a
FEATURES
Current Conditioning
Complete Vector Transformation on Silicon
Three-Phase 120擄 and Orthogonal 90擄 Signal
Transformation
Three-Phase Balance Diagnostic鈥揌omopolar Output
DQ Manipulation
Real-Time Filtering
APPLICATIONS
AC Induction Motor Control
Spindle Drive Control
Pump Drive Control
Compressor Drive Control and Diagnostics
Harmonic Measurement
Frequency Analysis
Three-Phase Power Measurement
Cos
胃
Sin
胃
Cos
胃
Cos (
胃 +
120
Cos (
胃 +
240
擄)
Sin
胃
I
S1
I
S2
3
蠁
-2
蠁
I
S3
Vqs
Vds
Three-Phase
Current Conditioner
AD2S105
FUNCTIONAL BLOCK DIAGRAM
INPUT
DATA
STROBE
蠁
POSITION
PARALLEL
DATA
12 BITS
BUSY
SECTOR
MULTIPLIER
SINE AND
COSINE
MULTIPLIER
Cos
胃 + 蠁
Vds'
SECTOR
MULTIPLIER
SINE AND
COSINE
MULTIPLIER
Vqs'
Sin
胃 + 蠁
CONV1
CONV2
DECODE
Ia + Ib + Ic
3
HOMOPOLAR
REFERENCE
+5V GND 鈥?V
HOMOPOLAR
OUTPUT
GENERAL DESCRIPTION
A two-phase rotated output facilitates the implementation of
multiple rotation blocks.
The AD2S105 is fabricated on LC
2
MOS and operates on
鹵
5 volt power supplies.
PRODUCT HIGHLIGHTS
The AD2S105 performs the vector rotation of three-phase 120
degree or two-phase 90 degree sine and cosine signals by trans-
ferring these inputs into a new reference frame which is controlled
by the digital input angle
蠁.
Two transforms are included in the
AD2S105. The first is the Clarke transform which computes
the sine and cosine orthogonal components of a three-phase in-
put. These signals represent real and imaginary components
which then form the input to the Park transform. The Park
transform relates the angle of the input signals to a reference
frame controlled by the digital input port. The digital input
port on the AD2S105 is a 12-bit/parallel natural binary port.
If the input signals are represented by Vds and Vqs, respectively,
where Vds and Vqs are the real and imaginary components, then
the transformation can be described as follows:
Vds' = Vds Cos蠁 鈥?Vqs Sin蠁
Vqs' = Vds Sin蠁 + Vqs Cos蠁
Where Vds' and Vqs' are the output of the Park transform
and Sin蠁, and Cos蠁 are the trigonometric values internally cal-
culated by the AD2S105 from the binary digital data
蠁.
The input section of the device can be configured to accept
either three-phase inputs, two-phase inputs of a three-phase
system, or two 90 degree input signals. The homopolar output
indicates an imbalance of a three-phase input only at a user-
specified level.
The digital input section will accept a resolution of up to 12 bits.
An input data strobe signal is required to synchronize the position
data and load this information into the device counters.
REV. 0
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
Current Conditioning
The AD2S105 transforms the analog stator current signals (I
s1
,
I
s
2
, I
s
3
) using the digital angular signal (reference frame) into dc
values which represent direct current (I
ds
) and quadrature cur-
rent (I
qs
). This transformation of the ac signals into dc values
simplifies the design of the analog-to-digital (A/D) conversion
scheme. The A/D conversion scheme is simplified as the band-
width sampling issues inherent in ac signal processing are
avoided and in most drive designs, simultaneous sampling of the
stator currents may not be necessary.
Hardware Peripheral for Standard Microcontroller and DSP
Systems
The AD2S105 off-loads the time consuming Cartesian transfor-
mations from digital processors and benchmarks show a signifi-
cant speed improvement over single processor designs. AD2S105
transformation time = 2
碌s.
Field Oriented Control of AC Motors
The AD2S105 accommodates all the necessary functions to pro-
vide a hardware solution for current conditioning in variable
speed control of ac synchronous and asynchronous motors.
Three-Phase Imbalance Detection
The AD2S105 can be used to sense imbalances in a three-phase
system via the homopolar output.
One Technology Way, P.O. Box 9106, Norwood. MA 02062-9106, U.S.A.
Tel: 617/329-4700
Fax: 617/326-8703
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