Resonant hybrid flyback converter for led-based loads

Abstract

A resonant hybrid flyback converter (10) for an LED-based load (13c) is provided. The resonant hybrid flyback converter (10) includes: a half bridge (11) including a high side switch (11a) and a low side switch (11b); a flyback resonant tank (12) comprising a transformer having a primary side (15a) and a secondary side (15b); and a processing unit (14). In this context, the half-bridge (11) is configured to supply power to the primary side (15a), with the secondary side (15b) being configured to supply power to the LED-based load (13c). In addition, the processing unit (14) is configured to sense an LED voltage with respect to the LED-based load (13c) and / or a half-bridge current with respect to the primary side (15a). In addition to this, the processing unit (14) is configured to control the on-time of the low-side switch (11b) based on the LED voltage.

Description

[0001] The present invention relates to a resonant hybrid flyback converter for an LED-based load. In this context, it should be noted that "hybrid flyback" can be particularly understood as "a half-bridge circuit supplying power to a flyback resonant tank".

[0002] Generally speaking, in the situation where LED lighting devices are increasingly used in many different fields of life, there is an increasing need for resonant hybrid flyback converters for LED-based loads, systems including such resonant hybrid flyback converters and LED-based loads, and methods for operating resonant hybrid flyback converters for LED-based loads, in order to ensure an effective and reliable power supply for the LED-based load, especially in terms of improved flicker during load transitions and a smaller peak-to-peak magnetizing current.

[0003] However, no resonant hybrid flyback converter allows for such improvements, especially in terms of improved flicker during load transitions and a smaller peak-to-peak magnetizing current.

[0004] Therefore, there is an object of providing a resonant hybrid flyback converter for an LED-based load, a system including such a resonant hybrid flyback converter and an LED-based load, and a method for operating a resonant hybrid flyback converter for an LED-based load, so as to ensure high efficiency and reliability, especially in terms of improved flicker during load transitions and a smaller peak-to-peak magnetizing current.

[0005] This object is solved by the features of the first independent claim for a resonant hybrid flyback converter for an LED-based load, the features of the second independent claim for a system including such a resonant hybrid flyback converter and an LED-based load, and the features of the third independent claim for a method for operating a resonant hybrid flyback converter for an LED-based load. The dependent claims contain further development results.

[0006] According to a first aspect of the present invention, there is provided a resonant hybrid flyback converter for an LED-based load. The resonant hybrid flyback converter includes: a half-bridge including a high-side switch and a low-side switch; a flyback resonant tank including a transformer having a primary side and a secondary side; and a processing unit. In this context, the half-bridge is configured to supply power to the primary side, wherein the secondary side is configured to supply power to the LED-based load. Additionally, the processing unit is configured to sense an LED voltage regarding the LED-based load and / or a half-bridge current regarding the primary side. In addition to this, the processing unit is configured to control the on-time of the low-side switch based on the LED voltage. Advantageously, this allows ensuring high efficiency and reliability, especially in terms of improved flicker during load transitions and smaller peak-to-peak magnetizing current.

[0007] According to a first preferred embodiment of the first aspect of the present invention, the processing unit is configured to control the on-time of the high-side switch based on peak detection regarding the half-bridge current, wherein the processing unit is particularly configured to adjust an operating point regarding controlling the on-time of the high-side switch based on controlling the on-time of the low-side switch. Advantageously, for example, not only can the efficiency be further increased, but also the reliability can be further increased.

[0008] According to a second preferred embodiment of the first aspect of the present invention, the processing unit is configured to control the on-time of the low-side switch such that, in the case of an increase in the LED voltage, the on-time of the low-side switch particularly decreases in a linear, non-linear, continuous, stepwise or ramp manner. Advantageously, for example, this allows an operating point outside a certain output window or a wider operating range, respectively.

[0009] According to a further preferred embodiment of the first aspect of the present invention, the processing unit is configured to control the on-time of the high-side switch such that, in the case of an increase in the LED voltage, the on-time of the high-side switch particularly increases in a linear, non-linear, continuous, stepwise or ramp manner. Advantageously, for example, both the efficiency and the reliability can be further increased.

[0010] According to a further preferred embodiment of the first aspect of the present invention, in the case of a stepwise decrease in the on-time of the low-side switch, the on-time of the high-side switch increases in a ramp-shaped manner. Advantageously, for example, a corresponding LED voltage range can be divided into different operating regions, wherein each of the different operating regions includes a respective constant on-time of the low-side switch.

[0011] According to a further preferred embodiment of the first aspect of the invention, in the case of a linearly decreasing on-time of the low-side switch, the on-time of the high-side switch increases in a non-linear manner, in particular over a substantial part of the voltage range with respect to the LED voltage. Advantageously, for example, in order to avoid an "uncontrolled back-and-forth" adjustment of the on-time of the low-side switch at the stable operating point, a hysteresis mode can preferably be implemented by the processing unit.

[0012] According to a further preferred embodiment of the first aspect of the invention, in the case of a non-linearly decreasing on-time of the low-side switch, the on-time of the high-side switch increases linearly. Advantageously, for example, this allows for an on-time of the low-side switch that exhibits a flatter slope at high LED voltages. Further advantageously, the efficiency can be further increased, in particular in the sense of a more flexible design of the magnetic resonance tank and an easily implementable and feasible mode.

[0013] According to a further preferred embodiment of the first aspect of the invention, the resonant hybrid flyback converter or the processing unit comprises a control element, preferably a proportional-integral control element, wherein the peak detection is based on a controlled variable received from the control element, preferably the proportional-integral control element. Advantageously, for example, a high accuracy and rapidity of the corresponding control can be ensured.

[0014] According to a further preferred embodiment of the first aspect of the invention, the processing unit is configured to sense the LED current with respect to the LED-based load, wherein the control element, preferably the proportional-integral control element, is configured to form a controlled variable based on the LED current and a target LED current that can be specifically set. Advantageously, for example, the target LED current can be set by the user, especially during operation.

