Servosila-Device-Reference-0xA020192

by the manufacturer. This would establish a safety margin at the expense of
torque. If the design goal is to push the motor to its limit in terms of torque and
dynamics, it is still wise to start the commissioning procedure at a lower limit,
and gradually raise the limit while observing how the motor handles the heat,
particularly in stalled situations such as braking or direct drive modes. Note that
a motor is operating in its worse possible situation as far as heat dissipation is
concerned whenever the motor is producing maximum torque (=maximum
current) while stalled (=no motion), for example, in a braking mode or in a low-
speed direct drive mode.
Note a difference between a "maximum current" and a "nominal
current/maximum continuous current" characteristics of motors. Since
manufacturers of the motors use varying terminology, it is easy to get confused
and make a mistake. The term "maximum current" is what manufacturers often
use to define an electric current the motor can handle for relatively short periods
of time, typically a few seconds. This is not what needs to be configured here.
What we are looking for is "continuous" maximum current, often defined as the
"nominal" or "rated" current in datasheets. This is a phase-to-phase electric
current that a stalled motor can handle indefinitely without any damage due to
heat. To summarize the point, be extra careful with datasheet entries called
"maximum current". Those entries might define a current that is way above a
"continuous current/nominal current" limit that we are looking for.
HINT: If a brushless motor's datasheet defines both "nominal power" and
"nominal voltage" parameters, it is possible to derive implied "nominal current"
using a formula given below. However, please do not confuse "maximum power"
with "nominal power" as those might differ by a factor of five or more.
Maximum Continuous Current (Line-to-Line) = Nominal Power (W) / Nominal
Voltage (V) * 1.414213562
3 Poles Number
(Rotor Poles)
- The Poles Number parameter should be taken from the motor's datasheet, or it
can be determined experimentally. Note that the number of rotor poles is always
an EVEN number since magnet poles always come in pairs.
Note that some motor manufacturers specify "Pole Pairs" instead of "Poles
Number" in their datasheets. However, it is easy to convert "pole pairs" to
"poles". Just multiple the number of pairs by 2 to get the number of poles. For
example, if a motor has 8 "Pole Pairs", then it means that Poles Number is
8*2=16 poles.
The number of poles can be determined by looking inside the motor. Just count
the number of coils in the motor, divide it by 3, and then multiply by 2. For
example, if a motor has 21 stator coils, this means that Poles Number = (21 / 3) *
2 = 14.
If one cannot peek inside the motor, there is a simple procedure that
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