A DC converter, an electronic device and a control method for the DC converter

Abstract

The present application provides a DC converter, an electronic device, and a control method for the DC converter, for improving the efficiency of the DC converter. The method includes: calculating a target transformation ratio, which is the transformation ratio between the DC converter input voltage and the DC converter's target output voltage; determining a first transformation ratio of the LLC resonant conversion unit from multiple voltage conversion gears of the LLC resonant conversion unit based on the target transformation ratio and the minimum transformation ratio of a first voltage regulation circuit; and determining a second transformation ratio of the first voltage regulation circuit based on the first transformation ratio and the target transformation ratio.

Description

Technical Field

[0001] The present application relates to the field of circuit technology, and in particular to a DC converter, an electronic device, and a control method for the DC converter. Background Art

[0002] The LLC resonant converter circuit is a common DC-DC voltage conversion circuit. Its ability to achieve soft switching of switching transistors is used in voltage converters within various types of power systems. For example, voltage converters within power systems such as electric / hybrid vehicle power management systems, photovoltaic power generation systems, telecommunication power supply systems, and data centers often require LLC resonant converter circuits for voltage conversion.

[0003] Generally speaking, the LLC resonant conversion circuit mainly includes: an inverter circuit, a resonant circuit, a transformer and a rectifier circuit. The inverter circuit is used to convert the DC voltage received at the input end into AC power and output it to the resonant circuit. The resonant circuit is used to realize soft switching of the inverter circuit. The transformer is used to output the AC power output by the resonant circuit to the rectifier circuit. The rectifier circuit is used to convert the AC power output by the transformer into DC power and output it.

[0004] In actual use, the voltage converter's input voltage can fluctuate within a certain range, and its voltage conversion ratio is adjustable, depending on the load's voltage regulation requirements. To achieve soft switching of the switches in the inverter circuit and improve conversion efficiency, the LLC resonant converter circuit has a fixed on-time sequence for the switches, and its switching frequency matches the resonant frequency of the resonant circuit. Consequently, the voltage conversion ratio of the LLC resonant converter circuit is fixed, making it difficult for the LLC resonant converter circuit to meet the voltage conversion requirements of the voltage converter.

[0005] In order to meet the voltage conversion requirements of the voltage converter, a two-stage converter architecture is currently proposed to meet the requirements of the voltage converter. Figure 1 As shown, the LLC resonant conversion circuit converts and outputs the voltage received by the voltage converter input terminal, and then regulates the DC voltage output by the LLC resonant conversion circuit through the voltage regulating circuit to output a voltage that meets the requirements of the voltage converter.

[0006] However, when the above solution is implemented, the overall efficiency of the two-stage series connection architecture is equal to the product of the two-stage efficiencies. Due to the low conversion efficiency of the voltage regulator circuit, the conversion efficiency of the DC converter will be directly reduced. In order to solve this problem, a quasi-parallel conversion two-stage converter architecture is proposed, such as Figure 2 As shown, the input end of the LLC resonant conversion circuit receives most of the input voltage and converts the received voltage into the voltage required by the voltage converter, and the input end of the voltage regulation circuit receives a small part of the input voltage and converts the received voltage into the voltage required by the voltage converter.

[0007] In specific implementation, the total efficiency of the voltage converter is the weighted average of the conversion efficiencies of the two circuits and the input voltage ratio. When the input voltage of the voltage converter increases, or the output voltage of the voltage converter decreases, since the voltage conversion ratio of the LLC resonant conversion circuit is fixed, it can only be achieved by increasing the voltage received by the input end of the voltage regulation circuit, which directly reduces the conversion efficiency of the voltage converter. Summary of the Invention

[0008] The present application provides a DC converter, an electronic device, and a control method for the DC converter, for improving the conversion efficiency of the DC converter.

[0009] In the first aspect, the present application provides a control method for a DC converter, which is applied to a DC converter. The DC converter includes an LLC resonant conversion unit and a first voltage regulation circuit. The LLC resonant conversion unit has multiple voltage conversion gears. The LLC resonant conversion unit includes a first input terminal, a second input terminal, a first output terminal, and a second output terminal. The first voltage regulation circuit includes a third input terminal, a fourth input terminal, a third output terminal, and a fourth output terminal. The second input terminal is connected to the third input terminal. The first output terminal is connected to the third output terminal, and the second output terminal is connected to the fourth output terminal. Specifically, the control method mainly includes the following steps:

[0010] A target transformation ratio is calculated, where the target transformation ratio is a transformation ratio between an input voltage of the DC converter and an output voltage of the DC converter; a first transformation ratio of the LLC resonant conversion unit is determined from a plurality of voltage conversion gears of the LLC resonant conversion unit based on the target transformation ratio and a minimum transformation ratio of the first voltage regulation voltage; and a second transformation ratio of the first voltage regulation circuit is determined based on the target transformation ratio and the first transformation ratio.

[0011] Using the above method, the input ends of the LLC resonant conversion unit and the first voltage regulation circuit are connected in series, and the output ends are connected in parallel. The two conversion devices respectively convert a portion of the input voltage. Since the conversion efficiency of the LLC resonant conversion unit is greater than the conversion efficiency of the first voltage regulation circuit, the first transformation ratio of the LLC resonant conversion circuit can be increased as much as possible when the target conversion ratio of the DC converter and the minimum transformation ratio of the first voltage regulation circuit are determined. Since the input voltage of the LLC resonant conversion circuit is fixed, the larger the first transformation ratio, the more input voltage can be received by the LLC input end and the more power can be transmitted, thereby ensuring the conversion efficiency of the entire DC converter.

[0012] In one possible design, when determining the first transformation ratio of the LLC resonant conversion unit based on the target transformation ratio and the minimum transformation ratio of the voltage regulation circuit, the value range of the voltage conversion gear of the LLC resonant conversion circuit is determined based on the target transformation ratio and the minimum transformation ratio of the first voltage regulation voltage; and the largest voltage conversion gear within the value range of the voltage conversion gear of the LLC resonant conversion circuit is determined as the first transformation ratio.

[0013] By adopting the above method, since the efficiency of the LLC resonant conversion unit is relatively high, the efficiency of the switching power supply is further improved. The maximum achievable transformation ratio of the LLC resonant conversion unit can be found according to the minimum transformation ratio of the voltage regulating circuit, and the maximum transformation ratio can be used as the first transformation ratio of the LLC resonant conversion, so that the LLC resonant conversion unit can transmit more power.

[0014] In one possible implementation, determining the second transformation ratio using the target transformation ratio and the first transformation ratio includes: calculating a target input voltage of the LLC resonant conversion unit when the LLC resonant conversion circuit is in the first transformation ratio; calculating a first voltage difference between the DC converter input voltage and the target input voltage; and determining the transformation ratio between the first voltage difference and the output voltage of the DC converter as the second transformation ratio.

[0015] By adopting the above method, when the maximum achievable transformation ratio of the LLC resonant conversion unit is determined to enable the LLC resonant conversion unit to transmit more power, the first voltage regulating circuit is used to transmit the difference voltage between the LLC resonant conversion unit at the maximum transformation ratio and the total input voltage to achieve voltage fine-tuning.

[0016] Specifically, the LLC resonant conversion unit is controlled to be at a first transformation ratio, and the first voltage regulation circuit is controlled to be at a second transformation ratio.

[0017] In one possible implementation, the LLC resonant conversion unit includes: an inverter circuit, a resonant circuit, a transformer, and a rectifier circuit. Controlling the LLC resonant conversion unit to a first transformation ratio includes:

[0018] A drive signal is sent to the inverter circuit to control the LLC resonant conversion unit to be in a first transformation ratio. After the inverter circuit receives the drive signal, the period of the AC voltage output by the inverter circuit is the same as the resonant period of the resonant circuit.

[0019] By adopting the above scheme, the efficiency of the LLC resonant conversion unit can be improved because the period of the alternating current output by the inverter circuit in the LLC resonant conversion unit is consistent with the resonant period of the resonant circuit. In order to achieve the adjustable ratio of the LLC resonant conversion unit, the conduction timing of the switch tube can be changed by changing the driving signal when the period of the alternating current output by the inverter circuit is consistent with the resonant period of the resonant circuit, thereby expanding the ratio range of the LLC resonant conversion unit.

[0020] In a second aspect, an embodiment of the present application provides a DC converter, which mainly includes an LLC resonant conversion unit and a first voltage regulation circuit.

[0021] The LLC resonant conversion unit includes a first input terminal, a second input terminal, a first output terminal, and a second output terminal. The first voltage regulation circuit includes a third input terminal, a fourth input terminal, a third output terminal, and a fourth output terminal. The second input terminal is connected to the third input terminal, the first output terminal is connected to the third output terminal, and the second output terminal is connected to the fourth output terminal. The LLC resonant conversion unit may include an inverter circuit, a resonant circuit, a transformer, and a rectifier circuit.

[0022] Specifically, the inverter circuit is used to convert the first input voltage received through the first input terminal and the second input terminal into an AC voltage, and transmit the AC voltage to the rectifier circuit through the resonant circuit and the transformer. The rectifier circuit converts the AC voltage output by the transformer into the output voltage of the DC converter, and outputs the output voltage of the DC converter through the first output terminal and the second output terminal; the LLC resonant conversion unit has multiple voltage conversion gears; the first voltage regulating circuit is used to convert the second input voltage received through the third input terminal and the fourth input terminal into the output voltage of the DC converter, and output the output voltage of the DC converter through the third output terminal and the fourth output terminal. The total input voltage of the conversion circuit includes the first input voltage and the second input voltage.

[0023] In the above DC converter structure, the LLC resonant conversion unit and the input side of the first voltage regulating circuit are connected in series, and the output side is connected in parallel. Assuming that the efficiency of the LLC resonant conversion unit is a%, and the efficiency of the first voltage regulating circuit is b%, since the efficiency of the LLC resonant conversion unit is higher than that of the first voltage regulating circuit, the efficiency of the DC converter provided by the embodiment of the present application can be expressed as Since the efficiency of the DC converter is higher when the transformation ratio of the LLC resonant conversion unit is larger, the efficiency of the DC converter is higher. Achieving the maximum transformation ratio by adjusting the voltage conversion gear of the LLC resonant conversion unit is beneficial to improving the efficiency of the DC converter.

[0024] In one possible design, when the LLC resonant conversion unit is in any voltage conversion gear among multiple voltage conversion gears, the period of the AC voltage output by the inverter circuit is the same as the resonant period of the resonant circuit, and the output voltage of the LLC resonant conversion unit is greater than zero.

[0025] In one possible implementation, the voltage conversion efficiency of the LLC resonant conversion unit is greater than the voltage conversion efficiency of the first voltage regulation circuit, the voltage conversion efficiency of the LLC resonant conversion unit is the ratio of the output power of the LLC resonant conversion unit to the input power of the LLC resonant conversion unit, and the voltage conversion efficiency of the first voltage regulation circuit is the ratio of the output power of the first voltage regulation circuit to the input power of the first voltage regulation circuit.

[0026] In one possible implementation, a controller.

[0027] The controller is configured to control the LLC resonant conversion unit to convert the first input voltage into the output voltage of the DC converter, control the first voltage regulation circuit to convert the second input voltage into the output voltage of the DC converter, and adjust the voltage conversion gear of the LLC resonant conversion unit according to a target transformation ratio of the DC converter. The target transformation ratio is the ratio of the total input voltage to the target output voltage of the DC converter.

[0028] That is, the states of various circuits in the DC converter are adjusted under the control of the controller.

[0029] In a possible implementation, the LLC resonant conversion unit includes: an inverter circuit, a resonant circuit, a transformer, and a rectifier circuit.

[0030] Among them, the two input ends of the inverter circuit respectively form a first input end and a second input end, one output end of the inverter circuit is connected to one end of the resonant circuit, and the other output end of the inverter circuit is connected to one end of the primary winding of the transformer; the other end of the resonant circuit is connected to the other end of the primary winding of the transformer; the two ends of the secondary winding of the transformer are respectively connected to the two input ends of the rectifier circuit; and the two output ends of the rectifier circuit respectively form a first output end and a second output end.

