Electric energy equalization circuit for all-vanadium redox flow battery

Abstract

The utility model relates to an electric energy equalization circuit for an all-vanadium redox flow battery. The positive electrode of a first battery subsystem is connected with the negative electrode of a second battery subsystem through a manual switch Q1, a pre-charging circuit K1, the positive electrode end of a filter capacitor C1, a power switch S1, the positive electrode end of an inductor L1, a power switch S2, the positive electrode end of a filter capacitor C2, a pre-charging circuit K2 and a manual switch Q2; and the positive electrode of the second battery subsystem is connected with the negative electrode of the first battery subsystem through the manual switch Q2 and the manual switch Q1 to form a loop. The all-vanadium redox flow battery system overcomes the defects of non-uniform electric energy and voltage difference among the battery subsystems of the existing all-vanadium redox flow battery system, is simple in circuit structure, effectively solves the problem of energy imbalance among the battery subsystems on the premise of not depending on energy balance adjustment of power grid energy, improves the performance and operation reliability of the whole system, and prolongs the service life of the whole system.

Description

Technical Field

[0001] The utility model relates to the field of power energy storage technologies and equipment, and particularly relates to an electric energy balancing circuit for a vanadium redox flow battery. Background Art

[0002] As a new type of power energy storage technology, the vanadium redox flow battery has gradually become the first choice for large-scale power energy storage systems due to its advantages such as long service life, high energy efficiency, and good environmental adaptability. However, with the increase in the scale and complexity of the vanadium redox flow battery system, the imbalance problem between its battery subsystems has become increasingly prominent, which will directly affect the performance and service life of the overall battery system. The imbalance problem of the vanadium redox flow battery is mainly manifested in the differences in electrolyte concentration and cell voltage. During long-term operation, the charge and discharge states of each battery cell may be inconsistent, resulting in uneven distribution of vanadium ions in the electrolyte, thereby reducing the performance of the battery system and accompanied by capacity loss; in addition, the voltage difference between battery cells will cause some batteries to be overcharged and over-discharged, increasing the risk of battery aging and damage. Content of the Utility Model

[0003] The technical problem to be solved by the utility model is to overcome the defects of uneven electric energy and voltage difference between the battery subsystems of the existing vanadium redox flow battery system, and provide an electric energy balancing circuit for a vanadium redox flow battery. The circuit structure is simple, and without relying on the energy balancing regulation of grid energy, it effectively solves the energy imbalance problem between battery subsystems, and improves the performance, operation reliability and service life of the overall system.

[0004] The electric energy balancing circuit for a vanadium redox flow battery. The electric energy balancing circuit is connected between the first and second battery subsystems. The electric energy balancing circuit includes manual switches Q1 and Q2, a pre-charge switch circuit, a filter circuit, and an inductor circuit. The pre-charge switch circuit includes pre-charge circuits K1, power switches S1, S2, and pre-charge circuit K2. The filter circuit includes filter capacitors C1 and C2. The inductor circuit includes inductor L1. Among them, the positive electrode of the first battery subsystem is respectively connected to the negative electrode of the second battery subsystem through manual switch Q1, pre-charge circuit K1, the positive terminal of filter capacitor C1, power switch S1, the positive terminal of inductor L1, power switch S2, the positive terminal of filter capacitor C2, pre-charge circuit K2, and manual switch Q2. The positive electrode of the second battery subsystem is connected to the negative electrode of the first battery subsystem through manual switch Q2 and manual switch Q1 to form a loop. The positive terminal of the inductor L1 is connected between the power switches S1 and S2. The positive electrode of the filter capacitor C2 is connected between the pre-charge circuit K1 and the power switch S1. The positive electrode of the filter capacitor C3 is connected between the power switch S2 and the second pre-charge circuit K2. The negative electrodes of the filter capacitor C1, inductor L1, and filter capacitor C2 are all connected to the wire between the positive electrode of the second battery subsystem and the negative electrode of the first battery subsystem and are located between the manual switch Q2 and the manual switch Q1.

