aa.rar_magnet_永磁电机_永磁直流电机_电机_直流电机

Ansoft RMxprt Application Note

Application Note AP064-9911

A Permanent Magnet DC Motor Problem

This application note describes how to set up, solve, and analyze the results of a two-pole 75-watt DC

brush-type motor using RMxprt. You will then use the results from RMxprt as a basis for performing a

more detailed analysis in the finite element time transient solver, EMpulse.

RMxprt uses a combination of electric and magnetic circuit equations to predict the performance of this

permanent magnet DC motor. EMpulse uses the time domain finite element method, coupled with the

These projects were created using version 3.0 of RMxprt and version 8.0 of Maxwell 2D.

Page 2 A Permanent Magnet DC Motor Problem

General Data

Use the General window to specify the motor characteristics.

➤ Define the general data:

1. Enter 0.075 kW in the Rated Output Power field for this two-pole motor.

2. Enter 12 V in the driving DC Rated Voltage field.

3. Enter 2 in the Number of Poles field.

4. Enter 2400 rpm in the Given Rated Speed field.

5. Optionally, you can enter the Friction Loss as a lumped parameter value, or allow it to be

calculated according to the brush pressure. Allow RMxprt to calculate the friction loss due to

Use the Rotor1 and Rotor2 windows to define the rotor data.

Define the General Rotor Data

Use the Rotor1 window to define the number of slots and the diameter of the rotor.

➤ Define the general rotor data:

1. Select 2 as the Slot Type. This corresponds to a slot shape with a tapered neck that has a round

bottom.

2. Enter 9 mm in the Inner Diameter field.

3. Enter 55 mm in the Outer Diameter field.

4. Enter 12 in the Number of Slots field.

5. Enter 0 in the Skew Width field. The stator lamination is a straight stack without any skew.

• Enter 8.6 in the Br1 field.

• Enter 4.0 in the Br2 field.

A Permanent Magnet DC Motor Problem Page 3

Define the Rotor Slots and Wires

Use the Rotor2 window to define the rotor slots and wires.

➤ Define the rotor slots:

Page 4 A Permanent Magnet DC Motor Problem

12. Enter 5 in the Coil Pitch field. Even though RMxprt assumes there are two layers of conductors,

a rotor that uses only one layer can still be modeled by making the coil pitch full instead of

fractional. A full pitch for this motor would be 6 slots (12 slots/2 poles); instead of a full pitch,

this motor is wound one slot short, or 5 slots, and is a lap-type winding.

13. Enter 2 in the number of Wires per Conductor field.

14. Enter 0.09 mm in the Wire Wrap field as the thickness of the insulations. This refers to the

width of the insulation on both sides of the wire.

15. Enter 0.95 in the Wire Diameter field. This number is not a standard AWG value, so you must

enter it in the field, rather than selecting an available value from the pull-down menu. When

entered in the Wire Wrap field in the Rotor2 window overrides the value in this wire table.

A Permanent Magnet DC Motor Problem Page 5

Use the Stator Pole window to define the stator data.

➤ Specify the stator: