Current slope calculation in FPGA for sensorless control technique and associated slope based predictive precise current control

This paper introduces a new approach to measure the current slope only with normal current sensors. The current slope, which is caused by voltage switching of PWM amplifiers, can be used for a sensorless control technique for magnetic bearings or electrical drives. Further, with the information of the slope, we can realize a predictive precise current control. By combining the current sensor, analogue-to-digital converter and FPGA, using the proposed multiple current sampling technique, the current slope will be calculated in hardware with the method of least squares. This sub-system acts like a virtual sensor, which delivers both current and its slope values at the given sample point.