AT15250U1 - Converter module for phase dimming of LEDs - Google Patents

Abstract

The invention provides a converter module for dimming at least one LED, comprising a switched / clocked converter comprising a converter switch which supplies power to the at least one LED, the converter being operated in a limit mode, wherein a converter switch is turned on in the limit mode when the input current is a predetermined threshold level, e.g. B. 0 amps reached, a detection device for detecting a current / voltage input to the converter, in particular on its primary side, and a control unit (U1), which is suitable for changing a turn-off threshold of the converter switch as a function of the current / voltage, / which is detected at the detection device.

Description

description

CONVERTER MODULE FOR A PHASE DIMMING OF LEDS

The invention relates to converter modules that enable a dimmable operation of LEDs, which are dimmable by a phase dimmer (triac). Triacs are still widely used as an incandescent dimming infrastructure.

It is known that incandescent convert the leading phase angle directly into a corresponding light power. The operation of a dimmable converter module is different because the leading phase angle can not be directly converted to a corresponding variable light power in a normal LED actuator.

The converter module can be used to operate at least one LED incandescent lamp, e.g. LED retrofit lamp, which may have a limited dimming function. Alternatively or additionally, the converter module may also be part of an LED incandescent lamp or LED retrofit lamp, for example as a module integrated in the incandescent lamp.

The converter module according to the invention has a control unit / a converter driver, which controls either a flyback converter with a galvanically isolated primary and secondary side, which is operated for example in the limit mode, or a buck converter. Other converter structures may also be used in the illustrated inventive concepts.

The turn-on time (sound) of a switch of the flyback converter can be maintained at a constant level during a half-cycle / half-cycle of the supply voltage supplied to the converter module. The switch-off time (Toff) can then be determined from the current value of the supply current / the supply voltage or results from this. Normally, the supply current / supply voltage is a mains current / mains voltage, but it can also be another input voltage.

In operation, a change or variation in the supply current voltage resulting, for example, from a Phasenanschnittsdimmvorgang lead to a change or fluctuation of the LED input voltage.

Current control methods and devices in which a switched mode power supply provides power factor correction and output voltage to a load via the control of a single switch without requiring feedback information associated with the load are known from WO02 / 8137460 A2. In this document, a single switch can be driven without monitoring either the output voltage at the load or a current absorbed by the load, and without regulating either the output voltage at the load or the current absorbed by the load. The rms value of an AC input voltage to the switched-mode power supply can be varied via a conventional AC dimmer to then control the output voltage. The switching power includes a flyback converter assembly, a buck converter assembly or a boost converter assembly, and the load may include an LED based light source.

Dimmable controllers are also known which provide various approaches to the problem of controlling triac behavior / phase control dimming and converting the phase angle into an LED current. A disadvantage of these approaches is that they require a large material set-up (BOM) and require, for example, double-sided printed circuit boards (PCB).

Therefore, an object of the invention is to provide an LED actuator which enables the dimming of LED's connected thereto, which are dimmable by phase control / phasing leading edge / triac dimmers, the overhead being so low be held as possible.

This problem is solved with a device, a method and a system according to the independent claims. Further aspects of the invention are dealt with in the dependent claims.

In a first aspect, the invention provides a converter module for dimming at least one LED, with a switched converter providing power to the at least one LED, the converter being operated in a limit mode, and wherein the Converter on its input side has a passive, so-called bleed circuit connected to generate a holding current for a dimmer, and wherein the converter module is designed for control by a phase-locked / triac dimmer.

In another aspect, the invention provides a converter module for dimming at least one LED with a switched converter which supplies power to the at least one LED, the converter being operated in a limit mode, detection means for Detecting a current / voltage input to the converter, in particular on its primary side, and a control unit, which can change a turn-off threshold of the converter switch in dependence of / on the detection device detected current / voltage.

The passive bleed circuit may consist of a capacitor (C10) and / or a series resistor (R10). Attenuators (R1, R9) may be conductively connected in input current / input voltage paths of the converter, e.g. a live wire or a neutral conductor. The damping resistors and / or the bleed circuit can be designed such that a ringing of a radio interference choke of the dimmer is attenuated.

