A charging and discharging control circuit and energy storage system

Abstract

This invention relates to the field of energy storage technology, mainly providing a charging and discharging control circuit and an energy storage system. The circuit includes a control module connected to a battery and an inverter, a charging switch module and a discharging switch module connected to the control module, the charging switch module being connected to the discharging switch module, the charging switch module also being connected to the battery, and the discharging switch module being connected to both the inverter and a heater mounted on the battery. Specifically, when the battery has sufficient remaining capacity and a low temperature, the control module promptly cuts off the charging channel and opens the discharging heating channel, thereby preventing damage to the battery caused by continued charging at low temperatures. Simultaneously, the inverter heats the battery to a suitable temperature range, extending the battery's cycle life. Furthermore, by dual monitoring of the current in the discharging channel and the heater, when the inverter output current exceeds the actual input current of the heater, the discharging channel is quickly shut off, effectively preventing safety risks such as over-discharge of the battery.

Description

Technical Field

[0001] This invention relates to the field of energy storage, and more particularly to a charging and discharging control circuit and an energy storage system. Background Technology

[0002] In the field of new energy storage, lithium batteries are widely used in high-voltage energy storage systems due to their advantages such as high energy density and long cycle life. However, lithium batteries pose significant safety risks when used in low-temperature environments. When charging lithium batteries at low temperatures, lithium plating is highly likely to occur, which may puncture the internal separator of the cell, leading to a short circuit and seriously threatening the safe operation of the energy storage system. Furthermore, continuously heating batteries at low temperatures using their own energy can easily lead to over-discharge, causing irreversible degradation of cell performance, affecting battery life, and even posing safety hazards. Summary of the Invention

[0003] This invention provides a charging and discharging control method and an energy storage system, aiming to solve the technical problems of lithium batteries being prone to over-discharging, having low safety, and low reliability during charging in the prior art.

[0004] To solve the above-mentioned technical problems, one technical solution adopted in the embodiments of the present invention is: to provide a charging and discharging control circuit, comprising:

[0005] A control module is used to connect the battery and to communicate with the inverter;

[0006] The system includes a charging switch module and a discharging switch module. The control terminals of both the charging switch module and the discharging switch module are connected to the control module. The first output terminal of the charging switch module is connected to the first output terminal of the discharging switch module. The second output terminal of the charging switch module is used to connect to the battery. The second output terminal of the discharging switch module is used to connect to the inverter and to connect to the heater disposed on the battery.

[0007] The control module is used to obtain the remaining capacity and temperature of the battery. When the remaining capacity is less than a first preset capacity and the temperature is less than a preset temperature, the control module is used to output a first drive signal to the charging switch module to turn off the charging switch module, thereby turning off the output current of the inverter to the charging channel of the battery. The control module is also used to output a second drive signal to the discharging switch module to turn on the discharging switch module, thereby turning on the discharging channel from the battery and the discharging switch module to the heater, and the output current of the inverter flows to the heater.

[0008] Optionally, the charging switch module includes at least one first body diode connected in series with the first output terminal and the second output terminal of the charging switch module, and the discharging switch module includes at least one second body diode connected in series with the first output terminal and the second output terminal of the discharging switch module.

[0009] The battery, at least one first body diode, and the activated discharge switch module form the discharge channel, and the at least one second body diode, the activated charging switch module, and the battery form the charging channel.

[0010] Optionally, the charging switch module further includes at least two charging power transistors, each of which is provided with a first body diode; the discharging switch module includes at least two discharging power transistors, each of which is provided with a second body diode;

[0011] The control terminals of all the charging power transistors and all the discharging power transistors are connected to the control module. The output terminals of all the charging power transistors are connected in series to form a first series structure, and all the discharging power transistors are connected in series to form a second series structure. The output terminal of the charging power transistor at the beginning of the first series structure is used to connect to the battery. The charging power transistor at the end of the first series structure is connected to the output terminal of the discharging power transistor at the beginning of the second series structure. The output terminal of the discharging power transistor at the end of the second series structure is used to connect to the inverter.

[0012] When the charging power transistor and the discharging power transistor receive the first driving signal and the second driving signal respectively, the charging power transistor is turned off and the discharging power transistor is turned on, and the discharge current of the battery flows from the first body diode on each of the charging power transistors and the discharging power transistor to the heater.

[0013] Optionally, the charging switch module further includes at least two first resistors, and the discharging switch module further includes at least two second resistors; the number of first resistors is the same as the number of charging power transistors, and the number of second resistors is the same as the number of discharging power transistors.

[0014] Each of the first resistors is connected to the output terminal of each of the charging power transistors, and each of the second resistors is connected to the output terminal of each of the discharging power transistors.

[0015] The at least two first resistors are used to balance the voltage at the output terminals of all the charging power transistors of the charging switch module when it is turned off, and the at least two second resistors are used to balance the voltage at the output terminals of all the discharging power transistors of the discharging switch module when it is turned off.

[0016] Optionally, the formula for calculating the number of charging power transistors and the number of discharging power transistors is as follows:

[0017] n≥V Batmax / V MOS_DS ;

[0018] Where n is the total number of the charging power transistors and the discharging power transistors, V Batmax V is the voltage when the battery is fully charged. MOS_DS This is the withstand voltage value of the power transistor.

[0019] Optionally, the charging and discharging control circuit further includes a relay, the first end of which is connected to the control module, and the second and third ends of which are respectively connected to the second output terminal of the charging switch module and the second output terminal of the discharging switch module; before the discharging switch module or the charging switch module is turned on, the relay is used to control the discharging switch module and the charging switch module to be turned off.

[0020] Optionally, when the remaining capacity is less than a first preset power and the temperature is less than a preset temperature, the control module is further configured to send a pulse signal to the first terminal of the relay to control the relay to engage. After the relay engages for a first preset time, the control module is further configured to send the first drive signal and the second drive signal to the charging switch module and the discharging switch module respectively, and then send a pulse signal to the first terminal of the relay to control the relay to disengage.

[0021] When the remaining capacity is less than the first preset power and the temperature is greater than the preset temperature, the control module is further configured to send a pulse signal to the first terminal of the relay to control the relay to engage. After the relay engages, the control module is further configured to send a third drive signal to the discharge switch module to control the discharge switch module to turn off; wherein, the second preset power is less than or equal to the first preset power.

[0022] Optionally, when the discharge switch module is turned on and the heater is heating, when the inverter is connected to a load, the control module is also used to control the charging switch module to turn on for a second preset time, and then the control module is also used to send a pulse signal to the relay to control the relay to engage.

[0023] Optionally, when the remaining capacity is less than a first preset charge and the temperature is less than a preset temperature, the control module is further configured to detect a third current value input to the heater and a second current value on the discharge channel; when the first current value of the inverter's output current is greater than the third current value, the control module is further configured to output a third drive signal to the discharge switch module to control the discharge switch module to turn off, thereby controlling the shutdown of the discharge channel from the battery, the discharge switch module to the heater.

[0024] To solve the above-mentioned technical problems, another technical solution adopted in the embodiments of the present invention is to provide an energy storage system, the energy storage system comprising:

[0025] A battery, wherein a heater and a temperature detection element for detecting the temperature of the battery are provided on the battery;

[0026] Inverter, used to connect the power grid and the load;

[0027] As described above, in the charge / discharge control circuit, the temperature detection element is connected to the control module, and the charge / discharge control circuit is used to control the charging and discharging process of the battery; and

[0028] The current detection module is connected to the second output terminal of the inverter and the discharge switch module, and is used to detect the current value and current direction of the inverter.

[0029] Unlike related technologies, this invention provides a charging and discharging control circuit and an energy storage system. The circuit includes: a control module for connecting to the battery and for communicating with an inverter; a charging switch module and a discharging switch module, wherein the control terminals of the charging switch module and the discharging switch module are both connected to the control module; a first output terminal of the charging switch module is connected to a first output terminal of the discharging switch module; a second output terminal of the charging switch module is used to connect to the battery; and a second output terminal of the discharging switch module is used to connect to the inverter and for connecting a heater disposed on the battery.

[0030] Specifically, when the battery has sufficient remaining capacity (greater than the first preset capacity) and a low temperature (less than the preset temperature), the control module can promptly cut off the charging channel and open the discharge heating channel to avoid damage to the battery caused by continuing to charge at low temperatures. At the same time, the inverter heats up the battery temperature to a suitable range, extending the battery cycle life.

[0031] By monitoring both the discharge channel and the heater current, the discharge channel can be quickly shut off when the inverter output current exceeds the actual input current of the heater, effectively preventing safety risks such as over-discharge of the battery. Attached Figure Description

[0032] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0033] Figure 1 This is a schematic diagram of an application scenario provided by an embodiment of the present invention;

[0034] Figure 2 This is a structural block diagram of a charging and discharging control circuit provided in an embodiment of the present invention;

[0035] Figure 3a This is a structural block diagram of a charge / discharge control circuit provided in another embodiment of the present invention;

[0036] Figure 3b This is a schematic diagram of the current flow in a charging and discharging control circuit provided in an embodiment of the present invention;

[0037] Figure 3c This is a schematic diagram of the current flow direction in another charging and discharging control circuit provided in an embodiment of the present invention;

[0038] Figure 4 This is a circuit diagram of a charging and discharging control circuit provided in an embodiment of the present invention;

[0039] Figure 5a This is a circuit diagram of a charge / discharge control circuit provided in another embodiment of the present invention;

[0040] Figure 5b This is a schematic diagram of the current flow direction of a charging and discharging control circuit under load, provided in an embodiment of the present invention.

[0041] Figure 5c This is a schematic diagram of the current flow direction of another charging and discharging control circuit under load, provided in an embodiment of the present invention;

[0042] Figure 5d This is a schematic diagram of the current flow direction when the charging and discharging control circuit is under load, as provided in another embodiment of the present invention. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0044] It should be noted that, unless otherwise specified, the various features in the embodiments of the present invention can be combined with each other, and all are within the protection scope of the present invention. Furthermore, although functional modules are divided in the device schematic diagram and a logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in a different module division or in a different order than that shown in the device schematic diagram or the flowchart.

[0045] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items.

[0046] Please see Figure 1 , Figure 1 This is a schematic diagram of an application scenario provided by an embodiment of the present invention, such as... Figure 1 As shown, this application scenario includes an energy storage system 100, a power grid 200, and a load 300, wherein the energy storage system 100 is connected to the power grid 200 and / or the load 300. The energy storage system 100 is used to charge based on the input voltage of the power grid 200; and when the energy storage system 100 is connected to the load 300, it supplies power to the load 300 based on the stored voltage.

[0047] Among them, such as Figure 1 As shown, the energy storage system 100 includes a battery 10, an inverter 20, a charge / discharge control circuit 30, and a current detection module 40. The battery 10 is equipped with a heater 11 and a temperature detection element (not shown) for detecting the temperature of the battery 10. The charge / discharge control circuit 30 is connected to the battery 10 and the current detection module 40, and is also connected to the heater 11 and the temperature detection element. The current detection module 40 is also connected to the inverter 20 and the charge / discharge control circuit 30. The inverter 20 is also connected to either the power grid 200 or the load 300. Inverter 20 can convert the energy provided by grid 200 and output it to battery 10. The energy of battery 10 can be output to inverter 20 and then provided by inverter 20 to load 300 or connected to grid 200. During the energy exchange process between inverter 20, grid 200, battery 10 and load 300, the charge and discharge control circuit 30 is used to control the charge and discharge process of battery 10, and the current detection module 40 is used to detect the current value and current direction of inverter 20.

[0048] In some embodiments, the heater 11 may be a heating device such as a thermistor or a thin-film heater. The temperature sensing element may be, but is not limited to, a temperature sensor that senses temperature.

[0049] In other embodiments, the current detection module may be a device that detects current values, such as a Hall element or a current transformer.

[0050] Please see Figure 2 , Figure 2 This is a structural block diagram of a charging and discharging control circuit provided in an embodiment of the present invention, as shown below. Figure 2 As shown, the charge / discharge control circuit 30 includes a control module 31, a charging switch module 32, and a discharging switch module 33.

[0051] The control module 31 is used to connect the battery 10 and to communicate with the inverter 20. The control module 31 is a BMS control chip. The battery 10 is equipped with a temperature sensor connected to the BMS control chip, which can obtain the battery's remaining capacity and temperature. When the remaining capacity is less than a preset threshold, the control module 31 sends a charging signal to the inverter 20. Upon receiving the charging signal, the inverter 20 obtains energy from the grid 200 for subsequent output.

[0052] The control terminal of the charging switch module 32 and the control terminal of the discharging switch module 33 are both connected to the control module 31. The first output terminal of the charging switch module 32 is connected to the first output terminal of the discharging switch module 33. The second output terminal of the charging switch module 32 is used to connect to the battery 10. The second output terminal of the discharging switch module 33 is used to connect to the inverter 20 and to connect to the heater 11 disposed on the battery 10.

[0053] The control module 31 is used to obtain the remaining capacity of the battery 10 and the temperature of the battery 10. When the remaining capacity is greater than a first preset charge and the temperature is less than a preset temperature, the control module 31 is used to output a first drive signal to the charging switch module 32 to turn off the charging switch module 32, thereby turning off the output current of the inverter 20 to the charging channel of the battery 10. The control module 31 is also used to output a second drive signal to the discharge switch module 33 to turn on the discharge switch module 33, thereby turning on the discharge channel of the battery 10, the discharge switch module 33 to the heater 11, and the output current of the inverter 20 flows to the heater 11.

[0054] During the process of the battery 10 heating the heater 11 through the discharge channel, the control module 31 is also used to detect the third current value input to the heater 11 and the second current value on the discharge channel. When the first current value of the output current of the inverter 20 is greater than the third current value, the control module 31 is also used to output a third drive signal to the discharge switch module 33 to control the discharge switch module 33 to turn off, thereby controlling the discharge channel from the battery 10 and the discharge switch module 33 to the heater 11 to be turned off.

