(1) Basic information

(1) Basic information

Permanent magnet synchronous motors have the advantages of simple structure, small size, light weight, small loss, high efficiency, and high power factor. They are mainly used for high-performance servo drive systems and DC motors that require fast response, wide speed regulation range, and accurate positioning. Replacement motors.

(2) Product introduction

Variable frequency speed-regulating permanent magnet synchronous motors can be divided into two categories. One is a brushless DC motor whose back EMF waveform and supply current waveform are both ideal rectangular waves (actually trapezoidal waves), and the other is a permanent magnet synchronous motor in the general sense where both waveforms are sine waves. Among them, the frequency conversion speed regulation system of a brushless DC motor uses a rotor position detection device to form a closed-loop control. The position of the rotor determines the ON and OFF of the corresponding power tubes of the frequency converter, so that the output frequency of the frequency converter and the speed of the motor are always synchronized. The so-called self-controlled speed regulation system. Whenever the motor rotor turns a pair of magnetic poles, the output current of the inverter changes for exactly one cycle, and the current and the rotor are always synchronized, and there will be no out-of-step phenomenon. The frequency converter regulates speed by adjusting the input voltage of the motor. Its characteristics are similar to those of a DC motor. It also replaces the latter's mechanical commutation with electronic commutation and eliminates the brush, hence the name. Brushless DC motors are mainly used in computer parts and external equipment, household appliances, automobile parts, electric bicycles, etc.

The cast film production line mainly consists of five parts: extrusion part, casting part, corona part, winding part, and electronic control part. The DC drive motor used before the project renovation has complex structure and requirements on the environment. The speed is determined by its own structure, power supply voltage and load weight. Therefore, it is not suitable for occasions with large load changes, causing electromagnetic interference and affecting production and working conditions. The variable frequency permanent magnet synchronous motor control system adopts a variable frequency system with a wide speed regulation range, high dynamic characteristics and efficiency, so as to meet the requirements of production conditions and save energy.

(3) Product application areas

It is suitable for various fields such as fans, water pumps, metallurgy, printing and dyeing, textiles, papermaking, thermoelectric, cement, steel, various mechanical equipment, etc.

(4) Application cases

Motor power-saving renovation project of Shanghai Dahui Plastic Co., Ltd.

1) Implementation content and cycle: Replace three DC traction motors in a cast film production line of the company with three variable-frequency drive permanent magnet synchronous motors (motor powers: one set of 250kW and two sets of 75kW respectively); The project started on February 2, 2018 and was completed on July 28, 2018.

2) Energy conservation and emission reduction effect and investment payback period: The project saves 1.2388 million kWh of electricity, and the energy conservation amount is 357 tons of standard coal. Based on the enterprise's electricity purchase unit price of 0.8 yuan/kWh, the project saves 990,400 yuan annually. The investment amount of this project is 354,800 yuan, so the investment payback period of this project is 0.4 years.