CN113630933A

CN113630933A - LED driver, driving circuit and driving method

Info

Publication number: CN113630933A
Application number: CN202111101328.9A
Authority: CN
Inventors: 陈鸣; 关彦青; 文星; 薛连杰
Original assignee: Shanghai Sansi Technology Co Ltd; Shanghai Sansi Electronic Engineering Co Ltd; Jiashan Sansi Photoelectric Technology Co Ltd; Pujiang Sansi Optoelectronics Technology Co Ltd
Current assignee: Shanghai Sansi Technology Co Ltd; Shanghai Sansi Electronic Engineering Co Ltd; Jiashan Sansi Photoelectric Technology Co Ltd; Pujiang Sansi Optoelectronics Technology Co Ltd
Priority date: 2021-09-18
Filing date: 2021-09-18
Publication date: 2021-11-09
Anticipated expiration: 2041-09-18
Also published as: CN113630933B

Abstract

The application relates to the field of integrated circuit design and discloses an LED driver, a driving circuit and a driving method. The circuit of the application comprises: the anode of the first of the N series lamp sections of the LED lamp string is connected with the voltage conversion module; the reference voltage signal generation module is connected with the voltage conversion module, the constant current driving module is connected with the reference voltage signal generation module, N output ends of the constant current driving module correspond to the N series-connected lamp sections one by one, and each output end is connected to the cathode of the corresponding lamp section; the voltage conversion module is used for converting the input voltage signal into a driving voltage signal; the reference voltage signal generating module is used for correspondingly generating a reference voltage signal forming a driving current signal according to the driving voltage signal; the constant current driving module is used for generating driving current signals according to the reference voltage signals and inputting the driving current signals to the corresponding lamp segments so as to control the N lamp segments to be sequentially switched on or switched off. The driving circuit achieves high power factor and simultaneously has low total harmonic distortion.

Description

LED driver, driving circuit and driving method

Technical Field

The present application relates to the field of integrated circuit design, and in particular, to an LED driver, a driving circuit, and a driving method.

Background

The LED lighting is increasingly widely applied as a green and environment-friendly new generation lighting technology, and because the LED needs to keep the stability of the driving current during working, the driving of the LED is an important link in the LED lighting technology. In the existing LED lighting driving technology, a switching power supply technology adopting constant current output is a widely applied driving technology, and a well-designed switching power supply driving circuit can provide stable driving current for an LED and can provide a convenient control function. With the progress of circuit technology, devices and packaging, the switching power supply driving circuit, especially the low-power driving circuit, is also made to be more compact.

In recent years, as an alternative driving scheme, linear driving circuits are beginning to be more and more widely used. Different from a switching power supply circuit, the linear driving circuit directly drives the LED by a low-voltage difference constant current source circuit composed of an operational amplifier and a transistor, and devices such as a power switch, an inductor and a capacitor used in the switching power supply are omitted. In addition, because the high-frequency switch is not arranged in the driving circuit, the electromagnetic interference problem of the driving circuit and related components can be omitted, so that the whole driving circuit scheme is very simplified, the cost is greatly reduced, and the service life of the driving circuit is greatly prolonged. Although the linear driving circuit is inferior to the switching power supply circuit in terms of driving efficiency, working voltage range, strict matching requirement on input and output voltages, etc., the linear driving circuit still has great attractiveness in some applications due to its simplified circuit structure and cost advantage. However, the current linear driving circuit cannot achieve a high Power Factor (PF) and also has a high Total Harmonic Distortion (THD).

Disclosure of Invention

The application aims to provide an LED driver, a driving circuit and a driving method.

To solve the above technical problem, a first aspect of the present application provides an LED driving circuit, including: the LED lamp comprises a voltage conversion module, an LED lamp string, a reference voltage signal generation module and a constant current driving module; the LED lamp string comprises N LED lamp sections which are connected in series, and the anode of the first LED lamp section is connected with the output end of the voltage conversion module; the input end of the reference voltage signal generation module is connected with the output end of the voltage conversion module, the input end of the constant current driving module is connected with the output end of the reference voltage signal generation module, N driving output ends of the constant current driving module correspond to N LED lamp sections one by one, and each driving output end is connected to the cathode of the corresponding LED lamp section; the voltage conversion module is used for converting an input voltage signal into a driving voltage signal; the reference voltage signal generating module is used for correspondingly generating a reference voltage signal forming a driving current signal according to the driving voltage signal; the constant current driving module is used for generating driving current signals of the LED lamp sections according to the reference voltage signals and inputting the driving current signals to the corresponding LED lamp sections so as to control the N LED lamp sections to be sequentially switched on or switched off.

A second aspect of the present application provides an LED driver including the above LED driving circuit.

A third aspect of the present application provides an LED driving method applied to an LED driving circuit including: the LED lamp comprises a voltage conversion module, an LED lamp string, a reference voltage signal generation module and a constant current driving module; the LED lamp string comprises N LED lamp sections which are connected in series, and the anode of the first LED lamp section is connected with the output end of the voltage conversion module; the input end of the reference voltage signal generation module is connected with the output end of the voltage conversion module, the input end of the constant current driving module is connected with the output end of the reference voltage signal generation module, N driving output ends of the constant current driving module correspond to N LED lamp sections one by one, and each driving output end is connected to the cathode of the corresponding LED lamp section; the LED driving method comprises the following steps: the voltage conversion module converts an input voltage signal into a driving voltage signal; the reference voltage signal generating module correspondingly generates a reference voltage signal forming a driving current signal according to the driving voltage signal; the constant current driving module generates driving current signals of the LED lamp sections according to the reference voltage signals and inputs the driving current signals to the corresponding LED lamp sections so as to control the N LED lamp sections to be sequentially switched on or switched off.

In an embodiment of the first aspect, the driving current signals of N of said LED segments are combined to form a half sine wave current signal.

In an embodiment of the first aspect, the driving voltage signal and the reference voltage signal are both half sine wave voltage signals, and the frequencies of the driving voltage signal and the reference voltage signal are the same.

In an embodiment of the first aspect, the reference voltage signal generating module includes an input voltage sampling circuit, a reference voltage generating circuit, and a reference voltage signal generating circuit, which are connected in sequence, wherein an input end of the input voltage sampling circuit is connected to an output end of the voltage converting module, and the reference voltage signal generating circuit is connected to an input end of the constant current driving module; the input voltage sampling circuit is used for acquiring the peak voltage of the partial voltage input signal according to the partial voltage input signal of the driving voltage signal; the reference voltage generating circuit is used for generating a reference voltage which is inversely proportional to the peak voltage; the reference voltage signal generating circuit is used for generating the reference voltage signal according to the reference voltage and the divided voltage input signal.

