EP0702508B1 - Electronic ballast with fuzzy-logic for gas-discharge lamps - Google Patents

Abstract

The electronic bias circuit has a rectifier (2) for rectifying the supply voltage, coupled to a current converter (3), in turn coupled to a load circuit (4) for supplying at least one gas discharge lamp (5). The brightness of the lamp is controlled via a regulation device (6, 7) with a fuzzy regulator (7), providing an outlet signal determining the setting value of at least one physical operating parameter of the current converter or the load circuit, in dependence on at least one input signal. Pref. the fuzzy regulator is supplied with a difference value obtained by comparing the actual operating current of the lamp with the required lamp operating current and is used for regulating the pulse ratio or frequency of the lamp current.

Description

The present invention relates to an electronic ballast for Gas discharge lamps according to the preamble of claim 1.

Ballasts are known in the field of electronic ballasts that work with a positively controlled oscillator and are dimmable. For dimming a gas discharge lamp to be connected to the electronic ballast the current flowing through the lamp changes. This is controlled using the Oscillator achieved by changing the lamp current frequency. The Gas discharge lamp is controlled via a series resonance circuit in its load circuit. Approximately corresponds to the frequency of the current delivered to the gas discharge lamp the resonance frequency of the series resonance circuit, the lamp is ignited. By Shift the current frequency from the resonance frequency of the series resonant circuit away or to the resonance frequency of the resonant circuit, the current of the Gas discharge lamp can be lowered or increased. To regulate the lamp current the actual value of the current lamp current is measured and with a setpoint compared. A corresponding current controller generates based on these two Values a control value for the current. The lamp voltage is set accordingly Lamp curve on.

Gas discharge lamps have a negative characteristic. That means that the The lamp voltage drops when the lamp current increases. The lamp should be brighter the current must be regulated up. But it works because of negative characteristic of the lamp counteracts the drop in lamp voltage.

For this reason, it was suggested not the lamp current, but the Lamp power, d. H. to regulate the product of lamp current and lamp voltage. The lamp power is in turn adjusted via the frequency. The The actual value of the lamp power is measured and compared with a target value. Around compensation of the control difference, i.e. the difference between the actual value and the To achieve the desired value, the frequency depends on the sign of the control difference from the resonance frequency of the one present in the load circuit of the lamp Series resonance circuit away or shifted to the resonance frequency. Such Ballasts, however, have the disadvantage that only the lamp power can be monitored. Because only the product of lamp voltage and lamp current is regulated, it is not excluded that the electronic ballast may be in an unstable or prohibited range is controlled. For example conceivable that a limit value for the maximum permissible lamp power is maintained is exceeded, however, a limit value for a maximum permissible lamp current becomes.

The invention has for its object an improved electronic Ballast for gas discharge lamps to specify, which in particular the avoids disadvantages explained above.

According to the invention, the object is achieved by an electronic ballast Claim 1 solved with the features specified in the characterizing part of claim 1.

According to the invention, use is made of fuzzy logic control technology, i.e. the The brightness of the connected gas discharge lamp is controlled by a fuzzy controller regulated that, depending on at least one input variable, a manipulated variable for a physical size of the inverter or the load circuit of the electronic Ballast generated. The lamp current is preferably regulated, i.e. the The actual value of the lamp current is recorded and fed to a comparator which measures the actual value with a specified target value and compares the resulting control difference passes on to the fuzzy controller. The fuzzy controller generates according to the rules of Fuzzy logic depending on the control difference a control signal for the Inverter or the load circuit. The control signal of the Fuzzy controller the frequency or the duty cycle of the lamp current or the Lamp voltage set. The fuzzy controller ensures by setting up Decision rules, into which corresponding empirical values can flow, that the Lamp is not controlled in unstable areas.

Instead of current regulation, voltage or power regulation is also conceivable.

For a comprehensive control of the lamp brightness, the Ambient temperature and / or the filament resistance of the gas discharge lamp is detected and be fed to the fuzzy controller. Using this information, the Fuzzy controller in connection with the detected lamp voltage a statement about make the degree of aging of the connected gas discharge lamp.

The setpoint signal of the comparator of the control device can be external, e.g. be changeable via a dimmer and also stored as a predetermined fixed value.

Furthermore, it is proposed according to the invention to use the fuzzy controller as exponential or logarithmic function element, so that between the Output variable of the fuzzy controller and its input variable an exponential or there is a logarithmic relationship. This is - as explained below will be - particularly advantageous to a linear relationship between the of the brightness output received by the gas discharge lamp and that of the To create observers subjectively perceived brightness.

A special feature of fuzzy logic is that not all input variables are used for Obtaining the output variable must be evaluated. Reaches e.g. one or the fuzzy controller sets several of the input variables regardless of the remaining input variables, the output variable to one certain value. The output value of the fuzzy controller depends only on the Design of the decision rules, i.e. the so-called fuzzy rules.

