Quick start-up circuit and method for driver circuit

Abstract

The invention relates to a quick start-up circuit and method for a self-powered single stage driver with a large energy storage snubber capacitor. An auxiliary winding for supplying power to a controller on the primary side of the transformer may include a tap winding and a selector for selecting an appropriate winding for supplying power to the controller. During an initial charging phase of the output capacitor in the start-up phase, a voltage supply capacitor of the controller is connected to the enlarged auxiliary winding, thereby applying a higher voltage to the voltage supply capacitor. Once the supply voltage reaches a maximum level, the selector switches to the tap, reducing the connected voltage.

Description

Technical Field

[0001] This invention relates to the field of power supplies for lighting systems, such as, but not limited to, solid-state lighting systems or other loads for various applications in homes, offices, retail, hospitality, and industry. Background Technology

[0002] The luminaire can be any type of lighting unit or lighting appliance, which includes one or more light sources (e.g., visible or invisible (infrared (IR) or ultraviolet (UV)) light sources) for lighting and / or communication purposes, and optionally includes other internal and / or external components required for proper operation of the lighting, such as for distributing light, for positioning and protecting the light source and ballast (where applicable), and for connecting the luminaire to a power source.

[0003] Solid-state lighting (SSL) is a type of lighting that uses semiconductor light-emitting diodes (LEDs), organic light-emitting diodes (OLEDs), or polymer light-emitting diodes (PLEDs) as the light source instead of filaments, plasma (used in arc lamps such as fluorescent lamps), or gases. Unlike incandescent bulbs (which use thermal radiation) or fluorescent tubes, SSL uses solid-state electroluminescence. Compared to incandescent lighting, SSL produces visible light with reduced heat generation and less energy dissipation.

[0004] The driver needs to provide a very stable, constant current to the luminaire, independent of changes in luminaire characteristics or supply voltage, while complying with increasingly stringent regulations covering power factor and harmonic distortion.

[0005] The basic element of a two-stage lighting driver can be a power factor correction (PFC) stage followed by a constant current (CC) driver (e.g., a flyback converter). Each stage in the driver introduces losses. If the two functions of the PFC and CC drivers are combined into a single stage, fewer components will be required and efficiency can be improved.

[0006] With only one conversion stage, single-stage drivers can significantly improve efficiency while significantly reducing component costs. Therefore, single-stage drivers for luminaires are low-cost and energy-efficient. They are widely used in the mass production of lighting products.

[0007] However, single-stage drivers suffer from high ripple current and therefore high flicker visibility measure (SVM). SVM is a measure of the probability of flicker. The visibility threshold for flicker is an SVM value equal to or greater than 1. If this value is less than 1, the flicker effect is not visible to the observer. Ripple removers are known to be used to reduce SVM, but at the cost of energy efficiency. Energy efficiency has become a hot topic in recent years. New Class A light sources must achieve an efficiency of 210 lm / W. Driver losses are one of the main factors affecting Class A light sources.

[0008] To reduce ripple, adding more storage capacitors to the switching stage can be considered. The result of adding large electrolytic capacitors is a long startup time, as the capacitor bank must be charged to a voltage level sufficient to exceed the luminaire's threshold voltage. During this process, the energy stored in the voltage supply capacitors on the primary side depletes to a low level, potentially triggering the controller's undervoltage lockout (UVLO) protection. This leads to multiple driver startup attempts and delayed light generation and / or flickering during startup. Therefore, the driver components may experience excessive stress during the startup phase. Summary of the Invention

[0009] The object of this invention is to provide a reduced startup time for a single-stage driver with a switching stage having a large storage capacitance.

[0010] This objective is achieved by the apparatus of claim 1, the driver device of claim 3, the lighting system of claim 8, the method of claim 9, and the computer program product of claim 10.

[0011] According to a first aspect, there is provided an apparatus for controlling a driver device (e.g., an electronic circuit or a (programmable) integrated circuit (e.g., an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA) or a programmable controller), the driver device having one or more output storage capacitors for supplying power to a load device, the apparatus being configured to monitor the level of a supply voltage at a voltage supply capacitor of the driver device, and to control a selector to apply a first charging current to the voltage supply capacitor when a start-up level of the supply voltage is reached, and to switch to a lower second charging current in response to detecting that the level of the supply voltage has reached a predetermined maximum level.

[0012] Furthermore, according to a second aspect, a driver device is provided, comprising the means of the first aspect and a transformer for supplying power to one or more output storage capacitors, wherein a selector is configured to select first and second charging currents from different terminals of at least one auxiliary winding of the transformer.

[0013] Furthermore, according to a third aspect, a lighting system is provided, which includes a plurality of driver devices of a second aspect connected to respective luminaires.

[0014] Additionally, according to a fourth aspect, a method is provided for controlling a driver device having an output storage capacity for supplying power to a load device, the method comprising: monitoring the level of a supply voltage at a voltage supply capacitor of the driver device; applying a first charging current to the voltage supply capacitor when a start-up level of the supply voltage has been reached; and switching to a lower second charging current in response to detecting that the level of the supply voltage has reached a predetermined maximum level.

[0015] Furthermore, according to a fifth aspect, a computer program product is provided, which includes code means for generating the steps of the method described above in the fourth aspect when run on a controller device.

[0016] Therefore, a fast startup circuit and method are provided for various types of driver devices (e.g., self-powered single-stage drivers) with large energy storage buffer capacitors. During the initial charging phase of the output capacitor in the startup phase, the voltage supply capacitor of the driver device (e.g., at the Vcc input of the controller) is supplied with an amplified charging current (e.g., from an amplified auxiliary winding), thereby applying a higher voltage to the voltage supply capacitor. Once the supply voltage reaches its maximum value, the charging current is reduced (e.g., a selector switches to a tap on the auxiliary winding or another (part) of the auxiliary winding). The auxiliary winding used to power the voltage supply capacitor on the primary side may include a tapped winding. A selector (switch) can be used to select the appropriate winding (part) for powering the voltage supply capacitor.

[0017] Therefore, rapid start-up can be achieved. As a further benefit, the tapped auxiliary winding also allows for a wider output voltage window.

[0018] According to the first option of any of the first to fifth aspects, a voltage detector (e.g., in or at the device) may be provided for measuring the supply voltage and for controlling a selector to apply a first charging current to the voltage supply capacitor when a start-up level of the supply voltage has been reached, and to switch to a lower second charging current when the measured level of the input voltage has reached a predetermined maximum level.

[0019] According to the second option of any of the first to fifth aspects that can be combined with the first option, the transformer may include at least two auxiliary windings for generating first and second charging currents, and wherein the selector is configured to select one auxiliary winding to apply a lower second charging current and select at least two auxiliary windings to apply a first charging current.

[0020] According to the third option, which can be combined with any of the first to fifth aspects, at least two auxiliary windings may include tapped windings.

[0021] According to the fourth option of any of the first to fifth aspects, which can be combined with any of the first to third options, the selector may include a controllable switch for switching between terminals of one auxiliary winding and terminals of at least two auxiliary windings in the auxiliary winding.

[0022] According to the fifth option, which can be combined with any of the first to fifth aspects, the driver circuit can be a single-stage flyback LED driver.

[0023] It should be noted that the above-mentioned devices may be implemented based on discrete hardware circuits having discrete hardware components, integrated chips or chip modules arranged, or based on signal processing devices or chips controlled by software routines or programs stored in memory, written on computer-readable media or downloaded from a network (such as the Internet).

[0024] It should be understood that the apparatus of claim 1, the driver circuit of claim 3, the lighting system of claim 8, the method of claim 9, and the computer program product of claim 10 may have similar and / or identical preferred embodiments, particularly as defined in the dependent claims.

[0025] It should be understood that the preferred embodiments of the present invention may also be any combination of the dependent claims or the above embodiments with the corresponding independent claims.

