LED driver control circuit

Abstract

An LED driver control circuit for an LED driver operating under a line-switch dimming protocol. The LED driver control circuit generates a control signal that can switch between a voltage level at a first node and a voltage level at a second node. The first node is connected to a three-phase input via a first voltage control circuit, and the second node is connected to the three-phase input via a second voltage control circuit. The first voltage control circuit controls the voltage level at the first node to be greater than the voltage level of each phase of the three-phase input in a first embodiment, or less than the voltage level of each phase of the three-phase input in a second embodiment, for at least a portion of a cycle of the corresponding phase. The second voltage control circuit controls the voltage level at the second node to be less than or equal to the voltage level of each phase of the three-phase input in a first embodiment, or greater than or equal to the voltage level of each phase of the three-phase input in a second embodiment, for the entire cycle of the corresponding phase.

Description

Technical Field

[0001] The present invention relates to the field of control circuits for LED drivers, and in particular to a control circuit suitable for providing an isolated control signal to an LED driver. Background Art

[0002] A light emitting diode (LED) arrangement formed of a plurality of LEDs is typically driven or powered by an LED driver. The LED driver may be adapted to define the amount of light output by the LED arrangement, for example by controlling the amount of current passing through the LEDs of the LED arrangement.

[0003] Various methods or protocols have been considered for controlling the amount of current through LEDs (i.e., dimming an LED device). Generally, these protocols share the common feature that an LED driver controls the amount of light output by the LED device in response to a control signal provided by an LED driver control circuit.

[0004] One example of a method for dimming LED devices is known as "line switching." Line switching is a step dimming method in which a control signal is provided to an LED driver, where the control signal is switchable between two levels. The LED driver responds to the change in the level of the control signal by appropriately varying the level of current through the connected LED device between two non-zero (and typically predetermined) levels.

[0005] Other methods of controlling dimming of LED devices are known, including DALI, 1-10V, 0-10V, and the like.

[0006] It is desirable to improve the adaptability of LED systems so that they can be connected to different or new power sources or inputs. In particular, it will be appreciated that the characteristics of different power sources (i.e., inputs) for LED systems may differ from typical power sources used in home settings or industrial applications (e.g., in different jurisdictions).

[0007] Therefore, there is a need to provide components for LED systems for such non-domestic power sources. Summary of the Invention

[0008] The invention is defined by the claims.

[0009] According to an example of one aspect of the present invention, an LED driver control circuit is provided. The LED driver control circuit is designed to generate a control signal for an LED driver connected to a three-phase input, the three-phase input including three different phase lines, each phase line carrying an AC signal having the same frequency and a different phase.

[0010] An LED driver control circuit comprises: a switch adapted to controllably connect a switch output node between a first switch input node and a second switch input node, the voltage at the switch output node defining the control signal; a first voltage control circuit connectable to at least one phase line of the three-phase input and to the first switch input node, and arranged to control the voltage at the first switch input node; and a second voltage control circuit connectable to at least one phase line and to the second switch input node of the three-phase input, and arranged to control the voltage at the second switch input node.

[0011] The first voltage control circuit and the second voltage control circuit are configured such that: the voltage at the first switch input node is greater than the instantaneous voltage of each AC signal in a portion of the cycle of each corresponding AC signal, and the voltage at the second switch input node is not greater than the instantaneous voltage of any AC signal at any point during the cycle of each corresponding AC signal; or the voltage at the first switch input node is less than the instantaneous voltage of each AC signal in a portion of the cycle of each corresponding AC signal, and the voltage at the second switch input node is not less than the instantaneous voltage of any AC signal at any point during the cycle of each corresponding AC signal.

[0012] The present invention proposes a novel LED driver control circuit suitable for generating control signals for (a plurality of) LED drivers operating under a line-switch dimming method. In particular, the proposed LED driver control circuit enables a line-switch-based LED driver to be powered by a three-phase mains input without requiring consideration during installation of which phases (provided by the three-phase input) are connected to which power terminals of the LED driver, while maintaining the accuracy of the control signals.

[0013] This significantly increases the ease of installation of the LED driver (and its associated LED devices) to be connected to the LED driver control circuit.

[0014] The present invention thus enables an LED driver and LED driver control circuit to operate from a three-phase input (such as a three-phase delta connection) without a neutral wire. This eliminates the need for a three-phase mains input to provide a neutral wire for the LED driver, thereby reducing the amount of wiring used to power and control the LED driver. For example, an existing lighting installation (to which the proposed technology can be retrofitted) may already include wiring for providing three inputs of mains power, as well as a neutral wire. In this case, a neutral wire is no longer required to power the LED driver (or LED driver control circuit), and the neutral wire can be used to carry the control signals generated by the LED driver control circuit. This enables a dimmable LED system to be retrofitted into existing lighting installations and increases the flexibility of the entire LED system.

[0015] It should be clear that the proposed LED driver control circuit is particularly suitable for line switch dimming method, but can be implemented in the context of other similar dimming methods.

[0016] The first voltage control circuit may include a first diode connected from a first phase line to a first switch input node; and a second diode connected from a second phase line to the first switch input node.

[0017] In some embodiments, the first voltage control circuit further includes a third diode connected from the third phase line to the first switch input node. The third diode is not required and may be omitted in some embodiments to reduce the size of the first voltage control unit.

[0018] The three-phase input may further include a neutral line, wherein the first voltage control circuit includes a first capacitor connected between the neutral line and the first switch input node; and a diode connected between one of the phase lines and the first switch input node.

[0019] When a neutral line is available for use in the LED driver control circuit, the reliability of the voltage at the first switch input node can be increased by providing a capacitor connected between the first switch input node and the neutral line. This smoothes the voltage provided at the first switch input node, increasing the time during which the voltage at the first switch input node is greater than the voltage at the neutral terminal of the LED driver. It also increases the flexibility of the LED driver circuit, requiring only two wires to be connected to the three-phase input.

[0020] In another embodiment, the first voltage control circuit comprises, in addition to the first capacitor, three diodes, each diode connecting a respective phase line of the three-phase input to the first switching input node.

[0021] In at least one embodiment, the second voltage control circuit includes three diodes, each diode connecting the second switch input node to a corresponding phase line of the three-phase input.

[0022] In at least one embodiment, the three-phase input further includes a neutral line and the second voltage control circuit includes: a second capacitor connected between the neutral line and the second switching input node; and a diode connected from the second switching input node to one of the phase lines of the three-phase input.

[0023] When a neutral line is available for the LED driver control circuit, the reliability of the voltage at the second switch input node can be increased by providing a capacitor connected between the second switch input node and the neutral line. This smoothes the voltage provided at the second switch input node and reduces the likelihood that the voltage at the neutral terminal of the LED driver will rise above the voltage at the second switch input node (for example, in the event of a power surge). It also increases the flexibility of the LED driver circuit by requiring only two wires connected to the three-phase input (rather than all three).

[0024] An LED driver system is also provided, comprising: an LED driver control circuit as described herein; and an LED driver for driving an LED device, connectable to a three-phase input and responsive to a control signal generated by the LED driver control circuit.

[0025] Preferably, the LED driver system is adapted so that no LED driver is connected to the neutral line (if present) of the three-phase input. The present invention enables the LED driver to be operated solely from the phase lines of the three-phase input, freeing up a line that might previously have been designated as the neutral line (e.g., to carry control signals for the LED driver control circuit). This improves the ease of retrofitting the LED driver system into existing wiring schemes or lighting systems.

[0026] In an embodiment, each LED driver comprises a control signal isolator adapted to receive the control signal and to generate an isolated control signal based on a difference between the control signal and an AC signal carried by one of the phase lines.

[0027] In some embodiments, the control signal isolator includes: a light emitting diode connected between the switch output node and one of the phase lines and adapted to generate light in response to a voltage at the switch output node; and a light responsive circuit adapted to receive the light generated by the light emitting diode and generate the control signal. Thus, the control signal isolator may effectively include an optocoupler device.

[0028] In some embodiments, the control signal isolator further comprises a reverse current diode connected between the switch output node and a phase line same as the light emitting diode, wherein the polarity of the control diode is opposite to that of the light emitting diode.

[0029] The LED driver is preferably adapted to control the current flowing through the LED arrangement in response to the control signal.In particular, the LED driver may operate according to a line switching protocol in response to the control signal.

[0030] Also provided is an LED system comprising any LED driver system described herein; and an LED arrangement formed of one or more LEDs driven by the LED driver system.

[0031] An LED system is also provided, comprising an LED driver control circuit of any description; a plurality of LED drivers for driving respective LED devices, the plurality of LED drivers being connectable to the three-phase input and responsive to control signals generated by the LED driver control circuit; and a plurality of LED devices driven by the respective LED drivers, the number of LED devices being equal to the number of LED drivers.

[0032] Therefore, different LED drivers can share the control signal generated by the LED driver control circuit.

[0033] According to an example of one aspect of the present invention, a method of controlling an LED driver control circuit is provided, wherein the LED driver control circuit is used to generate a control signal for an LED driver that can be connected to a three-phase input, the three-phase input including three different phase lines, each phase line carrying an AC signal with the same frequency and a different phase.

[0034] The method includes: controllably connecting a switch output node between a first switch input node and a second switch input node; generating a control signal for the LED driver in response to a voltage at the switch output node, wherein the control signal is electrically isolated from the switch output node; providing a voltage to the first switch input node using a first voltage control circuit connected between at least one phase of the three-phase input and the first switch input node; and providing a voltage to the second switch input node using a second voltage control circuit connected to the second switch input node and connectable to at least one phase of the three-phase input, wherein: the voltage provided at the first switch input node is greater than the instantaneous voltage of each AC signal for a portion of a cycle of each corresponding AC signal, and the voltage provided at the second switch input node is not greater than the instantaneous voltage of any AC signal at any point during the cycle of each corresponding AC signal; or the voltage provided at the first switch input node is less than the instantaneous voltage of each AC signal for a portion of a cycle of each corresponding AC signal, and the voltage provided at the second switch input node is not less than the instantaneous voltage of any AC signal at any point during the cycle of each corresponding AC signal. These and other aspects of the invention will become apparent and elucidated with reference to the embodiments described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] For a better understanding of the present invention, and in order to show more clearly how it may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, in which:

[0036] Figure 1 An LED system with an LED driver control circuit according to an example known in the prior art is shown;

[0037] Figure 2 shows an LED driver control circuit according to a general embodiment of the present invention;

[0038] Figure 3 shows an LED driver control circuit according to a first embodiment;

[0039] Figure 4 shows waveforms for explaining the LED driver control circuit according to the first embodiment;

[0040] Figure 5 FIG. 2 shows waveforms for explaining the LED driver control circuit according to the second embodiment;

[0041] Figure 6 shows an LED driver control circuit according to a third embodiment; and

[0042] Figure 7A method for controlling an LED driver control circuit according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0043] The present invention will be described with reference to the accompanying drawings.

[0044] It should be understood that although the detailed description and specific examples indicate exemplary embodiments of the devices, systems, and methods, they are for illustrative purposes only and are not intended to limit the scope of the present invention. These and other features, aspects, and advantages of the devices, systems, and methods of the present invention will become better understood from the following description, the appended claims, and the accompanying drawings. It should be understood that the drawings are merely schematic and not drawn to scale. It should also be understood that the same reference numerals are used throughout the drawings to indicate the same or similar components.

