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Motorcycle Regulator-Rectifier With Low Power Dissipation 2015-10-31

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crutschow

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crutschow submitted a new article:

Motorcycle Regulator-Rectifier With Low Power Dissipation - Low power regulator design for permanent magnet alternators improves reliability

This circuit is a design I worked on after three regulator failures I've had on my motorcycle over a period of a few years, due likely to excess heat dissipation (the regulator has a small heat sink and is mounted close to engine heat). The fourth regulator I recently purchased is a MOSFET design which is claimed to dissipate less heat and thus be more reliable. This led me to do the paper design (below) on such a regulator to try and reduce heat dissipation to a practical minimum (which...
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killivolt

Well-Known Member
Oddly, I would have to say not many Motorcycles change the design of circuits and some are very similar. So, I would have to say that this is probably good in most cases for some motorcycles with similar design.
However, this is true with older motorcycles (Not sure about newer, because I ride an 82 Yamaha) due in part the older designs are 6v or 12v and could need different regulation. But, I'm not able to define which or if it will provide for both or not. Many DIY folks have done some interesting things with there bikes and some are able to convert them from 6v to 12v I'm told?

Many Motorcycles have similar designs and have some interchangeable parts. The electrical systems are not unique and have for the most part similar design features.

So, if this is true maybe just some tweaking is needed to do the work needed to make both 6v and 12v to regulate the voltage requirements of the bike.

kv

Edit,

crutschow, didn't know you had a bike.
 

renato2

New Member
Hi,

thanks for the interesting circuit and simulation figure.
Usually these regulators were made using SCRs for shunting the power, thus showing a constant 2V forward voltage during conduction. MOSFETs are more safe against thermal failure due to their much lower voltage drop and resistive forward characteristics.
Power dissipation can be reduced further, by opening the MOSFET in reverse direction i. e. providing a parallel resistor to the reverse diode. Of course, this needs a very elaborate, fast gate driver circuit.

Crutschow, have you used this regulator successfully on your bike?

bye renato
 

Tony Stewart

Well-Known Member
Most Helpful Member
:cool::cool:looks good on simulation. My only concern is the Vin- exceeds the required Vcc-2V limits for reliable operation on U2,3,4 on power signals 1,2,3 which also exceed Vs by a Schottky diode drop.

"specs below for LM339"

9.2.2.1 Input Voltage Range

When choosing the input voltage range, the input common-mode voltage range (VICR) must be taken in to account. If temperature operation is above or below 25°C the VICR can range from 0 V to VCC– 2 V. This limits the input voltage range to as high as VCC– 2 V and as low as 0 V. Operation outside of this range can yield incorrect comparisons."

can doesn't mean will..so
i gather it worked ok. http://www.electro-tech-online.com/...tor-rectifier-with-low-power-dissipation.756/
 

otoman

New Member
This is a good simulation result. Actually, advanced products were in production with excellent performance in Taiwan (a small island near China). With full MOSFET structure, lower operating temperature and higher current output with fast voltage recovery capability is available. http://www.ototek.com.tw
 

Ian Nic

New Member
Nice article. I'd figured out from examining a commercial MOSFET regulator (from a 2007 Yamaha R1) that something like this was going on inside (~160mV drop from phase to positive output, ~600mV from phase to negative output). Just one question - why the pull-up resistors (R6, 7, 8)? Surely if the op-amps can sink enough current to pull the gates down plus another 7mA or so through the resistor, then they can source enough to switch the mosfets on pretty smartly?
 

otoman

New Member
The LM339 is open-drain output, so it needs pull-up resistor. As I know, MOSFET regulators on market are mostly high arm schottky diode, the phase to positive should be ~600mV.
 

Ian Nic

New Member
The LM339 is open-drain output, so it needs pull-up resistor. As I know, MOSFET regulators on market are mostly high arm schottky diode, the phase to positive should be ~600mV.
Ah, my mistake, <slaps head> it's a comparator not an op-amp. Thanks for clearing that up. Why do you say ~600mV phase to positive though? Schottkys have a lower forward conduction voltage that that.
 

otoman

New Member
This is a high current Schottky diode, the forward voltage drop at this current rating should be more than 500mV. You can check it @ mouser on-line.
 

otoman

New Member
For cost concern, this circuit was implemented on Al-based PCB with thermal resistance of >5 deg-C/W. It means the ambient to diodes temperature increase up to 100 deg-C. This will definitely burn the diodes at higher outdoor temperature. Tc=130'C, the diodes temperature will rise to 230'C that over-stress their Tj limit of 175'C.
 

Danwvw

Active Member
Instead of the 3 Schottky Diodes why not use 3 more MOSFET's bridge them just like the diode bridge rectifiers, Wouldn't that lower the power loss thus the heat?
 
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