Capacitors

Exactly what and why do you need to know about Prius capacitors? No "flux capacitor" or really any power related capacitors exist in the Prius other than some small filtering caps as shown in the pics above.

 

Modern high frequency switching power supplies and inverters don't rely on big capacitor banks like older linear power supplies did. This makes them smaller and importantly, more efficient. The following link describes the concepts. Think of the regen charging in a hybrid as an AC generator supplying a switching power supply to generate DC to charge the battery.
Ken Shirriff's blog: Apple didn't revolutionize power supplies; new transistors did

 

they're probably worried you're working for a law firm on a class action suit.

 

File:2010 Prius Regeneration.jpg - Wikimedia Commons

and - pages 24-25 (with xray vision of capacitors), & page 77 - your tax $ at work
http://ecee.colorado.edu/~ecen5017/notes/OakRidge_2010Prius.pdf

 

The linked 572 page manual is probably Toyota's most definitive public pdf. It includes waveforms from which frequency could be obtained. However in places you will see "TOYOTA's intellectual property" meaning they don't want everyone to know all the details as much of it is patented.

 

Start here: Evolution of the 2010 Toyota Prius Hybrid Synergy Drive System | PriusChat

Bob Wilson

 

The Toyota ultracap experiments are in their TS040 race car: Toyota TS040 Hybrid - Wikipedia, the free encyclopedia

Inside the car, the air-bag system uses caps to fire the air-bags in the event the 12V battery power is lost.

GOOD LUCK!
Bob Wilson

 

More information than you ever wanted to know is here: Evolution of the 2010 Toyota Prius Hybrid Synergy Drive System | PriusChat
Courtesy of the US govt.

 

A boost converter in this case is a DC/DC converter that takes 201 vdc and converts it to a higher dc voltage before it is passed to the inverter to be modulated into 3 phase vac for the motors. Usually the complete power circuit is called a variable frequency drive (VFD). So you could look up theory of operation for a VFD for better information. In any case, a boost converter increases the dc voltage while decreasing the dc current with a little loss to heat. So while it is probably true it is temporarily storing an increasing voltage level and is essential for the circuit, it might be stretching it to say it is a source for the load. It has to charge and discharge quickly in a high frequency power supply, so whatever is the best terminology might be in the engineering theory books. It's been more than 40 years since I had an EE class so you probably have access to the best references.

 

3300 uF is quite a low capacity. I just purchased 5x of the BCAP3400 supercaps from Mouser to replace the 12v lead-acid battery in my truck. It has a series capacitance of 680 farads.

A more interesting study might be Mazda's SkyActiv systems. It has a sort of regen that is activated when the driver steps on the brake, and it charges super caps which are then used in the 12v electrical system. It's a way to recapture some of the energy that would normally be wasted when decelerating. Supercaps are much more efficient at recapturing that energy since there is practically no limit to how quickly they are charged, and there are very low losses since they aren't undergoing a chemical change. Batteries have a limited charge rate and loose a large amount of energy in the chemical reaction process.

 

There is a box in the rear by the 12V battery like you were looking at. It's there to keep the important systems working until you can bring the car to a stop in case the 12V battery fails catastrophically (internal short, open, fuse failure, etc). It also provides some "regulation" to the 12V system, absorbing spikes etc. It is not there to "power the car" in the strictest sense of the word. The Prius doesn't use capacitors to power the car, it just uses the "traction battery". The Toyota Hybrid race car does use "super capacitors" to help power the car.

Remember there are two power systems in the Prius, one 12V system for the electronics and other smaller systems (seat heat for example), and the high voltage system, with a 201V battery and inverter that puts 560V or so to the 3 phase motor/generators and the A/C system pump. Both must be fully operational for the Prius to work.