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kivdenn
Nobel Prize Winner
Uganda
535 Posts |
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wasssup1990
Nobel Prize Winner
A Land Down Under
2261 Posts |
 Posted - Aug 19 2010 : 04:43:58 AM
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Ewww! Like totally don't use those designs, they are crap. The least you need to make is a DC-DC converter (like 12VDC to 340VDC) and then H-bridge that 340VDC through an output filter to your load. Simple. You should at least get above 70% efficiency for a beginner and definitely into the high 90's if you really know what you are doing. It actually isn't too hard to modify this commonly used approach to get a pure sine wave output rather than a simple modified square wave output.
Good luck. |
When one person suffers from a delusion it is called insanity.
When many people suffer from a delusion it is called religion. |
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kivdenn
Nobel Prize Winner
Uganda
535 Posts |
Posted - Aug 21 2010 : 02:04:52 AM
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| But that web site people say they have tried to build it and it works well. Are they lieing? |
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wasssup1990
Nobel Prize Winner
A Land Down Under
2261 Posts |
Posted - Aug 21 2010 : 03:01:30 AM
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I never said that it wouldn't work well. The topology it uses is old now. This design is bulky, heavy and probably not very energy efficient compared to the modern topology I mentioned in my last post. I have an old 1990's UPS that uses a similar inverter topology that you have posted and one problem with it is that it uses quite a noticeable amount of energy without a load attached. This is even more so if the transformer is of poor quality or not designed correctly.
With your topology, power is wasted in the output transformer since the primary and secondary windings have quite a lot of resistance (maybe a few ohms but it matters) compared to the rather low resistance paths of a SMPS based inverter.
I noticed that you are prepared to use an IC in your circuit, in that case you should build a SMPS based inverter instead as they all use ICs.
I saw those pictures in the link you posted and I saw big heat sinks and big transformers. Why I say? Do big heatsinks and big transformers turn you on? You should know that big heat sinks mean that design must waste quite a bit of energy. Now compare them to the cup holder sized inverters that are out there. They all use SMPS based topologies. Now you choose the power supply that suites you. Remember a cooler and more compact design generally means a longer life span and definitely means more energy efficiency, which means your battery will last longer with the same output power relative to an inverter that is wasteful.
Hope this helps. |
When one person suffers from a delusion it is called insanity.
When many people suffer from a delusion it is called religion. |
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wasssup1990
Nobel Prize Winner
A Land Down Under
2261 Posts |
Posted - Aug 21 2010 : 03:15:22 AM
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| Oh yeah. Also notice that they mention absolutely nothing about energy efficiency in their article. You've got to start asking questions then. The article title claims "250 to 5000 watts" whilst the finer print reveals the claim that they only made a 1500W inverter and the actual schematic submitted is for a claimed 250W inverter. |
When one person suffers from a delusion it is called insanity.
When many people suffer from a delusion it is called religion. |
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wasssup1990
Nobel Prize Winner
A Land Down Under
2261 Posts |
Posted - Aug 21 2010 : 03:22:08 AM
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Here is a 150W modified sine wave inverter.
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When one person suffers from a delusion it is called insanity.
When many people suffer from a delusion it is called religion. |
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RRITESH KAKKAR
Apprentece
India
23 Posts |
Posted - Aug 21 2010 : 10:51:51 AM
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| Plz tell me how to know power of self made inverter & calculte no of turns intransformer as they are not mention in it.....! |
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audioguru
Nobel Prize Winner
Canada
4218 Posts |
Posted - Aug 21 2010 : 6:07:27 PM
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quote:
Originally posted by RRITESH KAKKAR
Plz tell me how to know power of self made inverter & calculte no of turns intransformer as they are not mention in it.....!
Power equals the voltage times the current. You know how much output voltage then you pick a max current and multiply it with the voltage to give the max wanted output power.
