Quote:
Originally Posted by raubvogel
While I understand that the engine and MG2 have different power bands -- I expect electric motors to reach their peak HP at lower RPMs than an engine -- the part of having MG2 spinning backwards confuse me: is it doing that to collect engine power that is not necessary to keep the desired road speed (like the MG1) or actually "fighting against" the engine? Also, how would that work if I have pedal to the floor and want to drive at its top speed?
Also, shouldn't a reduction gear on MG2 be able to shift where its peak power is compared to the engine?
|
In some cases it's actually necessary for MG1 or 2 to fight against the engine, to sap some of its energy and send it to the battery or the other motor.
Here are two cases:
1) Imagine flooring the accelerator pedal from a dead stop. The engine kicks to life. If MG2 were stationary, it would be like dropping the clutch on a manual, you'd stall the engine. MG2 actually needs to spin backwards to provide a gear reduction between the gasoline engine and the wheels. The higher the gas engine needs to rev to generate power, relative to wheel speed, the faster MG2 needs to spin backwards.
2) Traveling at normal highway speeds, the engine is spinning at a fixed RPM. In order to get the proper gearing to match that RPM to road speed, MG2 also needs to be spinning forward. However, this energy needs to come from somewhere, and the battery would only last a short time. So, MG1 is constantly working against the gasoline engine to generate power to send to MG2.