Energy storage converter

Abstract

The utility model provides an energy storage converter. The energy storage converter comprises a plurality of DC side input ends A1, A2, A3,..., An; the H bridge consists of switching tubes Q1, Q2, Q3 and Q4; the switching tubes Qa2, Qa3,..., Qan are respectively connected with the direct current side input ends A2, A3,..., An and the negative electrode of the direct current end of the H bridge; the direct current side input end A1 is connected with the direct current end positive electrode of the H bridge; and the alternating current output end of the H bridge is used as the alternating current output end of the energy storage converter. The direct-current side input end A1 is connected with the positive electrode of a series direct-current power supply; the series direct-current power supply is formed by connecting n independent direct-current power supplies with the voltage of Vdc in series; and the direct current side input ends A2, A3,..., An are respectively connected with the negative electrode of each independent direct current power supply according to the potential from high to low. The scheme of the utility model is a hybrid topological structure combining multi-level direct-current voltage selection and the standard H bridge, and compared with a typical high-voltage direct-hanging converter formed by cascading a plurality of H bridges, the scheme of the utility model has the advantage that the usage amount of switch tubes is obviously reduced.

Description

Technical Field

[0001] This utility model relates to a bidirectional converter in an energy storage system, and more particularly to a novel high-voltage direct-connected bidirectional converter. Background Technology

[0002] A power conversion system (PCS) is a key device in an electrochemical energy storage system that connects a DC battery system to the AC power grid (and / or load), enabling bidirectional power conversion. It controls the charging and discharging process of the energy storage battery pack, converting AC to DC power, and can directly supply power to AC loads in the absence of a power grid. Traditional energy storage solutions mainly employ low-voltage boost technology, where a dedicated PCS is configured to form an energy storage unit for the battery pack, outputting AC voltage at the power frequency. Multiple energy storage units are connected in parallel and then boosted by a transformer before being connected to the grid. While this approach has advantages such as mature technology, high reliability, and simple maintenance, it also has drawbacks such as large footprint during deployment, reduced system efficiency due to the introduction of the power frequency transformer, and the potential for internal circulating currents when multiple battery packs are connected in parallel. In recent years, high-voltage direct-connected PCS has received increasing attention and application, especially in large-scale energy storage projects. Compared to traditional low-voltage PCS with step-up transformers, high-voltage direct-connect PCS connects directly to medium- and high-voltage power grids (e.g., 10kV or 35kV) via H-bridge cascading, eliminating the need for a power frequency transformer and achieving high-voltage AC waveform output through a multi-level topology. By eliminating the bulky power frequency transformer, this solution achieves higher efficiency and larger unit capacity, offering advantages such as small footprint, high efficiency, fast response, and high-quality AC waveform. However, it also introduces new technical challenges. For example, since each H-bridge consists of four switching transistors, the number of required transistors increases linearly with the number of series stages. The use of a large number of transistors leads to complex control circuitry, intricate control logic, and additional power consumption.

[0003] This invention addresses the technical challenges of the aforementioned high-voltage direct-connected PCS by proposing a novel energy storage converter. By using a new circuit topology, it achieves the functions of a high-voltage direct-connected PCS while significantly reducing the number of switching transistors, thereby simplifying the PCS's control circuitry and logic. Utility Model Content

[0004] This utility model proposes an energy storage converter, comprising: multiple DC-side input terminals A1, A2, A3, ..., An; an H-bridge composed of switching transistors Q1, Q2, Q3, and Q4; switching transistors Qa2, Qa3, ..., Qan respectively connected to the DC-side input terminals A2, A3, ..., An and the negative DC terminal of the H-bridge; the DC-side input terminal A1 is connected to the positive DC terminal of the H-bridge; and the AC output terminal of the H-bridge serves as the AC output terminal of the energy storage converter.

[0005] The H-bridge further includes a DC bus capacitor C1, which is connected in parallel between the positive and negative terminals of the H-bridge DC terminal; the switching transistors Q1, Q2, Q3, and Q4 form an H-type topology, wherein Q1 and Q2 form the upper bridge arm, Q3 and Q4 form the lower bridge arm, Q1 and Q3 are connected in series to form the left bridge arm, and Q2 and Q4 are connected in series to form the right bridge arm; the midpoint between the left and right bridge arms is led out to form the AC output terminal of the H-bridge.

[0006] The collectors of the upper bridge arm switches Q1 and Q2 are connected, serving as the positive DC terminal of the H-bridge; the emitters of the lower bridge arm switches Q3 and Q4 are connected, serving as the negative DC terminal of the H-bridge; in the left bridge arm, the emitter of the upper bridge arm switch Q1 is connected to the collector of the lower bridge arm switch Q3; in the right bridge arm, the emitter of the upper bridge arm switch Q2 is connected to the collector of the lower bridge arm switch Q4.

