Multifunctional charging pile system based on solid-state transformer

Abstract

The invention discloses a multifunctional charging pile system based on a solid-state transformer. The multifunctional charging pile system comprises an energy input module, an energy conversion module, an energy storage module and a charging output module. According to the multifunctional charging pile system based on the solid-state transformer, the direct-current solid-state transformer and the low-voltage DC / DC converter are adopted as core components of the energy conversion module, and the direct-current solid-state transformer works cooperatively through the filter inductor, the half-bridge module and the DC-DC isolation type converter; the half-bridge module is formed by connecting two full-control type switching devices in series, the two ends of the half-bridge module are connected with reverse diodes in parallel, high efficiency and stability in the conversion process are ensured, the resonant frequency of the LC series resonance link is 20 kHz, the daily operation cost is minimized, and the SOC state of the storage battery is monitored in real time, so that high-voltage direct current and low-voltage direct current are effectively isolated and converted. The charging and discharging process is accurately controlled, the charging and discharging efficiency is ensured to reach 92% or above, and the energy utilization efficiency is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of charging piles, and in particular to a multifunctional charging pile system based on a solid-state transformer. Background Art

[0002] With the increasing number of electric vehicles, large-scale charging is inevitable, which will bring challenges to the safe and economic operation of the power system. In most cases at present, electric vehicles charge their batteries with AC power through an on-board rectifier or using the rectifier device of a charging pile. Both methods convert AC power into DC power before charging the battery, resulting in large power losses and harmonic distortion. Solid-state transformers, as a new type of power electronic device, have the advantages of high efficiency, flexibility, and small size. They show broad application prospects in power systems. Applying solid-state transformers to charging pile systems can significantly improve charging efficiency and system flexibility.

[0003] However, the existing charging pile system based on solid-state transformers still has some technical bottlenecks, such as low energy conversion efficiency, unintelligent energy storage management, and inflexible charging power distribution. Summary of the Invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a multifunctional charging pile system based on a solid-state transformer, the purpose of which is to solve the problems of low conversion efficiency, single function, and inflexible charging power distribution in the charging pile system.

[0005] In order to achieve the above-mentioned purpose of the invention, the technical solution adopted by the present invention is: a multifunctional charging pile system based on a solid-state transformer, including an energy input module, an energy conversion module, an energy storage module, and a charging output module;

[0006] Energy input module: The photovoltaic array is connected to the intelligent combiner box to collect solar energy and output DC power;

[0007] Energy conversion module: a DC solid-state transformer and a low-voltage DC / DC converter; the DC solid-state transformer includes a filter inductor, a half-bridge module, and a DC-DC isolated converter, wherein the filter inductor is connected to the DC input of the half-bridge module, and the output of the half-bridge module is connected to the input of the DC-DC isolated converter; the DC-DC isolated converter includes a single-phase full-bridge inverter, an LC series resonant link, a high-frequency transformer, and a single-phase bridge rectifier to achieve isolated conversion between high-voltage DC (±750V) and low-voltage DC (48V);

[0008] Energy storage module: The battery is connected to the DC solid-state transformer through an intelligent combiner box, supporting bidirectional charging and discharging;

[0009] Charging output module: includes multiple charging guns and charging interfaces, driven by a low-voltage DC / DC converter, and supports dynamic power distribution;

[0010] The control device coordinates and controls the energy input module, energy conversion module, energy storage module and charging output module respectively.

[0011] Furthermore, the half-bridge module in the energy conversion module is composed of two fully controlled switching devices connected in series, with reverse diodes connected in parallel at both ends. The resonant frequency of the LC series resonant link is 20kHz, and the resonant inductor and resonant capacitor are connected in series between the full-bridge inverter and the high-frequency transformer; the high-frequency transformer has a transformation ratio of 10:1, the magnetic core material is nanocrystalline alloy, and the conversion efficiency is ≥97%.

[0012] Furthermore, the low-voltage DC / DC converter includes: a bidirectional Buck-Boost topology consisting of two fully controlled switching devices, an inductor and a capacitor; an input voltage range of 200-1000V, an output voltage accuracy of ≤±2%, and compatibility with lead-acid batteries and lithium-ion batteries; inductors and capacitors (tolerance ≤±5%) realize dynamic power buffering.

[0013] Furthermore, the control device is a DSP controller that integrates the following functions: a mixed integer linear programming algorithm is used to optimize energy distribution, with the objective function being to minimize daily operating costs; real-time monitoring of the battery SOC status, with a charge and discharge efficiency ≥92% and a cycle life ≥5000 times; and voltage / current dual closed-loop control is achieved through PI regulation, with a dynamic response time ≤100ms.

[0014] Furthermore, the DC fast charging gun of the charging output module has a rated power of ≥150kW and supports dynamic power allocation (10%-100%); the AC slow charging interface integrates a leakage protection device, the charging efficiency is ≥95%, and the harmonic distortion rate is ≤3%; it is compatible with the CCS charging protocol, and the communication delay is ≤50ms.

[0015] Furthermore, the SOC lower limit of the battery in the energy storage module is set to 30%, supporting capacity priority allocation in emergency power supply scenarios; the charging and discharging protocol is matched with the DC solid-state transformer, and the reverse discharge power is ≥ 80% of the rated power.

[0016] Furthermore, the control switch group of the single-phase full-bridge inverter and the bridge rectifier in the DC-DC isolated converter is composed of IGBTs, and the trigger pulse frequency is 20kHz; the voltage balancing control accuracy of the high-voltage side DC capacitor and the low-voltage side DC capacitor is ≤±1%.

[0017] Furthermore, the driving signal of the fully controlled switching device in the low-voltage DC / DC converter adopts PWM modulation, and the duty cycle dynamic range is 5%-95%; the capacitor adopts a film capacitor with a withstand voltage level of ≥1200V and an equivalent series resistance of ≤10mΩ.

[0018] Furthermore, the control device also includes an equipment life prediction model based on an LSTM neural network, with a fault warning accuracy rate of ≥95%; a temperature / humidity sensor monitors environmental parameters in real time, and the over-temperature protection threshold is set at 85°C.

[0019] The beneficial effects of the present invention are:

[0020] The present invention provides a multifunctional charging pile system based on a solid-state transformer. The present invention adopts a DC solid-state transformer and a low-voltage DC / DC converter as core components of the energy conversion module. The DC solid-state transformer realizes efficient isolation conversion between high-voltage DC and low-voltage DC through the coordinated work of a filter inductor, a half-bridge module and a DC-DC isolation converter. The half-bridge module is composed of two fully-controlled switching devices in series, and reverse diodes are connected in parallel at both ends to ensure high efficiency and stability during the conversion process. The resonant frequency of the LC series resonance link is 20kHz, which further optimizes the energy conversion efficiency. The high-frequency transformer adopts nanocrystalline alloy core material with a conversion efficiency of more than 97%, which significantly improves the overall energy conversion efficiency of the charging pile system. The control device adopts a DSP controller and integrates a mixed integer linear programming algorithm to optimize energy distribution and minimize daily operating costs. By real-time monitoring of the battery SOC state, the charging and discharging process is accurately controlled to ensure that the charging and discharging efficiency is as high as more than 92%, further improving the energy utilization efficiency.

[0021] The charging output module designed in the present invention includes multiple charging guns and charging interfaces, supports DC fast charging and AC slow charging, has a rated power of up to 150kW or more, and supports dynamic power distribution. The DC fast charging gun supports dynamic power distribution of 10%-100%, and the AC slow charging interface integrates a leakage protection device, has high charging efficiency, low harmonic distortion rate, and is compatible with the CCS charging protocol, meeting the diverse requirements of different vehicle models and charging needs. The SOC lower limit of the battery in the energy storage module is set to 30%, supporting capacity priority allocation in emergency power supply scenarios, and the charging and discharging protocol is matched with the DC solid-state transformer. The reverse discharge power is as high as 80% of the rated power, ensuring the emergency power supply capability of the charging pile system in the event of a grid failure or power outage. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a structural schematic diagram of a multifunctional charging pile system based on a solid-state transformer according to the present invention;

[0023] Figure 2This is a schematic structural diagram of an energy conversion module of a multifunctional charging pile system based on a solid-state transformer according to the present invention; DETAILED DESCRIPTION

[0024] The specific embodiments of the present invention are further described below with reference to the accompanying drawings, wherein the same parts are represented by the same reference numerals.

[0025] It should be noted that the words "front", "rear", "left", "right", "up" and "down" used in the following description refer to directions in the accompanying drawings, and the words "inside" and "outside" refer to directions toward or away from the geometric center of a specific component, respectively.

[0026] In order to make the contents of the present invention more clearly understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0027] like Figures 1 to 2 As shown, a multifunctional charging pile system based on a solid-state transformer includes an energy input module, an energy conversion module, an energy storage module, and a charging output module;

[0028] Energy input module: The photovoltaic array is connected to the intelligent combiner box to collect solar energy and output DC power;

[0029] Energy conversion module: a DC solid-state transformer and a low-voltage DC / DC converter; the DC solid-state transformer includes a filter inductor, a half-bridge module, and a DC-DC isolated converter, wherein the filter inductor is connected to the DC input of the half-bridge module, and the output of the half-bridge module is connected to the input of the DC-DC isolated converter; the DC-DC isolated converter includes a single-phase full-bridge inverter, an LC series resonant link, a high-frequency transformer, and a single-phase bridge rectifier to achieve isolated conversion between high-voltage DC (±750V) and low-voltage DC (48V);

[0030] Energy storage module: The battery is connected to the DC solid-state transformer through an intelligent combiner box, supporting bidirectional charging and discharging;

[0031] Charging output module: includes multiple charging guns and charging interfaces, driven by a low-voltage DC / DC converter, and supports dynamic power distribution;

[0032] The control device coordinates and controls the energy input module, energy conversion module, energy storage module and charging output module respectively.

[0033] The half-bridge module in the energy conversion module is composed of two fully controlled switching devices connected in series, with reverse diodes connected in parallel at both ends. The resonant frequency of the LC series resonant link is 20kHz, and the resonant inductor and resonant capacitor are connected in series between the full-bridge inverter and the high-frequency transformer; the high-frequency transformer has a transformation ratio of 10:1, the magnetic core material is nanocrystalline alloy, and the conversion efficiency is ≥97%.

[0034] The low-voltage DC / DC converter includes a bidirectional Buck-Boost topology consisting of two fully controlled switching devices, an inductor, and a capacitor. It has an input voltage range of 200-1000V, an output voltage accuracy of ≤±2%, and is compatible with both lead-acid and lithium-ion batteries. The inductor and capacitor (with a tolerance of ≤±5%) provide dynamic power buffering.

[0035] The control device is a DSP controller that integrates the following functions: a mixed integer linear programming algorithm is used to optimize energy distribution, with the objective function being to minimize daily operating costs; real-time monitoring of the battery state of charge (SOC), with a charge and discharge efficiency of ≥92% and a cycle life of ≥5,000 times; and voltage / current dual closed-loop control achieved through PI regulation, with a dynamic response time of ≤100ms.

[0036] The DC fast charging gun of the charging output module has a rated power of ≥150kW and supports dynamic power allocation (10%-100%); the AC slow charging interface integrates a leakage protection device, with a charging efficiency of ≥95% and a harmonic distortion rate of ≤3%; it is compatible with the CCS charging protocol and has a communication delay of ≤50ms.

[0037] The SOC lower limit of the battery in the energy storage module is set to 30%, supporting capacity priority allocation in emergency power supply scenarios; the charging and discharging protocol is matched with the DC solid-state transformer, and the reverse discharge power is ≥ 80% of the rated power.

[0038] The control switch group of the single-phase full-bridge inverter and the bridge rectifier in the DC-DC isolation converter is composed of IGBTs, and the trigger pulse frequency is 20kHz; the voltage balancing control accuracy of the high-voltage side DC capacitor and the low-voltage side DC capacitor is ≤±1%.

[0039] The driving signal of the fully controlled switch device in the low-voltage DC / DC converter adopts PWM modulation, and the duty cycle dynamic range is 5%-95%; the capacitor adopts a film capacitor with a withstand voltage level of ≥1200V and an equivalent series resistance of ≤10mΩ.

[0040] The control device also includes an equipment life prediction model based on an LSTM neural network, with a fault warning accuracy rate of ≥95%; a temperature / humidity sensor monitors environmental parameters in real time, and the over-temperature protection threshold is set at 85°C.

[0041] Example 1:

[0042] Energy synergy and dynamic scheduling under conventional charging mode

[0043] Energy input module operation process: The photovoltaic array collects solar energy and outputs DC power through the smart combiner box, using the maximum power point tracking (MPPT) algorithm to optimize power generation efficiency and ensure that the conversion efficiency of the photovoltaic modules is ≥22%. When the light intensity changes, the smart combiner box adjusts the voltage range (200-1000V) input to the DC solid-state transformer in real time, and suppresses high-frequency harmonic interference through filter inductors.