[0055] In the charging and discharging control circuit 30, when the battery 10 is charging or about to be charged, the control module 31 can detect the remaining power of the battery 10 and receive the battery temperature output by the temperature detection element. When the remaining power of the battery 10 is less than a first preset power and the battery temperature is less than a preset temperature, the control module 31 will output a first drive signal to the charging switch module 32 to turn off the charging switch module 32. In this way, the output current of the inverter 20 to the charging channel of the battery 10 is in a closed state, that is, the inverter 20 is prevented from charging the battery 10 which is in a low temperature state. And the control module 31 will output a second drive signal to the discharging switch module 33 to turn on the discharging switch module 33. That is, the discharging channel of the battery 10 is opened to heat the heater 11. When the first current value of the output current of the inverter 20 is greater than the third current value, that is, when the current output by the inverter 20 is greater than the current required for heating by the heater 11, the discharge channel from the battery 10 and the discharge switch module 33 to the heater 11 is shut off, thereby preventing the continuous consumption of battery energy and avoiding over-discharge of the battery 10. This charge and discharge control circuit 30 ensures the safety and service life of the battery 10 during charging and discharging.

[0056] In some embodiments, when the battery 10 heats the heater 11 through the discharge channel, if the remaining capacity is less than a first preset charge and the temperature is less than a preset temperature, the control module 31 is further configured to output a third drive signal to the discharge switch module 33 to control the discharge switch module 33 to turn off, thereby controlling the shutdown of the discharge channel from the battery 10, the discharge switch module 33 to the heater 11.

[0057] When the temperature is lower than the preset temperature, it means that the battery is in a low temperature state and is not suitable for charging. The heater 11 on the battery 10 needs to obtain energy to heat the battery 10. When the remaining capacity of the battery 10 is less than the first preset charge, it means that the energy of the battery 10 is too low and the battery 10 is no longer suitable to output energy to heat itself. Therefore, at this time, it is necessary to close the discharge channel of the battery 10 and only allow the inverter 20 to output energy to the heater 11 to prevent the battery 10 from being over-discharged.

[0058] In yet another embodiment, such as Figure 2 As shown, the charging switch module 32 includes at least one first body diode D1 connected in series with the first output terminal and the second output terminal of the charging switch module 32, and the discharging switch module 33 includes at least one second body diode D2 connected in series with the first output terminal and the second output terminal of the discharging switch module 33.

[0059] The battery 10, at least one first body diode D1, and the turned-on discharge switch module 33 form the discharge channel, and at least one second body diode D2, the turned-on charging switch module 32, and the battery 10 form the charging channel.

[0060] It should be noted that the charging switch module 32 includes at least one first body diode D1, which is connected in series and is connected to both the first output terminal and the second output terminal of the charging switch module 32. The discharging switch module 33 includes at least one second body diode D2, which is connected in series and is connected to both the first output terminal and the second output terminal of the discharging switch module 33.

[0061] In another embodiment, please refer to Figure 3a , Figure 3a This is a structural block diagram of a charge / discharge control circuit provided in another embodiment of the present invention, as shown below. Figure 3a As shown, the charging switch module 32 further includes at least two charging power transistors Q1, each of which is provided with a first body diode D1; the discharging switch module 33 includes at least two discharging power transistors Q2, each of which is provided with a second body diode D2.

[0062] The control terminals of all the charging power transistors Q1 and all the discharging power transistors Q2 are connected to the control module 31. The output terminals of all the charging power transistors Q1 are connected in series to form a first series structure, and all the discharging power transistors Q2 are connected in series to form a second series structure. The output terminal of the first charging power transistor Q1 in the first series structure is used to connect to the battery 10, the charging power transistor Q1 at the end of the first series structure is connected to the output terminal of the first discharging power transistor Q2 in the second series structure, and the output terminal of the discharging power transistor Q2 at the end of the second series structure is used to connect to the inverter 20.

[0063] Among them, such as Figure 3b As shown, Figure 3b This is a schematic diagram of the current flow in a charging and discharging control circuit provided by an embodiment of the present invention. When the charging power transistor Q1 and the discharging power transistor Q2 receive the first driving signal and the second driving signal respectively, the charging power transistor Q1 is turned off and the discharging power transistor Q2 is turned on. The discharge current of the battery 10 flows from the first body diode D1 on each of the charging power transistors Q1 and the discharging power transistor Q2 to the heater 11.

[0064] It is known that the number of the first body diodes D1 is the same as the number of the charging power transistors Q1, and the number of the second body diodes D2 is the same as the number of the discharging power transistors Q2. The second output terminal of the first charging power transistor Q1 is connected to the battery 10, the first output terminal of the first charging power transistor Q1 is connected to the second output terminal of the second charging power transistor Q1, and so on, until the first output terminal of the last charging power transistor Q1 is connected to the first output terminal of the first discharging power transistor Q2. The second output terminal of the first discharging power transistor Q2 is connected to the first terminal of the second discharging power transistor Q2, the second terminal of the second discharging power transistor Q2 is connected to the first terminal of the third discharging power transistor Q2, and so on, until the second terminal of the last discharging power transistor Q2 is connected to the inverter 20. In this configuration, a first body diode D1 is connected to each of the at least two charging power transistors Q1, with its anode connected to the second output terminal of the charging power transistor Q1 and its cathode connected to the first output terminal of the charging power transistor Q1. A second body diode D2 is connected to each of the at least two discharging power transistors Q2, with its anode connected to the second output terminal of the discharging power transistor Q2 and its cathode connected to the first output terminal of the discharging power transistor Q2.

