Voltage sensor with discharge resistance circuit monitoring

Abstract

To provide a passive discharge circuit capable of performing more secure discharge by detecting an abnormality in the passive discharge circuit of a smoothing capacitor.SOLUTION: A discharge system for vehicles comprises a battery, which is loaded on a vehicle including a driving motor, and an inverter by which power supplied from the battery is controlled and outputted to the driving motor. The inverter includes a capacitor, a passive discharge circuit connected in parallel to a smoothing capacitor, a voltage sensor, and a controller. The passive discharge circuit is a circuit consisting of a plurality of resistors and further has one or more intermediate contacts. The voltage sensor acquires a voltage between the intermediate contact and a negative pole of the passive discharge circuit. When a voltage supplied by the battery and the voltage acquired by the voltage sensor exceed a normal range in a predetermined map, the controller detects an abnormality of the passive discharge circuit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The disclosed technology relates to a discharge circuit for a smoothing capacitor in an on-board inverter. [Background technology]

[0002] In vehicles that run on an electrically powered motor, an inverter controls the voltage supplied by the battery to an appropriate voltage and supplies power to the motor. Inverters generally have a large-capacity smoothing capacitor to smooth the voltage. This smoothing capacitor stores charge when the vehicle is on (driving). When the vehicle is off, the smoothing capacitor is electrically disconnected. For vehicle operation, the smoothing capacitor must be discharged after the vehicle is turned off. A combination of active and passive discharge is widely used to remove the charge from the smoothing capacitor when the vehicle is turned off. Active discharge refers to a function that rapidly discharges the battery by using a function such as the motor after the vehicle is turned off. Passive discharge, on the other hand, refers to a function that continuously discharges the battery using a resistive element without using such a specific function. Passive discharge is known to be provided in vehicles as a backup when active discharge does not function sufficiently.

[0003] Patent Document 1 discloses a technique for improving the reliability of discharge in the event of an abnormality in an active discharge circuit by combining active discharge and passive discharge. However, Patent Document 1 does not disclose any improvements to passive discharge circuits, particularly improvements to address abnormal states that may occur in passive discharge circuits. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-176432 Summary of the Invention [Problem to be solved by the invention]

[0005] The passive discharge circuit is a backup in the event of an abnormality in the active discharge circuit, but providing some kind of improvement to the passive discharge in an abnormal state will further increase the reliability of the discharge of the smoothing capacitor. An object of the present invention is to provide a passive discharge circuit that can detect an abnormality in a passive discharge circuit of a smoothing capacitor and perform more reliable discharge. [Means for solving the problem]

[0006] The disclosed technology relates to a vehicle discharge system for a smoothing capacitor in an inverter mounted on a vehicle. The vehicle discharge system includes a battery mounted on a vehicle having a drive motor, and an inverter that controls the power supplied from the battery and outputs it to the drive motor. The inverter includes a smoothing capacitor, a passive discharge circuit connected in parallel to the smoothing capacitor, a voltage sensor, and a controller. The passive discharge circuit is a circuit composed of a plurality of resistors and further has one or more intermediate junctions. The voltage sensor acquires the voltage between the intermediate junction and the negative pole of the passive discharge circuit. The controller detects an abnormality in the passive discharge circuit when the voltage supplied by the battery and the voltage acquired by the voltage sensor exceed the normal range in a predetermined map.

[0007] With this configuration, it is possible to provide a passive discharge circuit that can detect an abnormality in the passive discharge circuit of the smoothing capacitor and perform more reliable discharge.

[0008] The disclosed technology further includes a voltage bypass circuit that is installed between the positive pole of the passive discharge circuit and the voltage sensor and controls the voltage detected by the voltage sensor to be the voltage at the time of abnormality detection, and the voltage bypass circuit is normally open and is controlled to be closed when the controller detects an abnormality, and when the controller detects an abnormality in the passive discharge circuit, the controller controls the circuit of the voltage bypass circuit for circuit abnormality to be closed.

[0009] With this configuration, even if an abnormality occurs in the passive discharge circuit, the voltmeter provided in parallel with the passive discharge circuit can read the voltage of the smoothing capacitor.

[0010] The disclosed technology further includes a configuration in which the voltage bypass circuit divides the positive pole voltage and provides it to the voltage sensor, and the divided voltage provided is set to be a voltage that exceeds the first map.

