A multi-stage converter suitable for ultra-wide range high voltage input and multi-output

Abstract

The application discloses a multi-stage converter suitable for super-wide-range high-voltage input and multi-channel output, and belongs to the field of DC-DC converters of electric energy conversion devices. The multi-stage converter comprises two function modules connected in cascade. The first function module is composed of a Ladder type switched capacitor converter and a synchronous rectification Buck converter connected in cascade, wherein the Ladder type switched capacitor converter adopts an intermediate capacitor of a switched capacitor topological structure as an output to realize fixed step-down ratio step-down, thereby ensuring uniform current distribution and reducing device voltage stress; the synchronous rectification Buck converter adopts input voltage feedforward variable duty ratio control to convert super-wide-range high-voltage input into a relatively narrow-range intermediate bus voltage. The second function module is composed of a half-bridge LLC resonant converter and a multi-channel non-isolated DC-DC converter, the LLC resonant converter adopts open-loop fixed-frequency control, and the multi-channel secondary sides are respectively configured with non-isolated DC-DC converters to independently carry out closed-loop control on each channel output. The application effectively solves the problems of high device voltage stress, limit duty ratio control and poor multi-channel output cross regulation under the condition of super-wide-range high-voltage input (such as DC 320V-6500V), realizes multi-channel isolated regulated output, and improves system efficiency and reliability.

Description

Technical Field

[0001] This invention relates to a multi-stage converter suitable for ultra-wide range high voltage input and multiple outputs, belonging to the field of DC-DC converters for power conversion devices. Background Technology

[0002] Flexible DC transmission technology is a key technology for achieving long-distance, high-capacity, and high-efficiency power transmission. The Modular Multilevel Converter (MMC), as the mainstream topology of flexible DC transmission systems, consists of multiple independent sub-modules connected in series. To ensure the stable operation of the internal drive, control circuits, and bypass capacitors of each sub-module, each sub-module requires an independent auxiliary power supply with multiple outputs. Typically, the auxiliary power supply draws power directly from the sub-module's bus capacitor. As the voltage levels of flexible DC transmission systems continue to increase, the input voltage of the auxiliary power supply can reach hundreds to thousands of volts. In particular, some engineering applications require the auxiliary power supply to operate stably within an ultra-wide range of DC 320V to 6500V. This not only requires the auxiliary power supply to withstand input voltages as high as 6500V but also to adapt to an ultra-wide input voltage variation range exceeding 20 times. These ultra-wide-range high-voltage input conditions place higher demands on the topology selection, component selection, and control stability of the auxiliary power supply.

[0003] Existing auxiliary power supply solutions are mostly based on classic isolation topologies such as flyback, half-bridge, or push-pull. However, they have significant technical limitations under ultra-wide high-voltage input conditions ranging from DC 320V to 6500V. On the one hand, under input conditions as high as DC 6500V, due to circuit structure limitations, high-voltage devices with large conduction losses must be selected or series topologies requiring additional voltage equalization control must be adopted, making control complex. On the other hand, since the auxiliary power supply needs to have multi-output characteristics, simultaneously obtaining DC 15V and DC 35V low-voltage outputs for control and drive circuits, as well as DC 400V medium-voltage outputs for charging the bypass switch control circuit, the ultra-wide input range requires the converter to achieve an extremely high buck ratio. This forces the switching transistors of traditional topologies to operate in extreme duty cycle states, resulting in poor control reliability.

[0004] Switched-capacitor converters (SFCs) offer significant advantages in reducing device voltage stress and increasing power density due to their high capacitor energy density, ease of integration, and low requirement for magnetic components. Ladder-type SFCs, in particular, can uniformly reduce the device's withstand voltage to the output voltage level without the need for additional voltage equalization control. However, traditional SFCs typically have a fixed turns ratio, limited voltage regulation capability, and difficulty in independently handling ultra-wide input conditions.

[0005] In summary, existing single-conversion topologies struggle to simultaneously handle high voltage, ultra-wide input range, and multiple output requirements. Therefore, a multi-stage converter architecture capable of accommodating ultra-wide DC high-voltage input ranges from 320V to 6500V is developed, decoupling the complex conversion task into two collaborative functional modules. The first functional module efficiently converts the ultra-wide high-voltage input into a narrower-range intermediate bus voltage, significantly reducing the input voltage level of the second functional module and effectively mitigating the risks associated with extreme duty cycle operation. The second functional module achieves electrical isolation and is configured with non-isolated DC-DC conversion units to meet different load requirements, enabling multiple regulated outputs. Summary of the Invention

[0006] To address the requirements of auxiliary power supply on device withstand voltage, control stability, and operating efficiency under ultra-wide range high voltage input conditions, this invention proposes a multi-stage converter suitable for ultra-wide range high voltage input and multiple outputs.

