Tuning guide lines for a pulse length frequency adjustable inverter

Replacing your inverter which is usually only 90 percent efficient is the logical next step for RV operation off the grid as standard inverters are not that efficient.

Also frequency adjust is a must to permit maximum benefit of RV operation.

Please check the first e-book in this series entitled laymen’s RV theory for instructions and schematics for building one.

Here is a picture of one built for by a dear friend PHIL. With hectors feet.

Description

With this inverter I made, it’s a square wave but with using a capacitance and relying on the inductance of the transformer and your motor, it is partly sign wave. It has the switch too lock it on 60HTZ and if you want you can switch this out and wind the frequency up from 60HTZ too 120HTZ.

 An AC motor works very well on square wave voltages. They do sound a little noisier than pure AC but who cares. Now the other thing involved is that I am using any Back EMF from your motor and also from the transformer to give you extra energy gains. Plus I am using my other techniques of recycling energy on the primary side of the circuit.  It is only a 12volt Inverter but uses 2 batteries where one pulses a polarity and the other pulses the other polarity. The circuit, flip flops between the two and hence creates a charging stage for the battery not being used. There is also a buffering circuit on board that also does some charging even if there is no back EMF.

View the circuit exactly as if it is your inverter, so you are now not using the inverter you already have. With this circuit and your Toroidal Transformer you now have an inverter that is more efficient than what you already have. The circuit allows you to adjust the frequency to also tune the optimum speed and

efficiency of your motor, but at the same time it recycles as much energy as it can through a semi closed loop sequence.

This is where you need two batteries for the optimum performance where

one is charging while one is discharging and where you don't need to worry about your diode plug circuit if you don't want to. The two batteries can be of a less capacity than what you are using, or you can use what you have it doesn't really matter.

With the circuit it allows you to run any load at the 110 volts but it will recycle what it can to extend the run time. So we have a concept where if your current inverter was running a load the batteries may last 1 hour but with this inverter circuit they may last 2 hours or even longer depending on the type of load and the battery efficiency.

Instructions given to me are Check the input voltage of the inverter (12V or 24V?). Connect the inverter to your battery(ies) of same voltage. For now connect just a light bulb to the output, and see it works OK. Measure the voltage with a voltmeter. The output of the inverter is likely a modified square wave. So the RMS value of the voltmeter will not be correct, and those are tuned for sine waves. You will be 11% off Adjust the frequency (you should not see any luminance difference I guess).If you have a scope, connect it in parallel over the output, then you can measure the frequency.

Important to know the frequency swing, and where 50 or 60Hz is. (I don't want to connect this straight to the RV without checking the freq, as if it were at 200Hz, your RV will accelerate to 12000rpm....) For RV connection: - switch off inverter - connect RV as normal to it - set the inverter freq to the lowest - start inverter - see what motor does

 * if the lowest freq of inverter is 0Hz, then your motor will not spin  * if the lowest is eg. 10Hz, then your motor will start up to 1/5 of the rpm, (so for a 3000rpm motor, you'll get 600rpm)

- SLOWLY increase freq; you'll see motor running faster

(reason for "slowly" is that you need to give your motor time to catch up with the speed WITHOUT drawing too much input current)

- go to 50/60Hz - you can go faster if you believe your RV setup can handle it (be careful)  test if can go to 100Hz (6000rpm). In fact if I think about this, it believe you don't need start caps with your RV, only run caps. Start caps are only needed if you start straight from the grid with is fixed 50Hz.

Further notes from Phil on this concept

Everyone will have their own points of view but mostly there own focus on how the energy gains should be achieved. Hectors resonance concepts are important and is a must for power savings. My focus has been by using auto resonance tuning and known scientific capacitor behaviors.

The ultimate system is the RV controlled by an auto resonance tuning AC inverter with a battery parallel and series charge circuitry.

This way any subjected loads too the RV will be auto adjusted for the ultimate performance and all energy returned too the original sources. Using step up transformers this is easily monitored on the low voltage primary side and will auto tune out any variables.

Notes on freq adjust by hector

The rotor is virtual inductor and capacitor makes it synchronous to specific speed and ac current frequency. If you accelerate using frequency inverter and de-accelerate the rotor makes the power goes negative as rotor angle of rotation becomes leading acting as generator the capacitor tends to lead the angle (over-speed) as you switch to low capacitance this leading slip turns for an instant in asynchronous generation state where rotor provides energy to source and the current goes to 0 or negative. Refer to asynchronous generation, cogeneration & power factor rotary condenser machines, read this in RV energy savings R and D doc located at the EDGRAY and RVreplication yahoo groups in the file sections.

Some may experience a shudder happening near full RPM just before the next cap should be switched out. This is because the Rotor becomes a reverse inductor to the LC at a lower frequency and the LC brakes the rotor by inductive braking the LC tends to generate at higher frequency harmonics ( refer to chorus motor patents as to existence of this harmonics) (other application).

That is due to excess capacitance and over running (tendency of rotor to spin at higher frequency than line frequency) as ANGLE of rotation imposed on the 3 phase lines exceeds and overlaps the next creating a counter rotation null field (braking ).

If you have found that if you don't get the caps changed over quick enough this shudder happens and the RPM drops dramatically, and have to reboot again and go though the same sequence. Use less starting capacitance were motors hums in frequency beat mode but not exceeding the slip limit.. or use centrifugal start switch to drop off capacitor at bellow maximal rotation speed a centrifugal switch from 1 phase motor can be used for this at proper speed of course , if you got 3200 RPM at 60cps you must use a switch for 3450-3600 RPM range if 1800 then 1725 to 1800 and so on .

EMP warfare resistant is a centrifugal start switch installed in fan housing external for easy maintenance.. Mostly cleaning if not sealed.

For variable frequency a switch to 3 phase inverters is recommended the RV one phase set up is test bed to understand phase relation to frequency capacitance and impedance , in 3 phase alone is a bit nightmarish without the single phase inverter experience needed to attain OU conditions were in 3 phase this is attained with pulse length frequency and amplitude , here we reach a point were the hi level engineering must be addressed in a well funded R&D lab were all of us can participate ( out current stagnation point).