Connected bulb RC latch optimized for low standby power

Abstract

The invention relates to a driver for driving a lighting load, the driver comprising a rectifier adapted to receive an alternating current (AC) input voltage and adapted to provide a rectified voltage; a converter adapted to convert the rectified voltage to an output voltage for a lighting load; a controller for controlling the converter and the switching element; and a latch circuit adapted to receive an alternating input voltage or a rectified voltage and comprising a series combination of a resistor, a capacitor and a switching element, where the controller is arranged to configure the converter in an active mode and a standby mode, and when the controller configures the converter in the active mode, the latch circuit is configured to receive the alternating input voltage or the rectified voltage and comprises a series combination of a resistor, a capacitor and a switching element. The switching element is closed when the converter is in a standby mode and is opened when the controller configures the converter in a standby mode.

Description

Technical Field

[0001] The present invention relates to a driver, a lighting system and a method. Background Art

[0002] Over time, awareness of the energy efficiency of lighting products has increased. Most of the attention has been focused on the efficiency of lamps in active mode. New regulations require lamps to become more efficient. With the popularity of radio wave wirelessly controlled LED lamps, more attention has been paid to the standby power of wireless LED lamps. These lamps are controlled by wireless switches, sensors or apps and are always connected to the mains. In an average home, there can be dozens of these wireless lamps, so since these lamps are in standby mode for a considerable period of time during the day, the energy consumption of the lamps in standby mode can be quite significant. The current legislative status requires a standby power of less than 0.5W, so this may mean a continuous standby power of several watts or even more than 10W in a home. It is expected to further reduce the standby power of lamps to further reduce the energy consumption of lighting products. Summary of the invention

[0003] It is an object of the present invention to provide a driver which requires less power during standby operation.

[0004] In a first aspect of the present invention, a driver for driving a lighting load is provided, the driver comprising:

[0005] a rectifier adapted to receive an alternating current (AC) input voltage and adapted to provide a rectified voltage;

[0006] a converter adapted to convert the rectified voltage into an output voltage for a lighting load;

[0007] controller for controlling the converter and the switching elements, and

[0008] a latch circuit adapted to receive an AC input voltage or a rectified voltage and comprising a series combination of a resistor, a capacitor and a switching element,

[0009] The controller is arranged as:

[0010] Configure the converter in active and standby modes;

[0011] When the controller configures the converter to be in active mode, the switching element is closed, and

[0012] When the controller configures the converter to be in the standby mode, the switching element is turned off.

[0013] The driver has a converter that converts the AC input voltage into a voltage that can be used by the lighting load. The rectifier rectifies the AC voltage into a rectified voltage. The driver has a latch circuit that can be used to improve compatibility with a phase-cut dimmer. The latch circuit also has a series connection of a resistor, a capacitor and a switching element. The driver has a controller that is used to control the converter and the switching element. The controller can put the converter in an active mode and a standby mode. In the active mode, the converter can provide regulated power to the lighting load. In the standby mode, the converter can be passive, that is, no power is provided to the lighting load. The AC input voltage is provided by the phase-cut dimmer. When the phase-cut dimmer becomes active, the latch circuit provides additional current, that is, when the voltage to the driver increases at a phase angle, additional current is drawn. This improves the compatibility of the driver with the phase-cut dimmer. However, the latch circuit also provides additional losses. When the controller configures the converter to be in standby mode, the latch circuit can also be cut off. Therefore, when the converter is set to standby mode, the controller disconnects the switching element. The latch circuit does not draw any current, so the latch circuit does not dissipate any power. At this point, the phase-cut dimmer may not operate properly, but this is no longer relevant because the operation is invisible to the user. When the converter is configured in active mode, it is expected that compatibility with the phase-cut dimmer exists, which might otherwise be reflected in the light output of the lighting load, and the switching element is closed, allowing the latch circuit to become active.