[0031] The inverter circuit has a plurality of voltage conversion ratios, and the plurality of voltage conversion ratios correspond one-to-one to the plurality of voltage conversion gears of the plurality of voltage conversion units of the LLC resonant conversion unit.

[0032] By adopting this LLC resonant conversion circuit structure, the conversion ratio of the LLC resonant conversion unit can be adjusted by adjusting the conversion ratio of the inverter circuit, thereby facilitating the control of the LLC resonant conversion unit to a larger conversion ratio, transmitting more power, and further improving the efficiency of the DC converter.

[0033] Specifically, there are at least the following possible implementations of the inverter circuit:

[0034] Implementation method of inverter circuit 1:

[0035] The inverter circuit includes an H-bridge circuit and a first capacitor.

[0036] In which, the first end of the first bridge arm of the H-bridge circuit forms a first input end, the second end of the first bridge arm is connected to one end of the resonant circuit, the first end of the second bridge arm of the H-bridge circuit forms a second input end, the first end of the second bridge arm and the resonant circuit form a second input end, the second end of the second bridge arm is connected to the second end of the first bridge arm, the H-bridge circuit is used to receive a first drive signal and adjust the voltage conversion gear of the LLC resonant conversion unit according to the first drive signal; the first capacitor is connected across the middle node of the first bridge arm and the middle node of the second bridge arm.

[0037] By adopting the above-mentioned inverter circuit structure, the conduction timing of the switch tube in the H-bridge circuit can be controlled by the received drive signal to control the charging and discharging of the first capacitor, so that the inverter circuit can output different voltage values, thereby adjusting the transformation ratio of the LLC resonant conversion unit.

[0038] The second way to realize the inverter circuit:

[0039] The inverter circuit includes: a flying capacitor type multi-level half-bridge inverter circuit, a first switching tube and a second switching tube.

[0040] Among them, the first input end of the flying capacitor type multi-level half-bridge inverter circuit forms the first input end, the second input end of the flying capacitor type multi-level half-bridge inverter circuit forms the second input end, the first output end of the flying capacitor type multi-level half-bridge inverter circuit is connected to the first end of the first switch tube, the second output end of the flying capacitor type multi-level half-bridge inverter circuit is connected to the first end of the second switch tube, the flying capacitor type multi-level half-bridge inverter circuit is used to receive the second drive signal and adjust the voltage conversion gear of the LLC resonant conversion unit according to the second drive signal; the second end of the first switch tube is connected to one end of the resonant circuit; and the second end of the second switch tube is connected to the second end of the first switch tube.

[0041] By adopting the above-mentioned inverter circuit structure, the conduction timing of the switch tube in the flying capacitor type multi-level half-bridge inverter circuit can be controlled by the received drive signal to control the charging and discharging of multiple flying capacitors, so as to realize the inverter circuit outputting different voltage values, thereby realizing the adjustment of the transformation ratio of the LLC resonant conversion unit.

[0042] In one possible design, when the transformation ratio of a single LLC resonant conversion unit is limited, to further improve the conversion efficiency of the DC converter, the LLC resonant conversion unit includes N LLC resonant conversion circuits. Each of the N LLC resonant conversion circuits has multiple voltage conversion gears. N is an integer greater than or equal to 2.

[0043] The input ends of the N LLC resonant conversion circuits are connected in series to form a first input end and a second input end, and the output ends of the N LLC resonant conversion circuits are connected in parallel to form a first output end and a second output end.

[0044] In a possible design, the DC converter may further include: a plurality of third switching tubes, a plurality of fourth switching tubes, and a plurality of fifth switching tubes.

[0045] Each third switch is connected across the first terminals of the input terminals of two adjacent LLC resonant conversion circuits; each fourth switch is connected across the second terminals of the input terminals of two adjacent LLC resonant conversion circuits; one terminal of each fifth switch is connected to the second terminal of the input terminal of the first LLC resonant conversion unit in the two adjacent LLC resonant conversion circuits, and the other terminal of the fifth switch is connected to the first terminal of the input terminal of the second LLC resonant conversion unit in the two adjacent LLC resonant conversion circuits. The first terminal is the terminal at which the LLC resonant conversion circuit receives a high level, and the second terminal is the terminal at which the LLC resonant conversion circuit receives a low level.

[0046] By adopting the above-mentioned DC converter structure, when the input voltage and the output voltage change, resulting in a change in the target transformation ratio of the DC converter, the input sides of multiple LLC resonant conversion circuits can be changed from series connection to parallel connection, thereby adjusting the transformation ratio of the LLC resonant conversion unit, that is, adjusting the transformation ratio in real time according to the application scenario.

[0047] In one possible design, when the maximum transformation ratio of the LLC resonant conversion unit is much smaller than the target transformation ratio, in order to improve the efficiency of the DC converter, the DC converter further includes: a second voltage regulating circuit with higher conversion efficiency.

[0048] Among them, the input end of the second voltage regulating circuit is respectively connected in series with the input end of the first voltage regulating circuit and the input end of the LLC resonant conversion unit to form a first input end and a second input end, and the output end of the second voltage regulating circuit is respectively connected in parallel with the output end of the first voltage regulating circuit and the output end of the LLC resonant conversion circuit to form a first output end and a second output end.

[0049] In one possible design, the first voltage regulation circuit may be a Buck circuit.

[0050] In a third aspect, an embodiment of the present application provides a DC converter, which mainly includes an LLC resonant conversion unit and a first voltage regulation circuit.

[0051] The LLC resonant conversion unit includes a first input terminal, a second input terminal, a first output terminal, and a second output terminal. The first voltage regulation circuit includes a third input terminal, a fourth input terminal, a third input terminal, and a fourth output terminal. The LLC resonant conversion unit includes an inverter circuit, a resonant circuit, a transformer, and a rectifier circuit.

[0052] Specifically, the second output terminal is connected to the third output terminal, the first input terminal is connected to the third input terminal, and the second input terminal is connected to the fourth input terminal.

[0053] Among them, the inverter circuit can be used to convert the DC converter input voltage received through the first input terminal and the second input terminal into an AC voltage, and the AC voltage is transmitted to the rectifier circuit through the resonant circuit and the transformer. The rectifier circuit converts the AC voltage output by the transformer into a first output voltage and outputs it through the first output terminal and the second output terminal; the LLC resonant conversion unit has multiple voltage conversion gears; the first voltage regulating circuit is used to convert the DC converter input voltage received through the third input terminal and the fourth input terminal into a second output voltage, and output it through the third input terminal and the fourth output terminal. The total output voltage of the DC converter includes the first output voltage and the second output voltage.

[0054] Using the above-mentioned DC converter structure, the LLC resonant conversion unit and the input side of the first voltage regulating circuit are connected in parallel, and the output side is connected in series. It is mainly used in boost application scenarios and has similar technical effects to the second aspect. The technical effects of the corresponding scheme in the third aspect can refer to the technical effects that can be obtained by the corresponding scheme in the second aspect, and the repetitions are not described in detail.

[0055] In one possible design, when the LLC resonant conversion unit is in any voltage conversion gear among multiple voltage conversion gears, the period of the AC voltage output by the inverter circuit is the same as the resonant period of the resonant circuit, and the output voltage of the LLC resonant conversion unit is greater than zero.

[0056] In one possible design, the voltage conversion efficiency of the LLC resonant conversion unit is greater than the voltage conversion efficiency of the voltage regulation circuit. The voltage conversion efficiency of the LLC resonant conversion unit is the ratio of the output power of the LLC resonant conversion unit to the input power of the LLC resonant conversion unit, and the voltage conversion efficiency of the voltage regulation circuit is the ratio of the output power of the voltage regulation circuit to the input power of the voltage regulation circuit.

[0057] In one possible design, the DC converter further includes a controller.

[0058] The controller is configured to control the LLC resonant conversion unit to convert the input voltage of the DC converter into a first output voltage, control the voltage regulation circuit to convert the input voltage of the DC converter into a second output voltage, and adjust the voltage conversion gear of the LLC resonant conversion unit according to a target transformation ratio of the DC converter. The target transformation ratio is the ratio of the input voltage to the target output voltage.

[0059] In a fourth aspect, an embodiment of the present application provides a conversion system, which mainly includes a DC converter and a controller.

[0060] Specifically, the DC converter mainly includes an LLC resonant conversion unit and a first voltage regulation circuit. The LLC resonant conversion unit has multiple voltage conversion gears. The LLC resonant conversion unit includes a first input terminal, a second input terminal, a first output terminal, and a second output terminal. The first voltage regulation circuit includes a second input terminal, a third input terminal, a third output terminal, and a fourth output terminal. The LLC resonant conversion unit includes an inverter circuit, a resonant circuit, a transformer, and a rectifier circuit.

[0061] Specifically, the second input terminal is connected to the third input terminal, the first output terminal is connected to the third output terminal, and the second output terminal is connected to the fourth output terminal.

[0062] The controller is connected to the LLC resonant conversion unit and the first voltage regulating circuit, respectively. The controller can be used to: control the inverter circuit to convert the first input voltage received through the first input terminal and the second input terminal into an AC voltage, and transmit the AC voltage to the rectifier circuit through the resonant circuit and the transformer. The rectifier circuit converts the AC voltage output by the transformer into the output voltage of the system, and outputs the output voltage of the DC converter through the first output terminal and the second output terminal; control the first voltage regulating circuit to convert the second input voltage received through the third input terminal and the fourth input terminal into the output voltage of the conversion system, and output the output voltage of the DC converter through the third output terminal and the fourth output terminal. The total input voltage of the DC converter includes the first input voltage and the second input voltage.

[0063] By adopting the above-mentioned conversion system structure, the controller can configure a suitable maximum transformation ratio for the LLC resonant conversion unit from multiple voltage conversion gears, so that the LLC resonant conversion unit can transmit more power. Since the efficiency of the LLC resonant conversion unit is greater than the efficiency of the voltage regulation circuit, it is beneficial to improve the efficiency of the conversion system.

[0064] In a fifth aspect, an embodiment of the present application provides an electronic device, which may include a power supply and the DC converter provided in the above embodiment.

[0065] The DC converter may be connected to a power supply, and the DC converter may convert the voltage output by the power supply into a supply voltage for the load.

[0066] Optionally, the electronic device can switch power on and off.

[0067] Optionally, the electronic device may be a vehicle charger.

[0068] By using the above electronic device, the efficiency of the electronic device can be improved through the above DC converter.

