WO2015145496A1 - Current detection apparatus and power supply system - Google Patents

Current detection apparatus and power supply system Download PDF

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Publication number
WO2015145496A1
WO2015145496A1 PCT/JP2014/004967 JP2014004967W WO2015145496A1 WO 2015145496 A1 WO2015145496 A1 WO 2015145496A1 JP 2014004967 W JP2014004967 W JP 2014004967W WO 2015145496 A1 WO2015145496 A1 WO 2015145496A1
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Prior art keywords
voltage
amplifier
output voltage
current detection
gain
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PCT/JP2014/004967
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French (fr)
Japanese (ja)
Inventor
克昭 濱本
岸本　圭司
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三洋電機株式会社
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Publication of WO2015145496A1 publication Critical patent/WO2015145496A1/en

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/0092—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/382—Arrangements for monitoring battery or accumulator variables, e.g. SoC
    • G01R31/3828—Arrangements for monitoring battery or accumulator variables, e.g. SoC using current integration
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/48—Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R35/00—Testing or calibrating of apparatus covered by the other groups of this subclass
    • G01R35/005—Calibrating; Standards or reference devices, e.g. voltage or resistance standards, "golden" references
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0047—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with monitoring or indicating devices or circuits
    • H02J7/0048—Detection of remaining charge capacity or state of charge [SOC]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to a current detection device that detects a current flowing in a secondary battery, and a power supply system including the current detection device.
  • HV hybrid cars
  • EV electric cars
  • These vehicles are equipped with a traveling motor and a secondary battery that supplies electric power to the traveling motor and stores electric power regenerated from the traveling motor.
  • lithium ion batteries and nickel metal hydride batteries are used as in-vehicle secondary batteries.
  • a regular area and a use-prohibited area are close to each other in a lithium ion battery, it is necessary to manage voltage and current more strictly than other types of batteries (see, for example, Patent Document 1).
  • the present invention has been made in view of such circumstances, and an object thereof is to provide a technique for detecting a current flowing in a secondary battery with high accuracy.
  • a current detection device includes a first voltage amplification unit that amplifies a voltage across a first current detection element connected in series to a secondary battery, both ends of the first current detection element, and the first voltage. Inserted between both ends of the input of the amplifying unit to supply a voltage between both ends of the first current detecting element to both ends of the input of the first voltage amplifying unit, or to detect an offset voltage of the first voltage amplifying unit
  • a switching unit that switches whether to supply a voltage, a second voltage amplification unit that amplifies a voltage across a second current detection element connected in series to the secondary battery and the first current detection element, and the first voltage amplification unit
  • the gain of the second voltage amplification unit is fixed, the output voltage of the first voltage amplification unit is used for calculating the SOC of the secondary battery, and the output of the second voltage amplification unit Voltage is used for overcurrent detection of the secondary battery It is.
  • the current flowing through the secondary battery can be detected with high accuracy.
  • FIG. 1 is a diagram showing a configuration of a power supply system 300 according to Embodiment 1 of the present invention.
  • the power supply system 300 is mounted on a hybrid car or an electric vehicle, and supplies power to a load 400 in the vehicle.
  • a traveling motor is assumed as load 400 in the vehicle.
  • the power supply system 300 and the traveling motor are connected via an inverter (not shown).
  • the inverter converts the DC voltage supplied from the power supply system 300 into an AC voltage and supplies it to the traveling motor, and converts the AC voltage supplied from the traveling motor into a DC voltage and supplies it to the power supply system 300.
  • the power supply system 300 includes a secondary battery 200, a first shunt resistor R1, a second shunt resistor R2, and a current detection device 100.
  • the current detection device 100 includes a current measurement unit 10 and a microcontroller 20. In this specification, attention is paid to the current detection of the secondary battery 200, and therefore the configuration relating to the voltage detection is omitted in FIG.
  • Secondary battery 200 includes a plurality of lithium ion battery cells connected in series.
  • 12 or 13 lithium ion battery cells having a representative voltage of 3.6 to 3.7 V are connected in series to form a 48 V assembled battery.
  • the kind or voltage of a battery is an example, and is not limited to the above.
  • the first shunt resistor R1 and the second shunt resistor R2 are connected in series to the secondary battery 200.
  • the first shunt resistor R1 and the second shunt resistor R2 have the same resistance value (for example, 1 m ⁇ ).
  • the first shunt resistor R1 and the second shunt resistor R2 are examples of current detection elements, and Hall elements may be used instead of the first shunt resistor R1 and the second shunt resistor R2.
  • the current measurement unit 10 includes a first voltage amplification unit 11, a second voltage amplification unit 12, and a switching unit 13.
  • the microcontroller 20 includes a calculation unit 21, a switching unit 26, a first AD converter 27, and a second AD converter 28.
  • the first voltage amplifier 11 amplifies the voltage across the first shunt resistor R1.
  • the second voltage amplifier 12 amplifies the voltage across the second shunt resistor R2.
  • the first shunt resistor R1 and the first voltage amplification unit 11 are mainly used for calculating the SOC of the secondary battery 200.
  • the second shunt resistor R2 and the second voltage amplification unit 12 are mainly used for overcurrent detection of the secondary battery 200.
  • the former is positioned as an active system, and the latter is a standby system. In the present embodiment, both are basically operating.
  • the first voltage amplification unit 11 is designed to have higher specifications than the second voltage amplification unit 12.
  • the gain of the first voltage amplification unit 11 is designed to be variable, and the gain of the second voltage amplification unit 12 is designed to be fixed.
  • the first voltage amplification unit 11 is added with an offset detection circuit, and the second voltage amplification unit 12 is not added with an offset detection circuit.
  • the switching unit 13 is inserted between both ends of the first shunt resistor R1 and both ends of the input of the first voltage amplifying unit 11.
  • the switching unit 13 switches between supplying the both-ends voltage of the first shunt resistor R ⁇ b> 1 or the voltage for detecting the offset voltage of the first voltage amplifying unit 11 to both ends of the input of the first voltage amplifying unit 11.
  • a ground potential is used as a voltage for detecting the offset voltage.
  • the same potential may be supplied to both ends of the input of the first voltage amplification unit 11, or a fixed potential other than the ground potential may be supplied.
  • the switching unit 13 is controlled to be switched according to a selection signal from the calculation unit 21.
  • FIG. 1 illustrates an example in which the switching unit 13 includes two C contact switches.
  • Each C contact switch is composed of a semiconductor switching element such as a MOSFET or IGBT.
  • the first voltage amplifier 11 includes a first amplifier 11a and a second amplifier 11b connected in parallel.
  • the first amplifier 11a amplifies the voltage across the first shunt resistor R1 and outputs the amplified voltage to the switching unit 26.
  • the second amplifier 11b also amplifies the voltage across the first shunt resistor R1 and outputs it to the switching unit 26.
  • the second gain of the second voltage amplifier 12 is set higher than the first gain of the first voltage amplifier 11.
  • the switching unit 26 selects the output voltage of the first amplifier 11a and the output voltage of the second amplifier 11b in a time division manner and outputs the selected voltage to the first AD converter 27.
  • the first AD converter 27 converts the input analog voltage into a digital value and outputs the digital value to the calculation unit 21.
  • the switching unit 26 is configured by a multiplexer, for example. In this way, the output voltage of the first amplifier 11a and the second amplifier 11b is switched and input to the first AD converter 27, whereby the gain of the entire first voltage amplifier 11 is variable.
  • the second voltage amplifier 12 has a third amplifier 12a.
  • the third amplifier 12a amplifies the voltage across the second shunt resistor R2 and outputs the amplified voltage to the second AD converter 28.
  • the second AD converter 28 converts the input analog voltage into a digital value and outputs the digital value to the calculation unit 21.
  • the third gain of the third amplifier 12a is set to the same value as the first gain of the first amplifier 11a. In the present embodiment, the first gain of the first amplifier 11a is 10 times, the second gain of the second amplifier 11b is 20 times, and the third gain of the third amplifier 12a is 10 times.
  • FIG. 2 is a diagram for explaining the first amplifier 11a of FIG.
  • FIG. 2A is a diagram illustrating a configuration example of the first amplifier 11a.
  • the first amplifier 11a includes an operational amplifier OP1, a resistor R4, a resistor R5, a resistor R6, and a resistor R7, and constitutes a differential amplifier circuit.
  • the potential of one end of the first shunt resistor R1 is input to the inverting input terminal of the operational amplifier OP1 through the resistor R4.
  • the inverting input terminal and output terminal of the operational amplifier OP1 are connected via a resistor R5.
  • the potential of the other end of the first shunt resistor R1 is input to the non-inverting input terminal of the operational amplifier OP1 through the resistor R6.
  • the reference potential Vr is input to the non-inverting input terminal of the operational amplifier OP1 through the resistor R7.
  • the differential amplifier circuit shown in FIG. 2A is a circuit that amplifies the input differential voltage Vdiff with a set gain (R5 / R4) when the reference potential Vr is 0V.
  • the first AD converter 27 and the second AD converter 28 are built in the microcontroller 20.
  • the AD converter built in the microcontroller 20 can handle only positive values.
  • the output voltage of the first amplifier 11a may be a negative value.
  • the level shift is performed so that the output voltage of the first amplifier 11a is always a positive value. If the reference potential Vr is set to a half potential of the power supply voltage of the microcontroller 20, the output voltage of the first amplifier 11a can always be a positive value. In this embodiment, since the power supply voltage of the microcontroller 20 is set to 5V, the reference potential Vr is set to 2.5V.
  • FIG. 2 (b) is a diagram showing input / output characteristics of the first amplifier 11a of FIG. 2 (a).
  • the gain G is described as a negative value.
  • the output voltage of the first amplifier 11a is level-shifted to 2.5V and the positive side. That is, when the input differential voltage Vdiff is 0V, the output voltage Vo is 2.5V.
  • the second amplifier 11b and the third amplifier 12a can be configured similarly to the first amplifier 11a. If the first AD converter 27 and the second AD converter 28 are provided outside the microcontroller 20 and can also handle negative values, the reference potential Vr can be set to 0V.
  • the calculation unit 21 includes a current calculation unit 22, an offset calculation unit 23, an offset holding unit 24, and an SOC calculation unit 25.
  • the computing unit 21 is realized only by hardware resources or by cooperation of hardware resources and software resources.
  • the offset calculation unit 23 supplies a selection signal to the switching unit 13 and supplies a ground potential to both ends of the input of the first voltage amplification unit 11. In this state, the offset calculation unit 23 calculates an offset voltage value from the output voltage of the first voltage amplification unit 11.
  • the offset voltage Vio can be calculated by the following (Equation 1).
  • Vio (Vmio ⁇ 2.5) / G (Formula 1) Vio represents the offset voltage of the first amplifier 11a, G represents the gain of the first amplifier 11a, 2.5V represents the reference potential Vr, and Vmio represents the output voltage of the first amplifier 11a when calculating the offset voltage value.
  • the offset voltage of the second amplifier 11b can be calculated similarly.
  • the offset calculation unit 23 holds the calculated offset voltage value of the first amplifier 11a and the calculated offset voltage value of the second amplifier 11b in the offset holding unit 24.
