Wide input range quasi-single-stage DC / DC converter and voltage control method

Abstract

The present invention specifically relates to a quasi-single-stage DC / DC converter with a wide input range and a voltage control method. The quasi-single-stage DC / DC converter includes: a three-port DC converter, and an auxiliary converter for outputting positive and negative polarity voltages; the three-port DC converter includes an input port, an output port, and an auxiliary port; a DC transformer is provided between the input port and the output port, and between the input port and the auxiliary port, respectively; the input port is connected to an input power supply, the auxiliary port is used to provide a DC voltage to the auxiliary converter, and the output port is used to provide a DC voltage to a resistive load; the voltage input terminal of the auxiliary converter is connected to the auxiliary port of the three-port DC converter, and the voltage output terminal is connected in series in a forward or reverse direction in a loop formed by the input power supply and the input port of the three-port DC converter. The present invention can operate stably within a wide input range and can effectively improve the efficiency of the rated operating point.

Description

Technical Field

[0001] The present invention relates to the technical field of converter topology structures, and in particular to a wide-input-range quasi-single-stage DC / DC converter device and a voltage control method. Background Art

[0002] As data centers continue to expand, high-power density and high-efficiency server power distribution solutions are gaining increasing attention. Power factor correction converters (PFC converters) and downstream DC / DC converters are key components of traditional server high-voltage DC power distribution architectures. PFC converters are used to achieve power factor correction, while downstream DC / DC converters are used to achieve voltage matching.

[0003] The instantaneous input power of a PFC converter fluctuates at twice the power frequency, while the output power remains constant. When the input power exceeds the output power, the output capacitor stores excess energy, causing the voltage across it to rise. When the input power falls below the output power, the output capacitor releases energy, causing the voltage across it to decrease. Consequently, the output voltage of the PFC converter exhibits periodic pulsations at a frequency of twice the power frequency. To prevent significant voltage fluctuations on the PFC converter's output bus, a large-capacity electrolytic capacitor is used for filtering at the PFC output.

[0004] However, the presence of electrolytic capacitors limits the system's service life, reliability, and power density. Furthermore, during the power-off holdup time, the voltage on the PFC converter's output bus drops significantly. To ensure successful data backup in servers, the downstream DC / DC converter must continue to output a stable DC voltage during this period. Therefore, the downstream DC / DC converter must be capable of operating over a wide input voltage range. These converters typically employ either a single-stage or two-stage structure, both of which have limitations. For single-stage configurations, traditional hard-switching PWM (pulse width modulation) converters exhibit high switching losses. Zero-voltage switching PWM converters, such as phase-shifted full-bridge converters and dual-active-bridge converters, cannot achieve zero-current shutdown on the secondary side. LLC resonant converters require a large resonant inductor for operation over a wide input range, which also limits efficiency and power density. For two-stage configurations, all power is converted across two stages, resulting in relatively low efficiency.

[0005] To address the above issues, existing technologies have proposed a quasi-single-stage structure. This adds an auxiliary regulation section to the single-stage structure, allowing most of the power to be transmitted through the main conversion section, while a portion of the power flows through the auxiliary regulation section, thereby achieving efficient and tight regulation of the output voltage over a wide input range. However, the auxiliary converter used in existing quasi-single-stage solutions can only output a unipolar DC voltage or a high-frequency AC square wave. If a unipolar DC voltage is output, a considerable amount of power will still flow through the auxiliary converter even when the converter is operating near the rated operating point, thereby limiting efficiency under rated conditions. If a high-frequency AC square wave is output, the direct superposition of the high-frequency AC square wave on the DC input will cause current distortion, requiring an LC filter at the output, making it unsuitable for applications with a wide input range. Therefore, designing a quasi-single-stage DC / DC converter device that can operate stably over a wide input range and effectively improve efficiency at the rated operating point is a technical problem that urgently needs to be solved. Summary of the Invention

[0006] In view of the deficiencies of the above-mentioned prior art, the technical problem to be solved by the present invention is: how to provide a quasi-single-stage DC / DC converter with a wide input range, which can operate stably within a wide input range and effectively improve the efficiency of the rated operating point, thereby improving the efficiency and stability of DC / DC conversion, and further providing a basis for constructing a high-power density and high-efficiency power distribution solution.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] A wide input range quasi-single-stage DC / DC converter device includes: a three-port DC converter and an auxiliary converter for outputting positive and negative polarity voltages;

[0009] The three-port DC converter includes an input port, an output port, and an auxiliary port; a DC transformer is provided between the input port and the output port, and between the input port and the auxiliary port, respectively; the input port is connected to an input power supply, the auxiliary port is used to provide a DC voltage for the auxiliary converter, and the output port is used to provide a DC voltage for a resistive load;

[0010] The voltage input terminal of the auxiliary converter is connected to the auxiliary port of the three-port DC converter, and the voltage output terminal is connected in series in a positive or negative direction in a loop formed by the input power supply and the input port of the three-port DC converter;

[0011] When the power supply voltage of the input power source is equal to the rated value, the output voltage of the auxiliary converter is 0;

[0012] When the power supply voltage of the input power supply is less than the rated value, the auxiliary converter outputs a positive polarity voltage;

[0013] When the power supply voltage of the input power supply is greater than the rated value, the auxiliary converter outputs a negative polarity voltage;

[0014] When the power supply voltage of the input power supply changes, the output voltage of the auxiliary converter changes along with the power supply voltage of the input power supply, so that the input voltage of the three-port DC converter is constant, and thus the wide input range quasi-single-stage DC / DC conversion device outputs a constant voltage.

[0015] Preferably, there are three ways to connect the voltage input terminal of the auxiliary converter to the input power supply: first, the voltage input terminal of the auxiliary converter is connected in series in a forward or reverse direction between the negative pole of the input power supply and the ground; second, the voltage input terminal of the auxiliary converter is connected in series in a forward or reverse direction between the positive pole of the input power supply and the positive pole of the input port of the three-port DC converter; third, the voltage input terminal of the auxiliary converter is connected in series in a forward or reverse direction between the negative pole of the input port of the three-port DC converter and the ground.

[0016] Preferably, the DC transformers between the input port and the output port and between the input port and the auxiliary port are isolated converters capable of achieving electrical isolation.

[0017] Preferably, the input port and the auxiliary port of the three-port DC converter need to transmit power in both directions, and adopt a full-bridge structure, a symmetrical half-bridge structure, an asymmetrical half-bridge structure or a stacked structure; the output port of the three-port DC converter does not need to transmit power in both directions, and adopts a full-wave rectification, a full-bridge rectification or a voltage doubler rectification circuit.

[0018] Preferably, the auxiliary converter adopts a full-bridge structure; the full-bridge structure includes an H-bridge, a filter inductor and a filter capacitor; the H-bridge includes switch tubes S1, S2, S3 and S4 connected in series in sequence;

[0019] When the auxiliary converter outputs a positive polarity voltage, S2 and S4 are always off, and S1 and S3 operate at a certain duty cycle;

[0020] When the auxiliary converter outputs a negative polarity voltage, S1 and S3 are constantly off, and S2 and S4 operate at a certain duty cycle.

[0021] Preferably, the relationship between the DC voltage gain and the duty cycle when the auxiliary converter outputs a positive polarity voltage is expressed by the following formula:

[0022]

[0023]

[0024]

[0025] Where: M represents the DC voltage gain; D represents the duty cycle of the switches S1 and S3; T s Represents the switching cycle; Vo represents the output voltage of the auxiliary converter; V in represents the input voltage of the auxiliary converter; R represents the equivalent load resistance at the output terminal of the auxiliary converter; L represents the magnitude of the filter inductor of the auxiliary converter; D0 represents the critical duty cycle in continuous conduction mode or discontinuous conduction mode. When D > D0, the auxiliary converter operates in continuous conduction mode. When D < D0, the auxiliary converter operates in discontinuous conduction mode.

[0026] Preferably, when the auxiliary port of the three-port DC converter adopts voltage-doubling rectification, the auxiliary converter adopts a symmetrical half-bridge structure; the symmetrical half-bridge structure includes a symmetrical half-bridge, a filter inductor, and a filter capacitor; the capacitor bridge arm of the symmetrical half-bridge is multiplexed with the capacitor bridge arm of the voltage-doubling rectification at the auxiliary port of the three-port DC converter; the switch bridge arm of the symmetrical half-bridge includes complementary-conducting switch tubes S5 and S6.

[0027] Preferably, the relationship between the DC voltage gain of the auxiliary converter and the duty cycle is expressed by the following formula:

[0028]

[0029] In the formula: M represents the DC voltage gain; D represents the duty cycle; V in represents the output voltage of the voltage-doubling rectification at the auxiliary port of the three-port DC converter, that is, the input voltage of the auxiliary converter;

[0030] When the duty cycle D > 0.5, the auxiliary converter outputs a positive-polarity voltage;

[0031] When the duty cycle D < 0.5, the auxiliary converter outputs a negative-polarity voltage.

[0032] The present invention also discloses a voltage control method for a wide-input-range quasi-single-stage DC / DC conversion device, which is implemented based on the wide-input-range quasi-single-stage DC / DC conversion device of the present invention, and specifically includes:

[0033] S01: Connect the output port of the three-port DC converter in the quasi-single-stage DC / DC conversion device to a resistive load;

[0034] S02: Connect the input port of the three-port DC converter in the quasi-single-stage DC / DC conversion device to an input power supply; ​​​​S04: controlling the output voltage of the auxiliary converter voltage output terminal according to the power supply voltage of the input power supply, thereby achieving control of the output voltage of the wide input range quasi-single-stage DC / DC converter device.

[0037] Preferably, when the power supply voltage of the input power supply is equal to the rated value, the output voltage of the auxiliary converter is controlled to be 0;

[0038] When the power supply voltage of the input power supply is less than the rated value, the auxiliary converter is controlled to output a positive polarity voltage;

[0039] When the power supply voltage of the input power supply is greater than the rated value, the auxiliary converter is controlled to output a negative polarity voltage;

[0040] When the power supply voltage of the input power supply changes, the output voltage of the auxiliary converter is controlled to change along with the power supply voltage of the input power supply, so that the input voltage of the three-port DC converter is constant, and thus the wide input range quasi-single-stage DC / DC conversion device outputs a constant voltage.

[0041] Compared with the prior art, the wide input range quasi-single-stage DC / DC converter device of the present invention has the following beneficial effects:

[0042] In the wide input range quasi-single-stage DC / DC converter device of the present invention, a DC transformer is provided between the input port and the output port of the three-port DC converter and between the input port and the auxiliary port. The voltage input terminal of the auxiliary converter is connected to the auxiliary port of the three-port DC converter, and the voltage output terminal is used to adjust the input voltage of the input port of the three-port DC converter by outputting the voltage. On the one hand, when the power supply voltage of the input power supply is equal to the rated value, the output voltage of the auxiliary converter is zero, so that all power is transmitted through the DC transformer between the input port and the output port of the three-port DC converter, which can effectively improve the efficiency of the rated operating point. On the other hand, when the power supply voltage of the input power supply is less than the rated value, the auxiliary converter outputs a positive polarity voltage. When the power supply voltage is greater than the rated value, the auxiliary converter outputs a negative polarity voltage. When the power supply voltage changes, the output voltage of the auxiliary converter changes (increases or decreases) along with the power supply voltage of the input power supply. That is, the input voltage of the three-port DC converter can be kept constant by adjusting the magnitude of the output voltage of the auxiliary converter, thereby enabling the wide input range quasi-single-stage DC / DC converter device to output a constant voltage. That is, the output voltage can be tightly regulated within a wide input range, thereby enabling the quasi-single-stage DC / DC converter to operate stably within a wide input range, thereby improving the efficiency and stability of DC / DC conversion, and providing a basis for building a high power density and high efficiency power distribution solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to make the purpose, technical solutions and advantages of the invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings, in which:

[0044] Figure 1 This is the topological structure diagram of the wide input range quasi-single-stage DC / DC converter;

[0045] Figure 2 It is the topological structure diagram of the three-port DC converter;

[0046] Figure 3 It is an auxiliary converter with full-bridge structure;

[0047] Figure 4 The curve showing the relationship between DC gain and duty cycle when the full-bridge auxiliary converter outputs a positive voltage.

[0048] Figure 5 It is an auxiliary converter with a half-bridge structure;

[0049] Figure 6 This is the topological structure diagram of the quasi-single-stage DC / DC converter in the experiment;

[0050] Figure 7 (a) to (c) are simulation waveforms under steady state;

[0051] Figure 8 (a) to (b) are simulation waveforms under input voltage jump conditions;

[0052] Figure 9 (a) to (b) are simulation waveforms under load jump conditions;

[0053] Figure 10 (a) to (b) are simulation waveforms when the input voltage contains a ripple component twice the power frequency. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but only represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0055] It should be noted that similar reference numerals and letters denote similar items in the following figures. Therefore, once an item is defined in one figure, it does not require further definition or explanation in subsequent figures. In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the figures, or the orientations or positional relationships in which the inventive product is typically placed when in use. These terms are intended solely to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation, and are therefore not to be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third," etc., are used solely to distinguish descriptions and are not to be construed as indicating or implying relative importance. Furthermore, terms such as "horizontal" and "vertical" do not imply that a component must be absolutely horizontal or overhanging, but rather may be slightly tilted. For example, "horizontal" simply refers to a direction that is more horizontal than "vertical," and does not imply that the structure must be completely horizontal, but rather may be slightly tilted. In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections or electrical connections; they may refer to direct connections or indirect connections through an intermediate medium; and they may refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0056] The following is a further detailed description through specific implementation methods:

[0057] Example 1:

[0058] This embodiment discloses a quasi-single-stage DC / DC converter with a wide input range.

[0059] like Figure 1 As shown, a wide input range quasi-single-stage DC / DC converter device includes: a three-port DC converter, and an auxiliary converter for outputting positive and negative polarity voltages;

[0060] The three-port DC converter includes an input port, an output port, and an auxiliary port. A DC transformer (DCX) is provided between the input port and the output port, and between the input port and the auxiliary port. The input port is connected to the input power supply, and the auxiliary port is used to provide a DC voltage V for the auxiliary converter. aux_in , the output port is used to provide a stable DC voltage to the resistive load;

[0061] The voltage input terminal of the auxiliary converter is connected to the auxiliary port of the three-port DC converter, and the voltage output terminal is connected in series in a positive or negative direction in a loop formed by the input power supply and the input port of the three-port DC converter, so as to adjust the input voltage of the input port of the three-port DC converter by using the output voltage;

[0062] According to KVL, V in +V aux_o =V DCX_in ;

[0063] When the input power supply voltage V in Equal to the rated value V inN When the auxiliary converter output voltage V aux_o is 0;

[0064] When the input power supply voltage V in Less than the rated value V inN When , the auxiliary converter outputs positive polarity voltage;

[0065] When the input power supply voltage V in Greater than the rated value V inN When , the auxiliary converter outputs a negative polarity voltage;

[0066] When the input power supply voltage V in When the output voltage of the auxiliary converter V aux_o The power supply voltage V in changes so that the input voltage V DCX_in Constant, thereby making the wide input range quasi-single-stage DC / DC converter output a constant voltage.

[0067] In the wide input range quasi-single-stage DC / DC converter device of the present invention, a DC transformer is provided between the input port and the output port of the three-port DC converter and between the input port and the auxiliary port. The voltage input terminal of the auxiliary converter is connected to the auxiliary port of the three-port DC converter, and the voltage output terminal is used to adjust the input voltage of the input port of the three-port DC converter by outputting the voltage. On the one hand, when the power supply voltage of the input power supply is equal to the rated value, the output voltage of the auxiliary converter is zero, so that all power is transmitted through the DC transformer between the input port and the output port of the three-port DC converter, which can effectively improve the efficiency of the rated operating point. On the other hand, when the power supply voltage of the input power supply is less than the rated value, the auxiliary converter outputs a positive polarity voltage. When the power supply voltage is greater than the rated value, the auxiliary converter outputs a negative polarity voltage. When the power supply voltage changes, the output voltage of the auxiliary converter changes (increases or decreases) along with the power supply voltage of the input power supply. That is, the input voltage of the three-port DC converter can be kept constant by adjusting the magnitude of the output voltage of the auxiliary converter, thereby enabling the wide input range quasi-single-stage DC / DC converter device to output a constant voltage. That is, the output voltage can be tightly regulated within a wide input range, thereby enabling the quasi-single-stage DC / DC converter to operate stably within a wide input range, thereby improving the efficiency and stability of DC / DC conversion, and providing a basis for building a high power density and high efficiency power distribution solution.

[0068] In the specific implementation process, there are three ways to connect the voltage input terminal of the auxiliary converter to the input power supply:

[0069] First, the voltage input terminal of the auxiliary converter is connected in series between the negative terminal of the input power supply and the ground in a forward or reverse direction;

[0070] Second, the voltage input terminal of the auxiliary converter is connected in series in a forward or reverse direction between the positive electrode of the input power source and the positive electrode of the input port of the three-port DC converter;

[0071] Third, the voltage input terminal of the auxiliary converter is connected in series in a forward or reverse direction between the negative pole of the input port of the three-port DC converter and the ground.

[0072] All three methods meet V in ±V aux_o =V DCX_in .

