Can anyone help me with ideas for driving a med/large dc spindle drive motor, please?

[Voicecoil]

Those Infineon FETs are likely a good choice, I've found their devices reliable in SMPS applications. They do however have a pretty huge input capacitance so you'll need a driver chip with plenty of beans like the ONSemi FAN7191. Going back to my original suggestion, rectifying & smoothing the mains to give ~325V @ abou 5KW will need some biggish capacitors which will draw hellish charging current spikes from the mains - using smaller caps that don't charge all the way when under load might make Powergen rather happier, but will of course reduce your available power - on which subject does the Bridgeport have pulleys connecting the motor to the spindle? Obviously at lower voltages you will get lower motor RPM.

[Doddy]

Going back to my original suggestion, rectifying & smoothing the mains to give ~325V @ abou 5KW will need some biggish capacitors which will draw hellish charging current spikes from the mains

I genuinely don't know the answer to this: Would it not be worth trialling without caps at first - the inductance of the motor windings will provide a hefty current stabilisation without throwing energy into expensive high voltage, high capacitance, high ripple caps?

[Mortattoo]

on which subject does the Bridgeport have pulleys connecting the motor to the spindle? Obviously at lower voltages you will get lower motor RPM.

It has a belt drive which i believe is a 1.5-1 ratio. I very much doubt I would be trying to drive this at anywhere close to it's max output and I can easily overcome most of the downsides of this just by reducing my DOC and better calculating the speeds and feeds. Hell, if i can get 30% of the normal max power it would turn this from a beautiful giant doorstop into a machine again!!

Going back to my original suggestion, rectifying & smoothing the mains to give ~325V @ abou 5KW will need some biggish capacitors which will draw hellish charging current spikes from the mains - using smaller caps that don't charge all the way when under load might make Powergen rather happier, but will of course reduce your available power.

To be honest I am going to have to figure this out as i go along, it is deeply outside of my comfort zone. I work with big AC all the time but DC, of this kind, is a mystery to me (but getting clearer as i look into it more). Getting this running is first on the list so I will give this a go and put fuses into the line so i don't do any damage. I have a few different caps i can use and i can trial a few different configurations to see how it is effected. Then I will further look at the control side, when i can get this to work.

I genuinely don't know the answer to this: Would it not be worth trialling without caps at first - the inductance of the motor windings will provide a hefty current stabilisation without throwing energy into expensive high voltage, high capacitance, high ripple caps?

I will try this too and let you know how it goes, so long as i don't do any permanent damage I am up for trying anything!

First things first though, i will have a bit of time tomorrow to do some measuring and calculations then will see where I am!

Thank you for all your help.

Mort