I'm interestig in control of BLDC motor. I have one of this motor,their
trade is GLOBE MOTOR and it is in automotive application, Electric
Power Steering of Fiat Stilo has one.
This motor has 11 pin, 3 are big (is possible are power supply), other
8 are small. 2 of this are controling one relay that short circuit the
3 big pin. Is possible stop this type of motor when you short circuit??
I would like have the datasheet and pin out of this motor.
Thank you and sorry for muy english.
Your English is plenty good enough. Brushless DC motors commonly have
Hall-effect sensors built in to control the commutation; the smaller
contacts probably connect to them. I agree that the larger contacts
probably connect to the coils, but I can't guess about how they are
wired internally. A delta connection is difficult to drive. Is the frame
used as a common? An ohmmeter might tell.
Shorting the coils together applies a braking torque proportion to
rotation speed. It won't hold the motor, but it will slow it.
Thanks for your help. I move de rotor with the help of drill and I
measure the larger contacts and they have voltage. When I probe to
measure with ohmmeter, it don=B4t measure anything, I don't know why.
Many ohmmeters aren't sensitive enough to distinguish fractional ohms
from a short circuit. Do you measure zero ohms? That would indicate a
low-resistance winding, what I would expect.
Globe has been around for a long time. You can probably get a data sheet
Thanks for all !!!
This motor is in EPS (Electric Power Steering) of FIAT STILO,and I
would like have its datasheet (winding connection,Ke,Km, Power,J, R,
L,...) because I would like simulate in Simulink.
I would like to control with a Data Acquisition Target (Advantech) and
3 phase bridge with mosfet (International Rectifier F1404L)
I would like very much model this type of motor. Have you any idea?
Ask Globe Motor if they can identify the motor you have. I gave you the
URL of their catalog, but they make specials. Most specials are simply
winding variations on their standard frames, so inertias will have the
catalog values. You may need an accurate measurement of winding
resistance so they can help you identify the part.
If you find a picture of the motor in the catalog, you can infer winding
variations by comparing the torque constant you measure with the
Do you mean brushless motors in general, or this particular motor?
Have you done a web search on modeling brushless motors?
Here's a rough guess at how you should go about it. Anything I say here
should be backed up with measurements and experiments, and probably with
reference to a text on electrical machines.
The electromechanical torques on a brushless motor will be due to two
things: the cogging torque, which is a function of the geometry of the
magnets and iron in the motor, and the motor torque, which is a function
of the magnets, iron, windings and current.
The cogging torque is nominally a sine wave with a period equal to
1/(P*N) revolutions, where P is the number of magnetic poles and N is
the number of phases (brushless motors are almost always three phase).
In reality it's not really sinusoidal and it really has a period of 1
rotation; it's up to you to discover/decide how close your motor is to
The motor torque is nominally a product of the torque constant (kt)
times the current in one winding times the sine of the angle between
that winding and the magnets -- so if you energize one winding you'll
see the motor snapping to one position and staying there; driving the
motor requires that you keep the leading coil energized in the correct
direction so the motor will go the direction you want it to go. Your
motor sounds like it's connected in a delta (3 heavy wires), which means
that you can't energize just one winding, but running a current through
any one pair of terminals should get the same effect.
In reality this motor torque will not be sinusoidal; once again it's up
to you to decide/determine how far off it is. In addition iron
saturates, so the motor torque won't be quite proportional to current,
although this is usually not a big deal unless you need to do some
pretty tight simulations, or if you're worried about motor efficiency.
As the motor turns it generates a voltage ("back EMF"). In a perfect
motor the relationship between motor voltage vs. speed and torque vs.
current are the same; this is a direct consequence of the power balance
equation that says that power in = power out, so voltage * current =
torque * speed. The primary effect of this back EMF is that if you
drive your motor with a constant-voltage drive it'll draw lots of
current at stall, then as the motor speeds up the back EMF will reduce
the voltage available to drive current through the armature so the motor
will draw less and less current until finally the torque required to
turn the armature equals the torque available and the speed will level out.
At this point I've done two things: I've used up a page of text, and
I've only scratched the surface of how the motor works. Once again, you
need to get a good book on electric machines and spend some quality time
with it. The electric machines book that I use is "Electric Machines -
Steady State Theory and Dynamic Performance" by Mulukutla S. Sarma.
It's what I use for a reference but it's a bit out of date and not the
best for self-study. It's also the only one that I've read so I can't
recommend any other.
Then you should ask their customer support people for for the motor's
descriptive constants. Assuming that you connect it in in the expected
way, the motor's torque, voltage, and speed constants are used pretty
much like any other PM DC motor. The cogging will be higher than with a
brush servo motor because there are only three poles, but that is a
Circuitry beginning with the Hall effect sensors and ending with the
MOSFET H bridges replace physical brushes while performing the same
function. It is basically a PM motor. You can control the speed by
varying the applied voltage, just as with any PM motor. Since the drive
is electronic, you can do that with PWM on the drive transistors. Think
of that as a superposition of two controls; one for speed, the other for
commutation. During the 'off' time, you want to open-circuit the
windings, not short them.
Thanks Tim and Jerry for your answer.
When I have 3 phase bridge, and use PWM, how I control speed of motor??
I Know that in PWM:
Voltage=>V=Vn*D and D=t/T (duty cycle)
where t=Signal On time and T=period
Duty cycle=(Motor Rated Voltage/DC bus voltage)* Speed Reference
Are correct this calculus??
How I know if my motor is delta or star??
In this type of motor, can I control torque?? Because I have control
the amount of assistence.
I search information and I have the conmutation of this type of motor
when you have Hall sensors at 60 degrees.I have the truth table and
which phases I have applied voltage.
Thank you for all!!!
I don't know what "Speed Reference" stands for, but probably. Do you
intend to run the motor open loop? If not, it hardly matters.
Delta is most likely. With three coil leads, star can only be
accomplished by using the frame (check with ohmmeter) or by letting the
neutral float. The only difference between delta and floating neutral is
effective winding impedance. It doesn't matter to you whether the
winding impedance you see is caused by connections or wire size.
Torque is proportional to current. The motor torque/speed/voltage
relations are essentially the same as a two-wire permanent-magnet
carbon-brush motor. Small ones of that type are used in electric toys.
You need to understand one of those to accomplish what you want.
That's a good place to start.
Normally you switch from one winding to the next depending on the
position of the motor, and control the current or voltage to control
motor speed, much like a regular DC motor.
Yes, the torque is proportional to motor current if you're commutating
You need a web page or book section on "How to control brushless
motors". This is a big subject, and you seem to be pretty light on the
required information. It's _not_ something that can be easily answered
in a few newsgroup postings.