Abb Oy

Jussi Suortti

Matti Laitinen

Tero Viitanen

Matti T Jussila

Ora Veli-Matti Leppänen

A method and an arrangement of measuring inverter current, where the inverter is connected to and supplied by a DC intermediate circuit having two or more parallel capacitor branches connected between the positive and negative rail of the DC intermediate circuit, and the capacitance of the capacitor branches being known. The method comprises the steps of measuring the current of one of the parallel capacitor branches, and determining from the measured current the magnitude of the inverter current.

Current measurement in an inverter unit and a frequency converter

A two-level or multi-level inverter are supplied with a positive auxiliary voltage (Ug+) and a negative auxiliary voltage (Ug&#x2212;). A bootstrap technique provides a first positive auxiliary voltage and a first negative auxiliary voltage from the supplied potentials. The bootstrap technique provides at least one additional negative auxiliary voltage to a switch driver of at least one semiconductor switch from the first negative auxiliary voltage. At the start up of an inverter, the inverter can perform a startup sequence to provide auxiliary voltages to the respective auxiliary voltage inputs of the switch drivers by turning the power semiconductors sequentially on and off.

Inverter

A method and a circuit for controlling a thyristor (V) into conducting state, the thyristor (V) being in a rectifier, which rectifier supplies DC voltage to a DC voltage circuit. The circuit comprising a trigger capacitor (C) adapted to be charged from the voltage difference across the thyristor (V) when the anode-to-cathode voltage of the thyristor is positive, a zener diode (V) adapted to be triggered with the voltage of the trigger capacitor (C), when the voltage of the trigger capacitor (C) exceeds the breakdown voltage of the zener diode (V), and an auxiliary thyristor (V) adapted to be triggered with the current from the trigger capacitor (C) flowing via the zener diode (V), wherein the cathode of the auxiliary thyristor (V) is connected to the gate of the thyristor (V) for triggering the thyristor (V) with the current from the trigger capacitor (C) flowing via the auxiliary thyristor (V) for using the thyristor (V) in a diode mode.

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Helsinki, Finland

Jussi Suortti