[0026] These and other aspects of the invention will become apparent and elucidated with reference to the embodiments described below. Attached Figure Description

[0027] In the following figures:

[0028] Figure 1 A block diagram of a luminaire driver with fast-start circuit control according to various embodiments is shown schematically;

[0029] Figure 2 The waveform of the Vcc startup voltage of a lamp driver with a large storage capacitor is schematically shown.

[0030] Figure 3 A circuit diagram of an example of an enhanced single-stage flyback LED driver with a fast-start circuit according to one embodiment is shown schematically.

[0031] Figure 4 schematically showing having Figure 3 The waveform of the Vcc startup voltage of the enhanced single-stage flyback LED driver in the fast-start circuit shown; and

[0032] Figure 5A flowchart of a fast driver startup process according to various embodiments is shown. Detailed Implementation

[0033] Various embodiments of the present invention are now described, which can be applied to luminaires in solid-state lighting systems, such as semiconductor LEDs, semiconductor lasers, vertical-cavity surface-emitting lasers (VCSELs), organic light-emitting diodes (OLEDs), or polymer light-emitting diodes (PLEDs), as illumination sources or light sources in the visible or non-visible spectrum.

[0034] More specifically, the following embodiments relate to LED luminaires. They can be implemented using any type of LED module or board and can be applied to various LED drivers or luminaire converters.

[0035] Figure 1 A block diagram of a luminaire driver with fast-start circuit control according to various embodiments is shown schematically.

[0036] Note that throughout this disclosure, the structure and / or function of blocks or circuit components with the same reference numerals as previously described are not described again unless specific additional functionality is involved. Furthermore, only those structural elements and functions useful for understanding the embodiments are shown. For brevity, other structural elements and functions are omitted.

[0037] Power supply AC voltage V AC (For example, a mains voltage of 110 or 220V at a mains frequency of 50 or 60Hz) is provided to an electromagnetic interference (EMI) filter 10, which is an electronic device that attenuates electromagnetic interference from the power system to limit noise in the system and reduce the risk of lamp driver failure.

[0038] The filtered AC voltage is then supplied to rectifier stage (RECT) 20, which is an electronic device that converts the transformed AC voltage into DC voltage using one or more rectifier elements (e.g., diodes or other valve elements) that allow current to flow in only a single direction. In one example, the rectifier stage could be a full-bridge rectifier stage.

[0039] The rectified DC voltage is supplied to the high-voltage start-up (HVSU) circuit 30, which is configured to provide a sufficient level of current to the supply voltage (Vcc) terminal of the switching stage (SW CTRL) 40 upon turn-on, allowing the Vcc power supply capacitor to charge rapidly and enabling the driver system to start. This avoids the need for a start-up resistor, which wastes power and introduces a significant delay during startup at low line voltages. The high-voltage start-up circuit 30 may be integrated into the switching stage 40.

[0040] The converter stage of the luminaire driver can be configured as an isolated power converter and may include the switching section of the switching stage 40, magnetic components (inductors / transformers), the converter output section (rectifier section) (CONV) 60, and the controller ( Figure 1 (Not shown in the image).

[0041] The switching stage 40 is configured to control the converter output section 60 of the converter stage via the electronic transformer (TRA) 50 to provide the desired power level to the LED luminaire 70. The converter stage can be a flyback converter, a forward converter, a resonant converter, etc.

[0042] When the supply voltage Vcc at the terminals of the switching stage 40 reaches a predetermined start-up level (e.g., 15V), all internal functions of the switching stage 40 begin to operate to provide drive pulses to the converter output section 60. At this time, the (tapped) auxiliary winding on the primary side of the transformer 50 can provide the required operating voltage to the switching stage 40 via the selector (SEL) 80.

[0043] Selector 80 can be implemented as a controllable semiconductor switching circuit. In one example, selector 80 can be a simple switching element for selecting one of at least two terminals of an auxiliary winding to control / regulate the level of the operating voltage supplied to the Vcc terminal of switching stage 40. The selection process of selector 80 is controlled by voltage detector (V-DET) 90, which is configured to measure the supply voltage at the Vcc terminal of switching stage 40 and control selector 80 in response to the detected supply voltage level. The measurement or detection operation of voltage detector 90 can be based on a resistor divider and / or comparator function that generates a control signal for selector 80 if one or more predetermined levels of the supply voltage have been reached.