In an embodiment of the first aspect, the lighting device further includes a dimming control circuit, an input end of the dimming control circuit is connected to an output end of the reference voltage generation circuit, an output end of the dimming control circuit is connected to an input end of the reference voltage signal generation circuit, and the dimming control circuit is configured to control on/off of the reference voltage generated by the reference voltage generation circuit to the reference voltage signal generation circuit.

In an embodiment of the first aspect, the constant current driving circuit further includes a sampling resistor, one end of the sampling resistor is connected to the output end of the constant current driving module, and the other end of the sampling resistor is grounded.

In an embodiment of the first aspect, the voltage reference circuit further includes a compensation capacitor, one end of the compensation capacitor is connected to the input end of the reference voltage signal generation circuit, and the other end of the compensation capacitor is grounded.

In an embodiment of the first aspect, the voltage conversion module further includes a filter capacitor, a first end of the filter capacitor is connected to the output positive terminal of the voltage conversion module, and a second end of the filter capacitor is connected to the output negative terminal of the voltage conversion module and grounded.

In an embodiment of the first aspect, the constant current driving module includes a reference voltage signal switching circuit and a multi-stage constant current driving circuit, where the multi-stage constant current driving circuit includes N constant current driving units, and N output terminals of the N constant current driving units form N driving output terminals of the constant current driving module;

the input end of the reference voltage signal switching circuit is connected with the output end of the reference voltage signal generating circuit, the reference voltage signal switching circuit comprises N segmented reference voltage output ends, and the N segmented reference voltage output ends are respectively connected with the N input ends of the multi-segment constant current driving circuit in a one-to-one correspondence manner; the reference voltage signal switching circuit is used for providing N reference driving voltage signals according to the reference voltage signals;

the multi-section constant current driving circuit is used for generating driving current signals of the LED lamp sections according to the N reference driving voltage signals and inputting the driving current signals to the corresponding LED lamp sections so as to control the N LED lamp sections to be sequentially switched on or switched off.

In an embodiment of the first aspect, the reference voltage signal switching circuit includes a voltage buffer and a switch network, an input end of the voltage buffer is connected to an output end of the reference voltage signal generating circuit, the voltage buffer includes 3 segmented voltage output ends, 3 segmented voltage output ends are connected to 3 segmented voltage input ends of the switch network in a one-to-one correspondence manner, and N voltage output ends of the switch network are connected to N input ends of the multi-segment constant current driving circuit in a one-to-one correspondence manner; the voltage buffer is used for generating 3 segmented voltage signals according to the reference voltage signal, wherein the 3 segmented voltage signals at least comprise a first segmented voltage signal which is the same as the reference voltage signal and a voltage difference value between two adjacent segmented voltage signals at the same moment is a preset offset voltage value; the switch network is used for switchably distributing the 3 segmented voltage signals to the N voltage output ends of the switch network according to a distribution instruction sent by the multi-segment constant current driving circuit.

In an embodiment of the third aspect, the driving current signals of N of said LED segments are combined to form a half sine wave current signal.

In an embodiment of the third aspect, the driving voltage signal and the reference voltage signal are both half sine wave voltage signals, the driving voltage signal and the reference voltage signal have the same frequency, and the driving voltage signal and the reference voltage signal have different amplitudes.

In an embodiment of the third aspect, the constant current driving module comprises a reference voltage signal switching circuit and a multi-stage constant current driving circuit, wherein the reference voltage signal switching circuit comprises a voltage buffer and a switch network; the constant current driving module generates a driving current signal of each LED lamp section according to the reference voltage signal, and inputs each driving current signal to a corresponding LED lamp section to control N LED lamp sections to be sequentially turned on or off, and specifically includes:

the voltage buffer acquires 3 segmented voltage signals according to the reference voltage signal, wherein the 3 segmented voltage signals at least comprise a first segmented voltage signal which is the same as the reference voltage signal and a voltage difference value between two adjacent segmented voltage signals at the same moment is a preset bias voltage value;

the switch network switchably distributes the 3 segmented voltage signals to N voltage output ends of the switch network according to a distribution instruction of the multi-segment constant current driving circuit to form N reference driving voltage signals;

the multi-section constant current driving circuit generates driving current signals of the LED lamp sections according to the N reference driving voltage signals and inputs the driving current signals to the corresponding LED lamp sections so as to control the N LED lamp sections to be sequentially switched on or switched off.

The reference voltage which is generated by the driving circuit and is inversely proportional to the input voltage guarantees that the input power can be kept stable and unchanged when the input voltage changes, and the average value generated by the reference voltage signal is equal to the reference voltage, so that the input driving current signal is guaranteed to change along with the reference voltage signal, and the input current of the whole alternating current period is guaranteed to change along with the input voltage, so that the driving circuit achieves a higher power factor and has lower total harmonic distortion.

Drawings

Fig. 1 is a schematic structural diagram of an LED driving circuit according to a first embodiment of the present application;

fig. 2 is a schematic structural diagram of an LED driving circuit according to a second embodiment of the present application;

fig. 3 shows a schematic structure diagram of an LED driving circuit including a dimming control circuit according to a second embodiment of the present application;

fig. 4 is a schematic structural diagram of an LED driving circuit according to a third embodiment of the present application;

FIG. 5 shows waveforms of a divided input signal and a DC voltage signal according to a third embodiment of the present application;

FIG. 6 shows waveforms of a divided input signal, a reference voltage signal and an average reference voltage signal according to a third embodiment of the present application;

FIG. 7 shows waveforms of the respective voltage-current signals and the distribution command signal during the whole AC cycle according to the third embodiment of the present application;

fig. 8 is a flowchart illustrating an LED driving method according to a fifth embodiment of the present application.

Detailed Description

The embodiments of the present application are described below with specific examples, and other advantages and effects of the present application will be readily apparent to those skilled in the art from the disclosure of the present application. The present application is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present application. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.

Embodiments of the present application will be described in detail below with reference to the accompanying drawings so that those skilled in the art to which the present application pertains can easily carry out the present application. The present application may be embodied in many different forms and is not limited to the embodiments described herein.

In order to clearly explain the present application, components that are not related to the description are omitted, and the same reference numerals are given to the same or similar components throughout the specification.

