Converter architecture and control method, battery pack, and energy storage system

Abstract

The present application provides a converter architecture and control method, a battery pack, and an energy storage system, which realizes the performance optimization of the power conversion system through the integration of a grid-connected relay, a controller, an AC filter circuit, an AC / DC conversion circuit, and a DC / DC conversion circuit. The core innovation lies in the dynamic regulation of the battery voltage by the controller: when the battery voltage is higher than the AC grid voltage by a preset multiple, a step-down operation is performed; otherwise, a step-up operation is performed to ensure that the battery voltage matches the preset AC grid voltage. By introducing an additional DC / DC conversion circuit and dynamically controlling the DC bus voltage, it can support a wide battery voltage input of 200 to 1000V and operate in a high-efficiency mode. It solves the problems of low converter system efficiency and narrow battery voltage adaptation range in the prior art, overcomes the technical limitations of traditional solutions, significantly improves system performance, and reduces switching losses.

Description

Technical Field

[0001] The present application relates to the technical field of energy storage systems and converters, and in particular to a converter architecture and control method, a battery pack, and an energy storage system. Background Art

[0002] With the rapid development of electric vehicles and distributed renewable energy, higher requirements are placed on the performance and flexibility of energy storage systems, which brings more possibilities for research in this field. Currently, a common solution to the deep discharge problem of low-voltage batteries in energy storage systems is to use a primary converter topology.

[0003] The primary converter topology directly connects the high-voltage side to the low-voltage battery and uses the converter's boost function to achieve deep discharge of the low-voltage battery. However, this structure requires the input voltage to be increased to a higher voltage level to meet the needs of the output side, so the battery terminal voltage requirement is relatively high, usually above 600V. This requirement seriously affects the application of retired batteries, heavy truck batteries and other batteries with low voltage in energy storage systems, making it very difficult to achieve deep discharge, thus failing to fully utilize their full capacity and causing a waste of resources.

[0004] In order to solve the deep discharge requirements of low-voltage batteries, simply adding a DC / DC conversion circuit is a feasible solution, but this will reduce the conversion efficiency of the entire energy storage system. This is because each additional conversion circuit will bring a certain amount of power loss, thus affecting the overall performance of the system. Summary of the invention

[0005] In view of the shortcomings of the prior art mentioned above, the purpose of the present application is to provide a converter architecture and control method, a battery pack, and an energy storage system, which are used to solve the problem in the existing converter architecture that the primary converter topology requires the battery terminal voltage to be too high, making it difficult for the low-voltage battery to be deeply discharged.

[0006] To achieve the above-mentioned purpose and other related purposes, the first aspect of the present application provides a converter architecture, the converter comprising a grid-connected relay, a controller, an AC filter circuit, an AC / DC conversion circuit, and a DC / DC conversion circuit; wherein the first end of the grid-connected relay is connected to the AC power grid, and the second end of the grid-connected relay is connected to the first end of the AC filter circuit; the second end of the AC filter is connected to the first end of the AC / DC conversion circuit; the second end of the AC / DC conversion circuit is connected to the first end of the DC / DC conversion circuit; the second end of the DC / DC conversion circuit is connected to a battery; the controller is used to detect the AC grid voltage and the battery voltage; if it is detected that the battery voltage is greater than a preset multiple of the AC grid voltage, the DC / DC conversion circuit is controlled to perform a step-down operation so that the battery voltage is equal to the preset multiple of the AC grid voltage; otherwise, the DC / DC conversion circuit is controlled to perform a step-up operation so that the battery voltage rises to a preset multiple of the AC grid voltage.

[0007] In some embodiments of the first aspect of the present application, the positive circuit of the DC / DC conversion circuit includes a first switch tube; an initial state of the first switch tube is a disconnected state.

[0008] In some embodiments of the first aspect of the present application, the process of the controller controlling the DC / DC conversion circuit to perform a step-down operation includes: if the controller detects that the voltage of the battery is greater than a preset multiple of the AC grid-connected voltage, closing the first switch tube to make the voltage of the battery equal to the preset multiple of the AC grid-connected voltage.

[0009] In some embodiments of the first aspect of the present application, the preset multiple is square root of two times the modulation ratio.

[0010] In some embodiments of the first aspect of the present application, the first switching tube includes: a first triode and a first diode; the base of the first triode is connected to the controller, the collector of the first triode is connected to the cathode of the first diode, and the emitter of the first triode is connected to the anode of the first diode.

[0011] In some embodiments of the first aspect of the present application, the converter includes: the negative circuit of the DC / DC conversion circuit includes a second switch tube; the DC / DC conversion circuit performs the boost operation by controlling the first switch tube and the second switch tube.

