High-voltage direct-current conversion system based on modular series connection and voltage-sharing control method

Abstract

The invention discloses a high-voltage direct-current conversion system based on modular series connection and a voltage-sharing control method, and the system comprises a plurality of DCDC converter units which are connected in a step-by-step series connection manner, and the voltage is increased step by step; the voltage-sharing circuit collects the output voltage / current of the current-stage converter and regulates and controls the current-stage converter, and the control unit dynamically obtains a modulation signal in combination with a digital control algorithm and sends the modulation signal to the voltage-sharing circuit. According to the system, switching loss and energy waste during light load are reduced, an efficient working interval is widened, system energy consumption and operation cost are reduced, system conversion efficiency and light load performance are improved, and the overall conversion efficiency of the system is greatly improved through a modular series structure and accurate voltage-sharing control.

Description

Technical Field

[0001] This invention relates to the field of high voltage direct current conversion technology, and in particular to a high voltage direct current conversion system based on modular series connection and a voltage equalization control method. Background Technology

[0002] DC-DC converters, as key devices for DC voltage conversion and regulation, occupy a central position in the field of power electronics. Based on differences in function and topology, existing DC-DC converters have evolved into various types. Functionally, they are mainly classified into three categories: buck converters, boost converters, and buck-boost converters.

[0003] Buck converters convert high input voltage to a lower, stable output voltage by controlling the on / off state of a switching transistor, and are widely used in low-voltage applications such as mobile phone chargers and laptops. Boost converters can boost low input voltage to a higher output voltage, and are commonly found in applications requiring voltage boosting, such as solar panels and new energy chargers. Buck-boost converters combine the characteristics of both, offering a more flexible output voltage range, and are suitable for applications with unstable input voltage or requiring wide-range voltage regulation, such as portable electronic devices and industrial control systems.

[0004] Although various DC-DC converter technologies are relatively mature, they still have the following significant limitations when facing special needs and complex application scenarios: First, the voltage conversion range is limited. The topology of traditional single converters determines that their output voltage range has a bottleneck. For example, in renewable energy power generation systems, the output voltage of solar panels fluctuates drastically with environmental factors, and traditional converters struggle to maintain a stable and efficient output voltage across such a wide input voltage range. While boost or buck-boost converters can perform voltage conversion, their regulation capability drops significantly under a wide input range, making it difficult to achieve efficient and stable operation across the entire range. Second, conversion efficiency needs improvement. Converters incur switching losses during switching, with efficiency degradation being particularly pronounced under light load conditions. Third, dynamic response and stability are insufficient. When the load current changes abruptly or the input voltage fluctuates, the control loop of traditional converters struggles to respond quickly, resulting in large fluctuations in output voltage and long recovery times. This can cause problems in applications with extremely high voltage stability requirements (such as precision measurement and medical equipment). Simultaneously, the system is susceptible to electromagnetic interference, leading to output instability. Fourth, it is difficult to break through the upper limits of single-unit power and voltage. In application scenarios that require high output voltage and high power, such as high-voltage power transmission and fast charging of new energy, the power and voltage levels of a single converter often cannot meet the requirements. If multiple converters are directly connected in parallel to increase power, challenges such as current sharing difficulties and complex control will be faced, and the output voltage cannot be effectively improved.

[0005] Therefore, the existing single DC-DC converter has significant shortcomings in meeting the requirements of high voltage, high power, wide input range and high stability, and a new technical solution is needed to solve these comprehensive problems. Summary of the Invention

[0006] The purpose of this invention is to provide a modular series-connected high-voltage DC-DC converter system and a voltage equalization control method to solve the limitations of a single DC-DC converter in terms of output voltage, output power and stability.

[0007] The objective of this invention can be achieved through the following technical solution: a high-voltage direct current converter system based on modular series connection and a voltage equalization control method, comprising:

[0008] Multiple DC-DC converter units are connected in series in stages to increase the voltage step by step.

[0009] The voltage equalization circuit collects the output voltage / current of the current stage converter and adjusts the current stage converter according to the modulation signal of the control unit;

[0010] The control unit dynamically acquires the modulation signal based on the output voltage / current of the previous stage converter and the output voltage / current of the current stage converter, and sends it to the voltage equalization circuit.

[0011] As a further embodiment of the present invention, it also includes an input filtering circuit and an output filtering circuit, wherein:

[0012] The input filter circuit is located at the input front end of the first-stage converter and is used to filter out high-frequency noise and spurious waves in the input voltage.

[0013] The output filter circuit is set at the output end of the last stage converter to eliminate high-frequency components in the output voltage.

[0014] As a further aspect of the present invention, it also includes:

[0015] The boost module is connected to the output voltage of each stage of the converter and outputs cascaded voltage as needed.

[0016] As a further embodiment of the present invention,

[0017] As a further embodiment of the present invention, the converter cascaded is no more than 32 stages.

[0018] As a further embodiment of the present invention, the control unit uses a clock chip for synchronization control, and controls the synchronization error of each stage of switching within ±5ns.

[0019] As a further improvement of the present invention, the conversion efficiency of the system is not less than 90% when fully loaded.

[0020] As a further embodiment of the present invention, the voltage equalization circuit adopts active control, and the voltage equalization circuit includes an operational amplifier, a controller, a power switch and a sampling resistor.

[0021] A pressure equalization control method includes the following steps:

[0022] S1. Each stage of the DC-DC converter is connected in series to increase the voltage step by step.

[0023] S2. The voltage equalization circuit collects the output voltage signal of each stage of the DC-DC converter in real time, and feeds it back to the control unit after signal conditioning.

[0024] S3. The control unit, based on a preset control algorithm, compares the output voltage difference of each stage converter, generates a corresponding modulation signal, and sends it to the voltage equalization circuit.

[0025] S4. The voltage equalization circuit generates a PWM control signal based on the modulation signal, which adjusts the output impedance of the corresponding DC-DC converter to keep the output voltage of the series-connected DC-DC converters balanced.

[0026] The beneficial effects of this invention are:

[0027] 1. Under full load conditions, the system efficiency of this invention can reach over 90%. The digital control algorithm can dynamically optimize the working state of each stage of the converter, reduce switching losses and energy waste under light load, thereby widening the high-efficiency working range, reducing system energy consumption and operating costs, and significantly improving system conversion efficiency and light load performance. This invention achieves a significant improvement in the overall system conversion efficiency through modular series structure and precise voltage equalization control.

[0028] 2. This invention combines a high-precision clock chip to control the synchronization error of each stage of the switches within ±5ns, and adjusts it in real time through an active voltage equalization circuit, resulting in small voltage deviations between modules. This design effectively avoids device overload damage caused by voltage unevenness, and the built-in overvoltage, overcurrent, and other multiple protection mechanisms further enhance the system's stability and lifespan under complex operating conditions. Achieving high-voltage, high-power output and ensuring high system reliability, this invention breaks through the limitations of a single converter in voltage and power levels by sequentially connecting multiple medium- and low-specification DC-DC converter units, enabling flexible construction of systems that meet high-voltage, high-power requirements.

[0029] 3. The control unit of this invention rapidly generates modulation signals using digital algorithms based on real-time acquired voltage / current signals at various levels, driving the voltage equalization circuit to adjust the output impedance of the corresponding converter, thereby maintaining stable output voltage. In extreme cases of sudden load increases, the system voltage recovery time is extremely fast. This rapid and precise dynamic response capability makes it particularly suitable for scenarios with extremely high requirements for power supply adaptability and stability, such as solar power generation and industrial automation.

[0030] 4. Under the same output power and output voltage requirements, the system of this invention uses DC-DC converters with smaller rated voltage and rated current in series combination. These lower-specification converters have relatively low costs, reducing the overall hardware cost of the power supply system. At the same time, by improving conversion efficiency and reducing power loss, this invention further reduces operating costs.

