| Electronics > Projects, Designs, and Technical Stuff |
| Half-Bridge 0-30V, 0-20A Feedback loop problem |
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| paladyn:
Hi everyone After long break i would like to resurrect topic. I changed LC filter to 300uH inductor and total capacity 9000uF plus common mode choke. Also i bought Analog Discovery 2 to measure bode plot. Quick recap: Topology - Half Bridge PWM Controller - SG3525 Mosfet Drivers - HCPL3120 Transistors - IRFP460 Rectifer - 4 x 60CPQ150 Voltage after diodes on max PWM - 43V Target output voltage 0-30V (regulated) Feedback OP-AMP - TL3474C Used compensators - Type 2 , or Type 3 Load = about 1ohm LC_Filter schematic I have charts bode plot with out compensator, and few charts for compensator type 2 and type 3. Can you evaluate where put zero and pole looking to uncompensated chart. Also i would ask you to evaluate attached charts for compensator type 2 and type 3. Feedback loop uncompensated Output = 5V Feedback loop uncompensated Output = 12V Type 2 compensator Output = 5V Type 2 compensator Output = 12V I have hope that toogether we will resolve feedback loop compensation problem, and acquired knowledge will be usefull for others designers |
| paladyn:
Type 3 compensator VOUT = 5V Type 3 compensator VOUT = 12V |
| T3sl4co1l:
I suppose it's too late to recommend an average current mode control... The CMC in the filter by the way, can't possibly do anything if it's shorted between GND and GND; indeed if the circuit is common ground, the solution is easier because common mode noise can be controlled by layout alone. Tim |
| paladyn:
Sorry, I made mistake during drowing schematic. I will correct atachment above T3sl4co1l can you tell more about average current mode control. Why is it better ? |
| David Hess:
Sometimes I am amazed that anybody gets a voltage mode variable input or output switching regulator to work. |
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