[0012] To achieve the above-mentioned purpose and other related purposes, the second aspect of the present application provides a converter control method, including: the converter includes a grid-connected relay, a controller, an AC filter circuit, an AC / DC conversion circuit, and a DC / DC conversion circuit; wherein the first end of the grid-connected relay is connected to the AC grid, and the second end of the grid-connected relay is connected to the first end of the AC filter circuit; the second end of the AC filter is connected to the first end of the AC / DC conversion circuit; the second end of the AC / DC conversion circuit is connected to the first end of the DC / DC conversion circuit; the second end of the DC / DC conversion circuit is connected to a battery; the control method includes: detecting the AC grid voltage and the battery voltage; if it is detected that the battery voltage is greater than a preset multiple of the AC grid voltage, controlling the DC / DC conversion circuit to perform a step-down operation so that the battery voltage is equal to the AC grid voltage; otherwise, controlling the DC / DC conversion circuit to perform a step-up operation so that the battery voltage rises to a preset multiple of the AC grid voltage.

[0013] In some embodiments of the second aspect of the present application, the positive circuit of the DC / DC conversion circuit includes a first switch tube; the initial state of the first switch tube is a disconnected state, and the method includes: if the controller detects that the voltage of the battery is greater than a preset multiple of the AC grid-connected voltage, closing the first switch tube to make the voltage of the battery equal to the preset multiple of the AC grid-connected voltage.

[0014] To achieve the above-mentioned object and other related objects, a third aspect of the present application provides a battery pack, which includes: a plurality of batteries and the converter described in any one of the above items.

[0015] To achieve the above-mentioned purpose and other related purposes, the fourth aspect of the present application provides an energy storage system, including: the above-mentioned battery pack.

[0016] As described above, the converter architecture and control method, battery pack, and energy storage system of the present application have the following beneficial effects: through the innovative converter architecture and control strategy, the problem of reduced system efficiency caused by the introduction of traditional DC / DC conversion circuits is cleverly solved. By dynamically adjusting the DC bus voltage (Ubus), the DC / DC conversion circuit is ensured to always operate in a high-efficiency mode, effectively reducing the power loss caused by the introduction of additional circuits. The solution supports a wide range of battery voltage input of 200 to 1000V, meets the deep discharge requirements of low-voltage batteries, and is suitable for electric vehicles, renewable energy and other fields. Through the intelligent judgment and execution of the boost and buck operations by the controller, the battery voltage and the AC grid voltage are accurately matched to ensure stable operation of the system and efficient energy transmission. Compared with the traditional solution, the present application significantly improves the overall reliability of the converter, reduces switching losses, reduces power losses in the system energy conversion process, and provides a better technical solution for power electronic systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A structural schematic diagram of an embodiment of the converter architecture of the present application is shown.

[0018] Figure 2 A schematic diagram of the structure of an AC filter circuit in an embodiment of the converter architecture of the present application is shown.

[0019] Figure 3 A schematic diagram of the structure of an AC / DC conversion circuit in an embodiment of a converter architecture of the present application is shown.

[0020] Figure 4 A schematic diagram of the structure of a DC / DC conversion circuit in an embodiment of the converter architecture of the present application is shown.

[0021] Figure 5 A flow chart of an embodiment of a converter control method of the present application is shown.

[0022] Figure 6 A flow chart of another embodiment of the converter control method of the present application is shown. DETAILED DESCRIPTION

[0023] The following describes the embodiments of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. The present application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0024] Before further explaining the present application in detail, the nouns and terms involved in the embodiments of the present application are explained. The nouns and terms involved in the embodiments of the present application are subject to the following interpretations:

[0025] <1> Converter: A power electronic device that can convert electrical energy from one form to another. It is usually used for AC / DC power conversion, voltage conversion and frequency regulation. It is widely used in power systems, industrial control and renewable energy fields.

[0026] <2> Grid-connected relay: An electrical switching device with opening and closing functions, specifically used to control the connection and disconnection between the power generation system and the power grid, ensuring that the power generation equipment can be safely and reliably connected to the power grid, and quickly cut off the grid connection under abnormal circumstances.

[0027] <3> AC / DC conversion circuit: A power electronic circuit that converts alternating current into direct current. It typically uses components such as rectifier bridges and filter capacitors to achieve conversion of electrical energy forms through rectification, filtering and other technologies. It is a key component of power supply systems and power electronic equipment.

[0028] <4> DC / DC conversion circuit: A power electronic circuit that can achieve voltage increases or decreases in a DC power system. It uses the on-off control of switching devices and energy storage elements such as inductors and capacitors to accurately adjust the DC voltage. It is widely used in power management, battery charging and discharging, and other fields.

[0029] <5> Modulation ratio: In pulse width modulation (PWM) technology, it refers to the ratio of the on-time of the switching device to the switching period. It is a key parameter for controlling the output voltage amplitude and power conversion efficiency.

[0030] <6> AC grid-connected voltage: The AC voltage connected to the grid in a grid-connected power generation system usually needs to meet technical standards such as the amplitude, frequency and waveform of the grid voltage to ensure that the power generation equipment is safely and stably connected to the grid.

[0031] <7> Switching tube: A semiconductor device that can quickly disconnect and conduct current, including MOSFET, IGBT, etc. It is used for power conversion and control in power electronic systems and has the characteristics of high switching speed and low conduction loss.

