JP2019009002A - Power supply device comprising lithium ion secondary battery, and method of controlling the same - Google Patents

Abstract

To provide a power supply device capable of improving performance of a lithium ion secondary battery in a low-temperature state, or to provide a method of controlling the same.SOLUTION: A power supply device comprises: a lithium ion secondary battery; a control circuit; a discharge circuit; and a measurement circuit that measures a state of the lithium ion secondary battery. The control circuit applies a discharge current from the lithium ion secondary battery to the discharge circuit for the purpose of raising a temperature of the lithium ion secondary battery.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power supply device including a lithium ion secondary battery and a control technology thereof, and more particularly to a power supply device including a lithium ion secondary battery that can be used at a low temperature and a control technology thereof.

  Lithium ion secondary batteries are small and light, and have a high energy density per unit volume. For this reason, it is being used widely, and its demand is expected to increase further in the future. Lithium ion secondary batteries only move lithium ions in the electrolyte during charge / discharge operation, and are not a method of storing power using chemical changes like many other secondary batteries. It has a relatively broad advantage.

  However, the properties of the lithium ion mobile electrolyte change depending on the temperature in the charge / discharge state. In a lithium ion secondary battery, the performance of the lithium ion secondary battery changes depending on the movement characteristics of lithium ions moving in the electrolyte. When the temperature is lowered, the state of the electrolyte is changed, and the lithium ion transfer characteristics in the electrolyte are deteriorated. As a result, the performance of the lithium ion secondary battery decreases with a decrease in temperature in the environment where the lithium ion secondary battery is placed.

  Lithium ion secondary batteries are superior in performance to other secondary batteries, and there is a desire to use lithium ion secondary batteries even at low temperatures. However, in a low temperature state of minus 20 ° C. or minus 30 ° C., for example, the viscosity of the electrolyte of the lithium ion secondary battery increases, the mobility of lithium ions decreases, and the performance as a secondary battery decreases. For this reason, there has been proposed a technique for improving the electrolyte and suppressing an increase in the viscosity of the electrolyte of the lithium ion secondary battery in a low temperature state.

JP, 2006-134261, A Japanese Patent Laying-Open No. 2015-5426

  Patent Documents 1 and 2 propose an electrolyte for a lithium ion secondary battery in which the decrease in lithium ion mobility is small even in a low temperature state. However, it cannot be said that sufficient performance is obtained.

  The objective of this invention is providing the power supply device provided with the lithium ion secondary battery which can improve the performance of a lithium ion secondary battery in a low-temperature state, or its control method.

  A first invention includes a lithium ion secondary battery, a control circuit, a discharge circuit, and a measurement circuit that measures a state of the lithium ion secondary battery, and the control circuit includes the lithium ion secondary battery. In order to raise temperature, it is a power supply device which made it flow a discharge current from the said lithium ion secondary battery to the said discharge circuit.

  According to a second invention, in the first invention, the maximum value of the discharge current flowing from the lithium ion secondary battery to the discharge circuit in order to increase the temperature of the lithium ion secondary battery is that of the lithium ion secondary battery. The power supply device is characterized in that the current value is larger than the maximum current value of the lithium ion secondary battery in normal operation.

  According to a third invention, in the first invention, a display device is further provided, and the control circuit supplies a discharge current from the lithium ion secondary battery to the discharge circuit in order to increase the temperature of the lithium ion secondary battery. When the battery is supplied, the power supply device displays that the display device is in an operation mode for increasing the temperature of the lithium ion secondary battery.

  A fourth invention is characterized in that, in the third invention, the display device further displays information related to a scheduled time until the end of the operation mode for increasing the temperature of the lithium ion secondary battery. It is a power supply device.

  5th invention is the control method of the power supply device of 1st invention, Comprising: The said control circuit raises the temperature of the said lithium ion secondary battery based on the measurement result of the said measurement circuit, Temperature rising operation mode And determining whether or not the operation of the temperature rise operation mode is necessary, and performing control to flow a current from the lithium ion secondary battery to the discharge circuit. It is a control method.

  According to a sixth aspect of the present invention, in the method for controlling a power supply device according to the fifth aspect, the control circuit obtains a current value or energization time to be passed through the discharge circuit from the measurement result of the measurement circuit, and the control circuit The method of controlling a power supply device is characterized by controlling a current flowing through the power supply.

