Monitoring of current by light-emitting diodes, system and method therefor

Abstract

A circuit (110, 210, 310, 601) configured to monitor current through one or more strings (130, 230, 330, 618, 620) of light-emitting diodes, the circuit (110, 210, 310, 601) comprising: a power converter unit (112, 212, 312, 602), wherein the power converter unit (112, 212, 312, 602) is configured to receive an input signal from an energy source, and wherein the power converter unit (112, 212, 312, 602) is designed to output an output signal to the one or more strings (130, 230, 330, 618, 620) of light-emitting diodes, the output signal comprising an output voltage and comprises an output current; a setpoint unit (114, 214, 314) designed to to output a setpoint signal to the power converter unit (112, 212, 312, 602), wherein the power converter unit (112, 212, 312, 602) is designed to regulate the output current so that it is proportional to a setpoint parameter value associated with the setpoint signal; and a correction unit (116, 216, 316) designed to: to receive an input parameter value, wherein the input parameter value is proportional to the input signal; to receive an output parameter value, wherein the output parameter value is proportional to the output voltage; to receive the setpoint parameter value, wherein the setpoint parameter value is proportional to the setpoint signal; and to output a correction signal to the power converter unit (112, 212, 312, 602) based on the input parameter value, the output parameter value and the setpoint parameter value.

Description

field of technology

[0001] This disclosure relates to circuits for monitoring the driving and controlling of strings of light-emitting diodes, and corresponding systems and methods. background

[0002] Drivers are often used to control a voltage, current, or power at a load. For example, a light-emitting diode (LED) driver can control the power supplied to a string of light-emitting diodes. Some drivers may include a DC-DC power converter, such as a buck-boost converter, step-down converter, boost converter, or other DC-DC converter. Such DC-DC converters can be used to control and potentially change the power to the load based on a characteristic of the load. DC-DC power converters can be particularly useful for regulating the current through LED strings. In some cases, LED driver circuits can accept an input signal comprising an input current and an input voltage and provide an output signal comprising an output current and an output voltage.In some such cases, an LED driver circuit can regulate at least some aspects of the input signal and the output signal, such as controlling the output current emitted by the LED driver circuit. Such drivers are known, for example, from the documents US 2013 / 0 169 172 A1, DE 10 2014 117 578 A1, and US 10 085 314 B1. Summary

[0003] A circuit according to claim 1, a system according to claim 12 and a method according to claim 13 are provided.

[0004] Further embodiments are defined in the dependent claims. This disclosure is generally directed to devices, systems, and techniques for outputting an electrical signal to one or more strings of light-emitting diodes (LEDs) using a circuit and regulating at least one parameter of the electrical signal using the circuit. For example, the circuit comprises a power converter unit and a setpoint unit, wherein the setpoint unit is configured to output a setpoint signal to the power converter unit. Based on the setpoint signal, the power converter unit may regulate the output signal to be proportional to a setpoint parameter value associated with the setpoint signal.In some cases, when a parameter associated with the input signal, the output signal, or the setpoint signal changes, the circuit may react by causing an overshoot in a parameter associated with the output signal. The circuit accordingly includes a correction unit configured to receive a set of inputs including, for example, an input parameter value proportional to the input signal, an output parameter value proportional to the output signal, and a setpoint value proportional to the setpoint signal. The correction unit outputs a correction signal to the power conversion unit based on any one or more of the input parameter value, the output parameter value, and the setpoint parameter value, thereby causing the power conversion unit to reduce an amount of overshoot in the parameter associated with the output signal.It may be advantageous to reduce the amount of overshoot in the parameter associated with the output signal, since such overshoot may cause damage to the one or more strings of LEDs.

[0005] In some examples, a circuit is configured to monitor the current through one or more strings of LEDs. The circuit includes a power conversion unit, wherein the power conversion unit is configured to receive an input signal from a power source, and wherein the power conversion unit is configured to provide an output signal to the one or more strings of LEDs, the output signal comprising an output voltage and an output current, and a setpoint unit configured to provide a setpoint signal to the power conversion unit, wherein the power conversion unit is configured to regulate the output current to be proportional to a setpoint parameter value associated with the setpoint signal.Furthermore, the circuit comprises a correction unit configured to receive an input parameter value, wherein the input parameter value is proportional to the input signal, to receive an output parameter value, wherein the output parameter value is proportional to the output voltage, to receive a setpoint parameter value, wherein the setpoint parameter value is proportional to the setpoint signal, and to output a correction signal to the power converter unit based on the input parameter value, the output parameter value, and the setpoint parameter value.

[0006] In some examples, a system includes one or more strings of light-emitting diodes (LEDs), a power source, and circuitry configured to monitor the current through one or more strings of LEDs. The circuitry includes a power conversion unit, the power conversion unit configured to receive an input signal from a power source, and the power conversion unit configured to provide an output signal to the one or more strings of LEDs, the output signal comprising an output voltage and an output current, a setpoint unit configured to provide a setpoint signal to the power conversion unit, the power conversion unit configured to regulate the output current to be proportional to a setpoint parameter value associated with the setpoint signal, and a correction unit.The correction unit is configured to receive an input parameter value, wherein the input parameter value is proportional to the input signal, to receive an output parameter value, wherein the output parameter value is proportional to the output voltage, to receive a setpoint parameter value, wherein the setpoint parameter value is proportional to the setpoint signal, and to output a correction signal to the power converter unit based on the input parameter value, the output parameter value, and the setpoint parameter value.

[0007] In some examples, a method includes receiving, by a power conversion unit of a circuit configured to monitor the current through one or more strings of light-emitting diodes (LEDs), an input signal from a power source, the power conversion unit providing an output signal to the one or more strings of LEDs, the output signal comprising an output voltage and an output current, and a setpoint unit providing a setpoint signal to the power conversion unit, the power conversion unit regulating the output current to be proportional to a setpoint parameter value associated with the setpoint signal.The method further comprises receiving an input parameter value by a correction unit, wherein the input parameter value is proportional to the input signal, receiving an output parameter value by the correction unit, wherein the output parameter value is proportional to the output voltage, receiving a setpoint parameter value by the correction unit, wherein the setpoint parameter value is proportional to the setpoint signal, and outputting a correction signal to the power converter unit by the correction unit based on the input parameter value, the output parameter value, and the setpoint parameter value.

[0008] The summary of the invention is intended to provide an overview of the subject matter described in the present disclosure. It is not intended to be an exclusive or exhaustive explanation of the systems, devices, and methods described in detail in the accompanying drawings and the description below. Further details of one or more examples of the present disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, as well as from the claims. Short description of the drawings Fig. 1 is a block diagram illustrating an exemplary system including circuitry for accepting an input signal from a power source and providing an output signal to one or more strings of light-emitting diodes (LEDs) in accordance with one or more techniques of the present disclosure. Fig. 2 is a circuit diagram illustrating an exemplary system including circuitry for accepting an input signal from a power source and providing an output signal to one or more strings of LEDs in accordance with one or more techniques of the present disclosure. Fig. 3 is a circuit diagram illustrating another exemplary system including circuitry for receiving an input signal from a power source and providing an output signal to one or more strings of LEDs in accordance with one or more techniques of the present disclosure. Fig. 4A is a graph illustrating an output voltage plot, a comparison signal plot, and an output current plot over a period of time in which the output current is reduced from a first output current value to a second output current value in accordance with one or more techniques of the present disclosure. Fig. 4B is a graph illustrating a first gain / comparison signal diagram and a second gain / comparison signal diagram according to one or more techniques of the present disclosure. Fig. 5A is a graph illustrating an output voltage plot, a comparison signal plot, and an output current plot over a period of time in which the output voltage is increased from a first output voltage value to a second output voltage value in accordance with one or more techniques of the present disclosure. Fig. 5B is a graph illustrating a first gain / comparison signal diagram and a second gain / comparison signal diagram according to one or more techniques of the present disclosure. Fig. 6 is a block diagram illustrating an example system including a first LED string and a second LED string and an LED driver in accordance with one or more techniques of the present disclosure. Fig. 7 is a flowchart illustrating an example process for providing a correction signal to reduce output current overshoot, in accordance with one or more techniques of the present disclosure.

[0009] The same reference symbols refer to the same elements throughout the description and the figures. Detailed description

[0010] Some systems may use a power converter, such as a direct current (DC-DC) converter, to control an electrical signal supplied to one or more strings of light-emitting diodes (LEDs). This disclosure is directed to a circuit comprising a power converter unit, a setpoint unit, and a correction unit, wherein the correction unit is configured to reduce overshoot of an output signal provided by the power converter unit to the one or more strings of LEDs. Such overshoot may, in some cases, be caused by a change in one or more parameters associated with the circuit, such as a setpoint parameter value corresponding to a setpoint signal emitted by the setpoint unit. The techniques and circuits described herein may be particularly useful in vehicle lighting applications including one or more strings of LEDs.

[0011] Fig. 1 shows a block diagram of an exemplary system 100 including circuitry 110 for receiving an input signal from power source 120 and providing an output signal to one or more strings of LEDs 130 in accordance with one or more techniques of the present disclosure. As in the example of Fig. 1, the system 100 includes the circuit 110, the energy source 120, and the LEDs 130. The circuit 110 includes the power converter unit 112, the setpoint unit 114, and the correction unit 116.

[0012] The circuit 110 may include circuit elements including resistors, capacitors, inductors, diodes, semiconductor switches, and other semiconductor elements. In the Fig. 1, the circuit 110 includes a power conversion unit 112. The power source 120 may provide an input signal to the power conversion unit 112, thereby powering the circuit 110. Further, the power conversion unit 112 may provide an output signal to the LEDs 130, which may represent a load powered by the power conversion unit 112. The input signal may, in some cases, include an input current and an input voltage. Furthermore, the output signal may include an output current and an output voltage. In some cases, the power conversion unit 112 includes a DC-to-DC power converter configured to regulate the output signal provided to the LEDs 130. In some examples, the DC-to-DC power converter includes a switch / inductor unit such as an H-bridge. An H-bridge uses a set of switches, often semiconductor switches, to convert electrical power.In some examples, the switch / inductor unit acts as a buck-boost converter. For example, a buck-boost converter is configured to regulate the output voltage provided to the LEDs 130 using at least two operating modes, including a buck mode and a boost mode. The power converter unit 112 may control semiconductor switches of the buck-boost converter to alternate the mode of the buck-boost converter (e.g., change the operating mode of the buck-boost converter from buck mode to boost mode and vice versa). In . Fig. 1, the semiconductor switches of power converter unit 112 may include transistors, diodes, or other semiconductor elements. In buck mode, the buck-boost converter of power converter unit 112 may decrease the voltage from the input of power converter unit 112 to the output of power converter unit 112 and increase the current from the input of power converter unit 112 to the output of power converter unit 112. In boost mode, the buck-boost converter of power converter unit 112 may increase the voltage from the input of power converter unit 112 to the output of power converter unit 112 and decrease the current from the input of power converter unit 112 to the output of power converter unit 112.

[0013] The setpoint unit 114 may be configured to output a setpoint signal to the power converter unit 112. In some examples, the power converter unit 112 is configured to regulate the output current delivered to the LEDs 130 so that it is proportional to a setpoint parameter value associated with the setpoint signal. In other words, the setpoint unit 114 may control the output current delivered by the power converter unit 112 to the LEDs 130. For example, the setpoint signal may include a setpoint current value, a setpoint voltage value, a setpoint signal frequency, a setpoint signal duty cycle, or any combination thereof. In some examples where the setpoint signal includes a setpoint signal voltage value, the setpoint signal voltage value may be in a range of 5 volts (V) to 10 V. As such, the range of setpoint voltage values (e.g.,5 V to 10 V) correspond to a possible range of output currents delivered by the power converter unit 112 to the LEDs 130. For example, the possible range of output current values may be from 0 amperes (A) to 3 A. In this way, if the setpoint voltage value is 7.5 V (e.g., in the middle of the range of setpoint voltage values), the power converter unit 112 will deliver an output current of 1.5 A (e.g., in the middle of the range of output current values). A relationship between the setpoint signal and the output current may, in some cases, be a linear relationship.

[0014] During transient phases of circuit 110, such as changes in the setpoint signal, changes in the input signal, changes in the output signal, or any combination thereof, an output signal overshoot may occur in the output signal provided by power conversion unit 112 to LEDs 130. For example, if the setpoint signal changes such that the output current drops from 1.5 to 0.3 A, the output current may initially drop below 0.3 A, then rapidly spike (e.g., overshoot) above 0.3 A before settling at 0.3 A. Additionally, in some examples, if the output signal changes such that LEDs 130 draw a greater amount of output voltage from power conversion unit 112 while maintaining a constant output current for an extended period, a short-term output current overshoot may occur during the transient phase, corresponding to the increase in the output voltage provided by power conversion unit 112 to LEDs 130.An output current overshoot may, in some examples, cause damage to components of circuit 110 and LEDs 130. Furthermore, in some examples, an output current overshoot may result in inaccuracies in the regulation of the output signal provided by power conversion unit 112. Therefore, it may be beneficial to reduce an amount of output current overshoot caused by a change in the input signal, a change in the output signal, a change in the setpoint signal, or any combination thereof.

[0015] The correction unit 116 may be configured to reduce an amount of output current overshoot caused during transient phases of the circuit 110. For example, the correction unit 116 may be configured to receive an input parameter value, wherein the input parameter value is proportional to the input signal supplied from the energy source 120 to the power conversion unit 112. For example, the input parameter value may be proportional to any one or more of an input current magnitude, an input voltage magnitude, or a frequency of the input signal. The correction unit 116 may receive an output parameter value, wherein the output parameter value is proportional to the output voltage. For example, the output parameter value may be proportional to one or more of an output current magnitude, an output voltage magnitude, or a frequency of the output signal.Additionally, the correction unit 116 may receive a setpoint parameter value, wherein the setpoint parameter value is proportional to the setpoint signal output by the setpoint unit 114. For example, the setpoint parameter value may be proportional to any one or more of a setpoint current magnitude, a setpoint voltage magnitude, a frequency of the setpoint signal, or a duty cycle of the setpoint signal.

[0016] The correction unit 116 may output a correction signal to the power converter unit 112 based on the input parameter value, the output parameter value, and the setpoint parameter value. In some cases, the correction signal may cause the power converter unit 112 to reduce an amount of output current overshoot that occurs due to transient phases of the circuit 110. In some examples, the correction unit 116 may determine a gain of the power converter unit 112 based on the input parameter value and the output parameter value. For example, a ratio of the output voltage to the input voltage represents a voltage gain of the power converter unit 112. In some cases, the correction unit 116 may output the correction signal based on the voltage gain of the power converter unit 112.Additionally, in some examples, the correction unit 116 may determine a difference between the setpoint parameter value and a maximum setpoint parameter value. The correction unit 116 may output the correction signal based on the difference between the setpoint parameter value and a maximum setpoint parameter value.

[0017] The power source 120 may represent one or more batteries configured to provide power (e.g., the input signal) to the circuit 110. The power source 120 may, for example, comprise a plurality of cells arranged in series with one another. In some examples, the plurality of cells comprise a plurality of lithium-ion cells. In other examples, the plurality of cells comprise lead cells, nickel-metal hydride cells, or other materials. In some examples, a maximum voltage output of the power source 120 is in a range of 10 V to 14 V. In one example, a maximum voltage output of the power source 120 is 12 V. However, the maximum voltage output of the power source 120 may be a different value or range of values.

[0018] The LEDs 130 may comprise one or more strings of LEDs. The LEDs 130 may comprise any solid-state light source. In some examples, an LED may comprise a pn junction configured to emit light when activated. In some examples, the LEDs 130 may be included in a headlight assembly for automotive applications. For example, the LEDs 130 may comprise a matrix, a string, or more than one string of light-emitting diodes to illuminate a road ahead of a vehicle. As used herein, a vehicle may refer to motorcycles, trucks, boats, golf carts, snowmobiles, heavy equipment, or any type of vehicle that utilizes directional lighting. In some examples, the LEDs 130 include a first string of LEDs that includes a set of high-beam LEDs and a set of low-beam LEDs.In some cases, system 100 may toggle between activating the set of low beam LEDs, activating the set of high beam LEDs, activating both the set of low beam LEDs and the set of high beam LEDs, and deactivating both the set of low beam LEDs and the set of high beam LEDs. Additionally, LEDs 130 may include a second string of LEDs representing a set of base LEDs. For example, if both the set of low beam LEDs and the set of high beam LEDs are deactivated, circuit 110 may provide the output signal to the second string of LEDs, activating the set of base LEDs. The second string of LEDs may, in some cases, emit a lesser amount of light than the first string of LEDs and draw a lesser amount of current from circuit 110 than the first string of LEDs.

[0019] Fig. 2 shows a circuit diagram of an exemplary system 200 including circuitry 210 for receiving an input signal from power source 220 and providing an output signal to one or more strings of LEDs 230 in accordance with one or more techniques of the present disclosure. As shown in Fig. 2, the system 200 includes the circuit 210, the energy source 220, and the LEDs 230. The circuit 210 includes the power converter unit 212, the setpoint unit 214, and the correction unit 216. The power converter unit 212 includes the first switching element 242, the first diode 244, the second switching element 246, the second diode 248, the inductor 250, the first current sensor 252, the second current sensor 262, the node 270, the amplifier 282, the amplifier 284, the amplifier 286, and the offset unit 288. The first current sensor 252 includes the first current sense resistor 254 and the first current sense amplifier 256. The second current sensor 262 includes the second current sense resistor 264 and the second current sense amplifier 266. The circuit 210 may be an example of the circuit 110 of Fig. 1. The power converter unit 212 may be an example of the power converter unit 112 of Fig. 1. The setpoint unit 214 may be an example of the setpoint unit 114 of Fig. 1. The correction unit 216 may be an example of the correction unit 116 of Fig. 1. The energy source 220 may be an example of the energy source 120 of Fig. 1. The LEDs 230 may be an example of the LEDs 130 of Fig. 1.

[0020] The power converter unit 212 may include a switch / inductor unit that acts as a buck-boost converter. The H-bridge may be represented by the first switching element 242, the first diode 244, the second switching element 246, the second diode 248, and the inductor 250. The first switching element 242 and second switching element 246 (collectively referred to as "switching elements" 242, 246) may, in some cases, be power switches, such as, but not limited to, any type of field-effect transistor (FET), including any combination of metal-oxide-silicon field-effect transistors (MOSFETS), bipolar junction transistors (BJTs), insulated-gate bipolar transistors (IGBTs), high-junction field-effect transistors (JFETs), high-speed transistors (HEMTs), or other elements that use voltage for control.Additionally, switching elements 242, 246 may include n-type transistors, p-type transistors, and power transistors, or any combination thereof. In some examples, switching elements 242, 246 include vertical transistors, lateral transistors, and / or horizontal transistors. In some examples, switching elements 242, 246 include other analog devices such as diodes and / or thyristors. In some examples, switching elements 242, 246 may act as switches and / or analog devices.

[0021] In some examples, the switching elements 242, 246 each include three terminals: two load terminals and a control terminal. For MOSFET switches, the switching elements 242, 246 may each include a drain terminal, a source terminal, and at least one gate terminal, where the control terminal is a gate terminal. For BJT switches, the control terminal may be a base terminal. Current may flow between the two load terminals of each of the switching elements 242, 246 based on the voltage at the respective control terminal. Therefore, electrical current may flow through the switching elements 242, 246 based on control signals applied to the respective control terminals of the switching elements 242, 246. In one example, if a voltage applied to the control terminals of the switching elements 242, 246 is greater than or equal to a voltage threshold, the switching elements 242, 246 may be activated, allowing the switching elements 242, 246 to conduct electricity.Furthermore, the switching elements 242, 246 may be deactivated when the voltage applied to the respective control terminals of the switching elements 242, 246 is below the threshold voltage, thereby preventing the switching elements 242, 246 from conducting electricity. The power converter unit 112 may be configured to control the switching elements 242, 246 independently of one another, such that one, both, or neither of the switching elements 242, 246 may be activated at a time.

[0022] The switching elements 242, 246 may comprise various material combinations such as silicon, silicon carbide, gallium nitride, or any other combination of one or more semiconductor materials. In some examples, silicon carbide switches may be subject to lower switching power losses. Improvements in magnetics and faster switching, such as with gallium nitride switches, may enable the switching elements 242, 246 to draw short bursts of current from the power source 220. These higher-frequency switching elements may require control signals (e.g., voltage signals delivered by the power converter unit 212 to respective control terminals of the switching elements 242, 246) to be sent with more precise timing compared to lower-frequency switching elements.

[0023] In Fig. 2, the first diode 244 and the second diode 248 (collectively referred to as "diodes 244, 248") represent semiconductor devices. In the field of circuit electronics, diodes include semiconductor devices that allow current to flow across the diode in a first direction (e.g., "forward direction") and prevent current from flowing across the diode in a second direction (e.g., "reverse direction"). A diode may include an anode and a cathode, and current may be allowed to pass through the diode in the forward direction from the anode to the cathode. However, current may be prevented from passing through the diode in the reverse direction from the cathode to the anode. For example, a cathode of the first diode 244 may be electrically connected to the first switching element 242 and the inductor 250, and an anode of the first diode 244 may be electrically connected to ground.In addition, a cathode of the second diode 248 may be electrically connected to the second current sensor 262, and an anode of the second diode 248 may be electrically connected to the first current sensor 252 and the second switching element 246.

[0024] The inductance 250 is a component of the power converter unit 212 according to the Fig. 2. Inductors are electrical circuit components that resist a change in the amount of current passing through the inductor. In some examples, inductors comprise an electrically conductive wire wound into a coil. When current passes through the coil, a magnetic field is created in the coil, and the magnetic field induces a voltage across the inductor. An inductor defines an inductive reactance, and the inductive reactance is the ratio of the voltage across the inductor to the rate of change of current passing through the inductor. Therefore, when the inductor 250 is charged with a magnetic field and placed in series with the power source 220 and the LEDs 230, the voltage across the inductor 250 is designed to increase the magnitude of the output voltage delivered to the load LEDs 230.The inductor 250 is also configured to step down the magnitude of the output voltage delivered to the LEDs 230 when the first switching element 242 is deactivated, thereby isolating the LEDs 230 from the power source 220 and reducing the output voltage delivered to the LEDs 230 to the voltage across the inductor 250 charged with a magnetic field.

[0025] The switch / inductor unit (e.g., the first switching element 242, the first diode 244, the second switching element 246, the second diode 248, and the inductor 250) is configured to regulate the output voltage supplied to the LEDs 230 using at least two operating modes, including a buck mode and a boost mode. The power converter unit 212 may control the first switching element 242 and the second switching element 246 to alternate the mode of the switch / inductor unit (e.g., change the operating mode of the switch / inductor unit from buck mode to boost mode and vice versa). Fig. 1, the first switching element 242 and the second switching element 246 may comprise transistors, diodes, or other semiconductor elements. In buck mode, the switch / inductor unit may decrease the voltage from the input of the power converter unit 212 to the output of the power converter unit 212 and increase the current from the input of the power converter unit 212 to the output of the power converter unit 212. In boost mode, the switch / inductor unit may increase the voltage from the input of the power converter unit 212 to the output of the power converter unit 212 and decrease the current from the input of the power converter unit 212 to the output of the power converter unit 212.

[0026] In some examples, while the switch / inductor unit is in buck mode, the second switching element 246 is deactivated and the first switching element 242 alternates between being activated and deactivated. When the first switching element 242 is activated, an electrical current passes through the first switching element 242, the inductor 250, and the second diode 248, charging the inductor 250. When the first switching element 242 is deactivated, the power converter unit 212 is disconnected from the power source 220, and the inductor 250 discharges, causing an electrical current to flow from ground through the first diode 244, the inductor 250, and the second diode 248. When the inductor 250 discharges, the power converter unit 212 may lower or buck an output voltage supplied by the power converter unit 212 to the LEDs 230.In addition, the power converter unit 212 may increase an output current supplied from the power converter unit 212 to the LEDs 230.

[0027] In some examples, while the switch / inductor unit is in boost mode, the first switching element 242 is on and the second switching element 246 alternates between being enabled and disabled. When the second switching element 246 is enabled, an electrical current flows from the power source 220 through the first switching element 242, the inductor 250, and the second switching element 246, thereby charging the inductor 250. When the second switching element 246 is disabled, the inductor 250 discharges and an electrical current flows from the power source 220 through the first switching element 242, the inductor 250, and the second diode 248 to the LEDs 230, thereby raising or boosting an output voltage provided to the LEDs 230. In addition, in boost mode, the power converter unit 121 can decrease a current supplied to the LEDs 230.

[0028] To regulate one or more aspects of the output signal delivered to the LEDs 230 (e.g., the output current and the output voltage), it may be useful for the power conversion unit 212 to receive a parameter indicative of the current through the inductor 250 and a parameter indicative of an output current delivered to the LEDs 230. By receiving such parameters, the power conversion unit 212 can more precisely regulate the one or more aspects of the output signal.

[0029] The first current sensor 252 may detect a current through the inductor 250, and the second current sensor 262 may detect an output current delivered by the power converter unit 212 to the LEDs 230. In the Fig. 2, the first current sensor 252 includes the first current sense resistor 254 and the first current sense amplifier 256. The second current sensor 264 includes the second current sense resistor 264 and the second current sense amplifier 266. Ohm's law states that a voltage across a resistor is equal to the resistance of the resistor times a magnitude of current through the resistor (V = I*R). Therefore, a current through the first current sense resistor 254 is equal to a voltage across the first current sense resistor 254 divided by a resistance (in ohms (Ω)) of the first current sense resistor 254. The first current sense amplifier 256 may, in some cases, output a first current sense signal correlated with a current through the first current sense resistor 254. Therefore, a first current sense amplifier 256 may output the first current sense signal correlated with a current through the inductor 250.Additionally, a current across the second current sense resistor 264 is equal to a voltage across the second current sense resistor 264 divided by a resistance (in ohms (Ω)) of the second current sense resistor 264. The second current sense amplifier 266 may, in some cases, output a second current sense signal correlated with a current across the second current sense resistor 264. Therefore, a second current sense amplifier 266 may output the second current sense signal correlated with an output current provided to the LEDs 230.

[0030] In some examples, node 270 receives the first current sense signal and receives a comparison signal, the comparison signal being correlated with a difference between the setpoint signal output by setpoint unit 214 and the second current sense signal output by second current sensor 262. For example, amplifier 282 may generate the comparison signal correlated with the difference between the setpoint signal and the second current sense signal, and amplifier 282 may output the comparison signal to node 270. Additionally, node 270 receives a correction signal from correction unit 216 and outputs a correction signal to any one or more of amplifier 284 and amplifier 286.In some cases, the control signal drives the activation and deactivation of the switching elements 242, 246 so that the power converter unit 212 can precisely regulate one or more aspects of the output signal provided to the LEDs 130. In some examples, the control signal represents a subtraction of the correction signal and the first current sense signal from the comparison signal.

[0031] In some examples where the switch / inductor unit of the power converter unit 212 operates in boost mode, the comparison signal (V comp ) by the following equation: Vcomp=Voffset+Vslope⋅D+Vpeak+Vcorrection

[0032] In equation 1, V comp represent the comparison signal, Voffset can represent an offset signal given by the offset unit 288, V slopemay represent an input 290 to the amplifier 284, D may represent a duty cycle of the second switching element 246, V peak may represent the first current detection signal output of the first current sensor 252 and V correction may represent the correction signal output by the correction unit 216.

[0033] When the switch / inductor unit of the power converter unit 212 operates in buck mode, a linear relationship may exist between a voltage gain of the power converter unit 212 (e.g., a ratio of the output voltage of the power converter unit 212 to the input voltage of the power converter unit 212) and the comparison signal received from node 270. Furthermore, when the switch / inductor unit of the power converter unit 212 operates in boost mode, a nonlinear relationship may exist between the voltage gain of the power converter unit 212 and the comparison signal received from node 270. In some cases, the nonlinear relationship between the voltage gain of the power converter unit 212 and the comparison signal received from node 270 may depend on the output current supplied by the power converter unit 212 to the LEDs 230.

[0034] For example, when the switch / inductor unit of the power converter unit 212 operates in buck mode, the first current sense signal V peak and the comparison signal V comp by the following two equations: Vpeak=IL,peak⋅Rext Vcomp=Voffset+Vslope⋅D+IL,peak⋅Rext+Vcorrection

[0035] In equations 2 and 3, I L,peak for a peak current across the inductance 250. Therefore, I L,peak for a peak current through the first current measuring resistor 254 of the first current sensor 252, which measures the current through the inductance 250. In addition, R ext for the resistance value of the first current measuring resistor 254.

[0036] In the example of Fig. 2, a current ripple factor associated with the current through the inductor 250 can be less than 30%. Therefore, the peak current through the inductor 250 (I L,peak), an average current across the inductor 250 and a valley current across the inductor 250 are substantially equal. Therefore, in examples where the switch / inductor unit of the power converter unit 212 operates in buck mode and in examples where the switch / inductor unit of the power converter unit 212 operates in boost mode, the peak current across the inductor 250 may in some cases be substituted for (e.g., substituted for) the average current across the inductor 250 and / or the valley current across the inductor. When the switch / inductor unit of the power converter unit 212 operates in boost mode, the first current sense signal V peak and the comparison signal V comp by the following two equations: Vpeak=Iout⋅Rext⋅VoVi Vcomp=Voffset+Vslope⋅D+Iout⋅Rext⋅VoVi+Vcorrection

[0037] In equations 4 and 5, I out for the output current supplied by the power converter unit 212 to the LEDs 230, R ext stands for the resistance value of the first current measuring resistor 254, V o represents the output voltage supplied by the power converter unit 212 to the LEDs 230, and V i represents the input voltage received by the power converter unit 212 from the energy source 220. As can be seen from equations 4 and 5, while the switch / inductor unit of the power converter unit 212 is operating in boost mode, the comparison signal (V comp ) from a function of voltage gain (VoVi) the power converter unit 212 and the output current (I out ) of the power converter unit 212. Therefore, while the boost mode is activated, V comp and (VoVi) a nonlinear relationship, where the nonlinear relationship of I out For example, for any value of I out a separate curve for V comp opposite VoVi exist.

[0038] In this way, if the setpoint unit 214 decreases the setpoint signal such that the output current decreases from a first output current value to a second output current value, the output voltage of the power converter unit 212 may increase while the comparison signal received from node 270 decreases. Such a decrease in the comparison signal and increase in the output voltage may cause the first output current to decrease from the first output current value to below the second output current value, then overshoot the second output current value before settling at the second output current value.Additionally, if the output signal changes such that the LEDs 230 draw a larger amount of output voltage from the power conversion unit 212 while maintaining a constant output current for an extended period, a short-term output current overshoot may occur during the transient phase, corresponding to the increase in the output voltage supplied by the power conversion unit 212 to the LEDs 230. An output current overshoot may, in some examples, cause damage to components of the circuit 210 and the LEDs 230. Furthermore, in some examples, an output current overshoot may result in inaccuracies in the regulation of the output signal supplied by the power conversion unit 212. Therefore, it may be beneficial to reduce an amount of output current overshoot caused by a change in the input signal, a change in the output signal, a change in the setpoint signal, or any combination thereof.

[0039] The correction unit 216 may reduce an amount of output current overshoot that occurs due to changes in the input signal, changes in the output signal, changes in the setpoint signal, or any combination thereof. For example, the correction unit 216 may be configured to receive an input parameter value, wherein the input parameter value is proportional to the input signal provided by the energy source 220 to the power conversion unit 212. For example, the input parameter value may be proportional to any one or more of an input current magnitude, an input voltage magnitude, or a frequency of the input signal. The correction unit 216 may receive an output parameter value, wherein the output parameter value is proportional to the output voltage provided by the power conversion unit 212 to the LEDs 230.For example, the output parameter value may be proportional to one or more of an output current magnitude, an output voltage magnitude, or a frequency of the output signal. Furthermore, the correction unit 216 may receive a setpoint parameter value, wherein the setpoint parameter value is proportional to the setpoint signal output by the setpoint unit 214. For example, the setpoint parameter value may be proportional to any one or more of a setpoint current magnitude, a setpoint voltage magnitude, a frequency of the setpoint signal, or a duty cycle of the setpoint signal.

[0040] The correction unit 216 may provide a correction signal to node 270 of the power converter unit 212 based on the input parameter value, the output parameter value, and the setpoint parameter value. In some examples, while the switch / inductor unit of the power converter unit 212 is operating in boost mode, the correction signal (V correction) by: Vcorrection=Rext⋅VoVi(Iout,max−Iout)

[0041] In equation 6, V o represent the output parameter value received from the correction unit 216, V i may represent the input parameter value received from the correction unit 216, and I out can represent the setpoint parameter value received from the correction unit 216. I out,max - I out may represent a difference between a maximum setpoint parameter value and the setpoint parameter value received from the correction unit 216. When Equation 6 is combined with Equation 5, the comparison signal (V comp ) by: Vcomp=Voffset+Vslope⋅D+Rext⋅VoVi⋅Vout,max

[0042] In this way, the comparison signal can be used by the voltage amplification (VoVi) of the power converter unit 212 and the maximum output current / maximum setpoint parameter value (I out,max ) and not on the current setpoint parameter value (I out ) depend on.

[0043] Fig. 3 shows a circuit diagram of another exemplary system 300 that includes circuitry 310 for receiving an input signal from power source 320 and providing an output signal to one or more strings of LEDs 330 in accordance with one or more techniques of the present disclosure. As shown in Fig. 3, the system 300 includes the circuit 310, the energy source 320, and the LEDs 330. The circuit 310 includes the power converter unit 312, the setpoint unit 314, and the correction unit 316. The power converter unit 312 includes the first switching element 342, the first diode 344, the second switching element 346, the second diode 348, the inductor 350, the first current sensor 352, the second current sensor 362, the node 370, the amplifier 382, the amplifier 384, the amplifier 386, and the offset unit 388. The first current sensor 352 includes the first current sense resistor 354 and the first current sense amplifier 356. The second current sensor 362 includes the second current sense resistor 364 and the second current sense amplifier 366. The node 370 includes a scaling unit 372, a first subnode 374 and a second subnode 376. The circuit 310 may be an example of the circuit 110 of Fig. 1. The power converter unit 312 may be an example of the power converter unit 312 of Fig. 1. The setpoint unit 314 may be an example of the setpoint unit 114 of Fig. 1. The correction unit 316 may be an example of the correction unit 116 of Fig. 1. The energy source 320 may be an example of the energy source 120 of Fig. 1. The LEDs 330 may be an example of the LEDs 130 of Fig. 1.

[0044] The system 300 can be substantially similar to the system 200 of Fig. 2, except that node 370 of Fig. 3 comprises a scaling unit 372, a first sub-node 374 and a second sub-node 376, all of which are Fig. 2 are not present. The scaling unit 372 can influence the control signal generated by the node 370. For example, the first sub-node 374 can control the comparison signal (V comp) from the amplifier 382, wherein the comparison signal represents a difference between the setpoint parameter value output by the setpoint unit 314 and the second current detection signal output by the second current sensor 362. In addition, the first subnode 374 can output the correction signal (V correction ) from the correction unit 316. The second subnode 376 may receive the first current detection signal (V peak ) and output a control signal to the amplifier 84. The scaling unit 372 can apply a scaling factor to the first current detection signal, the offset signal (V offset ) and the input 390 (V slope ) into the amplifier 384. Therefore, the comparison signal can be given by: Vcomp=1Kcomp⋅(Voffset+Vslope⋅D+Vpeak)+Vcorrection

[0045] In equation 8, K compfor the scaling factor applied by the scaling unit 372. The correction signal can be given by: Vcorrection,ideal=1Kcomp⋅VoVi⋅Rext⋅(Iout,max−Iout) where Iout,max=Vref,maxACS⋅1Rsense and Iout=VrefACS⋅1Rsense

[0046] In equations 9-11, R sense represents the resistance value of the second current measuring resistor 364 and A CS can represent a gain of the second current sense amplifier 366. Combining equations 10 and 11 with equation 9, the correction signal can be given by: Vcorrection,ideal=1Kcomp⋅VoVi⋅Rext⋅(Vref,max−VrefACS⋅Rsense)

[0047] In this way, in the example of Fig. 3 the correction signal may be proportional to the voltage gain of the power converter unit 312, and the correction signal may be proportional to a difference between the setpoint parameter value and a maximum setpoint parameter value.

[0048] Fig. 4A illustrates a graph depicting an output voltage graph 410, a comparison signal graph 420, and an output current graph 430 over a period of time in which the output current is reduced from a first output current value to a second output current value, in accordance with one or more techniques of the present disclosure. The output voltage graph 410 includes a first output voltage curve 412 and a second output voltage curve 414. The comparison signal graph 420 includes a first comparison signal curve 422 and a second comparison signal curve 424. The output current graph 430 includes a first output current curve 432 and a second output current curve 434.

[0049] The output voltage diagram 410 represents an output voltage of the power converter unit 112 that is delivered to the LEDs 130 over a period of time. For example, because the power converter unit 112 includes a switch / inductor unit that acts as a buck-boost converter, the power converter unit 112 can increase (e.g., boost) or decrease (e.g., buck) the output voltage from the input voltage delivered to the power converter unit 112 by the energy source 120. By controlling one or more switching elements (e.g., the switching elements 242, 246 of Fig. 2) the switch / inductor unit, the power converter unit 112 can switch the switch / inductor unit between a buck mode and a boost mode. Furthermore, by controlling the one or more switching elements (e.g., regulating a duty cycle of one or more of the switching elements 242, 246), the power converter unit 112 can control an amount by which the power converter unit 112 increases / decreases the output voltage, thereby controlling the output voltage over the period of time. Furthermore, the output voltage of the power converter unit can be influenced by devices and components other than the power converter unit 112 (e.g., the setpoint unit 114, the correction unit 116, the energy source 120, and the LEDs 130).

[0050] The setpoint unit 114 may provide a setpoint signal to the power converter unit 112. The power converter unit 112 may regulate an output current delivered to the LEDs 130 to be proportional to a setpoint parameter value associated with the setpoint signal. The power converter unit 112 may determine a comparison signal based on a difference between the setpoint signal and the output current. To regulate the output current, in some cases, the power converter unit 112 may regulate the output voltage delivered to the LEDs 130. In some cases, to deliver an appropriate amount of current to the LEDs 130, the power converter unit 112 may regulate the output current based on which of the LEDs 130 are activated at a given time. For example, the LEDs 130 may include a first string of LEDs having a set of high beam LEDs and a set of low beam LEDs.Additionally, the LEDs 130 may include a second string of LEDs comprising a set of base LEDs. The set of base LEDs may, in some cases, be activated while the set of high beam LEDs and the set of low beam LEDs are deactivated, thereby allowing the vehicle including the LEDs 130 to be more easily seen when the high beams and low beams are off, such as during the day. As such, the LEDs 130 may include a load supplied with power by a power conversion unit 112, and the load may be transferred between the first set of LEDs and the second set of LEDs. For example, if the high beams, the low beams, or both the high beams and low beams are activated, the load may be transferred from the second string of LEDs to the first string of LEDs.Additionally, if both the high beam and low beam are deactivated, the load may be transferred from the first string of LEDs to the second string of LEDs. The second string of LEDs may, in some cases, require a lower amount of output current from the power converter unit 112 than the first string of LEDs.

[0051] When the load of LEDs 130 is switched from the first string of LEDs to the second string of LEDs, in some cases the output voltage may increase and the comparison signal may decrease. For example, as seen in the output current graph 430, the output current may decrease from 1.5 A to 0.3 A over a period of time. During the period, the output voltage may increase, as seen in the output voltage graph 410, and the comparison signal may decrease, as seen in the first comparison signal curve 422 of the comparison signal graph 420. Such a decrease in the comparison signal graph 420 may cause the output current graph 430 to decrease from 1.5 A to below a final quiescent current of 0.3 A. The output current graph 430 may then increase above the final quiescent current of 0.3 A before settling at the final quiescent current of 0.3 A, as seen in the first output current curve 432.Therefore, the first output current waveform 432 represents an output current overshoot that occurs due to the switching of the load of the LEDs 130 from the first string of LEDs to the second string of LEDs.

[0052] The correction unit 116 can, in some cases, reduce the amount of output current overshoot that occurs due to the transfer of the load of the LEDs 130 between the first string of LEDs and the second string of LEDs. For example, the correction unit 116 outputs a correction signal to the power converter unit 112 that prevents the comparison signal from decreasing as the output voltage increases. When the correction unit 116 outputs the correction signal, the comparison signal graph 420 shifts from the first comparison signal curve 422 to the second comparison signal curve 424. Additionally, when the correction unit 116 outputs the correction signal, the output signal graph 410 shifts from the first output voltage curve 412 to the second output voltage curve 414.In this way, the correction unit 116 further reduces output voltage overshoot, as seen in the shift from the first output voltage curve 412 to the second output voltage curve 414, and the correction unit 116 prevents the comparison signal from decreasing when the output voltage increases. Therefore, when the correction unit 116 outputs the correction signal, the output current overshoot is reduced, and the output current diagram shifts from the first output current curve 432 to the second output current curve 434.

[0053] Fig. 4B shows a graph of a first gain / comparison signal diagram 482 and a second gain / comparison signal diagram 484 according to one or more techniques of the present disclosure. Fig. 4B illustrates a first gain / compare signal point 486 and a second gain / compare signal plot 488. The circuit 210 may switch a load of the LEDs 230 from a first string of LEDs to a second string of LEDs. While the power converter unit 212 is operating in boost mode, a relationship between the gain of the power converter unit 212 and the comparison signal provided by the amplifier 282 to the node 270 may be non-linear. The non-linear relationship may depend on the output current provided by the power converter unit 212 to the LEDs 230. For example, if the output current is 1.5 A (e.g., when the load of the LEDs 230 is the first string of LEDs), the relationship between the gain and the comparison signal may be indicated by the first gain / compare signal plot 482. Furthermore, if the output current is 0.3 A (e.g.,When the load of LEDs 230 is the second string of LEDs, the relationship between the gain and the comparison signal may be specified by the second gain / comparison signal diagram 484. Therefore, when the circuit 210 switches the load of LEDs 230 from the first string of LEDs to the second string of LEDs, the relationship between the gain and the comparison signal may shift from the first gain / comparison signal diagram 482 to the second gain / comparison signal diagram 484.

[0054] Additionally, when the circuit 210 switches the load of the LEDs 230 from the first string of LEDs to the second string of LEDs, an output voltage of the power converter unit 212 may increase. Therefore, the voltage gain of the power converter unit 212 may also increase. Due to the change in the relationship between the gain and the comparison signal from the first gain / comparison signal diagram 482 to the second gain / comparison signal diagram 484, the increase in the output voltage may correspond to a decrease in the comparison signal (e.g., the "Positive V out Jump” the “Negative V comp jump”). The decrease in the comparison signal can cause an overshoot in the output current, as in Fig. 4A. The correction unit 216 may in some cases be configured to output a correction signal to the node 270, wherein the correction signal eliminates the decrease in the comparison signal, thereby reducing the overshoot of the output current, as shown in Fig. 4A shown.

[0055] Fig. 5A illustrates a graph depicting an output voltage graph 540, a comparison signal graph 550, and an output current graph 560 over a period of time in which the output voltage is increased from a first output voltage to a second output voltage, in accordance with one or more techniques of the present disclosure. The output voltage graph 540 includes a first output voltage curve 542 and a second output voltage curve 544. The comparison signal graph 550 includes a first comparison signal curve 552 and a second comparison signal curve 554. The output current graph 560 includes a first output current curve 562 and a second output current curve 564.

[0056] The correction unit 116 may reduce an amount of output current overshoot that occurs due to an increase in the output voltage when the output current is constant over a period of time (e.g., the output current is the same at a time before the output voltage increase and at a time after the output current settles following the output voltage increase). For example, in response to the output voltage increase from a first output voltage value to a second output voltage value, the correction unit 116 may provide a correction signal to the power conversion unit 112 that causes the comparison signal diagram 550 to shift from the first comparison signal curve 552 to the second comparison signal curve 554.Additionally, the correction signal causes the output voltage graph 540 to shift from the first output voltage curve 542 to the second output voltage curve 544 and causes the output current graph 560 to shift from the first output current curve 562 to the second output current curve 564. Therefore, the correction unit 116 reduces an amount of output current overshoot that occurs due to an increase in the output voltage from the first output voltage value to the second output voltage value.

[0057] The output voltage may increase in some examples if the LEDs 130 comprise an LED string having a first group of LEDs and a second group of LEDs. If the first group of LEDs is enabled and the second group of LEDs is disabled, the LEDs 130 may require the first output voltage value of the power conversion unit 112. If both the first group of LEDs and the second group of LEDs are enabled, the LEDs 130 may require the second output voltage value of the power conversion unit 112. Therefore, by enabling the second group of LEDs, the output voltage graph 540 may increase from the first output voltage value to the second output voltage value.

[0058] Fig. 5B shows a graph of a first gain / comparison signal diagram 582 and a second gain / comparison signal diagram 584 according to one or more techniques of the present disclosure. Fig. 5B illustrates a first gain / compare signal point 586 and a second gain / compare signal plot 588. A load of LEDs 230 may, in some examples, comprise a single string of LEDs, where the single string of LEDs comprises a first set of LEDs and a second set of LEDs. In some examples, circuitry 210 may activate only the first set of LEDs. Additionally, in some examples, circuitry 210 may activate both the first set of LEDs and the second set of LEDs.When the circuit 210 switches from activating only the first set of LEDs to activating both the first set of LEDs and the second set of LEDs, the output voltage of the power converter unit 212 may increase while the output current of the power converter unit 212 remains constant from a time before activating both the first set of LEDs and the second set of LEDs to a time after the output current settles after activating both the first set of LEDs and the second set of LEDs.

[0059] After activating both the first set of LEDs and the second set of LEDs, the output voltage of the power converter unit 212 may increase (e.g., “positive Vout jump” as shown in Fig. 5B). Since the relationship between the gain of the power converter unit 212 and the comparison signal received by node 270 from amplifier 282 is non-linear, as can be seen from the second gain / comparison signal diagram 584, an increase in the output voltage may correspond to a relatively small increase in the comparison signal. Such a relatively small increase in the comparison signal may result in the Fig. 5A. The correction unit 216 may in some cases be configured to output a correction signal to the node 270, wherein the correction signal increases the relatively small increase in the comparison signal, thereby reducing the overshoot of the output current, as shown in Fig. 5A. Since the output current is Fig. 5B from a time before both the first set of LEDs and the second set of LEDs are activated to a time after the output current settles down after both the first set of LEDs and the second set of LEDs are activated, remains constant (e.g., 0.3 A), the relationship between the gain and the comparison signal may not deviate from the second gain / comparison signal diagram 584.

[0060] Fig. 6 shows a block diagram of an example system 600 that includes a first LED string 618 and a second LED string 620 and an LED driver 601 according to one or more techniques of the present disclosure. The LED driver 601 includes a DC-DC converter 602 configured to regulate the current through the first LED string 618 and the second LED string 620. The LED driver 601 may also include a switch controller 604 configured to control the switches 608 and 609 to control the current flow through the first LED string 618 and the second LED string 620. In some examples, the term "LED string" refers to a plurality of LEDs coupled in series. The DC-DC converter 602 may be an example of the switch / inductor unit 112 of Fig. 1. The current sense resistor 606 may be an example of the second current sense resistor 264 of Fig. 2. The LED string 618 and the LED string 620 may be an example of the LEDs 130 of Fig. 1.

[0061] The first LED string 618 and the second LED string 620 may be controlled in a complementary manner by a control switch 608, a control switch 609, and a control switch 610 (collectively referred to as "control switches 608, 609, 610"). The switch controller 604 may control the switch 608 to be in an ON state while the control switch 609 is in an OFF state. Alternatively, the switch controller 604 may control the switch 608 to be in an OFF state while the control switch 609 is in an ON state. In this manner, the switch controller 604 controls the LED string 618 and the second LED string 620 in a complementary manner, ensuring that both LED strings do not receive significant amounts of current at the same time.Switches 608 and 609 can be used to select different strings of LEDs at different times, and in some cases, switches 608 and 609 can be controlled to define duty cycles of the first LED string 618 and the second LED string 620 to more effectively control the power delivered to the different LED strings. Switch 610 can control whether LEDs 622 and LEDs 624 receive power while LED string 618 receives power, or whether LEDs 622 receive power and LEDs 624 do not receive power while LED string 618 receives power. As such, switch controller 604 can control whether, while power is being delivered to LED string 618, both LEDs 622 and 624 are illuminated, or only LEDs 622 is illuminated.

[0062] As examples, switches 608, 609, 610 may each comprise a field-effect transistor (FET), a bipolar transistor (BJT), a gallium nitride (GaN) switch, or possibly a silicon controlled rectifier (SCR). Examples of FETs may include, but are not limited to, a junction field-effect transistor (JFET), a metal-oxide-semiconductor FET (MOSFET), a double-gate MOSFET, an insulated-gate bipolar transistor (IGBT), any other type of FET, or any combination thereof. Examples of MOSFETs may include, but are not limited to, PMOS, NMOS, DMOS, or any other type of MOSFET, or any combination thereof. Examples of BJTs may include, but are not limited to, PNP, NPN, heterojunction, or any other type of BJT, or any combination thereof.

[0063] In order to monitor and detect the current flow through the first LED string 618 and through the second LED string 620, the Fig. 6 includes a current sense resistor 606 and two current sense pins at nodes 612 and 614. The current sense pins at nodes 612 and 614 are electrical contacts for connection to the DC-DC converter 602. The DC-DC converter 602 can monitor the voltage drop from node 612 to node 614. Based on the resistance of the resistor 606 and the voltage drop from node 612 to node 614, the DC-DC converter 602 can determine the current flow through the first LED string 618 and the current flow through the second LED string based on Ohm's law.

[0064] The DC-DC converter 602 may include the switch / inductor unit 112 of the power converter unit of Fig. 1. In this way, the DC-DC converter 602 can act as a buck-boost converter that controls an output signal (e.g., an output current and an output voltage) provided to the first LED string 618 and the second LED string 620. The first LED string 618 and the second LED string 620 can each draw different amounts of current from the DC-DC converter 602. In some cases, in order to sufficiently illuminate the LEDs 622 and LEDs 624, the first LED string 618 receives a current of 1.5 A from the DC-DC converter 602. In some cases, in order to sufficiently illuminate the LEDs of the second LED string 620, the second LED string 620 receives a current of 0.3 A from the DC-DC converter 602. The switch controller 604 can control the switch 608 and the switch 609 such that the DC-DC converter 602 supplies an output current to the second LED string 620 and the DC-DC converter 602 does not supply the output current to the first LED string 618.Since the second LED string 620 may be supplied with a second output current value and the first LED string 618 may be supplied with a first output current value, the DC-DC converter 602 may reduce the output current from the first output current value to the second output current value if the switch controller 604 switches the output current from the first LED string 618 to the second output string 620 using the switch 608 and the switch 609.

[0065] By decreasing the output current from the first output current value to the second output current value, the DC-DC converter 602 can cause an output current overshoot of the second output current value before the output current settles at the second output current value. A correction unit (in Fig. 6 not shown) of the LED driver 601 can output a correction signal that reduces such output current overshoot.

[0066] Fig. 7 is a flowchart illustrating an example process for providing a correction signal to reduce output current overshoot, in accordance with one or more techniques of the present disclosure. Fig. 7 is described for simplicity with reference to the circuit 110, the power source 120 and the LEDs 130 of Fig. 1. The techniques of Fig. 7 may, however, be performed by other components of circuit 110, power source 120 and LEDs 130, or by additional or alternative devices.

[0067] As in the example process of Fig.7, the power converter unit 112 of the circuit 110 is configured to receive an input signal from the power source 120 (702). In some examples, the input signal includes an input voltage, an input current. Furthermore, in some examples, the input signal may define any combination of an input frequency or an input duty cycle. The power converter unit 112 outputs an output signal to the LEDs 130 (704). The LEDs 130 may include one or more strings of LEDs. For example, the LEDs 130 may include a first string of LEDs that includes a set of high beam LEDs and a set of low beam LEDs. Furthermore, the LEDs 130 may include a second string of LEDs that represents a set of base LEDs.For example, if both the set of low beam LEDs and the set of high beam LEDs are deactivated, the circuit 110 may provide the output signal to the second string of LEDs so that the set of base LEDs is activated. The second string of LEDs may, in some cases, emit a smaller amount of light than the first string of LEDs and draw a smaller amount of current from the circuit 110 than the first string of LEDs. In this way, the power converter unit 112 may regulate the output signal provided to the LEDs 130 to provide the correct amount of power depending on which of the one or more strings of LEDs is activated.

[0068] The setpoint unit 114 of the circuit 110 may output a setpoint signal to the power converter unit 112 (706). In some examples, the power converter unit 112 may regulate the output current output to the LEDs 130 to be proportional to a setpoint parameter value associated with the setpoint signal. In this way, the setpoint unit 114 may control the output current output to the LEDs 130. The correction unit 116 of the circuit 110 may receive an input parameter value proportional to the input signal (708). In addition, the correction unit 116 may receive an output parameter value proportional to the output voltage (710) and a setpoint parameter value proportional to the setpoint signal (712). The correction unit 116 outputs a correction signal to the power converter unit 112 (714) based on the input parameter value, the output parameter value, and the setpoint parameter value.By supplying the correction signal to the power converter unit 112, the correction unit 116 can reduce an amount of output signal overshoot that occurs due to a change in the setpoint parameter value, a change in the output signal, or a change in the input signal.

