Direct-current converter, high-voltage constant-current remote power supply and control method thereof

Abstract

The invention belongs to the technical field of power electronics, and provides a direct-current converter, a high-voltage constant-current remote power supply and a control method thereof, the direct-current converter is formed by cascading n identical power conversion modules, and n is larger than or equal to 2 and smaller than or equal to 7; each power conversion module is composed of three direct-current conversion units of the same structure and a V / I detection circuit. The input ends of the three DC conversion units are connected in parallel, and the output ends are connected in series to form a cascade structure; each direct-current conversion unit is formed by sequentially connecting a voltage pre-stabilizing circuit, a high-frequency resonance circuit, a high-frequency transformer and a rectifying circuit. Wherein the voltage pre-stabilizing circuit adopts a Buck-Boost circuit. According to the direct-current converter disclosed by the invention, through a hardware architecture that three power conversion modules are cascaded into one module and n modules are cascaded into one system and through two-stage adaptive interleaving control adjustment, high-efficiency and high-precision output is realized, and input and output ripples are reduced at the same time.

Description

Technical Field

[0001] This disclosure belongs to the field of power electronics technology, and in particular relates to a DC converter, a high-voltage constant current remote power supply and its control method. Background Technology

[0002] Submarine cable communication systems are the core infrastructure of modern global communication networks, handling more than 95% of international data transmission. Onshore high-voltage constant current remote power supply is an important guarantee for the power supply of submarine cable communication systems.

[0003] In a high-voltage constant current remote power supply, the DC converter is responsible for converting a low-voltage constant voltage input into a high-voltage constant current output. As the DC converter has a large input current and a high output voltage, the reliability and stability requirements of the converter are very high.

[0004] Currently, the most commonly used solutions are single-stage boost converters based on bridge resonant transformers or two-stage boost converters based on BOOST-stabilized medium voltage. The former has a high transformer turns ratio, large size, complex loop control requiring simultaneous response to input and output changes, and suffers from low conversion efficiency due to difficulties in soft switching at low power output. The latter has a large overall size, limited bandwidth for independent control of the two stages, and slower dynamic response, introducing the risk of ripple superposition. Summary of the Invention

[0005] To address the aforementioned issues of single-stage boost converters based on bridge resonant converters or two-stage boost converters based on BOOST-stabilized intermediate voltage, a DC-DC converter is provided. This converter utilizes a hardware architecture where three DC-DC conversion units are cascaded into a power conversion module, and n power conversion modules are cascaded into a system. It also employs a two-stage adaptive interleaved control adjustment to achieve high-efficiency, high-precision output while significantly reducing input and output ripple.

[0006] This disclosure provides the following various implementable technical solutions: In one aspect, this disclosure provides a DC-DC converter composed of n identical power conversion modules cascaded together, where n is a natural number, 2≤n≤7; A single power conversion module consists of three DC-DC converters with identical structures and one V / I detection circuit; the input terminals of the three DC-DC converters are connected in parallel and the output terminals are connected in series to form a cascaded structure. A single DC-DC converter unit consists of a pre-regulator circuit, a high-frequency resonant circuit, a high-frequency transformer, and a rectifier circuit connected in sequence; the pre-regulator circuit adopts a Buck-Boost circuit. The DC-DC converter also includes a V / I detection module connected in parallel with the cascaded n power conversion modules; the V / I detection module is used to detect the voltage and current at the output of the DC-DC converter.

[0007] Furthermore, The high-frequency transformer adopts a frameless planar transformer, and the secondary winding uses PCB coils.

[0008] Furthermore, Each high-frequency transformer consists of one primary winding and one secondary winding; The primary winding is connected to a high-frequency resonant circuit, and the secondary winding is connected to a rectifier circuit.

[0009] Furthermore, The DC-DC converter unit also includes a freewheeling circuit, which is connected in parallel with the V / I detection circuit.

