EP4338553A1

EP4338553A1 - Control method and apparatus of buck converting circuit, buck converting circuit, led driver and led device

Info

Publication number: EP4338553A1
Application number: EP21947824.5A
Authority: EP
Inventors: Shuanghong Wang; Jianfeng Zhang; Hai ZHENG; Jiaqi Yang
Original assignee: Tridonic GmbH and Co KG
Current assignee: Tridonic GmbH and Co KG
Priority date: 2021-06-29
Filing date: 2021-08-10
Publication date: 2024-03-20
Also published as: WO2023272886A1; CN117598029A

Abstract

A control method and apparatus of buck converting circuit, buck converting circuit, led driver and led device are provided, the control method includes calculating a resonant time; determining a compensation time according to the resonant time; updating a total T _off time of a switch in the buck converting circuit according to the compensation time; generating a drive control signal of the switch by using the updated T _off time so as to obtain an output voltage.

Description

CONTROL METHOD AND APPARATUS OF BUCK CONVERTING CIRCUIT, BUCK CONVERTING CIRCUIT, LED DRIVER AND LED DEVICE

TECHNICAL FIELD

Embodiments of the present disclosure generally relate to the field of antenna design, and more particularly, to a control method and apparatus of buck converting circuit, buck converting circuit, LED driver and LED device.