[0032] <8> DClink capacitor: A large-capacity energy storage capacitor in a DC bus circuit, used to smooth DC voltage, suppress voltage fluctuations and store electrical energy. It is a key passive component in converters and power electronics systems.

[0033] <9> PWM (Pulse Width Modulation) signal: Pulse width modulation signal, which controls the on and off time of switching devices by changing the pulse width to achieve voltage regulation, energy conversion and signal processing. An important modulation technology.

[0034] <10> IGBT (Insulated Gate Bipolar Transistor): An insulated gate bipolar transistor that combines the control characteristics of a MOSFET with the high current handling capabilities of a bipolar transistor. It is one of the most commonly used power switching devices in modern power electronics systems.

[0035] <11> NPN transistor: A basic semiconductor amplifier device consisting of two PN junctions, with amplification and switching functions, widely used in analog and digital circuits.

[0036] <12> Diode: A semiconductor device that allows current to pass in only one direction. It has unidirectional conductivity and is widely used in circuits such as rectification, limiting and switching.

[0037] <13> Inverter: A power electronic device that converts DC power into AC power. It achieves energy conversion from DC to AC power through high-frequency switching and PWM control of switching devices. It is a key component of solar power generation, electric vehicles and uninterruptible power supply systems.

[0038] To facilitate understanding of the embodiments of the present application, first Figure 1 Detailed description. Figure 1 The structure diagram of a converter architecture in an embodiment of the present application is shown. The converter architecture in this embodiment mainly includes the following parts:

[0039] The converter includes a grid-connected relay 100, a controller 101, an AC filter circuit 105, an AC / DC conversion circuit 106, and a DC / DC conversion circuit 107; wherein a first end of the grid-connected relay is connected to an AC power grid, a second end of the grid-connected relay is connected to a first end of the AC filter circuit; a second end of the AC filter is connected to a first end of the AC / DC conversion circuit; a second end of the AC / DC conversion circuit is connected to a first end of the DC / DC conversion circuit; and a second end of the DC / DC conversion circuit is connected to a battery.

[0040] The controller is used to detect the AC grid voltage and the voltage of the battery; if it is detected that the voltage of the battery is greater than a preset multiple of the AC grid voltage, the DC / DC conversion circuit is controlled to perform a step-down operation so that the voltage of the battery is equal to the preset multiple of the AC grid voltage; otherwise, the DC / DC conversion circuit is controlled to perform a step-up operation so that the voltage of the battery rises to a preset multiple of the AC grid voltage.

[0041] In one embodiment of the present application, the input terminals of the grid-connected relay are marked as A, B, C, and N, which correspond to the A, B, and C phases of the three-phase alternating current and the neutral line N, respectively. a , L a ',L b , L b ',L c , L c 'Connected to the subsequent AC filter circuit. The connection between each phase is flexibly controlled by the control circuit to switch the state, ensuring efficient bidirectional flow of electric energy between the converter and the grid. The grid-connected relay is composed of IGBT modules or relays, and its state transition is determined by the drive signal (U a , U b , U c , U n ) Real-time control, U a , U b , U c Corresponding to A, B, C three phases, U n Corresponding to the neutral line. By adjusting the on and off of the IGBT through the PWM (pulse width modulation) signal, it can achieve synchronous access and separation with the power grid, avoiding surge current and interference with the power grid. a , L a ',L b , L b ',L c , L c 'Monitor and measure the incoming and outgoing lines of each phase separately, and realize the transmission switching and safe isolation of electric energy by switching the connection mode of windings or inductors.

[0042] In one embodiment of the present application, the AC filter circuit is as follows: Figure 2 As shown, its input terminal consists of A0, B0, C0, and N0, corresponding to the L of the grid-connected relay. a , L b , L cand N. Each phase output is connected to an inductor to filter out high-frequency harmonics and reduce noise interference in the power grid, thereby ensuring the stability of the input current of the subsequent AC / DC conversion. The filter circuit adopts an L-type or LC-type architecture: each phase input (A0, B0, C0) is connected to the inductor (corresponding to the p common mode and parallel inductor structure), and N0 is connected to the neutral ground through a neutral inductor or a neutral inductor. The setting of the inductance value depends on the current load and the power grid interference frequency. After filtering, the voltage at the output end is adjusted to a relatively smooth three-phase AC power and enters the next stage AC / DC converter.

