Voltage conversion circuit

Abstract

The application provides a voltage conversion circuit, which comprises a primary side circuit and a secondary side circuit. The primary side circuit comprises two primary switch bridge arms connected between an input positive terminal and an input negative terminal, and six resonance branches. Each primary switch bridge arm has four primary switches connected in series. Each resonance branch is electrically coupled to one of the two primary switch bridge arms, and comprises a resonance capacitor and a primary winding connected in series. The secondary side circuit comprises at least one secondary winding, wherein the at least one secondary winding is electromagnetically coupled to each primary winding of the primary side circuit.

Description

Technical Field

[0001] This case relates to a voltage conversion circuit, and more particularly to a voltage conversion circuit capable of achieving a high voltage conversion ratio. Background Technology

[0002] Most commonly used voltage conversion circuits achieve different voltage conversion ratios by adjusting the turns ratio between the primary and secondary sides of the transformer. For applications requiring a higher voltage conversion ratio, current technology typically increases the number of turns in the primary winding. However, this increases the transformer height, leading to larger circuit size and manufacturing costs, which is detrimental to miniaturization. Furthermore, the high voltage in the primary circuit subjectes its components to significant voltage stress, especially switching devices that frequently switch on and off, resulting in substantial switching losses and hindering efficient circuit design.

[0003] Therefore, there is an urgent need to provide a voltage conversion circuit that can improve upon the aforementioned prior art. Summary of the Invention

[0004] The purpose of this invention is to provide a novel voltage conversion circuit that achieves a high voltage conversion ratio while having a relatively small number of turns in both the primary and secondary windings, and simultaneously reduces the voltage stress on the switching components in the primary circuit. This effectively reduces the transformer height and circuit volume, and also effectively reduces the voltage stress on the switching components on the primary side of the voltage conversion circuit, thereby reducing switching losses and improving component lifespan and the operating efficiency of the voltage conversion circuit.

[0005] To achieve the above objectives, this invention provides a voltage conversion circuit comprising a primary-side circuit and a secondary-side circuit. The primary-side circuit includes a first primary switch, a second primary switch, a third primary switch, and a fourth primary switch connected in series between the positive and negative input terminals, and a fifth primary switch, a sixth primary switch, a seventh primary switch, and an eighth primary switch connected in series between the positive and negative input terminals. The first primary switch is electrically coupled to the positive input terminal; the connection point between the first and second primary switches is a first connection point; the connection point between the second and third primary switches is a second connection point; the connection point between the third and fourth primary switches is a third connection point; and the fourth primary switch is electrically coupled to the negative input terminal. The fifth primary switch is electrically coupled to the positive input terminal; the connection point between the fifth and sixth primary switches is a fourth connection point; the connection point between the sixth and seventh primary switches is a fifth connection point; the connection point between the seventh and eighth primary switches is a sixth connection point; and the eighth primary switch is electrically coupled to the negative input terminal. The primary side circuit also includes a first resonant branch, a second resonant branch, a third resonant branch, a fourth resonant branch, a fifth resonant branch, and a sixth resonant branch. The first resonant branch is electrically coupled between the first connection point and the third connection point, and includes a first resonant capacitor and a first primary winding connected in series. The second resonant branch is electrically coupled between the second connection point and the negative input terminal, and includes a second resonant capacitor and a second primary winding. The third resonant branch is electrically coupled between the third connection point and the negative input terminal, and includes a third resonant capacitor and a third primary winding. The fourth resonant branch is electrically coupled between the fourth connection point and the sixth connection point, and includes a fourth resonant capacitor and a fourth primary winding. The fifth resonant branch is electrically coupled between the fifth connection point and the negative input terminal, and includes a fifth resonant capacitor and a fifth primary winding. The sixth resonant branch is electrically coupled between the sixth connection point and the negative input terminal, and includes a sixth resonant capacitor and a sixth primary winding. The secondary circuit includes at least one primary winding, wherein the at least one primary winding is electromagnetically coupled to a first primary winding, a second primary winding, a third primary winding, a fourth primary winding, a fifth primary winding, and a sixth primary winding. Attached Figure Description

[0006] Figure 1 This is a schematic diagram of the circuit structure of a voltage conversion circuit according to an embodiment of this case.

[0007] Figure 2A An embodiment of the secondary side circuit of the voltage conversion circuit of this case is shown.

[0008] Figure 2B Another embodiment of the secondary side circuit of the voltage conversion circuit in this case is shown.

[0009] Figure 3A exemplify Figure 1The operating waveform of the voltage conversion circuit.

[0010] Figure 3B exemplify Figure 1 The voltage conversion circuit operates in the positive half-cycle.

[0011] Figure 3C exemplify Figure 1 The voltage conversion circuit operates in the negative half-cycle.

[0012] Figure 4 exemplify Figure 1 The voltage changes of each switch in the voltage conversion circuit. List of reference numerals 1: Voltage conversion circuit TR: Transformer 11: Primary side circuit T1: Positive input terminal T2: Input negative terminal QP1: First primary switch QP2: Second primary switch QP3: Third primary switch QP4: Fourth Primary Switch QP5: Fifth Primary Switch QP6: Sixth Primary Switch QP7: Seventh Primary Switch QP8: Eighth Primary Switch Cr1: First resonant capacitor Lr1: First resonant inductor P1: First primary winding Cr2: Second resonant capacitor Lr2: Second resonant inductor P2: Second primary winding Cr3: Third resonant capacitor Lr3: Third resonant inductor P3: Third primary winding Cr4: Fourth resonant capacitor Lr4: Fourth resonant inductor P4: Fourth primary winding Cr5: Fifth resonant capacitor Lr5: Fifth resonant inductor P5: Fifth primary winding Cr6: Sixth resonant capacitor Lr6: Sixth resonant inductor P6: Sixth primary winding X1: First connection point X2: Second connection point X3: Third connection point X4: Fourth connection point X5: Fifth connection point X6: Sixth connection point 10, 10a, 10b: Secondary side circuit QS1, QS1a: Primary switches QS2, QS2a: Secondary stage switches S1, S1a, S1b: Primary winding S2, S2a: Secondary winding T3, T3a, T3b: Positive output terminals T4, T4b: Negative output terminals T41a: First output negative terminal T42a: Second output negative terminal 12: Controller Cout, C1, C2: Output capacitors R, R1, R2: Load MP1, MP2: Midpoint of bridge arm T: Period t0, t1, t2, t3, t4: Time points PWM1: First control signal PWM2: Second control signal IP1, IP2, IP3, IP4, IP5, IP6, IS1, IS2: Current Vin: Input voltage Vo: Output voltage VS1, VP1, VP2, VP3, VP4: Voltage Detailed Implementation

[0013] Some typical embodiments embodying the features and advantages of this invention will be described in detail in the following description. It should be understood that this invention can have various variations under different implementation methods, all of which do not depart from the scope of this invention, and the descriptions and illustrations therein are for illustrative purposes only and are not intended to limit this invention.

[0014] The terms "first," "second," etc., used in this case do not specifically refer to order or sequence, nor are they used to limit this case; they are merely used to distinguish elements or operations described using the same technical terms. Secondly, the terms "comprising," "including," "having," and "containing," used in this case, are all open-ended terms, meaning they include but are not limited to. Furthermore, the terms "coupled" or "connected," used in this case, can refer to two or more elements making direct physical or electrical contact, or indirectly making physical or electrical contact with each other.

[0015] The following detailed description of some embodiments of this case is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments.

[0016] Please see Figure 1 , Figure 1 This is a schematic diagram of the circuit structure of a voltage conversion circuit according to an embodiment of the present invention. The voltage conversion circuit 1 includes a primary side circuit 11 and a secondary side circuit 10. The primary side circuit 11 includes a first primary switch bridge arm and a second primary switch bridge arm. The first primary switch bridge arm and the second primary switch bridge arm are connected in parallel between the positive input terminal T1 and the negative input terminal T2 of the voltage conversion circuit 1. The negative input terminal T2 may be, for example, but not limited to, a ground terminal. The first primary switch bridge arm has a first primary switch QP1, a second primary switch QP2, a third primary switch QP3, and a fourth primary switch QP4 connected in series in sequence. The first primary switch QP1 is electrically coupled to the positive input terminal T1 of the voltage conversion circuit 1. The connection node between the first primary switch QP1 and the second primary switch QP2 is the first connection point X1. The connection node between the second primary switch QP2 and the third primary switch QP3 is the second connection point X2. The connection node between the third primary switch QP3 and the fourth primary switch QP4 is the third connection point X3. The fourth primary switch QP4 is electrically coupled to the negative input terminal T2 of the voltage conversion circuit 1. The second primary switch arm has a fifth primary switch QP5, a sixth primary switch QP6, a seventh primary switch QP7, and an eighth primary switch QP8 connected in series. The fifth primary switch QP5 is electrically coupled to the positive input terminal T1 of the voltage conversion circuit 1. The connection point between the fifth primary switch QP5 and the sixth primary switch QP6 is the fourth connection point X4. The connection point between the sixth primary switch QP6 and the seventh primary switch QP7 is the fifth connection point X5. The connection point between the seventh primary switch QP7 and the eighth primary switch QP8 is the sixth connection point X6. The eighth primary switch QP8 is electrically coupled to the negative input terminal T2 of the voltage conversion circuit 1. The first primary switch QP1, the second primary switch QP2, the third primary switch QP3, the fourth primary switch QP4, the fifth primary switch QP5, the sixth primary switch QP6, the seventh primary switch QP7, and the eighth primary switch QP8 of the voltage conversion circuit 1 can be implemented using any suitable switching assembly, and is not limited to... Figure 1 The image shows a metal oxide semiconductor field effect transistor (MOSFET).

[0017] The primary side circuit 11 also includes a first resonant branch, a second resonant branch, a third resonant branch, a fourth resonant branch, a fifth resonant branch, and a sixth resonant branch, wherein each resonant branch includes a resonant capacitor and a primary winding connected in series. Specifically, the first resonant branch is electrically coupled between the first connection point X1 and the third connection point X3, and includes a first resonant capacitor Cr1 and a first primary winding P1 connected in series; the second resonant branch is electrically coupled between the second connection point X2 and the input negative terminal T2, and includes a second resonant capacitor Cr2 and a second primary winding P2 connected in series; the third resonant branch is electrically coupled between the third connection point X3 and the input negative terminal T2, and includes a third resonant capacitor Cr3 and a third primary winding P3 connected in series; the fourth resonant branch is electrically coupled between the fourth connection point X4 and the sixth connection point X6, and includes a fourth resonant capacitor Cr4 and a fourth primary winding P4 connected in series; the fifth resonant branch is electrically coupled between the fifth connection point X5 and the input negative terminal T2, and includes a fifth resonant capacitor Cr5 and a fifth primary winding P5 connected in series; the sixth resonant branch is electrically coupled between the sixth connection point X6 and the input negative terminal T2, and includes a sixth resonant capacitor Cr6 and a sixth primary winding P6 connected in series.

[0018] In some embodiments, each resonant branch of the primary-side circuit 11 further includes a resonant inductor. Specifically, the first resonant branch further includes a first resonant inductor Lr1 connected in series between the first resonant capacitor Cr1 and the first primary winding P1; the second resonant branch further includes a second resonant inductor Lr2 connected in series between the second resonant capacitor Cr2 and the second primary winding P2; the third resonant branch further includes a third resonant inductor Lr3 connected in series between the third resonant capacitor Cr3 and the third primary winding P3; the fourth resonant branch further includes a fourth resonant inductor Lr4 connected in series between the fourth resonant capacitor Cr4 and the fourth primary winding P4; the fifth resonant branch further includes a fifth resonant inductor Lr5 connected in series between the fifth resonant capacitor Cr5 and the fifth primary winding P5; and the sixth resonant branch further includes a sixth resonant inductor Lr6 connected in series between the sixth resonant capacitor Cr6 and the sixth primary winding P6. In each resonant branch, the resonant inductor may be an independent inductor, or it may be the leakage inductance of the transformer TR formed by the electromagnetic coupling between the primary winding and the secondary winding of the secondary-side circuit 10 in the resonant branch.

[0019] The secondary circuit 10 includes at least one primary winding, and this at least one primary winding is electromagnetically coupled to a first primary winding P1, a second primary winding P2, a third primary winding P3, a fourth primary winding P4, a fifth primary winding P5, and a sixth primary winding P6. Figure 1In the illustrated embodiment, the secondary-side circuit 10 includes a first-stage branch and a second-stage branch connected in parallel between the output positive terminal T3 and the output negative terminal T4 of the voltage conversion circuit 1. The aforementioned at least one primary winding includes a first-stage winding S1 and a second-stage winding S2, wherein the output negative terminal T4 may be, for example, but not limited to, a ground terminal. The first-stage branch includes the first-stage winding S1 and the first-stage switch QS1 connected in series, and the second-stage branch includes the second-stage winding S2 and the second-stage switch QS2 connected in series. Each secondary switch can be implemented using any suitable switching assembly, and is not limited to... Figure 1 The metal-oxide-semiconductor field-effect transistor shown is an example. In some embodiments, a secondary switch may not be provided in the secondary-side circuit 10.

[0020] In some embodiments, the voltage conversion circuit 1 further includes a controller 12. The controller 12 is electrically connected to each primary switch and each stage switch of the voltage conversion circuit 1, and is used to control the on and off operation of each primary switch and each stage switch in the voltage conversion circuit 1.

[0021] By providing the voltage conversion circuit described above, a large voltage conversion ratio between the primary and secondary sides can be achieved with a relatively small turns ratio. Specifically, the number of turns in the primary and secondary windings of the transformer can be reduced, thereby reducing circuit size and manufacturing costs. In addition, by connecting multiple primary switches in series, the voltage stress on the primary switches can be effectively distributed, thereby reducing switching losses and improving component lifespan and efficiency.