[0007] The DC input terminal A1 of the converter is connected to the positive terminal of a series DC power supply; the series DC power supply is composed of n independent DC power supplies with voltage Vdc connected in series; the DC input terminals A2, A3, ..., An are connected to the negative terminal of each independent DC power supply in descending order of potential.

[0008] The energy storage converter further includes: an auxiliary power module for providing auxiliary power to the gate driver and controller; a control unit consisting of a DSP / microcontroller, gate driver, and sensors, responsible for generating PWM modulation signals, current / voltage sampling, status monitoring, and fault diagnosis; and a communication unit for implementing remote monitoring and control protocol interfaces, including an RS-485 transceiver, a CAN bus transceiver, and an Ethernet interface. The controller communicates with the upper-level supervisory control and data acquisition system / BMS through these interfaces, supporting real-time data reporting and remote parameter adjustment.

[0009] The switching transistor is a high-voltage IGBT, and each IGBT is equipped with an isolated gate drive and a current / voltage measurement circuit. The current / voltage measurement circuit includes a Hall effect sensor or a magnetically shielded sensor. There is a reverse-parallel diode between the collector and emitter of each IGBT.

[0010] The IGBT is an Infineon FF1200R17IP5, and the gate driver uses an Infineon IR2x14 series chip, which can provide IGBT short circuit / undervoltage protection; the RS-485 transceiver is a TI ISO308x series; the DSP / microcontroller is a TI C2000 series or STM32H7 series chip.

[0011] The energy storage converter proposed in this invention is a hybrid topology combining multi-level DC voltage selection and standard H-bridge modulation. This structure aims to utilize the bipolar output capability of the H-bridge while increasing the number of output voltage stages by introducing an intermediate level, thereby improving output waveform quality and reducing harmonic content. Compared with a typical high-voltage direct-connected converter composed of multiple cascaded H-bridges, the present invention significantly reduces the number of switching transistors used.

[0012] Other features and advantages of this utility model will become clearer after reading the detailed description of the embodiments of this utility model in conjunction with the accompanying drawings. Attached Figure Description

[0013] To clearly illustrate the technical solution and embodiments of this utility model, the accompanying drawings are briefly described below. It should be noted that the drawings are primarily intended to explain the interconnections, structural features, and advantages of the various components of the device, and are not drawn to scale according to the actual dimensions of the device. Obviously, the drawings only relate to a limited set of embodiments and should not be construed as limiting the present utility model. Those skilled in the art can easily obtain new embodiments through formal variations based on these drawings.

[0014] Figure 1 This is a circuit diagram of a standard H-bridge;

[0015] Figure 2 This is the circuit topology diagram of a typical high-voltage direct-connected energy storage converter;

[0016] Figure 3 This is a circuit topology diagram of one embodiment of the present invention. Detailed Implementation

[0017] The specific embodiments of this utility model are described in detail below with reference to the accompanying drawings.

[0018] This invention proposes an energy storage converter designed to address the shortcomings of conventional solutions, such as a large number of switching transistors, complex control circuitry, and intricate control logic. High-voltage direct-connected energy storage converters typically employ a multi-stage cascaded H-bridge topology, distributing battery clusters to the DC side of the cascaded H-bridge converter, while its AC side is connected to the medium- or high-voltage power grid. Figure 1A typical H-bridge circuit is presented, consisting of a filter capacitor C1 and four insulated-gate bipolar transistors (IGBTs) with anti-parallel diodes (Q1-Q4). Specifically, it includes: a DC input terminal A, the circuit's DC power input, typically connected to a DC voltage source such as a battery pack or photovoltaic panel; a DC bus capacitor C1, connected in parallel to the DC input terminal; the core of the circuit consists of four power transistors forming an H-shaped topology, where Q1 and Q2 form the upper arm, Q3 and Q4 form the lower arm, Q1 and Q3 are connected in series to form the left arm, and Q2 and Q4 are connected in series to form the right arm; the midpoint between the left and right arms forms the AC output terminal B, outputting an AC voltage.

[0019] The capacitor C1 is used to stabilize the DC bus voltage, and the anti-parallel diode provides a current freewheeling path for the inductive load. By controlling the on / off combinations of the four switching transistors Q1-Q4, AC voltages of different polarities and amplitudes can be generated at the output terminal B.

