circuit of voltage mode control of boost converter

[mengghee]

can anyone tell me how i can built a voltage mode control of a boost converter ? circuit diagrams ? i wwant to build a boost converter from 5v to 10v with output current of 500mA. thank you very much

 

[jluhzw]

hello mengghee
I think your quenstion are too wide to be answered.
if you build it with the control chip, you can choose some datasheets to complete.
There are many companies have the chip,such as the Linear Technology Corporation (https://www.linear.com/index.jsp),Maxim(www.maxim.com)
TI and so on.
But if you want to built it by yourself.In my opinion,there something you need do.
Firstly,you need know how the boost converter work.It means you should study the basic knowledge about switch mode converter,especial the boost one.
Second, you need know the how to control the conveter.If you want to build a boost conveter,you should design the error amplifier, PWM comparator ,the voltage reference and so on.
I upload some basic material for you,which may be useful for you!
you also can find many useful materials in www.google.com
best wishes!

 

[mengghee]

hi jluhzw,

I have understood the basics of boost converter. I am just looking at how the control schemes is beeing build. what component, values of component etc... thank you very much.

regards,
mengghee

 

[hoonsk]

The dominant pole of the voltage mode moves a wide range with respect to Vout/Vin ratio, inductor, output cap. If you don't mind slightly low loop gain, you should just have the feedback directly goes to the comparator instead of using error amp.
Generally, I guess you know, boost converter uses current mode control.

 

[mengghee]

well ... i thought i can either chose voltage control mode or current control mode .... instead of having just current control mode

 

[hoonsk]

I have a hard time compensating the voltage-mode boost converter and have to further drop the loop-gain by having resistor divider to drop the feedback voltage. I have worked with two current mode boost, no problem, quite robust, although it is slightly more complex as we need to sense inductor current.

 

[mengghee]

hoonsk,
do you mind guiding me through current mode control ? i actually have a very strong intention on doing current control mode but ... i find the complexity rather too much .... can you post me some design schematics or sites which will give me a clearer view ? thank you very much

 

[hoonsk]

I can try to post my thesis online, it is a huge file, as you can see, I am a newbie, I still don't know how to post files, getting points and stuff, give me some time...

unfortunately, current mode is more complex than voltage mode with extra inductor current sensor and slope compensation, but so far I've seen in most seminars, people used alot of current mode, esp when working in continuous mode.

Have you pick your application ? Simplest thing to do is to go to one of the company website e.g. www.ti.com, and grab one of the specs e.g. white LED boost converter, with the associated components and work from there. The application notes can be very helpful, pertaining the power train design : L & C choice, but they seldom tell you how the error amp and protection stuff are designed.

hoonsk,
do you mind guiding me through current mode control ? i actually have a very strong intention on doing current control mode but ... i find the complexity rather too much .... can you post me some design schematics or sites which will give me a clearer view ? thank you very much

 

[mengghee]

well .... actually i am doing a feed forward control of boost converter ... i have completed my project analysis, simulation etc ... but i am actually trying to get more grades ..... i have been told by my lecturer that if i do feedback looping .. i will get better grades ... i am very interested in current mode control but i really find it hard without anybody helping .. i tried posting but no reply before ... now i post voltage mode ... u replied ... thanks thanks .. my boost converter converts 5v to 10 v .. load current is 500mA. i have also looked in various sites and data sheets .. they do show the theory but not .. how to design it ... such as design of the pi controller and so on ... thank you very much