Sinusoidal commutation typically leverages the mathematics of Clarke and Park transforms, performing 3-phase to 2-phase conversions, calculating rotating coordinate conversion, and implementing space vector modulation. In addition to executing these algorithms, motor currents must be measured using an analog-to-digital converter (ADC), and new output signals must be generated using pulse-width-modulated (PWM) timers. In a pure software implementation, this places a significant load on a processor.
This can make it especially challenging to implement the tests required of IEC 60730 (White Goods Safety Standard). For comprehensive compliance, control equipment needs to monitor software flow, interrupt handling, communication through I/O ports and the functionality of memory. If the processor is continuously occupied by the real-time demands of the motor control implementation, it becomes increasingly difficult to execute the necessary safety tests.
One approach to simplifying this complexity is by implementing the complex control mathematics in a dedicated hardware peripheral, an approach taken in the TXZ family of Arm® Cortex® based MCUs. Its Vector Engine (VE) not only implements the Park-Clarke transformations required for motor control but is also tightly coupled with the other on-chip peripherals needed for accurate motor control. This includes the pulse-width-modulation (PWM) timers and the analog-to-digital converter (ADC). Such tight integration simplifies configuration, ensures accuracy and efficiency in control, and leaves the developer with significantly more scope to schedule the necessary execution of safety functions.
To find out more about how such motor control microcontrollers can be used to develop safe household appliances, take a look at our latest whitepaper: