Hybrid converter and control method thereof

Abstract

The invention discloses a hybrid converter and a control method thereof, which are mainly applied to a high-voltage input high-power scene. The hybrid converter comprises a step-down circuit, a capacitor C1, an active clamping circuit, a first coupling circuit and a second coupling circuit. The first coupling circuit is a voltage feed coupling circuit, and the second coupling circuit is a current feed coupling circuit. The primary side switching circuits of the first coupling circuit and the second coupling circuit are connected in series, and the secondary side rectifying circuits are connected in parallel, so that high-efficiency output of a high-voltage high-power product can be realized, meanwhile, the power density of the product can be improved, the device model selection and cost advantages are obvious, and good economic and social benefits are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of power electronic converters, and in particular relates to a hybrid converter and a control method thereof. Background Art

[0002] Switching power supplies have become an integral part of various industries. Commonly used isolated topologies for switching power supplies include BUCK+full-bridge, BUCK+half-bridge, and BUCK+push-pull cascade topologies. However, for high-voltage input and high-power applications, conventional isolated topologies cannot meet these requirements due to large device size and the inability to achieve high power density. Consequently, product development typically requires upgrading and adjusting related technical solutions based on changes in application scenarios.

[0003] Please refer to Figure 1 Chinese patent application publication number CN114221549A discloses a cascade circuit and its control method, specifically a buck-boost cascade circuit. The buck-boost cascade circuit includes a front-stage buck circuit and a rear-stage isolated switch power supply circuit. To achieve buck-boost mode control, the cascade circuit includes at least switch S1, switch S2, a power inductor L, and an isolated switch power supply circuit. Switch S3 is a boost main circuit, and switch S4 and capacitor C1 form an active clamping circuit. Specifically, the isolated switch power supply circuit includes a primary switching circuit, transformer T1, and a secondary rectifier circuit. The cascade circuit employs a current-feed method. The primary switches in the rear-stage isolated switch circuit have a common conduction portion, which serves as an excitation element in boost mode and provides a freewheeling path for the inductor current in buck mode.

[0004] In summary, Figure 1 The cascade circuit shown is directly applied to high voltage input and high power (>1kW) scenarios, but there are still drawbacks such as limited device selection, low power density, and high product development costs. In order to further adapt to high voltage and high power applications with efficient output, Figure 1 The cascade circuit shown in the figure makes further technical breakthroughs, thereby solving the technical solution problems of high-voltage and high-power product development; Summary of the Invention

[0005] In view of this, the present invention provides a hybrid converter and control method, which can achieve efficient output of high-voltage and high-power products, while improving product power density, with obvious device selection and cost advantages, and good economic and social benefits.

[0006] The technical solutions of the present invention for solving the above-mentioned technical problems are as follows:

[0007] In a first aspect, the present invention provides a hybrid converter, comprising a step-down circuit, a capacitor C1, an active clamping circuit, a first coupling circuit, and a second coupling circuit;

[0008] The first output terminal of the step-down circuit is connected to the first input terminal of the first coupling circuit, the second input terminal of the first coupling circuit is connected to the first input terminal of the second coupling circuit, and the second output terminal of the step-down circuit is connected to the second input terminal of the second coupling circuit; or the first output terminal of the step-down circuit is connected to the first input terminal of the second coupling circuit, the second input terminal of the second coupling circuit is connected to the first input terminal of the first coupling circuit, and the second output terminal of the step-down circuit is connected to the second input terminal of the first coupling circuit;

[0009] The capacitor C1 is connected between the first input terminal and the second input terminal of the first coupling circuit, and the active clamping circuit is connected between the first input terminal and the second input terminal of the second coupling circuit;

[0010] The first coupling circuit is a voltage-fed coupling circuit, and the second coupling circuit is a current-fed coupling circuit.

[0011] Optionally, the step-down circuit includes a switch tube S1, a switch tube S2 and an inductor L;

[0012] The first end of the switch tube S1 serves as the positive input end of the hybrid converter, the second end of the switch tube S1 is connected to the first end of the switch tube S2 and the first end of the inductor L respectively, and the second end of the switch tube S2 serves as the input ground of the hybrid converter;

[0013] The second end of the inductor L is connected to the first end of the first coupling circuit, and the second end of the switch tube S2 is connected to the second end of the second coupling circuit; or the second end of the inductor L is connected to the first end of the second coupling circuit, and the second end of the switch tube S2 is connected to the second end of the first coupling circuit.

[0014] Optionally, the first coupling circuit includes a first switching circuit, a transformer T1, a first rectifier circuit and an output capacitor Co1 connected in sequence, the first input end of the first switching circuit is connected to the first end of the capacitor C1, the second input end of the first switching circuit is connected to the second end of the capacitor C1, the first end of the output capacitor Co1 and the first output end of the second coupling circuit are connected together as the positive output end of the hybrid converter, and the second end of the output capacitor Co1 and the second output end of the second coupling circuit are connected together as the negative output end of the hybrid converter.

[0015] Optionally, the first switching circuit includes a DC blocking capacitor Cr connected in series with the switching tube in the first switching circuit.

[0016] Optionally, the DC blocking capacitor Cr is further connected in series with a resonant inductor Lr, or the parasitic inductance of the transformer T1 is used as the resonant inductor Lr.

[0017] Optionally, the second coupling circuit includes a second switching circuit, a transformer T2, a second rectifier circuit and an output capacitor Co2 connected in sequence, the first input end of the second switching circuit is connected to the first end of the capacitor C2, the second input end of the second switching circuit is connected to the second end of the switch tube S4, the first output end of the first coupling circuit and the first end of the output capacitor Co2 are connected together as the positive output end of the hybrid converter, and the second output end of the first coupling circuit and the second end of the output capacitor Co2 are connected together as the negative output end of the hybrid converter.