  ADVANTAGE OF THE INVENTION According to this invention, the power supply device which can improve the performance of a lithium ion secondary battery in a low temperature state, or its control method can be obtained.

It is explanatory drawing explaining the concept of the power supply device provided with the lithium ion secondary battery to which this invention is applied. It is explanatory drawing explaining the relationship between the temperature of a lithium ion secondary battery, and an operation mode. It is a flowchart explaining control of the power supply device provided with the lithium ion secondary battery. It is explanatory drawing explaining the display content of the display apparatus 160 in the temperature rise operation mode 20. FIG. It is explanatory drawing explaining the relationship between the temperature of the lithium ion secondary battery 110, and the magnitude | size of the electric current A1 for temperature rise, or a pulse width or the frequency | count of a pulse.

1. Configuration of Power Supply Device 100 and Description of Basic Operation of Power Supply Device 100 FIG. 1 shows a configuration of power supply device 100 according to an embodiment of the present invention. The power supply device 100 includes a lithium ion secondary battery 110. In order to store electric power in the lithium ion secondary battery 110, electric power is supplied from the charging power source 190 to the lithium ion secondary battery 110 via the external connection circuit 180 and the internal connection circuit 140, and the lithium ion secondary battery 110 At 110, power is stored. Since the lithium ion secondary battery 110 stores DC power, when the charging power supply 190 supplies AC power, the AC / DC that converts AC to DC between the charging power supply 190 and the lithium ion secondary battery 110 is used. A DC conversion circuit is provided.

  When the electric power stored in the lithium ion secondary battery 110 is supplied to the electric load 182, the electric power stored in the lithium ion secondary battery 110 is supplied to the electric load 182 via the internal connection circuit 140 and the external connection circuit 180. Supplied. When the electric load 182 requires AC power, a DC / AC conversion circuit that converts direct current into alternating current is provided between the lithium ion secondary battery 110 and the electric load 182.

  Charge control for storing power in the lithium ion secondary battery 110 and power supply control for supplying power to the electric load 182 are performed by a control circuit 150 including a computer. When the operator directly operates the lithium ion secondary battery 110, it can be operated from the operation unit 142, and charging of the lithium ion secondary battery 110 and power supply to the electric load 182 are performed from the operation unit 142. It can be carried out. In addition, the above-described charging of power to the lithium ion secondary battery 110 and supply of power to the electrical load 182 can be performed based on information from an external device. Such a command can be issued from an external device, and the command is sent from the external device to the control circuit 150 via the information terminal 144.

  The power supply device 100 includes a current measuring circuit 152 that measures the entire input or output current of the lithium ion secondary battery 110, the overall terminal voltage of the lithium ion secondary battery 110, and the voltage of each cell constituting the lithium ion secondary battery 110. A voltage measurement circuit 154 that measures the terminal voltage and a temperature measurement device 156 that measures the surface and internal temperature of the lithium ion secondary battery 110 are provided to constantly detect the state of the power supply device 100 and to diagnose the abnormal state. Is always on. The diagnosis history and measurement data are stored in the storage device 158, and can be read and confirmed, for example, during maintenance inspection. A display device 160 is provided and used not only for input / output of information but also for displaying the operation mode and state of the power supply device 100.

2. Temperature rise operation mode When the power supply device 100 is placed in a low temperature environment, the internal temperature of the lithium ion secondary battery 110 also decreases, and the state of the electrolyte in each cell of the lithium ion secondary battery 110 changes as described above. The mobility of lithium ions in the electrolyte decreases. As a result, the performance of the lithium ion secondary battery 110 is degraded. The control circuit 150 can detect the temperature of the lithium ion secondary battery 110 by the temperature measuring device 156, and can detect a decrease in performance of the lithium ion secondary battery 110 due to a temperature decrease. Or the performance fall of the lithium ion secondary battery 110 by temperature fall can also be detected from the detection value of the current measurement circuit 152 or the voltage measurement circuit 154.