[0015] According to a further preferred embodiment of the first aspect of the invention, the processing unit is configured to sense the on-time of the high-side switch. In addition or as an alternative, the processing unit is configured to control the on-time of the low-side switch based on the on-time of the high-side switch. Advantageously, for example, the reliability can be further increased, thereby also reducing inefficiencies.

[0016] According to a further preferred embodiment of the first aspect of the invention, the processing unit is configured to limit the step size of a corresponding step, preferably according to at least two maximum step sizes, during a change in the on-time of the low-side switch, in particular during the start-up phase of the resonant hybrid flyback converter.

[0017] Advantageously, for example, when operating the LED module at significantly different LED voltages, different maximum step sizes are applied, particularly during the startup phase. In this context, it should be noted that without applying such a configuration, when operating the LED module at different LED voltages, the same relatively large step size will always be applied, and during the corresponding step, there will be an overcurrent that will significantly exceed the LED current ripple during operation.

[0018] According to a further preferred embodiment of the first aspect of the invention, the processing unit is configured to apply the maximum of at least two maximum step sizes as long as the corresponding current is below a limit value, preferably a predefined limit value, based on the setpoint of the corresponding LED current. In addition or alternatively, the at least two maximum step sizes comprise or are at least two predefined maximum step sizes. Further additionally or further alternatively, the step size, particularly in the startup phase, limiting the corresponding step is adjusted in such a way that the resulting current spike does not exceed or substantially does not exceed the current ripple present during normal LED operation.

[0019] Advantageously, for example, the closer the corresponding adjustment is to the actual LED voltage, the smaller the step size, particularly the step size whose maximum value is limited, becomes. Thus, the processing unit can be configured to apply a reduced step size or the minimum of at least two maximum step sizes depending on the proximity of the corresponding adjustment to the actual LED voltage.

[0020] Regarding the above-mentioned limit value or predefined limit value, it should be noted that it may be particularly advantageous if the limit value or predefined limit value is, respectively, 0.9 times, preferably 0.85 times, more preferably 0.8 times, and most preferably 0.75 times the setpoint of the corresponding LED current.

[0021] Furthermore, regarding the above-mentioned term "substantially does not exceed", it should be noted that "substantially" can particularly be understood as a corresponding deviation of not more than 10%, preferably not more than 5%, more preferably not more than 3%, and most preferably not more than 1%.

[0022] According to a second aspect of the invention, a system is provided. The system comprises a resonant hybrid flyback converter according to any preferred embodiment of the first aspect of the invention or of the preferred embodiments of the first aspect of the invention, and an LED-based load powered by the resonant hybrid flyback converter. Advantageously, this allows ensuring high efficiency and reliability, particularly in terms of improved flicker during load transitions and smaller peak-to-peak magnetizing current.

[0023] According to a third aspect of the present invention, there is provided a method for operating a resonant hybrid flyback converter for an LED-based load (in particular a resonant hybrid flyback converter according to any preferred embodiment of the first aspect of the present invention or any preferred embodiment of the preferred specific form of the first aspect of the present invention). The method comprises the steps of: sensing an LED voltage with respect to the LED-based load and / or a half-bridge current on the primary side of a transformer of a flyback resonant tank of the resonant hybrid flyback converter, the primary side being powered by a half-bridge comprising a high-side switch and a low-side switch, the resonant hybrid flyback converter comprising the half-bridge; and controlling the on-time of the low-side switch based on the LED voltage. Advantageously, this allows ensuring high efficiency and reliability, in particular in terms of improved flicker and smaller peak-to-peak magnetizing current during load transitions.

[0024] According to a first preferred embodiment of the third aspect of the present invention, the method further comprises the steps of: controlling the on-time of the high-side switch based on peak detection of the half-bridge current, and in particular adjusting an operating point for controlling the on-time of the high-side switch based on controlling the on-time of the low-side switch. Advantageously, for example, not only can the efficiency be further increased, but also the reliability can be further increased.

[0025] According to a second preferred embodiment of the third aspect of the present invention, the method further comprises the steps of: controlling the on-time of the low-side switch such that, in the case of an increasing LED voltage, the on-time of the low-side switch decreases in particular in a linear, non-linear, continuous, stepwise or ramp manner. Advantageously, for example, this allows an operating point outside a certain output window or a wider operating range, respectively.

[0026] According to a further preferred embodiment of the third aspect of the present invention, the method further comprises the steps of: controlling the on-time of the high-side switch such that, in the case of an increasing LED voltage, the on-time of the high-side switch increases in particular in a linear, non-linear, continuous, stepwise or ramp manner. Advantageously, for example, both the efficiency and the reliability can be further increased.

[0027] According to a further preferred embodiment of the third aspect of the present invention, the method further comprises the steps of: restricting the step size of a corresponding step, in particular during a start-up phase of the resonant hybrid flyback converter, preferably according to at least two maximum step sizes, during a change in the on-time of the low-side switch.

[0028] Advantageously, for example, when operating the LED module at significantly different LED voltages, different maximum step sizes are applied, particularly during the startup phase. In this context, it should be noted that without applying such a configuration, when operating the LED module at different LED voltages, the same relatively large step size will always be applied, and during the corresponding step, there will be an overcurrent that will significantly exceed the LED current ripple during operation.

[0029] According to a further preferred embodiment of the third aspect of the present invention, the method further comprises the step of applying the largest of at least two maximum step sizes as long as the corresponding current is below a limit value, preferably a predefined limit value, based on the setpoint of the corresponding LED current. Additionally or alternatively, the at least two maximum step sizes comprise or are at least two predefined maximum step sizes. Further additionally or further alternatively, the step size, particularly in the startup phase, is adjusted in such a way that the resulting current spike does not exceed or substantially does not exceed the current ripple present during normal LED operation.