[0018] Optionally, the active clamping circuit includes a capacitor C2 and a switch tube S4, the first end of the capacitor C2 is respectively connected to the second end of the capacitor C1, the second end of the first coupling circuit and the first end of the second coupling circuit, the second end of the capacitor C2 is connected to the first end of the switch tube S4, and the second end of the switch tube S4 is connected to the second input end of the second coupling circuit.

[0019] Optionally, the hybrid converter further includes a switch tube S3 , the first input end of the second coupling circuit is connected to the first end of the switch tube S3 , and the second input end of the second coupling circuit is connected to the second end of the switch tube S3 .

[0020] In a second aspect, the present invention further provides a hybrid converter, comprising a step-down circuit, a capacitor C1, an active clamping circuit, a first coupling circuit, and a second coupling circuit;

[0021] The first output terminal of the step-down circuit is connected to the first input terminal of the first coupling circuit, the second input terminal of the first coupling circuit is connected to the first input terminal of the second coupling circuit, and the second output terminal of the step-down circuit is connected to the second input terminal of the second coupling circuit; or the first output terminal of the step-down circuit is connected to the first input terminal of the second coupling circuit, the second input terminal of the second coupling circuit is connected to the first input terminal of the first coupling circuit, and the second output terminal of the step-down circuit is connected to the second input terminal of the first coupling circuit;

[0022] The capacitor C1 is connected between the first input terminal and the second input terminal of the first coupling circuit, and the active clamping circuit is connected between the first input terminal and the second input terminal of the second coupling circuit; wherein the first coupling circuit is a voltage-fed coupling circuit, and the second coupling circuit is a current-fed coupling circuit;

[0023] The step-down circuit includes a switch S1, a switch S2, and an inductor L; the first end of the switch S1 serves as the positive input end of the hybrid converter, the second end of the switch S1 is connected to the first end of the switch S2 and the first end of the inductor L, respectively, and the second end of the switch S2 serves as the input ground of the hybrid converter; the second end of the inductor L is connected to the first end of the first coupling circuit, and the second end of the switch S2 is connected to the second end of the second coupling circuit; or the second end of the inductor L is connected to the first end of the second coupling circuit, and the second end of the switch S2 is connected to the second end of the first coupling circuit.

[0024] The first coupling circuit includes a first switching circuit, a transformer T1, a first rectifier circuit, and an output capacitor Co1 connected in sequence, wherein a first input end of the first switching circuit is connected to a first end of the capacitor C1, and a second input end of the first switching circuit is connected to a second end of the capacitor C1;

[0025] The second coupling circuit includes a second switching circuit, a transformer T2, a second rectifier circuit and an output capacitor Co2 connected in sequence, the first input end of the second switching circuit is connected to the first end of the capacitor C2, the second input end of the second switching circuit is connected to the second end of the switch tube S4, the first end of the output capacitor Co1 and the first end of the output capacitor Co2 are connected together as the positive output end of the hybrid converter, and the second end of the output capacitor Co1 and the second end of the output capacitor Co2 are connected together as the negative output end of the hybrid converter.

[0026] In a third aspect, the present invention further provides a control method applied to the hybrid converter according to the second aspect, the control method comprising:

[0027] When the hybrid converter is in the buck mode, the switch S4 is turned on or partially turned on; in the excitation phase, the switch S2 is turned off, and the switch S1, the first switch circuit, and some of the switch tubes in the second switch circuit are turned on, transferring energy from the primary side to the secondary side through the transformer; in the demagnetization phase, the switch S1 is turned off, and the switch S2, the first switch circuit, and some of the switch tubes in the second switch circuit are turned on, transferring inductive energy from the primary side to the secondary side through the transformer; and when the hybrid converter operates in the buck mode, the duty cycle of the switch S1 and the switch S2 changes with the input voltage and output load, while the frequency remains unchanged; the switch tube in the first switch circuit operates at a first fixed duty cycle, and the switch tube in the second switch circuit operates at a second fixed duty cycle;

[0028] When the hybrid converter is in the buck-boost mode, the switch S1 operates at a set maximum duty cycle, and the switch S2 complements the switch S1 and operates at a minimum duty cycle. During the excitation phase, some of the switches in the first switching circuit are turned on, the second switching circuit is turned on, and the switch S4 remains off. During the demagnetization phase, the switch S4 is turned on or partially turned on, and some of the switches in the second switching circuit are turned on. The switches in the first switching circuit operate at a first fixed duty cycle, and the duty cycle of the switches in the second switching circuit varies with input voltage and output load, while the frequency remains unchanged.

[0029] When the hybrid converter is in the boost mode, the switch tube S1 remains turned on and the switch tube S2 remains turned off; and in the excitation stage, some of the switch tubes of the first switching circuit are turned on, the second switching circuit is turned on, and the switch tube S4 remains turned off; in the demagnetization stage, the switch tube S4 is turned on or turned on for part of the time period, and some of the switch tubes of the second switching circuit are turned on; the switch tubes in the first switching circuit operate at a first fixed duty cycle, and the duty cycle of the switch tubes in the second switching circuit changes with the input voltage and output load, and the frequency remains unchanged.

[0030] Optionally, when the input terminal of the second coupling circuit is connected in parallel to the switch tube S3, the drive signal of the switch tube S3 is issued when entering the boost mode, and remains on when the second switch circuit is turned on;

[0031] Optionally, the operating frequency of the switch tube in the first coupling circuit and the operating frequency of the switch tube in the second coupling circuit are half the operating frequency of the switch tube in the step-down circuit.

[0032] Optionally, the switch tube driving signal in the first rectifier circuit is in phase with the switch tube driving signal in the first switching circuit, and the pulse width of the first rectifier circuit driving signal is less than or equal to the pulse width of the switch tube driving signal in the first switching circuit.

[0033] Optionally, the driving signal of the switch tube in the second rectifier circuit and the driving signal of the switch tube in the second switching circuit are complementary.

