BTECH EEE: Electro-kinetic road ramp for power generation & Switch Mode Inverter

Switch Mode Inverter

A switch mode inverter is such kind of inverter that use a switching regulator to convert the DC voltage to another DC voltage and then convert this DC to AC voltage. As the high frequency switching voltage converter is more efficient than the regular converters so switch mode inverter is more efficient than the normal low frequency inverter. But the circuit is more complex than the normal low frequency inverters. Unlike a linear power supply, the pass transistor of a switching-mode supply continually switches between low-dissipation, full-on and full-off states, and spends very little time in the high dissipation transitions, which minimizes wasted energy. Ideally, a switched-mode power supply dissipates no power. Voltage regulation is achieved by varying the ratio of on-to-off time. In contrast, a linear power supply regulates the output voltage by continually dissipating power in the pass transistor. This higher power conversion efficiency is an important advantage of a switched-mode power supply. Switched-mode power supplies may also be substantially smaller and lighter than a linear supply due to the smaller transformer size and weight. Switching regulators are used as replacements for linear regulators when higher efficiency, smaller size or lighter weight are required.

So what is the steps to make a switch mode inverter?

Yes! First of all, we need to find the block diagram of a switch mode inverter.

we have a input here, and we need to convert this input low voltage to a high voltage. Because we need to get 220V AC in the last. So what we need? we need 220X√2 = 311V DC to get 220V AC (ideally). So here is our first block diagram:

Now we have a high voltage DC (315V). We have to keep this voltage little bit higher because, there will be some voltage loss in conversion. To get excellent result we have to make this voltage converter strong and clean in operation.

Then we have to convert this High Voltage DC into High Voltage AC(220V AC). To convert this DC to AC we need H-Bridge. So the next block diagram will be:

And now we are getting out AC voltage. Yes! But its all theoretical. In real hardware its much more complex.

Now Lets see what I did in my case…

In my case I started from making a good DC to DC converter first. I started from very beginning, I made a flyback DC/DC converter first! But it was not good enough. Then I tried to make another one based on Push-Pull topology. And this time I got good result. And I was able to make this:

The output was DC (>350V). And after some critical tests I was able to make another one. Besides, I made a H-Bridge to convert the DC into AC at the same time. The H-Bridge was working good. I used a micro-Controller (PIC16F73) to generate the pulses to drive the H-Bridge. Then I tested the H-Bridge with a low voltage (12VDC) to ensure that the Bridge is working pretty well. After ensuring, I made another DC/DC converter to take a load of 200W. And here is these two blocks:

Yes! Its working.

Now its time to make something commercial. And I made this:

And the Output wave-shape was:

This was a first step to make a commercial design. Its capacity was 150W. And the last one was:

This one was able to handle up to 400W load. The output was 50Hz 220V AC. I kept an option in this circuit that it can be used as normal inverter with changeover and with an option to add a charging adapter.

Electro-kinetic road ramp for power generation, the new way of thinking…

The electro-kinetic road ramp is a method of generating electricity by harnessing the kinetic energy of automobiles that drive over the ramp. In June 2009, one of the devices was installed in the car park at a Sainsbury’s supermarket in Gloucester, United Kingdom, where it provides enough electricity to run all of the store’s cash registers. The ramp was invented by Peter Hughes, an electrical and mechanical engineer who is employed by Highway Energy Systems Ltd. The company says that under normal traffic conditions, the apparatus will produce 30 kW of electricity. Other proposed applications for the road ramps include powering street and traffic lights, heating roads in the winter to prevent ice from forming, and ventilating tunnels to reduce pollution.

The idea was dismissed as Talk of ‘kinetic energy plates’ is a total waste of energy in the Guardian by David MacKay, the professor of natural philosophy in the department of Physics at the University of Cambridge. MacKay wrote, “The savings from parking at the green car park thus amount to one four-thousandth of the energy used by the trip to the supermarket.”

It is taken from wikipedia. Its really a awesome idea to generate power. Input is almost free! So, we can call it generating electricity for free! Yes, its one kind of free energy generation. In my own lab, I’m trying to make one of this ramp. It was a project work from a university student team, but I was trying to help them to make this awesome project.

First of all we need to know about the concept of the project. If we want to use the kinetic energy to convert it into electrical energy, we have to make a mechanical mechanism to rotate a generator. And the kinetic energy will come from the vehicles of the road.

First of all, we need to see this video to clear the concept.

http://www.youtube.com/watch?v=_cazBrpoMYg

Now its clear to us. So, we need to make the mechanical part first. I tried in my workshop with help of some experts in mechanical engineering as I’m not expert in that field. I’m expert in electronics. Any way, one of my known person helped me to make the frame. For demonstration type mechanism, we made this:

The frame was made to handle up to 200Kg Load. Then we updated the frame and inserted the ramps. and the mechanism which will support the ramps. We used springs with shaft holder below the ramps so that the spring and shaft can’t displace. The system have come in this form:

In the mean time, I designed the control circuit in my lab. In the control unit, I used two different batteries so that one can be used in case of the fail time of another one. Also, if one battery is fully charged then the system is able to charge the other one. And in case of load handling, the system will draw power from the first one until it discharged in the rated point. And then the system will switch the load to the second battery. This battery system can be extended in future if required. Also I put a sensor (LDR) so that the load( may be street lamp) can be used only at night time. This is totally optional. The control unit is here: 01092013639

The total system is still under R&D. The mechanism is being tested. After fully tested, I’ll post the rest images and news about it. The final one will be something like this: