A direct current voltage conversion circuit

Abstract

The application relates to the field of high-voltage applications, and discloses a direct-current voltage conversion circuit which comprises a front-stage circuit, a transformer and a rear-stage circuit. The front-stage circuit is electromagnetically connected with the rear-stage circuit through the transformer. The front-stage circuit comprises an isolation module, the isolation module is used for receiving a primary input voltage and transmitting energy generated by the primary input voltage to the rear-stage circuit in the form of a secondary input voltage through the transformer, and the rear-stage circuit comprises a rectification module and a pressure control module, which are used for rectifying and controlling the pressure of the secondary input voltage respectively. The application reduces the switching loss and improves the conversion efficiency through reasonable timing control and a reasonable energy transmission path.

Description

Technical Field

[0001] This application relates to the field of high voltage applications, and in particular to a DC voltage conversion circuit. Background Technology

[0002] A DC-DC converter is a power conversion module that transforms an input voltage into an output voltage, typically used in power management and control applications in electronic devices. Compared to linear regulators, DC-DC converters offer higher efficiency and greater power conversion capability. This is because linear regulators regulate the output voltage by converting excess voltage into heat, while DC-DC converters use components such as capacitors and inductors to store electrical energy in the output voltage waveform, reducing power loss. Therefore, DC-DC converters are more efficient than linear regulators and can support greater power conversion capabilities.

[0003] DC-DC voltage conversion circuits are generally implemented using topologies such as flyback, forward, two-stage, and bridge circuits, depending on their power output. The power rating of a DC-DC voltage conversion circuit refers to the power of the power source it converts, usually expressed in watts (W) or kilowatts (kW). Based on power output, DC-DC voltage conversion circuits are generally divided into medium-power and high-power types. Medium-power DC-DC voltage conversion circuits typically refer to power conversion modules with output power between tens and hundreds of watts, suitable for power applications in various small and medium-sized electronic devices, such as communication equipment, industrial automation, and automotive electronics. High-power DC-DC voltage conversion circuits typically refer to power conversion modules with output power between hundreds and thousands of watts, suitable for power conversion needs in large electronic devices and industrial applications, such as electric vehicles, charging stations, and solar inverters.

[0004] Currently, in medium and high power DC voltage conversion circuits, in wide-range high-voltage input applications, the high input voltage means that the switching transistors bear a high voltage during operation. As the frequency increases, the switching losses become prominent, making it difficult to improve the conversion efficiency and power density. Summary of the Invention

[0005] In order to reduce the switching losses and improve the conversion efficiency of DC voltage conversion circuit, this application provides a DC voltage conversion circuit.

[0006] This application provides a DC voltage conversion circuit, which adopts the following technical solution: A DC-DC voltage conversion circuit includes a front-end circuit, a transformer, and a rear-end circuit. The front-end circuit is electromagnetically connected to the rear-end circuit through the transformer. The front-end circuit includes an isolation module for receiving a primary input voltage and transmitting the energy generated by the primary input voltage to the rear-end circuit as a secondary input voltage via the transformer. The rear-end circuit includes a rectifier module and a voltage control module for rectifying and controlling the secondary input voltage, respectively. The voltage control module includes a voltage control switch unit and a voltage regulator unit. One side of the voltage control switch unit is electrically connected to the rectifier module to receive and regulate the rectified secondary input voltage. The other side of the voltage control switch unit is electrically connected to the voltage regulator unit to output the regulated target voltage to the voltage regulator unit. The voltage regulator unit is used to be electrically connected to the load to supply power to the load based on the target voltage. The pressure control switch unit includes a first pressure control switch PS1 and a second pressure control switch PS2. The first pressure control switch PS1 has a first pressure control terminal for receiving a first pressure control signal to control the opening and closing of the first pressure control switch PS1. The second pressure control switch PS2 has a second pressure control terminal for receiving a second pressure control signal to control the opening and closing of the second pressure control switch PS2.

[0007] By adopting the above technical solution, the traditional DC voltage conversion circuit is connected to a filter circuit after rectification to smoothly input the voltage into the BUCK or BOOST circuit. This application eliminates the filter circuit added after rectification in the traditional DC voltage conversion circuit, and directly connects the voltage control module after rectification, which reduces the energy transmission path and related losses. The shortened energy transmission path also reduces the delay in power transmission and improves the conversion efficiency.

[0008] By directly connecting to the voltage control module, controlling the first voltage control switch PS1 through the first voltage control terminal and the second voltage control switch PS2 through the second voltage control terminal, the switching losses caused by the simultaneous conduction of both voltage control switches can be avoided. Simultaneously, it enables precise control and regulation of the output voltage, allowing the DC-DC voltage conversion circuit to continuously output a load that matches the load, meeting the load's requirements. This allows the voltage control module to function as both a voltage controller for the DC-DC voltage conversion circuit and a voltage regulator for the load. Furthermore, by controlling the timing of the on / off states of the first and second voltage control switches PS1 and PS2, zero-voltage on / off can be achieved in conjunction with the isolation module, further reducing the switching losses of the DC-DC voltage conversion circuit.

[0009] For example, the first voltage control switch PS1 is composed of a first voltage control transistor, the second voltage control switch PS2 is composed of a second voltage control transistor, the rectifier module has a first rectifier terminal, a second rectifier terminal, a third rectifier terminal and a fourth rectifier terminal, the first rectifier terminal and the second rectifier terminal are both electrically connected to the transformer, the third rectifier terminal is electrically connected to the drain of the first voltage control transistor, the fourth rectifier terminal is electrically connected to the source of the second voltage control transistor, the gate of the first voltage control transistor is used as the first voltage control terminal, the gate of the second voltage control transistor is used as the second voltage control terminal, and the source of the first voltage control transistor is electrically connected to the drain of the second voltage control transistor. The voltage regulator unit includes an energy storage inductor PL1 and an output capacitor PC1. One end of the energy storage inductor PL1 is electrically connected to the source of the first voltage-controlled transistor, and the other end is electrically connected to the positive terminal of the output capacitor PC1. The negative terminal of the output capacitor PC1 is electrically connected to the source of the second voltage-controlled transistor.

