Power Limiting instead of Current Limiting

General topics and discussions about the VESC and its development.
BlakeCarmichael
Posts: 16
Joined: 06 Sep 2017, 12:12
Location: Florida

Re: Power Limiting instead of Current Limiting

Postby BlakeCarmichael » 06 Sep 2017, 22:12

Is it possible to read the battery voltage via UART to the Arduino, then write via UART from Arduino to the VESC to modify the battery current maximum with an inverse relationship as the battery voltage drops?

I have been using the VescController library which does not include reading from the VESC, but if above is possible then I may try another library that allows it to work.

rew
Posts: 943
Joined: 25 Mar 2016, 12:29
Location: Delft, Netherlands.

Re: Power Limiting instead of Current Limiting

Postby rew » 08 Sep 2017, 19:20

The problem with that, I think, would be that the motor stops when you write a new motor configuration.

BlakeCarmichael
Posts: 16
Joined: 06 Sep 2017, 12:12
Location: Florida

Re: Power Limiting instead of Current Limiting

Postby BlakeCarmichael » 13 Sep 2017, 14:41

rew wrote:The problem with that, I think, would be that the motor stops when you write a new motor configuration.


That may not be a deal breaker for me. Could you give me some pointers on how to accomplish this, or direction to any Arduino libraries that allow this to work please?

rew
Posts: 943
Joined: 25 Mar 2016, 12:29
Location: Delft, Netherlands.

Re: Power Limiting instead of Current Limiting

Postby rew » 13 Sep 2017, 17:29

Sorry. "No can do". Arduino is not my speciality.

devin
Posts: 255
Joined: 08 May 2017, 01:55
Location: San Francisco, California, US

Re: Power Limiting instead of Current Limiting

Postby devin » 17 Sep 2017, 22:03

Possible solution?

Topic: "Watt Control Via Duty Cycle Control?" - http://vedder.se/forums/viewtopic.php?f=6&t=1572

rew
Posts: 943
Joined: 25 Mar 2016, 12:29
Location: Delft, Netherlands.

Re: Power Limiting instead of Current Limiting

Postby rew » 18 Sep 2017, 06:14

Of course you can control the wattage by adjusting the duty cycle..... In theory.

The thing is, your control loop needs to be fast. Having that in the firmware in the mainloop would be best.

Slightly more relaxed timing can be obtained by using current control.

However, WAY more relaxed timings can be obtained by setting the battery max current depending on the actual battery voltage.


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