Converter control circuit and charger

Abstract

Embodiments of the present invention provide a converter control circuit and a charger. The converter control circuit comprises a first control circuit, a feedback circuit and a converter circuit; a voltage input end of the first control circuit and a voltage input end of the converter circuit are used for accessing an input voltage; a frequency output end of the first control circuit is electrically connected to a frequency input end of the converter circuit, and a voltage output end of the converter circuit is used for being electrically connected to a load; a feedback output end of the converter circuit is electrically connected to a feedback input end of the feedback circuit, and a feedback output end of the feedback circuit is electrically connected to a feedback input end of the first control circuit; the first control circuit comprises a control unit, and the control unit is used for receiving a feedback voltage and a feedback current that are transmitted by the feedback circuit, and on the basis of the feedback voltage and the feedback current, adjusting a target frequency input to the converter circuit so as to control a working mode of the converter circuit. The working mode of the converter can be controlled, thereby improving the conversion efficiency.

Description

Converter control circuit and charger

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on January 3, 2024, with application number 202410008669.9 and application name “Converter Control Circuit and Charger”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of power electronics, and in particular to a converter control circuit and a charger. Background Art

[0003] New energy electric vehicles all have large-capacity rechargeable battery packs, which require an onboard high-power charger during charging. Typically, these high-power chargers are based on switching power supply technology. Traditional switching power supplies, however, mostly use hard-switching technology, which prevents them from controlling the converter's operating mode and results in low conversion efficiency.

[0004] Summary of the Invention

[0005] In view of this, an embodiment of the present invention provides a converter control circuit and a charger, which can control the working mode of the converter and improve the conversion efficiency.

[0006] In a first aspect, an embodiment of the present invention provides a converter control circuit, the converter control circuit comprising: a first control circuit, a feedback circuit, and a converter circuit;

[0007] The voltage input terminal of the first control circuit and the voltage input terminal of the converter circuit are used to receive input voltage;

[0008] The frequency output terminal of the first control circuit is electrically connected to the frequency input terminal of the converter circuit, and the voltage output terminal of the converter circuit is used to be electrically connected to a load;

[0009] The feedback output of the converter circuit is electrically connected to the feedback input of the feedback circuit, and the feedback output of the feedback circuit is electrically connected to the feedback input of the first control circuit. The first control circuit includes a control unit configured to receive a feedback voltage and a feedback current transmitted by the feedback circuit and adjust a target frequency input to the converter circuit based on the feedback voltage and the feedback current to control the operating mode of the converter circuit. Embodiments of the present application can control the operating mode of the converter and improve conversion efficiency.

[0010] On the other hand, an embodiment of the present invention provides a charger including the above-mentioned converter control circuit. Since the charger includes the above-mentioned converter control circuit, it can also control the working mode of the converter and improve conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG1 is a schematic diagram of a converter control circuit provided by an embodiment of the present invention;

[0012] FIG2 is a schematic diagram of the converter circuit in FIG1 ;

[0013] FIG3 is another schematic diagram of the converter circuit in FIG1 ;

[0014] FIG4 is a detailed schematic diagram of the converter control circuit in FIG1 ;

[0015] 5 is a schematic diagram of operating waveforms of the resonant cavity loop of the converter circuit in the first operating mode according to an embodiment of the present invention;

[0016] 6 is a schematic diagram of operating waveforms of the resonant cavity loop of the converter circuit in the second operating mode according to an embodiment of the present invention;

[0017] FIG7 is a schematic structural diagram of a converter provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0018] In order to better understand the technical solution of the present invention, the embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0019] It should be understood that the embodiments described are only a portion of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0020] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The singular forms "a", "an", "the" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

[0021] It should be understood that the term "and / or" as used herein simply describes a relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A alone, A and B together, or B alone. Furthermore, the character " / " in this document generally indicates an "or" relationship between the associated objects.

[0022] The rapid development of new energy electric vehicles (EVs) has placed higher demands on their energy storage systems. For example, longer driving ranges and larger battery capacities are essential. To provide a better user experience, stronger power, shorter battery charging times, and more efficient charging have become fundamental requirements for EVs.

[0023] New energy electric vehicles all have large-capacity rechargeable battery packs, which require an onboard high-power charger during charging. Typically, onboard high-power chargers are implemented using switching power supply technology. Traditional switching power supplies utilize hard-switching technology for their power transistors, which makes it difficult to control the converter's operating mode. In hard-switching switching converters, the phase difference between current and voltage during the on-off process creates an overlap region where both current and voltage are non-zero, ultimately resulting in low converter efficiency.

[0024] Basic circuit theory tells us that if the voltage and current across a circuit element are non-zero, the element generates power and consumes energy. Therefore, the switching converter consumes energy, making it difficult for traditional hard-switching technology to achieve conversion efficiencies exceeding 90%. This ultimately results in longer battery charging times, higher energy consumption to fully charge the battery pack, and more heat generation during the charging process.

[0025] Based on the above technical problems, an embodiment of the present invention provides a converter control circuit and a charger, which can control the working mode of the converter, reduce the overlapping area of ​​the voltage and current of the power switch tube during the switching process, thereby greatly reducing the loss of the power switch tube, and thus greatly improving the conversion efficiency of the converter.

[0026] Figure 1 is a schematic diagram of a converter control circuit provided by an embodiment of the present invention, Figure 2 is a schematic diagram of the converter circuit in Figure 1, Figure 3 is another schematic diagram of the converter circuit in Figure 1, and Figure 4 is a detailed schematic diagram of the converter control circuit in Figure 1. As shown in Figure 1, the converter control circuit includes: a first control circuit 100, a feedback circuit 300, and a converter circuit 200;

[0027] The voltage input terminal a of the first control circuit 100 and the voltage input terminal b of the converter circuit 200 are used to access the input voltage VBUS_HV;

[0028] The frequency output terminal c of the first control circuit 100 is electrically connected to the frequency input terminal d of the converter circuit 200. The voltage output terminal e of the converter circuit 200 is used to be electrically connected to a load to provide an output voltage VCC_OUT to the load.

[0029] The feedback output terminal f of the converter circuit 200 is electrically connected to the feedback input terminal g of the feedback circuit 300, and the feedback output terminal h of the feedback circuit 300 is electrically connected to the feedback input terminal i of the first control circuit 100; the first control circuit 100 includes a control unit, which is used to receive the feedback voltage and feedback current transmitted by the feedback circuit 300, and adjust the target frequency input to the converter circuit 200 according to the feedback voltage and the feedback current to control the operating mode of the converter circuit 200.

[0030] As shown in FIG1 , the converter control circuit further includes an input common terminal GND_HV and an output common terminal GND_OUT.

[0031] The first control circuit 100 and the feedback circuit 300 are further configured to be electrically connected to the input common terminal GND_HV; the converter circuit 200 and the feedback circuit 300 are further configured to be electrically connected to the output common terminal GND_OUT.

[0032] The input voltage VBUS_HV comes from the positive voltage output by the rectifier or the power correction circuit; the input common terminal GND_HV comes from the negative voltage output by the rectifier or the power correction circuit.

[0033] The output voltage VCC_OUT is the voltage output by the positive electrode of the converter, which is used to provide a positive voltage for the load; the output common terminal GND_OUT is the voltage output by the negative electrode of the converter, which is used to provide a negative voltage for the load.

[0034] In some possible embodiments, as shown in FIG2 , the converter circuit includes: a first switch tube Q1, a second switch tube Q2, a first inductor Lr, a second inductor Lm1, a resonant capacitor Cr, a first transformer T1, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a first node A, a second node B, a third node C, and a second capacitor C2;

[0035] The first switching transistor Q1 and the second switching transistor Q2 are power switching transistors. The first switching transistor Q1 is the high-side power switching transistor of the converter circuit, while the second switching transistor Q2 is the low-side power switching transistor of the converter circuit. The first terminal 1 of the first switching transistor Q1 and the second switching transistor Q2 is the drain, the second terminal 2 is the source, and the third terminal 3 is the gate.

[0036] The first transformer T1 is a switching transformer. As shown in FIG2 , the left side of the first transformer T1 is the primary side of the first transformer T1 , and the right side of the first transformer T1 is the secondary side of the first transformer T1 .

[0037] The first terminal 1 of the first switch tube Q1 is a voltage input terminal of the converter circuit, so the first terminal 1 of the first switch tube Q1 is used to access the input voltage VBUS_HV;

[0038] The second end 2 of the first switch tube Q1 is electrically connected to the first end 1 of the second switch tube Q2 and one end of the first inductor Lr;

[0039] The third terminal 3 of the first switch tube Q1 and the third terminal 3 of the second switch tube Q2 are frequency input terminals of the converter circuit;

[0040] The other end of the first inductor Lr is electrically connected to one end of the second inductor Lm1 and the first end 1 of the first transformer T1. The other two ends of the second inductor Lm1, the second end 2 of the first transformer T1, and one end of the resonant capacitor Cr are electrically connected to the third node C. The other end of the resonant capacitor Cr and the second end 2 of the second switch Q2 are electrically connected to the input common terminal GND_HV.

[0041] The third end 3 of the first transformer T1 is electrically connected to the first end 1 of the first diode D1 and the second end 2 of the third diode D3. The second end 2 of the first diode D1, the second end 2 of the second diode D2, and one end of the second capacitor C2 are electrically connected to the first node A. The first node A is the voltage output end of the converter circuit.

[0042] The fourth end 4 of the first transformer T1 is electrically connected to the first end 1 of the second diode D2 and the second end 2 of the fourth diode D4. The first end 1 of the third diode D3, the first end 1 of the fourth diode D4, and the other end of the second capacitor C2 are electrically connected to the second node B. The second node B is used to be electrically connected to the output common terminal GND_OUT.

[0043] The first node A and the third node C are feedback output terminals of the converter circuit.

[0044] In the converter circuit shown in Figure 2, the power switching MOS transistors comprise a first switching transistor Q1 and a second switching transistor Q2, respectively. The transformer is a first transformer T1. The first inductor Lr and the resonant capacitor Cr are connected in series with the primary side of the first transformer T1. The second inductor Lm1 is connected in parallel with the primary side of the first transformer T1. The secondary output of the first transformer T1 passes through a bridge rectifier formed by a first diode D1, a second diode D2, a third diode D3, and a fourth diode D4. The second capacitor C2 serves as an output filter capacitor. The first switching transistor Q1, the first inductor Lr, the second inductor Lm1, the first transformer T1, the resonant capacitor Cr, and the second switching transistor Q2 form a first resonant cavity loop.

[0045] The first resonant cavity loop has two natural frequencies: a first frequency and a second frequency.

[0046] The first frequency is the resonant frequency F of the first inductor Lr and the resonant capacitor Cr in series. r ,Right now

[0047] The second frequency is the resonant frequency F of the first inductor Lr, the second inductor Lm and the resonant capacitor Cr. m ,Right now

[0048] The converter circuit shown in Figure 2 achieves power switch softening in the switching converter, significantly reducing losses in the power switch tubes, thereby significantly improving conversion efficiency during the energy conversion process. Simultaneously, this power switch softening reduces the current and voltage mutation rates (di / dt) during the switching process, thereby achieving improved anti-magnetic interference performance.

[0049] In some possible embodiments, as shown in FIG3 , the converter circuit includes: a first switch tube Q1, a second switch tube Q2, a resonant capacitor Cr, a second transformer T2, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a first node A, a second node B, a third node C, and a second capacitor C2;

[0050] The first terminal 1 of the first switching tube Q1 and the second switching tube Q2 is a drain, the second terminal 2 is a source, and the third terminal 3 is a gate.

[0051] The second transformer T2 is a switching transformer. As shown in FIG2 , the left side of the second transformer T2 is the primary side of the second transformer T2 , and the right side of the second transformer T2 is the secondary side of the second transformer T2 .

[0052] The first end 1 of the first switch tube Q1 is the voltage input end of the converter circuit, and the second end 2 of the first switch tube Q1 is electrically connected to the first end 1 of the second opening tube Q2 and the first end 1 of the second transformer T2;

[0053] The third terminal 3 of the first switch tube Q1 and the third terminal 3 of the second switch tube Q2 are frequency input terminals of the converter circuit;

[0054] The second end 2 of the second transformer T2 and one end of the resonant capacitor Cr are electrically connected to the third node C; the other end of the resonant capacitor Cr and the second end 2 of the second switch tube Q2 are used to be electrically connected to the input common terminal GND_HV;

[0055] The third end 3 of the second transformer T2 is electrically connected to the first end 1 of the first diode D1 and the second end 2 of the third diode D3. The second end 2 of the first diode D1, the second end 2 of the second diode D2, and one end 1 of the second capacitor C2 are electrically connected to the first node A. The first node A is the voltage output end of the converter circuit.

[0056] The fourth end 4 of the second transformer T2 is electrically connected to the first end 1 of the second diode D2 and the second end 2 of the fourth diode D4. The first end 1 of the third diode D3, the first end 1 of the fourth diode D4, and the other end of the second capacitor C2 are electrically connected to the second node B. The second node B is used to be electrically connected to the output common terminal GND_OUT.

[0057] The first node A and the third node C are feedback output terminals of the converter circuit.

[0058] Compared to the converter circuit shown in FIG2 , the embodiment of the present application performs a unified magnetic integration design on the switching transformer and the resonant inductor to make the physical form of the converter circuit simpler and form a resonant converter. In the unified magnetic integration design of the converter circuit shown in FIG3 , when designing the transformer, the leakage inductance of the second transformer T2 is appropriately controlled so that the leakage inductance is equal to the set Lr value, and this leakage inductance is used to achieve the purpose of realizing the first inductance Lr in FIG2 ; this method is equivalent to changing the parameters of the primary side of the transformer so that it is equivalent to the second inductor Lm1 in parallel with FIG2 and the first inductor Lr in FIG2 in series. Therefore, after the magnetic integration design, the primary leakage inductance of the second transformer T2 is equal to Lr, and the primary inductance of the second transformer T2 is equal to Lm1.

[0059] In FIG3 , the first switch tube Q1 , the second transformer T2 , the resonant capacitor Cr and the second switch tube Q2 form a second resonant cavity loop.

[0060] The second resonant cavity loop has two natural frequencies: a first frequency and a second frequency.

