Direct-current voltage conversion circuit of all-vanadium redox flow battery

Abstract

The utility model relates to a direct-current voltage conversion circuit of an all-vanadium redox flow battery, which belongs to the technical field of vanadium batteries and comprises an electric pile group, a control circuit, a DC / DC converter and a CPU (central processing unit) controller. The electric pile group comprises a first electric pile group branch, a second electric pile group branch and a third electric pile group branch which are connected in parallel; the control circuit comprises a first control circuit and a second control circuit; the first control circuit is connected with the output ends of the first electric pile group branch and the second electric pile group branch; the second control circuit is connected with the output ends of the second electric pile group branch and the third electric pile group branch; each electric pile group branch is connected in series with a bridge arm of the DC / DC converter through an energy storage inductor; and the CPU controller is connected with each electric pile group branch, the control circuit and the DC / DC converter. According to the utility model, through the galvanic pile groups which are combined and connected in series and in parallel, branch independent control of the galvanic pile groups and interleaved parallel control of the converters are realized.

Description

Technical Field

[0001] The utility model relates to the technical field of all-vanadium liquid flow batteries, in particular to a direct current voltage conversion circuit of an all-vanadium liquid flow battery. Background Art

[0002] All-vanadium liquid flow battery is a new energy storage technology with relatively young technology. It is particularly suitable for applications with high safety requirements and the need for flexible adjustment of energy storage capacity. All-vanadium liquid flow battery has become an important energy storage product for the promotion of large-scale energy storage due to its low current energy density, non-flammability, no risk of combustion and explosion, and can be reused many times and easy to expand capacity.

[0003] All-vanadium liquid flow batteries have low energy density, and the electrolyte needs to circulate for energy exchange. The voltage of a single battery stack is low, so it is necessary to connect the batteries in series to increase the voltage, and connect the batteries in parallel to increase the current of the battery group. However, if there are too many battery stacks in series, the battery stack will generate bypass current, the loss through the pipeline network will increase, and the efficiency will decrease. Therefore, an external DC / DC converter is needed to raise the voltage at the battery pack end. After adding DC / DC converters in series and parallel, the voltages of different battery stack branches will differ, and the circulating current will further reduce the overall efficiency.

[0004] Therefore, it is urgent to propose a DC voltage conversion circuit for an all-vanadium liquid flow battery that can reduce the circulating current of each branch and the ripple of the output voltage and improve the voltage conversion quality. Utility Model Content

[0005] In view of this, it is necessary to provide a DC voltage conversion circuit for an all-vanadium liquid flow battery to solve the technical problem of low voltage conversion efficiency caused by circulating current caused by voltage difference in existing battery stack branches.

[0006] In order to solve the above problems, the utility model provides a DC voltage conversion circuit of an all-vanadium liquid flow battery, including a battery stack, a control circuit, a DC / DC converter and a CPU controller;

[0007] Wherein, the battery stack group includes a first battery stack group branch, a second battery stack group branch, and a third battery stack group branch connected in parallel;

[0008] The control circuit includes a first control circuit and a second control circuit; the first control circuit is connected to the output end of the first battery stack group branch and the output end of the second battery stack group branch; the second control circuit is connected to the output end of the second battery stack group branch and the output end of the third battery stack group branch;

[0009] Each of the battery stack branches is connected in series with a bridge arm of a DC / DC converter via an energy storage inductor;

[0010] The CPU controller is connected to each battery stack branch, the control circuit and the DC / DC converter.

[0011] In a possible implementation, each of the battery stack group branches includes a plurality of battery stacks and battery stack switches connected in series;

[0012] The input end of each battery stack group branch is connected in series with the battery stack switch to control the working state of each battery stack group branch.

[0013] In one possible implementation, one end of the first control circuit is connected to the output end of the first battery stack branch, and the other end is connected to the output end of the second battery stack branch, and the first control circuit is used to separate and merge the first battery stack branch and the second battery stack branch.

[0014] In one possible implementation, one end of the second control circuit is connected to the output end of the second battery stack branch, and the other end is connected to the output end of the third battery stack branch, and the second control circuit is used to separate and merge the second battery stack branch and the third battery stack branch.

[0015] In a possible implementation, the DC / DC converter is externally connected to a capacitor and a DC-to-AC inverter.

[0016] In one possible implementation, the CPU controller includes a CPU processing unit, which is used to receive monitoring data, generate a stack switch control signal for each stack group branch, receive an output voltage of each stack group branch, generate a control signal, and generate a trigger signal based on input and output data.

