You do something like this:bwag wrote:Wow Mark, you're actually spot on! Peak Amp Efficiency is 13A, I'm not too worried if I end up getting something that will run 40A continuous. Thanks for your input!
Ame, I have no clue what you're talking about, and that's fantastic! I came hear to learn about ways that I don't know about, I'll have a busy day tomorrow!
Code: Select all
+V ------+-----------------+ | | NO o /o NC C C / RLA/1 o---|M|---o RLA/2 / NC o/ o NO | | +--------+--------+ | GPIO ------------|[ MOSFET | GND --------------+
Feel free to contribute a schematic and parts list.aTao wrote:You'll be wanting a back emf protection diode for the mosfet in there, otherwise its bye bye mosfet rely quick. In this case a 1n4001 isnt going to cut the mustard. You will also want a few capacitors so you arent wasting a whole bunch of energy with the back emf suppression.
Diode: STTH6012W placed across source/drain of mosfetame wrote:Feel free to contribute a schematic and parts list.aTao wrote:You'll be wanting a back emf protection diode for the mosfet in there, otherwise its bye bye mosfet rely quick. In this case a 1n4001 isnt going to cut the mustard. You will also want a few capacitors so you arent wasting a whole bunch of energy with the back emf suppression.
Be vary very careful when buying this.bwag wrote:, a 320 amp esc is $10, a 40 amp esc is $10,
NO! The diode goes across the motor. It provides a path for the current in the motoraTao wrote: Diode: STTH6012W placed across source/drain of mosfet
Capacitor: combination 100nF, 10uF and 10,000uF across power supply.
Yup, that's why the diode needs to be across the coil where the current is...Principal:When the current through a coil (motor winding) is changed the coil creates a voltage to oppose the change.
V(t)=L*di(t)/dt or voltage =- inductance * rate of change of current.
In a PWM control the current is cut almost instantly many times a second, which causes a large (huge) voltage to appear across the coil, this can exceed the ratings of the PWM power stage.. One way to deal with it is a transient suppressor across the motor (anything above a certain voltage is short circuited),quite wasteful. Another way is to push it back to the power supply and save it for later (like when the coil is turned on again). Since the power cables and connectors all have resistance then some capacitors place near to the motor circuit are ideal for storing the energy.
Using the Pi to control high powered motorsbwag wrote:Hey guys, I have a quick question.
How can I run a dc motor off of the pi? The motors stall current is 85 amps, I'd like to be able to run it to atleast 60 amps.
I was thinking I could just have the batteries directly wired to the motors (there are 4).
I found 40 amp motor controllers but they are seriously expensive, is there any low end way to actually do this?