Combined Horsepower???????

I don't see what you're getting at. Energy and power are different things. Both motors and engines convert energy into power (work).

 

Power is energy per unit time. The motors are energy tansducers. They have a power limitation in converting electric (volts times amps times time ) to shaft energy (rpm times torque times time). But the sources of energy are what limit the power of the system. The motors can be assumed to be designed to acomadate any power that the sources can supply.

The sources of energy, the engine and battery have power ratings too. The engine can combine so much gas with so much air per unit time. And the battery can combine so many ions with each other per unit time. All the power in must equal all the power out. So, the sources of energy are operating at some power, and the transducers and gears just pass it through to the road with some of the power getting lost as calories of heat/second.

So, its the engine and battery power that sumed together is the system power. The reason for stating the motor powers is to give a relative comparison to the older system. And with a real good knowlede of Mechanical Engineering (not me) one might be able to even work out how much power goes to the wheels from the engine by way of the gear box from the engine, and by the motors from the engine. The power just gets routed around in the HSD transmission in different ways depending on speed and accelleration command. And then it comes out at the wheels. The motors are not burning gas, or combining ions, so they are not generating energy per unit time. They are only passing it through.

 

Yes, energy comes from the battery, and if it is limited, it will limit the work that the motor can perform. Maximum output of a motor is highly dependent on the energy it can get from the battery or power source it is running off of. I'm very aware of that

 

This is a bad assumption. You could just as easily assume that the battery can be designed to supply any power that the motors can consume. One doesn't spring from the other, they come forth together. You would expect a good design to balance all of the factors, which in this case are the power ratings of MG1, MG2, the HV battery, and the ICE. All are related. Installing an overly large MG would be silly: a waste of weight, space, and money.

Tom

 

It looks MG1->AC->DC->AC->MG2.
Please refer to Figure 2.14 on page 13 of following paper.
http://www.autoshop101.com/forms/Hybrid02.pdf

Ken@Japan

 

Hi HTMLSpinnr,

It has to go to DC, or else the function could not be continuously variable. A 6000 RPM 3 phase MG1 could only send power to a 6000 RPM 3 Phase MG2 by AC. And that is just not going to happen. MG1 varies in speed all over depending on the engine speed, MG2 is locked to road speed by a fixed ratio.

An alternator uses a field coil. MG1 and 2 use permanent magnets, allowing them to be brushless. That is a small difference in the big scheme of things.

The alternators I have taken appart were 3 phase electrical machines. That is why they had 6 diodes, not 4.

 

Hi Gbee...,

Well, the assumption is based on the fact that Prius do not break down on the side of the road after a hard climb up a mountain, say. If they do not, then the power capacity of the motors must be able to handle the power from the two sources.

Reading what your saying again, it seems we are saying the same thing. Remember that the power available to MG1 is limited by the gearing. The PSD does a fixed torque split. And indeed MG2 is quite large, the car leans to the left. That is one of the technical disadvantages of the HSD design. One that is worth it in my opinion.

 

Agreed. MG2 in the 2010 is considerably lighter. Toyota went with a geared design so that a smaller, higher speed MG2 could be used.

Tom

 

You are right. The combined power output for MG2 and the ICE lies somewhere between the 2000-2400 RPM at which the geared MG2 develops its maximum power of 80 HP(prior to which the torque is flat-line controlled at 153 ft-lb), and 5200 RPM, where the ICE develops its maximum power of 98 HP.

The combined power output can only measured on a dynamometer, and this is probably how the combined output figure of 134 HP is arrived at. I suppose if you could determine all of the inherent losses within the system theoretically you could calculate the combined power output, but that would be exceedingly complex, and still theoretical.