A high-voltage box applicable to a sodium-ion energy storage system, a sodium-ion energy storage system and a control method

Abstract

The present application provides a high-voltage box, a sodium-ion energy storage system and a control method applicable to a sodium-ion energy storage system, including: a soft start circuit, a filter circuit, a main control BCM and a switching circuit; the filter circuit is connected to an external energy storage PCS; the filter circuit is connected to the soft start circuit; the soft start circuit and the filter circuit are respectively connected to the first positive terminal and the first negative terminal of the switching circuit; the switching circuit is provided with a second positive terminal and a second negative terminal respectively for connecting to the positive and negative terminals of an external sodium-ion battery PACK1; the switching circuit is provided with a third positive terminal and a third negative terminal respectively for connecting to the positive and negative terminals of an external sodium-ion battery PACK2; the main control BCM is respectively connected to the soft start circuit, the filter circuit and the switching circuit, and controls the external sodium-ion battery PACK1 and the external sodium-ion battery PACK2 to suppress current and voltage mutations when switching between series and parallel states through the switching circuit, so as to avoid the impact on the external energy storage PCS during the switching process.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage, and particularly relates to a high-voltage box applicable to a sodium-ion energy storage system, a sodium-ion energy storage system and a control method thereof. Background Art

[0002] At present, due to the advantages of rich resources, low price and easy availability of sodium, major battery manufacturers are vigorously developing sodium-ion battery technology. With the maturity of sodium-ion battery technology and its gradual industrialization, it is expected that sodium-ion batteries can be used for large-scale energy storage in the next few years.

[0003] Sodium-ion batteries mainly work by the movement of sodium ions between the positive electrode and the negative electrode. Similar to the working principle of lithium-ion batteries, both are called "rocking chair" batteries. However, the positive electrode material of sodium-ion batteries usually has a relatively high voltage, which can reach 4V, while the voltage of the negative electrode material is relatively low, usually between 0.01V and 1V. The battery voltage window range is relatively wide. The single-cell voltage of sodium-ion batteries within the full SOC (state of charge / remaining charge level) ranges from 1.5V to 4V, and the voltage window range is 2.17 times that of lithium-ion batteries with a range of 2.5V to 3.65V. Existing energy storage PCSs (power conversion systems) are not suitable for sodium-ion energy storage systems with a wide voltage window range. The common solution is to configure a DCDC converter for DC voltage conversion or use a higher-voltage power device energy storage PCS for adaptation. The DC-DC converter divides the input voltage into several pulse periods and uses a switching tube to control the duty cycle of these pulse periods to achieve the transfer of electrical energy and the rise and fall of voltage. This pulse width modulation (PWM) technology is the core of the DC-DC converter. By controlling the conduction time of the switching tube, the output voltage is adjusted to achieve stable voltage output. However, this method requires maintaining the pulse width modulation of the switching tube and the electromagnetic conversion operation of the transformer (or inductor coil) during use, increasing the system consumption and reducing the system efficiency. Using an energy storage PCS with higher-voltage power devices will result in a large number of energy storage PCSs being replaced, resulting in a relatively high system conversion cost.

[0004] In view of this, there is a need for a high-voltage box applicable to a sodium-ion energy storage system, a sodium-ion energy storage system and a control method thereof. Summary of the Invention

[0005] Aiming at the problems of high conversion cost when replacing an external energy storage PCS or reducing the system efficiency by adding a DCDC converter in the prior art, the present invention provides a high-voltage box applicable to a sodium-ion energy storage system, a sodium-ion energy storage system and a control method thereof, which can not only avoid replacing the existing external energy storage PCS, but also avoid the problem of system efficiency reduction. The specific technical solutions are as follows:

[0006] A high-voltage box applicable to a sodium-ion energy storage system, comprising: a soft start circuit, a filtering circuit, a Hall sensor, a voltage sensor, a main control BCM, and a switching circuit; the first positive terminal of the filtering circuit is connected to the positive terminal of an external energy storage PCS; the first negative terminal of the filtering circuit is connected to the negative terminal of the external energy storage PCS; the second positive terminal of the filtering circuit is connected to the first end of the soft start circuit; the second end of the soft start circuit and the second negative terminal of the filtering circuit are respectively connected to the first positive terminal and the first negative terminal of the switching circuit; the Hall sensor is connected in series between the second negative terminal of the filtering circuit and the first negative terminal of the switching circuit; the switching circuit further has a second positive terminal and a second negative terminal; the second positive terminal of the switching circuit is connected to the positive end of an external sodium-ion battery PACK1; the second negative terminal of the switching circuit is connected to the negative end of the external sodium-ion battery PACK1; the switching circuit further has a third positive terminal and a third negative terminal; the third positive terminal of the switching circuit is connected to the positive end of an external sodium-ion battery PACK2; the third negative terminal of the switching circuit is connected to the negative end of the external sodium-ion battery PACK2; the voltage sensor is arranged between the first positive terminal and the first negative terminal of the switching circuit and is connected to the main control BCM; the main control BCM is respectively connected to the soft start circuit, the filtering circuit, the Hall sensor, and the switching circuit to control the switching circuit to switch the external sodium-ion battery PACK1 and the external sodium-ion battery PACK2 between a parallel state and a series state, and at the same time adjust the filtering ability level of the filtering circuit according to the change of the series-parallel connection state between the external sodium-ion battery PACK1 and the external sodium-ion battery PACK2, so as to suppress the current and voltage mutations generated by the switching of the external sodium-ion battery in different states due to the series-parallel connection method, smooth the current and voltage mutations, and avoid the impact on the external energy storage PCS during the switching process.

