Overview
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A permanent magnet synchronous motor rotates by converting electric energy
to mechanical energy.
The important thing when converting energy is efficiency indicated by the
power factor for the amount of current effectively used, as well as the
percentage of output versus input.
Evaluating the power factor and input/output characteristics that account
for efficiency is necessary to design a highly efficient motor.
This example presents the use of a magnetic field analysis to evaluate
the efficiency of a permanent magnet synchronous motor. |
Voltage Waveform / Current Waveform
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The U-phase for the voltage waveform and current waveform are indicated
in Fig. 1. The phases of the phase voltage and the phase current are out
of alignment as indicated in Fig.1. θ=7.74 can be obtained for the
phase difference (θ) which is called the power factor angle . The
power factor of this motor is 0.99 because the power factor is cosθ. |
Effective Power Waveform / Power Vector Plot
| The effective power waveform of the U-phase is indicated in Fig. 2, and
the power vector plot is indicated in Fig. 3.The average effective power
of the U-phase is 10.68 as indicated in Fig. 2. The apparent power and
the reactive power can be obtained from the average effective power and
power factor for the three phases and displayed in a vector plot such as
Fig. 3. |
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Output Characteristics
| The torque waveform is indicated in Fig. 4, and the output characteristics
are indicated in Table 1. The average torque is 0.15 Nm as indicated in
Fig. 4. The mechanical output of the motor is calculated by the torque
that is obtained and rotation speeds. The mechanical output is 27.95 W.
The efficiency of the motor is calculated by the effective force, mechanical
output, and the losses. The efficiency of this SPM motor is 82.41%. Furthermore,
the iron losses consumed by the coil is 3.97 W. |
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