400W servo - Leadshine ACS806 + ACM604V60 driver - PSU size?

[Gary]

An AC servo system would be the better option because the power supply is built in.
The leadshine system is a good system, but you need a large power supply that can deliver the peaks that the application needs.

[dsc]

Thanks for the reply Gary. I might be running well below the nominal torque, which means I'll never get above nominal current either. As I said before, the motor is overspec'd for the purpose, which is one way of getting out from having to buy / make a massive DC PSU. Surely the AC system with a built in supply will have limitations as well, won't it?

Am I correct to think that in heavy duty applications the PSU current capabilities are based on the peak current of the motor? that indeed means massive motors for the bigger servos, which can get up to 80A peak or more.

Regards,
dsc.

[Gary]

An AC server driver will give you a continuous current and a peak current.
In the datasheet of the motor there will be a torque constant figure and this is typically Nm/A so from this you can work out the peak torque that you can get from the motor when used with that AC servo driver.
However, normally the smallest AC servo driver would be 750W and if we take this as an example the peak current would be 15A and the nominal would be 4A so is 3.75 times the nominal current.
A 750W AC servo driver would be rated to be able to handle the peak current of a 750W motor for the amount of time specified within the specifications.
This is assuming the motor is rated at the 300V DC bus.
A dc servo has a lower DC bus so the current is a lot higher, so that is why you need a larger power supply.
It makes no sense to spend the money on a servo system and then cripple it with a low powered power supply.
Also as a casing point AC servo systems out sell DC by 50:1.

[dsc]

Again, thanks for the info.

Looked at the range of servos you've got, a 750W would work well I think. One other reason why I was looking at DC servos is that I already have a stepper motor, which will need it's driver and a power supply. That means loads of components, wires etc.

Regards,
dsc.

[Gary]

Yes the CD422 is the smallest AC servo we do, but can be configured to use the SME60 range of motors that are either 200W or 400W.

[dsc]

Gary,

good stuff, looking at the specs the CD422 can do upto 750W, so I'll go for a CD422 + 750W AC SMH80 servo.

Regards,
dsc.

[Gary]

That's a big motor, with a 3:1 ratio that would be a continuous torque of 7.17Nm and a peak of 21.33Nm at 1000 RPM.
Thats a big jump up form 400W.