[0073] The present invention realizes the series connection of the voltage input terminal of the auxiliary converter with the input power supply and the input port of the three-port DC converter to form a loop through three connection modes, so that the input voltage of the three-port DC converter can be kept constant by adjusting the magnitude of the auxiliary converter output voltage, thereby achieving tight regulation of the output voltage within a wide input range, that is, stable operation within the wide input range, thereby further improving the efficiency and stability of DC / DC conversion.

[0074] In the specific implementation process, Figure 2 As shown in the figure, the DC transformers between the input and output ports, and between the input and auxiliary ports, use isolated converters capable of achieving electrical isolation, such as dual active bridge (DAB) DC converters and resonant DC converters such as LC, LLC, and CLLC. To simplify control, they operate in open-loop mode as DC transformers.

[0075] The input port and auxiliary port of the three-port DC converter need to transmit power in both directions, and adopt a full-bridge structure, a symmetrical half-bridge structure, an asymmetrical half-bridge structure or a stacked structure; the output port of the three-port DC converter does not need to transmit power in both directions, and adopts a full-wave rectification, a full-bridge rectification or a voltage doubler rectification circuit.

[0076] The present invention uses an isolated converter capable of achieving electrical isolation as a DC transformer between the input port and the output port, and between the input port and the auxiliary port, so that no current loop is directly formed between the ports, resulting in minimal mutual interference. This improves the safety and reliability of the three-port DC converter and enables high voltage gain. Furthermore, when the power supply voltage of the input power source is equal to the rated value, all power is transmitted through the DC transformer between the input port and the output port of the three-port DC converter, effectively improving the efficiency at the rated operating point and thereby further improving the efficiency and stability of DC / DC conversion.

[0077] In the specific implementation process, the auxiliary converter adopts Figure 3 The full-bridge structure shown in the figure includes an H-bridge, a filter inductor L, and a filter capacitor C. auxo The H-bridge includes switches S1, S2, S3, and S4 connected in series.

[0078] When the auxiliary converter outputs a positive polarity voltage, S2 and S4 are always off, and S1 and S3 operate at a certain duty cycle;

[0079] When the auxiliary converter outputs a negative polarity voltage, S1 and S3 are constantly off, and S2 and S4 operate at a certain duty cycle.

[0080] The relationship curve between DC voltage gain and duty cycle when the auxiliary converter outputs positive polarity voltage is as follows: Figure 4 As shown in the figure, the horizontal axis is the duty cycle and the vertical axis is the voltage gain.

[0081] The relationship between the DC voltage gain and the duty cycle when the auxiliary converter outputs a positive voltage is expressed by the following formula:

[0082]

[0083]

[0084]

[0085] Where: M represents the DC voltage gain; D represents the duty cycle of switch tubes S1 and S3 (or S2 and S4); T s represents the switching period; V o represents the output voltage of the auxiliary converter; V in represents the input voltage of the auxiliary converter; R represents the equivalent load resistance at the output terminal of the auxiliary converter; L represents the magnitude of the filter inductor of the auxiliary converter; D0 represents the critical duty cycle of continuous conduction mode (CCM) or discontinuous conduction mode (DCM). When D > D0, the auxiliary converter operates in continuous conduction mode. When D < D0, the auxiliary converter operates in discontinuous conduction mode.

[0086] When outputting a negative-polarity voltage, the relationship between the DC voltage gain M and the duty cycle D is similar to that when outputting a positive-polarity voltage.

[0087] By adopting an auxiliary converter with a full-bridge structure in the present invention, it is possible to keep the input voltage of the three-port DC converter constant by adjusting the magnitude of the output voltage of the auxiliary converter, and further, it is possible to achieve precise regulation of the output voltage within a wide input range, that is, to operate stably within a wide input range, thereby further improving the efficiency and stability of DC / DC conversion.

[0088] During the specific implementation process, when a voltage doubler rectification is adopted for the auxiliary port of the three-port DC converter, the auxiliary converter adopts a symmetric half-bridge structure as shown in Figure 5 ; the symmetric half-bridge structure includes a symmetric half-bridge, a filter inductor L, and a filter capacitor C auxo ; the capacitor bridge arm of the symmetric half-bridge is reused with the capacitor bridge arm of the voltage doubler rectification of the auxiliary port of the three-port DC converter (otherwise, the voltages of the two capacitors on the capacitor bridge arm of the symmetric half-bridge are unbalanced, and the auxiliary converter cannot work properly); the switch bridge arm of the symmetric half-bridge includes complementary-conducting switch tubes S5 and S6.

