Switching circuit for 0 V starting of zinc-bromine flow battery

Abstract

The utility model discloses a switching circuit for 0V starting of a zinc-bromine flow battery, which is characterized in that firstly, 220V single-phase alternating current is input through an alternating current input port, the 220V alternating current is converted into 50V alternating current through a step-down transformer, then the 50V alternating current is rectified and filtered into 48V direct current through a rectifier, and the 48V direct current is connected with the step-down transformer. Finally, the positive electrode and the negative electrode of the 48V direct current are connected to the positive electrode and the negative electrode of a bus bar of the zinc-bromine flow battery respectively, when charging is started, the voltage of the battery can be rapidly increased by the direct current to be larger than the starting range value of a converter, and once the voltage of the battery reaches the starting range of the converter, a disconnection switch is turned off; the common converter can start to charge the zinc-bromine flow battery; according to the invention, the step-down transformer and the rectifier are added, the alternating current is converted into the direct current, and the direct current is input into the zinc-bromine flow battery busbar after step-down and rectification treatment, so that the charging starting process of the battery is effectively controlled, and the charging efficiency and safety are improved.

Description

Technical Field

[0001] The invention belongs to the field of zinc-bromine liquid flow batteries, and in particular relates to a switch circuit for 0V starting of zinc-bromine liquid flow batteries. Background Art

[0002] With the rapid development of renewable energy, photovoltaic power generation, as an important form of renewable energy, has been widely used. In photovoltaic power generation systems, photovoltaic energy storage systems play a vital role. They can store and regulate the electricity generated by photovoltaic power generation to better adapt to the needs of the power grid.

[0003] At present, zinc-bromine flow battery, as an emerging energy storage technology, has the advantages of high energy density, long life and environmental friendliness. It is safe, environmentally friendly and has no risk of combustion and explosion, making it suitable for application in energy storage systems.

[0004] A major feature that distinguishes zinc-bromine flow batteries from other energy storage batteries is that they can be deeply charged and discharged, that is, the battery voltage can be reduced to 0V or the battery voltage is also 0V in the initial state, which requires the corresponding charging and discharging equipment to also have the function of 0V start-up.

[0005] However, most of the "charging and discharging equipment" (inverters) on the market are designed for lead-acid batteries and lithium batteries. Lead-acid batteries and lithium batteries do not allow deep discharge, that is, they will not be discharged to 0V. Therefore, the general-purpose inverters on the market cannot be directly used for zinc-bromine batteries. General-purpose inverters can only be used when the voltage of zinc-bromine batteries reaches a certain value.

[0006] Therefore, in order to achieve 0V start-up, the inverters currently used in zinc-bromine flow batteries are all specially customized equipment, and technically use pre-charging resistors on the AC or DC side to step down the voltage. This has low efficiency because the current passing through the pre-charging resistors will cause energy to be lost in the form of heat, especially in the early stages of charging, when the current is large. This loss is more significant. In addition, the cost is high: since it is a customized product, the cost is more than 30% higher than that of a general-purpose inverter, and there are very few options. Only one or two customization companies can be found on the market, and there is almost no choice.

[0007] Chinese patent CN116247763A discloses an energy storage converter circuit and control method for 0V start of a flow battery. By adding a pre-charge resistor on the AC side, voltage adjustment and management are indirectly achieved through the design of the energy storage converter circuit (pre-charge resistor). Although it is also a start-up method, multiple resistors are connected in series in the circuit to limit the size of the initial charging voltage and current, protect the circuit and reduce the current impact at the initial start-up. However, the disadvantage of this method is that the energy loss is serious: the pre-charge resistor will generate heat loss during the current limiting process, which converts the electrical energy into heat and consumes it, and does not participate in the battery charging process.

[0008] Chinese patent CN117614303A discloses a flow battery energy storage converter control system and method, which uses a DC-DC chopper module and a bidirectional AC-DC power module as well as a DC and AC pre-charging module to achieve fine control and voltage reduction of the battery. It is a method of adding a pre-charging resistance module on the DC side. This method also causes the current energy to be lost in the form of heat, especially in the early stage of charging, when the current is large, this loss is more significant. And the control system needs to be used during the full period of charge and discharge of the flow battery, so safety protection measures are required, resulting in a complex structure (addition of DC power supply arrester, DC circuit breaker, DC fuse, reactor, AC filter, AC circuit breaker, AC power supply arrester).

[0009] The above problems seriously limit the application and promotion of zinc-bromine flow batteries. Summary of the invention

[0010] In view of the above problems, the purpose of the present invention is to propose a switching circuit for 0V starting of zinc-bromine liquid flow batteries, using a short-time boost device to increase the voltage of the 0V zinc-bromine battery to above the minimum voltage of lead-acid batteries and lithium batteries in a short time, so that a general-purpose inverter can also be used in the application of zinc-bromine batteries.

[0011] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a switching circuit for 0V starting of a zinc-bromine liquid flow battery, comprising an AC input port, a step-down transformer connected to the AC input port, a rectifier connected to the step-down transformer, and a zinc-bromine liquid flow battery connected to the rectifier.

[0012] The AC power input port is used to transmit 220V AC power to the step-down transformer, and the step-down transformer is used to convert the received 220V AC power into 50V AC power and transmit it to the rectifier. The rectifier rectifies and filters the 50V AC power into 48V DC power through an internal rectifier bridge, and transmits it to the zinc-bromine liquid flow battery. The zinc-bromine liquid flow battery receives 48V DC power through the DC bus bar.

[0013] When charging begins, the DC power will quickly raise the voltage of the zinc-bromine flow battery to above the starting range of the inverter. Once the voltage of the zinc-bromine flow battery reaches the starting range of the inverter, the inverter can start charging the zinc-bromine flow battery.

[0014] After the zinc-bromine flow battery is started, the starting circuit is disconnected by a switching device to complete the 0V starting process. The switching device is a relay that controls the on and off of the starting circuit. When the DC bus voltage of the zinc-bromine flow battery reaches the operating voltage, the zinc-bromine flow battery can be charged with a general-purpose inverter.

[0015] The switch circuit for 0V start-up of zinc-bromine liquid flow battery proposed by the present invention has the following beneficial effects:

[0016] 1. The method is simple: the present invention adds a step-down transformer and a rectifier, converts AC power into DC power, and inputs the DC power into the zinc-bromine liquid flow battery busbar after step-down and rectification, thereby effectively controlling the charging start-up process of the battery and improving the charging efficiency and safety.

[0017] 2. Low cost: The present invention does not require a complex control system and external bulky equipment, avoids damage to the battery caused by high current, simplifies the circuit design, does not require the addition of multiple converters, reduces costs and maintenance difficulties, and has good economy and practicality.

[0018] 3. Low energy loss: The step-down transformer in the present invention adjusts the input and output voltages through the principle of electromagnetic induction, and achieves low loss during the conversion process through the combination of the step-down transformer and the rectifier.

[0019] 4. Fast starting speed: The 0V starting method proposed in the present invention can realize the fast charging and starting of the zinc-bromine liquid flow battery, so that it can reach the working voltage in a short time, thereby improving the availability and reliability of the battery.

[0020] 5. Safety and stability: The present invention controls the on-off of the current through a relay, ensuring the stable charging of the zinc-bromine flow battery after startup, thereby improving the stability and reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of a switch circuit for 0V starting of a zinc-bromine flow battery in the present invention. DETAILED DESCRIPTION

[0022] In order to better understand the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0023] like Figure 1 As shown, a schematic diagram of a switching circuit for 0V startup of a zinc-bromine liquid flow battery includes an AC power input port (L-①.N-②), a step-down transformer -Tq connected to the AC power input port (L-①.N-②), a rectifier bridge -VQ connected to the step-down transformer -Tq, and a zinc-bromine liquid flow battery DC busbar (BUS+ and BUS-) connected to the rectifier bridge -VQ.

[0024] During use, close switch K, 220V AC is input through the AC input port (L-①.N-②) and the step-down transformer-Tq is converted into 50V AC and output from ③④, and then rectified and filtered by the rectifier bridge-VQ to 48V DC. The DC is input into the DC busbar (BUS+ and BUS-) of the zinc-bromine liquid flow battery, so that its DC bus voltage rises to the working voltage, thereby starting the charging of the zinc-bromine liquid flow battery.

[0025] When charging begins, the DC power will quickly increase the voltage of the zinc-bromine flow battery to above the starting range of the inverter. When the DC bus voltage of the zinc-bromine flow battery reaches the operating voltage, the zinc-bromine flow battery can be charged with a general-purpose inverter.

[0026] Preferably, after the zinc-bromine flow battery is started, the starting circuit is disconnected by a switching device to complete the 0V starting process. The switching device is a relay for controlling the on and off of the starting circuit. Subsequently, a general converter is used to charge the zinc-bromine flow battery.

[0027] As a preferred embodiment of this embodiment, the step-down transformer is a toroidal transformer BOD-300VA.

[0028] As a preferred embodiment of this embodiment, the rectifier is a rectifier QL100A1600V.

[0029] Through the above specific implementation methods, the present invention provides a simple and efficient 0V starting circuit for zinc-bromine liquid flow batteries, which solves the problem that zinc-bromine liquid flow batteries cannot be started in the 0V state and improves the reliability and applicability of zinc-bromine liquid flow batteries.

[0030] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A switching circuit for 0V starting of a zinc-bromine flow battery, characterized in that: It includes an AC power input port, a step-down transformer connected to the AC power input port, a rectifier connected to the step-down transformer, and a zinc-bromine liquid flow battery connected to the rectifier; The AC input port is used to transmit 220V AC to the step-down transformer, and the step-down transformer is used to convert the received 220V AC into 50V AC and transmit it to the rectifier. The rectifier rectifies and filters the 50V AC into 48V DC through an internal rectifier bridge, and transmits it to the zinc-bromine liquid flow battery. The zinc-bromine liquid flow battery receives 48V DC through the DC busbar; The switch circuit also includes a relay. After the zinc-bromine liquid flow battery is started, the starting circuit is disconnected by the relay to complete the 0V starting process.

2. A switch circuit for 0V start-up of a zinc-bromine flow battery according to claim 1, characterized in that: The relay is used to control the on-off of the starting circuit. When the DC bus voltage of the zinc-bromine liquid flow battery reaches the operating voltage, the zinc-bromine liquid flow battery can be charged using a universal converter.

3. A switch circuit for 0V start-up of a zinc-bromine liquid flow battery according to claim 1, characterized in that: The step-down transformer is a toroidal transformer BOD-300VA.

4. A switch circuit for 0V start-up of a zinc-bromine liquid flow battery according to claim 1, characterized in that: The rectifier is a QL100A1600V rectifier.

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