[0014] In another example, the latch circuit is adapted to receive an AC input voltage, and wherein the latch circuit comprises another rectifier, wherein the switching element is a semiconductor direct current (DC) switch and is coupled at an output of the another rectifier and arranged to shunt the output of the another rectifier.

[0015] To improve the impact on compatibility with phase-cut dimmers, a latch circuit can be placed before the rectifier and coupled to the AC input voltage. Another rectifier can be provided to provide a rectified voltage to the switching element. The switching element can then be a semiconductor that can only be safely operated at a DC voltage, such as a MOSFET. When the switching element is now in a DC operating state, the controller can provide a control signal to the switching element, so no adaptation for AC voltage operation is required. The switching element is then used to shunt the output of the other rectifier.

[0016] In another example, the latch circuit is adapted to receive an AC input voltage, and wherein the switching element is a relay.

[0017] The relay provides galvanic isolation between the control input and the switch input. The relay can be any type of relay, such as, for example, an electromechanical relay or a solid-state relay. In this case, no further rectifier is required, and the controller can directly provide a control signal to the control input.

[0018] In another example, the driver includes an auxiliary power supply for powering the controller.

[0019] Preferably, an auxiliary power supply is provided for powering the controller. When the converter is in standby mode, it may still be desirable to keep the controller powered. This allows the controller, for example, to receive and process information that can be used to configure the converter to be in active mode. The auxiliary power supply may only need to provide a small amount of power to the controller compared to the power that needs to be provided to the lighting load. In addition, in standby mode, the phase-cut dimmer may not operate normally, but this has no effect on the power supply to the controller.

[0020] In another example, an input of the auxiliary power supply is coupled to a switching element, wherein the auxiliary power supply is arranged to provide a conductive path for current to flow through the resistor and the capacitor when the switching element is open.

[0021] The auxiliary power supply may receive its power via the resistor and capacitor of the latch circuit. Therefore, it is necessary to open the switching element so that the auxiliary power supply can provide a conductive path for the current to flow at least through the capacitor. This current is then used by the auxiliary power supply to provide an auxiliary output voltage that can be used, for example, by the controller. When the switching element is open, the auxiliary power supply provides a conductive path.

[0022] In another example, the driver includes a phase-cut dimmer detection circuit adapted to detect the presence of a phase cut in the AC input voltage.

[0023] It may be desirable to detect the presence of a phase-cut dimmer. This may allow other functions to be implemented, such as, for example, allowing phase-cut dimming or determining the type of phase-cut dimmer.

[0024] In another example, the controller is further arranged to close the switching element in the active mode when the phase cut dimmer detection circuit detects a phase cut in the AC input voltage.

[0025] To reduce power losses during operation of the driver and when the converter is active, the switch element may be closed when a phase-cut dimmer is detected and when the controller has configured the converter to be in active mode. When a phase-cut dimmer is not detected, a latch circuit may not be required. Therefore, it is desirable to close the switch only when a phase-cut dimmer has been detected and when the converter is active.

[0026] In another example, the controller is arranged to receive wireless control commands for controlling the converter.The controller may receive control commands for controlling the converter and thus also light generated by the lighting load.

[0027] Preferably, the control command is sent in a wireless manner, which facilitates communication between remote control devices (eg, mobile phones or remote controllers). When the converter is in standby mode, the controller can still receive wireless control commands.

[0028] In another example, the converter is a switch mode power supply.

[0029] The converter may be a switched mode power supply (SMPS) which can be easily configured to be in an active mode and a standby mode. Additionally, SMPSs are very energy efficient and therefore desirable for use in lighting applications.

[0030] In another example, the auxiliary power supply is a switch mode power supply.

[0031] Similar to the converter, the auxiliary power supply is desirably a SMPS. Because the auxiliary power supply only needs to provide a relatively small amount of power compared to the converter, the auxiliary power supply may be relatively small.

[0032] In another example, a lighting system includes a driver according to the present invention and a lighting load.

[0033] Preferably, the driver is a part of the lighting system. The introduction of the driver improves the energy efficiency of the entire lighting system.

