wattage of DC-DC converter ?

[ken1784]

Originally Posted by HeadsUp

if battery max current drain is 100 amps then the rating could be 150 A x 202 V = 30 kilowatts or more

i am still guessing

As patsparks wrote, there is no specification plate. Toyota never published the official specification.
No one can exceed 25kW wattage.
A safety margin is another story.

Ken@Japan

[Mike Dimmick]

Originally Posted by hobbit

First of all, the boost converter is in 2004+, not 2003. I don't
know how much power it's rated for, but consider this: the nominal
max battery current in and out is 100 amps. [Rarely we see
peaks slightly above that but not for long, and the pack is
fused at 120A.] At full regen when the pack is around 250V
instantaneous that's 25 kilowatts on the "200V" side; obviously
less current but higher voltage at the motor for equivalent
power. Now, MG2 [the big one] is rated for 50 kW peak, I believe,
which presumably would have to be fed by the doubled-up side of the
inverter rack, but there's no way the battery is going to deliver
or accept that on its own. What's probably more important than
"power handling" in terms of the buck/boost converter is just how
much current it can handle without getting too warm or blasting the
bejeezus out of some transistor dies. The power dissipated *across*
the circuit is probably very low by comparison, and we count on the
mass of the inverter frame and that always-running coolant loop to
whisk that excess away from the important bits in short order.
.
I haven't answered the question, but hopefully have gotten your
thinking into the right order of magnitude. At a very outside guess
I'd say somewhere between 25 and 50 kW to have a nice safe envelope.
Compare the die and bond-wire sizes of the inverter-rack vs. the
boost-switch transistors, consider the real-life feed current at
up to a 300V delta, and you can probably get close.
.
_H*

The waveforms of three-phase alternating current (AC) going to the main drive motor MG2, main generator MG1 when driven as a motor (heretical mode), and to the air-conditioning compressor (also a three-phase alternating current motor), have to exactly follow the current position of the rotor so that the correct magnetic field is being produced in the correct coils at the right time, in order to actually drive the motor. Basically, from the perspective of any magnet on the rotor, the coil directly overhead must be more-or-less neutral, the one ahead must be attracting, and the one behind repulsing, in order that the magnet is pulled and pushed forwards.

Let's say we're accelerating hard at 30mph (48km/h). 72% of the torque produced by the engine goes straight to the ring gear whereupon it goes to the reduction gear (via the chain in Gen 1 and 2), differential and front wheels. 28% of the torque goes to drive MG1 to produce power which goes to MG2. To get more acceleration we also add the power from the battery to MG2.

However, MG1 and MG2 are rotating at different rates. According to a Prius simulator, MG2 (which is directly related to the road speed) is turning at 1,800rpm. The highest speed we can set the engine to and keep MG1 within the ±6,500rpm bracket is 3,000rpm. If the engine is rotating at this speed MG1 must turn at about 6,100rpm. Clearly we can't just take the waveform directly from MG1 and apply it to MG2, the wrong coils would be driven.

So that all the voltages and timings work out, the power generated by MG1 - which due to the setup of the coils and magnets is also three-phase, at high voltages - has to be converted back to around 200V DC. That allows power to be directly taken off from or returned to the battery. The MG2 inverter must be able to handle the entirety of the power capability of MG2 itself - a full 50kW for Gen 2, 60kW for Gen 3.

I believe that the inverter is actually a pulse-width-modulated variable-frequency drive as described at Variable-frequency drive - Wikipedia, the free encyclopedia.

From what I recall of Gen 3 marketing materials, the battery supplies up to 25kW on Gen 2, up to 27kW on Gen 3. The remaining power for large outputs from MG2 comes from MG1.

[hobbit]

No, MG1 and MG2 share the same 500V power rail, both post-boost.
.
_H*