[0022] In some embodiments, the first end of the first primary winding P1 is electrically coupled to the first connection point X1, the first end of the second primary winding P2 is electrically coupled to the input negative terminal T2, the first end of the third primary winding P3 is electrically coupled to the third connection point X3, the first end of the fourth primary winding P4 is electrically coupled to the sixth connection point X6, the first end of the fifth primary winding P5 is electrically coupled to the fifth connection point X5, the first end of the sixth primary winding P6 is electrically coupled to the input negative terminal T2, the first end of the first primary winding S1 is electrically coupled to the output positive terminal T3, and the first end of the second primary winding S2 is coupled to the output negative terminal T4. The first ends of the first primary winding P1, the second primary winding P2, the third primary winding P3, the fourth primary winding P4, the fifth primary winding P5, the sixth primary winding P6, the first end of the first primary winding S1, and the first end of the second primary winding S2 are terminals of the same name.

[0023] The secondary circuit of voltage conversion circuit 1 in this case can have various implementations, and is not limited to... Figure 1 The secondary-side circuit shown is limited to 10. For example, please refer to [reference needed]. Figure 2A and pair Figure 1, Figure 2A A secondary-side circuit topology according to another embodiment of this case is shown. For example... Figure 2A As shown, the secondary-side circuit 10a includes two secondary branches, and the secondary windings include a primary winding S1a and a secondary winding S2a. The primary branch is located between the positive output terminal T3a and the negative output terminal T41a, and the secondary branch is located between the positive output terminal T3a and the negative output terminal T42a. The negative output terminals T41a and T42a are electrically coupled to ground. The primary branch includes the primary winding S1a and the primary switch QS1a connected in series, and the secondary branch includes the secondary winding S2a and the secondary switch QS2a connected in series. Furthermore, the secondary-side circuit 10a also includes an output capacitor C1 connected in parallel to the primary branch and an output capacitor C2 connected in parallel to the secondary branch, as well as a load R1 for the parallel output capacitor C1 and a load R2 for the parallel output capacitor C2. The first end of the first primary winding S1a is electrically coupled to the positive output terminal T3a, and the first end of the second primary winding S2a is electrically coupled to the negative output terminal T42a. The first ends of the first primary winding P1, the second primary winding P2, the third primary winding P3, the fourth primary winding P4, the fifth primary winding P5, the sixth primary winding P6, the first end of the first primary winding S1a, and the first end of the second primary winding S2a are terminals of the same name.

[0024] Please see Figure 2B and pair Figure 1 , Figure 2B The secondary-side circuit topology of another embodiment of this invention is shown. The secondary-side circuit of this invention can also be a full-bridge rectifier circuit. For example... Figure 2B As shown, the secondary side circuit 10b also includes two secondary switch bridge arms connected in parallel between the output positive terminal T3b and the output negative terminal T4b, and each secondary switch bridge arm has two secondary switches connected in series. The two ends of the secondary winding S1b are electrically coupled to the midpoints MP1 and MP2 of the two secondary switch bridge arms, respectively.

[0025] Figure 3A exemplify Figure 1 The operating waveform of the voltage conversion circuit. Figure 3B exemplify Figure 1 The voltage conversion circuit operates during the positive half-cycle. Figure 3C exemplify Figure 1 The voltage conversion circuit operates during the negative half-cycle. Figure 3AThe diagram shows the first control signal PWM1, the second control signal PWM2, the on / off state of the first primary switch QS1, the on / off state of the second primary switch QS2, the current IP1 through the first primary winding P1, the current IP2 through the second primary winding P2, the current IP3 through the third primary winding P3, the current IP4 through the fourth primary winding P4, the current IP5 through the fifth primary winding P5, and the current IP6 through the sixth primary winding P6, where I0 is the maximum value of the current IP1 through the first primary winding P1 at this time. The first control signal PWM1 controls the first primary switch QP1, the third primary switch QP3, the sixth primary switch QP6, and the eighth primary switch QP8, causing them to be synchronously turned on or off. The second control signal PWM2 controls the second primary switch QP2, the fourth primary switch QP4, the fifth primary switch QP5, and the seventh primary switch QP7, causing them to be synchronously turned on or off. The first primary switch QP1 and the second primary switch QP2 are turned on alternately; similarly, the first primary switch QS1 and the second primary switch QS2 are turned on alternately. Time points t0 to t4 can be considered as a complete cycle T, where time points t0 to t1 are defined as the dead time, time points t1 to t2 are defined as the positive half-cycle, time points t2 to t3 are defined as the dead time, and time points t3 to t4 are defined as the negative half-cycle. The operation of voltage conversion circuit 1 is explained below according to each time point.