The ratio of the number of turns in a transformer is the ratio of the drive voltage to the unloaded output voltage. Then calculate how the resistance of the windings will reduce the output voltage with a max load by using Ohm's Law. |
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kivdenn
Nobel Prize Winner
Uganda
535 Posts |
Posted - Aug 22 2010 : 02:05:52 AM
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| Thanks all for your input, do you think for a 500watt inverter the energy loss can exceed 6 watts ? Thanks |
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wasssup1990
Nobel Prize Winner
A Land Down Under
2261 Posts |
Posted - Aug 22 2010 : 02:52:11 AM
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| Only a very good design can achieve that. Your talking 98.8% efficiency there. It certainly is possible though. If you are wanting to produce a sine wave output then it is probably unlikely you will achieve that efficiency since the output filtering required will be a bit more lossy than an output filter for a modified sine wave inverter. Also the sinwave generation MOSFET's will be switching faster than the fundamental output frequency so the switching transition time to MOSFET on/off states ratio will be higher than switching at the fundamental output frequency of which a square wave inverter would be doing. In layman's terms this simply means the MOSFETs will be dissipating more power. A Fundamental output frequency would typically be 50Hz or 60Hz depending on your country. |
When one person suffers from a delusion it is called insanity.
When many people suffer from a delusion it is called religion. |
Edited by - wasssup1990 on Aug 22 2010 02:54:35 AM |
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RRITESH KAKKAR
Apprentece
India
23 Posts |
Posted - Aug 22 2010 : 06:54:11 AM
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| PLz tell I want to make inverter & for this I have to generate freq. & as I am Doing it by 555 ic But I have problem on Connectihg It to Transformer as It drives more current for this tell me solution eg: like Mosfet or transister Circuit..............! |
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wasssup1990
Nobel Prize Winner
A Land Down Under
2261 Posts |
Posted - Aug 22 2010 : 09:08:27 AM
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quote:
Originally posted by RRITESH KAKKAR
PLz tell I want to make inverter & for this I have to generate freq. & as I am Doing it by 555 ic But I have problem on Connectihg It to Transformer as It drives more current for this tell me solution eg: like Mosfet or transister Circuit..............!
If you are having difficulty finding a circuit you would probably also have difficulty understanding and subsequently building a well functioning inverter. Seriously that's why I don't put the effort in to find schematics for you people, no offence. I have tried in the past and have tried just now to educate you people that creating something that works requires an understanding of how the device actually works! Schematics aren't instructions on how to put a jigsaw puzzle together using electronic components... well with simple circuits it is but not for inverters. Also your grammar is horrible. How would you understand someone's technical explanation I wonder.
Good luck! |
When one person suffers from a delusion it is called insanity.
When many people suffer from a delusion it is called religion. |
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kivdenn
Nobel Prize Winner
Uganda
535 Posts |
Posted - Aug 23 2010 : 01:26:10 AM
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So to what level of efficiency would you put this type of inbverter incase the transformer is well wound.
Also I woulkd like to ask Mr Audioguru wether this type of inverter has a 'shoot through' current moment as it is in the case of a simple CD4047 square wave inverter we discussed in some other thread. Thanks
Dennis |
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wasssup1990
Nobel Prize Winner
A Land Down Under
2261 Posts |
Posted - Aug 23 2010 : 03:18:40 AM
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Okay, so to get a rough idea without doing any calculations it is a good idea to do your research into inverter products that are already out there. You will find that heavy toroidal transformers are typically used in low frequency inverters and they guarantee a minimum efficiency that is usually lower than a SMPS based inverter's (high frequency inverter) minimum guaranteed efficiency.
Here is a low frequency inverter of similar internal functionality to the inverter design in question on this thread.
LF Inverter
You can see that they guarantee an efficiency greater than 70%.
However doing your reasearch will reveal that these inverters...
HF SMPS based Inverter
... have a guaranteed minimum efficiency of greater than 90%!!!
I hope this helps you make more informed design choices, and good luck! |
When one person suffers from a delusion it is called insanity.
When many people suffer from a delusion it is called religion. |
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wasssup1990
Nobel Prize Winner
A Land Down Under
2261 Posts |
Posted - Aug 23 2010 : 03:30:16 AM
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| Oh and look at the weight difference! The HF inverter weighs just 23% of the LF inverter! |
When one person suffers from a delusion it is called insanity.
When many people suffer from a delusion it is called religion. |
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kivdenn
Nobel Prize Winner
Uganda
535 Posts |
Posted - Aug 23 2010 : 04:06:09 AM
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| Is there any way we can modify it to give a modified sine wave output, may be by adding a CD4025 IC or something like that? Thanks for all your input on this I really appreciate. Dennis |
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Another PWM inverter circuit
PWM inverter.gif