[0011] With this configuration, even if an abnormality occurs in the passive discharge circuit, the voltmeter provided in parallel with the passive discharge circuit can more reliably read the voltage of the smoothing capacitor.

[0012] Furthermore, in the disclosed technology, if the voltage bypass circuit is closed when the controller detects an abnormality, the circuit will remain closed even when the vehicle power is turned off and then turned on again.

[0013] This configuration can reduce false detections that occur when the vehicle is turned off after an abnormality is detected and then turned on again. [Effects of the Invention]

[0014] According to a vehicle power supply control system to which the disclosed technology is applied, it is possible to provide a passive discharge circuit that can detect an abnormality in the passive discharge circuit of a smoothing capacitor and perform more reliable discharge. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram showing the structure of an automobile to which the disclosed technology is applied. [Figure 2] 1 is a schematic diagram showing an electric circuit of a main electric device of a high-voltage system according to the first embodiment. FIG. [Figure 3] FIG. 1 is a diagram illustrating a configuration of a communication network related to voltage values. [Figure 4] 10 is a flowchart for determining an abnormality in a passive discharge circuit. [Figure 5] 10 is a graph showing a voltage conversion map for a voltage value V1 and a voltage value V2 when the circuit is normal. [Figure 6] FIG. 10 is a schematic diagram showing an electric circuit of a main electric device of a high-voltage system according to the second embodiment. [Figure 7] 10 is a flowchart illustrating the operation of the voltage bypass circuit. [Figure 8] 10 is a graph showing a voltage conversion map for a voltage value V1 and a voltage value V2 when the circuit is normal after activation of the voltage bypass circuit. DETAILED DESCRIPTION OF THE INVENTION

[0016] <Embodiment 1> A vehicle in embodiment 1 will be described. FIG. 1 shows an automobile 1 (an example of a vehicle) to which the disclosed technology is applied. The automobile 1 is an electric vehicle that can run using electric power. The automobile 1 is equipped with a drive motor 2 as its drive source, which drives the front wheels and / or rear wheels. This allows the automobile 1 to run. In addition to the drive motor 2, the automobile 1 is equipped with a drive battery 10, an inverter 20, and other high-voltage electrical devices. The inverter 20 is a device that controls the operation of the drive motor 2, and controls the DC power supplied from the battery 10 via a high-voltage circuit 3 and outputs it to the drive motor 2.

[0017] The inverter 20 in the first embodiment will now be described. Fig. 2 shows the electrical circuit of the main electrical devices of the high-voltage system. The inverter 20 has a predetermined switching circuit 21 composed of a plurality of switching elements, a smoothing capacitor 22, an active discharge circuit 23, a passive discharge circuit 24, and a voltmeter 25. The inverter 20 is provided with a positive-side main wiring 3a connected to the positive side of the high-voltage circuit 3, and a negative-side main wiring 3b connected to the negative side of the high-voltage circuit 3.

[0018] The smoothing capacitor 22 smoothes the voltage input to the inverter 20. That is, when the main power supply of the automobile 1 is turned on, the voltage of the battery 10 is applied to the smoothing capacitor 22. As a result, a charge corresponding to that voltage is stored in the smoothing capacitor 22. The smoothing capacitor 22 discharges when the voltage drops, and stores when the voltage rises. Therefore, the voltage between the positive main wiring 3a and the negative main wiring 3b is smoothed by the smoothing capacitor 22.

[0019] When the main power supply is cut off, the power supply from the battery 10 to the inverter 20 is cut off. However, a charge remains in the smoothing capacitor 22, and this residual charge causes a high voltage to be maintained between the positive main wiring 3a and the negative main wiring 3b. Therefore, the charge in the smoothing capacitor 22 must be discharged quickly. Therefore, the automobile 1 is provided with an active discharge circuit 23 in the inverter 20 as a means for forcibly discharging the smoothing capacitor 22.

[0020] The active discharge circuit 23 may employ a mechanism that uses the drive motor 2 to consume the residual charge in the smoothing capacitor 22 as heat, for example. However, in the case of the automobile 1, there is a risk that part of the drive motor 2 may be damaged in a collision or the like, causing the mechanism to stop functioning. Therefore, the automobile 1 is provided with a passive discharge circuit 24 as a backup in such cases.

