Equalization management architecture for energy storage system

Abstract

Provided in the present invention is an equalization management architecture for an energy storage system. The equalization management architecture comprises n energy storage units, each energy storage unit comprising an energy storage element unit or module, a transformer, a first switching tube, a second switching tube, a differential operational amplification circuit and a sampling and holding circuit, wherein each unit or module is sequentially connected in series; one end of a primary side of the transformer is connected to a positive electrode of the unit or module, and the other end of the primary side of the transformer is connected to a negative electrode of the unit or module and one end of a primary side of a transformer of the next energy storage unit by means of the first switching tube; one end of a secondary side of the transformer is sequentially connected to the differential operational amplification circuit and the sampling and holding circuit; an output end of each sampling and holding circuit is connected to a control unit; and the other end of the secondary side of the transformer is grounded by means of the second switching tube. In the solution of the present invention, when operating in an equalization mode, a current flows from a high-voltage end to a low-voltage end, such that a terminal voltage of each unit or module is between the highest voltage and the lowest voltage, thereby effectively reducing the energy loss of a system, and the terminal voltage of each unit or module can also be monitored.

Description

A balanced management architecture for energy storage systems Technical Field

[0001] The present invention relates to the field of power electronics technology, and in particular to a balanced management architecture for an energy storage system. Background Art

[0002] Energy storage components are important technologies and basic equipment supporting new power systems. Due to factors such as differences in production processes and equipment precision during production, different device temperature changes during use, and inconsistent environmental conditions during storage, energy storage components such as supercapacitors and lithium batteries will have certain differences in internal voltage, internal resistance, charge, self-discharge rate and other parameters of each energy storage component after being combined in series and parallel in actual use. This phenomenon will cause the smaller-capacity energy storage component monomers to reach the charging cut-off voltage first when the system is charging. When the energy storage component group is fully charged, the small-capacity energy storage component monomers will be overcharged. Similarly, when discharging, the small-capacity energy storage component monomers will be over-discharged. This will cause irreversible chemical reactions in the small-capacity energy storage component monomers, thereby damaging the system's service life, charge and discharge efficiency, and output power. The impact of such small-capacity energy storage component monomers on the overall capacity of the system is similar to the "barrel effect."

[0003] Due to the limitations of current material technology, it is difficult to significantly improve the performance of individual energy storage components in the short term. In order to improve the utilization efficiency and economic benefits of energy storage systems, balanced management of energy storage systems is an important issue. At present, there are two mainstream response measures for domestic and foreign manufacturers. One is to improve the production technology of energy storage components from the source to reduce the parameter differences of various types of devices produced; the other is to collect voltage, temperature and other data of the device through the management system during use and storage, balance it through the control circuit, and adjust the higher terminal voltage to drop based on the lower terminal voltage. However, this will undoubtedly bring about greater energy loss. Summary of the Invention

[0004] The present invention provides an energy storage system balancing management architecture. By transferring energy from energy storage element cells or modules (supercapacitors, lithium-ion batteries, etc.) with higher terminal voltages to energy storage element cells or modules with lower terminal voltages, the voltages of each cell or module gradually converge to a set voltage value in the middle, achieving non-dissipative active balancing and simultaneously realizing an isolated voltage measurement function.

[0005] The technical solution for achieving the purpose of the present invention is: a balanced management architecture for an energy storage system, comprising n energy storage units, each energy storage unit comprising an energy storage element monomer or module, a transformer, a first switching tube, a second switching tube, a differential operational amplifier circuit, and a sampling and holding circuit, wherein the monomers or modules of each energy storage unit are sequentially connected in series, one end of the primary side of the transformer is connected to the positive electrode of the monomer or module, the other end of the primary side of the transformer is connected to the negative electrode of the monomer or module and one end of the primary side of the transformer of the next energy storage unit through the first switching tube, one end of the secondary side of the transformer is sequentially connected to the differential operational amplifier circuit and the sampling and holding circuit, the output end of each sampling and holding circuit is connected to a control unit, and the other end of the secondary side of the transformer is grounded through the second switching tube;

[0006] The differential operational amplifier circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, and a differential amplifier; one end of the secondary side of the transformer is divided into three branches, which are respectively connected to one end of the first resistor, the third resistor, and the fifth resistor; the other end of the first resistor is connected to a common bus; the other end of the third resistor is connected to the positive input terminal of the differential amplifier; the other end of the fifth resistor is grounded; one end of the second resistor is grounded, and the other end is connected to the negative input terminal of the differential amplifier; a fourth resistor is connected between the negative input terminal and the output terminal of the differential amplifier; the output terminal of the differential amplifier is connected to the input terminal of the sample-and-hold circuit; and the output terminal of the sample-and-hold circuit is connected to the control unit;

[0007] The control unit includes a multi-channel analog switch, an A / D converter, a DPGA, a square wave generator, a delay unit, a first AND gate, and a second AND gate. The output ends of n sampling and holding circuits are connected to the input ends of the multi-channel analog switch, the output ends of the multi-channel analog switch are connected to the input ends of the A / D converter, the output ends of the A / D converter are connected to the DPGA, the DPGA outputs a duty cycle control signal and a frequency control signal to the square wave generator, the DPGA outputs a voltage sampling enable signal to the first AND gate input ends and the second AND gate input ends, the square wave generator outputs a signal to the control ends of n first switching tubes, the second AND gate input end and the delay unit, an isolation driver is provided between the signal output end of the square wave generator and the n first switching tubes, the signal output end of the delay unit is connected to the input end of the first AND gate, the output end of the first AND gate is connected to the input end of the A / D converter, the output end of the second AND gate is connected to the control ends of n second switching tubes, and an isolation driver is provided between the output end of the second AND gate and the n second switching tubes.

[0008] Compared with the prior art, the present invention has the following beneficial effects:

[0009] Compared with traditional large-capacity energy storage systems, when the balancing circuit operates in balancing mode, the current flows from the high-voltage end to the low-voltage end, which can increase the voltage of the energy storage element monomer or module with lower voltage and reduce the voltage of the energy storage element monomer or module with higher voltage, so that the terminal voltage of each energy storage element monomer or module is between the highest voltage and the lowest voltage, and energy flows from the high-voltage end to the low-voltage end, effectively reducing the system energy loss and eliminating the influence of the "barrel effect". At the same time, by controlling the change of the voltage sampling enable signal, the system can also switch the operating state and monitor the terminal voltage of each supercapacitor monomer. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0011] FIG1 is a schematic diagram of a structure of an energy storage system balancing management architecture provided by an embodiment of the present disclosure;

[0012] FIG2 is a schematic structural diagram of a control unit;

[0013] FIG3 is a waveform diagram of a voltage sampling enable signal, a first switch control signal, a second switch control signal, a delay unit output signal, a first AND gate output signal, and a common bus voltage signal. DETAILED DESCRIPTION

[0014] Embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although certain embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0015] The technical solution of the present invention is described in detail below with reference to specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0016] FIG1 is a balanced management architecture of an energy storage system provided by an embodiment of the present disclosure, including n energy storage units, each of which includes an energy storage element monomer or module, a transformer T k , the first switch tube S k1 , the second switch tube S k2, differential operational amplifier circuit and sampling and holding circuit, the monomers or modules of each energy storage unit are connected in series in sequence, and the transformer T k One end of the primary side is connected to the positive pole of the monomer or module, and the transformer T k The other end of the primary side passes through the first switch tube S k1 Transformer T that connects the negative pole of a single cell or module to the next energy storage unit k+1 At the primary side, transformer T k One end of the secondary side is connected to the differential operational amplifier circuit and the sampling and holding circuit in sequence. The output end of each sampling and holding circuit is connected to the control unit. The transformer T k The other end of the secondary side passes through the second switch tube S k2 grounding;

[0017] The differential operational amplifier circuit includes a first resistor R k1 , the second resistor R k2 , the third resistor R k3 , the fourth resistor R k4 , the fifth resistor R k5 and differential amplifier, one end of the transformer secondary side is divided into three branches, which are respectively connected to the first resistor R k1 , the third resistor R k3 , the fifth resistor R k5 One end, the first resistor R k1 The other end is connected to the common bus, and the third resistor R k3 The other end is connected to the positive input of the differential amplifier, and the fifth resistor R k5 The other end is grounded, and the second resistor R k2 One end is grounded, and the other end is connected to the negative input of the differential amplifier. A fourth resistor R is connected between the negative input and output of the differential amplifier. k4 , the output end of the differential amplifier is connected to the input end of the sampling and holding circuit, and the output end of the sampling and holding circuit is connected to the control unit;

[0018] The control unit includes a multi-channel analog switch, an A / D converter, a DPGA, a square wave generator, a delay unit, a first AND gate, and a second AND gate. The output ends of the n sampling and holding circuits are connected to the input ends of the multi-channel analog switch, the output ends of the multi-channel analog switch are connected to the input ends of the A / D converter, the output ends of the A / D converter are connected to the DPGA, the DPGA outputs a duty cycle control signal and a frequency control signal to the square wave generator, the DPGA outputs a voltage sampling enable signal to the first AND gate input end and the second AND gate input end, and the square wave generator outputs a signal to the n first switch tubes S 11 ~S n1 The control terminal, the second AND gate input terminal and the delay unit, the square wave generator signal output terminal and the n first switch tubes S 11 ~S n1An isolation driver is provided between the delay unit, the signal output end of the delay unit is connected to the first AND gate input end, the first AND gate output end is connected to the input end of the A / D converter, and the second AND gate output end is connected to n second switch tubes S 12 ~S n2 The control terminal, the second AND gate output terminal and n second switch tubes S 12 ~S n2 An isolation driver is provided between them.

[0019] The system operation process is as follows:

[0020] The system has a voltage balancing mode and a capacitor voltage measurement mode. When the DPGA sends a voltage sampling enable signal EN=0, the system operates in the voltage measurement mode, the second AND gate is closed, and the n second switch tubes S 12 ~S n2 In the off state, the square wave generator transmits a high level, and the n first switch tubes S 11 ~S n1 When turned on, the voltage of n energy storage element monomers or modules is sensed from the primary side to the secondary side through a transformer with a transformation ratio of 1:1. The secondary side voltage is sampled by the differential operational amplifier circuit and transmitted to the multi-channel analog switch through the sample and hold circuit. It is then input into the DPGA after passing through the AD converter. The voltage waveforms of each part of the circuit shown in Figure 3 can be obtained. To ensure the accuracy of the collected voltage, the AD converter is generally delayed by 1 / 4 of the switching cycle to achieve high-precision isolated collection. When the DPGA sends a voltage sampling enable signal EN = 1, the system operates in voltage balancing mode. When the square wave generator transmits a high level, the second AND gate is opened, and the n first switch tubes S 11 ~S n1 And n second switching tubes S 12 ~S n2 The secondary circuit is turned on, and the current flows from the high-voltage end to the low-voltage end. The voltage on the high-voltage side gradually decreases, and the voltage on the low-voltage side gradually increases. The voltage at each monomer or module end reaches the set intermediate value, realizing non-dissipative active voltage balancing.

Claims

1. A balanced management architecture for an energy storage system, characterized in that: The system comprises n energy storage units, each of which comprises an energy storage element monomer or module, a transformer, a first switching tube, a second switching tube, a differential operational amplifier circuit, and a sampling and holding circuit. The monomers or modules of each energy storage unit are sequentially connected in series. One end of the primary side of the transformer is connected to the positive electrode of the monomer or module, and the other end of the primary side of the transformer is connected to the negative electrode of the monomer or module and one end of the primary side of the transformer of the next energy storage unit through the first switching tube. One end of the secondary side of the transformer is sequentially connected to the differential operational amplifier circuit and the sampling and holding circuit. The output end of each sampling and holding circuit is connected to the control unit, and the other end of the secondary side of the transformer is grounded through the second switching tube. The differential operational amplifier circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, and a differential amplifier; one end of the secondary side of the transformer is divided into three branches, which are respectively connected to one end of the first resistor, the third resistor, and the fifth resistor; the other end of the first resistor is connected to a common bus; the other end of the third resistor is connected to the positive input terminal of the differential amplifier; the other end of the fifth resistor is grounded; one end of the second resistor is grounded, and the other end is connected to the negative input terminal of the differential amplifier; a fourth resistor is connected between the negative input terminal and the output terminal of the differential amplifier; the output terminal of the differential amplifier is connected to the input terminal of the sample-and-hold circuit; and the output terminal of the sample-and-hold circuit is connected to the control unit; The control unit includes a multi-channel analog switch, an A / D converter, a DPGA, a square wave generator, a delay unit, a first AND gate, and a second AND gate. The output ends of n sampling and holding circuits are connected to the input ends of the multi-channel analog switch, the output ends of the multi-channel analog switch are connected to the input ends of the A / D converter, the output ends of the A / D converter are connected to the DPGA, the DPGA outputs a duty cycle control signal and a frequency control signal to the square wave generator, the DPGA outputs a voltage sampling enable signal to the first AND gate input ends and the second AND gate input ends, the square wave generator outputs a signal to the control ends of n first switching tubes, the second AND gate input end and the delay unit, an isolation driver is provided between the signal output end of the square wave generator and the n first switching tubes, the signal output end of the delay unit is connected to the input end of the first AND gate, the output end of the first AND gate is connected to the input end of the A / D converter, the output end of the second AND gate is connected to the control ends of n second switching tubes, and an isolation driver is provided between the output end of the second AND gate and the n second switching tubes.

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