The fuzzy logic is also advantageous for detecting the lamp type connected gas discharge lamp used. From EP-A-0 413 991 it is known to determine the ignition voltage of the connected gas discharge lamp and on the basis the determined ignition voltage to infer the lamp type. The determination of Ignition voltage depends, among other things, on the manufacturer, the degree of aging Gas filling and the heating of the lamp, so that there are overall fluctuations in Range between 10% and 20% when determining the ignition voltage.

Claim 13 specifies a new method, by means of which by determining at least one operating parameter after startup of the gas discharge lamp Lamp type can be determined. The solution according to the invention has the advantage on that several different operating parameters for evaluating the lamp type can be used, the different volatility exhibit. For this reason, it is advantageous to determine the lamp type Fuzzy logic is used because of the free design of the fuzzy rules allows the individual operating parameters to be evaluated individually or in combination. A corresponding solution is given in claim 14.

If the lamp type of the connected gas discharge lamp has been determined, then this preferably in a memory in the form of various operating parameters or stored in the form of the corresponding lamp characteristic so that the lamp type does not have to be constantly checked and determined as long as the corresponding one Gas discharge lamp has not been replaced. The lamp can be replaced determined by detecting a possible break in the heating circuit become.

After determining the lamp type, the corresponding controller of the electronic controls Ballast the brightness of the connected gas discharge lamp in Depending on their type. Ideally, the type of lamp found is optical and / or indicated acoustically so that the user is constantly aware of the type of lamp used.

Further advantageous embodiments of the invention are in the rest Subclaims specified.

Fig. 1 - Fig. 4 Darstellungen zur Erläuterung der allgemeinen Funktionsweise der Fuzzy-Logik,

Fig. 5 ein Diagramm zur vergleichsweisen Gegenüberstellung der Helligkeitskennlinie eines herkömmlichen Reglers mit der eines Fuzzy-Reglers,

Fig. 6 ein symbolisches Blockschaltbild eines ersten Ausführungsbeispieles der Erfindung,

Fig. 7 ein symbolisches Blockschaltbild eines zweiten Ausführungsbeispieles der Erfindung,

Fig. 8a - 8d Darstellungen, die den Einsatz des erfindungsgemäßen Fuzzy-Reglers als exponentielles Funktionsglied verdeutlichen,

Fig. 9 ein symbolischen Blockschaltbild zur Verdeutlichung der erfindungsgemäßen Lampenerkennung, und

Fig. 10 ein Strom-Spannungs-Diagramm des Lampenstromes und der Lampenspannung zur Verdeutlichung des erfindungsgemäßen Verfahrens, bei dem aus den Strom-Spannungs-Kennlinien der Lampentyp der angeschlossenen Gasentladungslampe abgeleitet werden kann.

The invention is described in more detail below with reference to the drawing. Show it:

1-4 representations to explain the general functioning of the fuzzy logic,

5 shows a diagram for comparing the brightness characteristic of a conventional controller with that of a fuzzy controller,

6 is a symbolic block diagram of a first embodiment of the invention,

7 is a symbolic block diagram of a second embodiment of the invention,

8a-8d representations that illustrate the use of the fuzzy controller according to the invention as an exponential function element,

9 is a symbolic block diagram to illustrate the lamp detection according to the invention, and

10 shows a current-voltage diagram of the lamp current and the lamp voltage to illustrate the method according to the invention, in which the lamp type of the connected gas discharge lamp can be derived from the current-voltage characteristics.

The invention is described below on the basis of preferred exemplary embodiments Described in more detail with reference to the drawing.

As mentioned above, according to the invention, an electronic ballast for Gas discharge lamps used the fuzzy logic. The generally valid statements of Fuzzy logic will be briefly described below.

Fuzzy logic is logic that works with imprecise statements. The single ones Quantities of the fuzzy logic are quantified, i.e. it is for each size only certain value ranges permitted. The individual sizes are quantified according to so-called membership functions, the current value being one Input variable of the fuzzy logic a corresponding value range according to its Affiliation function and a corresponding truth value (degree of fulfillment) is assigned. The quantified input variables are with their Truth values combined according to certain decision rules, so that a - likewise quantified - output variable of the fuzzy logic system can be derived can. The quantified output variable is then converted into a concrete one Output variable converted according to a certain method.

The basic procedure of the fuzzy logic is now based on the example of a Temperature control, as described, for example, in the report "Technology Profile Fuzzy Logic ", Marcello Hoffmann, SRI International, June 1994 become.