The converter may be a flyback converter. The converter can be controlled by a control unit. In limit mode, the converter switch may be on when the input current is at a predetermined threshold, e.g. 0 amps, reached.

It can be provided a detection device to switch the converter switch in response to the input current / the input voltage of the converter.

The detection device may consist of an auxiliary winding, particularly galvanically separated from a converter winding and in particular be arranged on the primary side of the converter. The detection means may feedback a parameter indicative of the input current / voltage of the converter indirectly or directly.

The control unit may consist of a PFC (Power Factor Correction) fixed controller and / or a PFC fixed output controller.

The control unit may include a DC bus capacitor and / or a correction circuit capable of controlling an input current / input voltage from a mains voltage source during a half cycle.

A PFC, in particular a passive PFC circuit, may be located in the control unit and / or in the converter module. The control unit may comprise a switch of the flyback converter.

A feedback signal may be supplied from the detection device to the control unit.

The detection means may be provided on the primary side of a flyback converter and preferably directly or indirectly couples a parameter indicating the current / voltage through the primary side of the flyback converter back to the control unit.

The detection means may feedback a current / voltage to the control unit as a negative current / negative voltage depending on the input current / input voltage to the module, the feedback current / voltage being the current (s). Indicates voltage through a shunt resistor, which is arranged in series with the flyback switch, for example, built into the control unit.

The control unit may generate current / voltage, wherein the control unit may be able to change the input current / input voltage supplied to the converter, in particular on the primary side of the converter, preferably as a function of the current / voltage generated.

The control unit may influence the input current / input voltage supplied to the converter as a function of a phase angle by varying the peak current, i. of the current / voltage changing upon turn-off of the flyback converter, and more particularly by varying the peak current / voltage such that the latter are substantially proportional to the instantaneous amplitude of the input current / voltage.

There is provided an energy store, which may be located in particular on the primary side of the flyback converter.

In particular, on the secondary side of the flyback converter, a storage capacitor may be provided which is dimensioned so that it compensates for a ripple on the converter module input current supplied / the input voltage.

The turn-off threshold of the control unit and / or the inhibit switch may be adaptively adjusted as a function of the input current / voltage of the converter to simplify the PFC function.

In the feedback path from the detection means to the control unit, a Zener diode may be connected to clamp the feedback to the control unit negative current / the negative voltage to a maximum value. The terminals may additionally or alternatively be made in the control unit or by software of the control unit.

The converter may be a down converter. The auxiliary winding may have only a few windings, e.g. 1 to 7, in particular at least two windings, which can reduce the current supplied to the control unit / the voltage and / or reduce the power loss at the control unit.

The control unit can be supplied with an input signal via a first resistor, which can be selectively connected by means of a selection circuit, which can take at least two states, in a first state of the selection circuit with a further resistor to a voltage divider. The input signal can be supplied from the voltage divider to the control unit.

The input signal can reproduce the course of the supply voltage. The supply voltage may be the mains voltage or a voltage derived therefrom.

The selection circuit may adopt the first or a second state as a function of whether a predetermined threshold value is exceeded by a value derived from the supply voltage.

The derived from the supply voltage size can be supplied to the selection circuit via a voltage divider.

The input signal may be a reference value. The reference value may be reduced when the selection circuit is in the first state.

The control unit may be operated in a higher power operating mode when the selection circuit is in the first state and / or the reference value is reduced.

The control unit may be operated in a lower power mode when the selection circuit is in the second state and / or the reference value is not reduced.

In a further aspect, there is provided a method of dimming at least one LED, comprising the steps of providing a converter module with a phase locked / triac dimmer controlled input current / input voltage, powering the at least one LED a switched / clocked converter, wherein the converter is operated in a limit mode, and generating a holding current for the phase locked / triac dimmer by a passive bleed circuit.

