Lead-acid battery and sodium ion battery hybrid energy storage system

Abstract

The utility model discloses a lead-acid battery and sodium-ion battery mixed energy storage system which comprises a sodium-ion battery pack string, a lead-acid battery, a lead-acid battery management system, a controller module and a heating plate, the lead-acid battery management system comprises a first temperature sensor, a second MCU and an RS485 communication interface, and the second MCU is connected with the first temperature sensor and used for collecting temperature data of the lead-acid battery and sending the temperature data of the lead-acid battery to the controller module through the RS485 communication interface; the heating plate is connected with the sodium-ion battery pack string through the first relay, the controller module controls the first relay to achieve connection and disconnection between the heating plate and the sodium-ion battery pack string, the temperature of the lead-acid battery is stabilized between 20 DEG C and 25 DEG C through the heating plate, and the capacity of the lead-acid battery is kept in the optimal state.

Description

Technical Field

[0001] The utility model belongs to the technical field of batteries, and in particular relates to a hybrid energy storage system of a lead-acid battery and a sodium-ion battery, and a source adjustment, load adjustment (leveling) and capacity display system of a low-voltage (48V) energy storage battery composed of a hybrid of two types of battery cells, a lead-acid battery and a sodium-ion battery. Background Art

[0002] Currently, with the development of sodium-ion battery technology, it has attracted much attention as the safest non-lithium-ion battery in the battery field, with the highest comprehensive advantages in low-temperature characteristics, cost, and energy density. At present, lead-acid batteries have not been able to exit the market due to their market share and residual value. In the fields of household energy storage, computer room backup power supply, etc., lead-acid batteries and lithium batteries have poor low-temperature characteristics, while sodium-ion batteries are not favored by the capital market because of their lack of residual value. Therefore, a hybrid system of lead-acid and sodium-ion batteries is proposed for market use. In actual use, no matter whether the system is in charging or discharging state, the discharge strategy is adjusted according to the current temperature. In low temperature conditions, sodium-ion batteries are given priority for charging and discharging, and in high temperature conditions, lead-acid batteries are given priority for charging and discharging. Summary of the invention

[0003] The technical problem to be solved by the utility model is the problem of the capacity reduction of lead-acid batteries under low temperature conditions in the current market. The utility model proposes a hybrid system of lead-acid and sodium-ion batteries.

[0004] The utility model discloses a hybrid energy storage system of lead-acid battery and sodium-ion battery, comprising a sodium-ion battery string, a sodium-ion battery management system, a lead-acid battery, a lead-acid battery management system, a controller module and a heating plate; one end of the sodium-ion battery string is connected to an external interface negative electrode PGNG through the sodium-ion battery management system, and the other end of the sodium-ion battery string is connected to an external interface positive electrode PVCC+; one end of the lead-acid battery is connected to an external interface negative electrode PGNG through the lead-acid battery management system, and the other end of the lead-acid battery is connected to an external interface positive electrode PVCC+; the controller module is respectively connected to the lead-acid battery management system and the sodium-ion battery management system, and the charge and discharge of the sodium-ion battery string and the lead-acid battery are respectively controlled by the lead-acid battery management system and the sodium-ion battery management system; the lead-acid battery management system comprises a first temperature sensor, a second MCU and an RS485 communication interface, the second MCU is connected to the first temperature sensor, and is used to collect lead-acid battery temperature data, and the lead-acid battery temperature data is sent to the controller module through the RS485 communication interface; the heating plate is connected to the sodium-ion battery string through a first relay, and the controller module realizes the on-off between the heating plate and the sodium-ion battery string by controlling the first relay.

[0005] Through the first temperature sensor, the controller module can obtain the lead-acid battery temperature. When the lead-acid battery temperature is lower than 20 degrees Celsius, the controller module controls the first relay to energize, the sodium-ion battery string supplies power to the heating plate, and stabilizes the lead-acid battery temperature between 20 and 25 degrees Celsius. Within this temperature range, the capacity of the lead-acid battery remains in the best state.

