Naked Science Forum

Non Life Sciences => Technology => Topic started by: scientizscht on 15/06/2018 15:15:49

Title: When is the electric motor used in hybrid vehicles?
Post by: scientizscht on 15/06/2018 15:15:49
Hello!

In current hybrid vehicles, when does the electric motor work? Does it work all the time to assist the internal combustion engine or only under specific conditions? Which are they?

Thanks
Title: Re: When is the electric motor used in hybrid vehicles?
Post by: wolfekeeper on 15/06/2018 18:56:52
There's many different schemes:

https://en.wikipedia.org/wiki/Hybrid_vehicle#Hybrid_vehicle_power_train_configurations

Title: Re: When is the electric motor used in hybrid vehicles?
Post by: scientizscht on 15/06/2018 19:36:11
There's many different schemes:

https://en.wikipedia.org/wiki/Hybrid_vehicle#Hybrid_vehicle_power_train_configurations

I am talking about regular hybrid vehicles, nobody makes series hybrids!
Title: Re: When is the electric motor used in hybrid vehicles?
Post by: evan_au on 16/06/2018 02:08:27
Quote from: scientizscht
In current hybrid vehicles, when does the electric motor work?
I have regularly travelled as a passenger in a colleague's hybrid car.

After being parked for 4 hours, there is still enough charge in the batteries to start off entirely on electric power (silent death for any pedestrians in the carpark!).

But the motor cuts in soon after - perhaps when we hit the ramp up to ground level? (I haven't been taking careful notes...).

In general, the electric motor operates on its own when the battery is full, and/or there is little power demand (suburban driving, downhill or on a level road).

The petrol motor kicks in when the battery is low and/or there is sustained high power demand (acceleration uphill, or high-speed highway driving).

There are many factors, which all go into a computer algorithm to work out the optimum balance between power generation and consumption - the algorithm is probably so complex that even people who work on it can't accurately predict the outcome under all possible conditions.
Title: Re: When is the electric motor used in hybrid vehicles?
Post by: wolfekeeper on 16/06/2018 15:45:55
There's different strategies used in different cars. The Prius has a only small battery, so the engine runs quite a bit, the battery mostly captures regenerative braking energy. The Chevrolet Volt has a much bigger battery, so runs mainly just on that, and when the battery gets depleted it runs as a series-hybrid using the engine to turn a generator to top up the battery. However, there's also a mechanical linkage, between the engine and the wheels, so it can directly drive the car, together with the electric motor, when you need a burst of extra acceleration.