  The performance degradation of the lithium ion secondary battery 110 due to the temperature decrease can be improved by increasing the internal temperature of the lithium ion secondary battery 110. The power supply apparatus 100 includes a discharge circuit 146 that allows a discharge current of the lithium ion secondary battery 110 to flow. By passing the current from the lithium ion secondary battery 110 to the discharge circuit 146, the internal temperature of the lithium ion secondary battery 110 can be raised. A temperature increase operation mode in which the internal temperature of the lithium ion secondary battery 110 is increased will be described with reference to FIG.

  When the internal temperature of the lithium ion secondary battery 110 decreases, the performance decreases accordingly. As an example, when the lithium ion secondary battery 110 is desired to operate at −t1 ° C. or higher, the control circuit 150 first uses the temperature measuring device 156 to detect the lithium ion 2. It is detected that secondary battery 110 is in a state of −t1 ° C. or lower. Based on this detection, the control circuit 150 enters a temperature increase operation mode, and supplies current from the lithium ion secondary battery 110 to the discharge circuit 146 via the internal connection circuit 140. The discharge circuit 146 is a circuit for supplying a current for increasing the temperature of the lithium ion secondary battery 110. The current temporarily exceeds the maximum discharge current of the lithium ion secondary battery 110 or the maximum discharge of the lithium ion secondary battery 110. A current several times or even several tens times the current can be passed. When such a large current flows for a long time, there is a great danger. However, when a large current is flowed only for an extremely short period, the internal temperature of the lithium ion secondary battery 110 is originally a low temperature state. There is no sex.

  In FIG. 2, since the temperature of the lithium ion secondary battery 110 is lower than −t1 ° C., the temperature increase operation mode 20 is controlled, and the temperature increase current A1 exceeding the maximum discharge current A0 of the lithium ion secondary battery 110. Is supplied from the lithium ion secondary battery 110 to the discharge circuit 146. As shown in graph 1 in FIG. 2, the temperature of the lithium ion secondary battery 110 rises due to the flow of the temperature raising current A1. As a result, the temperature of the lithium ion secondary battery 110 becomes higher than −t1 ° C., and the normal operation mode 30 is controlled instead of the temperature increase operation mode 20. The discharge circuit 146 is disconnected from the lithium ion secondary battery 110 by the internal connection circuit 140, and the operating current A2 is supplied from the lithium ion secondary battery 110 to the electric load 182 via the internal connection circuit 140 and the external connection circuit 180. . The operating current A2 changes due to a request from the electric load 182 but does not exceed the maximum discharge current A0.

  As described above, the purpose of increasing the temperature A1 is to positively increase the internal temperature of the lithium ion secondary battery 110 in a short time. In this embodiment, the maximum discharge current A0 of the lithium ion secondary battery 110 is used. Current that exceeds is flowing. In order to flow such a large current, an electric load having a small resistance value is required, and a discharge circuit 146 is provided.

Although the current supply mode to the electric load 182 is illustrated as the normal operation mode 30 in FIG. 2, a power supply mode from the charging power source 190 to the lithium ion secondary battery 110 may be used. In this case, the operating current A2 is a current in the direction opposite to that shown in FIG.
3. Description of Operation of Control Circuit 150 The operation of the control circuit 150 according to the temperature rise operation mode 20 in the power supply apparatus 100 will be described using a control flowchart S500 shown in FIG. In a state where the power supply device 100 itself is not used, even if the temperature of the lithium ion secondary battery 110 is in a low temperature state such as minus 30 ° C., it is not necessary to increase the temperature. Therefore, the operation of the lithium ion secondary battery 110 based on the temperature increase operation mode 20 for increasing the temperature of the lithium ion secondary battery 110 is not necessary. When there is no command from the information terminal 144 and there is no input related to the operation from the operation unit 142, the command is waiting. In this state, the control circuit 150 checks the presence / absence of an operation command for the control circuit 150 at regular intervals. If there is no special operation command, the temperature increase operation mode 20 is not performed in this embodiment.

  When an operation command is input by the operator from the operation unit 142 or an operation command is received from another device via the information terminal 144, the control circuit 150 operates using the lithium ion secondary battery 110. Judge as necessary. The control circuit 150 determines that there is an operation command in step S510, and the execution of the control circuit 150 moves to step S512. In order to start the operation using the lithium ion secondary battery 110, it is necessary to detect the state of the lithium ion secondary battery 110. In step S512, the state of the lithium ion secondary battery 110 is detected. . Specifically, as an example, measurement regarding the state of the lithium ion secondary battery 110 is performed by the current measurement circuit 152, the voltage measurement circuit 154, and the temperature measurement device 156.

