Control system enables smooth motor movements

The Digital Spin, or Dspin, combines all the necessary digital control, analogue measurement and power electronic circuitry for controlling stepper motors using ST's BCD fabrication process.

It is the first device in ST's Dspin range of monolithic motor-control ICs that will bypass specialised hardware and software design tasks, reduce component count and PC-board area, as well as speed time to market.

Implementing the motor-control calculations in hardware simplifies software design by requiring only acceleration, deceleration, speed and target position commands from the application microcontroller.

This frees microcontroller resources to support other differentiating features.

The Dspin ensures smooth movement of the motor by using a voltage-mode control algorithm.

The voltage-mode approach allows full digital control, feeding the motor phases with an accurate sinusoidal waveform and resulting in position resolution of 128 microsteps per step.

Other advantages include reduced resonances, mechanical noise and low-speed vibration, as well as reduced speed and torque ripple at low speeds.

'The Dspin, with its integrated digital control core, extends the ST Powerspin product platform,' said Pietro Menniti, group vice-president and general manager of the Industrial and Power Conversion Division, ST Microelectronics.

'The high steps resolution, the digital motion management, the full set of protections and a dual H-bridge power switch array connecting directly to motor phases, enable the Dspin to deliver in applications requiring one or more motors up to 100W,' he added.

Using analogue integration as part of its BCD process, ST has been able to implement protection features including over-temperature protection, low bus voltage protection, non-dissipative over-current protection and motor stall detection.