[0020] The positive terminal of DC input terminal A is connected to the collectors of upper bridge arm switches Q1 and Q2; the negative terminal of DC input terminal A is connected to the emitters of lower bridge arm switches Q3 and Q4; the DC bus capacitor C1 is connected in parallel between the positive and negative terminals of DC input terminal A; in the left bridge arm, the emitter of upper bridge arm switch Q1 is connected to the collector of lower bridge arm switch Q3; in the right bridge arm, the emitter of upper bridge arm switch Q2 is connected to the collector of lower bridge arm switch Q4; one terminal of AC output terminal B is connected to the midpoint of the left bridge arm (i.e., the connection point between the emitter of Q1 and the collector of Q3); the other terminal of AC output terminal B is connected to the midpoint of the right bridge arm (i.e., the connection point between the emitter of Q2 and the collector of Q4); each anti-parallel diode is connected between the collector and emitter of the corresponding IGBT, with the anode connected to the emitter and the cathode connected to the collector.

[0021] Figure 2The paper further presents a topology for a high-voltage direct-connected PCS constructed by cascading multiple H-bridges. Each H-bridge's DC input is connected to an independent DC power supply with a voltage of Vdc, such as a battery cluster. The AC output ports of all H-bridges are connected sequentially, and the total output of the series connection constitutes the final AC output Vac of the entire circuit, which is the sum of the output voltages of all individual H-bridge units. This circuit constructs a cascaded H-bridge multilevel inverter by connecting multiple H-bridge inverter units with independent DC power supplies in series on the AC side. Each H-bridge unit can output positive, negative, or zero voltage. By controlling the switching state of each H-bridge unit, their individual output voltages can be superimposed to synthesize a stepped multilevel AC voltage waveform at the final output Vac. The advantage of this structure is its ease of modular expansion and the ability to synthesize output waveforms with higher voltage levels and lower harmonics. As shown in the figure, a PCS composed of n-stage H-bridges can output a stepped AC voltage waveform synthesized from 2*n+1 levels. It requires 4*n switching transistors to form a single-phase AC output, and 12*n switching transistors are needed to form a complete three-phase AC output.

[0022] The energy storage converter circuit topology proposed in this utility model is as follows: Figure 3 As shown, the DC side of this energy storage converter has multiple input terminals, such as A1, A2, A3, ..., A1 in the figure. n As shown, A1 is the positive DC terminal of an H-bridge, and A2, A3, ..., A n Each is controlled by an IGBT switch Q. a2 Q a3 ,…,Q an The negative DC terminal of the H-bridge, i.e., the DC input terminal A2 of the energy storage converter, is connected to the IGBT switch Q. a2 The collector, Q a2 The emitter of each power source is connected to the negative DC terminal of the H-bridge (the emitters of the lower bridge arm switches Q3 and Q4), and so on. The AC terminal of the H-bridge is the AC terminal Vac of the energy storage converter. When using this energy storage converter, n independent DC power supplies with voltage Vdc are connected in series. The highest potential point of the series connection, i.e., the positive terminal of the entire series power supply, is connected to the DC input terminal A1 of the energy storage converter. The negative terminals of each independent power supply, from the highest potential point to the lowest potential point, are sequentially connected to the DC input terminals A2, A3, ..., A1 of the energy storage converter. n The switching transistor Q connected to the series DC source a2 Q a3 ,…,Q an Different DC voltage levels relative to the negative bus can be generated at the DC input terminal of the energy storage converter by selectively turning it on / off. The H-bridge (Q1-Q4) on the right side is responsible for converting the DC voltage to AC voltage. This is achieved through coordinated control of the series switch Q on the left.a2 Q a3 ,…,Q an Together with the four switches (Q1-Q4) of the H-bridge on the right, a stepped AC voltage waveform synthesized from 2*n+1 levels can be output at the AC output terminal. The required number of switches is n+4, which is significantly less than the number of switches required by a high-voltage direct-connected PCS using multi-stage cascaded H-bridges.

[0023] The energy storage converter proposed in this invention is a hybrid topology combining multi-level DC voltage selection and standard H-bridge modulation. The left-side circuit is responsible for providing different DC voltage levels (including the total voltage and intermediate levels), and the right-side H-bridge uses these levels to synthesize the final multi-level AC output voltage Vac. This structure aims to utilize the H-bridge's ability to generate bipolar outputs while increasing the number of output voltage levels by introducing intermediate levels, thereby improving output waveform quality and reducing harmonic content.

[0024] Furthermore, the energy storage converter also includes: an auxiliary power supply module that provides auxiliary power (±15V, +5V) for the gate driver and controller, generating ±15V and +5V DC power through an isolated DC / DC module; a control unit consisting of a DSP / microcontroller, gate driver, and sensors, wherein the controller (e.g., TI C2000 series or STM32H7 series) is responsible for PWM modulation, current / voltage sampling, status monitoring, and fault diagnosis, and each IGBT switch is equipped with an isolated gate driver (with low-delay turn-off and short-circuit protection) and a current / voltage measurement circuit, wherein the current / voltage measurement circuit includes Hall or magnetically shielded sensors; and a communication unit for implementing remote monitoring and control protocol interfaces, integrating an isolated RS-485 transceiver (supporting Modbus-RTU), a CAN bus transceiver, an Ethernet interface module (supporting Modbus-TCP / HTTP or VPN remote access), etc., through which the controller communicates with the upper-level supervisory control and data acquisition system / BMS, supporting real-time data reporting and remote parameter adjustment.

[0025] The IGBT switching transistor is a high-voltage IGBT, such as the Infineon FF1200R17IP5, and the matching gate driver chip is the Infineon IR2x14 series chip, which provides IGBT short-circuit / undervoltage protection. The Modbus-RTU uses an isolated RS-485 transceiver, such as the TI ISO308x series, and the CAN communication uses an ISO11898 compatible CAN transceiver. The Ethernet interface module is a gigabit PHY chip, such as Marvell or TI's Ethernet PHY, with an RJ45 interface.

[0026] The description of this utility model is given for illustrative purposes only and is not intended to be exhaustive or to limit the utility model to the disclosed forms. The embodiments were chosen and described to better illustrate the principles and practical applications of the utility model, and to enable those skilled in the art to understand the utility model and design various embodiments with various modifications suitable for a particular purpose. All new embodiments that fall within the basic concept, construction principles, and spirit of this utility model, and are achieved through simple variations, modifications, equivalent substitutions, or improvements, should be included within the scope of protection of this utility model. The scope of this utility model is defined by the appended claims.

Claims

1. An energy storage converter, characterized in that, The energy storage converter includes: multiple DC-side input terminals A1, A2, A3, ..., A n A bridge consisting of switching transistors Q1, Q2, Q3, and Q4; connected to the DC input terminals A2, A3, ..., A4 respectively. n The switching transistor Q at the negative DC terminal of the H-bridge a2 Q a3 Q an The DC input terminal A1 is connected to the positive DC terminal of the H-bridge; the AC output terminal of the H-bridge serves as the AC output terminal of the energy storage converter.

2. The energy storage converter according to claim 1, characterized in that, The H-bridge further includes a DC bus capacitor C1, which is connected in parallel between the positive and negative terminals of the H-bridge DC terminal; the switching transistors Q1, Q2, Q3, and Q4 form an H-type topology, wherein Q1 and Q2 form the upper bridge arm, Q3 and Q4 form the lower bridge arm, Q1 and Q3 are connected in series to form the left bridge arm, and Q2 and Q4 are connected in series to form the right bridge arm; the midpoint between the left and right bridge arms is led out to form the AC output terminal of the H-bridge.

3. The energy storage converter according to claim 2, characterized in that, The collectors of the switching transistors Q1 and Q2 are connected, serving as the positive DC terminal of the H-bridge; the emitters of the switching transistors Q3 and Q4 are connected, serving as the negative DC terminal of the H-bridge; in the left bridge arm, the emitter of the switching transistor Q1 is connected to the collector of Q3; in the right bridge arm, the emitter of the switching transistor Q2 is connected to the collector of Q4.

4. The energy storage converter according to claim 1, characterized in that, The DC input terminal A1 of the converter is connected to the positive terminal of a series DC power supply; the series DC power supply is composed of n independent DC power supplies with voltage Vdc connected in series; the DC input terminals A2, A3, ..., An are connected to the negative terminal of each independent DC power supply in descending order of potential.

5. The energy storage converter according to claim 1, characterized in that, The energy storage converter further includes: an auxiliary power module for providing auxiliary power to the gate driver and controller; a control unit consisting of a DSP / microcontroller, gate driver, and sensors, responsible for generating PWM modulation signals, current / voltage sampling, status monitoring, and fault diagnosis; and a communication unit for implementing remote monitoring and control protocol interfaces, including an RS-485 transceiver, a CAN bus transceiver, and an Ethernet interface. The controller communicates with the upper-level supervisory control and data acquisition system / BMS through these interfaces, supporting real-time data reporting and remote parameter adjustment.

6. The energy storage converter according to any one of claims 1-5, characterized in that, The switching transistor is a high-voltage IGBT, and each IGBT is equipped with an isolated gate drive and a current / voltage measurement circuit. The current / voltage measurement circuit includes a Hall effect sensor or a magnetically shielded sensor. There is a reverse-parallel diode between the collector and emitter of each IGBT.

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