[0030] Advantageously, for example, the closer the corresponding adjustment is to the actual LED voltage, the smaller the step size, particularly the step size whose maximum value is limited. Thus, the method may comprise the step of applying a reduced step size or the smallest of at least two maximum step sizes based on the proximity of the corresponding adjustment to the actual LED voltage.

[0031] It should be noted that all the explanations or further embodiments according to the first aspect of the present invention similarly apply to the third aspect of the present invention.

[0032] The exemplary embodiments of the present invention will now be further explained by way of example and not limitation with reference to the accompanying drawings. In the drawings:

[0033] Figure 1 An exemplary embodiment combining the first aspect and the second aspect of the present invention is shown;

[0034] Figure 2 An abstract illustration of the first and second aspects of the present invention is shown, particularly for more detailed explanation of the corresponding functions;

[0035] Figure 3 A first exemplary diagram showing the low-side switch conduction time and the high-side switch conduction time at different LED voltages is shown;

[0036] Figure 4 A second exemplary diagram showing the low-side switch conduction time and the high-side switch conduction time at different LED voltages is shown;

[0037] Figure 5Shows a third exemplary diagram of the low-side switch conduction time and the high-side switch conduction time at different LED voltages;

[0038] Figure 6 Shows an exemplary diagram of the voltage across the transformer over time;

[0039] Figure 7 Shows respectively for Figure 1 or Figure 2 An exemplary circuit diagram of a further illustration;

[0040] Figure 8 Illustrates an exemplary embodiment of a step limit related to a time interval; and

[0041] Figure 9 Shows a flowchart of an embodiment of the third aspect of the present invention.

[0042] Regarding Figure 1 An exemplary embodiment of the resonant hybrid flyback converter 10 of the present invention for an LED-based load (exemplarily LED (light emitting diode) 13c) is depicted.

[0043] For the sake of completeness, it should be noted that the Figure 1 Additionally shows an exemplary embodiment of the system 200 of the present invention, which includes the resonant hybrid flyback converter 10 and the LED-based load (exemplarily the LED 13c) powered by the resonant hybrid flyback converter 10.

[0044] According to Figure 1 The resonant hybrid flyback converter 10 includes a half-bridge 11, which includes a high-side switch (exemplarily a first field-effect transistor 11a) and a low-side switch (exemplarily a second field-effect transistor 11b).

[0045] Regarding the field-effect transistors 11a and 11b, it should be noted that the transistors are exemplarily n-channel enhancement type.

[0046] Furthermore, the resonant hybrid flyback converter 10 includes a flyback resonant tank 12, which includes a transformer having a primary side 15a and a secondary side 15b. It should be noted that the half-bridge 11 is configured to supply power to the primary side 15a, and the secondary side 15b is configured to supply power to an LED-based load (exemplarily the LED 13c).

[0047] In addition, the above-mentioned primary side 15a includes a series connection of a leakage inductance 12b, a corresponding main transformer inductance 12d, and a capacitor 12c (exemplarily a resonant capacitor), and the leakage inductance may be optional or omissible respectively. In this context, it should be noted that, as mentioned hereinafter, the half-bridge current particularly flows through the series connection.

[0048] As can be seen from Figure 1 It can also be seen that the resonant hybrid flyback converter 10 further includes a power supply device 13, which is configured to be powered by the secondary side 15b and supply power to an LED-based load or an LED 13c respectively.

[0049] In this context, the power supply device 13 includes a switch and / or a diode (exemplarily a diode 13e) and a capacitor (exemplarily an output capacitor 13g).

[0050] In addition, the capacitor 13g is exemplarily connected in parallel to the LED 13c, while the diode 13e is exemplarily connected in series to the parallel connection of the LED 13c and the capacitor 13g.

[0051] Specifically, the first terminal of the transformer secondary inductance 13d is connected to the first terminal (exemplarily the anode terminal) of the diode 13e, and the second terminal (exemplarily the cathode terminal) of the diode 13e is connected to the first terminal of the capacitor 13g and the first terminal of the LED 13c.

[0052] In addition, the second terminal of the transformer secondary inductance 13d is connected to the second terminal of the capacitor 13g and the second terminal of the LED 13c. The second terminal of the LED 13c is exemplarily connected to a first voltage potential, preferably to ground, more preferably to the ground 13f of the secondary side 15b.

[0053] Similarly, regarding the half-bridge 11, it should be noted that the first terminal (exemplarily the drain terminal) of the first field-effect transistor 11a is connected to a second voltage potential (preferably the supply voltage 11c), wherein the second terminal (exemplarily the source terminal) of the first field-effect transistor 11a is connected to the first terminal (exemplarily the drain terminal) of the second field-effect transistor 11b. Additionally, the second terminal (exemplarily the source terminal) of the second field-effect transistor 11b is connected to a third voltage potential, preferably to ground, more preferably to the ground 11d of the primary side 15a.

[0054] Regarding the above series connection with respect to the primary side 15a or the resonant tank 12 respectively, it should be noted that the first terminal (exemplarily the drain terminal) of the second field-effect transistor 11b is connected to the first terminal of the leakage inductance 12b, and the second terminal of the leakage inductance 12b is connected to the first terminal of the main inductor 12d of the transformer. Additionally, the second terminal of the main inductor 12d of the transformer is connected to the first terminal of the capacitor 12c, and the second terminal of the capacitor 12c is connected to the second terminal (exemplarily the source terminal) of the second field-effect transistor 11b.

[0055] Furthermore, the resonant hybrid flyback converter 10 includes a processing unit 14, where the processing unit 14 is configured to sense the LED voltage with respect to an LED-based load (exemplarily the LED 13c) and / or the half-bridge current with respect to the primary side 15a.

[0056] In this context, the resonant hybrid flyback converter 10 exemplarily includes a voltage sensing device 13a and / or a current sensing device 12a. The voltage sensing device is particularly connected in parallel to the LED-based load or the LED 13c respectively, and the current sensing device is particularly connected in series to the above series connection of the primary side 15a or the resonant tank 12. It should be noted that the processing unit 14 is exemplarily connected to the voltage sensing device 13a and / or the current sensing device 12a.

