Hall Sensor Selection

[Knuckles]

Well I seem to be blowing a lot of Hall sensors in my Grubee BL motors. My guess is heat is the enemy.
I am pushing 80V and 30 amps thru the motor and the sensors seem to blow on high acceleration.

I am using this Hall Sensor ... http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=480-1999-ND

But many different sensors are available. Can anyone suggest a more robust Hall Sensor that can take the heat?

 

[fechter]

That's the same sensor used on Crystalyte, Puma and BMC motors.

The datasheet says the maximum operating temperature is 150C. That's pretty damn hot.

Since the sensors are typically located right next to the windings, they might be getting pretty toasty.

I'm not aware of any sensors that are rated for higher temperatures.

One possibility would be to relocate the sensors away from the windings somehow. They just need to be triggered by the magnets at the correct time. I've seen some motors that use a separate encoder instead of triggering hall sensors directly from the motor magnets.
I've seen some motors that have the hall sensors located so the edge of the magnet triggers it, rather than the face, so the sensor is off to one side.

Maybe it's time for forced-air cooling

 

[Knuckles]

The funny thing is that the motor exterior is not hot or even warm. It may be an "instantaneous" heating effect. A rapid temperature rise within the stator coils that rapidly cooks the sensor. The stator is always fine but replacing those sensors is a real PITA! Plus this is Grubee’s original harness with those wimpy gauge phase wires. I haven't got around to rewiring this particular motor (now on the to-do list of course). But this also makes me think 'pedal first' controller.

To quote the bodaciously excellent dudes at ebikes.ca

"Pedal First Controllers: We are now replenishing the supply of sensor-less motor controllers, and have a new model on hand with IRFB4110 mosfets for operation up to 72V as well. These controllers without the hall sensor dependency are much more robust in wet or high exposure environments, where the Crystalyte Immediate Start systems have proven somewhat vulnerable. Highly recommended if you don't absolutely need assistance from zero speed."

Hmmm.

 

[The7]

Any internal picture for your Grubee BL motors showing the location of the Hall sensors?

 

[Knuckles]

Sure. I'll post pics here ... http://endless-sphere.com/forums/viewtopic.php?f=2&t=4626

I always like opening up these motors. Opening the motor is easy. Chiseling out those &%@#$%$ Hall Sensors sucks! BUT I DO LOVE 80+V! Yow!

I'll do a little hall replacement - harness replacement pictorial if that works for folks.

cheers

 

[Knuckles]

Hall Sensor Testing vid ...

[youtube]7m8DA6mmo84[/youtube]

 

[Microbatman]

Great work Knuckles!!!

You asked the question as to what hall sensor is the best heat/durability wise.

Have you been able to find out which one is the best?

If I need to someday replace mine want to put in the best possible and be prepared ahead of time.

Which ones would you reccommend for replacement on an X5?

Thanks

 

[dirty_d]

i notice they are bipolar, whats that mean? the datasheet really sucks.

 

[fechter]

i notice they are bipolar, whats that mean? the datasheet really sucks.

Maybe it means they have good days and they have bad days.

Actually, I think it means the output is driven both high and low vs. some models that only pull down.

 

[Larry]

Knuckles,

I'm wondering why you aren't just using Keywin's sensorless brushless controller? Is that controller just not able to handle the higher voltage you are running or something? My sensorless brushless controller is the 36v/48v model and it seems to be working just fine.

 

[Microbatman]

Where can one find these sensorless controllers?

Would like to check them out.

 

[Knuckles]

Knuckles,

I'm wondering why you aren't just using Keywin's sensorless brushless controller? Is that controller just not able to handle the higher voltage you are running or something? My sensorless brushless controller is the 36v/48v model and it seems to be working just fine.

Well, for a direct drive (DD) motor, nothing beats hall sensors for "Laying Rubber" out of the gate. A sensor-less requires some degree of back electromagnetic force (BEMF aka Back-Electro-Motive-Force) for it to operate. At low rpm on a DD motor, the BEMF is weak (and zero at no rotation), while with hall sensors BEMF is not utilized by the controller to make the motor "scream" from a dead start.

But Keywin's module will start the motor from a dead start by inducing a very small EMF (in stator coils) and then forcing rotation in the forward direction.
Totally cool! But on a DD motor not as much "burning rubber" as with hall sensors.

Once the rotor is turning then there is no difference between sensor and sensor-less (more or less true).

I just like really sick power from dead (balls to the wall - energy wasting - wheel screaming - gravel flying) start! My "front hub saw blade of death"!

But I suspect the sensor-less module will really shine on a geared motor.

Because BEMF is developed in a fraction of the wheel rpm as compared to a DD motor.

The module is a clear hit for simplicity alone and the ability to simplify the harness and
increase the gauge of the three fundamental power phase wires thru the axle.

-K

 

[Knuckles]

Where can one find these sensorless controllers?

Would like to check them out.

Just an email away!

ecrazyman@gmail.com

With full Knuckles F'n NY support of course ... 8)

 

[docnjoj]

I was just wondering if a Lithium battery cured Bipolar sensor disorder? Yes! That sensorless thingie seems to be the Bees kneez for a geared motor! We can forget about the "hall/phase wire mating dance"! John in CR should love it!
otherDoc

 

[MidniteTweeker]

We make the Hall sensors in question. 150C is a conservative temperature. The first failure point occurs when something melts at 200C. The die itself will work very briefly at 250C.

Is there a way to get a temp sensor (thermocouple maybe?) inside a motor and find out exactly what's happening temp-wise? I'm wondering if there could be some kind of electrical transient that's causing your problem.

MT