LED driving power supply, power supply circuit and power supply method

Abstract

The present invention provides an LED driver power supply, power supply circuit, and power supply method, comprising: a rectifier module, which rectifies an AC voltage to obtain an input voltage; a first diode and a second diode connected in series in the same direction and then connected in parallel to the output end of the rectifier module; a first end of a first inductor connected to the cathode of the first diode, and a second end connected to the first end of a main switch; a freewheeling module connected in parallel to both ends of the first inductor; a lower plate of a first capacitor connected to the anode of the first diode, and an upper plate connected to the second end of the first inductor; a first end of a second inductor connected to the second end of the main switch, and a second end connected to the inverting output end of the rectifier module via a second capacitor; a cathode of a third diode connected to the first end of the second inductor, and an anode connected to the inverting output end of the rectifier module. The present invention has two switches, i.e., there are two degrees of control freedom, which makes it easier to optimize the control parameter design; and has a faster load dynamic response speed and smaller output current ripple.

Description

Technical Field

[0001] The present invention relates to the field of power electronics design, and in particular to an LED driving power supply, a power supply circuit and a power supply method. Background Art

[0002] Traditional power electronic devices connected to the power grid using bridge-type uncontrolled rectifier and filter circuits experience a large phase difference between their input current and input voltage, resulting in high harmonic content and low power factor. This can cause harmonic pollution to the power grid, leading to grid resonance and interference with the normal operation of electrical equipment. In fact, the large amount of current harmonics generated by power electronic devices has become one of the most significant sources of harmonics in the power grid. To reduce the harmonic components of the switching converter input current, power factor correction (PFC) technology must be used to meet harmonic standards such as IEC61000-3-2, thereby reducing pollution to the power grid. However, this still presents the following issues.

[0003] First, the output ripple of a single-stage PFC converter is large, which affects the system's output characteristics. Second, in applications where the load changes frequently and rapidly, the slow load dynamic response will cause the output DC bus voltage to fluctuate significantly for a long time, which not only degrades the system's control performance but also causes oscillation of the undervoltage protection function.

[0004] Therefore, how to obtain a power supply circuit with fast dynamic response and low output current ripple has become one of the problems that need to be solved urgently by those skilled in the art. Summary of the Invention

[0005] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide an LED driving power supply, a power supply circuit and a power supply method, which are used to solve the problems of slow dynamic response speed and large output current ripple of the PFC converter in the prior art.

[0006] To achieve the above-mentioned and other related objectives, the present invention provides a power supply circuit, which at least includes:

[0007] Rectifier module, first diode, second diode, first inductor, first capacitor, freewheeling module, main switch, third diode, second inductor and second capacitor;

[0008] The rectifier module receives an AC voltage and obtains a DC input voltage based on the rectification of the AC voltage;

[0009] The cathode of the first diode is connected to the positive phase output terminal of the rectifier module, and the anode is connected to the cathode of the second diode; the anode of the second diode is connected to the negative phase output terminal of the rectifier module;

[0010] A first end of the first inductor is connected to the cathode of the first diode, and a second end of the first inductor is connected to the first end of the main switch;

[0011] The input end of the freewheeling module is connected to the second end of the first inductor, and the output end is connected to the first end of the first inductor;

[0012] The lower plate of the first capacitor is connected to the anode of the first diode, and the upper plate is connected to the second end of the first inductor;

[0013] A first end of the second inductor is connected to the second end of the main switch, and a second end of the second inductor is connected to the inverting output end of the rectifier module via the second capacitor;

[0014] The cathode of the third diode is connected to the first end of the second inductor, and the anode of the third diode is connected to the inverting output end of the rectifier module.

[0015] Optionally, the freewheeling module includes a freewheeling switch and a fourth diode, and the freewheeling switch and the fourth diode are connected in series.

[0016] Optionally, the power supply circuit further includes a main switch control module, which includes an operational amplifier and a first comparator; the operational amplifier amplifies and outputs a difference between an output current of the power supply circuit and the first reference current; the first comparator compares an output signal of the operational amplifier with the carrier signal and generates a main switch control signal;

[0017] In which, the inverting input terminal of the operational amplifier receives the output current of the power supply circuit, and the non-inverting input terminal receives the first reference current; the non-inverting input terminal of the first comparator is connected to the output terminal of the operational amplifier, and the inverting input terminal receives the carrier signal; or, the non-inverting input terminal of the operational amplifier receives the output current of the power supply circuit, and the inverting input terminal receives the first reference current; the inverting input terminal of the first comparator is connected to the output terminal of the operational amplifier, and the non-inverting input terminal receives the carrier signal.