[0006] Furthermore, the lead-acid battery and sodium-ion battery hybrid energy storage system of the utility model also includes a sodium-ion battery management system; one end of the sodium-ion battery string is connected to the external interface negative electrode PGNG after passing through the sodium-ion battery management system, and the other end of the sodium-ion battery string is connected to the external interface positive electrode PVCC+; the controller module is connected to the sodium-ion battery management system, and the controller module controls the external charging and discharging of the sodium-ion battery string through the sodium-ion battery management system.

[0007] Further, the sodium ion battery management system includes a first DCDC power supply module, a first regulator LDO (low dropout regulator, abbreviated as LDO), a first MCU, a multi-channel voltage and temperature acquisition unit, an ADC sampling module, a first sampling resistor, a first level conversion interface, and a sodium ion battery charge and discharge pre-discharge control unit; the first DCDC power supply module is connected to the sodium ion battery string, and the other end of the first DCDC power supply module is connected to the first regulator LDO, and outputs a stable voltage to the ADC sampling module, the first MCU and the surrounding CAN circuit; the multi-channel voltage and temperature acquisition unit is connected to the sodium ion battery string and the first MCU, and is used to collect single-cell voltage and temperature data in the sodium ion battery string, and send it to the first MCU, and the first MCU then sends the single-cell voltage and temperature data in the sodium ion battery string to the control module through the CAN circuit; one end of the first sampling resistor is connected to the sodium ion battery string, and the other end is connected to the sodium ion battery charge and discharge pre-discharge control unit; the ADC sampling module is connected in parallel to the first sampling resistor connection section and the first MCU, and is used to collect voltage through the first sampling resistor, and send the collected voltage to the first MCU, The first MCU then sends the voltage to the control module through the CAN circuit; the first MCU is connected to the sodium ion battery charge, discharge and pre-discharge control unit through the first level conversion interface, and is used to control the sodium ion battery charge, discharge and pre-discharge control unit.

[0008] Furthermore, the sodium ion battery charge, discharge and pre-discharge control unit includes a charging relay, a discharging relay, two pre-discharge relays, and four diodes; each diode is connected in parallel with a relay, the charging relay is connected in series with the discharging relay, and the two pre-discharge relays are connected in series and connected at both ends of the discharging relay; by controlling the disconnection and attraction of the relay, the charging, discharging and pre-discharging of the sodium ion battery string are realized.

[0009] When the control module sends a message to the first MCU through the CAN circuit that the sodium-ion battery string is the power supply, the first MCU controls the charging relay and the two pre-discharge relays to be attracted through the first level conversion interface. At this time, the discharge relay is in the disconnected state and pre-discharges to the outside; the controller module receives a communication message from the external load device requesting discharge, and the controller module notifies the first MCU through the CAN communication interface. The first MCU controls the discharge relay to open and starts discharging to the outside;

[0010] When the control module sends a message for charging the sodium-ion battery string to the first MCU through the CAN circuit, the first MCU controls the charging relay and the discharging relay to open through the first level conversion interface, and the pre-discharging relay is in the disconnected state.

[0011] Further, the lead-acid battery management system includes a second DCDC power supply module, a second MCU, a second voltage regulator LDO, a first temperature sensor, a voltage sampling circuit, an operational amplifier, an RS485 communication interface and a second sampling resistor;

[0012] The second DCDC power supply module is connected to a lead-acid battery, and the other end of the second DCDC power supply module is connected to a second voltage regulator LDO, and the second voltage regulator LDO outputs a stable voltage to power the second MCU and the operational amplifier module;

[0013] The second MCU is connected to the first temperature sensor and is used to collect the current ambient temperature;

[0014] The second MCU is connected to the positive electrode of the lead-acid battery through a voltage sampling circuit to obtain the total voltage of the lead-acid battery;

[0015] One end of the second sampling resistor is connected to the lead-acid battery, and the other end is connected to the lead-acid battery charge and discharge pre-discharge control unit; the two input ends of the operational amplifier are connected in parallel to the two ends of the second sampling resistor, and the output end of the operational amplifier is connected to the main control second MCU. The second MCU obtains the voltage of the second sampling resistor through the operational amplifier, and the second MCU sends the voltage to the control module through the RS485 communication interface;

[0016] The second MCU is connected to the lead-acid battery charge, discharge and pre-discharge control unit via a second level conversion interface, and is used to control the lead-acid battery charge, discharge and pre-discharge control unit.

