10. Consider PMAC for same torque as AC Induction in a smaller, lighter motor.
Permanent Magnet AC (PMAC) motors are a growing alternative to AC Induction motors, which for decades have been the workhorse of almost any electrical motor application.
PMAC motors preserve the reliability and simplicity of the ac induction motor while offering higher efficiency, synchronous operation, and the opportunity to use a smaller frame size.
9. Use the best lamination bath impregnation process for optimum thermal management.
Impregnating stators strengthens stator winding electrical insulation, protects against chemicals or harsh environments, and enhances thermal dissipation.
Driving out air pockets from the electric winding enhances the thermal conductivityof the winding.
8. Balance at operational speeds using high standards.
Bearing vibration readings are normally taken on three planes. Vertical vibration may indicate a mounting problem. Horizontal vibration may mean a balance problem, whereas axial vibration may indicate a bearing problem.
Unbalance can also be caused by centripetal forces at the bearings.
7. Select low-friction bearings suited for application speeds.
Ball bearings are more suitable for high-speed applications than roller bearings.
Consider additional forces such as unsymmetrical air gaps causing magnetic pull, out-of-balance forces, pitch errors in gears, and thrust loads.
6. Consider rare earth versus ferrite (ceramic) magnets.
Neodymium rare earth, samarium cobalt magnets or ferrite (ceramic) magnets are used in PMAC electric motors.
Rare earth magnets are two to three times stronger than ferrite or ceramic permanent magnets but are more expensive.
Samarium cobalt magnets are optimal for high-temperature applications because of their high energy density.
5. Optimize design of rotor/stator laminations to show a sinusoidal magnetic field.
ABM synchronous motors with high-performance permanent magnets come with a sinusoidal flux distribution as well as Electro-Motive-Force.
Stator windings for distributed windings are identical to asynchronous motor windings. It results in lowered vibration, noise and maintenance cost as well as increased overall performance.
4. Select an inverter to provide sensorlessoperation & optimize programing.
PMAC drives can “self-detect” and track the rotor’s permanent magnet position. Critical for a smooth motor start and also allows for optimum torque production.
Programming the controller settings to attain optimum efficiency is becoming more and more important with the ever-increasing efficiency regulations.
3. Use high grade copper for more conductive windings and to optimize density.
Use of more copper by optimizing the stator lamination slot design increases the cross-sectional area of stator windings. This lowers resistance of the windings and reduces losses due to current flow.
A high-efficiency electric motor can have up to 20 percent more copper in the stator winding.
2. Optimize cooling fan for minimum power, while providing adequate cooling.
A cool motor runs more efficiently. To obtain the best airflow, optimize the cooling fan and fan shroud design. Assuring a tight bond between the stator and motor housing provides the best cooling performance.
- Select duty cycle for peaks/shocks in a specific time period.
What torque and speed is needed when and how often?
What are the ambient conditions such as temperature, humidity and elevation?
Even the most efficient motor will not perform to its utmost efficiency if used for the wrong application.
Choosing a Gearbox Drive and Electric Motor Supplier
When choosing manufacturing partners during a machine build, remember that there are two methods for choosing a gearbox and electric motor supplier. One is selecting a pre-engineered unit and the other is choosing a gearbox-motor combination and integrating them into the equipment.
Pre-engineered gearmotor solutions are suitable if a design engineer doesn’t have the time or engineering resources to build a gearmotor in-house — or if the design needs a quick setup. New modular approaches to support OEMs (and enable new machine tools, automation, and design software) now let engineers get reasonably priced gearmotors even in modest volumes.
Contact: Gabriel Venzin, President, ABM DRIVES INC, +1-513-576-1300, [email protected].