Quote:
Originally Posted by jyanof
It sounds like you're writing your own software... is that right? If so, is your control scheme 'motor current' based? As in, the throttle is interpreted as a commanded output current and control loop uses the current sensor feedback to adjust the PWM duty cycle to match this commanded current?
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Hi Mate
You make it sound more complicated than it is.
It is not done in software but hard wired and totally autonomous.
Basically the PWM is generated by a pic chip that generate's PWM in response to a voltage from the throttle pot.
The current is sensed with a hall effect sensor as in the openrevo cougar.
When the current trips, the output from the sensor OP Amp is used to switch in a low value resistor across the output from the throttle pot so lowering the voltage fed to the pic chip. This will change the PWM duty cycle and so lower the current.
When the current sensor recovers the resistor across the throttle is removed and a smallish capacitor across the the input is allowed to charge up to the value set by the throttle. The current is thus ramped up fairly slowly to the value it was at the start unless the throttle has been eased off.
I thought this was kinder than chopping a very high current flow to zero and then immediately banging it back on possibly up to 100 or so times a sec.
I know this is exactly what the PWM generator is doing but very much faster.
I have a second timer cct that is allowed to fire if the output from the current sensor remains active for about 1.6secs. This trips my main contactor relay which remains tripped until I switch off and allow the timer to reset, again hardwired and autonomous. I figure if everything goes short circuit I wont get very far in 1.6secs even at full speed.