[0018] More optionally, the power supply circuit also includes a freewheeling switch control module, which includes a second comparator and an RS trigger; the inverting input terminal of the second comparator receives the current of the first inductor, and the non-phase input terminal receives a second reference current, compares the current of the first inductor with the second reference current and outputs a comparison result; the set terminal of the RS trigger is connected to the output terminal of the second comparator, and the reset terminal is connected to the control signal of the main switch, and outputs the freewheeling switch control signal.

[0019] More optionally, the second reference current is a sine wave in phase with the AC voltage.

[0020] To achieve the above-mentioned and other related purposes, the present invention further provides an LED driving power supply, which comprises at least:

[0021] An LED load and the above-mentioned power supply circuit, wherein the LED load is connected in parallel to both ends of the second capacitor.

[0022] To achieve the above-mentioned object and other related objects, the present invention further provides a power supply method for the above-mentioned power supply circuit, the power supply method for the power supply circuit at least comprising:

[0023] When the input voltage is less than or equal to the voltage on the first capacitor, the main switch is turned on and the freewheeling switch is turned off, and the first capacitor supplies power to the second inductor and the load; or the main switch and the freewheeling switch are turned off, and the second inductor supplies power to the load;

[0024] When the input voltage is greater than the voltage on the first capacitor, the main switch is turned on and the freewheeling switch is turned off, and the input voltage and the first capacitor supply power to the second inductor and the load; or the main switch and the freewheeling switch are turned off, and the first inductor charges the first capacitor, and the second inductor supplies power to the load; or the main switch is turned off and the freewheeling switch is turned on, the first inductor enters a freewheeling state, and the second inductor supplies power to the load.

[0025] To achieve the above-mentioned object and other related objects, the present invention further provides a power supply method for the above-mentioned power supply circuit, the power supply method for the power supply circuit at least comprising:

[0026] When the input voltage is less than or equal to the voltage on the first capacitor, the main switch is turned on and the freewheeling switch is turned off, so that the first capacitor supplies power to the second inductor and the load; or the main switch and the freewheeling switch are turned off, so that the current on the second inductor decreases, and the second inductor supplies power to the load; or the main switch and the freewheeling switch are turned off, so that the current on the second inductor is zero, and the second capacitor supplies power to the load;

[0027] When the input voltage is greater than the voltage on the first capacitor, the main switch is turned on and the freewheeling switch is turned off, and the input voltage and the first capacitor supply power to the second inductor and the load; or the main switch and the freewheeling switch are turned off, the first inductor charges the first capacitor, and the second inductor supplies power to the load; or the main switch is turned off and the freewheeling switch is turned on, the first inductor enters a freewheeling state, the current on the second inductor decreases, and the second inductor supplies power to the load; or the main switch is turned off and the freewheeling switch is turned on, the first inductor enters a freewheeling state, the first inductor enters a freewheeling state, the current on the second inductor is zero, and the second capacitor supplies power to the load.

[0028] More optionally, the main switch is turned on when the value obtained by subtracting the output current from the first reference current is greater than the value of the carrier signal; and the main switch is turned off when the value obtained by subtracting the output current from the first reference current is less than the value of the carrier signal.

[0029] More optionally, the carrier signal is a sawtooth wave.

[0030] More optionally, when the current of the first inductor is less than a second reference current and the main switch is in an off state, the freewheeling switch is turned on.

[0031] More optionally, the second reference current is a sine wave in phase with the AC voltage.

[0032] As described above, the LED driving power supply, power supply circuit, and power supply method of the present invention have the following beneficial effects:

[0033] 1. The converter in the LED driving power supply, power supply circuit and power supply method of the present invention has two switches: a main switch and a freewheeling switch, that is, there are two control degrees of freedom, which makes it easier to optimize the control parameter design.

[0034] 2. The LED driving power supply, power supply circuit and power supply method of the present invention have faster load dynamic response speed and smaller output current ripple. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Shown is a schematic structural diagram of the power supply circuit of the present invention.

