WO1999034650A1 - Elektronisches vorschaltgerät - Google Patents

Elektronisches vorschaltgerät Download PDF

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Publication number
WO1999034650A1
WO1999034650A1 PCT/EP1998/007429 EP9807429W WO9934650A1 WO 1999034650 A1 WO1999034650 A1 WO 1999034650A1 EP 9807429 W EP9807429 W EP 9807429W WO 9934650 A1 WO9934650 A1 WO 9934650A1
Authority
WO
WIPO (PCT)
Prior art keywords
state
electronic ballast
control circuit
lamp
gas discharge
Prior art date
Application number
PCT/EP1998/007429
Other languages
German (de)
English (en)
French (fr)
Inventor
Norbert Primisser
Reinhard BÖCKLE
Stefan Koch
Stefan Rhyner
Original Assignee
Tridonic Bauelemente Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tridonic Bauelemente Gmbh filed Critical Tridonic Bauelemente Gmbh
Priority to AU17556/99A priority Critical patent/AU1755699A/en
Priority to DE59804841T priority patent/DE59804841D1/de
Priority to AT98962360T priority patent/ATE220849T1/de
Priority to EP98962360A priority patent/EP1040733B1/de
Publication of WO1999034650A1 publication Critical patent/WO1999034650A1/de

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
    • H05B41/14—Circuit arrangements
    • H05B41/26—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc
    • H05B41/28—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters
    • H05B41/295—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices and specially adapted for lamps with preheating electrodes, e.g. for fluorescent lamps
    • H05B41/298—Arrangements for protecting lamps or circuits against abnormal operating conditions
    • H05B41/2981—Arrangements for protecting lamps or circuits against abnormal operating conditions for protecting the circuit against abnormal operating conditions