[0043] In one embodiment of the present application, the topology diagram of the AC / DC conversion circuit is as follows: Figure 3 As shown, a three-phase full-bridge structure is adopted, and each phase consists of two IGBTs and corresponding freewheeling diodes. A, B, C and N are connected from the input end of the AC filter circuit and connected to the S of the conversion circuit. a , S b , S c , S n The AC / DC conversion circuit includes the following signal processing steps: S a , S b , S c and S n The upper and lower arms of the rectifier are turned on alternately, and the freewheeling diode is used to rectify the voltage. After pulse width modulation, the three-phase AC power is converted into DC power. DC smoothing: After the output current passes through the filter capacitor (DClink capacitor), it is smoothed into DC power and output to DCBUS+ and DCBUS-. The control signal and topology controller generate S through PWM a , S b , S c The switching signal is used to control the on and off of the upper and lower IGBTs to ensure the stability of the DC output voltage. The Sn branch is used to balance the zero-sequence signal and compensate for the unbalanced component of the current. It also helps to maintain the three-phase symmetry, thereby achieving a high-power and high-efficiency rectification process and meeting the stability requirements of the DC bus voltage. Finally, the DC-processed grid-connected voltages DCBUS+ and DCBUS- are output, which is the AC grid-connected voltage U in this embodiment. 交流 .

[0044] In this embodiment, the controller 104 is directly connected to the grid-connected relay 100 through control signals Ua, Ub, Uc, and Un, and is responsible for controlling the connection and disconnection of the three-phase power supply A phase, B phase, C phase, and neutral line N of the power grid, thereby ensuring the safe connection of the power grid. Through the grid-connected relay, the three-phase power supply and neutral line signals converge to the AC filter circuit 103, which uses inductance to process the input AC current, filters out high-frequency interference, and provides a stable input signal for the subsequent AC / DC conversion circuit 105. The controller uses the AC grid voltage U busMonitor the output state of the AC filter circuit and accurately control the rectification process of the AC / DC conversion circuit to achieve effective conversion of AC power through IGBT full-bridge rectification. The DC / DC conversion circuit 107 is connected to the controller and samples the signal U bat and I dc The DC output voltage and current are monitored in real time, and the controller dynamically adjusts the operating state of the DC / DC circuit according to these feedback information to ensure that a stable DC power supply is supplied to the battery 110. In addition, the pre-charging circuit 109 is connected to the controller, and the controller detects the voltage across the resistor 111 to determine the pre-charging state and control the circuit to be turned on or off to ensure that the bus voltage is appropriate before charging is allowed. Overall, the controller plays an integrating and coordinating role in the entire system, ensuring that each module works together to achieve efficient management and conversion of electrical energy.

[0045] Through the grid-connected relay, AC filter circuit and AC / DC conversion circuit structure in the above embodiment, the process of converting the current of the AC power grid into DC direct current is realized. Specifically, the grid-connected relay connects the three-phase power supply (phase A, phase B, phase C) and the neutral line (N) of the power grid to the AC filter circuit, and the switching and protection are completed by the control signals (Ua, Ub, Uc, Un) to ensure the safety and stability of the system. In the AC filter circuit, the A0, B0, C0 and N0 signals are filtered by inductance, thereby providing a smooth voltage for the subsequent circuit to reduce fluctuations and interference. Subsequently, the AC / DC conversion circuit adopts an insulated gate bipolar transistor (IGBT) full-bridge structure to accurately control the rectification process, convert AC power into DC power, and smooth the output DC voltage through a filter capacitor. The output voltage is connected to a controller, which is used to monitor the output DC voltage in real time to ensure that it is within a set range, thereby achieving the AC grid-connected voltage U 交流 In this way, the current in the AC grid is accurately and stably converted into the required DC current, providing a reliable power supply for subsequent loads.

[0046] It should be noted that Figure 2 The AC filter circuit shown, Figure 3 The AC / DC conversion circuit shown and Figure 4The DC / DC circuits shown all adopt a two-level converter topology, and a three-level topology may also be used. The present application itself does not limit the structure of the grid-connected relay, AC filter circuit, AC / DC conversion circuit, and DC / DC conversion circuit. The core of the present application is to provide a converter architecture and a control method thereof, and dynamically adjust the Buck-Boost voltage at the DCBUS end by monitoring the battery voltage and the grid-connected voltage on the AC side, so that the switch tube of the DC / DC conversion circuit is always kept in the on state, thereby reducing switching losses and improving system efficiency. Therefore, the converter architecture proposed in the present application can simultaneously support a wide range of battery voltage inputs and achieve high system efficiency close to that of the primary topology.

[0047] In one embodiment of the present application, the converter includes: the positive circuit of the DC / DC conversion circuit includes a first switch tube; the initial state of the first switch tube is a disconnected state.

[0048] In this embodiment, the first switch tube is used to control the conduction and cut-off states to achieve the power conversion function. Figure 4 As shown, the first switch tube is composed of a transistor and a diode. The transistor (Q1) is directly connected to the controller, and its base is used as the control terminal to realize the conduction and shutdown of the transistor through an external signal; the diode (D1) is configured in the collector-emitter loop of the transistor for freewheeling protection and reverse current control. Its working principle includes a transistor part and a diode part. Among them, when the transistor part is working, when the base voltage is higher than the critical value required by the emitter (usually about 0.6V), the transistor enters the saturation region, and the current flows from the collector to the emitter; when the base voltage is lower than the critical value, the transistor is cut off and the circuit is disconnected. Diode part: used to prevent the reverse current of the load from affecting the transistor and the battery.

