Battery control apparatus

Abstract

To provide a battery control apparatus capable of accurately detecting an abnormality of a battery sensor with a simple configuration.SOLUTION: A battery control apparatus comprises a sensor for detecting a current of a battery that is charged with a current supplied from a DC converter and supplies power to a predetermined electrical device, and detects an abnormality of the sensor based on a detection value of the sensor. A controller comprises: a voltage instructing unit (Step S5) of issuing an instruction to set an output voltage of the DC converter to the battery to a predetermined voltage based on an open circuit voltage of the battery; a current determining unit (Step S6) of determining whether a current value of the battery exceeds a predetermined current value in a state where the voltage instructing unit is giving the instruction to set to the predetermined voltage; and an abnormality determining unit (Steps S7, S8) of performing an abnormality determination when the current value of the battery exceeds the predetermined current value.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a device for controlling batteries that supply power to various electrical devices such as electrical components, and in particular to a device that is mounted on an electric vehicle and is capable of detecting abnormalities in sensors for batteries that are charged from a high-voltage battery via a DC converter. [Background technology]

[0002] A device for detecting an abnormality in a power supply circuit in an electric vehicle is described in Patent Document 1. To briefly explain its configuration, it is configured to determine that the system is normal when the generator is in a generating state capable of charging the battery and the battery is in a charging state, or when the generator is not generating power and the battery is in a discharging state, and to determine that an abnormality exists in any other state. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-069681 Summary of the Invention [Problem to be solved by the invention]

[0004] Recently, from the perspective of maintaining and improving the global environment, there has been a growing demand for vehicles to maintain and diagnose their original performance. This demand applies not only to so-called engine vehicles that use an engine as a driving force source, but also to so-called electric vehicles that use an electric motor as a driving force source. Since the abnormality detection device described in Patent Document 1 above is not configured to diagnose the power generation state of the generator, it is possible to add a fault detection means to the generator to obtain a signal to be used for on-board self-diagnosis. However, such a configuration requires additional equipment, which is undesirable in terms of simplifying the configuration and the resulting weight and cost reductions.

[0005] Furthermore, as described in Patent Document 1, conventionally, abnormalities in the power supply circuit are detected based on the charging current of the battery when the internal combustion engine is stopped. However, in recent electric vehicles, charging current may flow to the battery even when the generator, such as the internal combustion engine, is stopped. Therefore, in this type of vehicle, it is not possible to detect or determine abnormalities based on the charging and discharging current of the battery when power generation is stopped, and it is also difficult to perform on-board self-diagnosis.

[0006] The present invention has been made in light of the above circumstances, and aims to provide a battery control device that can accurately detect abnormalities in the sensors of a battery that is charged by power supplied via a DC converter, with a simple configuration. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention provides a battery control device that is charged with a current supplied from a DC converter and has a sensor that detects the current of a battery that supplies power to a specified electrical device, and detects an abnormality in the sensor based on the detected value of the sensor, and has a controller that controls the DC converter and determines an abnormality in the sensor, and the controller is characterized by having: a voltage indication unit that issues an instruction to set the output voltage of the DC converter to the battery to a predetermined voltage based on the open circuit voltage of the battery; a current determination unit that determines whether the current value of the battery exceeds the predetermined current value when the voltage indication unit is instructing the predetermined voltage; and an abnormality determination unit that determines an abnormality when the current value of the battery exceeds the predetermined current value. [Effects of the Invention]

[0008] According to the present invention, while instructing the DC converter to set the output voltage to the battery to a predetermined voltage based on the battery's open-circuit voltage, the battery current value is detected and a determination is made as to whether the current value exceeds the predetermined current value. That is, the battery current is intentionally set to the discharge side based on the output voltage of the DC converter. In response to this, the battery current value when the battery current is set to the discharge side is compared with the predetermined current value to determine whether the battery current is on the discharge side or the charge side. Therefore, by setting the predetermined current value to the discharge side, i.e., a small current value, a sensor abnormality can be determined when the detected current value exceeds the predetermined current value. That is, according to the present invention, a sensor abnormality can be detected accurately with a simple configuration by using the detection signal of an existing detector such as a current sensor and simply adding a new output voltage control for the DC converter. Furthermore, a signal based on the detected current value or the abnormality determination can also be used as a signal for on-board self-diagnosis in a vehicle. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram illustrating an example of an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram showing the functional configuration of the controller. [Figure 3] 4 is a flowchart illustrating an example of control executed by a controller. DETAILED DESCRIPTION OF THE INVENTION

[0010] Next, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that the embodiment described below is merely an example of how the present invention can be implemented, and is not intended to limit the present invention.