[0010] By adopting the above technical solution, the first and second voltage-controlled transistors have low on-resistance and short reverse recovery time, which can reduce conduction loss and switching loss and greatly improve conversion efficiency.

[0011] For example, the isolation module includes a first pre-stage switch Q1, a second pre-stage switch Q2, a third pre-stage switch Q3, a fourth pre-stage switch Q4, and a resonant inductor L1. The first pre-stage switch Q1 has a first connection terminal, a second connection terminal, and a first control terminal for receiving a first control signal to control the on / off state of the first pre-stage switch Q1. The second pre-stage switch Q2 has a third connection terminal, a fourth connection terminal, and a second control terminal for receiving a second control signal to control the on / off state of the second pre-stage switch Q2. The third pre-stage switch Q3 has a fifth connection terminal, a sixth connection terminal, and a third control terminal for receiving a third control signal to control the on / off state of the third pre-stage switch Q3. The fourth pre-stage switch Q4 has a seventh connection terminal, an eighth connection terminal, and a fourth control terminal for receiving a fourth control signal to control the on / off state of the fourth pre-stage switch Q4. The resonant inductor L1 has a ninth connection terminal and a tenth connection terminal. The first connection terminal is electrically connected to the positive terminal of the primary input voltage; the second connection terminal is electrically connected to the ninth connection terminal; the third connection terminal is electrically connected to the second connection terminal; the fourth connection terminal is electrically connected to the negative terminal of the primary input voltage; the fifth connection terminal is electrically connected to the positive terminal of the primary input voltage; the sixth connection terminal is electrically connected to the seventh connection terminal; the seventh connection terminal is electrically connected to one side of the primary coil of the transformer; the eighth connection terminal is electrically connected to the negative terminal of the primary input voltage; and the tenth connection terminal is electrically connected to the other side of the primary coil of the transformer.

[0012] By adopting the above technical solution, the first pre-stage switch Q1, the second pre-stage switch Q2, the third pre-stage switch Q3, the fourth pre-stage switch Q4, and the resonant inductor L1 constitute a full-bridge isolation circuit. By controlling the on / off state of the first pre-stage switch Q1 with a first control signal, the second pre-stage switch Q2 with a second control signal, the third pre-stage switch Q3 with a third control signal, and the fourth pre-stage switch Q4 with a fourth control signal, the switching states of each switch can be precisely controlled. This enables the transformation and adjustment of the primary input voltage to meet the needs of different loads. Furthermore, it allows for zero-voltage switching or zero-current switching, further reducing switching losses and improving conversion efficiency.

[0013] For example, in the operating state, the DC voltage conversion circuit performs voltage conversion sequentially in the following modes: In the first mode T1 stage, the first control signal triggers the first pre-stage switch Q1 to turn on, the fourth control signal triggers the fourth pre-stage switch Q4 to turn on, and the first control voltage signal triggers the first control voltage switch PS1 to turn on; in the second mode T2 stage, the first control signal triggers the first pre-stage switch Q1 to turn off, the first control voltage signal triggers the first control voltage switch PS1 to turn off, and the second control voltage signal triggers the second control voltage switch PS2 to turn on; in the third mode T3 stage, the second control signal triggers the second pre-stage switch Q2 to turn on; in the fourth mode T4 stage, the fourth control signal triggers the fourth pre-stage switch Q4 to turn off; in the fifth mode T5 stage, the third control signal triggers the third pre-stage switch Q3 to turn on, and the second control signal triggers the second pre-stage switch Q2 to turn off; in the sixth mode T6 stage, the first control voltage signal triggers the first control voltage switch PS1 to turn on.

[0014] By adopting the above technical solution, the first pre-stage switch Q1, the second pre-stage switch Q2, the third pre-stage switch Q3, and the fourth pre-stage switch Q4 all have parasitic capacitance and body diodes. In the first mode T1, the first pre-stage switch Q1 and the second pre-stage switch Q2 are turned on. Current flows through the first pre-stage switch Q1, the resonant inductor L1, and the fourth pre-stage switch Q4 back to the negative terminal of the primary input voltage. Energy is transferred from the primary coil of the transformer to the secondary coil, and then powers the load through the rectifier module and the voltage control module. In the second mode T2, the first pre-stage switch Q1 is turned off. With a sufficiently large resonant inductor L1, the current can remain approximately constant. The parasitic capacitance of the first pre-stage switch Q1 charges, while the parasitic capacitance of the second pre-stage switch Q2 discharges. When the parasitic capacitance of the second pre-stage switch Q2 has finished discharging, the body diode of the second pre-stage switch Q2 naturally turns on. At this time, the second voltage control switch PS2 turns on, providing a freewheeling path for the energy storage inductor PL1 and also powering the output capacitor PC1 and the load. In the third mode (T3), the voltage across the second pre-stage switch Q2 is clamped to zero potential by its body diode. Zero-voltage conduction of the second pre-stage switch Q2 at this time reduces switching losses. In the fourth mode (T4), the fourth pre-stage switch Q4 is turned off, its parasitic capacitance charges, and the parasitic capacitance of the third pre-stage switch Q3 discharges. The second control switch PS2 remains on, providing a freewheeling path for the energy storage inductor PL1 and supplying power to the output capacitor PC1 and the load. In the fifth mode (T5), the voltage across the third pre-stage switch Q3 is clamped to zero potential by its body diode. Zero-voltage conduction of the third pre-stage switch Q3 at this time reduces switching losses. In the sixth mode (T6), the second and third pre-stage switches Q2 and Q3 provide current paths. The first control switch PS1 is on, charging the energy storage inductor PL1 and supplying power to the output capacitor PC1 and the load.

