Charging and discharging control circuit and energy storage system

Abstract

The invention relates to the technical field of energy storage, and mainly provides a charging and discharging control circuit and an energy storage system.The circuit comprises a control module connected with a battery and an inverter, a charging switch module and a discharging switch module, the charging switch module and the discharging switch module are connected with the control module, and the charging switch module is further connected with the battery; and the discharge switch module is also respectively connected with the inverter and a heater arranged on the battery. When the residual capacity of the battery is sufficient and the temperature is low, the control module cuts off the charging channel in time and opens the discharging heating channel, so that damage to the battery caused by continuous charging at low temperature can be avoided, meanwhile, the temperature of the battery is increased to a proper range through heating of the inverter, and the cycle life of the battery is prolonged. And by performing dual monitoring on the current of the discharge channel and the heater, when the output current of the inverter is greater than the actual input current of the heater, the discharge channel is rapidly turned off, so that safety risks such as over-discharge of the battery can be effectively avoided.

Description

Technical Field

[0001] The present invention relates to the field of energy storage, and in particular to a charge and discharge control circuit and an energy storage system. Background Art

[0002] In the field of new energy storage, lithium batteries are widely used in high-voltage energy storage systems due to their 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 deposition is very likely to occur, which may puncture the internal separator of the battery cell, causing the cell to short-circuit and seriously threatening the safe operation of the energy storage system. Furthermore, using the battery's own energy to heat the battery at low temperatures can easily lead to over-discharge, resulting in irreversible degradation of the battery cell performance, shortening the battery life and even posing safety risks. Summary of the Invention

[0003] The embodiments of the present invention provide a charge and discharge control method and an energy storage system, which aim to solve the technical problems in the prior art of lithium batteries being prone to over-discharge, low safety, and low reliability during charging.

[0004] To solve the above technical problems, a technical solution adopted in an embodiment of the present invention is to provide a charge and discharge control circuit, comprising: A control module, configured to connect to the battery and to communicate with the inverter; A charging switch module and a discharging switch module, wherein the control end of the charging switch module and the control end of the discharging switch module are both connected to the control module, the first output end of the charging switch module is connected to the first output end of the discharging switch module, the second output end of the charging switch module is used to connect to a battery, and the second output end of the discharging switch module is used to connect to the inverter and to connect to a heater provided on the battery; The control module is used to obtain the remaining capacity of the battery and the temperature of the battery; when the remaining capacity is less than a first preset power 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 discharge switch module to turn on the discharge switch module, thereby opening the discharge channel from the battery and the discharge switch module to the heater, and the output current of the inverter flows to the heater.

[0005] Optionally, the charging switch module includes at least one first body diode connected in series to the first output end of the charging switch module and the second output end of the charging switch module, and the discharging switch module includes at least one second body diode connected in series to the first output end of the discharging switch module and the second output end of the discharging switch module; The battery, at least one first body diode and the turned-on discharge switch module form the discharge channel, and at least one second body diode, the turned-on charge switch module and the battery form the charge channel.

[0006] Optionally, the charging switch module further includes at least two charging power tubes, each of which is provided with a first body diode; the discharging switch module includes at least two discharging power tubes, each of which is provided with a second body diode; The control ends of all the charging power tubes and the control ends of all the discharging power tubes are connected to the control module. The output ends of all the charging power tubes are sequentially connected in series to form a first series structure, and the output ends of all the discharging power tubes are sequentially connected in series to form a second series structure. The output end of the charging power tube at the head of the first series structure is used to connect to the battery, the charging power tube at the tail of the first series structure is connected to the output end of the discharging power tube at the head of the second series structure, and the output end of the discharging power tube at the tail of the second series structure is used to connect to the inverter. When the charging power tube and the discharging power tube receive the first driving signal and the second driving signal respectively, the charging power tube is turned off and the discharging power tube is turned on, and the discharge current of the battery flows from the first body diode on each of the charging power tubes and the discharging power tube to the heater.

[0007] 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 the first resistors is the same as the number of the charging power tubes, and the number of the second resistors is the same as the number of the discharging power tubes; Each of the first resistors is connected to the output end of each of the charging power tubes, and each of the second resistors is connected to the output end of each of the discharging power tubes; The at least two first resistors are used to balance the voltages at the output ends of all the charging power tubes of the charging switch module when the charging switch module is turned off, and the at least two second resistors are used to balance the voltages at the output ends of all the discharging power tubes of the discharging switch module when the discharging switch module is turned off.