BACKGROUND

Nowadays, a light emitting diode (LED) is widely used in the field of lighting, and it usually requires constant current drive. At present, a LED driver is commonly used to provide constant drive current for LEDs.
LED driver usually uses combination of flyback or boost power factor correction (PFC) circuit followed by buck converting circuit using Digital BUCK solution by T _off control, wherein T _off is the off time of a switch in the LED driver.
Figure 1 shows a diagram which shows an overall structure of LED driver; as shown in figure 1, the LED driver 50 includes electromagnetic Interference (EMI) filter 51, boost PFC circuit 52, direct current (DC) -DC converting circuit 53 (such as buck converting circuit) . The EMI filter 51 filters the Electromagnetic Interference; the boost PFC circuit 52 converts the input AC power into DC power; a buck converting circuit 53 converts the DC voltage of the boost PFC circuit 52 into an output voltage, the output voltage is used to drive a lighting device, for example, the lighting device is LED. The detail function of other part may refer to relevant art which is omitted here, for example, a controller 54 controls the DC-DC converting circuit 53; and a control circuit 55 communicates with the controller 54. The control circuit 54 communicate with a peripheral device via an interface. For example, the peripheral devices may be dimmers, sensors, controllers, security device, etc.
Figure 2 shows the relationship between output current and Safety or Separated Extra Low Voltage (SELV) output voltage of a LED driver. As shown in figure 2, the LED driver shall provide wide output current range from 100mA to 1050mA. A buck converting circuit operates in continuous current mode (CCM) if a current I_L through an inductor never falls to zero and operates in discontinuous current mode (DCM) if a current I_L through an inductor will falls to zero during a period. In CCM, load regulation is good and sufficient. In DCM, load regulation could not fulfill demanded accuracy.
This section introduces aspects that may facilitate a better understanding of the disclosure. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.
SUMMARY
In Ulysses W2 project, it is designed with PFC plus buck SELV output. Implemented with T _off control to maintain the buck operating in CCM and DCM, in order to supply constant current output. Figure 3 shows a block diagram which shows a solution of the buck converting circuit. Figure 4 shows a diagram of the existed buck converting circuit. As shown in Figure 3 and 4, in the existed buck converting circuit, microcontroller unit (MCU) generates the Pulse Width Modulation (PWM) signal by using Proportional Integral Derivative (PID) according to the feedback voltage and DC input. The PWM signal is taken as the signal to drive the Mos drive circuit (taken as the switch) .
The inventor found that, when the buck converting circuit works in the DCM mode and chooses high current output, load regulation will be out of range.
In order to solve at least part of the above problems, methods, apparatus, devices 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 read in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of embodiments of the present disclosure.
In general, embodiments of the present disclosure provide a control method and apparatus of buck converting circuit, buck converting circuit, LED driver and LED device. It is expected to improve the load regulation.
In a first aspect, a buck converting circuit control method, applied in a buck converting circuit is provided, the method including:
calculating a resonant time;
determining a compensation time according to the resonant time;
updating a total T _off time of a switch in the buck converting circuit according to the compensation time;
generating a drive control signal of the switch by using the updated Toff time so as to obtain an output voltage.
In some embodiment, wherein the resonant time is calculated according to a resonant frequency.
In some embodiment, wherein the step of determining a compensation time according to the resonant time including:
determining a sign of the compensation time is positive or negative according to the resonant time;
determining a value of the compensation time.
In some embodiment, wherein the step of determining the sign of the compensation time including:
determining the sign of the compensation time according to a relationship of a next switching start point and a phase range of a inductor current generated during the resonant time;
In some embodiment, wherein, when a next target switching start point of is located in a first phase range of a inductor current generated during the resonant time, the sign of the compensation time is negative;
when a next switching start point of is located in a second phase range of a inductor current generated during the resonant time, the sign of the compensation time is positive.
In some embodiment, wherein the total Toff time is equal to a target T _off time plus the compensation time.
In some embodiment, wherein when a work mode of the buck converting circuit is Discontinuous Conduction Mode, DCM, calculating the resonant time and the compensation time and updating the total T _off time of a switch in the buck converting circuit according to the compensation time.
In some embodiment, wherein the drive control signal is PWM signal.
In a second aspect, a control apparatus, applied in a buck converting circuit is provided, the apparatus including:
a calculating unit configured to calculate a resonant time;
a determining unit configured to determine a compensation time according to the resonant time;
an updating unit configured to update a total T _off time of a switch in the buck converting circuit according to the compensation time.
In a third aspect, a buck converting circuit is provided, the buck converting circuit including:
a control apparatus as mentioned in the second aspect;
a switch circuit;
a control unit configured to receive an input voltage and generate a drive control signal of the switch circuit by using the updated T _off time;
a buck circuit connected to the switch circuit and configured to output the voltage.
In some embodiment, wherein the control apparatus is connected to the buck circuit to obtain the feedback output voltage.
In some embodiment, the input voltage is DC voltage.
In a fourth aspect, A LED driver, used to drive an LED load is provided, the LED driver including:
A rectifier circuit connected with a Buck converting circuit as mentioned in the third aspect;
wherein the Buck converting circuit 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 illumination source;
a LED driver as mentioned in the fourth aspect, configured to electrically couple to at least one LED illumination source for driving the LED illumination source.
According to various embodiments of the present disclosure, making a correction to the T _off time of a switch based on resonant time of the current and output voltage, so as to get more accurate output current and to improve the load regulation.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and benefits of various embodiments of the disclosure will become more fully apparent, by way of example, from the following detailed description with reference to the accompanying drawings, in which like reference numerals or letters are used to designate like or equivalent elements. The drawings are illustrated for facilitating better understanding of the embodiments of the disclosure and not necessarily drawn to scale, in which:
Fig. 1 is a diagram which shows an overall structure of LED driver;
Fig. 2 is a diagram which shows relationship between output current and voltage;
Fig. 3 is a block diagram which shows a solution of a buck converting circuit;
Fig. 4 is a diagram which show a structure of the existed buck converting circuit;
Fig. 5 is a schematic circuit diagram which show a structure of the existed buck converting circuit;
Fig. 6 is a diagram which shows the ideal and actual iLED current in DCM; .
Fig. 7 and 8 are diagrams which show DCM output current;
Fig. 9 is a diagram which shows a current resonance in accordance with an embodiment of the present disclosure;
Fig. 10 is a diagram which shows a relationship in accordance with an embodiment of the present disclosure;
Fig. 11 is a diagram which shows a buck converting circuit in accordance with an embodiment of the present disclosure;
Fig. 12 is a diagram which shows an example of the control solution in accordance with an embodiment of the present disclosure;
Fig. 13 is a flowchart which shows an example of the control method in accordance with an embodiment of the present disclosure;
Fig. 14 is a diagram which shows an example of the control method in accordance with an embodiment of the present disclosure;
Fig. 15 is a diagram which shows a structure of the control apparatus in accordance with an embodiment of the present disclosure;
Fig. 16 is a schematic circuit diagram which show a structure of the buck converting circuit in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION

The present disclosure will now be described with reference to several example embodiments. It should be understood that these embodiments are discussed only for the purpose of enabling those skilled persons in the art to better understand and thus implement the present disclosure, rather than suggesting any limitations on the scope of the present disclosure.
It should be understood that when an element is referred to as being “connected” or “coupled” or “contacted” to another element, it may be directly connected or coupled or contacted to 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 contacted” to another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “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” and “an” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises, ” “comprising, ” “has, ” “having, ” “includes” and/or “including” as used herein, specify the presence of stated features, elements, and/or components and the like, but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof.
The term “based on” is to be read as “based at least in part on” . The term “cover” is to be read as “at least in part cover” . The term “one embodiment” and “an embodiment” are to be read as “at least one embodiment” . The term “another embodiment” is to be read as “at least one other embodiment” . Other definitions, explicit and implicit, 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 will be further understood that terms, e.g., those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
Figure 5 is a schematic circuit diagram which show a structure of the existed buck converting circuit. As shown in Figure 5, the buck converting circuit includes MCU, totem pole circuit (taken as Mos drive circuit) , current peak limiter circuit and buck circuit. Vin represents DC input voltage detection. Vout represents LED output voltage detection. Isns is not applied yet. PWM is taken as Mos Gate (switch) driver. Break means PWM breaker trigger. Ref represents current limit reference. Other part may refer to relevant art which is omitted here.
Figure 6 shows the ideal and actual output current iLED current in DCM, as shown in Figure 6, the ideally value of an inductor current I_L is 0, ideally wherein T _period is a period of the inductor current in DCM charge and discharge to 0 until next start point which align one cycle of PWM signal. Ipk means peak of the inductor current. That is, when the inductor current I_L falls to zero, there exists no circuit oscillation in theory. But as shown in figure 5, as there exists parasite capacitor around which will form an oscillating circuit, a sinusoidal current signal will appear and disappear after a few cycles as shown in figure 6 case 1 and case 2.
In case 1, next switching start point is negative, switch is turned to on state when actual I_L<0 (Next switching start point B') , iLED1<ideally iLED, T _period1>T _period; In case 2, next switching start point is positive, switch is turned to on state when actual>0 (Next switching start point B”) , iLED2>ideally iLED, T _period2<T _period; so T _{off_actual_1} in case 1 and T _{off_actual_2} in case 2 are not equal to T _{off_target}.
Figure 7 and 8 are diagrams which show DCM output current in 100mA and 200mA. As shown in Figure 7 and 8, as mentioned above, when the buck converting circuit works in the DCM mode and chooses low current output, load regulation will be out of range.
The inventor found the root case is that in DCM, as buck choke discharge and output current I_L goes to zero, current starts to resonance (appear the above sinusoidal current signal) . The frequency of the resonant various with output voltage. Next switching start point could be positive or negative depends on LED load.
So in order to solve at least part of the above problems, when a work mode of the buck converting circuit is Discontinuous Conduction Mode, DCM, making a correction to the T _off time of a switch based on resonant time of the current and output voltage, so as to get more accurate output current and to improve the load regulation.
A first aspect of embodiments
A buck converting circuit control method, applied in a buck converting circuit is provided in the embodiments. Figure 14 shows a diagram of the control method, as shown in Fig. 14, the method includes:
S1, a resonant time is calculated;
S2, a compensation time is determined according to the resonant time;
S3, a total T _off time of a switch in the buck converting circuit is updated according to the compensation time;
S4, a drive control signal of the switch is generated by using the updated T _off time so as to obtain an output voltage.
In some embodiment, in order to get more accurate output current and to improve the load regulation, this method introduces a compensation time T _{off_comp} to shift the actual T _off time (such as T _{off_actual_1} and T _{off_actual_2} in case 1 and case 2 of Figure 6) .
Figure 9 further shows the current resonance generated due to the parasite capacitor. As shown in Figure 9, T _{off_dcm} is the resonant time belongs to the T _off. T_resonant related to parameters of components (such as Diode parasite capacitor, and inductor) .
In some embodiment, T _resonant is equal to reciprocal of resonant frequency, which means on period (cycle) of resonant time of LC circuit (as shown in figure 6, capacitor C and inductor L) and leads to the voltage swinging when the switch is being switched off, it is a constant value. For example, resonant frequency Lr means Inductance (inductor value, actual tolerance is +/-1%, stored inside the MCU FLASH memory) , Cr means Diode parasite Capacitance, so T _resonant can be calculated according to a feedback output voltage of the buck converting circuit; there exists a linear relationship between the Cr and the feedback output voltage Vout, for example: Cr= (Vout-Vmin) ×Cr _factor+Cr _offset, Vmin means minimum output voltage the Cr _offset could be refer from datasheet of Buck Diode, Cr _factor could be determined on demand and this disclosure is not limited thereto..
In some embodiment, in S1, a resonant time T _{off_dcm} is the resonant time belongs to a target T _off time started from the start point of the resonant time of LC circuit (or the time point when the inductor current I_L falls to zero) and is ended to the next switching start point, as shown in figure 6, the target T _off time T _{off_target} is the off time of the switch (time of low level of the PWM signal) when I_L is equal to ideally value 0, which is started from point A (located at maximum I_L) to the Next switching start point B (start point of the next high level of the PWM signal, that is, start point of next T _on which is on time of the switch) wherein T _{off_target} can be obtained by looking up table in DCM.
And T _{off_dcm} could be less or larger than T _resonant, for examples, it determined by T _{off_target} could be calculated. T _{off_dcm} is equal to the T _{off_target} minus the time for the inductor current to fall from the maximum value to 0, that is,
In some embodiment, T _{off_dcm} is the intended time that the switch should be switched off in order to control the amount of power transferred. The timing of this off-time is adjusted in order to achieve zero voltage switching (or be close to zero voltage switching) in knowledge of the time period /inverted resonant frequency of the resonance of the circuit.
In some embodiment, in S2, a compensation time T _{off_comp} is determined according to the resonant time T _{off_dcm};
T _{off_comp} could be positive value or negative value, depends on the resonant time T _{off_dcm}. Using phase shift to compensate theT _{off_actual_1} in case 1 and T _{off_actual_2} in case2. That is, To calculate Resonant time, Add parameter “T _{off_comp}” for compensation the total T _off time, in order to get more accurate output current.
In some embodiment, wherein the step of S2 including:
S21, a sign of the compensation time is determined as positive or negative according to the resonant time;
S22, a value of the compensation time is determined.
In some embodiment, in S21, it determines the sign of the compensation time according to a relationship of a next switching start point and a phase range of a inductor current generated during the resonant time;
In some embodiment, wherein, when a next target switching start point of is located in a first phase range of a inductor current generated during the resonant time, the sign of the compensation time is negative; when a next switching start point of is located in a second phase range of a inductor current generated during the resonant time, the sign of the compensation time is positive.
Figure 10 shows the relationship of a next switching start point and a phase range of a inductor current generated during the resonant time . As shown in figure 10, in phase 1 and 2 (first phase range, that is, a next target switching start point of is located in a phase 1 or phase 2) , the sign of the compensation time T _{off_comp} can be determined as negative, In phase 3 and 4 (second phase range, that is, a next target switching start point of is located in a phase 3 or phase 4) , the sign of the compensation time T _{off_comp} can be determined as positive.
In some embodiment, the range of phase 1 is 180°～270°, the range of phase 2 is 270°～360°, the range of phase 3 is 0°～90°, the range of phase 4 is 90°～180°.
In some embodiment, in S2, value of the compensation time is determined according the value of resonant time T _{off_dcm.} As shown in figure 10, when a next target switching start point of is located in phase 1 of a inductor current generated during the resonant time, the formula of the compensation time is formula A; when a next target switching start point of is located in phase 2 of a inductor current generated during the resonant time, the formula of the compensation time is formula B;when a next target switching start point of is located in phase 3 of a inductor current generated during the resonant time, the formula of the compensation time is formula C; when a next target switching start point of is located in phase 4 of a inductor current generated during the resonant time, the formula of the compensation time is formula D.
In some embodiment, based on S21 and S22, when a next target switching start point of is located in phase 1 of a inductor current generated during the resonant time, when a next target switching start point of is located in phase 2 of a inductor current generated during the resonant time, when a next target switching start point of is located in phase 3 of a inductor current generated during the resonant time, when a next target switching start point of is located in phase 4 of a inductor current generated during the resonant time,
In some embodiment, in S3, a total T _off time of a switch in the buck converting circuit is updated according to the compensation time; for example, the total T _off time is equal to a target T _off time plus the compensation time.
As shown in figure 10, in phase 1 and 2 (first phase range, that is, a next target switching start point of is located in a phase 1 or phase 2) , T _{off_actual}=T _{off_target}-T _{off_comp}, In phase 3 and 4 (second phase range, that is, a next target switching start point of is located in a phase 3 or phase 4) , T _{off_actual}=T _{off_target}+T _{off_comp}; wherein, T _{off_target} can be obtained by looking up table in DCM, L represents the value of the Inductor (inductance) ; ΔIpk is the peak of the current; iLED is LED output current, Vout represents LED output voltage.
