A non-isolated converter, high efficiency converter and control method thereof

Abstract

The application provides a non-isolated converter, a high-efficiency converter and a control method thereof. The non-isolated converter comprises a transformer, an energy conversion circuit connected with a primary winding of the transformer, a rectifier circuit connected with a secondary winding of the transformer and a filter circuit connected with an output end of the rectifier circuit. The secondary winding comprises a first secondary winding and a second secondary winding, and the number of turns NS1 of the first secondary winding is equal to the number of turns NS2 of the second secondary winding. The energy conversion circuit is alternately turned on through a first switch branch and a second switch branch, so that part of the energy of the primary winding is alternately transmitted to the output through the first secondary winding and the second secondary winding. The application greatly reduces the loss of the transmission path from the input to the output through the first secondary winding and the second secondary winding. Moreover, each secondary winding only needs to be matched with one power tube to complete the energy transmission process of a single bridge arm to the output, thereby effectively reducing the cost and the board area of the power device on the secondary side.

Description

Technical Field

[0001] This invention relates to the field of switching power supplies, and in particular to a non-isolated converter, a high-efficiency converter, and a control method thereof. Background Technology

[0002] With the rapid growth of energy consumption in data centers, the problems of high energy conversion losses and poor flexibility and controllability of power conversion in traditional AC power supply systems for data centers are becoming increasingly prominent. DC power supply systems, on the other hand, have advantages such as fast and flexible control, high system efficiency, and large power supply capacity, making them an important direction for the development of data center power supply systems.

[0003] With the increasing computing power of server GPUs, data centers have higher requirements for power efficiency, power density, and transient current response speed to reduce energy consumption and improve computing power. The input voltage range for this type of operation is generally 40V to 60V, with an output voltage of 12V. Furthermore, as server power demand increases, users are choosing to abandon traditional isolated power supplies in search of lower-cost non-isolated solutions. However, traditional non-isolated solutions are limited by the inherent characteristics of the topology, making further improvements in size, efficiency, and power consumption difficult in this situation. Therefore, some design manufacturers have simply converted conventional isolation solutions (such as hard-switching full-bridge and LLC transformers) into non-isolated solutions to meet market demands. However, this approach is essentially no different from isolated solutions and does not effectively improve product efficiency, reduce product cost, or decrease size.

[0004] To address the aforementioned technical issues, patent CN 114257094 A proposes a device for reducing losses in transformers and rectifier components. However, because the maximum stress on the switching devices in its inverter section is Vin, high-voltage switching devices must be selected. For applications with an input voltage range of 40V to 60V, considering device reliability, the inverter section must use switching devices with a maximum voltage rating of 80V, preventing further improvement in system efficiency. Furthermore, the primary winding energy in this patent must be transferred to the filter circuit through the secondary winding, resulting in energy loss during primary winding energy transfer. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a non-isolated converter, a high-efficiency converter, and a control method thereof for use in non-isolated environments. This method can effectively reduce the voltage stress on the switching devices in the inverter section from the maximum Vin to Vin. Np / (Np+Ns) allows for the use of lower voltage-rated switching devices, thereby improving power supply efficiency and reducing product costs. Furthermore, the primary winding energy of this invention can bypass the secondary winding and be directly transferred to the filter circuit, thus further reducing energy losses in the primary winding during energy transfer and improving voltage efficiency.

[0006] In a first aspect, the present invention provides a non-isolated converter, including a transformer, an energy conversion circuit connected to the primary winding of the transformer, a rectifier circuit connected to the secondary winding of the transformer, and a filter circuit connected to the output terminal of the rectifier circuit.

[0007] The secondary winding includes a first secondary winding and a second secondary winding, and the number of turns NS1 of the first secondary winding is equal to the number of turns NS2 of the second secondary winding. The second end of the first secondary winding is connected to the first end of the second secondary winding and serves as the output end of the rectifier circuit. The energy conversion circuit includes a first switch branch and a second switch branch. The first switch branch is connected to the first end of the primary winding of the transformer and the output end of the rectifier circuit. The second switch branch is connected to the second end of the primary winding of the transformer and the output end of the rectifier circuit. The energy conversion circuit alternately turns on the first switch branch and the second switch branch, so that part of the energy of the primary winding is alternately transmitted to the output through the first stage winding and the second stage winding.

[0008] Optionally, the rectifier circuit includes a seventh switch and an eighth switch, wherein the seventh switch is connected between the first end of the primary winding and ground, and the eighth switch is connected between the second end of the secondary winding and ground; The first switching branch is used to form a current path in the first operating mode of the energy conversion circuit, where a portion of the energy from the primary winding is directly supplied to the filter circuit. The second switching branch is used to form a current path in the second operating mode of the energy conversion circuit, where a portion of the energy from the primary winding is directly supplied to the filter circuit. The seventh switch is used to form a current path from the primary winding to the filter circuit through the primary winding in the first operating mode of the energy conversion circuit. The eighth switch is used to form a current path from the primary winding to the secondary winding to the filter circuit in the second operating mode of the energy conversion circuit.

[0009] Optionally, the energy conversion circuit further includes a first switch S1 and a fifth switch S5, which together with the second switch S2 in the first switch branch and the sixth switch S6 in the second switch branch form a full-bridge circuit topology. The source of the first switch S1 is connected to the drain of the second switch S2 and the first end of the primary winding, respectively. The source of the fifth switch S5 is connected to the drain of the sixth switch S6 and the second end of the primary winding, respectively. The drain of the first switch S1 is connected to the drain of the fifth switch S5 and then connected to the input voltage. The source of the second switch S2 is connected to the source of the sixth switch S6 and then connected to the output terminal of the rectifier circuit.

[0010] Optionally, in the first operating mode, two current paths are formed. The first current path A1, through the fifth switch, the primary winding, and the first switch branch, forms a current path that directly supplies energy to the output terminal of the rectifier circuit. The second current path A2, through the seventh switch and the primary winding, forms a current path that supplies energy to the output terminal of the rectifier circuit.

[0011] Optionally, in the second operating mode, two current paths are formed. The first current path B1, through the first switch, the primary winding, and the second switch branch, forms a current path that directly supplies energy to the output of the rectifier circuit. The second current path B2, through the eighth switch and the secondary winding, forms a current path that supplies energy to the output of the rectifier circuit.

[0012] Optionally, the non-isolated converter further includes a discharge mode in which two current paths are formed. The first current path C1 forms a current path for the output inductor to discharge via the seventh switch and the first stage winding, and the second current path C forms a current path for the output inductor to discharge via the eighth switch and the second stage winding. The sum of the currents in the two current paths is equal to the output current of the non-isolated converter.

[0013] Optionally, the energy conversion circuit is a full-bridge, half-bridge, or push-pull circuit topology.

[0014] Secondly, the present invention also provides a high-efficiency converter suitable for non-isolated environments, comprising an energy conversion circuit, a rectifier circuit, and a filter circuit; the energy conversion circuit includes an inverter section and a coupling section; the inverter section is disposed at the front end of the coupling section and is used to invert the input voltage and transmit it to the coupling section; the coupling section includes a primary winding and a secondary winding of a transformer, disposed at the front end of the rectifier circuit; the filter circuit includes an inductor Lout and an output capacitor Cout, disposed at the rear end of the rectifier circuit, and directly supplies energy to the output terminal; the secondary winding includes a primary winding and a secondary winding. The primary winding directly supplies energy to the filter circuit through a switching branch connected in parallel between the primary winding of the transformer and the filter circuit. The primary winding, the secondary winding, and the rectifier circuit receive energy from the primary winding through a switching branch connected between the positive and negative outputs, and recover the energy of the output inductor Lout when there is no coupled energy transmission, and provide it to the filter circuit. The switching branches are alternately turned on, so that part of the energy of the primary winding is alternately transmitted to the output through the first-stage winding and the second-stage winding.

[0015] Optionally, the switch branch connected in parallel between the primary winding of the transformer and the filter circuit consists of two switch branches formed by the second switch S2 and the sixth switch S6. The connection relationship is that one end of the primary winding is connected to the drain of the second switch S2 and the other end is connected to the drain of the sixth switch S6. The source of the second switch S2 and the source of the sixth switch S6 are connected to the filter circuit. The switching branch connecting the positive and negative outputs consists of two switching branches formed by the seventh switch S7 and the eighth switch S8. The connection relationship is as follows: the source of the seventh switch S7 and the source of the eighth switch S8 are connected to a common ground; the drain of the seventh switch S7 is connected to one end of the first stage winding; the drain of the eighth switch S8 is connected to one end of the second stage winding; and the other ends of the first stage winding and the second stage winding are connected to the output filter inductor Lout.

[0016] Thirdly, the present invention provides a control method for a non-isolated converter, applicable to an energy conversion circuit with an isolated circuit topology, including an isolation transformer, an energy conversion circuit connected to the primary winding of the isolation transformer, a rectifier circuit connected to the secondary winding of the isolation transformer, and a filter circuit connected to the output terminal of the rectifier circuit. The secondary winding includes a first secondary winding and a second secondary winding; the energy conversion circuit includes a first switching branch and a second switching branch; the rectifier circuit includes a seventh switch and an eighth switch; The energy conversion circuit alternately turns on the first switch branch and the second switch branch, so that part of the energy of the primary winding is alternately transmitted to the output through the first primary winding and the second primary winding; In the first operating mode, a current path is formed by connecting the first terminal of the primary winding of the transformer to the output terminal of the rectifier circuit through the first switch branch, which forms a current path that directly supplies part of the energy of the primary winding to the filter circuit; and another current path is formed by connecting the seventh switch between the first terminal of the primary winding and ground through the primary winding to the filter circuit. In the second operating mode, a current path is formed by connecting the second terminal of the primary winding of the transformer to the output terminal of the rectifier circuit through the second switch branch, which forms a current path that directly supplies part of the energy of the primary winding to the filter circuit; and another current path is formed by connecting the eighth switch between the second terminal of the secondary winding and ground, which forms a current path that allows part of the energy of the primary winding to flow through the secondary winding to the filter circuit.

[0017] Fourthly, the present invention provides a power converter, including the non-isolated converter described in the first aspect, or including any of the high-efficiency converters described in the second aspect, or employing the control method of the non-isolated converter described in the third aspect, wherein the inverter section is a full-bridge, half-bridge, or push-pull circuit.

[0018] Compared with the prior art, the present invention has the following advantages: 1) This invention alternately turns on the first and second switching branches, allowing a portion of the energy from the primary winding to be transferred to the output through the first and second secondary windings alternately. This not only allows direct energy transfer to the output via the bridge arm of the primary winding, but also allows alternating energy transfer through either the first secondary winding NS1 or the second secondary winding NS2, significantly reducing energy loss along the input-to-output path. Furthermore, each secondary winding requires only one power transistor to complete the energy transfer process from a single bridge arm to the output, effectively reducing the cost and board area of ​​the secondary power devices. Simultaneously, since the reference ground for the drive voltage of the secondary power transistors is the output ground, a single driver IC can be used to drive the secondary power transistors, further reducing driving costs. 2) By connecting the first and second switching branches in parallel between the primary winding Np of the transformer and the filter circuit, the switching stress of the inverter section is reduced from the maximum Vin to the maximum Vin. Np / (Np+Ns) reduces the voltage stress plateau of the switches in the inverter circuit, which is beneficial to improving converter efficiency and reducing material costs; and the energy of the primary winding can be directly transferred to the filter circuit without passing through the secondary winding of the transformer, thereby reducing the loss of primary side energy in the process of transferring to the output and improving converter efficiency. 3) The first winding is connected by the seventh switch and the second winding is connected by the eighth switch to form current paths. This not only allows some of the energy of the primary winding to pass through the first or second winding to the filter circuit, but also only requires the seventh and eighth switches. This can greatly reduce the number of switching devices and other components, and effectively reduce the circuit manufacturing cost. Attached Figure Description

[0019] Figure 1 This is a block diagram illustrating the principle of a non-isolated converter according to the present invention. Figure 2This is a schematic diagram of a first embodiment of a non-isolated converter according to the present invention; Figure 3 This is a schematic diagram of the first operating mode of a first embodiment of a non-isolated converter according to the present invention; Figure 4 This is a schematic diagram of the second operating mode of a first embodiment of a non-isolated converter according to the present invention; Figure 5 This is a schematic diagram of the discharge mode of a first embodiment of a non-isolated converter according to the present invention; Figure 6 This is a timing diagram of the PWM control of the inverter section in a first embodiment of a non-isolated converter according to the present invention; Figure 7 This invention provides a timing diagram for complementary control in the inverter section of a non-isolated converter. Figure 8 This invention provides a timing diagram for phase-shift control in the inverter section of a non-isolated converter. Detailed Implementation

[0020] Specific embodiments of the present invention will now be described in detail. It should be noted that the embodiments described herein are for illustrative purposes only and are not intended to limit the invention. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention.

[0021] The existing non-isolated solutions require high-voltage switching devices because the maximum stress on the switching devices in the inverter section is Vin. Furthermore, the energy in the primary winding must be transferred to the filter circuit through the secondary winding, which prevents further improvement in system efficiency.

[0022] refer to Figure 1 and Figure 2 The present invention provides a non-isolated converter, including a transformer, an energy conversion circuit connected to the primary winding of the transformer, a rectifier circuit connected to the secondary winding of the transformer, and a filter circuit connected to the output terminal of the rectifier circuit. The secondary winding includes a primary winding and a secondary winding, and the number of turns NS1 of the primary winding is equal to the number of turns NS2 of the secondary winding; the energy conversion circuit includes a first switching branch and a second switching branch; the rectifier circuit includes a seventh switch and an eighth switch; The secondary winding includes a primary winding and a secondary winding, and the number of turns NS1 of the primary winding is equal to the number of turns NS2 of the secondary winding. The second end of the primary winding is connected to the first end of the secondary winding and serves as the output terminal of the rectifier circuit. The energy conversion circuit includes a first switching branch and a second switching branch. The first switching branch is connected to the first end of the primary winding of the transformer and the output end of the rectifier circuit. The second switching branch is connected to the second end of the primary winding of the transformer and the output end of the rectifier circuit. The energy conversion circuit alternately turns on the first switch branch and the second switch branch, so that part of the energy of the primary winding is transferred to the output through the first primary winding and the second primary winding alternately.

[0023] The rectifier circuit includes a seventh switch and an eighth switch. The seventh switch is connected between the first end of the primary winding and ground, and the eighth switch is connected between the second end of the secondary winding and ground. The first switching branch is used to form a current path in the first operating mode of the energy conversion circuit, where part of the energy of the primary winding is directly supplied to the filter circuit. The second switching branch is used to form a current path in the second operating mode of the energy conversion circuit, where part of the energy of the primary winding is directly supplied to the filter circuit. The seventh switch S7 is used to form a current path from the primary winding to the filter circuit in the first operating mode of the energy conversion circuit, where part of the energy of the primary winding passes through the primary winding. The eighth switch S8 is used to form a current path from the primary winding to the secondary winding to the filter circuit in the second operating mode of the energy conversion circuit.

[0024] The energy conversion circuit is a full-bridge, half-bridge, or push-pull circuit topology.

[0025] In this embodiment of the invention, the first switching branch and the second switching branch are connected in parallel between the primary winding Np of the transformer and the filter circuit, respectively, so that the switching stress of the inverter section is reduced from the maximum Vin to the maximum Vin. Np / (Np+Ns) reduces the voltage stress plateau of the switches in the inverter circuit, which is beneficial to improving the converter efficiency. Furthermore, the primary winding energy of this invention can be transferred to the rectifier and filter circuit directly without passing through the secondary winding, thereby further reducing the loss of the primary winding in the energy transfer process and improving voltage efficiency.

[0026] This invention, through the alternating switching of the first and second switching branches, allows a portion of the energy from the primary winding to be transferred to the output alternately via the first and second secondary windings. This not only allows direct energy transfer to the output through the primary winding's bridge arm but also allows alternating energy transfer to the output via either the secondary winding NS1 or NS2, significantly reducing energy loss along the input-to-output transmission path. Furthermore, since each secondary winding only requires one power transistor to complete the energy transfer process from a single bridge arm to the output, dividing the transformer's secondary winding into two secondary windings means that only two secondary power transistors are needed to complete a full operating cycle, reducing the cost and board space occupied by the secondary power devices. Simultaneously, since the reference ground for the secondary power transistor's drive voltage is the output ground, a single driver IC can be used to drive the secondary power transistors, further reducing driving costs.

[0027] First Embodiment refer to Figure 2 This is a schematic diagram of a first embodiment of a non-isolated converter according to the present invention. The non-isolated converter of the present invention includes an energy conversion circuit, a rectifier circuit, and a filter circuit. The energy conversion circuit includes an inverter section and a coupling section.

[0028] The inverter section includes input voltage Vin, common ground GND, input filter capacitor Cin, first switch S1, second switch S2, fifth switch S5, and sixth switch S6; the coupling section includes primary winding Np, first secondary winding Ns1, and second secondary winding Ns2; the rectifier circuit includes seventh switch S7 and eighth switch S8; and the filter circuit includes output inductor Lout and output filter capacitor Cout.

