Consider the h bridge circuit from here:
http://www.allaboutcircuits.com/textbook/semiconductors/chpt-11/pulse-width-modulation/
I refer to the transistors as a matrix:
11 12
21 22
When PWM is 1, 11 and 22 are ON and the motor goes in one direction. When PWM is 0, 12 and 21 are ON and the motor goes in the opposite direction.
But I do not understand. For xT time, the motor goes into one direction and for (1-x)T time the motor goes in the opposite direction. So in one period of the PWM signal, the motor switches directions.
I thought that we use the PWM signal in order to determine the speed of the rotation in some direction by using the duty cycle, and not the direction itself.
What am I saying wrong?
Or is the fact that because it rotates for just a little bit in the opposite direction for (1-x)T, because of inertia and what not, it still rotates in the right direction but just slower?
So for duty cycle of 100%, it rotates at full speed in one direction. And for 0%, it rotates at full speed in the opposite direction.
For 75% it rotates in one direction but slower. And for 25% it rotates in the opposite direction but slower.
Is this the case? If yes, what happens at 50%?
http://www.allaboutcircuits.com/textbook/semiconductors/chpt-11/pulse-width-modulation/
I refer to the transistors as a matrix:
11 12
21 22
When PWM is 1, 11 and 22 are ON and the motor goes in one direction. When PWM is 0, 12 and 21 are ON and the motor goes in the opposite direction.
But I do not understand. For xT time, the motor goes into one direction and for (1-x)T time the motor goes in the opposite direction. So in one period of the PWM signal, the motor switches directions.
I thought that we use the PWM signal in order to determine the speed of the rotation in some direction by using the duty cycle, and not the direction itself.
What am I saying wrong?
Or is the fact that because it rotates for just a little bit in the opposite direction for (1-x)T, because of inertia and what not, it still rotates in the right direction but just slower?
So for duty cycle of 100%, it rotates at full speed in one direction. And for 0%, it rotates at full speed in the opposite direction.
For 75% it rotates in one direction but slower. And for 25% it rotates in the opposite direction but slower.
Is this the case? If yes, what happens at 50%?
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