Throughout the specification, when a device is referred to as being "connected" to another device, this includes not only the case of being "directly connected" but also the case of being "indirectly connected" with another element interposed therebetween. In addition, when a device "includes" a certain component, unless otherwise stated, the device does not exclude other components, but may include other components.

When a device is said to be "on" another device, this may be directly on the other device, but may also be accompanied by other devices in between. When a device is said to be "directly on" another device, there are no other devices in between.

Although the terms first, second, etc. may be used herein to describe various elements in some instances, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, the first interface and the second interface, etc. are described. Also, as used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes" and/or "including," when used in this specification, specify the presence of stated features, steps, operations, elements, components, items, species, and/or groups, but do not preclude the presence, or addition of one or more other features, steps, operations, elements, components, species, and/or groups thereof. The terms "or" and/or "as used herein are to be construed as inclusive or meaning any one or any combination. Thus, "A, B or C" or "A, B and/or C" means "any of the following: a; b; c; a and B; a and C; b and C; A. b and C ". An exception to this definition will occur only when a combination of elements, functions, steps or operations are inherently mutually exclusive in some way.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the singular forms "a", "an" and "the" include plural forms as long as the words do not expressly indicate a contrary meaning. The term "comprises/comprising" when used in this specification is taken to specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but does not exclude the presence or addition of other features, regions, integers, steps, operations, elements, and/or components.

Terms representing relative spatial terms such as "lower", "upper", and the like may be used to more readily describe one element's relationship to another element as illustrated in the figures. Such terms are intended to include not only the meanings indicated in the drawings, but also other meanings or operations of the device in use. For example, if the device in the figures is turned over, elements described as "below" other elements would then be oriented "above" the other elements. Thus, the exemplary terms "under" and "beneath" all include above and below. The device may be rotated 90 or other angles and the terminology representing relative space is also to be interpreted accordingly. In addition, in the present application, any circuit parameter initials in upper and lower case represent the same variable, and there is no distinction meaning, for example, Vref and Vref indicate the same physical variable, and there is no distinction.

Although not defined differently, including technical and scientific terms used herein, all terms have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Terms defined in commonly used dictionaries are to be additionally interpreted as having meanings consistent with those of related art documents and the contents of the present prompts, and must not be excessively interpreted as having ideal or very formulaic meanings unless defined.

A first embodiment of the present application relates to an LED driving circuit. As shown in fig. 1, the LED driving circuit includes a voltage conversion module 100, a reference voltage signal generation module 200, a constant current driving module 300, and an LED string 400. The output end of the voltage conversion module 100 is connected to the input end of the reference voltage signal generation module 200, and the output end of the reference voltage signal generation module 200 is connected to the input end of the constant current driving module 300. The LED light string 400 includes N LED segments (segment 401, segment 402 …, segment 40N) connected in series, and the anode of the first LED segment 401 is connected to the output terminal of the voltage conversion module 100. The constant current driving module 300 includes N driving output terminals (out1-out N), where the N driving output terminals correspond to the N LED segments connected in series one by one, and each driving output terminal is connected to a cathode of the corresponding LED segment.

The voltage conversion module 100 is configured to convert an input voltage signal AC into a driving voltage signal vbulk, where one driving voltage signal vbulk provides a working voltage for the LED lamp string 400, the other driving voltage signal vbulk is loaded to the reference voltage signal generation module 200, the reference voltage signal generation module 200 generates a reference voltage signal vref _ cs according to the driving voltage signal vbulk, the constant current driving module 300 generates a corresponding driving current signal (iout1-ioutn) for driving each LED lamp segment (the lamp segment 401 and the lamp segment 402 … lamp segment 40N) according to the reference voltage signal vref _ cs, and inputs each driving current signal (iout1-ioutn) to the corresponding LED lamp segment through the N driving output ends to control the N LED lamp segments to be sequentially turned on or off.

Specifically, in the preferred embodiment shown in fig. 1, the input voltage signal is an ac power supply, the reference voltage signal generating module 200 samples the driving voltage signal vbulk, generates a reference voltage inversely proportional to the input voltage according to the driving voltage signal vbulk, and then generates a reference voltage signal vref _ cs with an average value equal to the reference voltage, for outputting to the constant current driving module 300 to generate each driving current signal (iout1-ioutn) corresponding to the driving voltage signal vref _ cs. And each driving current signal is input to the corresponding LED lamp section, so that the N LED lamp sections are controlled to be sequentially switched on or switched off, wherein the driving current signals of the N LED lamp sections are combined to form a half sine wave current signal.

The reference voltage which is generated by the reference voltage signal generation module 200 and is inversely proportional to the input voltage ensures that the input power can be kept stable and unchanged when the input voltage changes, and the reference voltage signal vref _ cs which is generated by the reference voltage signal generation module and has the average value equal to the reference voltage ensures that the driving current signal changes along with the reference voltage signal vref _ cs, so that the input current in the whole alternating current period changes along with the input voltage, the driving circuit achieves a higher power factor, and meanwhile, the total harmonic distortion is lower. In the preferred embodiment, the reference voltage signal generating module 200 may generate a reference voltage inversely proportional to the input voltage through a dividing circuit, and then generate a reference voltage signal vref _ cs having an average value equal to the reference voltage through a negative feedback loop formed by a multiplying circuit and a transconductance amplifier, but it is understood that the above implementation manner is merely illustrative.

A second embodiment of the present application relates to an LED driving circuit. The second embodiment is a further improvement on the first embodiment, and the main improvement is that in this embodiment, an implementation manner of the reference voltage signal generation module 200 and the constant current driving module 300 is specifically provided, and as shown in fig. 2, the reference voltage signal generation module 200 further includes an input voltage sampling circuit 201, a reference voltage generation circuit 202, and a reference voltage signal generation circuit 203. An input of the input voltage sampling circuit 201 forms an input of the reference voltage signal generation module 200 and an output of the reference voltage signal generation circuit 203 forms an output of the reference voltage signal generation module 200. The constant current driving module 300 further includes a reference voltage signal switching circuit 301 and a multi-stage constant current driving circuit 302. The input end of the reference voltage signal switching circuit 301 forms the input end of the constant current driving module 300, and the output end of the multi-stage constant current driving circuit 302 forms the output end of the constant current driving module 300.

