Electronic ballast and method for operating at least one discharge lamp

Abstract

The present invention relates to an electronic ballast for operating at least one discharge lamp (RL), comprising an input having a first (E1) and a second input connection (E2) for coupling to a DC supply voltage (UZw); an output having a first (A1) and a second output connection (A2) for coupling to the at least one discharge lamp (RL); an inverter (10) having a bridge circuit with at least one first (S2) and one second electronic switch (S1), and a control device (12) for actuating at least the first (S2) and the second electronic switch (S1) such that the first (S2) and the second electronic switches (S1) are alternately conductively connected with a first frequency (fR), wherein the first (S2) and the second switches (S1) are coupled in series between the first (E1) and the second input connections (E2), wherein the first electronic switch (S2) is coupled to the first input connection (E1) and the second electronic switch (S1) is coupled to the second input connection (E2), wherein a first bridge center point (HBM) is designed between the first (E2) and the second electronic switch (E1); a current measurement device (RS) for measuring the current (IS) at least by the second electronic switch (S1); a lamp choke (LR) that is serially coupled between the first bridge center point (HBM) and the first output connection (A1); at least one trapezoidal capacitor (Ct) that is coupled parallel to one of the two electronic switches (S1; S2); and at least one coupling capacitor (CC) for coupling the load; wherein the control device (12) is coupled to the current measurement device (RS) and designed to switch the second electronic switch (S1) to be conductive a) if a predeterminable negative threshold value (IThres) of the current is exceeded by the second electronic switch (S1) after switching off the first electronic switch (S2); or b) if the predeterminable negative threshold value (IThres) of the current (IS) is not exceeded by the second electronic switch (S1) after turning off the first electronic switch (S2), after a predeterminable period of time (ttimeout); wherein the control device (12) is designed to increase the first frequency (fR) in case b). The invention furthermore relates to a corresponding method for operating a discharge lamp (RL).

Description

Technical field [0001] The present invention relates to an electronic ballast for driving at least one discharge lamp, which has: an input terminal with first and second input interfaces for coupling with a DC power supply voltage; an output terminal, The output terminal has first and second output interfaces for coupling with at least one of the discharge lamps; an inverter, the inverter has a bridge circuit with at least one first and second electronic switch, and A control device for controlling at least the first and second electronic switches so that the first and second electronic switches are alternately turned on at a first frequency, wherein the first and second switches are coupled in series to the first and Between the second input interfaces, where the first electronic switch is coupled to the first input interface and the second electronic switch is coupled to the second input interface, wherein a first bridge midpoint is formed between the first and second electron...

AI Technical Summary

Problems solved by technology

However, this measure leads to increased reactive currents in the inverter and thus to undesirably large losses in the inverter

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