[0069] These and other aspects of the present application will become more readily apparent from the description of the following embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 A schematic diagram of a two-stage converter architecture Figure 1 ;

[0071] Figure 2 A schematic diagram of a two-stage converter architecture Figure 2 ;

[0072] Figure 3 It is a structural diagram of an LLC resonant conversion unit;

[0073] Figure 4 A schematic diagram of a DC converter structure provided in an embodiment of the present application Figure 1 ;

[0074] Figure 5 A schematic diagram of a DC converter structure provided in an embodiment of the present application Figure 2 ;

[0075] Figure 6 A schematic flow chart of a method for adjusting the transformation ratio of a DC converter provided in an embodiment of the present application;

[0076] Figure 7 A schematic flow chart of a specific method for adjusting the transformation ratio of a DC converter provided in an embodiment of the present application;

[0077] Figure 8 A schematic diagram of a process for determining a transformation ratio change provided in an embodiment of the present application;

[0078] Figure 9 A schematic structural diagram of an LLC resonant conversion unit provided in an embodiment of the present application;

[0079] Figure 10 A schematic diagram of a driving signal provided in an embodiment of the present application;

[0080] Figure 11 A schematic diagram of the switching state of an LLC resonant conversion unit provided in an embodiment of the present application;

[0081] Figure 12 Schematic diagram of an equivalent circuit of an LLC resonant conversion unit provided in an embodiment of the present application;

[0082] Figure 13 A schematic diagram of the switching state of an LLC resonant conversion unit provided in an embodiment of the present application;

[0083] Figure 14 Schematic diagram of an equivalent circuit of an LLC resonant conversion unit provided in an embodiment of the present application;

[0084] Figure 15A schematic diagram of the switching state of an LLC resonant conversion unit provided in an embodiment of the present application;

[0085] Figure 16 Schematic diagram of an equivalent circuit of an LLC resonant conversion unit provided in an embodiment of the present application;

[0086] Figure 17 A schematic diagram of a driving signal provided in an embodiment of the present application;

[0087] Figure 18 A schematic diagram of the switching state of an LLC resonant conversion unit provided in an embodiment of the present application;

[0088] Figure 19 Schematic diagram of an equivalent circuit of an LLC resonant conversion unit provided in an embodiment of the present application;

[0089] Figure 20 A schematic structural diagram of an LLC resonant conversion unit provided in an embodiment of the present application;

[0090] Figure 21 A schematic structural diagram of an LLC resonant conversion unit provided in an embodiment of the present application;

[0091] Figure 22 A schematic structural diagram of an LLC resonant conversion unit provided in an embodiment of the present application;

[0092] Figure 23 A schematic structural diagram of an LLC resonant conversion unit provided in an embodiment of the present application;

[0093] Figure 24 A schematic diagram of a driving signal provided in an embodiment of the present application;

[0094] Figure 25 A schematic structural diagram of an LLC resonant conversion unit provided in an embodiment of the present application;

[0095] Figure 26 A schematic structural diagram of a first voltage regulating circuit provided in an embodiment of the present application;

[0096] Figure 27 A schematic structural diagram of a first voltage regulating circuit provided in an embodiment of the present application;

[0097] Figure 28 A schematic structural diagram of an LLC resonant conversion unit provided in an embodiment of the present application;

[0098] Figure 29 A schematic structural diagram of an LLC resonant conversion unit provided in an embodiment of the present application;

[0099] Figure 30A schematic structural diagram of an LLC resonant conversion unit provided in an embodiment of the present application;

[0100] Figure 31 This is a schematic structural diagram of another DC converter provided in an embodiment of the present application. DETAILED DESCRIPTION

[0101] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings. The specific operating methods in the method embodiments can also be applied to device embodiments or system embodiments. It should be noted that in the description of the present application, "at least one" refers to one or more, wherein multiple refers to two or more. In view of this, "multiple" can also be understood as "at least two" in the embodiments of the present invention. "And / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / ", unless otherwise specified, generally indicates that the previous and next associated objects are in an "or" relationship. In addition, it should be understood that in the description of the present application, words such as "first" and "second" are only used to distinguish the purpose of description, and cannot be understood as indicating or implying relative importance, nor can they be understood as indicating or implying order.

[0102] It should be noted that in the embodiments of the present application, "connection" refers to electrical connection, and the connection between two electrical components can be a direct or indirect connection between the two electrical components. For example, the connection between A and B can be either a direct connection between A and B, or an indirect connection between A and B through one or more other electrical components. For example, the connection between A and B can also be a direct connection between A and C, and C and B can be directly connected, with A and B connected through C.

[0103] It should be noted that in the embodiments of the present application, the "transformation ratio" of the conversion circuit refers to the ratio between the larger of the input voltage and the output voltage of the conversion circuit and the smaller of the input voltage and the output voltage. If the conversion circuit performs step-down conversion, the output voltage of the conversion circuit is less than the input voltage of the conversion circuit, and the transformation ratio of the conversion circuit is input voltage / output voltage. If the conversion circuit performs step-up conversion, the output voltage of the conversion circuit is greater than the input voltage of the conversion circuit, and the transformation ratio of the conversion circuit is output voltage / input voltage.

[0104] With the development of power electronics, switching converters are gaining increasing application. Consequently, their design faces comprehensive performance requirements, including high power density, high efficiency, and fast dynamic characteristics. To achieve higher power density, increasing the switching frequency is often used to reduce the size of magnetic components in the converter, such as capacitors, inductors, and transformers. However, increasing the switching frequency increases switching losses, thereby reducing the efficiency of the switching converter.

[0105] Soft switching technology is one of the important technologies for switching converters to achieve high conversion efficiency. Among them, LLC resonant converters have been extensively researched and widely used. Figure 3 As shown in the figure, the LLC resonant converter mainly includes: an inverter circuit, a resonant circuit, a transformer, and a rectifier circuit. The first output terminal of the inverter circuit is connected to one end of the resonant circuit, the other output terminal of the inverter circuit is connected to one end of the primary winding of the transformer; the other end of the resonant circuit is connected to the other end of the primary winding of the transformer; and the two ends of the secondary winding of the transformer are respectively connected to the two input terminals of the rectifier circuit.

[0106] During operation, the switching transistors in the inverter circuit typically operate at a switching frequency with a 50% duty cycle. The switching frequency of the switching transistors can be adjusted to control the transformation ratio of the entire LLC resonant converter. When operating at the resonant frequency of the resonant circuit, the LLC resonant converter achieves soft switching and low conduction losses, achieving maximum efficiency. As the switching frequency deviates from the resonant frequency, the LLC resonant converter's efficiency decreases.

[0107] In specific implementation, in order to ensure the efficiency of the LLC resonant converter, the conduction timing and switching frequency of the switch tube in the inverter circuit are fixed, so that the switching frequency of the switch tube in the inverter is consistent with the resonant frequency of the resonant circuit to achieve maximum efficiency. In this case, the transformation ratio of the LLC resonant conversion circuit is fixed.

[0108] In actual power supply applications, it is usually necessary to adjust a variety of different output voltages, and the input voltage can also adapt to a certain wide range. The converter needs to output different transformation ratios to meet the power supply operation at different transformation ratios. The transformation ratio of the single-stage LLC resonant conversion converter is no longer able to meet the power supply requirements. Based on this, a two-stage converter power supply architecture is set up.

[0109] See also Figure 2 The schematic diagram of the two-stage converter power supply architecture is shown in Figure 1. The LLC resonant converter has a fixed voltage conversion range, and the Buck circuit is used to convert voltages that the LLC resonant converter cannot convert, thus achieving voltage regulation.

[0110] For example, the efficiency of the LLC resonant converter is 97%, the efficiency of the Buck circuit is 88%, and the transformation ratio of the LLC resonant converter is 30. Figure 2 The two-stage converter power supply architecture shown takes the input voltage as 40-60V and the output voltage as 0.6-1.2V as an example.

[0111] When the input voltage of the two-stage converter power supply architecture is 40V and the output voltage is 1.2V, the input voltage of the LLC resonant converter is 36V and the output voltage is 1.2V, the input voltage of the Buck circuit is 4V and the output voltage is 1.2V, then the total efficiency of the two-stage converter power supply architecture is 36 / 40*97%+4 / 40*88%≈96%; when the input voltage of the two-stage converter power supply architecture is 60V and the output voltage is 0.6V, the output voltage of the LLC resonant converter is 18V and the output voltage is 0.6V, the input voltage of the Buck circuit is 42V and the output voltage is 0.6V, then the total efficiency of the two-stage converter power supply architecture is 18 / 60*97%+42 / 60*88%≈91%. Therefore, Figure 2 In the converter structure shown, the smaller the ratio of the input voltage borne by the LLC resonant converter to the input voltage of the two-stage converter power supply architecture is, the lower the efficiency of the converter is.

[0112] In view of this, the present application provides a DC converter, which can be applied to a switching power supply, which can not only meet the transformation ratio requirements of the switching power supply, but also help improve the efficiency of the switching power supply.

[0113] like Figure 4 As shown, the DC converter 400 provided in the embodiment of the present application mainly includes an LLC resonant conversion unit 401 and a first voltage regulation circuit 402. The LLC resonant conversion unit 401 includes a first input terminal 11, a second input terminal 12, a first output terminal 13, and a second output terminal 14. The first voltage regulation circuit 402 includes a third input terminal 21, a fourth input terminal 22, a third output terminal 23, and a fourth output terminal 24.

[0114] The first input terminal 11 and the second input terminal 12 of the LLC resonant conversion unit 401 are used to receive the first input voltage Vi1 of the DC converter 400, and the third input terminal 21 and the fourth input terminal 22 of the first voltage regulating circuit 402 are used to receive the second input voltage Vi2 of the DC converter 400. The first input voltage Vi1 and the second output voltage Vi2 constitute the total input voltage Vi of the DC converter 400. That is, the input side (the first input terminal 11 and the second input terminal 12) of the LLC resonant conversion unit 401 is connected in series with the input side (the third input terminal 21 and the fourth input terminal 22) of the first voltage regulating circuit 402.

[0115] Since the input side of the LLC resonant conversion unit 401 and the input side of the first voltage regulating circuit 402 are connected in series, the LLC resonant conversion unit 401 and the first voltage regulating circuit 402 have the same input current. Figure 4 As shown, the voltage between the input terminals 11 and 12 is Vi1 , the voltage between the input terminals 21 and 22 is Vi2 , and the sum of the input voltage Vi1 and the input voltage Vi2 is the total input voltage Vi of the DC converter 400 .

[0116] In the embodiment of the present application, both the LLC resonant conversion unit 401 and the first voltage regulating circuit 402 can implement voltage conversion functions. Specifically, the LLC resonant conversion unit 401 can convert the input voltage Vi1 and output the converted voltage through output terminals 13 and 14. The first voltage regulating circuit 402 can convert the input voltage Vi2 and output the converted voltage through output terminals 23 and 24. Specifically, the LLC resonant conversion unit 401 includes an inverter circuit, a resonant circuit, a transformer, and a rectifier circuit.

[0117] When the above-mentioned LLC resonant conversion unit is used to convert the input voltage Vi1, the inverter circuit converts the input voltage Vi1 received through the input terminals 11 and 12 into an AC voltage, and transmits the AC voltage to the rectifier circuit through the resonant circuit and the transformer. The rectifier circuit converts the AC power output by the transformer into a DC voltage and outputs it.

[0118] like Figure 4 As shown, the output end of the LLC resonant conversion unit 401 is connected to the output end of the first voltage regulating circuit 402, the output end 13 of the LLC resonant conversion unit 401 is connected to the output end 23 of the first voltage regulating circuit 402, and the output end 14 of the LLC resonant conversion unit 401 is connected to the output end 24 of the first voltage regulating circuit 402. That is, the output side (the first output end 13 and the second output end 14) of the LLC resonant conversion unit 401 is connected in parallel with the output side (the third output end 23 and the fourth output end 24) of the first voltage regulating circuit 402. Therefore, the output voltage Vo of the LLC resonant conversion unit 401 and the first voltage regulating circuit 402 are the same, and the output voltage Vo is also the output voltage of the DC converter 400.

[0119] The DC converter 400 provided in the embodiments of the present application has high conversion efficiency. For example, assume that the input current of the DC converter 400 is Ii and the output current is Io. The output current of the LLC resonant conversion unit 401 is Io1, and the output current of the first voltage regulating circuit 402 is Io2. Since the output side of the LLC resonant conversion unit 401 and the output side of the first voltage regulating circuit 402 are connected in parallel, the sum of the output current Io1 of the LLC resonant conversion unit 401 and the output current Io2 of the first voltage regulating circuit 402 is the output current Io of the DC converter 400, that is, Io1+Io2=Io.

[0120] Assuming that the efficiency of the LLC resonant conversion unit 401 is a%, the efficiency a% of the LLC resonant conversion unit 401 can be understood as the ratio of the output power of the LLC resonant conversion unit 401 to the input power of the LLC resonant conversion unit 401 (mostly expressed as a percentage), and a can be any value greater than or equal to 0 and less than or equal to 100. The efficiency of the LLC resonant conversion unit satisfies the following formula 1:

[0121] (N1*Vo)*Ii*a%=Vo*Io1 (Formula 1)

[0122] Wherein, N1 is the transformation ratio of the LLC resonant conversion unit 401, hereinafter referred to as the first transformation ratio N1, N1*Vo=Vi1, and Vi1 is the input voltage of the LLC resonant conversion unit.

