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AD2S105AP

Three-Phase Current Conditioner

Analog Devices 

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FEATURES

Current Conditioning

Complete Vector Transformation on Silicon

Three-Phase 120° and Orthogonal 90° Signal

Transformation

Three-Phase Balance Diagnostic–Homopolar 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

Three-Phase

Current Conditioner

AD2S105

FUNCTIONAL BLOCK DIAGRAM

Cosθ Sinθ

INPUT

DATA

STROBE

φ POSITION

PARALLEL

DATA

12 BITS

IS1

Cosθ

Cos (θ + 120°) IS2

IS3

Cos (θ + 240°)

Sinθ

Vds

SECTOR

MULTIPLIER

SINE AND

COSINE

MULTIPLIER

3φ-2φ

Vqs

SECTOR

MULTIPLIER

SINE AND

COSINE

MULTIPLIER

Vds'

Vqs'

BUSY

Cos θ + φ

Sin θ + φ

CONV1

CONV2

DECODE

Ia + Ib + Ic

3

HOMOPOLAR HOMOPOLAR +5V GND –5V

OUTPUT

REFERENCE

GENERAL DESCRIPTION

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 φ. 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 Cosφ – Vqs Sinφ

Vqs' = Vds Sinφ + Vqs Cosφ

Where Vds' and Vqs' are the output of the Park transform

and Sinφ, and Cosφ are the trigonometric values internally cal-

culated by the AD2S105 from the binary digital data φ.

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.

A two-phase rotated output facilitates the implementation of

multiple rotation blocks.

The AD2S105 is fabricated on LC2MOS and operates on

± 5 volt power supplies.

PRODUCT HIGHLIGHTS

Current Conditioning

The AD2S105 transforms the analog stator current signals (Is1,

Is2, Is3) using the digital angular signal (reference frame) into dc

values which represent direct current (Ids) and quadrature cur-

rent (Iqs). 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 µs.

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.

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.

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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