[0011] FIG. 1 is a block diagram showing an example of an embodiment of the present invention. This example is an electric vehicle equipped with a motor, such as a hybrid vehicle, as a driving force source, and is configured to detect an abnormality in the current of an auxiliary battery 1. The auxiliary battery 1 corresponds to the "battery" in the embodiment of the present invention and is a so-called 12V battery (or low-voltage battery) whose open-circuit voltage (OCV) falls within a predetermined range around 12V. The auxiliary battery 1 is used as a power source to supply power to electrical equipment (electrical components) 2, such as a hydraulic motor, air conditioner, or headlights (not shown). Power for charging the battery 1 is supplied from a main (high-voltage) battery 3 via a DC / DC converter (hereinafter referred to as a DC converter) 4. The DC converter 4 can appropriately set its output voltage; more specifically, it can be set to a voltage lower than the open-circuit voltage of the battery 1. The power for charging the high-voltage battery 3 and the battery 1 can be obtained by driving a generator mounted on the electric vehicle using an engine (not shown) or from an external power source (not shown) such as an appropriate charging station.

[0012] A controller 5 is provided with a function to control the output voltage of the DC converter 4. The controller 5 is mainly composed of a computer equipped with a processing element (CPU), memory elements (RAM, ROM), and various interfaces. The controller 5 is configured to perform calculations according to a pre-prepared program using pre-stored data and data input from the outside, and to output the calculation results as a control signal. The controller 5 is also provided with a battery sensor 6 that detects the current value of the battery 1. The battery current value detected by the battery sensor 6 is input to the controller 5 as data. Examples of data detected and input by sensors (not shown) include the voltage of the battery 1, ON and OFF signals from a ready switch that starts the DC converter 4, and, in the case of a hybrid vehicle (EHV or PEHV), ON and OFF signals from an ignition switch that starts the engine.

[0013] The primary function of the controller 5 in the embodiment described here is to detect or determine an abnormality in the battery sensor 6, and the configuration for executing this function is shown in the block diagram of FIG. 2. The controller 5 includes a condition satisfaction determination unit 5A. The condition satisfaction determination unit 5A is a functional configuration that determines whether the conditions for determining an abnormality in the battery sensor 6 are satisfied. The battery current changes under various conditions. For example, if the battery 1 is deteriorated or at an extremely low temperature, the battery 1 will not function normally and the battery current will not be accurately detected. Therefore, the condition satisfaction determination unit 5A determines whether the battery 1 is normal.

[0014] The presence or absence of an abnormality in the battery sensor 6 is determined by whether the battery 1 is in a discharging state and the current value is on the discharging side. For this purpose, a voltage indicator 5B is provided that instructs the DC converter 4, to which the battery 1 is connected, to set its output voltage to a predetermined voltage determined based on the open-circuit voltage of the battery 1. The predetermined voltage to be instructed is essentially a voltage equal to or lower than the open-circuit voltage of the battery 1, and since the open-circuit voltage varies somewhat depending on the battery 1, it is preferable to instruct a voltage lower than the minimum open-circuit voltage of a normal battery 1, which has a certain range.

[0015] The controller 5 is provided with a current determination unit 5C. This current determination unit 5C has a functional configuration that determines whether the current value detected by the battery sensor 6 exceeds a predetermined current value. More specifically, the predetermined current value may be "0 A." In short, it is sufficient if the current of the battery 1 can be determined to be a discharge current or a charge current.

[0016] The controller 5 is provided with an abnormality determination unit 5D that determines whether an abnormality exists based on the determination result of the current determination unit 5C. As described above, when the output voltage of the DC converter 4 is set to be equal to or lower than the open circuit voltage of the battery 1, if there is no abnormality, the battery current will be on the discharge side. Conversely, if there is any abnormality, the battery current will be on the charge side. In other words, if the current determination unit 5C determines that the battery current is on the charge side, the abnormality determination unit 5D will determine that there is an "abnormality." The determination result is output to, for example, the on-board self-diagnosis unit OBD.

[0017] FIG. 3 is a flowchart illustrating the control of the controller 5 for determining abnormalities in battery current. The example shown here begins with the ignition switch in the ON (IG-ON) state. First, a determination is made as to whether the aforementioned conditions are met. One example of such conditions is that the battery 1 is operating normally. The fulfillment of the conditions can be determined based on the battery voltage. Specifically, a determination is made as to whether the battery voltage is equal to or lower than a predetermined voltage αV determined based on the open-circuit voltage OCV (step S1). If the battery 1 is degraded or malfunctions due to a voltage drop caused by extremely low temperatures, the battery voltage may fall below a lower limit of the open-circuit voltage, which has a predetermined range. Therefore, a voltage approximately equal to or slightly lower than the lower limit is predefined as the predetermined voltage αV (e.g., 11 V). In step S1, the detected battery voltage is compared with the predetermined voltage αV. If the determination result in step S1 is "Yes," this indicates that the battery 1 is not operating normally. Therefore, the routine of FIG. 3 is temporarily terminated without any special control.