  • the offset calculation unit 23 executes the above offset calculation every time the power supply system 300 is activated. After startup, it is executed whenever the temperature value from a temperature sensor (not shown) changes beyond the set value. This is because the operational amplifier and the resistor have temperature characteristics, so that the offset voltage changes when the temperature changes.
  • the current calculation unit 22 calculates the current value of the secondary battery 200 based on the output voltage of the first voltage amplification unit 11.
  • the current calculation unit 22 calculates the current value of the secondary battery 200 based on the output voltage of the second voltage amplification unit 12.
  • the current calculation unit 22 uses the offset voltage value of the first amplifier 11a held in the offset holding unit 24 to perform the first operation.
  • the output voltage of the amplifier 11a is corrected.
  • the current calculation unit 22 uses the offset voltage value of the second amplifier 11b held in the offset holding unit 24.
  • the output voltage of the second amplifier 11b is corrected.
  • the current calculation unit 22 uses the offset voltage value of the first amplifier 11 a held in the offset holding unit 24.
  • the output voltage of the three amplifier 12a is corrected.
  • the first amplifier 11a and the third amplifier 12a need to be configured with the same specifications. If the two specifications are different, the output voltage of the third amplifier 12a is corrected by a value obtained by multiplying the offset voltage value of the first amplifier 11a by a correction coefficient for correcting the difference.
  • the current calculation unit 22 calculates the input differential voltage Vdiff by the following (Formula 2) or (Formula 3), and calculates the current value I by the following (Formula 4).
  • Vdiff ⁇ (Vo ⁇ 2.5) / G) ⁇ Vio (Formula 2)
  • Vdiff ⁇ (Vo ⁇ 2.5) ⁇ (Vmio ⁇ 2.5) ⁇ / G (Formula 3)
  • I Vdiff / Rs (Formula 4)
  • Rs represents the resistance value of the shunt resistor, and Vo represents the output voltage of the first amplifier 11a.
  • the SOC calculation unit 25 calculates the SOC of the secondary battery 200 by integrating the current values calculated by the current calculation unit 22. In the default state, the SOC calculation unit 25 uses a current value calculated based on the output voltage of the first amplifier 11a. When the output voltage of the first amplifier 11a is equal to or higher than the set value, the SOC of the secondary battery 200 is calculated based on the output voltage of the first amplifier 11a. When the output voltage of the first amplifier 11a is less than the set value, the output voltage of the second amplifier 11b or the average value of the output voltages of the first amplifier 11a and the second amplifier is used.
  • the gain of the latter is higher, so that the voltage across the first shunt resistor R1 can be detected with high resolution.
  • the output voltage of the second amplifier 11b may be saturated. Therefore, in the default state, the output voltage of the first amplifier 11a having a wide input voltage range is used.
  • the output voltage of the first amplifier 11a When the output voltage of the first amplifier 11a is less than the set value, it can be determined that the current flowing through the secondary battery 200 is not large and the output voltage is not saturated even when detected by the second amplifier 11b. In this case, the current value is calculated based on the output voltage of the second amplifier 11b that can be detected with higher accuracy. In order to reduce the influence of variations in the outputs of the first amplifier 11a and the second amplifier 11b, an average value of both may be used. A weighted average value may be used. In the case of weighting, the ratio of the second amplifier 11b may be set high. The above set values can be derived from experiments or simulations by the designer.
  • an overcurrent determination unit inside the microcontroller 20 uses a current value calculated based on the output voltage of the first amplifier 11a or a current value calculated based on the output voltage of the third amplifier 12a. To do.
  • An abnormality detector inside the microcontroller 20 detects an abnormality of the power supply system 300 by comparing the output voltage of the first amplifier 11a with the output voltage of the third amplifier 12a. If the power supply system 300 is normal, the output voltages of the two are almost the same. Accordingly, when a deviation exceeding the set value occurs between the output voltages of both, it can be determined that an abnormality has occurred in any of the elements.
  • the abnormality detection unit notifies an alert to an unillustrated ECU (Electronic Control Unit) via a CAN (Controller Area Network) (not shown).
  • the ECU informs the driver of the abnormality by lighting a lamp indicating abnormality of the power supply system 300 on the instrument panel or sounding an alarm.
  • the first shunt resistor R1 and the first voltage amplifying unit 11, the second shunt resistor R2 and the second voltage amplifying unit 12 are provided, and the current is detected by each set.
  • the current detection device 100 that has redundancy and is resistant to failure.
  • the gain of the first voltage amplifier 11 used in the main variable the resolution can be adjusted according to the magnitude of the current flowing through the secondary battery 200, and the current flowing through the secondary battery can be adjusted. It can be detected with high accuracy.
  • the second voltage amplifier 12 used in the sub is not provided with an offset detection circuit with a fixed gain, an increase in cost can be suppressed.
  • the second voltage amplification unit 12 can be configured at low cost and with high accuracy.
  • FIG. 3 is a diagram showing a configuration of a power supply system 300 according to Embodiment 2 of the present invention.
  • the first amplifier 11a and the third amplifier 12a are provided without providing the second amplifier 11b.
  • the output voltage of the first amplifier 11 a is directly input to the first AD converter 27 without providing the switching unit 13 and the switching unit 26.
  • the load 400 is assumed to be a motor / generator, and the discharge current when discharging from the secondary battery 200 to the load 400 (motor mode) and the charging current when charging the secondary battery 200 from the load 400 (generator mode) are currents. Detection is performed by the detection device 100.
  • the inverting input terminal of the first amplifier 11a is connected to one end (low potential side) of the first shunt resistor R1.
  • the non-inverting input terminal of the first amplifier 11a can be connected to the other end (high potential side) of the first shunt resistor R1 or one end (low potential side) of the second shunt resistor R2 via the first switch SW1. is there.
  • the definitions of the high potential side and the low potential side indicate the direction of the voltage generated at both ends of the shunt resistor when discharging from the secondary battery 200 to the load 400, and the same definition will be used in the following description.
  • the inverting input terminal of the third amplifier 12a is connected to one end (low potential side) of the second shunt resistor R2.
  • the non-inverting input terminal of the third amplifier 12a can be connected to the other end (high potential side) of the second shunt resistor R2 or the other end (high potential side) of the first shunt resistor R1 via the second switch SW2. It is.
  • the offset voltage Vio is zero.
  • the output voltage Vo1 of the first amplifier 11a is 4.5V.
  • the output voltage Vo2 of the first amplifier 11a is 0.5V.
  • the offset voltage Vio is 100 mV.
  • the output voltage Vo1 of the first amplifier 11a is 4.6V.
  • the output voltage Vo2 of the first amplifier 11a is 0.6V.
  • the output voltage Vo1 and the output voltage Vo2 of the first amplifier 11a are calculated by the following (formula 5) and the following (formula 6), the offset voltage Vio of the first amplifier 11a is calculated by the following (formula 7), and the first amplifier 11a
  • the output voltage (true value) Vt before the level shift is calculated by the following (formula 8).
  • Vo1 2.5 + Vt + Vio (Formula 5)
  • Vo2 2.5 ⁇ Vt + Vio (Expression 6)
  • Vio (Vo1 + Vo2-2.5 ⁇ 2) / 2 (Expression 7)
  • Vt (Vo1-Vo2) / 2 (Expression 8)
  • 2.5V represents the voltage shift
  • Vt represents the true value before the shift
  • Vio represents the offset voltage.
  • the true value Vt can be calculated from the output voltage Vo1 and the output voltage Vo2 of the first amplifier 11a, and the offset voltage Vio can be calculated if the true value Vt can be calculated.
  • the true value Vt is 2.0V and the offset voltage Vio is 100mV. In this way, the offset voltage of the first amplifier 11a can be detected without supplying the ground potential to the both-end potential of the first amplifier 11a.
  • (Equation 8) is used, the true value Vt can be calculated directly from the output voltage Vo1 and the output voltage Vo2 of the first amplifier 11a without calculating the offset voltage Vio.
  • the offset voltage Vio is zero.
  • a state in which a current of 100 A is discharged from the secondary battery 200 to the load 400 will be considered.
  • the voltage across the second shunt resistor R2 is 100 mV
  • the voltage across the resistor in which the first shunt resistor R1 and the second shunt resistor R2 are connected in series is 200 mV.
  • the output voltage Vo1 of the third amplifier 12a is 3.5V.
  • the output voltage Vo2 of the third amplifier 12a is 4.5V. Since any value falls within the range of 0 to 5V, the output voltage Vo2 with higher resolution is used.
  • the resistance value is doubled, so that the state is substantially the same as the doubled state ( ⁇ 20).
  • the voltage across the second shunt resistor R2 is 200 mV
  • the voltage across the resistor in which the first shunt resistor R1 and the second shunt resistor R2 are connected in series is 400 mV.
  • the output voltage Vo1 of the third amplifier 12a is 4.5V.
  • the output voltage Vo2 of the third amplifier 12a is 6.5V. Since the value of the output voltage Vo2 exceeds the range of 0 to 5V, the output voltage Vo1 is used.
  • the first switch SW1 and the second switch SW2 are provided, and the potentials input to the first amplifier 11a and the third amplifier 12a are switched, so that The same effect is produced.
  • FIG. 4 is a diagram showing a configuration of a power supply system 300 according to Embodiment 3 of the present invention.
  • the first amplifier 11a is provided without providing the second amplifier 11b and the third amplifier 12a. Further, the output voltage of the first amplifier 11 a is directly input to the first AD converter 27 without providing the switching unit 13 and the switching unit 26.
  • the second AD converter 28 is not provided.
  • a third shunt resistor R3 is connected in series with the first shunt resistor R1 and the second shunt resistor R2. The resistance value of the third shunt resistor R3 is also 1 m ⁇ .
  • the inverting input terminal of the first amplifier 11a is connected to one end (low potential side) of the second shunt resistor R2.
  • the non-inverting input terminal of the first amplifier 11a is connected to the other end (high potential side) of the second shunt resistor R2, one end (low potential side) of the third shunt resistor R3, or the first shunt resistor via the third switch SW3. This is a configuration connectable to the other end (high potential side) of R1.
  • the non-inverting input terminal of the first amplifier 11a is connected to the other end (high potential side) of the second shunt resistor R2 and the state where it is connected to one end (low potential side) of the third shunt resistor R3 is
  • the non-inverting input terminal of the first amplifier 11a is connected to the other end (high potential side) of the first shunt resistor R1, and is connected to one end (low potential side) of the second shunt resistor R2.
  • the non-inverting input terminal of the third amplifier 12a is connected to the other end (high potential side) of the second shunt resistor R2, and the other end (high potential side) of the first shunt resistor R1. It is the same situation as the combination of the states connected to. Therefore, the resolution can be switched.
  • FIG. 5 is a diagram showing a configuration of a power supply system 300 according to Embodiment 4 of the present invention.
  • the fourth embodiment only the first amplifier 11a is provided without providing the second amplifier 11b and the third amplifier 12a. Further, the output voltage of the first amplifier 11 a is directly input to the first AD converter 27 without providing the switching unit 13 and the switching unit 26. The second AD converter 28 is not provided.
  • the inverting input terminal of the first amplifier 11a can be connected to one end (low potential side) of the second shunt resistor R2 or the other end (high potential side) of the second shunt resistor R2 via the second switch SW2. is there.
