Uma proposta para a modelagem de inversores para o estudo de correntes de modo comum em sistemas de acionamento de motores

As far as PWM inverters are concerned, it is well known that the common-mode voltage generated during its normal operation produces high-frequency earth return currents which cause several problems in industrial electric systems. The computational study of such currents requires the appropriate modeling of the inverter, transformer, motor and cable for high-frequency phenomena studies. Regarding the inverter, it is usually modeled for this purpose by the inclusion of a capacitor to ground in order to represent the potential path of the common-mode currents. Since this representation is way too simple, this work presents a more detailed modeling of the inverter bridge, in which the capacitances of the switches collectors, DC link and clamping diodes (in the case of a three-level unit) are included. Once the representation of the whole bridge is not necessary, the proposed methodology reduces the amount of non-linear devices in the simulation, being thus attractive from the computational effort point of view.