[0045] The present invention provides an LED driver control circuit for an LED driver operating under a line-switch dimming protocol. The LED driver control circuit generates a control signal that can switch between a voltage level at a first node and a voltage level at a second node. The first node is connected to a three-phase input via a first voltage control circuit, and the second node is connected to the three-phase input via a second voltage control circuit. The first voltage control circuit controls the voltage level at the first node to be greater than the voltage level of each phase of the three-phase input in a first embodiment, or less than the voltage level of each phase of the three-phase input in a second embodiment, for at least a portion of a cycle of the corresponding phase. The second voltage control circuit controls the voltage level at the second node to be less than or equal to the voltage level of each phase of the three-phase input in a first embodiment, or greater than or equal to the voltage level of each phase of the three-phase input in a second embodiment, for the entire cycle of the corresponding phase.

[0046] The present invention thus provides an LED driver control circuit that enables an LED driver operating under a line switch dimming protocol to use any two of the three phase inputs as phase and return paths (ie acting as neutral) while still being properly controlled.

[0047] Figure 1 A known LED driver control circuit 100 is shown in the context of an overall LED system 10. The LED system 10 also includes an LED driver 150 and an LED device 160, which is driven by a driving component 159 of the LED driver 150. The LED driver control circuit 100 generates a control signal Sc used by the LED driver 150.

[0048] The LED driver 150 is adapted to operate according to a line switch interface scheme or dimming protocol. In this scheme, the LED driver 150 is energized from the mains input via the phase terminal T1 and the neutral terminal T2. The "line switch" interface scheme includes an additional input terminal T3 ("control terminal") for the LED driver (which serves as the control of the LED driver) and uses the neutral terminal as a shared return path for the control signal received at the additional input terminal.

[0049] Typically, in the line switch interface method, the control signal S (received at the additional input) C The LED driver is switchable between a first level and a second level, and controls the current through the LED device connected between the first and second (non-zero) current levels in response to the level of the control signal. This enables switching and controlled dimming.

[0050] Therefore, the LED driver control circuit 100 is adapted to generate the control signal Sc for the additional input terminal T3 of the driver.

[0051] The LED driver 150 has three terminals T1, T2, and T3 for connecting to three corresponding wirings. The first terminal T1 and the second terminal T2 can be connected to the mains input 190 and thus serve as "power terminals". The first terminal T1 ("phase terminal") can be connected to draw power from the phase line 191 of the mains input 190 (which can be alternatively labeled as "power line", "hot line", "driver line" or "line"). The second terminal T2 ("neutral terminal") can be connected to the neutral line 192 of the mains input, which serves as a return path for the LED driver, which is well known in the art. Therefore, the power input 190 provides two (transmission) lines for connecting to the terminals of the LED driver.

[0052] The LED driver 150 also includes a third terminal T3 ("control terminal" or "line switch terminal") for receiving a control signal Sc generated by the LED driver control circuit 100. The control signal Sc is consistent with a line switch interface method. Specifically, the third terminal T3 can be connected to the switch output node 115 of the LED driver control circuit 100, which provides the control signal Sc, as will be explained below.

[0053] The LED driver 150 includes a circuit that generates an isolation control signal S C1 The control signal isolator 155 receives the control signal S C , and based on the control signal S C The difference between the voltage of the neutral line or the voltage at the neutral line terminal T2 (ie, the current through the control signal isolator 155) generates the isolation control signal S C1The control signal isolator 155 requires a return path for the control signal, which is provided by the neutral line 192 connected to the second terminal T2. C1 Therefore, the control signal S C Electrical isolation.

[0054] The LED driver 150 further includes a driving component 159 for driving the LED device. The driving of the LED device is sensitive to or responsive to the isolated control signal S C1 , and thus responds to the control signal S C For example, the driver component may control the current through the LED arrangement in response to a (isolated) control signal, as explained before.

[0055] The LED driver control circuit 100 includes a switch S1 that controllably connects a switch output node 115 between a first switch input node 116 (connected to the phase line 191) and a second switch input node 117 (connected to the neutral line 192). Switching of S1 can be responsive to an external control signal or manually, for example, via a user interface (not shown). This effectively allows the switch S1 to switch the voltage at the switch output node (i.e., the control signal) between the voltage of the phase line 191 and the voltage of the neutral line 192.

[0056] In the prior art example shown, the control signal isolator 155 effectively comprises a circuit 150 responsive to the control signal S C The isolation control signal S is generated C1 However, the optical coupler device generates an isolated control signal S C1 Other methods will be apparent to those skilled in the art (eg, using a 1:1 transformer).

[0057] The control signal isolator 155 includes a light emitting diode 157 and a light response circuit 158. The light response circuit 158 ​​is adapted to receive the light generated by the light emitting diode and generate an isolated control signal S C1 The light emitting diode 157 emits light in response to the current flowing therethrough, ie, the voltage difference between the control terminal T3 and the neutral terminal T2.

[0058] The control signal isolator 155 further includes a diode D connected in parallel with the light emitting diode 157 but having an opposite polarity (reverse current) I The resistor R1 limits the current through the LED 157. This is because the LED 157 and the diode D I Neither limit current, which means that a resistor is preferably used to limit the current through these components (for example if the neutral terminal T2 is connected to a low output impedance voltage).

[0059] Obviously, when the switch S1 connects the switch output node 115 to the first switch input node, current will flow from the phase line 191 through the resistor R1 and the light emitting diode 157 and to the neutral line 192. This will cause the light emitting diode to generate light, which in turn causes the light responsive circuit to generate an isolated control signal S having a first characteristic (i.e., indicating that light has been detected). C1 The first characteristic may be the presence of (some) voltage / current in the isolated control signal.

[0060] When switch S1 connects the switch output node to the second switch input node, no current flows through light emitting diode 157. Therefore, light responsive circuit 158 ​​will generate an isolated control signal having a second characteristic (i.e., indicating that no light is detected). The second characteristic may be the absence of (some) voltage / current in the isolated control signal.

[0061] Therefore, the control signal S C The characteristics of the LED device can be controlled while allowing electrical isolation from components that control the LED device and the LED device itself.

[0062] Specifically, some current (i.e., a voltage difference over a period of time) flowing through the control signal isolator (from the switch output node to the neutral line) results in the generation or output of an isolated signal having a first characteristic. No current flowing from the switch output node through the control signal isolator to the neutral line, i.e., when there is no voltage across the control signal isolator, results in the generation or output of an isolated control signal having a second characteristic.

[0063] As briefly described above, the driving component 159 of the LED driver 150 responds to the isolated control signal S C1 characteristics to control the LED device 160.

[0064] It is known that the driving component 159 controls the current through the LED device 160 at a first level in response to an isolated control signal having a first characteristic, and controls the current through the LED device 160 at a different second level in response to an isolated control signal having a second characteristic. C (Thus, the switch SI) can effectively control the current through the LED device 160. Methods for controlling LED devices based on different signal characteristics of isolated control signals are well known in the art.

[0065] In known examples, the second switch input node 117 is omitted from the LED driver control circuit 100 and the switch may instead disconnect the switch output node from the first switch input node (ie, open the switch) (resulting in a control signal having a second characteristic).

[0066] However, one problem with this approach is that current may still be coupled from the phase line 191 to the switch output node 115, for example, via parasitic capacitance, which may still cause current to flow through the control signal isolator and erroneously generate an isolated control signal. Therefore, it is preferable to enable the switch output node 115 to be connected to the neutral line 192 to generate a control signal having a second characteristic.

[0067] In known examples, it is possible to use the above-described LED driver 150 and LED driver control circuit 100 with a (industrial) 3-phase star (Y) input or power supply having three phases and a neutral line, rather than the (domestic) power supply shown having a single phase and a neutral line.

[0068] A three-phase input typically provides three phase lines, each carrying an alternating signal (i.e., a signal having an alternating current and an alternating voltage), and a neutral line (carrying a return path and / or representing ground or earth). In some embodiments, an additional line (not shown) may be provided that provides a protective earth. The voltages / currents carried by the phase lines are substantially identical to one another (i.e., identical frequency, peak amplitude, shape, etc.), except that each voltage / current is 120° out of phase with the voltages / currents carried by the other phase lines. Each alternating signal, for example, may be iteratively and periodically cycled in a sinusoidal manner.

[0069] In such a configuration, the phase terminal T1 of the LED driver 150 can be connected to any one of three phases (or possibly more), each carrying a signal of a different phase (R, S, T), and the neutral terminal T2 can be connected to the neutral line. For such a system, the corresponding LED driver control circuit can use any one of the three phases (for connection to the first switch input node) and the neutral line (for connection to the second switch input node). The phase line used for the first switch input node can be selected independently of the input node used to power the LED driver.

[0070] The operation of the LED driver and the LED driver control circuit operates in much the same manner. In some examples, a capacitor may be provided at the output of the light-responsive circuit to smooth any ripple in the isolated control signal caused by the AC carried by the phase line. However, this component is not required.

[0071] However, the present inventors have recognized that in some applications, it is desirable to use an input or power supply arranged in a three-phase delta configuration or other configuration in which the power supply does not provide a neutral line (or in which the neutral line is used for other purposes). With such a power supply, the LED driver 150 can be connected to any two of the phases of the input source and successfully powered (e.g., able to drive the LED device 160). In particular, the LED driver's phase terminal T1 can be connected to any of the three phases (R, S, T), and the LED driver's neutral terminal T2 can be connected to any of the other two phases.

[0072] For ease of installation, preferably, the phase terminal T1 and the neutral terminal T2 of the LED driver 150 can be connected to any selection of available input lines.

[0073] However, the inventors have recognized that this causes problems with conventional LED driver control circuits 100, since it is not known (at the time of designing the LED driver control circuit) which available input line will be connected to the neutral terminal of the LED driver. Furthermore, different LED drivers may share the same control signal (e.g., have control terminals connected to the same switching output node of the LED driver control circuit), but themselves be connected to arbitrary / different input lines for powering themselves.

[0074] For example, if the neutral terminal of the LED driver is connected to the same phase line as the first switch input node of the LED driver control circuit, then the LED driver will not generate an isolated control signal when the switch S1 controls the switch output node to be connected to the first switch input node (which would be incorrect compared to when implemented with a domestic mains supply).

[0075] Therefore, in a situation where the control terminals T3 of multiple LED drivers are connected to the same switched output node of the LED driver control circuit, but their power / neutral terminals are connected to any two of the available input lines, this issue may lead to erroneous behavior of the isolated control signals in some of the LED drivers, thereby leading to erroneous behavior of at least one corresponding LED device.

[0076] It would therefore be desirable to provide an LED driver control circuit that can be adapted for or used with any configuration in which the LED driver is connected to a three-phase power source that does not have a neutral conductor, or is connected to a three-phase power source without using a neutral conductor.

[0077] Figure 2The LED driver control circuit 200 according to a general embodiment of the present invention is conceptually shown. Instead of directly connecting the first / second switching input nodes to the available phase lines of the three-phase input, first and second voltage control units are used to provide voltage levels to the first / second switching input nodes.

[0078] Specifically, the first voltage control unit 210 provides a voltage to the first switch input node, and the second voltage control unit 220 provides a voltage to the second switch input node.

[0079] The first voltage control circuit 210 is connected between at least one phase line R, S, T of the three-phase input and the first switching input node 116. The first voltage control circuit 210 is arranged so that the voltage at the first switching input node 116 is greater than the instantaneous voltage of each AC signal (carried by each corresponding phase line) during a portion of a cycle of each corresponding AC signal.