[0007] Further, the switching circuit includes a switch DCSSR1, a switch DCSSR2, and a switch DCSSR3; the first positive terminal of the switching circuit is directly led out as the second positive terminal of the switching circuit; the first positive terminal of the switching circuit is connected in series with the switch DCSSR3 and then used as the third positive terminal of the switching circuit; the first negative terminal of the switching circuit is directly led out as the third negative terminal of the switching circuit; the first negative terminal of the switching circuit is connected in series with the switch DCSSR2 and then used as the second negative terminal of the switching circuit; the switch DCSSR1 is connected in series between the second negative terminal of the switching circuit and the third positive terminal of the switching circuit; the main control BCM is connected to the switch DCSSR1, the switch DCSSR2, and the switch DCSSR3 to control the on-off states of the switches.

[0008] Further, the switch circuit further includes a NOT gate N1; the input end of the NOT gate N1 is connected to the control ends of the switches DCSSR2 and DCSSR3; the input end of the NOT gate N1 is connected to the main control BCM; the output end of the NOT gate N1 is connected to the control end of the switch DCSSR1.

[0009] Further, the filter circuit includes a first LC circuit and a second LC circuit; the first LC circuit and the second LC circuit are connected in parallel.

[0010] Further, the first LC circuit includes a switch K11, a switch K12, an inductor L1 and a capacitor C1; the second LC circuit includes a switch K21, a switch K22, an inductor L2 and a capacitor C2; the first end of the switch K11 is connected to the first ends of the switch K12 and the inductor L1; the second end of the switch K12 is connected to the first end of the capacitor C1; the first end of the switch K21 is connected to the first ends of the switch K22 and the inductor L2; the second end of the switch K22 is connected to the first end of the capacitor C2; the second end of the switch K11 is connected to the second end of the switch K21, and the connection point serves as the first positive terminal of the filter circuit; the second ends of the inductor L1 and the inductor L2 are connected, and the connection point serves as the second positive terminal of the filter circuit; the second ends of the capacitor C1 and the capacitor C2 are connected, the second end of the capacitor C1 serves as the first negative terminal of the filter circuit, and the second end of the capacitor C2 serves as the second negative terminal of the filter circuit; the main control BCM is connected to the switches K11, K12, K21 and K22 to control the filtering ability level state of the filter circuit.

[0011] Further, the soft start circuit includes a relay K31, a relay K32 and a resistor R31; the first end of the relay K31 is connected to the first end of the resistor R31; the second end of the relay K31 is connected to the first end of the relay K32, and the connection point serves as the first end of the soft start circuit; the second end of the resistor R31 is connected to the second end of the relay K32, and the connection point serves as the second end of the soft start circuit; the soft start circuit is used to connect the relay K31 and the resistor R31 in advance for pre-charging before officially turning on the relay K32 of the main path to prevent excessive impact on the external sodium ion battery.

[0012] Further, it further includes a first linkage circuit; the first linkage circuit includes an OR gate N2, a resistor R32, and a resistor R34; the first end of the resistor R32 is connected to the first end of the resistor R34, and the connection point is connected to the first input terminal of the OR gate N2; the second end of the resistor R34 is grounded; the second end of the resistor R32 is connected to the first end of the resistor R31; the second input terminal of the OR gate N2 is connected to the main control BCM; the output terminal of the OR gate N2 is respectively connected to the switch K21 and the switch K22.

[0013] Further, it further includes a second linkage circuit; the second linkage circuit includes a triode N3, a capacitor C3, and a resistor R33; the collector of the triode N3 is connected to the power supply VCC, the base is connected to the output terminal of the NOT gate N1, and the emitter is connected to the first end of the capacitor C3; the second end of the capacitor C3 is connected to the first end of the resistor R33, and the connection point is connected to the third input terminal of the OR gate N2; the second end of the resistor R33 is grounded.

[0014] A sodium-ion energy storage system includes the high-voltage box applicable to the sodium-ion energy storage system described above, and further includes an external energy storage PCS, a slave control BMM, an energy management system EMS, an external sodium-ion battery PACK1, and an external sodium-ion battery PACK2; the first positive terminal and the first negative terminal of the filtering circuit are respectively connected to the positive terminal and the negative terminal of the external energy storage PCS; the second positive terminal and the second negative terminal of the switching circuit are respectively connected to the positive and negative terminals of the external sodium-ion battery PACK1; the third positive terminal and the third negative terminal of the switching circuit are respectively connected to the positive and negative terminals of the external sodium-ion battery PACK2; the main control BCM is respectively connected to the external energy storage PCS, the slave control BMM, and the energy management system EMS.

[0015] A control method for a sodium-ion energy storage system, used to control the sodium-ion energy storage system described above, includes the following steps:

[0016] The high-voltage box performs a power-on self-check, and the main control BCM performs series and parallel switching on the external sodium-ion battery PACK1 and the external sodium-ion battery PACK2, and records the series and parallel voltage values.

[0017] When the series voltage value is greater than the maximum voltage on the DC side of the external energy storage PCS and the parallel voltage is less than the maximum voltage on the DC side of the external energy storage PCS, the main control BCM controls the switch DCSSR1 to disconnect, the switches DCSSR2 and DCSSR3 to conduct, and the external sodium-ion battery PACK1 and the external sodium-ion battery PACK2 enter the parallel voltage reduction mode.

