Switch-Mode Supply Driving Servo Motors

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Hi All,

We've been working on a design for a few months now and we keep coming across a potential stumbling block.  We're building a robotic device for agricultural work, with 120V generators for power.  Since we don't have much excess power we're also using switchmode supplies.  We have 1750W 48V supplies (meanwell RSP-2000) that drive 4 motors each (2 steering, 2 drive).    I'm hoping that by setting low acceleration profiles I can limit the problems but that might not solve everything.  I'm curious if anyone has suggestions for how to deal with power regen and motor startup?

Some other info:
Total vehicle weight: 500kg
Drive motors (4): Allied Motion EMI-095G9004 (750W)
Drive gear reduction: 67:1
Steering Motors (4): Moog Animatics SL17406D
Steering Reduction: 100:1
Top Speed: Maybe 2m/s

[fourtytwo42]

I'm hoping that by setting low acceleration profiles I can limit the problems but that might not solve everything.  I'm curious if anyone has suggestions for how to deal with power regen and motor startup?

I should think that is going to be very dependent on the motor controllers but you dont mention what your using ?

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The motors are actually integrated controller types, so each has a CANOpen interface directly on the motor.  I'm using that for vehicle-wide control.

I guess I'm just curious about what strategies people usually take when dealing with regen power and switchmode supplies.  I've read about using batteries, capacitors, or voltage level triggered shunts, but I'm not sure what would make the more reliable system.

[jmelson]

Hi All,

We've been working on a design for a few months now and we keep coming across a potential stumbling block.  We're building a robotic device for agricultural work, with 120V generators for power.  Since we don't have much excess power we're also using switchmode supplies.  We have 1750W 48V supplies (meanwell RSP-2000) that drive 4 motors each (2 steering, 2 drive).    I'm hoping that by setting low acceleration profiles I can limit the problems but that might not solve everything.  I'm curious if anyone has suggestions for how to deal with power regen and motor startup?

At low speed, although the motors may be drawing a lot of current, the switching motor drives (You ARE using a motor drive, right, not just connecting the motors to the 48 V supply with a relay??)  will draw low current.  With a switch-mode motor drive, the power IN is slightly greater than the power OUT.  So, with a modest acceleration profile, the peak current can be limited.

Jon

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Haha, no, I'm not just connecting the motors to a relay, that would end poorly.  They're fully smart servo motors with integrated drive electronics.  You basically just tell them the motion you want and they'll handle the commutation of the brushless motor to create that motion profile.