In some embodiment, wherein when a work mode of the buck converting circuit is Discontinuous Conduction Mode, DCM, step S1-S3 can be performed.
In some embodiment, wherein the drive control signal is PWM signal.
Figure 11 shows a diagram of the buck converting circuit of the present invention. It is different from Figure 5, the circuit further includes Low frequency op-amp circuit which is used for compensation the total T _off time, and Isns represents the Rshunt mean voltage detection. In DCM, 0< the current of Rshunt < iLED; T _{off_target}< T _period (see formulas) .
Figure 13 shows a flowchart of the control method, as shown in Fig. 13, the method includes:
1301, the mean of current I is checked according to the input voltage and output voltage;
1302, the work mode of the buck converting circuit is CCM or DCM is determined according to the mean of current I; when the work mode is DCM, performing 1303-1306, when the work mode is CCM, performing 1307;
For example, the buck converting circuit operates in continuous current mode (CCM) if a current I through an inductor never falls to zero and operates in discontinuous current mode (DCM) if a current I through an inductor will falls to zero during a period.
1303, T _{off_target} is obtained in DCM;
1304, T _resonant and T _{off_dcm} are calculated;
1305, a compensation time T _{off_comp} is determined according to the resonant time (T _resonant and T _{off_dcm}) ;
1306, a total T _{off_actual} of a switch is updated according to the T _{off_comp};
1307, T _off is obtained in CCM based on the relevant art which is omitted here.
the implement of 1304-1306 may refer to S1-S3 which is omitted here.
1308, a drive control signal of the switch is generated by using the updated T _off time so as to obtain an output voltage.
In some embodiment, Low frequency op-amp circuit is used to check the value. MCU is used to calculate and generate the value or signal.
T _off and T _on correspond to the time of low level and high level of the PWM signal respectively. For example, the drive control signal (PWM signal) can be generated by using proportional integral derivative (PID) loop. In some embodiment, duty cycle of the PWM can be adjusted by the PID loop based on the relevant art which is omitted here, the PWM signal is taken as the signal to drive the Mos drive circuit (taken as the switch) .
In some embodiment, this method can be flexible usage in different products; and support CCM/DCM performance –wider operation window for output power.
Furthermore, no valley detection/capture because in order to save the cost; The constant value of resonant capacitor and resonant inductance can be stored inside the MCU FLASH memory;
In knowledge of the resonant frequency as well as the output voltage the method selects a correction for the end of the off-time in DCM in order to achieve valley switching (switching at or close to the zero crossings) .
In this embodiment, making a correction to the T _off time of a switch based on resonant time of the current and output voltage, so as to get more accurate output current and to improve the load regulation.
A second aspect of embodiments
A control apparatus, applied in a buck converting circuit is provided, Fig. 15 is a diagram which shows a structure of the control apparatus in accordance with an embodiment of the present disclosure, As shown in figure 15, the apparatus 1500 including:
a calculating unit 1501, configured to calculate a resonant time;
a determining unit 1502, configured to determine a compensation time according to the resonant time;
an updating unit 1503, configured to update a total T _off time of a switch in the buck converting circuit according to the compensation time.
The implement of the calculating unit 1501, determining unit 1502, updating unit 1503 may refer to S1-S3 mentioned in the first aspect of embodiment which is omitted here.
In some embodiment, the resonant time is the resonant time belongs to a target T _off time.
In some embodiment, the determining unit 1502 determines a sign of the compensation time is positive or negative according to the resonant time and determines a value of the compensation time.
In some embodiment, the determining unit 1502 determines the sign of the compensation time according to a relationship of a next switching start point and a phase range of a inductor current generated during the resonant time;
In some embodiment, when a next target switching start point of is located in a first phase range of a inductor current generated during the resonant time, the sign of the compensation time is negative; when a next switching start point of is located in a second phase range of a inductor current generated during the resonant time, the sign of the compensation time is positive.
In some embodiment, wherein the total T _off time is equal to a target T _off time plus the compensation time.
In some embodiment, wherein when a work mode of the buck converting circuit is Discontinuous Conduction Mode, DCM, calculating unit 1501, determining unit 1502, updating unit 1503 perform the corresponding behavior.
In some embodiment, the drive control signal is PWM signal.
In some embodiment, the functions of the control apparatus 1500 described in the embodiment of the second aspect may be integrated into the MCU.
