Hello, this is my first post,
I am writing this post because I hope that you will help me solve my problem.
Designs adjustable Half-Bridge converters with 0-30V and 0-20A parameters. The power block itself is able to give over 800W at maximum PWM and it is not a problem. The problem is the feedback loop, which works unstable. I thought it might be a problem with the low choke value, originally 47uH, but then I used the 250uH inductor and it's even harder to stabilize the converter.
In general, the whole works, it is possible to regulate the voltage and current, but there are considerable squeaks of the transformer at low voltages, ie 10V and quite large currents of 10A. There are also significant noises at the output as well as sinusoidal oscillations. Generally, these are noises with an amplitude up to 1V when measuring AC on an oscilloscope
The loop is created on the external LM324 operational amplifier, while the internal SG3525 amplifier works as a voltage follower. The switching frequency of the transformer is 40kHz. Using the book Switching Power Supplies fromA to Z - Sanjaya Maniktala I used and calculated coefficients for the type 3 compensator for the following data:
fESR = 6392 Hz
fLC = 424Hz for 47uH inductor and 184Hz for 250uH inductor
fz1 = fz2 = 424Hz
fp0 = 260Hz
fp1 = fESR = 6392Hz
fp2 = 1/2 fsw = 20kHz
frcoss = 1/10 * fsw = 4kHz
Vramp = 2.8V
Vin = 43V (output voltage after diodes)
fsw = 40kHz
Cout = 3 x 1000uF
Total ESR = 8.3mohm
I calculated the following element values for the 47uH inductor
C1 = 30.6nF -> I used 33nF
C2 = 17.5nF -> I used 18nF
R2 = 12.3KOhm -> I used 12kohm
C3 = 678pF -> I used 680pF
R3 = 1.4kohm -> I used 1.5kohm
For inductor 250uH, the coefficients are:
C1 = 30.6nF -> I used 33nF
C2 = 42nF -> I used 42nF
R2 = 28,3kohm -> I used 27kohm
C3 = 297.6pF -> I used 300pF
R3 = 600ohm -> I used 560ohm
Despite many attempts, I have no idea where the problem is.
It also adds inverter schemes. The diagrams are two because the inverter consists of 2 PCBs
1. PCB is a power part
2. PCB is the control part
Thank you for your help