[0005] Further, both the pre-charge circuit K1 and the pre-charge circuit K2 include a switch connected in series on the connection line between the positive electrode of the first battery subsystem and the negative electrode of the second battery subsystem and a current-limiting resistor connected in parallel with the switch.

[0006] As a specific functional component implementation, both the power switches S1 and S2 are MOS transistors.

[0007] As a specific functional component implementation, both the power switches S1 and S2 are triodes.

[0008] Further, the positive and negative electrodes of the first battery subsystem are respectively connected to the manual switch Q1, and the positive and negative electrodes of the second battery subsystem are respectively connected to the manual switch Q2. Among them, the positive electrode side of the manual switch Q1 is connected to the collector of the power switch S1 through the pre-charge circuit K1 and the positive electrode of the filter capacitor C1. The emitter of the power switch S1 is connected to the collector of the power switch S2 through the positive electrode of the inductor L1. The emitter of the power device S2 is connected to the negative electrode side of the manual switch Q2 through the pre-charge circuit K2. The positive electrode side of the manual switch Q2 is connected to the negative electrode side of the manual switch Q1 through the capacitor C2, inductor L1, and the negative electrode of the capacitor C1.

[0009] Optimally, the negative electrodes of the capacitor C1, inductor L1, and capacitor C2 are connected and converge at one point.

[0010] The utility model relates to an electric energy balancing circuit for a vanadium redox flow battery, which overcomes the defects of uneven electric energy and voltage difference among battery subsystems in the existing vanadium redox flow battery system. With a simple circuit structure and without relying on grid energy for energy balancing regulation, it effectively solves the problem of energy imbalance among battery subsystems, and improves the performance, operation reliability and service life of the overall system. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The following further describes an electric energy balancing circuit for a vanadium redox flow battery of the utility model with reference to the drawings:

[0012] Figure 1 is the circuit diagram of the electric energy balancing circuit for the vanadium redox flow battery;

[0013] Figure 2 is the operation flow chart of the electric energy balancing circuit for the vanadium redox flow battery;

[0014] Figure 3 is the power flow direction of the charging state of the second battery subsystem in the electric energy balancing circuit for the vanadium redox flow battery;

[0015] Figure 4 is the balanced power flow direction of the charging state of the first battery subsystem in the electric energy balancing circuit for the vanadium redox flow battery. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] In the utility model, unless otherwise clearly defined and limited, terms such as "installation", "connection", "connection", "fixation" and other terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be directly connected, or indirectly connected through an intermediate medium, and can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the utility model can be understood according to specific situations.

[0017] In the description of the utility model, it should be understood that the orientation or positional relationship indicated by terms such as "left", "right", "front", "rear", "top", "bottom", "inside", "outside", etc. are all based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the utility model.

[0018] The following further describes the technical solution of the utility model with specific embodiments, but the protection scope of the utility model is not limited to the following embodiments.

[0019] Embodiment 1: As Figure 1As shown in the figure, the power energy balancing circuit for a all-vanadium redox flow battery is connected between the first and second battery subsystems. The power energy balancing circuit includes manual switches Q1 and Q2, a pre-charge switch circuit, a filter circuit, and an inductor circuit. The pre-charge switch circuit includes pre-charge circuits K1, power switches S1, S2, and pre-charge circuit K2. The filter circuit includes filter capacitors C1 and C2. The inductor circuit includes inductor L1. Among them, the positive electrode of the first battery subsystem is respectively connected to the negative electrode of the second battery subsystem through the manual switch Q1, the pre-charge circuit K1, the positive terminal of the filter capacitor C1, the power switch S1, the positive terminal of the inductor L1, the power switch S2, the positive terminal of the filter capacitor C2, the pre-charge circuit K2, and the manual switch Q2; the positive electrode of the second battery subsystem is connected to the negative electrode of the first battery subsystem through the manual switch Q2 and the manual switch Q1 to form a loop; the positive terminal of the inductor L1 is connected between the power switches S1 and S2, the positive electrode of the filter capacitor C2 is connected between the pre-charge circuit K1 and the power switch S1, the positive electrode of the filter capacitor C3 is connected between the power switch S2 and the second pre-charge circuit K2, and the negative electrodes of the filter capacitor C1, the inductor L1, and the filter capacitor C2 are all connected to the wire between the positive electrode of the second battery subsystem and the negative electrode of the first battery subsystem and are located between the manual switch Q2 and the manual switch Q1. Q1 and Q2 are switches for connecting the power energy balancing circuit; K1 and K2 are used to execute the start and stop of pre-charging; S1 realizes the power energy balancing between battery subsystems by adjusting the duty cycle, and judges the balancing situation of the two battery subsystems by detecting the current of L1 until it reaches a certain value.

