Does pressing the pedal mechanically/hydraulically move spinning magnets on the hub nearer other magnets to create electricity?
In: Engineering
The technology is more commonly known as regenerative braking. Even the term KERS is outdated. But you are sort of correct, although the magnets do not physically move. Rather these are electromagnets that is turned on and off by a switch controlled by a computer. The computer can therefore control exactly where the magnetic field should be at any time. When coasting freely the magnetic field of the electromagnets match the magnetic field of the rotating permanent magnets exactly. So no force is applied through the electric motor. But when you apply the regenerative braking the computer moves the magnetic field of the electromagnets slightly behind the magnetic field of the permanent magnets. So the electromagnets are pulling the rotating magnets back slowing down the rotation. This also produces a current in the electromagnets which is fed back to the batteries charging them.
The wheel motors are already generators. In regen braking mode the motor terminals are disconnected from the motor driver circuit and connected to a rectifier/battery charger instead.
Edit: I see it is a formula 1 specific system. The answer still stands, it’s just that the electric motor is by default disconnected completely rather than being in propulsion mode like the usual electric car.
Most Motors are Generators, too. It’s just the same device: If you put rotation onto it, electricity comes out at the other end. If you put elecricity into that end, it starts spinnig. You could even couple two of those devices at the drive shaft and put electicity into one. Then they both starts turning and on the other end electricity comes out. Or vice versa: you connect them by cables and spin one and the other starts spinning, too. There are losses, but it will work in general.
Whenever you are not povering your bicycle, car or whatever the motors starts producing a voltage. If you put any resistance to it the now-generator literally turns motion into electricity. In result you’ll get slower and your battery charges up. Old trams were breaking this way over big resistors on their roofs to prevent wear on the disk breaks. Modern trams/trains putting the energy back into the power line for other trams.
Somewhat, yes. Electrical currents generate magnetic fields. This is a fundamental thing in Physics, not much I can explain about this.
Now, things don’t like to change state. If you apply a force on something, it will push you back. Same thing if you apply a moving magnetic field to something. It will, if possible, create an internal current that creates a magnetic field that resists that movement. We call this current an induced current, since it was generated by the external magnetic flux. Basically, moving magnetic fields make things magnetic too, but opposite, by inducing a current within said thing.
Regenerative braking basically uses electromagnets (magnets which can be turned on and off at will) to make the spinning wheel magnetic. This causes the part of the brake that is on the car to naturally create a resisting field. That resisting magnetic field slows down the wheel and the induced current can be captured into the battery.
You have electric motors connected to the wheels, they don’t do anything, just sit there.
When you apply pressure to the breaking pedal, you reverse the motors aka you turn them into generators which then use the wheel rotation to create electricity (basically as any other way we create electricity)
This created electricity is then send to a battery to be stored.
When you release the breaking pedal, you reverse the system again from generators to motors, then if you want, you can deliver power stored in the battery to the motors which then deliver it to the wheels which makes you go faster.
KERS Is pretty outdated in F1 and it’s not used anymore. Though they use something similar called MGU-K (and MGU-H which operates in a different principle and F1 is anyway ditching it, if not already have, haven’t followed up with F1 in years.)
It’s a common (and understandable) misconception that the brakes themselves are doing the harvesting.
What happens is that the electric motor that drives the car basically goes into reverse. Instead of the battery sending electricity into the motor and making it turn, the battery ”sucks out” electricity from the motor which steals some of its energy, slowing it down.
It’s not using ‘braking energy’ the way it sounds.
What’s actually happening is that the generator used to generate the power provides a resistance to the drivetrain, thus slowing the car down. It has nothing to do with the disc brakes.
KERS is a pretty general term, but generally when we talk about regenerative braking in vehicles, it’s in hybrid and electric vehicles.
Electric motors are pretty cool devices. They use both permanent and electromagnets to resist the flow of electricity and convert it to kinetic energy. What’s even cooler is with a bit of extra controls and design consideration, they can run backwards as generators instead.
Normally, you put electricity into a motor, the motor *resists* the flow of electricity, and out comes kinetic energy. In a generator, you put kinetic energy in, the generator *resists* the kinetic energy, and out comes electricity.
KERS/Regenerative braking systems keep the wheels connected through the drivetrain to the motor, and then use motor controls to make the motor behave as a generator. Electricity generated in the process is fed through some form of voltage controller and used to charge the battery.
The reason we don’t tend to put regenerative braking on ICE vehicles is because they don’t already have an electric motor that can be used as a generator, the electrical controls, or a suitably sized battery to store the energy generated.
The way regenerative braking tends to work is not that complicated, and there are essentially two common setups, and some cars allow you to toggle between them.
1. Combination braking. When you hit the pedal, the friction brakes engage the same way they do on any other vehicle. At the same time though, the brake pedal switch (the same switch that already turns on the brake lights), also sends a signal to the regen braking system that tells it to engage at the same time. I.e. both brakes work together.
2. Auto-regen braking, or “one pedal driving”. This tells the regen brakes to engage any time your foot is off the accelerator pedal. As soon as you take your foot off the accel pedal, the vehicle starts braking. If you want to “coast”, you can keep your foot lightly on the accel pedal. The benefit to this is that as long as you’re planning far enough ahead, you can use regen braking for 99% of your braking needs, and will rarely have to use the friction brakes.
The brake pedal still engages the friction brakes as normal for when you need them for a faster stop.
Simplifying quite a bit, but every electric motor is a generator. If you send electricity to it, it will spin. If you spin it manually, it will generate electricity. This is similar to how microphone and speakers are effectively the same devices, and LED’s and photovoltaic cells are basically the same devices. Obviously if something is made as a motor, its design is optimized for the motor duties, and it would make a pretty crappy generator.
However, if you build a motor specifically to be OK at doing both (turning electricity into movement, and converting movement back into electricity), then you can use it for regenrative braking. The same electric motor that pwoeres the car, when you want to use it for braking, you just “run it in reverse” and use the motion of the wheels to produce electricity.
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