[0123] Assuming that the efficiency of the first voltage regulating circuit 402 is b%, the efficiency b% of the first voltage regulating circuit 402 can be understood as the ratio of the output power of the first voltage regulating circuit 402 to the input power of the first voltage regulating circuit 402 (usually expressed as a percentage), and b can be any value greater than or equal to 0 and less than or equal to 100. The efficiency of the first voltage regulating circuit satisfies the following formula 2:

[0124] (Vi-N1*Vo)*Ii*b%=Vo*Io2 (Formula 2)

[0125] Combining Formula 1 and Formula 2, it can be seen that the efficiency of the DC converter 400 satisfies the following Formula 3:

[0126]

[0127] Wherein, η represents the efficiency of the DC converter 400. Formula 3 can be further used to obtain the following formula 4:

[0128]

[0129] It can be seen from Formula 4 that when the efficiency a% of the LLC resonant conversion unit 401 is greater than the efficiency b% of the first voltage regulating circuit 402, is a positive value, and the larger the value of N1, the greater the efficiency η of the DC converter. Figure 2 The two-stage converter structure shown in this application Figure 4 The DC converter 600 can achieve greater efficiency by adjusting the voltage conversion gear of the LLC resonant conversion unit 401. Each voltage conversion gear corresponds to a transformation ratio of the LLC resonant conversion unit 401.

[0130] It should be noted that in order to achieve the efficiency of the LLC resonant conversion unit, when the LLC resonant conversion unit is in any of the multiple voltage conversion gears, the period of the AC voltage output by the inverter circuit is the same as the resonant period of the resonant circuit, and the output voltage of the LLC resonant conversion unit is greater than zero.

[0131] In a specific implementation, the LLC resonant conversion unit 401 and the first voltage regulation circuit 402 may be composed of components such as a switch tube, a diode, an inductor, and a capacitor. The operating states of the LLC resonant conversion unit 401 and the first voltage regulation circuit 402 may be adjusted by adjusting the operating states of these components (e.g., the switch tube) to adjust the transformation ratio of the LLC resonant conversion unit 401 and the first voltage regulation circuit 402.

[0132] In this application, the above working state can be adjusted by a controller. That is, the DC converter 400 may further include a controller 403, such as Figure 5 As shown, the controller 403 is connected to the LLC resonant conversion unit 401 and the first voltage regulating circuit 402, respectively. It can be used to control the LLC resonant conversion unit 401 to convert the first input voltage Vi1 into the output voltage V0 of the DC converter 400, control the first voltage regulating circuit 402 to convert the second input voltage Vi2 into the output voltage Vo of the DC converter 400, and adjust the voltage conversion gear of the LLC resonant conversion unit 401 according to the target transformation ratio of the DC converter. The target transformation ratio is the ratio between the total input voltage and the target output voltage of the DC converter.

[0133] Specifically, if the switching tubes in each circuit of the DC converter 400 are metal oxide semiconductor (MOS) tubes, the controller 403 can be connected to the gate of the MOS tube, thereby controlling the on and off of the MOS tube to enable the DC converter 400 to achieve voltage conversion; if the switching tubes in each circuit of the DC converter 400 are bipolar junction transistors (BJT), the controller 403 can be connected to the base of the BJT, thereby controlling the on and off of the BJT to enable the DC converter 400 to achieve voltage conversion.

[0134] In a specific implementation, the controller 403 can be any one of a microcontroller unit (MCU), a central processing unit (CPU), and a digital signal processor (DSP). Of course, the specific form of the controller 403 is not limited to the above examples.

[0135] In addition, since the LLC resonant conversion unit 401 and the first voltage regulating circuit 402 perform voltage conversion independently in the embodiment of the present application, the switching frequencies of the LLC resonant conversion unit 401 and the first voltage regulating circuit 402 do not need to be consistent.

[0136] As can be seen from Equation 4, the efficiency a% of the LLC resonant converter unit 401 is greater than the efficiency b% of the first voltage regulator circuit 402, and the greater the value of the first transformation ratio N1, the higher the efficiency of the DC converter 400. With the output voltage Vo fixed, the greater the value of N1, the greater the input voltage Vi1 (Vi1 = N1 * Vo) of the LLC resonant converter unit 402, and the more voltage is transmitted. Therefore, when the efficiency a% of the LLC resonant converter unit 401 is greater than the efficiency b% of the first voltage regulator circuit, the controller 403 can increase the transformation ratio of the LLC resonant converter unit 401 and decrease the transformation ratio of the first voltage regulator circuit 402.

[0137] Ideally, if the first voltage regulator circuit 402 has a step-down function, its transformation ratio N2 can be 1, i.e., Vo = Vi2. In other words, the first voltage regulator circuit 402 only transmits voltage and does not convert it. Since the losses in the first voltage regulator circuit 402 primarily occur during the voltage conversion process, when the second transformation ratio N2 is 1, it can be considered that the losses in the first voltage regulator circuit 402 are minimized, and less power is transmitted.

[0138] If the first voltage regulator circuit 402 has a boost function, the voltage regulation range of the first voltage regulator circuit can be increased. Ideally, the transformation ratio N2 of the first voltage regulator circuit 402 can be less than 1 and close to 0. In other words, the smaller the input voltage Vi2 of the first voltage regulator circuit 402, the less power the first voltage regulator circuit 402 transmits.

[0139] As previously described, when the efficiency a% of the LLC resonant conversion unit 401 is greater than the efficiency b% of the first voltage regulating circuit 402, configuring the LLC resonant conversion unit 402 with a larger transformation ratio can enable the LLC resonant conversion unit 401 to transmit more power, thereby further improving the efficiency of the DC converter 400. However, because the application scenario of the DC converter 400 is not very stable, such as fluctuations in the battery voltage and changes in the operating voltage of the load, the transformation ratio of the LLC resonant conversion unit 401 often needs to be dynamically changed as the application scenario changes.

[0140] In one possible implementation, the first transformation ratio N1 and the second transformation ratio N2 in the embodiment of the present application are adjustable. In the embodiment of the present application, the controller 403 can also detect the current total input voltage Vi and the target output voltage Va of the DC conversion. The current total input voltage Vi can be the output voltage of the battery connected to the DC converter 400, and the target output voltage Va of the DC converter 400 can be the operating voltage currently required by the load. As mentioned above, during the discharge process of the connected battery, the battery voltage will gradually decrease. Specifically, the load connected to the output terminal 13 and the output terminal 14 may have multiple operating states, and the operating voltage required in different operating states is different. For example, the load can be a GPU or a battery. When the battery is charging, the voltage at both ends of the battery gradually increases.

[0141] It should be understood that the output voltage Vo of the DC converter 400 may be the same as or different from the target output voltage Va. When the output voltage Vo of the DC converter is different from the target output voltage Va, the controller may adjust the transformation ratio of the DC converter to adjust the output voltage Vo of the DC converter to the desired target output voltage Va. The target output voltage is the voltage actually required by the load.

[0142] Exemplarily, the controller 403 may detect the current output voltage Vo and the total input voltage Vi. When the current output voltage Vo differs from the target output voltage Va of the DC converter 400, the controller 403 may adjust the transformation ratio of the LLC resonant conversion unit 401 and the first voltage regulation circuit 402 according to the total input voltage Vi, thereby adjusting the output voltage Vo of the DC converter 400 to the target output voltage Va.

[0143] Specifically, the controller 403 may execute the following Figure 6 The control method shown adjusts the above Figure 4 The transformation ratio of the LLC resonant conversion unit 401 and the first voltage regulating circuit 402 is increased to improve the conversion efficiency of the DC converter 400, which mainly includes the following steps:

[0144] S601: Calculate a target transformation ratio, which is the transformation ratio between the input voltage of the DC converter 400 and the target output voltage of the DC converter 400. The target transformation ratio is Na=Vi / Va.

[0145] S602: Determine a first transformation ratio of the LLC resonant conversion unit from a plurality of voltage conversion gears of the LLC resonant conversion unit according to the target transformation ratio and the minimum transformation ratio of the first voltage regulation circuit.

[0146] The first transformation ratio N1 is smaller than or equal to the difference between the target transformation ratio Na and the minimum transformation ratio of the first voltage regulating circuit 402 , and smaller than or equal to the maximum transformation ratio of the LLC resonant conversion unit 401 .

[0147] Generally speaking, the controller 403 can change the voltage conversion gear of the LLC resonant conversion unit 401 by controlling the timing and switching frequency of the drive signal of the switch tube in the inverter circuit of the LLC resonant conversion unit 401, thereby adjusting the first transformation ratio N1. The specific value of N1 determined by the controller is related to the structure of the LLC resonant conversion unit. The controller can flexibly select an implementation method for setting the transformation ratio of the LLC resonant conversion unit based on the specific structure of the LLC resonant conversion unit.

[0148] S603: Determine the second transformation ratio N2 of the first voltage regulating circuit 402 according to the first transformation ratio N1 and the target transformation ratio.

[0149] Specifically, the controller 402 can determine the input voltage Vi1 after adjusting the transformation ratio of the LLC resonant conversion unit 401 according to the set first transformation ratio N1, that is, the adjusted input voltage Vi1 is the product of the set first transformation ratio N1 and the target output voltage Va (Vi1=N1*Va).

[0150] The controller 403 can then determine the regulated input voltage Vi2 of the first voltage regulator circuit 402 based on the current total input voltage Vi, i.e., Vi2 = Vi - Vi1 = Vi - N1 * Va. In other words, the second transformation ratio N2 should be set to N2 = (Vi - N1 * Va) / Va. The controller can flexibly select an implementation method for setting the transformation ratio of the first voltage regulator circuit 402 based on the specific structure of the first voltage regulator circuit 402.

[0151] For ease of understanding, the present application embodiment takes the case where the efficiency of the LLC resonant conversion unit is a% and the efficiency of the first voltage regulating circuit is b% as an example. Figure 6 The control method shown is explained.

[0152] In the embodiment of the present application, the first transformation ratio N1 has a plurality of discontinuously adjustable transformation ratios, each of which corresponds to the first voltage conversion gear of the LLC resonant conversion unit 401 .

[0153] As described above, if the efficiency a% of the LLC resonant conversion unit 401 is greater than the efficiency b% of the first voltage regulation circuit 402, the input voltage Vi1 of the LLC resonant conversion unit 401 should be increased as much as possible. Therefore, in the case where the LLC resonant conversion unit 401 has a plurality of adjustable turns ratios that are discontinuous, the first turns ratio N1 can be the adjustable turns ratio that is less than the difference between the target turns ratio Na and the minimum turns ratio of the first voltage regulation circuit 402 and is closest to the target turns ratio Na among the plurality of adjustable turns ratios in the LLC resonant conversion unit.

[0154] Taking the case where the values of the plurality of adjustable turns ratios of the LLC resonant conversion unit 402 are consecutive integers (such as the adjustable turns ratios being 4, 3, 2, 1) as an example, the controller 403 can adopt the method as Figure 7 shown to adjust the first turns ratio N1 and the second turns ratio N2. As Figure 7 shown, it mainly includes the following steps:

[0155] S701: Detect the current total input voltage Vi and the target output voltage Va.

[0156] S702: The controller calculates the target turns ratio Na. Among them, the target turns ratio Na is the ratio between the total input voltage Vi and the target output voltage Va, that is, Na = Vi / Va.

[0157] S703: Detect whether the first voltage regulation circuit has a boosting function. If so, execute S704, otherwise execute S705.

[0158] S704: If the first voltage regulation circuit has a boosting function, the value range of the voltage conversion gear is less than or equal to the target turns ratio Na. Each voltage conversion gear corresponds to a first voltage turns ratio N1.

[0159] If the first voltage regulation circuit has a boosting function, in an ideal situation, the second turns ratio N2 of the first voltage regulation circuit can be close to 0. At this time, Vi2 < Va, and the first turns ratio N1 = (Vi - Vi2) / Va ≈ Na. That is to say, in an ideal situation, the second turns ratio N2 ≈ 0. Therefore, the value range of the first turns ratio N1 is N1 < Na and N1 is less than or equal to the maximum voltage conversion gear of the LLC resonant conversion unit.

[0160] S705: If the first voltage regulation circuit has a bucking function, the value range of the voltage conversion gear is less than the target turns ratio Na - 1.

[0161] If the first voltage regulating circuit has a step-down function, in an ideal situation, the second turns ratio N2 of the first voltage regulating circuit can reach 1. At this time, Vi2 = Va, and the first turns ratio N1 = (Vi - Vi2) / Va = Na - 1. That is to say, in an ideal situation, the first turns ratio N1 = Na - 1. Therefore, the value range of the first turns ratio N1 is N1 ≤ Na - 1 and less than or equal to the maximum voltage conversion gear of the LLC resonant conversion unit.