The input end of the input voltage sampling circuit 201 is connected to the output end of the voltage conversion module 100, the input voltage sampling circuit 201, the reference voltage generating circuit 202, and the reference voltage signal generating circuit 203 are sequentially connected, and the output end of the reference voltage signal generating circuit 203 is connected to the input end of the reference voltage signal switching circuit 301 of the constant current driving module 300. The output end of the reference voltage signal switching circuit 301 is connected to the input end of the multi-stage constant current driving circuit 302.

The input voltage sampling circuit 201 samples a divided input signal of the input driving voltage signal vbulk and generates a dc voltage proportional to the divided input signal to determine the magnitude of the input signal. Specifically, the input voltage sampling circuit 201 may sample the divided input signal to obtain an average value of the divided input signal, or may obtain a peak value of the divided input signal, so as to determine the magnitude of the divided input signal according to the average value or the peak value of the divided input signal.

The reference voltage generating circuit 202 receives the dc voltage input to the voltage sampling circuit 201 and generates a reference voltage inversely proportional to the dc voltage, thereby achieving the purpose of keeping the input power constant when the input voltage varies. The reference voltage signal generation circuit 203 receives the reference voltage of the reference voltage generation circuit 202, and generates a reference voltage signal vref _ cs from the reference voltage and the divided input signal. The average value of the reference voltage signal vref _ cs is equal to the average value of the reference voltage. In a preferred embodiment, the divided input signal of the driving voltage signal vbulk is a half sine wave voltage, and the reference voltage signal vref _ cs is a half sine wave voltage proportional to the divided input signal of the driving voltage signal vbulk and has the same frequency.

In some embodiments, as shown in fig. 3, a dimming control circuit 204 is further included between the reference voltage generation circuit 202 and the reference voltage signal generation circuit 203, an input terminal of the dimming control circuit 204 is connected to the output terminal of the reference voltage generation circuit 202, and an output terminal of the dimming control circuit 204 is connected to the input terminal of the reference voltage signal generation circuit 203. The dimming control circuit 204 controls on/off of the reference voltage generated by the reference voltage generation circuit 202 to the reference voltage signal generation circuit 203. Specifically, the dimming control circuit 204 receives an externally input PWM control signal and outputs a pair of complementary logic signals, thereby implementing PWM control of the reference voltage. The reference voltage is allowed to be applied to the reference voltage signal generation circuit 203 at one logic level state by the PWM control signal. In the other logic level state, the reference voltage is blocked from being applied to the reference voltage signal generating circuit 203 so that the voltage applied to the reference voltage signal generating circuit 203 is 0, and thus the reference voltage vrefo applied to the reference voltage signal generating circuit 203 has a relationship with the duty ratio of the PWM control signal, thereby realizing accurate PWM dimming control.

As shown in fig. 2 and 3, an input terminal of the reference voltage signal switching circuit 301 is connected to an output terminal of the reference voltage signal generating circuit 203. The reference voltage signal switching circuit 301 includes N segment reference voltage output ends, and the N segment reference voltage output ends of the reference voltage signal switching circuit 301 are respectively connected to N input ends of the multi-segment constant current driving circuit 302 in a one-to-one correspondence manner.

The reference voltage signal switching circuit 301 provides N reference driving voltage signals (vref1-vref1N) to the multi-stage constant current driving circuit 302 according to the reference voltage signal vref _ cs, generates driving current signals (iout1-ioutn) of each LED lamp segment, and inputs the driving current signals (iout1-ioutn) to the corresponding LED lamp segments to control the N LED lamp segments to be sequentially turned on or off.

Specifically, the multi-stage constant current driving circuit further includes N constant current driving units, where the N constant current driving units have output terminals forming N driving output terminals of the multi-stage constant current driving circuit 302, and the reference voltage signal switching circuit 301 generates N reference driving voltage signals (vref1-vref1N) to each constant current driving unit of the multi-stage constant current driving circuit 302 according to the reference voltage signal vref _ cs and the on state of each constant current driving unit, and generates driving current signals (iout1-ioutn) corresponding to each LED lamp stage. The multi-stage constant current driving circuit 302 can combine and synthesize voltage signals which are the same as the reference voltage signal vref _ cs in a half alternating current period according to the N reference driving voltage signals (vref1-vref1N), so that the driving current signals (iout1-ioutn) of the N LED lamp segments are combined and formed half sine wave current signals, the half sine wave current signals are made to change along with the driving voltage signals vbulk, and the LED driving circuit can achieve a high power factor and has low total harmonic distortion.

A third embodiment of the present application relates to an LED driving circuit. The third embodiment is a further improvement on the basis of the first embodiment and the second embodiment, and the main improvement is that in this embodiment, an implementation manner of the LED driving circuit is specifically provided, as shown in fig. 4, the LED driving circuit in this embodiment includes a more specific component structure. In the preferred embodiment shown in fig. 4, the input terminals (ac1 and ac2) of the voltage conversion module 100 are connected to ac voltage, and dc + output driving voltage signal vbulk at the output terminals (dc + and dc-) of the voltage conversion module 100 is connected to the LED string 400 and dc-grounded. The driving voltage signal vbulk provides the operating voltage for the LED string 400.

Specifically, the output dc + of voltage conversion module 100 is connected to the anode of the first LED segment LED1 of LED light string 400. LED light string 400 is comprised of a plurality of series-connected LED light segments (LEDs 1-LEDn). The cathode of the LED1 is connected to the anode of the LED2 and the driving current signal output terminal out1 of the first constant current driving unit of the multi-stage constant current driving circuit 302, other LEDs are connected in sequence like the LED1, and the cathode of the last LED N is connected to the driving current signal output terminal outn of the nth constant current driving unit.

In some embodiments, the driving voltage signal vbulk has a large voltage value and cannot be directly connected with a driving circuit, and the driving circuit needs to be provided with a voltage division network for dividing the voltage of the driving voltage signal vbulk. In the preferred embodiment shown in fig. 4, the resistors R1 and R2 form a voltage divider network for dividing the driving voltage signal vbulk. The divided input signal vin obtained by the voltage division is input to the input terminal of the input voltage sampling circuit 201. Specifically, the input voltage sampling circuit 201 is composed of an operational amplifier I110, a MOS transistor M110, a capacitor C110, and a resistor R110. The non-inverting input terminal of the operational amplifier I110 is connected to the input terminal of the divided-voltage input signal to receive the divided-voltage input signal vin, and the inverting input terminal of the operational amplifier I110 is connected to the output terminal of the input voltage sampling circuit 201 to receive the dc voltage vindc at the output terminal. The output end of the operational amplifier I110 is connected with the gate of the MOS transistor M110, the drain of the MOS transistor M110 is connected with the internal power supply VDD, and the source of the MOS transistor M110 is connected with the output end of the input voltage sampling circuit 201. The capacitor C110 is a sample-and-hold capacitor, a first end of the capacitor C110 is connected to the output end of the input voltage sampling circuit 201, and a second end of the capacitor C110 is grounded. The resistor R110 is a discharge resistor, and the resistor R110 is connected in parallel with the capacitor C110. In the preferred embodiment shown in fig. 4, when the divided input signal vin is a half sine wave voltage, the dc voltage vindc at the output terminal of the input voltage sampling circuit 201 outputs a peak voltage of the half sine wave voltage as shown in fig. 4. It is understood that the dc voltage vindc may also be an average of the divided input signal vin.