[0020] Embodiment 2: In the power energy balancing circuit for a all-vanadium redox flow battery, both the pre-charge circuit K1 and the pre-charge circuit K2 include a switch connected in series on the connection line between the positive electrode of the first battery subsystem and the negative electrode of the second battery subsystem and a current-limiting resistor connected in parallel with the switch. It is used for large current limiting during the pre-charging process of the circuit. The remaining structures and components are as described in Embodiment 1 and will not be repeated.

[0021] Embodiment 3: In the power energy balancing circuit for a all-vanadium redox flow battery, both the power switches S1 and S2 are MOS transistors. The remaining structures and components are as described in Embodiment 2 and will not be repeated.

[0022] Embodiment 4: In the power - equalizing circuit for a vanadium redox flow battery, the power switches S1 and S2 are both triodes. The positive and negative electrodes of the first battery subsystem are respectively connected to the manual switch Q1, and the positive and negative electrodes of the second battery subsystem are respectively connected to the manual switch Q2. Among them, the positive - electrode side of the manual switch Q1 is connected to the collector of the power switch S1 through the pre - charge circuit K1 and the positive electrode of the filter capacitor C1. The emitter of the power switch S1 is connected to the collector of the power switch S2 through the positive electrode of the inductor L1. The emitter of the power device S2 is connected to the negative - electrode side of the manual switch Q2 through the pre - charge circuit K2. The positive - electrode side of the manual switch Q2 is connected to the negative - electrode side of the manual switch Q1 through the capacitors C2, L1, and the negative electrode of the capacitor C1. The negative electrodes of the capacitors C1, L1, and C2 are connected and converge at one point for easy access to the circuit. The remaining structures and components are as described in Embodiment 2 and will not be repeated.

[0023] During operation: The drive waveforms of the switching transistors S1 and S2 are complementary, that is, they are not both 0 at the same time. At any moment, there is one switching transistor with a drive of 0. At the same time, the duty cycle of the drive of the switching transistor S1 is limited to be adjustable between 0.4 - 0.6. In the case of system standby, the duty cycle of S1 is about 0.5. Affected by the SOC estimation algorithm of the flow battery, the voltages of the two flow - battery subsystems are not exactly the same, so the duty cycle of S1 will not be exactly equal to 0.5.

[0024] As Figure 2 shown, the operation of the entire circuit is affected by the SOCs of the two flow - battery subsystems, and the operation process is as follows:

[0025] S1: Close Q1 and Q2;

[0026] S2: Execute the pre - charge control of the systems K1 and K2. After completion, short - circuit and disconnect K1 and K2;

[0027] S3: The system operates in standby, controlling the current flowing through L1 to be 0. When the SOCs of the two battery subsystems are basically the same, the duty cycle of the switching transistor S1 is approximately equal to 0;

[0028] S4: As Figure 3 shown, the system continuously detects the SOCs of the two subsystems. When the SOC of the first battery subsystem exceeds the SOC of the second flow - battery subsystem by a certain threshold, dynamically adjust and increase the duty cycle of S1 until the current of L1 meets the adjusted expected value;

[0029] S5: Under the action of the equalizing circuit, the SOCs of the two battery subsystems gradually approach each other. After the difference in SOCs is less than a certain threshold, enter step S3.

[0030] As Figure 4 shown, when the SOC of the second battery subsystem exceeds the SOC of the first battery subsystem by a certain threshold, dynamically adjust and decrease the duty cycle of S1 until the current of L1 meets the adjusted expected value.

[0031] The power energy balancing circuit for a vanadium redox flow battery overcomes the defects of uneven power energy and voltage differences among battery subsystems in the existing vanadium redox flow battery system. With a simple circuit structure and without relying on grid energy for energy balancing regulation, it effectively solves the problem of energy imbalance among battery subsystems, and improves the performance, operation reliability and service life of the overall system.

[0032] The above description shows the main features, basic principles and advantages of the present utility model. For those skilled in the art, it is obvious that the present utility model is not limited to the details of the above exemplary embodiments or examples, and without departing from the spirit or basic features of the present utility model, the present utility model can be implemented in other specific forms. Therefore, the above embodiments or examples should be regarded as exemplary and non-limiting. The scope of the present utility model is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present utility model. Any reference signs in the claims should not be construed as limiting the claimed rights.

[0033] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An energy balancing circuit for an all-vanadium liquid flow battery, characterized in that: The energy balancing circuit is connected between the first and second battery subsystems. The energy balancing circuit includes manual switches Q1 and Q2, a pre-charging switch circuit, a filter circuit and an inductor circuit. The pre-charging switch circuit includes a pre-charging circuit K1, a power switch S1, a power switch S2, and a pre-charging circuit K2. The filter circuit includes filter capacitors C1 and C2. The inductor circuit includes an inductor L1. The positive electrode of the first battery subsystem is connected to the negative electrode of the second battery subsystem through the manual switch Q1, the pre-charging circuit K1, the positive terminal of the filter capacitor C1, the power switch S1, the positive terminal of the inductor L1, the power switch S2, the positive terminal of the filter capacitor C2, the pre-charging circuit K2, and the manual switch Q2; the positive electrode of the second battery subsystem is connected to the negative electrode of the first battery subsystem through the manual switch Q2 and the manual switch Q1 to form a loop; The positive terminal of the inductor L1 is connected between the power switches S1 and S2, the positive terminal of the filter capacitor C2 is connected between the pre-charging circuit K1 and the power switch S1, the positive terminal of the filter capacitor C3 is connected between the power switch S2 and the second pre-charging circuit K2, and the negative terminals of the filter capacitor C1, the inductor L1, and the filter capacitor C2 are all connected to the line between the positive terminal of the second battery subsystem and the negative terminal of the first battery subsystem, and are located between the manual switch Q2 and the manual switch Q1.

2. The energy balancing circuit for all-vanadium liquid flow battery according to claim 1 is characterized in that: The pre-charging circuit K1 and the pre-charging circuit K2 both include a switch connected in series to the connection line between the positive electrode of the first battery subsystem and the negative electrode of the second battery subsystem, and a current limiting resistor connected in parallel to the switch.

3. The energy balancing circuit for all-vanadium liquid flow battery according to claim 2 is characterized in that: The power switches S1 and S2 are both MOS tubes.

4. The energy balancing circuit for all-vanadium liquid flow battery according to claim 2 is characterized in that: The power switches S1 and S2 are both triodes.

5. The energy balancing circuit for all-vanadium liquid flow battery according to claim 4 is characterized in that: The positive and negative electrodes of the first battery subsystem are respectively connected to the manual switch Q1, and the positive and negative electrodes of the second battery subsystem are respectively connected to the manual switch Q2, wherein the positive electrode side of the manual switch Q1 is connected to the collector of the power switch S1 via the pre-charging circuit K1, the positive electrode of the filter capacitor C1 is connected to the collector of the power switch S1, the emitter of the power switch S1 is connected to the collector of the power switch S2 via the positive electrode of the inductor L1, the emitter of the power device S2 is connected to the negative electrode side of the manual switch Q2 via the pre-charging circuit K2, and the positive electrode side of the manual switch Q2 is connected to the negative electrode side of the manual switch Q1 via the capacitor C2, the inductor L1, and the negative electrode of the capacitor C1.

6. The energy balancing circuit for all-vanadium liquid flow battery according to claim 1 is characterized in that: The negative electrodes of the capacitor C1 , the inductor L1 , and the capacitor C2 are connected and converged at one point.

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