Vector-Based Six-Step Sensorless Phase Control

The novel application of leading-edge motor theory has led to an improvement and simplification of accurate six-step PMS motor control for high-volume, cost-sensitive applications. Precise phase control of step advancement is achieved by sensing motor phase directly, from its induced terminal voltages, and combining winding voltages vectorially to produce waveforms that correctly commutate the motor at their zero-crossings. The result is higher, smoother torque and is simple to implement.

This technology is based on an evolving approach to motor drives with the following features:

Low-cost, microcontroller-based

Drives 3-phase Y- or delta-configured PMS motors

Uses innovative, six-step vector-summed phase control

Calculates 6-step switching points from vectorially-combined winding voltages

Common-mode rejection of PWM noise

Operates down to near-zero speed

Hardware options: programmed controller IC or complete drive design

Few parts: fits into the end-cap of a "smart motor" design

No position sensors or A/D conversion is needed, resulting in low-cost implementation which can be customized for a wide range of cost-sensitive applications. 

Novel vector-summed phase-control theory along with basic 3-phase PMS motor principles includes both basic theory and more detailed derivations for two implementation methods
Designware files begin with simple, open-loop stepping, and progress through external sensor-driven control to sensorless vector-summed control
Command interface designs included

The StepMaker Vector-Summed Motor-Drive project manual is currently being written. The StepMaker is also undergoing some design refinement. Contact Innovatia for details.

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