[0015] The first, second, third, and fourth pre-stage switches Q1, Q2, Q3, and Q4 are all switched on at zero voltage, reducing switching losses. Specifically, in traditional DC-DC voltage conversion circuits, when current flows through a switch, the voltage rises or falls instantaneously across the switch, resulting in significant switching losses. This application, however, achieves near-zero voltage conduction by rationally controlling the switching time and signal, reducing the on-state voltage drop and thus lowering switching losses. Furthermore, by reducing energy losses during energy conversion, more input energy can be effectively transferred to the output, thereby improving overall conversion efficiency.

[0016] For example, the first control signal and the second control signal are complementary, the third control signal and the fourth control signal are complementary, and after the first pre-stage switch Q1 is turned off, the second pre-stage switch Q2 is turned on after a first dead time delay, and after the fourth pre-stage switch Q4 is turned off, the third pre-stage switch Q3 is turned on after a second dead time delay. A first phase shift angle is provided between the first control signal and the fourth control signal of the second pre-stage switch Q2, and a second phase shift angle is provided between the second control signal and the third control signal.

[0017] By adopting the above technical solution, the first and second control signals are complementary. After the first pre-stage switch Q1 is turned off, the second pre-stage switch Q2 is turned on. Specifically, the second pre-stage switch Q2 does not immediately turn on after the first pre-stage switch Q1 is turned off to allow time for the parasitic capacitance of the first pre-stage switch Q1 to charge and the parasitic capacitance of the second pre-stage switch Q2 to discharge, thereby achieving zero-voltage switching of the second pre-stage switch Q2 and reducing switching losses. Similarly, the third and fourth control signals are complementary. After the fourth pre-stage switch Q4 is turned off, the third pre-stage switch Q3 is turned on. The third pre-stage switch Q3 does not immediately turn on after the fourth pre-stage switch Q4 is turned off to allow time for the parasitic capacitance of the fourth pre-stage switch Q4 to charge and the parasitic capacitance of the third pre-stage switch Q3 to discharge, thereby achieving zero-voltage switching of the third pre-stage switch Q3 and reducing switching losses. Furthermore, the setting of the first and second phase shift angles is also to enable zero-voltage switching and reduce losses.

[0018] For example, in the first mode T1 stage, after both the first pre-stage switch Q1 and the fourth pre-stage switch Q4 are turned on, the first control voltage signal triggers the first control voltage switch PS1 to turn on. In the second mode T2 stage, before the first pre-stage switch Q1 is turned off, the first control voltage signal triggers the first control voltage switch PS1 to turn off. When the first pre-stage switch Q1 is turned off, the second control voltage signal triggers the second control voltage switch PS2 to turn on. In the fifth mode T5 stage, when the third pre-stage switch Q3 is turned on, the second control voltage signal triggers the second control voltage switch PS2 to turn off. In the sixth mode T6 stage, after the third pre-stage switch Q3 is turned on, the first control voltage signal triggers the first control voltage switch PS1 to turn on.

[0019] By adopting the above technical solution, after the first voltage control switch PS1 is turned off, the second voltage control switch PS2 is delayed in turning on, and after the second voltage control switch PS2 is turned off, the first voltage control switch PS1 is delayed in turning on. This avoids the simultaneous conduction of the first voltage control switch PS1 and the second voltage control switch PS2, which would form a short circuit, causing component overload, overheating, and damage. Furthermore, due to the presence of short-circuit current, electrical energy is wasted within the circuit and cannot be effectively transferred to the load, reducing conversion efficiency. Moreover, both the first voltage control switch PS1 and the second voltage control switch PS2 will simultaneously bear voltage and current loads, leading to increased power loss and further reducing conversion efficiency.

[0020] For example, the rectifier module is a bridge rectifier circuit, including a first rectifier switch SR1, a second rectifier switch SR2, a third rectifier switch SR3, and a fourth rectifier switch SR3. The first rectifier switch SR1 has a first transmission terminal, a second transmission terminal, and a first receiving terminal for receiving a first rectified signal to control the on / off state of the first rectifier switch SR1. The second rectifier switch SR2 has a third transmission terminal, a fourth transmission terminal, and a second receiving terminal for receiving a second rectified signal to control the on / off state of the second rectifier switch SR2. The third rectifier switch SR3 has a fifth transmission terminal, a sixth transmission terminal, and a third receiving terminal for receiving a third rectified signal to control the on / off state of the third rectifier switch SR3. The fourth rectifier switch SR3 has a seventh transmission terminal, an eighth transmission terminal, and a fourth receiving terminal for receiving a fourth rectified signal to control the on / off state of the fourth rectifier switch SR3. The first transmission terminal is electrically connected to one side of the secondary coil of the transformer, the second transmission terminal is electrically connected to the fifth transmission terminal, the third transmission terminal is electrically connected to the second transmission terminal, the fourth transmission terminal is electrically connected to the eighth transmission terminal, the sixth transmission terminal is electrically connected to the seventh transmission terminal, and the seventh transmission terminal is electrically connected to the other side of the secondary coil of the transformer. The first transmission terminal is used as the first rectifier terminal, the seventh transmission terminal is used as the second rectifier terminal, the fifth transmission terminal is used as the third rectifier terminal, and the eighth transmission terminal is used as the fourth rectifier terminal.

[0021] By adopting the above technical solution, the full-bridge rectifier has high conversion efficiency, can rectify in both the positive and negative half-cycles of the primary input voltage, and can also reduce switching losses during the rectification process and improve conversion efficiency by controlling the rectifier switch.

[0022] For example, when both the first pre-stage switch Q1 and the fourth pre-stage switch Q4 are turned on, the first rectified signal triggers the first rectified switch SR1 to turn on, and the fourth rectified signal triggers the fourth rectified switch SR3 to turn on. When both the second pre-stage switch Q2 and the third pre-stage switch Q3 are turned on, the third rectified signal triggers the third rectified switch SR3 to turn on, and the fourth rectified switch SR3 triggers the fourth rectified switch SR3 to turn on.