[0061] The first frequency is the resonant frequency F of the second transformer T2's primary leakage inductance Lr and resonant capacitor Cr in series. r ,Right now

[0062] The second frequency is the resonant frequency F of the primary leakage inductance Lr of the second transformer T2, the primary inductance Lm1 of the second transformer T2 and the resonant capacitor Cr. m ,Right now

[0063] The converter circuit shown in Figure 3 adjusts the transformer's primary parameters, making the transformer's primary coil and the two resonant inductors in Figure 2 equivalent to a single circuit element. This reduces the size and weight of the on-board charger, achieving higher energy density, while also minimizing losses in the power switches. A higher switching frequency for the power switches reduces the system's size. By properly designing the electromagnetic parameters, the resonant current approaches a sinusoidal pattern, enabling zero-voltage / zero-current switching of the converter's power switches. Simultaneously, the rectifier diodes on the secondary side of the switching transformer are turned on and off at zero current, minimizing losses during the rectifier diode turn-on and turn-off processes. This significantly improves the converter's efficiency.

[0064] As shown in FIG. 2 or FIG. 3 , the first diode D1 , the second diode D2 , the third diode D3 and the fourth diode D4 are rectifier diodes.

[0065] The first end 1 of the first diode D1 , the second diode D2 , the third diode D3 and the fourth diode D4 is an anode, and the second end 2 is a cathode.

[0066] As shown in FIG2 or FIG3, the converter circuit provided in the embodiment of the present application designs the switching converter as a semi-LLC topology, and by designing reasonable parameters of the resonant inductor (first inductor Lr and second inductor Lm1) and the resonant capacitor Cr to meet the load requirements, the primary current of the switching transformer (first transformer T1 or second transformer T2) tends to change in a sinusoidal manner, thereby enabling the power switch MOS tube (first switch tube Q1 and second switch tube Q2) to achieve zero voltage / zero current turn-on and turn-off within the load range, ultimately significantly reducing the overlapping area where the current and voltage are not zero.

[0067] As shown in FIG4 , the first control circuit includes: a control unit U1, a first capacitor C1, a fourth capacitor C4, a seventh capacitor C7, a ninth capacitor C9, a tenth capacitor C10, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, an eleventh resistor R11, and a twelfth resistor R12;

[0068] The seventh pin 7 of the control unit U1 is electrically connected to one end of the fifth resistor R5 and one end of the sixth resistor R6. The other end of the fifth resistor R5 is a voltage input end of the first control circuit; the other end of the sixth resistor R6 is electrically connected to the input common end GND_HV.

[0069] The first pin 1 of the control unit U1 is electrically connected to one end of the tenth capacitor C10 and one end of the twelfth resistor R12; the second pin 2 of the control unit U1 is electrically connected to one end of the eleventh resistor R11 and one end of the ninth capacitor C9; the third pin 3 of the control unit U1 is electrically connected to one end of the seventh capacitor C7; the other end of the tenth capacitor C10, the other end of the eleventh resistor R11, the other end of the ninth capacitor C9, and the other end of the seventh capacitor C7 are electrically connected to the input common terminal GND_HV;

[0070] The fourth pin 4 of the control unit U1 is electrically connected to the other end of the twelfth resistor R12 and one end of the seventh resistor R7, and the other end of the seventh resistor R7 is electrically connected to the input common terminal GND_HV;

[0071] The fifth pin 5 of the control unit U1 is electrically connected to one end of the eighth resistor R8, and the other end of the eighth resistor R8 is electrically connected to the fourth pin 4 of the control unit U1; the fifth pin 5 and the sixth pin 6 of the control unit U1 are feedback input terminals of the first control circuit;

[0072] The eighth pin 8 and the tenth pin 10 of the control unit U1 are used to be electrically connected to the input common terminal GND_HV;

[0073] The eleventh pin 11 of the control unit U1 is electrically connected to the third end 3 of the second switch tube Q2; the twelfth pin 12 of the control unit U1 is used to receive the first voltage VCC; the fourteenth pin 14 of the control unit U1 is electrically connected to the second end 2 of the first switch tube Q2 and the first end 1 of the second opening tube Q1; the fifteenth pin 15 of the control unit U1 is electrically connected to the third end of the first switch tube Q1;

[0074] The sixteenth pin 16 of the control unit U1 is electrically connected to one end of the first capacitor C1, the other end of the first capacitor C1 is electrically connected to the fourteenth pin 14, the fourteenth pin 14 is also electrically connected to one end of the fourth capacitor C4, and the other end of the fourth capacitor C4 is electrically connected to the ninth pin 9 of the control unit U1;

[0075] The eleventh pin 11 and the fifteenth pin 15 are frequency output terminals of the first control circuit.

[0076] The first voltage VCC is 12V.