[0044] As described above, the switching stage 40, transformer 50, and converter output section 60 are configured to operate as an electrical power conversion device (power converter) that regulates the power supplied to the LED luminaire 70 and can respond to changes in the LED luminaire 70's electrical characteristics, such as those changing with temperature, by providing a constant amount of power to the LED luminaire 70. Therefore, a very specific electrical power can be supplied to the LED luminaire 70 for proper operation. If the voltage supplied to the LED luminaire 70 is lower than the required voltage, very little current flows through the LED junction, resulting in low brightness and poor performance. On the other hand, if the voltage is too high, too much current flows through the LED junction, and it may overheat and be severely damaged or completely fail (thermal runaway). This, of course, also applies to other types of luminaires or other load devices.

[0045] Figure 2It schematically shows the absence of Figure 1 A waveform of the Vcc startup voltage of a conventional lamp driver with a large storage capacitor (e.g., at the converter stage) for voltage detector 80 and selector 90.

[0046] like Figure 2 As shown, during startup, the Vcc capacitor at the voltage supply terminal of the switching stage is first charged by a high-voltage startup circuit. This can be a high-voltage junction field-effect transistor (JFET) startup circuit (which can be integrated into the controller of the switching stage itself). When the voltage reaches the startup level Vcc (e.g., 20V), the controller of the switching stage begins to operate and draws current from the Vcc capacitor. As a result, the Vcc supply voltage will drop because the current drawn by the controller is much higher than the high-voltage startup current (typically a few mA). At this time, the output voltage of the luminaire is still at a very low level and the Vcc capacitor cannot be charged through the auxiliary winding of the transformer. Therefore, Vcc will continue to drop until it reaches the UVLO level (e.g., 6V), and the controller is disabled for a certain amount of time. Then, the Vcc capacitor is charged again by the high-voltage startup circuit, and the cycle repeats. Depending on the size of the storage capacitor in the converter stage, multiple startup attempts may be required to achieve stable operation. Due to the low startup current of the high-voltage startup circuit, the startup delay is longer at lower mains voltages (e.g., 120V).

[0047] Therefore, the Vcc startup voltage of the luminaire driver with a large storage capacitor shows multiple startup attempts, which delays the luminaire startup process.

[0048] According to various embodiments, the combination of the tapped auxiliary winding on the primary side of transformer 50 with voltage detector 90 and selector 80 is as follows: Figure 1 The LED driver provides a fast start-up circuit. During the initial charging phase of the storage capacitor in the converter output section 60 during the start-up phase, the Vcc capacitor of the switching stage 40 can be charged via selector 80 in the entire or a larger portion of the auxiliary winding (T). H The output voltage is supplied at the point where the voltage detector 90 detects the Vcc capacitor, thus providing the highest possible voltage for rapid charging. Once the Vcc voltage detected by the voltage detector 90 reaches its maximum value or a predetermined upper limit, the selector 80 switches to a smaller portion of the tap or auxiliary winding, providing a lower voltage. Therefore, rapid start-up can be achieved without reaching the UVLO level. Furthermore, the variable auxiliary winding allows for a very wide output voltage window.

[0049] Figure 3A more detailed circuit diagram of an example of an enhanced single-stage flyback LED driver with a fast-start circuit according to an embodiment is schematically shown. Thus, a high-efficiency LED driver with a fast-start circuit can be obtained for large energy storage on the secondary side.

[0050] like Figure 3 As shown, the exemplary single-stage driver is based on a flyback topology with a high power factor. It is supplied with a mains voltage V. AC The circuit includes: an EMI filter circuit 10 with an inductor L1 and two capacitors C2 and C3 at the input; a rectifier bridge with four diodes D1 to D4; a transformer with multiple windings T1-1, T1-2, T1-3, and T1-4; and a switching stage with a power metal-oxide-semiconductor FET (MOSFET) M1 and a controller (CTRL) 42. The output converter circuit (flyback circuit) that generates the output voltage Vo for the LED lamp D8 includes a diode D5 and a (large) capacitor bank 62 with (electrolytic) capacitors C4, C6, C7, etc., connected in parallel.