It is assumed that the heating of a room depends on the interior and Outside temperature of the room should be regulated. As shown in Figure 1 the two input variables, i.e. the inside and outside temperature, and the Output variable, i.e. for example the control value for the temperature of the Boiler, quantified according to corresponding membership functions. Everyone Size is assigned only five ranges of values, according to their corresponding Membership function are delimited from each other. The one shown in Figure 1 The course of the membership functions is by no means mandatory. The individual areas can optionally also be non-overlapping and triangular. A concrete input value of the fuzzy controller is now based on its corresponding one Membership function assigned to one or more of the areas, depending on whether the areas for the concrete input value overlap or not. Of further is for the concrete input value and for each of its assigned Areas a corresponding truth value or degree of fulfillment.

To explain this procedure it is assumed that for the two Input values five value ranges "cold", "cool", "pleasant", "warm" and "hot" stand ready. The value range "cool" runs between 10 ° C and 20 ° C. If the input variable A were 15 ° C, the value range would be "cool" assigned with a truth value of 1.0. For one accordingly the corresponding lower or higher value in this range of values Truth value reduced according to the membership function.

Analogously, the output variable of the controller is also quantified, ie divided into certain value ranges. As shown in FIG. 1, the identifiers (label) "strong heating", "slight heating", "constant", "slight cooling" and "strong cooling" are available for the output variable, which are each defined between specific temperature limits. The individual temperature limits are determined based on certain empirical values. If the designation for the output variable is "slight cooling" with a truth value of 1.0, this would mean the manipulated variable T ₄ for the heating. If the output variable has a correspondingly low truth value, the control value for the heating changes according to the membership function C.

The process of quantifying the input quantities and the output quantity is called "Fuzzification" or "defuzzification" referred to. The following is exemplary be assumed that the internal temperature, as shown in Figure 1, 12 ° C and the outside temperature is 17 ° C. Corresponding to that shown in Figure 1 Membership functions thus result in a truth value for unit size A. 0.7 for the identifier "cold" and a truth value 0.3 for the identifier "cool". For the input variable B, a truth value of 0.8 results for the identifier "cool" and a truth value of 0.3 for the identifier "pleasant". Through the Membership functions are thus the internal and for each concrete input value Outside temperature each a pair of values, consisting of an identifier and an associated truth value. Since in the shown in Figure 1 Example overlap the individual value ranges for the selected temperature values, there are a total of four pairs of values that are used to find a specific manipulated variable for the boiler temperature must be combined. The single ones Pairs of values are combined crosswise with each other, with the Laws of fuzzy logic must be observed. Figure 2 shows the Laws of fuzzy logic compared to Boolean logic. For the Combination of discrete values A and B with a truth content of 1 or 0 the fuzzy logic corresponds to the Boolean logic. However, has one of the input variables A and B have a value between 0 and 1, so the Boolean logic fails. The fuzzy logic provides the minimum value of the for an AND combination of the input variables two input variables and for an OR combination the maximum value of the two Input variables, so that in principle the fuzzy logic corresponds to the Boolean logic, but with the exception that the fuzzy logic also contains unsharp values between 0 and 1 can combine with each other.

The individual value pairs of the input variables A and B, which correspond to the Affiliation functions in Figure 1 are now obtained after certain rules, the so-called fuzzy rules, combined with each other. For each a combination of a pair of values of input variable A with a pair of values the input variable B results in a certain quantified output variable C. The Individual fuzzy rules are set up based on certain empirical values. On the corresponding combination diagram is shown in FIG. 3 with the associated legend. The assignment of a specific identifier of the output variable C to one certain combination of input variables A and B is initially without Consideration of the corresponding truth values. From Figure 3, for example can be read that for the input variable A with the identifier "cold" and the Input variable B with the identifier "cool" is the identifier for output variable C "strong warming" results. The two pairs of values of input variable A and B are according to the diagram shown in Figure 3, which the fuzzy rules for this example represents, combined with each other, so that a total of four Combination variations of input variable A and input variable B with their corresponding truth values. The individual combinations are shown in Figure 4a. For the combination of the individual identifiers of the Input variables A and B become an identifier of the output variable C according to the in Figure 3 determined diagram. The identifier is then after the Calculation rules of the fuzzy logic shown in FIG. 2 from the truth values of the individual pairs of values for input variables A and B also a truth value assigned. As previously described, the truth value corresponds to the quantified one Output variable C the minimum of the two truth values of each other Combined input variables A and B. In this way the consisting of an identifier and a truth value each Input variables A and B on from an identifier and a truth value existing pair of values determined for the quantified output variable C. In this Example, as shown in Figure 4a, four pairs of values for the output variable C received.

The last remaining step to determine a concrete manipulated variable for the Heating is the implementation of the four pairs of values of the quantified output variable C in a specific controller manipulated variable. For this purpose, the four different ones Value pairs of the output variable C combined with each other to a specific one to receive a concrete manipulated variable. This process is called defuzzification.