Definitions

  • the present invention relates to an electronic ballast for operating gas discharge lamps according to the preamble of claim 1.
  • Such an electronic ballast is known for example from EP-Bl-0338 109.
  • Fig. 10 shows the basic structure of this electronic ballast.
  • the electronic ballast shown in FIG. 10 first comprises a circuit A which is connected to the AC network.
  • This circuit A serves as an RF harmonic filter for reducing the harmonic harmonics of the mains frequency and for radio interference suppression.
  • the circuit A is followed by a rectifier circuit B, which converts the mains voltage into a rectified intermediate voltage and supplies it to an inverter circuit D via a harmonic filter C, which serves to smooth the intermediate voltage.
  • This inverter D serves as a controllable AC voltage source and converts the DC voltage of the rectifier B into a variable AC voltage.
  • the inverter D generally comprises two controllable switches (not shown), for example MOS field-effect transistors. The two switches are connected in the form of a half-bridge circuit and are alternately controlled with the aid of a corresponding bridge driver such that one of the switches is switched on and the other is switched off.
  • the two inverter switches are connected in series between a supply voltage and ground, a load circuit or output circuit E in which a gas discharge lamp or fluorescent lamp G is arranged being connected to the common node between the two inverter switches.
  • This output circuit E comprises a series resonance circuit, via which the “chopped” high-frequency AC voltage of the inverter D is fed to the fluorescent lamp G.
  • the lamp electrodes of the fluorescent lamp G are preheated in order to extend the life of the lamp.
  • the preheating can be carried out, for example, with the aid of a heating transformer, the primary winding of which is connected to the series resonant circuit, while the secondary windings of the heating transformer are coupled to the individual lamp filaments. In this way it is possible to use the lamp filaments even in the ignited mode To supply energy.
  • the frequency of the alternating voltage supplied by the inverter D is changed in relation to the resonant frequency of the series resonant circuit of the output circuit E such that the voltage applied to the gas discharge lamp G does not cause the lamp to ignite.
  • the electronic ballast has a control circuit F, which monitors various circuit sizes of the electronic ballast and generates a corresponding control signal for the inverter D when a limit value is exceeded, in order to change the frequency of the alternating voltage generated by the inverter D depending on the detected fault .
  • control circuit F can monitor the lamp voltage, the preheating voltage, the lamp operating current, the impedance phase angle of the output circuit E or the DC voltage generated by the rectifier B and set the inverter frequency such that the lamp voltage, the preheating voltage or the lamp current have a predetermined limit value do not exceed, the direct current power taken from the rectifier B is as constant as possible or a capacitive operation of the series resonance output circuit E is avoided.
  • the function of the control circuit F is always the same regardless of the operating state of the gas discharge lamp G.
  • the individual detectors of the control circuit F are constantly activated and the measurement results of these individual detectors are continuously evaluated, although possibly related to the current operating state of the gas discharge lamp G some of these error or detector signals are of no interest at all or even incorrect reactions of the Lead control circuit F.
  • the occurrence of an increased voltage could lead to the electronic ballast being switched off, although the occurrence of an overvoltage during the ignition operation of the gas discharge lamp G is quite desirable.
  • the electronic ballast shown in FIG. 10 requires a relatively long time due to the constant monitoring of all possible error quantities until an operating point of the gas discharge lamp G that is as stable and error-free as possible has been reached.
  • the present invention is therefore based on the object of providing an electronic ballast of the type described at the beginning, in which the problems of the electronic ballast described at the beginning do not occur.
  • an electronic ballast is to be created which enables the gas discharge lamp (s) controlled by the electronic ballast to be reached more quickly and safely.
  • the control circuit of the electronic ballast controls the gas discharge lamp (s) connected to the electronic ballast in accordance with certain predetermined operating states, the control circuit only changing from a current operating state to a new operating state if one is monitored by the control switching line Status or monitoring variable of the electronic ballast or the gas discharge lamp (s) fulfills a certain condition associated with the current operating state.
  • the electronic ballast advantageously remains in the current operating state if the aforementioned condition is not met.
  • the monitoring variables of the electronic ballast monitored by the control circuit can be temporal variables, so that the control circuit monitors the expiry of predetermined time intervals. Furthermore, the monitoring variables monitored by the control circuit can determine certain operating parameters of the electronic ballast, such as the lamp voltage, the lamp current, etc., so that the presence or absence of certain fault conditions can be monitored and detected.
  • the type and number of the individual monitoring variables are advantageously dependent on the control gear depending on the current operating state supervised.
  • only those errors are monitored or evaluated in each operating state that are actually relevant for the respective operating state, so that the contradictions explained at the beginning with reference to FIG. 10 between the individual operating states on the one hand and error monitoring by the control circuitry on the other hand are avoided become.
  • the individual state variables of the electronic ballast are advantageously evaluated with the aid of so-called digital event filters, which ensure that a certain condition is only considered to be fulfilled if the corresponding state variable assumes a certain state several times in succession. For example, the existence of an overvoltage is only concluded if the lamp voltage exceeds a predetermined limit three times in succession. As soon as the monitored company size, i.e. in this case the lamp voltage, the given state, i.e. in this case the limit value, not reached, the corresponding counter of the digital event filter is reset.
  • Possible operating states of the electronic ballast or the gas discharge lamp include, for example, a commissioning state for the electronic ballast to settle, an ignition state for igniting the gas discharge lamp (s) connected to the electronic ballast, an operating state for operating the gas discharge lamp (s) after ignition, and an error state after a malfunction of the electronic ballast occurs in question.
  • Further possible operating states are a reset state (reset state) for initializing the electronic ballast when it is restarted or restarted, a preheating state for preheating the lamp filaments of the gas discharge lamp (s) or a lamp change detection state for recognizing the replacement of a gas discharge lamp.
  • the sequence control of the individual operating states of the control circuit of the electronic ballast is advantageously implemented digitally, so that the individual operating states are redefined in a simple manner or additional operating states can be added.
  • a change of state between two defined operating states is assigned at least one condition which must be fulfilled so that the control circuit changes operation from one operating state to the other operating state.
  • it is advantageously determined for each operating state which quantities of the electronic ballast or the gas discharge lamp (s) are monitored in the corresponding operating state or how the monitored quantities are evaluated in the corresponding operating state. In this way, the sequence control of the electronic ballast according to the present invention can be optimally adapted to the actual needs of the electronic ballast.
  • control circuit of the electronic ballast according to the invention can be designed in the form of an application-specific integrated circuit (Application Specific Integrated Circuit, ASIC).
  • ASIC Application Specific Integrated Circuit
  • control circuit of the electronic ballast can have inverter control means which generate control signals for the two inverter switches described at the outset, it being possible to switch between a symmetrical and asymmetrical duty cycle between the two control signals for the inverter switches depending on the operating state.
  • the control signals for the two inverter switches are output with an asymmetrical duty cycle, while in preheating or ignition mode, symmetrical control signals are used.
  • asymmetrical control signals for the inverter switches By generating asymmetrical control signals for the inverter switches, the so-called rattling of the gas discharge lamp (s) controlled by the electronic ballast can be avoided.
  • the resolution for the output frequency of the inverter can be increased with the aid of the inverter control means.
  • FIG. 1 shows a circuit diagram of a preferred exemplary embodiment of an electronic ballast according to the invention
  • FIG. 2 shows an enlarged illustration of a control gearshift shown in FIG. 1 with a corresponding external shading of this control gearshift
  • 3 shows a block diagram of the control circuit shown in FIG. 2
  • FIG. 4 shows a circuit diagram of a current detection block shown in FIG. 3,
  • FIGS. 3 and 4 show illustrations for explaining the capacitance current detection with the aid of the current detection block shown in FIGS. 3 and 4,
  • FIG. 6 shows a circuit diagram of a voltage detection block shown in FIG. 3,
  • FIGS. 7a and 78b show illustrations for explaining the lamp change detection with the aid of the voltage detection block shown in FIGS. 3 and 6,
  • FIG. 8a and 8b show circuit diagrams of a warm / cold start switching block shown in FIG. 3,
  • Fig. 10 shows a block diagram of a known electronic ballast
  • 11a to 11d show illustrations for explaining a further function of the voltage detection block shown in FIGS. 3 and 6.
  • the electronic ballast shown in FIG. 1 first comprises a circuit A, which is connected on the input side to a supply voltage, for example a mains voltage, and is used for radio interference suppression.
  • the circuit A is constructed in the usual way and includes, for example, capacitive input filters and, if necessary, harmonic chokes.
  • a capacitor C2 and a symmetry transformer L1 are shown only by way of example, it being possible for a surge arrester or a VDR with the designation F1 to be connected in parallel.
  • the circuit B following the circuit A comprises a full-wave rectifier bridge with diodes VI-V4.
  • the rectifier circuit B converts the supply AC voltage present on the input side into a rectified intermediate voltage.
  • the rectifier circuit B can therefore be omitted if the electronic ballast is operated with direct voltage.
  • the following Druckangteil C is used for harmonic filtering and smoothing the intermediate voltage supplied by the rectifier B.
  • the circuit C shown in FIG. 1 comprises, for example, capacitors C3, C1, a diode V5, a coil L2, a MOS field effect transistor T1 and a control circuit IC1 configured as an integrated circuit.
  • the control circuit IC1 is connected to a supply voltage potential VCC and can be connected to the other circuit elements in such a way that it receives different voltage potentials U or currents I.
  • VCC supply voltage potential
  • I currents
  • An inverter switching circuit D is driven by the harmonic filter C shown in FIG. 1, the essential elements of which are two controllable switches connected in series between a supply voltage line and ground, in the present example in the form of MOS field effect transistors T2 and T3.
  • the two inverter switches T2, T3 are connected to form a half bridge and are each controlled with the aid of a control circuit IC2 designed as an integrated circuit, i.e. opened and closed.
  • the control circuit IC2 thus also takes on the function of a bridge driver and is connected to or coupled to a corresponding supply voltage line VCC.
  • the inverter circuit D generates an AC voltage with a variable frequency and / or duty cycle depending on the rectified intermediate voltage generated by the rectifier circuit B.
  • the inverter D is constructed in the usual way and its function is sufficiently known, so that a further explanation can be dispensed with here. It is only important at this point that the control circuit IC2 controls the two inverter switches T2 and T3 alternately depending on the control signals supplied to them, so that a "chopped", high-frequency AC voltage occurs at the connection point between the two inverter switches T2 and T3.
  • a series resonance output circuit or load circuit E is connected to the inverter D.