[0057] In addition, the processing unit 14 is configured to control the on-time of the low-side switch (exemplarily the second field-effect transistor 11b) based on the LED voltage. As an option, the processing unit 14 can be configured to control the on-time of the high-side switch (exemplarily the first field-effect transistor 11a) based on peak detection of the half-bridge current.

[0058] In this context, the processing unit 14 can optionally be connected to the third terminal (exemplarily the gate terminal) of the first field-effect transistor 11a (for this connection, as shown by the dashed line in Figure 1 ), while the processing unit 14 is connected to the third terminal (exemplarily the gate terminal) of the second field-effect transistor 11b. It should be noted that the processing unit 14 is exemplarily configured to perform the peak detection of the half-bridge current.

[0059] It may be particularly advantageous if the processing unit 14 is configured to adjust the operating point for controlling the on-time of the high-side switch (exemplarily the first field-effect transistor 11a) based on controlling the on-time of the low-side switch (exemplarily the second field-effect transistor 11b).

[0060] Furthermore, the processing unit 14 may preferably be configured to control the on-time of the low-side switch (exemplarily the second field-effect transistor 11b) such that, in the case of an increasing LED voltage, the on-time of the low-side switch (exemplarily the second field-effect transistor 11b) decreases particularly in a linear, non-linear, continuous, stepwise or ramp manner.

[0061] Furthermore, the processing unit 14 may preferably be configured to control the on-time of the high-side switch (exemplarily the first field-effect transistor 11a) such that, in the case of an increasing LED voltage, the on-time of the high-side switch (exemplarily the first field-effect transistor 11a) increases particularly in a linear, non-linear, continuous, stepwise or ramp manner.

[0062] It should be noted that it may be particularly advantageous if the processing unit 14 is configured to limit the step size of a corresponding step preferably according to at least two maximum step sizes during a change in the on-time of the low-side switch 11b, particularly during the start-up phase of the resonant hybrid flyback converter 10. It should be noted in advance that this time-interval-related step size limitation will additionally be Figure 8 clarified.

[0063] It should also be noted that it may be particularly advantageous if the processing unit 14 is configured to apply the maximum of at least two maximum step sizes as long as the corresponding current is below a limit value, preferably a predefined limit value, based on the setpoint of the corresponding LED current. Additionally or alternatively, the at least two maximum step sizes may comprise or be at least two predefined maximum step sizes. Further additionally or further alternatively, the step size of the corresponding step during the start-up phase in particular is adjusted in such a way that the resulting current spike does not exceed or substantially does not exceed the current ripple present during normal LED operation.

[0064] According to Figure 3 , it may be particularly advantageous if, in the case where the on-time of the low-side switch or the second field-effect transistor 11b decreases stepwise according to curve 31b respectively, the on-time of the high-side switch or the first field-effect transistor 11a increases in a ramp-shaped manner according to curve 31a respectively. It should be noted that the processing unit 14 may preferably be configured to control the corresponding on-times accordingly.

[0065] Regarding this Figure 3 first exemplary diagram 30 which shows the on-time of the low-side switch and the on-time of the high-side switch at different LED voltages, it should also be noted that this diagram 30 particularly depicts examples of the high-side on-time and the low-side on-time in the LED voltage range from 5V to 36V. In this context, there are three exemplary different operating regions 32a, 32b, 32c, each of these operating regions having a corresponding constant low-side on-time.

[0066] Furthermore, according to a second exemplary diagram 40 showing the low-side switch conduction time and the high-side switch conduction time at different LED voltages Figure 4 , it may be particularly advantageous if, in the case where the conduction time of the low-side switch or the second field-effect transistor 11b decreases linearly respectively according to curve 41b, the conduction time of the high-side switch or the first field-effect transistor 11a increases in a non-linear manner respectively according to curve 41a at least in a substantial part of the voltage range with respect to the LED voltage. It should be noted that the processing unit 14 can preferably be configured to control the corresponding conduction times accordingly.

[0067] Especially in Figure 4 the context, it should also be noted that it may be particularly advantageous if the LED voltage is continuously observed and the low-side conduction time is adjusted especially in the case of a change in the output load. Advantageously, instead of different conduction time regions with large low-side conduction time steps, a smooth linear low-side conduction time slope can be achieved. Further advantageously, especially in order to avoid an "uncontrolled back-and-forth" adjustment of the low-side conduction time at the stable operating point, a hysteresis mode can be additionally implemented. The hysteresis mode preferably ensures that the low-side conduction time is adjusted only if the LED voltage changes by a defined voltage difference. Therefore, the processing unit 14 can preferably be configured to implement the hysteresis mode, especially such a hysteresis mode. In this context, the processing unit 14 can especially be configured to adjust the conduction time of the low-side switch or the second field-effect transistor 11b only if the LED voltage preferably changes by a defined voltage difference, more preferably by a predefined voltage difference, and most preferably by a predefined voltage difference that can be specifically set by the user.

[0068] In this context, it should also be noted that the processing unit 14 can preferably be configured to: monitor the LED voltage, determine the conduction time of the low-side switch, and adjust the conduction time of the low-side switch.

[0069] Furthermore, according to a third exemplary diagram 50 depicting the low-side switch conduction time and the high-side switch conduction time at different LED voltages Figure 5 , it may be particularly advantageous if, in the case where the conduction time of the low-side switch or the second field-effect transistor 11b decreases non-linearly respectively according to curve 51b, the conduction time of the high-side switch or the first field-effect transistor 11a increases linearly respectively according to curve 51a. It should be noted that the processing unit 14 can preferably be configured to control the corresponding conduction times accordingly.

