Power conversion circuit and power conversion method

Abstract

A power conversion circuit includes: a transformer including a primary winding and a secondary winding; a bridge switching circuit including a first switch and a second switch coupled to a first end of the primary winding; the third switch and the fourth switch are coupled with the second end of the primary winding; and a switching circuit coupled between the primary winding and the secondary winding; the first end of the switching circuit is coupled between the first winding and the second winding in the primary winding; and an output conversion circuit coupled to the secondary winding and the switching circuit. The output conversion circuit comprises an output inductor and an output capacitor. The first end of the output inductor and the first end of the output capacitor are coupled to the first output end. The second end of the output inductor is coupled between the third winding and the fourth winding in the secondary winding. The application range of the input voltage is expanded through the topological structure of the power conversion circuit.

Description

Technical Field

[0001] The present disclosure relates to a power conversion circuit, and more particularly to a power conversion circuit for a non-isolated full-bridge topology structure. Background Art

[0002] With the booming development of technology and civilized society, various types of electronic products have emerged. Therefore, the conversion efficiency of the power converter is crucial for the performance of electronic products. Currently, high-conversion-efficiency power converters on the market, such as DC-to-DC converters, adopt a non-isolated full-bridge topology structure. However, the applicable input voltage range of this type of power converter is narrow, resulting in too low conversion efficiency for other input voltages outside the applicable range.

[0003] Therefore, it is necessary to improve the existing power converter to solve the above technical problems. Summary of the Invention

[0004] An object of the present disclosure is to provide a power conversion circuit, comprising: a transformer including a primary winding and a secondary winding; a bridge switch circuit including a first switch and a second switch coupled to the first end of the primary winding at a first node; a third switch and a fourth switch coupled to the second end of the primary winding at a second node, wherein the first switch and the second switch are coupled to an input voltage; and a switching circuit coupled between the primary winding and the secondary winding, wherein a first end of the switching circuit is coupled between a first winding and a second winding in the primary winding; and an output conversion circuit coupled to the secondary winding and the switching circuit. The output conversion circuit includes an output inductor and an output capacitor. A first end of the output inductor and a first end of the output capacitor are coupled to a first output terminal. A second end of the output inductor is coupled between a third winding and a fourth winding in the secondary winding.

[0005] In some embodiments, a turn ratio of the primary winding, the third winding, and a fourth winding is 2:1:1.

[0006] In some embodiments, the number of turns of the first winding, the second winding, the third winding, and a fourth winding is the same.

[0007] In some embodiments, a second end of the switching circuit is coupled between the third switch and the output conversion circuit, and a second end of the switching circuit is coupled between the fourth switch and the output conversion circuit.

[0008] In some embodiments, the output conversion circuit includes a fifth switch coupled between the third winding and ground; and a sixth switch coupled between the fourth winding and ground. The power conversion circuit further includes a seventh switch coupled between the third switch and the fifth switch; and an eighth switch coupled between the fourth switch and the sixth switch.

[0009] In some embodiments, when the input voltage is greater than or equal to a preset value, the switching circuit remains off, and in the first mode, the second switch, the third switch, the sixth switch, and the seventh switch are off, and the first switch, the fourth switch, the fifth switch, and the eighth switch are turned on to electrically connect in series the primary winding, the four-winding, and the three-winding in sequence, so that the output inductor is charged to generate an output voltage. In the second mode following the first mode, the first switch to the fourth switch, the seventh switch to the eighth switch, and the switching circuit are off, and the fifth switch and the sixth switch are turned on. In the third mode following the second mode, the first switch, the fourth switch, the fifth switch, and the eighth switch are off, and the second switch, the third switch, the sixth switch, and the seventh switch are turned on to electrically connect in series the primary winding, the third winding, and the fourth winding in sequence, so that the output inductor is charged to generate an output voltage.

[0010] In some embodiments, the duty cycles of the multiple control signals received by the first switch to the eighth switch are less than 0.5.

[0011] In some embodiments, the preset value is four times the output voltage.

