Specifications

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APPLICATION INFORMATION
To use the model 503 set up the internal header with the
components that configure the transconductance, current
limits, and load inductance. Current-limits and load
inductance set up the amplifier for your particular motor,
and the transconductance defines the amplifiers overall
response in amps/volt that is required by your system.
COMPONENT HEADER SETTINGS
Use the tables provided to select values for your load and
system. We recommend that you use these values as
starting points, adjusting them later based on tests of the
amplifier in your application.
LOAD INDUCTANCE (RH1,CH2)
Maximizes the bandwidth with your motor and supply
voltage. First replace CH2 with a jumper (short). Adjust the
value of RH1 using a step of 1A or less so as not to
experience large signal slew-rate limiting. Select RH1 for
the best transient response ( lowest risetime with minimal
overshoot). Once RH1 has been set. choose the smallest
value of CH2 that does not cause additional overshoot or
degradation of the step response.
TRANSCONDUCTANCE (RH6,7)
The transconductance of the 503 is the ratio of output
current to input voltage. It is equal to 10kΩ/RH6 (Amps/
Volt). RH6,and RH7 should be the same value and should
be 1% tolerance metal film type for good common-mode
noise rejection.
CURRENT LIMITS (RH3, 4, & 5)
The amplifier operates at the 5A continuous, 10A peak
limits as delivered. To reduce the limit settings, choose
values from the tables as starting points, and test with your
motor to determine final values. Limit action can be seen
on current monitor when output current no longer changes
in response to input signals. Separate control over peak,
continuous, and peak time limits provides protection for
motors, while permitting higher currents for acceleration.
SETUP BASICS
1. Set RH1 and CH2 for motor load inductance (see
following section).
2. Set RH3, 4, & 5 if current limits below standard values is
required.
3. Ground the /Enable (/Enable Pol open), /Pos Enable,
and /Neg Enable inputs to signal ground.
4. Connect the motor Hall sensors to J2 based on the
manufacturers suggested signal names. Note that
different manufacturers may use
A-B-C, R-S-T, or U-V-W to name their Halls. Use the
required Hall supply voltage (+5 or +15V). Note that
there is a 30 mA limit at +5V. Encoders that put-out Hall
signals typically consume 200-300 mA, so if these are
used, then they must be powered from an external
power supply.
5. Connect J1-4,5 to a transformer-isolated source of DC
power,
+18-55V. Ground the amplifier and power supply with an
additional wire from J1-5 to a central ground point.
6. With the motor windings disconnected, apply power and
slowly rotate the motor shaft. Observe the Normal (green)
led. If the lamp blinks while turning then the 60/120°
setting is incorrect. If J2-2 is open, then ground it and
repeat the test. In order to insure proper operation, the
correct Hall phasing of 60° or 120° must be made.
6.Turn off the amplifier and connect the motor leads to
J1-1,2,3 in U-V-W order. Power up the unit. Apply a
sinusoidal reference signal of about 1 Hz. and 1Vrms
between
Ref(+) and Ref(-), J2-10,11.
7. Observe the operation of the motor as the current monitor
signal passes through zero. When phasing is correct the
speed will be smooth at zero crossing and at low speeds. If
it is not, then power-down and re-connect the motor.
There are six possible ways to connect the motor windings,
and only one of these will result in proper motor operation.
The six combinations are listed in the table below. Incorrect
phasing will result in erratic operation, and the motor may
not rotate. When the correct combination is found, record
your settings.
J1-1 J1-2 J1-3
#1 U V W
#2 V W U
#3 W U V
#4 U W V
#5 W V U
#6 V U W
GROUNDING & POWER SUPPLIES
Power ground and signal ground are common ( internally
connected ) in this amplifier. These grounds are isolated
from the amplifier case which can then be grounded for best
shielding while not affecting the power circuits.
Currents flowing in the power supply connections will create
noise that can appear on the amplifier grounds.
This noise will be rejected by the differential amplifier at the
reference input, but will appear at the digital inputs. While
these are filtered, the lowest noise system will result when
the power-supply capacitor is left floating, and each ampli-
fier is grounded at its power ground terminal ( J1-5 ). In
multiple amplifier configurations, always use separate
cables to each amplifier, twisting these together for lowest
noise emission. Twisting motor leads will also reduce
radiated noise from pwm outputs. If amplifiers are more than
1m. from power supply capacitor, use a small (500-1000µF. )
capacitor across power inputs for local bypassing.
Model 503
DC Brushless Servo Amplifier