[0008] Optionally, the calculation formula for the number of the charging power tubes and the discharging power tubes is: n≥V Batmax / V MOS_DS ; Wherein, n is the total number of the charging power tubes and the discharging power tubes, V Batmax is the voltage of the battery when it is fully charged, V MOS_DS It is the withstand voltage value of the power tube.

[0009] Optionally, the charge and discharge control circuit also includes a relay, the first end of the relay is connected to the control module, and the second end and the third end 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 shutdown of the discharging switch module and the charging switch module.

[0010] 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 end of the relay to control the relay to be energized; after the relay is energized 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 end of the relay to control the relay to be disconnected; When the remaining capacity is less than a first preset power and the temperature is greater than a preset temperature, the control module is further used to send a pulse signal to the first end of the relay to control the relay to be attracted. After the relay is attracted, the control module is further used to send a third drive signal to the discharge switch module to control the discharge switch module to be turned off; wherein, the second preset power is less than or equal to the first preset power.

[0011] Optionally, when the discharge switch module is turned on and the heater is heating, when the inverter is connected to the load, the control module is also used to control the charging switch module to be turned on for a second preset time, and the control module is also used to send a pulse signal to the relay to control the relay to be energized.

[0012] 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 used 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 output current of the inverter is greater than the third current value, the control module is further used to output a third drive signal to the discharge switch module to control the discharge switch module to shut down, thereby controlling the shutdown of the battery and the discharge channel from the discharge switch module to the heater.

[0013] In order to solve the above technical problems, another technical solution adopted in the embodiment of the present invention is to provide an energy storage system, which includes: a battery, wherein the battery is provided with a heater and a temperature detection element for detecting the temperature of the battery; An inverter, wherein the inverter is used to connect the power grid and the load; The charge and discharge control circuit as described above, wherein the temperature detection element is connected to the control module, and the charge and discharge control circuit is used to control the charge and discharge process of the battery; and A current detection module is connected to the inverter and the second output end of the discharge switch module, and is used to detect the current value and current direction of the inverter.

[0014] Different from the related art, the present invention provides a charge and discharge control circuit and energy storage system, which includes: a control module, which is used to connect to the battery and communicate with the inverter; a charging switch module and a discharging switch module, wherein the control end of the charging switch module and the control end of the discharging switch module are both connected to the control module, the first output end of the charging switch module is connected to the first output end of the discharging switch module, the second output end of the charging switch module is used to connect to the battery, and the second output end of the discharging switch module is used to connect to the inverter and to connect to a heater provided on the battery.

[0015] Among them, when the remaining battery capacity is sufficient (greater than the first preset power) and the temperature is low (lower than the preset temperature), the control module promptly cuts off the charging channel and opens the discharge heating channel, thereby avoiding damage to the battery caused by continuing charging at low temperatures. At the same time, the battery temperature is raised to an appropriate range through inverter heating, thereby extending the battery cycle life.

[0016] By dual monitoring of the discharge channel and the heater current, when the inverter output current is greater than the actual heater input current, the discharge channel is quickly shut down, which can effectively avoid safety risks such as battery over-discharge. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] One or more embodiments are exemplarily illustrated by corresponding drawings, which do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0018] Figure 1 This is a schematic diagram of an application scenario provided by an embodiment of the present invention; Figure 2 This is a structural block diagram of a charge and discharge control circuit provided by an embodiment of the present invention; Figure 3a is a structural block diagram of a charge and discharge control circuit provided by another embodiment of the present invention; Figure 3b This is a schematic diagram of current flow in a charge and discharge control circuit provided by an embodiment of the present invention; Figure 3c is a schematic diagram of current flow in another charge and discharge control circuit provided by an embodiment of the present invention; Figure 4 is a circuit diagram of a charge and discharge control circuit provided by an embodiment of the present invention; Figure 5a is a circuit diagram of a charge and discharge control circuit provided in another embodiment of the present invention; Figure 5b Schematic diagram of current flow when a charge and discharge control circuit is loaded, provided by an embodiment of the present invention; Figure 5c Schematic diagram of current flow when another charge and discharge control circuit is loaded, provided by an embodiment of the present invention; Figure 5d This is a schematic diagram of current flow when another charge and discharge control circuit is loaded, provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present 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 only used to explain the present invention and are not intended to limit the present invention.