[0029] The negative terminal of the input voltage Vin and one end of the input filter capacitor Cin are connected to the common ground. The positive terminal of the input voltage Vin, the other end of the input filter capacitor Cin, the drain of the first switch S1, and the drain of the fifth switch S5 are connected. The source of the fifth switch S5 and the drain of the sixth switch S6 are connected to one end of the primary winding. The source of the first switch S1 and the drain of the second switch S2 are connected to the other end of the primary winding. The source of the second switch S2, the source of the switch S6, one end of the first primary winding, and one end of the second primary winding are connected to one end of the output filter inductor Lout. The other end of the first primary winding is connected to the drain of the seventh switch S7. The other end of the second primary winding is connected to the drain of the eighth switch S8. The other end of the output filter inductor Lout is connected to one end of the output filter capacitor Cout. The other end of the output filter capacitor Cout is connected to the common ground.

[0030] This invention discloses a non-isolated converter for use in non-isolated environments. It comprises four interconnected switching branches. The first and second switching branches are connected in parallel between the primary winding Np of the transformer and the filter circuit, respectively. The first and second switching branches are also connected in series between the positive input and positive output, respectively, forming a current path through which energy from the primary winding Np of the transformer can be directly supplied to the filter circuit. The third and fourth switching branches are connected in parallel between the positive and negative output, respectively, forming a current path through which energy from the primary winding Np indirectly reaches the filter circuit via the first primary winding Ns1 or the second primary winding Ns2. This also forms a current path that recovers energy from the output inductor Lout and supplies it to the rectifier filter circuit.

[0031] like Figure 2 As shown, in this embodiment, the first switch branch is composed of switch element S6, the second switch branch is composed of switch element S2, the third switch branch is composed of switch element S8, and the fourth switch branch is composed of switch element S7. In this way, the voltage stress on the inverter section's switch elements can be reduced from maximum Vin to maximum Vin. The formula Np / (Np+Ns) allows for the use of switching elements with lower withstand voltage, thereby improving system efficiency. Furthermore, a portion of the energy in the primary winding Np can be directly transferred to the filter circuit via the transformer secondary winding, further reducing losses and improving efficiency. The remaining energy is generated by the coupling between the primary and secondary windings.

[0032] This also includes drive control circuits for each switching element, used to generate control signals (e.g., pulse width modulation (PWM) signals) for the power supply circuit switching elements S1, S2, S3, S4, S5, S6, S7, and S8. Figure 2 As shown, control signal A controls power circuit switching elements S2 and S5; control signal B controls power circuit switching elements S1 and S6; control signal A inverse controls power circuit switching element S8; and control signal B inverse controls power circuit switching element S7. According to an embodiment of the present invention, for control reasons (e.g., compensating for delays in the drive circuit, different modulations during startup, etc.), control signal A can be divided into two control signals (A_S2 and A_S5), and control signal B can be divided into two control signals (B_S1 and B_S6). The first embodiment of the present invention uses PWM control in the inverter section, as shown in the timing diagram below. Figure 6 As shown.

[0033] Figure 3This is a schematic diagram of the first operating mode of a first embodiment of a high-efficiency converter according to the present invention. In the first operating mode, power circuit switching elements S1, S6, and S8 are open, while power circuit switching elements S2, S5, and S7 are open. Current path A1 includes the current Ip from the primary winding Np via switching elements S5 and S2, and current path A2 includes the current Is1 from the primary winding Ns1 of the transformer via switching element S7.

[0034] Figure 4 This is a schematic diagram of the second operating mode of a first embodiment of a high-efficiency converter according to the present invention. In the second operating mode, power circuit switching elements S1, S6, and S8 are turned on, while power circuit switching elements S2, S5, and S7 are turned off. Current path B1 includes the current Ip from the primary winding Np via switching elements S1 and S6, and current path B2 includes the current Is2 from the secondary winding Ns2 of the transformer via switching element S8.

[0035] Figure 5 This is a schematic diagram of the discharge mode of a first embodiment of a high-efficiency converter according to the present invention. In the discharge mode, power circuit switching elements S1, S2, S5, and S6 are open, while power circuit switching elements S7 and S8 are open. Current path C1 includes the current through the recovery output inductor Lout via switching element S8, and current path C2 includes the current through the recovery output inductor Lout via switching element S7. The sum of the currents in circuit paths C1 and C2 equals the output current.

