Specifications

MODELS 7225AC, 7425AC
LINE-POWERED AC BRUSHLESS SERVO AMPLIFIERS
WITH +/-10V ANALOG U-V INPUTS
APPLICATION INFORMATION
EXTERNAL COMMUTATION OVERVIEW
The model 7XX5AC amplifiers are designed to work
with controllers that perform external commutation to drive AC
brushless motors. Lower torque ripple can be obtained by
sinusoidal commutation of the three-phase motor than can be
obtained by trapezoidal commutation. The figure below shows
a typical external commutation configuration using an encoder
for determining position. The controller uses two DAC outputs,
the U and V Phase, to drive the U and V reference inputs on
the amplifier. The amplifier then generates W Phase and
delivers power to all three motor windings simultaneously.
The encoder data is processed by the controller, to
generate the sinusoidal waveform signals, which are delivered
to the amplifier. These waveforms are typically 120
phase
separated, a jumper in the amplifier can be moved for 90
phase separation. The controller will perform a phase
initialization routine for proper commutation. Improved phase
initialization can be achieved by using Hall sensors for
determining initial position.
Controler
Motor
Amplifier
Phase U
Phase V
Phase
W Gen.
Encoder
Optional Halls
U
V
W
Copley Controls Corp, 20 Dan Road, Canton, MA 02021, USA Tel: [phone] Fax: [phone]
E-mail: [e-mail], on the Internet at http://www.copleycontrols.com Page 7 of 12
AMPLIFIER WIRING & CABLING
Power supply and motor connections should be made with wire
that has a rating to support the amplifiers continuous current.
AWG 14 wire will support all amplifiers in this series. To
minimize noise radiation from the motor and power cabling,
wires should be twisted and shielded. Motor sensor signals are
often routed near the motor phase winding cables. To minimize
coupling of PWM noise, sensor signal wiring should be
multiple-conductor-shielded cable.
GROUNDING AND ISOLATION
The signal board is fully isolated from the power section in this
series of amplifiers. For proper operation, connect the signal
ground J3-13 to the controller ground.
For safety, it is important that J1-3 be connected to earth
ground, typically through the power cable.
The connections on the power board, such as the motor phase,
are at line potential.
SETUP FOR THE MOTOR
The motor windings and encoder are to be connected in
accordance with the control card setup.
MOTOR INDUCTANCE COMPENSATION
Header components control the amplifier compensation for
different motors. These set the gain in the current error
amplifier to give the best response for different winding
inductance. There are two current-control loops in this series of
amplifiers, both must have the same values in the header.
The tables below give values for the header parts for the two
models. The default values for RH11 and RH14 are indicated
below in bold & italic. If the inductance of your motor is less
than ½ of the value shown in the table, use the values from the
next lower inductance range. Ex., for a 4 mH motor, use the
values from the 3 mH row (1/2 of 10mH is 5mH, which is
greater than 4mH, so the value from the next lower row, 3mH,
is used).
For all tables: CH12 & CH15 are <out>
Model 7225AC @ 115VAC; CH10 & CH13 = 15nF
L (mH) R11& RH14 (k
)
0.3 18
1 39
3 75
10 180
30 300
Model 7425AC @ 230VAC; CH10 & CH13 = 10nF
L (mH) R11& RH14 (k
)
0.3 12.5
1 24.9
3 51
10 120
30 200
Model 7425AC @ 115VAC CH10 & CH13 = 10nF
L (mH) R11& RH14 (k
)
0.3 18
1 39
3 75
10 180
30 300
If the default values do not give sufficient bandwidth, contact
factory for a detailed tuning procedure.
Phone: [phone]
Phone: 877-IP-Tech1
Fax: 877-IP-Tech2
www.iptech1.com
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