Hi Mick,
I thought to follow up on the discussion about LARGE single to three phase converters. Basically your power company would be
within theirs rights to say 'No, we will not permit you connect such a device to our network'.
The first pic is a representative circuit of an off-line input rectifier you might expect in a single phase VFD or servo drive.
The second pic show the currents and voltage when powered by a 230Vrms 50Hz supply. Note the output voltage (green trace), approx. 320Vpeak
but notice it sag between cycles. You would have to say that the DC Link capacitance is marginal for the output current.
Note the output current (red trace) is reasonably steady at about 12A but look at the supply input current (blue trace). It has peaks of about 180A!
This is a real problem....offline rectifiers draw current in high amplitude pulses with big gaps in between. The power companies hate that, they call it power factor
but in truth its more about current distortion. Any other customer hooked to the network is going to have their input supply degraded because of your device.
There are various means, both passive filters and active powerfactor correction circuitry that will solve this problem but they are expensive.
Given the plethora of electronic devices that have such simple input rectifiers and in ever increasing numbers, power companies are now having to insist on
powerfactor correction and prosecute you if you fail to comply. They have to try to protect their network for all our sakes.
Given the size of the inverter you would require for a 5kW motor I think you would come up in the power companies radar and they would ask some very pointed
questions and probably insist that you improve your installation. Industrial users are familiar with this problem and are required to spend somewhere between a quarter
and a half of their total cost of installation on the required powerfactor correction equipment.
Hood has pointed out that a 2098-DSD-030 can mange about 3kW, which is pretty damn fair. Given the exemplary torque characteristics of servos verses ansynchronous
motors I think you'd find this a very suitable replacement. Certainly it represents a practical limit to singe phase technology. DSD-030's are not nearly as common or as
cheap as the smaller 020's, but can be had for around $400US on EBay.
Craig