[0034] Optionally, the first fixed duty cycle is less than 50%, and the second fixed duty cycle is greater than 50%.

[0035] Compared with the existing technical solutions, the present invention has the following beneficial effects:

[0036] 1. Compared with the existing technology, the present invention proposes a hybrid converter that, by introducing a voltage-fed coupling circuit, can achieve low inductor current ripple in boost mode, small inductance, reduced Bm, small inductor size, and low loss. In addition, the voltage feed itself can achieve ZVS switching, which can effectively improve the efficiency and power density of power supply products.

[0037] 2. Compared with existing technologies, in high-voltage and high-power applications, the current-fed coupling circuit has a main switch tube that is turned on in the boost mode. Compared with the case without a main switch tube, the on-resistance of the switch tube through which the excitation current flows can be reduced by half, which can effectively improve power supply efficiency.

[0038] 3. Compared with the existing technology, the voltage-fed coupling circuit and the current-fed coupling circuit are connected in series on the primary side and in parallel on the secondary side. The stress on the primary side devices is low, and the device selection is advantageous, which can improve the power density of the power supply product and reduce the cost. The secondary side parallel output current has a ripple cancellation effect, which is beneficial to the output ripple index, reduces the output capacitance, and reduces the cost of the power supply product.

[0039] 4. Compared with the existing technology, the voltage-fed coupled inductor can also achieve zero-current shutdown of the secondary-side rectifier circuit by introducing a resonant inductor, which can effectively improve the efficiency of the power supply product. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is the principle diagram of the existing buck-boost cascade circuit;

[0041] Figure 2 This is a schematic diagram of the principle of a first embodiment of a hybrid converter according to the present invention;

[0042] Figure 3 This is a schematic diagram of the principle of a second embodiment of a hybrid converter according to the present invention;

[0043] Figure 4 This is a circuit diagram of a first embodiment of a hybrid converter according to the present invention;

[0044] Figure 5 This is a circuit diagram of a second embodiment of a hybrid converter according to the present invention;

[0045] Figure 6 This is a timing diagram of the buck mode operation of the first embodiment of a hybrid converter according to the present invention;

[0046] Figure 7 This is a timing diagram of the buck-boost mode operation of a first embodiment of a hybrid converter according to the present invention;

[0047] Figure 8 This is a timing diagram of the boost mode operation of the first embodiment of a hybrid converter according to the present invention;

[0048] Figure 9 This is a circuit diagram of a third embodiment of a hybrid converter according to the present invention;

[0049] Figure 10 is a circuit diagram of a fourth embodiment of a hybrid converter according to the present invention;

[0050] Figure 11 is a circuit diagram of a fifth embodiment of a hybrid converter according to the present invention;

[0051] Figure 12 is a circuit diagram of a sixth embodiment of a hybrid converter according to the present invention;

[0052] Figure 13 This is a circuit diagram of a seventh embodiment of a hybrid converter according to the present invention. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0054] Please refer to Figure 2 and Figure 3 Schematic diagrams of two hybrid converters of the present invention, the hybrid converter includes a step-down circuit 100, a capacitor C1, an active clamping circuit 200, a first coupling circuit 300 and a second coupling circuit 400;

[0055] The first output terminal of the step-down circuit 100 is connected to the first input terminal of the first coupling circuit 300, the second input terminal of the first coupling circuit 300 is connected to the first input terminal of the second coupling circuit 400, and the second output terminal of the step-down circuit 100 is connected to the second input terminal of the second coupling circuit 400; or, the first output terminal of the step-down circuit 100 is connected to the first input terminal of the second coupling circuit 400, the second input terminal of the second coupling circuit 400 is connected to the first input terminal of the first coupling circuit 300, and the second output terminal of the step-down circuit 100 is connected to the second input terminal of the first coupling circuit 300;

[0056] The capacitor C1 is connected between the first input terminal and the second input terminal of the first coupling circuit 300 , and the active clamping circuit 200 is connected between the first input terminal and the second input terminal of the second coupling circuit 400 ;

[0057] The first coupling circuit 300 is a voltage-fed coupling circuit, and the second coupling circuit 400 is a current-fed coupling circuit.

[0058] by Figure 2 Taking the diagram as an example, the buck circuit 100 mainly includes a switch tube S1, a switch tube S2, and an inductor L, as follows:

[0059] The first end of the switch tube S1 serves as the positive input end of the hybrid converter, the second end of the switch tube S1 is connected to the first end of the switch tube S2 and the first end of the inductor L respectively, and the second end of the switch tube S2 serves as the input ground of the hybrid converter;

[0060] The second end of the inductor L is connected to the first end of the first coupling circuit 300, and the second end of the switch tube S2 is connected to the second end of the second coupling circuit 400; or the second end of the inductor L is connected to the first end of the second coupling circuit 400, and the second end of the switch tube S2 is connected to the second end of the first coupling circuit 300.

[0061] In one embodiment, the first coupling circuit 300 includes a first switching circuit, a transformer T1, a first rectifier circuit, and an output capacitor Co1 connected in sequence. The first input terminal of the first switching circuit is connected to the first end of the capacitor C1, the second input terminal of the first switching circuit is connected to the second end of the capacitor C1, the first end of the output capacitor Co1 and the first output terminal of the second coupling circuit 400 are connected together to serve as the positive output terminal of the hybrid converter, and the second end of the output capacitor Co1 and the second output terminal of the second coupling circuit 400 are connected together to serve as the negative output terminal of the hybrid converter.

[0062] Preferably, the first switching circuit includes a DC blocking capacitor Cr connected in series with the switching tube.

[0063] Preferably, the DC blocking capacitor Cr is further connected in series with a resonant inductor Lr, or the parasitic inductance of the transformer T1 is used as the resonant inductor Lr.