[0007] To solve its technical problem, the present invention adopts the following technical solution:

[0008] A multi-stage converter suitable for ultra-wide range high-voltage input and multiple outputs comprises two cascaded functional modules. The first functional module includes a Ladder-type switched-capacitor converter and a synchronous rectifier Buck converter cascaded with its output. The output of the Ladder-type switched-capacitor converter is located at the intermediate capacitor of the switched-capacitor topology. The second functional module includes a half-bridge LLC resonant converter and multiple non-isolated DC-DC converter units located on the secondary side of the LLC resonant converter. Each non-isolated DC-DC converter unit has an independent closed-loop voltage regulation control circuit to achieve multi-channel isolation and regulated output.

[0009] The first functional module's Ladder-type switched-capacitor converter uses a 50% duty cycle complementary conduction mode to step down the input voltage with a fixed buck ratio of N:1. The buck ratio N can be adjusted based on the input voltage V. in The highest voltage rating is matched to the rated withstand voltage of the selected power devices to accommodate higher voltage input levels. The output of the Ladder-type switched-capacitor converter is located at the middle capacitor of the switched-capacitor topology, allowing the load current to converge from both ends of the structure to the middle to achieve balanced current distribution. The input of the synchronous rectifier Buck converter is cascaded with the output of the middle capacitor of the Ladder-type switched-capacitor converter, employing variable duty cycle control with input voltage feedforward.

[0010] For ultra-wide range high-voltage input scenarios of DC 320V~6500V, the step-down ratio N is 6. The Ladder-type switched capacitor converter includes multiple flying capacitors C1~C 10and switching transistors Q1 to Q 12 The output terminals are the two ends of the flying capacitor C6 located in the middle of the switched capacitor topology; the input terminal of the synchronous rectifier Buck converter is connected to the output terminal of the Ladder-type switched capacitor converter, which includes a pair of switching transistors Q. 13 Q 14 and the filter inductor L connected to it f and filter capacitor C f The negative terminal of the flying capacitor C6 in the middle is set as the reference ground of the synchronous rectifier Buck converter.

[0011] The synchronous rectifier Buck converter adopts a variable duty cycle control method with input voltage feedforward, which detects its input voltage V. Buck_in And make the duty cycle D follow V Buck_in It exhibits inverse proportional dynamic adjustment, and then, through a limiting stage, restricts the duty cycle to a preset range [D]. min D max Within this range, an ultra-wide input voltage range is converted to a narrower output range. Buck_in The output voltage across the intermediate capacitor of the Ladder-type switched capacitor converter is given. The duty cycle adjustment of the synchronous rectifier Buck converter is constrained by the following expression based on the change in its input voltage:

[0012]

[0013] Among them, V Buck_in_min and V Buck_in_max D represents the minimum and maximum values ​​of the input voltage of the synchronous rectified Buck converter, respectively. min and D max These are the minimum and maximum duty cycles of the preset range, respectively, which can be set according to the input voltage of the synchronous rectifier Buck converter and its target output voltage range.

[0014] The beneficial effects of this invention are as follows:

[0015] 1. By utilizing the high-efficiency voltage reduction characteristics of the Ladder-type switched-capacitor converter in the first functional module, subsequent circuits do not need to withstand high voltage, thus reducing the voltage withstand requirements of the components. Unlike traditional Ladder-type switched-capacitor converters, this invention places its output terminal at the middle capacitor of the switched-capacitor topology, improving current distribution characteristics and effectively reducing charge transfer losses.

[0016] 2. In the first functional module, the synchronous rectifier Buck converter adopts input voltage feedforward variable duty cycle control, so that the duty cycle D varies with the input voltage V. Buck_inIt features inverse proportional regulation, which enables efficient conversion of an ultra-wide range input into a narrower range intermediate bus voltage, reducing the design difficulty of the second functional module and providing favorable conditions for independent and stable output of multiple loads.

