My friend Bao asked Ms. Can: What are the secrets to high-efficiency motors ? Is it really just about using more materials? He's been in the motor sales business for many years and has never felt this much pressure recently. He clearly feels that customers are becoming increasingly demanding of motors, especially in terms of high efficiency and energy saving. It's no longer easy to just give platitudes like "using better materials" or "using more materials," since everyone is under cost pressure. Bao sought out Ms. Can to learn more about motors. High-efficiency motors are indeed more than just using more materials. To some extent, using more materials might actually be the main factor limiting efficiency improvements.
Energy and environmental pressures are forcing motors to upgrade to higher efficiency.
Energy crises and environmental issues have become barometers for the normal operation of various industries, and people are paying increasing attention to energy efficiency. Although electric motors are already highly efficient at converting electrical energy into mechanical energy, there is no end to achieving maximum efficiency. It is essential to ensure that electric motors are properly matched to their applications, while continuously optimizing designs and innovating technologies to achieve high efficiency → ultra-high efficiency → ultra-ultra-high efficiency.
How to improve motor efficiency?
Studying motor efficiency is essentially a process of analyzing various losses and understanding the key factors that affect these losses.
● Reduce losses as current flows through the windings. One of the most direct ways to improve motor efficiency is to reduce armature winding losses. For example, by increasing the slot area, more copper can be used to increase the cross-sectional area of the windings, thereby reducing their resistance and lowering losses as current flows through the windings.
● Control of core loss. Core loss is related to two main factors: magnetic flux density and frequency. Since the power supply frequency is usually fixed, the core is generally lengthened to reduce core loss.
●Efficiency improvements are closely related to material consumption. To achieve the required energy consumption level, an increase in the amount of copper and the volume of the core is unavoidable. However, a reduction in losses is not always positively correlated with an increase in copper and iron consumption. When the cross-section of the core and coil increases to a certain extent, losses may actually increase, because the increase in core volume also increases core and coil losses. If this exceeds the reduction caused by decreased resistance and core unsaturation, efficiency may actually decrease. There may be a point beyond which increasing the core volume actually increases losses. Similarly, for a given magnetic flux density, eddy current losses can be reduced by using thinner laminations.
● Technological innovation improves efficiency. Breaking through previously insurmountable technological barriers such as closed-slot rotors and cast copper rotors will lead to a qualitative leap in motor efficiency.
Improving efficiency is not as simple as using more materials.
While efficiency improvements do come at the cost of consuming more effective materials, the presence of effective materials such as copper wire and iron core inevitably leads to various losses. Under certain relatively stable conditions, the product of the loss per unit of material and the total material consumption will always have a minimum value. Achieving this minimum value or optimizing the design is a traditional method for improving efficiency. However, improving relatively stable conditions, upgrading material grades, and breaking through the bottlenecks of traditional processes rely on innovative technologies.
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