In yet another aspect, there is provided a method of dimming at least one LED, comprising the steps of providing a converter module with a phase-locked / triac dimmer-controlled input current / input voltage, powering the at least one LED by a switched / clocked converter, wherein the converter is operated in a limit operation, and the detection by a detecting means of a current input / a voltage in the converter, in particular on its primary side, wherein a switch-off threshold of the converter switch in dependence of / of the detection means detected current / voltage is changed via the control unit.

In yet another aspect, a system is provided with a phase locked / triac dimmer and a converter module as described above.

Further aspects of the invention will be explained below with reference to the drawings. In particular, FIG. 1 shows an example dimmer driver based on fixed output PFC control; FIG. FIG. 2 shows an exemplary input current waveform; FIG. FIG. 3 shows an exemplary power factor corrected buck converter; FIG. FIG. 4 shows an existing PFC model; FIG. FIG. 5 shows an exemplary fixed output driver with PFC; FIG. Fig. 6 shows by way of example primary peak currents of the converter without terminals; Fig. 7 shows by way of example primary peak currents of the converter with terminals; Fig. 8 shows by way of example input network currents of the converter without terminals; Fig. 9 shows by way of example input network currents of the converter with terminals.

Fig. 10 shows an example of a modification of the circuit of Fig. 5 with a verbes serten dimming behavior.

Single-stage fixed output power lock-up control units (ICs) with built-in power factor correction are known, but it will be appreciated that this type of control unit can be used for a simple and elegant dimming solution with very good performance, as described below.

In general, the invention is directed to providing a smooth and flicker-free dimming that can be achieved in conjunction with most dimmers, whereby the amount of parts and material lists can be reduced, and which can function simultaneously with different ICs. In addition, no high-voltage electrolytic capacitor must be present.

For this purpose, the circuit present in the converter module for controlling the at least one LED can provide a power factor correction (PFC) function, e.g. In particular, the invention uses the high power factor of a PFC circuit When a flyback converter is used, the current / voltage on the secondary side of the flyback converter driving the at least one LED mirrors, reflected by phase angle or phase section at the input of the primary side of the converter dimming reflected.

In this case, there is the problem that the PFC circuit sometimes does not receive enough power that the used for Phasenanschnitts- or phase portion dimming (triac) dimmer required as holding current. Bleed circuits are known to remedy this symptom and to ensure the required holding current through their power loss. Usually, these bleed circuits are formed as tracks, which can be selectively operated or interrupted.

However, the invention solves the problem by using only passive components to fabricate the bleed circuits, and more particularly to an ohmic resistor R10 and a capacitor C10 as shown in the exemplary LED actuator circuit shown in FIG.

Furthermore, two additional ohmic resistors R1, R9 are connected to the input lines of the circuit, which are referred to as current / phase wire and zero line in Fig. 1, which is advantageous for the damping of the sound at the input of the circuit through an interaction of the phase control / triac dimmer with inductive identifier and a PFC circuit with capacitive switch is generated.

Fig. 1 shows an arrangement with additional passive components for attenuating a ringer R1, R9 of the radio interference suppression reactor (RFI) of the dimmer with switching capacity. This in turn ensures even, flicker-free dimming. Thus, Fig. 1 shows a circuit for a converter module with a fixed output power PFC controller. The PFC function circuit is replaced by the use of a circuit integrated in the control unit, e.g. the flyback converter driver, realized with an integrated switch.

The components circled in Figure 1 represent the additional components for attenuating the blade R1, R9 and for making passive bleeding R10, C10. However, the circuit shows very little complexity of the converter even using the latest fixed output power controllers ,

Furthermore, an auxiliary winding is provided, which is inductively coupled to the converter and in which current / voltage is generated in dependence on the mains voltage of the LED actuator. This generated voltage is supplied to the control unit as a negative current / voltage. The generated voltage also indicates the current / voltage through a shunt resistor connected in series with a switch built into the control unit. The turn-off threshold is adaptively changed by the control unit, i. depending on the current state of the mains voltage, resulting in the PFC function.