  The measurement result in step S512 is recorded in the storage device 158. As described above, the storage device 158 stores not only measurement data but also past diagnosis results, and stores a history of the state of the lithium ion secondary battery 110 and a history of measurement results. Therefore, the state change of the lithium ion secondary battery 110 can be confirmed. Based on the measurement result in step S512, the previous measurement result and the change in state, etc., a determination regarding the safety of the lithium ion secondary battery 110 is made in step S514. If an abnormality is detected, step S515 is executed, the contents of the abnormal state are displayed on the display device 160, and the control circuit 150 further performs control to avoid danger. Raise alarms as needed. As control for avoiding danger, for example, the internal connection circuit 140 is operated to perform an operation of disconnecting the lithium ion secondary battery 110 from other devices and circuits. As a result, the above-described state of the lithium ion secondary battery 110 may be avoided.

  When the control circuit 150 determines that the lithium ion secondary battery 110 is in a safe state from the measurement result regarding the lithium ion secondary battery 110 in step S512 and the data measured earlier, the execution of the control circuit 150 moves to step S516. . In step S516, it is determined whether the lithium ion secondary battery 110 is in a low temperature state. The determination of the low temperature state of the lithium ion secondary battery 110 is performed by determining whether the temperature of the lithium ion secondary battery 110 described with reference to FIG. 2 is −t1 ° C. or lower, and in the state of −t1 ° C. or lower, You may judge that the state of the secondary battery 110 is a low temperature state. Or you may judge by another method.

  If it is determined that the state of the lithium ion secondary battery 110 is a low temperature state, the performance of the lithium ion secondary battery 110 is in a degraded state, and the control circuit 150 is connected via the operation unit 142 or the information terminal 144. The control circuit 150 determines that the supported operation cannot be performed, and executes control of the temperature increase operation mode 20 for increasing the temperature of the lithium ion secondary battery 110.

  On the other hand, when the control circuit 150 determines that the state of the lithium ion secondary battery 110 is not a low temperature state, the execution operation of the control circuit 150 moves from step S516 to step S517, and is supported via the operation unit 142 or the information terminal 144. Then, the operation using the lithium ion secondary battery 110 is executed. As this operation, for example, power supply from the lithium ion secondary battery 110 to the electric load 182 and charging operation of the lithium ion secondary battery 110 that supplies power from the charging power source 190 to the lithium ion secondary battery 110 are included. is there.

  If it is determined in step S516 that the state of the lithium ion secondary battery 110 is a low temperature state, the operation of the control circuit 150 proceeds to step S520. In step S520, execution of the temperature increase operation mode 20 is displayed on the display device 160. Thus, the operator can know that the temperature rising operation mode 20 is executed before executing the normal operation mode 30, and further, when the temperature increasing operation mode 20 is completed, the normal operation mode 30 is executed. I can know. Further, the display device 160 also displays the scheduled execution time of the temperature increase operation mode 20.

  FIG. 4 is a display screen of the display device 160. In the display field 162, “execution of the temperature increase operation mode 20 of the lithium ion secondary battery 110 is being performed” is displayed as the execution mode, and the scheduled execution time is further displayed in the display field 164. The Next, in step S520, the magnitude of the temperature increasing current A1 is determined. When the temperature of the lithium ion secondary battery 110 is low, the temperature of the lithium ion secondary battery 110 can be increased in a short time by increasing the value of the temperature increasing current A1. In step S522, the magnitude of the temperature increasing current A1 is determined based on the measurement result. In addition, although the scheduled completion | finish time of the temperature rise operation mode 20 in the display column 164 may be displayed with a character, you may display with a graph. In this case, the relationship between the executed time with respect to the scheduled time and the remaining time is displayed in a graph state.

  The relationship between the temperature of the lithium ion secondary battery 110 and the temperature increasing current A1 is shown in a graph 30 of FIG. The value of the temperature increasing current A1 increases as the temperature of the lithium ion secondary battery 110 decreases. The graph 20 shows the energization time of one temperature rise current A1. The lower the temperature of the lithium ion secondary battery 110, the longer the energization time of the current A1 for temperature increase. Graph 10 shows the number of pulses supplied. The current may flow continuously during the energizing time of the temperature increasing current A1 shown in the graph 20, but a current pulse of unit time is generated and the number of pulses corresponds to the energizing time of the temperature increasing current A1. Also good.

