The main advantages of the motor variable frequency speed regulation system are:

1. The speed regulation power is high, and the characteristic of variable frequency speed regulation is that after the frequency changes, the motor still operates near the synchronous speed of that frequency, basically insisting on an additional slip rate and not adding slip loss. The loss during variable frequency speed regulation is only due to the current loss occurring in the variable frequency equipment, as well as the increase in motor losses and corresponding power reduction caused by the influence of high-order harmonics. So variable frequency speed regulation is an efficient speed regulation method.

2. The speed regulation scale is wide, usually up to 10 Yi 1 (50 Yao 5 Hz) or 20 Yi 1 (50 Yao 2.5 Hz). And it has a high power turbidity V among all speed regulation scales. So the variable frequency speed regulation method is suitable for loads with a wide speed regulation scale and often operating at low speeds.

3. When necessary, the frequency conversion equipment can be shut down and powered directly by the power grid. This is very beneficial for the safe and economical operation of pumps or fans. If the frequency conversion equipment malfunctions, it will shut down without affecting the continuous operation of the pump and fan; For example, when operating near an additional frequency (50 Hz), the economy of speed regulation by frequency conversion equipment is not high. The frequency conversion equipment can be taken out of operation and directly powered by the power grid, using conventional methods such as saving.

4. Variable frequency equipment can also serve as a soft starting device, and through the frequency converter, the motor can be continuously lubricated and accelerated from zero speed to full speed operation. Variable frequency soft start is currently the best soft start method, and variable frequency drive is currently the best soft start equipment.

The main disadvantages of the motor variable frequency speed regulation system are:

1. Now, there are two primary questions regarding the promotion and application of variable frequency speed regulation skills in high-voltage and large capacity transmission. One is that the supply voltage of auxiliary motors in Chinese power plants is high (3 to 10 kV), and the voltage withstand level of power switchgear is not sufficient, resulting in voltage matching issues; Another issue is that high-voltage and high-power variable frequency speed control equipment has high skill content and difficulty, resulting in high investment. However, energy-saving renovations of fans and water pumps usually require low investment and high returns, which raises questions about economic benefits. These two questions are the primary obstacles to its application in wind turbine and water pump speed regulation and energy saving.

2. Due to the fact that the current waveform output by the current type frequency converter and the voltage waveform output by the voltage type frequency converter are both non sinusoidal waveforms, high-order harmonics can have various adverse effects on the motor and power supply. If the additional losses and temperature rise of the motor are increased, then the power and power factor of the motor are reduced, the output is limited, the noise is increased, and the interference with wireless communication is increased. Together, high-order harmonics can cause torque pulsation in electric motors, with a pulsation frequency of 6gf (k=1, 2, 3...).

When the torque pulsation frequency is low and close to the natural frequency of the equipment system, resonance may occur. Therefore, it is necessary for the equipment system to pay attention to preventing operation near the resonance point. If a PWM frequency converter or a current type and voltage type frequency converter with multiple skills is selected, the output waveform will be greatly improved and high-order harmonics will be greatly reduced, so this question can be greatly improved.