[0012] In some embodiments, the switching circuit includes a ninth switch coupled between the first end of the switching circuit and the third winding; and a tenth switch coupled between the first end of the switching circuit and the fourth winding. When the input voltage is less than the preset value, in the first mode, the second switch to the fourth switch and the sixth switch to the ninth switch are off, and the first switch, the fifth switch, and the tenth switch are turned on to electrically connect in series the first winding, the fourth winding, and the three-winding in sequence, so that the output inductor is charged to generate an output voltage. In the second mode following the first mode, the first switch to the fourth switch and the seventh switch to the tenth switch are off, and the fifth switch and the sixth switch are turned on. In the third mode following the second mode, the first switch, the third switch to the fifth switch, the seventh switch, the eighth switch, and the tenth switch are off, and the second switch, the sixth switch, and the ninth switch are turned on to electrically connect in series the second winding, the third winding, and the fourth winding in sequence.

[0013] In some embodiments, the third switch, the fourth switch, the seventh switch, and the eighth switch are N-type transistors. The sources of the third switch and the seventh switch are coupled to each other, and the sources of the fourth switch and the eighth switch are coupled to each other.

[0014] In some embodiments, the output conversion circuit includes a fifth switch coupled between the third winding and the ground; and a sixth switch coupled between the fourth winding and the ground. The power conversion circuit further includes a seventh switch coupled between the first switch and the third switch, and the drains of the third switch and the seventh switch are coupled to each other; and an eighth switch coupled between the second switch and the fourth switch, and the drains of the fourth switch and the eighth switch are coupled to each other.

[0015] Another object of the present disclosure is to provide a power conversion method. The power conversion circuit includes a first transistor group and a second transistor group connected in parallel between an input voltage and ground. The power conversion circuit further includes a primary winding, a secondary winding, and a switching circuit coupled between the first transistor group and the second transistor group. The switching circuit has a first end coupled between a first winding and a second winding in the primary winding, a second end coupled to the first transistor group and the secondary winding, and a third end coupled to the second transistor group and the secondary winding. A node between a third winding and a fourth winding in the secondary winding is coupled to a first end of an output inductor. The power conversion method includes: when the input voltage is greater than or equal to a preset value, turning off the switching circuit, and selectively turning on transistors in the first transistor group and the second transistor group to output an output voltage; and when the input voltage is less than the preset value, turning off transistors in the first transistor group and transistors in the second transistor group that are coupled between the primary winding and the secondary winding, and selectively turning on a first transistor or a second transistor in the switching circuit, transistors in the first transistor group and the second transistor group that are coupled between the input voltage and the primary winding, and transistors in the first transistor group and the second transistor group that are coupled between the secondary winding and ground to output an output voltage.

[0016] In some embodiments, the power conversion method further includes: adjusting a duty cycle of a plurality of control signals for controlling the first transistor group, the second transistor group, and the switching circuit to be less than 0.5.

[0017] In some embodiments, when the input voltage is greater than or equal to the preset value, the primary winding and the secondary winding are connected in series and turned on. When the input voltage is less than the preset value, the first winding or the second winding is connected in series with the secondary winding and turned on.

[0018] In some embodiments, the power conversion method further includes: adjusting a plurality of control signals for controlling the first transistor group, the second transistor group, and the switching circuit according to the input voltage and the output voltage.

[0019] Therefore, the power conversion circuit and the power conversion method of the present disclosure control the states of switches in the power conversion circuit to adjust the turns ratio of the primary winding, the first secondary winding, and the second secondary winding, thereby expanding the application range of the input voltage.

[0020] The detailed technology and implementation manners of the present disclosure are described below in conjunction with the drawings, so that those of ordinary skill in the technical field to which the present disclosure belongs can understand the technical features of the claimed invention. Description of the Drawings

[0021] For the above and other objects, features, and embodiments of the present disclosure to be more clearly understood, the descriptions of the accompanying drawings are as follows:

[0022] Figure 1 A block diagram showing a power conversion circuit in an embodiment of the present disclosure;

[0023] Figure 2A Showing when the input voltage is greater than or equal to a preset value Figure 1 The operating schematic diagram of the power conversion circuit in the first mode;

[0024] Figure 2B Showing when the input voltage is greater than or equal to a preset value Figure 1 The operating schematic diagram of the power conversion circuit in the second mode;

[0025] Figure 2C Showing when the input voltage is greater than or equal to a preset value Figure 1 The operating schematic diagram of the power conversion circuit in the third mode;

[0026] Figure 3 Showing Figure 2A 、 Figure 2B And Figure 2C The timing diagram of the power conversion circuit among the first mode, the second mode, and the third mode;

[0027] Figure 4A Showing when the input voltage is less than the preset value Figure 1 The operating schematic diagram of the power conversion circuit in the first mode;

[0028] Figure 4B Showing when the input voltage is less than the preset value Figure 1 The operating schematic diagram of the power conversion circuit in the second mode;

[0029] Figure 4C Showing when the input voltage is less than the preset value Figure 1 The operating schematic diagram of the power conversion circuit in the third mode;

[0030] Figure 5 Showing Figure 4A 、 Figure 4B And Figure 4C The timing diagram of the power conversion circuit among the first mode, the second mode, and the third mode;

[0031] Figure 6 A block diagram showing a power conversion circuit in another embodiment of the present disclosure; and

[0032] Figure 7 Showing for Figure 1 The power conversion circuit and Figure 6 The power conversion method of the power conversion circuit.

[0033] Among them, the description of the reference numerals in the drawings is as follows:

[0034] 100: Power conversion circuit

[0035] 110: Bridge switch circuit

[0036] 111: Switching circuit

[0037] 112: Primary winding

[0038] 113: Secondary winding

[0039] 120: Output conversion circuit

[0040] 130: Control circuit

[0041] 200: Power conversion method

[0042] CS1 to CS10: Control signals

[0043] Co: Output capacitor

[0044] Lo: Output inductor

[0045] S1 to S10: Switches

[0046] Vin: Input voltage

[0047] Vout: Output voltage

[0048] TX: Transformer

[0049] Np1: Winding

[0050] Np2: Winding

[0051] Ns1: Winding

[0052] Ns2: Winding

[0053] n1 to n6: Nodes

[0054] Ts: Duty cycle

[0055] T1 to T4: Time intervals

[0056] S210, S220, S230: Steps Detailed implementation manners

[0057] The following disclosure provides many different embodiments or examples for implementing different features of this disclosure document. Components and configurations in specific examples are used to simplify this disclosure in the following discussion. Any example discussed is only for illustrative purposes and will not limit the scope and meaning of this disclosure document or its examples in any way. Where appropriate, the same reference numerals are used between the drawings and the corresponding textual descriptions to represent the same or similar components.

[0058] Since the power converters with high conversion efficiency on the market have a narrow applicable input voltage range, the conversion efficiency for other input voltages outside the applicable range is low. Therefore, this disclosure document proposes a power conversion circuit with a new power topology structure that can dynamically adjust the turns ratio of the primary winding, the first secondary winding, and the second secondary winding, thereby expanding the application range of the input voltage.

[0059] Please refer to Figure 1 , which shows a schematic block diagram of a power conversion circuit 100 in an embodiment of this disclosure document. As Figure 1 shown, the power conversion circuit 100 includes a transformer TX, a bridge switch circuit 110, a switching circuit 111, an output conversion circuit 120, and a control circuit 130. In one embodiment, the power conversion circuit 100 can be a non-isolated full-bridge converter, but this disclosure document is not limited thereto.

[0060] As Figure 1 shown, the transformer TX includes a primary winding 112 and a secondary winding 113. The winding Ns1 and the winding Ns2. The primary winding 112 includes the winding Np1 and the winding Np2. The secondary winding 113 includes the winding Ns1 and the winding Ns2. In one embodiment, the number of turns of the winding Np1, the winding Np2, the winding Ns1, and the winding Ns2 is the same, that is, the turns ratio of the winding Np1, the winding Np2, the winding Ns1, and the winding Ns2 can be 1:1:1:1, but this disclosure document is not limited thereto.

[0061] As Figure 1 shown, the bridge switch circuit 110 includes switches S1 to S4. The output conversion circuit 120 includes switches S5 to S6. The power conversion circuit 100 further includes switches S7 and S8 coupled between the primary winding 112 and the secondary winding 113. The switching circuit 111 includes switches S9 and S10. In one embodiment, the switches S1 to S10 are N-type metal-oxide-semiconductor field-effect transistors (Metal-Oxide-Semiconductor-Field-Effect Transistor), but this disclosure document is not limited thereto. In one embodiment, the switches S1 to S10 can be P-type metal-oxide-semiconductor field-effect transistors, but this disclosure document is not limited thereto.