[0026] like Figure 3A As shown, during the period from time point t0 to time point t1, all primary and secondary switches are in the off state.

[0027] During the period from time point t1 to time point t2, voltage conversion circuit 1 operates in the positive half-cycle, and the corresponding operating state of voltage conversion circuit 1 is as follows: Figure 3BAs shown. During the positive half-cycle, the first primary switch QP1, the third primary switch QP3, the sixth primary switch QP6, and the eighth primary switch QP8 are in the on state, while the second primary switch QP2, the fourth primary switch QP4, the fifth primary switch QP5, and the seventh primary switch QP7 remain in the off state. At this time, the current flowing through each primary winding flows from the first end to the second end of that primary winding. Specifically, the current IP1 flowing through the first primary winding P1 enters from the first terminal of the first primary winding P1, charging the first resonant capacitor Cr1; the current IP2 flowing through the second primary winding P2 enters from the first terminal of the second primary winding P2, discharging the second resonant capacitor Cr2; the current IP3 flowing through the third primary winding P3 enters from the first terminal of the third primary winding P3, charging the third resonant capacitor Cr3; the current IP4 flowing through the fourth primary winding P4 enters from the first terminal of the fourth primary winding P4, discharging the fourth resonant capacitor Cr4; the current IP5 flowing through the fifth primary winding P5 enters from the first terminal of the fifth primary winding P5, charging the fifth resonant capacitor Cr5; and the current IP6 flowing through the sixth primary winding P6 enters from the first terminal of the sixth primary winding P6, discharging the sixth resonant capacitor Cr6. Furthermore, in the secondary circuit 10, the first primary switch QS1 is in the on state, while the second primary switch QS2 remains in the off state. At this time, in the secondary circuit 10, the current IS1 through the primary winding S1 flows out from the first end of the primary winding S1.

[0028] At time t2, all currents IP1, IP2, IP3, IP4, IP5 and IP6 flowing through the primary winding decrease to zero (with some error allowed), and the current IS1 flowing through the first primary winding S1 also decreases to zero. At this time, the first primary switch QP1, the third primary switch QP3, the sixth primary switch QP6, the eighth primary switch QP8 and the first primary switch QS1 are turned off.

[0029] Between time point t2 and time point t3, all primary and secondary switches are in the off state.

[0030] During the period from time point t3 to time point t4, voltage conversion circuit 1 operates in the negative half-cycle, and the corresponding operating state of voltage conversion circuit 1 is as follows: Figure 3CAs shown. During the negative half-cycle, the second primary switch QP2, the fourth primary switch QP4, the fifth primary switch QP5, and the seventh primary switch QP7 are in the on state, while the first primary switch QP1, the third primary switch QP3, the sixth primary switch QP6, and the eighth primary switch QP8 remain in the off state. At this time, the current flowing through each primary winding flows from the second end of the primary winding to the first end. Specifically, the current IP1 flowing through the first primary winding P1 exits from the first terminal of the first primary winding P1, at which time the first resonant capacitor Cr1 discharges; the current IP2 flowing through the second primary winding P2 exits from the first terminal of the second primary winding P2, at which time the second resonant capacitor Cr2 charges; the current IP3 flowing through the third primary winding P3 exits from the first terminal of the third primary winding P3, at which time the third resonant capacitor Cr3 discharges; the current IP4 flowing through the fourth primary winding P4 exits from the first terminal of the fourth primary winding P4, at which time the fourth resonant capacitor Cr4 charges; the current IP5 flowing through the fifth primary winding P5 exits from the first terminal of the fifth primary winding P5, at which time the fifth resonant capacitor Cr5 discharges; and the current IP6 flowing through the sixth primary winding P6 exits from the first terminal of the sixth primary winding P6, at which time the sixth resonant capacitor Cr6 charges. Furthermore, in the secondary circuit 10, the first primary switch QS1 remains off, while the second primary switch QS2 is on. At this time, in the secondary side circuit 10, the current IS2 through the secondary winding S2 flows in from the first end of the secondary winding S2.

[0031] When voltage conversion circuit 1 is running, since the magnetomotive force on the primary and secondary sides of transformer TR is conserved, the relationship (1) can be obtained: (1) Where NPi represents the number of turns in the i-th primary winding, IPi represents the current flowing through the i-th primary winding, and i is an integer between 1 and 6. NSj represents the number of turns in the j-th secondary winding, ISj represents the current flowing through the j-th secondary winding, and J is the number of secondary windings with current flowing through them at that time. Specifically, using... Figure 3B Taking the voltage conversion circuit 1 shown as an example in the switching operation state of the positive half-cycle, the current only flows through the primary winding S1. Therefore, the number of secondary windings through which current flows is 1, that is, J equals 1. And NS1 is the number of turns of the primary winding S1, and IS1 is the current flowing through the primary winding S1.