  • the non-inverting input terminal of the first amplifier 11a can be connected to one end (low potential side) of the second shunt resistor R2 or the other end (high potential side) of the first shunt resistor R1 via the first switch SW1. It is.
  • the inverting input terminal of the first amplifier 11a is connected (fixed) to the other end (high potential side) of the second shunt resistor R2, and the non-inverting input terminal of the first amplifier 11a is the other end (high) of the first shunt resistor R1.
  • the non-inverting input terminal of the first amplifier 11a is connected to the first shunt resistor.
  • the combination of the state connected to the other end (high potential side) of R1 and the state connected to one end (low potential side) of the second shunt resistor R2 is the same situation. Therefore, the offset voltage can be detected.
  • the non-inverting input terminal of the first amplifier 11a is connected (fixed) to the other end (high potential side) of the first shunt resistor R1, and the inverting input terminal of the first amplifier 11a is connected to the other end of the second shunt resistor R2.
  • the combination of the state connected to the high potential side) and the state connected to one end (low potential side) of the second shunt resistor R2 is the same as that of the second shunt of the third amplifier 12a in the second embodiment.
  • the combination of the state connected to the other end (high potential side) of the resistor R2 and the state connected to the other end (high potential side) of the first shunt resistor R1 is the same situation. Therefore, the resolution can be switched.
  • the first gain of the first amplifier 11a and the third gain of the third amplifier 12a are set to the same value.
  • the third gain may be set to a value (for example, 8 times) smaller than the first gain.
  • the third amplifier 12a can detect a wider range of current than the first amplifier 11a.
  • the SOC is calculated based on a voltage with low resolution. The designer sets the first gain of the first amplifier 11a and the third gain of the third amplifier 12a in consideration of this trade-off relationship.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
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  • Charge And Discharge Circuits For Batteries Or The Like (AREA)
  • Secondary Cells (AREA)

Abstract

A first voltage amplifying unit (11) amplifies an end-to-end voltage of a first current detection element connected in series to a secondary battery (200). A switch unit (13) is inserted between both the ends of the first current detection element, and both the input ends of the first voltage amplifying unit (11), and performs switching between whether to supply both the input ends of the first voltage amplifying unit (11) with the end-to-end voltage of the first current detection element or with a voltage for detecting an offset voltage of the first voltage amplifying unit (11). A second voltage amplifying unit (12) amplifies an end-to-end voltage of a second current detection element connected in series to the secondary battery (200) and the first current detection element. The gain of the first voltage amplifying unit (11) is variable, and the gain of the second voltage amplifying unit (12) is constant. The output voltage of the first voltage amplifying unit (11) is used for the purpose of calculating the state of charge (SOC) of the secondary battery (200), and the output voltage of the second voltage amplifying unit (12) is used for the purpose of detecting an overcurrent of the secondary battery (200).

Description

電流検出装置、電源システムCurrent detection device, power supply system
　本発明は、二次電池に流れる電流を検出する電流検出装置、及びそれを備えた電源システムに関する。 The present invention relates to a current detection device that detects a current flowing in a secondary battery, and a power supply system including the current detection device.
　近年、ハイブリットカー（ＨＶ）、電気自動車（ＥＶ）が普及してきている。それらの車両には走行用モータが搭載されるとともに、走行用モータに電力を供給し、走行用モータから回生される電力を蓄える二次電池が搭載される。車載用二次電池にはリチウムイオン電池、ニッケル水素電池が用いられることが一般的である。特に、リチウムイオン電池は常用領域と使用禁止領域が近接しているため、他の種類の電池より厳格に電圧および電流を管理する必要がある（例えば、特許文献１参照）。 In recent years, hybrid cars (HV) and electric cars (EV) have become widespread. These vehicles are equipped with a traveling motor and a secondary battery that supplies electric power to the traveling motor and stores electric power regenerated from the traveling motor. In general, lithium ion batteries and nickel metal hydride batteries are used as in-vehicle secondary batteries. In particular, since a regular area and a use-prohibited area are close to each other in a lithium ion battery, it is necessary to manage voltage and current more strictly than other types of batteries (see, for example, Patent Document 1).
特開２００２－６２３４１号公報JP 2002-62341 A
　二次電池のＳＯＣ（State Of Charge）推定には、電流の時間積分から求める電流積算法が用いられることが多い。従ってＳＯＣを高精度に推定するには、電流値を正確に検出する必要がある。また二次電池を保護するには過電流を的確に検出する必要がある。 In order to estimate the SOC (State Of Charge) of a secondary battery, a current integration method obtained from current time integration is often used. Therefore, in order to estimate the SOC with high accuracy, it is necessary to accurately detect the current value. In addition, it is necessary to accurately detect overcurrent in order to protect the secondary battery.
　本発明はこうした状況に鑑みなされたものであり、その目的は、二次電池に流れる電流を高精度に検出する技術を提供することにある。 The present invention has been made in view of such circumstances, and an object thereof is to provide a technique for detecting a current flowing in a secondary battery with high accuracy.
　本発明のある態様の電流検出装置は、二次電池に直列接続された第１電流検出素子の両端電圧を増幅する第１電圧増幅部と、前記第１電流検出素子の両端と前記第１電圧増幅部の入力両端の間に挿入され、前記第１電圧増幅部の入力両端に、前記第１電流検出素子の両端電圧を供給するか、前記第１電圧増幅部のオフセット電圧を検出するための電圧を供給するか切り替える切替部と、前記二次電池および前記第１電流検出素子に直列接続された第２電流検出素子の両端電圧を増幅する第２電圧増幅部と、前記第１電圧増幅部のゲインは可変であり、前記第２電圧増幅部のゲインは固定であり、前記第１電圧増幅部の出力電圧は、前記二次電池のＳＯＣ算出に使用され、前記第２電圧増幅部の出力電圧は、前記二次電池の過電流検出に使用される。 A current detection device according to an aspect of the present invention includes a first voltage amplification unit that amplifies a voltage across a first current detection element connected in series to a secondary battery, both ends of the first current detection element, and the first voltage. Inserted between both ends of the input of the amplifying unit to supply a voltage between both ends of the first current detecting element to both ends of the input of the first voltage amplifying unit, or to detect an offset voltage of the first voltage amplifying unit A switching unit that switches whether to supply a voltage, a second voltage amplification unit that amplifies a voltage across a second current detection element connected in series to the secondary battery and the first current detection element, and the first voltage amplification unit The gain of the second voltage amplification unit is fixed, the output voltage of the first voltage amplification unit is used for calculating the SOC of the secondary battery, and the output of the second voltage amplification unit Voltage is used for overcurrent detection of the secondary battery It is.
　本発明によれば、二次電池に流れる電流を高精度に検出できる。 According to the present invention, the current flowing through the secondary battery can be detected with high accuracy.
本発明の実施の形態１に係る電源システムの構成を示す図である。It is a figure which shows the structure of the power supply system which concerns on Embodiment 1 of this invention. 図１の第１増幅器を説明するための図である。It is a figure for demonstrating the 1st amplifier of FIG. 本発明の実施の形態２に係る電源システムの構成を示す図である。It is a figure which shows the structure of the power supply system which concerns on Embodiment 2 of this invention. 本発明の実施の形態３に係る電源システムの構成を示す図である。It is a figure which shows the structure of the power supply system which concerns on Embodiment 3 of this invention. 本発明の実施の形態４に係る電源システムの構成を示す図である。It is a figure which shows the structure of the power supply system which concerns on Embodiment 4 of this invention.
　図１は、本発明の実施の形態１に係る電源システム３００の構成を示す図である。電源システム３００はハイブリッドカー、又は電気自動車に搭載され、車両内の負荷４００に電力を供給する。本実施の形態では車両内の負荷４００として走行用モータを想定する。電源システム３００と走行用モータは、図示しないインバータを介して接続される。インバータは、電源システム３００から供給される直流電圧を交流電圧に変換して走行用モータに供給し、走行用モータから供給される交流電圧を直流電圧に変換して電源システム３００に供給する。 FIG. 1 is a diagram showing a configuration of a power supply system 300 according to Embodiment 1 of the present invention. The power supply system 300 is mounted on a hybrid car or an electric vehicle, and supplies power to a load 400 in the vehicle. In the present embodiment, a traveling motor is assumed as load 400 in the vehicle. The power supply system 300 and the traveling motor are connected via an inverter (not shown). The inverter converts the DC voltage supplied from the power supply system 300 into an AC voltage and supplies it to the traveling motor, and converts the AC voltage supplied from the traveling motor into a DC voltage and supplies it to the power supply system 300.
　電源システム３００は二次電池２００、第１シャント抵抗Ｒ１、第２シャント抵抗Ｒ２及び電流検出装置１００を備える。電流検出装置１００は電流計測部１０及びマイクロコントローラ２０を含む。なお本明細書では二次電池２００の電流検出に注目しているため、図１では電圧検出に関する構成は省略して描いている。 The power supply system 300 includes a secondary battery 200, a first shunt resistor R1, a second shunt resistor R2, and a current detection device 100. The current detection device 100 includes a current measurement unit 10 and a microcontroller 20. In this specification, attention is paid to the current detection of the secondary battery 200, and therefore the configuration relating to the voltage detection is omitted in FIG.
　二次電池２００は、直列接続された複数のリチウムイオン電池セルを含む。本実施の形態では代表電圧３．６～３．７Ｖのリチウムイオン電池セルが１２個または１３個直列接続されて４８Ｖの組電池を構成している。なお電池の種類または電圧は一例であり、上記に限定されるものではない。 Secondary battery 200 includes a plurality of lithium ion battery cells connected in series. In this embodiment, 12 or 13 lithium ion battery cells having a representative voltage of 3.6 to 3.7 V are connected in series to form a 48 V assembled battery. In addition, the kind or voltage of a battery is an example, and is not limited to the above.
　第１シャント抵抗Ｒ１及び第２シャント抵抗Ｒ２は、二次電池２００に直列接続される。本実施の形態では第１シャント抵抗Ｒ１及び第２シャント抵抗Ｒ２に、同じ抵抗値（例えば、１ｍΩ）のものが使用される。なお第１シャント抵抗Ｒ１及び第２シャント抵抗Ｒ２は電流検出素子の一例であり、第１シャント抵抗Ｒ１及び第２シャント抵抗Ｒ２の代わりに、それぞれホール素子が使用されてもよい。 The first shunt resistor R1 and the second shunt resistor R2 are connected in series to the secondary battery 200. In the present embodiment, the first shunt resistor R1 and the second shunt resistor R2 have the same resistance value (for example, 1 mΩ). The first shunt resistor R1 and the second shunt resistor R2 are examples of current detection elements, and Hall elements may be used instead of the first shunt resistor R1 and the second shunt resistor R2.
　電流計測部１０は第１電圧増幅部１１、第２電圧増幅部１２及び切替部１３を含む。マイクロコントローラ２０は演算部２１、切替部２６、第１ＡＤ変換器２７及び第２ＡＤ変換器２８を含む。 The current measurement unit 10 includes a first voltage amplification unit 11, a second voltage amplification unit 12, and a switching unit 13. The microcontroller 20 includes a calculation unit 21, a switching unit 26, a first AD converter 27, and a second AD converter 28.