[0017] 3. In the second functional module, the half-bridge LLC operates near the fixed-frequency resonant point, realizing soft switching (ZVS) across the entire load range. Its multi-secondary non-isolated DC-DC converter performs closed-loop control on each output, solving the cross-regulation problem of traditional multi-winding output schemes. Attached Figure Description

[0018] Figure 1 This invention provides a circuit topology for a multi-stage converter with ultra-wide range high-voltage input and multiple outputs, comprising two functional modules, V in For the input voltage, a ladder-type switched-capacitor converter and a synchronous rectified buck converter are cascaded to form the first functional module. The output of the first functional module is connected to the input of the second functional module; V LLC_in The second functional module consists of a half-bridge LLC resonant converter and a non-isolated converter with multiple secondary-side outputs, serving as the input voltage. o This is the output voltage.

[0019] Figure 2 This is the circuit topology of the first functional module of the present invention, wherein: V in For the input voltage, Q1, Q3, Q5, Q7, Q9, Q 11 Q2, Q4, Q6, Q8, Q 10 Q 12 The two sets of power transistors C1 to C2 of the Ladder-type switched capacitor converter are complementary power transistors with 50% duty cycles. 10 V is the flying capacitor of the Ladder-type switched-capacitor converter; Buck_in Q is the output voltage of the Ladder-type switched-capacitor converter, which is also the input voltage of the synchronous rectified Buck converter; 13 Q 14 L is the power transistor that is complementary to the synchronous rectified Buck converter. f C is the filter inductor for the synchronous rectified Buck converter. f For the filter capacitor of the synchronous rectified Buck converter, V LLC_in This is the output voltage of the synchronous rectified Buck converter, and also the input voltage of the second functional module.

[0020] Figure 3 The circuit topology of the 6:1 Ladder type switched capacitor converter in the first functional module of this invention is such that the output terminal is located at the middle capacitor of the switched capacitor topology, wherein: Vin For the input voltage, Q1, Q3, Q5, Q7, Q9, Q 11 Q2, Q4, Q6, Q8, Q 10 Q 12 These are two sets of power transistors with complementary 50% duty cycles, C1~C 10 For flying capacitor, V Buck_in This is the output voltage of the switched capacitor converter.

[0021] Figure 4 This is a block diagram illustrating the input voltage feedforward duty cycle control principle of the synchronous rectifier Buck converter in the first functional module of this invention, where: H v The high-voltage resistor voltage divider sampling coefficients are represented by R1 to R3, which, together with the multiplier in the operational amplifier feedback loop, form a division unit. V1 is the output of the division unit. R4 to R7, together with the operational amplifier, form a non-inverting summing circuit. ref As the reference signal, V saw It is a triangular carrier signal.

[0022] Figure 5 This is the input voltage feedforward duty cycle control characteristic curve of the synchronous rectified Buck converter of this invention, where: D is the duty cycle of the main switch, and V... Buck_in This is the input voltage of the synchronous rectified Buck converter.

[0023] Figure 6 V is the output voltage of the synchronous rectified Buck converter of this invention. LLC_in With input voltage V Buck_in The relationship curve, where V LLC_in V is the output voltage of the synchronous rectified Buck converter. Buck_in This is the input voltage of the synchronous rectified Buck converter.

[0024] Figure 7 This is the circuit topology of the second functional module of the present invention, wherein: V LLC_i n is the input voltage of the half-bridge LLC resonant converter, C dc For the intermediate bus capacitor, Q r1 Q r2 For a power transistor with complementary 50% duty cycle conduction, L r For resonant inductance, L m For the magnetizing inductance, C r The capacitor is a resonant capacitor, and T is a transformer. The secondary side of the converter T has four electrically isolated output windings, D... r1 ~D r16 For rectifier diodes, C fr1 ~C fr4As the output filter capacitor, each output winding is rectified and filtered before being connected to a non-isolated DC-DC converter to independently adjust the output voltage of each output.

[0025] Figure 8 The voltage transfer ratio M and f in the resonant cavity of the LLC resonant converter in the second functional module of this invention. n The relationship curve, where M is the voltage gain, f n Here, Q is the normalized frequency, and Q is the quality factor. Detailed Implementation

[0026] The invention will now be described in further detail with reference to the accompanying drawings.

[0027] The circuit topology of a multi-stage converter with ultra-wide range high-voltage input and multiple outputs, as described in this invention, is as follows: Figure 1 As shown, this circuit topology includes two functional modules. The first functional module is a cascaded Ladder-type switched-capacitor converter with a synchronous rectifier Buck converter. The second functional module is a half-bridge LLC resonant converter and a non-isolated converter with multiple secondary-side outputs. The input terminal of the Ladder-type switched-capacitor converter in the first functional module is connected to the power supply V. in The output of the first functional module is connected to the input of the subsequent synchronous rectifier Buck converter; the output of the first functional module is connected to the input of the half-bridge LLC resonant converter in the second functional module, and its secondary output is configured with different non-isolated converters to achieve multi-channel isolation and stable output.

