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SENSITRON
SEMICONDUCTOR
TECHNICAL DATA
DATA SHEET 1023, REV. E
Application Information
60
o Rotor Position Sensing
SMC6M40-XX is designed to operate with 120
o position sensing encoding. In this
format, the three position sensor signals are never simultaneously high or low. Motors
whose sensors provide 60
o encoding can be converted to 120o using the circuit shown
in Fig. 4.
Two-Quadrant vs Four-Quadrant
In two-quadrant mode only one switch is modulated at any time while in four-quadrant
operation two switches are modulated. This results in a more efficient controller and less EMI
emission when operating in two-quadrant mode. However, two-quadrant mode has some
limitations as explained below.
Fig. 5 illustrates the four possible quadrants of operation for a motor. Two-quadrant mode
refers to a motor operating in quadrants I and III. With a two-quadrant BDC motor, friction is
the only force to decelerate the load. Four-quadrant control provide controlled operation in all
quadrants, including II and IV, where torque and rotation are of opposite directions.
SMC6M40-10
SMC6M40-10-1
SMC6M40-25
SMC6M40-25-1