Measurement system

Abstract

To provide a measurement system contributing to more accurate detection of a battery voltage.SOLUTION: A measurement system S comprises: an IC 16 that receives drive power from a battery cell unit 11, detects voltage from a battery cell X as a first detection value when the battery cell X is not connected to an inverter 20, and detects the voltage from the battery cell X as a second detection value when the battery cell X is connected to the inverter 20; an IC 17 for detecting the voltage from the battery cell X as a third detection value when the battery cell X is not connected to the inverter 20; and a battery ECU 18 for correcting the second detection value by using a difference between the first detection value and the third detection value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to measurement systems. [Background technology]

[0002] Technologies for monitoring the state of batteries have been developed. For example, Patent Document 1 describes a battery monitoring device that monitors the state of unit batteries based on the voltages of multiple unit batteries detected by a measurement integrated circuit (IC) and the voltages of conductive members adjacent to the unit batteries. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-146728 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, when the unit battery to be measured serves as the driving power source for the measurement IC and the power line of the measurement IC and the voltage detection line of the unit battery are configured as the same path, there is a possibility that the accuracy of voltage detection will deteriorate. This is because the current consumed by the measurement IC may flow through the wiring resistance between the unit battery and the measurement IC, causing a voltage drop.

[0005] The present disclosure provides a measurement system that contributes to more accurate detection of battery voltage. [Means for solving the problem]

[0006] A measurement system according to an exemplary embodiment of the present disclosure includes: a first voltage detection unit that receives driving power from a battery cell, the first voltage detection unit detecting a voltage from the battery cell as a first detection value when the battery cell is not connected to an inverter, and detecting a voltage from the battery cell as a second detection value when the battery cell is connected to the inverter; a second voltage detection unit that detecting a voltage from the battery cell as a third detection value when the battery cell is not connected to the inverter; and a control unit that corrects the second detection value using a difference between the first detection value and the third detection value. [Effects of the Invention]

[0007] The present disclosure can provide a measurement system that contributes to more accurate detection of battery voltage. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram of a measurement system. [Figure 2] 10 is a flowchart showing the operation of the measurement system. [Figure 3] FIG. 2 is another block diagram of the measurement system. DETAILED DESCRIPTION OF THE INVENTION

[0009] Embodiment 1 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the following description and drawings have been omitted or simplified as appropriate for clarity of explanation.

[0010] Figure 1 shows a first block diagram of the measurement system. Measurement system S is a measurement system for a battery mounted on a vehicle, and includes a battery cell unit 11, a flexible printed circuit (FPC) 12, a battery monitoring unit 13, a battery ECU (Electronic Control Unit) 18, a system main relay (SMR) 19, and an inverter 20. Battery monitoring unit 13 includes a switch (SW) unit 14, noise filters 15A and 15B, ICs 16, and ICs 17, which are components configured on the same board. Hereinafter, the noise filter will also be referred to simply as a filter.

[0011] The battery cell unit 11 is composed of multiple (X) battery cells connected in series. Each battery cell is a secondary battery capable of charging and discharging. The FPC 12 is provided with multiple (X+1) wiring resistors that connect the battery cell unit 11 and the battery monitoring unit 13. These wiring resistors are connected in parallel. One end of each wiring resistor is connected to an end of a corresponding battery cell, and the other end is connected to one end of a resistor in the filter 15A. Furthermore, the other ends of wiring resistors 1 and 2, which are resistors in the first end region of the FPC 12, are connected to one end of SW4 and SW3 of the SW unit 14, respectively. The other ends of wiring resistors X and X+1, which are resistors in the second end region of the FPC 12, are connected to one end of SW2 and SW1 of the SW unit 14, respectively. Furthermore, the other ends of wiring resistors 1 and X+1 are directly connected to IC 16 without any resistors in between.

[0012] The battery monitoring unit 13 is a unit for monitoring the state of the battery cell unit 11 by measuring the voltage of each battery cell. The SW unit 14 has SW1 to SW4, which are turned on and off under the control of the battery ECU 18. The filter 15B has four resistors connected in parallel and two capacitors connecting two adjacent resistors together. The filter 15B reduces noise superimposed on the measured voltage when the IC 17 measures the voltage. As described above, one end of each of SW1 to SW4 is connected to a corresponding wiring resistor in the FPC 12. The other end of each of SW1 to SW4 is connected to one end of a resistor in the filter 15B. The other end of each resistor in the filter 15B is connected to the IC 17.

