Unlike the flux signal, the back-EMF signal amplitude diminishes at lower speeds, resulting in poor signal-to-noise performance. back-EMF zero-cross timing also enables more stable operation at lower speeds. Abrupt speed changes will be reflected in the flux waveform in real time, so that it will still cross the specified threshold value at exactly the right time to commutate. But InstaSPIN-BLDC monitors a real-time flux waveform to determine the appropriate time to commutate. With zero-cross timing, you are always using PAST information to predict FUTURE commutation events. In addition to its ability to work with just about ANY BLDC motor, InstaSPIN-BLDC has demonstrated incredible resilience to speed transient perturbations.
Optimal commutation can be verified by observing the phase voltage and current waveforms, which are also displayed.
With the help of a free GUI (see figure), the user can watch the flux signal in a plot window, and set the “Flux Threshold” slider to specify at what flux level the motor should be commutated. Unlike other sensorless BLDC control techniques based on back-EMF zero-cross timing, InstaSPIN-BLDC monitors the motor’s flux to determine when to commutate the motor. In field tests with over 50 different motor types, InstaSPIN-BLDC was able to get each motor up and running in less than 20 seconds! The reason for this incredible robustness is because InstaSPIN-BLDC doesn’t require any knowledge about motor parameters to work, and you only need to adjust a single tuning value. Targeted at low cost BLDC applications, InstaSPIN-BLDC is a sensorless control technique based on the premise that “simple is better”. In keeping with TI’s philosophy of making motor control more accessible and easier to use by design engineers, TI is proud to announce the release of its newest motor control technology, InstaSPIN-BLDC.