  • the load circuit E is designed for the connection of two gas discharge lamps Gl, G2 in a tandem configuration.
  • the load circuit E can also be modified such that only one gas discharge lamp or more than two gas discharge lamps can be operated.
  • the load circuit E has a series resonance circuit consisting of a resonance circuit coil L3 and a resonance circuit capacitor C14.
  • This series resonant circuit or the resonant circuit coil L3 is connected to the connection point between the two inverter switches T2 and T3 and the resonant circuit capacitor C14 is arranged such that it is parallel to the operating gas discharge lamp or the gas discharge lamps G 1, G 2 to be operated.
  • the high-frequency AC voltage generated by the inverter D is supplied to the gas discharge lamps Gl and G2 via the series resonance circuit.
  • the two gas discharge lamps Gl and G2 are connected in a tandem configuration to the load circuit E or the electronic ballast.
  • the upper filament of the upper gas discharge lamp Gl and the lower filament of the lower gas discharge lamp G2 are connected directly to the load circuit E, while the lower filament of the upper gas discharge lamp Gl and the upper filament of the lower Gas discharge lamp G2 connected to each other and connected to the load circuit E.
  • a heat exchanger L4 is provided according to FIG.
  • the frequency of the alternating voltage supplied by the inverter E is set with respect to the resonant frequency of the series resonant circuit in such a way that the voltage across the resonant circuit capacitor C14 and thus across the gas discharge lamps Gl and G2 does not cause the gas discharge lamps to ignite.
  • an essentially constant preheating current flows through the filaments of the gas discharge lamps Gl, G2.
  • FIG. 1 adapts the preheating voltage in the tandem configuration of the gas discharge lamps Gl and G2 shown in FIG. 1.
  • the previously explained principle of preheating can of course also be transferred in a simple manner to the operation of a gas discharge lamp or more than two gas discharge lamps.
  • a parallel configuration or parallel connection of a plurality of gas discharge lamps Gl, G2 is also conceivable.
  • the tandem configuration of the gas discharge lamps Gl, G2 is shown, since in such a lamp configuration with the help of the electronic ballast shown in Fig. 1, a lamp change of both the upper and the lower gas discharge lamp can advantageously be determined in a simple manner.
  • the lamp change detection is explained in more detail below.
  • the frequency of the AC voltage supplied by the inverter D is in the vicinity of the resonance frequency of the Series resonant circuit shifted, whereby the voltage across the resonant circuit capacitor C14 and the gas discharge lamps Gl, G2 is increased, whereby these gas discharge lamps ignite.
  • the electronic ballast shown in FIG. 1 goes into the actual operating phase, in which the frequency of the alternating voltage supplied by the inverter D is continuously set, for example, such that the most constant lamp current flows or starts through the gas discharge lamps Gl, G2 the gas discharge lamps have as constant a lamp voltage as possible.
  • the electronic ballast shown in FIG. 1 goes into the actual operating phase, in which the frequency of the alternating voltage supplied by the inverter D is continuously set, for example, such that the most constant lamp current flows or starts through the gas discharge lamps Gl, G2 the gas discharge lamps have as constant a lamp voltage as possible.
  • the 1 has a number of error detectors which monitor specific switching variables of the electronic ballast, in particular the load circuit E, and trigger a corresponding control of the inverter D when a specific error is detected For example, to avoid the occurrence of an overvoltage on the gas discharge lamps G2 and G2, a rectification effect in the gas discharge lamps G1, G2 or a capacitive operation of the load circuit E.
  • a switching gear module is used to control the inverter D, which comprises the control switching gear IC2 already mentioned at the heart and several external components as the external switching gear of the control switching gear IC2.
  • the main external components are six resistors RIO, R13 - R16 and R21, R22 and two capacitors C7 and C17. As shown in Fig. 1, the individual external components are connected to respective input terminals of the control circuit IC2.
  • the external components connected to the control circuit IC2 serve primarily for the detection of certain switching variables of the electronic ballast, so that these can be evaluated in the control circuit IC2.
  • FIG. 2 shows an enlarged illustration of the control circuit IC2 shown in FIG. 1 and the external circuit of the individual input connections of the control circuit IC2. Only the essential connections and external components are shown in FIG. 2.
  • the control circuit IC2 is advantageously designed as an application-specific integrated circuit (Application Specific Integrated Circuit, ASIC) and accommodated in a multi-pole SMD housing (Surface Mounted Device).
  • ASIC Application Specific Integrated Circuit
  • the control circuit IC2 is suitable both for operating a single lamp output circuit E and for operating a load circuit E designed for a tandem configuration shown in FIG. 1 with a plurality of gas discharge lamps.
  • the control switching circuit IC2 has several connections which have the following functions.
  • connection GND The reference potential, ie the ground potential, for the individual analog and digital function blocks of the control circuit IC2 is applied to the connection GND. From Fig. 1 it can be seen that the ground potential of the entire electronic ballast is grounded via a coupling capacitor C1.
  • the internally generated supply voltage for the individual analog and digital function blocks of the control circuit IC2 is provided at the connection VDD, which is connected to the ground potential via the coupling capacitor C7 (cf. FIG. 1).
  • the connection NP serves, as will be explained in more detail below, for the external setting and detection of the preheating method, ie for the selection between a cold start and warm start operation.
  • the NP connection is connected externally in such a way that dynamic selection of the preheating method is possible.
  • the terminal VL1 detects the divided lamp voltage of the gas discharge lamps Gl, G2 via the resistors RIO and R14, R15 shown in FIG. 1 and partly in FIG. 2 and thus serves primarily for monitoring the lamp voltage.
  • the connection ILC is used with the help of the resistors R13 and R16 shown in FIG. 1 and partly in FIG. 2 for monitoring the output circuit or load circuit current (choke current) or for monitoring the lamp current flowing through the gas discharge lamps Gl, G2 after their ignition by using the shunt resistor R16 to detect a voltage proportional to it and to supply the control circuit via the connection ILC.
  • the connection VL1 thus serves for voltage monitoring, while the connection ILC serves for current monitoring.
  • the two output connections OUTL and OUTH serve to control the low-lying or high-lying half-bridge switch T3 and T2 shown in FIG. 1.
  • control signals (TTL level) for switching the two inverter switches T2 and T3 on and off are provided at the output connections OUTL and OUTH.
  • the connection VCC of the control circuit IC2 is finally the central supply voltage connection of the control circuit IC2.
  • the supply voltage range can include 10-18V, for example.
  • the control circuit IC2 controls the inverter switches T2 and T3 in such a way that an alternating voltage of variable frequency with an operating frequency range of, for example, 40-80 kHz is generated on the output side of the inverter circuit D.
  • the control circuit IC2 forms the heart of the entire electronic ballast shown in FIG. 1 and accordingly comprises a large number of different functions.
  • the preheating method can be controlled using the IC2 control switch be dynamically defined for the connected gas discharge lamp (s) and switched between a cold start and a warm start operation.
  • the control switch IC2 ensures a defined preheating operation with a defined preheating time and a defined preheating current.
  • the control circuit IC2 also ensures a predefined ignition operation with a defined ignition time and a defined ignition voltage.
  • the preheating current and the lamp operating current or the lamp voltage can be detected via the connections ILC or VL1 of the control circuit IC2 and regulated to a value that is as constant as possible.
  • the capacitive operation of the load circuit E is monitored by the control circuit IC2 via the current connection ILC.
  • the occurrence of a constant light effect in a connected gas discharge lamp Gl, G2 can also be detected via the voltage connection VLI.
  • the occurrence of a gas defect which leads to an overvoltage on the corresponding gas discharge lamp, can be detected with the aid of the voltage connection VLI, and the electronic ballast can accordingly be switched off in this case.
  • a special function of the control circuit IC2 is the detection of a lamp change, the lamp change detection in the tandem configuration shown in FIG. 1 being in particular independent of the changed lamp, ie both a change of the upper gas discharge lamp Gl and of the lower gas discharge lamp G2 can be detected.
  • a (preferably digitally implemented) sequence control is implemented in the control circuit IC2, which ensures that the gas discharge lamp (s) connected to the electronic ballast are controlled in accordance with predetermined operating states, whereby from one operating state to a new operating state only when fulfilled at least one specific condition can be changed.
  • operating state-dependent monitoring of certain variables of the electronic ballast is possible, so that different error variables can be monitored and evaluated differently depending on the respective operating state.
  • an event-filtered error evaluation is carried out in particular, ie with the help of digital event filters, for example, it is ensured that the existence of an error is only concluded if the corresponding error actually occurs several times in succession.
  • control switch IC2 has further functions, all of which will be explained in more detail below with reference to the accompanying drawing.
  • Fig. 3 shows a block diagram of the internal structure of the control circuit IC2 described above.
  • a module 100 is initially coupled to the power connection ILC, which is used, among other things, for the previously described current detection and capacitive current detection of the load circuit.
  • the evaluation of the current sensed via the connection ILC is carried out in particular with the aid of a regulator formed by a comparator circuit.
  • this comparator circuit is also fed and evaluated the voltage signal received by the voltage connection VLI of the control circuit IC2 and processed by a module 200.
  • the module 200 is used in particular for detecting the lamp voltage, for rectifying effect detection and for lamp change detection.
  • a further module 300 is coupled to the connection NP, which module is used to detect the warm or cold start operation when preheating the gas discharge lamp (s) to be controlled and to implement a dynamic preheating operation.
  • a voltage regulator module 400 is connected to the supply voltage connections VCC and VDD, which has an internal voltage regulator which provides a regulated, very precise voltage for the voltage supply of all internal function blocks.
  • Another module 500 serves as a source for all required reference quantities, ie reference voltages and reference currents, in the control circuit IC2.
  • An oscillator 600 serves as an internal clock generator of the control circuit IC2, a time base generator 700 coupled thereto deriving internal time variables for the sequence control of the control circuit IC2, such as the preheating or ignition time, depending on the predetermined clock of the oscillator 600.
  • Another module 800 is used to implement the sequence control of the individual operating states of the entire electronic ballast and interacts closely with another module 900, which is used for measuring phase control.
  • the module 900 is used in particular for event-filtered evaluation of certain error quantities of the electronic ballast and for the measurement phase-dependent control of all switches of the individual function blocks of the control circuit IC2.
  • the sequence controller 800 evaluates the event-filtered status messages from the measurement phase controller 900 and controls the individual operating states of the electronic ballast or the control switching circuit IC2 depending on the time variables specified by the time base generator 700.
  • the control circuit IC2 has a further module 1000 for controlling the inverter. With the aid of this module 1000, frequency setting signals supplied by the measuring phase control 900 are converted into corresponding control signals for the upper inverter switch (via the output connection OUTH) or the lower inverter switch (via the output connection OUTL).
  • the control circuit IC2 can comprise both analog and digitally implemented function blocks.