[0017] Furthermore, the lead-acid battery charging, discharging and pre-discharging control unit has the same structure as the sodium battery charging, discharging and pre-discharging control unit, and the lead-acid battery charging, discharging and pre-discharging control unit includes a charging relay, a discharging relay, two pre-discharging relays, and four diodes; each diode is connected in parallel with a relay, the charging relay and the discharging relay are connected in series, and the two pre-discharging relays are connected in series and connected at both ends of the discharging relay; by controlling the disconnection and attraction of the relay, the charging, discharging and pre-discharging of the lead-acid battery are realized.

[0018] When the control module sends a message that the lead-acid battery is the power supply to the second MCU through the RS485 communication interface, the second MCU controls the charging relay and the two pre-discharging relays to be attracted through the second level conversion interface to pre-discharge the external device, and the discharge relay is in the disconnected state at this time; the controller module receives the communication message requesting discharge from the external load device, and the controller module notifies the second MCU through the RS485 communication interface, and the second MCU controls the discharge relay to open and start discharging to the external device;

[0019] When the control module sends a message for charging the sodium-ion battery string to the second MCU through the RS485 communication interface, the second MCU controls the charging relay and the discharging relay to open through the second level conversion interface; when the second MCU detects the charging micro-current through the second sampling resistor, the second MCU controls the discharge relay in its lead-acid battery charge and discharge pre-discharge control unit to be pulled in, and disconnects the two pre-discharge relays for pre-discharge;

[0020] Furthermore, the hybrid energy storage system of lead-acid battery and sodium-ion battery of the utility model also includes a human-machine control and display module and a second temperature sensor; the human-machine control and display module is connected to the control module, and is used to display the battery string and the charge and discharge current of the lead-acid battery and the display power; the second temperature sensor is connected to the control module, and is used to collect the ambient temperature. The displayed power is the maximum power storage energy that the lead-acid battery can have under the current temperature plus the maximum power storage energy that the sodium-ion battery can have under the current temperature; it solves the problem that the battery capacity SOC of the lead-acid battery is inaccurate only by collecting voltage, where SOC refers to the percentage of the remaining power of the battery to the rated capacity under specific conditions.

[0021] Beneficial effects: When the energy storage system needs to be charged, the external interface (PVCC+ and PGND) is connected to the external charger, and the internal battery exists as the load of the charger. If the sodium-ion battery charger is connected, the lead-acid battery part needs to be cut off at the negative pole and the negative pole PGND of the external interface. The load is adjusted to the sodium-ion battery string. When charging is completed, the sodium-ion battery string avoids overcharging. When the first MCU determines that the charging is completed, it will actively turn off the sodium-ion battery charging and discharging pre-discharge control unit and cut off the sodium-ion battery string B- from the external port. If the lead-acid battery charger is connected, the lead-acid battery charging voltage is high and does not have a communication function. The controller module will immediately notify the sodium-ion battery string to turn off the charging and discharging and prevent the electric circuit to protect the sodium-ion battery string from the high voltage when the lead-acid battery is charged. The lead-acid battery BMS can distinguish the direction of current flow and calculate the current value by sampling the voltage on the resistor. The second MCU has a built-in power metering system that can accurately calculate the percentage of power that can change with temperature in the lead-acid battery. It can be provided to the host computer in real time to meet the energy and power scheduling strategy of the EMS (energy management system) or PMS (power management system) of the energy host computer. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a circuit structure diagram of the utility model. DETAILED DESCRIPTION

[0023] like Figure 1 As shown, a lead-acid battery and sodium-ion battery hybrid energy storage system of the utility model comprises a sodium-ion battery string, a sodium-ion battery management system, a lead-acid battery, and a lead-acid battery management system;

[0024] The sodium ion battery management system includes a first DCDC power supply module, a main control first MCU, a CAN communication module, a multi-channel voltage and temperature acquisition unit, a high-precision ADC sampling module, a sampling constantan, a level conversion interface, and a charge and discharge pre-discharge control unit.

