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- เผยแพร่เมื่อ 10 ก.ย. 2024
- In this video Dr Ali Shirsavar from Biricha, and supported by @OMICRONLabTutorials, explains in clear and simple terms what we mean by right half plane zero (RHPZ), the problems that is causes, how to identify if your PSU has a RHPZ and how to design our power supply control loop to mitigate its impact.
Wow!! I have never seen such a crystal clear explanation!
There are a few ways to avoid right hand plane zeros in a flyback. If your applications allows it one can use DCM (Discontinuous Mode Conduction). The other way is to use a controller that does
not allow a duty cycle beyond 50%. But these also have disadvantages, higher peak currents for example. Flybacks, despite their apparent simplicity are surprisingly complex circuits.
Maybe Dr Ali could do a video on that. Otherwise an other excellent video as all his others. Learned a great deal from him.
Best explanation on rhpz. Thank you!
Your BIG FAN from Thailand. Thank for your informative videos Dr. Ali
RHPZ - Right Half-Plane Zero. Hear about this term for the first time. Thank you.
Nicely explained. You were correct, you explanations are very easy to follow.
very good explained, I have the sensation that many designers forget about the RHPz. I usually use a pole zero diagram in addition to the bode plot.
Big Fan! Nice explanation!
Your flyback topology is wrong, the forward biased dot, being inverted, cannot deliver any power to the load. The dot is down and the diode is reversed.
It's just an unfamiliar representation: with the secondary dot-phasing and diode direction as shown, the output and input have opposite polarities. The winding phase and diode are usually reversed so the input and output polarities are the same. That's just a convenience; it's not necessary in order to make the circuit work.
Assume the supply polarity is positive at the top. During the Don interval, the supply can force current into the primary because the switch is on. That means the positive end of the primary is its dot end. Therefore the secondary's dot end is also positive, so the diode is reverse-biased and stays off.
During the Doff interval the primary is no longer sinking current, because the switch is off. Being an inductor though, it still tries to keep current flowing through itself in the same direction as before. It can only do that by trying to force current through the circuit, so its polarity must reverse: its positive end becomes the non-dot end. The secondary therefore also becomes positive at its non-dot end. That forward-biases the diode, which turns on and delivers current to the capacitor and load - with the output positive at the bottom and negative at the top, opposite to the supply's polarity.