[0089] The relationship between the DC voltage gain of the auxiliary converter and the duty cycle is represented by the following formula:

[0090]

[0091] Where: M represents the DC voltage gain; D represents the duty cycle; V in represents the output voltage of the voltage doubler rectification of the auxiliary port of the three-port DC converter, that is, the input voltage of the auxiliary converter;

[0092] When the duty cycle D>0.5, the auxiliary converter outputs a positive polarity voltage;

[0093] When the duty cycle D<0.5, the auxiliary converter outputs a negative polarity voltage.

[0094] When the auxiliary port of the three-port DC converter adopts voltage doubling rectification, the present invention adopts an auxiliary converter with a symmetrical half-bridge structure, so that the input voltage of the three-port DC converter can be kept constant by adjusting the magnitude of the auxiliary converter output voltage. This can achieve tight regulation of the output voltage within a wide input range, that is, it can operate stably within the wide input range, thereby further improving the efficiency and stability of DC / DC conversion.

[0095] In order to better illustrate the advantages of the technical solution of the present invention, the following experiments are also disclosed in this embodiment.

[0096] This experiment uses the simulation software Matlab / Simulink to do relevant simulations. The topology used in the simulation is as follows: Figure 6 The specific simulation results are as follows:

[0097] like Figure 7 The waveforms shown are simulated at a rated input voltage of 380V. It can be seen that due to the influence of component parasitic parameters and other factors, the input voltage of the three-port DC converter deviates from the ideal value of 380V when it outputs 48V. However, the quasi-single-stage DC / DC converter proposed in this invention can automatically adjust the input of the three-port DC converter, stabilizing the output of the three-port DC converter at 48V. Furthermore, by appropriately adjusting the turns ratio of the transformer between the input and output ports of the three-port DC converter, the output voltage of the auxiliary converter can be controlled near 0V at the rated input voltage, thereby improving efficiency at the rated operating point. Figure 7 (c) is a waveform diagram of the resonant current and excitation current of the LLC resonant converter between the input port and the output port of the three-port DC converter. It can be seen that the LLC resonant converter operates at the resonant frequency point.

[0098] like Figure 8 Shown is the input voltage V in Simulation waveform under jump condition, input voltage V in At 0.005s, it jumps from 400V to 420V, and at 0.01s, it jumps from 420V to 340V. Figure 8 (a) It can be seen that when the input voltage jumps, the output voltage of the auxiliary converter changes accordingly, maintaining the input voltage V DCX_in Constant. Figure 8 (b) It can be seen that the output voltage V o The voltage remains constant at 48V over a wide input voltage range.

[0099] like Figure 9 The following is the simulation waveform under load jump condition. The load current jumps from 9.6A to 19.2A at 0.005s. It can be seen that the output voltage V o It can always maintain 48V over a wide load range.

[0100] like Figure 10 The figure shows the simulation when the input voltage contains twice the power frequency ripple. The input voltage V in It contains a 380V DC component and a 100V peak-to-peak ripple component twice the power frequency. Figure 10 (a) It can be seen that the output voltage V aux_o It also includes DC component and twice the power frequency component. Among them, the twice power frequency component is used to offset the input voltage V in The twice power frequency component in the three-port DC converter makes the input voltage V DCX_in Maintain a stable DC; the DC component is used to adjust the input voltage V of the three-port DC converter DCX_in The average value enables the three-port DC converter to stably output a 48V DC voltage. Figure 10 (b) As can be seen, the output voltage of the three-port DC / DC converter is stable at 48V, consistent with theoretical analysis. This simulation demonstrates that the proposed quasi-single-stage DC / DC converter topology allows for a significant double-power frequency ripple on the front-stage DC bus, eliminating the need for large-capacity electrolytic capacitors for filtering. This improves the system's power density, service life, and reliability.

[0101] Example 2:

[0102] This embodiment discloses a voltage control method for the wide input range quasi-single-stage DC / DC converter in the first embodiment.

[0103] A voltage control method for a quasi-single-stage DC / DC converter with a wide input range specifically includes:

[0104] S01: connecting the output port of the three-port DC converter in the quasi-single-stage DC / DC converter to a resistive load;

[0105] S02: connecting the input port of the three-port DC converter in the quasi-single-stage DC / DC converter to an input power supply;

[0106] S03: connecting the auxiliary port of the three-port DC converter in the quasi-single-stage DC / DC converter device to the auxiliary converter, and connecting the voltage output terminal of the auxiliary converter in a forward or reverse series manner in a loop formed by the input power supply and the input port of the three-port DC converter;

[0107] S04: controlling the output voltage of the auxiliary converter voltage output terminal according to the power supply voltage of the input power supply, thereby achieving control of the output voltage of the wide input range quasi-single-stage DC / DC converter device.

