Motor control algorithm makes sensors redundant

February 28, 2013 // By Christoph Hammerschmidt
Motor control system designers can concentrate on differentiating designs rather than spending weeks and months tuning their motor control systems, promises Texas Instruments to users of its InstaSPIN-FOC (field-oriented-control) solution. It enables designers to identify, tune and control (through variable speeds and loads) any type of three-phase, synchronous or asynchronous motor in five minutes or less and removes the need for a mechanical motor rotor sensor.

Using TI's software encoder (sensorless observer) algorithm, FAST (flux, angle, speed and torque), embedded in the read-only-memory (ROM) on TI’s 32-bit C2000 Piccolo microcontrollers, InstaSPIN FOC reduces system costs and improves operation, the vendor promises. The system joins the previously introduced InstaSPIN-BLDC technology.

Many industries have delayed the use and adoption of sensorless FOC motor techniques because of the lack of motor control system knowledge, despite the many system benefits these techniques provide. InstaSPIN-FOC eases development and reduces system cost and complexity for designers — even those with limited motor control experience — and enables solutions that improve motor efficiency, performance and reliability in all variable speed and load motor applications. In traditional FOC motor designs, the use of a rotor sensor can impact a system with increased costs (sensor, power supply, special cabling and connectors, installation and maintenance) and potentially lower reliability (performance degradation in harsh conditions, electrical noise, temperature and humidity). In addition, using a sensor in many applications, such as an enclosed compressor or a large traction machine, is also impractical.

Features and benefits of InstaSPIN-FOC technology:

  • Save months of design time with nearly fully automated identification and control tuning, allowing designers to differentiate their products with capabilities beyond full motor torque.
  • Near encoder performance with embedded on-chip FAST observer algorithm calculating a reliable and robust estimation of flux, angle, speed and torque across use conditions. Accurate, sensorless “estimator” performance eliminates the need for a physical encoder in most cases.

Accommodate all three-phase motors , synchronous (BLDC, SPM and IPM) and asynchronous (ACI) with the same solution.

Identify and tune with off-line motor commissioning that identifies the needed electrical parameters of the motor, tunes the FAST algorithm, and initializes the current controllers for stable operation. An optional online resistance re-estimation mode which tracks changes for robust observer performance in the harshest use cases is also offered.

Eliminate start-up challenges of other sensorless techniques with built-in start-up