  • the digital part of the control switching circuit IC2 designed as ASIC comprises the time base generator 700, the sequence control 800, the measuring phase control 900 and the inverter control 1000.
  • the control circuit IC2 can be equipped in such a way that the digital part corresponds to the analog part in terms of the area required by the control circuit IC2.
  • FIG. 4 shows a detailed circuit diagram of the current detection module 100 shown in FIG. 3.
  • FIG. 4 also shows the resistors R13 and R16 which are connected externally to the current connection ILC of the control circuit and which are also shown in FIG. 1.
  • a reference current Irefl is added to the signal detected at the current connection ILC in order to ensure that the signal to be processed by the current detection module 100 is always in the operating voltage range of the control circuit.
  • an integrator circuit 105 is provided, which is used to integrate the input signal supplied to it.
  • the entire function block 105 is implemented in such a way that the integrator function can be used both for measuring the lamp current (via the ILC connection) in normal operation and for identifying rectification effects (via the VLI connection).
  • the integrator circuit 105 can have sample and hold elements which alternately sample the input signal of the integrator every period of the internal clock generator (cf. module 600 in FIG. 3). The charge thereby stored in the sample and hold elements is passed on to an integration amplifier of the integrator circuit 105. This process is repeated cyclically.
  • the integrator 105 can have an internal controllable switch which bridges the aforementioned sample and hold elements and is closed during the duration of the offset adjustment of the integrator 105. In this way, any signal, in particular the signal present at the input connection ILC, can be applied to the actual integration amplifier via the switch S105 or a reference voltage potential for rectifying effect detection from the voltage block 200 via the switch S107 during the initialization phase.
  • the actual integration amplifier of integrator 105 has the task of integrating the current measurement signal at the ILC connection in a time-controlled manner.
  • the switch S105 is closed, while in the case of the rectification effect evaluation the reference potential for the rectification effect evaluation supplied via the switch S107 is present at the integrator circuit 105.
  • a comparator 103 serves as the actual controller, which carries out the required setpoint / actual value comparison and is connected to the output of integrators 105.
  • the arrangement of this comparator 103 shown in FIG. 4 makes it possible to use the comparator 103 very flexibly.
  • reference voltages Vrefl-Vref ⁇ By actuating a switch S124 accordingly, different reference voltages or reference values can be connected or applied to the comparator 103, reference voltages Vrefl-Vref ⁇ being shown by way of example in FIG.
  • the reference potential Vrefl and Vref2 corresponds, for example, to a desired preheating voltage during a preheating operating state.
  • the reference voltage Vrefl or Vref2 is thus applied to the comparator 103 with the aid of the controllable switch S124, so that the measurement signal which is present at the ILC connection and is not integrated is compared with the reference value Vrefl or Vref2 respectively applied.
  • the reference potential Vref3 corresponds to the integration start value of the integration amplifier of the integrator 105, so that when this reference potential Vref3 is applied, the comparator 103 can detect the actual change in the integration result.
  • the reference potentials Vref4 or Vref ⁇ can correspond to a positive or negative limit value for the lamp voltage of the connection VLI that is supplied and integrated via the switch S107, so that, by comparison with these two limit values, the occurrence of a rectification effect in a positive or negative direction when the integration result is exceeded is reliable to be able to recognize.
  • the further reference potential Vref5 is also used, which is added during the rectification effect detection and corresponds to the output or start value for the integration of the lamp voltage supplied via the switch S107.
  • the start values of the integration amplifier of the integrator 105 given by the reference potentials Vref3 or Vref5
  • the change in the corresponding integration variable that is actually present relative to the corresponding start value can thus be determined with the aid of the comparator 103.
  • the output signal of the comparator 103 is fed to the measuring phase controller 900 shown in FIG. 3, which evaluates it and evaluates it differently depending on the current measuring phase.
  • the measurement phase controller 900 provides for a corresponding adaptation of the output frequency of the inverter of the electronic ballast if the current measurement signal of the connection ILC monitored by the comparator 103 deviates from the predetermined target value Vref3.
  • the measuring phase control generates an event-filtered signal which indicates whether there is a rectification effect in a connected gas discharge lamp or not. This signal is evaluated by the sequence control block 800 shown in FIG. 3 and used to control the operating state of the entire electronic ballast.
  • the measurement signal present at the connection ILC can also be monitored and evaluated bypassing the integrator circuit 105, e.g. to detect a capacitive operation of the load circuit of the electronic ballast.
  • a detector can be provided for detecting a capacitive current flowing in the load circuit, which for example detects the phase angle of the load circuit, i.e. the phase difference between the load circuit voltage and the load circuit current, determined (capacitive current detection).
  • the result of this monitoring or evaluation can also be fed to the measuring phase controller 900.
  • FIG. 5a shows an enlarged illustration of the essential elements of the inverter D already shown in FIG. 1 and of the load circuit E.
  • FIG. 5a assumes that only one gas discharge lamp Gl is connected to the load circuit.
  • 5a shows the two inverter switches T2 and T3 connected in series.
  • the load circuit with its series resonance circuit is connected to the connection point between the two inverter switches T2 and T3, i.e. the resonance circuit coil L3 is connected in parallel with the resonance circuit capacitor C14 to the lower inverter switch T3.
  • the resonant circuit capacitor C14 is also connected in parallel to the gas discharge lamp Gl.
  • Free-wheeling diodes VI 1 and V12 are connected in parallel to the individual inverter switches T2 and T3 and serve to protect the respective inverter switch.
  • 5b shows on the one hand the switch-on states of the two inverter switches T2 and T3 as well as the current profile of the current 1 ⁇ flowing through the choke L3 and the time profile of the current at the connection point between the two inverter switches T2 and T3 occurring voltage potential V L shown.
  • a current flows in the freewheeling diode of the inverter switch to be switched on and the inverter half bridge switches the resonant load circuit inductively, ie the voltage or potential V L leads the choke current I u .
  • the capacitive switching of the resonance load of the resonance load circuit is the capacitive switching of the resonance load of the resonance load circuit.
  • FIG. 5a shows the course of the individual currents I, -I 4 that occur during the time intervals t, -t 4 shown in FIG. 5b in the case of an inductive or capacitive inductor current I u .
  • the level of the current amplitude of the load circuit detected via the input ILC can now be monitored and compared with a predefined reference value.
  • the level of the current amplitude is advantageously recorded at the time when the lower inverter switch T3 is switched on, since in this case the polarities of the measured values to be recorded are favorable for processing within the control circuit IC2 designed as ASIC. If the detected current value is below the limit value specified by the corresponding reference potential, the presence of capacitive operation is inferred from the load circuit, and an output signal with a high level can be generated which is evaluated by the measurement phase control block 900 shown in FIG. 3 and finally by the inverter control block 1000, also shown in FIG.
  • FIG. 6 shows on the one hand the internal structure of the voltage detection block 200 and the external circuitry of the control circuitry coupled to the connection VLI of the voltage detection block 200.
  • a series resistor RIO is coupled on the one hand to the connection VLI and on the other hand to a voltage divider consisting of resistors R14 and R15, the two voltage divider resistors R14 and R15 being connected in parallel to the gas discharge lamp Gl and are connected to the gas discharge lamps Gl and G2 connected in tandem in FIG. 1.
  • FIG. 6 it is assumed in FIG. 6 that, in contrast to FIG. 1, only one gas discharge lamp G1 is driven, to which the resonant circuit capacitor C14 is also connected in parallel.
  • the two resistors R14 and R15 have the task of dividing down the voltage applied to the gas discharge lamp Gl so that a measuring signal representative of the lamp voltage can be supplied to the voltage terminal VLI of the voltage detection block 200 with the aid of the resistor RIO acting at the connection point between the resistors R14 and R15 .
  • the three external resistors RIO, R14 and R15 are advantageously variable, so that - analogously to the power connection ILC (cf. resistors R13, R16) - a connection of the control circuit completely independent of one another at different times includes a total of three different control variables of the electronic ballast Can be set or controlled using one and the same controller.
  • the setpoints for the control of the three different control variables can be set or predefined depending on the lamp type or the electronic ballast type currently being used.
  • the following variables of the electronic ballast can be set with the help of the three external variable resistors RIO, R14 and R15: the maximum lamp voltage positive / negative, the amplitude of the AC voltage component of the lamp voltage signal and the signal increase of the lamp voltage signal for rectification effect evaluation.
  • an internal reference current source is again provided, which applies an additional internal current Iref2 to the measurement signal present at the voltage connection VLI.
  • the reference current Iref2 is only activated, ie closed, using the controllable switch S207 during the evaluation of the rectification effect.
  • All other evaluations connected to the VLI connection relate to the signal present at the VLI connection without an additional reference current Iref2, ie without a DC offset. Accordingly, all other detectors at the VLI connection are deactivated during the rectification effect evaluation, since they would otherwise give incorrect results.
  • the rectification effect detection is to be explained in more detail with the help of the present control circuit.
  • gas discharge lamps due to the wear of the heating filament, have the effect at the end of the life of the gas discharge lamps that the lamp electrodes wear out unevenly over time, i.e. the removal of the emission layers on the lamp electrodes is different. Due to the different wear of the lamp electrodes, there are differences in the emissivity of the two lamp electrodes. The result of this is that a higher current flows from one lamp electrode to the other when the corresponding gas discharge lamp is operated than vice versa. The time course of the lamp current thus shows an increase in a half-wave.
  • the different removal of the two lamp electrodes thus creates asymmetries which not only lead to a stronger flickering of light at the end of the life of the gas discharge lamp, but even in extreme cases only allow the gas discharge lamp to be operated during one half-wave.
  • the gas discharge lamp acts like a rectifier, so that the effect described above is referred to as the "rectifying effect".
  • the previously explained rectification effect also has the consequence that the more worn electrode, which has a higher work function than the other electrode, heated up more than the other electrode when starting up the gas discharge lamp.
  • the work function is generally the minimum energy required to detach an electron from a metal, in the present case from a lamp electrode.
  • the heating of the lamp electrode described above can become so strong, in particular in the case of lamps with a small diameter, that parts of the lamp glass bulb can melt.
  • each controlled lamp is monitored for the occurrence of a rectification effect, so that a reaction can be made accordingly when a rectification effect is detected.
  • the actual rectification effect detection does not take place in the voltage detection block 200 shown in FIG. 6, but in the current detection block 100, since the integrator circuit of the current detection block 100 and the downstream comparator 103 (cf. FIG. 4) are also used for the rectification effect detection . In this way, the number of components required for monitoring the electronic ballast or the gas discharge lamp (s) can be reduced.