In some embodiment, the control apparatus 1500 and the MCU may be configured separately. For example, the control apparatus 1500 may be configured as a chip connected to the MCU, with the functions of the control apparatus 1500.
In this embodiment, making a correction to the T _off time of a switch based on resonant time of the current and output voltage, so as to get more accurate output current and to improve the load regulation.
A third aspect of embodiments
A buck converting circuit is provided, the buck converting circuit (refer to figure 12) including:
a control apparatus 1601;
a switch circuit 1602;
a control unit 1603 configured to receive an input voltage and generate a drive control signal of the switch circuit by using the updated T _off time;
a buck circuit 1604 connected to the switch circuit and configured to output the voltage.
The control apparatus 1601 is illustrated in the second aspect of embodiments, and the same contents as those in the second aspect of embodiments are omitted.
In some embodiment, the control apparatus 1601 is connected to the buck circuit 1604 to obtain the feedback output voltage.
In some embodiment, the input voltage is DC voltage, the output voltage is DC voltage. The buck converting circuit can be taken as DC-DC converting circuit.
Figure 12 shows a diagram of the control solution, as shown in Fig. 12, different from figure 3, the control apparatus obtains the feedback output voltage and determines the work mode is CCM or DCM based on the method mentioned in 1302, when the work mode is DCM, control apparatus updates a total T _off time of a switch in the buck converting circuit according to the compensation time. MCU (corresponding to control unit 1603) generates the PWM signal by using PID according to the updated total T _off time and DC input. The PWM signal is taken as the signal to drive the Mos drive circuit (corresponding to a switch circuit 1602) . The Mos drive circuit (corresponding to a switch circuit 1602) can be taken as the switch in the buck converting circuit. The buck circuit (corresponding to a buck circuit 1604) connected to the Mos drive circuit (corresponding to a switch circuit 1602) and configured to output the voltage. The detail function of other part may refer to relevant art which is omitted here.
In this embodiment, making a correction to the T _off time of a switch based on resonant time of the current and output voltage, so as to get more accurate output current and to improve the load regulation.
A fourth aspect of embodiments
A LED driver is provided in the embodiments. The LED driver includes:
A rectifier circuit connected with a Buck converting circuit mentioned in the third aspect;
wherein the Buck converting circuit configured to provide a substantially constant current for powering the LED load.
The buck converting circuit is illustrated in the third aspect of embodiments, and the same contents as those in the third aspect of embodiments are omitted.
The LED driver is electrically couple to at least one LED illumination source for driving the LED illumination source.
As shown in figure 1, rectifier circuit includes an EMI filter 51 and a boost PFC circuit 52, the EMI filter 51 filters the Electromagnetic Interference; the boost PFC circuit 52, converts the input AC power into DC power; a Buck converting circuit 53, configured to convert the DC voltage of the boost PFC circuit 52 into an output voltage, the output voltage is used to drive a lighting device, for example, the lighting device is LED.
In some embodiment, the LED driver configured to supply direct current (DC) power to the lighting device, the lighting device may be an LED device.
A fifth aspect of embodiments
A LED device is provided in the embodiments. The LED device includes: at least one LED illumination source and a LED driver configured to electrically couple to at least one LED illumination source for driving the LED illumination source. The LED driver is illustrated in the fourth aspect of embodiments, and the same contents as those in the fourth aspect of embodiments are omitted.
It is to be understood that, the above examples or embodiments are discussed for illustration, rather than limitation. Those skilled in the art would appreciate that there may be many other embodiments or examples within the scope of the present disclosure. Furthermore, some contents of LED may be referred to relevant art, and these are omitted in this disclosure. It should be appreciated that some components are illustrated only as examples in the second and third aspect of embodiments. However, it is not limited thereto, for example, some components not mentioned may be included, some components or elements may be omitted.
Further, it is expected that one of ordinary skill, notwithstanding possibly significant effort and many design choices motivated by, for example, available time, current technology, and economic considerations, when guided by the concepts and principles disclosed herein will be readily capable of generating such software instructions and programs and integrated circuits (ICs) with minimal experimentation.
Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device.
While various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representation, it will be appreciated that the blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.
Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous.
Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination.
Although the present disclosure has been described in language specific to structural features and/or methodological acts, it is to be understood that the present disclosure defined in 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 example forms of implementing the claims.