[0010] Furthermore, The DC-DC converter unit also includes a filter circuit, and the output of the rectifier circuit is connected to the filter circuit to filter out the ripple of the high voltage output. The filtering circuit is a low-pass filter composed of LC circuits.

[0011] Furthermore, The high-frequency resonant circuit adopts a half-bridge LLC resonant circuit.

[0012] Furthermore, The rectifier circuit uses a full-bridge uncontrolled rectifier.

[0013] Secondly, this disclosure also provides a high-voltage constant current remote power supply, including any of the aforementioned DC converters, as well as a main control module, a main control circuit 1, a drive circuit 1, a main control circuit 2, and a drive circuit 2. The main control module is used to control the main control circuit 1 and the main control circuit 2 based on the voltage and current signals of the V / I detection module; The main control circuit 1 and the drive circuit 1 are used to control the pre-stabilized circuit of the DC-DC converter unit; The main control circuit 2 and the drive circuit 2 are used to control the high-frequency resonant circuit of the DC-DC converter unit.

[0014] Furthermore, The drive circuit 1 connects to the power switching device of the Buck-Boost circuit. The main control circuit 1 sends a PWM signal to the drive circuit 1 according to the real-time detection signal and the instructions of the main control module, and adaptively controls the output voltage and current of the Buck-Boost circuit.

[0015] Thirdly, the disclosure also provides a control method for a high-voltage constant current remote power supply, applicable to the aforementioned high-voltage constant current remote power supply. The method includes a primary control strategy and a secondary control strategy; wherein... The primary control strategy includes: real-time detection of the output voltage and current of the DC-DC converter, the operating status of each power conversion module, and user settings; the main control module sends the operating mode of each power conversion module output by the adaptive control strategy to the main control circuit 1 and main control circuit 2 of the corresponding power conversion module. The secondary control strategy includes: secondary control strategy 1 and secondary control strategy 2; secondary control strategy 1 is responsible for the closed-loop regulation of the pre-stabilized circuit, and secondary control strategy 2 is responsible for the closed-loop regulation of the high-frequency resonant circuit.

[0016] Compared with the prior art, this disclosure provides a DC converter, a high-voltage constant current remote power supply and its control method, which have the following beneficial effects: (1) In the embodiments of this disclosure, the LLC resonant circuit avoids the problem of difficulty in soft switching of the phase-shifted full-bridge topology in a wide output power range. The adaptive control strategy of the Buck-Boost circuit also makes up for the shortcomings of the LLC resonant circuit in gain adjustment capability in a wide input-output range application. The output adjustment range is improved while the power conversion efficiency is greatly improved.

[0017] (2) By cascading three DC-DC converter units into one power conversion module, and cascading n power conversion modules into one DC-DC converter, along with a two-stage adaptive control strategy, the interleaved control of the 3n conversion modules in the DC-DC converter is realized. The output ripple of the DC-DC converter is reduced to only a fraction of that of a single-stage control. This greatly improves the stability of the DC-DC converter output parameters.

[0018] (3) Compared with phase-shifted full-bridge, half-bridge LLC reduces the number of power devices used by 50%, thus reducing the bill of materials cost (BOM) of the product.

[0019] Other features and advantages of this disclosure will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the disclosure. The objects and other advantages of this disclosure may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A block diagram illustrating the structural principle of a DC-DC converter in an embodiment of this disclosure is shown. Figure 2 A schematic diagram of the topology of a single power conversion module M in an embodiment of this disclosure is shown; Figure 3 A schematic diagram of a two-stage control strategy for a high-voltage constant current remote power supply control method in an embodiment of this disclosure is shown. Figure 4 A schematic diagram of the Buck-Boost closed-loop control strategy according to an embodiment of the present disclosure is shown; Figure 5 A schematic diagram of an LLC closed-loop control strategy according to an embodiment of the present disclosure is shown. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0023] See appendix Figure 1 and 2 , Figure 1 A structural principle block diagram of a DC-DC converter according to an embodiment of the present disclosure is shown. Figure 2 A schematic diagram of the topology of a single power conversion module M in a DC-DC converter according to an embodiment of the present disclosure is shown.

