In search of a quieter life - combatting noise and vibration via innovations in motor control

To meet the pressing need for elevated levels of energy efficiency, the conventional direct current (DC) motors incorporated into electric fans, domestic appliances, air conditioning systems, office equipment and such like, have over time been replaced by more sophisticated three-phase brushless DC (BLDC) motors. This has enabled compliance with the stringent international environmental guidelines that have now emerged, as well as helping to reduce the size of utility bills. In addition to minimising the degree of power dissipation witnessed, these applications mandate that the motors utilised are able to keep both acoustic noise and vibrations to a minimum. The need to accomplish this has prompted a migration from away from square wave motion control and resulted in greater implementation of sine wave control. To maximise motor performance, sine wave control requires phase adjustment between motor voltage and motor current. However, this has meant that realising high efficiency over a wide range of rotational speeds often proves to be a long drawn out and complex process.

Fixed lead angle BLDC motor control arrangements have been supplanted by ones which automatically control of the lead angle. Nevertheless these arrangements still have their drawbacks in terms of the lead angle needing to be set for each specific motor based on a variety of different factors. The emergence of more advanced lead angle control technology is showing its effectiveness at delivering energy efficient motor operation (with 20% power savings compared to alternative solutions), plus low vibration and low noise, across the full breadth of rotational speeds (rather than having to focus on optimisation at either low speed or high speed).

Toshiba has published a detailed white paper on next generation BLDC motor control. To download click here: