CN117598029A - Control method and device of buck conversion circuit, LED driver and LED device - Google Patents

Abstract

The invention provides a control method and device for a buck conversion circuit, a buck conversion circuit, an LED driver and an LED device. The control method includes calculating the resonance time; determining the compensation time based on the resonance time; and updating the buck based on the compensation time. The total T _off time of the switch in the conversion circuit; use the updated T _off time to generate the drive control signal of the switch to obtain the output voltage.

Description

Control method and device for step-down conversion circuit, step-down conversion circuit, LED driver Drivers and LED devices

Technical field

Embodiments of the present invention generally relate to the field of antenna design, and more specifically, to control methods and devices for buck conversion circuits, buck conversion circuits, LED drivers, and LED devices.

Background technique

In recent years, light-emitting diodes (LEDs) have been widely used in the lighting field, and they usually require constant current driving. Currently, LED drivers are usually used to provide constant driving current for LEDs.

LED drivers typically use a combination of flyback or boost power factor correction (PFC) circuits, followed by a buck conversion circuit using a digital buck solution controlled by T _off , where T _off is the switch off time.

Figure 1 shows a diagram showing the overall structure of an LED driver; as shown in Figure 1, the LED driver 50 includes an electromagnetic interference (EMI) filter 51, a boost PFC circuit 52, and a direct current (DC)-DC conversion circuit 53 (Such as a buck converter circuit). The EMI filter 51 filters electromagnetic interference; the boost-type PFC circuit 52 converts the input AC power into DC power; the buck-type conversion circuit 53 converts the DC voltage of the boost-type PFC circuit 52 into an output voltage, and the output voltage is For driving lighting equipment, for example, the lighting equipment is an LED. Detailed functions of other parts can be referred to related technologies and will not be described again here. For example, the controller 54 controls the DC-DC conversion circuit 53; and the control circuit 55 communicates with the controller 54. Control circuitry 54 communicates with peripheral devices through interfaces. For example, peripheral devices can be dimmers, sensors, controllers, security devices, etc.

Figure 2 shows the relationship between the safety or discrete extra low voltage (SELV) output voltage and output current of an LED driver. As shown in Figure 2, the LED driver will provide a wide output current range from 100mA to 1050mA. The buck converter circuit operates in continuous current mode (CCM) where the current I_L through the inductor will never fall to zero, and in continuous current mode (CCM) where the current I_L through the inductor will fall to zero over a period of time. Continuous current mode (DCM) operation. Under CCM, load regulation is good and adequate. Under DCM, load regulation cannot meet the required accuracy.

This section introduces aspects that may be helpful in better understanding the disclosure. Accordingly, the statements in this section should be read in this context and should not be construed as an admission that what is or is not the prior art.

Contents of the invention

In the Ulysses W2 project, it is designed with PFC plus buck SELV output. It is implemented through T _off control to maintain the buck operating under CCM and DCM in order to supply a constant current output. Figure 3 shows a block diagram of a solution for a buck converter circuit. Figure 4 shows a diagram of a conventional buck converter circuit. As shown in Figures 3 and 4, in existing buck-type conversion circuits, a microcontroller unit (MCU) generates a pulse-width modulation (PWM) signal by using proportional integral derivative (PID) based on the feedback voltage and DC input. The PWM signal is used as a signal to drive the Mos drive circuit (as a switch).

The inventor found that when the buck converter circuit is operated in DCM mode and a high current output is selected, the load regulation will be out of range.

In order to solve at least part of the above problems, methods, devices, and equipment are provided in the present disclosure. Features and advantages of embodiments of the present disclosure will also be understood from the following description of specific embodiments when taken in conjunction with the accompanying drawings, which illustrate by way of example the principles of embodiments of the present disclosure.

Generally speaking, embodiments of the present disclosure provide a control method and device for a buck conversion circuit, a buck conversion circuit, an LED driver, and an LED device. Improved load regulation is desired.

In a first aspect, a step-down conversion circuit control method applied to a step-down conversion circuit is provided. The method includes:

Calculate resonance time;

Determine the compensation time based on the resonance time;

Update the total T _off time of the switches in the buck conversion circuit based on the compensation time;

The updated T _off time is used to generate the drive control signal of the switch to obtain the output voltage.

In some embodiments, wherein the resonance time is calculated based on the resonance frequency.

In some embodiments, the step of determining the compensation time based on the resonance time includes:

Determine whether the sign of the compensation time is positive or negative based on the resonance time;

Determine the value of the compensation time.

In some embodiments, wherein the step of determining the sign of the compensation time includes:

Determine the sign of the compensation time based on the relationship between the next switching starting point and the phase range of the inductor current generated during the resonance time;

In some embodiments, wherein the sign of the compensation time is negative when the next target switching onset point is within a first phase range of the inductor current produced during the resonance time;

The sign of the compensation time is positive when the next switching start point is within the second phase range of the inductor current produced during the resonance time.

In some embodiments, the total Toff time is equal to the target _Toff time plus the offset time.

In some embodiments, when the operating mode of the buck conversion circuit is discontinuous conduction mode (DCM), the resonance time and the compensation time are calculated, and the total number of switches in the buck conversion circuit is updated according to the compensation time. T _off time.

In some embodiments, the drive control signal is a PWM signal.

In a second aspect, a control device applied to a buck conversion circuit is provided, which device includes:

a calculation unit configured to calculate the resonance time;

a determining unit configured to determine the compensation time according to the resonance time;

An update unit, the update unit is configured to update the total T _off time of the switches in the buck conversion circuit according to the compensation time.

In a third aspect, a step-down conversion circuit is provided. The step-down conversion circuit includes:

A control device as described in the second aspect;

switching circuit;

a control unit configured to receive the input voltage and generate a drive control signal of the switching circuit by using the updated T _off time;

A step-down circuit connected to the switching circuit and configured to output a voltage.

In some embodiments, the control device is connected to a buck circuit to obtain the feedback output voltage.

In some embodiments, the input voltage is a DC voltage.

In a fourth aspect, an LED driver for driving an LED load is provided, and the LED driver includes:

a rectifier circuit connected to the step-down conversion circuit as described in the third aspect;

Wherein, the buck conversion circuit is configured to provide a substantially constant current for powering the LED load.

In a fifth aspect, a light emitting diode (LED) device is provided, the LED device including:

At least one LED lighting source;

As described in the fourth aspect, the LED driver is configured to be electrically coupled to at least one LED lighting source for driving the LED lighting source.

According to various embodiments of the present disclosure, the T _off time of the switch is corrected based on the resonance time of the output voltage and current, thereby obtaining a more accurate output current and improving load regulation.

Description of drawings

The above and other aspects, features and benefits of various embodiments of the present disclosure will become more apparent from the following detailed description, by way of example, with reference to the accompanying drawings, wherein like reference numerals or letters are used to designate similar or Equivalent components. The accompanying drawings are illustrated to facilitate a better understanding of embodiments of the present disclosure and are not necessarily to scale, in which:

Figure 1 is a diagram showing the overall structure of an LED driver;

Figure 2 is a diagram showing the relationship between output current and voltage;

Figure 3 is a block diagram showing a solution of a buck conversion circuit;

FIG. 4 is a diagram showing the structure of a conventional buck-type conversion circuit;

FIG. 5 is a schematic circuit diagram showing the structure of a conventional buck conversion circuit;

Figure 6 is a diagram showing ideal iLED current and actual iLED current under DCM;.

Figures 7 and 8 are diagrams showing DCM output current;

Figure 9 is a diagram illustrating current resonance according to an embodiment of the present disclosure;

Figure 10 is a diagram showing relationships according to an embodiment of the present disclosure;

11 is a diagram illustrating a buck conversion circuit according to an embodiment of the present disclosure;

Figure 12 is a diagram showing an example of a control solution according to an embodiment of the present disclosure;

13 is a flowchart illustrating an example of a control method according to an embodiment of the present disclosure;

14 is a diagram illustrating an example of a control method according to an embodiment of the present disclosure;

15 is a diagram showing the structure of a control device according to an embodiment of the present disclosure;

16 is a schematic circuit diagram showing the structure of a buck-type conversion circuit according to an embodiment of the present disclosure.

Detailed ways

The present disclosure will now be described with reference to several exemplary embodiments. It should be understood that these embodiments are discussed only for the purpose of enabling those skilled in the art to better understand and thus practice the disclosure, and are not intended to suggest any limitation on the scope of the disclosure.

It will be understood that when an element is referred to as being "connected" or "coupled" or "contacting" another element, it can be directly connected, coupled or contacting the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" or "directly contacting" another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a like fashion (eg, "between" versus "directly between," "adjacent" versus "directly adjacent," etc.).

As used herein, the terms "first" and "second" refer to different elements. The singular forms "a," "an" and "an" are intended to include the plural forms as well, unless the context clearly dictates otherwise. As used herein, the terms "comprises," "comprising," "having," and/or "containing" designate the presence of stated features, elements, and/or components, etc., but do not exclude the presence of one or more other features, elements, etc. , components and/or combinations thereof.

The term "based on" should be understood as "based at least in part on." The term "covering" should be understood as "at least partially covering". The terms "one embodiment" and "embodiment" should be understood to mean "at least one embodiment". The term "another embodiment" should be understood as "at least one other embodiment". Other explicit and implicit definitions may be included below.

In this disclosure, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It should further be understood that terms such as those defined in commonly used dictionaries are to be construed to have meanings consistent with their meaning in the context of the relevant art and will not be used in an idealized or overly formal manner unless expressly so defined herein. meaning explanation.

FIG. 5 is a schematic circuit diagram showing the structure of a conventional step-down conversion circuit. As shown in Figure 5, the buck conversion circuit includes an MCU, a totem pole circuit (as a Mos drive circuit), a current peak limiter circuit, and a buck circuit. Vin represents the DC input voltage detection result. Vout represents the LED output voltage detection result. Isns not administered yet. Use PWM as a Mos gate (switch) driver. Break represents a PWM circuit breaker trigger. Ref represents the current limit reference. For other parts, please refer to related technologies and will not be repeated here.

Figure 6 shows the ideal output current iLED and the actual output current iLED under DCM. As shown in Figure 6, the ideal value of the inductor current I_L is 0. Under ideal conditions, Where, T _period is the period during which the inductor current charges and discharges to 0 under DCM until the next starting point consistent with one cycle of the PWM signal. Ipk represents the peak value of the inductor current. That is, when the inductor current I_L drops to zero, there is theoretically no circuit oscillation. However, as shown in Figure 5, due to the presence of parasitic capacitors, an oscillation circuit will be formed around the parasitic capacitors, so the sinusoidal current signal will appear and disappear after multiple cycles, as shown in Use Case 1 and Use Case 2 in Figure 6.

In use case 1, the next switching starting point is negative. When actual I_L < 0 (next switching starting point B'), iLED1 < ideal iLED, T _period1 > T _period , the switch is turned to the on state; in the use case In 2, the next switching starting point is positive. When actual > 0 (next switching starting point B”), iLED2 > ideal iLED, and T _period2 < T _period , the switch is turned to the on state; therefore, in use case 1 T _{off_actual_1} and T _{off_actual_2} in use case 2 are not equal to T _{off_target} .

Figures 7 and 8 are graphs showing DCM output current at 100mA and 200mA. As shown in Figure 7 and Figure 8, as mentioned above, when the buck converter circuit is operated in DCM mode and a low current output is selected, the load regulation will be out of range.

The inventor found that the fundamental reason is that under DCM, as the buck choke coil discharges and the output current I_L approaches zero, the current begins to resonate (the above-mentioned sinusoidal current signal appears). The frequency of resonance changes with the output voltage. The next switching starting point can be positive or negative, depending on the LED load.

Therefore, in order to solve at least part of the above problems, when the operating mode of the buck conversion circuit is discontinuous conduction mode (DCM), the T _off time of the switch is corrected based on the resonance time of the output voltage and current, thereby obtaining a better Accurate output current and improved load regulation.

The first aspect of the implementation plan

This embodiment provides a step-down conversion circuit control method applied to a step-down conversion circuit. Figure 14 shows a diagram of a control method. As shown in Figure 14, the method includes:

S1, calculate the resonance time;

S2, determine the compensation time based on the resonance time;

S3, update the total Toff time of the switch in the buck conversion circuit according to the compensation time;

S4, use the updated T _off time to generate the drive control signal of the switch to obtain the output voltage.

In some embodiments, in order to obtain more accurate output current and improve load regulation, the method introduces a compensation time T _{off_comp} to offset the actual T _off time (such as T _{off_actual_1} and T _{off_actual_2} in use case 1 and use case 2 of Figure 6 ). shift.

Figure 9 also shows current resonance due to parasitic capacitors. As shown in Figure 9, T _{off_dcm} is the resonance time belonging to T _off . T_resonant is related to parameters of components such as diode parasitic capacitors and inductors.

In some embodiments, T _resonant is equal to the reciprocal of the resonant frequency, which represents the on-period (cycle) of the resonant time of the LC circuit (shown in Figure 6, capacitor C and inductor L) and when the switch is turned off , resulting in a voltage swing, which is a constant value. For example, the resonant frequency Lr represents the inductance (inductor value, the actual tolerance is +/-1%, stored in the MCU FLASH memory), Cr represents the diode parasitic capacitance, therefore,/> T _resonant can be calculated based on the feedback output voltage of the buck conversion circuit; there is a linear relationship between Cr and the feedback output voltage Vout, for example: Cr = (Vout-Vmin) × Cr _factor + Cr _offset , Vmin represents the minimum output voltage, Cr _offset can refer to the data sheet of the buck diode, Cr _factor can be determined as needed, and the present disclosure is not limited thereto.

In some embodiments, at S1 _, the resonance time T _{off_dcm} is the resonance time that falls within the target T _off time starting from the starting point of the resonance time of the LC circuit (or the time when the inductor current I_L drops to zero point), and ends at the next switching starting point, as shown in Figure 6. The target T _off time T _{off_target} is the off time of the switch (the low level time of the PWM signal) when I_L is equal to the ideal value 0, which is Starting from point A (located at the maximum I_L) to the next switching starting point B (the starting point of the next high level of the PWM signal, that is, the starting point of the next on-time T _on of the switch), where, T _{off_target} This can be obtained by looking for the table under DCM.

And T _{off_dcm} can be smaller or larger than T _resonant , for example, it can be calculated and determined by T _{off_target} . T _{off_dcm} is equal to T _{off_target} minus the time for the inductor current to drop from the maximum value to 0, that is

In some implementations, _{Toff_dcm} is the expected time that the switch should be turned off in order to control the amount of power delivered. Knowing the time period/anti-phase resonant frequency of the circuit's resonance, the timing of this off-time is adjusted to achieve zero voltage switching (or approaching zero voltage switching).

In some embodiments, at S2, the compensation time T _{off_comp} is determined based on the resonance time T _{off_dcm} ;

T _{off_comp} can be positive or negative, depending on the resonance time T _{off_dcm} . Utilize phase shift compensation for T _{off_actual_1} in use case 1 and T _{off_actual_2} in use case 2. That is, in order to calculate the resonance time, add the parameter "T _{off_comp} " that compensates the total T _off time in order to obtain a more accurate output current.

In some embodiments, step S2 includes:

S21, determine whether the sign of the compensation time is positive or negative based on the resonance time;

S22, determine the value of the compensation time.

In some embodiments, at S21, the sign of the compensation time is determined based on the relationship between the next switching starting point and the phase range of the inductor current generated during the resonance time;

In some embodiments, the sign of the compensation time is negative when the next target switching start point is within the first phase range of the inductor current generated during the resonance time; When the inductor current is within the second phase range, the sign of the compensation time is positive.

Figure 10 shows the relationship between the next switching starting point and the phase range of the inductor current produced during the resonance time. As shown in Figure 10, in phase 1 and phase 2 (the first phase range, that is, the next target switching starting point is located in phase 1 or phase 2), the sign of the compensation time T _{off_comp} can be determined to be negative, in phase 3 and phase 4 (the second phase range, ie the next target switching starting point is in phase 3 or phase 4), the sign of the compensation time T _{off_comp} can be determined to be positive.

In some embodiments, Phase 1 ranges from 180° to 270°, Phase 2 ranges from 270° to 360°, Phase 3 ranges from 0° to 90°, and Phase 4 ranges from 90° to 180°.

In some embodiments, at S2, the value of the compensation time is determined based on the value of the resonance time _{Toff_dcm} . As shown in Figure 10, when the next target switching starting point is located in phase 1 of the inductor current generated during the resonance time, the formula for the compensation time is formula A; when the next target switching starting point is located in the inductance generated during the resonance time When the next target switching starting point is in phase 3 of the inductor current generated during the resonance time, the formula for the compensation time is formula C; when the next target switching starting point is in phase 3 of the inductor current generated during the resonance time, the formula for the compensation time is formula C; When the starting point is in phase 4 of the inductor current generated during the resonance time, the formula for the compensation time is formula D.

In some embodiments, based on S21 and S22, when the next target switching starting point is located in Phase 1 of the inductor current generated during the resonance time, When the next target switching start point is in phase 2 of the inductor current produced during the resonance time, /> When the next target switching start point is in phase 3 of the inductor current produced during the resonance time, /> When the next target switching start point is in phase 4 of the inductor current produced during the resonance time,

In some embodiments, at S3, the total Toff time of the switches in the buck conversion circuit is updated according to the compensation time; for example, the total _Toff time is equal to the target _Toff time plus the compensation time.

As shown in Figure 10, in phase 1 and phase 2 (the first phase range, that is, the next target switching starting point is located in phase 1 or phase 2), T _{off_actual} =T _{off_target} -T _{off_comp} , in phase 3 and phase 4 (The second phase range, that is, the next target switching starting point is located in phase 3 or phase 4), T _{off_actual} = T _{off_target} + T _{off_comp} ; where T _{off_target} can be obtained by looking up the table under DCM, L represents the inductor (inductor) value; ΔIpk is the peak value of the current; iLED is the LED output current, and Vout represents the LED output voltage.

In some embodiments, when the operating mode of the buck conversion circuit is discontinuous conduction mode (DCM), steps S1 to S3 may be performed.

In some embodiments, the drive control signal is a PWM signal.

Figure 11 shows a diagram of a buck converter circuit of the present invention. Different from Figure 5, this circuit also includes a low-frequency operational amplifier circuit for compensating the total T _off time, and Isns represents the Rshunt average voltage detection result. Under DCM, the current of 0<Rshunt<iLED; T _{off_target} <T _period (see formula).

Figure 13 shows a flow chart of the control method. As shown in Figure 13, the method includes:

1301, check the average value of current I according to the input voltage and output voltage;

1302. Determine whether the working mode of the buck conversion circuit is CCM or DCM according to the average value of the current I; when the working mode is DCM, execute 1303 to 1306; when the working mode is CCM, execute 1307;

For example, a buck converter circuit operates in continuous current mode (CCM) where the current I through the inductor never drops to zero, and where the current I through the inductor will drop to zero over a period of time. Operates in discontinuous current mode (DCM).

1303, obtain T _{off_target} under DCM;

1304, calculate T _resonant and T _{off_dcm} ;

1305, determine the compensation time T _{off_comp} according to the resonance time (T _resonant and T _{off_dcm} );

1306, update the total T _{off_actual} of the switch according to T _{off_comp} ;

1307, T _off is obtained under CCM based on related technologies, which will not be described again here.

For the implementation of steps 1304 to 1306, please refer to S1 to S3, which will not be described again here.

1308. Use the updated T _off time to generate a drive control signal of the switch to obtain the output voltage.

In some embodiments, a low frequency operational amplifier circuit is used to check this value. The MCU is used to calculate and generate this value or signal.

T _off and T _on respectively correspond to the low level and high level time of the PWM signal. For example, the drive control signal (PWM signal) can be generated by using a proportional integral derivative (PID) loop. In some implementations, the duty cycle of the PWM can be adjusted by the PID loop based on related technologies, which will not be described again here. The PWM signal is used as a signal to drive the Mos drive circuit (as a switch).

In some embodiments, this method can be flexibly used in different products; and supports CCM/DCM performance of output power, that is, a wider operating window.

In addition, there is no peak and valley detection/capture because this is to save costs; the constant values of the resonant capacitor and resonant inductor can be stored in the MCU FLASH memory;

Knowing the resonant frequency as well as the output voltage, the method chooses to correct for the end of the off-time at DCM in order to achieve valley switching (switching at or near zero crossing).

In this embodiment, the T _off time of the switch is corrected based on the resonance time of the output voltage and current, thereby obtaining a more accurate output current and improving load regulation.

The second aspect of the implementation plan

A control device applied to a buck-type conversion circuit is provided. FIG. 15 is a diagram illustrating the structure of a control device according to an embodiment of the present disclosure. As shown in FIG. 15 , the device 1500 includes:

Calculation unit 1501, the calculation unit is configured to calculate the resonance time;

Determining unit 1502, the determining unit is configured to determine the compensation time according to the resonance time;

Update unit 1503, the update unit is configured to update the total T _off time of the switches in the buck conversion circuit according to the compensation time.

For the implementation of the calculation unit 1501, the determination unit 1502, and the update unit 1503, reference may be made to S1 to S3 described in the first aspect of the implementation, and details will not be described again here.

In some embodiments, the resonance time is the resonance time that falls within the target _Toff time.

In some embodiments, the determining unit 1502 determines whether the sign of the compensation time is positive or negative based on the resonance time, and determines the value of the compensation time.

In some embodiments, the determination unit 1502 determines the sign of the compensation time based on the relationship between the next switching starting point and the phase range of the inductor current generated during the resonance time;

In some embodiments, the sign of the compensation time is negative when the next target switching start point is within the first phase range of the inductor current produced during the resonance time; when the next target switching start point is within the first phase range of the inductor current produced during the resonance time When the current is within the second phase range of the device, the sign of the compensation time is positive.

In some embodiments, the total _Toff time is equal to the target _Toff time plus the offset time.

In some implementations, when the operating mode of the buck conversion circuit is discontinuous conduction mode (DCM), the calculation unit 1501, the determination unit 1502, and the update unit 1503 perform corresponding operations.

In some embodiments, the drive control signal is a PWM signal.

In some embodiments, the functionality of the control device 1500 described in the embodiment of the second aspect may be integrated into an MCU.

In some embodiments, the control device 1500 and the MCU may be configured separately. For example, the control device 1500 may be configured as a chip connected to an MCU to have the functions of the control device 1500 .

In this embodiment, the T _off time of the switch is corrected based on the resonance time of the output voltage and current, thereby obtaining a more accurate output current and improving load regulation.

The third aspect of the implementation plan

A step-down conversion circuit is provided. The step-down conversion circuit (see Figure 12) includes:

Control device 1601;

Switch circuit 1602;

A control unit 1603 configured to receive the input voltage and generate a drive control signal of the switching circuit by using the updated T _off time;

A buck circuit 1604 connected to the switching circuit and configured to output a voltage.

The control device 1601 is shown in the second aspect of the embodiment, and those contents that are the same as those in the second aspect of the embodiment are omitted.

In some embodiments, control device 1601 is connected to buck circuit 1604 to obtain a feedback output voltage.

In some embodiments, the input voltage is a DC voltage and the output voltage is a DC voltage. The step-down conversion circuit can be used as a DC-DC conversion circuit.

Figure 12 shows a diagram of the control scheme. As shown in Figure 12, different from Figure 3, the control device obtains the feedback output voltage and determines whether the operating mode is CCM or DCM according to the method described at 1302, when the operating mode is DCM , the control device updates the total T _off time of the switch in the buck conversion circuit according to the compensation time. The MCU (corresponding to the control unit 1603) generates the PWM signal by using the PID based on the updated total _Toff time and the DC input. The PWM signal is used as a signal to drive the Mos drive circuit (corresponding to the switch circuit 1602). The Mos driver circuit (corresponding to the switch circuit 1602) can be used as a switch in a buck conversion circuit. The buck circuit (corresponding to the buck circuit 1604) is connected to the Mos drive circuit (corresponding to the switching circuit 1602) and is configured to output a voltage. For detailed functions of other parts, please refer to related technologies and will not be described again here.

In this embodiment, the T _off time of the switch is corrected based on the resonance time of the output voltage and current, thereby obtaining a more accurate output current and improving load regulation.

The fourth aspect of the implementation plan

In an embodiment, an LED driver is provided. The LED driver includes:

A rectifier circuit connected to the step-down conversion circuit described in the third aspect;

Wherein, the buck conversion circuit is configured to provide a substantially constant current for powering the LED load.

The buck-type conversion circuit is shown in the third aspect of the embodiment, and the same contents as those in the third aspect of the embodiment are omitted.

The LED driver is electrically coupled to at least one LED lighting source for driving the LED lighting source.

As shown in Figure 1, the rectifier circuit includes an EMI filter 51 and a boost PFC circuit 52. The EMI filter 51 filters electromagnetic interference; the boost PFC circuit 52 converts the input AC power into DC power; a buck-type conversion circuit 53 configured to convert the DC voltage of the boost-type PFC circuit 52 into an output voltage for driving a lighting device, for example, the lighting device is an LED .

In some embodiments, the LED driver is configured to supply direct current (DC) power to a lighting device, which may be an LED device.

The fifth aspect of the implementation plan

In an embodiment, an LED device is provided. The LED device includes: at least one LED lighting source and an LED driver configured to be electrically coupled to the at least one LED lighting source for driving the LED lighting source. The LED device is shown in the fourth aspect of the embodiment, and those contents that are the same as those in the fourth aspect of the embodiment are omitted.

It should be understood that the above examples or embodiments are discussed for purposes of illustration and not limitation. Those skilled in the art will understand that many other embodiments or examples are possible within the scope of this disclosure. In addition, some contents of LED can refer to related technologies, and these contents will not be described again in this disclosure. It should be understood that in the second and third aspects of embodiments, some components are shown as examples only. However, it is not limited thereto, and for example, some components not mentioned may be included, and some components or elements may be omitted.

Furthermore, it is expected that one of ordinary skill will readily realize this with minimal experimentation, notwithstanding, for example, the potentially significant effort and many design choices motivated by available time, current technology, and economic considerations when guided by the concepts and principles disclosed herein. Generate such software instructions and programs and integrated circuits (ICs).

Generally speaking, the various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic components, or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software that may be executed by a controller, microprocessor, or other computing device.

Although various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representation, it is to be understood that the blocks, devices, systems, techniques, or methods described herein are, by way of non-limiting examples, May be implemented in hardware, software, firmware, special purpose circuits or logic components, general purpose hardware or controllers or other computing devices, or some combination thereof.

Additionally, although operations are shown in a particular order, this should not be construed as requiring that such operations be performed in the particular order shown or in sequential order or that all illustrated operations are required to be performed to achieve desired results. In some cases, multitasking and parallel processing may be advantageous.

Likewise, while several specific implementation details are included in the above discussion, these specific implementation details should not be construed as limitations on the scope of the disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination.

Although the present disclosure has been described in language specific to structural features and/or methodological acts, it is to be understood that the disclosure as defined by the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as exemplary forms of implementing the claims.

Claims (14)

1. A step-down conversion circuit control method applied to a step-down conversion circuit, the method comprising: Calculate resonance time; Determine the compensation time according to the resonance time; Update the total T _off time of the switches in the buck conversion circuit according to the compensation time; The updated T _off time is used to generate a drive control signal of the switch, thereby obtaining an output voltage. 2. The control method according to claim 1, wherein the resonance time is the resonance time belonging to the target T _off time. 3. The control method according to claim 1, wherein the step of determining the compensation time according to the resonance time includes: Determine whether the sign of the compensation time is positive or negative based on the resonance time; Determine the value of the compensation time. 4. The control method according to claim 3, wherein the step of determining the sign of the compensation time includes: The sign of the compensation time is determined based on the relationship between the next switching starting point and the phase range of the inductor current produced during the resonance time. 5. The control method according to claim 4, wherein the sign of the compensation time is negative when the next target switching starting point is within the first phase range of the inductor current generated during the resonance time. ; The sign of the compensation time is positive when the next switching starting point is within the second phase range of the inductor current produced during the resonance time. 6. The control method according to claim 1, wherein the total _Toff time is equal to the target _Toff time plus the compensation time. 7. The control method according to claim 1, wherein when the operating mode of the buck conversion circuit is discontinuous conduction mode DCM, the resonance time and the compensation time are calculated, and the compensation time is calculated according to the compensation time. Time updates the total T _off time of the switches in the buck conversion circuit. 8. The control method according to claim 1, wherein the drive control signal is a PWM signal. 9. A control device applied to a step-down conversion circuit, the device comprising: a calculation unit configured to calculate the resonance time; a determining unit configured to determine a compensation time according to the resonance time; An update unit, the update unit is configured to update the total T _off time of the switches in the buck conversion circuit according to the compensation time. 10. A step-down conversion circuit, the step-down conversion circuit includes: A control device according to claim 9; switching circuit; a control unit configured to receive an input voltage and generate a drive control signal of the switching circuit by using the updated T _off time; A buck circuit connected to the switching circuit and configured to output the voltage. 11. The buck conversion circuit according to claim 10, wherein the control device is connected to the buck circuit to obtain a feedback output voltage. 12. The step-down conversion circuit of claim 10, wherein the input voltage is a DC voltage. 13. An LED driver for driving an LED load, the LED driver comprising: A rectifier circuit connected to the step-down conversion circuit according to claim 10; Wherein, the step-down conversion circuit is configured to provide a substantially constant current for powering the LED load. 14. A light emitting diode (LED) device, comprising: At least one LED lighting source; 11. The LED driver of claim 11, the LED driver configured to be electrically coupled to at least one LED lighting source for driving the LED lighting source.