　第１電圧増幅部１１は第１シャント抵抗Ｒ１の両端電圧を増幅する。第２電圧増幅部１２は第２シャント抵抗Ｒ２の両端電圧を増幅する。第１シャント抵抗Ｒ１及び第１電圧増幅部１１は、主に二次電池２００のＳＯＣ算出用に使用される。一方、第２シャント抵抗Ｒ２及び第２電圧増幅部１２は、主に二次電池２００の過電流検出用に使用される。基本的に前者が現用系、後者が予備系という位置づけになるが、本実施の形態では両方とも動作している状態を基本とする。 The first voltage amplifier 11 amplifies the voltage across the first shunt resistor R1. The second voltage amplifier 12 amplifies the voltage across the second shunt resistor R2. The first shunt resistor R1 and the first voltage amplification unit 11 are mainly used for calculating the SOC of the secondary battery 200. On the other hand, the second shunt resistor R2 and the second voltage amplification unit 12 are mainly used for overcurrent detection of the secondary battery 200. Basically, the former is positioned as an active system, and the latter is a standby system. In the present embodiment, both are basically operating.
　第１電圧増幅部１１は第２電圧増幅部１２より高仕様に設計する。例えば第１電圧増幅部１１のゲインは可変に、第２電圧増幅部１２のゲインは固定に設計する。また第１電圧増幅部１１はオフセット検出回路が付加され、第２電圧増幅部１２はオフセット検出回路が付加されない。 The first voltage amplification unit 11 is designed to have higher specifications than the second voltage amplification unit 12. For example, the gain of the first voltage amplification unit 11 is designed to be variable, and the gain of the second voltage amplification unit 12 is designed to be fixed. The first voltage amplification unit 11 is added with an offset detection circuit, and the second voltage amplification unit 12 is not added with an offset detection circuit.
　切替部１３は、第１シャント抵抗Ｒ１の両端と第１電圧増幅部１１の入力両端の間に挿入される。切替部１３は、第１電圧増幅部１１の入力両端に、第１シャント抵抗Ｒ１の両端電圧を供給するか、第１電圧増幅部１１のオフセット電圧を検出するための電圧を供給するか切り替える。オフセット電圧を検出するための電圧には、例えばグラウンド電位が用いられる。なお第１電圧増幅部１１の入力両端に、同じ電位が供給されればよく、グラウンド電位以外の固定電位が供給されてもよい。切替部１３は、演算部２１からの選択信号に応じて切り替え制御される。図１では切替部１３は２つのＣ接点スイッチで構成される例を描いている。各Ｃ接点スイッチはＭＯＳＦＥＴ、ＩＧＢＴ等の半導体スイッチング素子で構成される。 The switching unit 13 is inserted between both ends of the first shunt resistor R1 and both ends of the input of the first voltage amplifying unit 11. The switching unit 13 switches between supplying the both-ends voltage of the first shunt resistor R <b> 1 or the voltage for detecting the offset voltage of the first voltage amplifying unit 11 to both ends of the input of the first voltage amplifying unit 11. For example, a ground potential is used as a voltage for detecting the offset voltage. Note that the same potential may be supplied to both ends of the input of the first voltage amplification unit 11, or a fixed potential other than the ground potential may be supplied. The switching unit 13 is controlled to be switched according to a selection signal from the calculation unit 21. FIG. 1 illustrates an example in which the switching unit 13 includes two C contact switches. Each C contact switch is composed of a semiconductor switching element such as a MOSFET or IGBT.
　第１電圧増幅部１１は、並列接続された第１増幅器１１ａ及び第２増幅器１１ｂを有する。第１増幅器１１ａは第１シャント抵抗Ｒ１の両端電圧を増幅して切替部２６に出力する。第２増幅器１１ｂも第１シャント抵抗Ｒ１の両端電圧を増幅して切替部２６に出力する。第２電圧増幅部１２の第２ゲインは、第１電圧増幅部１１の第１ゲインより高く設定される。 The first voltage amplifier 11 includes a first amplifier 11a and a second amplifier 11b connected in parallel. The first amplifier 11a amplifies the voltage across the first shunt resistor R1 and outputs the amplified voltage to the switching unit 26. The second amplifier 11b also amplifies the voltage across the first shunt resistor R1 and outputs it to the switching unit 26. The second gain of the second voltage amplifier 12 is set higher than the first gain of the first voltage amplifier 11.
　切替部２６は、第１増幅器１１ａの出力電圧と第２増幅器１１ｂの出力電圧を時分割で選択して第１ＡＤ変換器２７に出力する。第１ＡＤ変換器２７は、入力されたアナログ電圧をデジタル値に変換して演算部２１に出力する。切替部２６は例えば、マルチプレクサで構成される。このように第１増幅器１１ａと第２増幅器１１ｂの出力電圧が切り替えられて第１ＡＤ変換器２７に入力されることにより、第１電圧増幅部１１全体のゲインが可変する構成である。 The switching unit 26 selects the output voltage of the first amplifier 11a and the output voltage of the second amplifier 11b in a time division manner and outputs the selected voltage to the first AD converter 27. The first AD converter 27 converts the input analog voltage into a digital value and outputs the digital value to the calculation unit 21. The switching unit 26 is configured by a multiplexer, for example. In this way, the output voltage of the first amplifier 11a and the second amplifier 11b is switched and input to the first AD converter 27, whereby the gain of the entire first voltage amplifier 11 is variable.
　第２電圧増幅部１２は第３増幅器１２ａを有する。第３増幅器１２ａは第２シャント抵抗Ｒ２の両端電圧を増幅して第２ＡＤ変換器２８に出力する。第２ＡＤ変換器２８は、入力されたアナログ電圧をデジタル値に変換して演算部２１に出力する。第３増幅器１２ａの第３ゲインは、第１増幅器１１ａの第１ゲインと同じ値に設定される。本実施の形態では第１増幅器１１ａの第１ゲインが１０倍、第２増幅器１１ｂの第２ゲインが２０倍、第３増幅器１２ａの第３ゲインが１０倍の例を示している。 The second voltage amplifier 12 has a third amplifier 12a. The third amplifier 12a amplifies the voltage across the second shunt resistor R2 and outputs the amplified voltage to the second AD converter 28. The second AD converter 28 converts the input analog voltage into a digital value and outputs the digital value to the calculation unit 21. The third gain of the third amplifier 12a is set to the same value as the first gain of the first amplifier 11a. In the present embodiment, the first gain of the first amplifier 11a is 10 times, the second gain of the second amplifier 11b is 20 times, and the third gain of the third amplifier 12a is 10 times.
　図２は、図１の第１増幅器１１ａを説明するための図である。図２（ａ）は、第１増幅器１１ａの構成例を示す図である。第１増幅器１１ａは、オペアンプＯＰ１、抵抗Ｒ４、抵抗Ｒ５、抵抗Ｒ６及び抵抗Ｒ７を有し、差動増幅回路を構成している。オペアンプＯＰ１の反転入力端子には、抵抗Ｒ４を介して第１シャント抵抗Ｒ１の一端の電位が入力される。オペアンプＯＰ１の反転入力端子と出力端子は、抵抗Ｒ５を介して接続される。オペアンプＯＰ１の非反転入力端子には、抵抗Ｒ６を介して第１シャント抵抗Ｒ１の他端の電位が入力される。オペアンプＯＰ１の非反転入力端子には、抵抗Ｒ７を介して基準電位Ｖｒが入力される。 FIG. 2 is a diagram for explaining the first amplifier 11a of FIG. FIG. 2A is a diagram illustrating a configuration example of the first amplifier 11a. The first amplifier 11a includes an operational amplifier OP1, a resistor R4, a resistor R5, a resistor R6, and a resistor R7, and constitutes a differential amplifier circuit. The potential of one end of the first shunt resistor R1 is input to the inverting input terminal of the operational amplifier OP1 through the resistor R4. The inverting input terminal and output terminal of the operational amplifier OP1 are connected via a resistor R5. The potential of the other end of the first shunt resistor R1 is input to the non-inverting input terminal of the operational amplifier OP1 through the resistor R6. The reference potential Vr is input to the non-inverting input terminal of the operational amplifier OP1 through the resistor R7.
　図２（ａ）に示す差動増幅回路は、基準電位Ｖｒが０Ｖであれば、入力差動電圧Ｖｄｉｆｆを設定ゲイン（Ｒ５／Ｒ４）で増幅する回路である。本実施の形態では第１ＡＤ変換器２７及び第２ＡＤ変換器２８がマイクロコントローラ２０に内蔵されている。マイクロコントローラ２０に内蔵されているＡＤ変換器は、正の値しか扱えない。一方、二次電池２００は充電と放電があるため、第１増幅器１１ａの出力電圧が負の値になる場合もある。 The differential amplifier circuit shown in FIG. 2A is a circuit that amplifies the input differential voltage Vdiff with a set gain (R5 / R4) when the reference potential Vr is 0V. In the present embodiment, the first AD converter 27 and the second AD converter 28 are built in the microcontroller 20. The AD converter built in the microcontroller 20 can handle only positive values. On the other hand, since the secondary battery 200 is charged and discharged, the output voltage of the first amplifier 11a may be a negative value.
　そこで第１増幅器１１ａの出力電圧が、常に正の値になるようにレベルシフトする。上記の基準電位Ｖｒを、マイクロコントローラ２０の電源電圧の半分の電位に設定すれば、第１増幅器１１ａの出力電圧を常に正の値にできる。本実施の形態ではマイクロコントローラ２０の電源電圧を５Ｖに設定しているため、上記の基準電位Ｖｒを２．５Ｖに設定する。 Therefore, the level shift is performed so that the output voltage of the first amplifier 11a is always a positive value. If the reference potential Vr is set to a half potential of the power supply voltage of the microcontroller 20, the output voltage of the first amplifier 11a can always be a positive value. In this embodiment, since the power supply voltage of the microcontroller 20 is set to 5V, the reference potential Vr is set to 2.5V.
　図２（ｂ）は、図２（ａ）の第１増幅器１１ａの入出力特性を示す図である。ここで、図２（ａ）の第１増幅器１１ａは反転増幅回路となるためゲインＧは負の値として説明を行っている。図２（ｂ）に示すように第１増幅器１１ａの出力電圧が２．５Ｖ、正側にレベルシフトされる。即ち、入力差動電圧Ｖｄｉｆｆが０Ｖのとき出力電圧Ｖｏが２．５Ｖになる。第２増幅器１１ｂと第３増幅器１２ａも、第１増幅器１１ａと同様に構成できる。なお第１ＡＤ変換器２７及び第２ＡＤ変換器２８がマイクロコントローラ２０の外に設けられ、負の値も扱うことができるＡＤ変換器であれば上記の基準電位Ｖｒを０Ｖに設定できる。 FIG. 2 (b) is a diagram showing input / output characteristics of the first amplifier 11a of FIG. 2 (a). Here, since the first amplifier 11a in FIG. 2A is an inverting amplifier circuit, the gain G is described as a negative value. As shown in FIG. 2 (b), the output voltage of the first amplifier 11a is level-shifted to 2.5V and the positive side. That is, when the input differential voltage Vdiff is 0V, the output voltage Vo is 2.5V. The second amplifier 11b and the third amplifier 12a can be configured similarly to the first amplifier 11a. If the first AD converter 27 and the second AD converter 28 are provided outside the microcontroller 20 and can also handle negative values, the reference potential Vr can be set to 0V.