[0062] As Figure 1 shown, the output conversion circuit 120 further includes an output inductor Lo and an output capacitor Co. In one embodiment, the output inductor Lo can be an iron core coil, but this disclosure document is not limited thereto.

[0063] As Figure 1As shown, the first ends of switch S1 and switch S2 are coupled to the positive terminal of the input voltage Vin. The second end of switch S1 is coupled to the first end of switch S3 and the same-named end of winding Np1 at node n1. The second end of switch S3 (e.g., the source) is coupled to the first end of switch S7 (e.g., the source). The second end of switch S2 is coupled to the first end of switch S4 and the different-named end of winding Np2 at node n2. The second end of switch S4 (e.g., the source) is coupled to the first end of switch S8 (e.g., the source). In other words, switch S1 and S2 are coupled at node n1 and the first end of the primary winding 112, and switch S3 and S4 are coupled at node n2 and the second end of the primary winding 112.

[0064] Switch S5 and switch S6 are respectively coupled between the negative terminal of the input voltage Vin and the second ends of switch S7 and switch S8. Specifically, the first ends of switch S5 and switch S6 are coupled to the negative terminal of the input voltage Vin and the negative terminal of the output voltage Vout (i.e., grounded). The second end of switch S5 is coupled to the second end of switch S7, the first end of switch S9, and the different-named end of winding Ns1 at node n5. The second end of switch S6 is coupled to the second end of switch S8, the first end of switch S10, and the same-named end of winding Ns2 at node n6.

[0065] In one embodiment, the input voltage Vin can be between 40 - 60 volts (Volt), and the output voltage Vout can be 12 volts, but the present disclosure is not limited thereto. In one embodiment, the input voltage Vin can be between 36 - 80 volts (Volt), but the present disclosure is not limited thereto.

[0066] Switch S9 and switch S10 each have a second end coupled to the third end of the primary winding 112 at node n3.

[0067] The first end of the output inductor Lo is coupled to the same-named end of winding Ns1 and the different-named end of winding Ns2 at node n4. The second end of the output inductor Lo is coupled to the first end of the output capacitor Co and generates the output voltage Vout. The second end of the output capacitor Co is grounded.

[0068] In some embodiments, the power conversion circuit 100 includes a control circuit 130, and is configured to detect and determine whether the input voltage Vin is greater than or equal to a preset value, and control the states of switches S1 to S10 based on the determination result, where the preset value may be a general input voltage of the power conversion circuit 100, such as 48 volts, or other values suitable for the circuit design of the power conversion circuit 100. In one embodiment, the control circuit 130 may be a microcontroller unit (MCU), a central processing unit (CPU), an application specific integrated circuit (ASIC), or any control circuit having signal processing functions, but the present disclosure is not limited thereto.

[0069] In one embodiment, the preset value is related to the output voltage Vout. For example, the preset value is four times the output voltage Vout. In some other embodiments, the preset value is greater than four times the output voltage Vout, but the present disclosure is not limited thereto. Regarding the operation control manner of the control circuit 130 for switches S1 to S10 of the power conversion circuit 100 in different magnitude cases of the input voltage Vin and the output voltage Vout, please refer to the discussions in Figure 2A 、 Figure 2B 、 Figure 2C 、 Figure 3 、 Figure 4A 、 Figure 4B 、 Figure 4C and Figure 5 below.

[0070] Please refer to Figure 2A 、 Figure 2B 、 Figure 2C and Figure 3 . Figure 2A 、 Figure 2B 、 Figure 2C respectively illustrate the operation schematic diagrams of the power conversion circuit 100 in the first mode, the second mode, and the third mode when the input voltage Vin is greater than or equal to a preset value. Figure 1 The schematic diagrams of the power conversion circuit 100 operating in the first mode, the second mode, and the third mode are shown. Figure 3 Illustrates Figure 2A 、 Figure 2B and Figure 2C The timing diagrams of the power conversion circuit 100 operating in the first mode during the time interval T1, in the second mode during the time intervals T2 and T4, and in the third mode during the time interval T3. In one embodiment, the first mode may be a positive mode, the second mode may be a freewheeling mode, and the third mode may be a negative mode.