[0032] In some embodiments, the first resonant capacitor Cr1, the second resonant capacitor Cr2, the third resonant capacitor Cr3, the fourth resonant capacitor Cr4, the fifth resonant capacitor Cr5, and the sixth resonant capacitor Cr6 have the same capacitance value. In some embodiments, the first resonant inductor Lr1, the second resonant inductor Lr2, the third resonant inductor Lr3, the fourth resonant inductor Lr4, the fifth resonant inductor Lr5, and the sixth resonant inductor Lr6 have the same inductance value. When all resonant capacitors have the same capacitance value and all resonant inductors have the same inductance value, since the first primary switch arm and the second primary switch arm are completely symmetrical, the absolute values ​​of currents IP1, IP2, IP4, and IP5 are equal, and the absolute values ​​of currents IP3 and IP6 are equal and twice the absolute value of current IP1 (ignoring error). Accordingly, and with... Figure 3B Taking the voltage conversion circuit 1 shown as an example under the positive half-cycle operation, the magnetomotive force conservation equation (1) of the transformer TR can be rewritten as equation (2): (2)

[0033] If the conduction losses of the circuit and switches are ignored, since the input power and output power are conserved, the relationship (3) can be obtained: (3) Wherein, Vin is the input voltage between the positive input terminal T1 and the negative input terminal T2 of voltage conversion circuit 1, Vo is the output voltage between the positive output terminal T3 and the negative output terminal T4 of voltage conversion circuit 1, Iin is the input current, that is, the current IP1 flowing through the first primary winding P1 during the positive half-cycle, and Io is the output current, that is, the current IS1 flowing through the first primary winding S1 during the positive half-cycle.

[0034] Similarly, when voltage conversion circuit 1 operates in the negative half-cycle, the relationship between the input voltage and the output voltage can also be obtained through the same derivation: (4)

[0035] In some embodiments, the first primary winding P1, the second primary winding P2, the third primary winding P3, the fourth primary winding P4, the fifth primary winding P5, and the sixth primary winding P6 in the voltage conversion circuit 1 have the same number of turns, and the first primary winding S1 and the second primary winding S2 have the same number of turns. Therefore, the relationship between the input voltage and the output voltage (3) can be simplified to equation (5): (5)

[0036] Accordingly, the voltage conversion circuit topology provided in this application can achieve a relatively large voltage conversion ratio using a relatively low turns ratio. For example, in some embodiments, the turns ratio of voltage conversion circuit 1 is 2:1, then the voltage conversion ratio of voltage conversion circuit 1 is 16:1.

[0037] The voltage conversion circuit topology provided in this application further reduces the voltage stress on the primary-side switches. Please refer to [link / reference]. Figure 4 , Figure 4 It shows Figure 1 A simulation diagram of the voltage changes of each switch during operation of an embodiment of the voltage conversion circuit. In this embodiment, Figure 1 In the voltage conversion circuit 1 shown, all resonant capacitors in each resonant branch have the same capacitance value, all resonant inductors have the same inductance value, all primary windings have the same number of turns, and all secondary windings have the same number of turns. The transformer's turns ratio is 2:1, meaning the ratio of input voltage Vin to output voltage Vo is 16:1. When the output voltage is Vo, the input voltage is 16Vo, and the voltage stress of each switch in the first primary switching arm of the voltage conversion circuit 1, as well as the voltage stress of the first primary switch, is as follows: Figure 4 As shown in the diagram. Here, VS1 represents the voltage across the first primary switch QS1, VP1 represents the voltage across the first primary switch QP1, VP2 represents the voltage across the second primary switch QP2, VP3 represents the voltage across the third primary switch QP3, and VP4 represents the voltage across the fourth primary switch QP4. Figure 4 As shown, when voltage conversion circuit 1 operates in the positive half-cycle, the first primary switch QP1 and the third primary switch QP3 are in the on state, the second primary switch QP2 and the fourth primary switch QP4 are in the off state, and the first primary switch QS1 is in the on state. At this time, the voltage VP2 across the second primary switch QP2 is 12Vo, and the voltage VP4 across the fourth primary switch QP4 is 4Vo. When voltage conversion circuit 1 operates in the negative half-cycle, the first primary switch QP1 and the third primary switch QP3 are in the off state, the second primary switch QP2 and the fourth primary switch QP4 are in the on state, and the first primary switch QS1 is in the off state. At this time, the voltages VP1 and VP3 across the first primary switch QP1 and the third primary switch QP3 are both 8Vo, and the voltage VS1 across the first primary switch QS1 is 2Vo.