[0077] As shown in FIG4 , the feedback circuit includes: a sixth capacitor C6, a first resistor R1, a fourth resistor R4, a second resistor R2, a third resistor R3, a ninth resistor R9, a tenth resistor R10, an eighth capacitor C8, a phototransistor U2, and a voltage reference regulator U3;

[0078] One end of the sixth capacitor C6 is electrically connected to the third node C, the other end of the sixth capacitor C6 is electrically connected to one end of the first resistor R1 and one end of the fourth resistor R4, and the other end of the fourth resistor R4 is electrically connected to the sixth pin 6 of the control unit U1;

[0079] A first terminal 1 of the voltage reference regulator U3 is electrically connected to one end of a ninth resistor R9, one end of a tenth resistor R10, and a first terminal 1 of the phototransistor U2; the other end of the tenth resistor R10 is electrically connected to one end of an eighth capacitor C8, and the other end of the eighth capacitor C8 is electrically connected to the second terminal 2 of the voltage reference regulator U3, one end of the second resistor R2, and one end of the third resistor R3;

[0080] The other end of the second resistor R2, the other end of the ninth resistor R9 and the first node A are electrically connected;

[0081] The other end of the third resistor R3 is electrically connected to the second node B;

[0082] The second terminal 2 of the phototransistor U2 and the third terminal 3 of the voltage reference regulator U3 are used to be electrically connected to the output common terminal GND_OUT;

[0083] The third terminal 3 of the phototransistor U2 and the other end of the first resistor R1 are used to be electrically connected to the input common terminal GND_HV;

[0084] The fourth terminal 4 of the phototransistor U2 is electrically connected to the fifth pin 5 of the control unit U1 .

[0085] For example, in the converter circuit shown in FIG4 , the primary inductance of the second transformer is 75uH, and the primary leakage inductance of the second transformer is 10uH. Therefore, Lr of the second resonant cavity loop is 10uH, and Lm1 is 75uH. The resonant capacitance Cr is 133nF. According to the calculation formula of the first frequency and the second frequency, the first frequency F is obtained as follows: r =138KHZ, second frequency F m =47KHZ.

[0086] The control unit includes a pulse modulator. For example, the control unit is an HR1001A pulse modulator. The embodiments of the present application do not specifically limit the control unit. Any device that can implement the functions of the control unit of the present application is within the scope of protection of the present application.

[0087] When the converter control circuit of the embodiment of the present application is working, a control unit is used to realize frequency conversion modulation of the conversion working pulse; when working, the primary side peak current and secondary side output voltage of the transformer in the converter circuit are fed back through the feedback circuit loop to realize dual-loop closed-loop control.

[0088] The embodiment of the present application realizes the frequency conversion control of the converter circuit by connecting the control unit. The control unit is used to generate the target frequency Fs and input the target frequency Fs into the resonant cavity loop of the converter circuit. Since the first switch tube and the second switch tube are constantly switched on and off during operation, the control unit is used to control the normal operation of the first switch tube and the second switch tube to ensure that the target frequency Fs is greater than the second frequency Fs. m This results in two working modes, namely the first working mode and the second working mode.

[0089] The target frequency input by the control unit to the converter circuit belongs to the first frequency range, and the operating mode of the converter control circuit is the first operating mode. The first operating mode is suitable for light load conditions where the required charging speed is low and the amount of electricity required to be charged is small. The first frequency range is obtained by the first frequency and the second frequency. For example, the first frequency range is greater than the second frequency F m and is less than the first frequency F r .

[0090] The target frequency belongs to the second frequency range, and the operating mode of the converter control circuit is the second operating mode. The second operating mode is suitable for heavy load conditions where the required charging speed is high and the required amount of charged electricity is large. The second frequency range is obtained from the second frequency. For example, the second frequency range is greater than the first frequency F r .

[0091] FIG5 is a schematic diagram of operating waveforms of the resonant cavity circuit of the converter circuit in the first operating mode according to an embodiment of the present invention. One switching cycle can be divided into eight modes, namely, mode 1-1, mode 1-2, mode 1-3, mode 1-4, mode 1-5, mode 1-6, mode 1-7, and mode 1-8. As can be seen from the waveforms shown in FIG5 :

[0092] 1) Mode 1-1: Time t0~t1:

[0093] Before time t0, the first switch tube Q1 is turned on, and the resonant current i of the first inductor Lr is Lr and the resonant current i of the second inductor Lm1 Lm is a negative value, and |i Lr |>|i Lm |, the voltage of the second inductor Lm1 is clamped to a negative value by the turned-on second diode D2 and third diode D3, and therefore does not participate in the resonance.

[0094] At time t0, the resonant current i Lr and the resonant current i LmThe second diode D2 and the third diode D3 are cut off, and the first inductor Lr, the second inductor Lm1 and the resonant capacitor Cr form a resonant circuit through the second switch tube Q2. Because the inductance of the second inductor Lm1 is large, the resonant period is large, and the resonant current i on the first inductor Lr is large. Lr No significant changes were observed at this stage.

[0095] 2) Mode 1-2: Time t1 to t2:

[0096] At time t1, the second switch Q2 turns off. Because the parasitic capacitance (the junction capacitance between the drain and source) of the first and second switches Q1 and Q2 is small, the resonant current linearly discharges the parasitic capacitance of the first switch Q1 and linearly charges the parasitic capacitance of the second switch Q2. During this process, the terminal voltage of the first switch Q1 gradually decreases, while the terminal voltage of the second switch Q2 gradually increases. Therefore, the second switch Q2 achieves zero-voltage turn-off. At time t2, the voltage across the resonant cavity, UA(t2), and the voltage across the resonant capacitor, Cr, Ucr(t2), are equal.