[0162] S706: Determine the maximum voltage conversion gear within the value range of the voltage conversion gear of the LLC resonant conversion unit as the first turns ratio.

[0163] For example, assume that the LLC resonant conversion unit has three voltage conversion gears: 3, 2, and 1. As Figure 8 shown, the total input voltage Vi is 3.4V, and the target output voltage Va is 1V. At this time, the target turns ratio Na is 3.4. If the first voltage regulating circuit 402 has a step-down function, then N1 ≤ Na - 1 = 2. Therefore, the voltage conversion gear of the LLC resonant conversion unit 401 can be 1 or 2, and N1max = 2. Therefore, the controller 403 can set the first turns ratio N1 to 2. If the first voltage regulating circuit has a step-up function, then N1 < Na ≈ 3.4. Therefore, the voltage conversion gear of the LLC resonant conversion unit can be 1, 2, or 3, and N1max = 3. Therefore, the controller can set the first turns ratio N1 to 3.

[0164] S707: Calculate the target input voltage of the LLC resonant conversion unit when the LLC resonant conversion unit is at the first turns ratio.

[0165] S708: Calculate the first voltage difference between the DC converter input voltage and the target input voltage.

[0166] S709: Determine the turns ratio between the first voltage difference and the output voltage of the DC converter as the second turns ratio.

[0167] As mentioned before, as shown in the input voltage Figure 8 shown, the controller can set the first turns ratio N1 to 3, so that the input voltage Vi1 is 3V, and the input voltage Vi2 = Vi - Vi1 = 0.4V. Then the second turns ratio N2 = Vi2 / Vo = 0. 4 / 1 = 0.4.

[0168] It can be seen from the above embodiments that based on the DC converter 400 provided in the embodiment of the present application, the controller 403 can flexibly adjust the transformation ratio of the LLC resonant conversion unit 401 and the first voltage regulating circuit according to the total input voltage Vi and the target output voltage Va of the DC converter, so that in application scenarios with different total input voltages Vi and target output voltages Va, the LLC resonant conversion unit 401 can receive as large an input voltage Vi1 as possible while adapting to the application scenario. Combined with the above formula 4, it can be seen that when the efficiency a% of the LLC resonant conversion unit, the efficiency b% of the first voltage regulating circuit and the output voltage Vo are fixed, when the input voltage Vi1=N1*Vo of the LLC resonant conversion unit increases, the efficiency of the DC converter will also increase accordingly. Therefore, using the embodiment of the present application Figure 6 and Figure 8 The method for setting the first transformation ratio N1 and the second transformation ratio N2 shown is beneficial to further improve the efficiency of the DC converter 400 .

[0169] In one achievable manner, when the DC converter provided by the embodiment of the present application is used to power a load, if the output voltage Vo deviates from the target output voltage Va due to a change in the voltage received on the input side or the load on the output side, the DC converter can be used. Figure 6 and Figure 8 The method for setting the first transformation ratio N1 and the second transformation ratio N2 shown reconfigures the transformation ratios of the LLC resonant conversion unit 401 and the first voltage regulation circuit.

[0170] In another achievable manner, when the DC converter provided in an embodiment of the present application is used to power a load, if the output voltage Vo deviates from the target output voltage Va due to a change in the voltage received on the input side or the load on the output side, the output voltage Vo can be brought into alignment with the target output voltage Va by adjusting the transformation ratio of the first voltage regulating circuit 402.

[0171] In one example, when the DC converter provided in an embodiment of the present application is used to power a load, if the load connected to the output terminals 13 and 14 of the DC converter increases, causing the output voltage Vo of the DC converter to be less than the target output voltage Va, the duty cycle of the switch tube in the first voltage regulation circuit 402 can be adjusted to adjust the transformation ratio N2 of the first voltage regulation circuit 402, thereby adjusting the output voltage Vo until the output voltage Vo is equal to the target output voltage Va.

[0172] In one example, when the DC converter provided in an embodiment of the present application is used to power a load, if a battery is connected to the input side of the DC converter, the voltage of the battery gradually decreases during the process of powering the load, causing the voltage Vo output by the DC converter to deviate from the target output voltage Va. The duty cycle of the switching tube in the first voltage regulation circuit 402 can be adjusted to adjust the transformation ratio N2 of the first voltage regulation circuit 402, thereby adjusting the output voltage Vo until the output voltage Vo is equal to the target output voltage Va.

[0173] As disclosed in the embodiment of the present application, there are multiple possible implementation structures of the LLC resonant conversion unit 401. Next, the embodiment of the present application further illustrates the DC converter 400 provided in the embodiment of the present application through the following examples.

[0174] Example 1 of a DC converter:

[0175] The embodiment of the present application provides a DC converter 400, such as Figure 9 As shown. The inverter circuit in the LLC resonant conversion unit 401 includes: a first capacitor C1 and a first H-bridge circuit composed of four switching tubes S1, S2, S3, and S4. The resonant circuit mainly includes: a resonant inductor including Lr and a resonant capacitor Cr. The primary winding of the transformer is connected in series with the resonant inductor Lr and the resonant capacitor Cr, and the secondary winding of the transformer is connected to a rectifier circuit composed of a second H-bridge circuit. The second H-bridge circuit mainly includes switching tubes S5, S6, S7, and S8. The resonant inductor Lr can be an independent inductor, or it can be the leakage inductance of the primary winding of the transformer, or the resonant inductor Lr is composed of a part of the independent inductor and a part of the leakage inductance of the primary winding of the transformer. Lm is the excitation winding of the transformer.

[0176] S1 and S2 are connected in series to form the first arm of the first H-bridge circuit, S3 and S4 are connected in series to form the second arm of the first H-bridge circuit, and C1 is connected between the middle node of the first arm and the middle node of the second arm. That is, the second end of S2 is connected to the first end of S1 and one end of C1, respectively, and the second end of S4 is connected to the first end of S3 and the other end of C2, respectively. Specifically, the first end of S1 is connected to input terminal 11, and the first end of S3 is connected to input terminal 12.

[0177] S5 and S6 are connected in series to form the first arm of the second H-bridge circuit, and S7 and S8 are connected in series to form the second arm of the second H-bridge circuit. That is, the second end of S6 is connected to the first end of S5, the second end of S8 is connected to the first end of S7, the first end of S5 is connected to the first end of S7 and one end of the secondary winding of the transformer, and the second end of S6 is connected to the second end of S8 and the other end of the secondary winding of the transformer. Specifically, the middle node of the first arm and the middle node of the second arm of the second H-bridge circuit are connected to output terminal 12 and output terminal 14, respectively. That is, the second end of S5 is connected to output terminal 13, and the second end of S7 is connected to output terminal 14.

[0178] Among them, the second end of S2 and the second end of S4 are both connected to one end of the resonant capacitor Cr, the other end of Cr is connected to one end of the resonant inductor Lr, the other end of Lr is connected to one end of the primary winding of the transformer, and the other end of the primary winding of the transformer is connected to the input end 12.

[0179] In a specific implementation, the first H-bridge circuit has multiple voltage conversion ratios, and the multiple voltage conversion ratios are one-to-one with the multiple voltage conversion gears of the LLC resonant conversion unit 401, and the multiple voltage conversion ratios are one-to-one with the multiple drive signals. The drive signal is used to control the conduction timing of the switch tubes S1, S2, S3 and S4 in the first H-bridge circuit. The voltage conversion gear represents a ratio relationship between the input voltage of the LLC resonant conversion unit and the output voltage of the LLC resonant conversion unit, and the ratio relationship is the first transformation ratio N1 in the embodiment of the present application. It should be noted that in the DC converter provided in the present application, the LLC resonant conversion unit has multiple voltage conversion gears, which means that there are multiple ratio relationships between the input voltage of the LLC resonant conversion unit and the output voltage of the LLC resonant conversion unit, for example, the multiple ratio relationships are 1:1, 1.2:1, 1.5:1, and 2:1. Under different voltage conversion gears, facing the same input voltage, the output voltage of the LLC resonant conversion unit is different.

[0180] In one possible implementation, Figure 9 As shown, the DC converter 400 may further include an input capacitor Cin1 and an input capacitor Cin2. One end of the input capacitor Cin1 is connected to the input terminal 11, and the other end of the input capacitor Cin1 is connected to the input terminal 12. The input capacitor Cin1 can filter the first input voltage Vi1. One end of the input voltage Cin2 is connected to the input terminal 21, and the other end of the input voltage Cin2 is connected to the input terminal 22. Cin2 can filter the second input voltage Vi2.

[0181] In one possible implementation, Figure 9As shown, the DC converter 400 may further include an output capacitor Cout. One end of the output capacitor Cout is connected to the output terminal 13 of the LLC resonant conversion unit 401, and the other end of the output capacitor Cout is connected to the output terminal 14 of the LLC resonant conversion unit 401. The output capacitor Cout can filter the output voltage Vo and reduce fluctuations in the output voltage Vo.

[0182] See also Figure 9 As shown, taking the period of the AC power output by the inverter circuit as T as an example, when the switches S1, S2, S3 and S4 receive corresponding different drive signals, the transformation ratio of the LLC resonant conversion unit satisfies the following relationship:

[0183] N1=2N h *N L (Formula 5)

[0184] Nh=Vi1 / Vh (Formula 6)

[0185] Where Vh is the peak-to-peak value of the output voltage of the inverter circuit. h It represents the transformation ratio between the input voltage Vi1 and the peak-to-peak value of the inverter circuit output voltage, and NL is the transformation ratio between the number of turns of the primary winding and the secondary winding of the transformer.

[0186] For ease of calculation and understanding, the embodiment of the present application is described below using the transformer's NL being equal to 1 as an example, and no further details will be given subsequently.

[0187] It should be noted that, since the period of the alternating current output by the inverter circuit is consistent with the resonant period of the resonant circuit, soft switching of the switch tube can be achieved, thereby ensuring the efficiency of the LLC resonant conversion unit 401 .

[0188] Figure 9 When switches S1, S2, S3, and S4 in the LLC resonant conversion circuit receive different drive signals, the LLC resonant conversion circuit is in different states and has different transformation ratios. When S1, S2, S3, and S4 receive different drive signals, the corresponding relationship between the drive signals and the output voltage of the first H-bridge circuit is shown in Table 1.

[0189] Table 1

[0190] S1 S2 S3 S4 <![CDATA[C1]]> Vh Status ① 0 0 1 1 -- 0 Status ② 1 0 1 0 Charge Vi1 / 2 Status ③ 0 1 0 1 discharge Vi1 / 2 Status ④ 1 1 0 0 -- 1Vi1

[0191] when Figure 9When the LLC resonant conversion unit 401 uses the driving signals shown in Table 1 to drive the states of the switches S1, S2, S3, and S4, the LLC resonant conversion unit has at least two adjustable ratios: 4 and 2. It should be noted that the adjustable ratio is the theoretically achievable ratio of the LLC resonant conversion unit 401. Due to factors such as parasitic resistance and parasitic inductance, there may be a slight deviation between the actual ratio of the LLC resonant conversion unit 401 and the adjustable ratio, but this does not affect the implementation of the technical solution of the present application.

[0192] The following describes in detail the transformation ratio process of the LLC resonant conversion unit 401 at two voltage conversion gears with reference to examples.

[0193] The first implementation method: the first transformation ratio N1 is 4.

[0194] Assume that each switch in the LLC resonant conversion unit 401 is turned on at high voltage and turned off at low voltage. Figure 10 When the driving signal is shown, the first transformation ratio N1 is 4. The controller sends the driving signal in the order of states ②①③① to control the switch tube to switch the state.

[0195] like Figure 10 As shown, the period of the alternating current is T, and the switching tubes S1, S2, S3 and S4 correspond to different driving signals respectively.

[0196] During the time period from 0 to T / 2, the status of each switch tube can be as follows: Figure 11 As shown, the switch tubes S1 and S3 are turned on, and the switch tubes S2 and S4 are turned off.