To simplify dimming operations as a function of a leading phase angle of the mains voltage, a feedback signal is fed back from a detection device, for example an auxiliary winding AUX of the converter, to the control unit. In particular, the current through the detection means is measured to determine the current in the converter, preferably the current through the primary side of a flyback converter. As a result, the control unit directly or indirectly determines the current / voltage, for example through the primary side of the flyback converter. This particular current / voltage represents the signal fed back to the control unit. The control unit may be an IC, ASIC or a microcontroller.

If the converter is designed for example as a flyback converter, the circuit of the converter module can provide an energy store (capacitor) on the secondary side of the converter, wherein the flyback converter provides an inductive separation between arranged on the primary side of the components and arranged on the secondary side components , The auxiliary winding as shown for example in Fig. 5 can also be located on the secondary side.

A flyback converter with constant on-time (sound) could realize the PFC function even without feedback supplied to the driver IC from the auxiliary winding. However, the power factor would not be so good. An example of a control unit used is the HVLED8 05 from ST Microelectronics.

A single stage, power factor corrected controller may also include a small DC bus capacitor in the range of about 100nF. Therefore, a flyback converter receives as its input non-smoothed, rectified mains half-cycles that may drop to 0V.

The use of such an integrated driver circuit (IC) allows excellent dimming performance with most so-called leading or trailing edge (rising or falling) dimmers. The circuit usually fits on a single-sided board and, as the process works with virtually any fixed PFC controller, the designs can be easily adapted to applications that use the latest low-cost IC.

While in Fig. 1, a possible output ripple is controlled only by an output capacitor, the simple structure of the circuits also leaves room for a large capacitor, with which the ripple under 40% to 60%, in particular 50%, can be maintained.

As a control factor, the control unit generates current / voltage which is used to change the current of the flyback converter to its primary input side. In particular, a dimming operation depends on the phase gating when the peak current, namely the current at the flyback switch off is changed, and the peak current is controlled so that it is in principle proportional to the amplitude of the present input voltage.

Consequently, depending on the phase angle, a current characteristic could be generated, as shown by way of example in FIG. 2.

It should be noted that the converter module circuit can also be used with other converters, e.g. Down converter structures. In addition, the control unit may have a power factor correction (PFC), but this is not mandatory. However, an improvement in the power factor of the converter module circuit is desirable, and therefore, a method for applying a power factor correction in any control unit will be described below, particularly for control units having an external peak current measuring resistor.

In particular, if a control unit is used only with source input (e.g., NXP SSL21083, which has only one source input to HVLED815, for example) to determine a current / voltage on the shunt resistor, a different approach may be used. In Fig. 3, such a control unit is shown in a configuration with a buck converter.

At the source input of the control unit shown in Fig. 3, a relatively low impedance of e.g. about 1 to 5 Ω, preferably 2.7 Ω, connected. If a relatively high negative current / negative voltage were detected by the detector at this input, the power loss would be unduly high.

Thus, the power loss is limited by significantly reducing the voltage at the detector. This is achieved by reducing the turns of, for example, the auxiliary winding to only a few turns, for example 1 to 5 turns, in particular approximately two turns. As a result, the current / voltage at the detector can be reduced, and even at a lower impedance, the power loss can be reduced.

Specifically, the control unit includes a control system having a current sense resistor for measuring a peak inductor current in time when the main switch is turned on.

In a device without PFC, the switch is generally turned off when the voltage drop across the voltage measuring resistor reaches a predetermined value. The peak current flowing through the inductor represents a known amount of energy, and this, in conjunction with a known switching frequency, forms the basis for power output control or current control.

The power factor associated with such a model tends to be poor, even when a mass storage capacitor is small. This is because the on-time can be relatively long when the mains voltage is low (during mains current values). The reason for this is that the inductor current takes longer to reach the required peak value. Consequently, the average input current is high during these times and low during the mains voltage spikes. This is exactly the opposite of the current waveform required for a high power factor.

To correct this, the detector may be added to the throttle. This is to provide a negative current / voltage while the main switch is turned on. This current / voltage is then applied to the CS input of the current sensor of the control unit via a second resistor. In Fig. 3, an example is shown in which the method has been applied to a cost-effective buck converter. Thus, Figure 3 shows a power factor corrected buck converter.

