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Undestanding motor braking

PDM Installation & Configuration

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In the course video on motor braking, the presenter says that braking can be achieved by connecting both ends of the motor to either ground or power. However, he goes on to give an example of a battery-powered drill, which brakes the motor by shorting both ends of the motor together. Are these not two different circuits?

I'm just a little confused, because I've seen the 2nd configuration (shorting the motor) commonly mentioned, but can't find any material that supports the 1st configuration (connecting both ends to ground/power). I want to use a half-bridge arrangement on my PDM to control my wipers and just want to make sure that I can get a braking effect this way.

I'm going through the same thing now. I believe this is the same thing. Whether the two sides of a motor are connected to each other or both connected to ground is the same outcome - they are connected to each other.

I REALLY hope there's a good sized resistor in the circuit you didn't mention, with good heat rejection properties.

As Adrian said, they amount to the same thing.

Why do you feel you need a "braking action" on the wiper motor? I think you may be over-thinking the whole thing.

I believe Eric is referring to the brief braking effect as the motor passes the wiper park position to stop the momentum of the rotor, linkages and wipers from continuing past the park position half way up the windscreen after the driver has turned off the wipers. It is only for a fraction of a second and only when you switch the wipers off. Looks like 18V for a fraction of a second which is only 50% more current that the motor handles anyway.

Voltage and current are different things ;-)

While I'm coming from an 'old school' background, and not fully up to date on possible electonically controlled wipers, they are traditionally wired with the wiper switch powering an otherwise 'dead', or unpowered sector, which energises the motor and moves a sweep contact onto a powered sector which continues to supply power to the motor even when the wiper switch is turned off. the wiper thus continues moving until it comes back to the 'dead' sector which stops the motor receiving power, and the internal gearing, friction, and other physical resistances stop it moving.

It would seem the open circuit as the sweep contact is no longer powered, which results in a slight spike in the voltage potential across the open circuit is confusing quite a few people.

There is NO "reverse voltage" applied, it's the result of the motor still being driven by the moving masses before physically stopping.

You can check out wiring schematics here - https://www.google.com/search?source=univ&tbm=isch&q=windscreen+wiper+motor+schematic&client=firefox-b-d&fir=tMUzNK--tgifRM%252CvR9Rnssk91_R-M%252C_%253BT2NfVxYY66nshM%252CA6VK9me7ILAPWM%252C_%253B3o3pMrxS4qZoSM%252CS_-fBvv3YGFObM%252C_%253Bj7y1qRfYqK2EYM%252CLY9NWCNZAfNDfM%252C_%253BoREk7f5FamkQ0M%252CZ7pNzZZvvUYAXM%252C_%253B9I7L2vNfwA8NBM%252Ct9qtxy75u8qOLM%252C_%253BuXJEmUILaQHX4M%252CXo2sfYBB6zKYgM%252C_%253BjFfl81EqrWWU6M%252CVCaafx1CCoLYmM%252C_%253BYnW_BGYEIL-ayM%252CX8GlENkjcWtTmM%252C_%253BvVliyfSXUjN4NM%252C0X0wFBrgWdSjXM%252C_&usg=AI4_-kROIF3WLVEB45Zh6XQuG4eaNzxgqg&sa=X&ved=2ahUKEwjXvL6Rzpn2AhX_RmwGHYTHBPgQ7Al6BAgLEE8&biw=2144&bih=1138&dpr=0.9

The motor braking effect is achieved by momentarily connecting both sides of the low speed winding to each other. It's not through applying a reverse voltage.

You are of course correct that voltage is different to current. What I meant to say is 18V through a motor winding doesn't generate enough current or heat (for a brief period) to require any additional resistance other than than of the motor winding itself.

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