Total Power = VxIxPWM or just VxI ?

General discussion of using Roboclaw motor controllers
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cjmbasicmicro
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Joined: Sat Mar 07, 2020 9:11 am

Total Power = VxIxPWM or just VxI ?

Post by cjmbasicmicro » Sat Mar 07, 2020 9:16 am

To know the total power my motors are using in my Dual 60 roboclaw, should I multiply three values:

Main Battery Voltage Level (interface data item #24)
x the Motor PWM values (#48)
x Motor Currents (#49),

or, just two:

Main Battery Voltage Level (#24)
x Motor Currents (#49)

In other words, are the Motor Currents already adjusted for the PWM duty cycle, or, do I need to adjust by multiplying by the duty cycle?

Thank you

Chris

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Basicmicro Support
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Re: Total Power = VxIxPWM or just VxI ?

Post by Basicmicro Support » Mon Mar 09, 2020 10:43 am

The current is always the current. PWM Duty has no effect on the current(on a pulse by pulse basis) because current doesnt like to change. Even when the PWM pulse is low(eg the high side mosfet is off) current is still flowing.

The voltage the motor sees is determined by the Duty(as a percent) * the Voltage. So 50% duty is equal to half the voltage. So your first assumption was correct.

cjmbasicmicro
Posts: 2
Joined: Sat Mar 07, 2020 9:11 am

Re: Total Power = VxIxPWM or just VxI ?

Post by cjmbasicmicro » Wed Mar 11, 2020 4:39 am

Thanks!

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