[0064] In one embodiment, the second coupling circuit 400 includes a second switching circuit, a transformer T2, a second rectifier circuit, and an output capacitor Co2 connected in sequence. The first input end of the second switching circuit is connected to the first end of the capacitor C2, and the second input end of the second switching circuit is connected to the second end of the switch tube S4. The first output end of the first coupling circuit 300 and the first end of the output capacitor Co2 are connected together to serve as the positive output end of the hybrid converter. The second output end of the first coupling circuit 300 and the second end of the output capacitor Co2 are connected together to serve as the negative output end of the hybrid converter.

[0065] In one embodiment, the active clamping circuit 200 includes a capacitor C2 and a switch S4. The first end of the capacitor C2 is respectively connected to the second end of the capacitor C1, the second end of the first coupling circuit 300, and the first end of the second coupling circuit 400. The second end of the capacitor C2 is connected to the first end of the switch S4. The second end of the switch S4 is connected to the second input end of the second coupling circuit 400.

[0066] In one embodiment, when the switch S3 is included, the first input end of the second coupling circuit 400 is connected to the first end of the switch S3 , and the second input end of the second coupling circuit 400 is connected to the second end of the switch S3 .

[0067] Preferably, the switch tubes S1 , S2 , S3 , S4 and the switch tubes in the first switch circuit, the second switch circuit, the first rectifier circuit and the second rectifier circuit are MOS tubes, triodes or IGBTs.

[0068] It should be noted that the hybrid converter described above has a primary-side series and secondary-side parallel structure, making it particularly suitable for high-voltage input and high-power output applications. The first and second switching circuits have low component selection stress, which can reduce costs and reduce size. The secondary sides can be connected in parallel to output a higher current. The switch tube S3 acts as the main switch tube in the boost mode, turning it on and off. It is connected in parallel with the second switching circuit for inductive excitation. Compared with a circuit without the switch tube S3, the on-resistance of the switch tube in the second switching circuit when the inductive excitation current flows can be reduced by half, effectively improving power supply efficiency.

[0069] In addition, it should be noted that the first coupling circuit 300 is of the voltage-fed type, specifically, a capacitor C1 is connected in parallel to the input end of the first coupling circuit 300, and energy is mainly transferred to the output through the capacitor C1 as a voltage source; the second coupling circuit 400 is of the current-fed type, and energy is mainly transferred to the output through the inductor as a current source; in addition, an active clamping circuit 200 can be added to absorb the voltage stress of the switch tube in the second coupling when it is working; the hybrid converter of the present invention is mainly composed of a series-parallel combination of voltage-fed and current-fed circuits. If only Figure 1 In the current-fed cascade circuit shown, the inductor is magnetized in boost mode and cannot transfer energy to the output. However, after voltage feeding is introduced, during the inductor excitation period in current-fed boost mode, the switch tube in the first switching circuit of the voltage-fed type is partially turned on to transfer energy to the output. Under the same gain, after the voltage feeding is introduced, less energy is transferred to the output during the current-fed demagnetization period, the demagnetization time is shortened, and the demagnetization voltage remains unchanged. Therefore, the introduction of voltage feeding reduces the inductor current ripple compared to the single current feeding. Therefore, the inductor value can be reduced, which can reduce the maximum magnetic flux density Bm of the inductor. The inductor size is small, and the loss is also low. In addition, the voltage feeding itself can achieve ZVS opening of the primary power tube, which can effectively improve the efficiency and power density of the power supply product.

[0070] In boost mode, the voltage-fed and current-fed output currents have a ripple-cancelling effect, which is beneficial to the output ripple index, reduces the output capacitance, and reduces the cost of power supply products;

[0071] In addition, the first switching circuit in the first coupling circuit 300 is connected in series with a DC blocking capacitor to prevent transformer magnetic bias. Depending on the power circuit design, a resonant inductor or the parasitic inductance of the transformer can also be connected in series. In this case, the primary current and voltage of the first coupling circuit 300 operate in a resonant state, which is consistent with the principle of a resonant topology. The first rectifier circuit can achieve zero current shutdown, which can effectively improve the efficiency of the power supply product.

[0072] The first coupling circuit 300 includes a first switching circuit, a transformer T1, and a first rectifier circuit; the first switching circuit includes four switching tubes, which together with the transformer T1 form a full-bridge circuit; the first rectifier circuit includes four switching tubes, which together with the transformer T1 form a full-bridge rectifier circuit; Figure 4 , as follows:

[0073] The first switching circuit includes a switching tube S5-1, a switching tube S5-2, a switching tube S6-1 and a switching tube S6-2; the first rectifier circuit includes a switching tube S7-1, a switching tube S7-2, a switching tube S8-1 and a switching tube S8-2; one end of the switching tube S6-1 and one end of the switching tube S5-1 are connected together to the positive output of the step-down circuit 100100, the other end of the switching tube S6-1 and one end of the switching tube S5-2 are connected together to one end of the DC blocking capacitor Cr, the other end of the DC blocking capacitor Cr is connected to the same-name end of the primary winding of the transformer T1, the other end of the switching tube S5-1 and one end of the switching tube S6-2 are connected to the opposite-name end of the primary winding of the transformer T1, and the other end of the switching tube S5-2 is connected to the switch The other end of the transistor S6-2 is connected together to one end of the second switching circuit; one end of the switch transistor S8-1 and one end of the switch transistor S7-2 are connected to the same-name terminal of the secondary winding of the transformer T1, one end of the switch transistor S7-1 and one end of the switch transistor S8-2 are connected to the opposite-name terminal of the secondary winding of the transformer T1, the other end of the switch transistor S8-1 and the other end of the switch transistor S7-1 are connected together to one end of the output capacitor Co and serve as the positive output Vo of the hybrid converter; the other end of the switch transistor S7-2 and the other end of the switch transistor S8-2 are connected together to the other end of the output capacitor Co and serve as the negative output of the hybrid converter. The positive output of the hybrid converter and the negative output of the hybrid converter are used to provide energy to the connected load.

