On 5 October 2011 15:50, Jan de Kruyf <[email protected]> wrote:
>> Almost perfect, but 18V minimum supply voltage.. > So limit the input to your speed- amp to the equivalent of 12 V back-emf. > You might need some headroom in any case to get your dynamics right. The problem is that we only have a 12V supply. Let me explain in full: The application is to control a butterfly valve mounted in the exhaust of an engine to emulate the back-pressure from the production system including cat and particulate filter. The valve and motor (12V) already exist. The Dyno controller can operate the valve in closed-loop control (it is already controlling about 7 other process variables). It can output a voltage of up to +/- 11V and a current of +-25mA, but this is on a single wire which must be able to drive the valve actuator in either direction. The only power in the cell is 12V, 240V and 380V 3P. I have a feeling that a set of back-to-back power transistors could do the job linearly, at the expense of getting a bit hot, but an existing commercial solution would be best. The problem with the power-amp ideas is that that I don't see how that would drive the motor in the reverse direction, I think an H-bridge is needed. (unless we were to hold one terminal of the motor at 6V, and drive the other to 0V and 12V, I suppose) -- atp "Torque wrenches are for the obedience of fools and the guidance of wise men" ------------------------------------------------------------------------------ All the data continuously generated in your IT infrastructure contains a definitive record of customers, application performance, security threats, fraudulent activity and more. Splunk takes this data and makes sense of it. Business sense. IT sense. Common sense. http://p.sf.net/sfu/splunk-d2dcopy1 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