[0071] In Figure 2A 、 Figure 2B 、 Figure 2C and Figure 3 In the embodiments, the control circuit 130 transmits control signals CS1 to CS10 to switch the switches S1 to S10, and their duty cycles are less than or equal to 0.5.

[0072] As shown in Figure 2A and Figure 3 , when the input voltage Vin is greater than or equal to a preset value, the first mode is performed in the time interval T1. The switches S2, S3, S7, and S6, and the switches S9 and S10 in the switching circuit 111 are turned off, and the switches S1, S4, S5, and S8 are turned on to electrically connect the primary winding 112, the winding Ns2, and the winding Ns1 in series in sequence, so that the output inductor Lo is charged and the output capacitor Co generates the output voltage Vout.

[0073] In one embodiment, Figure 2A the output voltage Vout can be a positive voltage, but the present disclosure is not limited thereto. For example, when the input voltage Vin and the expected output voltage Vout are 48 volts and 12 volts respectively (i.e., the input voltage Vin is four times the output voltage Vout), the control circuit 130 sends high-level control signals (as shown in Figure 3 ) to the gate terminals of the switches S1, S4, S5, and S8 to control the states of the switches S1, S4, S5, and S8 to be turned on. The control circuit 130 sends low-level control signals (as shown in Figure 3 ) to the gate terminals of the switches S2, S3, S6, S7, and S9 and S10 to turn them off.

[0074] The conduction paths generated due to the conduction of switches S1, S4, S5, and S8 are in the same direction as the polarities of windings Np1, Np2, Ns1, and Ns2 (i.e., the direction of the corresponding input current (not shown) of the input voltage Vin flows from the positive poles of windings Np1, Np2, Ns1, and Ns2 to the negative poles of windings Np1, Np2, Ns1, and Ns2). After the input voltage Vin is sequentially divided by windings Np1, Np2, Ns2, and Ns1, a positive voltage division (i.e., a positive voltage) is generated at node n4, causing the positive voltage division to charge the output inductor Lo to generate a positive output voltage Vout. In the above conduction paths, the turns ratios of the conducting primary winding 112, winding Ns1, and winding Ns2 are 2:1:1. The voltage at node n6 can be approximately equal to or half of the input voltage Vin, the voltage at node n3 can be approximately equal to or three-quarters of the input voltage Vin, and the voltage across between node n4 and node n5 can be approximately equal to or one-quarter of the input voltage Vin, but the present disclosure is not limited thereto.

[0075] As Figure 2B and Figure 3 shown, then, after the first mode is completed in time interval T1, during the second mode in time interval T2, switches S1 to S4, S7 to S10 are turned off in response to a low-level control signal. Switches S5 and S6 are turned on in response to a high-level control signal to demagnetize the output inductor Lo, charge the output capacitor Co, and continuously generate the output voltage Vout.

[0076] Please refer to Figure 2C and Figure 3 . After the second mode is completed, during the third mode in time interval T3, switches S1, S4, S5, S8, S9, and S10 are turned off. Switches S2, S3, S6, and S7 are turned on to electrically connect the primary winding 112, winding Ns1, and winding Ns2 in series in sequence, such that the output inductor Lo is charged and the output capacitor Co is discharged to generate the output voltage Vout.

[0077] In an embodiment as Figure 1 and Figure 2C shown, in the conduction path of the third mode, the turns ratios of the primary winding 112, winding Ns1, and winding Ns2 are adjusted to 2:1:1. The magnitude of the voltage at node n5 can be approximately equal to or half of the input voltage Vin, the magnitude of the voltage at node n3 can be approximately equal to or three-quarters of the input voltage Vin, and the magnitude of the voltage across between node n4 and node n6 can be approximately equal to or one-quarter of the input voltage Vin.

[0078] After completing the third mode, at time interval T4, the operation of the second mode is performed. Therefore, through Figure 2A , Figure 2B and Figure 2C operating, the power conversion circuit 100 sequentially performs the first mode, the second mode, the third mode, and the second mode in the working cycle Ts including four time intervals T1 to T4 to convert and stably generate the output voltage Vout from the input voltage Vin. This not only improves the conversion efficiency, expands the voltage range of the input voltage, but also avoids damage to the output inductor Lo.

[0079] In some other embodiments, when the input voltage Vin is greater than or equal to a preset value, in the first mode to the third mode, the switches S7 and S8 are maintained in the on state in response to the control signal that holds the high level.

[0080] Please refer to Figure 4A , Figure 4B , Figure 4C and Figure 5 . Figure 4A Figure 4B and Figure 4C respectively illustrate schematic diagrams of the operation of the power conversion circuit 100 in the first mode, the second mode, and the third mode when the input voltage Vin is less than the preset value Figure 1 .

[0081] In one embodiment, in the embodiments of Figure 4A , Figure 4B , Figure 4C and Figure 5 , the control circuit 130 transmits control signals CS1 to CS10 to switch the switches S1 to S10, and their duty cycles are less than or equal to 0.5.

[0082] As shown in Figure 4A and Figure 5 , when the input voltage Vin is less than the preset value (for example, the input voltage Vin and the expected output voltage Vout are 40 volts and 12 volts respectively), in the first mode during the time interval T1, the switches S2 to S4 and the switches S6 to S9 are turned off in response to the low-level control signal output by the control circuit 130. The switches S1, S5, and S10 are turned on in response to the high-level control signal output by the control circuit 130 to sequentially electrically connect the windings Np1, Ns2, and Ns1 in series, so that the output inductor Lo is charged and the output capacitor Co is discharged to generate the output voltage Vout.

[0083] In the cases such as Figure 1 and Figure 4AIn an embodiment shown, when windings Np1, Ns1, and Ns2 form a conduction path, the turns ratio of windings Np1, Ns1, and Ns2 is 1:1:1. Therefore, the voltages of nodes n3 and n6 can be approximately equal to two-thirds of the input voltage Vin, and the voltage across nodes n4 and n5 can be approximately equal to one-third of the input voltage Vin.

[0084] As Figure 4B and Figure 5 shown, after completing the first mode T1 in time interval T1, during the second mode in time interval T2, switches S1 to S4, and switches S7 to S10 are turned off in response to a low-level control signal. Switches S5 and S6 are turned on in response to a high-level control signal to demagnetize the output inductor Lo, charge the output capacitor Co, and continuously generate the output voltage Vout.

[0085] As Figure 4C and Figure 5 shown, after completing the second mode in time interval T2, a third mode is performed in time interval T3. Switches S1, S3 to S5, S7, S8, and S10 are turned off. Switches S2, S6, and S9 are turned on to electrically connect windings Np2, Ns1, and Ns2 in series in sequence, so that the output inductor Lo is charged and the output capacitor Co is discharged to generate the output voltage Vout.

[0086] In the embodiment as Figure 1 and Figure 4C shown, in the conduction path of the third mode, the turns ratio of windings Np2, Ns1, and Ns2 can be adjusted to 1:1:1, and the magnitudes of the voltages of nodes n5 and n3 can be approximately equal to two-thirds of the input voltage Vin. The magnitude of the voltage across nodes n4 and n6 can be approximately equal to one-third of the input voltage Vin.

[0087] After completing the third mode, during time interval T4, the operation of the second mode is performed. Therefore, through Figure 4A , Figure 4B and Figure 4C operation, the power conversion circuit 100 sequentially performs the first mode, the second mode, the third mode, and the second mode in a working cycle Ts including four time intervals T1 to T4 to convert the input voltage Vin and stably generate the output voltage Vout. In some embodiments, the conversion efficiency is the highest when the input voltage Vin is 40 volts.

[0088] Please refer to Figure 6 . Figure 6 The block diagram of a power conversion circuit 100 in another embodiment of the present disclosure is shown. ​

[0089] Compared with the embodiment of the power conversion circuit 100 in Figure 1 , the switch S7 is coupled between the switch S1 and the switch S3, and the drains of the switch S3 and the switch S7 are coupled to each other. Similarly, the switch S8 is coupled between the switch S2 and the switch S4, and the drains of the switch S4 and the switch S8 are coupled to each other.