[0028] The circuit topology and control of the first functional module are as follows: Figure 2 As shown, the first functional module consists of a Ladder-type switched-capacitor converter and a synchronous rectified Buck converter cascaded at its output. The Ladder-type switched-capacitor converter employs two sets of complementary conduction modes with a duty cycle of 50%. By changing the series and parallel connection states of the flying capacitors under different operating modes, it achieves control over the input voltage V. in The switching capacitor converter operates on a fixed ratio. In this mode, the voltage stress across each power switch and flying capacitor is limited by the output voltage V of the switching capacitor converter. Buck_in No additional voltage equalization control circuitry is required. The synchronous rectified Buck converter detects its input voltage V... Buck_in It also dynamically adjusts the duty cycle to convert the ultra-wide range input into a narrower range intermediate bus voltage.

[0029] The output voltage of the Ladder-type switched-capacitor converter is determined by the topology. This invention is not limited to a specific voltage conversion ratio; different voltage conversion ratios can be achieved by configuring and adjusting the number of switching transistors and flying capacitors, while the voltage stress borne by each switching transistor and flying capacitor remains its output voltage. For ultra-wide-range high-voltage input scenarios of DC 320V~6500V, a 6:1 Ladder-type switched-capacitor converter is selected, and its circuit topology is as follows: Figure 3 As shown, the odd-numbered and even-numbered switches are turned on alternately in two complementary operating modes, and each flying capacitor completes periodic charging and discharging during the switching of operating modes, thereby realizing energy transfer.

[0030] Based on the series and parallel connection relationship of the capacitors in the two operating modes of the 6:1 Ladder type switched capacitor converter, the following relationship can be written:

[0031]

[0032] Among them, V Cn Represents capacitor C n The steady-state voltage on, V in This is the high-voltage DC input voltage, V Buck_in This is the output voltage of the switched capacitor converter, which is also the input voltage of the synchronous rectified Buck converter.

[0033] The energy transfer of a switched-capacitor converter essentially relies on the periodic charging and discharging process of the flying capacitor; however, losses are inevitable during charge transfer. To reduce charge transfer losses and improve current distribution characteristics, the output position of the ladder-type switched-capacitor converter in the first functional module of this invention has been improved. Unlike conventional structures that place the output terminal at the bottom capacitor, this invention places the output terminal at the middle capacitor of the switched-capacitor topology. The specific circuit topology diagram is still as follows. Figure 3 As shown. While maintaining the connection relationship between the switching transistor and the flying capacitor, and keeping the topology buck ratio unchanged, adjusting the output terminal position will not alter the device voltage stress. By placing the output terminal at the intermediate capacitor, the load current converges from both ends of the ladder structure towards the middle, achieving a balanced distribution of current in each branch. This avoids the additional charge transfer losses introduced by the gradual accumulation of charge in conventional energy extraction methods, thus improving energy conversion efficiency.

[0034] In the first functional module, the Ladder-type switched-capacitor converter does not participate in output voltage regulation; its main function is to achieve a fixed buck ratio and reduce device voltage stress. Furthermore, to reduce the design pressure on the second functional module under ultra-wide input conditions and to create favorable conditions for achieving multi-channel isolation and stable output, a synchronous rectifier Buck converter is cascaded at the output of the Ladder-type switched-capacitor converter. The synchronous rectifier Buck converter regulates the output voltage. Simultaneously, the synchronous rectifier Buck converter uses a switching transistor instead of a diode for freewheeling, enabling zero-voltage turn-on of the synchronous rectifier transistor, which helps reduce switching losses.