[0025] The total power of the sodium-ion battery pack after being connected in series always powers the DC / DC1 module. The generated 12V long-term power powers the first voltage regulator LDO, and also powers the level conversion interface in the sodium-ion battery management system. The low voltage 3.3V output by LDO-1 powers the first MCU and the surrounding CAN circuits and IIC_ADC sampling modules. The first MCU obtains the single-cell voltage and temperature data of the battery cell from the multi-channel voltage and temperature acquisition unit through the SPI bus. The ADC sampling module obtains the voltage signal on the constantan wire and converts the charge and discharge current information read out into a data code and sends it to the first MCU through the IIC communication bus. The CAN interface circuit on the right side of the first MCU is used for the first MCU to communicate with the controller module on the right side. The first MCU controls the sodium-ion battery charge, discharge and pre-discharge control unit by driving the level conversion interface on its lower side.

[0026] Among them, the sodium-ion battery charging, discharging and pre-discharging control unit is the charging circuit, discharging circuit and external pre-discharging circuit of the sodium-ion battery from the sampling resistor to the PGND external interface. When the controller module commands the sodium-ion battery string to be powered, the charging and pre-discharging relays are energized, and the sodium-ion battery string pre-discharges to the outside. The controller module receives the communication message from the external load device requesting discharge. The controller module notifies the first MCU through the CAN communication interface, and the first MCU controls the discharge port to open. Start discharging to the outside. When the external port is connected to a charger, the external charger communicates with the controller module and requests to charge the sodium-ion battery string. The first MCU obtains the charging request message sent by the controller module and closes the charging relay and the discharge relay.

[0027] The lead-acid battery management system includes a second DCDC power supply module, a second MCU, an RS485 communication interface, a voltage regulator LDO, an operational amplifier, a sampling resistor, and a temperature collector.

[0028] The total power of the lead-acid battery group after being connected in series always powers the DC / DC2 module. The generated 12V power supply powers the controller module and the level conversion interface in the lead-acid battery BMS system. The 12V power supply also generates a 3.3V power supply through the second regulator LDO to power the second MCU. The low-voltage 3.3V also powers the surrounding RS485 circuit and operational amplifier module. The second MCU collects analog quantities from the first temperature sensor to obtain the current ambient temperature data, the second MCU obtains the total voltage of the lead-acid battery from the voltage sampling circuit, and the second MCU obtains the voltage signal on the copper wire from the operational amplifier end to calculate the charge and discharge current value. The RS485 interface circuit on the left side of the second MCU is used for the second MCU to communicate with the controller module. The second MCU controls the lead-acid battery charge, discharge and pre-discharge control unit by controlling the level conversion interface in the lead-acid battery BMS system.

[0029] Among them, the lead-acid battery charging, discharging and pre-discharging control unit is the charging circuit, discharging circuit and pre-discharging circuit for the lead-acid battery from the B-end to the PGND external interface. When the controller module sends a communication message that the lead-acid battery is a power supply to the second MCU, the charging relay and the pre-discharging relay are energized, and the lead-acid battery pre-discharges to the outside. The controller module receives the communication message requesting discharge from the external load device, and the controller module notifies the second MCU via the RS485 communication interface. The second MCU controls the discharge port to open and starts to discharge to the outside. When the external port is connected to a lead-acid charger, the controller module sends a charging request to the second MCU, and the second MCU obtains the charging request message sent by the controller module. The second MCU controls the opening of the charging relay and two pre-discharging relays. When the second MCU sampling resistor detects the charging micro-current, the second MCU controls the discharge relay in its lead-acid battery charging, discharging and pre-discharging control unit to energize, and disconnects the two pre-discharging relays for pre-discharging.

[0030] The utility model provides a lead-acid battery and sodium-ion battery hybrid energy storage system, which also includes a display system. The display system includes an RS485 communication interface, a human-machine control and display module, and a second temperature sensor.

[0031] The multi-channel controller module is used to synchronously collect the voltage of the sodium-ion battery string and the lead-acid battery. The SOC information of the sodium-ion battery cell is obtained from the sodium-ion battery battery management system and transmitted to the controller module via the CAN interface. The SOC information of the lead-acid battery is obtained from the lead-acid battery BMS and transmitted to the controller module via the RS485 interface. The controller module can transmit status information to other embedded controllers via the RS485 communication interface.