[0024] See appendix Figure 1 The DC-DC converter of this embodiment is used for high-voltage constant current remote power supply and consists of n identical power conversion modules M. n The system is composed of cascaded components, where n is a natural number, preferably 2 ≤ n ≤ 7. The cascaded configuration is a topology where the input terminals are connected in parallel and the output terminals are connected in series.

[0025] The DC-DC converter also includes a V / I detection module connected in parallel with the cascaded n power conversion modules. The V / I detection module is used to detect the voltage and current at the output of the DC-DC converter, and outputs the voltage U externally using an electro-optical conversion device and optical fiber. O and current I O Detection signal.

[0026] See appendix Figure 2 Each power conversion module consists of three identical DC-DC converters and one V / I detection circuit. The inputs of the three DC-DC converters are connected in parallel, and their outputs are connected in series, forming a cascaded structure. The V / I detection circuit is connected in parallel with the three cascaded DC-DC converters.

[0027] A single DC-DC converter unit consists of a pre-regulator circuit, a high-frequency resonant circuit, a high-frequency transformer, and a rectifier circuit connected in sequence. The DC-DC converter unit also includes a filter circuit connected in parallel to the output of the rectifier circuit. The DC-DC converter unit further includes a freewheeling circuit connected in parallel with the V / I detection circuit.

[0028] by Figure 2 Taking the topology of the first DC-DC converter unit in a single power conversion module as an example, the following description will be provided: The pre-regulator circuit uses a Buck-Boost circuit, consisting of capacitor C11, power switch Q11, inductor L11, and diode D11. For the connection topology of each component, please refer to the appendix. Figure 2 In this embodiment, the Buck-Boost circuit can boost the input low-voltage DC power supply to a medium-voltage DC power supply.

[0029] See appendix Figure 2 The high-frequency resonant circuit adopts a half-bridge LLC resonant circuit, consisting of capacitor C13, power device Q12, power device Q13, capacitor C14, capacitor C15, and resonant inductor L. r 1. Magnetizing inductance L of the primary winding of a high-frequency transformer m This circuit consists of 1 component and can achieve soft switching of a half-bridge circuit. For the connection topology of each component, please refer to the appendix. Figure 2 As alternative methods, the high-frequency resonant circuit can also employ a full-bridge LLC resonant circuit or other pulse-width modulated full-bridge soft-switching circuits. In this embodiment, the half-bridge LLC circuit converts the hundreds of volts of DC medium voltage output from the Buck-Boost circuit into an approximately sinusoidal AC current and sends it to the high-frequency transformer. Figure 2 R11 and R12 are voltage divider resistors.

[0030] The high-frequency transformer adopts a frameless planar transformer. Each high-frequency transformer includes one primary winding and one secondary winding. The primary winding is connected to the high-frequency resonant circuit, and the secondary winding is connected to the rectifier circuit. The secondary winding adopts a PCB coil design, which effectively solves the safety regulations and parasitic parameter consistency problems caused by the high voltage output of the secondary side.

[0031] The rectifier circuit uses a full-bridge uncontrolled rectifier composed of diodes D12-D14. The output of the rectifier circuit is connected to a filter circuit to filter out high-voltage output ripple. The filter circuit is preferably a low-pass filter composed of an LC circuit; in this embodiment, capacitor C16 is used as a schematic representation of the filter circuit. In this embodiment, the rectifier circuit and filter circuit can rectify the AC power boosted by the high-frequency transformer into high-voltage DC power output. Other existing topologies can also be selected for the rectifier circuit and filter circuit according to actual needs.