Various methods are proposed for the defuzzification process been. The most common method, however, is the so-called center of gravity method, who works with weighted proportions and quasi a weighted average the individual pairs of values of the quantified output variable C.

Figure 4b is intended to illustrate the operation of this method. The associated truth values are applied to the individual identifiers of the output variable C. According to FIG. 4a, the identifier "strong warming" with a truth value of 0.7 was obtained once for the quantified initial variable C and three times the identifier "slight warming" with a truth value of 0.3 each. The remaining identifiers of the associated membership function C have not been determined, which corresponds to a truth value 0 for these identifiers. The center of gravity is calculated for the structure thus obtained using the following formula: T Stell = T 1 0.7 + (0.3 + 0.3 + 0.3) T 2nd 0.7 + 0.3 + 0.3 + 0.3.

In this example, the calculated center of gravity corresponds to the concrete manipulated variable for the boiler temperature. If, for example, it is assumed that T ₁ corresponds to a heating boiler temperature of 80 ° C and T ₂ corresponds to a heating boiler temperature of 70 ° C, the control value for the heating boiler temperature would be 74 ° C.

This way, using fuzzy logic can be done quickly and easily using fuzzy terms and corresponding truth values, concrete manipulated values for one Controller can be determined. In particular in the field of programming, the Fuzzy logic has many advantages because it is automatic quickly and inexpensively Applications can be implemented.

According to the fuzzy logic described above for an electronic Ballast used for gas discharge lamps.

Due to the use of the fuzzy logic, the inventive method results electronic ballast compared to the known electronic ballast a number of advantages. The main advantages of fuzzy logic are for example in "Fuzzy logic, the fuzzy logic conquers technology", Daniel McNeill and Paul Freiberger, Droemer Knaur Verlag, 1994. So points for example, the logic control over digital control has the advantage that a possibly existing control difference is gradually reduced, while at comparable digital controllers often exceed or fall below the target value is so that this overregulation must be quickly compensated for. This advantage the fuzzy logic can be used in particular when igniting gas discharge lamps become. Gas discharge lamps are made by approximating the frequency of the Lamp current to the resonance frequency of the existing in the load circuit Series resonance circuit switched on or ignited. Should the lamp after Turn on to operate at a low brightness, so it is necessary after switch the brightness of the lamp down quickly when switching on, whereby at ordinary systems undershoot below the desired brightness occur what in the worst case, the lamp can go out.

FIG. 5 shows (a) the time-dependent characteristic of the lamp brightness E during an ignition process of the gas discharge lamp. It can be seen that while the lamp brightness _{is being} reduced, the target brightness E target is fallen short of, so that compensation control is necessary to achieve the target value. With the fuzzy logic, on the other hand, an improved approach to the desired brightness value is possible without overshoot or undershoot. For comparison, FIG. 5 shows the brightness characteristic curve (b) that can be achieved with a fuzzy controller.

Furthermore, the fuzzy logic enables a particularly fast response or Setting the output size possible so that when using a fuzzy controller an existing control difference, as can also be seen in FIG. 5, is compensated more quickly can be. Other advantages of fuzzy logic can be seen in the fact that compared less information is required about known control systems and additionally this Verbal formulations can be found immediately because the Fuzzy logic works with linguistic terms. For this reason, too human knowledge is brought into the system in the simplest way, without translation into complex mathematical models.

According to the fuzzy logic described above for an electronic Ballast used for gas discharge lamps. Figure 6 shows a first Embodiment of the ballast according to the invention.