[0032] The human-machine control and display module is used to display the charging and discharging current and power capacity of the sodium-ion battery strings and lead-acid batteries on both sides. At the same time, the discharge strategy can be adjusted through user operation, and the current and power capacity of the lithium battery and lead-acid battery can be displayed.

[0033] Both the sodium-ion battery management system and the lead-acid battery management system use the ampere-hour integration method to calculate the battery power, and make capacity corrections based on the current temperature value and the battery voltage value. Sodium-ion batteries and lead-acid batteries can be charged independently. The two ends of the lithium battery and the lead-acid battery are respectively connected to the external interfaces PVCC+ and PGND, which are independently controlled by the controller module. When the lead-acid battery charger is connected, because the lead-acid charger does not have a communication function and the floating charge voltage is high, the sodium-ion battery side controls the first MCU to accept the command of the intermediate controller module and turn off the sodium-ion charging and discharging control unit and the sodium-ion battery charging and discharging pre-charging control unit. The second MCU of the lead-acid battery control unit receives the command, disconnects the lead-acid battery discharge control unit, and automatically starts the pre-discharge charging. When the lead-acid battery SOC is full, the second MCU sends a full charge instruction to the controller module, and the controller module receives the full charge instruction and displays it on the display interface.

[0034] The controller module has a built-in ARM Cortex-A7 microprocessor platform, which has an ADC sampling interface, a CAN communication interface, and a TTL serial communication interface. Its ADC sampling interface can obtain the battery voltage from the sodium-ion battery side and the lead-acid battery side. Its CAN communication interface and TTL serial communication interface can communicate with the first MCU on the sodium-ion battery side and the second MCU on the lead-acid battery side to obtain power data and the battery's external output status. When the system is at a low temperature (the temperature collected by the second temperature sensor is below 10°C), the capacity of the lead-acid battery decreases, and the system needs to discharge or charge the lead-acid battery first. At this time, due to the good low-temperature characteristics of the sodium-ion battery, the controller module can control the relay unit of the battery heating plate to heat the ambient temperature of the lead-acid battery to 20-25 degrees Celsius. Ensure that the capacity of the lead-acid battery does not decay.

[0035] Battery power calculation scheme:

[0036] Lead-acid battery energy: Lead-acid battery voltage x ampere-hours = total lead-acid battery energy;

[0037] Sodium battery energy: total battery string voltage x ampere-hours = total sodium ion battery energy;

[0038] Total capacity: The maximum storage capacity of a lead-acid battery at the current temperature + the maximum storage capacity of a sodium battery at the current temperature.

[0039] System power percentage: (remaining power of lead-acid battery at current temperature + remaining power of sodium battery at current temperature) / (total power).

Claims

1. A lead-acid battery and sodium-ion battery hybrid energy storage system, characterized in that: It includes sodium-ion battery strings, lead-acid batteries, lead-acid battery management systems, controller modules and heating plates; One end of the lead-acid battery is connected to the negative electrode of the external interface after passing through the lead-acid battery management system, and the other end of the lead-acid battery is connected to the positive electrode of the external interface; The controller module is connected to a lead-acid battery management system, and the controller module controls the charging and discharging of the sodium-ion battery string and the lead-acid battery through the lead-acid battery management system; The lead-acid battery management system includes a first temperature sensor, a second MCU and a communication interface, the second MCU is connected to the first temperature sensor, and is used to collect lead-acid battery temperature data, and send the lead-acid battery temperature data to the controller module through the communication interface; The heating plate is connected to the sodium ion battery string through a first relay, and the controller module realizes the on-off between the heating plate and the sodium ion battery string by controlling the first relay.

2. A lead-acid battery and sodium-ion battery hybrid energy storage system according to claim 1, characterized in that: Also included is a sodium-ion battery management system; One end of the sodium ion battery string is connected to the external interface negative electrode after passing through the sodium ion battery management system, and the other end of the sodium ion battery string is connected to the external interface positive electrode; The controller module is connected to the sodium-ion battery management system, and the controller module controls the external charging and discharging of the sodium-ion battery string through the sodium-ion battery management system.