　図１に戻る。演算部２１は電流算出部２２、オフセット算出部２３、オフセット保持部２４及びＳＯＣ算出部２５を含む。演算部２１はハードウェア資源のみ、またはハードウェア資源とソフトウェア資源の協働により実現される。 Return to Figure 1. The calculation unit 21 includes a current calculation unit 22, an offset calculation unit 23, an offset holding unit 24, and an SOC calculation unit 25. The computing unit 21 is realized only by hardware resources or by cooperation of hardware resources and software resources.
　オフセット算出部２３は、切替部１３に選択信号を供給して第１電圧増幅部１１の入力両端にグラウンド電位を供給する。この状態でオフセット算出部２３は、第１電圧増幅部１１の出力電圧からオフセット電圧値を算出する。オフセット電圧Ｖｉｏは下記（式１）により算出できる。 The offset calculation unit 23 supplies a selection signal to the switching unit 13 and supplies a ground potential to both ends of the input of the first voltage amplification unit 11. In this state, the offset calculation unit 23 calculates an offset voltage value from the output voltage of the first voltage amplification unit 11. The offset voltage Vio can be calculated by the following (Equation 1).
　Ｖｉｏ＝（Ｖｍｉｏ－２．５）／Ｇ　・・・（式１）
　Ｖｉｏは第１増幅器１１ａのオフセット電圧、Ｇは第１増幅器１１ａのゲイン、２．５Ｖは上記の基準電位Ｖｒ、Ｖｍｉｏはオフセット電圧値算出時の第１増幅器１１ａの出力電圧をそれぞれ示す。第２増幅器１１ｂのオフセット電圧も同様に算出できる。 Vio = (Vmio−2.5) / G (Formula 1)
Vio represents the offset voltage of the first amplifier 11a, G represents the gain of the first amplifier 11a, 2.5V represents the reference potential Vr, and Vmio represents the output voltage of the first amplifier 11a when calculating the offset voltage value. The offset voltage of the second amplifier 11b can be calculated similarly.
　オフセット算出部２３は、算出した第１増幅器１１ａのオフセット電圧値および第２増幅器１１ｂのオフセット電圧値をオフセット保持部２４に保持する。オフセット算出部２３は上記のオフセット算出を、本電源システム３００が起動する度に実行する。起動後は、図示しない温度センサからの温度値が設定値を超えて変化する度に実行する。オペアンプ及び抵抗には温度特性があるため、温度が変化するとオフセット電圧も変化するためである。 The offset calculation unit 23 holds the calculated offset voltage value of the first amplifier 11a and the calculated offset voltage value of the second amplifier 11b in the offset holding unit 24. The offset calculation unit 23 executes the above offset calculation every time the power supply system 300 is activated. After startup, it is executed whenever the temperature value from a temperature sensor (not shown) changes beyond the set value. This is because the operational amplifier and the resistor have temperature characteristics, so that the offset voltage changes when the temperature changes.
　電流算出部２２は、第１電圧増幅部１１の出力電圧をもとに二次電池２００の電流値を算出する。また電流算出部２２は、第２電圧増幅部１２の出力電圧をもとに二次電池２００の電流値を算出する。第１増幅器１１ａの出力電圧をもとに二次電池２００の電流値を算出する際、電流算出部２２は、オフセット保持部２４に保持される第１増幅器１１ａのオフセット電圧値を用いて第１増幅器１１ａの出力電圧を補正する。同様に第２増幅器１１ｂの出力電圧をもとに二次電池２００の電流値を算出する際、電流算出部２２は、オフセット保持部２４に保持される第２増幅器１１ｂのオフセット電圧値を用いて第２増幅器１１ｂの出力電圧を補正する。 The current calculation unit 22 calculates the current value of the secondary battery 200 based on the output voltage of the first voltage amplification unit 11. The current calculation unit 22 calculates the current value of the secondary battery 200 based on the output voltage of the second voltage amplification unit 12. When calculating the current value of the secondary battery 200 based on the output voltage of the first amplifier 11a, the current calculation unit 22 uses the offset voltage value of the first amplifier 11a held in the offset holding unit 24 to perform the first operation. The output voltage of the amplifier 11a is corrected. Similarly, when calculating the current value of the secondary battery 200 based on the output voltage of the second amplifier 11b, the current calculation unit 22 uses the offset voltage value of the second amplifier 11b held in the offset holding unit 24. The output voltage of the second amplifier 11b is corrected.
　また第３増幅器１２ａの出力電圧をもとに二次電池２００の電流値を算出する際、電流算出部２２は、オフセット保持部２４に保持される第１増幅器１１ａのオフセット電圧値を用いて第３増幅器１２ａの出力電圧を補正する。前提として第１増幅器１１ａと第３増幅器１２ａが同じ仕様で構成されている必要がある。なお両者の仕様が異なる場合、その違いを補正するための補正係数を、第１増幅器１１ａのオフセット電圧値に掛けた値で、第３増幅器１２ａの出力電圧を補正する。 Further, when calculating the current value of the secondary battery 200 based on the output voltage of the third amplifier 12 a, the current calculation unit 22 uses the offset voltage value of the first amplifier 11 a held in the offset holding unit 24. The output voltage of the three amplifier 12a is corrected. As a premise, the first amplifier 11a and the third amplifier 12a need to be configured with the same specifications. If the two specifications are different, the output voltage of the third amplifier 12a is corrected by a value obtained by multiplying the offset voltage value of the first amplifier 11a by a correction coefficient for correcting the difference.
　電流算出部２２は下記（式２）又は（式３）により入力差動電圧Ｖｄｉｆｆを算出し、下記（式４）により電流値Ｉを算出する。 The current calculation unit 22 calculates the input differential voltage Vdiff by the following (Formula 2) or (Formula 3), and calculates the current value I by the following (Formula 4).
　Ｖｄｉｆｆ＝｛（Ｖｏ－２．５）／Ｇ）－Ｖｉｏ　・・・（式２）
　Ｖｄｉｆｆ＝｛（Ｖｏ－２．５）－（Ｖｍｉｏ－２．５）｝／Ｇ　・・・（式３）
　Ｉ＝Ｖｄｉｆｆ／Ｒｓ　・・・（式４）
　Ｒｓはシャント抵抗の抵抗値、Ｖｏは第１増幅器１１ａの出力電圧を示す。 Vdiff = {(Vo−2.5) / G) −Vio (Formula 2)
Vdiff = {(Vo−2.5) − (Vmio−2.5)} / G (Formula 3)
I = Vdiff / Rs (Formula 4)
Rs represents the resistance value of the shunt resistor, and Vo represents the output voltage of the first amplifier 11a.
　ＳＯＣ算出部２５は、電流算出部２２により算出された電流値を積算して二次電池２００のＳＯＣを算出する。ＳＯＣ算出部２５はデフォルト状態では、第１増幅器１１ａの出力電圧をもとに算出された電流値を使用する。第１増幅器１１ａの出力電圧が設定値以上のとき第１増幅器１１ａの出力電圧をもとに二次電池２００のＳＯＣを算出する。第１増幅器１１ａの出力電圧が当該設定値未満のとき第２増幅器１１ｂの出力電圧、または第１増幅器１１ａ及び第２増幅器の出力電圧の平均値を使用する。 The SOC calculation unit 25 calculates the SOC of the secondary battery 200 by integrating the current values calculated by the current calculation unit 22. In the default state, the SOC calculation unit 25 uses a current value calculated based on the output voltage of the first amplifier 11a. When the output voltage of the first amplifier 11a is equal to or higher than the set value, the SOC of the secondary battery 200 is calculated based on the output voltage of the first amplifier 11a. When the output voltage of the first amplifier 11a is less than the set value, the output voltage of the second amplifier 11b or the average value of the output voltages of the first amplifier 11a and the second amplifier is used.
　第１増幅器１１ａと第２増幅器１１ｂを比較すると、後者のほうがゲインが高いので、第１シャント抵抗Ｒ１の両端電圧を高分解能に検出できる。ただし第１シャント抵抗Ｒ１に流れている電流が大きい場合、第２増幅器１１ｂの出力電圧が飽和する可能性がある。従ってデフォルト状態では、入力電圧範囲の広い第１増幅器１１ａの出力電圧を使用する。 When comparing the first amplifier 11a and the second amplifier 11b, the gain of the latter is higher, so that the voltage across the first shunt resistor R1 can be detected with high resolution. However, when the current flowing through the first shunt resistor R1 is large, the output voltage of the second amplifier 11b may be saturated. Therefore, in the default state, the output voltage of the first amplifier 11a having a wide input voltage range is used.
　第１増幅器１１ａの出力電圧が設定値未満の場合、二次電池２００に流れる電流が大きくなく、第２増幅器１１ｂで検出しても出力電圧が飽和しないと判断できる。この場合、より高精度に検出できる第２増幅器１１ｂの出力電圧をもとに電流値を算出する。なお第１増幅器１１ａと第２増幅器１１ｂの出力のバラツキの影響を軽減するため、両者の平均値を用いてもよい。また重み付け平均値を用いてもよい。重み付けする場合、第２増幅器１１ｂの比率を高く設定するとよい。上記の設定値は設計者による実験またはシミュレーションから導くことができる。 When the output voltage of the first amplifier 11a is less than the set value, it can be determined that the current flowing through the secondary battery 200 is not large and the output voltage is not saturated even when detected by the second amplifier 11b. In this case, the current value is calculated based on the output voltage of the second amplifier 11b that can be detected with higher accuracy. In order to reduce the influence of variations in the outputs of the first amplifier 11a and the second amplifier 11b, an average value of both may be used. A weighted average value may be used. In the case of weighting, the ratio of the second amplifier 11b may be set high. The above set values can be derived from experiments or simulations by the designer.
　一方、過電流の検出では、高分解能である必要はなく広い電圧範囲で検出できることが重要である。従ってマイクロコントローラ２０内部の図示しない過電流判定部は、第１増幅器１１ａの出力電圧をもとに算出された電流値、又は第３増幅器１２ａの出力電圧をもとに算出された電流値を使用する。 On the other hand, in overcurrent detection, it is important that detection is possible in a wide voltage range without requiring high resolution. Therefore, an overcurrent determination unit (not shown) inside the microcontroller 20 uses a current value calculated based on the output voltage of the first amplifier 11a or a current value calculated based on the output voltage of the third amplifier 12a. To do.
　マイクロコントローラ２０内部の図示しない異常検出部は、第１増幅器１１ａの出力電圧と第３増幅器１２ａの出力電圧を比較して電源システム３００の異常を検出する。両者の出力電圧は、電源システム３００が正常であれば、ほぼ一致することになる。従って両者の出力電圧に、設定値を超える乖離が発生した場合、いずれかの素子に異常が発生していると判断できる。当該異常検出部は、図示しないＣＡＮ（Controller Area Network）を介して、図示しない車両側のＥＣＵ（Electronic Control Unit）にアラートを通知する。当該ＥＣＵはインストルメントパネルに、電源システム３００の異常を示すランプを点灯させたり、アラームを鳴らして運転者に当該異常を知らせる。 An abnormality detector (not shown) inside the microcontroller 20 detects an abnormality of the power supply system 300 by comparing the output voltage of the first amplifier 11a with the output voltage of the third amplifier 12a. If the power supply system 300 is normal, the output voltages of the two are almost the same. Accordingly, when a deviation exceeding the set value occurs between the output voltages of both, it can be determined that an abnormality has occurred in any of the elements. The abnormality detection unit notifies an alert to an unillustrated ECU (Electronic Control Unit) via a CAN (Controller Area Network) (not shown). The ECU informs the driver of the abnormality by lighting a lamp indicating abnormality of the power supply system 300 on the instrument panel or sounding an alarm.