[0020] It should be noted that, unless there is a conflict, the various features of the embodiments of the present invention may be combined with each other and are all within the scope of protection of the present invention. In addition, although the functional modules are divided in the device schematics and the logical order is shown in the flowcharts, in some cases, the steps shown or described may be performed in a different order than the module division in the device schematics or the order in the flowcharts.

[0021] Unless otherwise defined, all technical and scientific terms used in this specification have the same meanings as those commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification are intended solely for the purpose of describing specific embodiments and are 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.

[0022] See also 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. The energy storage system 100 is connected to the power grid 200 and / or the load 300, respectively. The energy storage system 100 is configured 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.

[0023] Among them, such as Figure 1As shown, the energy storage system 100 includes a battery 10, an inverter 20, a charge and discharge control circuit 30, and a current detection module 40. The battery 10 is provided with a heater 11 and a temperature detection element (not shown) for detecting the temperature of the battery 10. The charge and discharge control circuit 30 is connected to the battery 10 and the current detection module 40, respectively. The charge and discharge control circuit 30 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 and discharge control circuit 30. The inverter 20 is also connected to the power grid 200 or the load 300. The inverter 20 can convert the energy provided by the power grid 200 and output it to the battery 10. The energy of the battery 10 can be output to the inverter 20 and then provided by the inverter 20 to the load 300 or incorporated into the power grid 200. During the energy exchange process between the inverter 20, the power grid 200, the battery 10 and the load 300, the charge and discharge control circuit 30 is used to control the charge and discharge process of the battery 10, and the current detection module 40 is used to detect the current value and current direction of the inverter 20.

[0024] In some embodiments, the heater 11 may be a heating device such as a thermistor, a thin film heater, etc. The temperature detection element may be, but is not limited to, a temperature sensor for sensing temperature.

[0025] In other embodiments, the current detection module may be a device for detecting current values, such as a Hall element, a current transformer, etc.

[0026] See also Figure 2 , Figure 2 This is a structural block diagram of a charge and discharge control circuit provided by an embodiment of the present invention. Figure 2 As shown, the charge and discharge control circuit 30 includes a control module 31 , a charge switch module 32 and a discharge switch module 33 .

[0027] The control module 31 is connected to the battery 10 and communicates with the inverter 20. This control module 31 is a battery management system (BMS) control chip. The battery 10 is equipped with a temperature-sensing sensor connected to the BMS control chip, which can obtain the battery's remaining capacity and temperature. The control module 31 obtains the battery's remaining capacity. When the remaining capacity is less than a preset threshold, the control module 31 sends a charging signal to the inverter 20, to which it is communicating. Upon receiving the charging signal, the inverter 20 obtains energy from the power grid 200 for subsequent output.

[0028] The control end of the charging switch module 32 and the control end of the discharging switch module 33 are both connected to the control module 31, the first output end of the charging switch module 32 is connected to the first output end of the discharging switch module 33, the second output end of the charging switch module 32 is used to connect to the battery 10, and the second output end of the discharging switch module 33 is used to connect to the inverter 20 and to connect to the heater 11 provided on the battery 10.

[0029] 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 power 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 opening the discharge channel from the battery 10 and the discharge switch module 33 to the heater 11, and the output current of the inverter 20 flows to the heater 11.

[0030] When the battery 10 heats the heater 11 through the discharge channel, the control module 31 is further used to detect a third current value input to the heater 11 and a 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 further used to output a third drive signal to the discharge switch module 33 to control the discharge switch module 33 to be turned off, thereby controlling the shutdown of the discharge channel from the battery 10 and the discharge switch module 33 to the heater 11.

