Reducing Voltage w/ 1067

[AdamLee]

Good day everyone!

We've been running 12V rated motors with the 1067 and a 24V power supply for some time now. One of the things we noticed early on is that the motors get pretty hot. I don't have any current measurements but at one point I remember getting an IR reading of 70C.

I noticed that there is some language in the user guide that specify that the 1067 can reduce the output voltage:

https://www.phidgets.com/?tier=3&catid= ... ly_Voltage

The 1067 can operate from 10 to 30 VDC. It is able to reduce the voltage during operation if your motor requires less, but it cannot increase the voltage.

Can someone point out to me how to reduce the voltage? It looks like the only control we have is to set the current limit, but I'm not understand how that could affect the output voltage. We haven't limited the current before but we're going to do some testing to see what value we can get down to and still operate at.

[mparadis]

That sentence is a bit misleading- what we were trying to say is that users don't have to worry about using a 30V supply on the 1067 when driving a motor rated for 12V. If this were a simpler controller, one that didn't have any current control, it would damage the motor to apply more than double the rated voltage to the motor's coils.

The reason using a higher voltage isn't a problem on the 1067 is because it uses a chopper drive- it monitors the current being pulled by the motor and when it reaches a certain threshold, it cuts power. When the current drops enough, it 'chops' the power back on. This happens very rapidly and the result is an effective voltage that is lower than the supply voltage. The only difference the supply voltage makes in this case is that a higher supply voltage results in the current rising faster between chops, which can improve performance in some cases.

So, in your case, lowering the Current Limit will naturally result in a lower effective voltage, and less current means less heat.

[AdamLee]

Thanks @mparadis!