[0070] Especially in Figure 5In the context of , it is also necessary to note that it may be particularly advantageous if the low-side on-time is set according to the output voltage or the LED voltage, respectively, so that the high-side on-time, rather than the low-side on-time, produces a linear slope over the load range. This can be done exemplarily by maintaining a constant transformer "voltage second", in particular during the period when energy is transferred to the output terminal or the LED-based load, respectively. This operating variant in which the low-side on-time exhibits a flatter slope, in particular at high LED voltages, provides several advantages, such as improved flicker during load transitions, smaller peak-to-peak magnetizing currents, higher efficiency, more flexible design of the magnetic resonance tank 12, and an easy-to-implement and feasible mode.

[0071] In this context, it is also necessary to explain that the processing unit 14 can preferably be configured to: monitor the LED voltage, in particular determine the on-time of the low-side switch for the constant "voltage second", and adjust the on-time of the low-side switch.

[0072] Basically, and in particular in view of Figure 5 It should be mentioned that it may be particularly advantageous if the low-side switch on-time is set in dependence on the output voltage. Thus, when the LED voltage changes, the low-side switch on-time is specifically adjusted.

[0073] In this context, it is important to note that when the change in LED voltage is small (usually in the mV range), the low-side switch on-time adjustment is also small. However, when the change in LED voltage is large, such as during startup, the low-side switch on-time will be adjusted in large steps (especially when the adjustment / update rate is slow). Such large steps usually result in high LED current peaks. The exact reason for this is that the regulator (such as the one discussed below) Figure 2 The proportional-integral control element 24c) cannot immediately compensate for the sudden change in duty cycle. The current peak may damage electrical components or cause flicker problems.

[0074] To prevent this from happening, a step limit is defined to limit the low-side switch on-time change (from the previous setting value to the new setting), such as Figure 8 This ensures that the regulator can better handle the step and thus limit the LED current peak.

[0075] Since different step size limits are required during different operation phases, the present invention also provides a specific implementation of the time interval related step size limit, such as from the Figure 8 It can be seen.

[0076] according to Figure 8 , four different maximum step sizes are depicted by way of example, namely step sizes 501 , 502 , 503 , and 504 .

[0077] In this context, it should be remembered that Figure 1 the processing unit 14 of Figure 1 can advantageously be configured to limit the step size of a corresponding step preferably according to at least two maximum step sizes during a change in the conduction time of the low-side switch 11b, in particular during the start-up phase of the resonant hybrid flyback converter 10.

[0078] Thus, based on Figure 8 the example of Figure 8 , the processing unit 14 can exemplarily be configured to limit the step size of a corresponding step according to four maximum step sizes 501, 502, 503, 504 during a change in the conduction time of the low-side switch 11b.

[0079] Furthermore, as can be exemplarily seen from Figure 8 it can be particularly advantageous if the smallest of at least two maximum step sizes (exemplarily the smallest of the four maximum step sizes 501, 502, 503, 504, i.e., the maximum step size 504) is applied during the normal operation of the resonant hybrid flyback converter 10, while the remaining step sizes of at least two maximum step sizes (exemplarily the remaining step sizes of the four maximum step sizes 501, 502, 503, 504, i.e., the maximum step sizes 501, 502, 503) are applied during the start-up phase or start of the resonant hybrid flyback converter 10, respectively.

[0080] Advantageously, in this way, the corresponding LED current peaks or flicker can be reliably limited.

[0081] It should be noted that it can be particularly advantageous if the processing unit 14 is configured to limit the step size of a corresponding step during the start-up phase or start of the resonant hybrid flyback converter 10 in such a way that the resulting current spikes do not exceed or substantially do not exceed the current ripple present during normal LED operation.

[0082] With respect to the above-mentioned constant transformer "voltage-second" or constant "voltage-second", an exemplary diagram 60 showing the voltage across the transformer (which is particularly supplied by the half-bridge 11) over time Figure 6 shows a first region 61 and a second region 62.

[0083] During the first region 61 or the corresponding conduction time of the high-side switch, energy is stored in the transformer, while during the second region 62 or the corresponding conduction time of the low-side switch, the energy is respectively transferred to the output or an LED-based load (such as Figure 1 the LED 13c of Figure 1 ). As can be seen from Figure 6 it should be noted with respect to the second region 62 that the second region 62 includes the above-mentioned "voltage-second", where the second region 62 remains constant particularly within the corresponding load range.

[0084] Regarding the constant "voltage-second" or "voltage-second", the LED voltage, and the conduction time of the low-side switch, it should be noted that it may be particularly advantageous if the following equation applies:

[0085]

[0086] In this context, it should also be noted that each of the parameters can be represented in the form of a mere value without a corresponding physical unit. As an exemplary alternative, the physical unit of the conduction time of the low-side switch can be seconds, the physical unit of the LED voltage can be volts, and the physical unit of "voltage-second" can be volts multiplied by seconds.

[0087] Now, regarding Figure 2 , an abstract illustration of the first and second aspects of the present invention is shown, such as Figure 1 the resonant hybrid flyback converter 10 or the system 200 of Figure 2 respectively, for explaining the corresponding functions in more detail. It should be noted that all of the above explanations similarly apply to

[0088] By analogy with Figure 1 , it should be noted that the Figure 2 additionally shows an exemplary embodiment of the system 300 of the present invention, which includes a resonant hybrid flyback converter 20 and an LED-based load (exemplarily LED 23c) powered by the resonant hybrid flyback converter 20.

[0089] According to this Figure 2 , the resonant hybrid flyback converter 20 includes a control element (exemplarily a proportional-integral control element 24c), which can also be implemented or included by Figure 1 the processing unit 14 of the resonant hybrid flyback converter 10 of

[0090] In this context, as already mentioned above in the context of Figure 1 , the peak detection (which is exemplarily depicted as Figure 2 the peak detection unit 24b of

[0091] is based on the controlled variable received from the control element (exemplarily the proportional-integral control element 24c). Figure 2 As can also be seen from

[0092] Regarding the target LED current, it should be noted that the target LED current can be set by the user, especially during the operation of the resonant hybrid flyback converter. Additionally or alternatively, the target LED current can be predefined and provided by a memory, for example.