[0031] In the charge and discharge control circuit 30, when the battery 10 is in the charging process or is 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 the first preset power and the battery temperature is less than the 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, so that the output current of the inverter 20 to the charging channel of the battery 10 is in the off state, that is, the inverter 20 is prevented from charging the battery 10 in a low temperature state; and the control module 31 will output a second drive signal to the discharge switch module 33 to turn on the discharge switch module 33; that is, the discharge channel of the battery 10 is opened to heat the heater 11. When the first current value of the inverter 20 output current 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 path from the battery 10 and the discharge switch module 33 to the heater 11 is shut off, thereby preventing continuous consumption of battery energy and over-discharge of the battery 10. This charge and discharge control circuit 30 ensures the safety and service life of the battery 10 during the charging and discharging process.

[0032] In some embodiments, when the battery 10 heats the heater 11 through the discharge channel, when the remaining capacity is less than a first preset power and the temperature is less than a preset temperature, the control module 31 is further used to output a third drive signal to the discharge switch module 33 to control the discharge switch module 33 to be turned off, thereby controlling the shutdown of the discharge channel from the battery 10 and the discharge switch module 33 to the heater 11.

[0033] When the temperature is lower than the preset temperature, it indicates 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 lower than the first preset power, it indicates that the energy of the battery 10 is too low. The battery 10 itself is no longer suitable for outputting energy to heat itself. Therefore, the discharge channel of the battery 10 needs to be closed at this time, and only the inverter 20 is allowed to output energy to the heater 11 to prevent the battery 10 from being over-discharged.

[0034] In yet another embodiment, Figure 2 As shown, the charging switch module 32 includes at least one first body diode D1 connected in series to the first output end of the charging switch module 32 and the second output end of the charging switch module 32, and the discharging switch module 33 includes at least one second body diode D2 connected in series to the first output end of the discharging switch module 33 and the second output end of the discharging switch module 33; 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 charge switch module 32 , and the battery 10 form the charge channel.

[0035] It should be noted that the charging switch module 32 includes at least one first body diode D1, which is connected in series with one another. The series-connected first body diode D1 is respectively connected to the first output terminal of the charging switch module 32 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 with one another. The series-connected second body diode D2 is respectively connected to the first output terminal of the discharging switch module 33 and the second output terminal of the discharging switch module 33.

[0036] In another embodiment, see Figure 3a , Figure 3a FIG. 1 is a structural block diagram of a charge and discharge control circuit provided by another embodiment of the present invention. Figure 3a As shown, the charging switch module 32 further includes at least two charging power tubes Q1, each of which is provided with a first body diode D1; the discharging switch module 33 includes at least two discharging power tubes Q2, each of which is provided with a second body diode D2; The control ends of all the charging power tubes Q1 and the control ends of all the discharging power tubes Q2 are connected to the control module 31. The output ends of all the charging power tubes Q1 are sequentially connected in series to form a first series structure, and the output ends of all the discharging power tubes Q2 are sequentially connected in series to form a second series structure. The output end of the charging power tube Q1 at the head of the first series structure is connected to the battery 10. The charging power tube Q1 at the tail of the first series structure is connected to the output end of the discharging power tube Q2 at the head of the second series structure. The output end of the discharging power tube Q2 at the tail of the second series structure is connected to the inverter 20. Among them, such as Figure 3b As shown, Figure 3b 2 is a schematic diagram of current flow in a charge and discharge control circuit provided by an embodiment of the present invention. When the charging power tube Q1 and the discharging power tube Q2 receive a first drive signal and a second drive signal, respectively, the charging power tube Q1 is turned off and the discharging power tube Q2 is turned on. The discharge current of the battery 10 flows from the first body diode D1 on each of the charging power tube Q1 and the discharging power tube Q2 to the heater 11.

[0037] It can be seen that the number of the first body diodes D1 is the same as the number of the charging power tubes Q1, the number of the second body diodes D2 is the same as the number of the discharging power tubes Q2, the second output end of the first charging power tube Q1 of the at least two charging power tubes Q1 is connected to the battery 10, the first output end of the first charging power tube Q1 is connected to the second output end of the second charging power tube Q1, and so on, until the first output end of the last charging power tube Q1 is connected to the first output end of the first discharging power tube Q2 of the at least two discharging power tubes Q2. The second output end of the first discharging power tube Q2 is connected to the first end of the second discharging power tube Q2, the second end of the second discharging power tube Q2 is connected to the first end of the third discharging power tube Q2, and so on, until the second end of the last discharging power tube Q2 is connected to the inverter 20. The first body diode D1 is connected to the at least two charging power transistors Q1, and the anode of the first body diode D1 is connected to the second output terminal of the charging power transistor Q1, and the cathode of the first body diode D1 is connected to the first output terminal of the charging power transistor Q1. The second body diode D2 is connected to the at least two discharging power transistors Q2, and the anode of the second body diode D2 is connected to the second output terminal of the discharging power transistor Q2, and the cathode of the second body diode D2 is connected to the first output terminal of the discharging power transistor Q2.

