Electronics > Projects, Designs, and Technical Stuff
Do modern car/boat alternators use PFC circuits?
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Zbig:

--- Quote from: NiHaoMike on July 23, 2019, 04:45:42 am ---An increasing number of cars are using switching power supplies for the 12V.
http://techno-fandom.org/~hobbit/cars/ginv/i1mech.html

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Not saying they aren't (don't know) but the page you've linked talks about Toyota Prius (hybrid) specifically. Toyota Hybrid Synergy Drive uses completely different electrical system topology. You don't have a conventional alternator there: the 12V system and the 12V lead-acid battery (yes, there still is one) are powered from high voltage (c.a. 400V IIRC) DC coming from the High Voltage Battery or either of the two Motor-Generators via the Inverter-Converter.
james_s:

--- Quote from: NiHaoMike on July 25, 2019, 01:06:39 am ---
--- Quote from: MagicSmoker on July 24, 2019, 11:44:14 am ---Really? That's exceptionally stupid, even for an automotive OEM, which can usually be counted on to do things too cheaply, rather than the other way around. PM rotors are much more expensive and can't withstand even moderately high temperatures (some types of rare earth magnets start to suffer demagnetization at less than 100C), to say nothing of then needing an SMPS to provide voltage regulation and current-limiting. It would make far more sense to simply replace the crappy claw-pole rotor with a salient pole wound-field rotor as found on larger synchronous machines since it could use the same field current regulator design and 3-ph. bridge rectifier.

--- End quote ---
The added cost is offset by removing the need for a separate starter motor. Then add auto start/stop, to boost MPG and help otherwise conventional cars stay competitive with hybrids and EVs.

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Those silly auto stop-start systems exist to exploit a loophole in the way idle emissions are calculated. They have a negligible impact on real world fuel economy and anecdotally they seem to have a very real impact on battery life. They certainly are annoying to drive a vehicle that has one too, especially the cheap ones that have an ordinary noisy starter that engages.
soldar:
PFC circuits exist in devices connected to the mains because the energy (current) has to be transported hundreds or thousands of Km from generation to consumption and PFC provides a reduction in power wasted in transmission.

In a car it makes no sense.
Gyro:

--- Quote from: Zbig on July 25, 2019, 02:17:40 pm ---
--- Quote from: NiHaoMike on July 23, 2019, 04:45:42 am ---An increasing number of cars are using switching power supplies for the 12V.
http://techno-fandom.org/~hobbit/cars/ginv/i1mech.html

--- End quote ---

Not saying they aren't (don't know) but the page you've linked talks about Toyota Prius (hybrid) specifically. Toyota Hybrid Synergy Drive uses completely different electrical system topology. You don't have a conventional alternator there: the 12V system and the 12V lead-acid battery (yes, there still is one) are powered from high voltage (c.a. 400V IIRC) DC coming from the High Voltage Battery or either of the two Motor-Generators via the Inverter-Converter.

--- End quote ---

We picked up our nice Kia Niro Hybrid earlier this week. Kia phased out (no pun intended) the 12V lead-acid battery in 2018 - It was there when the car was first released in 2016. It uses both the 32kW drive motor and the Engine belt coupled Hybrid Starter Generator (8kW) for regeneration. Both are hooked up to the high voltage battery (240-270V).

Apparently there is now a separate 12V auxiliary section in the main (LIPo) high voltage battery (there's a regenerate button to recharge it from the main battery if it gets low), but both of the motors, and the Aircon compressor too are 3-phase permanent magnet type, driven by the inverter module from high voltage battery.

It took me a while searching around the boot for the Aux battery compartment before I found a reference on the web to it being phased out. The earlier service manual reference that I have still had it included.

I can't get my head around these new 48V 'mild' hybrids! A tax / congestion area get-around?

I do like the belt drive starter generator though, pinion drive 12V starters are a really weak link for stop-start operation.
ejeffrey:

--- Quote from: Gyro on July 25, 2019, 04:45:29 pm ---I can't get my head around these new 48V 'mild' hybrids! A tax / congestion area get-around?

I do like the belt drive starter generator though, pinion drive 12V starters are a really weak link for stop-start operation.

--- End quote ---

48 V mild hybrid is basically start-stop++.  You get a more powerful combined starter/generator that is attached directly to the drive shaft and replaces the starter and alternator.  It can restart the engine faster than a crappy 12V starter motor and also start to move the car forward while starting for impatient people who need to move *now* when the light turns green.  The 48 V system is also enough to power an electric AC compressor which means the compressor doesn't have to deal with the huge RPM range of the engine and also doesn't shut off when the engine stops at a traffic light.  The electric motor costs more than a pulley, but also gives the manufacturer more freedom in placement, and may allow complete elimination of the serpentine belt. You get a small amount of regenerative braking which still helps for stop/go city driving and if you can put some of the other higher power accessories on 48V you save a bit on copper costs.  Since 48V is still considered "safe" you don't have to implement the same emergency cutoff and auxillary battery systems that traditional hybrids have.

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