阅读说明：本技术 使用计算出的平均电流的功率转换器控制 (Power converter control using calculated average current ) 是由 P·德尔·克罗斯 A·巴齐罗托 O·加斯帕里 A·皮杜蒂 于 2020-01-15 设计创作，主要内容包括：本公开涉及使用计算出的均值电流的功率转换器控制。控制器电路被配置为：驱动开关元件,以建立将电源电耦合至降压转换器的电感元件的通道；并且生成最小电流采样。响应于在开关元件处的电流超过针对降压转换器的控制参数集的目标峰值电流阈值,控制器电路被配置为：生成峰值电流采样,使用最小电流采样和峰值电流采样来计算均值电流,并且使用均值电流来修改控制参数集。响应于开关元件满足控制参数集的截止时间,控制器电路被配置为驱动开关元件,以在随后开关时段的导通状态期间建立将电源电耦合至电感元件的通道。(The present disclosure relates to power converter control using a calculated average current. The controller circuit is configured to: driving a switching element to establish a path electrically coupling a power source to an inductive element of a buck converter; and generates a minimum current sample. In response to the current at the switching element exceeding a target peak current threshold of a set of control parameters for the buck converter, the controller circuit is configured to: the method further includes generating peak current samples, calculating a mean current using the minimum current samples and the peak current samples, and modifying a set of control parameters using the mean current. In response to the switching element meeting the off-time of the set of control parameters, the controller circuit is configured to drive the switching element to establish a channel that electrically couples the power source to the inductive element during the on-state of the subsequent switching period.)

1. A controller circuit for a buck converter configured to provide a set of light emitting diodes (L ED), the controller circuit configured to:

driving a switching element to establish a channel electrically coupling a power source to an inductive element of the buck converter during an on state of a current switching period;

generating a minimum current sample corresponding to a measured current at the switching element in response to driving the switching element for establishing the channel;

in response to the current at the switching element exceeding a target peak current threshold for a set of control parameters for the buck converter:

driving the switching element to avoid establishing the channel electrically coupling the power source to the inductive element during an off state of the current switching period;

generating a peak current sample corresponding to the measured current at the switching element;

calculating a mean current using the minimum current sample and the peak current sample; and

modifying the set of control parameters for the buck converter using the mean current; and

in response to the switching element meeting an off-time of the set of control parameters during the off-state of the current switching period, drive the switching element to establish the channel that electrically couples the power source to the inductive element during an on-state of a subsequent switching period.

2. The controller circuit of claim 1, wherein to modify the set of control parameters, the controller circuit is configured to:

calculating a difference between the mean current and a target mean current; and

modifying the cutoff time using the difference between the mean current and the target mean current.

3. The controller circuit of claim 1, wherein to modify the set of control parameters, the controller circuit is configured to:

calculating a difference between the mean current and a target mean current; and

modifying the target peak current threshold using the difference between the mean current and the target mean current.

4. The controller circuit of claim 1, wherein to calculate the mean current, the controller circuit is configured to:

calculating a mean current using only the minimum current sample and the peak current sample.

5. The controller circuit of claim 1, wherein the controller circuit is configured to:

after generating the minimum current sample and before generating the peak current sample, generating one or more supplemental current samples corresponding to a measured current at the switching element,

wherein to calculate the mean current, the controller circuit is configured to calculate the mean current using the minimum current sample, the peak current sample, and the one or more supplemental current samples.

6. The controller circuit of claim 5, wherein to generate the one or more supplemental current samples, the controller circuit is configured to:

generating the mean current sample corresponding to the measured current at the switching element equidistant from the generated minimum current sample and from the generated peak current sample.

7. The controller circuit of claim 1, wherein the controller circuit comprises:

a current sensor configured to output an indication of a measured current at the switching element;

a comparator configured to output a reset signal in response to the indication of the measured current at the switching element exceeding the target peak current threshold;

a clock configured to output a set signal in response to the switching element satisfying the off-time, the clock being initialized in response to the reset signal; and

a set-reset (SR) latch configured to reset in response to the reset signal and set in response to the set signal, wherein the SR latch outputs a gate drive signal to drive the switching element to establish the channel when the SR latch is set and to drive the switching element to avoid establishing the channel when the SR latch is reset.

8. The controller circuit of claim 7, wherein the controller circuit comprises:

a first register configured to store the peak current sample in response to the measured current at the switching element being greater than the target peak current threshold;

a second register configured to store the minimum current sample in response to the set signal;

a mean calculator configured to receive the peak current sample stored at the first register, receive the minimum current sample stored at the second register, and output the mean current;

an error module configured to receive the mean value from the mean calculator, receive the target peak current threshold, and output an error signal.

9. The controller circuit of claim 8, wherein the controller circuit comprises:

an adder configured to receive the error signal, receive a previous cutoff time, and modify the cutoff time using the error signal and the previous cutoff time.

10. The controller circuit of claim 8, wherein the controller circuit comprises:

an adder configured to receive the error signal, receive a previous target peak current threshold, and modify the target peak current threshold using the error signal and the previous target peak current threshold.

11. The controller circuit according to claim 1,

wherein to generate the minimum current sample corresponding to the measured current at the switching element, the controller circuit is configured to: generating the minimum current sample after driving the switching element to establish the channel for a first switch off duration; and

wherein to generate the peak current sample corresponding to the measured current at the switching element, the controller circuit is configured to: generating the peak current sample after the current at the switching element exceeds the target peak current threshold for a second switch turn-off duration.

12. The controller circuit according to claim 1,

wherein the power supply outputs a voltage between 6 volts and 16 volts; and

wherein the buck converter outputs a voltage between 3 volts and 4 volts to the L ED set, wherein the L ED set includes one or two L ED.

13. The controller circuit according to claim 1,

wherein the power supply comprises a positive node and a reference node;

wherein a current sensor disposed in an integrated circuit having the switching element is configured to: outputting an indication of the measured current at the switching element;

wherein the switching element comprises a control node coupled to the controller circuit, a first node coupled to the positive node, and a second node;

wherein the buck converter comprises a diode having an anode coupled to the reference node and a cathode coupled to the second node of the switching element; and

wherein the inductive element comprises a first node coupled to the second node of the switching element and a second node coupled to the L ED set.

14. A method for controlling a buck converter configured to supply a set of light emitting diodes (L ED), the method comprising:

driving, by controller circuitry, a switching element to establish a channel electrically coupling a power source to an inductive element of the buck converter during a conducting state of a current switching period;

generating, by the controller circuitry, a minimum current sample corresponding to a measured current at the switching element in response to driving the switching element for establishing the channel;

in response to the current at the switching element exceeding a target peak current threshold for a set of control parameters for the buck converter:

driving, by the controller circuitry, the switching element to avoid establishing the channel electrically coupling the power source to the inductive element during an off state of the current switching period;

generating, by the controller circuitry, a peak current sample corresponding to the measured current at the switching element;

calculating, by the controller circuitry, a mean current using the minimum current sample and the peak current sample; and

modifying, by the controller circuitry, the set of control parameters for the buck converter using the mean current; and

in response to the switching element meeting an off-time of the set of control parameters during the off-state of the current switching period, driving, by the controller circuitry, the switching element to establish the channel that electrically couples the power source to the inductive element during an on-state of a subsequent switching period.

15. The method of claim 14, wherein modifying the set of control parameters comprises:

calculating a difference between the mean current and a target mean current; and

modifying the cutoff time using the difference between the mean current and the target mean current.

16. The method of claim 14, wherein modifying the set of control parameters comprises:

calculating a difference between the mean current and a target mean current; and

modifying the target peak current threshold using the difference between the mean current and the target mean current.

17. The method of claim 14, wherein calculating the mean current comprises:

calculating a mean current using only the minimum current sample and the peak current sample.

18. The method of claim 14, further comprising:

generating, by the controller circuit, one or more supplemental current samples corresponding to the measured current at the switching element after generating the minimum current sample and before generating the peak current sample,

wherein calculating the mean current comprises: calculating the mean current using the minimum current sample, the peak current sample, and the one or more supplemental current samples.

19. The method of claim 18, wherein generating the one or more supplemental current samples comprises:

generating the mean current sample corresponding to the measured current at the switching element equidistant from the generated minimum current sample and from the generated peak current sample.

20. A buck converter system comprising:

a battery;

a set of light emitting diodes (L ED);

a buck converter including an inductive element;

a controller circuit configured to:

driving a switching element to establish a channel electrically coupling the battery to the inductive element during an on state of a current switching period;

generating a minimum current sample corresponding to a measured current at the switching element in response to driving the switching element for establishing the channel;

in response to the current at the switching element exceeding a target peak current threshold for a set of control parameters for the buck converter:

driving the switching element to avoid establishing the channel electrically coupling the battery to the inductive element during an off state of the current switching period;

generating a peak current sample corresponding to the measured current at the switching element;

calculating a mean current using the minimum current sample and the peak current sample; and

modifying the set of control parameters for the buck converter using the mean current; and

in response to the switching element meeting an off-time of the set of control parameters during the off-state of the current switching period, drive the switching element to establish the channel that electrically couples the battery to the inductive element during an on-state of a subsequent switching period.

Technical Field

The present disclosure relates to electrical power converters, and in particular, to buck converters.

Background

DC/DC converters, including buck converters, may be used as drivers for loads with specific current and/or voltage requirements, such as chains of one or more light emitting diodes (L ED). L ED chain light intensity is controlled by the amount of current flowing through the L ED chain.

Disclosure of Invention

In this example, the controller circuit may drive the buck converter to supply an average current to the L ED set without directly measuring the current at the L ED set.

In one example, a controller circuit for a buck converter is configured to: driving a switching element to establish a channel electrically coupling a power source to an inductive element of a buck converter during an on state of a current switching period; generating a minimum current sample corresponding to a measured current at a switching element in response to driving the switching element for establishing the channel; in response to the current at the switching element exceeding a target peak current threshold for a set of control parameters for the buck converter: driving the switching element to avoid establishing a channel electrically coupling the power source to the inductive element during an off-state of a current switching period; generating a peak current sample corresponding to the measured current at the switching element; calculating a mean current using the minimum current sample and the peak current sample; and modifying a set of control parameters for the buck converter using the mean current; and in response to the switching element meeting the off-time of the set of control parameters during the off-state of the current switching period, drive the switching element to establish a channel that electrically couples the power source to the inductive element during the on-state of the subsequent switching period.

In another example, a method for controlling a buck converter includes: driving, by controller circuitry, a switching element to establish a channel electrically coupling a power source to an inductive element of a buck converter during a conducting state of a current switching period; generating, by controller circuitry, a minimum current sample corresponding to a measured current at a switching element in response to driving the switching element for establishing a channel; in response to the current at the switching element exceeding a target peak current threshold for a set of control parameters for the buck converter: driving, by controller circuitry, the switching element to avoid establishing a channel electrically coupling the power source to the inductive element during an off state of a current switching period; generating, by controller circuitry, a peak current sample corresponding to the measured current at the switching element; calculating, by the controller circuitry, a mean current using the minimum current sample and the peak current sample; and modifying, by the controller circuitry, a set of control parameters for the buck converter using the mean current; and in response to the switching element meeting the off-time of the set of control parameters during the off-state of the current switching period, driving, by the controller circuitry, the switching element to establish a channel that electrically couples the power source to the inductive element during the on-state of the subsequent switching period.

In another example, a buck converter system includes a battery, an L ED set, a buck converter including an inductive element, a controller circuit configured to drive a switching element to establish a channel electrically coupling the battery to the inductive element during an on state of a current switching period, generate a minimum current sample corresponding to a measured current at the switching element in response to driving the switching element to establish the channel, drive the switching element to avoid establishing the channel electrically coupling the battery to the inductive element during an off state of the current switching period, generate a peak current sample corresponding to the measured current at the switching element, calculate a mean current using the minimum current sample and the peak current sample, and modify the control parameter set for the buck converter using the mean current, and drive the switching element to establish the channel electrically coupling the battery to the inductive element during an on state of a subsequent switching period in response to the switching element satisfying an off time for the control parameter set during an off state of the current switching period.

The details of these examples and other examples are set forth in the description and figures below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.

Drawings

Fig. 1 is a block diagram illustrating an example system configured for power converter control using a calculated average current in accordance with one or more techniques of this disclosure.

Fig. 2 is a conceptual diagram illustrating an example controller circuit configured to modify a cutoff time in accordance with one or more techniques of this disclosure.

Fig. 3 is a schematic diagram of a first performance of the example controller circuit of fig. 2, in accordance with one or more techniques of this disclosure.

Fig. 4 is a schematic diagram of a second performance of the example controller circuit of fig. 2, in accordance with one or more techniques of this disclosure.

Fig. 5 is a conceptual diagram illustrating an example controller circuit configured to modify a target peak current threshold in accordance with one or more techniques of this disclosure.

Fig. 6 is a flow diagram consistent with a technique for controlling a buck converter using a calculated average current according to the present disclosure.

Detailed Description

In some examples, light emitting diode (L ED) applications may use L ED sets having a combined operating voltage less than a supply voltage, such L ED applications may be used in automotive lighting or other settings, automotive lighting may include, for example, instrument or control lighting, and automotive front lighting (e.g., high beam lighting, low beam lighting, directional lighting, object detection based lighting, or other lighting technologies).

In some systems, a controller circuit for buck converter control may apply a controlled time-off ("Toff") topology to control the average current output to the L ED set.

The controller circuit may use internal readings of the current (e.g., on-chip) without relying on a sense resistor external to the IC implementing the controller circuit. In this way, Rsense pins may be omitted on the IC and the corresponding PCB may omit additional pads and metal lines, which reduces space on the PCB and the cost of the IC, PCB and the resulting controller circuitry.

For example, when a minimum current at an inductor of the buck converter is reached, the controller circuit may generate (e.g., sample using an analog-to-digital converter (ADC), store at a capacitor, etc.) a first current sample during the on-phase.

For example, the controller circuit may dynamically modify a time-off value used to determine when to begin an on-phase of the buck converter, thereby minimizing a difference between the average current and the target average current.

A controller circuit configured to use internal current readings may integrate more on-chip (e.g., within a single IC) components, which may reduce cost compared to a controller circuit using external sense resistors. Furthermore, a system using internal readings may sense the current between the high-side switching elements (e.g., DMOS) and the diode, so that the current will only be read during the on-phase of the high-side switching elements, which may reduce power consumption compared to a system that reads the current during both the on-phase and the off-phase of the high-side switching elements.

FIG. 1 is a block diagram illustrating an example system 100 configured for power converter control using a calculated average current in accordance with one or more techniques of this disclosure, as shown in the example of FIG. 1, the system 100 may include a power supply 102, a buck converter 104, a L ED106 set (hereinafter "L ED"), a controller circuit 110, a switching element 112, and a current sensor 114. As shown, the buck converter 104 includes an inductive element 116 and a diode 118. in some examples, the diode 118 may instead include a switching element configured for active rectification.

The power source 102 may be configured to provide electrical power to one or more other components of the system 100. for example, the power source 102 may be configured to supply power to the L EDs 106. in some examples, the power source 102 includes a battery that may be configured to store electrical energyAcid, nickel metal hydride, nickel zinc, silver oxide, lithium ion, lithium polymer, any other type of rechargeable battery, or any combination thereof. In some examples, the power source 102 may include an output of a linear voltage regulator, a power converter, or a power inverter. For example, the power supply 102 may include an output of a DC to DC power converter, an output of an Alternating Current (AC) to DC power converter, and so forth. In some examples, the power source 102 may represent a connection to an electrical power supply grid. In some examples, the input power signal provided by the power supply 102 may be a DC input power signal. For example, in some examples, the power supply 102 may be configured to provide at about 5V_DCTo about 40V_DCDC input power signal within a range of (a). In some examples, the power supply 102 may output a voltage between 6 volts and 16 volts.

As used herein, a vehicle may refer to a truck, boat, golf cart, snowmobile, heavy machinery, or any type of vehicle that uses directional lighting.A L ED106 may include one or two L EDs in some examples.

The current sensor 114 may include an internal resistor that generates a voltage corresponding to a current flowing through the internal resistor. In some examples, the current sensor 114 may include a hall effect sensor, a current clamp meter, or another current sensor.

The switching element 112 may be configured to establish a path that electrically couples the power source 102 to the inductive element 116. Examples of switching elements may include, but are not limited to, Silicon Controlled Rectifiers (SCRs), Field Effect Transistors (FETs), and Bipolar Junction Transistors (BJTs). Examples of FETs may include, but are not limited to, Junction Field Effect Transistors (JFETs), Metal Oxide Semiconductor FETs (MOSFETs), double gate MOSFETs, Insulated Gate Bipolar Transistors (IGBTs), any other type of FET, or any combination thereof. Examples of MOSFETs may include, but are not limited to, depletion mode p-channel MOSFETs (PMOS), enhancement mode PMOS, depletion mode n-channel MOSFETs (NMOS), enhancement mode NMOS, double diffused MOSFETs (dmos), 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. The switching element may be a high-side or a low-side switching element. Additionally, the switching element may be voltage-controlled and/or current-controlled. Examples of current-controlled switching elements may include, but are not limited to, gallium nitride (GaN) MOSFETs, BJTs, or other current-controlled elements.

The controller circuit 110 may be configured to control the switching element 112 such that the average current at L ED106 corresponds to (e.g., is equal to, proportional to, etc.) the target average current in some examples, the controller circuit 110 may switch the switching element 112 such that the buck converter 104 outputs a voltage between 3 volts and 4 volts to the L ED 106.

The controller circuit 110 may comprise a microcontroller on a single integrated circuit comprising a processor core, a memory, an input, and an output. For example, the controller circuitry 110 may include one or more processors including one or more microprocessors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components. The term "processor" or "processing circuitry" may generally refer to any of the foregoing logic circuitry, circuitry alone or in combination with other logic circuitry, or any other equivalent circuitry. The controller circuit 110 may be a combination of one or more analog components and one or more digital components.

In the example of fig. 1, the power source 102 includes a positive node and a reference node (e.g., ground, a local ground rail, or another reference node). in this example, the current sensor 114 is disposed in an integrated circuit having the switching element 112, and the sensor 114 is configured to output an indication of the measured current at the switching element 112. as shown, the switching element 112 includes a control node coupled to the controller circuit 110, a first node coupled to the positive node of the power source 102. as shown, the buck converter 104 includes an anode having a reference node coupled to the power source 102, and a cathode coupled to the second node of the switching element 112. as shown, the inductive element 116 includes a first node coupled to the second node of the switching element 112, and a second node coupled to L ED 106.

In accordance with one or more of the described techniques, the controller circuit may be configured to drive the switching element 112 to establish a channel that electrically couples the power source 102 to the inductive element 116 of the buck converter 104 during the conductive state of the current switching period; in response to driving the switching element 112 for establishing the channel, the controller circuit 110 may be configured to generate a minimum current sample corresponding to the measured current at the switching element 112; in response to the current at the switching element 112 exceeding a target peak current threshold of the set of control parameters for the buck converter 104, the controller circuit 110 may be configured to drive the switching element 112 to avoid establishing a channel electrically coupling the power source 102 to the inductive element 106 during the off-state of the current switching period; generating a peak current sample corresponding to the measured current at the switching element 112; calculating a mean current using the minimum current sample and the peak current sample; and the average current is used to modify the set of control parameters for the buck converter 104. In response to the switching element 112 satisfying the off-time of the set of control parameters during the off-state of the current switching period, the controller circuit 110 may be configured to drive the switching element 112 to establish a path that electrically couples the power source 102 to the inductive element 116 during the on-state of the subsequent switching period.

Fig. 2 is a conceptual diagram illustrating an example controller circuit configured to modify a cutoff time in accordance with one or more techniques of this disclosure. The controller circuit 210 may correspond to the controller circuit 110 of the system 100 shown in fig. 1. In the example of fig. 2, the controller circuit 210 includes a current sensor 214, a register 219, a comparator 220, a clock 222, a set-reset (SR) latch 224, a register 226, a mean calculator 228, an error module 230, and an adder 232. In the example of fig. 2, the controller circuit 210 modifies the off-time of the set of control parameters for the buck converter. Additionally, or alternatively, the controller circuit may modify other parameters of the set of control parameters for the buck converter, such as, but not limited to, the target peak current threshold (see fig. 5).

In the example of fig. 2, the current sensor 214 is configured to output an indication of the measured current at the switching element 112 of fig. 1. The comparator 220 is configured to output a reset signal in response to the indication of the measured current at the switching element exceeding the target peak current threshold. The clock 222 is configured to output a set signal in response to the switching element satisfying the off-time, the clock being initialized in response to the reset signal. When the count value of the clock 222 set to 0 by the reset signal output by the comparator 220 exceeds the off-time, the clock 222 may determine that the off-time during the off-state of the current switching period is satisfied.

The SR latch 224 is configured to be reset in response to a reset signal and set in response to a set signal. The SR latch outputs a gate drive signal to drive the switching element 112 to establish a channel when the SR latch is set, and to drive the switching element 112 to avoid establishing a channel when the SR latch is reset.

The register 219 is configured to: in response to the measured current at the switching element 112 being greater than the target peak current threshold, a peak current sample is stored. For example, the register 219 may be configured to store peak current samples in response to a reset signal. The register 226 is configured to store a minimum current sample in response to a set signal.

The mean calculator 228 is configured to receive the peak current stored at register 219, receive the minimum current sample stored at register 226, and output a mean current. For example, the mean calculator 228 may be configured to calculate the mean current using only the minimum current samples and the peak current samples. For example, the mean calculator 228 may calculate the mean current as the sum of the minimum current sample and the peak current sample divided by 2.

In some examples, the controller circuit 210 may be configured to: after generating the minimum current sample and before generating the peak current sample, one or more supplemental current samples corresponding to the measured current at the switching element are generated. In this example, the mean calculator 228 may be configured to calculate the mean current using the minimum current sample, the peak current sample, and the one or more supplemental current samples. In some examples, the mean calculator 228 may generate mean current samples corresponding to the measured current at the switching element 112 equidistant from generating a minimum current sample and from generating a peak current sample. For example, the mean calculator 228 may calculate the mean current as an average of mean current samples corresponding to the measured current at the switching element and a result of dividing a sum of minimum current samples and peak current samples by 2, the mean current samples being equidistant from the generated minimum current samples and from the generated peak current samples.

The error module 230 may be configured to receive the mean value from the mean calculator 228, receive the target peak current threshold, and output an error signal. For example, the error module 230 may calculate a difference between the mean current and the target mean current. The adder 232 may be configured to receive the error signal, receive the previous cutoff time, and modify the cutoff time using the error signal and the previous cutoff time. In other words, the adder 232 may modify the off-time using the difference between the mean current and the target mean current. For example, the adder 232 may add a value corresponding to a difference between the mean current and the target mean current to the Toff value, which is increased or decreased.

In an exemplary operation, the comparator 220 compares the measured current to a reference Iref, i.e., a peak current threshold. Once the current reaches this value, the comparator 220 sets the reset input of the SR latch 224 high. In response to setting the reset input, clock 222 begins counting for an amount of time equal to Toff. The clock 222 generates a gate driving signal to turn on the switching element 112 after the Toff period.

When the switching element 112 is turned on, the current is minimum and the register 226 stores the minimum value of the current. The storing may be performed by coupling a set signal to the enable of the register 226. Likewise, when the switching element 112 is turned off, the current is maximum and the register 219 stores the maximum value of the current. The storing may be performed by connecting a reset signal to the enable of the register 219.

Once the minimum current value is available, the mean calculator 228 may calculate the mean as the sum of the reference value, which is the maximum value reached by the current, and the stored minimum value divided by 2. The error module 230 may compare the calculated average value to a searched value (e.g., a target average current) to obtain a difference of the calculated average value and the searched value. The adder then adds the generated difference to the Toff value, which will increase or decrease. In particular, if the calculated average is higher than the searched value, the Toff value may be increased, and if the calculated average is not higher than the searched value, the Toff value may be decreased. In an example, the controller circuit 210 may give the next Toff value by the control loop itself, and at each subsequent cycle the average current may become increasingly closer to the searched value. Accordingly, controller circuit 210 may help control the peak and average values of the current with greater accuracy than systems using constant Toff values. In addition, the controller circuit 210 may help control the accuracy of the current ripple, as the current ripple may depend on how close the average value is to the peak reference. For example, if the average current is very close to the peak reference, very little ripple may be generated.

Fig. 3 is a schematic diagram of a first performance of the example controller circuit 210 of fig. 2, in accordance with one or more techniques of this disclosure. The abscissa axis (e.g., horizontal) of fig. 3 represents time and the ordinate axis (e.g., vertical) of fig. 3 represents inductor current 302, count value 304, and gate drive signal 306.

In the example of fig. 3, the switching element 112 is closed and the controller circuit 210 monitors the rise time of the inductor current 302 by, for example, reading the current. At time 310, inductor current 302 reaches a reference, such as a target peak current threshold. In this example, register 219 may store maximum value 330 in response to inductor current 302 reaching a reference. In response to the inductor current 302 reaching the reference, the SR latch 224 generates a voltage that causes the switching element 112 to open and the inductor current 302 to decrease. At the same time, the clock 222 is initialized and a count value 304 is generated to start counting from 0 to a particular value identifying Toff.

Accordingly, after a duration equal to Toff, the SR latch 224 generates a gate drive signal that closes the switching element 112. At this point, inductor current 302 stops decreasing and begins to increase. For brief instances, inductor current 302 is at a minimum value 332. In the example of fig. 3, the register 226 may store the minimum value 332 after a duration equal to Toff. The mean calculator 228 may use the maximum 330 and minimum 332 values to generate an error signal that is used by the adder 232 to modify the off-time to control the peak and mean values of the current with greater accuracy than systems using constant Toff values.

Fig. 4 is a schematic diagram of a second performance of the example controller circuit of fig. 2, in accordance with one or more techniques of this disclosure. The abscissa axis (e.g., horizontal) of fig. 4 represents time and the ordinate axis (e.g., vertical) of fig. 4 represents inductor current 402.

In the example of fig. 4, the controller circuit 210 operates such that the Toff period in which the switch is off is updated at each switching cycle based on the average current calculated by the loop. In the example of fig. 4, the error module 230 compares the calculated average value 420 with the searched mean value Imean. In this manner, error module 230 is able to derive a signed error that adder 232 may add to the previous value of Toff. The Toff period can be increased or decreased to lengthen or shorten the ripple of the inductor current 402 until the calculated average value coincides with the desired value. In this manner, the controller circuit 210 may achieve a steady state condition.

Due to technical limitations, the inductor current 402 may not be accurately read at the minimum current value. The read circuitry (e.g., current sensor 214) may have a settling time after closing the switching element 112. If the settling time is related to Ton, the controller circuit 212 may extrapolate the minimum current during post-processing. For example, to generate a minimum current sample corresponding to the measured current at the switching element 112, the controller circuit 210 may be configured to: after driving the switching element 112 to establish the channel for a first switch off duration, a minimum current sample is generated. In this example, to generate peak current samples corresponding to the measured current at the switching element 112, the controller circuit 210 may be configured to: the peak current sample is generated after the current at the switching element 112 exceeds the target peak current threshold for a second switch off duration. In some embodiments, controller circuit 210 may use more than two measurements during the on phase.

The controller circuit 210 may be configured to generate (e.g., store digital values in memory, analog values in capacitors, etc.) a minimum current sample corresponding to the measured current at the switching element 112 in response to driving the switching element 112 for establishing the channel. Examples of generating the minimum current sample in response to driving the switching element 112 for establishing the channel may include, but are not limited to: the minimum current sample is generated before, during, or (slightly) after driving the switching element for establishing the channel.

Similarly, the controller circuit 210 may be configured to generate (e.g., store digital values in memory, analog values in capacitors, etc.) peak current samples corresponding to the measured current at the switching element 112 in response to the current at the switching element 112 exceeding a target peak current threshold for a set of control parameters for the buck converter 104. Examples of generating peak current samples in response to the current at the switching element 112 exceeding the target peak current threshold may include, but are not limited to: the peak current sample is generated before, during, or (slightly) after the current at the switching element 112 exceeds the target peak current threshold.

The current sensor 214 detects the measured current at the switching element prior to or substantially simultaneously with generating the current sample. For example, the current sensor 214 may continuously detect the current at the switching element 112 in response to driving the switching element 112 for establishing the channel, and the newly detected measured current is generated only as a minimum current sample. In another embodiment, the current sensor 214 may continuously detect the current at the switching element 112 in response to the current at the switching element 112 exceeding a target peak current threshold, and the newly detected measured current is generated only as a peak current sample.

Fig. 5 is a conceptual diagram illustrating an example controller circuit configured to modify a target peak current threshold in accordance with one or more techniques of this disclosure. The controller circuit 510 may correspond to the controller circuit 110 of the system 100 shown in fig. 1. In the example of fig. 5, the controller circuit 510 may include a current sensor 514, a register 519, a comparator 520, a clock 522, an SR latch 524, a register 526, a mean calculator 528, an error module 530, and an adder 532.

In the example of fig. 5, the current sensor 514 is configured to output an indication of the measured current at the switching element 112 of fig. 1. The comparator 520 is configured to output a reset signal in response to the indication of the measured current at the switching element 112 exceeding the target peak current threshold. The clock 522 is configured to output a set signal in response to the switching element 112 satisfying the off-time, the clock being initialized in response to the reset signal. When the count value of the clock 522 at which the reset signal output by the comparator 520 is set to 0 exceeds the off-time, the clock 522 may determine that the off-time during the off-state of the current switching period is satisfied.

The SR latch 524 is configured to be reset in response to a reset signal and set in response to a set signal. The SR latch 524 may output a gate driving signal to drive the switching element 112 to establish the channel when the SR latch 524 is set, and to drive the switching element 112 to avoid establishing the channel when the SR latch 524 is reset.

The register 519 is configured to store a peak current sample in response to the measured current at the switching element 112 being greater than a target peak current threshold. The register 526 is configured to store a minimum current sample in response to a set signal.

The mean calculator 528 is configured to receive the peak current stored at the register 519, receive the minimum current sample stored at the register 526, and output a mean current. For example, the mean calculator 528 may be configured to calculate the mean current using only the minimum current samples and the peak current samples.

In some examples, the controller circuit 510 may be configured to generate one or more supplemental current samples corresponding to the measured current at the switching element after generating the minimum current sample and before generating the peak current sample. In this example, the mean calculator 528 may be configured to calculate the mean current using the minimum current sample, the peak current sample, and the one or more supplemental current samples. In some examples, the mean calculator 528 may generate mean current samples corresponding to the measured current at the switching element equidistant from the generated minimum current sample and from the generated peak current sample.

The error module 530 may be configured to receive the mean value from the mean calculator 528, receive the target peak current threshold, and output an error signal. For example, the error module 530 may calculate a difference between the mean current and the target mean current. The summer 532 may be configured to receive the error signal, receive a previous target peak current threshold, and modify the target peak current threshold using the error signal and the previous target peak current threshold. In other words, the adder 532 may use the difference between the average current and the target average current to modify the target peak current threshold. For example, the adder 532 may add a value corresponding to (e.g., equal to, proportional to, etc.) the difference between the average current and the target average current to the target peak current threshold, which will be increased or decreased.

For illustrative purposes only, example operations are described below within the context of fig. 1-5, however, the techniques described below may be used in any arrangement and any combination with the power supply 102, buck converter 104, L ED106, controller circuit 110, switching element 112, and current sensor 114 of fig. 1.

In accordance with one or more techniques of this disclosure, the SR latch 224 switches (602) in the switching element 112. Register 226 generates a minimum current sample (604). The SR latch 224 turns off the switching element 112(606) in response to the measured current exceeding the maximum current threshold. For example, the comparator determines that the measured current exceeds the maximum current threshold and outputs a reset signal to the SR latch 224.

Register 219 generates a peak current sample (608). For example, the register 219 generates peak current samples in response to a reset signal to the SR latch 224. The mean calculator 228 calculates a mean current using the minimum current sample and the peak current sample (610). The error module 230 calculates a difference between the target average current and the calculated average current (612). Adder 232 modifies a control parameter set that includes a maximum current threshold and an off-time (614). For example, adder 232 modifies the cutoff time. In some examples, adder 532 modifies the maximum current threshold. The clock 222 determines that the off-time has elapsed (616), and for the subsequent switching period, the process repeats to step 602.

The following examples may illustrate one or more aspects of the present disclosure.

Example 1 a controller circuit for a buck converter configured to provide a set of light emitting diodes (L ED), the controller circuit configured to drive a switching element to establish a channel electrically coupling a power source to an inductive element of the buck converter during an on state of a current switching period, to generate a minimum current sample corresponding to a measured current at the switching element in response to driving the switching element to establish the channel, to drive the switching element to avoid establishing the channel electrically coupling the power source to the inductive element during an off state of the current switching period, to generate a peak current sample corresponding to the measured current at the switching element, to calculate a mean current using the minimum current sample and the peak current sample, and to modify the set of control parameters for the buck converter using the mean current, and to drive the switching element to establish the channel of the power source to the inductive element during a subsequent on state of the switching period in response to the switching element meeting an off time of the set of control parameters during the off state of the current switching period.

Example 2. the controller circuit of example 1, wherein to modify the set of control parameters, the controller circuit is configured to: calculating the difference between the average current and the target average current; and modifying the off-time using the difference between the mean current and the target mean current.

Example 3. the controller circuit of any one of the combinations of examples 1-2, wherein to modify the set of control parameters, the controller circuit is configured to: calculating the difference between the average current and the target average current; and modifying the target peak current threshold using the difference between the mean current and the target mean current.

Example 4. the controller circuit of any one of the combinations of examples 1-3, wherein to calculate the mean current, the controller circuit is configured to: an average current is calculated using only the minimum current sample and the peak current sample.

Example 5. the controller circuit of any one of the combinations of examples 1-4, wherein the controller circuit is configured to: after generating the minimum current sample and before generating the peak current sample, generating one or more supplemental current samples corresponding to a measured current at a switching element, wherein to calculate the mean current, the controller circuit is configured to calculate the mean current using the minimum current sample, the peak current sample, and the one or more supplemental current samples.

Example 6. the controller circuit of any one of the combinations of examples 1-5, wherein to generate the one or more supplemental current samples, the controller circuit is configured to: generating a mean current sample corresponding to the measured current at the switching element, the mean current sample being equidistant from the minimum current sample generated and from the peak current sample generated.

Example 7. the controller circuit of any one of the combinations of examples 1-6, wherein the controller circuit comprises: a current sensor configured to output an indication of the measured current at the switching element; a comparator configured to output a reset signal in response to the indication of the measured current at the switching element exceeding a target peak current threshold; a clock configured to output a set signal in response to the switching element satisfying the off-time, the clock being initialized in response to the reset signal; and a set-reset (SR) latch configured to be reset in response to the reset signal and set in response to the set signal, wherein the SR latch outputs a gate driving signal to drive the switching element to establish the channel when the SR latch is set, and to drive the switching element to avoid establishing the channel when the SR latch is reset.