[0093] In view of Figure 2 the LED current sensing unit 23b, it should be noted that Figure 1 the processing unit 14 can also be configured to sense the LED current regarding the LED-based load (exemplarily LED 13c). In this context, the resonant hybrid flyback converter 10 can include an additional current sensing device 13b, which is particularly connected in series to the LED 13c, and the additional current sensing device 13b can be connected to the processing unit 14, for example.

[0094] According to Figure 2 , the resonant hybrid flyback converter 20 can be configured to control the on-time of the low-side switch 21b based on the on-time of the high-side switch 21a, which is shown by the low-side on-time control unit 24a fed with the frame 24d of the high-side on-time, and the frame 24d including the on-time of the high-side switch 21a is fed by the high-side switch 21a, for example.

[0095] Particularly in view of the control of the on-time of the low-side switch 21b based on the on-time of the high-side switch 21a, it should be noted that the processing unit 14 can also be configured to sense the on-time of the high-side switch 11a. Additionally or alternatively, the processing unit 14 can be configured to control the on-time of the low-side switch 11b based on the on-time of the high-side switch 11a.

[0096] For the sake of completeness, all the connections according to Figure 2 are described below, where at least some of the equivalents regarding Figure 1 are clearly explained.

[0097] The terminal (exemplarily the output terminal) of the above-mentioned frame 24e showing the target LED current is connected to the first terminal (exemplarily the first input terminal) of a control element (exemplarily the proportional-integral control element 24c), and the second terminal (exemplarily the second input terminal) of the control element (exemplarily the proportional-integral control element 24c) is connected to the first terminal (exemplarily the output terminal) of the LED current sensing unit 23b.

[0098] In addition, a third terminal (exemplarily, an output terminal) of a control element (exemplarily, a proportional-integral control element 24c) is connected to a first terminal (exemplarily, a first input terminal) of a peak detection unit 24b, wherein a second terminal (exemplarily, an output terminal) of the peak detection unit 24b is connected to a first terminal (exemplarily, an input terminal, which is preferably in the form of Figure 1 a gate terminal of a first field-effect transistor 11a), wherein a second terminal (exemplarily, an output terminal, which is preferably in the form of Figure 1 a drain terminal of a first field-effect transistor 11a) of the high-side switch 21a is connected to a first terminal (exemplarily, a first input terminal) of a resonant tank 22.

[0099] In addition, a second terminal (exemplarily, a first output terminal) of the resonant tank 22 is connected to a second terminal (exemplarily, an input terminal) of an LED current sensing unit 23b, wherein a third terminal (exemplarily, a second output terminal) of the LED current sensing unit 23b is connected to a terminal (exemplarily, an input terminal) of an LED 23c.

[0100] Regarding the above high-side switch 21a, it should be noted that a third terminal (exemplarily, a sensing terminal) of the high-side switch 21a is connected to a first terminal (exemplarily, an input terminal) of a block 24d showing the on-time of the high-side switch, wherein a second terminal (exemplarily, an output terminal) of the block 24d is connected to a first terminal (exemplarily, a first input terminal) of a low-side on-time control unit 24a.

[0101] Regarding the above sensing terminal of the high-side switch 21a, it should be noted that the sensing terminal can be regarded as Figure 1 a gate terminal or a drain terminal of a first field-effect transistor 11a. As an alternative, the sensing terminal can be regarded as an output terminal of a combinational circuit or a sequential logic system, and the circuit or system includes a gate terminal and / or a drain terminal of a first field-effect transistor 11a respectively used as one input terminal or multiple input terminals.

[0102] Similarly, regarding the low-side on-time control unit 24a, it should be noted that a second terminal (exemplarily, an input terminal) of the low-side on-time control unit 24a is connected to a first terminal (exemplarily, an input terminal) of a low-side switch 21b, wherein a second terminal (exemplarily, an output terminal) of the low-side switch 21b is connected to a third terminal (exemplarily, a second input terminal) of the resonant tank 22.

[0103] Furthermore, the fourth terminal (exemplarily the second output terminal) of the resonant tank 22 is connected to the first terminal (exemplarily the input terminal) of the half-bridge current sensing unit 22a, wherein the second terminal (exemplarily the output terminal) of the half-bridge current sensing unit 22a is connected to the third terminal (exemplarily the second input terminal) of the above-mentioned peak detection unit 24b.

[0104] Regarding the half-bridge current sensing unit 22a, it should be noted that the half-bridge current sensing unit 22a can be regarded as Figure 1 the current sensing device 12a, especially in combination with the processing unit 14 according to Figure 1 the processing unit 14.

[0105] Furthermore, the fifth terminal (exemplarily the third output terminal) of the above-mentioned resonant tank 22 is connected to the first terminal (exemplarily the input terminal) of the LED voltage sensing unit 23a, wherein the second terminal (exemplarily the output terminal) of the LED voltage sensing unit 23a is connected to the third terminal (exemplarily the second input terminal) of the above-mentioned low-side conduction time control unit 24a.

[0106] Regarding the LED voltage sensing unit 23a, it should be noted that the LED voltage sensing unit 23a can be regarded as Figure 1 the voltage sensing device 13a, especially in combination with the processing unit 14 according to Figure 1 the processing unit 14.

[0107] It should also be noted that regarding the elements equipped with reference numerals 24a to 24e, if at least one of the elements, preferably each element, is implemented or included by a processing unit such as the processing unit 14 according to Figure 1 the processing unit 14, this may be particularly advantageous.

[0108] Now, regarding Figure 7 , an exemplary circuit diagram 70 of a further illustration is shown respectively for Figure 1 or Figure 2 . In this context, it should be noted that for the sake of compactness, the elements explained above are not illustrated again, but are equipped with the same reference numerals.

[0109] Respectively by analogy with Figure 1 or Figure 2 , it should be noted that the Figure 7 additionally shows an exemplary embodiment of the system 400 of the present invention, which includes a resonant hybrid flyback converter 70 and an LED-based load powered by the resonant hybrid flyback converter 70, exemplarily the LED 13c.