The electronic ballast comprises a rectifier 2, which is fed by a supply voltage source 1 and is connected to an inverter 3. A load circuit 4 is connected to the inverter 3, which serves to control a gas discharge lamp 5 and usually contains, inter alia, a series resonance circuit for igniting the connected gas discharge lamp 5. Furthermore, the electronic ballast comprises a control device which comprises a controller 7 and a comparator 6. According to the invention, the controller 7 is designed as a fuzzy controller. The control device can be arranged in the electronic ballast or also externally. The lamp current of the connected gas discharge lamp 5 is preferably regulated. For this purpose, the lamp current is detected by a current measuring element 8 and the instantaneous actual value of the lamp current i _is output to the comparator 6 of the control device. The comparator 6 compares the actual value i _{ist of} the lamp current with a predetermined lamp current setpoint i _soll , the current setpoint i _soll corresponding _to a predetermined dimming setpoint, which is output, for example, by a dimmer to the comparator 6. Be the current target value i _soll or the predetermined dimming setpoint can be changed in both time manually, as is the case with ordinary Dimmeinrichtungen, as well as present an invariable fixed value, for example, stored in the form. The comparator 6 determines a control difference value i _diff , which is applied to the fuzzy controller 7, on the basis of the comparison of the current setpoint i _soll with the actual value i _ist . The fuzzy controller generates a control value y for the inverter 3 depending on the input variable i _diff. The lamp brightness is usually set by adjusting the frequency f or the pulse duty factor d of the lamp current of the connected gas discharge lamp 5. With the fuzzy controller, however, manipulated values for other physical quantities of the inverter 3 or the load circuit 4 can also be generated. Likewise, the invention is not limited to the exemplary embodiment shown in FIG. 6. Rather, the fuzzy controller can also be used to regulate the lamp voltage or lamp power. For this purpose, as indicated by dashed lines in FIG. 6, a voltage measuring element 9 is provided which detects the instantaneous lamp voltage and generates an actual value of the lamp voltage u _ist . In order to be able to regulate the lamp voltage, the lamp voltage actual value signal u _ist determined by the voltage measuring element 9 is then applied to the comparator 6 instead of the lamp current actual value signal i _ist and compared there with a voltage target value, the comparator 6 then correspondingly Control difference signal of the voltage to the fuzzy controller. Should the lamp power be regulated, so that from the current-measuring device 8 and the voltage measuring element 9 are actual values supplied _is i and u _is mulitiplizieren together, for example by using a multiplier, and the thus obtained power value to be applied to the comparator 6 , which uses this to apply a corresponding control difference signal to the fuzzy controller by comparison with a specified power setpoint. However, it should be pointed out at this point that the current control, as shown in FIG. 6, represents the common type of control. The reason for this can be seen in the fact that, due to the negative characteristic curve of the lamp, a plurality of lamp current values can be assigned for one lamp voltage value, so that ambiguities would arise in the case of voltage regulation. In contrast, there is only a single lamp voltage value for each lamp current value, so that ambiguities are avoided with the aid of the current control.

It is also possible according to the invention that the lamp voltage u detected by the voltage measuring element 9 _{is to be applied} directly to the fuzzy controller 7 as a further input variable of the fuzzy controller 7. In this case, then, the fuzzy controller 7 combines the two input values i _diff and _u which are present in fuzzifizierter form, and determines capped decision rules based on previously a corresponding control value signal y for the inverter 3 or the load circuit 4 of the electronic ballast. Due to the properties of the fuzzy logic described above, in contrast to conventional controllers, it is possible in principle to evaluate certain input variables and to combine them, whereby neither the input variables nor the output variable need to belong to the same physical variable (eg current or voltage). Actual values of the outside temperature and / or the filament resistance of the gas discharge lamp can also be supplied to the fuzzy controller 7 as further input variables. This will be explained in more detail with the aid of a subsequent exemplary embodiment. Due to the property of the fuzzy logic, the brightness of the connected gas discharge lamp 5 can be set very effectively, quickly and easily using the circuit according to the invention. For this purpose, all input variables of the fuzzy controller 7 and the output variable (s) of the fuzzy controller are fuzzified. One or more fuzzified values for the output variable of the fuzzy controller 7 are obtained from a concrete value pair of the input variables applied to the fuzzy controller, and a concrete value for the output variable is derived therefrom by defuzzification, as described above. As shown in FIG. 6, the specific defuzzified manipulated variable y of the fuzzy controller 7 is applied to the inverter 3 or the load circuit 4 in order to preferably set the frequency or the pulse duty factor of the lamp current or the lamp voltage.

FIG. 7 shows a further exemplary embodiment, which differs from the first exemplary embodiment shown in FIG. 6 in that, as already described above, the lamp voltage is also monitored by a voltage measuring element 9 and a corresponding actual lamp voltage value u _{is applied} to the fuzzy Controller 7 is created as an additional input variable. Furthermore, in FIG. 7, the fuzzy controller 7 generates a further output signal z in addition to the control value y for the inverter 3. In the drawing, the corresponding parts of the block diagrams are identified by identical reference numerals. In the second exemplary embodiment shown in FIG. 7, the fuzzy controller 7 can draw conclusions about the aging of the connected gas discharge lamp 5 with the aid of the supplied voltage u _ist . For this purpose, according to the fuzzy logic, the fuzzy controller assigns each fuzzified lamp voltage value u _is a corresponding degree of aging on the basis of previously established decision rules, the degrees of aging also being present in fuzzified form. After defuzzification of the degree of aging has taken place, ie the conversion of the fuzzified degree of aging into a concrete aging value, the fuzzy controller 7 outputs the corresponding output signal z. Furthermore, the feedback voltage u _ist can also be used for constant regulation of the lamp power. The lamp voltage of the gas discharge lamp 5 changes depending on the ambient temperature, so that it is necessary for constant regulation of the lamp power, depending on the instantaneous lamp voltage u _, the current value has to be increased or decreased. In this context, it should be pointed out that the brightness of the connected gas discharge lamp is approximately proportional to the lamp power. In FIG. 7 it is also indicated that, in addition to the control difference value i _diff, alternatively or alternatively also its temporal gradient i ' _diff , ie the change in the control difference i _{diff over time} , can be fed to the fuzzy controller 7, since, for example, also when the degree of aging is detected of the connected gas discharge lamp are interested in the rate of change of the lamp current over time and can accordingly be used to determine the degree of aging.