[0074] The second coupling circuit 400 includes a second switching circuit, a transformer T2, and a second rectifier circuit. The second switching circuit includes four switching transistors, which together with the transformer T2 form a full-bridge circuit. The second rectifier circuit includes four switching transistors, which together with the transformer T2 form a full-bridge rectifier circuit. The details are as follows:

[0075] The second switching circuit includes a switch tube S5-3, a switch tube S5-4, a switch tube S6-3 and a switch tube S6-4; the second rectifier circuit includes a switch tube S7-3, a switch tube S7-4, a switch tube S8-3 and a switch tube S8-4; one end of the switch tube S6-3 and one end of the switch tube S5-3 are connected together with the other end of the switch tube S5-2 and the other end of the switch tube S6-2; the other end of the switch tube S6-3 and one end of the switch tube S5-4 are connected together to the same-name end of the primary winding of the transformer T2; the other end of the switch tube S5-3 and one end of the switch tube S6-4 are connected to the opposite-name end of the primary winding of the transformer T2; the other end of the switch tube S5-4 and the other end of the switch tube S6-4 are connected together to The input ground of the step-down circuit 100 and the input ground of the hybrid converter; one end of the switch tube S8-3 and one end of the switch tube S7-4 are connected to the same-name terminal of the secondary winding of the transformer T2, one end of the switch tube S7-3 and one end of the switch tube S8-4 are connected to the opposite-name terminal of the secondary winding of the transformer T2, the other end of the switch tube S8-3 and the other end of the switch tube S7-3 are connected together to one end of the output capacitor Co and serve as the positive output Vo of the hybrid converter, the other end of the switch tube S7-4 and the other end of the switch tube S8-4 are connected together to the other end of the output capacitor Co and serve as the negative output of the hybrid converter, and the positive output of the hybrid converter and the negative output of the hybrid converter are used to provide energy to the connected load;

[0076] Figure 5 The following is another hybrid converter circuit schematic diagram. Figure 4 The difference between the circuit schematics is that the upper and lower connection relationships of the first coupling circuit 300 and the second coupling circuit 400 are swapped.

[0077] refer to Figures 6 to 8 In addition, an embodiment of the present invention further provides a hybrid converter control method, which includes:

[0078] When the positive input voltage of the hybrid converter is greater than the positive output voltage of the buck circuit 100, the hybrid converter operates in the buck mode. When the hybrid converter operates in the buck mode, each cycle includes at least an excitation phase and a demagnetization phase. In both the excitation phase and the demagnetization phase, the active clamp switch S4 is turned on or partially turned on. During the excitation phase, the switch S2 is turned off, while the switch S1, the first switch circuit of the first coupling circuit 300, and the second switch circuit of the second coupling circuit 400 are partially turned on, allowing energy to be transferred from the primary side to the secondary side through the transformer. During the demagnetization phase, the switch S1 is turned off, while the switch S2, the first switch circuit, and the second switch circuit are partially turned on, allowing inductive energy to be transferred from the primary side to the secondary side through the transformer. When the hybrid converter operates in the buck mode, the duty cycle of the switches S1 and S2 varies with the input voltage and output load, while the frequency remains unchanged. The switch in the first switch circuit operates at a first fixed duty cycle, and the switch in the second switch circuit operates at a second fixed duty cycle.

[0079] When the positive input voltage of the hybrid converter is close to the positive output voltage of the buck circuit 100, the hybrid converter operates in the buck-boost mode. When the hybrid converter operates in the buck-boost mode, each cycle includes at least an excitation phase and a demagnetization phase. In both the excitation phase and the demagnetization phase, the switch tube S1 maintains a set maximum duty cycle, and the switch tube S2 complements the switch tube S1 and operates at a minimum duty cycle. In the excitation phase, some of the switches in the first switching circuit are turned on, the second switching circuit is turned on, and the active clamp switch tube S4 remains off. In the demagnetization phase, the active clamp switch tube S4 is turned on or turned on for a portion of the time, and some of the switches in the second switching circuit are turned on. The switches in the first switching circuit operate at a first fixed duty cycle, and the duty cycle of the switches in the second switching circuit changes with changes in the input voltage and output load, while the frequency remains unchanged.

[0080] When the positive input voltage of the hybrid converter is less than the positive output voltage of the buck circuit 100, or when the hybrid converter operates in the buck-boost mode and the duty cycle of some switches of the second switch circuit exceeds a certain threshold, the hybrid converter enters the boost mode. When the hybrid converter operates in the boost mode, each cycle includes at least an excitation phase and a demagnetization phase. During the excitation phase and the demagnetization phase, the switch S1 remains on and the switch S2 remains off. During the excitation phase, some switches of the first switch circuit are turned on, the second switch circuit is turned on, and the active clamp switch S4 remains off. During the demagnetization phase, the active clamp switch S4 is turned on or turned on for a portion of the time, and some switches of the second switch circuit are turned on. The switches in the first switch circuit operate at a first fixed duty cycle, and the duty cycle of the switches in the second switch circuit changes with changes in the input voltage and output load, while the frequency remains unchanged.

[0081] Preferably, when the input end of the second coupling circuit 400 is connected in parallel to the switch tube S3, the drive signal of the switch tube S3 is issued when entering the boost mode, and remains on when the second switch circuit is turned on;

[0082] Preferably, the operating frequency of the switch tubes in the first coupling circuit 300 and the second coupling circuit 400 is half the operating frequency of the switch tube in the buck circuit 100;

[0083] Preferably, the first fixed duty cycle is less than 50%;

[0084] Preferably, the second fixed duty cycle is greater than 50%;

[0085] Preferably, the switch tube driving signal in the first rectifier circuit is in phase with the switch tube driving signal in the first switching circuit, and the pulse width of the first rectifier circuit driving signal is less than or equal to the pulse width of the switch tube driving signal in the first switching circuit;

[0086] Preferably, the driving signal of the switch tube in the second rectifier circuit and the driving signal of the switch tube in the second switching circuit are complementary.