[0097] 3) Mode 1-3: Time t2 to t3:

[0098] After time t2, the resonant cavity input voltage UA continues to increase, the voltage acting on the second inductor Lm1 is greater than zero, and the transformer primary voltage is greater than zero, so the first diode D1 and the fourth diode D4 on the transformer secondary side are turned on. After that, the voltage of the second inductor Lm1 becomes clamped at KtUo (Kt is the transformer ratio). Therefore, during this period, the resonant current i Lm The first inductor Lr and the resonant capacitor Cr continue to charge the parasitic capacitance of the first switch tube Q1 and the parasitic capacitance of the second switch tube Q2. At time t3, the resonant cavity input voltage UA is equal to Ui, and the mode ends. Where Ui represents the input voltage VBUS_HV; U O Indicates the output voltage VCC_OUT.

[0099] 4) Mode 1-4: Time t3-t4:

[0100] After time t3, the freewheeling diode in the first switch tube Q1 is turned on, so the resonant current i Lr In the stage where ΔV is negative, that is, the freewheeling diode in the first switch tube Q1 is turned on, the first switch tube Q1 can be turned on with zero voltage and zero current.

[0101] 5) Modes 1-5, 1-6, 1-7, and 1-8 are the second half of the cycle, which are symmetrical with the center of the first half of the cycle relative to a certain point on the horizontal axis and are not repeated here.

[0102] FIG6 is a schematic diagram of the operating waveforms of the resonant cavity loop of the converter circuit in the second operating mode according to an embodiment of the present invention. One switching cycle can be divided into six modes, namely, mode 2-1, mode 2-2, mode 2-3, mode 2-4, mode 2-5, and mode 2-6. As can be seen from the waveforms shown in FIG6 :

[0103] 1) Mode 2-1: Time t0~t1:

[0104] Before time t0, the resonant current i Lr Greater than the resonant current i Lm , transformer primary current i p =i Lr -i Lm , so i p >0, so the first diode D1 and the fourth diode D4 on the secondary side of the transformer are turned on. Since the first switch tube Q1 is turned off and the second switch tube Q2 is turned on, and the resonant current i Lr is positive, so the freewheeling diode in the second switch tube Q2 is turned on.

[0105] At time t0, the resonant current i Lr and the resonant current i Lm When the values ​​of the first and fourth diodes D1 and D4 on the secondary side of the transformer are equal and positive, the resonant current continues to decrease, and the current on the primary side of the transformer becomes negative. The second and third diodes D2 and D3 on the secondary side are turned on, and the first inductor Lr and the resonant capacitor Cr continue to resonate. The voltage on the resonant cavity loop is -0.5Ui+KtUo. Where Ui represents the resonant cavity input voltage UA equal to Ui at time t3 in mode 1-3; KtUo represents the voltage of the second inductor Lm1 between time t2 and t3 in mode 1-3, which is clamped to KtUo.

[0106] When the resonant current i Lr After changing from positive to negative, the freewheeling diode in the second switch tube Q2 is cut off. In this stage, the voltage of the second inductor Lm1 is clamped at -KtU, and the resonant current i Lm It decreases linearly, and when it reaches time t1, the second switch tube Q2 is turned off, and the mode ends.

[0107] 2) Mode 2-2: Time t1 to t2:

[0108] At time t1, the second switch tube Q2 is turned off, and the resonant current i Lr The parasitic capacitance of the first switch Q1 is linearly discharged, while the parasitic capacitance of the second switch Q2 is linearly charged. During this process, the terminal voltage of the first switch Q1 gradually decreases, while the terminal voltage of the second switch Q2 gradually increases, thus achieving zero-voltage shutdown of the second switch Q2. At time t2, the resonant cavity input voltage Ua(t2) equals Ui.

[0109] 3) Mode 2-3: Time t2 to t3:

[0110] After time t2, the freewheeling diode in the first switch tube Q1 is turned on, so the terminal voltage of the first switch tube Q1 is zero. At this time, turning on the first switch tube Q1 can achieve zero voltage / zero current turn-on. This mode continues until time t3, at which time i Lr =i Lm .

[0111] 4) Modes 2-4, 2-5, and 2-6 are the second half of the cycle. Their principles are symmetrical with respect to a certain point on the horizontal axis with respect to the first half of the cycle and will not be described here.

[0112] When a higher output voltage is required, the control unit lowers the target frequency, and vice versa. The present embodiment of the application rationally designs the parameters of the converter control circuit so that the converter's switching frequency and resonant frequency meet the aforementioned zero-voltage shutdown and zero-voltage / zero-current start conditions, thereby meeting the required voltage output.