[0021] The passive discharge circuit 24 continuously discharges the charge in the smoothing capacitor 22 regardless of the operating status of the active discharge circuit 23. The passive discharge circuit 24 is a circuit electrically connected between the positive main wiring 3a and the negative main wiring 3b. The passive discharge circuit 24 is configured, for example, as a circuit in which multiple resistors are connected like a ladder. This circuit creates one or more contact points (referred to as intermediate contact points 24a) between the positive main wiring 3a and the negative main wiring 3b.

[0022] The voltmeter 25 is electrically connected between the intermediate contact 24a and the negative main wiring 3b and has the function of acquiring the voltage value V1 between them. To operate the voltmeter 25, a capacitor and a resistor must be electrically arranged around the voltmeter 25, but this description will be omitted. Providing the voltmeter 25 and the discharge resistor in a single package has the advantage of simplifying the assembly work to the main wiring 3, etc. during vehicle assembly. Furthermore, as will be described later, the voltage value acquired by the voltmeter 25 can be used to detect an abnormality in the passive discharge circuit 24.

[0023] The automobile 1 further has a determination unit 30 (controller), a battery voltmeter 11 that measures the voltage of the battery 10, and a communication network NW. The determination unit 30 may be implemented by a processor that loads and executes a program from a memory that stores the program. The processor may also be included in an on-board ECU (Electric Control Unit) and installed in the automobile 1. The determination unit 30 has a data acquisition unit 31, a determination processing unit 32, and a determination result notification unit 33. Each of these will be described below.

[0024] 3 shows a configuration diagram of a communication network related to voltage values. Data acquisition unit 31 has the function of acquiring voltage value V1 and voltage value V2 of battery 10 from voltmeter 25. Determination unit 30, voltmeter 25, and battery voltmeter 11, which measures the voltage of battery 10, are connected to a communication network NW that enables data communication. Through this connection, voltmeter 25 transmits data indicating voltage value V1 to the communication network NW, and data acquisition unit 31 receives the data. Similarly, battery voltmeter 11 transmits data indicating voltage value V2 to the communication network NW, and data acquisition unit 31 receives the data.

[0025] Based on the voltage value V1 and the voltage value V2, it is determined whether there is an abnormality in the passive discharge circuit 24. Fig. 4 shows a flowchart for determining whether there is an abnormality in the passive discharge circuit 24. The data acquisition unit 31 acquires the voltage values ​​V1 and V2 (step S10).

[0026] Next, the determination processing unit 32 maps the voltage values ​​V1 and V2 to a normal-circuit voltage conversion map M1 (described later) (step S11). FIG. 5 shows a graph illustrating the normal-circuit voltage conversion map M1 for the voltage values ​​V1 and V2. When the passive discharge circuit 24 is normal, the relationship between the voltage value V1 acquired by the voltmeter 25 and the voltage value V2 of the battery 10 is as shown by the solid line in the normal-circuit voltage conversion map M1. The voltage values ​​V1 and V2 have this relationship because the passive discharge circuit 24 is configured with a combination of multiple resistors. When the passive discharge circuit 24 becomes abnormal, the voltage values ​​V1 and V2 deviate from the normal-circuit voltage conversion map. An abnormality in the passive discharge circuit 24 is expected, for example, when some of the resistors constituting the circuit become open or short-circuited. This changes the overall resistance value of the passive discharge circuit 24 compared to when it is normal, and this also affects the voltage at the intermediate junction 24a. The voltage value V1 at this time may be higher or lower than the V1 derived from the voltage V2 based on the voltage conversion map for normal circuits. Therefore, normality determination limits (upper and lower limits) are set in the voltage conversion map for normal circuits M1, and an abnormality in the passive discharge circuit 24 is determined when the limits are exceeded.

[0027] The normal judgment limits (upper and lower limits) can be set, for example, by assuming that some of the resistor elements among the multiple resistors that make up the passive discharge circuit 24 will be in an open state or a short-circuit state, and then generating this state through circuit simulation, and setting the limits appropriately based on the range of fluctuation of the voltage value V1 that occurs.