[0049] In one embodiment of the present application, the process of the controller controlling the DC / DC conversion circuit to perform a step-down operation includes: if the controller detects that the voltage of the battery is greater than a preset multiple of the AC grid-connected voltage, closing the first switch tube to make the voltage of the battery equal to the preset multiple of the AC grid-connected voltage.

[0050] In this embodiment, when the battery starts to discharge, the current flows from BAT+ through the pre-charging circuit and the DC filter circuit, the first transistor Q1 in the first switch tube is in the off state, the current flows in from the anode of the first diode, flows out from the cathode of the first diode, and finally flows to DCBUS+. The negative current flows in from DCBUS- and flows directly to BAT- through the DC Hall of the controller.

[0051] Furthermore, when the battery terminal voltage U bat Higher than When the DC / DC converter enters the step-down mode, the battery voltage is reduced to a voltage that meets the grid connection requirements, that is, the battery terminal voltage U bat Approximately When the first transistor Q1 is turned on, the battery voltage directly drives the load, and the voltage at the DCBUS+ terminal is approximately equal to the voltage at the BAT+ terminal. The β modulation ratio represents the voltage boost factor required by the inverter to convert DC power into AC power. The selection of the modulation ratio is closely related to the working mode and output requirements of the inverter, ensuring that the inverter can operate stably under given AC voltage conditions. When the battery terminal voltage U bat Approximately At the same time, it can ensure that the inverter has optimized power conversion efficiency under different load conditions, meet the grid-connected voltage specifications, and achieve dynamic balance of power flow and safe and stable operation of the system.

[0052] In an embodiment of the present application, the preset multiple is square root of two times the modulation ratio.

[0053] In this embodiment, the preset multiple is selected as Multiplying by the modulation ratio is mainly to ensure that the inverter can effectively convert the DC voltage into the required AC voltage. In the inverter grid-connected operation, the effective value (RMS voltage) of the AC power is U 交流 , and the DC voltage U bat Must reach Because there is such a relationship between the RMS value of the AC voltage and the instantaneous DC voltage. At the same time, the modulation ratio β is the voltage boost factor required by the inverter under current fluctuations, which affects the final output voltage. Therefore, by setting the preset multiple to This ensures that the inverter meets the grid voltage requirements while avoiding losses caused by voltage mismatch, thus improving system efficiency and stability. This design choice provides the inverter with the necessary voltage support, ensuring that it can operate efficiently under various working conditions.

[0054] In one embodiment of the present application, the first switching tube includes: a first triode and a first diode; the base of the first triode is connected to the controller, the collector of the first triode is connected to the cathode of the first diode, and the emitter of the first triode is connected to the anode of the first diode.

[0055] In this embodiment, Figure 4The schematic diagram of the structure of the DC / DC conversion circuit in this embodiment is shown. The first transistor acts as the main switch, and its base is connected to the controller, which can adjust the current according to the instructions of the controller. When the controller sends a signal, the transistor can quickly switch the state to complete the conduction or cutoff of the current. The first diode provides a unidirectional conductive function, so that the current can flow smoothly to the load when the transistor is turned on, and when the current direction changes, the diode prevents the current from flowing back and protects the circuit. This configuration helps to achieve efficient transmission of electrical energy and reduce the power consumption of the system in high-frequency switching applications.

[0056] In this process, the controller is responsible for managing the step-down operation of the DC / DC conversion circuit. Specifically, when the controller detects that the battery voltage is greater than the preset multiple of the AC grid voltage, the first switch tube will be closed. This ensures that the battery voltage is adjusted to a preset multiple of the AC grid voltage, thereby achieving stable energy conversion and transmission. This closing mechanism not only optimizes the utilization efficiency of electrical energy, but also enhances the overall stability of the converter architecture.

[0057] In one embodiment of the present application, the negative electrode circuit of the DC / DC conversion circuit includes a second switch tube; the DC / DC conversion circuit performs the boost operation by controlling the first switch tube and the second switch tube.

[0058] In this embodiment, the first switch tube is composed of a first triode (Q1) and a first diode (D1), and is connected to the positive electrode part of the circuit. The first triode serves as the main switch, and its base is connected to the controller, and the rapid switching of the current is realized through the signal sent by the controller. This design enables the circuit to flexibly adjust the input voltage to meet the boost demand. The second switch tube is composed of a second triode (Q2) and a second diode (D2), and as a negative switch, it works in conjunction with the first switch tube and is responsible for controlling the flow of current in the negative path. Its design ensures that during the boost operation, the circuit can effectively adjust the current flow direction, thereby realizing efficient energy conversion.

[0059] Specifically, when the battery terminal voltage U bat Lower than When the controller uses precise PWM (pulse width modulation) drive signals to coordinately control the switching tubes Q1 and Q2 in the DC / DC conversion circuit to work alternately. By precisely adjusting the on and off states of Q1 and Q2, inductive energy storage and energy conversion are achieved, so that the battery voltage U bat Under the action of the inductor UL, the voltage is boosted to √2βU AC, ensuring that the voltage after inversion accurately matches the grid-connected voltage requirement.

