Power system

Abstract

To provide a power system in which a battery can be used safely and continuously without separating the battery from the system immediately, even when information concerning the battery cannot be directly acquired from the battery due to communication abnormality or the like.SOLUTION: A power system has a battery device outputting information concerning a battery, a power generation device supplying power to the battery device, and a control device controlling power generation voltage of the power generation device based on information acquired from the battery device. When the information cannot be acquired from the battery device, the control device controls the power generation voltage of the power generation device based on output voltage that is voltage of an output end side of the power generation device.SELECTED DRAWING: Figure 1

Description

Technical Field

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[0001] The present disclosure relates to a power system for controlling a battery.

Background Art

[0002] Patent Document 1 discloses an electric vehicle that ensures the safety of the vehicle without impairing the vehicle's driving opportunity. In the electric vehicle described in this Patent Document 1, it is described that when a communication abnormality detection unit detects a communication abnormality related to a charging unit during driving, safety control for restricting the driving control of the vehicle is not performed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the detected communication abnormality is related to the battery, it is conceivable to electrically disconnect the battery related to the detected communication abnormality from the system for safety. However, if this battery is a battery necessary for the implementation of safety control, disconnecting it from the system will cause a problem that the necessary control cannot be executed in a situation where safety control is required.

[0005] The present disclosure has been made in view of the above problems, and an object thereof is to provide a power system that can safely continue to use a battery without immediately disconnecting the battery from the system even when information related to the battery cannot be directly obtained from the battery due to a communication abnormality or the like.

Means for Solving the Problems

[0007] According to the power system described in this disclosure, even if information about the battery cannot be obtained directly from the battery due to communication failures or other reasons, it is possible to safely continue using the battery without immediately disconnecting it from the system. [Brief explanation of the drawing]

[0008] [Figure 1] Schematic diagram of a power system according to one embodiment of this disclosure. [Figure 2A] Flowchart of voltage control processing performed by a power system control device [Figure 2B] Flowchart of voltage control processing performed by a power system control device [Figure 3] Diagram illustrating the change in output voltage of a power generator during voltage control processing (First Command) [Figure 4] Diagram illustrating the change in output voltage of a power generator during voltage control processing (from the second command to the third command). [Figure 5] Diagram illustrating the change in output voltage of a power generator during voltage control processing (from the second command to the fourth command). [Figure 6] Diagram illustrating the change in output voltage of a power generator during voltage control processing (from the 4th command to the 2nd command). [Modes for carrying out the invention]

[0009] The power system of this disclosure controls the output voltage of the DC-DC converter based on the actual output voltage of the DC-DC converter if the electronic control unit (ECU) that controls the DC-DC converter is unable to obtain feedback information on the output voltage requested from the battery side to the DC-DC converter, so that the battery can be safely used continuously. The embodiments of this disclosure will be described in detail below with reference to the drawings.

[0010] <Embodiment> [composition] Figure 1 is a schematic diagram of the configuration of a power system 100 according to one embodiment of the present disclosure. The power system 100 illustrated in Figure 1 comprises a battery device 110, a power generator 120, and a control device 130. In Figure 1, power lines through which power is supplied are shown as solid lines, and signal lines through which control instructions and data are communicated are shown as dashed lines. This power system 100 can be mounted on a vehicle or the like.

[0011] The battery device 110 is a rechargeable secondary battery, such as a lithium-ion battery. This battery device 110 can store the power generated by the power generator 120 and supply the power it has stored to the load 150. The battery device 110 includes a battery cell 111 and a battery ECU 112 that monitors the state of the battery cell 111. Specifically, the battery ECU 112 acquires information about the battery cell 111 and provides this acquired information to the control device 130. The information about the battery cell 111 is physical quantities such as voltage and current that indicate the state of the battery cell 111. The battery ECU 112 acquires these physical quantities via detection devices (not shown), such as sensors. The battery ECU 112 also calculates the value of the generated voltage to request from the power generator 120 as information necessary to protect the battery cell 111. This information is transmitted from the battery ECU 112 to the control device 130. An example of this battery device 110 is an auxiliary battery mounted on a vehicle.

[0012] The power generator 120 is a device for supplying power to the battery device 110 and the load 150. Typically, this power generator 120 is a DC-DC converter 121 (power converter) that converts the voltage of the input power to a predetermined voltage and outputs it. Power generated by a generator (not shown), such as an alternator, is input to the input terminal of the DC-DC converter 121. This DC-DC converter 121 can be a step-down DC-DC converter that, for example, steps down the voltage on the input terminal side and outputs it to the output terminal side to which the battery device 110 and the load 150 are connected. Note that the configuration of the power generator 120 may include both the DC-DC converter 121 and a generator.