[0108] When the power supply voltage of the input power supply is equal to the rated value, the output voltage of the auxiliary converter is controlled to be 0;

[0109] When the power supply voltage of the input power supply is less than the rated value, the auxiliary converter is controlled to output a positive polarity voltage;

[0110] When the power supply voltage of the input power supply is greater than the rated value, the auxiliary converter is controlled to output a negative polarity voltage;

[0111] When the power supply voltage of the input power supply changes, the output voltage of the auxiliary converter is controlled to change along with the power supply voltage of the input power supply, so that the input voltage of the three-port DC converter is constant, and thus the wide input range quasi-single-stage DC / DC conversion device outputs a constant voltage.

[0112] According to the present invention, when the power supply voltage of the input power supply is equal to the rated value, the output voltage of the auxiliary converter is zero, so that all power is transmitted through the DC transformer between the input port and the output port of the three-port DC converter, which can effectively improve the efficiency at the rated operating point. When the power supply voltage of the input power supply is less than the rated value, the auxiliary converter outputs a positive polarity voltage. When the power supply voltage is greater than the rated value, the auxiliary converter outputs a negative polarity voltage. When the power supply voltage changes, the output voltage of the auxiliary converter changes (increases or decreases) along with the change in the power supply voltage of the input power supply. That is, the input voltage of the three-port DC converter can be kept constant by adjusting the magnitude of the output voltage of the auxiliary converter, thereby enabling the wide input range quasi-single-stage DC / DC converter device to output a constant voltage. That is, the output voltage can be tightly regulated within the wide input range, thereby enabling the quasi-single-stage DC / DC converter device to operate stably within the wide input range, thereby improving the efficiency and stability of DC / DC conversion.

[0113] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the technical solutions. Those skilled in the art should understand that modifications or equivalent replacements of the technical solutions of the present invention that do not depart from the purpose and scope of the technical solutions of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A wide input range quasi-single-stage DC / DC converter, characterized in that: include: A three-port DC converter and an auxiliary converter for outputting positive and negative polarity voltages; The three-port DC converter includes an input port, an output port and an auxiliary port; A DC transformer is provided between the input port and the output port and between the input port and the auxiliary port; the input port is connected to the input power supply, the auxiliary port is used to provide a DC voltage for the auxiliary converter, and the output port is used to provide a DC voltage for the resistive load; The voltage input terminal of the auxiliary converter is connected to the auxiliary port of the three-port DC converter, and the voltage output terminal is connected in series in a positive or negative direction in a loop formed by the input power supply and the input port of the three-port DC converter; When the power supply voltage of the input power source is equal to the rated value, the output voltage of the auxiliary converter is 0; When the power supply voltage of the input power supply is less than the rated value, the auxiliary converter outputs a positive polarity voltage; When the power supply voltage of the input power supply is greater than the rated value, the auxiliary converter outputs a negative polarity voltage; When the power supply voltage of the input power supply changes, the output voltage of the auxiliary converter changes along with the power supply voltage of the input power supply, so that the input voltage of the three-port DC converter is constant, and thus the wide input range quasi-single-stage DC / DC conversion device outputs a constant voltage.

2. The wide input range quasi-single-stage DC / DC converter according to claim 1, wherein: There are three ways to connect the voltage output end of the auxiliary converter to the input power supply: first, the voltage output end of the auxiliary converter is connected in series in a forward or reverse direction between the negative pole of the input power supply and the ground; second, the voltage output end of the auxiliary converter is connected in series in a forward or reverse direction between the positive pole of the input power supply and the positive pole of the input port of the three-port DC converter; third, the voltage output end of the auxiliary converter is connected in series in a forward or reverse direction between the negative pole of the input port of the three-port DC converter and the ground.

3. The wide input range quasi-single-stage DC / DC converter according to claim 1, wherein: The DC transformers between the input port and the output port and between the input port and the auxiliary port use isolated converters that can achieve electrical isolation.

