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What is the difference between high-efficiency motors and ordinary motors

Date:2022-10-19   Author:XINDA MOTOR
Ordinary motor: The 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 the efficiency value of the motor, which is an important technical indicator of the motor. The remaining 30%- The 5% part is consumed by the motor itself due to heat generation, mechanical loss, etc., so this part of the electric energy is wasted.
High-efficiency motor: A motor with a high 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%, and the material will increase a lot, and when the motor efficiency reaches a certain value, no matter how much material is added, it cannot be improved. Most of the high-efficiency motors on the market are replacement products of three-phase asynchronous motors, which means that the basic working principle has not changed.

The high-efficiency motor mainly improves the efficiency of the motor through the following ways.
1. Increase the material: increase the outer diameter of the iron core, increase the length of the iron core, increase the size of the stator slot, and increase the weight of the copper wire to achieve the purpose of improving the efficiency. For example, the outer diameter of the Y2-8024 motor is increased from the current Φ120 to Φ130 , some foreign countries increase Φ145, and at the same time increase the length from 70 to 90. The amount of iron used for each motor increases by 3Kg. The copper wire increases by 0.9Kg.
2. Silicon steel sheets with good magnetic permeability are used. In the past, hot-rolled sheets with large iron loss were used, and high-quality cold-rolled sheets with low losses are now used, such as DW470. Even lower than the DW270.
3. Improve machining accuracy and reduce mechanical losses. Replace small fans to reduce fan losses. High-efficiency bearings are used.
4. Optimize the electrical performance parameters of the motor, and optimize the parameters by changing the slot shape.
5. Adopt cast copper rotor (complex process and high cost).
Therefore, to make a real high-efficiency motor, the design, raw materials, and processing costs are 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 involving the entire life cycle of the motor. From the design and manufacture of the motor to the selection, operation, adjustment, maintenance and scrapping of the motor, the effect of its energy saving measures must be considered from the entire life cycle of the motor. In this aspect, the main consideration is to improve the efficiency from the following aspects.
The design of energy-saving motor refers to the use of modern design methods such as optimization design technology, new material technology, control technology, integration technology, test and detection technology, etc., to reduce the power loss of the motor, improve the efficiency of the motor, and design an efficient motor.
When the motor converts electrical energy into mechanical energy, it also loses a part of the energy itself. Typical AC motor losses can generally be divided into three parts: fixed loss, variable loss and stray loss. Variable losses are load-dependent and include stator resistance losses (copper losses), rotor resistance losses, and brush resistance losses; fixed losses are load-independent and include core losses and mechanical losses.
The iron loss is composed of hysteresis loss and eddy current loss, which is proportional to the square of the voltage, and the hysteresis loss is also inversely proportional to the frequency; other stray losses are mechanical losses and other losses, including friction losses of bearings and fans, rotors and other windage losses due to rotation.

Features of high-efficiency motors

1. Save energy and reduce long-term operating costs. It is very suitable for textiles, fans, pumps, and compressors. The cost of motor purchase can be recovered by saving electricity for one year;
2. Direct start or speed regulation with frequency converter can fully replace the asynchronous motor;
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, which saves the transmission and distribution capacity and prolongs the overall operating life of the system;
6. Power-saving budget: Take a 55-kilowatt motor as an example, a high-efficiency motor saves 15% of electricity than a general motor, and the electricity fee 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 the energy-saving motor.

Advantages of high-efficiency motors

1. Direct start, the asynchronous motor can be completely replaced.
2. The rare earth permanent magnet high-efficiency energy-saving motor itself can save more than 3% of electric energy than ordinary motors.
3. 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.
4. The motor current is small, which saves the transmission and distribution capacity and prolongs the overall operating life of the system.
5. Adding a driver can realize soft start, soft stop and stepless speed regulation, and the power saving effect is further improved.