  • the switch S207 shown in FIG. 6 is advantageously closed some time before the expected zero crossing of the lamp voltage signal present at the connection VLI, so that transient processes caused by the capacitor C201 cannot additionally falsify the measurement signal.
  • Switch S201 is opened again exactly at the calculated zero crossing of the lamp voltage. That on the in Figs. 4 and 6
  • the switch S107 present signal corresponds to the AC voltage amplitade at the connection VLI, while the DC component of the signal present at switch S107 corresponds to the reference voltage Vref ⁇ which is switched on.
  • the measurement signal of the connection VLI prepared in this way is finally fed to the integrator circuit 105 shown in FIG. 4, as has already been explained above.
  • the switching state of the switch S107 is controlled by the measuring phase controller 900 shown in FIG. 3.
  • the individual switches shown in FIG. 4 are closed or opened by the measuring phase controller 900 in such a way that, with the aid of the comparator 103, an averaged expansion of the current measurement signal present at the ILC connection or of the voltage measurement signal present at the VLI connection is possible.
  • the comparator 103 can also be connected directly to the current measurement connection ILC, bypassing the integrator circuit, in order thus to evaluate or regulate the peak value of the current measurement signal at the connection ILC.
  • the measuring phase controller 900 specifies which of the measuring or Control states are assumed.
  • Rectifier effect detection principle provides that the lamp voltage detected via the voltage connection VLI is integrated with the aid of the integrator circuit of the current detection block 100 shown in FIG. 4, and then the deviation from a predetermined desired value is expanded.
  • the measurement signal corresponding to the lamp voltage is integrated over a full period or a multiple of a full period of the lamp voltage, and then the deviation of the integration result from the original integration start value is evaluated.
  • the comparator 103 is supplied with the integration start value by applying the corresponding reference potential Vref5.
  • the comparator 103 can also be given a positive limit value or a negative limit value for the rectification effect detection in the form of the further reference potentials Vref4 or Vref ⁇ .
  • the potential Vref5 can be, for example, 3.0V, while a value of 4.0V can be used as the positive reference potential Vref4 and a value of 2.0V can be used as the negative reference potential Vref ⁇ .
  • the output signal of the comparator shown in FIG. 4 again becomes the Measuring phase control 900 is supplied which, after detection of a rectification effect, outputs a corresponding status message or error message to the sequence control 800 shown in FIG. 3.
  • the measurement phase controller 900 carries out an event-filtered revision of this error message and ensures that an error message indicating the rectification effect is only output to the sequence controller 800 if the rectification effect occurs continuously over a long period of time.
  • the measuring phase controller 900 only outputs a rectification effect error message to the sequence controller 800 if a rectification effect is detected 32 times in succession every 255th period of the lamp voltage by the comparator 103 shown in FIG. 4. As soon as no rectification effect has been detected during a period of the lamp voltage, the counter of the measuring phase control 900 assigned to the rectification effect is reset to zero and the evaluation of the rectification effect error signal of the comparator 103 is started again.
  • the occurrence of a rectification effect is only taken into account in the operating state of the electronic ballast, since, for example, the occurrence of a rectification effect should not lead to the system being switched off during the preheating phase.
  • the rectification effect detection takes place in particular in that clock pulses of a (high-frequency) reference clock are counted and compared with one another during the individual half-waves of the lamp voltage or the quantity dependent thereon, the clock pulses counted as a function of the duration of the respective half-wave are. If there is no rectification effect, the clock pulses counted during the positive and negative half-waves match. In contrast, if there is a rectification effect, the clock pulses counted during the positive and negative half-waves differ from one another.
  • 11a shows an implementation of this embodiment in terms of switching technology with an up / down counter 107, which is a signal as the actual input signal UZERO and also receives as control signals a high-frequency reference clock signal CLK, for example with the frequency 10 MHz, and a reset or reset signal.
  • the signal UZERO assumes a positive and otherwise a negative voltage level during each positive half-wave of the lamp voltage present at the connection VLI and thus detects the zero crossing of the lamp voltage.
  • the counter 107 is started at the zero crossing of the lamp voltage and counts either up or down during the subsequent half-wave of the lamp voltage. If the measurement signal, ie the lamp voltage, reaches zero again after a half period, the counting direction of the counter 107 is reversed. After a full period of the lamp voltage has elapsed, the current counter reading N of the counter 103 is connected to a comparator, which can be formed, for example, by the comparator 103 already described above. This comparator 103 compares the current counter reading N with the initialization value or the original counter reading of the counter 107. If there is no rectification effect, the counter reading N must have reached the output value N 0 again after the next zero crossing of the lamp voltage.
  • the comparator 103 advantageously compares the counter reading N with the initial value N 0 within certain tolerance limits, in order not to prematurely conclude that there is a rectification effect.
  • the output signal of the comparator 103 is fed via a D-flip-flop 108 clocked by a latch signal to the measuring phase controller 900, which - as has been described above - evaluates this signal and in particular carries out an event-filtered evaluation, ie only then concludes that there is a rectification effect , if, for example, a rectification effect is reported by the comparator 103 32 times in succession every 255th period of the lamp voltage.
  • the zero crossing signal UZERO can originate, for example, from a further comparator 203, which monitors the voltage measuring signal present at the voltage connection VLI with regard to its zero crossing.
  • the entire integrated measuring system of the control circuit IC2 is synchronized cyclically with respect to the zero point of the lamp voltage.
  • the synchronization advantageously takes place every second period of the output frequency.
  • An exception to this principle is the rectification effect evaluation. In this case, the synchronization is delayed by two further periods over a full period of the lamp voltage due to the integration carried out for the rectification effect evaluation.
  • the output signal of the Zero crossing comparator 203 is also fed to measuring phase controller 900 and is of central importance for the control of all controllable switches of the entire control circuit, the actuation of which is controlled in each case to the zero crossing of the lamp voltage.
  • Fig. 11b shows a representation of the signal curves in the circuit shown in Fig. 11a in the absence of a rectification effect and the conditions that occur.
  • the zero crossing signal UZERO assumes the positive level during the positive half-wave of the lamp voltage U VL ⁇ and the counter 107 decreases its counter reading N based on the initialization value NO according to the reference clock CLK until a new zero crossing of the lamp voltage U VL1 is present. The counter reading N is then increased again.
  • the latch signal After a period of the lamp voltage U VL ⁇ , the latch signal outputs the output value of the comparator 103 via the D flip-flop 108 to the measuring phase controller 900 and then the counter 107 is reset to the initial value N 0 using the reset signal.
  • the counter reading N of the counter 107 corresponds to the output value N 0 again , so that the comparator 103 does not report a rectification effect.
  • 11c and 11d show courses of the counter reading N if there is a rectifying effect, the counter reading N being greater than N 0 according to FIG. 11c or smaller than N 0 according to FIG. 11d after a full period of the lamp voltage U VL1 and thus the comparator 103 recognizes and reports the rectification effect by comparing N with N 0 .
  • the comparator N is advantageously compared within predetermined tolerance limits, which are defined by threshold values N S1 and N s2 in accordance with FIG. 11D, that is to say the comparator 103 only outputs an output signal corresponding to the rectification effect if the following condition is not fulfilled: N S2 ⁇ N ⁇ N S1 .
  • the threshold values are advantageously selected asymmetrically in such a way that the distance between N S1 and N 0 is greater than the distance between N 0 and N S2 (in particular twice as large), since the control behavior of the electronic ballast occurs when the rectification effect shown in FIG always tries to compensate for the associated decrease in current by changing the frequency.
  • the sensitivity for the rectification effect detection at counter readings N which after a full period of the lamp voltage U V ⁇ below the Output value N 0 , increased and the threshold value N S2 shifted closer to the output value N 0 .
  • a further function block for overvoltage detection of the lamp voltage can be connected to the voltage connection VLI (cf. the arrow shown in FIG. 6), the output signal of this function block also being able to be fed to the measuring phase control 900 and, for example, in turn event-filtered (cf. the rectifying effect evaluation explained above) leads to a corresponding error message to the sequencer 800.
  • the voltage detection block 200 shown in FIG. 6 comprises a further function block which is provided for the detection of a lamp change.
  • This functional block comprises a sampling circuit 201, a switch S206 and a comparator 202.
  • This lamp change detection circuit enables the detection of a change in both the upper gas discharge lamp Gl shown in FIG. 1 and the lower gas discharge lamp G2.
  • This lamp change detection circuit enables the detection of a change in both the upper gas discharge lamp Gl shown in FIG. 1 and the lower gas discharge lamp G2.
  • the present lamp change detection circuit With the help of the present lamp change detection circuit, it is now possible to detect the change of any gas discharge lamp Gl, G2 connected to the electronic ballast. As soon as a lamp change has been recognized, this is communicated via the measuring phase controller 900 shown in FIG. 3 to the sequence controller 800 also shown schematically in FIG. 3, so that it can automatically restart the system after notification of a lamp change.
  • a lamp change is particularly considered if a lamp error, such as a gas defect, has been determined and reported by the control circuit. In this case, the installer will try to replace the faulty lamp. First knows the fitter does not know which of the gas discharge lamps Gl, G2 connected to the electronic ballast is faulty. He will therefore replace one of these connected gas discharge lamps. As soon as the
  • the sequence control 800 shown in FIG. 3 will restart the system. If a lamp fault is still detected or all the connected gas discharge lamps cannot be ignited, the control circuit switches back to an error or lamp change detection state without the connected gas discharge lamps being able to be operated continuously. For the fitter, this means that the gas discharge lamp that he replaced was either not defective or that another defective gas discharge lamp exists. In this case, the fitter has to replace another gas discharge lamp connected to the electronic ballast.
  • a lamp change is recognized in that a supply voltage of a certain frequency is applied to the load circuit by the inverter and the transient response of the load circuit is evaluated in this regard.
  • the transient response of the load circuit is in turn assessed on the basis of the measurement signal present at the voltage connection VLI and proportional to the lamp voltage, this measurement signal being sampled several times and thus the characteristic curve of the lamp voltage resulting from the applied supply voltage being assessed.
  • the supply voltage applied to the load circuit in lamp change detection mode has, in particular, a relatively low frequency of, for example, 40 Hz.
  • only one of the two inverter switches T2, T3 (cf. FIG. 1) is switched on or off alternately with the aforementioned frequency in the lamp change detection mode, while the other inverter switch remains permanently open during the lamp change mode.
  • it is the upper inverter switch T2 that is permanently open, while the lower inverter switch T3 is alternately switched on and off with the low repetition frequency of approximately 40 Hz.
  • the function of the lamp change detection circuit shown in Fig. 6 is as follows.