[0038] When the control module 31 outputs the first drive signal and the second drive signal, respectively, the at least two charging power transistors Q1 are turned off based on the first drive signal, and the at least two discharging power transistors Q2 are turned on based on the second drive signal. At this point, as shown in FIG3b , 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. However, the discharge current output by the battery 10 can flow 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 channel for the battery.

[0039] Similarly, if Figure 3c It can be seen that Figure 3c This is a schematic diagram of the current flow in another charge and discharge control circuit provided by an embodiment of the present invention. When at least two discharge power tubes Q2 are turned off, the second body diode D2 and at least two charging power tubes Q1 that are turned on provide a charging channel for the inverter 20 to charge the battery 10.

[0040] It should be noted that the number of the charging power tube Q1 and the discharging power tube Q2 is determined by the withstand voltage value of the power tube, and the withstand voltage value and number of the charging power tube Q1 are the same as the withstand voltage value and number of the discharging power tube Q2.

[0041] In some embodiments, the calculation formula for the number of the charging power tube Q1 and the discharging power tube Q2 is: n≥V Batmax / V MOS_DS ; Wherein, n is the total number of the charging power tube Q1 and the discharging power tube Q2, V Batmax is the voltage of the battery when it is fully charged, V MOS_DS is the withstand voltage of the power tube. Where n is a positive integer.

[0042] It can be seen that since the voltage resistance values ​​of the charging power tube Q1 and the discharging power tube Q2 are the same, after determining the voltage resistance values ​​of the power tubes, the voltage of the battery 10 when fully charged is obtained, and then the total number of the charging power tubes Q1 and the discharging power tubes Q2 can be calculated using the above formula. Finally, based on the total number, the number of the charging power tubes Q1 and the discharging power tubes Q2 can be determined.

[0043] In yet another embodiment, see Figure 4 , Figure 4 is a circuit diagram of a charge and discharge control circuit provided by an embodiment of the present invention, such as 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 the first resistors R1 is the same as the number of the charging power tubes Q1, and the number of the second resistors R2 is the same as the number of the discharging power tubes Q2; Each of the first resistors R1 is connected to the output end of each of the charging power tubes Q1, and each of the second resistors R2 is connected to the output end of each of the discharging power tubes Q2. The at least two first resistors R1 are used to balance the voltages at the output ends of all the charging power tubes Q1 of the charging switch module 32 when the charging switch module 32 is turned off, and the at least two second resistors R2 are used to balance the voltages at the output ends of all the discharging power tubes Q3 of the discharging switch module 33 when the discharging switch module 33 is turned off.

[0044] It can be known that the first resistor R1 is connected to the two output ends of the charging power tube Q1, and the second resistor R2 is connected to the two output ends of the discharging power tube Q2.

[0045] When the control module 31 outputs the first drive signal and / or the third drive signal, all the charging power tubes Q1 in the charging switch module 32 will be turned off based on the first drive signal; and / or all the discharging power tubes Q2 in the discharging switch module 33 will be turned off based on the third drive signal. When the charging power tubes Q1 and / or the discharging power tubes Q2 are turned off, there is a situation where the equivalent resistance of each charging power tube Q1 and / or the equivalent resistance of each discharging power tube Q2 are different. At this time, if the difference in the equivalent resistance is large, the charging power tube Q1 / discharging power tube Q2 with a larger equivalent resistance will be subjected to a greater voltage, which will cause the charging power tube Q1 / discharging power tube Q2 to break down, thereby reducing the reliability of the circuit.

[0046] Based on this, by connecting a first resistor R1 in parallel to the two output ends of each charging power tube Q1, and connecting a second resistor R2 in parallel to the two output ends of each discharging power tube Q2, the control module 31 outputs a first drive signal and / or a third drive signal, and balances the voltage of each charging power tube Q1 and / or balances the voltage on each discharging power tube Q2, thereby avoiding power tube breakdown.

