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 technical report 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.
Background: basic six-step motor theory
 | 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 |
Vector-summed phase control tech report:
To discuss vector-summed motor-drive semi-custom design, contact Innovatia.