[0069] The following numbered examples illustrate one or more aspects of the disclosure.

[0070] Example 1. A circuit is configured to monitor the current through one or more strings of light-emitting diodes (LEDs), the circuit comprising: a power conversion unit, wherein the power conversion unit is configured to receive an input signal from a power source, and wherein the power conversion unit is configured to provide an output signal to the one or more strings of LEDs, the output signal comprising an output voltage and an output current; a setpoint unit configured to provide a setpoint signal to the power conversion unit, wherein the power conversion unit is configured to regulate the output current to be proportional to a setpoint parameter value associated with the setpoint signal; and a correction unit.The correction unit is configured to: receive an input parameter value, wherein the input parameter value is proportional to the input signal; receive an output parameter value, wherein the output parameter value is proportional to the output voltage; receive a setpoint parameter value, wherein the setpoint parameter value is proportional to the setpoint signal; and, based on the input parameter value, the output parameter value, and the setpoint parameter value, output a correction signal to the power converter unit.

[0071] Example 2. The circuit of Example 1, wherein the circuit is further configured to: transfer the output signal from a first string of the one or more strings of LEDs to a second string of the one or more strings of LEDs, wherein the setpoint unit is configured to: change the setpoint parameter value from a first setpoint parameter value to a second setpoint parameter value based on transferring the output signal, and wherein, to output the correction signal to the power conversion unit, the correction unit is configured to: output the correction signal to the power conversion unit based on a difference between a maximum setpoint parameter value and the second setpoint parameter value to reduce an amount of output current overshoot corresponding to the transfer of the output signal.

[0072] Example 3. The circuit of examples 1-2 or any combination thereof, wherein a ratio of the output parameter value to the input parameter value represents a gain of the power converter unit, and wherein, to output the correction signal, the power converter unit is configured to: output the correction signal to the power converter unit based on the gain of the power converter unit.

[0073] Example 4. The circuit of examples 1-3, or any combination thereof, the circuit further configured to: based on the change in the setpoint parameter value from the first setpoint parameter value to the second setpoint parameter value, change the output current from a first output current correlated with the first setpoint parameter value to a second output current value correlated with the second setpoint parameter value.

[0074] Example 5. The circuit of examples 1-4 or any combination thereof, wherein the first output current value is in a range of 1.3 amperes (A) to 1.7 A, and wherein the second output current value is in a range of 0.1 A to 0.5 A.

[0075] Example 6. The circuit of examples 1-5 or any combination thereof, wherein the circuit is further configured to: change the output voltage from a first output voltage value to a second output voltage value, and wherein, to provide the correction signal to the power conversion unit, the correction unit is configured to: provide the correction signal to the power conversion unit based on a difference between a maximum setpoint parameter value and the setpoint parameter value to reduce an amount of output current overshoot corresponding to the change in output voltage.

[0076] Example 7. The circuit of examples 1-6 or any combination thereof, wherein the input parameter value represents an input voltage value, and wherein a ratio of the second output voltage value to the input voltage value represents a voltage gain of the power converter unit, and wherein, to output the correction signal, the power converter unit is configured to: output the correction signal to the power converter unit based on the voltage gain of the power converter unit.

[0077] Example 8. The circuit of examples 1-7 or any combination thereof, wherein the power conversion unit further comprises an inductor, and wherein the power conversion unit comprises: a first current sensor comprising: a first current sensing resistor; and a first amplifier configured to output a first current sense signal correlated with a current across the inductor and a current across the first current sensing resistor; and a second current sensor comprising: a second current sensing resistor connected in series with the first current sensing resistor;and a second amplifier configured to output a second current sense signal correlated with the output current delivered to the one or more strings of LEDs and a current across the second current sense resistor, wherein, based on the first current sense signal and the second current sense signal, the power converter unit is configured to regulate at least one of the output current and the output voltage.;

[0078] Example 9. The circuit of examples 1-8 or any combination thereof, wherein the power converter unit further comprises a node and a switching element, the node configured to: receive the correction signal; receive the first current sense signal; receive a comparison signal, the comparison signal correlated with a difference between the setpoint signal and the second current sense signal;and output a control signal, wherein the control signal represents a summation of the correction signal, the first current detection signal, and the comparison signal, and wherein the control signal controls a switching cycle of the switching element to regulate the at least one of the output current and the output voltage, wherein the switching element is configured to activate and deactivate according to the switching cycle and based on the control signal, wherein the switching cycle defines a duty cycle that represents a ratio of a time period for which the switching element is activated to a time period for which the switching element is deactivated.;

[0079] Example 10. The circuit of examples 1-9 or any combination thereof, wherein, while the switching element is enabled, the power conversion unit is configured to: charge the inductor, and wherein, while the switching element is disabled, the power conversion unit is configured to: discharge the inductor to boost the output voltage value of the one or more strings of LEDs.

[0080] Example 11. The circuit of examples 1-10 or any combination thereof, wherein the switching element is a first switching element, wherein the power conversion unit further comprises a second switching element, wherein while the second switching element is enabled and the first switching element is disabled, the power conversion unit is configured to: charge the inductor, and wherein while the second switching element is disabled and the first switching element is disabled, the power conversion unit is configured to: discharge the inductor to step down the output voltage value to the one or more strings of LEDs.

[0081] Example 12. A system comprises one or more strings of light-emitting diodes (LEDs); a power source; and circuitry configured to monitor the current through one or more strings of light-emitting diodes (LEDs), the circuitry comprising a power conversion unit, the power conversion unit configured to receive an input signal from a power source, and the power conversion unit configured to provide an output signal to the one or more strings of LEDs, the output signal comprising an output voltage and an output current; a setpoint unit configured to provide a setpoint signal to the power conversion unit, the power conversion unit configured to regulate the output current to be proportional to a setpoint parameter value associated with the setpoint signal;and a correction unit configured to: receive an input parameter value, wherein the input parameter value is proportional to the input signal; receive an output parameter value, wherein the output parameter value is proportional to the output voltage; receive a setpoint parameter value, wherein the setpoint parameter value is proportional to the setpoint signal; and, based on the input parameter value, the output parameter value, and the setpoint parameter value, output a correction signal to the power converter unit.

[0082] Example 13. The system of Example 12, wherein the circuit is further configured to: transfer the output signal from a first string of the one or more strings of LEDs to a second string of the one or more strings of LEDs, wherein the setpoint unit is configured to: change the setpoint parameter value from a first setpoint parameter value to a second setpoint parameter value based on transferring the output signal, and wherein, to provide the correction signal to the power conversion unit, the correction unit is configured to: provide the correction signal to the power conversion unit based on a difference between a maximum setpoint parameter value and the second setpoint parameter value to reduce an amount of output current overshoot corresponding to the transfer of the output signal.

[0083] Example 14. The system of examples 12-13 or any combination thereof, wherein a ratio of the output parameter value to the input parameter value represents a gain of the power converter unit, and wherein, to output the correction signal, the power converter unit is configured to: output the correction signal to the power converter unit based on the gain of the power converter unit.

[0084] Example 15. The system of examples 12-14 or any combination thereof, wherein a ratio of the output parameter value to the input parameter value represents a gain of the power converter unit, and wherein, to output the correction signal, the power converter unit is configured to: output the correction signal to the power converter unit based on the gain of the power converter unit.

[0085] Example 16. The system of examples 12-15, or any combination thereof, wherein the circuit is further configured to: based on the change in the setpoint parameter value from the first setpoint parameter value to the second setpoint parameter value, change the output current from a first output current correlated with the first setpoint parameter value to a second output current value correlated with the second setpoint parameter value.

[0086] Example 17. The system of examples 12-16 or any combination thereof, wherein the first output current value is in a range of 1.3 amperes (A) to 1.7 A, and wherein the second output current value is in a range of 0.1 A to 0.5 A.

[0087] Example 18. The system of examples 12-17 or any combination thereof, wherein the circuit is further configured to: change the output voltage from a first output voltage value to a second output voltage value, and wherein, to provide the correction signal to the power conversion unit, the correction unit is configured to: provide the correction signal to the power conversion unit based on a difference between a maximum setpoint parameter value and the setpoint parameter value to reduce an amount of output current overshoot corresponding to the change in output voltage.

[0088] Example 19. The system of examples 12-18 or any combination thereof, wherein the input parameter value represents an input voltage value, and wherein a ratio of the second output voltage value to the input voltage value represents a voltage gain of the power converter unit, and wherein, to output the correction signal, the power converter unit is configured to: output the correction signal to the power converter unit based on the voltage gain of the power converter unit.