[0065] When the control module 31 outputs the first drive signal and the second drive signal respectively, the at least two charging power transistors Q1 will be turned off based on the first drive signal, and the at least two discharging power transistors Q2 will be turned on based on the second drive signal. At this time, as shown in Figure 3b, due to the unidirectional conductivity of the first body diode D1, the current output by the inverter 20 to the battery 10 cannot flow to the battery 10 through the first body diode D1, while the discharge current output by the battery 10 can pass through the first body diode D1 and the at least two discharging power transistors Q2. Therefore, when the at least two charging power transistors Q1 are turned off, the first body diode D1 and the at least two conducting discharging power transistors Q2 provide a discharge path for the battery to discharge.

[0066] Similarly, such as Figure 3c It can be seen that, Figure 3cThis is a schematic diagram of the current flow in another charging and discharging control circuit provided by an embodiment of the present invention. When at least two discharge power transistors Q2 are turned off, the second body diode D2 and at least two conducting charging power transistors Q1 provide a charging channel for the inverter 20 to charge the battery 10.

[0067] It should be noted that the number of charging power transistors Q1 and discharging power transistors Q2 is determined by the voltage rating of the power transistors, and the voltage rating and number of charging power transistors Q1 are the same as those of discharging power transistors Q2.

[0068] In some embodiments, the formula for calculating the number of charging power transistors Q1 and discharging power transistors Q2 is as follows:

[0069] n≥V Batmax / V MOS_DS ;

[0070] Where n is the total number of the charging power transistor Q1 and the discharging power transistor Q2, V Batmax V is the voltage when the battery is fully charged. MOS_DS denoted as the voltage rating of the power transistor. Here, n is a positive integer.

[0071] As we know, since the charging power transistor Q1 and the discharging power transistor Q2 have the same voltage rating, after determining the voltage rating of the power transistors, we can obtain the voltage of battery 10 when it is fully charged, and then calculate the total number of charging power transistors Q1 and discharging power transistors Q2 using the above formula. Finally, based on the total number, we can know the total number of charging power transistors Q1 and discharging power transistors Q2.

[0072] In yet another embodiment, please refer to Figure 4 , Figure 4 This is a circuit diagram of a charging and discharging control circuit provided in an embodiment of the present invention, as shown below. Figure 4 As shown, the charging switch module 32 further includes at least two first resistors R1, and the discharging switch module 33 further includes at least two second resistors R2; the number of first resistors R1 is the same as the number of charging power transistors Q1, and the number of second resistors R2 is the same as the number of discharging power transistors Q2.

[0073] Each of the first resistors R1 is connected to the output terminal of each of the charging power transistors Q1, and each of the second resistors R2 is connected to the output terminal of each of the discharging power transistors Q2.

[0074] The at least two first resistors R1 are used to balance the voltage at the output terminals of all the charging power transistors Q1 of the charging switch module 32 when it is turned off, and the at least two second resistors R2 are used to balance the voltage at the output terminals of all the discharging power transistors Q3 of the discharging switch module 33 when it is turned off.

[0075] It is known that the first resistor R1 is connected to the two output terminals of the charging power transistor Q1, and the second resistor R2 is connected to the two output terminals of the discharging power transistor Q2.

[0076] When the control module 31 outputs the first drive signal and / or the third drive signal, all charging power transistors Q1 in the charging switch module 32 will be turned off based on the first drive signal; and / or all discharging power transistors Q2 in the discharging switch module 33 will be turned off based on the third drive signal. However, when the charging power transistors Q1 and / or the discharging power transistors Q2 are turned off, there may be a situation where the equivalent resistance of each charging power transistor Q1 and / or each discharging power transistor Q2 is different. If the difference in equivalent resistance is large, the charging power transistor Q1 / discharging power transistor Q2 with the larger equivalent resistance will bear a larger voltage, potentially leading to breakdown of the charging power transistor Q1 / discharging power transistor Q2, thereby reducing the reliability of the circuit.

[0077] Based on this, by connecting a first resistor R1 in parallel to the two output terminals of each charging power transistor Q1 and a second resistor R2 in parallel to the two output terminals of each discharging power transistor Q2, the control module 31 outputs a first drive signal and / or a third drive signal to balance the voltage of each charging power transistor Q1 and / or the voltage of each discharging power transistor Q2, thereby avoiding power transistor breakdown.