[0047] In yet another embodiment, see Figure 5a , Figure 5a FIG. 1 is a circuit diagram of a charge and discharge control circuit provided by another embodiment of the present invention, such as Figure 5a As shown, the charge and discharge control circuit 30 also includes a relay 34, a first end of the relay 34 is connected to the control module 31, and a second end and a third end 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 shutdown of the discharging switch module 33 and the charging switch module 32.

[0048] Specifically, before the control module 31 outputs the fourth drive signal and the second drive signal to the charging switch module 32 and the discharging switch module 33 respectively to control the charging switch module 32 and the discharging switch module 33 to be turned on, it will first output a pulse signal to the relay 34, so that the voltage across the drain and gate of each charging power tube Q1 in the charging switch module 32 and the voltage across the drain and gate of each discharging power tube Q2 in the discharging switch module 33 are close to zero voltage through the closed relay 34. Thereafter, the discharge switch module 33 or the charging switch module 32 is controlled to be turned on, which can increase the shutdown speed of the discharge switch module 33 and the charging switch module 32, that is, each charging power tube Q1 in the charging switch module 32 is turned off at the same time, or each discharging power tube Q2 in the discharging switch module 33 is turned off at the same time.

[0049] It should be noted that both the charging power tube Q1 and the discharging power tube Q2 include parasitic capacitance. When the charging power tube Q1 and / or the discharging power tube Q2 are turned on, the parasitic capacitance in the charging power tube Q1 and / or the discharging power tube Q2 will store voltage. At this time, when the charging power tube Q1 and / or the discharging power tube Q2 are turned off and then turned on again, due to the influence of the stored voltage in the parasitic capacitance, the closing speed of the charging power tube Q1 and / or the discharging power tube Q2 is different, resulting in the risk of power tube breakdown. Based on this, by attracting the relay 34 before closing the power tube, the phenomenon of power tube breakdown can be avoided.

[0050] In another embodiment, when the remaining capacity is greater than a first preset capacity and the temperature is less than a preset temperature, the control module 31 is further configured to send a pulse signal to the first end of the relay 34 to control the relay 34 to be energized. After the relay 34 is energized 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, and then send a pulse signal to the first end of the relay 34 to control the relay 34 to be disconnected. 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 used to send a pulse signal to the first end of the relay 34 to control the relay 34 to be attracted. After the relay 34 is attracted, the control module 31 is further used to send a third drive signal to the discharge switch module 33 to control the discharge switch module 33 to be turned off; wherein the second preset power is less than or equal to the first preset power.

[0051] 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 end 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 in accordance with the pulse signal, the relay 34 disconnects in accordance with the pulse signal. At this time, the control module 31 outputs a first drive signal to the charging switch module 32 to turn it off, and simultaneously outputs a second drive signal to the discharging switch module 33 to turn it on. When the charging switch module 32 is turned off and the discharging switch module 33 is turned on, the heater 11 begins heating the battery 10 while charging is prohibited. When the temperature of the battery 10 begins to rise due to the heater 11, the control module 31 also receives the battery temperature of the battery 10 in real time. When the battery temperature exceeds a preset temperature, the control module 31 again outputs a pulse signal to the relay 34 to energize the relay 34. Once energized, the relay 34 begins to discharge the voltage stored in the power transistor. After the relay 34 has been energized for a first preset time (i.e., when the voltage stored in the power transistor approaches 0V), the control module 31 outputs a third drive signal to the discharge switch module 33 to energize the discharge switch module 33. When the discharge switch module 33 is energized, the discharge path is also closed. At this point, the output current of the inverter 20 is input to the battery 10 through the relay 34, thereby charging the battery 10. It should be noted that charging the battery through the relay when the battery temperature is normal reduces the number of devices through which the output current flows, thereby reducing output current loss and accelerating the charging speed of the battery 10.

[0052] 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 the load, the control module 31 is also used to control the charging switch module 32 to be turned 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 be energized.