[0035] The basic circuit topology of synchronous rectifier Buck converter and its voltage feedforward control method are as follows: Figure 4 As shown, it includes the main switch transistor Q. 13 Synchronous rectifier tube Q 14 Filter inductor L f and filter capacitor C f The synchronous rectified Buck converter operates on the same principle as the traditional Buck converter. In continuous conduction mode, its output voltage is related to its input voltage as follows:

[0036] V LLC_in =V Buck_in D (4)

[0037] Since the input voltage of the synchronous rectified Buck converter still has an ultra-wide range characteristic, to avoid the non-isolated converter in the second functional module operating in a limit duty cycle state, this invention adopts a variable duty cycle control method with input voltage feedforward to regulate the output voltage of the synchronous rectified Buck converter. The input voltage V of the synchronous rectified Buck converter is regulated through a high-voltage resistor divider network. Buck_in The sampled signal is fed into a division unit consisting of an operational amplifier and a multiplier connected in series in its feedback loop, causing the output voltage V1 of the division unit to be different from the input voltage V. Buck_in They are inversely proportional. Then, the output voltage V1 is compared with the reference voltage V. ref Simultaneously, a non-inverting summing circuit is connected, thereby superimposing a DC bias component on V1 to generate a duty cycle control signal. This control signal is processed by a limiting circuit to strictly limit the duty cycle of the main switch transistor within a preset range [D]. min D max [Inside.] Therefore, the duty cycle D of the main switch of the synchronous rectifier Buck converter is related to the input voltage V. Buck_in The relationship between them can be represented as:

[0038]

[0039] Among them, V Buck_in_min and VBuck_in_max D represents the minimum and maximum values ​​of the input voltage of the synchronous rectified Buck converter, respectively. min and D max These are the minimum and maximum duty cycles of the preset range, respectively, which can be set according to the input voltage of the synchronous rectifier Buck converter and its target output voltage range.

[0040] When a DC 320V~6500V ultra-wide range high voltage input is stepped down by a 6:1 Ladder-type switched capacitor converter, a DC voltage of 53.3V~1083.3V can be obtained, which serves as the input voltage V of the synchronous rectified Buck converter. Buck_in For a synchronous rectifier Buck converter, its input voltage feedforward duty cycle control regulation characteristic curve can be obtained from formula (5), as follows: Figure 5 As shown, the duty cycle D is related to the input voltage V. Buck_in They are inversely proportional. Specifically, when the input voltage V in At higher values, the input voltage V of the synchronous rectified Buck converter is... Buck_in The input voltage V is also relatively high, so the duty cycle of the main switching transistor is reduced accordingly; when the input voltage V in When the voltage is low, the duty cycle is increased. Ultimately, the output voltage V of the synchronous rectified Buck converter... LLC_in With input voltage V Buck_in Relationship curves as follows Figure 6 As shown, V LLC_in With V Buck_in The voltage increases linearly, thus narrowing the output voltage range to [V]. Buck_in_ min D max V Buck_in_max D min [], which is DC 48V~108.3V, realizes the conversion of ultra-wide range high voltage input to narrower range output, effectively reduces the design pressure of the second functional module, and avoids the independent closed-loop non-isolated converter from operating in extreme duty cycle state.

[0041] In this invention, the output terminal of the first functional module is connected to the input terminal of the second functional module. The second functional module is a half-bridge LLC resonant converter and its secondary side multi-channel non-isolated DC-DC converter, which is used to isolate and transform the intermediate bus voltage after processing by the first functional module and realize multi-channel stable output.

[0042] The circuit topology of the second functional module of the present invention is as follows: Figure 7 As shown, it includes a half-bridge LLC resonant converter and its secondary-side multi-channel non-isolated DC-DC converter. The primary-side switch Q of the half-bridge LLC resonant converter... r1 and Q r2Connected in series between the intermediate DC buses, a 50% duty cycle complementary conduction mode is used to generate a stable high-frequency square wave voltage at the half-bridge output. The half-bridge LLC resonant converter adopts an open-loop fixed-frequency operation mode, and its switching frequency is fixedly set to the series resonant frequency f of the LLC resonant cavity. r Make the resonant inductance L r With resonant capacitor C r It is in a series resonance state. For example... Figure 8 As shown, the resonant frequency f r At this point, the voltage gain of the resonant cavity stabilizes in the region close to 1. The input voltage change is mainly transmitted to the primary side of the transformer in a proportional manner without introducing additional gain modulation, so that the half-bridge LLC resonant converter mainly undertakes the functions of isolation conversion and energy transfer.

[0043] To achieve multi-channel isolation and independent voltage regulation output to meet different load requirements, the multiple secondary outputs of the half-bridge LLC resonant converter are respectively powered to the non-isolated DC-DC converter unit via corresponding rectifier and filter circuits. The non-isolated DC-DC converter can adopt Buck, Boost, Buck-Boost, or other suitable non-isolated topologies according to specific load requirements. The control loops of each non-isolated DC-DC converter are independent, effectively avoiding the cross-regulation problem present in traditional multi-winding isolated power supplies. Previously, the first functional module converted the ultra-wide-range high-voltage input to a lower voltage level and narrower range intermediate voltage, providing good input conditions for the stable operation of each non-isolated DC-DC converter, effectively avoiding extreme duty cycle operation and achieving stable output.