[0197] In this case, the switch tube S1, capacitor C1, switch tube S3, Cr, Lr and Lm form a path, and the equivalent circuit can be as follows: Figure 12 As shown. At this time, V h It is 1 / 2Vi1.

[0198] During the time period from T / 2 to T, the states of the various switches can be as follows: Figure 13 As shown, the switch tubes S3 and S4 are turned on, and the switch tubes S1 and S2 are turned off.

[0199] In this case, the switch tube S3, the switch tube S4, Cr, Lr and Lm form a path, and the equivalent circuit can be as follows: Figure 14 Since the first capacitor is open circuited and the output terminal of the first H-bridge circuit is directly connected to the input terminal 12, Vh=0.

[0200] During the time period from T to T3 / 2, the status of each switch tube can be as follows: Figure 15As shown, the switch tubes S2 and S4 are turned on, and the switch tubes S1 and S3 are turned off.

[0201] In this case, the switch tube S4, Cr, the switch tube S2, Lr and Lm form a path, and the equivalent circuit can be as follows Figure 16 As shown, at this time, the capacitor C1 is discharged. Since the two ends of C1 have been charged to 1 / 2Vi1 during the time period from 0 to T / 2, V h It is 1 / 2Vi1, so I will not repeat it here.

[0202] During the time period from 3 / 2T to 2T, the status of each switch tube can be as follows: Figure 13 As shown, the switch tubes S1 and S2 are turned on, and the switch tubes S3 and S4 are turned off.

[0203] In this case, the switch tube S3, the switch tube S4, Cr, Lr and Lm form a path, and the equivalent circuit can be as follows: Figure 14 Since the output terminal of the first H-bridge circuit is directly connected to the input terminal 12, Vh is 0.

[0204] It should be pointed out that the switch tube is used in the above Figure 10 When the driving signal shown drives the switches S1, S2, S3 and S4, the output voltage of the inverter circuit switches between 0 and 1 / 2Vi1 in two cycles of the AC power. Then, the peak-to-peak value of the output voltage of the inverter circuit is Vi1 / 2. Substituting into Formula 5 and Formula 6, it is obtained that the transformation ratio N1 of the LLC resonant conversion unit 401 at this time is 4.

[0205] It should be noted that at this time, the switch tube switches once in the order of ②①③①. In each switching cycle of the switch tube, two cycles of alternating current are output, that is, the switching cycle of the switch tube is twice the resonant cycle of the resonant circuit.

[0206] Second implementation mode: the first transformation ratio N1 is 2.

[0207] Assume that each switch in the LLC resonant conversion unit is turned on at high voltage and turned off at low voltage. The controller 403 provides each switch in the LLC resonant conversion unit 401 with the following voltages: Figure 17 When the driving signal is shown, the first transformation ratio N1 is 2. The controller sends the driving signal in the order of states ④ and ①, thereby controlling the switch tube to switch states.

[0208] During the time period from 0 to T / 2, the status of each switch tube can be as follows: Figure 18 As shown, the switch tubes S1 and S2 are turned on, and the switch tubes S3 and S4 are turned off.

[0209] In this case, the switch tube S1, the switch tube S2, Cr, Lr and Lm form a path, and the equivalent circuit can be as follows Figure 19 As shown, since C1 is not charged and the first H-bridge circuit is connected between the input terminals 11 and 12, Vh=Vi1.

[0210] During the time period from T / 2 to T, the states of the various switches can be as follows: Figure 13 As shown, the switch tubes S3 and S4 are turned on, and the switch tubes S1 and S2 are turned off.

[0211] In this case, the switch tube S3, the switch tube S4, Cr, Lr and Lm form a path, and the equivalent circuit can be as follows: Figure 14 Since the first capacitor is open circuited and the output terminal of the first H-bridge circuit is directly connected to the input terminal 12, Vh=0.

[0212] It should be pointed out that the switch tube is used in the above Figure 17 When the driving signal shown drives the switches S1, S2, S3 and S4, the output voltage of the inverter circuit switches between 0 and Vi1 during the entire cycle of the AC power. The peak-to-peak value of the output voltage of the inverter circuit is Vi1. Substituting into Formula 5 and Formula 6, it is obtained that the transformation ratio of the LLC resonant conversion unit 401 at this time is 2.

[0213] It should be noted that at this time, the switch tube switches once in the order of ④①, and outputs one cycle of alternating current in each switching cycle of the switch tube, that is, the switching cycle of the switch tube is the same as the resonant cycle of the resonant circuit.

[0214] In actual use, other drive signal states in Table 1 can also be used to combine to obtain other adjustable ratios of the LLC resonant conversion unit, which are described in detail herein. It should be noted that when other drive signal states are used to combine, the number of charge and discharge times of the first capacitor C1 in each combination is the same.

[0215] It should be noted that, depending on the type of load, the rectifier circuit can adopt other circuit structures in addition to the structure of the second H-bridge circuit mentioned above. For example, the rectifier circuit adopts a half-bridge rectifier circuit with a center tap to power the load. In this case, the DC conversion circuit can adopt Figure 20 The circuit structure shown.

[0216] In one example, see Figure 21 As shown, in order to reduce device cost and volume, a diode can be used to replace the switch tube in the second H-bridge circuit.

[0217] In one example, see Figure 22As shown, the resonant capacitor in the resonant circuit can be split into two resonant capacitors C2 and C3, which are used to achieve resonance with the resonant inductor Lr. The sum of the capacitances of C1 and C2 is the capacitance of Cr.

[0218] Example 2 of LLC resonant conversion unit:

[0219] The embodiment of the present application provides a DC converter, such as Figure 23 As shown. The inverter circuit in the LLC resonant conversion unit 401 mainly includes a first switch tube S1, a second switch tube S2, and a flying capacitor type multi-level half-bridge inverter circuit consisting of N first conversion switch tubes, N second conversion switch tubes, and N flying capacitors. The resonant circuit mainly includes a resonant inductor Lr and a resonant capacitor Cr. The primary winding of the transformer is connected in series with the resonant inductor Lr and the resonant capacitor Cr, and the secondary winding of the transformer is connected to a rectifier circuit consisting of an H-bridge. The H-bridge circuit mainly includes switches S3, S4, S5, and S6. N is an integer greater than 1.

[0220] The first switching transistors are sequentially connected in series between the input terminal 11 and the first terminal of the switching transistor S1. That is, the second terminal of the i-th first switching transistor Si1 is connected to the first terminal of the i+1-th first switching transistor S(i+1)1, and the first terminal of the i-th first switching transistor Si1 is connected to the second terminal of the i-1-th first switching transistor S(i-1)1, where i ranges from 2 to N. Similarly, the first through N-th second switching transistors are sequentially connected in series between the input terminal 11 and the first terminal of the switching transistor S2. The first terminal of the first first switching transistor S11 is connected to the input terminal 11, and the first terminal of the first second switching transistor S12 is connected to the input terminal 12.

[0221] Among them, the second end of S2 and the second end of S1 are both connected to one end of the resonant capacitor Cr, the other end of Cr is connected to one end of the resonant inductor Lr, the other end of Lr is connected to one end of the primary winding of the transformer, and the other end of the primary winding of the transformer is connected to the input end 12.

[0222] S3 and S4 are connected in series to form the first arm of an H-bridge circuit, and S5 and S6 are connected in series to form the second arm of the H-bridge circuit. That is, the second end of S4 is connected to the first end of S3, the second end of S6 is connected to the first end of S5, the first end of S3 and the first end of S5 are connected to one end of the secondary winding of the transformer, and the second end of S4 is connected to the second end of S6 and the other end of the secondary winding of the transformer. Specifically, the middle node of the first arm and the middle node of the second arm of the H-bridge circuit are connected to output terminal 12 and output terminal 14, respectively. That is, the second end of S3 is connected to output terminal 13, and the second end of S5 is connected to output terminal 14.

[0223] The i-th first conversion switch tube Si1 and the i-th second conversion switch tube Si2 in the inverter circuit form a switch combination, and the inverter circuit may include N switch combinations. In each switch combination, the two switch tubes are complementary and conductive.

[0224] The following combination Figure 23 , the following description is made taking N as 2 as an example. In this case, the flying capacitor mainly includes C1 and C2, first switching transistors S11 and S21, and second switching transistors S12 and S22.

[0225] The switch tube S21 and the output switch tube S22 belong to the same switch combination, S11 and S12 belong to the same switch combination, and S1 and S2 belong to the same output combination.

[0226] Figure 23 When the switches in the LLC resonant conversion circuit shown receive different drive signals, the switches in the LLC resonant conversion unit are in different states and have different transformation ratios. The corresponding relationship between the drive signals and the output voltage of the flying capacitor multi-level half-bridge inverter circuit when receiving different drive signals is shown in Table 2.

[0227] Table 2

[0228]

[0229]

[0230] when Figure 23 When the LLC resonant conversion unit shown in Table 2 drives the switches in the flying capacitor type multi-level half-bridge inverter circuit, the LLC resonant conversion unit has at least three adjustable ratios of 6, 3, and 2.

[0231] It should be noted that when the state of S11&~S12 in Table 2 is 0, it indicates that the switch tube S11 is off and the switch tube S12 is on. Similarly, when the state of S11&~S12 in Table 2 is 1, it indicates that the switch tube S11 is on and the switch tube S12 is off.

[0232] The following combination Figure 23 Table 2 also provides a detailed description of the transformation ratios of the LLC resonant conversion unit 401 at the three voltage conversion gears.

[0233] The first implementation method: the first transformation ratio N1 is 6.

[0234] Assume that each switch in the LLC resonant conversion unit is turned on at high voltage and turned off at low voltage. The controller 403 provides each switch in the LLC resonant conversion unit 401 with the following voltages: Figure 24When the driving signal is shown, the first transformation ratio N1 is 6. The driving signal is switched in the order of states ②④③⑦⑤⑥.

[0235] When the flying capacitor type multi-level half-bridge inverter circuit uses the above Figure 24 When the switch is driven by the driving signal shown, in the three cycles of the alternating current, the output voltage of the inverter circuit switches between 2Vi1 / 3 and Vi1 / 3 in the three cycles of the alternating current output by the inverter circuit, and the peak-to-peak value of the output voltage of the inverter circuit is Vi1 / 3. Substituting into Formula 5 and Formula 6, it is obtained that the transformation ratio N1 of the LLC resonant conversion unit 401 at this time is 6.

[0236] It should be noted that at this time, the switch tube switches once in the order of ②④③⑦⑤⑥. In each switching cycle of the switch tube, three cycles of alternating current are output, that is, the switching cycle of the switch tube is three times the resonant cycle of the resonant circuit.

[0237] Second implementation mode: the first transformation ratio N1 is 3.

[0238] Assuming that all switches in the LLC resonant conversion unit are turned on at high voltage and turned off at low voltage, when the controller 403 switches the states of the switches in the LLC resonant conversion unit 401 in the order of states ④①⑥①⑦①, the LLC resonant conversion unit transformation ratio is 3.

[0239] When the flying capacitor type multi-level half-bridge inverter circuit uses the above-mentioned method to drive the signal drive switch, in the three cycles of the alternating current, the output voltage of the inverter circuit switches between 2Vi1 / 3 and 0 in the three cycles of the alternating current output by the inverter circuit, and the peak-to-peak value of the output voltage of the inverter circuit is 2Vi1 / 3. Substituting into Formula 5 and Formula 6, it is obtained that the transformation ratio N1 of the LLC resonant conversion unit 401 at this time is 3.

[0240] It should be noted that at this time, the switch tube switches once in the order of ④①⑥①⑦①. In each switching cycle of the switch tube, three cycles of alternating current are output, that is, the switching cycle of the switch tube is three times the resonant frequency cycle of the resonant circuit.

[0241] The third implementation method: the first transformation ratio N1 is 2.

[0242] Assuming that all switches in the LLC resonant conversion unit are turned on at high voltage and turned off at low voltage, when the controller 403 switches the states of the switches in the LLC resonant conversion unit 401 in the order of states ⑧①, the transformation ratio of the LLC resonant conversion unit is 2.