[0036] Figure 2 Shown is a structural schematic diagram of the main switch control module of the present invention.

[0037] Figure 3 Shown is a structural schematic diagram of the freewheeling switch control module of the present invention.

[0038] Figure 4 Shown is a schematic structural diagram of the LED driving power supply of the present invention.

[0039] Figure 5-Figure 9 Shown is a schematic diagram of the working modes of the power supply method of the power supply circuit of the present invention.

[0040] Figure 10 Shown is a schematic diagram of waveforms of major nodes in the power supply method of the present invention.

[0041] Figure 11-12 Shown is a schematic diagram of the working modes of the power supply method of the power supply circuit of the present invention.

[0042] Figure 13 Shown is a schematic diagram of waveforms of major nodes in the power supply method of the present invention.

[0043] Figures 14-19 Shown are schematic diagrams of the AC voltage, input current, and output current waveforms of six types of PFC converters.

[0044] Figure 20-25 Schematic diagram showing the load dynamic performance of three power supply circuits: CCM-DCM, DCM-DCM, and PCCM-DCM.

[0045] Component number description

[0046] 1 Power supply circuit

[0047] 11 Rectifier module

[0048] 12 Freewheeling module

[0049] 13 Main switch control module

[0050] 131 Operational Amplifier

[0051] 132 First Comparator

[0052] 14 Freewheeling switch control module

[0053] 141 Second comparator

[0054] 142 RS flip-flop DETAILED DESCRIPTION

[0055] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0056] See also Figure 1-Figure 25 It should be noted that the diagrams provided in this embodiment are merely schematic illustrations of the basic concept of the present invention. Therefore, the diagrams only show components related to the present invention and are not drawn according to the number, shape, and size of components in actual implementation. In actual implementation, the type, quantity, and proportion of each component may be changed arbitrarily, and the component layout may also be more complex.

[0057] Example 1

[0058] like Figure 1 As shown, this embodiment provides a power supply circuit 1, and the power supply circuit 1 includes:

[0059] The rectifier module 11 includes a first diode D1, a second diode D2, a first inductor L1, a first capacitor C1, a freewheeling module 12, a main switch S, a third diode D3, a second inductor L2, and a second capacitor C2.

[0060] like Figure 1 As shown, the rectifier module 11 receives the AC voltage V ac , and based on the AC voltage V ac Rectification obtains the DC input voltage V in .

[0061] Specifically, in this embodiment, the rectifier module 11 is a bridge-type uncontrolled rectifier filter circuit, including two diode groups connected in parallel, each diode group including two diodes connected in series, and the AC voltage V ac Connected between two diodes of each diode group, the rectifier module 11 provides a DC input voltage V in , the input voltage V in In actual use, any structure that can rectify AC voltage into DC voltage is applicable to the present invention, and is not limited to this embodiment.

[0062] like Figure 1 As shown, the cathode of the first diode D1 is connected to the positive phase output end of the rectifier module 11 , and the anode is connected to the cathode of the second diode D2 ; the anode of the second diode D2 is connected to the negative phase output end of the rectifier module 11 .

[0063] Specifically, the first diode D1 and the second diode D2 are connected in series in phase and then connected in parallel to the output end of the rectifier module 11 to provide a current path.

[0064] like Figure 1 As shown, a first end of the first inductor L1 is connected to the cathode of the first diode D1 , and a second end is connected to the first end of the main switch S.

[0065] like Figure 1 As shown, the input end of the freewheeling module 12 is connected to the second end of the first inductor L1 , and the output end is connected to the first end of the first inductor L1 .

[0066] Specifically, in this embodiment, the freewheeling module 12 includes a freewheeling switch SF and a fourth diode D4, wherein the freewheeling switch SF is connected in series with the fourth diode D4. As an example, the freewheeling switch SF is an NMOS transistor, wherein the drain of the freewheeling switch SF is connected to the second end of the first inductor, the source is connected to the anode of the fourth diode D4, and the gate receives the freewheeling switch control signal VSF; the cathode of the fourth diode D4 is connected to the first end of the first inductor L1; the positional relationship between the freewheeling switch SF and the fourth diode D4 is interchangeable, and the two can be connected in series. In actual use, any selectable freewheeling module is applicable to the present invention, and is not limited to this embodiment.