[0032] Based on the same inventive concept as the aforementioned DC-DC converter, embodiments of this disclosure also propose a high-voltage constant-current remote power supply, including a DC-DC converter, a main control module (not shown), a main control circuit 1, a drive circuit 1, a main control circuit 2, and a drive circuit 2. The main control module controls the main control circuit 1 and the main control circuit 2 according to the voltage and current signals from the V / I detection module. The main control circuit 1 and the drive circuit 1 control the pre-stabilized circuit of the DC-DC converter unit; the main control circuit 2 and the drive circuit 2 control the high-frequency resonant circuit of the DC-DC converter unit.

[0033] The main control module is connected to the V / I detection module via a photoelectric conversion device and optical fiber. Main control circuit 1 and main control circuit 2 are connected to the V / I detection circuit via a photoelectric conversion device and optical fiber.

[0034] The drive circuit 1 connects to the power switching device of the Buck-Boost circuit. The main control circuit 1 sends a PWM signal to the drive circuit 1 according to the real-time detection signal and the instructions of the main control module, and adaptively controls the output voltage and current of the Buck-Boost circuit.

[0035] The drive circuit 2 is connected to the power devices of the LLC circuit, and the main control circuit 2 is used to adaptively control the drive circuit 2 according to the detection signal and the instructions of the main control module.

[0036] A control method is provided for the aforementioned high-voltage constant current remote power supply. Figure 3 A schematic diagram of a two-stage control strategy for a high-voltage constant current remote power supply control method in an embodiment of this disclosure is shown.

[0037] See appendix Figure 3 The control method includes a primary control strategy (primary adaptive control strategy) and a secondary control strategy. The primary control strategy includes: real-time detection of the DC-DC converter's output voltage U. O and current I O The system includes the operating status F(n) of each power conversion module and user settings User. The main control module outputs the operating mode M(n) of each power conversion module based on the adaptive control strategy, and sends it to the corresponding main control circuit 1 and main control circuit 2. The operating mode M(n) includes the output voltage level, the pulse control angle of the Buck-Boost circuit, and the pulse control angle of the LLC circuit. The secondary control strategies include: Secondary Control Strategy 1 and Secondary Control Strategy 2. Secondary Control Strategy 1 is responsible for the closed-loop regulation of the Buck-Boost circuit, and Secondary Control Strategy 2 is responsible for the closed-loop regulation of the LLC circuit. n represents the nth power conversion module.

[0038] Appendix Figure 4The closed-loop control strategy principle of the Buck-Boost circuit (pre-regulator circuit) in this embodiment is illustrated. The main control circuit 1 receives the operating mode from the central control module and collects the input voltage Vin and chopper inductor current I of the power conversion module in real time. lref Intermediate voltage U OB Intermediate current I OB and the output voltage U of the DC-DC converter O The system generates adaptive closed-loop control parameters and outputs the PWM control signals of the three Buck-Boost circuits in the power conversion module to drive circuit 1. Drive circuit 1 is connected to the power switching devices of the Buck-Boost circuit. The closed-loop control strategy of the Buck-Boost circuit ensures that the LLC circuit operates within the optimal resonant frequency band. Intermediate voltage U OB Intermediate current I OB The output voltage and current of the Buck-Boost circuit are measured between the Buck-Boost circuit and the LLC circuit.

[0039] Appendix Figure 5 The closed-loop control strategy principle of the LLC circuit (high-frequency resonant circuit) in this embodiment is illustrated. The main control circuit 2 receives the operating mode issued by the central control module and collects the resonant inductor current I in real time. lref Intermediate current I OB Output voltage U O and output current I O The adaptive closed-loop regulation parameters are generated and output to the control signals of the three LLC circuits in the power conversion module, which are then sent to drive circuit 2. Drive circuit 2 is connected to the power devices of the LLC circuits. The closed-loop control strategy of the LLC circuit is used to ensure that the LLC circuit achieves complete soft switching.

[0040] In the embodiments of this disclosure, three DC-DC conversion units are cascaded in parallel at their input terminals and in series at their output terminals to form a single power conversion module, and n power conversion modules are cascaded in parallel at their input terminals and in series at their output terminals to form the DC-DC converter described in this disclosure.