[0031] 5. The DC-DC converter series technology used in this invention can adapt to a wider range of input voltage and load variations. Traditional single DC-DC converters typically operate efficiently only within a narrow input voltage range, and their output voltage is difficult to stabilize when the load changes abruptly. This invention, however, can flexibly modulate the operating state of each DC-DC converter according to input voltage and load changes, achieving a wide input range and stable output. This invention can adapt to large fluctuations in the output voltage of solar panels or wind turbines, and also to frequent load changes under different operating conditions in industrial automation equipment. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the high-voltage direct current converter system of the present invention;

[0033] Figure 2 This is a schematic flowchart of the pressure equalization control method of the present invention. Detailed Implementation

[0034] Embodiments of the present invention are described in detail below. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar symbols denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0035] The existing single DC-DC converter has significant shortcomings in meeting the requirements of high voltage, high power, wide input range and high stability. In order to address the above problems, this invention discloses a high voltage DC-DC converter system based on modular series connection and a voltage equalization control method.

[0036] Example 1:

[0037] This embodiment discloses a high-voltage direct current converter system based on modular series connection, such as... Figure 1 As shown, it mainly includes multiple DC-DC converter units, voltage equalization circuits, control units, filter circuits, and boost modules.

[0038] The system employs multiple DC-DC converter units connected in series, with the output of one converter connected to the input of the next, progressively increasing the voltage to meet high-voltage output requirements. This series connection allows the system to gradually increase the voltage based on each DC-DC converter unit, thereby achieving high-voltage output. Furthermore, each DC-DC converter unit has independent voltage conversion capabilities, enabling precise adjustment and control of the input voltage.

[0039] The voltage equalization circuit collects the output voltage / current of the current stage converter and adjusts the current stage converter according to the modulation signal of the control unit.

[0040] The voltage equalization circuit is connected to the output terminal of each stage converter and is used to detect the output voltage of each stage converter. Through efficient control by the control unit, it ensures that each DC-DC converter bears an equal voltage during series operation, avoiding overload damage to the converter unit due to uneven voltage, thereby ensuring the efficient and stable operation of the power system.

[0041] Preferably, the voltage equalization circuit employs an active control method. The voltage equalization circuit consists of an operational amplifier, a controller, power switching transistors, and sampling resistors. The operational amplifier amplifies the received signal to a range that can be recognized and processed, ensuring the accuracy and stability of the signal. The controller, as the core control component of the voltage equalization circuit, receives the processed modulation signal and generates a corresponding PWM control signal according to a preset control strategy. The power switching transistors then precisely regulate the voltage of the current stage converter based on the PWM control signal output by the controller.

[0042] The voltage equalization circuit can respond quickly and accurately to voltage changes. Compared with traditional voltage equalization circuits, it features faster response speed and more stable voltage equalization. This active control method of voltage equalization circuit has the advantages of fast response speed and high control accuracy. It can monitor and adjust the output voltage of each stage of the converter in real time, ensuring that the voltage across all DC-DC converter units remains equal under various operating conditions.

[0043] Meanwhile, thanks to the modular design concept, the various components work independently yet collaboratively, facilitating system maintenance and upgrades. Even if a component fails, it can be quickly located and replaced without affecting the normal operation of the entire power system, further improving the reliability and stability of the modular series-based high-voltage DC-DC converter system.

[0044] The control unit dynamically acquires the modulation signal based on the output voltage / current of the previous stage converter and the output voltage / current of the current stage converter, combined with a digital control algorithm, and sends it to the voltage equalization circuit.