The negative current / voltage provided by the auxiliary winding varies depending on the instantaneous line voltage. When the main switch is turned on, a current flows through the resistor R3, and due to the changing negative current / voltage, the current / voltage is increased when the input current / voltage has reached its peak, and is greatly reduced in mains voltage valleys. The currents through resistor R3 conduct current away from sensing resistor R4 and thus increase the final peak current by an amount that depends on the input voltage at that time. The result is an input current that is largely constant over most of each half cycle of the line voltage, thus providing a greatly improved power factor.

Again, the resulting typical current waveform is shown in Figure 2, in this case a typical input power waveform with power factor correction.

However, existing applications require that the current sense input of the controller be disconnected from the actual current carrying terminal, as illustrated in FIG. 4, which is a typical example of an existing PFC model.

In Fig. 1, the measuring resistor R5 is not directly connected to the CS input of the current measurement of the control unit. Instead, the wire resistor R7 is connected. Thus, the impedance is sufficiently increased that the method can operate using the normal auxiliary winding present in a typical flyback converter.

By providing a separate winding, as shown in Figure 3, with a small number of turns, the method can be generalized to work with any driver IC having an external current sense resistor.

This solution is particularly suitable for down converter applications since the turns of the auxiliary winding can be easily wound around a normal drum inductor. In summary, the structure illustrated in FIG. 3 shows a very inexpensive and widely applicable power factor correction method that provides power factors of 80% to 90%, more specifically, about 85%, and a total harmonic distortion (THD) of about 25-45%, especially 30% to 40%. This structure can also be easily adapted to control units and can also be combined with the structure of Fig. 1.

Another example of an inventive circuit is shown in Fig. 5, which shows a circuit diagram for a modified PFC model. While power factor correction can be achieved in a number of ways, one common method is to supply the control unit's peak current detection circuit with a contribution from detection means via an external resistor, as indicated above.

While the switching transistor of the converter is turned on, the output from the detector is negative and proportional to the mains input voltage at that time. The supply from the detector causes the peak current reached by the primary winding to be increased by an amount proportional to the instantaneous line voltage. The contribution to the peak current actually dominates with the result that the power consumed by the converter becomes approximately sinusoidal and provides a high power factor.

In summary, the wiring to the control unit is changed to compensate for variations in the mains voltage that result in changes in the light output emitted by the at least one LED.

For this reason, a Zener diode shown in Fig. 5 is provided in the feedback path from the detection means to the converter to the control unit to clamp the negative current / negative voltage fed back to the control unit to a maximum and / or predetermined value , Above this value, the voltage remains disconnected and thus constant and changes or fluctuations outside the clamping range are disregarded. Instead of a Zener diode, the clamping can also be simplified by built-in devices of the control unit and / or the software of the control unit.

This improves the control characteristics with respect to stability of the output current / voltage of the converter, taking into account a slight decrease of the power factor as described below.

A disadvantage of the described method can be seen in that the converter output is dependent on the mains voltage. The output control is poor in terms of the variations in the input voltage. However, this can be improved by a control with only a minimal degradation of the power factor as set forth below.

As shown in Fig. 5, the original PFC was achieved by the resistor R8 connected directly between the auxiliary winding and the current measuring input of the control unit and the high-voltage side of the resistor R7. Fig. 5 now shows some additional components in the illustrated box. In particular, a shunt reference U2 of the control unit (e.g., 2.5V) clamps the voltage on the low voltage side of resistor R8 to a maximum magnitude of negative voltage, e.g. 1 to 5 V, in particular 2.5 V negative. This voltage is then applied to the current sense input of the driver IC via resistor R27.

The power factor correction is still present, but the maximum amount is limited by the claimed voltage. Thus, increases in the mains voltage can not further increase the maximum peak current.

Figures 6 and 7 show envelope waveforms of the peak currents with and without change. The positive envelope shows the peak current variation. In particular, Figure 6 shows the peak current envelope without terminals, while in Figure 7 the peak current envelope bay is shown with terminals.

In this example, the output control is improved in input voltage by a factor of about 3, while the power factor decreases slightly by about 1% to 4%, for example, from 88% to, for example, 84%.

