This block implements the extended back-emf integration method.
It determines the time of a zero crossing by evaluating the slope of the back-emf. In the next step, the slope is also used to calculate the time when the next commutation is required.
TODO:
1. Implement the ADC-DMA-method and evaluate the measurements only when the ADC callback is executed.
2. In case the single-leg-PWM is applied, evaluate only the measurements when high side switch is on.
3. In case the function is called late, i.e. the zero crossing already happened, use the earliest voltage measurements and slope to determine when the zero crossing occured.