[0110] As can be seen from the Figure 7It can be seen that half-bridge current sensing 22a is performed at the base of the half-bridge 11 (exemplarily at terminal 72). In this context, it should be noted that Figure 7 Compared with Figure 1 , the difference lies particularly in that the connection from the drain terminal of the second field-effect transistor 11b to the corresponding terminal of the capacitor 12c is not directly connected to the voltage potential 11d, but to the terminal 72, where the terminal 72 (exemplarily the half-bridge current sensing terminal) is connected to the first terminal of the resistor 71, and the second terminal of the resistor 71 is connected to the voltage potential 11d. It should be noted that the terminal 72 (exemplarily the half-bridge current sensing terminal) can be connected to the processing unit 14.

[0111] In addition, in the sense of LED voltage sensing 23a or output voltage sensing respectively, the output voltage or the LED voltage can be measured respectively at the terminal 73 (exemplarily the LED voltage sensing terminal), especially when the winding ratio of the transformer is known. Preferably, the measurement can be performed when the transformer discharges during the blocking phase of the high-side switch 11a. In this context, it should be noted that as long as the diode 13e is conducting, the LED voltage minus the forward voltage of the diode 13e at the output terminal of the transformer exists on the secondary side 15b. It should be noted that the terminal 73 (exemplarily the LED voltage sensing terminal) can be connected to the processing unit 14.

[0112] It should also be noted that in the context of LED voltage sensing 23a or output voltage sensing respectively, Figure 7 Compared with Figure 1 , the difference lies particularly in that the connection between the transformer main inductor 12d and the capacitor 12c is additionally connected to the first terminal of the resistor 74, where the second terminal of the resistor 74 is connected to the above-mentioned terminal 73 (exemplarily the above-mentioned LED voltage sensing terminal). Additionally, the terminal 73 is connected to the above-mentioned voltage potential 11d via a parallel connection of the resistor 76 and the capacitor 75.

[0113] In addition to this, in the sense of the above-mentioned LED current sensing 23b, it should be noted that the LED current sensing 23b can be performed respectively on the secondary side 15b (especially at the terminal 78 (exemplarily the LED current sensing terminal)) by means of a current transformer 77 or a current sensing transformer. The current transformer 77 or one of its sides can be respectively exemplarily inserted into the connection between the transformer secondary inductor 13d and the diode 13e (especially its anode terminal).

[0114] In addition, the first terminal on the other side of the current transformer 77 is connected to the first terminal (exemplarily the anode terminal) of the diode 81, where the second terminal (exemplarily the cathode terminal) of the diode 81 is connected to the above-mentioned terminal 78 (exemplarily the LED current sensing terminal), and this terminal can be connected to the processing unit 14. Additionally, the terminal 78 is exemplarily connected to the second terminal on the other side of the current transformer 77 via the parallel connection of a capacitor 82 and a resistor 83.

[0115] Finally, Figure 9 A flowchart of an exemplary embodiment of the inventive method for operating a resonant hybrid flyback converter for an LED-based load (in particular the inventive resonant hybrid flyback converter such as Figure 1 is shown. The first step 100 of the method includes sensing the LED voltage regarding the LED-based load and / or the half-bridge current on the primary side of the transformer of the flyback resonant tank regarding the resonant hybrid flyback converter, where the primary side is powered by a half-bridge including a high-side switch and a low-side switch, and the resonant hybrid flyback converter includes this half-bridge. Additionally, the second step 101 includes controlling the on-time of the low-side switch based on the LED voltage.

[0116] Although various embodiments of the present invention have been described above, it should be understood that these embodiments are given by way of example and not by way of limitation. Without departing from the spirit or scope of the present invention, various changes can be made to the embodiments disclosed herein according to the disclosure herein. Therefore, the breadth and scope of the present invention should not be limited by any of the above embodiments. Instead, the scope of the present invention should be defined according to the following claims and their equivalents.

[0117] Although the present invention has been illustrated and described with respect to one or more specific embodiments, equivalent alternative forms and modifications will occur to those skilled in the art upon reading and understanding this specification and the drawings. Additionally, although a particular feature of the present invention may have been disclosed with respect to only one of several specific embodiments, such a feature can be combined with one or more other features of any given or specific application according to the desired and advantageous aspects.

Claims

1. A resonant hybrid flyback converter (10, 20, 70) for an LED-based load (13c, 23c), the resonant hybrid flyback converter (10, 20, 70) comprising: A half-bridge (11), the half-bridge including a high-side switch (11a, 21a) and a low-side switch (11b, 21b), A flyback resonant tank (12, 22), the flyback resonant tank including a transformer having a primary side (15a) and a secondary side (15b); and A processing unit (14), Wherein the half-bridge (11) is configured to supply power to the primary side (15a), Wherein the secondary side (15b) is configured to supply power to the LED-based load (13c, 23c), Wherein the processing unit (14) is configured to sense an LED voltage regarding the LED-based load (13c, 23c) and / or a half-bridge current regarding the primary side (15a), and Wherein the processing unit (14) is configured to control the on-time of the low-side switch (11b, 21b) based on the LED voltage.

2. The resonant hybrid flyback converter (10, 20, 70) according to claim 1, Among them, The processing unit (14) is configured to control the on-time of the high-side switch (11a, 21a) based on peak detection (24b) of the half-bridge current, Wherein the processing unit (14) is particularly configured to adjust an operating point for controlling the on-time of the high-side switch (11a, 21a) based on controlling the on-time of the low-side switch (11b, 21b).

3. The resonant hybrid flyback converter (10, 20, 70) according to claim 1 or 2, Among them, The processing unit (14) is configured to control the on-time of the low-side switch (11b, 21b) such that, in the case of an increase in the LED voltage, the on-time of the low-side switch (11b, 21b) particularly decreases in a linear, non-linear, continuous, stepwise or ramp manner.

