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Racing Refresh Tech Tuesday: MGU-Kinetic and MGU-Heat

Updated: Jul 1, 2022

(image via Renault F1)

Since the onset of the hybrid era in Formula One, the series has become one of the most technological racing series in the world. Delivering on the promise on being at the forefront of technology and engineering. With this edition of Tech Tuesday, we look at two of the most complex parts of the internal combustion engine of a Formula One car that changed the history of Formula One in 2014 and will be the catalyst of change as cars continue to develop in the future.

To understand fully understand the Motor Generating Unit-H and MGU-K, we have to go all the way back to 2009 which was the year the Kinetic Electric Recovery System (KERS) was introduced with new engine regulations into the series. Much like in the last edition of Tech Tuesday where we talked about the INDYCAR push-to-pass, Formula One also had an issue with cars being less efficient and losing energy. When racecars are traveling around the track they are carrying a level of stored kinetic energy. Under braking loads that kinetic energy is transferred into heat. Which is then wasted as it dissipates into the surrounding air.

But engineers found a different way; what if we used the build up of kinetic energy that a car provides and instead of wasting it trough the process of heat transfer, we can use it to provide electrical energy for the car. Before we move on, the MGU-K does not use heat energy to provide electrical energy. That is a common misconception I would like to get out of the way before we start.

(Image via shutterstock)

All right boys and girls, welcome to science class. I'm your teacher, Collin Best.

To start, we have to reintroduce ourselves to electromagnetism, which is the connection of electric charges through magnetic fields. Magnets are made up of two poles which are called north and south poles. When you have both of them in a space, the magnetic field travels between them from north to south. In electric currents, electrons flow in a path from positive to negative. (Got it?? Moving On!)

When electricity is passed through magnets, lets say on a copper wire. The wire will move around due to the magnetic field. The same thing also happens when the magnets are moved around the electrical wires thus creating an electrical motor. In all my research of the MGU-K, the motor is a three-phase motor. Which has electrical circuits in 120 degree intervals that spin in a magnetic field producing the electromagnetic power.

The MGU-K is set up by using three parts. First, the battery feeds electrical energy to the MGU-K which coverts it to rotational kinetic energy, which adds power to the crankshaft, which sends the energy through the transmission to drive the back wheels. Now to generate power, we need to run the circuit in reverse.

The driver starts the process of decelerating the car which means the wheels are now spinning with rotational kinetic energy which will spin the electrical motor of the MGU-K. In order to generate electrical power, the kinetic energy of the rear wheels is used faster because it takes a lot more energy to generate power with the system than it will be to deploy the stored energy. Thus, the rear wheels start to rotate less as more energy is used by the MGU-K.

At heavy braking circuits on the Formula One calendar, a the MGU-K can harvest up to 2MJ of energy per lap and can deploy 4MJ of energy per lap that can translate to a power boost of 160 hp to the engine.

Well, now that we understand the idea that kinetic energy is not wasted when on track by ways of electrical energy. What about thermal energy? Well to understand that we have to look at a Formula One engine and how it works.

In Formula One, the engine is a 1.6 liter, direct-injection turbo charged V6 engine. (Which is the smallest engine in the three major motorsport series in the world.) The engines now have direct injection into the cylinder which means a more efficient engine with the right air-to-fuel ratio. But lets say we need more air to increase power in critical moments. For example, coming out of the hairpin at Montreal before we get on to the main straight. That is where the Motor Generator Unit-Heat comes in too play.

(illustration by AJ Appeal)

The turbocharger is found on the exhaust manifold of the engine in which the superheated gases pass through the turbocharging unit to spin a small turbine which can move at about 1000 rpm. The air leaving the turbo charger is then forced into a compressor that takes air from an intake on the car and forces it back into the engine to give it the extra oxygen it needs to create more power.

The MGU-H takes some of the air that is passed through the turbocharger into a small wind turbine which can also send energy in the form of electrical energy to the battery store for later use or directly to the MGU-K. Much like the MGU-K which has the power to deploy power to the car for use under acceleration, the MGU-H can do the exact same thing by passing energy back to the turbocharger.

Now you are probably asking yourself why would it do this. Well, the spinning of the turbocharger is directly affected by how much power the engine is putting out. If you decelerate, the engine produces less power and the turbo slows down as well. The time it takes to get the turbocharger back up to full power is called turbo lag. What the MGU-H does is quickly boost the turbo back up to speed so it doesn't have to wait for the engine to get back up to full power which eliminates turbo lag.

So let us put both systems together. Imagine you are Max Verstappen and you are heading into a very slow corner before heading on to a long straight. You're wide open and the engine is at full song. The MGU-K is deploying reserved power to the wheels and you are approaching Turn One at Monza. You slam hard on the brakes and and the wheels are now in somewhat of a free spin while the car is slowing down which is turning the electric motor inside the car and creating more energy to be used when you get on the power leaving turn one. The turbo is also slowing down due to less power coming from the engine as a whole.

You are now through turn two and need to keep Lewis Hamilton behind you, well you can deploy that saved energy from the MGU-K to add up too 160 HP to the car but under initial acceleration the turbo is not up to full speed. The MGU-H forces air back into the turbo which then makes it way back into the engine so right off the slowest corner on the track, the engine can now be at 100% of its full power production which helps you maintain position ahead of Hamilton going into the next set of corners on your way to victory.

I hope you enjoyed another edition of Tech Tuesday. Next week, we will look in-depth of a new feature to the NASCAR Next-Gen car that has caused a lot of controversy in the series to this point and that is the new single lug nut used in the NASCAR Cup Series.

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