A first input terminal of the reference voltage generating circuit 202 is connected to the output terminal of the input voltage sampling circuit 201 for receiving the dc voltage vindc at the output terminal of the input voltage sampling circuit 201, a second input terminal thereof is connected to a fixed reference voltage vref, and an output terminal of the reference voltage generating circuit 202 is connected to an input terminal of the dimming control circuit 204 for transmitting the reference voltage vrefo outputted by the reference voltage generating circuit 202 to the dimming control circuit 204. In the preferred embodiment shown in fig. 4, the reference voltage generating circuit 202 is composed of a multiplying circuit I120 and an operational amplifier I121, and a first input terminal of the multiplying circuit I120 forms an input terminal of the reference voltage generating circuit 202 to receive the direct-current voltage vindc. The second input terminal of the multiplication circuit I120 is connected to the output terminal of the operational amplifier I121 and the output terminal of the reference voltage generation circuit 202 (i.e., the reference voltage vrefo), the output terminal of the multiplication circuit I120 is connected to the inverting input terminal of the operational amplifier I121, and the non-inverting input terminal of the operational amplifier I121 is connected to the second input terminal of the reference voltage generation circuit 202 (i.e., the fixed reference voltage vref).

The reference voltage generating circuit 202 is used for generating a reference voltage inversely proportional to the input terminal dc voltage vindc, so as to maintain the input power constant when the input voltage varies. Let the multiplication coefficient of the multiplication circuit I120 be K120, the gain of the operational amplifier I121 be a121, and the output terminal vrefo of the reference voltage generation circuit 202 be:

since a121 × K120 × vindc is much larger than 1, vrefo can be approximated as:

however, it is understood that the reference voltage generating circuit 202 of the present embodiment is only an example of an implementation manner, and besides the implementation manner of the present embodiment, a piecewise linear manner may be adopted, for example, to achieve the same technical effect.

The dimming control circuit 204 is disposed between the reference voltage generating circuit 202 and the reference voltage signal generating circuit 203, and the dimming control circuit 204 is composed of an input buffer I15 and two MOS transistors M11 and M12. The input end of the input buffer I15 is connected to the PWM control signal, the first output end of the input buffer I15 is connected to the gate of the MOS transistor M11, the second output end of the input buffer I15 is connected to the gate of the MOS transistor M12, the drain of the MOS transistor M11 is connected to the output end of the reference voltage generating circuit 202 (i.e., the reference voltage vrefo), the source of the MOS transistor M11 is connected to the drain of the MOS transistor M12 and to the input end of the reference voltage signal generating circuit 203 (i.e., the average reference voltage avg _ vref), and the source of the MOS transistor M12 is grounded. The input buffer I15 receives the input PWM control signal and outputs a pair of complementary logic signals to control the MOS transistors M11 and M12, thereby implementing PWM control of the reference voltage vrefo. Specifically, when the PWM control signal is at a high level, M11 is turned on, M12 is turned off, and the reference voltage vrefo signal is input to the input terminal avg _ vref of the reference voltage signal generation circuit 203; when the PWM control signal is low, the input terminal avg _ vref of the reference voltage signal generation circuit 203 cannot receive the reference voltage vrefo, and thus avg _ vref is 0. Assuming that the PWM control signal duty cycle is Dpwm, avg _ vref can be expressed as:

the reference voltage signal generating circuit 203 has a first input terminal connected to the divided input signal vin and a second input terminal avg _ vref. A first output terminal comp of the reference voltage signal generation circuit 203 and a second output terminal output a reference voltage signal vref _ cs. In the preferred embodiment shown in fig. 4, the reference voltage signal generation circuit 203 is composed of a multiplication circuit I160 and a transconductance amplifier I161. The first input end of the multiplication circuit I160 is connected with the divided input signal vin, the second input end of the multiplication circuit I160 is connected with the output ends of the comp and transconductance amplifier I161, the non-inverting input end of the transconductance amplifier I161 is connected with the avg _ vref, and the inverting input end of the transconductance amplifier I161 is connected with the output end of the multiplication circuit I160. During normal operation, the average value of the reference voltage signal vref _ cs approximates the average value of avg _ vref due to the high gain of the transconductance amplifier I161. In the preferred embodiment of fig. 4, the driving circuit further includes an external capacitor C1, and the avg _ vref signal controlled by PWM can be filtered into a dc signal by the filtering function of the capacitor C1, so as to avoid PWM dimming strobes. Assuming that the multiplication coefficient of the multiplication circuit I160 is K160 and the equation of the half sine wave voltage signal dividing the input signal vin is vin (t) ═ vinm × sin ω t, the reference voltage signal vref _ cs can be expressed as:

vref_cs(t)＝K160*comp*vinm*sinωt

due to the high gain of the transconductance amplifier I161, the average voltage at the non-inverting input of I161 in the steady state is approximately equal to the average voltage at the inverting input, i.e., the average value < vref _ cs > < avg _ vref >, and the above formula vref _ cs (t) ═ K160 comp × vinm sin ω t is substituted to obtain:

<avg_vref>＝K160*comp*<vin>

thus, the method can obtain the product,

the above formula is substituted into vref _ cs (t) ═ K160 comp vinm sin ω t to obtain

As can be seen, under the condition that the divided voltage input signal vin and the PWM control signal are constant, the peak voltage vinm of vin is kept constant, and the average voltage < vin > is kept constant, so the reference voltage signal vref _ cs is a half sine wave voltage signal proportional to the divided voltage input signal vin, and the average value is avg _ vref. Waveforms for vin, vref _ cs, and avg _ vref are shown in fig. 6.