[0067] like Figure 1 As shown, the lower plate of the first capacitor C1 is connected to the anode of the first diode D1, and the upper plate is connected to the second end of the first inductor L1.

[0068] like Figure 1 As shown, a first end of the second inductor L2 is connected to the second end of the main switch S, and a second end is connected to the inverting output end of the rectifier module 11 via the second capacitor C2.

[0069] Specifically, in this embodiment, the main switch S is an NMOS transistor, the drain of the main switch S is connected to the second end of the first inductor L1, the source is connected to the first end of the second inductor L2, and the gate is connected to the main switch control signal V S ; In actual use, the connection port can be adaptively adjusted according to the specific device type, and will not be described in detail here.

[0070] Specifically, the two ends of the second capacitor C2 are the output voltage V of the power supply circuit 1. o .

[0071] like Figure 1 As shown, the cathode of the third diode D3 is connected to the first end of the second inductor L2 , and the anode is connected to the inverting output end of the rectifier module 11 .

[0072] like Figure 2 As shown in FIG. 1 , as another implementation of the present invention, the power supply circuit 1 further includes a main switch control module 13. In this embodiment, the main switch control module 13 includes an operational amplifier 131 and a first comparator 132. As an example, the output current i of the power supply circuit 1 at the inverting input terminal of the operational amplifier 131 is o , the non-inverting input terminal receives the first reference current I ref , the output current i of the power supply circuit 1 o With the first reference current I refThe first comparator 132 has a positive input connected to the output of the operational amplifier 131, and an inverting input connected to the carrier signal, and compares the output signal of the operational amplifier 131 with the carrier signal to generate a main switch control signal V S . In this embodiment, the carrier signal is a sawtooth wave; in actual use, the waveform of the carrier can be set as needed. It should be noted that the relationship between the polarity of the input terminal of the operational amplifier 131 and the corresponding input signal is interchangeable, and at the same time, the relationship between the polarity of the input terminal of the first comparator 132 and the corresponding input signal also needs to be interchanged (that is, the positive input terminal of the operational amplifier receives the output current of the power supply circuit, and the negative input terminal receives the first reference current; the negative input terminal of the first comparator is connected to the output terminal of the operational amplifier, and the positive input terminal receives the carrier signal), which can also realize the control of the main switch S of the present invention. Furthermore, any circuit structure that can realize the following logic is applicable to the present invention, and is not limited to the devices and connection relationships listed in this embodiment: in the first reference current I ref Subtract the output current i o The value of (I ref -i o ) is greater than the value of the carrier signal, the main switch S is turned on, and the first reference current I ref Subtract the output current i o The value of (I ref -i o ) is less than the value of the carrier signal, the main switch S is turned off.

[0073] like Figure 3 As shown in FIG. 1 , as another implementation of the present invention, the power supply circuit 1 further includes a freewheeling switch control module 14. In this embodiment, the freewheeling switch control module 14 includes a second comparator 141 and an RS trigger 142. The inverting input terminal of the second comparator 141 receives the current i of the first inductor L1. L1 , the non-inverting input terminal receives the second reference current i ref , the current i of the first inductor L1 L1 With the second reference current i ref Compare and output the comparison result; as an example, the second reference current i ref The AC voltage V ac The set terminal of the RS trigger 142 is connected to the output terminal of the second comparator 141, and the reset terminal is connected to the main switch control signal V S , output freewheeling switch control signal V SFIt should be noted that any circuit structure that can realize the following logic is applicable to the present invention, and is not limited to the devices and connection relationships listed in this embodiment: When the current i L1 is less than the second reference current i ref , and when the main switch S is in the off state, the freewheeling switch SF is turned on.

[0074] It should be noted that the control logic of the main switch S and the freewheeling switch SF is not limited to the scheme listed in this embodiment. Any method that can control the main switch S and the freewheeling switch SF based on the power supply circuit of the present invention to achieve power supply as needed is applicable, and is not limited to this embodiment.