[0051] Alternatively, a ripple remover (RR) circuit 22 can be provided, which can be configured to reduce the peak-to-peak amplitude of the converter output current by removing output ripple through a linear post-regulator, thereby minimizing LED current ripple. A simple circuit solution could be a self-biased emitter follower circuit. A Darlington configuration can be used to keep the base resistor impedance relatively high, allowing a small capacitor to be used to filter the ripple frequency (e.g., 100Hz). This circuit can use an NPN transistor placed at the output voltage terminal or a PNP transistor placed at the ground terminal. The losses in the ripple remover depend on the size of the energy storage buffer capacitor. Therefore, the efficiency of the ripple remover circuit 22 can be improved by adding more capacitors to the capacitor bank 62.

[0052] For ease of layout in terms of energy efficiency and creepage distance (i.e., the shortest distance between two conductive parts along the surface of a solid insulating material), self-powered Vcc circuits are advantageous. For example... Figure 3 As shown, the Vcc supply voltage is self-powered through auxiliary windings T1-3 and T1-4 on the mains transformer itself. An auxiliary voltage supply via a stand-alone switch-mode power supply (SMPS) would introduce additional losses and require additional space to meet creepage distances as defined in, for example, standard IEC 61347-1.

[0053] Due to low-frequency ripple and supply voltage variations, high power factor (PF) topologies typically use diode conduction phase to provide Vcc capacitor C5 on the primary side of the transformer, which is attributed to the stable voltage at the output.

[0054] like Figure 3As shown, when diode D5 of the flyback circuit at the output is turned on (i.e., MOSFET M1 is turned off), the output voltage is reflected / coupled to the auxiliary windings T1-3 and T1-4 at a fixed turns ratio of the transformer (i.e., the number of turns of the winding on the input side (primary side) of the transformer relative to the number of turns of the winding on the output side (secondary side). Therefore, the voltage supplied to capacitor C5 of Vcc is directly related to the output voltage Vo across the storage capacitor (i.e., capacitor bank 62).

[0055] The proposed tapped auxiliary winding with windings T1-3 and T1-4 and tap T allows for a very wide output voltage window because the Vcc power supply is now connected via terminal T. H and T L The corresponding decoupling diodes D6 and D7, along with the selector 80 controlled by the voltage detector 90, are connected to the voltage from one or both auxiliary windings T1-3 and T1-4. The selector 80 can be configured as a selection switch S1, which connects to the higher voltage terminal T in response to a control signal provided by the voltage detector 90. H (Both auxiliary windings T1-3 and T1-4) or lower voltage terminal T L (Auxiliary winding T1-3 only).

[0056] In an exemplary design where auxiliary windings T1-3 and T1-4 have equal numbers of turns, the driver output voltage window can be extended by a factor of 2. Figure 4 schematically showing having Figure 3 The waveform diagram shows the startup voltage of the enhanced single-stage flyback LED driver with the fast startup circuit shown.

[0057] exist Figure 3 In this embodiment, the Vcc capacitor C5 is initially charged with the voltages of the auxiliary windings T1-3 and T1-4. If the auxiliary windings T1-3 and T1-4 are configured to have equal numbers of turns, this provides a much higher voltage for charging the Vcc capacitor C5, effectively doubling the voltage. Therefore, the Vcc supply voltage drops to the UVLO level, preventing triggering of protective measures. Due to the higher reflected self-feedback voltages from the two auxiliary windings T1-3 and T1-4, the Vcc capacitor C5, initially charged via the high-voltage start-up circuit 20, will now be charged by the higher reflected voltage from the secondary side of the transformer, achieving a smooth start-up.