[0018] When the series voltage value is greater than the minimum voltage on the DC side of the external energy storage PCS and less than the maximum voltage on the DC side of the external energy storage PCS, the main control BCM controls the switch DCSSR1 to conduct, and the switches DCSSR2 and DCSSR3 to disconnect. The external sodium-ion battery PACK1 and the external sodium-ion battery PACK2 enter the series operation boost mode;

[0019] When the series voltage value is less than the minimum voltage on the DC side of the external energy storage PCS, the main control BCM sends a charge and discharge prohibition instruction to the external energy storage PCS and the energy management system EMS, and reports the total voltage undervoltage fault;

[0020] In the case of charging, after the main control BCM adjusts the series or parallel connection mode of the external sodium-ion battery PACK1 and the external sodium-ion battery PACK2, it controls the soft start circuit to perform charging soft start in the order of pre-charging first and then formal charging, so as to prevent large current from causing impact damage to the battery, and adjusts the series and parallel connections according to the battery voltage situation;

[0021] In the case of discharging, after the main control BCM adjusts the series or parallel connection mode of the external sodium-ion battery PACK1 and the external sodium-ion battery PACK2, it controls the soft start circuit to perform discharging soft start in the order of pre-discharging first and then formal discharging, so as to prevent large current from causing impact damage to the external energy storage PCS, and adjusts the series and parallel connections according to the battery voltage situation.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. Based on the characteristics of the wide voltage of sodium-ion energy storage batteries, the uninterrupted power supply of the energy storage system and the requirements of rapid protection on the basis of the traditional high-voltage box. This high-voltage box takes the main control BCM as the control center, and according to the collected battery state data, the operating state of the energy storage system and the control request of the upper-layer system, controls the on and off of the DC solid-state switch DCSSR and cooperates with the voltage and current transformation of the external energy storage PCS to realize the nanosecond-level seamless switching of the high and low voltages of the battery cluster. Different LC circuit groups are configured to suppress the current and voltage mutations generated by the series and parallel switching of the external sodium-ion batteries in different states, smooth the current and voltage mutations, and avoid the impact on the external energy storage PCS during the switching process. On the premise that the existing external energy storage PCS converter remains unchanged, an adjustable high-voltage box is used to realize the seamless access of a high-efficiency and low-cost wide voltage range sodium-ion energy storage system. Description of the Drawings

[0024] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0025] Figure 1 It is a schematic structural diagram of a high-voltage box applicable to a sodium-ion energy storage system;

[0026] Figure 2 It is the first schematic circuit diagram of a high-voltage box applicable to a sodium-ion energy storage system;

[0027] Figure 3 It is the second schematic circuit diagram of a high-voltage box applicable to a sodium-ion energy storage system;

[0028] Figure 4 It is a schematic structural diagram of a sodium-ion energy storage system;

[0029] Figure 5 It is a schematic structural diagram of the series state of a high-voltage box applicable to a sodium-ion energy storage system;

[0030] Figure 6 It is a schematic structural diagram of the parallel state of a high-voltage box applicable to a sodium-ion energy storage system. Specific embodiments

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0032] It should be understood that when used in this application document, the terms "include" and "comprise" indicate the presence of the described features, wholes, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0033] It should also be understood that the terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in this application document, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms.

[0034] It should be further understood that the term " / and" used in this application document refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0035] Embodiment 1

[0036] As Figure 1The figure shows a schematic structural diagram of a high-voltage box applicable to a sodium-ion energy storage system, including: a soft start circuit, a filter circuit, a Hall sensor, a voltage sensor, a main control BCM, and a switch circuit; the first positive terminal of the filter circuit is connected to the positive terminal of an external energy storage PCS; the first negative terminal of the filter circuit is connected to the negative terminal of the external energy storage PCS; the second positive terminal of the filter circuit is connected to the first end of the soft start circuit; the second end of the soft start circuit and the second negative terminal of the filter circuit are respectively connected to the first positive terminal and the first negative terminal of the switch circuit; the Hall sensor is connected in series between the second negative terminal of the filter circuit and the first negative terminal of the switch circuit; the switch circuit further has a second positive terminal and a second negative terminal; the second positive terminal of the switch circuit is connected to the positive end of an external sodium-ion battery PACK1; the second negative terminal of the switch circuit is connected to the negative end of the external sodium-ion battery PACK1; the switch circuit further has a third positive terminal and a third negative terminal; the third positive terminal of the switch circuit is connected to the positive end of an external sodium-ion battery PACK2; the third negative terminal of the switch circuit is connected to the negative end of the external sodium-ion battery PACK2; the voltage sensor is arranged at the first positive terminal and the first negative terminal of the switch circuit and is connected to the main control BCM; the main control BCM is respectively connected to the soft start circuit, the filter circuit, the Hall sensor, and the switch circuit to control the switch circuit to enable the external sodium-ion battery PACK1 and the external sodium-ion battery PACK2 to switch between parallel and series states, and at the same time adjust the filtering ability level of the filter circuit according to the change in the series-parallel connection state between the external sodium-ion battery PACK1 and the external sodium-ion battery PACK2, so as to suppress the current and voltage mutations generated by the switching of the series-parallel method of the external sodium-ion battery in different states, smooth the current and voltage mutations, and avoid the impact on the external energy storage PCS during the switching process.

[0037] Because the voltage withstand of the commonly used MOS (metal-oxide-semiconductor field-effect transistor) and IGBT (insulated gate bipolar transistor) nowadays is within 1200V, the DC side voltage of the energy storage converter PCS is generally between 500V and 1100V, and the full SOC voltage range of the sodium-ion battery is between 1.5V and 4V. When the battery cluster is grouped in 334S, the battery cluster voltage range is 501 - 1336V, exceeding the accessible voltage range of 1100V on the DC side of the current energy storage converter PCS. When the battery cluster is grouped in less than 334S, the minimum voltage of the battery cluster is lower than the accessible voltage range of the DC side of the energy storage converter PCS.

[0038] Therefore, in this application, based on the traditional high-voltage box, it is based on the characteristics of the wide voltage of the sodium-ion energy storage battery, the uninterrupted power supply of the energy storage system, and the requirements for rapid protection. The high-voltage box takes the main control BCM as the control center. According to the collected battery state data, the operating state of the energy storage system, and the control requests of the upper-layer system, it controls the on-off of the switch circuit and cooperates with the voltage and current conversion of the external energy storage PCS to achieve nanosecond-level seamless switching of the high and low voltages of the battery cluster. Different LC circuit groups are configured in the filter circuit to suppress the current and voltage mutations generated by the switching of the series-parallel connection of the external sodium-ion battery in different states, smooth the current and voltage mutations, and avoid the impact on the external energy storage PCS during the switching process. On the premise that the existing external energy storage PCS converter remains unchanged, an adjustable high-voltage box is used to achieve seamless access to a wide-voltage-range sodium-ion energy storage system with high efficiency and low cost.

[0039] In specific implementation, as Figure 2 shown, the switch circuit includes switch DCSSR1, switch DCSSR2, and switch DCSSR3; the first positive terminal of the switch circuit is directly led out as the second positive terminal of the switch circuit; the first positive terminal of the switch circuit is connected in series with the switch DCSSR3 and then used as the third positive terminal of the switch circuit; the first negative terminal of the switch circuit is directly led out as the third negative terminal of the switch circuit; the first negative terminal of the switch circuit is connected in series with the switch DCSSR2 and then used as the second negative terminal of the switch circuit; the switch DCSSR1 is connected in series between the second negative terminal and the third positive terminal of the switch circuit; the main control BCM is connected to the switch DCSSR1, switch DCSSR2, and switch DCSSR3 to control the on-off states of each switch.

[0040] In specific implementation, the filter circuit includes a first LC circuit and a second LC circuit; the first LC circuit and the second LC circuit are connected in parallel.

[0041] In specific implementation, the first LC circuit includes a switch K11, a switch K12, an inductor L1, and a capacitor C1; the second LC circuit includes a switch K21, a switch K22, an inductor L2, and a capacitor C2; the first end of the switch K11 is connected to the first end of the switch K12 and the first end of the inductor L1; the second end of the switch K12 is connected to the first end of the capacitor C1; the first end of the switch K21 is connected to the first end of the switch K22 and the first end of the inductor L2; the second end of the switch K22 is connected to the first end of the capacitor C2; the second end of the switch K11 is connected to the second end of the switch K21, and the connection point serves as the first positive terminal of the filter circuit; the second ends of the inductor L1 and the inductor L2 are connected, and the connection point serves as the second positive terminal of the filter circuit; the second ends of the capacitor C1 and the capacitor C2 are connected, the second end of the capacitor C1 serves as the first negative terminal of the filter circuit, and the second end of the capacitor C2 serves as the second negative terminal of the filter circuit; the main control BCM is connected to the switch K11, the switch K12, the switch K21, and the switch K22 to control the filtering ability level state of the filter circuit.

[0042] In specific implementation, the soft start circuit includes a relay K31, a relay K32, and a resistor R31; the first end of the relay K31 is connected to the first end of the resistor R31; the second end of the relay K31 is connected to the first end of the relay K32, and the connection point serves as the first end of the soft start circuit; the second end of the resistor R31 is connected to the second end of the relay K32, and the connection point serves as the second end of the soft start circuit; the soft start circuit is used to pre-charge by first turning on the relay K31 and the resistor R31 before officially turning on the relay K32 of the main path to prevent excessive impact on the external sodium-ion battery.

[0043] Further, the external sodium-ion battery PACK1 and PACK2 have the same grouping method, both being XPYS, that is, Y sodium-ion battery cells are connected in series, and X battery packs with Y sodium-ion battery cells connected in series are connected in parallel.

[0044] Further, the switches DCSSR1, DCSSR2, and DCSSR3 can use MOS transistors or IGBT transistors, or other electronic components that can achieve the same or better switching performance.

[0045] Further, the switches K11, K12, K21, and K22 can use MOS transistors or IGBT transistors, or they can also use relays, or other electronic components that can achieve the same switching function.

[0046] Further, the above-mentioned circuits are arranged on a circuit board, and the high-voltage box further includes a housing, and the circuit board is arranged in the housing.

[0047] As shown Figure 2 in 3 Figures 5 and 6, a switch QF is provided between the second positive terminal of the filter circuit and the first end of the soft start circuit; a switch QF is provided between the second negative terminal of the filter circuit and the Hall sensor.

[0048] In this application, the soft start circuit realizes the flexible access of the high-voltage box to power on, and the Hall sensor collects the main circuit current signal of the high-voltage box. The battery master control BCM collects the main circuit voltage and current signals, receives the information of the battery slave control BMM and the information and control signals of the upper-layer EMS and the external energy storage PCS, and feeds back the battery state information and control signals to the upper-layer EMS and the external energy storage PCS. It makes logical judgments based on the collected information and control signals and controls the soft start circuit relay to close, the filter circuit switch group to close, and the on-off of the switch circuit DC solid-state switch DCSSR. Different LC circuit groups are configured in the filter circuit to suppress the current and voltage mutations generated by the external sodium-ion battery due to the series-parallel mode switching under different states, smooth the current and voltage mutations, and avoid the impact on the external energy storage PCS during the switching process. The master control BCM controls the on-off of the DC solid-state switch DCSSR to cooperate with the conversion of the voltage and current of the external energy storage PCS to achieve seamless switching of the high and low voltages of the battery cluster.

[0049] Embodiment 2

[0050] As shown Figure 3 in this embodiment, the difference from Embodiment 1 is that the switch circuit further includes a NOT gate N1; the input terminal of the NOT gate N1 is connected to the control terminals of the switches DCSSR2 and DCSSR3; the input terminal of the NOT gate N1 is connected to the master control BCM; the output terminal of the NOT gate N1 is connected to the control terminal of the switch DCSSR1. Through the NOT gate N1, the interlock between the series mode and the parallel mode of the battery can be realized, that is, it is impossible to have the parallel mode when using the series mode, and it is also impossible to have the series mode when using the parallel mode, preventing the switches DCSSR1, DCSSR2, and DCSSR3 from being fully turned on simultaneously due to the failure of the master control BCM or the incorrect signal output setting, resulting in a short circuit of the battery and the external energy storage PCS, and improving the safety performance of the circuit.