At this point, another use of the fuzzy controller 7 in Connection with electronic ballasts for gas discharge lamps pointed out. It is common knowledge that between that of a lamp recorded brightness performance and the subjective perception of an observer there is a logarithmic relationship, as is shown, for example, in FIG. 8d. On the one hand, this means that when the lamp is doubled recorded brightness power by the observer does not double the Brightness is perceived. Secondly, it follows that for a linear Increase in sensation compared to that absorbed by the lamp Brightness performance is an exponential increase in the absorbed by the lamp Brightness power is required so that a linear relationship between the Brightness performance of the lamp and the real perception of the observer guaranteed can be.

From the magazine "Electronics", edition 9/1994, p. 80, it is known such to realize exponential distortions with a fuzzy component. This is illustrated below with reference to FIGS. 8a-8c. Referring to Figure 8a it is assumed that an input variable X of the fuzzy component has a value range of 0-100 and with the membership function shown in Figure 8a five different value ranges is fuzzified. The maximum values of this Value ranges are 0, 25, 50, 75 and 100. As shown in FIGS. 8b and 8c, should also be the range of values of the output variable Y, which is a function of the input variable X represents 0-100. However, the output variable Y does not become inherent overlapping value ranges, but by individual, discrete values, so-called Singletons, each modeled with the truth value 1.0. The values of the singletons result from inserting the maximum values of the value ranges of the input variable X into the function to be described by the fuzzy component. Figure 8b shows the Realization of the straight line function Y = X, the values of the singleton of Output variable Y by inserting the maximum values 0, 25, 50, 75 and 100 in the Straight line equation can be obtained. In the straight line equation we get for the singletons have the same values as for the maximum values of the value ranges of the Input variable X. In contrast, FIG. 8c shows the implementation of a Exponential function, in which the values of the singletons of the output variable Y by inserting the maximum values 0, 25, 50, 75 and 100 of the value ranges of the Input variable X in the corresponding exponential equation shown in FIG. 8c be preserved. If the fuzzification method shown in Figure 8c to the previous described fuzzy controller 7, it is possible according to the invention between the output of the fuzzy controller, i.e. the manipulated variable for the inverter 3 or the load circuit 4 and the input variable of the fuzzy controller, for example the Control difference in lamp power or lamp current, an exponential Establish connection so that between the subjective feeling of the Observer and the brightness output recorded by the lamp is a linear one Connection is realizable.

Figure 9 shows a third embodiment of the invention according to the invention, at that in connection with an electronic ballast for a Gas discharge lamp use is made of the fuzzy logic.

However, the exemplary embodiment shown in FIG. 9 is independent of the fuzzy logic the inventive idea is based on different operating parameters of the connected gas discharge lamp after commissioning to the lamp type to close the gas discharge lamp 5. As already mentioned, it has already been done proposed the ignition voltage of a connected gas discharge lamp determine and infer the lamp type based on the determined ignition voltage. However, the determination of the ignition voltage depends on many different ones Requirements or parameters, so that the ignition voltage is only inaccurate can be determined. In contrast, the invention proposes at least one Determine the operating parameters of the lamp after its commissioning and on the basis of this operating parameter to infer the lamp type. However, it is advantageous monitor several operating parameters, so that according to the invention the possibility consists of evaluating the operating parameters both individually and in combination.

The basic procedure for lamp detection is briefly described below described. It is assumed that the Control device to be controlled physical quantity is the lamp current. To Commissioning of the gas discharge lamp will have different lamp current setpoints specified and the lamp current set according to these setpoints. To each Lamp current setpoint becomes the corresponding actual value of those to be monitored Operating size of the gas discharge lamp determined. The individual thus preserved Actual values of the operating variables are combined with one another, so that subsequently on the basis of the actual values depending on the specified lamp current setpoints Lamp type of the connected gas discharge lamp can be closed. To This purpose is, for example, the evaluation of various predefined ones Characteristic curves of the individual lamp types conceivable. For example, the Current / voltage characteristics of different lamp types can be known. As before different current setpoints are set and accordingly the Lamp voltage determined depending on the set current setpoints. Based the determined current / voltage value pairs and the various existing ones Current / voltage characteristics can be based on the lamp type of the connected Gas discharge lamp can be closed.