[0045] The control unit is connected to each stage of the voltage equalization circuit and relies on the sampling resistors of the voltage equalization circuit to acquire the output voltage / current of each stage of the converter. The control unit can be implemented by an F28032 processor, whose main function is to balance the load distribution among the converters. By monitoring the current and voltage signals of each branch in real time, it dynamically generates modulation signals using digital control algorithms and sends them to the voltage equalization circuit to ensure that the system can maintain efficient operation under different operating conditions.

[0046] Furthermore, the control unit integrates protection mechanisms, possessing the ability to detect and respond to faults such as overvoltage, overcurrent, and abnormal temperature, effectively improving system reliability and safety. When an overvoltage condition is detected, the control unit will quickly adjust the modulation signal to reduce the output voltage, preventing excessive voltage from damaging other components in the system. If an overcurrent occurs, the control unit will promptly take current-limiting measures to reduce current output, avoiding problems such as overheating and short circuits caused by excessive current.

[0047] Furthermore, upon detecting a fault, the control unit immediately records the fault information, including the time and type of the fault, as well as relevant parameters such as voltage, current, and temperature, facilitating subsequent troubleshooting and system maintenance. The control unit also communicates with an external monitoring system to promptly upload fault information, enabling operators to quickly understand the system status and make appropriate decisions.

[0048] This comprehensive protection mechanism and fault handling process enable the modular series-based high-voltage DC-DC converter system to operate stably and reliably in complex and ever-changing working environments, providing a solid guarantee for various application scenarios that require high-voltage DC power.

[0049] Furthermore, the system supports expansion to up to 32 converter stages, meeting diverse voltage level requirements in different application scenarios. Each converter stage adopts a standardized design, ensuring good compatibility and interchangeability, facilitating system installation, commissioning, and maintenance. During expansion, the converters can achieve fast and stable communication and synchronization, ensuring the stability of the entire system's output voltage and power.

[0050] Furthermore, the control unit employs a clock chip for synchronization control, keeping the switching synchronization error of each stage within ±5ns, significantly improving the switching consistency of the system. Precise synchronization control effectively reduces interference and losses between each stage of the converter, resulting in a significant improvement in system efficiency during operation. Under high-frequency switching operations, a synchronization error within ±5ns ensures that the switching actions of each stage of the converter occur almost simultaneously, avoiding voltage fluctuations and current spikes caused by inconsistent switching times.

[0051] Meanwhile, this high-precision synchronous control also benefits the system's voltage equalization control. With minimal synchronization error, each stage of the converter can achieve better voltage equalization, ensuring that each stage of the converter experiences a relatively uniform voltage, thereby extending the converter's lifespan and reducing the risk of system damage due to excessively high local voltage.

[0052] Through experimental comparison, under the same input voltage and load conditions, the DC-DC converter system using the present invention achieves a 15% to 20% improvement in conversion efficiency compared to a single DC-DC converter. Under light load conditions, the efficiency of a conventional converter may drop to around 60%, while the efficiency of the present invention system remains below 80%. Under full load conditions, the efficiency of a conventional converter operates at around 80%, while the efficiency of the present invention system can reach over 90%.

[0053] When an external power supply is connected to the DC-DC converter series system of this invention, the input voltage first passes through a filter circuit to eliminate high-frequency components, providing a stable input voltage for the first-stage DC-DC converter. The first-stage DC-DC converter outputs a first-stage output voltage. This first-stage output voltage provides the voltage input for the second-stage DC-DC converter, whose output voltage is the first-stage output voltage plus the voltage output from the second-stage DC-DC converter. This process continues, with each subsequent DC-DC converter adding the conversion result of the previous stage to the current voltage, thus achieving a step-by-step voltage increase and adjustment.

[0054] The voltage equalization circuit monitors the output voltage of each DC-DC converter in real time. If an imbalance is detected, it immediately adjusts the output impedance of that converter to ensure consistent output voltage across all converters, thus guaranteeing stable system operation. The control unit collects input and output voltage, current, and temperature parameters from each DC-DC converter in real time using sensors. Based on a preset control algorithm, it analyzes and processes these parameters, adjusting the frequency, phase, and duty cycle of the PWM control signals for each converter to optimize their operation and improve system stability.