[0051] In specific implementation, it further includes a first linkage circuit; the first linkage circuit includes an OR gate N2, a resistor R32, and a resistor R34; the first end of the resistor R32 is connected to the first end of the resistor R34, and the connection point is connected to the first input terminal of the OR gate N2; the second end of the resistor R34 is grounded; the second end of the resistor R32 is connected to the first end of the resistor R31; the second input terminal of the OR gate N2 is connected to the master control BCM; the output terminal of the OR gate N2 is respectively connected to the switches K21 and K22.

[0052] Linking the soft start circuit and the filtering circuit through the first linkage circuit can:

[0053] Smooth start: The soft start circuit can gradually increase the current when the system starts, avoiding sudden high - current shocks. The filtering circuit can further smooth the current, reducing current ripples and spikes.

[0054] Protect the circuit: Through the linkage of the soft start circuit and the filtering circuit, the current shock during startup can be effectively reduced, protecting other components in the circuit, such as capacitors, inductors, and semiconductor devices.

[0055] Improve system stability: The linkage of the soft start circuit and the filtering circuit can ensure that the current and voltage changes during system startup are smoother, reducing system oscillations and instability.

[0056] In specific implementation, it also includes a second linkage circuit; the second linkage circuit includes a triode N3, a capacitor C3, and a resistor R33; the collector of the triode N3 is connected to the power supply VCC, the base is connected to the output terminal of the NOT gate N1, and the emitter is connected to the first end of the capacitor C3; the second end of the capacitor C3 is connected to the first end of the resistor R33, and the connection point is connected to the third input terminal of the OR gate N2; the second end of the resistor R33 is grounded.

[0057] Linking the switch circuit and the filtering circuit through the second linkage circuit can:

[0058] Optimize current distribution: The switch circuit controls the connection mode of the battery pack (parallel or series), and the filtering circuit can smooth the current change during the switch circuit switching, optimizing the current distribution.

[0059] Reduce current shock: When the switch circuit switches, adapting to the corresponding filtering circuit ability level (for example, the series - cut - in voltage is higher, and two LC circuits are dynamically adjusted), the sudden change of current can be reduced, avoiding the impact on the energy storage system and PCS (Power Conversion System).

[0060] Improve system response speed: Through the linkage of the switch circuit and the filtering circuit, the system can respond faster to changes in system status, improving the dynamic performance of the system.

[0061] At the same time, the linkage effect realized by the hardware circuit in this application can improve the anti - interference ability and fault tolerance ability, preventing the problem of linkage failure caused by the failure of the upper - layer controller. Even if the main control BCM fails, it does not affect the linkage protection effect.

[0062] Therefore, through the linkage circuit, not only the system reliability is improved. Through the linkage of the soft start circuit and the filter circuit, as well as the linkage of the switch circuit and the filter circuit, the reliability and stability of the system can be significantly improved, and the probability of failure occurrence can be reduced. It can also extend the equipment life, reduce current impact and voltage fluctuation, and can extend the service life of battery packs, capacitors, inductors and other key components. At the same time, the system performance is optimized. By smoothing the current and voltage changes, the overall performance of the system can be optimized, the energy conversion efficiency can be improved, and the energy loss can be reduced. It also improves the system's anti-interference ability and fault tolerance ability. It can significantly improve the stability and reliability of the energy storage system, reduce current impact and voltage fluctuation, optimize the system performance, and extend the equipment life. These improvements are of great significance for improving the overall performance and safety of the energy storage system.

[0063] Embodiment 3

[0064] As Figure 1 、 Figure 4 shown, a sodium-ion energy storage system includes the high-voltage box applicable to the sodium-ion energy storage system described above, and also includes an external energy storage PCS, a slave BMM, an energy management system EMS, an external sodium-ion battery PACK1 and an external sodium-ion battery PACK2; the first positive terminal and the first negative terminal of the filter circuit are respectively connected to the positive terminal and the negative terminal of the external energy storage PCS; the second positive terminal and the second negative terminal of the switch circuit are respectively connected to the positive and negative terminals of the external sodium-ion battery PACK1; the third positive terminal and the third negative terminal of the switch circuit are respectively connected to the positive and negative terminals of the external sodium-ion battery PACK2; the master BCM is respectively connected to the external energy storage PCS, the slave BMM and the energy management system EMS.

[0065] Embodiment 4

[0066] A control method for a sodium-ion energy storage system, used to control the sodium-ion energy storage system described above, includes the following steps:

[0067] The high-voltage box powers on and performs self-check. The master BCM performs series and parallel switching on the external sodium-ion battery PACK1 and the external sodium-ion battery PACK2, and records the series and parallel voltage values.

[0068] When the series voltage value is greater than the maximum DC voltage on the DC side of the external energy storage PCS and the parallel voltage is less than the maximum DC voltage on the DC side of the external energy storage PCS, the master BCM controls the switch DCSSR1 to disconnect, and the switches DCSSR2 and DCSSR3 to conduct, and the external sodium-ion battery PACK1 and the external sodium-ion battery PACK2 enter the parallel step-down mode.

[0069] When the series voltage value is greater than the minimum voltage on the DC side of the external energy storage PCS and less than the maximum voltage on the DC side of the external energy storage PCS, the main control BCM controls the switch DCSSR1 to conduct, and the switches DCSSR2 and DCSSR3 to disconnect. The external sodium-ion battery PACK1 and the external sodium-ion battery PACK2 enter the series operation boost mode;

[0070] When the series voltage value is less than the minimum voltage on the DC side of the external energy storage PCS, the main control BCM sends a charge and discharge prohibition instruction to the external energy storage PCS and the energy management system EMS, and reports the total voltage undervoltage fault;

[0071] During charging, after the main control BCM adjusts the series or parallel connection mode of the external sodium-ion battery PACK1 and the external sodium-ion battery PACK2, it controls the soft start circuit to perform charging soft start in the way of pre-charging first and then formal charging, so as to prevent large current from causing impact damage to the battery, and adjusts the series and parallel according to the battery voltage situation;

[0072] During discharging, after the main control BCM adjusts the series or parallel connection mode of the external sodium-ion battery PACK1 and the external sodium-ion battery PACK2, it controls the soft start circuit to perform discharging soft start in the way of pre-discharging first and then formal discharging, so as to prevent large current from causing impact damage to the external energy storage PCS, and adjusts the series and parallel according to the battery voltage situation.

