EP0113451B1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Inverter with a load circuit comprising a series resonant circuit and a discharge lamp
Assignee: Siemens AG
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Filing: 1983-12-12
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Granted: 1987-10-14
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Expires: 2003-12-12
Abstract
Abstract In an inverter controlled with a firing unit connected to switches and defining an operating frequency, a resonant frequency of a series oscillating circuit of the inverter connected to one of the switches is placed below this operating frequency. Given this operating situation, a short of the d.c. voltage source is impossible. Given, for example, unfavorable component tolerances, however, the operating frequency can be moved close to the resonant frequency and cause impermissibly high voltages at the components. Such a voltage rise is limited according to the invention by means of a voltage-dependent resistor. It preferably lies in series with a capacitor and takes care of a voltage-dependent shift of the resonant frequency.
Inventors
- 👤 Peter Krummel
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 01:39
CPC Classifications
H; H05; H05B; H05B41/00; H05B41/14; H05B41/26; H05B41/28; H05B41/295; H05B41/298; H05B41/2981; H05B41/2985; Y; Y10; Y10S; Y10S315/00; Y10S315/07
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
221 words
An inverter which serves to supply a discharge lamp (E) comprising heatable electrodes, each with two terminals, - with a load circuit which includes a series resonant circuit (L, C), a coupling capacitor (C1) and the heatable electrodes (e1, e2) of the discharge lamp (E) in a series arrangement, where the capacitor (C) of the series resonant circuit connects one terminal of each of the two electrodes (e1, e2) to one another, - with two alternatively conductive, controllable switches (V1, V2) of which one switch (V1) is parallel to the load circuit and the other switch (V2) is between the load circuit and a d.c. voltage source (H), - with a control set (S) which alternately drives the switches (V1, V2) at an operating frequency (f B ) which is above the resonance frequency (f o ) of the series resonant circuit when the discharge lamp is not ignited, characterised in that for the purpose of voltage limitation a voltage-dependent resistor (R1) is provided - which forms in series with a capacitor (C4), a parallel arm to an arm which contains the choke (L) or the capacitor (C) of the series resonant circuit and thereby - changes the resonance frequency (f o ) of the series resonant circuit (L, C) when the voltage-dependent resistor (R1) is operating in its current-conducting range.
Claim 2
Dependent Claim
221 words
An inverter which serves to supply a discharge lamp (E) comprising heatable electrodes, each with two terminals, - with a load circuit which includes a series resonant circuit (L, C), a coupling capacitor (C1) and the heatable electrodes (e1, e2) of the discharge lamp (E) in a series arrangement, where the capacitor (C) of the series resonant circuit connects one terminal of each of the two electrodes (e1, e2) to one another, - with two alternatively conductive, controllable switches (V1, V2) of which one switch (V1) is parallel to the load circuit and the other switch (V2) is between the load circuit and a d.c. voltage source (H), - with a control set (S) which alternately drives the switches (V1, V2) at an operating frequency (f B ) which is above the resonance frequency (f o ) of the series resonant circuit when the discharge lamp is not ignited, characterised in that for the purpose of voltage limitation a voltage-dependent resistor (R1) is provided - which forms in series with a capacitor (C4), a parallel arm to an arm which contains the choke (L) or the capacitor (C) of the series resonant circuit and thereby - changes the resonance frequency (f o ) of the series resonant circuit (L, C) when the voltage-dependent resistor (R1) is operating in its current-conducting range.
Claim 3
Dependent Claim
46 words
An inverter as claimed in Claim 1, characterised in that the parallel arm comprising the voltage-dependent resistor (R1) and the capacitor (C4) is connected parallel to the series arrangement of the choke (L) of the series resonant circuit and the second switch (V2) of the inverter.
Claim 4
Dependent Claim
35 words
An inverter as claimed in Claim 2, with a monitoring device which disconnects the inverter (W) in dependence upon the current, characterised in that the voltage connected to the capacitor (C4) controls the monitoring device.
Claim 5
Dependent Claim
62 words
An inverter as claimed in Claim 1, characterised by a design such that at the highest occurring operating frequency of the inverter the operating point of the voltage-dependent resistor (R2) always lies in the current-conducting range of the curve during the igniting operation of the discharge lamp, and lies in the currentless range of the curve only when the lamp has ignited.
Claim 6
Dependent Claim
44 words
An inverter as claimed in Claim 4, characterised in that the control set (S) contains a saturable transformer, from whose secondary windings (t2, t3) the control voltages for the switches (V1, V2) are derived, and whose primary winding (t1) lies in the load circuit.
References Cited (Backward Citations)
DE3112281A1
Cited
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