
Electrical and electronic principles
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common use. These are single winding types, which have two terminals, and
double winding types, which have three terminals. Under ECU control, the
motor is caused to open and close a shutter, thus controlling air bypass. These
actuators only rotate about 90° to open and close the valve. As these are
permanent magnet motors, the term ‘single or double windings’ refers to the
armature.
The single winding type is fed with a square wave signal causing it to open
against a spring and then close again, under spring tension. The on/off ratio or
duty cycle of the square wave will determine the average valve open ...