[0055] Example 2:

[0056] Based on Example 1, the high voltage direct current converter system in this example is further provided with a filter circuit, which includes an input filter circuit and an output filter circuit.

[0057] The input filter circuit, located at the input front end of the first-stage converter, filters out high-frequency noise and spurious signals from the input voltage, providing a stable input voltage for the entire power supply system. This ensures that subsequent converter stages can operate under a stable voltage environment, reducing the impact of input voltage fluctuations and noise interference on converter performance. Simultaneously, the input filter circuit also improves the power supply system's anti-interference capability, enhancing system stability and reliability.

[0058] The output filter circuit, located at the output end of the last stage converter, eliminates high-frequency components in the output voltage, reduces output ripple, and makes the high-voltage DC output voltage cleaner and more stable, meeting the needs of various applications with high power quality requirements. Furthermore, the output filter circuit can also optimize the system output current, reducing current fluctuations and improving the overall system performance and efficiency.

[0059] The input and output filter circuits work together to form a complete filtering system, providing a good power supply environment for the modular series-based high-voltage DC-DC converter system, ensuring stable system operation and high-quality output.

[0060] Example 3:

[0061] Based on Embodiment 1 or 2, the high-voltage direct current converter system in this embodiment is further provided with a boost module.

[0062] like Figure 1 As shown, the boost module is used to output a cascaded voltage from the output voltages of each stage of the converter, based on requirements. The boost module can flexibly adjust the magnitude of the cascaded output voltage according to set parameters and actual application scenarios. It can accurately integrate and boost the output voltages of each stage of the converter to meet the specific requirements of different loads for high-voltage DC voltage. During operation, the boost module achieves efficient voltage conversion and stable output through advanced circuit design and control algorithms, ensuring that the output high-voltage DC voltage reaches the expected value.

[0063] Furthermore, the boost module also features a real-time monitoring and feedback mechanism, which automatically adjusts internal parameters based on changes in output voltage to ensure the stability and accuracy of the output voltage. It can seamlessly integrate with input and output filter circuits to further optimize the performance of the entire high-voltage DC-DC converter system.

[0064] Example 4:

[0065] Based on the high-voltage direct current converter system of Embodiments 1, 2, or 3, this embodiment discloses a voltage equalization control method, such as... Figure 2 As shown, the steps include:

[0066] S1. Each stage of the DC-DC converter is connected in series to increase the voltage step by step, and the voltage equalization control strategy ensures the balance of the output voltage of each stage of the converter.

[0067] A predetermined number of standardized DC-DC converter units are connected in series in stages, and the electrical connection between the output of the previous stage DC-DC converter and the input of the next stage is clearly defined, forming a cascaded voltage boosting link.

[0068] Configure the control unit parameters, load the preset voltage equalization control strategy, voltage threshold range and synchronization control parameters; start the synchronization control mechanism of each stage converter through the clock chip integrated in the control unit, calibrate the synchronization error of each stage switch to within ±5ns, and ensure the consistency of switching action.

[0069] After initialization, the system starts up and gradually increases the voltage through the independent voltage conversion function of each DC-DC converter, initially forming a high-voltage output prototype. At this time, the control unit enters the voltage equalization monitoring standby state, laying the foundation for subsequent voltage equalization regulation.

[0070] S2. The voltage equalization circuit collects the output voltage signal of each stage of the DC-DC converter in real time, and feeds it back to the control unit after signal conditioning.

[0071] During system operation, the voltage equalization circuits adapted to each stage of the DC-DC converter are continuously in operation: the voltage equalization circuits acquire the output voltage signal of the corresponding stage converter in real time through the sampling resistor, and can also assist in acquiring the output current signal as reference data.

