508183-01
Issue 2114
Page 11 of 52
Motor speed is determined by the size of the electrical pulse sent to
the motor windings. The longer the pulse, the faster the motor.
One revolution
HIGH SPEED COOL (output from controller to motor windings)
WINDING #1
WINDING #2
WINDING #3
LOW SPEED HEAT/COOL (output from controller to motor windings)
HIGH SPEED HEAT (output from controller to motor windings)
O volts
325VDC
One revolution
O volts
325VDC
O volts
325VDC
WINDING #1
WINDING #2
WINDING #3
O volts
325VDC
O volts
325VDC
O volts
325VDC
WINDING #1
WINDING #2
WINDING #3
O volts
325VDC
O volts
325VDC
O volts
325VDC
One
Pulse
ON PULSE
OFF PULSE
WINDINGS TURNED OFF
The frequency of the pulses to the windings is 20KHz.
DO NOT ATTEMPT TO MEASURE THESE VOLTAGES.
WINDINGS TURNED ON
OUTPUT FROM CONTROLLER TO MOTOR WINDINGS
One revolution
Figure 8. Motor Speed Control with D.C. Pulse-Width Modulation