[0023] By adopting the above technical solution, when both the first pre-stage switch Q1 and the fourth pre-stage switch Q4 are turned on, the first rectifier switch SR1 and the fourth rectifier switch SR3 are turned on. At this time, the first voltage control switch PS1 is also turned on, charging the energy storage inductor PL1 and supplying power to the output capacitor PC1 and the load. When both the second pre-stage switch Q2 and the third pre-stage switch Q3 are turned on, the first voltage control switch PS1 is turned on again, charging the energy storage inductor PL1 and supplying power to the output capacitor PC1 and the load.

[0024] In summary, this application includes at least one of the following beneficial technical effects: 1. By directly connecting the voltage control module after the rectified output, the energy transmission path and related losses are reduced. Shortening the energy transmission path also reduces power transmission delay and improves conversion efficiency. Furthermore, controlling the first voltage control switch PS1 via the first voltage control terminal and the second voltage control switch PS2 via the second voltage control terminal avoids switching losses caused by both switches conducting simultaneously. This also enables precise control and adjustment of the output voltage, ensuring the DC-DC voltage conversion circuit continuously outputs a load that matches the load requirements. Therefore, the voltage control module can function as both a voltage controller for the DC-DC voltage conversion circuit and a voltage regulator for the load.

[0025] 2. By controlling the on and off of the first pre-stage switch Q1, the second pre-stage switch Q2, the third pre-stage switch Q3, the fourth pre-stage switch Q4, the first voltage control switch PS1, and the second voltage control switch PS2 in sequence, zero-voltage turn-off is achieved, further reducing the switching losses of the DC voltage conversion circuit. Attached Figure Description

[0026] Figure 1 This is a circuit diagram of a DC-DC voltage conversion circuit.

[0027] Figure 2 This is a timing diagram of a DC-DC voltage conversion circuit.

[0028] Figure 3 This is a state diagram of a DC voltage conversion circuit in the first mode T1 stage.

[0029] Figure 4 This is a state diagram of a DC voltage conversion circuit in the first mode T2 stage.

[0030] Figure 5 This is a state diagram of a DC voltage conversion circuit in the first mode T3 stage.

[0031] Figure 6 This is a state diagram of a DC voltage conversion circuit in the first mode T4 stage.

[0032] Figure 7 This is a state diagram of a DC voltage conversion circuit in the first mode T5 stage.

[0033] Figure 8 This is a state diagram of a DC voltage conversion circuit in the first mode T6 stage.

[0034] Explanation of reference numerals in the attached figures: 1. Pre-amplifier circuit; 11. Isolation module; 2. Transformer; 3. Post-amplifier circuit; 31. Rectifier module; 32. Voltage control module; 321. Voltage control switch unit; 322. Voltage regulator unit. Detailed Implementation

[0035] The present application will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the application and are not intended to limit the scope of the application.

[0036] This application discloses a DC voltage conversion circuit. (Refer to...) Figure 1 A DC-DC voltage conversion circuit is disclosed, comprising a front-end circuit 1, a transformer 2, and a rear-end circuit 3. The front-end circuit 1 is electromagnetically connected to the rear-end circuit 3 via the transformer 2. In traditional DC-DC voltage conversion circuits, in applications with wide-range high-voltage inputs, the high input voltage results in high voltage withstand during switching operation. As the frequency increases, switching losses become significant, making it difficult to improve conversion efficiency and power density. This application reduces switching losses and improves conversion efficiency through reasonable timing control and a reasonable energy transfer path.

[0037] The front-end circuit 1 includes an isolation module 11, which receives the primary input voltage and transmits the energy generated by the primary input voltage to the subsequent circuit 3 via a transformer 2 as a secondary input voltage. As an example, the isolation module 11 includes a first front-end switch Q1, a second front-end switch Q2, a third front-end switch Q3, a fourth front-end switch Q4, and a resonant inductor L1. The first front-end switch Q1 has a first connection terminal, a second connection terminal, and a first control terminal for receiving a first control signal to control the on / off state of the first front-end switch Q1. The second front-end switch Q2 has a third connection terminal, a fourth connection terminal, and a second control terminal for receiving a second control signal to control the on / off state of the second front-end switch Q2. The third front-end switch Q3 has a fifth connection terminal, a sixth connection terminal, and a third control terminal for receiving a third control signal to control the on / off state of the third front-end switch Q3. The fourth front-end switch Q4 has a seventh connection terminal, an eighth connection terminal, and a fourth control terminal for receiving a fourth control signal to control the on / off state of the fourth front-end switch Q4. The resonant inductor L1 has a ninth connection terminal and a tenth connection terminal. The first connection terminal is electrically connected to the positive terminal of the primary input voltage; the second connection terminal is electrically connected to the ninth connection terminal; the third connection terminal is electrically connected to the second connection terminal; the fourth connection terminal is electrically connected to the negative terminal of the primary input voltage; the fifth connection terminal is electrically connected to the positive terminal of the primary input voltage; the sixth connection terminal is electrically connected to the seventh connection terminal; the seventh connection terminal is electrically connected to one side of the primary coil of transformer 2; the eighth connection terminal is electrically connected to the negative terminal of the primary input voltage; and the tenth connection terminal is electrically connected to the other side of the primary coil of transformer 2.