4. The wide input range quasi-single-stage DC / DC converter according to claim 1, wherein: The input port and auxiliary port of the three-port DC converter need to transmit power in both directions, and adopt a full-bridge structure, a symmetrical half-bridge structure, an asymmetrical half-bridge structure or a stacked structure; the output port of the three-port DC converter does not need to transmit power in both directions, and adopts a full-wave rectification, a full-bridge rectification or a voltage doubler rectification circuit.

5. The wide input range quasi-single-stage DC / DC converter according to claim 1, wherein: The auxiliary converter adopts a full-bridge structure; the full-bridge structure includes an H-bridge, a filter inductor, and a filter capacitor. Switches S8 and S10 are connected in series to form a first bridge arm, switches S7 and S9 are connected in series to form a second bridge arm, and the first bridge arm and the second bridge arm are connected in parallel to form an H-bridge. When the auxiliary converter outputs a positive polarity voltage, S7 and S10 are constantly off, and S8 and S9 operate at a certain duty cycle; When the auxiliary converter outputs a negative polarity voltage, S8 and S9 are constantly turned off, and S7 and S10 operate at a certain duty cycle.

6. The wide input range quasi-single-stage DC / DC converter according to claim 5, characterized in that: The relationship between the DC voltage gain and the duty cycle when the auxiliary converter outputs a positive voltage is expressed by the following formula: Where: M represents the DC voltage gain; D represents the duty cycle of switching transistors S8 and S10; T s represents the switching period; V o represents the output voltage of the auxiliary converter; V in represents the input voltage of the auxiliary converter; R represents the equivalent load resistance at the output of the auxiliary converter; L represents the value of the filter inductor of the auxiliary converter; D0 represents the critical duty cycle in continuous conduction mode or discontinuous conduction mode. When D > D0, the auxiliary converter operates in continuous conduction mode. When D < D0, the auxiliary converter operates in discontinuous conduction mode.

7. The wide input range quasi-single-stage DC / DC converter according to claim 4, wherein: The auxiliary converter adopts a symmetrical half-bridge structure; the symmetrical half-bridge structure includes a symmetrical half-bridge, a filter inductor and a filter capacitor; the capacitor bridge arm of the symmetrical half-bridge is reused with the capacitor bridge arm of the auxiliary port voltage doubler rectification of the three-port DC converter; the switch bridge arm of the symmetrical half-bridge includes complementary conductive switch tubes S5 and S6.

8. The wide input range quasi-single-stage DC / DC converter according to claim 7, wherein: The relationship between the auxiliary converter DC voltage gain and the duty cycle is expressed by the following formula: Where: M represents the DC voltage gain; D represents the duty cycle; V in It represents the output voltage of the auxiliary port of the three-port DC converter after voltage doubling and rectification, that is, the input voltage of the auxiliary converter; When the duty cycle D>0.5, the auxiliary converter outputs a positive polarity voltage; When the duty cycle D<0.5, the auxiliary converter outputs a negative polarity voltage.

9. A voltage control method for a quasi-single-stage DC / DC converter with a wide input range, characterized in that: The wide input range quasi-single-stage DC / DC converter device according to claim 1 is implemented as follows: S01: connecting the output port of the three-port DC converter in the quasi-single-stage DC / DC converter to a resistive load; S02: connecting the input port of the three-port DC converter in the quasi-single-stage DC / DC converter to an input power supply; S03: connecting the auxiliary port of the three-port DC converter in the quasi-single-stage DC / DC converter device to the auxiliary converter, and connecting the voltage output terminal of the auxiliary converter in a forward or reverse series manner in a loop formed by the input power supply and the input port of the three-port DC converter; S04: controlling the output voltage of the auxiliary converter voltage output terminal according to the power supply voltage of the input power supply, thereby achieving control of the output voltage of the wide input range quasi-single-stage DC / DC converter device.

10. The voltage control method for a quasi-single-stage DC / DC converter with a wide input range according to claim 9, wherein: In step S04: When the power supply voltage of the input power supply is equal to the rated value, the output voltage of the auxiliary converter is controlled to be 0; When the power supply voltage of the input power supply is less than the rated value, the auxiliary converter is controlled to output a positive polarity voltage; When the power supply voltage of the input power supply is greater than the rated value, the auxiliary converter is controlled to output a negative polarity voltage; When the power supply voltage of the input power supply changes, the output voltage of the auxiliary converter is controlled to change along with the power supply voltage of the input power supply, so that the input voltage of the three-port DC converter is constant, and thus the wide input range quasi-single-stage DC / DC conversion device outputs a constant voltage.

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