it inside the frequency converter cabinet; this treatment method is not good and will still cause harmonic interference. Secondly, the incoming line of the frequency converter can be placed in a metal corrugated pipe of m, with the outer shell of the pipe well grounded, which is also a measure to suppress harmonic interference. In addition, the control lines of the frequency converter can be shielded, and the shielding layer should be well grounded, which can also prevent harmonic interference. When implementing variable frequency speed regulation technical renovation, to improve the operating efficiency of the electric drive system, a frequency converter that is not prone to outputting high reflected voltage should be selected. If the driven motor needs to be replaced, a motor specially driven by a frequency converter should be selected.