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Feeding dc to 2 phase of 3 phase BLDC? short circuit?

ferbo

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I know this question might sound stupid... I want my 3 phase BLDC to hold its position even if I try to turn it with my hand. If I just fed the two phases with my dc voltage... i mean battery+ to one phase and battery- to the other... would it cause a short circuit due to the coils of the motor?
Thank you all.
 

FvM

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You can hold the position by applying DC, but current must be limited to the motor rating, or a lower value sufficient to provide the intended hold torque.
 

BradtheRad

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Gearing (step-down rpm) makes the motor resist being turned if you manually apply force to the load. However it can be overcome by continuing to apply force, since no current is drawn and the motor produces no physical counter-acting force.

A servo does physically resist if you try to move its arm by hand. It draws current but only during the time you try to move it.
 

c_mitra

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I know this question might sound stupid... I want my 3 phase BLDC to hold its position even if I try to turn it with my hand.

Whatever controller you may be using, read it carefully.

You can turn the motor clockwise or anticlockwise. Or you can brake it to come to a stop.

You can ask it to hold at the current position (it won't move if you try to turn it by hand).

If you just apply DC to one (or more) of the winding, it will hold the position but MAY not be the current position.

Because the motor is stalled, it may draw excessive current. You must reduce to voltage (better the current) to a safe value.

ALL BLDC motors must have matching controller (driver) and they live on DC (generally low voltage compared to their power).

Many of them come with sensors so that the software knows where the rotor is currently positioned.
 

KlausST

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Hi,

generally speaking:
Almost every device (IC, transitor, resistor...motor...) comes with a datasheet.

the one who is building a circuit needs to read the datasheets (professionals do this, hobbyists should do the same) and needs to keep on the given specifications.

Just connecting battery voltage to two wires of a BLDC motor will cause overload, killing parts, maybe fire...

The above question is not stupid. Those and similar questions need to be answered when professionals design circuits, too.
What do one need for a detailied answer/calculation to this question:
* power supply voltage
* driving circuit including specification (datasheet)
* motor type including specification (datasheet)
* any other involved parts and their datasheets
* maybe a complete schematic and wiring diagram.

... and ohm´s law...
math skills: + - * /

Klaus
 

FvM

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Doesn't the vesc controller provide the feature to activate the motor with zero speed, in other words hold the position?
 

ferbo

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Doesn't the vesc controller provide the feature to activate the motor with zero speed, in other words hold the position?

Thank you for your help. I think it only works with an encoder. but i will look into it again.
 

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