A Simple Method to Validate Power Loss in Medium Voltage SiC MOSFETs and Schottky Diodes Operating in a Three-Phase Inverter

Abstract

This paper presents an original method of power loss validation in medium-voltage SiC MOSFET (metal–oxide–semiconductor field-effect transistor) modules of a three-phase inverter. The base of this method is a correct description of the on-state performance of the diodes and the transistors in a PWM (pulse width modulation)-controlled inverter phase leg. Combined electro-thermal calculations are applied to precisely estimate the losses in the power devices and then, to find the suitable circuit parameters of a test circuit to emulate these conditions. A simple square-wave-controlled half-bridge with an inductive load enables the electrical and thermal stresses comparable to these in the inverter, and moreover, provided equations that confirmed the possibility of balancing the load between the diodes and the transistors. The circuit with 3.3 kV SiC MOSFETs was tested to verify the impact of selected parameters on power losses with the main focus on duty ratio. The same module was applied, in addition to an inductive load (3 × 112 μH) and two sets of DC-link capacitors (750 μF), to validate a phase leg of a 220 kVA inverter. In spite of a significantly apparent power, the active power delivered from the DC supply settled around 1 kW, which was enough to emulate 390 W of losses in two transistors and diodes.

A Bidirectional Grid-Connected DC–AC Converter for Autonomous and Intelligent Electricity Storage in the Residential Sector

“…The electrical waveforms were evaluated based on the topology and control strategies detailed in the previous section. The approach to the sizing of the converter was classical because the two stages taken separately are now well-known and mastered [36][37][38][39][40]. Of course, this approach is adaptable according to the targeted application and design constraints.…”

“…As shown in Figure 8, the main components to be sized were the power MOSFETs of both stages [36][37][38], the inductor of the DC-DC stage [39,40] and the output voltage modulation of the DC-DC stage [26].…”

Inverter Design and Droop Parallel Control Strategy Based on Virtual Impedance

“…The parallel system can operate normally only when the parallel inverter does not produce a circulating current and expected load current. The causes of circulating current are analyzed in this section to eliminate the ring current between inverters [26]. Figure 2 illustrates the equivalent circuit between the two inverters.…”