[0080] In other words, the first voltage control circuit 210 is designed so that, for at least a portion of the cycle of each signal provided by the available phase line, the voltage at the first switch input node is greater than the instantaneous voltage of the signal. This means that, for at least a portion of the cycle of the alternating signal carried by any given phase line, when the switch output node is connected to the first switch input node, at least some current will flow through the control signal isolator of the connected LED driver, regardless of which phase line the neutral terminal of the LED driver is connected to.

[0081] The second voltage control circuit 220 is connected to the second switching input node 117 and is connectable to at least one phase line of the three-phase input R, S, T. The second voltage control circuit 220 is arranged so that the voltage at the second switching input node is not greater than the instantaneous voltage of any AC signal at any point during a cycle of any AC signal.

[0082] In other words, the second voltage control circuit is designed so that the voltage at the second switch input node is always less than or equal to the instantaneous voltage of each alternating signal carried by the phase line. This means that no matter which phase line the neutral terminal of the LED driver is connected to, no current will flow through the control signal isolator of the LED driver during the cycle of any signal on the phase line.

[0083] The first and / or second voltage control circuits 210, 220 may be connected to a neutral line N of a three-phase input. This neutral line N may be made unavailable to the LED driver controlled by the LED driver control circuit. Specific embodiments using this concept will be explained in more detail below.

[0084] In other examples, the first and second voltage control circuits can be adapted so that the voltage at the first switch input node is less than the instantaneous voltage of each AC signal during a portion of a cycle of each corresponding AC signal, and the voltage at the second switch input node is not less than the instantaneous voltage of any AC signal at any point during the cycle of each corresponding AC signal. Methods for achieving this will be described later.

[0085] Figure 3 An LED driver control circuit 300 according to a first embodiment of the present invention is shown.

[0086] The LED driver control circuit 300 includes a switch S1 that selectively connects the switch output node 115 to the first switch input node 116 and / or the second switch input node 117 . The LED driver control circuit also includes a first voltage control circuit 310 and a second voltage control circuit 320 .

[0087] The first voltage control circuit 310 includes a first diode D1, a second diode D2, and a third diode D3 connected from each corresponding phase line R, S, T of the three-phase input to the first switching input node 116. Specifically, the anode of each diode D1, D2, D3 is connected to the corresponding phase line R, S, T, and the cathode of each diode is connected to the same first switching input node 116.

[0088] In practical terms, this means that the voltage at the first switch input node 116 is not less than the highest instantaneous voltage of each phase line R, S, T. This ensures that the voltage at the first switch input node is greater than the instantaneous voltage of each phase line for at least a portion of the cycle of each signal on the corresponding phase line. In other words, a positive voltage difference exists between the first switch input node 116 and each phase line R, S, T for at least a portion of the cycle of the signal carried by the corresponding phase line R, S, T.

[0089] This results in that, when the switch output node 115 is connected to the first switch input node 116 , current flows through the control signal isolator of the connected LED driver 150 during at least a portion of a cycle of the alternating signal carried by any phase line, regardless of which phase line the neutral terminal T2 of the LED driver 150 is connected to.

[0090] The second voltage control circuit 320 includes a fourth diode D4, a fifth diode D5, and a sixth diode D6 connected from the second switching input node to each corresponding phase line R, S, T of the three-phase input. In particular, the cathode of each diode D4, D5, and D6 is connected to the corresponding phase line R, S, and T, and the anode of each diode is connected to the same second switching input node 117.

[0091] This effectively means that the voltage at the second switch input node is no greater than the lowest instantaneous voltage of each phase line. This results in: when the switch output node is connected to the second switch input node, no current flows through the control signal isolator of the connected LED driver at any point during the mains cycle, regardless of which phase line the neutral terminal of the LED driver is connected to.

[0092] Figure 4 Three illustrative waveforms are provided for the LED driver control circuit according to the first embodiment.

[0093] The first waveform 401 shows the voltage at each phase line R, S, and T of the three-phase input. The first line 401a shows the voltage difference between the first phase line R and the second phase line S. The second line 401b shows the voltage difference between the second phase line S and the third phase line T. The third line 401c shows the voltage difference between the third phase line T and the first phase line R.

[0094] The second waveform 402 shows the voltage at the first switching input node 116 relative to the voltage of each corresponding phase line R, S, and T of the LED driver control circuit 300 of the first embodiment. A first line 402a shows the voltage difference between the first switching input node 116 and the first phase line R. A second line 402b shows the voltage difference between the first switching input node 116 and the second phase line S. A third line 402c shows the voltage difference between the first switching input node 116 and the third phase line T.

[0095] Therefore, it is clear that no matter which of the phase lines R, S, and T the neutral terminal of the LED driver is connected to, when the switch output node 115 is connected to the first switch input node 116, the voltage at the control terminal T3 (connected to the switch output node 115) will always be greater than the voltage at the neutral terminal T2 during at least a portion of the cycle of the alternating current supplied to the neutral terminal. Therefore, current will flow through the control signal isolator at this time.

[0096] The third waveform 403 shows the voltage at the second switching input node 117 relative to the voltage of each corresponding phase line R, S, and T of the LED driver control circuit 300 of the first embodiment. A first line 403a shows the voltage difference between the second switching input node and the first phase line R. A second line 403b shows the voltage difference between the second switching input node and the second phase line S. A third line 403c shows the voltage difference between the second switching input node and the third phase line T.

[0097] Therefore, it is clear that no matter which phase the neutral terminal T2 of the LED driver is connected to, the control terminal T3 (connected to the switch output node 115) will always be less than or equal to the voltage at the neutral terminal T2. Therefore, when the switch output node 115 of the LED driver control circuit (and thus the control terminal T2) is connected to the second switch input node 117, no current flows through the control signal isolator.

[0098] In a variation of the LED driver control circuit 300 of the first embodiment, one of the diodes D1 , D2 , D3 may be removed from the first voltage control unit 310 .