[0017] In a possible implementation, the CPU controller further includes a monitoring unit, one end of which is connected to the stack switch of the stack group, and the other end of which is connected to the CPU processing unit;

[0018] The monitoring unit is used to monitor the voltage and current of each battery stack group branch, and adjust the switch state of each battery stack group branch according to the switch control signal sent by the CPU processing unit.

[0019] In a possible implementation, the CPU controller further includes a sampling unit, one end of which is connected to the output end of each battery stack group branch, and the other end of which is connected to the CPU processing unit;

[0020] The sampling unit is used to collect the output voltage and current of each battery stack group branch, and adjust and control the switch state of each control circuit according to the control signal sent by the CPU processing unit.

[0021] In a possible implementation, the CPU controller further includes a trigger unit, one end of which is connected to the DC / DC converter, and the other end of which is connected to the CPU processing unit;

[0022] The trigger unit is used to control the working state of the DC / DC converter according to the trigger signal sent by the CPU processing unit.

[0023] In a possible implementation, the DC / DC converter is composed of three groups of DC / DC conversion units connected in parallel.

[0024] The beneficial effects of the utility model are as follows: the DC voltage conversion circuit of the all-vanadium liquid flow battery provided by the utility model comprises a plurality of groups of battery stacks connected in series and parallel, and each battery stack branch is individually controlled by a battery stack switch; the battery stack group is connected to a DC / DC converter, and each battery stack branch is controlled by a control circuit, so that each branch can be separated without interfering with each other, and the circulating current caused by the voltage difference of each branch is effectively avoided. At the same time, the control circuit performs staggered parallel control on the DC / DC converter, which effectively reduces the ripple of the output voltage and improves the voltage conversion efficiency. The input and output voltages of each battery stack group branch are monitored by a CPU controller, and a single battery stack group branch is closed-loop controlled, which further reduces the voltage difference between each battery stack branch and improves the voltage conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of the working principle of an embodiment of a DC voltage conversion circuit of an all-vanadium liquid flow battery provided by the utility model;

[0026] Figure 2 A schematic diagram of a series-parallel pipe network of a battery stack in a DC voltage conversion circuit of an all-vanadium liquid flow battery provided by the utility model;

[0027] Figure 3 This is a schematic diagram of the working process of the DC voltage conversion circuit of the all-vanadium liquid flow battery provided by the utility model. DETAILED DESCRIPTION

[0028] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0029] In the description of the embodiments of the present utility model, unless otherwise specified, "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may indicate three situations: A exists alone, A and B exist at the same time, and B exists alone.

[0030] Reference Figure 1 , Figure 1The schematic diagram of the working principle of an embodiment of a DC voltage conversion circuit of an all-vanadium liquid flow battery provided by the utility model; The utility model discloses a DC voltage conversion circuit of an all-vanadium liquid flow battery, including a battery stack 1, a control circuit 2, a DC / DC converter 3 and a CPU controller 4;

[0031] The battery stack group 1 includes a first battery stack group branch 5, a second battery stack group branch 6, and a third battery stack group branch 7 connected in parallel, and each battery stack group branch includes a plurality of battery stacks and battery stack switches K1, K2 or K3 connected in series;

[0032] Each battery stack group branch 5, 6, 7 is connected in series with the bridge arm of the DC / DC converter 3 through the energy storage inductor L1, L2, L3;

[0033] The control circuit 2 includes a first control circuit K4 and a second control circuit K5; the first control circuit K4 is connected to the output ends of the first battery stack group branch 5 and the second battery stack group branch 6; the second control circuit K5 is connected to the output ends of the second battery stack group branch 6 and the third battery stack group branch 7;

[0034] The CPU controller 4 is connected to each battery stack branch 5 , 6 , 7 , the control circuit 2 and the DC / DC converter 3 .

[0035] It should be noted that in the embodiment of the utility model, each battery stack group is generally composed of three four-series battery stack group branches, or three five-series battery stack group branches, such a combination can achieve a higher voltage and a larger current output. The DC / DC converter 3 is composed of three converters connected in parallel.

[0036] It should be further explained that the pipe network diagram of the three parallel stack group branches of this embodiment is as follows Figure 2 As shown, it includes a positive electrode pipe network 12, a negative electrode pipe network 13 and a stack group 1. The positive electrode pipe network includes a positive electrode tank 14, a circulation pump 15, a liquid supply pipe 16, a radiator 17 and a liquid return pipe 18. The positive electrode pipe network 12 pumps the electrolyte into the inlet of the stack group 1 through the circulation pump 15, and returns to the positive electrode tank 14 through the outlet of the stack group 1 through the radiator 17. The structure and working principle of the negative electrode pipe network 13 are the same as those of the positive electrode pipe network, and are not described in detail here.

[0037] Compared with the prior art, the utility model connects multiple groups of battery stacks in series and parallel, controls each battery stack branch individually through a battery stack switch, connects the battery stack group to a DC / DC converter, and separates and controls the connection of each battery stack branch through a control circuit, so that the branches can be separated without interfering with each other, effectively avoiding the circulating current caused by the voltage difference of each branch. At the same time, the control circuit controls the DC / DC converter in staggered parallel, effectively reducing the ripple of the output voltage and improving the voltage conversion efficiency. The input and output voltages of each battery stack group branch are monitored by the CPU controller, and a single battery stack group branch is closed-loop controlled, further reducing the voltage difference between each battery stack branch and improving the voltage conversion efficiency.

[0038] In the embodiment of the utility model, each of the battery stack group branches 5, 6, 7 includes a plurality of battery stacks and battery stack switches K1, K2, K3 connected in series;

[0039] The input ends of the battery stack branches 5, 6, 7 are connected in series with the battery stack switches K1, K2, K3 to control the working state of each battery stack branch.

[0040] It should be noted that the input end of the first battery stack group branch 5 is connected to the battery stack switch K1, the input end of the second battery stack group branch 6 is connected to the battery stack switch K2, and the input end of the third battery stack group branch 7 is connected to the battery stack switch K3. The working states of the first battery stack group branch 5, the second battery stack group branch 6 and the third battery stack group branch 7 are controlled by controlling the battery stack switches K1, K2 and K3. When K1, K2 and K3 are all closed, the three battery stack group branches work at the same time. When any one switch is turned on, only two battery stack group branches work.

[0041] The embodiment of the utility model controls the working state of each branch through different battery stack switches of each branch, and can flexibly control the battery stack group branches individually. When a branch is damaged, the battery stack group branch can be disconnected at any time, and other branches can continue to work.

[0042] In some embodiments of the present invention, one end of the first control circuit K4 is connected to the output end of the first battery stack group branch 5, and the other end is connected to the output end of the second battery stack group branch 6. The first control circuit K4 is used to separate and merge the first battery stack group branch 5 and the second battery stack group branch 6.

[0043] In a specific implementation, one end of the second control circuit K5 is connected to the output end of the second battery stack group branch 6, and the other end is connected to the output end of the third battery stack group branch 7. The second control circuit K5 is used to separate and merge the second battery stack group branch 6 and the third battery stack group branch 7.

[0044] Specifically, when the first control circuit K4 and the second control circuit K5 switches are turned on, the first battery stack group branch 5, the second battery stack group branch 6 and the third battery stack group branch 7 form three branches that do not interfere with each other, thereby achieving separate control of the three branches and further realizing dual closed-loop control of single-branch voltage and current.

[0045] Furthermore, when the first control circuit K4 and the second control circuit K5 are switched on, the first battery stack group branch 5, the second battery stack group branch 6 and the third battery stack group branch 7 form three parallel battery stack groups, and the DC / DC converter 3 is staggered in parallel to achieve voltage and current dual closed-loop control of the DC / DC converter 3. This ensures the stability of the voltage output and controls the output power by controlling the output current.

[0046] It should be noted that the three battery stack branches connected in parallel form three power supply systems. There may be voltage differences in the reference points of these three power supply systems. This voltage difference will generate circulating current, which will in turn affect the stability and efficiency of the circuit. Therefore, it is necessary to ensure that the voltage difference of the three battery stack branches is within the normal range.

[0047] Specifically, in order to ensure that the voltage difference of the three battery stack branches is within the normal range, each battery stack branch can be controlled individually by disconnecting the first control circuit K4 or the second control circuit K5, and the input voltage or current of each branch can be adjusted through the CPU controller to keep the voltage difference of each battery stack branch within the normal range.

[0048] Furthermore, when the voltage difference among the three battery stack branches is within a normal range, the first control circuit K4 or the second control circuit K5 can be closed. At this time, the output ends of the three DC / DC converters 3 are connected in parallel, and their working times are staggered, thereby realizing staggered parallel connection of the DC / DC converters 3. This staggered parallel connection can make the output voltage ripples of the DC / DC converters 3 cancel each other out, thereby reducing the overall output voltage ripple, and further improving the conversion power and efficiency.

[0049] This embodiment controls three parallel battery stack branches and DC / DC converters through two control switches, thereby achieving separate control of the three parallel battery stack branches, reducing the voltage difference between the branches, reducing the circulating current of each branch, and achieving staggered parallel connection of DC / DC converters, reducing the output voltage ripple, improving the overall output voltage stability, and further increasing the output power and the efficiency of voltage conversion.

[0050] In a specific implementation, the DC / DC converter 3 is externally connected to a capacitor C and a DC to AC inverter.

[0051] In some embodiments of the present invention, the CPU controller 4 includes a CPU processing unit 11, which is used to receive monitoring data, generate control signals of the battery stack switches K1, K2, and K3 of each battery stack group branch, receive the output voltage of each battery stack group branch 5, 6, and 7, generate control signals, and generate trigger signals based on input and output data.

[0052] Specifically, the CPU processing unit 11 is used to receive the monitoring data of the monitoring unit 8, generate a switch control signal for each battery stack branch, receive the output voltage of each battery stack branch sent by the sampling unit 9, generate a control signal, and generate a trigger signal according to the input and output data.

[0053] In some embodiments of the utility model, the CPU controller 4 also includes a monitoring unit 8, one end of the monitoring unit 8 is connected to the battery stack switches K1, K2, K3 of the battery stack group, and the other end is connected to the CPU processing unit 11; the monitoring unit 8 is used to monitor the voltage and current of each battery stack group branch 5, 6, 7, and adjust the switch state of each battery stack group branch according to the switch control signal sent by the CPU processing unit 11.

[0054] Specifically, the monitoring unit 8 uses a logic analyzer or oscilloscope or other device that can monitor circuit voltage and current and a switch control device. The monitoring unit 8 monitors the voltage and current of each battery stack branch. The CPU processing unit 11 determines whether each branch is damaged based on the voltage and current data of each branch, and generates a switch disconnect signal. At the same time, based on the output voltage collection of the monitoring unit 8 and the voltage difference of each branch, a voltage or current adjustment signal is generated to adjust the input voltage or current of a single branch to ensure that the voltage difference of each branch is within a normal range.

[0055] In some embodiments of the present invention, the CPU controller 4 further includes a sampling unit 9, one end of the sampling unit 9 is connected to the output end of each battery stack group branch, and the other end is connected to the CPU processing unit 11;

[0056] The sampling unit 9 is used to collect the voltage and current of each battery stack group branch, and adjust the switch state of the control circuit according to the control signal sent by the CPU processing unit 11.

[0057] Specifically, the sampling unit 9 is the same as the monitoring unit 8, and adopts a device that can monitor the output voltage and current and a switch control device; the sampling unit 9 collects the output voltage of each battery stack branch, and the CPU processing unit 11 determines the voltage difference of each branch based on the output voltage data of each branch, and generates a voltage or current adjustment signal to adjust the input voltage or current of the individual branch based on the voltage difference of each branch, and generates a control signal to control the switch to open or close.

[0058] In some embodiments of the present utility model, the CPU controller 4 further includes a trigger unit 10, one end of the trigger unit 10 is connected to the DC / DC converter 3, and the other end is connected to the CPU processing unit 11;

[0059] The trigger unit 10 is used to control the working state of the DC / DC converter 3 according to the trigger signal sent by the CPU processing unit 11 .

[0060] Specifically, the trigger unit 10 is a trigger control device that can control the converter according to input, feedback or real-time parameter trigger pulses. The CPU processing unit 11 compares the output voltage of the DC / DC converter 3 with the reference voltage based on the output voltage data of each branch and the current distribution signal of each branch, and generates feedback information. When the output voltage deviates from the reference voltage, the CPU processing unit 11 generates a trigger signal to control the conduction and cutoff of the MOS tube of the DC / DC converter 3, thereby achieving regulation of the output voltage.

[0061] In some embodiments of the present invention, the DC / DC converter is composed of three groups of DC / DC conversion units connected in parallel.

[0062] In order to better illustrate the utility model, Figure 3 As shown, Figure 3 The utility model provides a schematic diagram of the working process of the DC voltage conversion circuit of the all-vanadium liquid flow battery. First, the CPU processing unit 11 receives the monitoring data from the monitoring unit 8, and judges whether each branch is damaged according to the voltage and current information of each battery stack group branch in the monitoring data. If a branch is damaged, a disconnect switch signal is generated and sent to the monitoring unit 8. The switch of the corresponding branch is controlled by the monitoring unit 8 to disconnect it and process the branch; then, according to the output power supply and circuit data of each battery stack group branch collected by the sampling unit 9, the output voltage of each branch is compared with the preset voltage difference threshold. If the voltage difference between the branch voltages is within the normal range, a control signal is generated. The control signal is sent to the sampling unit 9, and the sampling unit 9 closes the first control circuit or the second control circuit switch according to the control signal, thereby forming a staggered parallel voltage circuit double closed-loop converter topology circuit; if the voltage difference between the branch voltages is not within the normal range, it means that the voltages between the branches are unbalanced, then a control signal is generated and sent to the sampling unit 9, and the sampling unit 9 disconnects the first control circuit or the second control circuit switch according to the control signal, controls the branches separately, and generates current distribution signals for the branches according to the voltage difference between the branches. The monitoring unit 8 generates input voltage or current adjustment signals between the branches according to the voltage difference between the branches, and adjusts the input voltage or current.

[0063] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present invention should be included in the protection scope of the present invention.

Claims

1. A DC voltage conversion circuit for an all-vanadium liquid flow battery, characterized in that: Including battery stack, control circuit, DC / DC converter and CPU controller; Wherein, the battery stack group includes a first battery stack group branch, a second battery stack group branch and a third battery stack group branch connected in parallel; The control circuit includes a first control circuit and a second control circuit; the first control circuit is connected to the output end of the first battery stack group branch and the output end of the second battery stack group branch; the second control circuit is connected to the output end of the second battery stack group branch and the output end of the third battery stack group branch; Each of the battery stack branches is connected in series with a bridge arm of a DC / DC converter via an energy storage inductor; The CPU controller is connected to each battery stack branch, the control circuit and the DC / DC converter.

2. The DC voltage conversion circuit of the all-vanadium liquid flow battery according to claim 1, characterized in that: Each of the battery stack group branches includes a plurality of battery stacks and battery stack switches connected in series; The input end of each battery stack group branch is connected in series with the battery stack switch to control the working state of each battery stack group branch.

3. The DC voltage conversion circuit of the all-vanadium liquid flow battery according to claim 2, characterized in that: One end of the first control circuit is connected to the output end of the first battery stack branch, and the other end is connected to the output end of the second battery stack branch. The first control circuit is used to disconnect and connect the first battery stack branch and the second battery stack branch.

4. The DC voltage conversion circuit of the all-vanadium liquid flow battery according to claim 3, characterized in that: One end of the second control circuit is connected to the output end of the second battery stack branch, and the other end is connected to the output end of the third battery stack branch. The second control circuit is used to disconnect and connect the second battery stack branch and the third battery stack branch.

5. The DC voltage conversion circuit of the all-vanadium liquid flow battery according to claim 4, characterized in that: The DC / DC converter is externally connected to a capacitor and a DC-to-AC inverter.

6. The DC voltage conversion circuit of the all-vanadium liquid flow battery according to claim 5, characterized in that: The CPU controller includes a CPU processing unit, which is used to receive monitoring data, generate a stack switch control signal for each stack group branch, receive the output voltage of each stack group branch, generate a control signal, and generate a trigger signal according to input and output data.

7. The DC voltage conversion circuit of the all-vanadium liquid flow battery according to claim 6, characterized in that: The CPU controller further comprises a monitoring unit, one end of which is connected to the stack switch of the stack group, and the other end of which is connected to the CPU processing unit; The monitoring unit is used to monitor the voltage and current of each battery stack group branch, and adjust the switch state of each battery stack group branch according to the switch control signal sent by the CPU processing unit.

8. The DC voltage conversion circuit of the all-vanadium redox flow battery according to claim 7, characterized in that: The CPU controller further comprises a sampling unit, one end of which is connected to the output end of each battery stack group branch, and the other end of which is connected to the CPU processing unit; The sampling unit is used to collect the output voltage and current of each battery stack group branch, and adjust and control the switch state of each control circuit according to the control signal sent by the CPU processing unit.

9. The DC voltage conversion circuit of the all-vanadium redox flow battery according to claim 8, characterized in that: The CPU controller further comprises a trigger unit, one end of which is connected to the DC / DC converter, and the other end of which is connected to the CPU processing unit; The trigger unit is used to control the working state of the DC / DC converter according to the trigger signal sent by the CPU processing unit.

10. The DC voltage conversion circuit of the all-vanadium redox flow battery according to claim 9, characterized in that: The DC / DC converter is composed of three groups of DC / DC conversion units connected in parallel.

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