　第１増幅器１１ａの出力電圧がゼロの場合、第１シャント抵抗Ｒ１から演算部２１の間の経路で短絡が発生した可能性がある。第１増幅器１１ａの出力電圧がゼロの場合も含めて、第１増幅器１１ａの出力電圧が異常値のとき、第１増幅器１１ａの出力電圧ではなく第３増幅器１２ａの出力電圧を、ＳＯＣ算出および過電流検出の両方に使用する。 When the output voltage of the first amplifier 11a is zero, there is a possibility that a short circuit has occurred in the path between the first shunt resistor R1 and the calculation unit 21. Even when the output voltage of the first amplifier 11a is zero, when the output voltage of the first amplifier 11a is an abnormal value, the output voltage of the third amplifier 12a, not the output voltage of the first amplifier 11a, is calculated and exceeded. Used for both current detection.
　以上説明したように実施の形態１では、第１シャント抵抗Ｒ１と第１電圧増幅部１１、第２シャント抵抗Ｒ２と第２電圧増幅部１２を設け、それぞれの組で電流を検出する。これにより、冗長性があり故障に強い電流検出装置１００を実現できる。またメインで使用される第１電圧増幅部１１のゲインを可変構成にすることにより、二次電池２００に流れる電流の大きさに応じて分解能を調整することができ、二次電池に流れる電流を高精度に検出できる。 As described above, in the first embodiment, the first shunt resistor R1 and the first voltage amplifying unit 11, the second shunt resistor R2 and the second voltage amplifying unit 12 are provided, and the current is detected by each set. As a result, it is possible to realize the current detection device 100 that has redundancy and is resistant to failure. Further, by making the gain of the first voltage amplifier 11 used in the main variable, the resolution can be adjusted according to the magnitude of the current flowing through the secondary battery 200, and the current flowing through the secondary battery can be adjusted. It can be detected with high accuracy.
　またサブで使用される第２電圧増幅部１２は、固定ゲインでオフセット検出回路を設けていないためコスト増大を抑制できる。第１電圧増幅部１１のオフセット検出回路で検出したオフセット電圧を用いて、第２電圧増幅部１２の出力電圧も補正することにより第２電圧増幅部１２を低コストで高精度に構成できる。 Moreover, since the second voltage amplifier 12 used in the sub is not provided with an offset detection circuit with a fixed gain, an increase in cost can be suppressed. By correcting the output voltage of the second voltage amplification unit 12 using the offset voltage detected by the offset detection circuit of the first voltage amplification unit 11, the second voltage amplification unit 12 can be configured at low cost and with high accuracy.
　図３は、本発明の実施の形態２に係る電源システム３００の構成を示す図である。実施の形態２では第２増幅器１１ｂを設けずに、第１増幅器１１ａ及び第３増幅器１２ａを設けている。また切替部１３及び切替部２６を設けずに第１増幅器１１ａの出力電圧が直接、第１ＡＤ変換器２７に入力される。負荷４００はモータ・ジェネレータが想定され、二次電池２００から負荷４００（モータモード）へ放電する時の放電電流および負荷４００（発電機モード）から二次電池２００へ充電する時の充電電流を電流検出装置１００で検出する。 FIG. 3 is a diagram showing a configuration of a power supply system 300 according to Embodiment 2 of the present invention. In the second embodiment, the first amplifier 11a and the third amplifier 12a are provided without providing the second amplifier 11b. Further, the output voltage of the first amplifier 11 a is directly input to the first AD converter 27 without providing the switching unit 13 and the switching unit 26. The load 400 is assumed to be a motor / generator, and the discharge current when discharging from the secondary battery 200 to the load 400 (motor mode) and the charging current when charging the secondary battery 200 from the load 400 (generator mode) are currents. Detection is performed by the detection device 100.
　第１増幅器１１ａの反転入力端子は、第１シャント抵抗Ｒ１の一端（低電位側）に接続される。第１増幅器１１ａの非反転入力端子は、第１スイッチＳＷ１を介して第１シャント抵抗Ｒ１の他端（高電位側）または第２シャント抵抗Ｒ２の一端（低電位側）に接続可能な構成である。ここでの高電位側、低電位側の定義は、二次電池２００から負荷４００への放電時のシャント抵抗両端に発生する電圧の向きを指し、この後の説明においても同様の定義とする。 The inverting input terminal of the first amplifier 11a is connected to one end (low potential side) of the first shunt resistor R1. The non-inverting input terminal of the first amplifier 11a can be connected to the other end (high potential side) of the first shunt resistor R1 or one end (low potential side) of the second shunt resistor R2 via the first switch SW1. is there. Here, the definitions of the high potential side and the low potential side indicate the direction of the voltage generated at both ends of the shunt resistor when discharging from the secondary battery 200 to the load 400, and the same definition will be used in the following description.
　第３増幅器１２ａの反転入力端子は、第２シャント抵抗Ｒ２の一端（低電位側）に接続される。第３増幅器１２ａの非反転入力端子は、第２スイッチＳＷ２を介して第２シャント抵抗Ｒ２の他端（高電位側）または第１シャント抵抗Ｒ１の他端（高電位側）に接続可能な構成である。 The inverting input terminal of the third amplifier 12a is connected to one end (low potential side) of the second shunt resistor R2. The non-inverting input terminal of the third amplifier 12a can be connected to the other end (high potential side) of the second shunt resistor R2 or the other end (high potential side) of the first shunt resistor R1 via the second switch SW2. It is.
　実施の形態２でも第１増幅器１１ａと第３増幅器１２ａの２つの検出回路が設けられるため冗長化が可能である。即ち、いずれかが故障した場合、どちらかのみで電流検出が可能である。 Also in the second embodiment, since the two detection circuits of the first amplifier 11a and the third amplifier 12a are provided, redundancy is possible. In other words, when one of them fails, current detection is possible only with either one.
　以下、二次電池２００から負荷４００に２００Ａの電流が放電されている状態を例に説明する。上記のように第１シャント抵抗Ｒ１及び第２シャント抵抗Ｒ２の抵抗値は１ｍΩであるため、第１シャント抵抗Ｒ１及び第２シャント抵抗Ｒ２の両端電圧は、それぞれ２００ｍＶである。また上記のように第１増幅器１１ａ及び第３増幅器１２ａのゲインは、１０倍とし、２．５Ｖレベルシフトさせているとする。 Hereinafter, a state in which a current of 200 A is discharged from the secondary battery 200 to the load 400 will be described as an example. As described above, since the resistance values of the first shunt resistor R1 and the second shunt resistor R2 are 1 mΩ, the voltage across the first shunt resistor R1 and the second shunt resistor R2 is 200 mV, respectively. Further, as described above, it is assumed that the gains of the first amplifier 11a and the third amplifier 12a are 10 times and are shifted by 2.5V level.
　まずオフセット電圧Ｖｉｏがゼロの場合を考える。第１増幅器１１ａの非反転入力端子が第１シャント抵抗Ｒ１の他端（高電位側）に接続されている状態では、第１増幅器１１ａの出力電圧Ｖｏ１は４．５Ｖとなる。第１増幅器１１ａの非反転入力端子が第２シャント抵抗Ｒ２の一端（低電位側）に接続されている状態では、第１増幅器１１ａの出力電圧Ｖｏ２は０．５Ｖとなる。 First, consider the case where the offset voltage Vio is zero. When the non-inverting input terminal of the first amplifier 11a is connected to the other end (high potential side) of the first shunt resistor R1, the output voltage Vo1 of the first amplifier 11a is 4.5V. When the non-inverting input terminal of the first amplifier 11a is connected to one end (low potential side) of the second shunt resistor R2, the output voltage Vo2 of the first amplifier 11a is 0.5V.
　次にオフセット電圧Ｖｉｏが１００ｍＶの場合を考える。第１増幅器１１ａの非反転入力端子が第１シャント抵抗Ｒ１の他端（高電位側）に接続されている状態では、第１増幅器１１ａの出力電圧Ｖｏ１は４．６Ｖとなる。第１増幅器１１ａの非反転入力端子が第２シャント抵抗Ｒ２の一端（低電位側）に接続されている状態では、第１増幅器１１ａの出力電圧Ｖｏ２は０．６Ｖとなる。 Next, consider the case where the offset voltage Vio is 100 mV. In a state where the non-inverting input terminal of the first amplifier 11a is connected to the other end (high potential side) of the first shunt resistor R1, the output voltage Vo1 of the first amplifier 11a is 4.6V. In a state where the non-inverting input terminal of the first amplifier 11a is connected to one end (low potential side) of the second shunt resistor R2, the output voltage Vo2 of the first amplifier 11a is 0.6V.
　第１増幅器１１ａの出力電圧Ｖｏ１及び出力電圧Ｖｏ２は下記（式５）、下記（式６）により算出され、第１増幅器１１ａのオフセット電圧Ｖｉｏは下記（式７）により算出され、第１増幅器１１ａのレベルシフト前の出力電圧（真値）Ｖｔは下記（式８）により算出される。 The output voltage Vo1 and the output voltage Vo2 of the first amplifier 11a are calculated by the following (formula 5) and the following (formula 6), the offset voltage Vio of the first amplifier 11a is calculated by the following (formula 7), and the first amplifier 11a The output voltage (true value) Vt before the level shift is calculated by the following (formula 8).
　Ｖｏ１＝２．５＋Ｖｔ＋Ｖｉｏ　・・・（式５）
　Ｖｏ２＝２．５－Ｖｔ＋Ｖｉｏ　・・・（式６）
　Ｖｉｏ＝（Ｖｏ１＋Ｖｏ２－２．５×２）／２　・・・（式７）
　Ｖｔ＝（Ｖｏ１－Ｖｏ２）／２　・・・（式８）
　２．５Ｖは電圧シフト分、Ｖｔはシフト前の真値、Ｖｉｏはオフセット電圧をそれぞれ示す。 Vo1 = 2.5 + Vt + Vio (Formula 5)
Vo2 = 2.5−Vt + Vio (Expression 6)
Vio = (Vo1 + Vo2-2.5 × 2) / 2 (Expression 7)
Vt = (Vo1-Vo2) / 2 (Expression 8)
2.5V represents the voltage shift, Vt represents the true value before the shift, and Vio represents the offset voltage.
