switch off regeneration
switch off regeneration
I am using a desktop DC power supply unit to power and test my robot that uses roboclaw 2x30A. How can I switch off regeneration. Till now I only use it to spin the motor and stop it. That works - but am scared this is going to get me in trouble if regeneration kicks in.
Also:
I am currently using a 2x30A roboclaw. My motors max stall currents are 20A. My desktop dc power supply has a max current output of 3A. And I am able to drive the motors. How does this work? Isn't it true that at startup the motors will pull close to 20A and the roboclaw should pull 20A from the DC power supply unit, which should blow the fuse? I am guessing that the limiter in my DC PSU is the one stopping everything. Or does the roboclaw also have a limiting circuit built in?
Also:
I am currently using a 2x30A roboclaw. My motors max stall currents are 20A. My desktop dc power supply has a max current output of 3A. And I am able to drive the motors. How does this work? Isn't it true that at startup the motors will pull close to 20A and the roboclaw should pull 20A from the DC power supply unit, which should blow the fuse? I am guessing that the limiter in my DC PSU is the one stopping everything. Or does the roboclaw also have a limiting circuit built in?
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Basicmicro Support
- Posts: 1594
- Joined: Thu Feb 26, 2015 9:45 pm
Re: switch off regeneration
Regeneration cant be switched off. It is inherent to driving motors. The regeneration has to go some where. Either an external voltage clamp/power shunt(which pill burn off the extra power as heat) needs to be added or you can set the min and max voltages on the Roboclaw to just above and just below your power supply voltage(about 2 volts above and 2 below is usually good, but will vary depending on your power supply). When you set the voltage limits, though, the Roboclaw will brake the motors whenever the voltage goes over the maximum limit and it will coast the motors whenever the voltage hits the minimum limit.
The current from the power supply is not usually the current at the motor. One way to think of it is like this: Say the motor is pulling 3amps from the power supply at 10% duty cycle. The motor has to fit that 3amps of continuous power into a time slice only 1/10th the full period of time. That means the current in that 1/10th time slice is 10 times higher(eg 30amps).
Also motors have back emf which fights current. As the motor speeds up there is more bemf which reduces the current pulled.
Note however that as your duty cycle percent increases the draw from the motor will become larger relative to the motors actual current draw. At 100% duty the power supply will have a 1:1 ratio.
Also note that power supply dont usually have hard current limit cutoffs. Your 3 amps supply could be supplying more than that and just over heating. You wont know until you damage the power supply. O its overtemp protection kicks in.
The current from the power supply is not usually the current at the motor. One way to think of it is like this: Say the motor is pulling 3amps from the power supply at 10% duty cycle. The motor has to fit that 3amps of continuous power into a time slice only 1/10th the full period of time. That means the current in that 1/10th time slice is 10 times higher(eg 30amps).
Also motors have back emf which fights current. As the motor speeds up there is more bemf which reduces the current pulled.
Note however that as your duty cycle percent increases the draw from the motor will become larger relative to the motors actual current draw. At 100% duty the power supply will have a 1:1 ratio.
Also note that power supply dont usually have hard current limit cutoffs. Your 3 amps supply could be supplying more than that and just over heating. You wont know until you damage the power supply. O its overtemp protection kicks in.