[0013] The control device 130 is a device for controlling the output of the generator 120 for the safe use of the battery device 110. The control device 130 acquires information about the battery device 110 (hereinafter referred to as "battery information") from the battery device 110 (its battery ECU 112) and controls the generated voltage of the generator 120 based on this battery information. The battery information includes information about the battery cells 111 and information about the required generated voltage for the generator 120. In the case of a vehicle, for example, the control device 130 acquires battery information from the battery device 110 through communication using a network such as CAN or LIN. The control device 130 can also acquire the output voltage, which is the voltage at the output terminal side of the DCDC converter 121 that constitutes the generator 120, and control the generated voltage of the generator 120 based on this output voltage. The control device 130 can acquire the output voltage of the DCDC converter 121 via a detection device (not shown), such as a voltage sensor. Details of the control of the generator 120 by this control device 130 will be described later.

[0014] Part or all of this control device 130 can typically be constituted by an ECU (e.g., HV-ECU, battery master ECU) including a processor such as a microcomputer, a memory, and an input / output interface. By the processor reading and executing a program stored in the memory, part or all of the functions performed by the above-described control device 130 can be realized.

[0015] The load 150 is a device, apparatus, system, etc. that operates by consuming the electric power output from the power generation device 120 and / or the electric power stored in the battery device 110. When the battery device 110 is an auxiliary battery mounted on a vehicle, the load 150 is, for example, an auxiliary device (such as a lighting device, an air conditioning device) not related to the running of the vehicle.

[0016] [Control] Next, referring further to FIGS. 2A, 2B, 3, 4, 5, and 6, the control performed by the power system 100 according to the present embodiment will be described. FIGS. 2A and 2B are flowcharts for explaining the procedure of the voltage control process of the power generation device 120 performed by the control device 130 of the power system 100. The process of FIG. 2A and the process of FIG. 2B are connected by connectors X and Y. FIGS. 3, 4, 5, and 6 are diagrams for explaining the change in the output voltage of the power generation device 120 at each processing stage of the voltage control process, respectively.

[0017] The voltage control process illustrated in FIGS. 2A and 2B is started when the control device 130 cannot obtain battery information from the battery device 110 due to a communication abnormality or the like, or when the reliability of the battery information obtained from the battery device 110 cannot be guaranteed due to an abnormality of a detection device or the like. In the following description, the control target of the power generation device 120 is described as the DCDC converter 121.

[0018] (Step S201) The control device 130 requests the DCDC converter 121 so that the output voltage (the voltage on the output terminal side) of the DCDC converter (DDC) 121 becomes the first voltage. This request and each request described later are typically made by instructing (controlling) the value of the ON / OFF duty ratio of the switching element constituting the DCDC converter 121. The instruction (control) to request the output of this first voltage from the DCDC converter 121 is called the "first command". This first voltage is a target voltage estimated to enable the safe use of the battery device 110 and is appropriately set based on the performance and characteristics of the battery device 110, etc.

[0019] When the control device 130 gives the first command to the DCDC converter 121, the process proceeds to step S202.

[0020] (Step S202) After giving the first command to the DCDC converter 121, the control device 130 determines whether a state where the output voltage of the DCDC converter 121 does not decrease to the first voltage and becomes a high value exceeding a predetermined value from the first voltage (a state satisfying the condition of "DDC output voltage > first voltage + predetermined value") continues for the first time. This determination is made to confirm that an abnormality has occurred in the battery device 110 where the output voltage does not decrease with only the first command. The predetermined value is an offset value from the first voltage for defining the upper limit voltage allowed to ensure the safety of the battery device 110. The first time is a time for confirming that the situation where the output voltage of the DCDC converter 121 exceeds the upper limit voltage (= first voltage + predetermined value) is not temporary but continuous. This predetermined value and the first time are appropriately set from the viewpoint of ensuring the safety of the battery device 110 based on the performance and characteristics of the battery device 110, etc.

[0021] If the control device 130 determines that the output voltage of the DC-DC converter (DDC) 121 has been exceeding a predetermined value above the first voltage for a continuous first time (DDC output voltage > first voltage + predetermined value) (step S202, yes), it determines that it is not appropriate to continue the first command and proceeds to step S203.