[0038] The operation of each switch in the second primary switch bridge arm and the operation of the second-stage switch correspond to the operation of each switch in the first primary switch bridge arm and the operation of the first-stage switch, respectively. Specifically, the voltage conversion circuit 1 has a symmetrical circuit topology, wherein the fifth primary switch QP5 is symmetrically arranged with the first primary switch QP1, and the fifth primary switch QP5 and the first primary switch QP1 are alternately turned on; the sixth primary switch QP6 is symmetrically arranged with the second primary switch QP2, and the sixth primary switch QP6 and the second primary switch QP2 are alternately turned on; the seventh primary switch QP7 is symmetrically arranged with the third primary switch QP3, and the seventh primary switch QP7 and the third primary switch QP3 are alternately turned on; the eighth primary switch QP8 is symmetrically arranged with the fourth primary switch QP4, and the eighth primary switch QP8 and the fourth primary switch QP4 are alternately turned on; the second-stage switch QS2 is symmetrically arranged with the first-stage switch QS1, and the second-stage switch QS2 and the first-stage switch QS1 are alternately turned on. Therefore, the fifth primary switch QP5 has the same voltage stress as the first primary switch QP1, the sixth primary switch QP6 has the same voltage stress as the second primary switch QP2, the seventh primary switch QP7 has the same voltage stress as the third primary switch QP3, the eighth primary switch QP8 has the same voltage stress as the fourth primary switch QP4, and the second primary switch QS2 has the same voltage stress as the first primary switch QS1.

[0039] Accordingly, the voltage stress on each primary switch is reduced compared to the input voltage. This not only extends the lifespan of each switch, but also allows users to replace the primary switch with one of lower rated voltage, thus reducing circuit manufacturing costs.

[0040] In summary, this disclosure has at least the following technical advantages: On the one hand, through the new voltage conversion circuit topology, a larger voltage conversion ratio can be achieved with a smaller transformer turns ratio, meeting the application requirements of high voltage conversion ratio, while reducing the transformer size and lowering the cost of magnetic components, which is beneficial for the miniaturization design of the circuit; on the other hand, the new topology improves voltage stress, making the voltage stress borne by multiple primary-side switching devices significantly lower than the input voltage, thereby enabling the use of low-voltage, low-loss switching devices, further reducing switching losses, improving the overall conversion efficiency of the voltage conversion circuit, and helping to extend the service life of the devices.

[0041] It should be noted that the above are merely preferred embodiments for illustrating this case, and this case is not limited to the described embodiments. The scope of this case is determined by the appended claims. Furthermore, this case can be modified in various ways by those skilled in the art, but all modifications shall not depart from the protection sought by the appended claims.

Claims

1. A voltage conversion circuit, comprising: A primary-side circuit, comprising: A first primary switch, a second primary switch, a third primary switch, and a fourth primary switch are sequentially connected in series between a positive input terminal and a negative input terminal. The first primary switch is electrically coupled to the positive input terminal. The connection node between the first primary switch and the second primary switch is a first connection point. The connection node between the second primary switch and the third primary switch is a second connection point. The connection node between the third primary switch and the fourth primary switch is a third connection point. The fourth primary switch is electrically coupled to the negative input terminal. A fifth primary switch, a sixth primary switch, a seventh primary switch, and an eighth primary switch are sequentially connected in series between the positive input terminal and the negative input terminal. The fifth primary switch is electrically coupled to the positive input terminal. The connection node between the fifth primary switch and the sixth primary switch is a fourth connection point. The connection node between the sixth primary switch and the seventh primary switch is a fifth connection point. The connection node between the seventh primary switch and the eighth primary switch is a sixth connection point. The eighth primary switch is electrically coupled to the negative input terminal. A first resonant branch is electrically coupled between the first connection point and the third connection point, and includes a first resonant capacitor and a first primary winding connected in series. A second resonant branch is electrically coupled between the second connection point and the negative input terminal, and includes a second resonant capacitor and a second primary winding; A third resonant branch is electrically coupled between the third connection point and the negative input terminal, and includes a third resonant capacitor and a third primary winding. A fourth resonant branch is electrically coupled between the fourth connection point and the sixth connection point, and includes a fourth resonant capacitor and a fourth primary winding. A fifth resonant branch, electrically coupled between the fifth connection point and the negative input terminal, and comprising a fifth resonant capacitor and a fifth primary winding; and A sixth resonant branch, electrically coupled between the sixth connection point and the negative input terminal, and comprising a sixth resonant capacitor and a sixth primary winding; and A primary-side circuit includes at least one primary winding, wherein the at least one primary winding is electromagnetically coupled to the first primary winding, the second primary winding, the third primary winding, the fourth primary winding, the fifth primary winding, and the sixth primary winding.