[0099] Therefore, in the second embodiment, the first voltage control circuit 310 may only include a first diode D1 and a second diode D2 connected from the corresponding phase line (R, S) of the three-phase input to the first switch input node. Specifically, the anode of each diode is connected to the corresponding phase line (R, S), wherein the cathode of each diode is connected to the same first switch input node.

[0100] In the second embodiment, the structures of the switch and the second voltage control circuit may be the same as those of the first embodiment.

[0101] Figure 5 Two waveforms are provided for understanding the effects of the LED driver control circuit according to the second embodiment.

[0102] For greater clarity, the first waveform 401 is repeated.

[0103] The fourth waveform 504 shows the voltage at the first switching input node 116 relative to the voltage of each corresponding phase line R, S, T of the LED driver control circuit of the second embodiment.

[0104] A first line 504a shows the voltage difference between the first switching input node and the first phase line R.

[0105] The second line 504b shows the voltage difference between the first switching input node and the second phase line S.

[0106] The third line 504 c shows the voltage difference between the first switching input node and the third phase line T.

[0107] As can be seen from the fourth waveform 504, the voltage between the first switch input node 116 and each input line R, S, T is positive during a portion of each cycle of the alternating signal carried by any given input line R, S, T. Therefore, regardless of which input line R, S, T is connected to the neutral terminal of the LED driver, the control terminal T3 (connected to the switch output node 115) will always be positive relative to the neutral terminal T2 during a portion of each cycle of the alternating signal at the neutral terminal. Therefore, current will flow through the control signal isolator for at least a portion of the mains cycle.

[0108] Note that the fact that the voltage between the switch output node and one of the input lines is negative during part of the mains cycle is not objectionable.

[0109] In other embodiments, the neutral line can still be used to connect to the LED driver control circuit (e.g., but not to the LED driver itself). The above embodiments of the LED driver control circuit are applicable to this situation. However, the availability of the neutral line provides flexibility and scope for further improvement of the LED driver control circuit.

[0110] Figure 6 The third embodiment of the LED driver control circuit 600 is particularly suitable for use when three phase lines R, S, T and a neutral line N are available for connection to the LED driver control circuit 600.

[0111] The LED driver control circuit 600 includes a switch S1 that selectively connects a switch output node to a first and / or second switch input node. The LED driver control circuit 600 also includes a first voltage control circuit 610 and a second voltage control circuit 620.

[0112] The first voltage control circuit 610 includes a first diode D1, a second diode D2, and a third diode D3 in a manner similar to the first embodiment. Specifically, the anode of each diode is connected to the corresponding phase line R, S, T, and the cathode of each diode is connected to the same first switch input node.

[0113] The first voltage control circuit 610 further includes a first capacitor C1 , which is connected between the neutral line N and the first switch input node 116 .

[0114] The provision of the first capacitor C1 means that a positive voltage is stored and maintained (via the first capacitor) at the first switch input node 116. This results in a positive voltage difference between the first switch input node 116 and each phase line R, S, T for at least a portion of each cycle of the alternating signal carried by any corresponding phase line. This, in turn, means that when the switch output node is connected to the first switch input node, a positive voltage difference exists between the control terminal of the connected LED driver and the neutral terminal of the LED driver for at least a portion of the cycle of the signal carried at the neutral terminal (or any phase line).

[0115] Capacitor C1 causes the voltage at the first switch input node to be smoother than in the previously described embodiments.

[0116] The second voltage control circuit 620 includes a fourth diode D4, a fifth diode D5, and a sixth diode D6 in a manner similar to the first embodiment. Specifically, the anode of each diode is connected to the second switching input node 117, and the cathode of each diode is connected to the corresponding phase line R, S, T.

[0117] The second voltage control circuit 620 further includes a second capacitor C2 , which is connected between the neutral line N and the second switch input node 117 .

[0118] Providing the second capacitor C2 means that a negative voltage is stored at the second switch input node 117 (via the second capacitor). This helps ensure that the voltage difference between the second switch input node and any phase line (or neutral line) remains at or below zero. In particular, due to the smoothing effect of the capacitor, the average voltage difference increases. This, in turn, means that when the switch output node is connected to the second switch input node, there is always a negative or zero voltage difference between the control terminal of the connected LED driver and the neutral terminal of the LED driver, regardless of whether the neutral terminal is connected to the input line / neutral line.

[0119] In a variation of the third embodiment, it should be noted that only one of the first, second, and third diodes of the first voltage control circuit is required to achieve the effect of ensuring a positive voltage difference between the first switch input node and each phase line for at least a portion of the cycle of the signal carried by the corresponding phase line. This is because the first capacitor can store and maintain a positive voltage greater than a portion of the cycle of the signal carried by each phase line. Therefore, according to various embodiments, one or both of the first, second, and third diodes can be omitted. This embodiment also provides the option of requiring only two (or possibly three) transmission lines (one of the phase line and the neutral line) to the LED driver control circuit.

[0120] In another variation of the third embodiment, note that only one of the first, second, and third diodes of the second voltage control circuit is required to achieve the effect of ensuring that the voltage difference between the first switch input node and each phase line is zero or negative for the entire cycle of the signal carried by the corresponding phase line. This is because: if a sufficiently large capacitance value is selected for the second capacitor, the second capacitor can store and maintain a negative voltage (between the second switch input node and the neutral line) that is less than or equal to any instantaneous voltage of the signal carried by each phase line. Therefore, according to various embodiments, one or both of the fourth, fifth, and sixth diodes can be omitted.

[0121] Various examples of first and second voltage control circuits have been described according to the embodiments (and variations thereof) of the present invention. A person skilled in the art can easily use different examples of first and second voltage control circuits from different embodiments and variations thereof. For example, one possible embodiment of the present invention employs the first voltage control circuit described with reference to the first embodiment (e.g., as described with reference to Figure 3 and 4 ) and the second voltage control circuit described with reference to the third embodiment (eg, as described with reference to Figure 6 described).