[0089] Example 20. A method includes receiving, by a power conversion unit of a circuit configured to monitor the current through one or more strings of light-emitting diodes (LEDs), an input signal from a power source; providing, by the power conversion unit, an output signal to the one or more strings of LEDs, the output signal comprising an output voltage and an output current; and providing, by a setpoint unit, a setpoint signal to the power conversion unit, wherein the power conversion unit regulates the output current to be proportional to a setpoint parameter value associated with the setpoint signal; receiving, by a correction unit, an input parameter value, wherein the input parameter value is proportional to the input signal; receiving, by the correction unit, an output parameter value, wherein the output parameter value is proportional to the output voltage;receiving a setpoint parameter value by the correction unit, wherein the setpoint parameter value is proportional to the setpoint signal; and outputting a correction signal to the power converter unit by the correction unit based on the input parameter value, the output parameter value, and the setpoint parameter value;

[0090] Various examples of the disclosure have been described. These and other examples are within the scope of the following claims.

Claims

[1] A circuit (110, 210, 310, 601) designed to monitor current through one or more strings (130, 230, 330, 618, 620) of light-emitting diodes, the circuit (110, 210, 310, 601) comprising: a power converter unit (112, 212, 312, 602), wherein the power converter unit (112, 212, 312, 602) is configured to receive an input signal from an energy source, and wherein the power converter unit (112, 212, 312, 602) is designed to output an output signal to the one or more strings (130, 230, 330, 618, 620) of light-emitting diodes, the output signal comprising an output voltage and comprises an output current; a setpoint unit (114, 214, 314) designed to to output a setpoint signal to the power converter unit (112, 212, 312, 602), wherein the power converter unit (112, 212, 312, 602) is designed to regulate the output current so that it is proportional to a setpoint parameter value associated with the setpoint signal; and a correction unit (116, 216, 316) designed to: to receive an input parameter value, wherein the input parameter value is proportional to the input signal; to receive an output parameter value, wherein the output parameter value is proportional to the output voltage; to receive the setpoint parameter value, wherein the setpoint parameter value is proportional to the setpoint signal; and to output a correction signal to the power converter unit (112, 212, 312, 602) based on the input parameter value, the output parameter value and the setpoint parameter value. [2] The circuit (110, 210, 310, 601) of claim 1, wherein the circuit (110, 210, 310, 601) is further configured to: Transferring the output signal from a first string of the one or more strings (130, 230, 330, 618, 620) of light-emitting diodes to a second string of the one or more strings (130, 230, 330, 618, 620) of light-emitting diodes, wherein the setpoint unit (114, 214, 314) is designed to: Changing the setpoint parameter value from a first setpoint parameter value to a second setpoint parameter value based on the transfer of the output signal, and wherein, in order to output the correction signal to the power converter unit (112, 212, 312, 602), the correction unit (116, 216, 316) is designed to: Outputting the correction signal to the power converter unit (112, 212, 312, 602) based on a difference between a maximum setpoint parameter value and the second setpoint parameter value to reduce an amount of output current overshoot corresponding to the transfer of the output signal. [3] The circuit (110, 210, 310, 601) of claim 2, wherein a ratio of the output parameter value to the input parameter value represents a gain of the power converter unit (112, 212, 312, 602), and wherein, in order to output the correction signal, the correction unit (116, 216, 316) is configured to: Outputting the correction signal to the power converter unit (112, 212, 312, 602) based on the gain of the power converter unit (112, 212, 312, 602). [4] Circuit (110, 210, 310, 601) according to claim 2 or 3, wherein the circuit (110, 210, 310, 601) is further configured to: based on the change of the setpoint parameter value from the first setpoint parameter value to the second setpoint parameter value, to change the output current from a first output current value correlated with the first setpoint parameter value to a second output current value correlated with the second setpoint parameter value. [5] The circuit (110, 210, 310, 601) of claim 4, wherein the first output current value is in a range of 1.3 A to 1.7 A, and wherein the second output current value is in a range of 0.1 A to 0.5 A. [6] Circuit (110, 210, 310, 601) according to one of claims 1 to 5, wherein the circuit (110, 210, 310, 601) is further designed to: to change the output voltage from a first output voltage value to a second output voltage value, and wherein, in order to output the correction signal to the power converter unit (112, 212, 312, 602), the correction unit (116, 216, 316) is designed to: Outputting the correction signal to the power converter unit (112, 212, 312, 602) based on a difference between a maximum setpoint parameter value and the setpoint parameter value to reduce an amount of output current overshoot corresponding to the change in the output voltage. [7] The circuit (110, 210, 310, 601) of claim 6, wherein the input parameter value represents an input voltage value, and wherein a ratio of the second output voltage value to the input voltage value represents a voltage gain of the power converter unit (112, 212, 312, 602), and wherein, in order to output the correction signal, the correction unit (116, 216, 316) is configured to: Outputting the correction signal to the power converter unit (112, 212, 312, 602) based on the voltage gain of the power converter unit (112, 212, 312, 602). [8] The circuit (110, 210, 310, 601) of any one of claims 1 to 7, wherein the power converter unit (112, 212, 312, 602) further comprises an inductor (250, 350), and wherein the power converter unit (112, 212, 312, 602) comprises: a first current sensor (252, 352) comprising: a first current measuring resistor (254, 354); and a first amplifier (256, 356) designed to one with a current through the inductance (250, 350) and outputting a first current detection signal correlated with a current across the first current measuring resistor (254, 354); and a second current sensor (262, 362) comprising: a second current measuring resistor (264, 364) connected in series with the first current measuring resistor (254, 354); and a second amplifier (266) configured to output a second current detection signal correlated with the output current delivered to the one or more strings (130, 230, 330, 618, 620) of light-emitting diodes and a current across the second current measuring resistor (264, 364), wherein, based on the first current detection signal and the second current detection signal, the power converter unit (112, 212, 312, 602) is configured to regulate at least one of the output current and the output voltage. [9] The circuit (110, 210, 310, 601) of claim 8, wherein the power converter unit (112, 212, 312, 602) further comprises a node (270, 370) and a switching element (242, 342), the node (270, 370) being configured to: to receive the correction signal; to receive the first current detection signal; to receive a comparison signal, wherein the comparison signal is correlated with a difference between the setpoint signal and the second current detection signal; and to output a control signal, wherein the control signal is a summation of the correction signal, the first current detection signal and the comparison signal, and wherein the control signal controls a switching cycle of the switching element (242, 342) to regulate the at least one of the output current and the output voltage, wherein the switching element (242, 342) is configured to activate and Deactivation according to the switching cycle and based on the control signal, wherein the switching cycle defines a duty cycle that is a ratio of a time period, for which the switching element is activated, for a period of time for which the switching element is deactivated. [10] The circuit (110, 210, 310, 601) of claim 9, wherein, while the switching element (242, 342) is activated, the power converter unit (112, 212, 312, 602) is configured to: to charge the inductance (250, 350) and wherein, while the switching element (242, 342) is deactivated, the power converter unit (112, 212, 312, 602) is designed to: to discharge the inductance (250, 350) in order to increase the output voltage value to the one or more strings (130, 230, 330, 618, 620) of light-emitting diodes. [11] The circuit (110, 210, 310, 601) of claim 10, wherein the switching element (242, 342) is a first switching element (242, 342), wherein the power converter unit (112, 212, 312, 602) further comprises a second switching element (246, 346), wherein, while the second switching element (246, 346) is activated and the first switching element (242, 342) is deactivated, the power converter unit (112, 212, 312, 602) is configured to: to charge the inductance (250, 350), and wherein, while the second switching element (246, 346) is deactivated and the first switching element (242, 342) is deactivated, the power converter unit (112, 212, 312, 602) is designed to: to discharge the inductance in order to lower the output voltage value on the one or more strings (130, 230, 330, 618, 620) of light-emitting diodes. [12] System that includes: one or more strings (130, 230, 330, 618, 620) of light-emitting diodes; an energy source (120, 220, 320); and the circuit (110, 210, 310, 601) according to one of claims 1 to 11. [13] Procedure which includes: Receiving an input signal from a power source by a power converter unit (112, 212, 312, 602) of a circuit (110, 210, 310, 601) configured to monitor current through one or more strings (130, 230, 330, 618, 620) of light-emitting diodes; Providing an output signal to the one or more strings (130, 230, 330, 618, 620) of light-emitting diodes by the power converter unit (112, 212, 312, 602), the output signal comprising an output voltage and an output current; Outputting a setpoint signal to the power converter unit (112, 212, 312, 602) by a setpoint unit (114, 214, 314) of the circuit (110, 210, 310, 601), wherein the power converter unit (112, 212, 312, 602) regulates the output current so that it is proportional to a setpoint parameter value associated with the setpoint signal; Receiving an input parameter value by a correction unit (116, 216, 316), wherein the Input parameter value is proportional to the input signal; Receiving an output parameter value by the correction unit (116, 216, 316), the output parameter value being proportional to the output voltage; Receiving the setpoint parameter value by the correction unit (116, 216, 316), wherein the setpoint parameter value is proportional to the setpoint signal; and Outputting a correction signal to the power converter unit (112, 212, 312, 602) by the correction unit (116, 216, 316) based on the input parameter value, the output parameter value and the setpoint parameter value. [14] The method of claim 13, wherein the method is performed using the circuit (110, 210, 310, 601) of any one of claims 1 to 11.

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