An input terminal of the reference voltage signal switching circuit 301 is connected to an output terminal of the reference voltage signal generating circuit 203 to receive the reference voltage signal vref _ cs. Specifically, the reference voltage signal switching circuit 301 includes a voltage buffer I131 and a switching network I130, an input of the reference voltage signal switching circuit 301 forms an input of the voltage buffer I131, and the voltage buffer I131 includes a first output terminal, a second output terminal, and a third output terminal, respectively forming three segment voltage signals V1, V2, and V3. Three output terminals of the voltage buffer I131 are respectively connected to three voltage input terminals of the switching network I130. The N reference driving voltage output terminals of the switching network I130 provide the reference driving voltage signals (vref1-vrefn), and the N reference driving voltage output terminals form the N voltage output terminals of the reference voltage signal switching circuit 301. The switch network I130 includes N status input terminals from the multi-stage constant current driving circuit 302, the N status input terminals are connected to the N status output terminals of the multi-stage constant current driving circuit 302, and the switch network I130 adjusts the magnitudes of vref1-vrefn according to the distribution commands (S1-Sn) input from the N status input terminals.

The N voltage output terminals of the reference voltage signal switching circuit 301 are connected to the input terminals of the N constant current driving units of the multi-stage constant current driving circuit 302 in a one-to-one correspondence, so as to respectively transmit the reference driving voltage signals (vref1-vref1N) to the input terminals of the N constant current driving units of the multi-stage constant current driving circuit 302. Specifically, the constant current driving units include an operational amplifier and an NMOS transistor, the non-inverting input terminal of the operational amplifier of each constant current driving unit is connected to a corresponding reference driving voltage signal, the inverting input terminal of the operational amplifier is connected to a sampling resistor Rcs, the output terminal of the operational amplifier is connected to the gate of the NMOS transistor, the state output terminals of the operational amplifiers of the constant current driving units form N state output terminals of the multi-stage constant current driving circuit 302 and are correspondingly connected to the state input terminals (S1-Sn) of the switch network I130, and the drain of the NMOS transistor of each constant current driving unit is correspondingly connected to the output terminals (out1-outn) of each driving current signal.

The switching network I130 adjusts the magnitude of vref1-vrefn based on the distribution commands input at the N status inputs. Specifically, the voltage buffer I131 outputs three segment voltage signals V1, V2 and V3 to the switch network I130 according to a reference voltage signal vref _ cs, where V1 is vref _ cs, V2 is vref _ cs + voffset, and V3 is vref _ cs-voffset, where voffset is a preset bias voltage value; the switch network I130 switchably distributes the three segment voltage signals to the N voltage outputs of the switch network I130 according to the distribution instruction inputted from the N status inputs, including the distribution of the same segment voltage signal to the plurality of voltage outputs. The distribution instruction (S1-Sn) includes logic signals 1 and 0 to indicate the on and off of each constant current driving unit in the multi-stage constant current driving circuit, and when a certain path of constant current driving unit is on, the corresponding logic signal is inverted from one state to another state (i.e., the inversion occurs between 0 and 1). In the preferred embodiment where N is 3, the reference voltage signal switching circuit 301 includes 3 voltage output terminals to output the reference driving voltage signals vref1, vref2, and vref3 to the input terminals of 3 constant current driving units of the multi-stage constant current driving circuit 302, respectively, and the 3 constant current driving units output driving current signals, respectively.

The switch network I130 adjusts the Vref1, Vref2 and Vref3 sizes according to the distribution commands (S1, S2, S3) inputted from the 3 status inputs. Specifically, it is assumed that (S1, S2, S3) the initial state in the case where M1-M3 do not flow through the circuit is (1, 1), indicating that LED1, LED2, and LED3 are all in the off state.

When the LED1 is switched from off to on, and the LED2 and the LED3 are off, the S1 is changed from 1 to 0, the conversion (S1, S2, S3) is (0, 1), the switching network I130 assigns V1 to Vref1, V2 to Vref2 and Vref3 according to the assignment command (0, 1), that is, V1 equals Vref1, and V2 equals Vref2 equals Vref 3. In this state, since the magnitude of the driving voltage signal vbulk is not enough to turn on the LED2 and the LED3, the constant current driving unit corresponding to the LED1 outputs a driving current signal iout1 flowing through the LED1 and varying in magnitude with the reference voltage signal vref _ cs, the driving current signal out1 flowing through M1 to Rcs, and the magnitude of the driving current signal iout1 is:

when the

LEDs

1 and 2 are turned on and the LED3 is turned off, the conversion of S2 from 1 to 0 (S1, S2, S3) is (0, 1), the switching network I130 assigns V1 to Vref2, V2 to Vref3, and V3 to Vref1 according to the assignment command (0, 1), that is, V1 is Vref2, V2 is Vref3, and V3 is Vref 1. In this state, due to the multi-stage constant current driving circuit 302, the output terminal out1 corresponding to the LED1 will be automatically turned off, and at the same time vbulk is not large enough to turn on the LED3, and the constant current driving unit corresponding to the LED1 outputs the driving current signal iout2 which flows through the LED1 and the LED2 and varies in magnitude with the reference voltage signal vref _ cs. The driving current signal iout2 flows to Rcs through the LED1 and the LED2, and the current of the driving current signal iout2 is:

when the LED1, the LED2, and the LED3 are turned on, the conversion of S3 from 1 to 0 (S1, S2, and S3) is (0, and 0), the switch network I130 assigns V1 to Vref3, V3 to Vref1 and Vref2 according to the assignment command (0, and 0), that is, V1 is Vref3, and V3 is Vref1 is Vref 2. In this state, due to the multi-stage constant current driving circuit 302, the output terminals out1 and out2 corresponding to the LED1 and the LED2, respectively, will be automatically turned off, and the driving current signal iout3 flows through the LED1, the LED2, and the LED3 and varies in magnitude in accordance with the reference voltage signal vref _ cs. The driving current signal iout3 flows to Rcs through the LED1, the LED2 and the LED3, and the magnitude of the current of the driving current signal iout3 is:

the current from the driving voltage to the ground is

The turn-on voltages of the LED1, the LED2 and the LED3 are vled1, vled2 and vled3, fig. 7 shows waveforms of vled1-vled3, vbulk, ivbulk, Vref _ cs, Vref1-Vref3, s1-s3 and iout1-iout 3 and cs in the whole half sine cycle, the driving current signals change along with the driving voltage signals vbulk in the whole half sine cycle, the LED1, the LED2 and the LED3 automatically switch the turn-on states according to the combined voltage, and the driving current signals flowing through the LED string when any combined segment is turned on all change along with the driving voltage signals Vref _ cs, so that the current changes along with the voltage in the whole alternating current cycle, the driving circuit achieves a high power factor, and meanwhile, the driving circuit has low total harmonic distortion.