[0034] In another example, the lighting load is a solid state lighting load.

[0035] Solid-state lighting loads require a small amount of power compared to traditional lighting loads. Reducing the power consumption of the driver has a significant impact on the overall power consumption of the lighting system. The solid-state lighting load can be, for example, any of the following: LEDs, laser diodes, or vertical cavity surface emitting lasers (VCSELs).

[0036] In another example, a method for controlling a driver includes:

[0037] a converter adapted to convert the rectified voltage into an output voltage for a lighting load;

[0038] controller for controlling the converter and the switching elements, and

[0039] a latch circuit adapted to receive an AC input voltage or a rectified voltage and comprising a series combination of a resistor, a capacitor and a switching element,

[0040] The method comprises the following steps:

[0041] Configure the converter to be in active mode;

[0042] Configure the converter to be in standby mode;

[0043] closing the switching element when the converter is in active mode, or closing the switching element when the converter is in active mode and when a phase cut has been detected, and

[0044] When the converter is in standby mode, the switching element is turned off.

[0045] The method allows controlling the driver according to the invention by configuring the converter in an active mode and in a standby mode. When the converter is in the active mode, the switching element is closed, and when the converter is in the standby mode, the switching element is open. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Now, examples of the present invention will be described with reference to the accompanying drawings, in which

[0047] Figure 1 An example of a driver according to the prior art is shown.

[0048] Figure 2 Another example of a driver according to the prior art is shown.

[0049] Figure 3 An example of a driver according to the invention is shown.

[0050] Figure 4 Another example of a driver according to the invention is shown.

[0051] Figure 5 Another example of a driver according to the invention is shown.

[0052] Figure 6 Another example of a driver according to the invention is shown.

[0053] Figure 7 A flow chart for controlling a driver according to the present invention is shown. DETAILED DESCRIPTION

[0054] The present invention is described with reference to the accompanying drawings.

[0055] It should be understood that the detailed description and specific examples, although indicating exemplary embodiments of the device, system and method, are intended for illustrative purposes only and are not intended to limit the scope of the invention. These and other features, aspects and advantages of the device, system and method of the present invention become better understood from the following description, the appended claims and the accompanying drawings. It should also be understood that the drawings are only schematic and are not drawn to scale. It should also be understood that the same reference numerals are used in all drawings to indicate the same or similar parts.

[0056] Figure 1 A drive known from the prior art is shown. The drive is coupled to a phase-cut dimmer that provides a phase-cut in the mains voltage. A rectifier 5 is used to rectify the AC input voltage and provide a rectified voltage between the outputs of the rectifier 5. The rectified voltage is provided to a converter 1. The converter 1 converts the rectified voltage into an output voltage that is coupled to a lighting load LED. A controller 3 is provided to control the converter 1. The controller 3 can configure the converter 1 to be in an active mode and a standby mode. A latch circuit is used to improve the compatibility between the drive and the phase-cut dimmer. When the phase-cut dimmer is active, the input voltage rises sharply. This is the rising edge of the input voltage. At this point, the triac in the phase-cut dimmer is closed. In order to properly close the triac, a large current is required at the moment when the triac is closed, which is also referred to as a latch current. If the current is too low, the triac may switch off again and no voltage is supplied to the driver, and this may cause instability in the output power. The latch circuit has a series combination of resistor R1 and capacitor C1, which draws a current that is maximum at the instant the triac switches on. This additional current allows the triac to be started correctly. When the converter 1 is in standby mode, the latch circuit is still active, so power is also lost in the latch circuit.

[0057] Figure 2 Another example of a driver as known in the prior art is shown. The basic structure of the driver is similar to Figure 1 The basic structure of the driver is similar to that of FIG. The latch circuit is now placed after the rectifier 5 and is coupled to the rectified voltage. The latch circuit still performs the same function, however, it is less effective in providing latching and holding current for the triac dimmer.