  • the lower inverter switch T3 of the inverter D shown in FIG. 1 is switched on and off with a low repetition frequency of approximately 40 Hz, while the upper inverter switch T2 remains permanently switched off. Because the inverter switch T3 is switched on and off, there is a certain transient response in the load circuit of the electronic ballast, which depends in particular on the gas discharge lamps connected to the electronic ballast. This transient response of the load circuit is reflected in the measurement signal detected via the input connection VLI, which is evaluated by the lamp change detection circuit.
  • the sampling circuit 201 stores the current voltage value of the measurement signal present at the connection VLI at certain times T r T 3 .
  • the third measurement at time T 3 is not absolutely necessary, but it does increase the reliability of the measurement against interference. The measurement process described above takes place after the inverter switch T3 has been opened and before it has been closed again.
  • the result is temporarily stored in the downstream digital part (not shown in FIG. 6).
  • the lamp change detection circuit is then reinitialized, ie a specific reference voltage Vrefl 1 is switched on via the switch S206 and a new sample value of the voltage signal at the connection VLI is temporarily stored in the sampling circuit 201.
  • the comparator 202 thus carries out a double relative evaluation of the sample values stored in the sampling circuit 201, that is to say the difference between the sample value stored at the point in time ⁇ and the sample value stored at the point in time T 2 and the difference between the sample at the point in time T 2 Sample value and the sample value stored at time T 3 .
  • This evaluation of the relative relationships between the individual sample values is advantageous compared to the evaluation of absolute measured variables, since additional components would be required to evaluate absolute measured variables.
  • FIG. 7a shows a time diagram of the profile of the voltage U VL1 present at the connection VLI, the switching state of the inverter switch T3 and the Switching state of the switch S206 shown in FIG. 6. Furthermore, the individual sampling times T ,, T 2 and T 3 are indicated in FIG. 7a.
  • the evaluation of the comparison result provided by the comparator 202 between the samples at the times T, and T 2 or T, and T 3 takes place in the measuring phase controller 900.
  • the transient process that is to say on the basis of the values obtained by the samples at the times T [- T 3 formed voltage characteristic, it can be decided whether one of the gas discharge lamps has been removed during the lamp change detection operation and, if so, which of the gas discharge lamps has been removed. Furthermore, it can be assessed whether instead all lamp filaments of the individual gas discharge lamps are correctly connected to the load circuit, ie all lamps are connected without errors.
  • 7b shows an example of the characteristic curve of the voltage signal U VL1 present at the connection VLI for three different cases.
  • the characteristic curve a corresponds to the characteristic curve which arises when the upper gas discharge lamp Gl shown in FIG. 1 changes.
  • the characteristic curve b corresponds to the characteristic curve when changing the lower gas discharge lamp G2 during the lamp change detection operation.
  • the third characteristic curve c shown in FIG. 7b corresponds to the characteristic curve in normal operation without a lamp change, ie in the event that all lamps are connected.
  • control circuit IC2 will monitor the transient behavior with regard to the occurrence of the characteristic curves a or b when a lamp fault occurs in an error state. As soon as the voltage at the connection VLI runs in accordance with one of these characteristics, this means that one of the connected gas discharge lamps has been removed from its version for troubleshooting.
  • the control switching circuit IC2 or sequence control 800 then changes into the actual lamp change detection state, in which, as in the fault state, only the lower inverter switch T3 is opened and closed, for example at 40 Hz, while the upper inverter switch T2 is permanently open.
  • control circuit IC2 waits for the appearance of the characteristic curve c, ie that instead of the removed lamp a replacement lamp has been inserted and now all lamps are reconnected. The system then restarts or restarts. This process will be explained again later with reference to FIG. 9.
  • FIG. 8a and 8b show two variants of the circuit 300 shown in FIG. 3 for detecting a warm / cold start operation. Both variants have in common that the voltage potential present at the connection NP of the control circuit is always evaluated and it is determined by comparison with a predetermined reference voltage Vrefl 2 whether a warm or cold start is to be carried out. This comparison is carried out with the aid of a comparator 301, the positive measuring input of which is connected to the connection NP. On the output side, the comparator 301 is connected to a state hold circuit 302, which can be implemented, for example, by a D flip-flop. This state hold circuit 302 has the effect that the output signal of the comparator 301 is only switched through and evaluated to the sequence control 800 if a corresponding enable signal EN is present.
  • This enable signal EN only briefly assumes a high level when the entire system is restarted or restarted, for example by actuating a corresponding mains switch. At no later point in time does a signal change at the NP port result in a state change at the output port of the state hold circuit 302.
  • FIG. 8b shows a variant of the circuit explained above, which enables a dynamic changeover between a warm and cold start operation.
  • the in Fig. 8b The circuit shown corresponds essentially to the circuit shown in FIG. 8a, but with the exception that a switch S301 is provided internally at the input terminal NP, via which the supply voltage potential VDD can be applied to the input terminal NP, while externally to the terminal NP RC element consisting of the resistor R22 and capacitor C17 already shown in FIGS. 1 and 2 is connected.
  • the voltage potential present at the input connection NP is monitored by the comparator 301.
  • the function of the circuit shown in Fig. 8b is as follows.
  • the switch S301 is closed so that the capacitor C17 is charged by the supply voltage potential VDD applied to the input terminal NP. If the system is switched off (e.g. due to a fault) or the system supply is switched from mains to emergency power operation, switch S301 is opened and capacitor C17 discharges with the time constant defined by the RC element.
  • the RC element is advantageously designed such that the capacitor C17 can hold the charge so long that the voltage applied to the input connection NP is greater than the reference voltage Vrefl2 applied to the comparator 301 for up to 400 ms.
  • the enable signal EN of the state hold circuit 302 assumes a high level, so that the comparison result of the comparator 301 is switched through. If, at this point in time, the voltage potential present at the input connection NP is still greater than the reference voltage Vrefl2, the sequence control 800 ensures the start-up of the connected gas discharge lamps without preheating operation and thus carries out a cold start. If, on the other hand, the voltage potential present at the input connection NP is less than the reference potential Vrefl2, the connected gas discharge lamps are preheated and a warm start is thus carried out.
  • the voltage potential present at the input connection NP of the control circuit depends on the on-time of the switch S301, which is equivalent to the operating time of the electronic ballast. This variable is decisive for the state of charge of the capacitor C17. Furthermore, the voltage potential at the input connection NP depends on the switch-off time of the switch S301 or the duration of the emergency power operation of the electronic ballast and the time constant of the RC element. These variables are decisive for the discharge process of the capacitor C17.
  • the circuit shown in FIG. 8b therefore performs a cold or warm start depending on the duration of the switch-off time and on the time constant of the RC element.
  • the switch-off time period can be specified which is just sufficient for a cold start operation of the connected lamps.
  • the RC element only has to be dimensioned such that after charging the capacitor C17 and opening the switch S301, the voltage potential applied to the input terminal NP is greater than the reference potential Vrefl2 of the comparator 301 just after the aforementioned switch-off period has elapsed.
  • the maximum permissible time between switching to emergency power operation and restarting or restarting the electronic ballast without preheating the lamp electrodes is set to 400 ms. Accordingly, the resistor R22 and the capacitor C17 are to be dimensioned in such a way that the aforementioned period of 400 ms can be observed.
  • any other energy storage circuit can be used, which stores energy depending on the supply voltage potential present at the input terminal NP and discharges with a certain time constant after the supply voltage potential has been disconnected .
  • This energy storage circuit can thus contain any delay elements, as long as a defined and known temporal behavior of the delay element or the energy storage circuit is given.
  • the function blocks 400 and 500 shown in FIG. 3 will be explained in more detail below.
  • the voltage regulator function block 400 generates an internally regulated, very precise supply voltage VDD for all internal function blocks, which at the same time represents the source for all required reference voltages.
  • this internal supply voltage VDD is applied to the outside via the connection VDD and filtered via the external capacitor C7 with good high-frequency properties. Due to the provision of the internal supply voltage VDD, a single low-voltage level can be used for all functional parts of the entire electronic ballast, which is particularly advantageous for cost reasons.
  • the reference voltage generator 500 is used for the central generation of all reference variables for the control circuit IC2, ie for the generation of all reference potentials and reference currents.
  • the oscillator 600 shown in FIG. 3 represents the central clock source for the entire control circuit IC2.
  • the oscillator 600 is constructed in such a way that no external components are required.
  • the basic clock of the oscillator is set with the help of micro fuses to the desired value of, for example, 10 MHz with an accuracy of z. B. 4-bit matched.
  • the frequency of the clock generator can be reduced to approximately 1/20 of the nominal clock rate, ie to approximately 550 kHz, via a digital input of the oscillator 600.
  • the time base generator 700 likewise shown in FIG. 3 generates a plurality of constant time intervals which are supplied to the individual function blocks of the control circuit IC2 via digital outputs of the time base generator 700.
  • the sequence control function block 800 receives, for example, all the time reference quantities from the time base generator 700. All the time quantities generated by the time base generator 700 are a multiple of the basic clock of the oscillator 600.
  • the time reference quantities generated by the time base generator 700 can include, for example, the individual preheating times or the ignition time. As will be explained in more detail below, these temporal reference variables are particularly important for the temporal operating state control of the control circuit IC2, which is carried out by the sequence control function block 800.
  • sequence controller 800 The function of the sequence controller 800 will be explained in more detail below with reference to FIG. 9.
  • the sequence control function block 800 controls the operation of the electronic ballast, for example in accordance with the state diagram shown in FIG. 9. 9, each possible operating state is illustrated by a circle, while the individual arrows represent possible changes in state which occur when a condition associated with the two operating states is met. These conditions are in each case linked to specific states of certain state or monitoring variables of the electronic ballast or the lamp (s), these monitoring variables being processed internally by the sequence control 800 in the form of variables which depend on whether the monitoring variable assumes the corresponding state or not, for example assumes the value "1" when the assigned state is taken or "0" when the state is not taken.
  • the individual variables monitored by the sequencer 800 can, for example include time-based variables or error variables.
  • the course of a commissioning time, a preheating time, an ignition time or a delay time for the rectification effect detection can be monitored.
  • the error quantities for example, the occurrence of a capacitive current in the load circuit (via the current detection block 100), the presence of an overvoltage at the connected gas discharge lamp, the occurrence of a rectification effect or asymmetrical lamp operation, the absence of a lamp or the occurrence of a synchronization error with regard to the zero crossing the lamp voltage (in each case via the voltage detection block 200) are monitored.
