A Universal Simulation Method to Calculate Power Losses of IGBTs and Anti-Parallel Diodes

Abstract

In this paper, a universal loss calculation model in simulation is established in MATLAB / Simulink which can be used in not only ideal but also non-ideal conditions (non-sinusoidal load current and grid voltage, unfixed system parameters such as stator resistance for induction motors, unstable DC voltage with fluctuation, aperiodic modulation strategies with unfixed switching frequency, and so on). Considering the influence of dead time, steady operating states of each device can be obtained by the measurement of the load current and gate triggering pulses of every IGBT in a phase arm which can be easily measured in experiment rather than the currents and voltages of devices. Analyses in two-level topology and Neutral-Point-Clamped (NPC) three-level topology were done as examples. In periodic pulse width modulation with sinusoidal modulation wave, consistency among results from the proposed simulation model, the formula commonly used and commercially available loss software provided by power device manufacturer was shown. Through the design of a two-level inverter in hysteretic control, experimental verification of proposed method was applied. Calculating power loss in this method can be adapted to different converter topologies with various control strategies which is not even for ideal conditions. Nomenclature A Quadratic coefficient for quadratic polynomial fitting of switching loss and current according to the least-square method [mJ/A 2 ] B Monomial coefficient for quadratic polynomial fitting of switching loss and current according to the least-square method [mJ/A] C Constant term for quadratic polynomial fitting of switching loss and current according to the least-square method [mJ] E Power loss [W] f Frequency [Hz] () it Real-time current through the device [A] I Current amplitude [A] K Correction coefficient for junction temperature relative to the base junction temperature M Modulation ratio r Conduction resistance [  ] R Conduction resistance at the base junction temperature t Time[s] T Temperature [℃] () ut Real-time voltage of device [V] U Voltage amplitude [V]