[0013] Filter 15A also has X+1 resistors connected in parallel and X capacitors connecting two adjacent resistors together. Filter 15A reduces noise superimposed on the measured voltage when IC 16 measures the voltage. As described above, one end of each resistor in filter 15A is connected to a corresponding wiring resistor in FPC 12. The other end of each resistor in filter 15A is connected to IC 16.

[0014] IC16 is provided to measure the voltage of each battery cell of the battery cell unit 11. IC16 has an A / D (Analog-to-Digital) converter (not shown) that converts the measured voltage data into a digital signal. IC16 outputs the converted digital signal to the battery ECU 18. IC17 has the same function as IC16. As described below, IC17 measures the voltage of the battery cell to calculate the voltage drop value. IC16 and IC17 output the measurement result data to the battery ECU 18.

[0015] Battery ECU 18 has a determination unit 181 and a memory unit 182. Determination unit 181 calculates a voltage drop value based on the measurement result data output from IC 16 or IC 17. Determination unit 181 also executes a correction process using the voltage drop value. Furthermore, determination unit 181 controls the ON / OFF of SW1 to SW4 to control which current from wiring resistors 1, 2, X, and X+1 flows to IC 17. Memory unit 182 stores the output measurement result data and determination results.

[0016] When the SMR 19 is ready to drive the vehicle, it switches a relay inside the SMR 19 to the ON state, causing drive power to be supplied from the battery cell unit 11 to the inverter 20. The inverter 20 converts the direct current supplied from the battery cell unit 11 to alternating current and supplies the converted current to each component of the vehicle. When the relay inside the SMR 19 is switched to the OFF state, drive power is not supplied from the battery cell unit 11 to the inverter 20.

[0017] When IC 16 obtains drive power from the battery cell unit 11, the current associated with the drive power flows through path P, which passes through wiring resistances 1 and X+1 inside FPC 12. In this example, path P does not pass through noise filter 15A. However, path P may also pass through another noise filter. In this case, a voltage drop occurs when the current passes through the wiring resistance on path P. The effect of the voltage drop can be reduced if the wiring inside FPC 12 can be separated into voltage measurement and power supply wiring. However, if this separation is not possible, the effect of the voltage drop cannot be ignored during normal voltage measurement by IC 16. In such a case, the voltages of battery cells X and 1 measured by IC 16 may be affected by the voltage drop and may be lower than the true voltage values ​​of battery cells X and 1.

[0018] Therefore, in the present disclosure, when the battery cell unit 11 is connected to IC16 so as to be able to supply driving power and the SMR 19 is OFF, IC17 mounted in the battery monitoring unit 13 measures the voltages of battery cell X and battery cell 1 with IC16 stopped. Furthermore, when the SMR 19 is OFF, IC16 measures the voltages of battery cell X and battery cell 1 by detecting the current flowing through path P as described above. The measurement results of IC16 and IC17 are stored in the memory unit 182. The determination unit 181 calculates the difference between the voltage measurement value of IC16 stored in the memory unit 182 and the voltage measurement value of IC17, and derives the voltage drop value based on the difference. Turning the SMR 19 OFF suppresses external noise from an inverter or the like from being reflected in the measurement value.

[0019] On the other hand, when the SMR 19 is in the ON state, the determination unit 181 adds the voltage drop value derived as described above to the voltage measurement value measured by the IC 16 when the SMR 19 is in the ON state, thereby enabling the determination unit 181 to measure the voltage of the battery cell while reducing the influence of the voltage drop.

[0020] The operation of the measurement system S will be described in detail below with reference to FIG. 2. First, the SMR 19 is set to the OFF state (step S12). At this time, the IC 16 is set to the stopped state, and the IC 17 is set to the driven state (step S14). The determination unit 181 controls SW3 and SW4 to be turned OFF (step S16). The determination unit 181 also controls SW1 and SW2 to be turned ON (step S18). As a result, the IC 17 forms a path through which the current flowing from the battery cell X passes through the wiring resistance X+1 and the wiring resistance X. The IC 17 measures the voltage of the battery cell X (third detection value) (step S20). The measured voltage value is converted into a digital signal and stored in the memory unit 182 (step S22).