In the preferred embodiment shown in fig. 4, let the input ac voltage be Vin _ rms, the duty ratio of the PWM control signal be Dpwm, and the driving voltage signal vbulk be:

the voltage-divided input signal vin after voltage division by the resistors R1 and R2 is as follows:

after being processed by the input voltage sampling circuit 201, the reference voltage generating circuit 202, the dimming control circuit 204 and the reference voltage signal generating circuit 203, the average value of the generated reference voltage signals is:

the average value of the current from the drive voltage to ground is:

it can be seen that the average ac input power can be expressed as:

from the above formula, under the condition that the external parameter is not changed, the input power is not affected by the input voltage, and the input power can be ensured to be stable in a wide input range. The invention is mainly applied to the design of LED lighting drive integrated circuits, in particular to the design of AC input high-power factor LED piecewise linear drive chips.

A fourth embodiment of the present application provides an LED driver including the above-described LED driving circuit. The LED drive circuit that this application driver provided guarantees that whole interchange cycle internal current follows voltage variation for drive circuit reaches higher power factor, has lower total harmonic distortion simultaneously.

A fifth embodiment of the present application relates to an LED driving method, and in this embodiment, an LED driving circuit includes: the LED lamp comprises a voltage conversion module, an LED lamp string, a reference voltage signal generation module and a constant current driving module; the LED lamp string comprises N LED lamp sections which are connected in series, and the anode of the first LED lamp section is connected with the output end of the voltage conversion module; the input end of the reference voltage signal generation module is connected with the output end of the voltage conversion module, the input end of the constant current driving module is connected with the output end of the reference voltage signal generation module, N driving output ends of the constant current driving module correspond to N LED lamp sections one by one, and each driving output end is connected to the cathode of the corresponding LED lamp section; the voltage conversion module is used for converting the input voltage signal into a driving voltage signal; the reference voltage signal generating module is used for correspondingly generating a reference voltage signal forming a driving current signal according to the driving voltage signal; the constant current driving module is used for generating driving current signals of the LED lamp sections according to the reference voltage signals and inputting the driving current signals to the corresponding LED lamp sections so as to control the N LED lamp sections to be sequentially switched on or switched off.

The following is a detailed description of implementation details of the LED driving method of the present embodiment, and the implementation details are provided only for easy understanding and are not necessary for implementing the present embodiment. The specific implementation flow of the LED driving method is shown in fig. 8, and includes the following steps:

step 401: the voltage conversion module converts the input voltage signal into a driving voltage signal.

Specifically, in the preferred embodiment, the input voltage signal is an ac power supply, and the voltage conversion module converts the input ac power supply into a driving voltage signal, where the driving voltage signal is a half-sine wave voltage signal.

Step 402: and the reference voltage signal generating module correspondingly generates a reference voltage signal forming a driving current signal according to the driving voltage signal.

Specifically, the reference voltage signal generation module samples the driving voltage signal, generates a reference voltage inversely proportional to the input voltage according to the driving voltage signal, and then generates a reference voltage signal having an average value equal to the reference voltage, wherein the reference voltage signal is a half sine wave voltage signal, and the reference voltage signal is a half sine wave voltage proportional to the driving voltage signal.

Step 403: the constant current driving module generates driving current signals of all the LED lamp sections according to the reference voltage signals and inputs all the driving current signals to the corresponding LED lamp sections so as to control the N LED lamp sections to be sequentially switched on or switched off.

Specifically, the constant current driving module obtains 3 segment voltage signals according to a reference voltage signal, where the 3 segment voltage signals include a first segment voltage signal v1, a first segment voltage signal v2, and a first segment voltage signal v3, the first segment voltage signal v1 is the same as the reference voltage signal, and a voltage difference between two adjacent segment voltage signals at the same time is a preset offset voltage value voffset, for example, v1 is equal to the reference voltage signal vref _ cs, v2 is equal to vref _ cs + voffset, and v3 is equal to vref _ cs-voffset. The constant current driving module switchably distributes the 3 segment voltage signals to form N reference driving voltage signals (vref1-vref1N) according to the distribution instruction. In a preferred embodiment where N is 3, when the first constant current driving unit (i.e., the LED1) is turned on, its corresponding logic signal is inverted from one state to another state (i.e., between 0 and 1), at this time, the first segment voltage signal v1 is distributed to the 1 st reference driving voltage signal vref1, and the other segment voltage signal v2 is distributed to the remaining reference driving voltage signals vref1 and vref 2. In this state, since the magnitude of the driving voltage signal is not sufficient to turn on the following LED at this time, the constant current driving unit corresponding to the LED1 outputs a driving current signal flowing through the LED1 and varying in magnitude following the reference voltage signal.

In turn, when the 2 nd constant current driving unit is turned on (i.e., the LED2 is turned on), v1 is distributed to the 2 nd reference driving voltage signal vref2, another segment voltage signal v2 is distributed to the 3 rd reference driving voltage signal vref3, and v3 is distributed to the 1 st reference driving voltage signal vref1 at this time. In this state, since the magnitude of the driving voltage signal is not sufficient to turn on the following LED3 at this time, the constant current driving unit corresponding to the LED2 outputs a driving current signal that flows through the LED1 and the LED2 and varies in magnitude following the reference voltage signal. Similarly, when the

LEDs

1, 2, and 3 are turned on, the constant current driving unit corresponding to the LED3 outputs a driving current signal that flows through the

LEDs

1, 2, and 3 and varies in magnitude in accordance with the reference voltage signal.

The constant current driving module correspondingly generates driving current signals of each LED lamp section through N reference driving voltage signals, each driving current signal is input to the corresponding LED lamp section, and each driving current signal can control the N LED lamp sections to be sequentially switched on or switched off. In the whole half sine period, the driving current signal changes along with the driving voltage signal, the LEDs 1-LEDn automatically switch the conducting state according to the combined voltage, and the driving current signal flowing through the LED lamp string changes along with the driving voltage signal when any combined section is conducted, so that the current in the whole alternating current period is ensured to change along with the voltage, the driving circuit achieves a high power factor, and meanwhile, the total harmonic distortion is low.