[0243] When the flying capacitor type multi-level half-bridge inverter circuit uses the driving signal in the above manner to drive the switch, the output voltage of the inverter circuit switches between 0 and Vi1 during the entire cycle of the AC power. The peak-to-peak value of the output voltage of the inverter circuit is Vi1. Substituting this into Formula 5 and Formula 6, it is obtained that the transformation ratio of the LLC resonant conversion unit 401 at this time is 2.

[0244] It should be noted that at this time, the switch tube switches once in the order of ⑧①, and outputs one cycle of alternating current in each switching cycle of the switch tube, that is, the switching cycle of the switch tube is the same as the resonant frequency cycle of the resonant circuit.

[0245] It should be noted that other states can also be used to combine and obtain multiple other ratios, which are described in detail in this application. Among them, when using other driving signal states to combine, the number of charge and discharge times of flying capacitors C1 and C2 in each combination is the same.

[0246] In actual use, in order to increase the transformation ratio range of the LLC resonant conversion unit, the inverter circuit may include a first flying capacitor type multi-level half-bridge inverter circuit and a second flying capacitor type multi-level half-bridge inverter circuit for increasing the transformation ratio type of the LLC resonant conversion unit.

[0247] See also Figure 25 As shown, in the first flying capacitor type multi-level half-bridge inverter circuit, the first conversion switch tube is sequentially connected in series between the input terminal 11 and the first end of the switch tube S1, the second conversion switch tube is sequentially connected in series between the input terminal 12 and the first end of the switch tube S2, and the second end of S1 and the second end of S2 are both connected to one end of the resonant circuit.

[0248] In the second flying capacitor type multi-level half-bridge inverter circuit, the first conversion switch tube is sequentially connected in series between the input terminal 11 and the first end of the switch tube S7, the second conversion switch tube is sequentially connected in series between the input terminal 12 and the first end of the switch tube S8, and the second end of S1 and the second end of S2 are both connected to the other end of the resonant circuit.

[0249] The process of using the driving signal to change the transformation ratio of the LLC resonant conversion unit 401 is the same as the process of Example 2 of the LLC resonant conversion unit of this application, and will not be repeated here in this application.

[0250] In the embodiment of the present application, there are also multiple possible implementations of the first voltage regulating circuit 402. Generally speaking, when the efficiency of the first voltage regulating circuit 402 is low, the first voltage regulating circuit can focus on finely regulating the output voltage Vo.

[0251] Example 1 of the first voltage regulation circuit:

[0252] The first voltage regulator can be a buck circuit. For example, Figure 9 As shown, the first voltage regulator circuit mainly includes a switch SH, a switch SL, and an inductor L1. The first end of the switch SH can serve as the input terminal 21 of the first voltage regulator circuit and is connected to the input terminal 12 of the LLC resonant conversion circuit 401. The second end of the switch SH is respectively connected to the first end of the switch SL and one end of the second regulating inductor L2. The second end of the switch SL can serve as the output terminal 24, connected to the input terminal 22, and grounded. The other end of the second regulating inductor L2 can serve as the output terminal 23 and be connected to the output terminal 13 of the LLC resonant conversion unit 401.

[0253] When the first voltage regulating circuit is in the continuous mode, for example, the duty cycle DH and the second transformation ratio N2 satisfy the following relationship:

[0254]

[0255] It should be noted that when the first voltage regulating circuit is in the continuous mode, the inductor L1 switches between storing and releasing energy for a long time, that is, the current flowing through the inductor L1 is in a changing state for a long time.

[0256] Example 2 of the first voltage regulating circuit 402:

[0257] The first voltage regulating circuit 402 may also be a Buck-Boost circuit. For example, Figure 26 As shown, the first voltage regulating circuit 402 mainly includes a switch tube Sa, a switch tube Sb, a switch tube Sc, a switch tube Sd, and a regulating inductor L1. The first end of the switch tube Sa can serve as the connection terminal 21 of the first voltage regulating circuit and be connected to the connection terminal 12 of the LLC resonant conversion unit 401. The second end of the switch tube Sa can be connected to the first end of the switch tube Sb and one end of the regulating inductor L1, respectively. The other end of the regulating inductor L1 can be connected to the second end of the switch tube Sc and the first end of the switch tube Sd, respectively. The first end of the switch tube Sc can serve as the output terminal 23 and be connected to the output terminal 13 of the LLC resonant conversion unit 401. The second ends of the switch tubes Sb and Sd can serve as the input terminal 22 and the output terminal 24, respectively, and be grounded.

[0258] Example 4 of the first voltage regulating circuit 402:

[0259] The first voltage regulating circuit 402 may also be a cuk chopper circuit. For example, Figure 27 As shown, the first voltage regulating circuit mainly includes a switch tube Sa, a switch tube Sb, a regulating capacitor C2, a regulating capacitor C3, a regulating inductor L1 and a regulating inductor L2.

[0260] One end of the regulating inductor L1 can serve as the input terminal 21 of the first voltage regulating circuit and is connected to the input terminal 12 of the LLC resonant conversion unit. The other end of the regulating inductor L1 is connected to the first end of the switching transistor Sa and one end of the regulating capacitor C2, respectively. The other end of the regulating capacitor C2 is connected to one end of the regulating inductor L2 and the first end of the switching transistor Sb, respectively. The other end of the regulating inductor L2 is connected to one end of the regulating capacitor C3. The other end of the regulating capacitor C3, the second end of the switching transistor Sa, and the second end of the switching transistor Sb are grounded.

[0261] It should be noted that the first voltage regulating circuit 402 provided in the aforementioned embodiments is a non-isolated converter circuit with a boost or buck function. In actual use, the first voltage regulating circuit 402 may also be an isolated converter circuit with a boost or buck function. The first voltage regulating circuit 402 may be, but is not limited to, an isolated converter such as a flyback converter, a forward converter, a half-bridge converter, a full-bridge converter, a push-pull converter, or a resonant switching converter.

[0262] The above examples illustrate possible implementations of the LLC resonant conversion unit 401 and the first voltage regulating circuit 402 in the DC converter. As previously mentioned, the DC converter 400 provided in the embodiment of the present application is beneficial for improving the efficiency of the DC converter.

[0263] In one achievable manner, if the transformation ratio N1 of a single LLC resonant conversion unit is much smaller than the target transformation ratio Na, see Figure 28 As shown, the resonance conversion unit at this time can be a combination of N resonance conversion circuits, where N≧2.

[0264] Wherein, each of the N LLC resonant conversion circuits has multiple voltage conversion gears.

[0265] Specifically, the input ends of the N LLC resonant conversion circuits are connected in series to form the input end 11 and the input end 12 , and the output ends of the K LLC resonant conversion circuits are connected in parallel to form the output end 13 and the output end 14 .

[0266] It should be noted that the structure of each LLC resonant conversion circuit can be Figure 9 or Figure 23 The circuit structure shown is the same, and its working principle will not be repeated here in this application.

[0267] In specific implementation, if Figure 28When the LLC resonant conversion unit shown is powered by a connected battery, during the charging process, the battery voltage increases, causing the target transformation ratio Na to decrease. At this time, the transformation ratio output by the DC converter is equal to the target transformation ratio Na. The DC converter provided in the embodiment of the present application also includes: multiple third switching tubes S3, multiple fourth switching tubes S4 and multiple fifth switching tubes S5.

[0268] See also Figure 29 Each of the third switching tubes S3 is connected across the first end point of the input end of two adjacent LLC resonant conversion circuits; each of the fourth switching tubes is connected across the second end point of the input end of two adjacent LLC resonant conversion circuits; one end of each of the fifth switching tubes is connected to the second end point of the input end of the first LLC resonant conversion unit in the two adjacent LLC resonant conversion circuits, and the other end of the fifth switching tube is connected to the first end point of the input end of the second LLC resonant conversion unit in the two adjacent LLC resonant conversion circuits.

[0269] In actual use, when the third switches S3 and S4 are turned on and the switch S5 is turned off, the input sides of the K LLC resonant conversion units are connected in parallel, and the output sides are connected in parallel. When the third switches S3 and S4 are turned off and the switch S5 is turned on, the input sides of the K LLC resonant conversion units are connected in series, and the output sides are connected in parallel.

[0270] It should be noted that when the input sides of multiple LLC resonant conversion circuits are connected in parallel and the output sides are connected in parallel, the input voltages of the multiple LLC resonant conversion circuits are the same. In order to achieve the output target output voltage Va, the transformation ratios of the multiple LLC resonant conversion circuits connected in parallel on the input sides are the same.

[0271] In a specific implementation, the switch tubes S3 , S4 and S5 are all connected to the controller 403 , and the adjustment state is achieved through the driving signal sent by 403 .

[0272] As can be seen from the above embodiments, based on the DC converter 400 provided in the embodiments of the present application, the controller 403 can flexibly adjust the switches S3, S4 and S5 according to the target transformation ratio Na of the DC converter, thereby adjusting the transformation ratio of the LLC resonant conversion unit 401.

[0273] In another achievable manner, the DC converter may further include a second voltage regulation unit 404 .

[0274] See also Figure 30 The input end of the second voltage regulating circuit 404 is respectively connected in series with the input end of the first voltage regulating circuit and the input end of the LLC resonant conversion unit to form the first input end and the second input end, and the output end of the second voltage regulating circuit is respectively connected in parallel with the output end of the first voltage regulating circuit and the output end of the LLC resonant conversion circuit to form the first output end and the second output end.

[0275] In a specific implementation, the second voltage regulation circuit may be an LLC resonant conversion circuit or other conversion circuits with high efficiency, which is used to increase the transformation ratio range of the DC converter.

[0276] In the above example, the LLC resonant conversion circuit and the first voltage regulator circuit in the DC converter are connected in series on the input side and in parallel on the output side. Based on the same technical concept, the LLC resonant conversion circuit and the first voltage regulator circuit can also be connected in parallel on the input side and in series on the output side.

[0277] In this case, if Figure 31 As shown, the input terminal 11 of the LLC resonant circuit can serve as the output terminal 11, the output terminal 13 of the LLC resonant conversion unit can serve as the input terminal 13, and the output terminal 14 of the LLC resonant conversion unit can serve as the input terminal 14. Similarly, the output terminal 23 of the first voltage regulating circuit can serve as the input terminal 23, and the output terminal 24 of the first voltage regulating circuit can serve as the input terminal 24.

[0278] That is, the input side (input end 13 and input end 14) of the LLC resonant conversion unit and the input side (input end 23 and input end 24) of the first voltage regulating circuit are connected in parallel, and the output side (output ends 11 and 12) of the LLC resonant conversion unit 401 and the output side (output ends 21 and 22) of the first voltage regulating circuit 402 are connected in series.

[0279] Input terminals 13 and 14 of the LLC resonant conversion unit can receive input voltage Vi, and output terminals 11 and 12 of the LLC resonant conversion unit 401 can output the LLC resonant conversion unit's output voltage Vo1. Input terminals 23 and 24 of the first voltage regulator circuit 402 can receive the DC converter's input voltage Vi, and output terminals 21 and 22 of the first voltage regulator circuit can output the first voltage regulator circuit's output voltage Vo2. The voltage between output terminals 11 and 22 is the DC converter's output voltage Vo, where Vo = Vo1 + Vo2.

[0280] It should be noted that when the DC converter's input side is connected in parallel and its output side is connected in series, the DC converter functions as a boost circuit. In this case, the first transformation ratio N1 can be understood as the ratio between the output voltage Vo1 and the input voltage Vi, i.e., N1 = Vo1 / Vi. The second transformation ratio N2 is similarly expressed as N2 = Vo2 / Vi.

[0281] It should be noted that when the DC converter provided in the embodiment of the present application is used as a boost circuit, the LLC resonant conversion unit and the first voltage regulation circuit can also adopt any of the above examples provided in the embodiment of the present application, and the details will not be repeated.

[0282] In order to further improve the efficiency of the DC converter, in a possible implementation, when the efficiency of the LLC resonant conversion unit is greater than the efficiency of the first voltage regulating circuit, Vo1 of the LLC resonant conversion unit is greater than the second output voltage Vo2. Figure 4 The same is true for the DC converter shown, which will not be described in detail.