[0058] like Figure 4 As shown, the Vcc capacitor C5 is initially charged by the output current of the high-voltage startup circuit 20 until it reaches the startup voltage level Vccs and activates the controller 42. In response, the controller 42 is activated, the Vcc capacitor C5 is discharged by the input current of the controller 42, and simultaneously discharged through the higher voltage terminal T connected to the auxiliary windings T1-3 and T1-4.H The increased self-reflected voltage at the capacitor bank 62 causes the reflected voltage to increase with the output voltage Vo, thus preventing the UVLO level from being reached due to the higher reflected portion of the output voltage Vo.

[0059] Voltage detector 90 monitors the Vcc supply voltage level at capacitor C5, and once it reaches the predetermined maximum level Vcc_max, switch S1 of selector 80 switches from the default position 1 (terminal T). H Switch to position 2 (terminal T) L Under steady-state conditions, a lower voltage is supplied to capacitor C5 at the auxiliary winding T1-3. As a result, Figure 4 The waveform decreases until it reaches a steady state below the maximum level Vcc_max. This avoids overvoltage at the Vcc capacitor C5 and the Vcc input of the controller 42. The initial high reflected voltage from the two auxiliary windings is too high for steady-state operation.

[0060] As an alternative, instead of auxiliary windings T1-3 and T1-4, the voltage doubler circuit or other boost circuit can be controlled by selector 80 (e.g., enable, disable). The voltage doubler can be configured to activate when Vcc capacitor C5 is charged to a first level (i.e., ...). Figure 3 The voltage divider provides a dual charging current at Vcc and can be deactivated by selector 80 under the control of voltage detector 90. Therefore, selector 80 can then be arranged to control (e.g., enable, disable) the voltage divider.

[0061] Figure 5 A flowchart illustrating a fast driver startup process for a luminaire driver according to various embodiments is shown. This process can be stored in a controller (e.g., Figure 3 Controller 42 or Figure 1 The switch stage 40 controller's memory includes a function for controlling the controller to trigger and / or execute. Figure 5 The steps are implemented by a software routine of instructions.

[0062] When the voltage level Vccs has been reached at the Vcc terminal of the controller (e.g., via a high-voltage start-up circuit), step S300 of the program is triggered, and the Vcc capacitor at the Vcc input terminal of the controller is initially charged with an increased charging current. This can be achieved by controlling a selector or switch (e.g., Figure 1 or Figure 3 Selector 80) is connected to the increased self-powered reflected voltage (e.g., the larger or two or more auxiliary windings of the transformer of the lamp driver). Figure 3This can be achieved by using T1-3 and T1-4 in the circuit or by increasing the external voltage. Due to the higher charging current, the Vcc capacitor will be charged faster to achieve a smooth driver startup.

[0063] In step S301, the level of the Vcc supply voltage is monitored by the controller's voltage detection function or by the readout process of an external voltage detector. Then, in step S302, the detected or read Vcc voltage level is compared with a predetermined maximum level (e.g., ...). Figure 4 It compares the voltage level with Vcc_max in the table and checks whether the detected or read voltage level has reached the predetermined maximum level.

[0064] If effective (i.e., the maximum level is reached), the process continues to step S303, and the selector or switch is controlled to reduce the charging current of the Vcc capacitor by switching to a smaller or single or fewer auxiliary windings or switching to a smaller externally supplied charging current to avoid overvoltage at the Vcc terminal of the controller.

[0065] Otherwise (i.e., the maximum level has not yet been reached), the process jumps back to step S301 and continues to monitor the detected or read Vcc voltage level until the maximum level is reached.

[0066] In summary, a fast startup circuit and method for a self-powered single-stage driver with a large energy storage buffer capacitor have been described. The auxiliary winding for supplying power to the controller on the primary side of the transformer may include a tapped winding and a selector for selecting the appropriate winding to supply power to the controller. During the initial charging phase of the output capacitor in the startup phase, the controller's voltage supply capacitor is connected to the expanded auxiliary winding, thereby applying a higher voltage to the voltage supply capacitor. Once the supply voltage reaches its maximum level, the selector switches to tapped mode, thereby reducing the connected voltage.

