Driving motor and simulation

Hi,
I work as inverter and dc / dc designer, but I'm new in three-phase motors' subject.
I should make a project sketched in the figure.



the characteristics of the motors are in the picture.
I say the pilot will be in open loop.

how are the discrete components (MOS or igbt) dimensioned in terms of current, voltage, and dissipated power ?
To supply the three-phase bridge of what DC voltage value do I need?
What amount of power Should DC / DC has to supply?
How can I simulate the motor without having the parameters described in the model provided by spice, but only those of the figure?

Thanks any advice / lesson about it is well accepted.

Re: driving motor and simulation

Find the PSpice models on mfr's web site for something
of appropriate voltage and current rating.

This is not a DC-DC, it's a 3-phase inverter (DC-AC).
You show no rectifier stage however (AC-DC).

You should be able to find 3-phase inverter project
inverter examples on the Web, to crib from. Suggest
you start with TI, ON, Linear Tech, Intersil, IXYS,
Power Integrations (I'm sure there are more) and see
what they've got supporting their controller IC products.
I'f bet that between them you can even find eval board
(buy, or just rip off the schematic and BOM).

Re: driving motor and simulation

Are you looking for a method to convert single-phase AC to 3-phase AC? It will not be easy, unless your power spec is very low.

Re: driving motor and simulation

BradtheRad said:

Are you looking for a method to convert single-phase AC to 3-phase AC?

Click to expand...

No, this in not my question. I've to do a DC/AC converter.

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dick_freebird said:

Find the PSpice models on mfr's web site

Click to expand...

what is "mfr's web site"?

This is not a DC-DC, it's a 3-phase inverter (DC-AC).

Click to expand...

i've to design also a dc/dc as shown in the figure.

Re: driving motor and simulation

franticEB said:

the characteristics of the motors are in the picture.

Click to expand...

There are two voltages, 220 V and 380 V. Which one you will use? Voltage can affect to component selection. Interesting motor for VFD as nominal speed is different for Y and delta.

franticEB said:

how are the discrete components (MOS or igbt) dimensioned in terms of current, voltage, and dissipated power ?

Click to expand...

Possible IGBT's are typically rated for 600 V and 1200 V. For 380 V use 1200 V device. About current rating, I would assume that one wants to have a certain junction temperature at a specified load. Current rating, device package, switching frequency and cooling arrangement are at least items to consider

franticEB said:

To supply the three-phase bridge of what DC voltage value do I need?

Click to expand...

Minimum for 380 VAC connection is 380 V/sqrt(2) which is about 538 VDC. This assumes space vector modulation or sinusoidal pwm + third harmonic injection. Increase DC level to account voltage losses.

franticEB said:

What amount of power Should DC / DC has to supply?

Click to expand...

I would guess motor shaft power + motor losses + inverter losses. Something like 800 W/0,7=1140 W for 220 V connection.

franticEB said:

How can I simulate the motor without having the parameters described in the model provided by spice, but only those of the figure?

Click to expand...

Use something like induction motor equivalent circuit is. Leakage reactance, magnetizing inductance and a resistor. Resistor value sets the active current. Check that no load current and power factor are reasonable. It was not mentioned, so I assume a pump or fan type load where it is enough to model max speed/load.

Re: driving motor and simulation

Actually, you do not have a star-delta connection; you simply start with a low voltage and go to full specified voltage once the motor picks up speed.

For a star connection, you will need a neutral which you will not have in the above configuration. Just reduce the voltage during the start phase. 800W is not much and it should not be difficult using any standard microprocessor.

By the way, 220V single phase will be close to 400V in the three phase (in single phase 220V is RMS for 1 phase with ref to the ground and for the three phase it is 400V RMS for phase to phase). So you need not bother about two diff voltages.