Neo-Aerodynamic

Pic 2

 

Neo-Aerodynamic LTD Co.
a solution for today energy crunch


Grid-Tie INVERTER

Patent pending.
But your are free to copy and build on your own risk for individual usage and noncommercial purpose.

Not to be connected to the national grid without proper authorization.

As by products of our research we have come up with a logic to build grid tie inverters. They are very inexpensive and for the benefit of the PEOPLE AT LARGE we post here. We do not present as how to make but the process how we build them and for informative purpose only.

Super Warning: Dealing with live AC grid may cause bodily harm or death; therefore any attempt should be only done by well trained and professional.

Schematic:


Part list:

  • Some heavy gauge wire and quick connector (from local hardware/electrical store
  • 1- piece of 6" x 8" aluminum plate as heat sink.
  • Terminal block for DC and AC 110V wall plug/receptacle.
  • Some screws, small bolts, and nuts.
  • Even its back side  looked complex but it is exactly the same as the schematic above. It's front is much clearer and simpler.
  • The rated wattage of the device are defined by the ohm law W=V *I, in this case it the alternistors are rated at 600V and 25Amp;  assuming that  the the capacitor(s) is large enough.
  • Warning: This system could drain a car battery in a few minutes.

We first use a Variac to try on low AC voltage of about 24V. Only when we are comfort with the system then you connect to the grid.

* The parts are selected because we have some extra and handy.

Note:

  • On the schematic the symbol of the triac does not state pin T1,T2 or MT2, MT2 but pins the actual work does make the difference. All the MT2 pins are connect to the AC  source as at the schematic.
  • DC supply can be anywhere from 3-50V
  • At times we place 4 fuses after MT1 pins even though in our tests it only blew one when we abuse.
  • You may need to try on different capacitor sizes to select the one that fit your configuration.
  • As it; most household breakers; 10A ,15A, 20A; may not be strong enough to sustain the uploading and strip.

Advantages:
  • Wide range of DC voltage from 3->50V.
  • Always in phase/synchronous to the grid.
  • The system automatically turns to idle (inactive) when AC the power goes down
  • Instead of using over imposing technology which represent creation of higher voltage and synchronous AC, the technology use the amplification technique which always eliminate the islanding problem.
  • No CPU (eliminate software, firmware problem)
  • Only use passive components.
  • Theoretically, the design has 100% efficiency. The only lost is the heat (equivalent to a 3w night light bulb?)

Disadvantages: (of this built)
  • Fuse blow if the DC voltage raise above 50V.
  • Only works on 110V AC configuration of 1 hot and one ground (US common residential electric system). 
  • Fuse blow in 2 hot wire AC configuration.
  • Power surge may cause fuse blown.


Some notes about the technology.
  • The old method of building a grid tie inverter is to creating an AC current that has higher the amplitude but having the synchronous frequency with the grid. The the two are parallel connected as if we seen in the battery charger.
  • If one traces or simulates the current it is exactly as if it is a charger to be used to charge a battery bank that contains 8 serially connected batteries. It can be used exactly as it (if the polarity is reversed).
  • And the circuitry (of that battery charger) works as (grid tie) inverter when it allows the reverse procedure to happen when it use the switching mechanism to produce a DC instead of using the blocking the reverse current as if it is in the conventional type of battery charger. Therefore the capacity of the device is limited by the rated of the component in AMP and the capacity of the capacitor bank.
  • The technology that we work here lie behind a new approach:
  • First it converts the AC current to the DC not by blocking the reverse bias as of the diode but switching the polarity of the current every time it crosses zero as if one turns a DPDT switch 120 times per second.
  • Secondly; The system now provides the conversion in both directions. AC->DC and DC->AC. The rest of the work is to add some voltage at the DC side at the same time to expose it to a brake to remove unwanted power spikes.
  • The novelties are:
    • One does not need to worry  about the AC frequency.
    • Because it use switching mechanism to achieve the DC then both the AC and DC side interact each others. Uploading power to the grid is a simple job of raising the amplitude at the DC side.  It's simple.
  • Such the technology? simple? anyone can do it? Why nobody has ever attempted before? -Perhaps it's not obvious at the first glance. This is just a fall through from other projects; our intention at the time was not to develop a GTI (grid tie inverter). If is is our main ficus then definitely; this approach is not among the options.

Grid connection & UL Standard issues:

UL Issue:
UL 1741 is the de facto standard for grid tie inverter. and it's not applicable to this type of grid tie inverter.

The UL standard applies to grid tie inverter as if it is an independent AC power plan with: Allowable tolerance of the power curve,  when it is safe to upload, etc . . .

This type of grid tie inverter is not an independent power plan and nor it generates power curve, nor it has the capability to be islanding.

This type of grid tie inverter contains only passive components reacting according the change from the grid and does not inject any current into it.

Grid connection:

For many decades each and every individual component has been  approved and certified to be connected to the grid. Their manufactures spent millions for that purposes.

It's just happened on the way how to wire them making it to function as a grid tie inverter. I don't know how one can forbid user to use the products that they approved and certified. The same way one goes to the local store buying timer, sensor, charger, etc . . . .

In the nutshell, the system also is a functional battery charger, when battery bank of 8 serial unit is working in both direction. Such AC->DC converter; 'battery charger' only allows user to reverse its procedure to (grid tie) inverter by switching the battery polarity.

Beside nothing like this has been done before; honestly no one knows how to deal with it.

Personal I think the power companies may be able to stretch their arm on new installation (grand father clause?)- Or they can pass the law to restrict the sale of those components . . . . .