| Author | Message | ||
     Panshovevo |
The former owner of Compu-Fire sent me a link to a forum thread that included this detailed explanation of different types of regulators. I'm not certain he wrote this, but it sounds like his writing. Posted on Monday, April 25, 2011 - 09:49 pm: Re'd this from Posplayr earlier: Richard, No worries. The Compufire SERIES R/R is about as efficient as is possible to be and in fact is even more efficient than an alternator. I'll summarize a little so you understand the categories. Most of our charging systems are what is know as Permanent Magnet generators, while some others are known as alternators. The main difference is that a PM generator uses magnets to puts out more and more power with RPM ; the only thing that limits it is a R/R or the max power available from the magnetics. The alternator does not have a permanent magnet, but rather controls an electromagnet. So as the RPM goes up the alternator reduces the current going to the electro magnet which there bu limits output. So this brings us to the PM generator and how to limit power from it. First variation is SHUNt v.s. SERIES. The SHUNT just shorts the windings when there is too much power. It is like dimming the lights in your room by shorting out a wall socket. The lights dim and without a fuse you would burn out the house wiring(analogy to the stator windings). The SERIES basically just opens and closes a light switch quickly. That causes the light to dim based on the duty cycle of how long it is on v.s. off. The SERIES is much better on the house wiring (the analogy of the stator winding) OK in Power Supply Design beside also having SERIES and SHUNT there is also something called Switching and Linear. The Linear regulators are also known typically called SERIES but it is really a completely different animal. A typical linear regulator is used for DC to DC drop down regulation. That means for example you take in 12-24V DC and you regulate it down to 5V. The SERIES regulator produces the 5V out by dropping voltage (and gertting hot at teh sametime) either 7V when 12V is coming in or 19V when 24V is coming in. This is very inefficient and only works when there is very little current being supplied. THIS IS NOT HOW THE COMPUFIRE WORKS. 5/12V is about 40% efficent and 5/25 is 20% effcient The other type of regulator is know as a Switcher. This is very similar in principle to the COMPUFIRE from an efficiency stand point but I would not call the COMPUFIRE a true switcher in the conventional sense. For a motorcycle forum you could call it a switcher, but it is not really one. The difference between a true switcher is that the switcher runs at a high frequency 5-10 Khz chopping the incoming DC to limit the output voltage as a function of the switch duty cycle. They usually chop at a rate independent of the input. The Chopping regulator also has a fairly significant energy storage device (capacitor/inductor) at the output to smooth the output voltage (as part of the switching regulator). Almost all of the SHUNT,FET and SERIES R/R's for the PM 3 phase on the motorcycles switch, but they switch synchronously with the 3 phase AC. For a 18 pole stator the frequency is RPM/10. So at 10K RPM you are a 1K hz maximum. This is well below what most true switches operate. If you look up DC to DC power supply, those are the classic Switches power supplies. Other than this speed difference, the Compufire SERIES R/R and the DC to DC switching regulator are similar as both are series designs. It is just a different application. Both operate in the 90-95% efficiency range. (power transfered vs total power consumed) in contrast to the SERIES Linear design. Hope that is clear; you can post the explanation if you like | ||
| Reepicheep |
That's a nice explanation. It is absolutely true in terms of the physics, and what he says about how these systems work makes good sense. Also nice to see somebody not sowing confusion by calling a regulator a MOSFET when they mean to be discussing a switching regulator versus a linear regulator. You can build either a linear regulator or a switching regulator using a MOSFET just fine. It just depends on the rest of the circuit. |