[0073] That is, let the total voltage of the external sodium-ion battery PACK1 be Vp1 and the total voltage of the external sodium-ion battery PACK2 be Vp2.

[0074] When Vp1 + Vp2 > the maximum voltage Vmax on the DC side of the PCS and Vp1 < Vmax & Vp2 < Vmax, the main control BCM controls DCSSR1 to disconnect, and the switches DCSSR2 and DCSSR3 to conduct. PACK1 and PACK2 enter the parallel buck mode, as Figure 6 . At this time, the main control BCM controls the switches K11, K12, K21, and K22 to close, and controls the relays K31 and K32 of the soft start circuit to close in sequence to connect the external sodium-ion battery to the DC side of the PCS.

[0075] When the main control BCM detects that the minimum voltage Vmin on the DC side of the PCS ≤ Vp1 + Vp2 ≤ Vmax, the main control BCM controls DCSSR1 to conduct, DCSSR2 and DCSSR3 to disconnect, and PACK1 and PACK2 enter the series operation boost mode, as Figure 5 . The main control BCM controls the switches K11, K12, K21, and K22 to close, and controls the relays K31 and K32 of the soft start circuit to close in sequence to connect the external sodium-ion battery to the DC side of the PCS.

[0076] When the master BCM detects that Vmin < Vp1 + Vp2, the master BCM sends charge and discharge inhibition commands to the PCS and EMS, reporting a total voltage undervoltage fault.

[0077] During the charging process, if the voltage Vc of any single cell in the energy storage system is ≥ 4.0V (the maximum voltage of a single battery cell, which can be obtained by setting a voltage detection circuit or sensor for each single battery cell and feeding back the signal to the master BCM), or Vp1 ≥ Vmax, or Vp2 ≥ Vmax, the BCM sends a charge inhibition command to the PCS and EMS.

[0078] During the discharging process, when Vp1 ≤ Vmin or Vp2 ≤ Vmin, and the voltage Vc of any single cell in the energy storage system is > 1.5V, the master BCM controls K11 and K12 to close, controls K21 and K22 to open, and after T1 time, controls DCSSR1 to conduct and DCSSR2 and DCSSR3 to open. After the switching, the voltage of the battery cluster doubles and the current halves, and it is very easy for PCS devices to be damaged due to sudden voltage increase and sudden current decrease. The first LC circuit of the high-voltage box provides current continuation and voltage stabilization for the switched current. After the switching, the BCM sends a command to double the PCS voltage and halve the current to adapt to the sudden change of the battery cluster voltage and current, enabling PACK1 and PACK2 to seamlessly enter the series boost mode. If the voltage Vc of any single cell in the energy storage system is ≤ 1.5V, the BCM sends a discharge inhibition command to the PCS and EMS. The T1 time is an interval time set according to actual needs.

[0079] During the discharging process, when the voltage Vc of any single cell in the energy storage system is ≤ 1.5V or Vp1 + Vp2 ≤ Vmin, the BCM sends a discharge inhibition command to the PCS and EMS.

[0080] During the charging process, when Vp1 + Vp2 ≥ Vmax, and the voltage Vc of any single cell in the energy storage system is < 4V, the BCM controls K11 and K12 to open, controls K21 and K22 to close, and after T2 time, controls DCSSR1 to conduct and DCSSR2 and DCSSR3 to open. After the switching, the voltage of the battery cluster halves and the current doubles, and it is very easy for PCS devices to be damaged due to sudden voltage drop and sudden current increase. The second LC circuit of the high-voltage box provides current continuation and voltage stabilization for the switched current. After the switching, the BCM sends a command to halve the PCS voltage and double the current to adapt to the sudden change of the battery cluster voltage and current, enabling PACK1 and PACK2 to seamlessly enter the parallel buck mode. If the voltage Vc of any single cell in the energy storage system is ≥ 4V, or Vp1 ≥ Vmax, or Vp2 ≥ Vmax, the BCM sends a charge inhibition command to the PCS and EMS. The T2 time is an interval time set according to actual needs.

[0081] The high-voltage box of this solution can enable a sodium-ion energy storage system with a wide voltage range to be connected to a conventional PCS converter, without the need to configure a DCDC or use power devices with a higher voltage platform, and has the characteristics of low cost, high efficiency, fast switching speed, and high reliability.

[0082] In applications where seamless switching is not required or the switching time requirement is not strict, conventional circuit breakers, contactors, etc. can also be used to replace the DC solid-state switch DCSSR.