Further, Figs. 8 and 9 show input current waveforms with and without change. As can be seen from Figures 8 and 9, there is only a very small difference in the mains input currents of the converter. In particular, FIG. 8 shows by way of example the mains input currents of the converter without terminals and a power factor of, for example, 88%, while FIG. 9 shows by way of example mains currents of the converter with terminals and a power factor of for example 84%.

Thus, the control is improved to more than about +/- 5% in the mains voltage range, while the method can be easily adapted to different control units.

Further, the method and system as described above can be improved by a modification of the circuit structure described below. The modified circuit configuration is shown in Fig. 10, the most important changes being indicated by a frame. The modified circuit construction is based on the circuit shown in Fig. 5. In particular, a selection circuit is shown in the frame.

The aim of the change is to vary an input value of the control unit so that small dimming value changes lead to an increased dimming effect at the light source. This change in the input value also makes it possible to further improve the phase-angle dimming method described above.

The change is also advantageous because it is often desirable to be able to operate a variable load on the converter module, in particular an LED driver module, for example, to be able to connect different LED types, but also to forward voltage tolerances to be able to compensate.

This is particularly important for LED retrofit driver modules, such as driver modules for MR16 LED retrofit lamps. For example. For example, it may be desired by a user to operate a variable number of LED lamps with the converter module, whereby lamps may be added or removed by the user. These lamps can have different power ratings. Because the lamps can be freely removed by the user from their sockets or placed in the sockets, it is important that even with a changing load, the remaining lamps can continue to operate normally. This means that in particular the dimming behavior of the remaining lamps does not change for the user.

However, variable load is a problem in many dimming applications, especially for low dimming dimming solutions with the above described phase gating dimming. This problem results from the fact that known dimming techniques reduce the primary-side peak current in order to achieve dimming of the light source, ie to reduce the light output emitted by the light source.

However, the resulting effect is that the power output from the converter module is reduced instead of the current when dimming down. Therefore, when the load is less than the maximum load, the load is always operated at a reduced power because the forward voltage is lower. For example, the dimmer itself must first be dimmed by a certain degree before the output of the converter module actually drops sufficiently to dimming the non-maximum load.

On the other hand, the minimum dimming value to be achieved is above that which could be achieved when the maximum load is applied. This means that at reduced load can not be dimmed down as far as it would be possible under maximum load. This results in an undesirable reduced dimming range, since the lower limit for the adjustable dimming value is increased.

In the following, therefore, a simple method is described based on the modified circuit of Fig. 10, which gradually changes between a plurality of operating modes, for example. Between two operating modes, i. E. a higher power operating mode and a lower power operating mode while reducing the dimming value using pulse width control.

The circuit in Fig. 10 in turn includes a control unit, for example, an LED driver HV LED 815 from ST Microelectronics as a control IC, which is designed as a dimmable driver for LED retrofit lamps. The selection of the operating mode is carried out by the selection circuit, which is shown outlined in Fig. 10.

For this purpose, the selection circuit has a first voltage divider, which is formed by a first resistor R3 and a second resistor R9. This first voltage divider serves to generate a replica of the supply voltage / current profile at a lower voltage. This replicated waveform is then applied as input to a regulator U2 (eg, a variable zener shunt regulator such as the Texas Instruments LM431). In particular, the input signal to the regulator U2 may be a voltage / current reference signal.

The controller U2 switches based on whether the input value is above or below a certain threshold, for example, 2.5 volts, on or off, i. a path via another voltage divider consisting of the resistors R4 and R5 becomes conductive or not.

By switching the regulator U2, the transistor Q2 is further turned on or off, whose base is connected to a midpoint of the further voltage divider. When the transistor Q2 is turned on, a gate of a FET transistor Q3 (e.g., a MOSFET) connected to the collector of the transistor Q2 is again driven. Thus, depending on the switching of the transistor Q2, the path between the drain and source of the FET transistor Q3 is turned on or non-conductive.

