Speed sensorless control of PM synchronous machine using direct current control

In this paper a novel algorithm for torque and speed sensorless PMSM control is described. The PMSM rotor position and speed is acquired using sliding-mode rotor flux observer. Observer is based on the model of the PMSM where the derivation of the estimated stator flux is calculated from measured stator voltage and current. When implementing a multiple-loop control of a drive on a single processor, most of the computational time is devoted to the inner current-control loop calculation and generation of output voltage vectors in order to obtain proper drive current signal. The speed of the current controller and modulator is therefore essential for the performance of the control. Major attention is paid to current control constructed as direct current control using event-driven approach and implemented on FPGA. Event-driving determines the transistor switching pattern directly from the current error logic signals change and is designed using a novel matrix based description of the discrete event systems. It is based on matrix description of Petri nets, supplemented with a combination of logic and algebraic equations and introduces a kind of state-space description for discrete event systems. The control algorithms designed by proposed approach can be easily implemented on modern FPGA devices, which enable parallel execution of the calculations, comparing to the traditional sequential executions on the DSPs. Instead of traditional coding, the control algorithms are loaded in the form of logical matrices. The approach is utilized for torque/speed control based on the sliding mode rotor flux observer. The results of computer simulations are presented as well as the experimental hardware setup