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I am new to field of charger designing but I have to complete one project of battery charger for 48 V 20 Ah Lithium-ion battery having 5 A max charging current.

The previous person had done work of designing PFC boost converter which is giving 400 VDC now I have to design the next circuitry but i do not know even fundamentals of charging like cc, cv charging modes and how to obtain them, how internal resistance plays role in current designing. So which books or links I should refer to start the research.

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  • \$\begingroup\$ You need a step down converter - look for application notes from the major manufacturers who want you to buy and use their chips, in these 'app notes' they tell you in detail how to do it. Then you need to control this converter so it gives you a suitable voltage and current profile to charge the battery - look at batteryuniversity.com for details for your battery type. \$\endgroup\$ – Neil_UK Mar 19 at 13:32
  • \$\begingroup\$ Hello Jay, welcome to eesx. Can you clarify your requirements? I reckon your charger will need to be powered with 400 VDC, is this correct? What kind (chemistry) of battery will you need to charge? \$\endgroup\$ – Vladimir Cravero Mar 19 at 13:33
  • \$\begingroup\$ These systems are called "fuel gauges" \$\endgroup\$ – analogsystemsrf Mar 19 at 13:40
  • \$\begingroup\$ Yes now the design is powered by 400volts dc supply. I ned to charge 48 volts 20ah lithium ion battery having 5 amp max charging current but I do not know about the charging concepts such as how cv,cc modes should be obtained and role of battery resistance so from where can I study. \$\endgroup\$ – Jay Mar 19 at 14:14
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On the output of your PFC you will need an isolated DC-DC converter for safety reasons. An LLC resonant converter would be one approach, due to the high efficiency and pre-regulated 400V input. Be sure to follow all the regulatory requirements for isolation/creepage/clearance etc.

Here's an example of a PFC-LLC design that's very close to your requirements: PFC-LLC design

Next you will need a charge controller capable of charging your battery. Here's an example of a design: 48V Li-Ion charger

You can read all the application notes from the main players in power management to get a better idea of what's required. It's not a simple task to go from a non-isolated PFC output to a battery charger, so you might want to get some help if you haven't done offline power before.

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  • \$\begingroup\$ I refered LLC TIDA-00355. But it is not possible to get all the required component in short duration. A came across this encrypted-tbn0.gstatic.com/… with this can I charge the battery. \$\endgroup\$ – Jay Mar 19 at 18:05
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You can refer TIDA-00355 In this guide Lithiun Ion charger is made using PFC+LLC combo. You have already PFC stage, so just study throughly Half bridge LLC to get output as per your requirement. You need to fine tune the LLC Controller and CC-CV feedback elements according to your output voltage and current requirements.

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  • \$\begingroup\$ Can I use buck converter as a next stage ? What kind of interface i will require to charge battery with buck converter output \$\endgroup\$ – Jay Mar 19 at 17:43
  • \$\begingroup\$ Theoretically speaking, yes you can. You also need to make provision for implementing CC-CV profile for Lithium Ion battery. This thing is very well given in TIDA-00355 design. \$\endgroup\$ – Avinash N. Chaure Mar 19 at 17:47
  • \$\begingroup\$ google.com/url?sa=t&source=web&rct=j&url=https://… \$\endgroup\$ – Avinash N. Chaure Mar 19 at 17:57
  • \$\begingroup\$ You can refer above link to study Battery charger fundamentals for Li-Ion and Implement CC-CV profile using PIC \$\endgroup\$ – Avinash N. Chaure Mar 19 at 17:59
  • \$\begingroup\$ Yest I refered TIDA-00355. But it is not possible to get all the required component in short duration. A came across this encrypted-tbn0.gstatic.com/… with this can I charge the battery. \$\endgroup\$ – Jay Mar 19 at 17:59

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