According to the invention, fuzzy logic is advantageously used for the evaluation of individual operating parameter values or different operating parameters in combination. A corresponding embodiment is shown in FIG 9. To lamp recognition are 14 via a resistive measuring element, a voltage measuring element 9 and a temperature-measuring element 11 _is 10, the instantaneous actual values of the coil resistance R a fuzzy logic component of the lamp voltage _u of the connected gas discharge lamp or the outside temperature T _is supplied. The fuzzy logic component 14 specifies current setpoints for setting the lamp current to a control device and detects the actual values R _ist , u _ist and T _ist depending on the set current setpoints. In this way, several actual lamp values R _ist , u _ist and T _{ist are} assigned to several lamp current values that have been set. The controller 7 shown in Figure 9 can also be implemented as a fuzzy controller, in which a supply of the lamp voltage detected _is u is as further input variable of the fuzzy controller for more precise control of the lamp current of advantage. Based on known relationships between the monitored operating parameters and the different types of lamp decision rules previously set, due to which the fuzzy logic component 14 _is the respective (fuzzifizierter) in quantified form the present actual values of the monitored operating variables R, _u and T _is according to the procedure of Fuzzy logic assigns a corresponding lamp type. The more different current values are approached, the more precisely the lamp type is determined. The decision rules were preferably established on the basis of known characteristic curves of the different lamp types.

FIG. 10 shows an example of the assignment of the lamp type to the detected actual values of the outside temperature T _ist , the filament resistance R _ist and the lamp voltage u _ist , different current-voltage characteristics being shown for different lamp types. The characteristics shown show the current-voltage characteristics of three different lamp types for the temperature range T _ist ≦ 25 ° C and for a filament resistance R _ist below a certain limit. For other areas of the temperature T _ist and the coil resistance R _ist , further characteristic curves are recorded or are already available. The voltage range of the lamp voltage u _L is divided into several ranges U ₁ to U ₅ , ie quantified or fuzzified. Because of the fuzzy logic component 14 known voltage and current values may be selected from the fuzzified lamp voltage depends on the instantaneous temperature T _and the instantaneous coil resistance _R, which are also present in quantified form, to the corresponding lamp characteristic closed, since these Characteristic must contain the set nominal point.

As shown in FIG. 9, a memory 13 is advantageous with the fuzzy logic 14 connected so that after determining the lamp type, this lamp type for example in the form of the corresponding lamp characteristic or in the form of various operating parameter values can be stored in the memory. On this is a repeated determination of the lamp type and an associated one repeated setting of the lamp current of the gas discharge lamp 5 during its Operation is not necessary, it is sufficient to determine the Lamp type. The lamp type can also be indicated acoustically or optically be so that the user during the operation of a gas discharge lamp the connected lamp type is constantly informed. According to the invention continues proposed to delete the memory after each lamp change. So can for example by detecting an interruption in the heating circuit Gas discharge lamp using a heating current measuring element 12 detects a lamp change and then the memory will be deleted.

If the lamp type of the connected gas discharge lamp has once been detected, the further control of the lamp brightness will depend on the detected lamp type, said fuzzy logic component 14 defines a respective current target value i _soll according to the determined lamp type to the comparator 6 of the control device.

Claims (25)

1. Electronic ballast for gas discharge lamps,

   having a rectifier (2) for rectifying a supply voltage,

   having an inverter (3) fed from the rectifier,

   having a load circuit (4), to which at least one gas discharge lamp (5) can be connected, connected to the inverter, and

   having a control device (6, 7) with a comparator (6) for controlling the brightness of the at least one gas discharge lamp,

      characterized in that,
      the control device includes a fuzzy controller (7) which in dependence upon at least one input signal (i_diff, u_ist, R_ist, T_ist) determines as output signal a setting value (y) for a physical parameter (f, d) of the inverter (3) or of the load circuit (4).
2. Electronic ballast according to claim 1,
      characterized by
      a current measurement means (8) for detecting the actual value (i_ist) of the lamp current of the at least one gas discharge lamp (5).
3. Electronic ballast according to claim 2,
      characterized in that,

   the comparator (6) determines a control difference value (i_diff) by means of comparison of the actual value of the lamp current (i_ist) with a settable lamp current desired value (i_soll), and