[0075] The present invention is based on a quadratic Buck PFC converter in a three-state operating mode, which improves load dynamic response speed and reduces output current ripple. In addition, according to the charge balance of the first capacitor C1, it can be obtained that:

[0076] (I L2 -I L1 )dT S =I L1 (1-d)T S Formula 1

[0077] Solving equation 1, we can get:

[0078] I L1 =dI L Formula 2

[0079] Among them, I L1 , I L2 They are the inductor current i L1 、i L2 The average value in each cycle, d is the on-duty cycle of the main switch, T S is the switching period of the power circuit. From formula 2, we can see that I L1 L2 Therefore, adding a freewheeling loop to the first inductor L1 can reduce losses during the freewheeling process, thereby enabling the power supply circuit to achieve higher efficiency.

[0080] Example 2

[0081] like Figure 4 As shown, this embodiment provides an LED driver power supply comprising an LED load and a power circuit 1. The power circuit 1 employs the power circuit structure of the first embodiment, and its specific structure is not described in detail here. The LED load is connected in parallel across a second capacitor C2, and the power circuit 1 supplies power to the LED load.

[0082] ​The power supply circuit 1 has a fast load dynamic response speed and a small output current ripple, which can achieve flicker-free LED load.

[0083] Example 3

[0084] like Figure 1 、 Figures 5-10 As shown, this embodiment provides a power supply method for a power supply circuit, which is implemented based on the power supply circuit 1 of Example 1, wherein the first inductor L1 operates in PCCM mode (Psuedo Continuous Conduction Mode), and the second inductor L2 operates in CCM mode (Continuous Conduction Mode). The power supply method for the power supply circuit includes:

[0085] When the input voltage is less than or equal to the voltage on the first capacitor, the main switch is turned on and the freewheeling switch is turned off, and the first capacitor supplies power to the second inductor and the load; or the main switch and the freewheeling switch are turned off, and the second inductor supplies power to the load;

[0086] When the input voltage is greater than the voltage on the first capacitor, the main switch is turned on and the freewheeling switch is turned off, and the input voltage and the first capacitor supply power to the second inductor and the load; or the main switch and the freewheeling switch are turned off, and the first inductor charges the first capacitor, and the second inductor supplies power to the load; or the main switch is turned off and the freewheeling switch is turned on, the first inductor enters a freewheeling state, and the second inductor supplies power to the load.

[0087] Specifically, within half a power frequency cycle, the working mode of the power supply circuit is divided into two stages: stage A and stage B.

[0088] 1) Phase A

[0089] When the input voltage V in Less than or equal to the voltage V on the first capacitor C1 When the power supply circuit operates in phase A, the input and output terminals are disconnected, and the freewheeling switch SF is always in the off state. Phase A includes two operating modes: mode I and mode II.

[0090] Mode I: If Figure 5 As shown, when the main switch S is turned on, no current flows through the first inductor L1, and the first diode D1 is turned off; the first capacitor C1 supplies power to the second inductor L2 and the load, the second diode D2 is turned on, and the third diode D3 is turned off. The current i L2 Linear increase.

[0091] Mode II: As Figure 6 As shown, when the main switch S is turned off, the third diode D3 is turned on to provide a discharge circuit for the second inductor L2. The second inductor L2 supplies power to the load. The current i L2 Linear decrease.

[0092] 2) Phase B

[0093] When the input voltage V in is greater than the voltage V on the first capacitor C1 When , the power circuit operates in phase B, which includes three operating modes: mode III, mode IV and mode V. In one switching cycle, assuming that the AC voltage V ac remain unchanged, then:

[0094] Mode III: If Figure 7 As shown, when the main switch S is turned on and the freewheeling switch SF is turned off, the input voltage V in The first capacitor C1 supplies power to the inductor and the load. The current i on the first inductor L1 and the second inductor L2 is L1 and i L2 The voltage rises linearly, the second diode D2 is turned on, and the first diode D and the third diode D3 are turned off due to the reverse voltage.

[0095] Mode IV: As Figure 8 As shown, when the main switch S and the freewheeling switch SF are both turned off, the second diode D2 is turned off, and the first diode D1 is turned on, providing a discharge circuit for the first inductor L1. The first inductor L1 charges the first capacitor C1, and the current i on the first inductor L1 is L1 The third diode D3 is turned on to provide a discharge circuit for the second inductor L2. The second inductor L2 supplies power to the load. The current i on the second inductor L2 is L2 Linear decrease.