[0021] Next, the determination unit 181 controls SW1 and SW2 to be turned OFF (step S24). The determination unit 181 also controls SW3 and SW4 to be turned ON (step S26). As a result, the IC 17 forms a path through which the current flowing from the battery cell 1 passes through the wiring resistance 1 and the wiring resistance 2. The IC 17 measures the voltage of the battery cell 1 (third detection value) (step S28). The measured voltage value is converted into a digital signal and stored in the memory unit 182 (step S30). Thereafter, the determination unit 181 turns SW3 and SW4 OFF (step S32).

[0022] Then, IC16 is set to an operating state (step S34). IC16 measures the voltages (first detection values) of battery cell 1 and battery cell X (step S36). The determination unit 181 derives the value of the voltage drop of battery cell 1 by calculating the difference between the measurement value of battery cell 1 measured in step S36 and converted into a digital signal and the measurement value of battery cell 1 stored in step S30. The determination unit 181 also derives the value of the voltage drop of battery cell X by calculating the difference between the measurement value of battery cell X measured in step S36 and converted into a digital signal and the measurement value of battery cell X stored in step S22 (step S38).

[0023] Thereafter, the SMR 19 is set to the ON state, thereby enabling the vehicle to be driven (step S40). The determination unit 181 corrects the measured voltage value of battery cell 1 by adding the voltage drop value derived in step S38 to the voltage measurement value of battery cell 1 (second detection value) measured by IC 16 in this state and converted into a digital signal. The determination unit 181 also corrects the measured voltage value of battery cell X by adding the voltage drop value derived in step S38 to the voltage measurement value of battery cell X (second detection value) measured by IC 16 in this state and converted into a digital signal (step S42). Note that the processing of step S40 is not essential, and the correction processing of step S42 is possible even if the SMR 19 remains in the OFF state.

[0024] As described above, the battery monitoring unit 13 has a branched measurement circuit, with a measurement IC at each branch. Therefore, the voltage of the battery cell when the measurement IC (IC16) is not operating under normal conditions can be measured by another IC 17 on the same board. This allows the battery cell voltage when no current is flowing through IC 16 to be measured and stored in the memory unit 182. The determination unit 181 calculates the voltage drop associated with the current consumption by comparing the stored voltage value with the battery cell voltage measured when current is flowing through IC 16. The determination unit 181 then eliminates the effect of the voltage drop from the battery cell voltage measured during normal operation. This improves the measurement accuracy of the battery cell even when the internal wiring of the FPC 12 is shared between voltage measurement and power supply.

[0025] Although the present disclosure has been described above with reference to the embodiments, the present disclosure is not limited to the above-described embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure.

[0026] For example, by making the resistance values ​​of wiring resistance X and wiring resistance 1 in Fig. 1 equal, SW3 and 4 and the associated circuit configuration can be removed as shown in Fig. 3. In this case, the measurement system S measures the voltage value by performing the process of either steps S16 to S22 or steps S24 to S30 in Fig. 2. The determination unit 181 derives the voltage drop value using the measured voltage value and the voltage value measured in step S36 for the battery cell whose measured voltage was recorded (step S38). This voltage drop value can be applied to both battery cell X and battery cell 1 in the correction process of step S42.

[0027] Moreover, a wire harness may be used instead of the FPC 12. [Explanation of symbols]

[0028] S Measurement system 11 Battery cell unit 12 FPC 13 Battery monitoring unit 14 Switch unit 15A, 15B Noise filter 16, 17 IC 18 Battery ECU 181 Judgment section 182 Memory section 19 SMR 20 Inverter

Claims

[Claim 1] a first voltage detection unit that receives drive power from a battery cell, the first voltage detection unit detecting a voltage from the battery cell as a first detection value when the battery cell is not connected to an inverter, and detecting a voltage from the battery cell as a second detection value when the battery cell is connected to the inverter; a second voltage detection unit that detects a voltage from the battery cell as a third detection value when the battery cell is not connected to the inverter; a control unit that corrects the second detection value using a difference between the first detection value and the third detection value, Measurement system.

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