[0038] Specifically, the aforementioned pre-stage switches can be composed of different types of electronic components. In some embodiments, the aforementioned pre-stage switches are composed of diodes; in some embodiments, the aforementioned pre-stage switches are composed of field-effect transistors (FETs); and in some embodiments, the aforementioned pre-stage switches are composed of insulated-gate bipolar transistors (IGBTs). As an example, the first pre-stage switch Q1 of this application is composed of a first pre-stage field-effect transistor, the second pre-stage switch Q2 is composed of a second pre-stage field-effect transistor, the third pre-stage switch Q3 is composed of a third pre-stage field-effect transistor, and the fourth pre-stage switch Q4 is composed of a fourth pre-stage field-effect transistor. Furthermore, the first front-end field-effect transistor (FET) is connected in parallel with a first parasitic capacitance C1 and a first body diode D1, meaning the first body diode D1 is also connected in parallel with the first parasitic capacitance C1. The second front-end FET is connected in parallel with a second parasitic capacitance C2 and a second body diode D2, meaning the second body diode D2 is also connected in parallel with the second parasitic capacitance C2. The third front-end FET is connected in parallel with a third parasitic capacitance C3 and a third body diode D3, meaning the third body diode D3 is also connected in parallel with the third parasitic capacitance C3. The fourth front-end FET is connected in parallel with a fourth parasitic capacitance C4 and a fourth body diode D4, meaning the fourth body diode D4 is also connected in parallel with the fourth parasitic capacitance C4. It is worth noting that commercially available FETs already include body diodes and parasitic capacitances in their packages; therefore, the front-end switch in this application can utilize a pre-packaged FET.

[0039] Specifically, the drain of the first front-end field-effect transistor is used as the first connection terminal, the source is used as the second connection terminal, and the gate is used as the first control terminal; the drain of the second front-end field-effect transistor is used as the third connection terminal, the source is used as the fourth connection terminal, and the gate is used as the second control terminal; the drain of the third front-end field-effect transistor is used as the fifth connection terminal, the source is used as the sixth connection terminal, and the gate is used as the third control terminal; the drain of the fourth front-end field-effect transistor is used as the seventh connection terminal, the source is used as the eighth connection terminal, and the gate is used as the fourth control terminal.

[0040] The subsequent circuit 3 includes a rectifier module 31 and a voltage control module 32, used to rectify and control the secondary input voltage, respectively. The rectifier module 31 has a first rectifier terminal, a second rectifier terminal, a third rectifier terminal, and a fourth rectifier terminal. The first and second rectifier terminals are both electrically connected to the transformer 2, and the third and fourth rectifier terminals are both electrically connected to the voltage control module 32.

[0041] In different embodiments, the rectifier module 31 can be a half-wave rectifier circuit, a full-wave rectifier circuit, or a bridge rectifier circuit. In this embodiment, the rectifier module 31 adopts a bridge rectifier circuit, including a first rectifier switch SR1, a second rectifier switch SR2, a third rectifier switch SR3, and a fourth rectifier switch SR3. The first rectifier switch SR1 has a first transmission terminal, a second transmission terminal, and a first receiving terminal for receiving a first rectified signal to control the on / off state of the first rectifier switch SR1. The second rectifier switch SR2 has a third transmission terminal, a fourth transmission terminal, and a second receiving terminal for receiving a second rectified signal to control the on / off state of the second rectifier switch SR2. The third rectifier switch SR3 has a fifth transmission terminal, a sixth transmission terminal, and a third receiving terminal for receiving a third rectified signal to control the on / off state of the third rectifier switch SR3. The fourth rectifier switch SR3 has a seventh transmission terminal, an eighth transmission terminal, and a fourth receiving terminal for receiving a fourth rectified signal to control the on / off state of the fourth rectifier switch SR3. The first transmission terminal serves as the first rectifier terminal, the seventh transmission terminal serves as the second rectifier terminal, the fifth transmission terminal serves as the third rectifier terminal, and the eighth transmission terminal serves as the fourth rectifier terminal. The first transmission terminal is electrically connected to one side of the secondary coil of transformer 2, the second transmission terminal is electrically connected to the fifth transmission terminal, the third transmission terminal is electrically connected to the second transmission terminal, the fourth transmission terminal is electrically connected to the eighth transmission terminal, the sixth transmission terminal is electrically connected to the seventh transmission terminal, and the seventh transmission terminal is electrically connected to the other side of the secondary coil of transformer 2. Full-bridge rectification has high conversion efficiency, rectifying both the positive and negative half-cycles of the primary input voltage. Furthermore, controlling the rectifier switches can reduce switching losses during rectification, thereby improving conversion efficiency.

[0042] Specifically, the first rectifier switch SR1, the second rectifier switch SR2, the third rectifier switch SR3, and the fourth rectifier switch SR3 can be constructed from different electronic components, such as diodes, field-effect transistors (FETs), or insulated-gate bipolar transistors (IGBTs). As an example, the first rectifier switch SR1, the second rectifier switch SR2, the third rectifier switch SR3, and the fourth rectifier switch SR3 are all constructed from field-effect transistors (FETs), and each of them has a capacitor and a diode connected in parallel. This application can use commercially available field-effect transistors with packaged body diodes and parasitic capacitances as rectifier switches.

[0043] The voltage control module 32 includes a voltage control switch unit 321 and a voltage regulator unit 322. One side of the voltage control switch unit 321 is electrically connected to the rectifier module 31 to receive and regulate the rectified secondary input voltage. The other side of the voltage control switch unit 321 is electrically connected to the voltage regulator unit 322 to output the regulated target voltage to the voltage regulator unit 322. The voltage regulator unit 322 is used to be electrically connected to the load to supply power to the load based on the target voltage.

[0044] The voltage control switch unit 321 includes a first voltage control switch PS1 and a second voltage control switch PS2. The first voltage control switch PS1 has a first voltage control terminal for receiving a first voltage control signal to control the on / off state of the first voltage control switch PS1, and the second voltage control switch PS2 has a second voltage control terminal for receiving a second voltage control signal to control the on / off state of the second voltage control switch PS2. By controlling the first voltage control switch PS1 through the first voltage control terminal and controlling the second voltage control switch PS2 through the second voltage control terminal, the switching losses caused by the simultaneous conduction of the two voltage control switches can be avoided. At the same time, it can also achieve precise control and regulation of the output voltage, and enable the DC voltage conversion circuit to continuously output a load that matches the load, meeting the load requirements. This allows the voltage control module 32 to act as both a voltage controller for the DC voltage conversion circuit and a voltage regulator for the load. Furthermore, by controlling the on / off state of the first voltage control switch PS1 and the second voltage control switch PS2 in a timing sequence, it can cooperate with the isolation module 11 to achieve zero-voltage shutdown, further reducing the switching losses of the DC voltage conversion circuit.

