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 [DPRG] Driving an H-Bridge with a switching power supply Message index sorted by: [ date ] [ thread ] [ subject ] [ author ] Previous message: [DPRG] Driving an H-Bridge with a switching power supply Next message: [DPRG] Driving an H-Bridge with a switching power supply Subject: [DPRG] Driving an H-Bridge with a switching power supply From: rljordan rljordan at airmail.net Date: Mon Dec 29 18:10:02 CST 2003 ```Ed, I have heard that each motor type needs to be "tuned" to the best PID frequency. I assume this has to do with the resonate frequency of the motor winding inductance. Have you heard this, had experience with it, or can you shed any light on it? This is hearsay and I have not found any documentation or good explanatins of it. It does seem to make sence to me in my limited experience. Thanks Bob Jordan P.S. Best of the Holiday season to you and yours. -----Original Message----- >From: dprglist-admin at dprg.org [mailto:dprglist-admin at dprg.org]On Behalf Of Ed Koffeman Sent: Monday, December 29, 2003 9:48 AM To: 'David P. Anderson'; dprglist at dprg.org Subject: RE: [DPRG] Driving an H-Bridge with a switching power supply Hi, David. The varying battery voltage creates a variance in the overall gain of the PID control loop and therefore affects the tuning. If your micro can measure the battery voltage (even as a rough relative value), then all you should have to do is multiply the result of the PID calculations by the factor representing the inverse of battery voltage over the nominal voltage it was tuned at e.g. the minimum operating voltage. The result should always produce the same amount of corrective drive regardless of the battery voltage. Of course, when the battery is low you will have a lower top speed, but that will be the same speed as if you were to regulate to that lower voltage, so really you are gaining the ability to go faster or handle greater extremes when the battery is fully charged. The above presupposes that the motor driver PWM frequency is high enough for continuous conduction e.g. bare minimum 3 or more times the time constant of the motor windings. A very low frequency PWM e.g. 200 Hz will not likely behave in a correct manner - the PWM percentage will more directly affect torque than speed, because the current can drop to zero during the off time of each PWM pulse. You probably need to run 2000+ Hz. (This applies to all PID imho.) Ed Koffeman _______________________________________________ DPRGlist mailing list DPRGlist at dprg.org http://nimon.ncc.com/mailman/listinfo/dprglist ``` Previous message: [DPRG] Driving an H-Bridge with a switching power supply Next message: [DPRG] Driving an H-Bridge with a switching power supply Message index sorted by: [ date ] [ thread ] [ subject ] [ author ] More information about the DPRG mailing list