How to find the right Permanent Magnet Motors AI guide
Written by an AI model from its trained knowledge.
What the AI looks for in Permanent Magnet Motors
- DC voltage and supply
- Match the rated armature voltage (for example 12, 24, 90 or 180 VDC). 90 VDC motors usually run from 120 VAC through an SCR drive, and 180 VDC motors from 240 VAC. Overvoltage overspeeds and overheats the motor, and undervoltage leaves it short on speed and power.
- Brushed vs brushless
- Brushed PMDC motors run directly on DC. Brushless (BLDC/PMSM) motors require a matching electronic controller. A brushless motor will not run when connected straight to a battery or power supply.
- Torque and speed
- Size the motor for the continuous rated torque at your working speed, not the peak or stall torque. Running above continuous torque overheats the armature and can demagnetize the magnets.
- Gearmotor ratio
- If you need low output RPM, choose an integral gearmotor with the right ratio and output torque instead of slowing an ungeared motor electronically. Low-speed operation without gearing gives poor torque and poor cooling.
- Duty cycle and brush service
- Check the continuous or intermittent duty rating, and on brushed motors check that the brushes are replaceable. Brushes are the main wear part, and short-duty motors such as winch types fail in continuous use.
- Frame and shaft
- Match the mounting face, bolt circle and shaft diameter or keyway (many PMDC motors use 56C). This is what lets the motor fit the existing coupling or gearbox.
Brands that matter
- Leeson: Common 12/24/90/180 VDC PMDC motors and gearmotors.
- Baldor-Reliance (ABB): Industrial PMDC motors in NEMA frames.
- Bodine Electric: Fractional-horsepower PMDC and brushless gearmotors.
- Dayton: Widely stocked fractional-horsepower DC motors and gearmotors.
- Groschopp: Fractional-horsepower DC and brushless motors and gearmotors.
What to avoid
- Buying a brushless motor without a controller made for it.
- Sizing from stall or peak torque figures.
- Unbranded motors that come without a voltage, current and torque datasheet.
- Using intermittent-duty motors for continuous applications.
Questions
Can I reverse a PMDC motor?
Yes. Swapping the armature polarity reverses a brushed PMDC motor. Brushless motors are reversed through their controller.
Do I need a special drive for a 90 VDC motor?
On AC mains, yes: use an SCR or PWM DC drive rated for the motor's voltage and current.