[0078] In yet another embodiment, please refer to Figure 5a , Figure 5a This is a circuit diagram of a charge / discharge control circuit provided in another embodiment of the present invention, as shown below. Figure 5a As shown, the charging and discharging control circuit 30 also includes a relay 34. The first end of the relay 34 is connected to the control module 31, and the second and third ends of the relay 34 are respectively connected to the second output end of the charging switch module 32 and the second output end of the discharging switch module 33. Before the discharging switch module 33 or the charging switch module 32 is turned on, the relay 34 is used to control the discharging switch module 33 and the charging switch module 32 to be turned off.

[0079] Specifically, before the control module 31 outputs the fourth driving signal and the second driving signal to the charging switch module 32 and the discharging switch module 33 to control the charging switch module 32 and the discharging switch module 33 to turn on, it first outputs a pulse signal to the relay 34. This is done by closing the relay 34 so that the voltage across the drain and gate of each charging power transistor Q1 in the charging switch module 32 and the voltage across the drain and gate of each discharging power transistor Q2 in the discharging switch module 33 are close to zero. After this, the discharging switch module 33 or the charging switch module 32 can be turned on, which can improve the turn-off speed of the discharging switch module 33 and the charging switch module 32. This allows each charging power transistor Q1 in the charging switch module 32 to turn off simultaneously, or each discharging power transistor Q2 in the discharging switch module 33 to turn off simultaneously.

[0080] It should be noted that both the charging power transistor Q1 and the discharging power transistor Q2 include parasitic capacitance. When the charging power transistor Q1 and / or the discharging power transistor Q2 are turned on, the parasitic capacitance in both transistors stores voltage. When the charging power transistor Q1 and / or the discharging power transistor Q2 are turned off and then on again, the closing speeds of the two transistors differ due to the stored voltage, potentially leading to a breakdown risk. Therefore, by activating the relay 34 before closing the power transistors, the breakdown of the power transistors can be avoided.

[0081] In another embodiment, when the remaining capacity is greater than a first preset power and the temperature is less than a preset temperature, the control module 31 is further configured to send a pulse signal to the first terminal of the relay 34 to control the relay 34 to engage. After the relay 34 is engaged for a first preset time, the control module 31 is further configured to send the first drive signal and the second drive signal to the charging switch module 32 and the discharging switch module 33 respectively. The control module is further configured to send a pulse signal to the first terminal of the relay 34 to control the relay 34 to disengage.

[0082] When the remaining capacity is less than the second preset power and the temperature is greater than the preset temperature, the control module 31 is further configured to send a pulse signal to the first terminal of the relay 34 to control the relay 34 to engage. After the relay 34 engages, the control module 31 is further configured to send a third drive signal to the discharge switch module 33 to control the discharge switch module 33 to turn off. Wherein, the second preset power is less than or equal to the first preset power.

[0083] Specifically, when the inverter 20 outputs current and the control module 31 determines that the remaining charge of the battery 10 is less than a first preset charge and the battery temperature is lower than a preset temperature, the control module 31 outputs a pulse signal to the first terminal of the relay 34 to control the relay 34 to engage. When the relay 34 engages, it discharges the voltage stored in the charging power transistor Q1 and the discharging power transistor Q2. After the relay 34 engages for a first preset time according to the pulse signal, it disengages according to the pulse signal. At this time, the control module 31 outputs a first drive signal to the charging switch module 32 to turn off the charging switch module 32, and simultaneously outputs a second drive signal to the discharging switch module 33 to turn on the discharging switch module 33. When the charging switch module 32 is off and the discharging switch module 33 is on, the heater 11 can begin heating the battery 10 while simultaneously prohibiting charging.

[0084] When the temperature of the battery 10 begins to rise based on the heater 11, the control module 31 will also receive the battery temperature of the battery 10 in real time. When the battery temperature exceeds a preset temperature, the control module 31 will output a pulse signal to the relay 34 again to make the relay 34 energize. After the relay 34 is energized, it begins to discharge the voltage stored in the power transistor. After the relay 34 has been energized for a first preset time (i.e., the voltage stored in the power transistor is close to 0V), the control module 31 will output a third drive signal to the discharge switch module 33 to make the discharge switch module 33 turn off. When the discharge switch module 33 is turned off, the discharge channel is also in the off state. At this time, the output current of the inverter 20 will be input to the battery 10 through the relay 34 to charge the battery 10. It should be noted that charging the battery through the relay when the battery temperature is normal can reduce the number of devices through which the output current flows, thereby reducing the loss of the output current and accelerating the charging speed of the battery 10.

[0085] Furthermore, in another embodiment, when the discharge switch module 33 is turned on and the heater 11 is heating, when the inverter 20 is connected to a load, the control module 31 is also used to control the charging switch module 32 to turn on for a second preset time, and the control module 31 is also used to send a pulse signal to the relay 34 to control the relay to engage.

[0086] Specifically, when the battery 10 is turned on through the discharge channel of the first body diode D1 and the discharge switch module 33, and the heater 11 is heating, the relay 34 is in the off state. If the inverter 20 switches from being connected to the grid 200 to being connected to the load 300 at this time, the energy storage system 100 is in a loaded state, and the output current of the battery 10 will increase sharply. Figure 5b As shown, Figure 5b This is a schematic diagram of the current flow direction under load in a charging and discharging control circuit according to an embodiment of the present invention. The output current of the battery 10 flows to the inverter 20 through the first body diode D1 of the charging power transistor Q1 and the discharging power transistor Q2, and then supplies the load 300. However, the body diode has weak current carrying capacity and cannot continuously carry the load, which easily leads to the body diode burning out due to excessive current. To solve this problem, such as Figure 5c As shown, Figure 5c This is a schematic diagram of the current flow direction of another charging and discharging control circuit under load provided in an embodiment of the present invention. When the inverter 20 is under load, the control module 31 will output a fourth driving signal to the charging switch module 32 to turn on the charging switch module 32, so that the output current of the battery 10 flows to the inverter through the charging power transistor Q1 and the discharging power transistor Q2, thereby avoiding the situation where a large current flows through the body diode and causes damage to the body diode.

[0087] After the second preset time, such as Figure 5d As shown, Figure 5d This is a schematic diagram of the current flow direction when the charging and discharging control circuit is under load, provided by another embodiment of the present invention. The control module 31 sends a pulse signal to the relay 34 to control the relay 34 to engage. After that, the discharge current of the battery 10 can flow through the relay 34 to the inverter 20 and then be output to the battery 10. The second preset time can be 1ms. This can solve the aforementioned problems that the body diode cannot be continuously loaded and that the body diode is prone to burnout due to excessive current.

[0088] It should be noted that when the inverter 20 is switched to be connected to the load 300, the discharge current of the battery 10 will increase sharply. At this time, the current detection module 40 will detect the discharge current and input the discharge current to the control module 31, so that the control module 31 outputs a fourth drive signal to close the charging switch module 32, thereby avoiding damage to the device by large current and improving the reliability of the energy storage system 100.

[0089] This invention provides a charge / discharge control circuit. When the battery has sufficient remaining capacity (greater than a first preset capacity) and a low temperature (below a preset temperature), the control module promptly cuts off the charging channel and activates the discharge heating channel. This avoids damage to the battery caused by continued charging at low temperatures. Simultaneously, the inverter heats the battery to a suitable temperature range, extending its cycle life. Furthermore, by dual monitoring of the discharge channel and heater current, when the inverter output current exceeds the actual input current of the heater, the discharge channel is quickly shut off, effectively preventing safety risks such as over-discharge of the battery.

[0090] When the battery temperature is heated to a suitable level, the control relay is activated to start charging the battery, thereby accelerating the charging speed.

[0091] When the charging and discharging control circuit is under load, in order to avoid damage to the body diode in the power transistor by a large current, the control module controls the charging power transistor to also work at the moment of load application, so that the large current flows out through the power transistor, thereby avoiding damage to the device.

[0092] In addition, before controlling the closing of the charging power transistor and / or the discharging power transistor, the control module will first control the relay to close, thereby releasing the voltage between the gate and drain of the charging power transistor and / or the discharging power transistor through the relay, so that at least two charging power transistors and / or at least two discharging power transistors operate synchronously, avoiding the phenomenon that the power transistors will break down due to high voltage caused by different closing speeds.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; under the concept of the present invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of the present invention as described above, which are not provided in detail for the sake of brevity; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A charging and discharging control circuit, characterized in that, include: The control module is used to connect to the battery and to communicate with the inverter; The system includes a charging switch module and a discharging switch module. The control terminals of both the charging switch module and the discharging switch module are connected to the control module. The first output terminal of the charging switch module is connected to the first output terminal of the discharging switch module. The second output terminal of the charging switch module is used to connect to the battery. The second output terminal of the discharging switch module is used to connect to the inverter and to connect to the heater disposed on the battery. The control module is used to obtain the remaining capacity and temperature of the battery; when the remaining capacity is greater than a first preset capacity and the temperature is less than a preset temperature, the control module is used to output a first drive signal to the charging switch module to turn off the charging switch module, thereby turning off the output current of the inverter to the charging channel of the battery; the control module is also used to output a second drive signal to the discharging switch module to turn on the discharging switch module, thereby turning on the discharging channel of the battery, the discharging switch module to the heater, and the output current of the inverter flows to the heater. During the process of the battery heating the heater through the discharge channel, the control module is also used to detect the third current value input to the heater and the second current value on the discharge channel. When the first current value of the inverter's output current is greater than the third current value, the control module is also used to output a third drive signal to the discharge switch module to control the discharge switch module to turn off, thereby controlling the discharge channel from the battery and the discharge switch module to the heater to be turned off.

2. The charging and discharging control circuit according to claim 1, characterized in that, The charging switch module includes at least one first body diode connected in series with the first output terminal and the second output terminal of the charging switch module, and the discharging switch module includes at least one second body diode connected in series with the first output terminal and the second output terminal of the discharging switch module. The battery, at least one first body diode, and the activated discharge switch module form the discharge channel, and the at least one second body diode, the activated charging switch module, and the battery form the charging channel.

3. The charging and discharging control circuit according to claim 2, characterized in that, The charging switch module further includes at least two charging power transistors, each of which is provided with a first body diode; the discharging switch module includes at least two discharging power transistors, each of which is provided with a second body diode. The control terminals of all the charging power transistors and all the discharging power transistors are connected to the control module. The output terminals of all the charging power transistors are connected in series to form a first series structure, and all the discharging power transistors are connected in series to form a second series structure. The output terminal of the charging power transistor at the beginning of the first series structure is used to connect to the battery. The charging power transistor at the end of the first series structure is connected to the output terminal of the discharging power transistor at the beginning of the second series structure. The output terminal of the discharging power transistor at the end of the second series structure is used to connect to the inverter. When the charging power transistor and the discharging power transistor receive the first driving signal and the second driving signal respectively, the charging power transistor is turned off and the discharging power transistor is turned on, and the discharge current of the battery flows from the first body diode on each of the charging power transistors and the discharging power transistor to the heater.

4. The charging and discharging control circuit according to claim 3, characterized in that, The charging switch module further includes at least two first resistors, and the discharging switch module further includes at least two second resistors; the number of first resistors is the same as the number of charging power transistors, and the number of second resistors is the same as the number of discharging power transistors. Each of the first resistors is connected to the output terminal of each of the charging power transistors, and each of the second resistors is connected to the output terminal of each of the discharging power transistors. The at least two first resistors are used to balance the voltage at the output terminals of all the charging power transistors of the charging switch module when it is turned off, and the at least two second resistors are used to balance the voltage at the output terminals of all the discharging power transistors of the discharging switch module when it is turned off.

5. The charge / discharge control circuit according to claim 3, characterized in that, The formula for calculating the number of charging power transistors and the number of discharging power transistors is as follows: n≥V Batmax / V MOS_DS ; Where n is the total number of the charging power transistors and the discharging power transistors, V Batmax V is the voltage when the battery is fully charged. MOS_DS This is the withstand voltage value of the power transistor.

6. The charging and discharging control circuit according to any one of claims 2 to 5, characterized in that, The charging and discharging control circuit also includes a relay. The first end of the relay is connected to the control module, and the second and third ends of the relay are respectively connected to the second output end of the charging switch module and the second output end of the discharging switch module. Before the discharging switch module or the charging switch module is turned on, the relay is used to control the discharging switch module and the charging switch module to turn off.

7. The charge / discharge control circuit according to claim 6, characterized in that, When the remaining capacity is greater than the first preset power and the temperature is less than the preset temperature, the control module is further configured to send a pulse signal to the first terminal of the relay to control the relay to engage. After the relay engages for a first preset time, the control module is further configured to send the first drive signal and the second drive signal to the charging switch module and the discharging switch module respectively. The control module is further configured to send a pulse signal to the first terminal of the relay to control the relay to disengage. When the remaining capacity is less than the second preset power and the temperature is greater than the preset temperature, the control module is further configured to send a pulse signal to the first terminal of the relay to control the relay to engage. After the relay engages, the control module is further configured to send a third drive signal to the discharge switch module to control the discharge switch module to turn off; wherein, the second preset power is less than or equal to the first preset power.

8. The charge / discharge control circuit according to claim 6, characterized in that, When the discharge switch module is turned on and the heater is heating, when the inverter is connected to a load, the control module is also used to control the charging switch module to turn on for a second preset time, and then send a pulse signal to the relay to control the relay to engage.

9. The charging and discharging control circuit according to claim 1, characterized in that, When the battery heats the heater through the discharge channel, if the remaining capacity is less than a first preset charge and the temperature is less than a preset temperature, the control module is also used to output a third drive signal to the discharge switch module to control the discharge switch module to turn off, thereby controlling the discharge channel from the battery and the discharge switch module to the heater to be turned off.

10. An energy storage system, characterized in that, The energy storage system includes: A battery, wherein a heater and a temperature detection element for detecting the temperature of the battery are provided on the battery; Inverter, used to connect the power grid and the load; The charge / discharge control circuit according to any one of claims 1 to 9, wherein the temperature detection element is connected to the control module, and the charge / discharge control circuit is used to control the charge / discharge process of the battery; and The current detection module is connected to the second output terminal of the inverter and the discharge switch module, and is used to detect the current value and current direction of the inverter.

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