F1 engines or Power Units as they called these days (PU) are a combination of an internal combustion engine that's turbocharged (similar to a lot of road cars) with a battery system.
The Kinetic energy that is generated by the car's brakes spins up a Motor Generator Unit (MGU-K) that charges the battery. The driver then has the option to deploy this energy when needed to help with overtaking or just overall improvements in laptime.
The Motor Generator Unit - Heat (MGU-H) is the second motor generator unit that forms part of the PU. Exhaust gasses that leave the engine after combustion is typically exiting at high speed. Since this is essentially the same as wind, the MGU-H acts almost like a wind turbine and spins up to generate electricity. This is then typically used to help reduce turbo lag. Turbo lag is the time taken from when the driver requests the engine to produce more power till when the turbo actually starts producing the required pressure. The MGU-H therefore does not convert heat into electrical energy despite its confusing name. It just uses the high speed gasses exiting the exhaust to spin up an electric motor that can be used to help get rid of turbo lag
That's three major components that we've discussed:
- The internal combustion engine that's turbo charged
- The MGU-K
- The MGU-H
The final major component is the Battery Store. This is essentially the same as the battery system as found on a road going electric vehicle and is used to store the energy generated by the MGU-K. The driver needs to ensure that the State of Charge (SOC) is always at a high enough level to allow for the car to not only maintain fast laptimes but to leave some room for an extra boost when an overtake may be required.
This balance of driving fast enough to be competitive but also to ensure that the SOC isn't depleted is something that a driver must maintain throughout a race distance. They generally run the system in an auto mode where the SOC will deploy automatically based on the location of the car on the track but higher or lower performance modes may be selected depending on the race situation.
Overall, a modern Formula 1 power unit is a very complex machine that combines the power of an internal combustion engine that's turbo charged with an electrical system that recovers energy from exhaust gasses and kinetic energy from braking. This energy is then deployed seamlessly when the driver applies the throttle with the internal combustion engine and electrical power blended into a smooth delivery of around 1000Hp (745KW).
As usual, I've tried to simplify the explanation as best as possible but certain things will always remain technical. This article may be brief but i'm sure it will help you have a better understanding of what a modern Formula 1 engine consists of.