Brushless Motor -- Sensor Decoding???

[asic_designer]

Hi All

I am trying to dig up some information on decoding sensor outputs from Brushless motors, can you all give me a hand with this. The standard plug/cable that I see that comes with sensored brushless motors has six pins. Does anyone have a breakdown of those pins, what they are and how exactly to decode the output signal? Are the signals PWMs signals, digital, analog, what do they represent, how do I go about decoding them, etc.

Thanks in advance for your help!

 

[Icewrench]

My sensored motors have 8 wires. 3 for the phases 3 for the hall sensor signals and 2 for 5 volt hall power supply.

 

[friendly1uk]

They are hall sensors

 

[asic_designer]

My sensored motors have 8 wires. 3 for the phases 3 for the hall sensor signals and 2 for 5 volt hall power supply.

Hmmm

Thats odd the one I'm looking at only has 6 wires.

http://www.yeahracing.com/catalog/yeah-racing-hackmoto-brushless-sensored-motor-xtat075-p-3464.html

 

[asic_designer]

They are hall sensors

Ooook

Thanks. No temperature sensors, just hall sensors? What about a decoding method, can you point me to a tutorial? Don't worry I'll do a google search, as well.

 

[friendly1uk]

They are hall sensors

Ooook

Thanks. No temperature sensors, just hall sensors? What about a decoding method, can you point me to a tutorial? Don't worry I'll do a google search, as well.

Sorry, I thought from your project that a short answer might be enough.

All the halls do is give an analogue indication of the field strength they are subjected too.

 

[Futterama]

The motor in question is a RC motor. I have a motor from Yeah Racing, not this one, but another 1/10th scale motor so I know these motors.

The sensor wire contains GND, VCC (5V), Phase A signal, Phase B signal, Phase C signal and an optional thermo resistor. GND and VCC is the power supply for the hall sensors. Phase A, B and C signals are from the hall sensors and are digital signals, they can either be 0V or VCC (5V). The thermo resistor is a 10k NTC resistor with reference to GND.

I have a pinout of the standard 6 pin connector on another PC, I can dig it up for you, in the meantime, here is another pinout for you.

 

[nieles]

this is the decoding for the hall sensors

google '6 step commutation bldc'

 

[asic_designer]

The motor in question is a RC motor. I have a motor from Yeah Racing, not this one, but another 1/10th scale motor so I know these motors.

The sensor wire contains GND, VCC (5V), Phase A signal, Phase B signal, Phase C signal and an optional thermo resistor. GND and VCC is the power supply for the hall sensors. Phase A, B and C signals are from the hall sensors and are digital signals, they can either be 0V or VCC (5V). The thermo resistor is a 10k NTC resistor with reference to GND.

I have a pinout of the standard 6 pin connector on another PC, I can dig it up for you, in the meantime, here is another pinout for you.

Thanks a lot!!! This is part of what I needed. A little background, I am trying to create digital decoders for the sensors outputs from the motor, hence the subject Sensor Decoding. I want to create hardware circuits which decode the sensor outputs to integers for RPM, temperature, and speed. So maybe this clears things up a bit. Thanks again for the pinout!

Any info on how to take the sensor output and convert them to RPM, temperature, and speed would be great, I could then build the IC to do the conversions.

 

[asic_designer]

this is the decoding for the hall sensors

google '6 step commutation bldc'

Thanks, any info on a conversion algorithm to get RPM, and MPH?

 

[nieles]

well as you can see a single hall goes 'high' and 'low' in one electrical RPM (e-RPM)

then RPM = e-RPM / (number of pole pairs)

MPH = Pi x Diameter wheel x RPM x 60

 

[fechter]

The hall sensors require power, usually a +5v and a ground. There are 3 signal lines that will toggle as shown in the graph. If there is an extra wire, it might be for a temperature sensor.

If you have a working motor setup, you can use a meter or scope to see what the lines are doing. Otherwise, you should be able to find a datasheet for the motor.

 

[asic_designer]

well as you can see a single hall goes 'high' and 'low' in one electrical RPM (e-RPM)

then RPM = e-RPM / (number of pole pairs)

MPH = Pi x Diameter wheel x RPM x 60

You guys are great, thanks, this is what I was looking for. So my next question is, why the need for three sensors? I know there is one for each phase but how do three sensors factor into those equations?

 

[fechter]

If you go back to the graph, you'll see that using 3 sensors gives 6 steps in the cycle. In each step a different pair of phase wires are active. The right phase wires need to be active to apply magnetic force in the right direction. It doesn't matter where the motor stops, as the correct phases will be activated when it starts up from a stop.

The phase wires are tri-state. Each one can connect to either the + supply, ground, or be open. The hall state has to tell the output transistors which ones are on or off. This is usually a 3 phase bridge with 6 switching transistor banks. Each bank may have one or more FETs or IGBTs in parallel.

Some motors use more than 3 phases, but they are not common on bike motors.

You could use optical sensors or some other encoder to determine rotor position.

 

[asic_designer]

Thanks for all the replies!

I guess what I am looking for "bottom line" are the equations that take the inputs from these three sensors and turn the data into MPH, and RPM. Now I saw the equations posted a few posts back, but I need to know how the three sensors factor into those equations. Also I need to know the same for the temperature sensor. I'm sure plenty of you have written C code which does this, all I need are the equations, or the code, that will work to I can work it out from there.

Thanks again.