When the FET transistor Q3 is in a first state, for example an "on" state (ie, when the FET transistor is turned on, for example), a current path is switched via a third resistor R10, which is then connected to a The resistor R11 forms a voltage divider, a center point of the voltage divider being connected to an input of the control unit, the input signal being fed to the control unit via this input As a result, a value detected by the control unit as an input signal, for example a current sense voltage, is reduced, which causes the control unit to change to the operating mode with higher power.

When the FET transistor Q3 is in a second state, for example, an "off" state (ie, when the transistor is nonconductive), the controller detects the input signal as it is, eg, the full current sense voltage, as Input signal via the fourth resistor R11, which causes the control unit to operate in the lower power operating mode.

It should be understood that the circuit shown may also be modified so that the non-reduced input signal in the first state of the FET transistor Q3 is supplied to the control unit while the reduced, or attenuated, input signal of the control unit is supplied when the FET transistor Q3 is in the second state.

Now, if the dimming value at the dimmer is reduced and the phase angle is reduced, the FET transistor Q3 switches to the second state for each longer half-time during each half-wave of the supply voltage / the supply current. This causes the controller to operate in the higher power mode at low dimming levels for a longer time. When the dimming value is changed in the direction of the minimum dimming value, the FET transistor Q3 is mostly or always in the second state.

In summary, the illustrated solution makes it possible to assure that at a maximum dimming value, i. E. at 100% light output, the controller operates in the higher power mode of operation. The output of the converter module is therefore at or near the maximum output power. Each load is operated between its minimum and maximum power.

At low dimming values, for example, when the load is to be operated with minimum brightness, the control unit switches to the operating mode with lower power. This allows any load to diminish as much as possible. Between the maximum dimming value and the minimum dimming value, the control unit gradually changes between the at least two modes.

Therefore, the illustrated solution allows for improved dimming at low cost. The solution shown can of course also be used with other control units.

The illustrated solution also avoids the risk of choosing the wrong mode of operation for a borderline load, especially if a large supply voltage range is to be covered for the load. The solution chooses a high power operating mode for a load at a dimming value of 100% and a lower power operating mode for a load when the dimming value is close to the minimum. The illustrated circuit thus allows automatic selection between the two operating modes (high power, lower power) to increase the range in which the load can be operated.

In doing so, the solution utilizes the waveform of the voltage of the phase gating dimmer to provide pulse width control based on a reference value (e.g., voltage / current reference value). The pulse width control signal is used to switch between the higher power operating mode and the lower power operating mode during each half cycle of the supply voltage / supply current. The temporal distribution depends on the dimming value.

The invention thus allows the converter module to operate a variable number of lamps, in particular retrofit lamps, the full dimming range being available in any configuration. Therefore, when using the solution, the number of required converter module variants can be reduced because a larger power range can be covered with the converter module according to the invention.

Claims (23)

