Hi,
some issues:
Let us say i give PWM with 100% duty
Many high side driver circuits can´t go to 100% because of the bootstrap circuit. Use 98% max. duty cycle
then the complete voltage is applied to the motor.
Theoretically yes. But ther is the above problem. And a motor won´t withstand this because it needs to be driven with AC. It will be killed very soon.
But if you have a resistive test load, then yes.
Suppose if i control the H leg with 50% duty then half the voltage will be applied.
With a resistive test load: yes. But not with a motor, because it is inductive.
It will generate it´s own voltage. If the lower MOSFET stays ON (slow decay mode), then there will be a small negative voltage across the inductance, as long as there is magnetic energy in the coil.
In reality the RMS voltage will be around 50% of the supply voltage.
H leg with 50% duty and the Low leg at 50% duty. What will be the voltage applied to the motor?
(fast decay mode). When both MOSFETs are OFF, then there will be about the negative sully voltage across the motor winding as long as there is magnetic energy in the coil.
--> The resulting averaged winding voltage will be close to zero. Low current, low torque.
These are raw estimatins.
It dependson
* motor: circuit, inductance, (DC) wire resistance, RPM, mechanical load..
* driving ciruit....
Klaus