[0067] While the invention has been detailed and described in the accompanying drawings and the foregoing description, such description should be considered illustrative or exemplary rather than limiting. The invention is not limited to the disclosed embodiments relating to solid-state luminaires (e.g., LED luminaires). The proposed feedforward balancing control can be applied in conjunction with any type of load sensitive to output ripple.

[0068] By studying the accompanying drawings, the disclosure, and the appended claims, those skilled in the art can understand and implement other variations of the disclosed embodiments in practicing the claimed invention. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. A single processor or other unit can implement the functions of several items as described in the claims. The fact that certain measures are recited in mutually different dependent claims does not mean that combinations of these measures cannot be advantageously used. The foregoing description details certain embodiments of the invention. However, it should be understood that the invention can be practiced in many ways, however detailed the foregoing may be, and is therefore not limited to the disclosed embodiments. It should be noted that the use of particular terms when describing certain features or aspects of the invention should not be construed as implying that the term is redefined herein as limited to any particular feature of the invention that includes the feature or aspect of the invention associated with that term.

[0069] A single unit or device can perform the functions of several items as described in the claims. The fact that certain measures are described in mutually different dependent claims does not mean that combinations of these measures cannot be used advantageously.

[0070] and Figure 5 The processes illustrated can be implemented as program code devices for computer programs and / or dedicated hardware for receiver or transceiver devices. Computer programs can be stored and / or distributed on suitable media, such as optical storage media or solid-state media, provided with or as part of other hardware, but can also be distributed in other forms, such as via the Internet or other wired or wireless telecommunications systems.

Claims

1. A driver device comprising means (40; 42) for controlling the driver device, the driver device having one or more output storage capacitors (62) for supplying power to a load device (70), the means being configured to monitor the level of a supply voltage at a voltage supply capacitor (C5) of the driver device, and to control a selector (80) to apply a first charging current to the voltage supply capacitor (C5) when a start-up level (Vccs) of the supply voltage has been reached, and to switch to a lower second charging current in response to detecting that the level of the supply voltage has reached a predetermined maximum level (Vcc_max). The driver device includes a transformer (50) for supplying power to the one or more output storage capacitors (62), wherein a selector (80) is configured to select a first charging current and a second charging current from different terminals of at least one auxiliary winding (T1-3, T1-4) of the transformer (50), wherein the transformer (50) includes at least two auxiliary windings (T1-3, T1-4) for generating the first charging current and the second charging current, and wherein the selector (80) is configured to select one of the auxiliary windings (T1-3, T1-4) to apply the lower second charging current, and to select at least two of the auxiliary windings (T1-3, T1-4) to apply the first charging current.

2. The driver device according to claim 1, wherein the means includes a voltage detector (90) for measuring the supply voltage and for controlling the selector (80) to apply the first charging current to the voltage supply capacitor (C5) when the start-up level (Vccs) of the supply voltage has been reached, and to switch to the lower second charging current when the level of the measured input voltage has reached the predetermined maximum level (Vcc_max).

3. The driver device according to claim 1, wherein the at least two auxiliary windings (T1-3, T1-4) include tapped windings.

4. The driver device according to any one of the preceding claims, wherein the selector (80) comprises a controllable switch (S1) for a terminal (T) of one of the auxiliary windings (t1-3) in the auxiliary windings (T1-3, T1-4). H T L ) and the terminals (T) of at least two of the auxiliary windings in the auxiliary windings (T1-3, T1-4). H T L Switch between ) 5. The driver device according to any one of the preceding claims, wherein the driver device is a single-stage flyback LED driver.

6. A lighting system comprising a plurality of driver devices according to claim 5 connected to respective luminaires (70).

7. A method for controlling a driver device having an output storage capacity (62) for supplying power to a load device (70), the method comprising: Monitor the level of the supply voltage at the voltage supply capacitor of the driver device; When the start-up level of the supply voltage has been reached, a first charging current is applied to the voltage supply capacitor; as well as In response to detecting that the supply voltage level has reached a predetermined maximum level, a lower second charging current is switched.

8. A computer program product comprising, when run on a controller device (42), code means for generating the steps of claim 7.

Images