Microcontroller based non standard Inverter

[savvys84]

Hey,
Im looking for a complete Kit for a microcontroller based non standard inverter.

Inverter Specs are as follows.

The Inverter Specs As Flws

On Switch On Of Input The First Pulse At The Output Should Always Be + ve

Safety Protected Transformerless Inverter. i.e A Simple Polarity Reverser Using Isulated Gate Bi Polar Trannsistors.

Input : 0 to 300 Volts, 0 to 60 Amps - DC, With Digital Readout of Input Voltage and Current

Output : Square Wave AC,

0 to 300 Volts, 0 to 60 Amps

3 to 60 Hz - ADJUSTABLE ( Analog or Digital Control ) - With Digital Readout. and a variable ) Keypad Input ) 1 to 10 millisecs add on dead gap between +ve and -ve pulses . Digital read out should read freq corresp to the pulse width. For ex a 20 millisecs single pulse width, the corresp freq readout should be 25 hz . So pulse widths corresponding to 3 to 60 Hz will be required.

Power Factor 0.8 to 0.9

Internal Electronics Support: 12 Volts Battery DC via a DC to DC Converter .

Also if possible a variable 5 to 60 amps ( Analog or Digital ) solid state current limiter, to be incorporated on the input side.

The Inverter Will Be Used To Drive Simple One at a time, LC Power Oscillators With an Iron Core . 1 Pc. Inverter is reqd for making a presentation to the Hospital Industry,

B Rgds
Savvy
Mumbai, India

 

[Oznog]

What do you mean by "Power Factor 0.8 to 0.9" if the input is DC? Do you mean DC input supply current ripple? Or that it supports output power factors up to 0.8?

 

[savvys84]

Oz,
If you read correctly, the Output is AC square wave, and the Power Factor of the LC loads range from 0.8 to 0.9. So to say that it supports such a power factor is also correct.
Thanks for the reply though.

 

[Sceadwian]

I think you've badly stated your specifications. 0-300 volts 0-60 amps? At the max 300 volts and 60 amps the total power out is 18 kilowatts... What are you REAL wattage requirements?

 

[savvys84]

Hi,
Looks like the specs are badly understood. Mind you this is a non standard inverter.
Variable Input. For Eg if Input is 50v/10A, Then the output is also 50V/10A.
Youhave stated the Max rating, which is correct.
Thanks for your reply tho.

 

[Sceadwian]

There is no such thing as a non standard inverter. You just want a variable controlled one,
You need to clarify your specs, because so far they don't make sense. 18kw for an inverter is not obtainable from a 'kit' you're talking about the same amount of electricty that an entire home in the US uses under peak load conditions.

 

[Oznog]

Well, did you mean the output is 0 to 300v, or +300v/0v/-300v via h-bridge? You mention a -ve pulse, but say "output is 0 to 300v".

'cause without an H-bridge it's not an inverter really. It doesn't invert. It's just a PWM.

An IGBT cannot drive to 0v. The CE drop is higher than that.

You're gonna need some sort of high-side gate driver, and probably a low-side driver too. The PIC sharing a ground with 60A surges on a 300v supply may be an issue. Or did you want to isolate the supply ground from the PIC?

A problem here is that at high currents, you need to be very particular about keeping the turn-on and turn-off smooth. But you don't know what the current OR voltage will be, nor much of what the load is like.

Now the actual PIC code here is simple, including the dead time control. 60Hz may be too slow to even need (or be able to use) the special-purpose PIC H-bridge driver. Any "digital control" display will be more complicated than the pulsing code. The difficulty in in an output stage with the capabilities listed; this will probably involve SPICE modeling. What do you mean "LC Power Oscillators With an Iron Core"? I know what an LC is, but I don't see what you're trying to do. An LC oscillator doesn't even consume much power in itself, the power factor should be near 0. An LC in series with an actual power-consuming load will NOT maintain a near-unity power factor over a wide frequency range.

You need to be about 5x more specific on what this circuit needs to do and how it needs to do it before we can help. It's not that we don't want to, but it's impossible to give specialized answers when the problem is unclear.

Your initial question seems to be asking for a link to a "complete kit". I am reasonably sure no such item exists for a PIC-controlled IGBT 0-300v 60A. This is a custom circuit.

