For designing 50v,100v,150v dc power supplies. - Page 1
Forum section: electronics / general

author: shibas
author_rank: Newbie
timestamp: April 09, 2013, 08:45:42 am
content: How to design 50v,100v,150v power supplies?I need to use these power supplies for an actuator(Piezo stack actuator).Can any body help me with the design equations for the above mentioned power supplies along with their circuit diagrams and necessary materials or notes for designing the power supply?

author: tom66
author_rank: Super Contributor
timestamp: April 09, 2013, 09:39:27 am
content: Umm... Probably not.You haven't provided anywhere near enough detail.1. What kind of input power supply do you have available?2. How much current is required on each rail?3. What kind of stability do you need?etc.etc.Most people would probably suggest off-the-shelf DC-DC converter modules if this is your first attempt at designing a power supply of any significant nature.

author: KJDS
author_rank: Super Contributor
timestamp: April 09, 2013, 11:16:33 am
content: just stick a diode and a cap on the mains, what could possibly go wrong?

author: eevblogfan
author_rank: Frequent Contributor
timestamp: April 09, 2013, 11:26:14 am
content: KJDS , VAST, HUGE, ENORMOUS, BIGG NO-NO to you !before someone got injured I MUST tell *DO NOT PLAY WITH MAINS IF YOU GOT NO EXPERIENCE * it is freaking dangerous and you musn't apply silly into that field

author: shibas
author_rank: Newbie
timestamp: April 10, 2013, 04:43:05 am
content: I think we can design these dc power supplies using a transformer,a bridge rectifier and a capacitor.But what should be the different voltage and current ratings of the transformer for designing the 50v,100v,150v dc power supplies?What should be the value and voltage rating of the capacitor?Can u help me by providing either the circuit diagrams of the power supply design using the transformer,bridge and capacitor for the 3 different dc power supplies of 50v,100v and 150v or by providing the links for getting the necessary materials,diagrams,equations for designing the 3 dc power supplies of 50v,100v and 150v.

author: tom66
author_rank: Super Contributor
timestamp: April 10, 2013, 10:39:09 am
content: We are not doing your homework/coursework/job for you.It should be fairly obvious what the minimum rating of a capacitor on a 50V rail should be. Bear in mind, a capacitor will usually fail if the voltage rating is less than what is applied across it, especially if the difference is large.As for a transformer, you need to understand RMS and peak voltages but basically you want an RMS voltage that's around 70% of the DC output voltage. As for current rating, a transformer will catch fire or fail (if it's feeling boring) if you exceed its current rating. So you should make sure you don't.Then you need to size the output capacitors based on maximum tolerable ripple etc. A general rule of 1000uF/amp can work well for lower output voltages, though there are a lot of exceptions to this rule.

author: eevblogfan
author_rank: Frequent Contributor
timestamp: April 10, 2013, 10:50:52 am
content: heyjust saw the 70% rule of thumbbased on my own experience with transformers , I know that the ratio between the ACVRMS of the transformer and the DCV after filtering * with * full load , is 115% ( Ie , 12(AC)V;R.M.S and around 13.8VDC )and as per the ratio * without any load * is 125% ( Ie, 12(AC)V;R.M.S and around 15VDC )so I hope I am correct . though this is from real world measurements and of 5 different transformers and I found that to be correct with all of them . part aluminum winding and part copper , the main differences is the temp at full working power ( 75C on the aluminum while ~60C on the copper )I am stand to be correct thoughCheers

author: free_electron
author_rank: Super Contributor
timestamp: April 10, 2013, 03:13:21 pm
content: There is anothe thing at play here... You say it is to drive piezo stack...Piezo stacks need ac voltage... Preferrably at a high frequency in the range of 30 to 40 kilohertz...That is, if you are making an ultrasonic system.If the stack is used in impulse mode ( like common rail injection for a car ) you need a supply that can handle fast transients. The pulse current is high and the voltage cannot collapse... A piezo element behaves as a tuned parallel L-C . The c is pretty high ..