[0053] Specifically, when the battery 10 is connected to the first body diode D1 and the discharge channel of the discharge switch module 33 is opened and the heater 11 is heated, the relay 34 is in the disconnected state. If the inverter 20 is switched from being connected to the grid 200 to being connected to the load 300, the energy storage system 100 is in the loaded state. At this time, the output current of the battery 10 will increase sharply, as shown in FIG. Figure 5b As shown, Figure 5b This is a schematic diagram of the current flow of a charge and discharge control circuit under load provided by an embodiment of the present invention. The output current of the battery 10 flows through the first body diode D1 of the charging power tube Q1 and the discharging power tube Q2 to the inverter 20 and then to the load 300. However, the body diode has a weak current carrying capacity and cannot be continuously loaded, which can easily cause the body diode to flow through a large current and burn out. In order to solve this problem, Figure 5c As shown, Figure 5cThis is a schematic diagram of the current flow when another charge and discharge control circuit provided by an embodiment of the present invention is loaded. When the inverter 20 is loaded, the control module 31 outputs a fourth drive 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 tube Q1 and the discharging power tube Q2, thereby avoiding the situation where a large current flows through the body diode and causes damage to the body diode.

[0054] After the second preset time, if Figure 5d As shown, Figure 5d This is a schematic diagram of the current flow when another charge and discharge control circuit is loaded, provided by an embodiment of the present invention. The control module 31 sends a pulse signal to the relay 34 to control the relay 34 to be attracted. After that, the discharge current of the battery 10 can flow to the inverter 20 through the relay 34 and then be output to the battery 10. The second preset time can be 1mS. This can solve the problem that the body diode cannot be continuously loaded and is prone to burning out due to the large current flowing through the body diode.

[0055] 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 large current damage to the device and improving the reliability of the energy storage system 100.

[0056] An embodiment of the present invention provides a charge-discharge control circuit. When the battery has sufficient remaining capacity (greater than a first preset charge) and the temperature is low (less than a preset temperature), the control module promptly shuts off the charging channel and activates the discharge and heating channel. This prevents damage to the battery caused by continued charging at low temperatures. Inverter heating simultaneously raises the battery temperature to a suitable range, extending the battery's cycle life. Furthermore, by dually monitoring the current in the discharge channel and the heater, the discharge channel is quickly shut off when the inverter output current exceeds the actual heater input current, effectively preventing safety risks such as over-discharge of the battery.

[0057] When the battery temperature is heated to a suitable temperature, the control relay is energized to start charging the battery through the relay, thereby speeding up the charging speed.

[0058] When the charge and discharge control circuit is loaded, in order to prevent the large current from damaging the body diode in the power tube, the control module controls the charging power tube to participate in the work at the moment of loading, so that the large current flows out through the power tube, thereby avoiding damage to the device.

[0059] In addition, before controlling the charging power tube and / or the discharging power tube to close, the control module will first control the relay to close, thereby discharging the voltage between the gate and the drain of the charging power tube and / or the discharging power tube through the relay, thereby making at least two charging power tubes and / or at least two discharging power tubes operate synchronously, avoiding the phenomenon of power tube breakdown due to high voltage caused by different closing speeds.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Under the concept of the present invention, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations in different aspects of the present invention as described above. For the sake of simplicity, they are not provided in detail. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A charge and discharge control circuit, characterized in that: include: A control module, used for connecting to the battery and for communicating with the inverter; A charging switch module and a discharging switch module, wherein the control end of the charging switch module and the control end of the discharging switch module are both connected to the control module, the first output end of the charging switch module is connected to the first output end of the discharging switch module, the second output end of the charging switch module is used to connect to a battery, and the second output end of the discharging switch module is used to connect to the inverter and to connect to a heater provided on the battery; The control module is used to obtain the remaining capacity of the battery and the temperature of the battery; when the remaining capacity is greater than a first preset power 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 shutting off the charging path of the output current of the inverter to 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 opening the discharging path from the battery and the discharging switch module to the heater, and the output current of the inverter flows to the heater; When the battery heats the heater through the discharge channel, the control module is further used 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 output current of the inverter is greater than the third current value, the control module is further used to output a third drive signal to the discharge switch module to control the discharge switch module to be turned off, thereby controlling the shutdown of the discharge channel from the battery and the discharge switch module to the heater.