[0045] In different embodiments, the first voltage-controlled switch PS1 can be composed of different electronic components, and the second voltage-controlled switch PS2 can be composed of different electronic components. As an example, the first voltage-controlled switch PS1 is composed of a first voltage-controlled transistor, and the second voltage-controlled switch PS2 is composed of a second voltage-controlled transistor. Both the first and second voltage-controlled transistors are field-effect transistors. The drain of the first voltage-controlled transistor is electrically connected to the third rectifier terminal, the gate of the first voltage-controlled transistor serves as the first voltage-controlled terminal, the source of the first voltage-controlled transistor is electrically connected to the drain of the second voltage-controlled transistor, the source of the second voltage-controlled transistor is electrically connected to the fourth rectifier terminal, and the gate of the second voltage-controlled transistor serves as the second voltage-controlled terminal.

[0046] Furthermore, both the first voltage control switch PS1 and the second voltage control switch PS2 are connected in parallel with body diodes. In this embodiment, a field-effect transistor with a body diode packaged in the market can be selected.

[0047] The voltage regulator unit 322 includes an energy storage inductor PL1 and an output capacitor PC1. One end of the energy storage inductor PL1 is electrically connected to the source of the first voltage-controlled transistor, and the other end is electrically connected to the positive terminal of the output capacitor PC1. The negative terminal of the output capacitor PC1 is electrically connected to the source of the second voltage-controlled transistor.

[0048] To reduce switching losses, the first control signal, the second control signal, the third control signal, the fourth control signal, the first control voltage signal, and the second control voltage signal periodically control the corresponding switches to turn on and off.

[0049] Specifically, refer to Figure 2 and Figure 3In operation, the DC voltage conversion circuit performs voltage conversion sequentially in the following modes: In the first mode T1, the first control signal triggers the first pre-stage switch Q1 to turn on, the fourth control signal triggers the fourth pre-stage switch Q4 to turn on, the first rectification signal triggers the first rectifier switch SR1 to turn on, the fourth rectifier signal triggers the fourth rectifier switch SR3 to turn on, and the first voltage control signal triggers the first voltage control switch PS1 to turn on. At this time, the current returns to the negative terminal of the primary input voltage through the first pre-stage switch Q1, the resonant inductor L1, and the fourth pre-stage switch Q4. Energy is transferred from the primary coil of transformer 2 to the secondary coil of transformer 2, and through the first rectifier switch SR1, the first voltage control switch PS1, and the fourth rectifier switch SR3, supplies power to the load and the output capacitor PC1, and charges the energy storage inductor PL1.

[0050] Reference Figure 2 and Figure 4 In the second mode T2 stage, the first control signal triggers the first pre-stage switch Q1 to turn off, the first rectifier signal triggers the first rectifier switch SR1 to turn off, the fourth rectifier signal triggers the fourth rectifier switch SR3 to turn off, the first control voltage signal triggers the first control voltage switch PS1 to turn off, and the second control voltage signal triggers the second control voltage switch PS2 to turn on. At this time, if the resonant inductor L1 is large enough, the current can remain approximately constant. Simultaneously, the first parasitic capacitor C1 charges, and the second parasitic capacitor C2 discharges, preparing for the zero-voltage switching of the second pre-stage switch Q2. After the second parasitic capacitor C2 has finished discharging, the voltage at both the source and drain of the second pre-stage switch Q2 is zero, the second body diode naturally conducts, and the second control voltage switch PS2 turns on, providing a freewheeling path for the energy storage inductor PL1 and also supplying power to the output capacitor PC1 and the load.

[0051] Reference Figure 2 and Figure 5 In the third mode T3 stage, the second control signal triggers the second front-stage switch Q2 to turn on. At this time, the voltage across the second front-stage switch Q2 is clamped to zero potential by the second body diode. The zero-voltage conduction of the second front-stage switch Q2 at this time can reduce switching losses.

[0052] Reference Figure 2 and Figure 6 In the fourth mode T4 stage, the fourth control signal triggers the fourth pre-stage switch Q4 to turn off. At this time, the fourth parasitic capacitor C4 charges, and the third parasitic capacitor C3 discharges, preparing for the zero-voltage turn-on of the third pre-stage switch Q3. Simultaneously, the first rectifier switch SR1 and the second rectifier switch SR2 remain off, and the second voltage control switch PS2 remains on, providing a freewheeling path for the energy storage inductor PL1 and also supplying power to the output capacitor PC1 and the load.

[0053] Reference Figure 2 and Figure 7In the fifth mode, T5, the third control signal triggers the third pre-stage switch Q3 to turn on, and the second control signal triggers the second pre-stage switch Q2 to turn off. At this time, the voltage across the third pre-stage switch Q3 is clamped to zero potential by the third body diode. The zero-voltage conduction of the third pre-stage switch Q3 at this time reduces switching losses. Simultaneously, although the first rectifier switch SR1 and the second rectifier switch SR2 remain off, the third rectifier signal triggers the third rectifier switch SR3 to turn on, and the fourth rectifier signal triggers the fourth rectifier switch SR3 to turn on.

[0054] Reference Figure 2 and Figure 8 In the sixth mode T6 stage, the first control voltage signal triggers the first control voltage switch PS1 to turn on. At this time, the second pre-stage switch Q2 and the third pre-stage switch Q3 provide current paths, the first control voltage switch PS1 turns on, charging the energy storage inductor PL1, and simultaneously supplying power to the output capacitor PC1 and the load.