[0087] refer to Figures 6 to 8 This is a working timing diagram of the first embodiment of the hybrid converter of the present invention. Figure 6 This is the buck mode working timing diagram. Figure 7 This is the working timing diagram of the buck-boost mode. Figure 8 This is the timing diagram for boost mode operation.

[0088] When the positive voltage input to the hybrid converter is greater than the positive voltage output by the buck circuit 100, the hybrid converter operates in the buck mode. When the hybrid converter operates in the buck mode, each cycle includes at least an excitation phase and a demagnetization phase. In both the excitation phase and the demagnetization phase, the switch tube S3 remains off, and the active clamp switch tube S4 is turned on for part of the period. In the excitation phase, the switch tube S2 is turned off, and the switch tubes S1, S5-1, S5-2, S5-3, and S5-4 are all turned on. During the demagnetization phase, the switch S1 is turned off, and the switch S2, the switch S5-1, the switch S5-2, the switch S5-3, and the switch S5-4 are all turned on, and the energy is transferred from the primary side to the secondary side through the transformer; during the next cycle of the excitation phase, the switch S2 is turned off, and the switch S1, the switch S6-1, the switch S6-2, the switch S6-3, and the switch S6-4 are all turned on, and the energy is transferred from the primary side to the secondary side through the transformer; during the demagnetization phase, the switch The switch S1 is turned off, and the switch S2, switch S6-1, switch S6-2, switch S6-3 and switch S6-4 are all turned on. When the hybrid converter works in the buck mode, the duty ratio of the switch S1 and S2 changes with the input voltage and output load, and the frequency remains unchanged; the duty ratio of the switch S5-1 and the switch S6-1 is less than 50% and fixed, for example, 49%, and there is a dead time. The driving signal of the switch S8-1 and the switch S8-2 is the same as the driving signal of the switch S6-1 and the switch S6-2. The driving signals of the switch tubes S7-1 and S7-2 are consistent with the driving signals of the switch tubes S5-1 and S5-2. The duty cycle of the switch tubes S6-3 and S5-3 is greater than 50% and is fixed, for example, 51%. There is a minimum overlap common time. The switch tubes S7-3 and S7-4 complement the switch tubes S6-3 and S6-4 and have a dead time. The switch tubes S8-3 and S8-4 complement the switch tubes S5-3 and S5-4 and have a dead time.

[0089] When the positive voltage input to the hybrid converter is close to the positive voltage output by the buck circuit 100, the hybrid converter operates in the buck-boost mode. When the hybrid converter operates in the buck-boost mode, each cycle includes at least an excitation phase and a demagnetization phase. In both the excitation phase and the demagnetization phase, the switch tube S3 remains off, and the active clamp switch tube S4 is turned on for part of the time period. In both the excitation phase and the demagnetization phase, the switch tube S1 operates at the set maximum duty cycle, and the switch tube S2 operates at the minimum duty cycle. In the excitation phase, the switch tube S5 -1, the switch tubes S5-2, S5-3 and S5-4 are all turned on, and the energy is transferred from the primary side to the secondary side through the transformer. In the demagnetization stage, the switch tube S1 is turned off, and the switch tubes S2, S5-1, S5-2, S5-3 and S5-4 are all turned on, and the energy is transferred from the primary side to the secondary side through the transformer; in the excitation stage of the next cycle, the switch tube S2 is turned off, and the switch tubes S1, S6-1, S6-2, S6-3 and S6-4 are all turned on, and the energy is transferred from the primary side to the secondary side through the transformer. Energy is transferred from the primary side to the secondary side. During the demagnetization phase, switch S1 is turned off, while switch S2, switch S6-1, switch S6-2, switch S6-3, and switch S6-4 are all turned on. When the hybrid converter operates in the buck-boost mode, the duty cycle of switch S1 reaches the maximum duty cycle and remains unchanged. The duty cycles of switches S5-1 and S6-1 are less than 50% and are fixed, for example, 49%, with a dead time. The drive signals of switches S8-1 and S8-2 are consistent with the drive signals of switches S6-1 and S6-2. The drive signals for switches S7-1 and S7-2 are consistent with the drive signals for switches S5-1 and S5-2. The duty cycles of switches S6-3 and S5-3 are greater than 50% and vary with input voltage and load. The overlap time is greater than the minimum overlap time. Switches S7-3 and S7-4 complement switches S6-3 and S6-4 and have a dead time. Switches S8-3 and S8-4 complement switches S5-3 and S5-4 and have a dead time.

[0090] When the positive voltage input to the hybrid converter is lower than the positive voltage output by the buck circuit 100, or when the hybrid converter operates in the buck-boost mode and the duty cycle of some switches of the second switching circuit exceeds a certain threshold, the hybrid converter enters the boost mode.