[0122] refer to Figures 3 to 6 The described embodiments are designed to provide a voltage at the first switch input node that is greater than the instantaneous / transient voltage of each AC signal during a portion of a cycle of each corresponding AC signal, and to provide a voltage at the second switch input node that is no greater than the instantaneous / transient voltage of any AC signal at any point during the cycle of each AC signal.

[0123] However, the described embodiments can be adapted so that: the voltage at the first switch input node is less than the instantaneous / transient voltage of each AC signal for a portion of the cycle of each corresponding AC signal, and the voltage at the second switch input node is not less than the instantaneous / transient voltage of any AC signal at any point during the cycle of each corresponding AC signal. This can be achieved by simply reversing the polarity of any diode in the embodiments of the LED driver control circuit, i.e., replacing references to "anode" with "cathode" and vice versa.

[0124] For such an embodiment, refer to Figure 1 The LED driver described can be adapted so that the polarity of the light emitting diode 157 and the (reverse) diode D1 are reversed. This will result in the isolated control signal having a polarity that is similar to the reference Figures 3 to 6 The embodiments described are of the same polarity.

[0125] Figure 7A method 700 according to an embodiment of the present invention is shown. The method is suitable for controlling an LED driver control circuit to generate control signals for an LED driver connectable to a three-phase input comprising three different phases, each phase carrying an AC signal of the same frequency and a different phase.

[0126] The method 700 comprises a first step 701 of controllably connecting a switching output node between a first switching input node and a second switching input node.

[0127] The method 700 further includes a second step 702 of generating a control signal for the LED driver in response to a voltage at the switch output node, wherein the control signal is electrically isolated from the switch output node.

[0128] The method 700 further includes a third step 703 of providing a voltage to the first switching input node using a first voltage control circuit connected between at least one phase line of the three-phase input and the first switching input node.

[0129] The method 700 further includes a fourth step 704 of providing a voltage to the second switching input node using a second voltage control circuit connected to the second switching input node and connectable to at least one phase line of the three-phase input.

[0130] The third step 703 and the fourth step 704 are adapted so that: the voltage provided at the first switch input node is greater than the instantaneous voltage of each AC signal in a portion of the cycle of each corresponding AC signal, and the voltage provided at the second switch input node is not greater than the instantaneous voltage of any AC signal at any point during the cycle of each corresponding AC signal; or the voltage provided at the first switch input node is less than the instantaneous voltage of each AC signal in a portion of the cycle of each corresponding AC signal, and the voltage provided at the second switch input node is not less than the instantaneous voltage of any AC signal at any point during the cycle of each corresponding AC signal.

[0131] Those skilled in the art can easily modify the above method to appropriately control the LED driver control circuit to implement any concept described herein, such as referring to Figures 2 to 6 Describing the conception.

[0132] Those skilled in the art will be able to easily develop a processing system for executing any method described herein.Thus, each step of the flowchart may represent a different action performed by the processing system and may be executed by a corresponding module of the processing system.

[0133] Thus, embodiments may utilize a processing system. A processing system may be implemented in a variety of ways using software and / or hardware to perform the various functions required. A processor is an example of a processing system that employs one or more microprocessors that can be programmed using software (e.g., microcode) to perform the required functions. However, a processing system may be implemented with or without a processor, and may also be implemented as a combination of dedicated hardware to perform certain functions and a processor (e.g., one or more programmed microprocessors and associated circuitry) to perform other functions.

[0134] Examples of processing system components that may be employed in various embodiments of the present disclosure include, but are not limited to, conventional microprocessors, application specific integrated circuits (ASICs), and field programmable gate arrays (FPGAs).

[0135] In various implementations, a processor or processing system may be associated with one or more storage media such as volatile and non-volatile computer memory (such as RAM, PROM, EPROM, and EEPROM). The storage media may be encoded with one or more programs that, when executed on one or more processors and / or processing systems, perform desired functions. The various storage media may be fixed within the processor or processing system, or may be transportable so that one or more programs stored thereon can be loaded into the processor or processing system.

[0136] It should be understood that the disclosed method is preferably a computer-implemented method. Like this, the concept of a computer program comprising a code device is also proposed, and the code device is used to realize any of the methods described when the program is run on a processing system such as a computer. Therefore, the different parts, rows or blocks of the code of the computer program according to the embodiment can be executed by a processing system or a computer to perform any method described herein. In some alternative implementations, the functions indicated in the box may not occur in the order indicated in the figure. For example, depending on the function involved, the two boxes shown in succession can actually be performed substantially simultaneously, or these boxes can sometimes be performed in reverse order.

[0137] By studying the drawings, the disclosure and the appended claims, those skilled in the art can understand and implement variations of the disclosed embodiments when practicing the claimed invention. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may perform the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not mean that a combination of these measures cannot be used to advantage. If a computer program is discussed above, it may be stored / distributed on a suitable medium, such as an optical storage medium or solid-state medium provided with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunications systems. If the term "suitable for" is used in a claim or in the specification, it should be noted that the term "suitable for" is intended to be equivalent to the term "configured to". Any figure marks in the claims should not be interpreted as limiting the scope.