  • the output signal of the function block 300 can be monitored, with the aid of which a distinction can be made between a warm and a cold start operation. Any other monitoring parameters of the electronic ballast are of course also conceivable.
  • the individual error quantities are detected by the blocks 100-300 shown in FIG. 3, but processing is first carried out by the measurement phase control function block 900 before the individual error quantities are actually evaluated by the sequence control 800.
  • the measuring phase control contains a digital event filter assigned to the corresponding error size for each monitored error size.
  • this digital event filter performs the function of a counter which counts the uninterrupted occurrence of the corresponding error.
  • An error message is only passed on to the sequence control 800 by the corresponding event filter when the corresponding error has occurred n times in succession, where n corresponds to the filter depth of the corresponding digital event filter and can be different for each error size.
  • the counter status of the digital event filter is reset and the counting process starts again from the beginning. This ensures that the sequencer 800 does not react prematurely to the occurrence of a specific error, and an operating state change as a result of a specific error message is only carried out when it can be assumed with a relatively high degree of certainty that the corresponding error actually exists.
  • a special feature in this regard is the digital event filter for the rectification effect detection, since the rectification effect is a gradual, that is, slowly occurring, error.
  • the event filter assigned to the rectification effect is therefore dimensioned in such a way that only when a The rectification effect is closed and a corresponding error message is output to the sequence control 800 if the measurement phase control 900 is notified of a rectification effect 32 times in succession every 255th period of the lamp voltage.
  • a filter depth of 64 can be used for the detection of a capacitive current, a filter depth of 3 for the detection of an overvoltage and one for the detection of a synchronization error and for the lamp change detection Filter depth of 7 can be provided.
  • filter depth values are also conceivable.
  • the corresponding error message from the measurement phase control 900 to the sequence control 800 after passing through the correspondingly assigned event filter is meant.
  • the initial state of the operating state control shown in FIG. 9 is the so-called. Reset state (state I).
  • the system is in state I whenever the electronic ballast has been started or restarted, which is synonymous with the occurrence of the enable signal EN explained with reference to FIG. 8.
  • the sequencer 800 may include a hysteresis comparator that monitors the external supply voltage signal VCC within certain limits and generates the enable signal EN if the supply voltage signal VC is within the required range
  • the comparator also monitors the switching on and off of the entire system.
  • the enable signal EN can thus occur asynchronously to all other signals depending on the switching on and off of the overall system, whereby after the enable signal EN has occurred, ie after being switched on or off.
  • the electronic ballast is switched on again and the individual function blocks of the control circuit IC2 are compared. This comparison is carried out by reading in the respective values for the individual micro fuses. These micro fuses are small fuses that are used, for example, to balance the individual internal power sources. Furthermore, as has been explained with reference to FIG. 8, when the enable signal EN occurs, the output signal of the function block 300 shown in FIG.
  • state I the control circuit IC2 is thus initialized.
  • the sequential control unit 800 automatically goes into a commissioning state (state II). Exceptionally, the transition from state I to state II is not linked to certain conditions and takes place automatically each time the electronic ballast is restarted or restarted.
  • state II the harmonic filter starts up or the load circuit of the electronic ballast settles. Furthermore, the coupling capacitor of the load circuit is precharged in state II. In this phase, all error detectors are deactivated, ie there is no evaluation of the error variables mentioned above.
  • a preheating condition III is started from condition II if e.g. a start-up time assigned to state II, which denotes the normal operating time of state II, has expired and no cold start operation has been reported by function block 300 shown in FIG. 3. If, on the other hand, the start-up time has not yet expired, the system remains in state II, which is shown in FIG. 9 by an arrow starting from state II and returning to state II. If a cold start operation was detected by the function block 300 and the start-up time has already expired, the sequence control 800 changes directly from the state II to an ignition state IV, which corresponds to the previously explained warm start operation.
  • the inverter half bridge is driven in such a way that it oscillates at the upper limit in terms of frequency and generates, for example, an output frequency of approximately 80 kHz.
  • the preheating control, the overvoltage detection and the capacitive current detection can be activated.
  • the working frequency of the inverter of the electronic ballast can be changed depending on the value of the lamp current detected and the states of the overvoltage and capacitive current detection.
  • the load circuit is attempted with the help of the control variable "lamp current" to first reduce the output frequency of the inverter, since the detected lamp current is significantly too small compared to the specified setpoint due to the fact that the ignition has not yet taken place.
  • This control process is continued until the overvoltage detection or capacitive current detection Continuous reduction of the inverter frequency is prevented or counteracts this.
  • the overvoltage detection will become dominant as an influencing factor.
  • the lamp voltage is regulated, as it were. This behavior changes until the lamp is ignited or until it expires
  • the gas discharge lamp will ignite before the specified ignition time has expired, in which case the lamp current control becomes dominant again and the output frequency of the inverter thus is reduced long until the stable operating point specified by the lamp current reference value has been reached.
  • the capacitive current detection will only actively intervene in the ignition process in the ignition state IV in the event of a fault, for example when the resonant circuit reactor L3 shown in FIG. 1 is saturated.
  • the ignition state IV can only be left in the direction of the previously mentioned operating state V after the specified ignition time has elapsed. This change of state is in particular independent of whether control in the ignition state IV is still based on the ignition voltage or is already based on the lamp current.
  • the mean or effective value of the lamp current is regulated, ie the output frequency of the inverter is dependent on the detected lamp current.
  • Overvoltage, capacitive current and synchronization error detection is activated during this operating state V, and during this state too the control circuit performs a new setpoint / actual value comparison only every second period of the inverter output frequency.
  • the rectification effect detection GLRE
  • the operating state V is not limited in time, ie in principle represents an endless loop, and can only be exited when one of the activated error detectors responds.
  • all fault detectors of the control circuit are activated during operating state V.
  • fault state VII shown in FIG. 9 is started up.
  • This fault condition VII is therefore the central point of contact for all serious operational disturbances.
  • Fault state VII is jumped on directly from preheating state III if an overvoltage or a capacitive current operation has been detected during these preheating states.
  • the fault state VII is started from the operating state V if a capacitive current operation, an overvoltage fault, a synchronization fault and / or the occurrence of a rectification effect etc. with respect to the connected gas discharge lamps has been detected during this state.
  • the start-up of the fault state VII can, for example, be associated with a corresponding signaling of the respective fault for the user.
  • Fault status VII is only exited by the sequential control system if, after restarting the system, start-up status II is restarted via reset status I and the gas discharge lamps are started up again.
  • error state VII can be left if it is detected in this state that not all of the lamps connected to the electronic ballast have intact lamp filaments. This is equivalent to leaving the fault state VII in the direction of the lamp change detection state VIII already mentioned as soon as one of the connected gas discharge lamps is removed from its socket.
  • the operating current consumption of the control circuit is reduced to a minimum possible value during the fault state VII.
  • the electronic ballast is operated as in the lamp change detection state, ie the lower inverter switch T3 is opened and closed with a low frequency of, for example, 40 Hz, while the upper inverter switch is permanently open.
  • the control switching circuit IC2 waits in the error state VII for the occurrence of the voltage characteristic curves a or b (cf. FIG. 7a) Voltage measurement connection VLI, which corresponds to the removal of one of the connected gas discharge lamps Gl, G2. In this case, the control circuit IC2 changes to the lamp change detection state VIII.
  • the control circuit can reliably detect both a change or a removal of the upper gas discharge lamp Gl and the lower gas discharge lamp G2 (cf. FIG. 1) and automatically restart the system after detecting a lamp change.
  • the lamp change detection state VIII monitors whether all the gas discharge lamps have been inserted. Once it is recognized that all gas discharge lamps have been inserted, i.e. all lamp filaments connected to the electronic ballast are intact, the system is automatically switched back to commissioning state II and the gas discharge lamps are put into operation again in accordance with the functional circuit shown in FIG. 9. Even during the
  • Lamp change detection status VIII with the exception of lamp change detection, all other fault detectors are deactivated.
  • the inverter control function block 1000 is used to generate control signals for the upper and lower inverter switches T2, T3 (see FIG. 1), which are output via the output connections OUTH or OUTL of the control circuit. Depending on these control signals, the two inverter switches are either switched on or opened. As a rule, the inverter control 1000 generates alternating control pulses for the control connections OUTH and OUTL of the two inverter switches T2 and T3 and can furthermore have an internal dead time counter function in order to ensure a sufficient dead time between the activation of the two inverter switches. In lamp change detection state VIII (see FIG.
  • the inverter control 1000 ensures that the upper inverter switch T2 remains permanently open via the upper output connection OUTH, while only the lower inverter switch T3 alternately opens and closes with a relatively low frequency via the lower output connection OUTL becomes.
  • the inverter control 1000 provides in particular for an asymmetrical duty cycle of the inverter switches, but this asymmetry is only 2.1% for an output frequency of the inverter of 43 kHz, for example, and only 4% for an output frequency of 80 kHz, and is therefore hardly significant.
  • the generation of asymmetrical output signals for the two inverter switches leads to an increase in the frequency resolution of the inverter, ie with the help of the control circuit, smaller frequency steps of the inverter can be set.
  • the generation of an asymmetrical duty cycle also has the effect that the so-called. "Walmen" of the connected gas discharge lamps can be changed.
  • This Walmen is an effect of "running layers", which occurs especially at low temperatures shortly after the start of the system, which is due to an uneven light distribution in the corresponding gas discharge lamp.
  • These "running layers” consist of light / dark zones which run along the lamp tube at a certain speed.
  • this running effect can be accelerated by superimposing a small direct current so that it
  • the generation of an asymmetrical pulse duty factor by the present control circuit of the electronic ballast can also counteract the occurrence of the so-called "whining".
  • an asymmetrical duty cycle for the two inverter switches is generated during individual half-periods, although the duty cycle is averaged over an entire period. Since only asymmetrical output signals are to be generated in the operating state V shown in FIG. 9, the inverter control 1000 evaluates, for example, a corresponding control signal which only releases the asymmetrical operation (for example by assuming a high level) if the system is in the operating state V is located.