[0060] Furthermore, during the boost operation, the controller achieves voltage boost by precisely coordinating the switching timing of the first switch tube (Q1) and the second switch tube (Q2), and the specific process includes two stages: energy storage and energy release. In the energy storage stage, when the controller detects that the input voltage is lower than the target output voltage, the second switch tube (Q2) is first turned off to ensure that the negative circuit is disconnected, and the first switch tube (Q1) is turned on at the same time, so that its base obtains a driving signal, and the current forms a conduction loop through the first transistor (Q1) and the first diode (D1), and stores electric energy in the form of a magnetic field in the inductor. At this time, the inductor current shows a linear upward trend; in the energy release stage, after the preset PWM (pulse width modulation) cycle arrives, the controller turns off the first switch tube (Q1) to cut off the positive circuit, and turns on the second switch tube (Q2) to establish a negative circuit. The magnetic field energy stored in the inductor is released through the second transistor (Q2) and the second diode (D2). At this time, the inductor current is superimposed in series with the input power supply current to form a higher output voltage, and the inductor current shows a linear downward trend.

[0061] In this embodiment, the controller achieves precise voltage regulation through closed-loop control, samples the input voltage, output voltage and inductor current in real time, dynamically calculates the required PWM duty cycle based on the sampled data, adjusts the on-time ratio of the switch tube, and ensures that the output voltage is stable at the target value.

[0062] To further improve efficiency, the controller uses a variety of optimization algorithms, including current mode control to limit peak current, soft switching technology to reduce switching losses, dead time control to avoid shoot-through, and adaptively adjusts control parameters according to load changes, while optimizing dynamic response through predictive control algorithms. To ensure the safety and stability of the system, the circuit is designed with a complete protection mechanism, including overvoltage protection to prevent excessive output voltage, overcurrent protection to limit excessive current, undervoltage lockout to prevent abnormal operation, temperature monitoring to prevent overheating and damage of the switch tube, and soft start function to reduce current shock during startup.

[0063] Preferably, the controller can also optimize the switching frequency to balance the loss and the volume of the magnetic components, use synchronous rectification technology to reduce the diode loss, dynamically adjust the dead time to optimize the efficiency, and realize load adaptive regulation to maintain a high efficiency range. Through the above-mentioned sophisticated control strategy and protection mechanism, the DC / DC conversion circuit can operate stably and reliably under various working conditions and realize efficient voltage boosting function. The controller continuously optimizes the system performance based on real-time monitoring data to ensure that the circuit maintains the best working state under different load conditions, while ensuring the safety and reliability of the system, so that it can play the maximum performance in practical applications.

[0064] In one embodiment of the present application, the converter architecture includes a DC filter circuit and a pre-charge circuit. The DC filter circuit is arranged inside the DC / DC converter circuit, the first end of the DC filter circuit is connected to the first switch tube and the second switch tube, and the second end is connected to the pre-charge circuit and the DC Hall. The DC Hall in this embodiment is used to measure the current output of the DC / DC converter circuit, and the Hall sensor measures the current by detecting the magnetic field generated by the current in the conductor. This method is suitable for high current applications and avoids inserting the measuring device directly into the circuit.

[0065] In this embodiment, the function of the DC filter circuit is to smooth the DC bus (DCBUS) voltage, eliminate the high-frequency ripple caused by the switching action, and provide a stable DC voltage for the output. The circuit is composed of an inductor and a capacitor, which respectively realize filtering and energy storage. Its connection structure is as follows: the input end is connected to the positive and negative poles of the DC bus (DCBUS+ and DCBUS-), connected to the filter capacitor after the filter inductor, and finally connected to the load (such as a battery). During operation, the filter inductor suppresses the peak and interference of the high-frequency current, and the filter capacitor smoothes the voltage fluctuations by charging and discharging to ensure the stability of the DC voltage at the output end. Diodes D1 and D2 are used to limit the current direction to prevent the current backflow from causing damage to the device. On the whole, the DC filter circuit improves the voltage quality of the system and protects the load equipment and battery.

[0066] In the present embodiment, the role of the pre-charge circuit is to protect the DC filter circuit and the battery, to prevent the high instantaneous current impact caused by the excessive bus capacitance during startup, and to damage the device. The pre-charge circuit is realized by connecting the pre-charge resistor, the reverse diode and the switch element. Its working process is as follows: when the system starts, the pre-charge resistor is connected in series between the DC bus and the battery, limits the initial charging current, and gradually charges the filter capacitor and the battery to avoid instantaneous current impact. The diode direction is a reverse design to ensure that the current after the main switch is closed will not flow back to the pre-charge resistor, protecting the safety of the circuit. When pre-charging is completed (the bus voltage is close to the target value), the controller triggers the DC output control relay to close, and the loop bypasses the pre-charge resistor, enters the normal charging process, and improves the system efficiency.