[0083] The present application provides a high-voltage box applicable to a sodium-ion energy storage system, comprising: a soft start circuit, a filtering circuit, a Hall sensor, a voltage sensor, a main control BCM, and a switching circuit; the first positive terminal of the filtering circuit is connected to the positive terminal of an external energy storage PCS; the first negative terminal of the filtering circuit is connected to the negative terminal of the external energy storage PCS; the second positive terminal of the filtering circuit is connected to the first end of the soft start circuit; the second end of the soft start circuit and the second negative terminal of the filtering circuit are respectively connected to the first positive terminal and the first negative terminal of the switching circuit; the Hall sensor is connected in series between the second negative terminal of the filtering circuit and the first negative terminal of the switching circuit; the switching circuit further has a second positive terminal and a second negative terminal; the second positive terminal of the switching circuit is connected to the positive end of an external sodium-ion battery PACK1; the second negative terminal of the switching circuit is connected to the negative end of the external sodium-ion battery PACK1; the switching circuit further has a third positive terminal and a third negative terminal; the third positive terminal of the switching circuit is connected to the positive end of an external sodium-ion battery PACK2; the third negative terminal of the switching circuit is connected to the negative end of the external sodium-ion battery PACK2; the voltage sensor is arranged at the first positive terminal and the first negative terminal of the switching circuit and is connected to the main control BCM; the main control BCM is respectively connected to the soft start circuit, the filtering circuit, the Hall sensor, and the switching circuit to control the switching circuit to enable the external sodium-ion battery PACK1 and the external sodium-ion battery PACK2 to switch between a parallel state and a series state, and at the same time, adjust the filtering ability level of the filtering circuit according to the change of the series-parallel connection state between the external sodium-ion battery PACK1 and the external sodium-ion battery PACK2, so as to suppress the current and voltage mutations generated by the switching of the external sodium-ion battery in different states due to the series-parallel mode switching, smooth the current and voltage mutations, and avoid the impact on the external energy storage PCS during the switching process. Based on the characteristics of the wide voltage of sodium-ion energy storage batteries, the requirements of uninterrupted power supply and fast protection of the energy storage system on the basis of the traditional high-voltage box. The high-voltage box takes the main control BCM as the control center, and according to the collected battery state data, the operating state of the energy storage system, and the control request of the upper-layer system, controls the on-off of the switching circuit and cooperates with the voltage and current transformation of the external energy storage PCS to realize the seamless switching of the high and low voltages of the battery cluster in nanoseconds. Different LC circuit groups are configured in the filtering circuit to suppress the current and voltage mutations generated by the switching of the external sodium-ion battery in different states due to the series-parallel mode switching, smooth the current and voltage mutations, and avoid the impact on the external energy storage PCS during the switching process. On the premise that the existing external energy storage PCS converter remains unchanged, an adjustable high-voltage box is used to realize the seamless access of a sodium-ion energy storage system with a wide voltage range efficiently and at low cost.

[0084] Those of ordinary skill in the art can realize that the units of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the composition of each example has been generally described according to functions in the above description. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods for each specific application to implement the described functions, but such implementation should not be considered to exceed the scope of the present invention.

[0085] In the embodiments provided by the present invention, it should be understood that the division of units is only a logical function division, and there may be other division methods in actual implementation. For example, multiple units can be combined into one unit, one unit can be split into multiple units, or some features can be ignored, etc.

[0086] In addition, the functional units in each embodiment of the present invention can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated units can be implemented in the form of hardware or in the form of software functional units.

[0087] If the above-mentioned integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in each embodiment of the present invention. The foregoing storage medium includes: various media such as USB flash drives, read-only memories (ROMs), random access memories (RAMs), mobile hard disks, magnetic disks, or optical discs that can store program codes.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the present invention.

Claims

1. A high-voltage box applicable to a sodium-ion energy storage system, characterized in that, Including: Soft start circuit, filter circuit, Hall sensor, voltage sensor, main control BCM and switch circuit; The first positive terminal of the filter circuit is connected to the positive terminal of the external energy storage PCS; the first negative terminal of the filter circuit is connected to the negative terminal of the external energy storage PCS; the second positive terminal of the filter circuit is connected to the first end of the soft start circuit; the second end of the soft start circuit and the second negative terminal of the filter circuit are respectively connected to the first positive terminal and the first negative terminal of the switch circuit; the Hall sensor is connected in series between the second negative terminal of the filter circuit and the first negative terminal of the switch circuit; the switch circuit also has a second positive terminal and a second negative terminal; the second positive terminal of the switch circuit is connected to the positive end of the external sodium-ion battery PACK1; the second negative terminal of the switch circuit is connected to the negative end of the external sodium-ion battery PACK1; the switch circuit also has a third positive terminal and a third negative terminal; the third positive terminal of the switch circuit is connected to the positive end of the external sodium-ion battery PACK2; the third negative terminal of the switch circuit is connected to the negative end of the external sodium-ion battery PACK2; the voltage sensor is arranged between the first positive terminal and the first negative terminal of the switch circuit and is connected to the main control BCM; the main control BCM is respectively connected to the soft start circuit, the filter circuit, the Hall sensor and the switch circuit to control the switch circuit to enable the external sodium-ion battery PACK1 and the external sodium-ion battery PACK2 to switch between parallel and series states, and at the same time adjust the filtering ability level of the filter circuit according to the change of the series-parallel connection state between the external sodium-ion battery PACK1 and the external sodium-ion battery PACK2 to suppress the current and voltage mutations generated by the switching of the series-parallel connection method of the external sodium-ion battery in different states, smooth the current and voltage mutations, and avoid the impact on the external energy storage PCS during the switching process.

2. The high-voltage box applicable to a sodium-ion energy storage system according to claim 1, wherein The switch circuit includes switch DCSSR1, switch DCSSR2 and switch DCSSR3; the first positive terminal of the switch circuit is directly led out as the second positive terminal of the switch circuit; the first positive terminal of the switch circuit is connected in series with the switch DCSSR3 and then used as the third positive terminal of the switch circuit; the first negative terminal of the switch circuit is directly led out as the third negative terminal of the switch circuit; the first negative terminal of the switch circuit is connected in series with the switch DCSSR2 and then used as the second negative terminal of the switch circuit; the switch DCSSR1 is connected in series between the second negative terminal of the switch circuit and the third positive terminal of the switch circuit; the main control BCM is connected to the switch DCSSR1, switch DCSSR2 and switch DCSSR3 to control the on-off states of each switch.

3. The high-voltage box applicable to a sodium-ion energy storage system according to claim 2, wherein, The switch circuit also includes a NOT gate N1; the input terminal of the NOT gate N1 is connected to the control terminals of the switch DCSSR2 and the switch DCSSR3; the input terminal of the NOT gate N1 is connected to the main control BCM; the output terminal of the NOT gate N1 is connected to the control terminal of the switch DCSSR1.