The above embodiments are merely illustrative of the principles and utilities of the present application and are not intended to limit the application. Any person skilled in the art can modify or change the above-described embodiments without departing from the spirit and scope of the present application. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical concepts disclosed in the present application shall be covered by the claims of the present application.

Claims

1. An LED driving circuit, comprising: the LED lamp comprises a voltage conversion module, an LED lamp string, a reference voltage signal generation module and a constant current driving module;

the LED lamp string comprises N LED lamp sections which are connected in series, and the anode of the first LED lamp section is connected with the output end of the voltage conversion module;

the input end of the reference voltage signal generation module is connected with the output end of the voltage conversion module, the input end of the constant current driving module is connected with the output end of the reference voltage signal generation module, N driving output ends of the constant current driving module correspond to N LED lamp sections one by one, and each driving output end is connected to the cathode of the corresponding LED lamp section;

the voltage conversion module is used for converting an input voltage signal into a driving voltage signal;

the reference voltage signal generating module is used for correspondingly generating a reference voltage signal forming a driving current signal according to the driving voltage signal;

the constant current driving module is used for generating driving current signals of the LED lamp sections according to the reference voltage signals and inputting the driving current signals to the corresponding LED lamp sections so as to control the N LED lamp sections to be sequentially switched on or switched off.

2. The LED driving circuit according to claim 1, wherein the driving current signals of N LED lamp segments are combined to form a half sine wave current signal.

3. The LED driving circuit according to claim 1, wherein the divided input signal of the driving voltage signal and the reference voltage signal are both half sine wave voltage signals, and the divided input signal of the driving voltage signal and the reference voltage signal have the same frequency.

4. The LED driving circuit according to claim 1, wherein the reference voltage signal generating module comprises an input voltage sampling circuit, a reference voltage generating circuit and a reference voltage signal generating circuit which are connected in sequence, wherein an input end of the input voltage sampling circuit is connected with an output end of the voltage converting module, and the reference voltage signal generating circuit is connected with an input end of the constant current driving module;

the input voltage sampling circuit is used for acquiring the peak voltage of the partial voltage input signal according to the partial voltage input signal of the driving voltage signal; the reference voltage generating circuit is used for generating a reference voltage which is inversely proportional to the peak voltage; the reference voltage signal generating circuit is used for generating the reference voltage signal according to the reference voltage and the divided voltage input signal.

5. The LED driving circuit according to claim 4, further comprising a dimming control circuit, wherein an input terminal of the dimming control circuit is connected to the output terminal of the reference voltage generation circuit, and an output terminal of the dimming control circuit is connected to the input terminal of the reference voltage signal generation circuit, and the dimming control circuit is configured to control on/off of the reference voltage generated by the reference voltage generation circuit to the reference voltage signal generation circuit.

6. The LED driving circuit according to claim 1, wherein the constant current driving module comprises a reference voltage signal switching circuit and a multi-section constant current driving circuit, the multi-section constant current driving circuit comprises N constant current driving units, and N output ends of the N constant current driving units form N driving output ends of the constant current driving module;

the input end of the reference voltage signal switching circuit is connected with the output end of the reference voltage signal generating circuit, the reference voltage signal switching circuit comprises N segmented reference voltage output ends, and the N segmented reference voltage output ends are respectively connected with the N input ends of the multi-segment constant current driving circuit in a one-to-one correspondence manner;

the reference voltage signal switching circuit is used for providing N reference driving voltage signals according to the reference voltage signals; the multi-section constant current driving circuit is used for generating driving current signals of the LED lamp sections according to the N reference driving voltage signals and inputting the driving current signals to the corresponding LED lamp sections so as to control the N LED lamp sections to be sequentially switched on or switched off.

7. The LED driving circuit according to claim 6, wherein the reference voltage signal switching circuit comprises a voltage buffer and a switch network, wherein an input terminal of the voltage buffer is connected with an output terminal of the reference voltage signal generating circuit, the voltage buffer comprises 3 segmented voltage output terminals, 3 segmented voltage output terminals are connected with 3 segmented voltage input terminals of the switch network in a one-to-one correspondence manner, and N voltage output terminals of the switch network are connected with N input terminals of the multi-segment constant current driving circuit in a one-to-one correspondence manner;

the voltage buffer is used for generating 3 segmented voltage signals according to the reference voltage signal, wherein the 3 segmented voltage signals at least comprise a first segmented voltage signal which is the same as the reference voltage signal and a voltage difference value between two adjacent segmented voltage signals at the same moment is a preset offset voltage value;

the switch network is used for switchably distributing the 3 segmented voltage signals to the N voltage output ends of the switch network according to a distribution instruction sent by the multi-segment constant current driving circuit.

8. An LED driver comprising the LED driving circuit according to any one of claims 1 to 7.

9. An LED driving method is applied to an LED driving circuit, and the LED driving circuit comprises: the LED lamp comprises a voltage conversion module, an LED lamp string, a reference voltage signal generation module and a constant current driving module; the LED lamp string comprises N LED lamp sections which are connected in series, and the anode of the first LED lamp section is connected with the output end of the voltage conversion module; the input end of the reference voltage signal generation module is connected with the output end of the voltage conversion module, the input end of the constant current driving module is connected with the output end of the reference voltage signal generation module, N driving output ends of the constant current driving module correspond to N LED lamp sections one by one, and each driving output end is connected to the cathode of the corresponding LED lamp section;

the LED driving method includes:

the voltage conversion module converts an input voltage signal into a driving voltage signal;

the reference voltage signal generating module correspondingly generates a reference voltage signal forming a driving current signal according to the driving voltage signal;

the constant current driving module generates driving current signals of the LED lamp sections according to the reference voltage signals and inputs the driving current signals to the corresponding LED lamp sections so as to control the N LED lamp sections to be sequentially switched on or switched off.

10. The method of claim 9, wherein the driving current signals of the N LED segments are combined to form a half sine wave current signal.

11. The LED driving method according to claim 9, wherein the driving voltage signal and the reference voltage signal are both half sine wave voltage signals, the driving voltage signal has the same frequency as the reference voltage signal, and the driving voltage signal has a different amplitude from the reference voltage signal.

12. The LED driving method according to claim 9, wherein the constant current driving module includes a reference voltage signal switching circuit and a multi-stage constant current driving circuit, the reference voltage signal switching circuit including a voltage buffer and a switch network;

the constant current driving module generates a driving current signal of each LED lamp section according to the reference voltage signal, and inputs each driving current signal to a corresponding LED lamp section to control N LED lamp sections to be sequentially turned on or off, and specifically includes: