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

[Voicecoil]

If "only half the power" would be fine for you, then there's maybe an easy option. Use a 230V:115V stepdown transformer/rectifier/smoothing cap for the field winding, and a PWM regulator run off rectified 230V AC for the armature - last time i looked for one these they were available as an off the shelf module from a few suppliers. This will only give you 325V tops on the armature but hey that's still 4000...4500 rpm and at least 75% power.

[Muzzer]

If "only half the power" would be fine for you, then there's maybe an easy option. Use a 230V:115V stepdown transformer/rectifier/smoothing cap for the field winding, and a PWM regulator run off rectified 230V AC for the armature - last time i looked for one these are available as an off the shelf modules from a few suppliers. This will only give you 325V tops on the armature but hey that's still 4000...4500 rpm and at least 75% power.

Nice idea. You'd need to check if the field winding has enough resistance to limit the current to the required level but it looks as if it might be about right.