Help me design a 1/2 kW SMPS 2-50V 0-10A

[FvM]

Re: 1/2 kW SMPS 2-50V 0-10A

The current sense is a standard feature of current mode PWM controllers. It's not intended to sense the output current. It's an auxilary control loop to improve the dynamic behaviour of the main control loop and a means to protect the switcher against overcurrents. You'll find detailed explanations of current mode in text books and PWM controller applications notes.

The auxilary winding providing the voltage feedback is primarly used as low voltage power supply. The 220k resistor is only sourcing a small start-up current, not able to supply the controller in operation.

A secondary voltage feedback will achieve better regulation but auxilary winding feedback is often sufficient for basic requirements.

 

[AMSA84]

Re: 1/2 kW SMPS 2-50V 0-10A

I see, but if you compare the 1st image with the 2nd one, and if the auxiliary winding is used as low voltage power supply, how the voltage is regulated in the 1st image? As you can see, there is no secondary voltage feedback then.

I thought that, for example, in the 1st picture, that auxiliary winding was to regulate the output voltage. I thought that it was another way to regulate too the output voltage, beside the secondary voltage feedback. Do you understand what I mean? Am I wrong?

Thanks in advance.

 

[FvM]

Re: 1/2 kW SMPS 2-50V 0-10A

how the voltage is regulated in the 1st image

By the auxilary winding, it's dual use.

I'm talking about the disadvantage of this solution in my previous post.

 

[AMSA84]

Re: 1/2 kW SMPS 2-50V 0-10A

Ok. I got it.

Anyway, it is a little bit confuse. In some application we see those two kind of configuration and for those who are just beginning with this might be confusing.

Thanks FvM.

 

[karthick1987]

Re: 1/2 kW SMPS 2-50V 0-10A

Hi guys,

I have been going through the SG3526 and the UC3845 datasheets and didnt understand the function of the compensation pin? What does it compensate?

Regards
K

View attachment SG3526_PWM Control.pdf
View attachment UC3845_SMPS_Current controller.pdf

 

[DeepOne]

Re: 1/2 kW SMPS 2-50V 0-10A

apropos with FET-s bridge on GDT are got improved results.

 

[DeepOne]

Another tl494-based PSU ). PCB obtained by toner transfer method.

 

[goldsmith]

Hi Deep one ,
Ha ha ! you are using this way to make PCBs too ? i'm using this way and photograph method too ( UV bulb ) .
Good luck
Goldsmith