Е. М. Solodkiy - Senior Lecturer, Perm National Research Polytechnic University. Е-mail: wsdl00@gmail.com
D. А. Dadenkov - Senior Lecturer, Perm National Research Polytechnic University. Е-mail: dadenkov@mail.ru

This article presents a concept of building voltage source inverter model, working on the master voltage vector playback algorithm using space vector pulse width modulation (SVPWM) technique. To implement SVPWM algorithms proposed an approach based on the use of two coordinate transformations. The transformation from a three-phase coordinate system (ABC) to a biphasic fixed axes in α, β are made in addition bringing the vector to the first sector accounting the current position of the vector in a particular sector is implemented, which minimizes the computation time. The proposed SVPWM model provides the formation of output line voltage vector repeating a given vector, which can be defined in a stationary-phase or сartesian coordinate system. The model also reflects the real time delays, i.e. interrupting routines of the microcontroller in which calculations and SVPWM transformations are performed. Therefore, the proposed method allows to implement the SVPWM algorithm with minimal microcontroller's CPU usage. Let's consider the function blocks and the principle of the proposed algorithm. The sector calculator unit generates sector number in which the voltage vector defined by it's projections on the αβ axis. Then the voltage vector is oriented to the first sector using coordinate transformations. Calculating time of switching unit sets the on time of adjacent vectors: T1, T2 and time T0, when the voltage vector is 0 (turn on or off state of all the upper switches of VSI). Ramp unit (RU) samples the signal rising linearly from 0 to 2 during Ts. Sampling frequency simulates microcontroller's interrupt frequency in which the time of switching will be calculating. The higher this frequency, the higher the accuracy of the calculation of switching times on the other hand it's leads to microcontroller's CPU load. The optimal frequency of interruptions can be found from the condition of not exceeding a specified total harmonic distortions (THD) of VSI output, when the range of variation of the vector angular velocity is predefined. Pulse signal generator unit generates a sequence of opening and closing signals to power switches according to SVPWM technique with symmetrical signals, which provides the minimum ratio of harmonic distortions due to symmetry of the arrangement of the pulse inside the 2-PWM periods. For testing the developed algorithms model of SVPWM is implemented in MATLAB/Simulink environment, which allows to evaluate the model in various modes. The modular structure of realization the algorithm and model enables fast procedures and functions realization in microcontroller. Simulation results and harmonic analysis of the output voltage of the inverter are given for assess the quality of the proposed algorithm implementation of SVPWM, which shows the reliable results of THD. The results of research are planned to implement in Vector Control systems for Induction and Permanent Magnet Synchronous Motor.