[0055] Reference Figure 2 Furthermore, the first and second control signals are complementary signals, as are the third and fourth control signals. After the first pre-stage switch Q1 is turned off, the second pre-stage switch Q2 is turned on after a first dead time delay. The second pre-stage switch Q2 does not immediately turn on after the first pre-stage switch Q1 is turned off to allow time for charging the parasitic capacitance of the first pre-stage switch Q1 and discharging the parasitic capacitance of the second pre-stage switch Q2, thus achieving zero-voltage switching of the second pre-stage switch Q2 and reducing switching losses. After the fourth pre-stage switch Q4 is turned off, the third pre-stage switch Q3 is turned on after a second dead time delay. The third pre-stage switch Q3 does not immediately turn on after the fourth pre-stage switch Q4 is turned off to allow time for charging the parasitic capacitance of the fourth pre-stage switch Q4 and discharging the parasitic capacitance of the third pre-stage switch Q3, thus achieving zero-voltage switching of the third pre-stage switch Q3. The first dead time and the second dead time are equal. A first phase shift angle is set between the first and fourth control signals of the second pre-stage switch Q2, and a second phase shift angle is set between the second and third control signals. Similarly, the setting of the first and second phase shift angles is also to enable zero-voltage conduction of the switch control voltage and reduce losses. Furthermore, the first phase shift angle is equal to the second phase shift angle, the first control signal leads the fourth control signal, and the second control signal leads the third control signal.

[0056] The on / off states of the first and second voltage control switches PS1 and PS2 also need to be limited to avoid them simultaneously forming a short circuit, increasing switching losses, and reducing conversion efficiency. Specifically, in the first mode T1 stage, after both the first and fourth pre-stage switches Q1 and Q4 are turned on, the first voltage control signal triggers the first voltage control switch PS1 to turn on. In the second mode T2 stage, before the first pre-stage switch Q1 is turned off, the first voltage control signal triggers the first voltage control switch PS1 to turn off. When the first pre-stage switch Q1 is turned off, the second voltage control signal triggers the second voltage control switch PS2 to turn on. In the fifth mode T5 stage, when the third pre-stage switch Q3 is turned on, the second voltage control signal triggers the second voltage control switch PS2 to turn off. In the sixth mode T6 stage, after the third pre-stage switch Q3 is turned on, the first voltage control signal triggers the first voltage control switch PS1 to turn on.

[0057] It is worth mentioning that the on / off state of the rectifier switch is related to the preceding switches. Specifically, when both the first preceding switch Q1 and the fourth preceding switch Q4 are on, the first rectified signal triggers the first rectifier switch SR1 to turn on, and the fourth rectified signal triggers the fourth rectifier switch SR3 to turn on. When both the second preceding switch Q2 and the third preceding switch Q3 are on, the third rectified signal triggers the third rectifier switch SR3 to turn on, and the fourth rectifier switch SR3 triggers the fourth rectifier switch SR3 to turn on.

[0058] In different embodiments, the DC voltage conversion circuit can be controlled by different methods. This application can control the duty cycle of the first and second control signals using the output voltage and the secondary voltage of transformer 2. The first, second, third, and fourth control signals are generated through dead-time control, a phase shifter, an isolator, and a driver. The duty cycle D of the rectified signal... s Determined by the following formula: t d +Δt=(1-D s )T s / 2. Where t d Let Δt be the dead time and Δt be the phase shift time. The phase shift time is obtained from the phase shift angle and the input voltage frequency. Assuming the frequency of the input voltage is f and the shift angle is α, then Δt = (α / 2π) / f.

[0059] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A DC voltage conversion circuit, characterized in that, The DC voltage conversion circuit includes a front-end circuit (1), a transformer (2), and a back-end circuit (3). The front-end circuit (1) is electromagnetically connected to the back-end circuit (3) through the transformer (2). The front-end circuit (1) includes an isolation module (11). The isolation module (11) is used to receive the primary input voltage and transmit the energy generated by the primary input voltage to the back-end circuit (3) through the transformer (2) as a secondary input voltage. The back-end circuit (3) includes a rectifier module (31) and a voltage control module (32) for rectifying and controlling the secondary input voltage, respectively. The isolation module (11) includes a full-bridge circuit composed of a first front-end switch Q1, a second front-end switch Q2, a third front-end switch Q3, and a fourth front-end switch Q4. The voltage control module (32) includes a voltage control switch unit (321) and a voltage regulator unit (322). One side of the voltage control switch unit (321) is electrically connected to the rectifier module (31) to receive and regulate the rectified secondary input voltage. The other side of the voltage control switch unit (321) is electrically connected to the voltage regulator unit (322) to output the regulated target voltage to the voltage regulator unit (322). The voltage regulator unit (322) is used to be electrically connected to the load to supply power to the load based on the target voltage. The pressure control switch unit (321) includes a first pressure control switch PS1 and a second pressure control switch PS2. The first pressure control switch PS1 has a first pressure control terminal for receiving a first pressure control signal to control the opening and closing of the first pressure control switch PS1. The second pressure control switch PS2 has a second pressure control terminal for receiving a second pressure control signal to control the opening and closing of the second pressure control switch PS2. In operation, the DC voltage conversion circuit performs voltage conversion sequentially in the following modes: In the first mode T1 stage, the first control signal triggers the first pre-stage switch Q1 to turn on, and the fourth control signal triggers the fourth pre-stage switch Q4 to turn on. Then, the first control voltage signal triggers the first control voltage switch PS1 to turn on. In the second mode T2 stage, before the first control signal triggers the first pre-stage switch Q1 to turn off, the first control voltage signal triggers the first control voltage switch PS1 to turn off. When the first pre-stage switch Q1 is turned off, the second control voltage signal triggers the second control voltage switch PS2 to turn on. In the third mode T3 stage, the second control signal triggers the second pre-stage switch Q2 to turn on. In the fourth mode T4 stage, the fourth control signal triggers the fourth pre-stage switch Q4 to turn off. In the fifth mode T5 stage, when the third control signal triggers the third pre-stage switch Q3 to turn on, the second control voltage signal triggers the second control voltage switch PS2 to turn off. The second control signal also triggers the second pre-stage switch Q2 to turn off. In the sixth mode T6 stage, after the third pre-stage switch Q3 turns on, the first control voltage signal triggers the first control voltage switch PS1 to turn on.

