I drive a hybrid car. I understand that there are electric motors that help the gasoline engine to produce power to the wheels. I also know that if a motor is spun without current applied, it will act as a generator and produce current. What I don’t understand is how my car is able to change how much is regenerated when I press the brake pedal (to give a smoother slowing force). For example, when I coast, my car regenerates a small amount of energy. Then, if I press lightly, it will slowly increase how much it regenerates and also increases how much it slows down. How can it change the amount it regenerates?
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Power transistors that can very rapidly connect and disconnect the battery charger (e.g. 1000 times a second).
If the brake pedal is requesting 10% slowing, it connects the battery charger for 0.0001 seconds, then disconnects it for 0.0009 seconds.
If the brake pedal is requesting 40% slowing, it connects the battery charger for 0.0004 seconds, then disconnects it for 0.0006 seconds.
While the battery charger’s connected, it creates a large mechanical load that rapidly slows the spinning. When the charger’s disconnected, the mechanical load is tiny by comparison.
Because it switches so fast, there’s enough mechanical and electrical inertia that it ends up averaging out into smooth deceleration. (Electrical inertia is provided by inductors and capacitors.) In other words, even though the computer’s effectively jamming the brake to the floor and then letting it completely up 1000 times a second, there’s electrical and mechanical stuff in the motor and power electronics that smooths it out, so you’re not jolted, jostled and vibrated around.
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