Claims

A buck converting circuit control method, applied in a buck converting circuit, the method comprising:

calculating a resonant time;

determining a compensation time according to the resonant time;

updating a total T _off time of a switch in the buck converting circuit according to the compensation time;

generating a drive control signal of the switch by using the updated T _off time so as to obtain an output voltage.
The control method according to claim 1, wherein the resonant time is the resonant time belongs to a target T _off time.
The control method according to claim 1, wherein the step of determining a compensation time according to the resonant time comprising:

determining a sign of the compensation time is positive or negative according to the resonant time;

determining a value of the compensation time.
The control method according to claim 3, wherein the step of determining the sign of the compensation time comprising:

determining the sign of the compensation time according to a relationship of a next switching start point and a phase range of a inductor current generated during the resonant time.
The control method according to claim 4, wherein, when a next target switching start point of is located in a first phase range of a inductor current generated during the resonant time, the sign of the compensation time is negative;

when a next switching start point of is located in a second phase range of a inductor current generated during the resonant time, the sign of the compensation time is positive.
The control method according to claim 1, wherein the total T _off time is equal to a target T _off time plus the compensation time.
The control method according to claim 1, wherein when a work mode of the buck converting circuit is Discontinuous Conduction Mode, DCM, calculating the resonant time and the compensation time and updating the total T _off time of a switch in the buck converting circuit according to the compensation time.
The control method according to claim 1, wherein the drive control signal is PWM signal.
A control apparatus, applied in a buck converting circuit, the apparatus comprising:

a calculating unit configured to calculate a resonant time;

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

an updating unit configured to update a total T _off time of a switch in the buck converting circuit according to the compensation time.
A buck converting circuit, comprising:

a control apparatus as claimed in claim 9;

a switch circuit;

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

a buck circuit connected to the switch circuit and configured to output the voltage.
The buck converting circuit according to claim 10, wherein the control apparatus is connected to the buck circuit to obtain the feedback output voltage.
The buck converting circuit according to claim 10, the input voltage is DC voltage.
A LED driver, used to drive an LED load, comprising:

A rectifier circuit connected with a Buck converting circuit as claimed in claim 10;

wherein the Buck converting circuit configured to provide a substantially constant current for powering the LED load.
A light emitting diode (LED) device, comprising:

at least one LED illumination source;

a LED driver as claimed in claim 11, configured to electrically couple to at least one LED illumination source for driving the LED illumination source.