[0058] Figure 3An example of a driver according to the present invention is shown. The driver has a rectifier 5 that rectifies an AC input voltage and provides a rectified voltage at the output of the rectifier 5. The rectified voltage is provided to a converter 1. The converter converts the rectified voltage into an output voltage provided to a lighting load LED. A controller 3 is used to control the converter 1. The controller 3 is arranged to configure the converter 1 to be in an active mode and a standby mode. When the converter 1 is in the active mode, the output voltage can be provided to the lighting load LED so that the lighting load LED is powered. When the converter 1 is in the standby mode, the converter 1 cannot provide the output voltage to the lighting load LED, thereby preventing the lighting load LED from emitting any light. In the example provided, the latch circuit 4 has a series combination of a resistor R1, a capacitor C1 and a switching element M1. The latch circuit 4 is placed at the output of the rectifier 5 and receives the rectified voltage. The controller 3 provides a control signal to the switching element M1. When the converter 1 is configured to be in the active mode, the controller 3 provides a control signal for closing the switching element M1. When the converter 1 is active, the latch circuit is also active. As long as the phase-cut dimmer operates correctly, the converter 1 can provide a correctly regulated output voltage for the lighting load LED. When the converter 1 is in standby, the controller 3 provides a control signal for disconnecting the switching element M1 to the switching element M1. When the converter 1 is not active, for example, in standby, compatibility with the phase-cut dimmer is no longer relevant. Therefore, the latch circuit 4 is cut off by disconnecting the switching element M1 so that the current does not flow through the resistor R1 and the capacitor C1. During the standby period of the converter 1, there is no power loss in the latch circuit 4. Placing the latch circuit 4 coupled to the rectified voltage in the DC path has the following benefits: the switching element M1 can be easily controlled. The control signal provided by the controller 3 can be directly coupled to the switching element M1. In this example, the switching element can be any type of switching element that can be controlled using an electrical signal. An example of such a switching element M1 can be a semiconductor switch, such as a MOSFET, an IGBT, or a bipolar transistor.

[0059] Figure 4 Another example of a driver is shown. The driver has Figure 3 The latch circuit 4 is now placed before the rectifier 5 and is coupled to the AC input voltage. The resistor R1 and the capacitor C1 can be connected as shown in FIG. Figure 3 The resistors and capacitors shown are identical. However, for the circuit to operate correctly, capacitor C1 needs to be split into two parts: C1 and C1', as shown in Figure 4This is due to the fact that the rectifier 5 and the further rectifier 6 share the same ground. The capacitor C1' prevents a DC path that could create high currents due to the phase difference between the two rectifiers. The switching element M1 is coupled to the resistor R1 and the capacitors C1, C1' via the further rectifier 6. The further rectifier provides a further rectified voltage at its output. The switching element M1 is coupled across the output of the further rectifier 6 so that when the switching element M1 is closed, the output of the further rectifier 6 is shunted. The use of the further rectifier 6 allows the switching element 6 to be connected to the same Figure 3 The illustrated switching element M1 is controlled in a similar manner. The controller 3 may provide a control signal to the switching element M1.

[0060] Figure 5 Another example of a driver is shown. The driver has Figure 3 and Figure 4 The latch circuit 4 is now placed before the rectifier 5 and is coupled to the AC input voltage. The resistor R1 and the capacitor C1 can be connected as shown in FIG. Figure 3 and Figure 4 The resistors and capacitors shown are the same. The switching element U1 is: a relay having an input for a relay control signal, and a relay switching element that can be opened or closed based on the relay control signal. The input for the relay control signal is galvanically isolated from the relay switching element. This allows the relay switching element to be directly coupled to the resistor R1 and capacitor C1. The input for the relay control signal can be directly coupled to the controller 3 and receive the control signal. The behavior of the relay may be different from Figure 3 and Figure 4 The switch elements shown are similar. When the relay switch element is closed, the latch circuit 4 is operational. When the relay switch element is open, the latch circuit 4 is inoperative. Examples of relays are electromechanical relays and solid-state relays.