Landscapes

  • Circuit Arrangements For Discharge Lamps (AREA)
  • Mechanical Treatment Of Semiconductor (AREA)
  • Glass Compositions (AREA)
  • Furan Compounds (AREA)
  • Non-Portable Lighting Devices Or Systems Thereof (AREA)
  • Organic Insulating Materials (AREA)
  • Discharge Heating (AREA)
  • Non-Silver Salt Photosensitive Materials And Non-Silver Salt Photography (AREA)
PCT/EP1998/007429 1997-12-23 1998-11-19 Elektronisches vorschaltgerät WO1999034650A1 (de)

Priority Applications (4)

Application Number Priority Date Filing Date Title
AU17556/99A AU1755699A (en) 1997-12-23 1998-11-19 Electronic lamp ballast
DE59804841T DE59804841D1 (de) 1997-12-23 1998-11-19 Elektronisches vorschaltgerät
AT98962360T ATE220849T1 (de) 1997-12-23 1998-11-19 Elektronisches vorschaltgerät
EP98962360A EP1040733B1 (de) 1997-12-23 1998-11-19 Elektronisches vorschaltgerät

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DE19757600.1 1997-12-23
DE19757600 1997-12-23

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AT (1) ATE220849T1 (xx)
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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1191826A1 (de) * 2000-09-15 2002-03-27 Tridonic Bauelemente GmbH Elektronisches Vorschaltgerät mit digitaler Steuereinheit
US6577079B2 (en) 2000-09-15 2003-06-10 Tridonicatco Gmbh & Co. Kg Electronic ballast with intermediate circuit regulation
EP1372362A2 (de) * 2002-06-11 2003-12-17 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH Entladungslampenbetriebsschaltung mit einer Stromregelschaltung und einer Schaltung zur Detektion der Nähe zu einem kapazitiven Betrieb
EP1377135A2 (de) * 2002-06-11 2004-01-02 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH Entladungslampenbetriebsschaltung mit Schaltung zur Detektion der Nähe zu einem kapazitiven Betrieb
US7728528B2 (en) 2004-11-29 2010-06-01 Century Concept Ltd Electronic ballast with preheating and dimming control
DE102006014062B4 (de) * 2006-03-27 2018-05-17 Tridonic Gmbh & Co Kg Betriebsgerät für Leuchtmittel

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GB2269279A (en) * 1992-08-01 1994-02-02 Coolite Ltd Fluorescent Tube Starting and Operating Circuit
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EP0677981A1 (de) * 1994-04-15 1995-10-18 Knobel Ag Lichttechnische Komponenten Vorschaltgerät mit Lampenwechselerkennung für Entladungslampen
WO1996003017A1 (de) * 1994-07-19 1996-02-01 Siemens Aktiengesellschaft Verfahren zum betreiben mindestens einer leuchtstofflampe mit einem elektronischen vorschaltgerät sowie vorschaltgerät dafür
US5636111A (en) * 1996-03-26 1997-06-03 The Genlyte Group Incorporated Ballast shut-down circuit responsive to an unbalanced load condition in a single lamp ballast or in either lamp of a two-lamp ballast
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WO1997042794A1 (en) * 1996-05-03 1997-11-13 Philips Electronics N.V. Ballast
WO1997043878A1 (en) * 1996-05-10 1997-11-20 Philips Electronics N.V. Electronic ballast
WO1998004103A1 (en) * 1996-07-24 1998-01-29 Motorola Inc. Inverter protection method and protection circuit for fluorescent lamp preheat ballasts

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1982001276A1 (en) * 1980-10-07 1982-04-15 Grubbs C Solid state ballast with high frequency inverter fault protection
GB2224170A (en) * 1988-09-21 1990-04-25 W J Parry Electronic ballast circuit for discharge lamps
US5173643A (en) * 1990-06-25 1992-12-22 Lutron Electronics Co., Inc. Circuit for dimming compact fluorescent lamps
GB2269279A (en) * 1992-08-01 1994-02-02 Coolite Ltd Fluorescent Tube Starting and Operating Circuit
US5424611A (en) * 1993-12-22 1995-06-13 At&T Corp. Method for pre-heating a gas-discharge lamp
EP0677981A1 (de) * 1994-04-15 1995-10-18 Knobel Ag Lichttechnische Komponenten Vorschaltgerät mit Lampenwechselerkennung für Entladungslampen
WO1996003017A1 (de) * 1994-07-19 1996-02-01 Siemens Aktiengesellschaft Verfahren zum betreiben mindestens einer leuchtstofflampe mit einem elektronischen vorschaltgerät sowie vorschaltgerät dafür
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US5636111A (en) * 1996-03-26 1997-06-03 The Genlyte Group Incorporated Ballast shut-down circuit responsive to an unbalanced load condition in a single lamp ballast or in either lamp of a two-lamp ballast
WO1997042794A1 (en) * 1996-05-03 1997-11-13 Philips Electronics N.V. Ballast
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WO1998004103A1 (en) * 1996-07-24 1998-01-29 Motorola Inc. Inverter protection method and protection circuit for fluorescent lamp preheat ballasts

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1191826A1 (de) * 2000-09-15 2002-03-27 Tridonic Bauelemente GmbH Elektronisches Vorschaltgerät mit digitaler Steuereinheit
US6577079B2 (en) 2000-09-15 2003-06-10 Tridonicatco Gmbh & Co. Kg Electronic ballast with intermediate circuit regulation
EP1771046A1 (de) * 2000-09-15 2007-04-04 TridonicAtco GmbH & Co. KG Elektronisches Vorschaltgerät mit digitaler Steuereinheit
EP1771048A3 (de) * 2000-09-15 2007-04-11 TridonicAtco GmbH & Co. KG Elektronisches Vorschaltgerät mit digitaler Steuereinheit
EP1372362A2 (de) * 2002-06-11 2003-12-17 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH Entladungslampenbetriebsschaltung mit einer Stromregelschaltung und einer Schaltung zur Detektion der Nähe zu einem kapazitiven Betrieb
EP1377135A2 (de) * 2002-06-11 2004-01-02 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH Entladungslampenbetriebsschaltung mit Schaltung zur Detektion der Nähe zu einem kapazitiven Betrieb
EP1372362A3 (de) * 2002-06-11 2006-04-05 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH Entladungslampenbetriebsschaltung mit einer Stromregelschaltung und einer Schaltung zur Detektion der Nähe zu einem kapazitiven Betrieb
EP1377135A3 (de) * 2002-06-11 2006-05-03 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH Entladungslampenbetriebsschaltung mit Schaltung zur Detektion der Nähe zu einem kapazitiven Betrieb
US7728528B2 (en) 2004-11-29 2010-06-01 Century Concept Ltd Electronic ballast with preheating and dimming control
DE102006014062B4 (de) * 2006-03-27 2018-05-17 Tridonic Gmbh & Co Kg Betriebsgerät für Leuchtmittel

Also Published As

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EP1040733B1 (de) 2002-07-17
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ZA9811768B (en) 1999-06-29
AU1755699A (en) 1999-07-19
ATE220849T1 (de) 2002-08-15

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