[0041] In the embodiments of this disclosure, by cascading three DC-DC converter units into one power conversion module, cascading n power conversion modules into one DC-DC converter, and employing a two-stage adaptive control strategy, interleaved control of the 3n DC-DC converter units in the DC-DC converter is achieved, reducing the output ripple of the DC-DC converter to that of a single-stage DC-DC converter unit. This greatly improves the stability of the DC-DC converter output parameters.

[0042] Although the present disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. A DC converter, characterized in that: the DC converter is composed of n identical power conversion modules in cascade, wherein n is a natural number, 2≤n≤7; a single power conversion module is composed of 3 DC conversion units with identical structure and a V / I detection circuit; the input terminals of the 3 DC conversion units are connected in parallel, and the output terminals are connected in series, forming a cascade structure; a single DC conversion unit is composed of a pre-stabilization circuit, a high-frequency resonance circuit, a high-frequency transformer, and a rectifier circuit connected in sequence; wherein the pre-stabilization circuit adopts a Buck-Boost circuit; the DC converter further comprises a V / I detection module connected in parallel with the n power conversion modules in cascade; the V / I detection module is used for voltage and current detection of the output of the DC converter.

2. The DC converter according to claim 1, characterized in that: the high-frequency transformer adopts a skeletonless planar transformer, and the secondary winding adopts a PCB coil.

3. The DC converter according to claim 1 or 2, characterized in that: each high-frequency transformer contains one primary winding and one secondary winding; the primary winding is connected to the high-frequency resonance circuit, and the secondary winding is connected to the rectifier circuit.

4. The DC converter according to claim 1, characterized in that: the DC conversion unit further comprises a freewheeling circuit connected in parallel with the V / I detection circuit.

5. The DC converter according to claim 1 or 2 or 4, characterized in that: the DC conversion unit further comprises a filter circuit, and the output of the rectifier circuit is connected to the filter circuit to filter out the ripple of the high-voltage output; the filter circuit is a low-pass filter composed of an LC circuit.

6. The DC converter according to claim 1 or 2 or 4, characterized in that: the high-frequency resonance circuit adopts a half-bridge LLC resonance circuit.

7. The DC converter according to claim 1 or 2 or 4, characterized in that: the rectifier circuit adopts a full-bridge uncontrolled rectifier.

8. A high-voltage constant-current remote power supply, characterized in that: it comprises the DC converter according to any one of claims 1-7, and a total control module, a main control circuit 1, a driving circuit 1, a main control circuit 2, and a driving circuit 2; the total control module is used for controlling the main control circuit 1 and the main control circuit 2 according to the voltage and current signals of the V / I detection module; the main control circuit 1 and the driving circuit 1 are used for controlling the pre-stabilization circuit of the DC conversion unit; the main control circuit 2 and the driving circuit 2 are used for controlling the high-frequency resonance circuit of the DC conversion unit.

9. The high-voltage constant-current remote power supply according to claim 8, characterized in that: the driving circuit 1 is connected to the power switching device of the Buck-Boost circuit, and the main control circuit 1 is used for sending a PWM signal to the driving circuit 1 according to the real-time detection signal and the instruction of the total control module, to adaptively control the output voltage and current of the Buck-Boost circuit.

10. A control method for a high-voltage constant-current remote power supply, suitable for the high-voltage constant-current remote power supply according to claim 8 or 9, characterized in that: the method comprises a primary control strategy and a secondary control strategy; wherein, The primary control strategy comprises: detecting output voltage and current of the direct current converter, working state of each power conversion module and user setting information in real time; and sending working mode of each power conversion module output by the total control module according to the adaptive control strategy to the main control circuit 1 and the main control circuit 2 of the corresponding power conversion module. The secondary control strategy comprises: a secondary control strategy 1 and a secondary control strategy 2; the secondary control strategy 1 is responsible for closed-loop adjustment of the pre-stabilization circuit, and the secondary control strategy 2 is responsible for closed-loop adjustment of the high-frequency resonance circuit.

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