 

[Sceadwian]

Oznog have you read the post?
His listed specs require EIGHTEEN THOUSAND WATTS of power.
You're talking an Industrial grade commercial power supply.

 

[savvys84]

Thanks Guys,

This is only a polarity reverser. 300 VDC is from a Hospital wall socket.
LC loads ( The hospital probably uses a linear disp armature of some sort ) are various for each selected freq ( 3 to 60 hz ). I only need to build a prototype and make a presentation to them. They will not be specific about the loads.
The 12 v battery only takes care of the control and display unit . Ther is no common -ve here.

 

[Oznog]

What does "LC" mean?
Does the load get inverted or not? You say "inverter", and "polarity reverser". OK, you've got 2 load wires, "A" and "B". Do you want Vab to be +300v and then -300v, or +300v then 0v?

What hospital puts 300VDC on a wall socket? I have never heard of this. It sounds extremely dangerous. But in any case it makes no sense, because won't such a socket be ONLY ~300vdc then? Not "any voltage between 0v and 300vdc"?

And how did you determine you need 60A?

 

[blueroomelectronics]

I wonder what hospital it is so I can avoid it.

 

[savvys84]

Gentlemen,
By proffession, I am a Marine Engineer, and I have Put the specs in an understandable engineering format.

Bottom line is, I have to deliver this to the hospital Industry, which has special needs. The variable input 0 to 300 VDC/ 0 to 60 A is their resposibility.

Square wave means, across the LC load or Plain L load, the currents should reverse, whic is acheived by reversing the polarity.

On a Oscilloscope the square wave ( Voltage ) will show voltages + and - w.r.t zero.

Bottom line

1. Selection and programming of Microchip. ( Need help with this )
2. Building the H Bridge.
3. Interfacing the microchip with power side and the display units and the keyboard.
4. Arranging a 12 volts DC to DC converter ( To avoid common negative ) to supply the electronics.

But hey thanks anyways for spending the time on my project

 

[Oznog]

Gentlemen,
By proffession, I am a Marine Engineer, and I have Put the specs in an understandable engineering format.

Bottom line is, I have to deliver this to the hospital Industry, which has special needs. The variable input 0 to 300 VDC/ 0 to 60 A is their resposibility.

Square wave means, across the LC load or Plain L load, the currents should reverse, whic is acheived by reversing the polarity.

On a Oscilloscope the square wave ( Voltage ) will show voltages + and - w.r.t zero.

1. Selection and programming of Microchip. ( Need help with this )
2. Building the H Bridge.
3. Interfacing the microchip with power side and the display units and the keyboard.
4. Arranging a 12 volts DC to DC converter ( To avoid common negative ) to supply the electronics.

Well, I gotta say though, your spec is not all that understandable yet. An input of 0v doesn't even make sense.

So now it's a wrtz inverter? And an h-bridge? Is this correct? This is a different device and was not initially described as such.

The microcontroller ground is different than the input ground? Again, this is ok, but it's a totally different problem!

12v is unnecessary for the DC/DC. It only needs 5v at most. 12v can of course regulate down to 5v but the 12v is not necessary. How are you getting the 12v? Getting an isolated 12v (or 5v) from a 300vdc supply is certainly possible but I can't think of any common off-the-shelf parts which do it.

The "LC load or Plain L load" does not make a lot of sense. An inductor and capacitor is not in itself a load which does any useful work. Not that I've got anything against LC loads, but it is likely there is a huge miscommunication here and what you're trying to do is something completely different than what it seems.

 

[savvys84]

Oz,
Thanks again. I admire your dedication. Comments as follows
1. Re 0 Volts input. As engineers we know that The CE Threshold voltage is expected and accepted.
2. wrtz and H bridge is correct. Mainly the currenys have to reverse.
Wouldnt the oscilloscope show a +ve and -ve pulse, when the polarities are reversed?
3. The client wants to use a 12v car battery. for electronics
4. Lc loads is either a series or parallel resonance. Plain L load is no resonance. They will draw current if they are moving a piston armature, although the client is reluctant to reveal the actusl device. V = IZ , where Z is the Impedance, and if The Value of L is significant, The Current will also be significant. Here we are not talking about some oscillators in a radio .
5. My prjoect is only to construct a polarity reverser for the client

B Rgds
Savvy
+919892777185