[0036] The control method for the high-efficiency converter of this invention defines a discharge phase when no energy is transferred from the input Vin to the output Vout, indicating that all energy transferred to the output comes from the output inductor Lout. The output is modulated according to the following formula: Vout = Vin D Ns / (Np+Ns), where D is the duty cycle implemented by PWM, defined as the sum of the on-time Ton of control signals A and B divided by the period.

[0037] The high-efficiency converter control method of this invention, during the charging phase, when energy is transferred from the input Vin to the output Vout and the output inductor Lout, the transformer primary winding current Ip is transferred to the output, instead of circulating only on the primary side of the converter. This is defined as Is = Iout. (1-Ns / (Np+Ns)) and Ip=Iout Ns / (Np+Ns), where Is is the current flowing through the primary winding Ns1 or the secondary winding Ns2 of the transformer, Ip is the current flowing through the primary winding Np of the transformer, Ns is the primary winding Ns1 or the secondary winding Ns2 of the transformer, Np is the primary winding of the transformer, and Iout is the output current of the non-isolated converter.

[0038] The inverter section of the energy conversion circuit, i.e., the power conversion circuit, can be a full-bridge, half-bridge, or push-pull circuit. Besides the PWM control used in the first embodiment, the inverter section can also employ complementary control or phase-shift control. Figure 7 This invention provides a timing diagram for complementary control in the inverter section of a high-efficiency converter. Figure 8 The timing diagram for phase-shift control in the inverter section of a high-efficiency converter of the present invention is shown below. Its working process can be analyzed with reference to the first embodiment, so it will not be described again.

[0039] The above embodiments should not be considered as limitations on the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. For those skilled in the art, several equivalent substitutions, improvements, and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A non-isolated converter comprising a transformer and an energy conversion circuit connected to a primary winding of the transformer, characterized in that: It also includes a rectifier circuit connected to the secondary winding of the transformer and a filter circuit connected to the output terminal of the rectifier circuit. The secondary winding includes a first secondary winding and a second secondary winding, and the number of turns NS1 of the first secondary winding is equal to the number of turns NS2 of the second secondary winding. The second end of the first secondary winding is connected to the first end of the second secondary winding and serves as the output end of the rectifier circuit. The energy conversion circuit includes a first switch branch and a second switch branch. The first switch branch is connected to the first end of the primary winding of the transformer and the output end of the rectifier circuit. The second switch branch is connected to the second end of the primary winding of the transformer and the output end of the rectifier circuit. The energy conversion circuit alternately turns on the first switch branch and the second switch branch, so that part of the energy of the primary winding is alternately transmitted to the output through the first stage winding and the second stage winding.

2. The non-isolated converter of claim 1, wherein: The rectifier circuit includes a seventh switch and an eighth switch. The seventh switch is connected between the first end of the first primary winding and ground, and the eighth switch is connected between the second end of the second secondary winding and ground. The first switching branch is used to form a current path in the first operating mode of the energy conversion circuit, where a portion of the energy from the primary winding is directly supplied to the filter circuit. The second switching branch is used to form a current path in the second operating mode of the energy conversion circuit, where a portion of the energy from the primary winding is directly supplied to the filter circuit. The seventh switch is used to form a current path from the primary winding to the filter circuit in the first operating mode of the energy conversion circuit, where a portion of the energy from the primary winding passes through the primary winding. The eighth switch is used to form a current path from the primary winding to the secondary winding to the filter circuit in the second operating mode of the energy conversion circuit.

3. The non-isolated converter of claim 1, wherein: The energy conversion circuit also includes a first switch S1 and a fifth switch S5, which together with the second switch S2 in the first switch branch and the sixth switch S6 in the second switch branch form a full-bridge circuit topology. The source of the first switch S1 is connected to the drain of the second switch S2 and the first end of the primary winding, respectively. The source of the fifth switch S5 is connected to the drain of the sixth switch S6 and the second end of the primary winding, respectively. The drain of the first switch S1 is connected to the drain of the fifth switch S5 and then connected to the input voltage. The source of the second switch S2 is connected to the source of the sixth switch S6 and then connected to the output terminal of the rectifier circuit.

4. The non-isolated converter of claim 1, wherein, In the first operating mode, two current paths are formed. The first current path A1, through the fifth switch, the primary winding, and the branch of the first switch, forms a current path that directly supplies energy to the output terminal of the rectifier circuit. The second current path A2, through the seventh switch and the primary winding, forms a current path that supplies energy to the output terminal of the rectifier circuit.