[0044] Technical details of the energy conversion module: The half-bridge module of the DC solid-state transformer consists of two fully-controlled IGBTs in series, and the reverse diode is connected in parallel to eliminate switching losses. The resonant frequency of the LC series resonant link is 20kHz, and the high-frequency transformer ratio is 10:1, realizing isolated conversion of ±750V high-voltage DC to 48V low-voltage DC, with an efficiency of ≥97%. The low-voltage DC / DC converter adopts a bidirectional Buck-Boost topology, dynamically adjusting the output voltage to the required range of the charging gun (such as 750V fast charging or 48V slow charging), with an output voltage accuracy of ≤±2%, and the film capacitor voltage rating is ≥1200V to ensure stability.

[0045] Coordinated control of energy storage and charging: The DSP controller of the control device optimizes daily operating costs based on the mixed integer linear programming (MILP) algorithm, giving priority to charging the battery (SOC 30%-90%) during the grid valley period (low electricity price), and reversely discharging to the charging pile during peak period, with a charging and discharging efficiency of ≥92%; the DC fast charging gun of the charging output module supports dynamic power distribution (10%-100%), with a response time of ≤100ms, and the harmonic distortion rate of the AC slow charging interface ≤3%, and is compatible with the CCS protocol.

[0046] Example 2:

[0047] Fast switching and safety protection in off-grid emergency power supply mode

[0048] Grid fault response mechanism: When a grid voltage fluctuation of >±10% or a frequency deviation of >0.5Hz is detected, the control device immediately switches to off-grid mode. The energy storage module prioritizes powering the emergency charging gun (power ≥80% of the rated value), and the power of the non-emergency interface is limited to 30%. The SOC lower limit of the energy storage module is set to 30% to ensure that the emergency power supply duration is ≥2 hours. The liquid cooling system maintains the battery temperature at 25±5℃ to prevent capacity decay.

[0049] Energy conversion path optimization: Battery power is converted into 48V low-voltage DC through a DC solid-state transformer, and then boosted to 750V through a low-voltage DC / DC converter to drive the fast charging gun. The IGBT trigger pulse frequency is 20kHz, and the voltage balancing control accuracy is ≤±1%; the single-phase full-bridge inverter and bridge rectifier use IGBT control switch groups, and PI regulation is used to achieve voltage / current dual closed-loop control, with a dynamic response time of ≤100ms.

[0050] Safety redundancy design: A temperature sensor monitors the high-frequency transformer core (made of nanocrystalline alloy) in real time. The over-temperature protection threshold is set at 85°C. When the limit is exceeded, load reduction protection is triggered and an early warning message is sent to the user terminal. The leakage protection device is integrated into the AC slow charging port. The equivalent series resistance is ≤10mΩ, ensuring charging efficiency ≥95%.

[0051] Example 3:

[0052] Smart grid collaboration and equipment life prediction management

[0053] Multi-station energy mutual assistance strategy: Interconnected with adjacent charging stations through high-voltage DC ports (±750V), electricity trading is triggered when the real-time electricity price difference is greater than 0.2 yuan / kWh, and the transmission efficiency is ≥95%. The MILP algorithm optimizes energy distribution among multiple stations, with constraints including transformer capacity (≤85% of rated value) and SOC safety range (30%-90%), reducing daily operating costs by ≥15%.

[0054] Equipment life prediction and maintenance: The control device integrates an LSTM neural network model to analyze the historical operating data of IGBT switching devices (such as temperature and load fluctuations), predict the remaining life of the equipment and generate a maintenance plan 30 days in advance, with a prediction accuracy of ≥95%; the blockchain node records charging pile usage data and fault logs (including timestamps and device IDs). The data cannot be tampered with and is used for fault tracing and protocol optimization.

[0055] Environmental adaptability design: A humidity sensor linked to a liquid cooling system maintains the energy storage module's operating temperature at 25±5°C, with a capacitance tolerance of ≤±5% and a ≥20% improvement in dynamic power buffering capacity. The user terminal app displays photovoltaic power generation, energy storage SOC status, and charging cost details in real time, supports scheduled charging and dynamic power adjustment, and has a communication delay of ≤50ms.

[0056] The charging station system based on the intelligent energy routing device provided by the present invention,

[0057] Economical: Optimizing multi-source collaborative scheduling through the MILP algorithm reduces daily operating costs by ≥15%, which is in line with the "serving the real economy" orientation of the patent transformation action plan.

[0058] Reliability: The LSTM model predicts equipment life with an accuracy rate of ≥95%. Combined with the liquid cooling system and blockchain monitoring, the system failure rate is reduced by ≥30%.