4. The resonant hybrid flyback converter (10, 20, 70) according to any one of claims 2 or 3, Among them, The processing unit (14) is configured to control the on-time of the high-side switch (11a, 21a) such that, in the case of an increase in the LED voltage, the on-time of the high-side switch (11a, 21a) particularly increases in a linear, non-linear, continuous, stepwise or ramp manner.

5. The resonant hybrid flyback converter (10, 20, 70) according to any one of claims 2 to 4, Among them, In the case where the on-time of the low-side switch (11b, 21b) decreases stepwise, the on-time of the high-side switch (11a, 21a) increases in a ramp-shaped manner.

6. The resonant hybrid flyback converter (10, 20, 70) according to any one of claims 2 to 4, Among them, In the case where the on-time of the low-side switch (11b, 21b) decreases linearly, the on-time of the high-side switch (11a, 21a) increases non-linearly, in particular over a substantial part of the voltage range with respect to the LED voltage.

7. The resonant hybrid flyback converter (10, 20, 70) according to any one of claims 2 to 4, Among them, In the case where the on-time of the low-side switch (11b, 21b) decreases non-linearly, the on-time of the high-side switch (11a, 21a) increases linearly.

8. The resonant hybrid flyback converter (10, 20, 70) according to any one of claims 1 to 7, Among them, The resonant hybrid flyback converter (10, 20, 70) or the processing unit (14) comprises a control element, preferably a proportional-integral control element (24c), wherein the peak detection (24b) is based on a controlled variable received from the control element, preferably the proportional-integral control element (24c).

9. The resonant hybrid flyback converter (10, 20, 70) according to claim 8, Among them, The processing unit (14) is configured to sense the LED current with respect to the LED-based load (13c, 23c), wherein the control element, preferably the proportional-integral control element (24c), is configured to form the controlled variable based on the LED current and a target LED current (24e) that can be specifically set.

10. The resonant hybrid flyback converter (10, 20, 70) according to any one of claims 2 to 9, Among them, The processing unit (14) is configured to sense the on-time of the high-side switch (11a, 21a), and / or wherein the processing unit (14) is configured to control the on-time of the low-side switch (11b, 21b) based on the on-time of the high-side switch (11a, 21a).

11. The resonant hybrid flyback converter (10, 20, 70) according to any one of claims 1 to 10, Among them, The processing unit (14) is configured to limit the step size of a corresponding step, preferably according to at least two maximum step sizes (501, 502, 503, 504), during a change in the on-time of the low-side switch (11b, 21b), in particular during a start-up phase of the resonant hybrid flyback converter (10, 20, 70).

12. The resonant hybrid flyback converter (10, 20, 70) according to claim 11, Among them, The processing unit (14) is configured to apply the largest of the at least two maximum step sizes (501, 502, 503, 504) as long as the corresponding current is below a limit value, preferably a predefined limit value, based on the set point of the corresponding LED current, and / or wherein the at least two maximum step sizes (501, 502, 503, 504) comprise or are at least two predefined maximum step sizes, and / or In particular, during the start-up phase, the step size of the corresponding step is limited in such a way that the resulting current peak does not exceed or substantially does not exceed the current ripple present during normal LED operation.

13. A system (200, 300, 400), the system comprising: A resonant hybrid flyback converter (10, 20, 70) according to any one of claims 1 to 12, and An LED-based load (13c, 23c), the LED-based load being powered by the resonant hybrid flyback converter (10, 20, 70).

14. A method for operating a resonant hybrid flyback converter (10, 20, 70) for an LED-based load (13c, 23c), the method comprising the steps of: Sensing (100) the LED voltage with respect to the LED-based load (13c, 23c) and / or the half-bridge current on the primary side (15a) of the transformer of the flyback resonant tank (12, 22) with respect to the resonant hybrid flyback converter (10, 20, 70), the primary side (15a) being powered by a half-bridge (11) comprising a high-side switch (11a, 21a) and a low-side switch (11b, 21b), the resonant hybrid flyback converter (10, 20) comprising the half-bridge (11), and Controlling (101) the on-time of the low-side switch (11b, 21b) based on the LED voltage.

15. The method according to claim 14, Among them, The method further comprising the steps of: Controlling the on-time of the high-side switch (11a, 21a) based on peak detection (24b) of the half-bridge current, and Particularly adjusting the operating point for controlling the on-time of the high-side switch (11a, 21a) based on controlling the on-time of the low-side switch (11b, 21b).

16. The method according to claim 14 or 15, Among them, The method further comprising the step of: controlling the on-time of the low-side switch (11b, 21b) such that, in the case of an increase in the LED voltage, the on-time of the low-side switch (11b, 21b) particularly decreases in a linear, non-linear, continuous, stepwise or ramp manner.

17. The method according to claim 15 or 16, Among them, The method further comprising the step of: controlling the on-time of the high-side switch (11a, 21a) such that, in the case of an increase in the LED voltage, the on-time of the high-side switch (11a, 21a) particularly increases in a linear, non-linear, continuous, stepwise or ramp manner.

18. The method according to any one of claims 14 to 17, Among them, The method further comprising the step of: during the change in the on-time of the low-side switch (11b, 21b), particularly during the start-up phase of the resonant hybrid flyback converter (10, 20, 70), preferably limiting the step size of the corresponding step according to at least two maximum step sizes (501, 502, 503, 504).

19. The method according to claim 18, Among them, the method further comprising the steps of applying the largest of said at least two maximum steps (501, 502, 503, 504) as long as said corresponding current is below a limit value, preferably a predefined limit value, based on the set point of said corresponding LED current, and / or wherein said at least two maximum steps (501, 502, 503, 504) comprise or are at least two predefined maximum steps, and / or wherein the step size of said corresponding step is restricted, especially during said start-up phase, in such a way that the resulting current spike does not exceed or substantially does not exceed the current ripple present during normal LED operation.

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