5. The non-isolated converter of claim 1, wherein, In the second operating mode, two current paths are formed. The first current path B1, through the first switch, the primary winding, and the second switch branch, forms a current path that directly supplies energy to the output of the rectifier circuit. The second current path B2, through the eighth switch and the secondary winding, forms a current path that supplies energy to the output of the rectifier circuit.

6. The non-isolated converter according to claim 1, characterized in that, The non-isolated converter also includes a discharge mode, in which two current paths are formed. The first current path C1 forms the current path for the output inductor to discharge through the seventh switch and the first stage winding, and the second current path C forms the current path for the output inductor to discharge through the eighth switch and the second stage winding. The sum of the currents in the two current paths is equal to the output current of the non-isolated converter.

7. A high-efficiency converter suitable for non-isolated environments, comprising an energy conversion circuit, a rectifier circuit, and a filter circuit; the energy conversion circuit includes an inverter section and a coupling section; the inverter section is disposed at the front end of the coupling section and is used to invert the input voltage and transmit it to the coupling section; the coupling section includes a primary winding and a secondary winding of a transformer and is disposed at the front end of the rectifier circuit; the filter circuit includes an inductor Lout and an output capacitor Cout and is disposed at the rear end of the rectifier circuit to directly supply energy to the output terminal, characterized in that: The secondary winding includes a primary winding and a secondary winding; The primary winding directly supplies energy to the filter circuit through a switching branch connected in parallel between the primary winding of the transformer and the filter circuit. The primary winding, the secondary winding, and the rectifier circuit receive energy from the primary winding through a switching branch connected between the positive and negative outputs, and recover the energy of the output inductor Lout when there is no coupled energy transmission, and provide it to the filter circuit. The switching branches are alternately turned on, so that part of the energy of the primary winding is alternately transmitted to the output through the first-stage winding and the second-stage winding.

8. The high-efficiency converter as described in claim 7, characterized in that, The parallel switching branch between the primary winding of the transformer and the filter circuit consists of two switching branches formed by the second switch S2 and the sixth switch S6. The connection relationship is that one end of the primary winding is connected to the drain of the second switch S2 and the other end is connected to the drain of the sixth switch S6. The source of the second switch S2 and the source of the sixth switch S6 are connected to the filter circuit. The switching branch connecting the positive and negative outputs consists of two switching branches formed by the seventh switch S7 and the eighth switch S8. The connection relationship is as follows: the source of the seventh switch S7 and the source of the eighth switch S8 are connected to a common ground; the drain of the seventh switch S7 is connected to one end of the first stage winding; the drain of the eighth switch S8 is connected to one end of the second stage winding; and the other ends of the first stage winding and the second stage winding are connected to the output filter inductor Lout.

9. A control method for a non-isolated converter, applicable to an energy conversion circuit with an isolated circuit topology, comprising an isolation transformer, an energy conversion circuit connected to the primary winding of the isolation transformer, a rectifier circuit connected to the secondary winding of the isolation transformer, and a filter circuit connected to the output terminal of the rectifier circuit, characterized in that: The secondary winding includes a primary winding and a secondary winding; the energy conversion circuit includes a first switching branch and a second switching branch; the rectifier circuit includes a seventh switch and an eighth switch; The energy conversion circuit alternately turns on the first switch branch and the second switch branch, so that part of the energy of the primary winding is alternately transmitted to the output through the first primary winding and the second primary winding; In the first operating mode, a current path is formed by connecting the first end of the primary winding of the transformer to the output end of the rectifier circuit through the first switch branch, which forms part of the energy of the primary winding directly to the filter circuit. By connecting the seventh switch between the first end of the primary winding and ground, a partial current path is formed for the energy of the primary winding to the filter circuit through the primary winding. In the second operating mode, a current path is formed by connecting the second end of the primary winding of the transformer to the output end of the rectifier circuit through the second switching branch, which forms part of the energy of the primary winding directly to the filter circuit. By connecting the eighth switch between the second end of the secondary winding and ground, a portion of the energy from the primary winding is formed through the secondary winding to another current path to the filter circuit.

10. A power converter, comprising the non-isolated converter according to any one of claims 1-6, or comprising the high-efficiency converter according to any one of claims 7-8, or employing the control method of the non-isolated converter according to claim 9, characterized in that, The inverter section is a full-bridge, half-bridge, or push-pull circuit.

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