Example 8. the controller circuit of any one of the combinations of examples 1-7, wherein the controller circuit comprises: a first register configured to store the peak current sample in response to the measured current at the switching element being greater than the target peak current threshold; a second register configured to store the minimum current sample in response to the set signal; a mean calculator configured to receive the peak current sample stored at the first register, receive the minimum current sample stored at the second register, and output the mean current; an error module configured to receive the mean value from the mean calculator, receive the target peak current threshold, and output an error signal.

Example 9. the controller circuit of any one of the combinations of examples 1-8, wherein the controller circuit comprises: an adder configured to receive the error signal, receive a previous cutoff time, and modify the cutoff time using the error signal and the previous cutoff time.

Example 10. the controller circuit of any one of the combinations of examples 1-9, wherein the controller circuit comprises: an adder configured to receive the error signal, receive a previous target peak current threshold, and modify the target peak current threshold using the error signal and the previous target peak current threshold.

Example 11 the controller circuit of any one of the combinations of examples 1-10, wherein to generate the minimum current sample corresponding to the measured current at the switching element, the controller circuit is configured to: generating the minimum current sample after driving the switching element to establish a channel for a first switch turn-off duration; and wherein to generate the peak current sample corresponding to the measured current at the switching element, the controller circuit is configured to: the peak current sample is generated after the current at the switching element exceeds the target peak current threshold for a second switch off duration.

Example 12. the controller circuit of any one of the combinations of examples 1-11, wherein the power supply outputs a voltage between 6 volts and 16 volts, and wherein the buck converter outputs a voltage between 3 volts and 4 volts to L ED sets, wherein the L ED set includes one or two L ED.

Example 13. the controller circuit of any one of the combinations of examples 1-12, wherein the power supply includes a positive node and a reference node, wherein a current sensor disposed in an integrated circuit having the switching element is configured to output an indication of a measured current at the switching element, wherein the switching element includes a control node coupled to the controller circuit, a first node coupled to the positive node, and a second node, the buck converter includes a diode having an anode coupled to the reference node and a cathode coupled to the second node of the switching element, and wherein the inductive element includes a first node coupled to the second node of the switching element and a second node coupled to the L ED set.

Example 14 a method for controlling a buck converter configured to supply a set of light emitting diodes (L ED), the method including driving a switching element by controller circuitry to establish a channel electrically coupling a power source to an inductive element of the buck converter during an on state of a current switching period, generating, by the controller circuitry, a minimum current sample corresponding to a measured current at the switching element in response to driving the switching element to establish the channel, driving, by the controller circuitry, the switching element to avoid establishing the channel electrically coupling the power source to the inductive element during an off state of the current switching period, in response to the current at the switching element exceeding a target peak current threshold for a set of control parameters of the buck converter, generating, by the controller circuitry, a peak current sample corresponding to the measured current at the switching element, calculating, by the controller circuitry, a mean current using the minimum current sample and the peak current sample, and modifying, by the controller circuitry, the control element for the buck converter using the mean current, and satisfying, during a subsequent off state of the switching element, the set of the switching element during the current switching period, the off state, the set of the control elements satisfying the set of control parameters of the buck converter.

Example 15 the method of example 14, wherein modifying the set of control parameters comprises: calculating a difference between the mean current and a target mean current; and modifying the cutoff time using the difference between the mean current and the target mean current.

Example 16 the method of any one of the combinations of examples 14-15, wherein modifying the set of control parameters comprises: calculating a difference between the mean current and a target mean current; and modifying the target peak current threshold using the difference between the mean current and the target mean current.

Example 17. the method of any one of the combinations of examples 14-16, wherein calculating the mean current includes: the mean current is calculated using only the minimum current sample and the peak current sample.

Example 18. the method according to any one of the combinations of examples 14-17, further comprising: after generating the minimum current sample and before generating the peak current sample, generating, by the controller circuitry, one or more supplemental current samples corresponding to a measured current at a switching element, wherein calculating the mean current comprises calculating the mean current using the minimum current sample, the peak current sample, and the one or more supplemental current samples.

Example 19. the method of any one of the combinations of examples 14-18, wherein generating the one or more supplemental current samples comprises: generating the mean current sample corresponding to the measured current at the switching element equidistant from the minimum current sample generated and the peak current sample generated.

Example 20. a buck converter system includes a battery, a set of light emitting diodes (L ED), a buck converter including an inductive element, a controller circuit configured to drive a switching element to establish a channel electrically coupling the battery to the inductive element during an on state of a current switching period, to generate a minimum current sample corresponding to a measured current at the switching element in response to driving the switching element to establish the channel, to drive the switching element to avoid establishing the channel electrically coupling the battery to the inductive element during an off state of the current switching period, to generate a peak current sample corresponding to the measured current at the switching element, to calculate a mean current using the minimum current sample and the peak current sample, and to modify the set of control parameters for the buck converter using the mean current, and to drive the switching element to establish the channel during the on state of the switching element during a subsequent on state of the switching period in response to the switching element satisfying the set of control parameters during the off state of the current switching period.

Various aspects have been described in this disclosure. These and other aspects are within the scope of the appended claims.