How to energy-saving motor

Although can awaken people in environmental protection and public attention, but for business decision is pale. Companies to buy and install the motor needs to be a better business case, try to save electricity in order to make the project more cost-effective. Installation of more energy-efficient motor to reduce the energy consumption can well meet the demands. America's new motor efficiency standards have since December 19, 2010, using energy-saving motor has become a rule.

When it comes to energy saving motor, you must understand what the word actually means with rotor field winding and the traditional structure of the motor. Rockwell Automation company Kinetix Motion Control of the global product manager David Hansen said: "the induction motor is used as the standard of energy efficiency, energy efficient, ultra-high efficiency, such as different types, and the permanent magnet motor is can't."

Due to the need for additional power to create the stator magnetic field, so the structure of permanent magnet motor has higher efficiency naturally. BaldElectric ac motor, a senior product manager John Malinowski said: "the ac induction motor has a whole family of products, in line with the NEMA ultra-high energy efficiency NEMA MG 1 table 12-12 and 12-13 in the requirements and the standard of IEC 60034-30 IE3 grade requirements."

Because of that, we will discuss only with ferromagnetic core and induction motor stator coil, for energy efficiency characteristic of permanent magnet motor, we will discuss later.

Malinowski continued: "ultra high efficiency motor tolerance is smaller than the old motor, less heat, less vibration, quieter, more durable." And Bosch Rexroth company industry manager Peter Fischbach says: "today's high efficiency of ac induction motor is through the use of the new type of slotting and winding geometry, better core materials and copper rotor to improve the energy conversion path and physical properties."

What makes the motor is more efficient?

Malinowski said: "the key to higher efficiency is to reduce wear and tear. Copper can reduce the loss of the stator coil to use more higher level of core silicon steel can reduce iron core loss. Less loss means that the electricity required to refrigeration is lower, this also reduces the wear and tear." Fischbach added: "the loss occurs mainly on the stator and rotor of the conduction loss and the loss of core itself, the loss is also called core loss or hysteresis loss"

Hansen, lists some design method, can make the motor energy-efficient:

-- with the increase of winding resistance, winding resistance motor efficiency is reduced. In order to maximize the efficiency of motor, the motor designers by maximizing the stator slot filling quantity (copper in stator slot winding) and minimize the terminal coiling radius (slot motor copper winding number) in order to maximize the efficiency of the motor.

Laminated material, size and material properties of core loss and stator iron is directly related to the quality of the lamination. And, more thin laminated thick laminated stator core with lower losses.

Lamination tooth geometry - lamination tooth geometry to affect motor internal magnetic flux density. Can provide higher magnetic flux density of the tooth geometry can reduce the stray loss, and thus improve energy efficiency.

System is the key

Fischbach suggest a way: "most of factory automation and industrial application is the purpose of efficiently using energy, with the highest output. So before buying motor such as stand-alone equipment, analysis, modeling, optimization of the whole system is very necessary."

Malinowski agrees: "using better motor replace the low efficiency of motor is very easy, but not necessarily can obtain higher efficiency. Efficiency of motor is 90% and from 95% to 90% of energy efficiency - spiral bevel reducer collocation use umbrella can obtain very high energy efficiency, but with only 50% to 60% of the secondary gear system with use effect is not ideal."

Fischbach agrees: "energy efficiency is a relative concept, because we have to consider energy-efficient equipment the influence factors of energy efficiency of the whole system, such as cycle time or production. For example, if you do not use the low efficiency of driving gear, gear box, for example, a 80% energy efficiency than 95% efficiency of servo motor direct driving torque motor is more energy-efficient, more can improve production."

Don't do these things

Fischbach warned: "engineers have made the biggest mistake is to only pay attention to the efficiency of the motor nameplate, also can achieve similar efficiency for specific application."

Different machine has different characteristics, and must be compatible with a particular application, to make energy efficient motors. More expensive high efficiency ac induction motor, for example, if the long-term work under male child or light condition does not save energy.

Malinowski provides a use of a new super high efficiency and energy saving motor to replace a example of centrifugal pump on the old motor. The impeller size may be designed according to the old motor speed, and higher efficiency of the new motor under the same load is likely to have higher speed, leading to higher energy consumption. The whole system may have a higher energy efficiency, but provided by the additional rotation speed is useless.

Hansen said: "to improve the design efficiency is concerned with researchers change will not take it for granted to a motor, but from the whole equipment design global considerations. If connected to the poor design of the mechanical system, even a perfect energy efficiency of the motor can't bring a lot of energy saving. In between the motor and load any mechanical transmission equipment inevitably have lower energy efficiency. The highest precision planetary gear retarding mechanism, when a new is only 90% to 95% with the highest efficiency. Worm worm gear reducer efficiency is lower, only 50% to 60%."

He concluded: "the ultimate solution is to enhance the efficiency of the equipment does not use any mechanical drive mechanism, and the use of direct drive permanent magnet servo motor."