claims A converter module for dimming at least one LED, comprising - a switched / clocked converter comprising a converter switch which supplies power to the at least one LED, the converter being operated in a limit mode, - in which the converter switch is turned on in the limit mode when the input current is a predetermined threshold level, eg Reaches 0 amps - a detection device (Aux) for detecting a StronWSpannungseingabe in the converter, in particular on its primary side, and - a control unit (U1), which is suitable for changing a turn-off threshold of the converter switch in dependence of the current / the voltage, the / is detected at the detection device (Aux). The converter module of claim 1, wherein a passive bleed circuit consists of a capacitor (C10) and / or a series resistor (R10), and wherein snubber resistors (R1, R9) conductively conduct in input current / voltage paths of the capacitor Converter are connected, eg a live wire or a zero line, wherein the damping resistors (R1, R9) and / or the bleed circuit are designed so that they dampen a ringing of a radio interference suppression of the dimmer. 3. converter module according to claim 1 or 2, wherein the converter is a flyback converter. 4. Converter module according to one of the preceding claims, wherein the converter is controlled by the control unit (U1). 5. Converter module according to one of the preceding claims, wherein the detection means (Aux) is provided to switch the converter switch in dependence of the input current / voltage of the converter. 6. converter module according to one of the preceding claims, wherein the detection device (Aux) represents an auxiliary winding (Aux), which is in particular galvanically separated from a converter winding, in particular on the primary side of the converter is arranged, and wherein the detection device (Aux) a feed back the input current / input voltage of the converter indirectly or directly indicating parameter. 7. Converter module according to one of the preceding claims, wherein the control unit (U1) is a PFC fixed controller and / or a PFC fixed output controller. 8. Converter module according to one of the preceding claims, wherein a feedback signal from the detection device (Aux) to the control unit (U1) is supplied. 9. Converter module according to claim 3 and one of claims 4 to 8, wherein the detection means (Aux) is provided on the primary side of the flyback converter and a parameter to the control unit (U1) feeds back the current / voltage through the primary side of the Flyback converter indicates. The converter module according to claim 3 and one of claims 4 to 9, wherein the detection means (Aux) supplies a current / voltage in response to the mains current / voltage input to the module as a negative current / voltage to the control unit (U1), wherein the supplied reverse current / voltage indicates the current / voltage through a shunt resistor (R2) arranged in series with the converter switch, eg is built into the control unit (U1). A converter module according to claim 3 and any one of claims 4 to 10, wherein the control unit (LH) influences the input current / input voltage supplied to the converter as a function of a phase gating by changing the peak current, i. of the current / voltage varying upon turn-off of the flyback converter, and more particularly by changing the peak current / voltage so that it is substantially proportional to the current applied amplitude of the input current / voltage. 12. converter module according to claim 3 and one of claims 4 to 11, wherein in particular on the secondary side of the flyback converter, a storage capacitor (C3) is provided which is dimensioned such that it ripple on the converter module input current / the Input voltage compensates. A converter module according to any one of the preceding claims, wherein the turn-off threshold of the control unit (U1) and / or the converter switch is adaptively adjusted as a function of the input current supplied to the converter and / or the input voltage supplied to the converter to facilitate a PFC function. 14. Converter module according to claim 10 and one of claims 9 to 13, wherein in the feedback path from the detection means (Aux) to the control unit (U1), a Zener diode (Z1) is connected to the feedback to the control unit (U1) negative Current / the negative voltage to a maximum value to clamp and / or wherein the terminals within the control unit (U1) and / or by software of the control unit (U1) takes place. 15. Converter module according to one of the preceding claims, wherein the control unit (U1) an input signal via a first resistor (R7) is supplied, which by means of a selection circuit (U2), which can take at least two states, in a first state of the selection circuit (U2) is selectively connected to a further resistor (R27) to a voltage divider (R7, R27) and the input signal from the voltage divider of the control unit (Ul) is supplied. 16. The converter module according to claim 15, wherein the input signal reflects the profile of the supply voltage, which is formed by the input voltage. 17. The converter module according to claim 16, wherein the selection circuit (U2) assumes the first or a second state as a function of whether a predetermined threshold value is exceeded by a value derived from the supply voltage. 18. converter module according to claim 16, wherein the derived from the supply voltage of the size selection circuit (U2) via a voltage divider (R7, R27) is supplied. 19. The converter module of claim 15, wherein the input signal is a reference value, and wherein the reference value is reduced when the selection circuit (U2) is in the first state. 20. The converter module according to claim 19, wherein the control unit (U1) is operated in a higher power operating mode when the selection circuit (U2) is in the first state and / or the reference value is reduced. 21. The converter module according to claim 19 or claims 19 and 20, wherein the control unit (U1) is operated in a reduced power mode when the selection circuit (U2) is in the second state and / or the reference value is not reduced , 22. A method for dimming at least one LED, comprising the steps of: providing a converter module according to one of the preceding claims with an input current / input voltage controlled by a phase-controlled / triac dimmer, supplying energy to the at least one LED a switched / clocked-converter having a converter switch, wherein the converter is operated in a limit operation, wherein in the limit operation of the converter switch is turned on when the input current is a predetermined threshold level, eg 0 amps reached and - generating a holding current for the phase-locked / triac dimmer through a passive bleed circuit. 23. System with a phase-controlled / triac dimmer and a converter module according to one of claims 1 to 21.