[0090] Please refer to Figure 7 . Figure 7 illustrates a power conversion circuit for Figure 1 and a power conversion method 200 of the power conversion circuit for Figure 6 . It should be understood that additional steps may be present before, during, and after the process of Figure 7 , the steps of the process may also be added, reduced, and / or the order adjusted, and for additional embodiments of the power conversion method 200, some of the steps described below may be replaced or eliminated. In one embodiment, the power conversion method 200 includes the steps S210, S220, and S230 described below with reference to Figures 1 to 6 .

[0091] In step S210, as Figure 1 shown, the control circuit 130 determines whether the input voltage Vin is greater than or equal to a predicted preset value. When the input voltage Vin is greater than or equal to a multiple of the predicted output voltage Vout, step S220 is performed; otherwise, step S230 is performed.

[0092] In step S220, as in the embodiment of Figures 2A to 3 , the switching circuit 111 is turned off, and the transistors in the first transistor group including the switches S1, S3, S5, S7 and the second transistor group including the switches S2, S4, S6, S8 will be selectively turned on according to the control signals received as Figure 3 shown to output the output voltage Vout.

[0093] Relatively, in step S230, as in the embodiment of Figures 4A to 5 , the switches S3, S7 in the first transistor group and the switches S4, S8 in the second transistor group are turned off, and the switches S9, S10 in the switching circuit 111, the switches S1, S5 in the first transistor group, and the switches S2, S6 in the second transistor group are selectively turned on to output the output voltage.

[0094] In some embodiments, the power conversion method 200 further includes adjusting the duty cycles of the control switches S1 to S10 by the control circuit 130 according to the required output voltage Vout.

[0095] In summary, based on the above embodiments, the power topology design of the power conversion circuit 100 and the power conversion method 200 provided in this disclosure document controls the conduction state of the switches in the power conversion circuit 100 according to the magnitude relationship between the input voltage Vin and the output voltage Vout, so as to dynamically adjust the turn ratio when the primary winding 112, the winding Ns1, and the winding Ns2 are conducting, thereby expanding the application range of the input voltage Vin, improving the conversion efficiency, and reducing the cost of circuit components.

[0096] Although this disclosure document has been disclosed in the above embodiments, it is not intended to limit this disclosure document. Those of ordinary skill in the art can make various changes and modifications without departing from the spirit and scope of this disclosure document. Therefore, the protection scope of this disclosure document shall be subject to that defined by the appended claims.

Claims

1. A power conversion circuit, characterized in that, Comprising: A transformer includes a primary winding and a secondary winding; A bridge switch circuit, comprising: A first switch and a second switch, coupled to a first end of the primary winding at a first node; A third switch and a fourth switch, coupled to a second end of the primary winding at a second node, wherein the first switch and the second switch are coupled to an input voltage; And A switching circuit, coupled between the primary winding and the secondary winding, wherein a first end of the switching circuit is coupled between a first winding and a second winding in the primary winding; and An output conversion circuit, coupled to the secondary winding and the switching circuit, and includes an output inductor and an output capacitor, Wherein a first end of the output inductor and a first end of the output capacitor are coupled to a first output terminal, and a second end of the output inductor is coupled between a third winding and a fourth winding in the secondary winding.

2. The power conversion circuit according to claim 1, wherein The turns ratio of the primary winding, the third winding, and the fourth winding is 2:1:

1.

3. The power conversion circuit according to claim 1, wherein The number of turns of the first winding, the second winding, the third winding, and the fourth winding is the same.

4. The power conversion circuit according to claim 1, wherein A second end of the switching circuit is coupled between the third switch and the output conversion circuit, and a second end of the switching circuit is coupled between the fourth switch and the output conversion circuit.

5. The power conversion circuit according to claim 1, characterized in that, The output conversion circuit includes: A fifth switch, coupled between the third winding and ground; and A sixth switch, coupled between the fourth winding and the ground, Wherein the power conversion circuit further includes: A seventh switch, coupled between the third switch and the fifth switch; and An eighth switch, coupled between the fourth switch and the sixth switch.

