Hybrid Battery
6-cell NiMH module, producing 7.2 volts. 28 of these are put together in series to form the full 201V battery, which fits under the deck between the car's rear wheel strut towers.

The cutaway illustrates the secondary inter-cell connection that allows using higher 100A currents instead of 50A. This improvement was made in model year 2004.

Boost Converter
Raises the 200 volts from the battery up to as much as 500 volts for the motors. (Level varies as needed.) Uses a large inductor (coil) and a power transistor module to drive it.

Smooths out the boosted voltage, and absorbs surges or spikes that occur during transistor switching. Very temporary energy storage, in effect.

Power Module
Contains large high-current power transistors, mounted on a large liquid-cooled heat-sink.
Sends the high voltage supply to each motor's 3 leads, to power the windings high or low at the right times and create magnetic torque.
Also handles regenerative braking power FROM the motor and regulates battery charging current to slow the car down while recapturing as much of that energy as possible.

Couples together the gasoline engine, the small motor-generator, and the large motor-generator (not present!) through a single planetary gearset, referred to as the "power split device". Sends torque to the final drive and wheels to push the car, and uses the small motor-generator inside to balance out the system under all running conditions.
Electrical power is shunted between the motors, and/or to and from the battery, to keep all three components stable.

The position sensor used in both motors. A non-contact device using differential coils and an oval rotor to derive very accurate sine and cosine signals for motor rotation.

The hybrid ECU uses these to know exactly where each motor is, how fast it is turning, and then calculates how to drive its windings for the desired effect.

Since we don't have a engine here to run, that's your job! By turning the crank, you can "burn the fuel" and supply mechanical power into the system which either turns the output gearing, spins MG1 to generate electricity, or both. The more that MG1 is held back by an electrical load, the more engine RPM goes to the differential and wheels. With the system in PARK, it's just a 3-phase generator. The 1.5 liter Atkinson-cycle engine can produce 57 kW. How many kilowatts can YOU produce?

** Please turn CLOCKWISE, as the planetary assembly has **
** a tendency to jump out of the ring if turned the other **
** way -- simply due to the helical cut of the gears. **

Hybrid ECU
The master brains of the whole operation. Receives the driver's accelerator-pedal request, decides when to start or stop the gasoline engine, and controls the two electric motors via the inverter to do exactly what's needed. Receives information from many other control computers as well as its own set of sensors. Handles regenerative braking by using MG2 to generate power into the battery.

(From a Katrina flood car -- thus the corrosion)

Engine ECM
A dedicated controller for the gas engine. Similar to the computers that manage engines in any other modern car, but has a few features that help it integrate with the hybrid system. Controls injection, spark, valve timing, cam and crank sensors, evaporative emissions, and coolant pumps.

And in the Prius, this module also controls the throttle -- allowing the engine to be run at optimal efficiency. By taking that function away from the driver, we can realize huge fuel economy benefits.

The "skid control ECU" handles almost all aspects of braking, including ABS and traction control, and communicates with the hybrid ECU to request regenerative stopping torque. The ECU controls hydraulic pressure to each separate wheel when needed -- although every effort is made to NOT use the physical brakes until absolutely necessary, since brakes only waste energy as heat.

(near a life-size printed photograph we had of it)
Occupying the half of the transaxle we don't have here today, motor-generator 2 is the big one -- 50 kilowatts of raw, 295-foot-pound grunt torque. It connects into the open end of the planetary ring and thus also to the final driveline, and allows for driving the car in pure electric mode with the engine shut down. MG2's primary jobs are vehicle propulsion and acting as a generator for regen braking.

Coolant bottle
At shutdown, a small electric pump moves about 3 liters of hot coolant from the engine into this insulated vacuum flask (like a coffee thermos) where it remains warm for as long as 2-3 days. At the next startup, the coolant is pumped back into the block around the cylinder and head (i.e. the combustion area) to supply a preheat, lowering cold-start emissions and raising overall fuel economy.

(on the large monitor displaying my "prius porn" from the laptop)
Scenes from many places and aspects of hybrid ownership, from road-trip "glamor shots" to deep technical detail. Takes about half an hour to fully cycle.

MPG Enhancer
(next to my tire pump, on the small table with our flyers)
Tire pressure less than sidewall rating? Get to work! It is actually quite easy to top up automobile tires with a hand or foot pump.

Warm Air Intake Kit
Brings preheated air from around the exhaust header over the engine and into the air box, in an attempt to conserve engine heat and lower intake air density. Still unclear if it really helps winter MPG over the long haul in a modern fuel-injected engine, but seems to shorten warmup time. Nonetheless, hacks like this and radiator-covering and engine block heaters are favorite topics on the forums as winter approaches. Some hypermilers have even stuffed household fiberglass insulation all around their engines.

Since a gasoline engine is a "heat engine" and depends on being at its normal operating temperature for best efficiency, anything to effectively conserve that heat helps some.

Block Heater
A small 400W electric heater that plugs into 120VAC, and sits in the engine block near the cylinder combustion area to warm the surrounding area. Definitely improves MPG over the first couple of miles where fuel consmption is otherwise much worse, and thus overall economy. A preheat of about three hours (10 cents of electricity) is all it takes to make a real difference on a cold day.

The simplest "plug-in conversion" you can do!