I'm busy building a force feedback joystick project driven by an AT90USB686 AVR however I have some unusual motor control requirements that I'm not sure how to address.
I've read up about PWM and H-bridges but it appears that those sort of solutions only work for speed and torque control when the motor is spinning.
In my design I need to control the torque of a brushless DC motor in it's stalled state. I'm looking at using one of the large DC brushless motors used to power RC aeroplanes (2-5kW sustained power output).
From what I've read I have two problems that I need to address:
1. The motor in it's stalled state doesn't behave exactly the same as when it's spinning. The stalled current is very high and PWM won't allow me to vary the torque easily in the stalled state. I need to vary the current supplied in the stalled state to vary the torque.
2. Using PWM to drive a brushless DC motor can be a problem due to the internal timing circuitry of the motors so I'll rather opt to drive the motor with a linear power supply.
According to what I've read the torque of DC motors is almost linear to current draw so in essence I need to build a current/voltage controller and forget about PWM?
I want to use brushless DC for low maintenance.
Am I on the right path or do I have some fundamental flaws in my logic?
I've read up about PWM and H-bridges but it appears that those sort of solutions only work for speed and torque control when the motor is spinning.
In my design I need to control the torque of a brushless DC motor in it's stalled state. I'm looking at using one of the large DC brushless motors used to power RC aeroplanes (2-5kW sustained power output).
From what I've read I have two problems that I need to address:
1. The motor in it's stalled state doesn't behave exactly the same as when it's spinning. The stalled current is very high and PWM won't allow me to vary the torque easily in the stalled state. I need to vary the current supplied in the stalled state to vary the torque.
2. Using PWM to drive a brushless DC motor can be a problem due to the internal timing circuitry of the motors so I'll rather opt to drive the motor with a linear power supply.
According to what I've read the torque of DC motors is almost linear to current draw so in essence I need to build a current/voltage controller and forget about PWM?
I want to use brushless DC for low maintenance.
Am I on the right path or do I have some fundamental flaws in my logic?