2. The voltage conversion circuit as claimed in claim 1, wherein the first primary switch, the third primary switch, the sixth primary switch and the eighth primary switch are synchronously turned on or off, the second primary switch, the fourth primary switch, the fifth primary switch and the seventh primary switch are synchronously turned on or off, and the first primary switch and the second primary switch are alternately turned on.

3. The voltage conversion circuit as described in claim 1, wherein the first resonant branch, the second resonant branch, the third resonant branch, the fourth resonant branch, the fifth resonant branch, and the sixth resonant branch each further include a first resonant inductor, a second resonant inductor, a third resonant inductor, a fourth resonant inductor, a fifth resonant inductor, and a sixth resonant inductor, wherein the first resonant inductor, the second resonant inductor, the third resonant inductor, the fourth resonant inductor, the fifth resonant inductor, and the sixth resonant inductor are leakage inductances of a transformer formed by the electromagnetic coupling of the first primary winding, the second primary winding, the third primary winding, the fourth primary winding, the fifth primary winding, the sixth primary winding, and the at least one primary winding, or are independent inductors.

4. The voltage conversion circuit as claimed in claim 1, wherein the first primary winding, the second primary winding, the third primary winding, the fourth primary winding, the fifth primary winding, and the sixth primary winding have the same number of turns.

5. The voltage conversion circuit as described in claim 1, wherein the capacitance values ​​of the first resonant capacitor, the second resonant capacitor, the third resonant capacitor, the fourth resonant capacitor, the fifth resonant capacitor, and the sixth resonant capacitor are equal.

6. The voltage conversion circuit as claimed in claim 1, wherein the secondary side circuit is a full-bridge rectifier circuit, the full-bridge rectifier circuit includes two secondary switch bridge arms connected in parallel between an output positive terminal and an output negative terminal, each of the secondary switch bridge arms includes two secondary switches connected in series and a bridge arm midpoint, and the two ends of the at least one primary winding are respectively electrically coupled to the bridge arm midpoint of the two secondary switch bridge arms.

7. The voltage conversion circuit of claim 1, wherein the secondary side circuit includes a positive output terminal, a negative output terminal, a primary branch and a secondary branch, the at least one primary winding includes a primary winding and a secondary winding, the primary branch and the secondary branch are connected in parallel between the positive output terminal and the negative output terminal, and the primary branch includes the primary winding and a primary switch connected in series, and the secondary branch includes the secondary winding and a secondary switch connected in series.

8. The voltage conversion circuit of claim 7, wherein the voltage between the positive input terminal and the negative input terminal is an input voltage of the voltage conversion circuit, and the voltage between the positive output terminal and the negative output terminal is an output voltage of the voltage conversion circuit, wherein during a positive half-cycle when the first-stage switch is in the on state and the second-stage switch is in the off state, the input voltage and the output voltage satisfy the following relationship: During the negative half-cycle when the primary switch is off and the secondary switch is on, the input voltage and the output voltage satisfy the following relationship: in, Vin For this input voltage, Vo This is the output voltage. N P1 This refers to the number of turns of the first primary winding. N P2 This refers to the number of turns of the second primary winding. N P3 This refers to the number of turns of the third primary winding. N P4 This refers to the number of turns of the fourth primary winding. N P5 This refers to the number of turns of the fifth primary winding. N P6 This refers to the number of turns of the sixth primary winding. N S1 This refers to the number of turns of the primary winding. N S2 This refers to the number of turns in the second stage winding.

9. The voltage conversion circuit as claimed in claim 7 or 8, wherein the primary winding and the secondary winding have the same number of turns.

10. The voltage conversion circuit as described in claim 7 or 8, wherein a first end of the first primary winding is electrically coupled to the first connection point, a first end of the second primary winding is electrically coupled to the negative input terminal, a first end of the third primary winding is electrically coupled to the third connection point, a first end of the fourth primary winding is electrically coupled to the sixth connection point, a first end of the fifth primary winding is electrically coupled to the fifth connection point, a first end of the sixth primary winding is electrically coupled to the negative input terminal, a first end of the first primary winding is electrically coupled to the positive output terminal, and a first end of the second primary winding is electrically coupled to the negative output terminal, wherein... The first end of the first primary winding, the first end of the second primary winding, the first end of the third primary winding, the first end of the fourth primary winding, the first end of the fifth primary winding, the first end of the sixth primary winding, the first end of the first primary winding, and the first end of the second primary winding are terminals with the same name.

Images