[0283] Among them, the structures of the LLC resonant conversion unit and the first voltage regulating circuit can be referred to the aforementioned embodiments, and are not described in detail in this application.

[0284] In one possible implementation, the DC converter may further include a controller, which may be used to control the LLC resonant conversion unit to convert the input voltage of the DC converter into a first output voltage, control the voltage regulating circuit to convert the input voltage of the DC converter into a second output voltage; and adjust the voltage conversion gear of the LLC resonant conversion unit.

[0285] Based on the same technical concept, an embodiment of the present application further provides a conversion system, which may include the aforementioned DC converter and a controller.

[0286] The DC converter includes an LLC resonant conversion unit and a first voltage regulation circuit. The LLC resonant conversion unit has multiple voltage conversion gears. The LLC resonant conversion unit includes a first input terminal, a second input terminal, a first output terminal, and a second output terminal. The first voltage regulation circuit includes a second input terminal, a third input terminal, a third output terminal, and a fourth output terminal. The LLC resonant conversion unit includes an inverter circuit, a resonant circuit, a transformer, and a rectifier circuit.

[0287] Specifically, the second input terminal is connected to the third input terminal, the first output terminal is connected to the third output terminal, and the second output terminal is connected to the fourth output terminal.

[0288] Specifically, the controller is connected to the LLC resonant conversion unit and the first voltage regulating circuit, respectively, and the controller is used to: control the LLC resonant conversion unit to convert the first input voltage received through the first input terminal and the second input terminal into the output voltage of the conversion system, and output the output voltage of the DC converter through the first output terminal and the second output terminal; control the first voltage regulating circuit to convert the second input voltage received through the third input terminal and the fourth input terminal into the output voltage of the conversion system, and output the output voltage of the DC converter through the third output terminal and the fourth output terminal. The total input voltage of the DC converter includes the first input voltage and the second input voltage.

[0289] It should be noted that the specific circuit structure of the DC converter can be found in the aforementioned embodiment, and this application will not provide a detailed introduction here.

[0290] Based on the same concept, an embodiment of the present application further provides an electronic device, which may include a power supply and the aforementioned DC converter.

[0291] The DC converter can be connected to a power supply and convert the voltage output by the power supply into a supply voltage for the load.

[0292] The power source may be, but is not limited to, a battery or a vehicle power source.

[0293] Optionally, the electronic device may be a switching power supply, which is connected to a battery and a load respectively. The switching power supply may receive a battery voltage provided by the battery, convert the battery voltage into an operating voltage of the load, and then output the voltage to the load.

[0294] Optionally, the electronic device may be an onboard charger, which may be connected to an electrical device. The DC converter may receive a voltage provided by an onboard power supply, convert the voltage output by the onboard power supply into a supply voltage for the electrical device, and then output the voltage to the electrical device.

[0295] Obviously, those skilled in the art may make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application is intended to include these modifications and variations.

Claims

1. A DC converter, characterized in that: The LLC resonant conversion unit comprises a first input terminal (11), a second input terminal (12), a first output terminal (13) and a second output terminal (14); the first voltage regulating circuit comprises a third input terminal (21), a fourth input terminal (22), a third output terminal (23) and a fourth output terminal; the second input terminal is connected to the third input terminal, the first output terminal is connected to the third output terminal, and the second output terminal is connected to the fourth output terminal; the LLC resonant conversion unit has a plurality of voltage conversion gears; wherein: the LLC resonant conversion unit comprises: an inverter circuit, a resonant circuit, a transformer and a rectifier circuit; The inverter circuit is used to convert a first input voltage (Vi1) received through the first input terminal and the second input terminal into an AC voltage, transmit the AC voltage to the rectifier circuit through the resonant circuit and the transformer, and the rectifier circuit converts the AC voltage output by the transformer into the output voltage (Vo) of the DC converter, and outputs the output voltage of the DC converter through the first output terminal (13) and the second output terminal (14); The first voltage regulating circuit is used to convert the second input voltage (Vi2) received through the third input terminal (21) and the fourth input terminal (22) into the output voltage (Vo) of the DC converter, and output the output voltage of the DC converter through the third output terminal and the fourth output terminal, and the total input voltage (Vi) of the DC converter includes the first input voltage and the second input voltage; The DC converter further includes: a controller; The controller is configured to control the LLC resonant conversion unit to convert the first input voltage into the output voltage of the DC converter, and control the first voltage regulating circuit to convert the second input voltage into the output voltage of the DC converter; and The voltage conversion gear of the LLC resonant conversion unit is adjusted according to the target transformation ratio of the DC converter; the target transformation ratio is the ratio between the total input voltage and the target output voltage of the DC converter.

2. The DC converter according to claim 1, wherein: When the LLC resonant conversion unit is in any voltage conversion position of the multiple voltage conversion positions, the period of the AC voltage output by the inverter circuit is the same as the resonant period of the resonant circuit, and the output voltage of the LLC resonant conversion unit is greater than zero.

3. The DC converter according to claim 1 or 2, wherein: The voltage conversion efficiency of the LLC resonant conversion unit is greater than the voltage conversion efficiency of the first voltage regulation circuit. The voltage conversion efficiency of the LLC resonant conversion unit is the ratio of the output power of the LLC resonant conversion unit to the input power of the LLC resonant conversion unit. The voltage conversion efficiency of the first voltage regulation circuit is the ratio of the output power of the first voltage regulation circuit to the input power of the first voltage regulation circuit.

4. The DC converter according to claim 1 or 2, wherein: The two input ends of the inverter circuit form the first input end and the second input end respectively, one output end of the inverter circuit is connected to one end of the resonant circuit, and the other output end of the inverter circuit is connected to one end of the primary winding of the transformer; The other end of the resonant circuit is connected to the other end of the primary winding of the transformer; The two ends of the secondary winding of the transformer are respectively connected to the two input ends of the rectifier circuit; The two output ends of the rectifier circuit form the first output end and the second output end respectively; The inverter circuit has a plurality of voltage conversion ratios, and the plurality of voltage conversion ratios correspond one-to-one to a plurality of voltage conversion gears of the LLC resonant conversion unit.

5. The DC converter according to claim 1 or 2, wherein: The inverter circuit includes: an H-bridge circuit and a first capacitor; The first end of the first bridge arm of the H-bridge circuit forms the first input end, the second end of the first bridge arm is connected to one end of the resonant circuit, the first end of the second bridge arm of the H-bridge circuit forms the second input end, the first end of the second bridge arm forms the second input end, and the second end of the second bridge arm is connected to the second end of the first bridge arm, the H-bridge circuit is used to receive a first drive signal and adjust the voltage conversion gear of the LLC resonant conversion unit according to the first drive signal; The first capacitor is connected between the middle node of the first bridge arm and the middle node of the second bridge arm.

6. The DC converter according to claim 1 or 2, wherein: The inverter circuit includes: a flying capacitor type multi-level half-bridge inverter circuit, a first switch tube and a second switch tube; The first input end of the flying capacitor type multi-level half-bridge inverter circuit forms the first input end, the second input end of the flying capacitor type multi-level half-bridge inverter circuit forms the second input end, the first output end of the flying capacitor type multi-level half-bridge inverter circuit is connected to the first end of the first switch tube, the second output end of the flying capacitor type multi-level half-bridge inverter circuit is connected to the first end of the second switch tube, and the flying capacitor type multi-level half-bridge inverter circuit is used to receive a second drive signal and adjust the voltage conversion gear of the LLC resonant conversion unit according to the second drive signal; The second end of the first switch tube is connected to one end of the resonant circuit; The second end of the second switching tube is connected to the second end of the first switching tube.

7. The DC converter according to claim 1 or 2, wherein: The LLC resonant conversion unit includes N LLC resonant conversion circuits; wherein each of the N LLC resonant conversion circuits has a plurality of voltage conversion gears, where N is an integer greater than or equal to 2; The input ends of the N LLC resonant conversion circuits are connected in series to form the first input end and the second input end, and the output ends of the N LLC resonant conversion circuits are connected in parallel to form the first output end and the second output end.

8. The DC converter according to claim 7, wherein: Also includes: a plurality of third switching tubes, a plurality of fourth switching tubes, and a plurality of fifth switching tubes; Each of the third switching tubes is connected across first endpoints of input terminals of two adjacent LLC resonant conversion circuits, where the first endpoint is a terminal of the LLC resonant conversion circuit that receives a high level; Each of the fourth switching tubes is connected across the second endpoints of the input terminals of two adjacent LLC resonant conversion circuits, where the second endpoint is a terminal of the LLC resonant conversion circuit that receives a low level; One end of each of the fifth switching tubes is connected to the second end of the input end of the first LLC resonant conversion unit in the two adjacent LLC resonant conversion circuits, and the other end of the fifth switching tube is connected to the first end of the input end of the second LLC resonant conversion unit in the two adjacent LLC resonant conversion circuits.

9. The DC converter according to claim 1 or 2, wherein: The DC converter further includes: a second voltage regulating circuit; The input end of the second voltage regulating circuit is respectively connected in series with the input end of the first voltage regulating circuit and the input end of the LLC resonant conversion unit to form the first input end and the second input end, and the output end of the second voltage regulating circuit is respectively connected in parallel with the output end of the first voltage regulating circuit and the output end of the LLC resonant conversion circuit to form the first output end and the second output end.

10. The DC converter according to claim 1 or 2, wherein: The first voltage regulation circuit is a Buck circuit.

11. An electronic device, characterized in that: comprising a power supply and a DC converter according to any one of claims 1 to 10; The DC converter is connected to the power supply, and is used to convert the voltage output by the power supply into a supply voltage for a load.

12. A control method for a DC converter, applied to a DC converter, characterized in that: The DC converter includes an LLC resonant conversion unit and a first voltage regulating circuit. The LLC resonant conversion unit has multiple voltage conversion gears. The LLC resonant conversion unit includes a first input terminal, a second input terminal, a first output terminal, and a second output terminal. The first voltage regulating circuit includes a third input terminal, a fourth input terminal, a third output terminal, and a fourth output terminal. The second input terminal is connected to the first and third input terminals, the first output terminal is connected to the third output terminal, and the second output terminal is connected to the fourth output terminal. Calculating a target transformation ratio, where the target transformation ratio is a transformation ratio between an input voltage of the DC converter and a target output voltage of the DC converter; determining a first transformation ratio of the LLC resonant conversion unit from a plurality of voltage conversion gears of the LLC resonant conversion unit according to a target transformation ratio and a minimum transformation ratio of the first voltage regulating circuit; A second transformation ratio of the first voltage regulating circuit is determined according to the first transformation ratio and the target transformation ratio.

13. The method according to claim 12, wherein: determining a first transformation ratio of the LLC resonant conversion unit according to the target transformation ratio and the minimum transformation ratio of the voltage regulating circuit; determining a value range of a voltage conversion gear of the LLC resonant conversion circuit according to the target transformation ratio and a minimum transformation ratio of the first voltage regulation voltage; The largest voltage conversion gear within the value range of the voltage conversion gear of the LLC resonant conversion circuit is determined as the first transformation ratio.

14. The method according to claim 12 or 13, characterized in that The determining the second transformation ratio by using the target transformation ratio and the first transformation ratio includes: calculating a target input voltage of the LLC resonant conversion unit when the LLC resonant conversion circuit is at the first transformation ratio; calculating a first voltage difference between the DC converter input voltage and the target input voltage; A transformation ratio between the first voltage difference and the output voltage of the DC converter is determined as the second transformation ratio.

15. The method according to claim 12 or 13, wherein: The method further includes controlling the LLC resonant conversion unit to be in the first transformation ratio, and controlling the first voltage regulation circuit to be in the second transformation ratio.

16. The method according to claim 15, wherein The LLC resonant conversion unit includes: an inverter circuit, a resonant circuit, a transformer, and a rectifier circuit. The controlling the LLC resonant conversion unit to be in the first transformation ratio includes: Sending a drive signal to the inverter circuit to control the LLC resonant conversion unit to be at the first transformation ratio; After the inverter circuit receives the driving signal, the period of the AC voltage output by the inverter circuit is the same as the resonance period of the resonant circuit.

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