6. The power conversion circuit according to claim 5, wherein When the input voltage is greater than or equal to a preset value, the switching circuit remains off, And in a first mode, the second switch, the third switch, the sixth switch, and the seventh switch are off, and the first switch, the fourth switch, the fifth switch, and the eighth switch are on to electrically connect the primary winding, the fourth winding, and the third winding in series in sequence, so that the output inductor is charged to generate the output voltage; In a second mode following the first mode, The first switch to the fourth switch, the seventh switch to the eighth switch, and the switching circuit are off, and the fifth switch and the sixth switch are on; And In a third mode following the second mode, The first switch, the fourth switch, the fifth switch, and the eighth switch are off, and the second switch, the third switch, the sixth switch, and the seventh switch are on to electrically connect the primary winding, the third winding, and the fourth winding in series in sequence, so that the output inductor is charged to generate the output voltage.

7. The power conversion circuit according to claim 6, wherein The duty cycles of the plurality of control signals received by the first switch to the eighth switch are less than 0.

5.

8. The power conversion circuit according to claim 7, wherein The preset value is 4 times the output voltage.

9. The power conversion circuit according to claim 5, characterized in that The switching circuit includes: A ninth switch, coupled between the first end of the switching circuit and the third winding; and A tenth switch, coupled between the first end of the switching circuit and the fourth winding; When the input voltage is less than a preset value and in a first mode, the second switch to the fourth switch and the sixth switch to the ninth switch are turned off, and the first switch, the fifth switch, and the tenth switch are turned on to electrically connect the first winding, the fourth winding, and the third winding in series in sequence, so that the output inductor is charged to generate the output voltage. In a second mode following the first mode, the first switch to the fourth switch and the seventh switch to the tenth switch are turned off, and the fifth switch and the sixth switch are turned on. In a third mode following the second mode, the first switch, the third switch to the fifth switch, the seventh switch, the eighth switch, and the tenth switch are turned off, and the second switch, the sixth switch, and the ninth switch are turned on to electrically connect the second winding, the third winding, and the fourth winding in series in sequence.

10. The power conversion circuit according to claim 5, wherein The third switch, the fourth switch, the seventh switch, and the eighth switch are N-type transistors. The sources of the third switch and the seventh switch are coupled to each other, and The sources of the fourth switch and the eighth switch are coupled to each other.

11. The power conversion circuit according to claim 1, characterized in that, The output conversion circuit includes: A fifth switch coupled between the third winding and the ground; and A sixth switch coupled between the fourth winding and the ground. Wherein the power conversion circuit further includes: A seventh switch coupled between the first switch and the third switch, and the drains of the third switch and the seventh switch are coupled to each other; and An eighth switch coupled between the second switch and the fourth switch, and the drains of the fourth switch and the eighth switch are coupled to each other.

12. A power conversion method, characterized in that, For a power conversion circuit, the power conversion circuit includes a first transistor group and a second transistor group connected in parallel between an input voltage and the ground. The power conversion circuit further includes a primary winding, a secondary winding, and a switching circuit coupled between the first transistor group and the second transistor group. The switching circuit has a first end coupled between a first winding and a second winding in the primary winding, a second end coupled to the first transistor group and the secondary winding, and a third end coupled to the second transistor group and the secondary winding. Wherein a node between a third winding and a fourth winding in the secondary winding is coupled to a first end of an output inductor. The power conversion method includes: When the input voltage is greater than or equal to a preset value, turn off the switching circuit, and selectively turn on the transistors in the first transistor group and the second transistor group to output an output voltage; And When the input voltage is less than the preset value, turn off the transistors in the first transistor group and in the second transistor group that are coupled between the primary winding and the secondary winding, and selectively turn on a first transistor or a second transistor in the switching circuit, the transistors in the first transistor group and in the second transistor group that are coupled between the input voltage and the primary winding, and the transistors in the first transistor group and in the second transistor group that are coupled between the secondary winding and the ground to output the output voltage.

13. The power conversion method according to claim 12, wherein Further includes: Adjust the duty cycle of a plurality of control signals for controlling the first transistor group, the second transistor group, and the switching circuit to be less than 0.

5.

14. The power conversion method according to claim 12, wherein When the input voltage is greater than or equal to the preset value, the primary winding and the secondary winding are connected in series and conduct, and When the input voltage is less than the preset value, the first winding or the second winding is connected in series with the secondary winding and conducts.

15. The power conversion method according to claim 12, characterized in that, Further includes: Adjust a plurality of control signals for controlling the first transistor group, the second transistor group, and the switching circuit according to the input voltage and the output voltage.

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