inverse one motor speed based on input from other motor speed

15 years 11 months ago #20891617 by Deyeme

A new question on this same line...<BR><BR>First, I'm just starting to refresh my knowledge of electronics. I've been away from transistors and resistors, and neck deep in computer programs and building servers for a number of years. This EV project has me back to things I haven't really been "into" since childhood. That said, I was about 10 when I reconfigured an old battery powered Philco AM radio as a cordless phone receiever, so... ;-)<BR><BR>Back to the subject!<BR><BR>I'm going to design a small circuit to change the speedo output (+5vdc sq. wave) to a voltage value. In the meantime, I have another possibility for a different way to use electrohydraulic PS that isn't speed sensitive. Tell me if this can be done with your existing controller:<BR><BR>any time the key is "ON", the controller has power, and the pump (80A max @ 12v) is at an "idle" speed. This is to always provide some low level of power assist without a huge power drain. As the steering wheel is turned away from center, the pump speeds up to a predetermined maximum. It's not too important that I know the speed of the motor. I could also set the maximum to be a current draw rather than a motor speed. Same with minimum, or idle, speed- it could also be a current draw rather than a known speed.<BR><BR>I could use something like throttle return springs, attached to a pot. This way, the more you're TRYING to steer, the more assist you get. At low speed, you're going to be making larger maneuvers (and require more assist), and at higher vehicle speeds, you would be making smaller steering movements, and require less assist.<BR><BR>This is a different concept than vehicle-speed-variable assist. I think the Toyota MR2 uses a combination of speed and steering wheel position. Unfortunately, my EV project is a Dodge Dakota, not an MR2.<BR><BR>Also, I have more info on the pump- it draws a max of 80A @ 12v. I definately want to get one of your controllers, since I could at least attach a control (pot) to give it a set speed or load, rather than just wiring it straight to the battery and having it pull max power all the time.<BR>

<BR>EDIT: what about the National Semiconductor LM2907 ?<BR><BR>EDIT2: I went ahead and purchased some LM2907s for testing. These babies are only $.70/ea when purchased in bulk. Sure would be a nice feature in the controllers...
Anyway, I'm going to make a test board that will turn the +5vdc sq wave to a voltage value (adjustable with a small pot), and I should be in business. I'll let everyone know how it goes!

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