Claims

1. An LED driver control circuit (200, 300, 600) arranged to generate control signals (S) for a plurality of LED drivers (150) connectable to a three-phase input. C ), the three-phase input includes three different phase lines (R, S, T) each carrying an AC signal (410a, 410b, 410c) having the same frequency and different phases, and the LED driver control circuit (200, 300, 600) includes: A switch (S1) adapted to controllably connect a switch output node (115) to a first switch input node (116) or a second switch input node (117), wherein the voltage of the switch output node (115) defines the control signal (S C ); a first voltage control circuit (210, 310, 610) arranged to be connected between at least one phase line of the three-phase input and the first switching input node (116), and arranged to control the voltage (402a, 402, 402c, 504a, 504b, 504c) at the first switching input node (116); as well as a second voltage control circuit (220, 320, 620) arranged to be connected to the second switching input node (117) and at least one phase line of the three-phase input and arranged to control the voltage (403a, 403b, 403c) at the second switching input node, The first voltage control circuit and the second voltage control circuit are configured such that: The voltage at the first switch input node (116) is greater than the instantaneous voltage of each AC signal during a portion of a cycle of each corresponding AC signal, and the voltage at the second switch input node (117) is not greater than the instantaneous voltage of any AC signal at any point during the cycle of each corresponding AC signal; or The voltage at the first switch input node (116) is less than the instantaneous voltage of each AC signal during a portion of a cycle of each corresponding AC signal, and the voltage at the second switch input node (117) is not less than the instantaneous voltage of any AC signal at any point during the cycle of each corresponding AC signal.

2. The LED driver control circuit (300, 600) according to claim 1, wherein the first voltage control circuit (310, 610) comprises: a first diode (D1) connected from a first phase line (R) to the first switch input node (116); as well as A second diode (D2) is connected from the second phase line (S) to the first switch input node.

3. The LED driver control circuit (300, 600) according to claim 2, wherein the first voltage control circuit (310, 610) further comprises a third diode (D3) connected from a third phase line (T) to the first switch input node (116).

4. The LED driver control circuit (600) according to claim 1, wherein the three-phase input further includes a neutral line (N), wherein the first voltage control circuit (610) comprises: a first capacitor (C1) connected between the neutral line (N) and the first switch input node (116); as well as A first diode (D1) is connected between one of the phase lines (R, S, T) and the first switch input node.

5. The LED driver control circuit (600) according to claim 4, wherein the first voltage control circuit (610) comprises a second diode (D2) and a third diode (D3), the first diode (D1), the second diode (D2), and the third diode (D3) connecting respective phase lines (R, S, T) of the three-phase input to the first switch input node (116).

6. The LED driver control circuit (300, 600) according to any one of claims 1 to 5, wherein the second voltage control circuit (320, 620) comprises three diodes (D4, D5, D6), each diode connecting the second switching input node (117) to a respective phase line (R, S, T) of the three-phase input.

7. The LED driver control circuit (600) according to claim 4, wherein the second voltage control circuit (620) comprises: a second capacitor (C2) connected between the neutral line and the second switch input node (117); as well as A diode (D4, D5, D6) is connected from the second switch input node (117) to one of the phase lines (R, S, T) of the three-phase input.

8. An LED driver system comprising: The LED driver control circuit (200, 300, 600) according to any one of claims 1 to 7; An LED driver for driving an LED device (160) is connectable to the three-phase input and responsive to the control signal (S) generated by the LED driver control circuit. C ).

9. The LED driver system according to claim 8, wherein the LED driver (150) comprises a control signal isolator (155), the control signal isolator (155) being adapted to receive the control signal (S C ), and generates an isolated control signal (S) based on the difference between the control signal and the AC signal carried by one of the phase lines (R, S, T) CI ), wherein the isolation control signal (S CI ) is isolated from components that control the LED device (160).

10. The LED driver system according to claim 9, wherein the control signal isolator comprises: a light emitting diode (157) connected between the switch output node and one of the phase lines and adapted to generate light in response to a voltage at the switch output node; A light-responsive circuit (158) is adapted to receive the light generated by the light emitting diode and generate the control signal.

11. The LED driver system according to claim 10, wherein the control signal isolator (155) further comprises a reverse current diode (D I ), the reverse current diode (D I ) is connected between the switch output node and a phase line that is the same as the light emitting diode, wherein the polarity of the control diode is opposite to that of the light emitting diode.

12. The LED driver system according to any one of claims 8 to 11, wherein the LED driver is adapted to control a current flowing through the LED device in response to the control signal.

13. An LED system comprising: The LED driver system according to any one of claims 8 to 12; as well as An LED device (160) is formed by one or more LEDs driven by the LED driver system.

14. An LED system comprising: The LED driver control circuit according to any one of claims 1 to 7; a plurality of LED drivers for driving respective LED devices, the plurality of LED drivers being connectable to the three-phase input and responsive to the control signals generated by the LED driver control circuit; as well as A plurality of LED devices driven by corresponding LED drivers, the number of LED devices being equal to the number of LED drivers.

15. A method (700) of controlling an LED driver control circuit (200, 300, 600) for generating control signals (S) for a plurality of LED drivers (150) connectable to a three-phase input. C ), the three-phase input includes three different phase lines (R, S, T) each carrying an AC signal (410a, 410b, 410c) having the same frequency and a different phase, the method comprising: controllably connecting (701) the switch output node (115) to the first switch input node (116) or the second switch input node (117); Generate (702) the control signal (Sc) for the plurality of LED drivers (150), wherein the voltage at the switch output node (115) defines the control signal (Sc) C ); providing (703) a voltage to the first switching input node (116) using a first voltage control circuit (210, 310, 610) connected between at least one phase line of the three-phase input and the first switching input node (116); as well as providing (704) a voltage to the second switching input node (117) using a second voltage control circuit (220, 320, 620), the second voltage control circuit (220, 320, 620) being connected to the second switching input node (117) and being connectable to at least one phase of the three-phase input, in: The voltage provided at the first switch input node (116) is greater than the instantaneous voltage of each AC signal in a portion of the cycle of each corresponding AC signal, and the voltage provided at the second switch input node (117) is not greater than the instantaneous voltage of any AC signal at any point during the cycle of each corresponding AC signal; or the voltage provided at the first switch input node (116) is less than the instantaneous voltage of each AC signal in a portion of the cycle of each corresponding AC signal, and the voltage provided at the second switch input node (117) is not less than the instantaneous voltage of any AC signal at any point during the cycle of each corresponding AC signal.

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