[0022] On the other hand, if the control device 130 determines that the output voltage of the DC-DC converter (DDC) 121 has not exceeded a predetermined value above the first voltage for the first time (DDC output voltage ≤ first voltage + predetermined value) (step S202, no), it determines that it is appropriate to continue the first command and proceeds to step S201. Figure 3 shows the change in the output voltage of the DC-DC converter 121 in this case. As shown in Figure 3, if the output voltage of the DC-DC converter 121 (dotted line) does not exceed the first voltage (solid line) by a predetermined value (double arrow), or if it exceeds the predetermined value but does not continue for the first time, the control of the output voltage of the DC-DC converter 121 by the first command continues.

[0023] (Step S203) The control device 130 requests the DC-DC converter (DDC) 121 to gradually decrease its output voltage from the current voltage until it reaches a second voltage. This instruction (control) that requests the DC-DC converter 121 to output a second voltage while gradually decreasing the current voltage is called a "second command". This second voltage is a voltage lower than the first voltage and is the minimum lower limit voltage required to ensure the safety of the battery device 110 and the operation of the load 150. It is set appropriately based on the performance and characteristics of the battery device 110 and the specifications of the load 150. The voltage can be changed from the current voltage to the second voltage according to a predetermined linear or quadratic curve.

[0024] When the control device 130 issues a second command to the DC-DC converter 121, the process proceeds to step S204.

[0025] (Step S204) After issuing a second command to the DC-DC converter (DDC) 121, the control device 130 determines whether the control value (control voltage) of the second command has reached the second voltage. This determination is made to confirm that even with control by the second command, the output voltage of the DC-DC converter 121 will not stabilize below the first voltage.

[0026] If the control device 130 determines that the control value (control voltage) of the second command has reached the second voltage (step S204, yes), it determines that it is appropriate to proceed to the final stage of control, and the process proceeds to step S205.

[0027] On the other hand, if the control device 130 determines that the control value (control voltage) of the second command has not yet reached the second voltage (step S204, no), the process proceeds to step S206 in order to further determine whether or not to advance the second command to the next stage.

[0028] (Step S205) The control device 130 requests the DC-DC converter 121 (DDC) to output a second voltage. This instruction (control) to the DC-DC converter 121 to output this second voltage is called the "third command." This third command is the final control that can be taken to minimize the impact of the battery device 110 on other devices. Figure 4 shows the change in the output voltage of the DC-DC converter 121 in this case. As shown in Figure 4, unless the output voltage of the DC-DC converter 121 (dotted line) remains below the first voltage (top of solid line) for a certain period of time, the control of the output voltage of the DC-DC converter 121 is fixed to the third command from the point when the control value of the second command reaches the second voltage (bottom of solid line).

[0029] When the control device 130 issues a third command to the DC-DC converter 121, the voltage control process of the power generator 120 is terminated.

[0030] (Step S206) After issuing a second command to the DC-DC converter (DDC) 121, the control device 130 determines whether the output voltage of the DC-DC converter 121 has remained below the first voltage (the condition "DDC output voltage < first voltage") for a second time. This determination is made to confirm that the output voltage of the DC-DC converter 121 has decreased to the desired level by issuing the second command. The second time is to confirm that the situation in which the output voltage of the DC-DC converter 121 is below the first voltage is not temporary but continuous. Therefore, this second time is set appropriately from the standpoint of ensuring the safety of the battery device 110, based on the performance and characteristics of the battery device 110.

[0031] If the control device 130 determines that the output voltage of the DC-DC converter (DDC) 121 has remained below the first voltage for a second time (DDC output voltage < first voltage) (step S206, yes), it is deemed appropriate to proceed to the next stage of the second command, and the process proceeds to step S207.

[0032] On the other hand, if the control device 130 determines that the output voltage of the DC-DC converter (DDC) 121 will not fall below the first voltage for the second time (DDC output voltage ≥ first voltage) (step S206, no), it determines that it is appropriate to continue with the second command and proceeds to step S203.

[0033] (Step S207) The control device 130 requests the DC-DC converter (DDC) 121 to output a third voltage. This instruction (control) to the DC-DC converter 121 to output this third voltage is called the "fourth command". This fourth command is a control to maintain the voltage state at the point when it is determined that the output voltage of the DC-DC converter 121 has decreased to the desired level by performing the second command. Therefore, this third voltage becomes the control value (control voltage) of the second command at the point when it is determined in step S206 that the output voltage of the DC-DC converter 121 has been below the first voltage for two consecutive hours (DDC output voltage < first voltage). Figure 5 shows the change in the output voltage of the DC-DC converter 121 in this case. As shown in Figure 5, if the output voltage of the DC-DC converter 121 (dotted line) remains below the first voltage for two consecutive hours, the gradual decrease of the control voltage is stopped, and the output voltage of the DC-DC converter 121 is controlled by the fourth command, which fixes the control voltage to the third voltage at the time of stopping (bottom of the solid line).

[0034] When the control device 130 issues a fourth command to the DC-DC converter 121, the process proceeds to step S208.

[0035] (Step S208) After issuing the fourth command to the DC-DC converter (DDC) 121, the control device 130 determines whether the output voltage of the DC-DC converter 121 has remained at or above the first voltage (the condition "DDC output voltage ≥ first voltage") for three hours. This determination is made to confirm whether the output voltage of the DC-DC converter 121 has returned to or above the first voltage after switching from the second to the fourth command. The third hour is a period to confirm that the situation in which the output voltage of the DC-DC converter 121 has returned to or above the first voltage is not temporary but is ongoing. Therefore, this third hour is set appropriately from the standpoint of ensuring the safety of the battery device 110, based on the performance and characteristics of the battery device 110.

[0036] If the control device 130 determines that the output voltage of the DC-DC converter (DDC) 121 has been at or above the first voltage for three consecutive hours (DDC output voltage ≥ first voltage) (step S208, yes), it determines that it is appropriate to return the fourth command to the second command, and the process proceeds to step S203. Figure 6 shows the change in the output voltage of the DC-DC converter 121 in this case. As shown in Figure 6, if the output voltage of the DC-DC converter 121 (dotted line) has been at or above the first voltage for three consecutive hours in the fourth command, the control of the output voltage of the DC-DC converter 121 is performed again by the second command, which releases the fixation of the third voltage of the control voltage and gradually reduces the control value (control voltage) to the second voltage.

[0037] On the other hand, if the control device 130 determines that the output voltage of the DC-DC converter (DDC) 121 will not exceed the first voltage for the third time (DDC output voltage < first voltage) (step S208, no), it determines that it is appropriate to continue with the fourth command and proceeds to step S207.

[0038] The voltage control process of the power generator 120 described above ends when the output voltage of the DC-DC converter 121 is controlled by the third command (step S205), or when the abnormality in the battery device 110 (communication abnormality, detection device abnormality, etc.) is resolved.

[0039] <Effects and Actions> As described above, according to the power system 100 according to one embodiment of the present disclosure, if the control device 130 cannot directly obtain a request for the output voltage of the DC-DC converter 121 constituting the power generator 120 from the battery device 110, it controls the output voltage of the DC-DC converter 121 based on the actual output voltage of the DC-DC converter 121 so that the battery device 110 can be used safely and continuously.

[0040] This process makes it possible to safely continue using the battery device 110 without immediately disconnecting it from the power system 100, even if battery information cannot be directly obtained from the battery device 110 due to communication errors or other reasons.

[0041] Although one embodiment of the present disclosure has been described above, the present disclosure can be understood not only as a power system, but also as a method executed by a power system equipped with a processor, memory, etc., a program for executing this method, a computer-readable non-temporary storage medium storing the program, and a vehicle equipped with the power system. [Industrial applicability]

[0042] The power system described herein can be used, for example, when controlling the output of a vehicle's battery with a DC-DC converter. [Explanation of Symbols]

[0043] 100 Power Systems 110 Battery device 111 battery cells 112 Battery ECU 120 Power generation equipment 121 DC-DC Converter 130 Control device 150 load

Claims

1. It is a power system, A battery device that outputs information about the battery, A DC-DC converter that outputs the input power to the battery device, The system includes a control device that controls the output voltage of the DC-DC converter based on the information obtained from the battery device, The control device is If the information cannot be obtained from the battery device, a first command is given to the DC-DC converter to control the output voltage of the DC-DC converter to a first voltage. After the first command is given to the DCDC converter, if the output voltage of the DCDC converter remains above a predetermined value for a first time, a second command is given to the DCDC converter to gradually reduce the control voltage to a second voltage lower than the first voltage. Power system.

2. After the control device has given the second command to the DCDC converter, if the control voltage of the second command reaches the second voltage, it gives the DCDC converter a third command to control the output voltage of the DCDC converter to the second voltage. The power system according to claim 1.

3. After the control device has given the second command to the DCDC converter, if the output voltage of the DCDC converter remains below the first voltage for a second time, it gives the DCDC converter a fourth command to control the output voltage of the DCDC converter to the third voltage, which is the command value at the time the second time has passed. The power system according to claim 1.

4. After the control device has given the fourth command to the DC-DC converter, if the output voltage of the DC-DC converter remains at or above the first voltage for a third time, it gives the second command to the DC-DC converter. The power system according to claim 3.

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