[0067] Furthermore, the pre-charge circuit is connected to the battery terminal through a DC fuse. It is used for overcurrent protection. When the current exceeds the safety threshold, the fuse inside the fuse melts due to heat, thereby quickly cutting off the current and preventing damage to circuit components. This feature not only prevents equipment damage caused by overload or short circuit, but also helps reduce the risk of fire. At the same time, the fuse can effectively protect the battery and connected equipment, ensure their normal operation, and provide safety isolation to prevent faults from affecting downstream equipment.

[0068] To facilitate understanding of the embodiments of the present application, first Figure 5Detailed description: A flow chart of a converter control method in an embodiment of the present application is shown.

[0069] The converter includes a grid-connected relay, a controller, an AC filter circuit, an AC / DC conversion circuit, and a DC / DC conversion circuit; wherein the first end of the grid-connected relay is connected to the AC power grid, and the second end of the grid-connected relay is connected to the first end of the AC filter circuit; the second end of the AC filter is connected to the first end of the AC / DC conversion circuit; the second end of the AC / DC conversion circuit is connected to the first end of the DC / DC conversion circuit; and the second end of the DC / DC conversion circuit is connected to a battery.

[0070] The converter control method in this embodiment mainly includes the following steps:

[0071] Step S51: detecting the AC grid voltage and the battery voltage.

[0072] Step S52: If it is detected that the voltage of the battery is greater than a preset multiple of the AC grid-connected voltage, the DC / DC conversion circuit is controlled to perform a step-down operation so that the voltage of the battery is equal to the AC grid-connected voltage.

[0073] Step S53: otherwise, controlling the DC / DC conversion circuit to perform a boost operation so that the voltage of the battery rises to a preset multiple of the AC grid-connected voltage.

[0074] In one embodiment of the present application, the positive circuit of the DC / DC conversion circuit includes a first switch tube; the initial state of the first switch tube is a disconnected state, and the method includes: if the controller detects that the voltage of the battery is greater than a preset multiple of the AC grid-connected voltage, closing the first switch tube to make the voltage of the battery equal to the preset multiple of the AC grid-connected voltage.

[0075] Figure 6 The converter control method in another embodiment of the present application is shown. After preparing for discharge, the converter is initialized. The battery voltage and the grid voltage are read by the controller. If the battery voltage is greater than the grid voltage multiplied by the square root of two times the modulation ratio, the first switch tube is turned on to make the battery voltage equal to the square root of two times the modulation ratio times the grid voltage (the modulation ratio is 0 to 1.1), and then the AC / DC conversion circuit performs subsequent operations, wherein the inverter current U 交流 The range is 360V to 440V; otherwise, the DC / DC conversion circuit is controlled to work so that the battery voltage is equal to the square root of two times the modulation ratio times the grid voltage.

[0076] The initialization process of the converter includes hardware self-check, parameter configuration, communication establishment, state initialization, control system preparation, safety check and system startup. These steps ensure that all hardware components work properly and are interconnected, and configure the corresponding operating parameters and control algorithms so that they can perform tasks efficiently during operation. Through initialization, the system can self-check, confirm that there are no faults, and prepare for various operating states to ensure safety and reliability after startup, thereby avoiding potential damage or instability factors that affect the normal operation of the equipment.

[0077] In the embodiments of the present application, words such as "first" and "second" are used to distinguish the same or similar items with basically the same functions and effects. For example, the first switch tube and the second switch tube are only used to distinguish different switch tubes, and their order is not limited. Those skilled in the art can understand that words such as "first" and "second" do not limit the quantity and execution order, and words such as "first" and "second" do not necessarily limit them to be different.

[0078] It should be noted that in the embodiments of the present application, words such as "exemplary" or "for example" represent examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0079] In the embodiments of the present application, "at least one" refers to one or more, and "plurality" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b or c can represent: a, b, c, ab, ac, bc or abc, where a, b, c can be single or multiple.

[0080] One embodiment of the present application includes a battery pack, which includes: a plurality of batteries and the above-mentioned converter. The converter architecture of the present invention achieves precise control of the battery pack voltage by integrating a dedicated DC / DC conversion circuit in the battery pack. The design uses a controller to dynamically monitor the battery voltage. When the battery voltage is higher or lower than the preset AC grid voltage, it can automatically perform step-up and step-down operations to ensure that the battery pack operates safely and efficiently within a wide voltage range of 200 to 1000V. At the same time, the converter architecture also has a built-in battery pack voltage balancing and real-time monitoring module, which can effectively reduce the voltage difference between battery cells and extend the service life of the battery pack.

[0081] An energy storage system is included in one embodiment of the present application, and the system includes: the above-mentioned battery pack. In the energy storage system, the converter architecture of the present invention realizes voltage matching and energy conversion of multiple power sources by introducing an intelligent voltage conversion module. The system can dynamically adjust the DC bus voltage according to different power supply characteristics and load requirements, and support the flexible interconnection of distributed power sources, renewable energy and grid power sources while ensuring power conversion efficiency. The control strategy of the converter can adaptively handle complex power conversion scenarios and provide a more stable and reliable power management solution for the energy storage system.