[0028] Next, the determination processor 32 determines whether the voltage values ​​V1 and V2 can be mapped into the normal range of the normal-circuit voltage conversion map M1 (step S12). If the voltage values ​​V1 and V2 are mapped into the range sandwiched between the normal judgment limits (upper and lower limits) shown by the dotted lines on the graph, it is determined that they are mapped into the normal range of the normal-circuit voltage conversion map M1 (YES in step S12). Conversely, if the voltage values ​​V1 and V2 are not mapped into the range sandwiched between the normal judgment limits (upper and lower limits) shown by the dotted lines on the graph, it is determined that they are not mapped into the normal range of the normal-circuit voltage conversion map M1 (NO in step S12).

[0029] Next, if step S12 is NO, the determination processing unit 32 determines that the passive discharge circuit 24 is abnormal.

[0030] The determination result notification unit 33 notifies the user of the determination result based on the result of the determination made by the determination processing unit 32. Specific examples of notification include turning on a warning light on the meter of the automobile 1 when it is determined that the passive discharge circuit 24 is abnormal, or displaying a warning message on the screen of the head unit. In either case, it is expected that a message will be displayed to prompt the user of the automobile 1 to have the vehicle inspected.

[0031] In this way, the vehicle 1 to which the invention disclosed in embodiment 1 is applied can provide a passive discharge circuit 24 of the smoothing capacitor that is capable of more reliable discharge. The reason for this is that it becomes possible to detect and notify the user of the automobile 1 to which the invention disclosed in embodiment 1 is applied of abnormalities in the passive discharge circuit 24, and the normal function of the passive discharge circuit 24 can be maintained.

[0032] <Embodiment 2> In addition to the invention disclosed in embodiment 1, the invention disclosed in embodiment 2 further includes a voltage bypass circuit 26. FIG. 6 shows an electric circuit of a main high-voltage electric device having a voltage bypass circuit. According to this, the voltage bypass circuit 26 is connected at a position connecting the positive pole of the passive discharge circuit 24 and the voltmeter 25. The voltage bypass circuit 26 includes a relay 26a. This relay 26a is initially open, but is configured to be closed when the determination processing unit 32 determines that there is an abnormality in the passive discharge circuit 24. As a specific example, the determination unit 30 may control the relay 26a to be closed. This control activates the voltage bypass circuit 26.

[0033] Although voltmeter 25 does not directly acquire the voltage of smoothing capacitor 22, it can also be used to indirectly acquire the voltage of smoothing capacitor 22 as long as passive discharge circuit 24 is normal. This is because, while the main power supply of automobile 1 is on, if voltage values ​​V1 and V2 are mapped within the normal range of voltage conversion map M1 for normal circuits, it can be determined that normal voltage is also being applied to smoothing capacitor 22. Furthermore, when the main power supply of automobile 1 is turned off in this state, it can be determined that discharge of smoothing capacitor 22 is progressing and its voltage is decreasing because voltage value V1 decreases.

[0034] However, if an abnormality occurs in the passive discharge circuit 24, the subsequent voltage value V1 will fluctuate depending on the type of failure in the passive discharge circuit 24, and therefore cannot be used to indirectly obtain the voltage of the smoothing capacitor 22. To address this issue, a voltage bypass circuit 26 is further provided, which reduces the fluctuation in voltage value V1 caused by the voltmeter 25 depending on whether or not there is an abnormality in the passive discharge circuit 24, thereby enabling the voltage of the smoothing capacitor 22 to be obtained indirectly.

[0035] The operation of the voltage bypass circuit 26 will be described using the flowchart of Fig. 7. First, the determination unit 30 determines whether there is an abnormality in the passive discharge circuit 24 by the method described in the first embodiment (step S20). At this stage, the relay 26a of the voltage bypass circuit 26 is open, and the voltage bypass circuit 26 is not activated.

[0036] Next, the determination unit 30 closes the relay 26a of the voltage bypass circuit 26 to activate the voltage bypass circuit 26 (step S21). The determination unit 30 may be connected to a relay control unit that controls the relay 26a to control the close of the relay 26a.

[0037] Next, the determination unit 30 switches the normal circuit voltage conversion map M1 to the abnormal circuit voltage conversion map M2, which is the pattern after the voltage bypass circuit 26 is activated (step S22). This will be explained in more detail. The voltage value V1 after the voltage bypass circuit 26 is activated will be explained using the graph in FIG.