2. The charge and discharge control circuit according to claim 1, wherein: The charging switch module includes at least one first body diode connected in series to the first output terminal of the charging switch module and the second output terminal of the charging switch module; the discharging switch module includes at least one second body diode connected in series to the first output terminal of the discharging switch module and the second output terminal of the discharging switch module; The battery, at least one first body diode and the turned-on discharge switch module form the discharge channel, and at least one second body diode, the turned-on charge switch module and the battery form the charge channel.

3. The charge and discharge control circuit according to claim 2, wherein: The charging switch module further includes at least two charging power tubes, each of which is provided with a first body diode; the discharging switch module includes at least two discharging power tubes, each of which is provided with a second body diode; The control ends of all the charging power tubes and the control ends of all the discharging power tubes are connected to the control module. The output ends of all the charging power tubes are sequentially connected in series to form a first series structure, and the output ends of all the discharging power tubes are sequentially connected in series to form a second series structure. The output end of the charging power tube at the head of the first series structure is used to connect to the battery, the charging power tube at the tail of the first series structure is connected to the output end of the discharging power tube at the head of the second series structure, and the output end of the discharging power tube at the tail of the second series structure is used to connect to the inverter. When the charging power tube and the discharging power tube receive the first driving signal and the second driving signal respectively, the charging power tube is turned off and the discharging power tube is turned on, and the discharge current of the battery flows from the first body diode on each of the charging power tubes and the discharging power tube to the heater.

4. The charge and discharge control circuit according to claim 3, wherein: 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 the first resistors is the same as the number of the charging power tubes, and the number of the second resistors is the same as the number of the discharging power tubes; Each of the first resistors is connected to the output end of each of the charging power tubes, and each of the second resistors is connected to the output end of each of the discharging power tubes; The at least two first resistors are used to balance the voltages at the output ends of all the charging power tubes of the charging switch module when the charging switch module is turned off, and the at least two second resistors are used to balance the voltages at the output ends of all the discharging power tubes of the discharging switch module when the discharging switch module is turned off.

5. The charge and discharge control circuit according to claim 3, characterized in that: The calculation formula for the number of the charging power tube and the discharging power tube is: n≥V Batmax / V MOS_DS ; Wherein, n is the total number of the charging power tubes and the discharging power tubes, V Batmax is the voltage of the battery when it is fully charged, V MOS_DS It is the withstand voltage value of the power tube.

6. The charge and discharge control circuit according to any one of claims 2 to 5, characterized in that: The charge and discharge control circuit also includes a relay, a first end of the relay being connected to the control module, and a second end and a third end of the relay being connected to the second output end of the charging switch module and the second output end of the discharging switch module, respectively; before the discharging switch module or the charging switch module is turned on, the relay is used to control the turning off of the discharging switch module and the charging switch module.

7. The charge and discharge control circuit according to claim 6, characterized in that: When the remaining capacity is greater than a first preset amount of power and the temperature is less than a preset temperature, the control module is further configured to send a pulse signal to the first end of the relay to control the relay to be closed; after the relay is closed 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 end of the relay to control the relay to be opened; When the remaining capacity is less than a second preset power and the temperature is greater than a preset temperature, the control module is further used to send a pulse signal to the first end of the relay to control the relay to be attracted. After the relay is attracted, the control module is further used to send a third drive signal to the discharge switch module to control the discharge switch module to be turned off; wherein, the second preset power is less than or equal to the first preset power.

8. The charge and discharge control circuit according to claim 6, wherein: When the discharge switch module is turned on and the heater is heating, when the inverter is connected to the load, the control module is further used to control the charging switch module to be turned on for a second preset time, and the control module is further used to send a pulse signal to the relay to control the relay to be attracted.

9. The charge and discharge control circuit according to claim 1, wherein: When the battery heats the heater through the discharge channel, 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 output a third drive signal to the discharge switch module to control the discharge switch module to be turned off, thereby controlling the shutoff of the discharge channel from the battery and the discharge switch module to the heater.

10. An energy storage system, characterized in that: The energy storage system comprises: a battery, wherein the battery is provided with a heater and a temperature detection element for detecting the temperature of the battery; An inverter, wherein the inverter is used to connect the power grid and the load; The charge and 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 and discharge control circuit is used to control the charge and discharge process of the battery; and A current detection module is connected to the inverter and the second output end of the discharge switch module, and is used to detect the current value and current direction of the inverter.

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