[0096] Mode V: As Figure 9 As shown, when the main switch S is turned off and the freewheeling switch SF is turned on, the fourth diode D4 is turned on, the first inductor L1 enters the freewheeling state, and the current i on the first inductor L1 is L1 The third diode D3 is turned on to provide a discharge circuit for the second inductor L2. The second inductor L2 supplies power to the load. The current i L2 Linear decrease.

[0097] In this embodiment, the control logic of the main switch S and the freewheeling switch SF is as follows: when the first reference current I refSubtract the output current i o When the value of the first reference current I ref Subtract the output current i o When the value of is greater than the value of the carrier signal, the main switch S is turned off. As an example, the carrier signal is a sawtooth wave. When the current i of the first inductor L1 is L1 is less than the second reference current i ref , and when the main switch S is in the off state, the freewheeling switch SF is turned on. As an example, the second reference current i ref is the AC voltage V ac In-phase sine waves.

[0098] Specifically, as an example, this embodiment adopts a sinusoidal current reference control strategy, uses a voltage signal to control the conduction of the main switch S, and uses an inductor current feedback signal to control the conduction of the freewheeling switch SF. Figure 2 and Figure 3 As shown, by outputting the current signal i o With reference current I ref The error signal obtained after comparison and amplification by the operational amplifier is used as the positive input of the first comparator and compared with the negative input carrier to obtain the driving control signal V for controlling the main switch S. S ; Inductor current i L1 Reference value i ref Is the AC voltage V ac The sine wave with the same phase is compared with the inductor current and is used as the input of the RS trigger S terminal through the second comparator. The control signal of the main switch S is used as the input of the RS trigger R terminal, and the Q terminal outputs the drive control signal V of the freewheeling switch SF. SF , thereby achieving control of the converter through a voltage outer loop and a current inner loop.

[0099] like Figure 10 FIG. 1 shows waveform diagrams of main nodes in the power supply method of this embodiment. It can be seen that the first inductor L1 operates in the PCCM mode, and the second inductor L2 operates in the CCM mode.

[0100] Example 4

[0101] like Figure 1 、 Figure 11-13 As shown, this embodiment provides a power supply method for a power supply circuit, which is implemented based on the power supply circuit 1 of Example 1, wherein the first inductor L1 operates in PCCM mode, and the second inductor L2 operates in DCM mode (Discontinuous Conduction Mode). The power supply method for the power supply circuit includes:

[0102] When the input voltage is less than or equal to the voltage on the first capacitor, the main switch is turned on and the freewheeling switch is turned off, so that the first capacitor supplies power to the second inductor and the load; or the main switch and the freewheeling switch are turned off, so that the current on the second inductor decreases, and the second inductor supplies power to the load; or the main switch and the freewheeling switch are turned off, so that the current on the second inductor is zero, and the second capacitor supplies power to the load;

[0103] When the input voltage is greater than the voltage on the first capacitor, the main switch is turned on and the freewheeling switch is turned off, and the input voltage and the first capacitor supply power to the second inductor and the load; or the main switch and the freewheeling switch are turned off, the first inductor charges the first capacitor, and the second inductor supplies power to the load; or the main switch is turned off and the freewheeling switch is turned on, the first inductor enters a freewheeling state, the current on the second inductor decreases, and the second inductor supplies power to the load; or the main switch is turned off and the freewheeling switch is turned on, the first inductor enters a freewheeling state, the first inductor enters a freewheeling state, the current on the second inductor is zero, and the second capacitor supplies power to the load.

[0104] Specifically, within half a power frequency cycle, the working mode of the power supply circuit is divided into two stages: stage A and stage B.

[0105] 1) Phase A

[0106] When the input voltage V in Less than or equal to the voltage V on the first capacitor C1 When the power supply circuit operates in phase A, it includes three operating modes: mode I, mode II and mode VI; wherein mode I and mode II are the same as mode I and mode II of embodiment three, and are not described in detail here.

[0107] Modal VI: If Figure 11 As shown, when the main switch S and the freewheeling switch SF are both turned off, the current i of the second inductor L2 L2 When the voltage drops to zero, the third diode D3 is turned off, and the second capacitor C2 supplies power to the load.

[0108] 2) Phase B

[0109] When the input voltage V in is greater than the voltage V on the first capacitor C1 When the power supply circuit operates in stage B, it includes four operating modes: mode III, mode IV, mode V and mode VII; among them, mode III, mode IV, mode V are the same as mode III, mode IV, mode V in embodiment three, and are not described one by one here.

