Datasheet

ManualsBrandsTEXAS INSTRUMENTS ManualsDev KitsPCB design board

Texas Instruments

Dave ¶s

Motor Control

Center

Texas Instruments

Dave ¶s

Motor Control

Center

sensor

Noise SusceptibilityNoise Susceptibility

Sensor IssuesSensor Issues

Sensor CablingSensor Cabling

Sensor ConnectorSensor Connector

Sensor Power SuppliesSensor Power Supplies

-V

sensor

FAST Provides Sensorless FOC Performance

www.ti.com

With any technique, the process of producing a stable software sensor is also extremely challenging, as

this motor model (observer) is essentially its own control system that needs to be tuned per motor across

the range of use. This tuning must be done with a stable forward control loop. Needed is a stable torque

(and usually speed) loop to tune the observer, but how do you pre-tune your forward control without a

functioning observer? One option is to use a mechanical sensor for feedback to create stable current and

speed loops, and then tune your software sensor in parallel to the mechanical sensor. However, the use of

a mechanical sensor is often not practical. This problem has delayed market use of software sensors for

sensorless FOC control.

Figure 3. Sensored FOC System

In summary, these existing solutions all suffer from various maladies including:

• Poor low-speed performance (back-EMF and SMO)

• Poor high-speed performance (saliency observers)

• Poor dynamic response

• Calculation intensive (multi-modal observers)

• Parameter sensitivity

• Requirement for observer tuning.

The most recent innovation in the evolution of sensorless control is InstaSPIN-FOC. Available as a C-

callable library embedded in on-chip ROM on several TI processors, InstaSPIN-FOC was created to solve

all of these challenges, and more. It reduces system cost and development time, while improving

performance of three-phase variable speed motor systems. This is achieved primarily through the

replacement of mechanical sensors with the proprietary FAST estimator. FAST is an estimator that:

• Works efficiently with all three phase motors, taking into account the differences between

synchronous/asynchronous, salient/non-salient, and permanent/non-permanent/induced magnets.

• Dramatically improves performance and stability across the entire operating frequency and load range

for a variety of applications.

• Removes the manual tuning challenge of traditional FOC systems:

– Qbservers and estimators, completely removes required tuning.

– Current loop regulators, dramatically reduces required tuning.

TMS320F28026F, TMS320F28027F InstaSPIN™-FOC Software SPRUHP4–August 2013

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