[0038] When the voltage bypass circuit 26 is activated, the voltage value V1 becomes higher than the voltage conversion map for normal circuit conditions before the activation of the voltage bypass circuit 26, as indicated by the solid line in the graph. This is because the resistive voltage division for the smoothing capacitor 22 is set so that even if one of the resistors in the passive discharge circuit 24 has an abnormality, such as an open circuit or short circuit, the voltage value V1 becomes higher than the voltage conversion map for normal circuit conditions before the activation of the voltage bypass circuit 26. This allows the voltage value V1 to be set to a voltage for abnormal conditions even if an abnormality occurs in the passive discharge circuit 24. When the voltage bypass circuit 26 is activated, the voltage value V1 can be read without being affected by the passive discharge circuit 24. Therefore, a voltage conversion map for abnormal circuit conditions M2, which is a map of the voltage value V1 after the activation of the voltage bypass circuit 26, is used instead of the voltage conversion map for normal circuit conditions M1. In other words, the "solid line in the graph: voltage conversion map for abnormal circuit conditions after activation of the voltage bypass circuit" in the voltage conversion map for abnormal circuit conditions M2 is used.

[0039] The determination unit 30 may use the voltage conversion map M2 during circuit abnormality to perform the determination process (steps S10 to S13) based on the new criteria. The voltage conversion map M2 during circuit abnormality also has a threshold value that defines a normal range. The normal range of the voltage conversion map M2 during circuit abnormality is set to a value that exceeds the normal range of the voltage conversion map M1 during circuit normality.

[0040] In this way, in the vehicle 1 to which the invention disclosed in embodiment 2 is applied, the discharge status of the charge in the smoothing capacitor 22 can be confirmed through the voltage value V1 even if there is an abnormality in the passive discharge circuit 24, which contributes to improved safety.

[0041] The disclosed technology is not limited to the above-described embodiment, and includes various other configurations. For example, in the above-described embodiment, the disclosed technology can also be applied to hybrid vehicles and electric vehicles driven only by a motor. [Explanation of symbols]

[0042] 1. Automobiles 2 drive motor 3 High voltage circuits 3a Positive side main wiring 3b Negative side main wiring 10 Battery 20 Inverter 21 Switching circuit 21 22 Smoothing capacitor 22 23 Active Discharge Circuit 23 24 Passive Discharge Circuit24 25 Voltmeter 26 Voltage bypass circuit 26a Relay 30 Judgment section 30 31 Data Acquisition Section 32 Judgment processing unit 33 Judgment result notification section NW Network M1 circuit normal voltage conversion map

Claims

1. a battery mounted on a vehicle equipped with a drive motor; an inverter that controls the power supplied from the battery and outputs the power to the drive motor; A vehicle power control system comprising: The inverter is A smoothing capacitor; a passive discharge circuit connected in parallel to the smoothing capacitor; A voltage sensor; A controller and Equipped with the passive discharge circuit is a circuit configured with a plurality of resistors and further has one or more intermediate contacts; the voltage sensor acquires a voltage between the intermediate contact and a negative electrode of a passive discharge circuit; the controller detects an abnormality in the passive discharge circuit when a voltage supplied by the battery and a voltage acquired by the voltage sensor exceed a normal range in a first map; Vehicle discharge system.

2. The vehicle discharge system further comprises: a voltage bypass circuit that is installed between the positive electrode of the passive discharge circuit and the voltage sensor and controls the voltage detected by the voltage sensor to be a voltage at the time of abnormality detection; the voltage bypass circuit is normally open and is controlled to be closed when the controller detects an abnormality; When the controller detects an abnormality in the passive discharge circuit, the controller controls the voltage bypass circuit for use in circuit abnormality to be closed. The vehicle discharge system according to claim 1 .

3. the voltage bypass circuit is configured to divide the positive voltage and provide it to the voltage sensor; The voltage provided by the voltage division is set to be a voltage exceeding the first map.

3. The vehicle discharge system according to claim 2.

4. The voltage bypass circuit is configured so that, if the circuit is closed when the controller detects an abnormality, the circuit remains closed even when the vehicle power is turned ON again after being turned OFF.

4. The vehicle discharge system according to claim 3.

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