   in that the control difference value is applied to the fuzzy controller (7) as input signal.
4. Electronic ballast according to any preceding claim,
      characterized in that,
      the physical parameter of the inverter (3), for which the fuzzy controller (7) determines a setting value (y), is the duty ratio (d) or the frequency (f) of the lamp current or the lamp voltage of the at least one gas discharge lamp (5).
5. Electronic ballast according to any preceding claim,
      characterized by
      a voltage measurement means (9) for detecting the actual value of the lamp voltage (u_ist) of the at least one gas discharge lamp (5).
6. Electronic ballast according to claim 5,
      characterized in that,
      the actual value of the lamp voltage (u_ist) detected by the voltage measurement means (9) is applied to the fuzzy controller (7) as input signal.
7. Electronic ballast according to claim 6,
      characterized in that,
      there is provided a temperature measurement means (11) for detecting the actual value of the environmental temperature (T_ist), and in that the actual value of the environmental temperature (T_ist) is applied to the fuzzy controller as input signal.
8. Electronic ballast according to claim 6 or 7,
      characterized in that,
      there is provided a resistance measurement means (10) for detecting the actual value of the winding resistance (R_ist) of the at least one gas discharge lamp (5), and in that the actual value of the winding resistance (R_ist) is applied to the fuzzy controller (7) as input signal.
9. Electronic ballast according to any of claims 6 to 8,
      characterized in that,
      the fuzzy controller (7) generates an output signal (z) dependent upon at least one of the input parameters (i_diff, u_ist, R_ist, T_ist) applied thereto, from which output signal the degree of aging of the connected gas discharge lamp (5) can be derived.
10. Electronic ballast according to any of claims 3 to 9,
       characterized in that,
       the desired value (i_soll) of the comparator (6) can be varied.
11. Electronic ballast according to any preceding claim,
       characterized in that,
       the fuzzy controller (7) determines the output signal (y) in accordance with an exponential function dependent upon the input signal (i_diff).
12. Electronic ballast according to any preceding claim,
       characterized in that,
       when a limit value of one or more of its input signals (i_diff, u_ist, R_ist, T_ist) is present, the fuzzy controller determines the output signal or the output signals (y, z) independently of the other input signals.
13. Method of recognizing the lamp type of a gas discharge lamp,
       characterized by the method steps

    placing the gas discharge lamp (5) in operation,

    setting various current desired values (i_soll),

    setting the lamp current correspondingly to the set lamp current desired values (i_soll),

    determining the actual value of at least one operational parameter (u_ist, R_ist, T_ist) of the gas discharge lamp (5) in dependence upon the respectively set lamp current desired values (i_soll),

    selecting a lamp type from several predetermined lamp types in dependence upon the various lamp current desired values (i_soll) and the respectively thereto determined actual values of the at least one operational parameter (u_ist, R_ist, T_ist) and

    allocation of the selected lamp type to the connected gas discharge lamp (5).
14. Method according to claim 13,
       characterized by the further method steps

    fuzzification of the at least one operational parameter (u_ist, R_ist, T_ist) in accordance with fuzzy logic,

    prescription of at least one decision rule which allocates the at least one fuzzified operational parameter (u_ist, R_ist, T_ist) of the gas discharge lamp (5) to one of a plurality of predetermined lamp types, in accordance with fuzzy logic, and

    selection of one lamp type from the plurality of predetermined lamp types in dependence upon the various lamp current desired values and the respectively detected fuzzified actual values of the at least one operational parameter (u_ist, R_ist, T_ist) on the basis of the at least one decision rule.
15. Method according to claim 14,
       characterized in that,
       the at least one decision rule is prescribed on the basis of known lamp characteristics for the plurality of predetermined lamp types.
16. Method according to any of claims 13 to 15,
       characterized in that,
       the brightness of the connected gas discharge lamp (5) is controlled in dependence upon of the detected lamp type.
17. Method according to claim 15,
       characterized in that,
       after detection of the lamp type of the connected gas discharge lamp (5) a lamp current desired value (i_soll) of a control device (6, 7) is set for controlling the lamp current.
18. Method according to claim 16 or 17,
       characterized in that,
       the brightness or the lamp current of the gas discharge lamp (5) is controlled in accordance with fuzzy logic.
19. Method according to any of claims 13 to 18,
       characterized in that,
       the lamp voltage (u_ist) and/or the winding resistance (R_ist) of the gas discharge lamp is or are detected as the at least one operational parameter.
20. Method according to any of claims 13 to 19,
       characterized in that,
       as operational parameter for the selection of the lamp type of the gas discharge lamp (5) there is detected the environmental temperature (T_ist) .
21. Method according to and of claims 13 to 20,
       characterized in that,
       the detected lamp type is stored in a memory (13) in the form of particular operational parameter values and/or of the corresponding lamp characteristic.
22. Method according to claim 21,
       characterized in that,
       a change of lamp is recognized, the memory is erased and then the lamp type of the new gas discharge lamp is determined.
23. Method according to claim 22,
       characterized in that,
       a change of lamp is recognized by means of detection of an interruption of the heating current circuit of the gas discharge lamp (5).
24. Method according to any of claims 14 to 23,
       characterized in that,
       the brightness of the gas discharge lamp (5) is controlled in accordance with an exponential function.
25. Method according to any of claims 13 to 24,
       characterized in that,
       the detected lamp type of the gas discharge lamp (5) is indicated optically and/or acoustically.

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