[0059] Compatibility: Supports mixed use of lead-acid batteries and lithium-ion batteries, with a dynamic power allocation range of 10%-100%, adapting to the charging needs of different models.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A multifunctional charging pile system based on a solid-state transformer, characterized in that: Including energy input module, energy conversion module, energy storage module, and charging output module; Energy input module: The photovoltaic array is connected to the intelligent combiner box to collect solar energy and output DC power; Energy conversion module: a DC solid-state transformer and a low-voltage DC / DC converter; the DC solid-state transformer includes a filter inductor, a half-bridge module, and a DC-DC isolated converter, wherein the filter inductor is connected to the DC input of the half-bridge module, and the output of the half-bridge module is connected to the input of the DC-DC isolated converter; the DC-DC isolated converter includes a single-phase full-bridge inverter, an LC series resonant link, a high-frequency transformer, and a single-phase bridge rectifier to achieve isolated conversion between high-voltage DC (±750V) and low-voltage DC (48V); Energy storage module: The battery is connected to the DC solid-state transformer through an intelligent combiner box, supporting bidirectional charging and discharging; Charging output module: includes multiple charging guns and charging interfaces, driven by a low-voltage DC / DC converter, and supports dynamic power distribution; The control device coordinates and controls the energy input module, energy conversion module, energy storage module and charging output module respectively.

2. The multifunctional charging pile system based on a solid-state transformer according to claim 1, characterized in that: The half-bridge module in the energy conversion module is composed of two fully controlled switching devices connected in series, with reverse diodes connected in parallel at both ends. The resonant frequency of the LC series resonant link is 20kHz, and the resonant inductor and resonant capacitor are connected in series between the full-bridge inverter and the high-frequency transformer; the high-frequency transformer has a transformation ratio of 10:1, the magnetic core material is nanocrystalline alloy, and the conversion efficiency is ≥97%.

3. The multifunctional charging pile system based on a solid-state transformer according to claim 1, characterized in that: The low-voltage DC / DC converter includes a bidirectional Buck-Boost topology consisting of two fully controlled switching devices, an inductor, and a capacitor. It has an input voltage range of 200-1000V, an output voltage accuracy of ≤±2%, and is compatible with both lead-acid and lithium-ion batteries. The inductor and capacitor (with a tolerance of ≤±5%) provide dynamic power buffering.

4. The multifunctional charging pile system based on a solid-state transformer according to claim 1, characterized in that: The control device is a DSP controller that integrates the following functions: a mixed integer linear programming algorithm is used to optimize energy distribution, with the objective function being to minimize daily operating costs; real-time monitoring of the battery state of charge (SOC), with a charge and discharge efficiency of ≥92% and a cycle life of ≥5,000 times; and voltage / current dual closed-loop control achieved through PI regulation, with a dynamic response time of ≤100ms.

5. The multifunctional charging pile system based on a solid-state transformer according to claim 1, characterized in that: The DC fast charging gun of the charging output module has a rated power of ≥150kW and supports dynamic power allocation (10%-100%); the AC slow charging interface integrates a leakage protection device, with a charging efficiency of ≥95% and a harmonic distortion rate of ≤3%; it is compatible with the CCS charging protocol and has a communication delay of ≤50ms.

6. The multifunctional charging pile system based on a solid-state transformer according to claim 1, characterized in that: The SOC lower limit of the battery in the energy storage module is set to 30%, supporting capacity priority allocation in emergency power supply scenarios; the charging and discharging protocol is matched with the DC solid-state transformer, and the reverse discharge power is ≥ 80% of the rated power.

7. The multifunctional charging pile system based on a solid-state transformer according to claim 1, characterized in that: The control switch group of the single-phase full-bridge inverter and the bridge rectifier in the DC-DC isolation converter is composed of IGBTs, and the trigger pulse frequency is 20kHz; the voltage balancing control accuracy of the high-voltage side DC capacitor and the low-voltage side DC capacitor is ≤±1%.

8. The multifunctional charging pile system based on a solid-state transformer according to claim 1, characterized in that: The driving signal of the fully controlled switch device in the low-voltage DC / DC converter adopts PWM modulation, and the duty cycle dynamic range is 5%-95%; the capacitor adopts a film capacitor with a withstand voltage level of ≥1200V and an equivalent series resistance of ≤10mΩ.

9. The multifunctional charging pile system based on a solid-state transformer according to claim 1, characterized in that: The control device also includes an equipment life prediction model based on an LSTM neural network, with a fault warning accuracy rate of ≥95%; a temperature / humidity sensor monitors environmental parameters in real time, and the over-temperature protection threshold is set at 85°C.

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