4. The high-voltage box applicable to a sodium-ion energy storage system according to claim 3, wherein, The filter circuit includes a first LC circuit and a second LC circuit; the first LC circuit and the second LC circuit are connected in parallel.

5. The high-voltage box applicable to a sodium-ion energy storage system according to claim 4, characterized in that, The first LC circuit includes a switch K11, a switch K12, an inductor L1, and a capacitor C1; the second LC circuit includes a switch K21, a switch K22, an inductor L2, and a capacitor C2; the first end of the switch K11 is connected to the first end of the switch K12 and the first end of the inductor L1; the second end of the switch K12 is connected to the first end of the capacitor C1; the first end of the switch K21 is connected to the first end of the switch K22 and the first end of the inductor L2; the second end of the switch K22 is connected to the first end of the capacitor C2; the second end of the switch K11 is connected to the second end of the switch K21, and the connection point serves as the first positive terminal of the filter circuit; the second ends of the inductor L1 and the inductor L2 are connected, and the connection point serves as the second positive terminal of the filter circuit; the second ends of the capacitor C1 and the capacitor C2 are connected, the second end of the capacitor C1 serves as the first negative terminal of the filter circuit, and the second end of the capacitor C2 serves as the second negative terminal of the filter circuit; the main control BCM is connected to the switch K11, the switch K12, the switch K21, and the switch K22 to control the filtering ability level state of the filter circuit.

6. The high-voltage box applicable to a sodium-ion energy storage system according to claim 5, wherein The soft start circuit includes a relay K31, a relay K32, and a resistor R31; the first end of the relay K31 is connected to the first end of the resistor R31; the second end of the relay K31 is connected to the first end of the relay K32, and the connection point serves as the first end of the soft start circuit; the second end of the resistor R31 is connected to the second end of the relay K32, and the connection point serves as the second end of the soft start circuit; the soft start circuit is used to pre-charge by turning on the relay K31 and the resistor R31 before officially turning on the relay K32 of the main path to prevent excessive impact on the external sodium ion battery.

7. The high-voltage box applicable to the sodium-ion energy storage system according to claim 6, wherein It further includes a first linkage circuit; the first linkage circuit includes an OR gate N2, a resistor R32, and a resistor R34; the first end of the resistor R32 is connected to the first end of the resistor R34, and the connection point is connected to the first input terminal of the OR gate N2; the second end of the resistor R34 is grounded; the second end of the resistor R32 is connected to the first end of the resistor R31; the second input terminal of the OR gate N2 is connected to the main control BCM; the output terminal of the OR gate N2 is respectively connected to the switch K21 and the switch K22.

8. The high-voltage box applicable to the sodium-ion energy storage system according to claim 7, characterized in that, It further includes a second linkage circuit; the second linkage circuit includes a triode N3, a capacitor C3, and a resistor R33; the collector of the triode N3 is connected to the power supply VCC, the base is connected to the output terminal of the NOT gate N1, and the emitter is connected to the first end of the capacitor C3; the second end of the capacitor C3 is connected to the first end of the resistor R33, and the connection point is connected to the third input terminal of the OR gate N2; the second end of the resistor R33 is grounded.

9. A sodium-ion energy storage system, characterized in that, Including the high-voltage box applicable to the sodium-ion energy storage system according to any one of claims 1 to 8, it further includes an external energy storage PCS, a slave BMM, an energy management system EMS, an external sodium-ion battery PACK1, and an external sodium-ion battery PACK2; the first positive terminal and the first negative terminal of the filter circuit are respectively connected to the positive terminal and the negative terminal of the external energy storage PCS; the second positive terminal and the second negative terminal of the switch circuit are respectively connected to the positive and negative terminals of the external sodium-ion battery PACK1; the third positive terminal and the third negative terminal of the switch circuit are respectively connected to the positive and negative terminals of the external sodium-ion battery PACK2; the master BCM is respectively connected to the external energy storage PCS, the slave BMM, and the energy management system EMS.

10. A control method for a sodium-ion energy storage system, characterized in that, For controlling the sodium-ion energy storage system according to claim 9, it includes the following steps: The high-voltage box powers on for self-check, and the master BCM performs series and parallel switching on the external sodium-ion battery PACK1 and the external sodium-ion battery PACK2, and records the series and parallel voltage values. When the series voltage value is greater than the maximum DC side voltage of the external energy storage PCS and the parallel voltage is less than the maximum DC side voltage of the external energy storage PCS, the master BCM controls the switch DCSSR1 to disconnect, and the switches DCSSR2 and DCSSR3 to conduct, and the external sodium-ion battery PACK1 and the external sodium-ion battery PACK2 enter the parallel buck mode. When the series voltage value is greater than the minimum DC side voltage of the external energy storage PCS and less than the maximum DC side voltage of the external energy storage PCS, the master BCM controls the switch DCSSR1 to conduct, and the switches DCSSR2 and DCSSR3 to disconnect, and the external sodium-ion battery PACK1 and the external sodium-ion battery PACK2 enter the series operation boost mode. When the series voltage value is less than the minimum DC side voltage of the external energy storage PCS, the master BCM sends a charge and discharge prohibition instruction to the external energy storage PCS and the energy management system EMS, and reports the total voltage undervoltage fault. In the case of charging, after the master BCM adjusts the series or parallel connection mode of the external sodium-ion battery PACK1 and the external sodium-ion battery PACK2, it controls the soft start circuit to perform charging soft start in the way of pre-charging first and then formal charging, so as to prevent large current from causing impact damage to the battery, and adjusts the series and parallel according to the battery voltage situation. In the case of discharging, after the master BCM adjusts the series or parallel connection mode of the external sodium-ion battery PACK1 and the external sodium-ion battery PACK2, it controls the soft start circuit to perform discharging soft start in the way of pre-discharging first and then formal discharging, so as to prevent large current from causing impact damage to the external energy storage PCS, and adjusts the series and parallel according to the battery voltage situation.

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