[0044] This invention decouples the conversion task of ultra-wide-range high-voltage input with multiple outputs into two functional modules: "fixed-ratio step-down and voltage range compression" and "isolation conversion and independent multi-channel voltage regulation," which work together. The first functional module effectively reduces the intermediate bus voltage and converts the ultra-wide-range input into a narrower-range output. The second functional module achieves efficient isolation conversion through a half-bridge LLC resonant converter and combines it with independent closed-loop control of multiple non-isolated DC-DC converters to achieve stable multi-channel outputs. This multi-stage converter structure, while adapting to ultra-wide-range high-voltage inputs and achieving multiple outputs, significantly reduces the voltage stress on power devices and control complexity, improving the overall system efficiency and operational reliability.

Claims

1. A multi-stage converter suitable for ultra-wide range high-voltage input and multiple output, comprising two cascaded functional modules, characterized in that, The first functional module includes a Ladder-type switched-capacitor converter and a synchronous rectifier Buck converter cascaded with its output. The input of the Ladder-type switched-capacitor converter is connected to the high-voltage DC input side, and its output is located at the middle capacitor of the switched-capacitor topology. The second functional module includes a half-bridge LLC resonant converter and a multi-channel non-isolated DC-DC converter unit located on the secondary side of the LLC resonant converter. Each of the non-isolated DC-DC converter units has an independent closed-loop voltage regulation control loop to achieve multi-channel isolation and voltage regulation output.

2. A multi-stage converter suitable for ultra-wide range high voltage input and multiple outputs according to claim 1, wherein in the first functional module, the Ladder-type switched capacitor converter adopts a 50% duty cycle complementary conduction mode, and uses a fixed step-down ratio of N:1 to step down the input voltage. Its output terminal is set at the middle capacitor of the switched capacitor topology, so that the load current gathers from both ends of the structure to the middle to achieve balanced current distribution. The input terminal of the synchronous rectifier Buck converter is cascaded with the output terminal of the middle capacitor of the Ladder-type switched capacitor converter, and a variable duty cycle control with input voltage feedforward is adopted. For ultra-wide range high-voltage input scenarios of DC 320V~6500V, the step-down ratio N is 6. The Ladder-type switched capacitor converter includes multiple flying capacitors C1~C 10 and switching transistors Q1 to Q 12 The output terminals are the two ends of the flying capacitor C6 located in the middle of the switched capacitor topology; the input terminal of the synchronous rectifier Buck converter is connected to the output terminal of the Ladder-type switched capacitor converter, which includes a pair of switching transistors Q. 13 Q 14 and the filter inductor L connected to it f and filter capacitor C f The negative terminal of the flying capacitor C6 in the middle is set as the reference ground of the synchronous rectifier Buck converter.

3. A multi-stage converter suitable for ultra-wide range high-voltage input and multiple outputs according to claim 2, characterized in that, The synchronous rectifier Buck converter adopts a variable duty cycle control method with input voltage feedforward, which detects its input voltage V. Buck_in And make the duty cycle D follow V Buck_in It exhibits inverse proportional dynamic adjustment, and then, through a limiting stage, restricts the duty cycle to a preset range [D]. min D max Within this range, an ultra-wide input voltage range is converted to a narrower output range. Buck_in The output voltage across the intermediate capacitor of the Ladder-type switched capacitor converter is given. The duty cycle adjustment of the synchronous rectifier Buck converter is constrained by the following expression based on the change in its input voltage: Among them, V Buck_in_min and V Buck_in_max D represents the minimum and maximum values ​​of the input voltage of the synchronous rectified Buck converter, respectively. min and D max These are the minimum and maximum duty cycles of the preset range, respectively, which can be set according to the input voltage of the synchronous rectifier Buck converter and its target output voltage range.

4. A multi-stage converter suitable for ultra-wide range high-voltage input and multiple outputs according to claim 1, characterized in that, The half-bridge LLC resonant converter in the second functional module adopts an open-loop fixed-frequency operation mode, and the half-bridge inverter unit adopts a 50% duty cycle complementary conduction mode. Its multiple secondary sides are equipped with non-isolated DC-DC conversion units for independent closed-loop control, so as to achieve multi-channel isolation and stable output.

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