[0061] In the example provided, an auxiliary power supply 2 may be provided to provide power to the controller 3. When the converter 1 is in standby mode, the auxiliary power supply 2 may still be active. This allows the controller 3 to be powered even when the converter 1 is in standby. The controller 3 can then still send and receive information that can be used to control the drive.

[0062] exist Figure 6 In FIG. 1 , an example of a driver is provided, in which an auxiliary power source 2 is coupled to a switching element M1. The connection of the switching element M1 is Figure 4The switching element M1 is similar to the switching element shown. The switching element M1 is coupled to the resistor R1, the capacitor C1 and the capacitor C1' via the further rectifier 6. The further rectifier provides another rectified voltage at its output. The switching element M1 is coupled across the output of the further rectifier 6 so that when the switching element M1 is closed, the output of the further rectifier 6 is shunted. The use of the further rectifier 6 allows the switching element 6 to be connected to the same Figure 3 The switch element M1 shown is controlled in a similar control manner. The controller 3 can provide a control signal to the switch element M1. The auxiliary power supply 2 is coupled across the switch element M1. This means that when the switch element M1 is closed, the switch element M1 also shunts the input of the auxiliary power supply 2. When the switch element M1 is disconnected, the converter 1 is in standby mode, and the voltage across the switch element M1 is provided to the auxiliary power supply 2. In this example, when the converter 1 is in standby mode, the latch circuit 4 can achieve a different function, namely providing a low power path for the auxiliary power supply 2. When the converter 1 is active and the switch element M1 is closed, the auxiliary power supply 2 can be powered via another power source. The converter 1 can provide power to the auxiliary power supply 2, for example, via an auxiliary winding of a transformer / inductor of the converter 1. Alternatively, when the converter 1 is active, the switch element M1 may be disconnected, and the auxiliary power supply 2 can then receive current from the resistor R1 and the capacitor C1, so that the latch circuit 4 still operates during the active mode of the converter 1. The switching element M1 combined with the circuit system in the auxiliary power supply 2 that allows the latch circuit 4 to be active may be regarded as the switching element M1 that performs closing and opening based on the control signal from the controller 3 according to the present invention.

[0063] Figure 7 A method for controlling a drive according to the present invention is shown. The drive may be such as Figure 3 , Figure 4 , Figure 5 and Figure 6 Any of the drivers shown and described. The method comprises the step of switching on the driver at the moment of start-up. This may be, for example, when the input voltage is first provided. When or immediately after switching on the driver, the latch circuit 4 is switched on. This is done by closing the switching element M1. After activating the latch circuit 4, the luminaire is switched on by switching on the converter 1 and power is supplied to the lighting load LED so that light is generated. When the lighting load LED is switched off, i.e. the converter 1 is configured to be in standby mode, the latch circuit 4 is cut off by opening the switching element M1. Furthermore, the circuit detects whether a dimmer is present. As long as the lighting load LED is not switched off and a dimmer is detected, the latch circuit 4 is still active, i.e. the switching element M1 is still closed.

[0064] The driver is preferably used in a lighting system. The lighting system comprises a driver and a lighting load LED. Preferably, the lighting load LED is a solid-state lighting load.

[0065] The lighting system can be connected to a phase-cut dimmer. In the example provided, the lighting system is required to be compatible with the phase-cut dimmer, which means that during operation of the lighting load LED, the phase-cut dimmer needs to operate correctly and preferably without any interference. When the converter 1 is active and the lighting load LED is powered on, the driver provides an active latch circuit 4. When the lighting system enters a standby state, the converter 1 is in the standby state and the lighting load LED is turned off. Then, the latch circuit 4 is also turned off to keep the standby power of the lighting system as low as possible.

[0066] In the example provided, the auxiliary power supply 2 and / or the converter 1 may be a switched mode power supply. Examples of switched mode power supplies are a boost converter, a buck converter, a buck-boost converter, a flyback converter and an LLC converter.