3. A lead-acid battery and sodium-ion battery hybrid energy storage system according to claim 2, characterized in that: The sodium ion battery management system includes a first DCDC power supply module, a first voltage regulator LDO, a first MCU, a multi-channel voltage and temperature acquisition unit, an ADC sampling module, a first sampling resistor, a first level conversion interface, and a sodium ion battery charge and discharge pre-discharge control unit; The first DCDC power supply module is connected in series with the sodium ion battery pack, and the other end of the first DCDC power supply module is connected to the first voltage regulator LDO to output a stable voltage to the ADC sampling module, the first MCU and the surrounding CAN circuit; The multi-channel voltage and temperature acquisition unit is connected to the sodium ion battery string and the first MCU, and is used to collect the voltage and temperature data of a single cell in the sodium ion battery string and send it to the first MCU. The first MCU then sends the voltage and temperature data of a single cell in the sodium ion battery string to the control module through the CAN circuit; One end of the first sampling resistor is connected to the sodium ion battery string, and the other end is connected to the sodium ion battery charge and discharge pre-discharge control unit; the ADC sampling module is connected in parallel to the first sampling resistor connection section and the first MCU, and is used to collect voltage through the first sampling resistor and send the collected voltage to the first MCU, and the first MCU then sends the voltage to the control module through the CAN circuit; The first MCU is connected to the sodium ion battery charge, discharge and pre-discharge control unit through a first level conversion interface, and is used to control the sodium ion battery charge, discharge and pre-discharge control unit.

4. A lead-acid battery and sodium-ion battery hybrid energy storage system according to claim 3, characterized in that: The sodium ion battery charge, discharge and pre-discharge control unit comprises a charging relay, a discharging relay, two pre-discharge relays and four diodes; each diode is connected in parallel with a relay, the charging relay is connected in series with the discharging relay, and the two pre-discharge relays are connected in series and connected at both ends of the discharging relay; the charging, discharging and pre-discharging of the sodium ion battery string are realized by controlling the disconnection and attraction of the relays.

5. The lead-acid battery and sodium-ion battery hybrid energy storage system according to claim 1, characterized in that: The lead-acid battery management system also includes a second DCDC power supply module, a second MCU, a second voltage regulator LDO, a voltage sampling circuit, an operational amplifier, and a second sampling resistor; The second DCDC power supply module is connected to a lead-acid battery, and the other end of the second DCDC power supply module is connected to a second voltage regulator LDO, and the second voltage regulator LDO outputs a stable voltage to power the second MCU and the operational amplifier module; The second MCU is connected to the positive electrode of the lead-acid battery through a voltage sampling circuit to obtain the total voltage of the lead-acid battery; One end of the second sampling resistor is connected to the lead-acid battery, and the other end is connected to the lead-acid battery charge and discharge pre-discharge control unit; the two input ends of the operational amplifier are connected in parallel to the two ends of the second sampling resistor, and the output end of the operational amplifier is connected to the main control second MCU. The second MCU collects the voltage of the second sampling resistor through the operational amplifier, and the second MCU sends the voltage to the control module through the communication interface; The second MCU is connected to the lead-acid battery charge, discharge and pre-discharge control unit via a second level conversion interface, and is used to control the lead-acid battery charge, discharge and pre-discharge control unit.

6. A lead-acid battery and sodium-ion battery hybrid energy storage system according to claim 5, characterized in that: The lead-acid battery charging, discharging and pre-discharging control unit comprises a charging relay, a discharging relay, two pre-discharging relays and four diodes; each diode is connected in parallel with a relay, the charging relay is connected in series with the discharging relay, and the two pre-discharging relays are connected in series and connected at both ends of the discharging relay; the charging, discharging and pre-discharging of the lead-acid battery are realized by controlling the disconnection and attraction of the relays.

7. A lead-acid battery and sodium-ion battery hybrid energy storage system according to claim 2, characterized in that: The hybrid energy storage system also includes a human-machine control and display module and a second temperature sensor; The human-machine control and display module is connected to the control module and is used to display the charging and discharging current of the battery string and the lead-acid battery and the display power; The second temperature sensor is connected to the control module and is used to collect the ambient temperature.

Images