[0018] Conversely, if the determination result in step S1 is "No," it is determined whether the ready switch is ON (Ready-ON) (step S2). The ready switch is a switch provided in an electric vehicle that turns on the driving electrical system, including the DC converter 4. Therefore, in the example shown in FIG. 3, step S2 determines whether the DC converter 4 is turned ON. If the determination result in step S2 is "No," the process returns to step S1 and waits for the DC converter 4 to be turned "Ready-ON." Conversely, if the determination result in step S2 is "Yes," it is determined whether the ignition switch that turns the engine power ON / OFF has been turned OFF (IG-OFF) (step S3). If the determination result in step S3 is "No," it waits for the ignition switch to be turned ON.

[0019] Conversely, if the determination result in step S3 is "Yes," it is determined whether the average battery voltage while the ready switch is ON is higher than a predetermined voltage βV determined based on the open-circuit voltage OCV (step S4). When the ready switch is ON, the DC converter 4 is ON and the battery 1 is charging. Therefore, if the battery 1 is operating normally, the average battery voltage will be higher than the open-circuit voltage. Conversely, if the battery 1 is not operating normally, the average voltage may fall below the upper limit of the open-circuit voltage, which has a predetermined range. Therefore, a voltage approximately equal to or slightly higher than the upper limit is preset as the predetermined voltage βV (e.g., 13 V). In step S4, the detected average battery voltage is compared with the predetermined voltage βV. If the determination result in step S4 is "Yes," the battery 1 is not operating normally. Therefore, the routine in FIG. 3 is temporarily terminated without any special control.

[0020] On the other hand, if the result of the determination in step S4 is "NO," it means that the battery 1 is operating normally, and therefore a state in which the battery current is discharging is created and the battery current is evaluated. That is, an instruction is given to set the output voltage of the DC converter 4 to a predetermined voltage that does not charge the battery 1 (step S5). The predetermined voltage can be determined based on the open-circuit voltage of the battery 1, and may be, for example, a voltage that is approximately the lower limit of the original open-circuit voltage within a predetermined range or a voltage slightly lower than the lower limit. In the example shown in FIG. 3, the predetermined voltage αV (e.g., 11 V) used in the determination in step S1 is set.

[0021] In this state, it is determined whether the detected battery current is on the discharging side (step S6). That is, it is determined whether the battery current value is greater than a predetermined current value I0. The battery sensor 6 detects the current value when the battery 1 is being charged as a positive current value and the current value when the battery 1 is being discharged as a negative current value, so the predetermined current value I0 that serves as the basis for determination is set to "0 A" in the example shown in FIG. 3.

[0022] Therefore, if the determination result in step S6 is "YES," the battery current is a charging current even though the output voltage of the DC converter 4 is instructed to put the battery 1 into a discharging state, and therefore the battery current value is determined to be "abnormal" (step S7). In this case, an abnormality has occurred in the battery sensor 6. Conversely, if the determination result in step S6 is "NO," the battery current is a discharging current even though the output voltage of the DC converter 4 is instructed to put the battery 1 into a discharging state, and therefore the battery current value is determined to be "normal" (step S8). In this case, the battery sensor 6 is normal. The determinations in steps S7 and S8 are made by the abnormality determination unit 5D described above, and then the routine shown in FIG. 3 is temporarily terminated.

[0023] As described above, according to the embodiment of the present invention, abnormalities in the battery current are determined using the existing battery sensor 6 and controller 5, so abnormalities in the battery current can be determined with a simple configuration without adding any new equipment. Furthermore, the determination result can be output as a signal to the controller 5, so that it can be used for on-board self-diagnosis to improve the reliability of the vehicle.

[0024] The present invention is not limited to the above-described embodiment, and can be implemented by making appropriate modifications within the scope of the object or gist of the present invention, and such modified aspects also fall within the scope of the present invention. For example, the determination of whether the battery current is charging or discharging may be made by determining whether the current is equal to or less than the reference current value I0, instead of determining whether the current is greater than the reference current value I0. [Explanation of symbols]

[0025] 1 Auxiliary battery (battery) 2 Electrical equipment 3 High-voltage battery 4 DC converter 5 Controller 5A Condition establishment determination section 5B Voltage indicator 5C current judgment section 5D Abnormality judgment section 6 Battery Sensor

Claims

[Claim 1] A battery control device that is charged with a current supplied from a DC converter and has a sensor that detects a current of a battery that supplies power to a predetermined electrical device, and detects an abnormality of the sensor based on a detected value of the sensor, a controller that controls the DC converter and determines whether the sensor is abnormal; The controller a voltage instruction unit that instructs the DC converter to set an output voltage for the battery to a predetermined voltage based on an open circuit voltage of the battery; a current determination unit that determines whether a current value of the battery exceeds a predetermined current value while the voltage indication unit is indicating the predetermined voltage; an abnormality determination unit that determines an abnormality when the current value of the battery exceeds the predetermined current value; A battery control device characterized by:

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