　（式５）～（式８）から分かるように、第１増幅器１１ａの出力電圧Ｖｏ１及び出力電圧Ｖｏ２から真値Ｖｔを算出でき、真値Ｖｔが算出できるとオフセット電圧Ｖｉｏを算出できる。上記の例のように、第１増幅器１１ａの出力電圧Ｖｏ１が４．６Ｖ、出力電圧Ｖｏ２が０．６Ｖの場合、真値Ｖｔが２．０Ｖとなり、オフセット電圧Ｖｉｏが１００ｍＶとなる。このように第１増幅器１１ａの両端電位にグラウンド電位を供給しなくても、第１増幅器１１ａのオフセット電圧を検出できる。なお（式８）を使用すれば、オフセット電圧Ｖｉｏを計算しなくても、第１増幅器１１ａの出力電圧Ｖｏ１及び出力電圧Ｖｏ２から直接、真値Ｖｔを計算することができる。 As can be seen from (Equation 5) to (Equation 8), the true value Vt can be calculated from the output voltage Vo1 and the output voltage Vo2 of the first amplifier 11a, and the offset voltage Vio can be calculated if the true value Vt can be calculated. As in the above example, when the output voltage Vo1 of the first amplifier 11a is 4.6V and the output voltage Vo2 is 0.6V, the true value Vt is 2.0V and the offset voltage Vio is 100mV. In this way, the offset voltage of the first amplifier 11a can be detected without supplying the ground potential to the both-end potential of the first amplifier 11a. If (Equation 8) is used, the true value Vt can be calculated directly from the output voltage Vo1 and the output voltage Vo2 of the first amplifier 11a without calculating the offset voltage Vio.
　次に分解能の切替について説明する。以下の説明では、オフセット電圧Ｖｉｏはゼロとする。まず二次電池２００から負荷４００に１００Ａの電流が放電されている状態を考える。第２シャント抵抗Ｒ２の両端電圧は１００ｍＶ、第１シャント抵抗Ｒ１及び第２シャント抵抗Ｒ２を直列接続した抵抗の両端電圧は２００ｍＶになる。 Next, resolution switching will be described. In the following description, the offset voltage Vio is zero. First, a state in which a current of 100 A is discharged from the secondary battery 200 to the load 400 will be considered. The voltage across the second shunt resistor R2 is 100 mV, and the voltage across the resistor in which the first shunt resistor R1 and the second shunt resistor R2 are connected in series is 200 mV.
　第３増幅器１２ａの非反転入力端子が第２シャント抵抗Ｒ２の他端（高電位側）に接続されている状態では、第３増幅器１２ａの出力電圧Ｖｏ１は３．５Ｖとなる。第３増幅器１２ａの非反転入力端子が第１シャント抵抗Ｒ１の他端（高電位側）に接続されている状態では、第３増幅器１２ａの出力電圧Ｖｏ２は４．５Ｖとなる。いずれの値も０～５Ｖの範囲に収まるため、より分解能の高い出力電圧Ｖｏ２を使用する。出力電圧Ｖｏ２を選択する場合は抵抗値が倍になるため、ゲインが２倍の状態（×２０）と実質的に同じ状態になる。 In a state where the non-inverting input terminal of the third amplifier 12a is connected to the other end (high potential side) of the second shunt resistor R2, the output voltage Vo1 of the third amplifier 12a is 3.5V. When the non-inverting input terminal of the third amplifier 12a is connected to the other end (high potential side) of the first shunt resistor R1, the output voltage Vo2 of the third amplifier 12a is 4.5V. Since any value falls within the range of 0 to 5V, the output voltage Vo2 with higher resolution is used. When the output voltage Vo2 is selected, the resistance value is doubled, so that the state is substantially the same as the doubled state (× 20).
　次に二次電池２００から負荷４００に２００Ａの電流が放電されている状態を考える。第２シャント抵抗Ｒ２の両端電圧は２００ｍＶ、第１シャント抵抗Ｒ１及び第２シャント抵抗Ｒ２を直列接続した抵抗の両端電圧は４００ｍＶになる。 Next, a state in which a current of 200 A is discharged from the secondary battery 200 to the load 400 will be considered. The voltage across the second shunt resistor R2 is 200 mV, and the voltage across the resistor in which the first shunt resistor R1 and the second shunt resistor R2 are connected in series is 400 mV.
　第３増幅器１２ａの非反転入力端子が第２シャント抵抗Ｒ２の他端（高電位側）に接続されている状態では、第３増幅器１２ａの出力電圧Ｖｏ１は４．５Ｖとなる。第３増幅器１２ａの非反転入力端子が第１シャント抵抗Ｒ１の他端（高電位側）に接続されている状態では、第３増幅器１２ａの出力電圧Ｖｏ２は６．５Ｖとなる。出力電圧Ｖｏ２の値が０～５Ｖの範囲を超えるため、出力電圧Ｖｏ１を使用する。 In a state where the non-inverting input terminal of the third amplifier 12a is connected to the other end (high potential side) of the second shunt resistor R2, the output voltage Vo1 of the third amplifier 12a is 4.5V. When the non-inverting input terminal of the third amplifier 12a is connected to the other end (high potential side) of the first shunt resistor R1, the output voltage Vo2 of the third amplifier 12a is 6.5V. Since the value of the output voltage Vo2 exceeds the range of 0 to 5V, the output voltage Vo1 is used.
　以上説明したように実施の形態２によれば、第１スイッチＳＷ１及び第２スイッチＳＷ２を設けて、第１増幅器１１ａ及び第３増幅器１２ａに入力される電位を切り替えることにより、実施の形態１と同様の効果を奏する。 As described above, according to the second embodiment, the first switch SW1 and the second switch SW2 are provided, and the potentials input to the first amplifier 11a and the third amplifier 12a are switched, so that The same effect is produced.
　図４は、本発明の実施の形態３に係る電源システム３００の構成を示す図である。実施３の形態では第２増幅器１１ｂ及び第３増幅器１２ａを設けずに、第１増幅器１１ａのみ設けている。また切替部１３及び切替部２６を設けずに第１増幅器１１ａの出力電圧が直接、第１ＡＤ変換器２７に入力される。第２ＡＤ変換器２８は設けていない。また第１シャント抵抗Ｒ１、第２シャント抵抗Ｒ２と直列に第３シャント抵抗Ｒ３を接続している。第３シャント抵抗Ｒ３の抵抗値も１ｍΩである。 FIG. 4 is a diagram showing a configuration of a power supply system 300 according to Embodiment 3 of the present invention. In the third embodiment, only the first amplifier 11a is provided without providing the second amplifier 11b and the third amplifier 12a. Further, the output voltage of the first amplifier 11 a is directly input to the first AD converter 27 without providing the switching unit 13 and the switching unit 26. The second AD converter 28 is not provided. A third shunt resistor R3 is connected in series with the first shunt resistor R1 and the second shunt resistor R2. The resistance value of the third shunt resistor R3 is also 1 mΩ.
　第１増幅器１１ａの反転入力端子は、第２シャント抵抗Ｒ２の一端（低電位側）に接続される。第１増幅器１１ａの非反転入力端子は、第３スイッチＳＷ３を介して第２シャント抵抗Ｒ２の他端（高電位側）、第３シャント抵抗Ｒ３の一端（低電位側）、または第１シャント抵抗Ｒ１の他端（高電位側）に接続可能な構成である。 The inverting input terminal of the first amplifier 11a is connected to one end (low potential side) of the second shunt resistor R2. The non-inverting input terminal of the first amplifier 11a is connected to the other end (high potential side) of the second shunt resistor R2, one end (low potential side) of the third shunt resistor R3, or the first shunt resistor via the third switch SW3. This is a configuration connectable to the other end (high potential side) of R1.
　第１増幅器１１ａの非反転入力端子が第２シャント抵抗Ｒ２の他端（高電位側）に接続される状態と、第３シャント抵抗Ｒ３の一端（低電位側）に接続される状態の組み合わせは、実施の形態２において第１増幅器１１ａの非反転入力端子が第１シャント抵抗Ｒ１の他端（高電位側）に接続される状態と、第２シャント抵抗Ｒ２の一端（低電位側）に接続される状態の組み合わせと、同じ状況である。従ってオフセット電圧の検出が可能である。 The combination of the state where the non-inverting input terminal of the first amplifier 11a is connected to the other end (high potential side) of the second shunt resistor R2 and the state where it is connected to one end (low potential side) of the third shunt resistor R3 is In the second embodiment, the non-inverting input terminal of the first amplifier 11a is connected to the other end (high potential side) of the first shunt resistor R1, and is connected to one end (low potential side) of the second shunt resistor R2. The situation is the same as the combination of states to be performed. Therefore, the offset voltage can be detected.
　また第１増幅器１１ａの非反転入力端子が第２シャント抵抗Ｒ２の他端（高電位側）に接続される状態と、第１シャント抵抗Ｒ１の一端（高電位側）に接続される状態の組み合わせは、実施の形態２において第３増幅器１２ａの非反転入力端子が第２シャント抵抗Ｒ２の他端（高電位側）に接続される状態と、第１シャント抵抗Ｒ１の他端（高電位側）に接続される状態の組み合わせと、同じ状況である。従って分解能の切替も可能である。 Further, a combination of a state where the non-inverting input terminal of the first amplifier 11a is connected to the other end (high potential side) of the second shunt resistor R2 and a state where it is connected to one end (high potential side) of the first shunt resistor R1. In the second embodiment, the non-inverting input terminal of the third amplifier 12a is connected to the other end (high potential side) of the second shunt resistor R2, and the other end (high potential side) of the first shunt resistor R1. It is the same situation as the combination of the states connected to. Therefore, the resolution can be switched.
　図５は、本発明の実施の形態４に係る電源システム３００の構成を示す図である。実施４の形態でも第２増幅器１１ｂ及び第３増幅器１２ａを設けずに、第１増幅器１１ａのみ設けている。また切替部１３及び切替部２６を設けずに第１増幅器１１ａの出力電圧が直接、第１ＡＤ変換器２７に入力される。第２ＡＤ変換器２８は設けていない。 FIG. 5 is a diagram showing a configuration of a power supply system 300 according to Embodiment 4 of the present invention. In the fourth embodiment, only the first amplifier 11a is provided without providing the second amplifier 11b and the third amplifier 12a. Further, the output voltage of the first amplifier 11 a is directly input to the first AD converter 27 without providing the switching unit 13 and the switching unit 26. The second AD converter 28 is not provided.
　第１増幅器１１ａの反転入力端子は、第２スイッチＳＷ２を介して第２シャント抵抗Ｒ２の一端（低電位側）、または第２シャント抵抗Ｒ２の他端（高電位側）に接続可能な構成である。第１増幅器１１ａの非反転入力端子は、第１スイッチＳＷ１を介して第２シャント抵抗Ｒ２の一端（低電位側）、または第１シャント抵抗Ｒ１の他端（高電位側）に接続可能な構成である。 The inverting input terminal of the first amplifier 11a can be connected to one end (low potential side) of the second shunt resistor R2 or the other end (high potential side) of the second shunt resistor R2 via the second switch SW2. is there. The non-inverting input terminal of the first amplifier 11a can be connected to one end (low potential side) of the second shunt resistor R2 or the other end (high potential side) of the first shunt resistor R1 via the first switch SW1. It is.