[0110] Mode VII: As Figure 12 As shown, when the main switch S is turned off and the freewheeling switch SF is turned on, the first inductor L1 enters the freewheeling state, and the current i L1 Remain unchanged, L2 drops to zero and capacitor C2 supplies power to the load.

[0111] The switch control logic and method of this embodiment are the same as those of the third embodiment, and are not described in detail here.

[0112] like Figure 13 FIG. 1 shows waveform diagrams of main nodes in the power supply method of this embodiment. It can be seen that the first inductor L1 operates in the PCCM mode, and the second inductor L2 operates in the DCM mode.

[0113] like Figures 14-19 As shown, the present invention builds the simulation models of six PFC converters including CCM / DCM-CCM / DCM quadratic Buck PFC converter and PCCM-CCM / DCM quadratic Buck PFC converter based on PSIM simulation software, and obtains the AC voltage V ac 、Input current i in and the output current i o Waveform diagram; among them, Figure 14 This is the waveform corresponding to the CCM-CCM working mode. Figure 15 This is the waveform corresponding to the CCM-DCM working mode. Figure 16 This is the waveform corresponding to the DCM-CCM working mode. Figure 17 This is the waveform corresponding to the DCM-DCM working mode. Figure 18 This is the waveform diagram corresponding to the PCCM-CCM working mode of the present invention, Figure 19 This is the waveform diagram corresponding to the PCCM-DCM working mode of the present invention; it can be seen that the present invention has smaller output ripple. Figure 20-25 As shown, three power supply circuits, CCM-DCM, DCM-DCM and PCCM-DCM, are selected to verify and analyze their load dynamic performance; among them, Figure 20 The figure shows the response time when the load power jumps from 20W to 10W in CCM-DCM working mode. Figure 21 The figure shows the response time when the load power jumps from 10W to 20W in CCM-DCM working mode. Figure 22 The figure shows the response time when the load power jumps from 20W to 10W in DCM-DCM working mode. Figure 23 The figure shows the response time when the load power jumps from 10W to 20W in DCM-DCM working mode. Figure 22The figure shows the response time when the load power jumps from 20W to 10W in the PCCM-DCM working mode of the present invention. Figure 23 The figure shows the response time when the load power jumps from 10W to 20W in the PCCM-DCM working mode of the present invention; it can be seen that the present invention has a faster load dynamic response speed.

[0114] In summary, the present invention provides a power supply circuit, comprising: a rectifier module, a first diode, a second diode, a first inductor, a first capacitor, a freewheeling module, a main switch, a third diode, a second inductor and a second capacitor; the rectifier module receives an AC voltage and obtains a DC input voltage based on the rectification of the AC voltage; the cathode of the first diode is connected to the positive output end of the rectifier module, and the anode is connected to the cathode of the second diode; the anode of the second diode is connected to the negative output end of the rectifier module; the first end of the first inductor is connected to the cathode of the first diode, and the second end is connected to the first end of the main switch; the input end of the freewheeling module is connected to the second end of the first inductor, and the output end is connected to the first end of the first inductor; the lower plate of the first capacitor is connected to the anode of the first diode, and the upper plate is connected to the second end of the first inductor; the first end of the second inductor is connected to the second end of the main switch, and the second end is connected to the negative output end of the rectifier module via the second capacitor; the cathode of the third diode is connected to the first end of the second inductor, and the anode is connected to the negative output end of the rectifier module. The converter in the LED driver power supply, power supply circuit, and power supply method of the present invention has two switches: a main switch and a freewheeling switch. This provides two degrees of control freedom, making it easier to optimize control parameter design. It also offers faster load dynamic response and reduced output current ripple. Therefore, the present invention effectively overcomes various shortcomings of the prior art and has high industrial application value.

[0115] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A power supply circuit, characterized in that: The power supply circuit at least includes: Rectifier module, first diode, second diode, first inductor, first capacitor, freewheeling module, main switch, third diode, second inductor and second capacitor; The rectifier module receives an AC voltage and obtains a DC input voltage based on the rectification of the AC voltage; The cathode of the first diode is connected to the positive phase output terminal of the rectifier module, and the anode is connected to the cathode of the second diode; the anode of the second diode is connected to the negative phase output terminal of the rectifier module; A first end of the first inductor is connected to the cathode of the first diode, and a second end of the first inductor is connected to the first end of the main switch; The input end of the freewheeling module is connected to the second end of the first inductor, and the output end is connected to the first end of the first inductor; wherein, when the current of the first inductor is less than the second reference current and the main switch is in the off state, the freewheeling module is turned on; The lower plate of the first capacitor is connected to the anode of the first diode, and the upper plate is connected to the second end of the first inductor; A first end of the second inductor is connected to the second end of the main switch, and a second end of the second inductor is connected to the inverting output end of the rectifier module via the second capacitor; The cathode of the third diode is connected to the first end of the second inductor, and the anode of the third diode is connected to the inverting output end of the rectifier module.

2. The power supply circuit according to claim 1, wherein: The freewheeling module includes a freewheeling switch and a fourth diode, and the freewheeling switch and the fourth diode are connected in series.

3. The power supply circuit according to claim 1, wherein: The power supply circuit further includes a main switch control module, which includes an operational amplifier and a first comparator; the operational amplifier amplifies and outputs a difference between an output current of the power supply circuit and a first reference current; the first comparator compares the output signal of the operational amplifier with a carrier signal and generates a main switch control signal; In which, the inverting input terminal of the operational amplifier receives the output current of the power supply circuit, and the non-inverting input terminal receives the first reference current; the non-inverting input terminal of the first comparator is connected to the output terminal of the operational amplifier, and the inverting input terminal receives the carrier signal; or, the non-inverting input terminal of the operational amplifier receives the output current of the power supply circuit, and the inverting input terminal receives the first reference current; the inverting input terminal of the first comparator is connected to the output terminal of the operational amplifier, and the non-inverting input terminal receives the carrier signal.

4. The power supply circuit according to any one of claims 1 to 3, wherein: The power supply circuit further includes a freewheeling switch control module, which includes a second comparator and an RS trigger; the second comparator receives the current of the first inductor at its inverting input terminal and the second reference current at its non-inverting input terminal, compares the current of the first inductor with the second reference current, and outputs a comparison result; The set end of the RS trigger is connected to the output end of the second comparator, and the reset end is connected to the control signal of the main switch, outputting a control signal for controlling the on and off of the freewheeling module.

5. The power supply circuit according to claim 4, wherein: The second reference current is a sine wave in phase with the AC voltage.

6. An LED driving power supply, characterized in that: The LED driving power supply at least includes: An LED load and a power supply circuit as described in any one of claims 1 to 5, wherein the LED load is connected in parallel to both ends of the second capacitor.

7. A power supply method for a power supply circuit according to any one of claims 1 to 5, characterized in that: The power supply method of the power supply circuit at least includes: When the input voltage is less than or equal to the voltage on the first capacitor, the main switch is turned on and the freewheeling switch is turned off, so that the first capacitor supplies power to the second inductor and the load; or the main switch and the freewheeling switch are turned off, so that the current on the second inductor decreases, and the second inductor supplies power to the load; or the main switch and the freewheeling switch are turned off, so that the current on the second inductor is zero, and the second capacitor supplies power to the load; When the input voltage is greater than the voltage on the first capacitor, the main switch is turned on and the freewheeling switch is turned off, and the input voltage and the first capacitor supply power to the second inductor and the load; or the main switch and the freewheeling switch are turned off, the first inductor charges the first capacitor, and the second inductor supplies power to the load; or the main switch is turned off and the freewheeling switch is turned on, the first inductor enters a freewheeling state, the current on the second inductor decreases, and the second inductor supplies power to the load; or the main switch is turned off and the freewheeling switch is turned on, the first inductor enters a freewheeling state, the first inductor enters a freewheeling state, the current on the second inductor is zero, and the second capacitor supplies power to the load.

8. The power supply method of the power supply circuit according to claim 7, wherein: The main switch is turned on when the value of the first reference current minus the output current is greater than the value of the carrier signal; and the main switch is turned off when the value of the first reference current minus the output current is less than the value of the carrier signal.

9. The power supply method of the power supply circuit according to claim 8, characterized in that: The carrier signal is a sawtooth wave.

10. The power supply method of the power supply circuit according to claim 7, wherein: The second reference current is a sine wave with the same phase as the AC voltage.

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