What are the differences between high-efficiency motors and ordinary motors? What's so expensive?

Ordinary motor: A motor is a device that converts electrical energy into mechanical energy. 70%-95% of the electrical energy absorbed by the motor is converted into mechanical energy. This is often referred to as the efficiency value of the motor. It is an important technical indicator of the motor, and the remaining 30%- The 5% part is consumed by the motor itself due to heat generation, mechanical loss, etc., so this part of the electrical energy is wasted.

 

High-efficiency motor: A motor with a higher power utilization rate is called a high-efficiency motor, or "high-efficiency motor" for short.

 

For ordinary motors, it is not easy to increase the efficiency by 1 percentage point. Materials will be added a lot, and when the efficiency of the motor reaches a certain value, no matter how much material is added, it cannot be improved. Most of the high-efficiency motors on the market today are updated products of three-phase asynchronous motors, which means that the basic working principle has not changed.

 

High-efficiency motors mainly improve the efficiency of motors through the following ways.

 

1. Increase materials: increase the outer diameter of the iron core, increase the length of the iron core, increase the stator slot size, and increase the weight of the copper wire to achieve the purpose of improving efficiency. For example: the Y2-8024 motor increases the outer diameter from the current Φ120 to Φ130 , some abroad have increased Φ145, and at the same time increased the length from 70 to 90. The amount of iron used in each motor increases by 3Kg and the copper wire increases by 0.9Kg.

2. Use silicon steel sheets with good magnetic permeability. In the past, hot-rolled sheets with large iron losses were used, but now high-quality cold-rolled sheets with low iron losses, such as DW470, are used. Even lower DW270.

3. Improve processing accuracy and reduce mechanical losses. Replace small fans to reduce fan losses and use high-efficiency bearings.

4. Optimize the electrical performance parameters of the motor and optimize the parameters by changing the groove shape, etc.

5. Use cast copper rotor (complex process and high cost).

 

Therefore, to make a truly high-efficiency motor, the cost of design, raw materials, and processing is much higher, so that electricity can be converted into mechanical energy to the greatest extent.

 

Energy-saving measures for high-efficiency motors

 

Motor energy saving is a systematic project that involves the entire life cycle of the motor, from motor design and manufacturing to motor selection, operation, adjustment, maintenance, and scrapping. The effect of energy-saving measures must be considered from the entire life cycle of the motor. Domestic Externally, we mainly consider improving efficiency from the following aspects.

 

The design of energy-saving motors refers to the use of modern design methods such as optimized design technology, new material technology, control technology, integration technology, and test and detection technology to reduce the power loss of the motor, improve the efficiency of the motor, and design an efficient motor.

 

While the motor converts electrical energy into mechanical energy, it also loses a part of its energy. Typical AC motor losses can generally be divided into three parts: fixed loss, variable loss and stray loss. Variable losses change with load and include stator resistance losses (copper losses), rotor resistance losses and brush resistance losses; fixed losses have nothing to do with load and include iron core losses and mechanical losses. Iron loss is composed of hysteresis loss and eddy current loss, which is proportional to the square of the voltage, and hysteresis loss is also inversely proportional to frequency; other stray losses are mechanical losses and other losses, including friction losses of bearings and fans and rotors. etc. Windage losses due to rotation.

 

Characteristics of high-efficiency motors

1. Save energy and reduce long-term operating costs. It is very suitable for use in textiles, fans, water pumps, and compressors. The purchase cost of the motor can be recovered by saving electricity in one year;

2. It can be started directly or adjusted with a frequency converter, and the asynchronous motor can be fully replaced;

3. The rare earth permanent magnet high-efficiency energy-saving motor itself can save more than 15℅ of electric energy than ordinary motors;

4. The power factor of the motor is close to 1, which improves the quality factor of the power grid without adding a power factor compensator;

5. The motor current is small, saving power transmission and distribution capacity and extending the overall operating life of the system;

6. Energy-saving budget: Taking a 55-kilowatt motor as an example, a high-efficiency motor saves 15% more energy than an ordinary motor. The electricity cost is calculated at 0.5 yuan per kilowatt hour. The cost of replacing the motor can be recovered by saving electricity within one year of using an energy-saving motor.

 

Advantages of high-efficiency motors

˙Direct start, asynchronous motor can be fully replaced.

˙The rare earth permanent magnet high-efficiency energy-saving motor itself can save more than 3% of electric energy than ordinary motors.

˙The power factor of the motor is generally higher than 0.90, which improves the quality factor of the power grid without adding a power factor compensator.

˙The motor current is small, saving power transmission and distribution capacity and extending the overall operating life of the system.

˙Adding a driver can realize soft start, soft stop, and stepless speed regulation, further improving the power saving effect.