[0072] The acquired voltage signal may contain high-frequency noise and interference signals, which need to be amplified by the operational amplifier inside the voltage equalization circuit to amplify the signal to a range that the control unit can recognize and process, while filtering out some noise.

[0073] After amplification, the signal is processed by a signal conditioning module for noise reduction and voltage stabilization to ensure the accuracy and stability of the signal. The conditioned standardized voltage signal is then fed back to the signal receiving port of the control unit, forming a closed-loop data input for voltage monitoring.

[0074] S3. The control unit, based on a preset control algorithm, compares the output voltage differences of each stage of the converter, generates corresponding modulation signals, and sends them to the voltage equalization circuit.

[0075] After receiving the standardized voltage signals from the voltage equalization circuits at each stage, the control unit starts the preset digital control algorithm to process the data.

[0076] First, the voltage signals at each stage are buffered and synchronized in real time. The synchronization signal from the clock chip eliminates the impact of time differences in signal transmission. Then, the average output voltage of each converter stage is calculated, and the voltage value of each stage is compared with the average to obtain the difference between each stage's voltage and the mean. Simultaneously, the load distribution is determined by referring to the acquired current signal. Next, based on the magnitude and direction of the voltage difference, the control algorithm generates a corresponding modulation signal according to a preset adjustment coefficient. The parameters of the modulation signal are positively correlated with the voltage deviation; that is, the larger the deviation, the stronger the modulation signal's adjustment force. Finally, the generated modulation signal is sent to the corresponding voltage equalization circuit to form an adjustment command.

[0077] S4. The voltage equalization circuit generates a PWM control signal based on the modulation signal, which adjusts the output impedance of the corresponding DC-DC converter to keep the output voltage of the series-connected DC-DC converters balanced.

[0078] After receiving the modulation signal sent by the control unit, the voltage equalization circuit analyzes and converts the modulation signal through its internal controller. Based on the parameters of the modulation signal, it generates a corresponding PWM (Pulse Width Modulation) control signal. The duty cycle of the PWM signal is matched with the adjustment requirements of the modulation signal. That is, for converters with positive voltage deviation, the duty cycle of the PWM signal is reduced to lower its output voltage, and for converters with negative voltage deviation, the duty cycle of the PWM signal is increased to raise its output voltage.

[0079] The generated PWM control signal is transmitted to the power switch in the voltage equalization circuit. The power switch controls its own turn-on and turn-off duration according to the pulse timing of the PWM signal, thereby precisely adjusting the output impedance of the corresponding DC-DC converter.

[0080] By dynamically adjusting the output impedance, the output voltage of each stage of the converter is gradually calibrated to near the average value, achieving voltage balance in a series configuration. During this process, the voltage equalization circuit sends the adjusted voltage signal back to the control unit in real time, forming a closed-loop regulation to ensure that the voltage of each stage remains balanced when the load changes or the operating conditions fluctuate.

[0081] Application Example 1:

[0082] The high-voltage direct current system of a photovoltaic power station, and the application of the technology of this invention in a 500kW photovoltaic power station, are specifically implemented as follows:

[0083] It employs 20 25kW DC-DC converter modules, with an input voltage range of 400-800VDC and a total output voltage of 2000VDC;

[0084] All converter modules adopt a full-bridge isolated topology, with a switching frequency of 50kHz, and the parameters of key components are completely consistent.

[0085] The control unit uses a TMS320F28032DSP to implement a high-precision control algorithm; the synchronization control uses a dedicated clock chip, and the synchronization error is controlled within ±5ns.

[0086] The heat dissipation integrated unit adopts liquid cooling, and the flow control is dynamically adjusted according to the temperature of each module;

[0087] The system supports expansion to a maximum of 32 modules, with a total power of up to 800kW and an output voltage of 3200VDC.

[0088] Actual operation tests show that the voltage deviation of each module is less than 0.8% when the system is running at full load, and the conversion efficiency reaches 97.8%. Under 10% load conditions, the efficiency is still maintained at 96.2%.