[0113] The output frequency of the control unit is set by the parameters of the seventh resistor R7, the eighth resistor R8 and the seventh capacitor C7. The minimum frequency output by the control unit is: The maximum frequency output by the control unit is:

[0114] In the converter circuit, the transformer's primary current is sampled via the sixth capacitor C6, the first resistor R1, and the fourth resistor R4 before being fed into the control unit as feedback current. The transformer's secondary output voltage is sampled via the second and third resistors R2 and R3. The voltage reference of the voltage reference regulator U3 is then integrated by the tenth resistor R10 and the eighth capacitor C8. The output voltage, after passing through the phototransistor U2, is fed back to the control unit as feedback voltage. Therefore, the control unit, through the combined effects of the feedback current and voltage, generates a target frequency that satisfies either the first or second operating mode, controlling the on / off switching of the first and second switching transistors Q1 and Q2, thereby achieving energy conversion.

[0115] When charging is not required, the first capacitor C1 accumulates charge to feed back current to the control unit, thereby stopping the output of the target frequency Fs.

[0116] Because the frequency of the modulation (control pulse) generated by the control unit can make the resonant cavity resonate reasonably, the first switch tube Q1 and the second switch tube Q2 can realize the opening and closing of the power switch tube at the zero voltage / zero current point under the action of the resonant current, that is, the softening of the power switch is achieved. Due to the softening of the power switch, the overlapping area of ​​the voltage and current of the power switch tube in the switching process is reduced, thereby greatly reducing the loss of the power switch tube, and thus greatly improving the efficiency of the converter. According to the embodiment of the present application, the converter can easily achieve an efficiency of more than 94%, and the peak efficiency can reach more than 96%.

[0117] In a technical solution of a converter control circuit provided by an embodiment of the present invention, since the converter circuit has a resonant cavity loop formed by inductance and capacitance, the phase of the current is delayed, thereby making the phase of the current of the switching tube consistent with the phase of the switching tube voltage, thereby significantly reducing the energy consumption of the converter and improving the conversion efficiency of the converter.

[0118] FIG7 is a schematic diagram of the structure of a converter provided in an embodiment of the present invention. As shown in FIG7 , converter 400 includes a converter control circuit 401. Converter control circuit 401 is the converter control circuit shown in FIG1-4 . A detailed description can be found in the aforementioned converter control circuit embodiments and will not be repeated here.

[0119] The above description is only a preferred embodiment of this specification and is not intended to limit this specification. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this specification should be included in the scope of protection of this specification.

Claims

1. A converter control circuit, characterized in that, The converter control circuit includes: a first control circuit, a feedback circuit, and a converter circuit; The voltage input terminal of the first control circuit and the voltage input terminal of the converter circuit are used to connect to an input voltage; The frequency output terminal of the first control circuit is electrically connected to the frequency input terminal of the converter circuit, and the voltage output terminal of the converter circuit is used to be electrically connected to a load; The feedback output terminal of the converter circuit is electrically connected to the feedback input terminal of the feedback circuit, and the feedback output terminal of the feedback circuit is electrically connected to the feedback input terminal of the first control circuit; the first control circuit includes a control unit, and the control unit is used to receive the feedback voltage and feedback current transmitted by the feedback circuit, and adjust the target frequency input to the converter circuit according to the feedback voltage and the feedback current to control the working mode of the converter circuit.

2. The converter control circuit according to claim 1, wherein The converter circuit includes: a first switch tube, a second switch tube, a first inductor, a second inductor, a resonant capacitor, a first transformer, a first diode, a second diode, a third diode, a fourth diode, a first node, a second node, a third node, and a second capacitor; The first end of the first switch tube is the voltage input terminal of the converter circuit, and the second end of the first switch tube is electrically connected to the first end of the second switch tube and one end of the first inductor; The third ends of the first switch tube and the second switch tube are the frequency input terminals of the converter circuit; The other end of the first inductor is electrically connected to one end of the second inductor and the first end of the first transformer; the other end of the second inductor, the second end of the first transformer, and one end of the resonant capacitor are electrically connected to the third node; the other end of the resonant capacitor and the second end of the second switch tube are used to be electrically connected to an input common terminal; The third end of the first transformer is electrically connected to the first end of the first diode and the second end of the third diode, and the second end of the first diode, the second end of the second diode, and one end of the second capacitor are electrically connected to the first node, and the first node is the voltage output terminal of the converter circuit; The fourth end of the first transformer is electrically connected to the first end of the second diode and the second end of the fourth diode, and the first end of the third diode, the first end of the fourth diode, and the other end of the second capacitor are electrically connected to the second node, and the second node is used to be electrically connected to an output common terminal; Wherein, the first node and the third node are the feedback output terminals of the converter circuit.

3. The converter control circuit according to claim 1, wherein The converter circuit includes: a first switch tube, a second switch tube, a resonant capacitor, a second transformer, a first diode, a second diode, a third diode, a fourth diode, a first node, a second node, a third node, and a second capacitor; The first end of the first switch tube is the voltage input terminal of the converter circuit, and the second end of the first switch tube is electrically connected to the first end of the second switch tube and the first end of the second transformer; The third ends of the first switch tube and the second switch tube are the frequency input terminals of the converter circuit; The second end of the second transformer, one end of the resonant capacitor are electrically connected to the third node; the other end of the resonant capacitor and the second end of the second switching transistor are used to be electrically connected to the input common terminal; The third end of the second transformer is electrically connected to the first end of the first diode and the second end of the third diode. The second end of the first diode, the second end of the second diode and one end of the second capacitor are electrically connected to the first node, and the first node is the voltage output terminal of the converter circuit; The fourth end of the second transformer is electrically connected to the first end of the second diode and the second end of the fourth diode. The first end of the third diode, the first end of the fourth diode, the other end of the second capacitor are electrically connected to the second node, and the second node is used to be electrically connected to the output common terminal; Wherein, the first node and the third node are the feedback output terminals of the converter circuit.