　第１増幅器１１ａの反転入力端子が第２シャント抵抗Ｒ２の他端（高電位側）に接続され（固定）、かつ第１増幅器１１ａの非反転入力端子が第１シャント抵抗Ｒ１の他端（高電位側）に接続される状態と、第２シャント抵抗Ｒ２の一端（低電位側）に接続される状態の組み合わせは、実施の形態２において第１増幅器１１ａの非反転入力端子が第１シャント抵抗Ｒ１の他端（高電位側）に接続される状態と、第２シャント抵抗Ｒ２の一端（低電位側）に接続される状態の組み合わせと、同じ状況である。従ってオフセット電圧の検出が可能である。 The inverting input terminal of the first amplifier 11a is connected (fixed) to the other end (high potential side) of the second shunt resistor R2, and the non-inverting input terminal of the first amplifier 11a is the other end (high) of the first shunt resistor R1. Combination of the state connected to the potential side) and the state connected to one end (low potential side) of the second shunt resistor R2 in the second embodiment, the non-inverting input terminal of the first amplifier 11a is connected to the first shunt resistor. The combination of the state connected to the other end (high potential side) of R1 and the state connected to one end (low potential side) of the second shunt resistor R2 is the same situation. Therefore, the offset voltage can be detected.
　また第１増幅器１１ａの非反転入力端子が第１シャント抵抗Ｒ１の他端（高電位側）に接続され（固定）、かつ第１増幅器１１ａの反転入力端子が第２シャント抵抗Ｒ２の他端（高電位側）に接続される状態と、第２シャント抵抗Ｒ２の一端（低電位側）に接続される状態の組み合わせは、実施の形態２において第３増幅器１２ａの非反転入力端子が第２シャント抵抗Ｒ２の他端（高電位側）に接続される状態と、第１シャント抵抗Ｒ１の他端（高電位側）に接続される状態の組み合わせと、同じ状況である。従って分解能の切替も可能である。 The non-inverting input terminal of the first amplifier 11a is connected (fixed) to the other end (high potential side) of the first shunt resistor R1, and the inverting input terminal of the first amplifier 11a is connected to the other end of the second shunt resistor R2. The combination of the state connected to the high potential side) and the state connected to one end (low potential side) of the second shunt resistor R2 is the same as that of the second shunt of the third amplifier 12a in the second embodiment. The combination of the state connected to the other end (high potential side) of the resistor R2 and the state connected to the other end (high potential side) of the first shunt resistor R1 is the same situation. Therefore, the resolution can be switched.
　以上、本発明を実施の形態をもとに説明した。実施の形態は例示であり、それらの各構成要素や各処理プロセスの組み合わせにいろいろな変形例が可能なこと、またそうした変形例も本発明の範囲にあることは当業者に理解されるところである。 The present invention has been described based on the embodiments. The embodiments are exemplifications, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are within the scope of the present invention. .
　例えば実施の形態１では第１増幅器１１ａの第１ゲインと第３増幅器１２ａの第３ゲインを同じ値に設定した。この点、第３ゲインを第１ゲインより小さい値（例えば、８倍）に設定してもよい。これにより第３増幅器１２ａでは、第１増幅器１１ａより広範囲の電流を検出できるようになる。その代わり、第１電圧増幅部１１がダウンして第３増幅器１２ａの出力電圧からＳＯＣを算出する場合、分解能が低い電圧をもとにＳＯＣを算出することになる。設計者は、このトレードオフ関係を考慮して、第１増幅器１１ａの第１ゲインと第３増幅器１２ａの第３ゲインを設定する。 For example, in the first embodiment, the first gain of the first amplifier 11a and the third gain of the third amplifier 12a are set to the same value. In this regard, the third gain may be set to a value (for example, 8 times) smaller than the first gain. As a result, the third amplifier 12a can detect a wider range of current than the first amplifier 11a. Instead, when the first voltage amplifying unit 11 goes down and calculates the SOC from the output voltage of the third amplifier 12a, the SOC is calculated based on a voltage with low resolution. The designer sets the first gain of the first amplifier 11a and the third gain of the third amplifier 12a in consideration of this trade-off relationship.
　また上記の実施の形態１－４では、電流検出装置１００又はそれを備える電源システム３００を車載用途に適用する例を説明したが、電流検出装置１００又はそれを備える電源システム３００を、家庭用や産業用等の蓄電システムに適用することも可能である。 Further, in the above Embodiment 1-4, the example in which the current detection device 100 or the power supply system 300 including the current detection device 100 is applied to an in-vehicle use has been described. It is also possible to apply to an industrial power storage system.
　１００　電流検出装置、　２００　二次電池、　３００　電源システム、　４００　負荷、　Ｒ１　第１シャント抵抗、　Ｒ２　第２シャント抵抗、　Ｒ３　第３シャント抵抗、　１０　電流計測部、　１１　第１電圧増幅部、　１１ａ　第１増幅器、　１１ｂ　第２増幅器、　１２　第２電圧増幅部、　１２ａ　第３増幅器、　１３　切替部、　２０　マイクロコントローラ、　２１　演算部、　２２　電流算出部、　２３　オフセット算出部、　２４　オフセット保持部、　２５　ＳＯＣ算出部、　２６　切替部、　２７　第１ＡＤ変換器、　２８　第２ＡＤ変換器、　ＯＰ　オペアンプ、　Ｒ４，Ｒ５，Ｒ６，Ｒ７　抵抗、　Ｖｒ　基準電圧、　ＳＷ１　第１スイッチ、　ＳＷ２　第２スイッチ、　ＳＷ３　第３スイッチ。 100 current detection device, 200 secondary battery, 300 power supply system, 400 load, R1 first shunt resistor, R2 second shunt resistor, R3 third shunt resistor, 10 current measurement unit, 11 first voltage amplification unit, 11a first Amplifier, 11b second amplifier, 12 second voltage amplification unit, 12a third amplifier, 13 switching unit, 20 microcontroller, 21 operation unit, 22 current calculation unit, 23 offset calculation unit, 24 offset holding unit, 25 SOC calculation unit , 26 switching unit, 27 first AD converter, 28 second AD converter, OP operational amplifier, R4, R5, R6, R7 resistance, Vr reference voltage, SW1 first switch, SW2 second switch, SW3 third switch.

Claims (7)

  1. 　二次電池に直列接続された第１電流検出素子の両端電圧を増幅する第１電圧増幅部と、
    　前記第１電流検出素子の両端と前記第１電圧増幅部の入力両端の間に挿入され、前記第１電圧増幅部の入力両端に、前記第１電流検出素子の両端電圧を供給するか、前記第１電圧増幅部のオフセット電圧を検出するための電圧を供給するか切り替える切替部と、
    　前記二次電池および前記第１電流検出素子に直列接続された第２電流検出素子の両端電圧を増幅する第２電圧増幅部と、
    　前記第１電圧増幅部のゲインは可変であり、前記第２電圧増幅部のゲインは固定であり、
    　前記第１電圧増幅部の出力電圧は、前記二次電池のＳＯＣ（State Of Charge）算出に使用され、前記第２電圧増幅部の出力電圧は、前記二次電池の過電流検出に使用されることを特徴とする電流検出装置。     A first voltage amplification unit that amplifies the voltage across the first current detection element connected in series to the secondary battery;
    Inserted between both ends of the first current detecting element and both ends of the input of the first voltage amplifying unit, and supplies both ends of the voltage of the first current detecting element to both ends of the input of the first voltage amplifying unit; A switching unit for switching whether to supply a voltage for detecting the offset voltage of the first voltage amplification unit;
    A second voltage amplification unit that amplifies the voltage across the second battery and the second current detection element connected in series to the first current detection element;
    The gain of the first voltage amplification unit is variable, and the gain of the second voltage amplification unit is fixed,
    The output voltage of the first voltage amplifier is used for calculating the SOC (State Of Charge) of the secondary battery, and the output voltage of the second voltage amplifier is used for detecting the overcurrent of the secondary battery. A current detection device characterized by that.
  2. 　前記第１電圧増幅部の出力電圧をもとに前記二次電池の電流値を算出するとともに、前記第２電圧増幅部の出力電圧をもとに前記二次電池の電流値を算出する演算部と、をさらに備え、
    　前記演算部は、前記第１電圧増幅部の入力両端に前記オフセット電圧を検出するための電圧が供給されている状態で、前記第１電圧増幅部の出力電圧からオフセット電圧値を算出して保持し、前記オフセット電圧値を用いて前記第１電圧増幅部の出力電圧および前記第２電圧増幅部の出力電圧の両方を補正することを特徴とする請求項１に記載の電流検出装置。     An arithmetic unit that calculates the current value of the secondary battery based on the output voltage of the first voltage amplifier, and calculates the current value of the secondary battery based on the output voltage of the second voltage amplifier. And further comprising
    The calculation unit calculates and holds an offset voltage value from the output voltage of the first voltage amplification unit in a state where a voltage for detecting the offset voltage is supplied to both ends of the input of the first voltage amplification unit. The current detection device according to claim 1, wherein both the output voltage of the first voltage amplification unit and the output voltage of the second voltage amplification unit are corrected using the offset voltage value.
  3. 　前記第１電圧増幅部は、
    　第１ゲインが設定された第１増幅器と、
    　前記第１増幅器と並列接続され、前記第１ゲインより高い第２ゲインが設定された第２増幅器と、を有し、
    　前記演算部は、前記第１増幅器の出力電圧が設定値以上のとき前記第１増幅器の出力電圧をもとに前記二次電池のＳＯＣを算出し、前記第１増幅器の出力電圧が前記設定値未満のとき前記第２増幅器の出力電圧、または前記第１増幅器および前記第２増幅器の出力電圧の平均をもとに前記二次電池のＳＯＣを算出することを特徴とする請求項２に記載の電流検出装置。     The first voltage amplification unit includes:
    A first amplifier with a first gain set;
    A second amplifier connected in parallel with the first amplifier and set with a second gain higher than the first gain;
    The computing unit calculates the SOC of the secondary battery based on the output voltage of the first amplifier when the output voltage of the first amplifier is equal to or higher than a set value, and the output voltage of the first amplifier is the set value. 3. The SOC of the secondary battery is calculated based on an output voltage of the second amplifier or an average of the output voltages of the first amplifier and the second amplifier when the value is less than the value. Current detection device.
  4. 　前記第２電圧増幅部は、
    　第３ゲインが設定された第３増幅器を有し、
    　前記第１ゲインと前記第３ゲインが同じ値に設定されることを特徴とする請求項３に記載の電流検出装置。     The second voltage amplification unit includes:
    A third amplifier having a third gain set;
    The current detection device according to claim 3, wherein the first gain and the third gain are set to the same value.
  5. 　前記演算部は、前記第１増幅器の出力電圧と前記第３増幅器の出力電圧を比較して、本電流検出装置の異常を検出することを特徴とする請求項４に記載の電流検出装置。 The current detection device according to claim 4, wherein the arithmetic unit detects an abnormality of the current detection device by comparing an output voltage of the first amplifier and an output voltage of the third amplifier.
  6. 　前記第２電圧増幅部は、
    　第３ゲインが設定された第３増幅器を有し、
    　前記第３ゲインは、前記第１ゲインより小さな値に設定されることを特徴とする請求項３に記載の電流検出装置。     The second voltage amplification unit includes:
    A third amplifier having a third gain set;
    The current detection device according to claim 3, wherein the third gain is set to a value smaller than the first gain.
  7. 　前記二次電池と、
    　請求項１から６のいずれかに記載の電流検出装置と、
    　を備えることを特徴とする電源システム。     The secondary battery;
    The current detection device according to any one of claims 1 to 6,
    A power supply system comprising:
PCT/JP2014/004967 2014-03-28 2014-09-29 Current detection apparatus and power supply system WO2015145496A1 (en)

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