  The relationship between the graph 30, the graph 20, and the graph 10, which is data illustrated in FIG. 5, is stored in the storage device 158 in advance. Based on the data stored in the storage device 158 in advance in step S522, the current value of the temperature increasing current A1, the energization time, or the number of occurrences of pulses is determined and executed in step S524. For example, the discharge circuit 146 includes a resistor, a semiconductor switching element, and a current control circuit, and the semiconductor switching element and the current control circuit of the discharge circuit 146 operate based on a command from the control circuit 150, and are determined in step S522. Control is executed.

  The execution of the control circuit 150 returns to step S512 again, and the state 110 during execution of the temperature rise operation mode 20 is measured in step S512, safety is confirmed in step S514, and the temperature rise operation mode 20 is changed in step S516. It is determined whether to end. Further, in step S522, the control content in the temperature increase operation mode 20 is determined in a state in which a new measurement result relating to the lithium ion secondary battery 110 is reflected, and is executed in step S524.

4). Effect of Example According to this example, there is an effect that the temperature of the lithium ion secondary battery 110 can be raised in a short time. In addition, there is an effect that safety can be secured. The control contents of the graph 30, the temperature increase operation mode 20, and the graph 10 of FIG. 5 may be selectively executed or may be executed in combination. When the power supply device 100 is used in a cold region, in this embodiment, the lithium ion secondary battery 110 can be raised to a temperature at which the lithium ion secondary battery 110 normally operates in a short time. Therefore, there is an effect that it can be used as a lithium ion secondary battery power source even in a cold region.

  DESCRIPTION OF SYMBOLS 10 ... Graph, 20 ... Graph, 30 ... Graph, 100 ... Power supply device, 110 ... Lithium ion secondary battery, 140 ... Internal connection circuit, 142 ... Operation part, 144 ... Information terminal, 146 ... Discharge circuit, 150 ... Control circuit, 152 ... Current measurement circuit, 154 ... Voltage measurement circuit, 156 ... Temperature measurement device, 158 ... Memory Device: 160 ... Display device, 162 ... Display field, 164 ... Display field, 180 ... External connection circuit, 182 ... Electric load, 190 ... Power supply for charging.

Claims (6)

  A lithium ion secondary battery; a control circuit; a discharge circuit; and a measurement circuit for measuring the state of the lithium ion secondary battery. The control circuit increases the temperature of the lithium ion secondary battery. A power supply apparatus, wherein a discharge current is allowed to flow from the lithium ion secondary battery to the discharge circuit.   2. The power supply device according to claim 1, wherein a maximum value of a discharge current flowing from the lithium ion secondary battery to the discharge circuit in order to increase a temperature of the lithium ion secondary battery is normal of the lithium ion secondary battery. A power supply apparatus characterized by having a current value larger than a maximum current value of a lithium ion secondary battery in operation.   2. The power supply device according to claim 1, further comprising a display device, wherein the control circuit causes a discharge current to flow from the lithium ion secondary battery to the discharge circuit in order to increase the temperature of the lithium ion secondary battery. And displaying on the display device that the operation mode is for increasing the temperature of the lithium ion secondary battery.   4. The power supply device according to claim 3, wherein the display device further displays information related to a scheduled time until the end of the operation mode for increasing the temperature of the lithium ion secondary battery. apparatus.   2. The method of controlling a power supply device according to claim 1, wherein the control circuit needs to be operated in a temperature increase operation mode in order to increase the temperature of the lithium ion secondary battery based on a measurement result of the measurement circuit. A control method for a power supply apparatus, comprising: determining whether or not it is necessary to operate in the temperature increase operation mode, and performing control to pass a current from the lithium ion secondary battery to the discharge circuit.   6. The method of controlling a power supply device according to claim 5, wherein the control circuit obtains a current value or energization time to flow to the discharge circuit from the measurement result of the measurement circuit, and the control circuit controls a current to flow to the discharge circuit. A method for controlling a power supply apparatus, comprising:

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