4. The converter control circuit according to any one of claims 1-3, characterized in that, The first control circuit includes: a control unit, a first capacitor, a fourth capacitor, a seventh capacitor, a ninth capacitor, a tenth capacitor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, an eleventh resistor, a twelfth resistor; The seventh pin of the control unit is electrically connected to one end of the fifth resistor and one end of the sixth resistor. The other end of the fifth resistor is the voltage input terminal of the first control circuit; the other end of the sixth resistor is used to be electrically connected to the input common terminal; The first pin of the control unit is electrically connected to one end of the tenth capacitor and one end of the twelfth resistor; the second pin of the control unit is electrically connected to one end of the eleventh resistor and one end of the ninth capacitor; the third pin of the control unit is electrically connected to one end of the seventh capacitor; the other ends of the tenth capacitor, the eleventh resistor, the ninth capacitor and the seventh capacitor are electrically connected to the input common terminal; The fourth pin of the control unit is electrically connected to the other end of the twelfth resistor and one end of the seventh resistor, and the other end of the seventh resistor is electrically connected to the input common terminal; The fifth pin of the control unit is electrically connected to one end of the eighth resistor, and the other end of the eighth resistor is electrically connected to the fourth pin of the control unit; the fifth pin and the sixth pin of the control unit are the feedback input terminals of the first control circuit; The eighth pin and the tenth pin of the control unit are used to be electrically connected to the input common terminal; The eleventh pin of the control unit is electrically connected to the third end of the second switching transistor; the twelfth pin of the control unit is used to access a first voltage; the fourteenth pin of the control unit is electrically connected to the second end of the first switching transistor and the first end of the second switching transistor; the fifteenth pin of the control unit is electrically connected to the third end of the first switching transistor; The sixteenth pin of the control unit is electrically connected to one end of the first capacitor, the other end of the first capacitor is electrically connected to the fourteenth pin, the fourteenth pin is also electrically connected to one end of the fourth capacitor, and the other end of the fourth capacitor is electrically connected to the ninth pin of the control unit; Among them, the eleventh pin and the fifteenth pin are the frequency output terminals of the first control circuit.

5. The converter control circuit according to any one of claims 1-3, characterized in that, The feedback circuit includes: a sixth capacitor, a first resistor, a fourth resistor, a second resistor, a third resistor, a ninth resistor, a tenth resistor, an eighth capacitor, a phototransistor, and a voltage reference regulator; One end of the sixth capacitor is electrically connected to the third node, and the other end of the sixth capacitor is electrically connected to one end of the first resistor and one end of the fourth resistor, and the other end of the fourth resistor is electrically connected to the sixth pin of the control unit; The first end of the voltage reference regulator is electrically connected to one end of the ninth resistor, one end of the tenth resistor, and the first end of the phototransistor; the other end of the tenth resistor is electrically connected to one end of the eighth capacitor, and the other end of the eighth capacitor is electrically connected to the second end of the voltage reference regulator, one end of the second resistor, and one end of the third resistor; The other ends of the second resistor and the ninth resistor are electrically connected to the first node; The other end of the third resistor is electrically connected to the second node; The second end of the phototransistor and the third end of the voltage reference regulator are used to be electrically connected to the output common terminal; The third end of the phototransistor and the other end of the first resistor are used to be electrically connected to the input common terminal; The fourth end of the phototransistor is electrically connected to the fifth pin of the control unit.

6. The converter control circuit according to any one of claims 1-5, characterized in that, The target frequency belongs to a first frequency range, the first frequency range is obtained from a first frequency and a second frequency, and the working mode of the converter control circuit is a first working mode; the target frequency belongs to a second frequency range, the second frequency range is obtained from the second frequency, and the working mode of the converter control circuit is a second working mode.

7. The converter control circuit according to claim 2, wherein The first frequency is the resonance frequency of the first inductor and the resonance capacitor; the second frequency is the resonance frequency of the first inductor, the second inductor, and the resonance capacitor.

8. The converter control circuit according to claim 3, wherein, The first frequency is the resonance frequency of the primary leakage inductance of the second transformer and the resonance capacitor; the second frequency is the resonance frequency of the primary leakage inductance of the second transformer, the primary inductance of the second transformer, and the resonance capacitor.

9. The converter control circuit according to claim 1, wherein, The control unit includes a pulse modulator.

10. A charger, characterized in that, Including: The converter control circuit according to any one of claims 1-9.

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