[0089] Application Example 2:

[0090] The present invention is applied to a 300kW industrial high-voltage power supply system, and the specific implementation method is as follows:

[0091] It uses 15 identical 20kW DC-DC converter modules, with an input voltage of 400VDC and a total output voltage of 1500VDC;

[0092] The converter operates within a temperature range of -40℃ to +85℃, meeting the requirements of industrial environments.

[0093] The voltage equalization adjustment unit has a sampling frequency of 1MHz to ensure fast response;

[0094] The protection mechanism has a response time of ≤10μs, which can effectively prevent the spread of faults;

[0095] The system features hot-swappable functionality, supports online module replacement, and the output voltage fluctuation during the replacement process is ≤2%.

[0096] Test results show that the system can run continuously for 1000 hours without failure, the drift of each module parameter is less than 0.5%, and the voltage recovery time is 120μs when the load suddenly increases from 10% to 100%.

[0097] The two application examples above demonstrate that the system of this invention exhibits superior performance and reliability in high-voltage power supply systems across various scenarios. In communication base station power supply systems, the high conversion efficiency significantly reduces energy loss, improves energy utilization efficiency, and reduces operating costs. Even under low load conditions, it maintains high efficiency, which is particularly important for applications like communication base stations where load variations are significant. In industrial high-voltage power supply systems, the wide operating temperature range, rapid voltage equalization regulation response, extremely short protection mechanism response time, and hot-swappable functionality ensure stable operation of the system in complex industrial environments, effectively preventing fault propagation, reducing downtime, and improving production efficiency.

[0098] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A high-voltage direct current converter system based on modular series connection, characterized in that, include: Multiple DC-DC converter units are connected in series in stages to increase the voltage step by step. The voltage equalization circuit collects the output voltage / current of the current stage converter and adjusts the current stage converter according to the modulation signal of the control unit; The control unit dynamically acquires the modulation signal based on the output voltage / current of the previous stage converter and the output voltage / current of the current stage converter, and sends it to the voltage equalization circuit.

2. The high-voltage direct current converter system according to claim 1, characterized in that, It also includes input filtering circuits and output filtering circuits, wherein: The input filter circuit is located at the input front end of the first-stage converter and is used to filter out high-frequency noise and spurious waves in the input voltage. The output filter circuit is set at the output end of the last stage converter to eliminate high-frequency components in the output voltage.

3. The high-voltage direct current converter system according to claim 1, characterized in that, Also includes: The boost module is connected to the output voltage of each stage of the converter and outputs cascaded voltage as needed.

4. The high-voltage direct current converter system according to claim 1, characterized in that, The number of cascaded converters shall not exceed 32.

5. The high-voltage direct current converter system according to claim 1, characterized in that, The control unit uses a clock chip for synchronization control, keeping the synchronization error of each switching stage within ±5ns.

6. The high-voltage direct current converter system according to claim 1, characterized in that, At full load, the conversion efficiency of this system is no less than 90%.

7. The high-voltage direct current converter system according to claim 1, characterized in that, The voltage equalization circuit employs active control and includes an operational amplifier, a controller, a power switch, and a sampling resistor.

8. The high-voltage direct current converter system according to any one of claims 1 to 7, characterized in that, A pressure equalization control method includes the following steps: S1. Each stage of the DC-DC converter is connected in series to increase the voltage step by step. S2. The voltage equalization circuit collects the output voltage signal of each stage of the DC-DC converter in real time, and feeds it back to the control unit after signal conditioning. S3. The control unit, based on a preset control algorithm, compares the output voltage difference of each stage converter, generates a corresponding modulation signal, and sends it to the voltage equalization circuit. S4. The voltage equalization circuit generates a PWM control signal based on the modulation signal, which adjusts the output impedance of the corresponding DC-DC converter to keep the output voltage of the series-connected DC-DC converters balanced.

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