2. The DC voltage conversion circuit according to claim 1, characterized in that, The first voltage control switch PS1 is composed of a first voltage control transistor, and the second voltage control switch PS2 is composed of a second voltage control transistor. The rectifier module (31) has a first rectifier terminal, a second rectifier terminal, a third rectifier terminal and a fourth rectifier terminal. The first rectifier terminal and the second rectifier terminal are both electrically connected to the transformer (2). The third rectifier terminal is electrically connected to the drain of the first voltage control transistor. The fourth rectifier terminal is electrically connected to the source of the second voltage control transistor. The gate of the first voltage control transistor is used as the first voltage control terminal, and the gate of the second voltage control transistor is used as the second voltage control terminal. The source of the first voltage control transistor is electrically connected to the drain of the second voltage control transistor. The voltage regulator unit (322) includes an energy storage inductor PL1 and an output capacitor PC1. One end of the energy storage inductor PL1 is electrically connected to the source of the first voltage control transistor, and the other end is electrically connected to the positive terminal of the output capacitor PC1. The negative terminal of the output capacitor PC1 is electrically connected to the source of the second voltage control transistor.

3. The DC voltage conversion circuit according to claim 2, characterized in that, The isolation module (11) further includes a resonant inductor L1. The first pre-stage switch Q1 has a first connection terminal, a second connection terminal, and a first control terminal for receiving a first control signal to control the on / off state of the first pre-stage switch Q1. The second pre-stage switch Q2 has a third connection terminal, a fourth connection terminal, and a second control terminal for receiving a second control signal to control the on / off state of the second pre-stage switch Q2. The third pre-stage switch Q3 has a fifth connection terminal, a sixth connection terminal, and a third control terminal for receiving a third control signal to control the on / off state of the third pre-stage switch Q3. The fourth pre-stage switch Q4 has a seventh connection terminal, an eighth connection terminal, and a fourth control terminal for receiving a fourth control signal to control the on / off state of the fourth pre-stage switch Q4. The resonant inductor L1 has a ninth connection terminal and a tenth connection terminal. The first connection terminal is electrically connected to the positive terminal of the primary input voltage, the second connection terminal is electrically connected to the ninth connection terminal, the third connection terminal is electrically connected to the second connection terminal, the fourth connection terminal is electrically connected to the negative terminal of the primary input voltage, the fifth connection terminal is electrically connected to the positive terminal of the primary input voltage, the sixth connection terminal is electrically connected to the seventh connection terminal, the seventh connection terminal is electrically connected to one side of the primary coil of the transformer (2), the eighth connection terminal is electrically connected to the negative terminal of the primary input voltage, and the tenth connection terminal is electrically connected to the other side of the primary coil of the transformer (2).

4. The DC voltage conversion circuit according to claim 3, characterized in that, The first control signal and the second control signal are complementary, the third control signal and the fourth control signal are complementary, and after the first pre-stage switch Q1 is turned off, the second pre-stage switch Q2 is turned on after a first dead time delay. After the fourth pre-stage switch Q4 is turned off, the third pre-stage switch Q3 is turned on after a second dead time delay. A first phase shift angle is set between the first control signal and the fourth control signal of the second pre-stage switch Q2, and a second phase shift angle is set between the second control signal and the third control signal.

5. The DC voltage conversion circuit according to claim 4, characterized in that, The rectifier module (31) is a bridge rectifier circuit, including a first rectifier switch SR1, a second rectifier switch SR2, a third rectifier switch SR3, and a fourth rectifier switch SR3. The first rectifier switch SR1 has a first transmission terminal, a second transmission terminal, and a first receiving terminal for receiving a first rectified signal to control the first rectifier switch SR1 to turn on or off. The second rectifier switch SR2 has a third transmission terminal, a fourth transmission terminal, and a second receiving terminal for receiving a second rectified signal to control the second rectifier switch SR2 to turn on or off. The third rectifier switch SR3 has a fifth transmission terminal, a sixth transmission terminal, and a third receiving terminal for receiving a third rectified signal to control the third rectifier switch SR3 to turn on or off. The fourth rectifier switch SR3 has a seventh transmission terminal, an eighth transmission terminal, and a fourth receiving terminal for receiving a fourth rectified signal to control the fourth rectifier switch SR3 to turn on or off. The first transmission terminal is electrically connected to one side of the secondary coil of the transformer (2), the second transmission terminal is electrically connected to the fifth transmission terminal, the third transmission terminal is electrically connected to the second transmission terminal, the fourth transmission terminal is electrically connected to the eighth transmission terminal, the sixth transmission terminal is electrically connected to the seventh transmission terminal, and the seventh transmission terminal is electrically connected to the other side of the secondary coil of the transformer (2). The first transmission terminal is used as the first rectifier terminal, the seventh transmission terminal is used as the second rectifier terminal, the fifth transmission terminal is used as the third rectifier terminal, and the eighth transmission terminal is used as the fourth rectifier terminal.

6. The DC voltage conversion circuit according to claim 5, characterized in that, When both the first pre-stage switch Q1 and the fourth pre-stage switch Q4 are turned on, the first rectified signal triggers the first rectified switch SR1 to turn on, and the fourth rectified signal triggers the fourth rectified switch SR3 to turn on. When both the second pre-stage switch Q2 and the third pre-stage switch Q3 are turned on, the third rectified signal triggers the third rectified switch SR3 to turn on, and the fourth rectified switch SR3 triggers the fourth rectified switch SR3 to turn on.

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