[0091] When the hybrid converter operates in the boost mode, each cycle includes at least an excitation phase and a demagnetization phase. In the excitation phase and the demagnetization phase, the switch tube S1 remains on, the switch tube S2 remains off, and the active clamp switch tube S4 is turned on for part of the time period; in the excitation phase, the switch tubes S3, S5-1, S5-2, S5-3, S5-4, S6-3, and S6-4 are all turned on. In the demagnetization phase, the switch tubes S6-3, S6-4, S6-1, and S6-2 are all turned on. In the excitation phase of the next cycle, the switch tubes S3, S5-3, S5-4, S6-3, S6-4, S6-1, and S6-2 are all turned on. In the demagnetization phase, the switch tubes S5-3, S5-4, S5-1, and S6-2 are all turned on. S5-2 are both turned on; when the hybrid converter operates in boost mode, the duty cycle of switch S5-1 and switch S6-1 is less than 50% and is fixed, for example, 49%, with a dead time. The drive signals of switch S8-1 and switch S8-2 are consistent with the drive signals of switch S6-1 and switch S6-2; the drive signals of switch S7-1 and switch S7-2 are consistent with the drive signals of switch S5-1 and switch S5-2; the duty cycle of switch S6-3 and switch S5-3 is greater than 50% and changes with changes in input voltage and load, and the overlap common time is greater than the set overlap common time. Switch S7-3 and switch S7-4 have complementary dead time with switch S6-3 and switch S6-4, and switch S8-3 and switch S8-4 have complementary dead time with switch S5-3 and switch S5-4;

[0092] Figure 9 、 Figure 10 、 Figure 11 、 Figure 12 、 Figure 13 They are respectively different circuit structure combinations of the first coupling circuit 300 and the second coupling circuit 400, mainly combining different circuit structures of the first switching circuit and the second switching circuit. The rectifier circuit can be a full-wave rectifier circuit or a full-bridge circuit, which can be selected according to the output voltage.

[0093] In addition, Figure 9 、 Figure 10 、 Figure 11 、 Figure 12 、 Figure 13 Only the first coupling circuit 300 and the second coupling circuit 400 are connected in a vertically distributed manner. The second coupling circuit 400 and the first coupling circuit 300 are exchanged into another combination, which will not be described in detail here.

[0094] Specifically:

[0095] Figure 9、 Figure 10 The first switching circuit in the second coupling circuit 400 shown is a full-bridge topology, and the first switching circuit in the first coupling circuit 300 is a half-bridge topology and a push-pull topology respectively; Figure 11 、 Figure 12 、 Figure 13 The second switching circuit in the second coupling circuit 400 shown is a push-pull topology, and the first switching circuit in the first coupling circuit 300 is a full-bridge topology, a half-bridge topology, and a push-pull topology respectively; the coupling circuit control method is similar to that in the first embodiment above and will not be described in detail here.

[0096] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be construed as limiting the present invention. Persons skilled in the art will appreciate that equivalent substitutions, improvements, and modifications may be made without departing from the spirit and scope of the present invention. These equivalent substitutions, improvements, and modifications should also be considered within the scope of protection of the present invention. Examples will not be used here for further elaboration; the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A hybrid converter, characterized in that: The hybrid converter includes a step-down circuit, a capacitor C1, an active clamping circuit, a first coupling circuit and a second coupling circuit; The first output terminal of the step-down circuit is connected to the first input terminal of the first coupling circuit, the second input terminal of the first coupling circuit is connected to the first input terminal of the second coupling circuit, and the second output terminal of the step-down circuit is connected to the second input terminal of the second coupling circuit; or the first output terminal of the step-down circuit is connected to the first input terminal of the second coupling circuit, the second input terminal of the second coupling circuit is connected to the first input terminal of the first coupling circuit, and the second output terminal of the step-down circuit is connected to the second input terminal of the first coupling circuit; The capacitor C1 is connected between the first input terminal and the second input terminal of the first coupling circuit, and the active clamping circuit is connected between the first input terminal and the second input terminal of the second coupling circuit; The first coupling circuit is a voltage-fed coupling circuit, and the second coupling circuit is a current-fed coupling circuit.

2. The hybrid converter according to claim 1, characterized in that: The step-down circuit includes a switch tube S1, a switch tube S2 and an inductor L; The first end of the switch tube S1 serves as the positive input end of the hybrid converter, the second end of the switch tube S1 is connected to the first end of the switch tube S2 and the first end of the inductor L respectively, and the second end of the switch tube S2 serves as the input ground of the hybrid converter; The second end of the inductor L is connected to the first end of the first coupling circuit, and the second end of the switch tube S2 is connected to the second end of the second coupling circuit; or the second end of the inductor L is connected to the first end of the second coupling circuit, and the second end of the switch tube S2 is connected to the second end of the first coupling circuit.

3. The hybrid converter according to claim 1, wherein: The first coupling circuit includes a first switching circuit, a transformer T1, a first rectifier circuit and an output capacitor Co1 connected in sequence. The first input end of the first switching circuit is connected to the first end of the capacitor C1, the second input end of the first switching circuit is connected to the second end of the capacitor C1, the first end of the output capacitor Co1 and the first output end of the second coupling circuit are connected together as the positive output end of the hybrid converter, and the second end of the output capacitor Co1 and the second output end of the second coupling circuit are connected together as the negative output end of the hybrid converter.

4. The hybrid converter according to claim 3, characterized in that: The first switching circuit includes a DC blocking capacitor Cr connected in series with a switching tube in the first switching circuit.

5. The hybrid converter according to claim 4, characterized in that: The DC blocking capacitor Cr is further connected in series with a resonant inductor Lr, or the parasitic inductance of the transformer T1 is used as the resonant inductor Lr.

6. The hybrid converter according to claim 1, characterized in that: The second coupling circuit includes a second switching circuit, a transformer T2, a second rectifier circuit and an output capacitor Co2 connected in sequence, the first input end of the second switching circuit is connected to the first end of the capacitor C2, the second input end of the second switching circuit is connected to the second end of the switch tube S4, the first output end of the first coupling circuit and the first end of the output capacitor Co2 are connected together as the positive output end of the hybrid converter, and the second output end of the first coupling circuit and the second end of the output capacitor Co2 are connected together as the negative output end of the hybrid converter.

7. The hybrid converter according to claim 1, characterized in that: The active clamping circuit includes a capacitor C2 and a switch tube S4. The first end of the capacitor C2 is respectively connected to the second end of the capacitor C1, the second end of the first coupling circuit, and the first end of the second coupling circuit. The second end of the capacitor C2 is connected to the first end of the switch tube S4. The second end of the switch tube S4 is connected to the second input end of the second coupling circuit.