[0067] In the example provided, the driver may also have a phase-cut dimmer detection circuit. The phase-cut dimmer detection circuit may detect a phase cut in the AC input voltage. This detection may be used to close the switching element M1 also based on the detection of a phase-cut dimmer. When a phase-cut dimmer is not present, in order to provide a more energy efficient driver, the driver does not require an active latch circuit 4 when the converter 1 is active. Thus, the switching element M1 will only be closed when the converter 1 is active and when a phase-cut dimmer has been detected.

[0068] Other variations of the disclosed embodiments may be understood and implemented by those skilled in the art in practicing the claimed invention by studying the drawings, the disclosure and the appended claims. 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. The fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be interpreted as limiting the scope.

Claims

1. A driver for driving a lighting load (LED), the driver comprising: a rectifier (5) adapted to receive an alternating current (AC) input voltage and adapted to provide a rectified voltage; A converter (1) adapted to convert the rectified voltage into an output voltage for the lighting load (LED); a controller (3) arranged to control the converter (1) and the switching element (M1), and a latch circuit (4) configured to receive the AC input voltage or the rectified voltage and comprising a series combination of a resistor (R1), a capacitor (C1) and the switching element (M1), The controller (3) is arranged as follows: Configuring the converter (1) to be in an active mode and a standby mode; When the controller (3) configures the converter (1) to be in the active mode, the switching element (M1) is closed, and When the controller (3) configures the converter (1) to be in the standby mode, the switching element (M1) is turned off.

2. A driver according to claim 1, wherein the latch circuit (4) is adapted to receive the AC input voltage, and wherein the latch circuit (4) includes another rectifier (6), wherein the switching element (M1) is a semiconductor direct current (DC) switch, coupled at the output of the other rectifier (6) and arranged to shunt the output of the other rectifier (6), wherein the capacitor C1 is arranged as two separate capacitors (C1, C1'), each capacitor being connected to one of the input terminals of the other rectifier (6).

3. The driver according to claim 1, wherein the latch circuit (4) is adapted to receive the AC input voltage, and wherein the switching element (M1) is a relay.

4. The drive according to any one of the preceding claims, further comprising an auxiliary power supply (2) for powering the controller (3).

5. A driver according to claim 4, wherein an input of the auxiliary power supply (2) is coupled to the switching element (M1), wherein the auxiliary power supply (2) is arranged to provide a conductive path for current to flow through the capacitor (C1) when the switching element (M1) is open.

6. A driver according to any one of the preceding claims, further comprising a phase cut dimmer detection circuit adapted to detect the presence of a phase cut in the AC input voltage.

7. Driver according to claim 6, wherein the controller (3) is further arranged to close the switching element (M1) in the active mode when the phase-cut dimmer detection circuit detects a phase-cut in the AC input voltage.

8. A drive according to any of the preceding claims, wherein the controller (3) is arranged to receive wireless control commands for controlling the converter (1).

9. A driver according to any one of the preceding claims, wherein the converter (1) is a switched mode power supply.

10. Driver according to any one of claims 4 or 5, wherein the auxiliary power supply (2) is a switch mode power supply.

11. A lighting system comprising the driver according to any one of the preceding claims and the lighting load (LED).

12. The lighting system of claim 11, wherein the lighting load (LED) is a solid-state lighting load.

13. A method for controlling a driver, the driver comprising: A converter (1) adapted to convert the rectified voltage into an output voltage for a lighting load (LED); A controller (3) for controlling the converter (1) and the switching element (M1), and a latch circuit (4) adapted to receive an AC input voltage or the rectified voltage and comprising a series combination of a resistor (R1), a capacitor (C1) and the switching element (M1), The method comprises the following steps: Configuring the converter (1) to be in active mode; Configuring the converter (1) to be in a standby mode; When the converter (1) is in the active mode, the switching element (M1) is closed, or when the converter (1) is in the active mode and when a phase cut has been detected, the switching element (M1) is closed, and When the converter (1) is in the standby mode, the switching element (M1) is turned off.

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