[0082] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

[0083] In summary, the present application provides a converter architecture and control method, a battery pack, and an energy storage system. The present application provides a converter architecture that improves grid-connected efficiency. The performance optimization of the power conversion system is achieved through the integration of grid-connected relays, controllers, AC filter circuits, AC / DC conversion circuits, and DC / DC conversion circuits. The core innovation lies in the dynamic regulation of the battery voltage by the controller: when the battery voltage is higher than the preset multiple of the AC grid voltage, a step-down operation is performed; otherwise, a step-up operation is performed to ensure that the battery voltage matches the preset AC grid voltage. By introducing an additional DC / DC conversion circuit and dynamically controlling the DC bus voltage, a wide battery voltage input of 200 to 1000V can be supported and operated in a high-efficiency mode. It solves the problems of low converter system efficiency and narrow battery voltage adaptation range in the prior art, overcomes the technical limitations of traditional solutions, significantly improves system performance, significantly reduces switching losses, and is particularly suitable for the deep discharge requirements of low-voltage batteries. Therefore, the present application effectively overcomes the various shortcomings of the prior art and has a high industrial utilization value.

[0084] The above embodiments are merely illustrative of the principles and effects of the present application and are not intended to limit the present application. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed in the present application shall still be covered by the claims of the present application.

Claims

1. A converter architecture, characterized in that: The converter includes a grid-connected relay, a controller, an AC filter circuit, an AC / DC conversion circuit, and a DC / DC conversion circuit; wherein the first end of the grid-connected relay is connected to the AC grid, the second end of the grid-connected relay is connected to the first end of the AC filter circuit; the second end of the AC filter is connected to the first end of the AC / DC conversion circuit; the second end of the AC / DC conversion circuit is connected to the first end of the DC / DC conversion circuit; and the second end of the DC / DC conversion circuit is connected to a battery; The controller is used to detect the AC grid voltage and the voltage of the battery; if it is detected that the voltage of the battery is greater than a preset multiple of the AC grid voltage, the DC / DC conversion circuit is controlled to perform a step-down operation so that the voltage of the battery is equal to the preset multiple of the AC grid voltage; otherwise, the DC / DC conversion circuit is controlled to perform a step-up operation so that the voltage of the battery rises to a preset multiple of the AC grid voltage.

2. The converter architecture according to claim 1, characterized in that: The converter includes: the positive circuit of the DC / DC conversion circuit includes a first switch tube; the initial state of the first switch tube is a disconnected state.

3. The converter architecture according to claim 2, characterized in that: The process of the controller controlling the DC / DC conversion circuit to perform a step-down operation includes: if the controller detects that the voltage of the battery is greater than a preset multiple of the AC grid-connected voltage, closing the first switch tube to make the voltage of the battery equal to the preset multiple of the AC grid-connected voltage.

4. The converter architecture according to claim 3, characterized in that: The preset multiple is the square root of two times the modulation ratio.

5. The converter architecture according to claim 2, characterized in that: The first switch tube includes: a first triode and a first diode; the base of the first triode is connected to the controller, the collector of the first triode is connected to the cathode of the first diode, and the emitter of the first triode is connected to the anode of the first diode.

6. The converter architecture according to claim 2, characterized in that: The converter includes: the negative pole circuit of the DC / DC conversion circuit includes a second switch tube; the DC / DC conversion circuit performs the boost operation by controlling the first switch tube and the second switch tube.

7. A converter control method, characterized in that: include: The converter includes a grid-connected relay, a controller, an AC filter circuit, an AC / DC conversion circuit, and a DC / DC conversion circuit; wherein the first end of the grid-connected relay is connected to the AC grid, the second end of the grid-connected relay is connected to the first end of the AC filter circuit; the second end of the AC filter is connected to the first end of the AC / DC conversion circuit; the second end of the AC / DC conversion circuit is connected to the first end of the DC / DC conversion circuit; and the second end of the DC / DC conversion circuit is connected to a battery; The control method comprises: Detecting the AC grid voltage and the voltage of the battery; if it is detected that the voltage of the battery is greater than a preset multiple of the AC grid voltage, controlling the DC / DC conversion circuit to perform a step-down operation so that the voltage of the battery is equal to the AC grid voltage; otherwise, controlling the DC / DC conversion circuit to perform a step-up operation so that the voltage of the battery rises to a preset multiple of the AC grid voltage.

8. The converter control method according to claim 7, characterized in that: The positive circuit of the DC / DC conversion circuit includes a first switch tube; the initial state of the first switch tube is a disconnected state, and the method includes: If the controller detects that the voltage of the battery is greater than a preset multiple of the AC grid-connected voltage, the first switch tube is closed to make the voltage of the battery equal to the preset multiple of the AC grid-connected voltage.

9. A battery pack, characterized in that: The battery pack comprises: a plurality of batteries and the converter according to any one of claims 1 to 6.

10. An energy storage system, characterized in that: include: The battery pack as claimed in claim 9.

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