8. The hybrid converter according to claim 1, characterized in that: The hybrid converter further includes a switch tube S3 , a first input end of the second coupling circuit is connected to the first end of the switch tube S3 , and a second input end of the second coupling circuit is connected to the second end of the switch tube S3 .

9. A hybrid converter, characterized in that: The hybrid converter includes a step-down circuit, a capacitor C1, an active clamping circuit, a first coupling circuit and a second coupling circuit; The first output terminal of the step-down circuit is connected to the first input terminal of the first coupling circuit, the second input terminal of the first coupling circuit is connected to the first input terminal of the second coupling circuit, and the second output terminal of the step-down circuit is connected to the second input terminal of the second coupling circuit; or the first output terminal of the step-down circuit is connected to the first input terminal of the second coupling circuit, the second input terminal of the second coupling circuit is connected to the first input terminal of the first coupling circuit, and the second output terminal of the step-down circuit is connected to the second input terminal of the first coupling circuit; The capacitor C1 is connected between the first input terminal and the second input terminal of the first coupling circuit, and the active clamping circuit is connected between the first input terminal and the second input terminal of the second coupling circuit; wherein the first coupling circuit is a voltage-fed coupling circuit, and the second coupling circuit is a current-fed coupling circuit; The step-down circuit includes a switch S1, a switch S2, and an inductor L; the first end of the switch S1 serves as the positive input end of the hybrid converter, the second end of the switch S1 is connected to the first end of the switch S2 and the first end of the inductor L, respectively, and the second end of the switch S2 serves as the input ground of the hybrid converter; the second end of the inductor L is connected to the first end of the first coupling circuit, and the second end of the switch S2 is connected to the second end of the second coupling circuit; or the second end of the inductor L is connected to the first end of the second coupling circuit, and the second end of the switch S2 is connected to the second end of the first coupling circuit. The first coupling circuit includes a first switching circuit, a transformer T1, a first rectifier circuit, and an output capacitor Co1 connected in sequence, wherein a first input end of the first switching circuit is connected to a first end of the capacitor C1, and a second input end of the first switching circuit is connected to a second end of the capacitor C1; The second coupling circuit includes a second switching circuit, a transformer T2, a second rectifier circuit and an output capacitor Co2 connected in sequence, the first input end of the second switching circuit is connected to the first end of the capacitor C2, the second input end of the second switching circuit is connected to the second end of the switch tube S4, the first end of the output capacitor Co1 and the first end of the output capacitor Co2 are connected together as the positive output end of the hybrid converter, and the second end of the output capacitor Co1 and the second end of the output capacitor Co2 are connected together as the negative output end of the hybrid converter.

10. A control method for the hybrid converter according to claim 9, characterized in that: The control method includes: When the hybrid converter is in the buck mode, the switch S4 is turned on or partially turned on; in the excitation phase, the switch S2 is turned off, and the switch S1, the first switch circuit, and some of the switch tubes in the second switch circuit are turned on, transferring energy from the primary side to the secondary side through the transformer; in the demagnetization phase, the switch S1 is turned off, and the switch S2, the first switch circuit, and some of the switch tubes in the second switch circuit are turned on, transferring inductive energy from the primary side to the secondary side through the transformer; and when the hybrid converter operates in the buck mode, the duty cycle of the switch S1 and the switch S2 changes with the input voltage and output load, while the frequency remains unchanged; the switch tube in the first switch circuit operates at a first fixed duty cycle, and the switch tube in the second switch circuit operates at a second fixed duty cycle; When the hybrid converter is in the buck-boost mode, the switch S1 operates at a set maximum duty cycle, and the switch S2 complements the switch S1 and operates at a minimum duty cycle. During the excitation phase, some of the switches in the first switching circuit are turned on, the second switching circuit is turned on, and the switch S4 remains off. During the demagnetization phase, the switch S4 is turned on or partially turned on, and some of the switches in the second switching circuit are turned on. The switches in the first switching circuit operate at a first fixed duty cycle, and the duty cycle of the switches in the second switching circuit varies with input voltage and output load, while the frequency remains unchanged. When the hybrid converter is in the boost mode, the switch tube S1 remains turned on and the switch tube S2 remains turned off; and in the excitation stage, some of the switch tubes of the first switching circuit are turned on, the second switching circuit is turned on, and the switch tube S4 remains turned off; in the demagnetization stage, the switch tube S4 is turned on or turned on for part of the time period, and some of the switch tubes of the second switching circuit are turned on; the switch tubes in the first switching circuit operate at a first fixed duty cycle, and the duty cycle of the switch tubes in the second switching circuit changes with the input voltage and output load, and the frequency remains unchanged.

11. The hybrid converter control method according to claim 10, characterized in that: When the input end of the second coupling circuit is connected in parallel to the switch tube S3, the drive signal of the switch tube S3 is issued when entering the boost mode, and remains on when the second switch circuit is turned on.

12. The hybrid converter control method according to claim 10, characterized in that: The operating frequency of the switch tube in the first coupling circuit and the operating frequency of the switch tube in the second coupling circuit are half of the operating frequency of the switch tube in the step-down circuit.

13. The hybrid converter control method according to claim 10, characterized in that: The switch tube driving signal in the first rectifier circuit is in phase with the switch tube driving signal in the first switching circuit, and the pulse width of the first rectifier circuit driving signal is less than or equal to the pulse width of the switch tube driving signal in the first switching circuit.

14. The hybrid converter control method according to claim 10, characterized in that: The driving signal of the switch tube in the second rectifier circuit and the driving signal of the switch tube in the second switching circuit are complementary.

15. The hybrid converter control method according to claim 10, characterized in that: The first fixed duty cycle is less than 50%, and the second fixed duty cycle is greater than 50%.

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