Current measurement-use semiconductor device

Abstract

A current measurement-use semiconductor device (30) is for measuring the current which flows through a shunt resistor (4) provided in a measurement target device (3), and comprises: a first current measurement circuit (10) that measures the current flowing through the shunt resistor (4) by detecting voltage at both ends of the shunt resistor (4); and a second current measurement circuit (20) that has a coreless magnetic sensor (50) and measures the current flowing through the shunt resistor (4) by using the coreless magnetic sensor (50).

Description

Current measuring semiconductor device

[0001] The present invention relates to a semiconductor device for current measurement, and more particularly to a semiconductor device for current measurement that measures a current flowing through a shunt resistor provided in a device to be measured.

[0002] Conventionally, current measurement circuits with magnetic cores (hereinafter referred to as "core magnetic sensors") have been widely used to measure the current of lithium-ion batteries installed in electric vehicles. However, while the core magnetic sensor method is capable of measuring small currents, it is difficult to ensure a wide dynamic range from small to large currents due to hysteresis and magnetic saturation caused by the magnetic core. The current measurement accuracy of core magnetic sensors is generally around ±1%.

[0003] On the other hand, coreless magnetic sensors, which do not have a magnetic core, are free from magnetic saturation due to the magnetic core and can measure in larger current ranges, but they have the problem of being unable to perform high-precision measurements due to external noise and installation location. As a result, adjustments are required after installation, and they are rarely used to measure current in lithium-ion batteries.

[0004] In recent years, with the improvement in electric vehicle performance, lithium-ion battery current measurement has become necessary not only for current measurement of approximately 10 mA to 100 mA when the vehicle is stopped, but also for measurement of a maximum current range of approximately 1,000 A to 2,000 A. Furthermore, in order to calculate the lithium-ion battery capacity (SOC: State of Charge) with high precision, a current measurement accuracy of approximately ±0.1% is required in coulomb counting by current measurement.

[0005] For this reason, current measurement for electric vehicles is being replaced from the core magnetic sensor method to a current measurement circuit using a shunt resistor (hereinafter referred to as the shunt current method).

[0006] However, the shunt current method has the problem that, in principle, if a short-circuit mode failure occurs in the shunt resistor through which the battery current directly flows, the measured current value appears small, making it impossible to detect the abnormality. In other words, a short-circuit mode failure in the shunt current method cannot detect overcurrent in the dangerous range that could lead to the lithium-ion battery ignition or explosion, and it cannot be said to achieve fail-safe. For this reason, functional safety measures such as installing multiple current measurement circuits using shunt resistors to provide redundancy are essential.

[0007] Therefore, a method has been proposed in the past in which two shunt resistors with different resistance values ​​are connected in series to provide redundancy, thereby preventing common cause failures (see Patent Document 1).

[0008] International Publication No. 2016-047010

[0009] However, as in Patent Document 1, in the case of redundancy using the same technology, namely shunt resistors, even though their resistance values ​​are different, it is difficult to say that the possibility of common cause failures occurring simultaneously in the same failure mode due to overcurrent flowing through the battery can be ruled out.

[0010] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a current measuring semiconductor device that measures a current flowing through a shunt resistor and that suppresses common cause failures.

[0011] In order to achieve the above-mentioned object, a current measuring semiconductor device according to one embodiment of the present invention is a current measuring semiconductor device that measures the current flowing through a shunt resistor provided in a device to be measured, and includes a first current measuring circuit that measures the current flowing through the shunt resistor by detecting the voltage across the shunt resistor, and a second current measuring circuit that has a coreless magnetic sensor and measures the current flowing through the shunt resistor using the coreless magnetic sensor.

[0012] The present invention provides a current measuring semiconductor device that measures a current flowing through a shunt resistor, in which common cause failures are suppressed.

[0013] FIG. 1 is a circuit block diagram showing the configuration of a current measurement semiconductor device according to an embodiment. FIG. 2A is an external view showing an example implementation of the current measurement semiconductor device according to the embodiment. FIG. 2B is a diagram showing an example layout of major circuit elements in the current measurement semiconductor device according to the embodiment. FIG. 3 is a diagram explaining the current-voltage characteristics of a shunt resistor included in a device to be measured and a coreless magnetic sensor included in the current measurement semiconductor device, and correction in the current measurement semiconductor device. FIG. 4 is a flowchart showing the operation of the current measurement semiconductor device according to the embodiment. FIG. 5 is a flowchart showing the operation of detecting an abnormality in a shunt resistor by the current measurement semiconductor device according to the embodiment. FIG. 6 is a flowchart showing the operation of detecting an abnormality in a device to be measured by the current measurement semiconductor device according to the embodiment.

[0014] (Summary and Effects of the Invention) In one embodiment of the present invention, a coreless magnetic sensor is mounted on a current measurement semiconductor device (hereinafter simply referred to as a "semiconductor device") that measures the current flowing through a shunt resistor, thereby realizing a coreless current sensor circuit, which makes it possible to realize a redundant current measurement circuit in which common cause failures are suppressed.

[0015] More specifically, in one embodiment of the present invention, in the high current region where the shunt resistor cannot detect, a second current measurement circuit is used that measures the current using a coreless magnetic sensor. That is, in the low current region where the coreless magnetic sensor circuit cannot measure, a magnetic sensor dead zone is set, and the measurement value of the second current measurement circuit in the magnetic sensor dead zone is ignored (i.e., only the measurement value using the shunt resistor is used).

[0016] In addition, in order to correct the temperature dependence of the coreless magnetic sensor and the shunt resistor, the semiconductor device is provided with a temperature measurement circuit for the coreless magnetic sensor and the shunt resistor, making it possible to correct the temperature dependence of the first current measurement circuit and the second current measurement circuit.

[0017] Generally, coreless magnetic sensors are composed only of semiconductor devices, making them very small and easy to install. However, the magnetic flux density generated by a flowing current varies depending on the distance between the magnetic sensor and the wiring under test, such as a bus bar, and on external noise. Therefore, in order to use coreless magnetic sensors to measure absolute current values, calibration after installation is essential. Furthermore, detecting minute currents is difficult, making them rarely used for measuring current in lithium-ion batteries.

[0018] Therefore, in the present invention, by providing a first current measurement circuit that measures current using a shunt resistor and a second current measurement circuit that measures current using a coreless magnetic sensor in the same semiconductor device, it is possible to correct the second current measurement circuit that measures current using a magnetic sensor using the measurement value of the first current measurement circuit that measures current using a shunt resistor.

[0019] Furthermore, the main cause of short-circuit mode failure in shunt resistors is the flow of a large current, and the situation in which a lithium-ion battery catches fire or explodes is also one in which a large current (overcurrent) is flowing.

[0020] Therefore, even with a coreless magnetic sensor, which has difficulty detecting minute currents, it is possible to detect a short-mode failure of the shunt resistor by comparing the measurement value of a first current measurement circuit that measures the current using a shunt resistor with the measurement value of a second current measurement circuit that measures the current using a coreless magnetic sensor only during periods when a large current is flowing.

[0021] Furthermore, since the semiconductor device of the present invention, which is equipped with a current measurement circuit that measures current using a shunt resistor, is installed in close proximity to the shunt resistor, the coreless magnetic sensor on the semiconductor device can be installed in an optimal location for detecting the magnetic flux generated by the current flowing through the shunt resistor.

[0022] Furthermore, since a temperature measurement circuit can be easily installed in the semiconductor device according to the present invention, it is easy to correct the temperature dependence of the coreless magnetic sensor on the semiconductor device and the shunt resistance on the device to be measured.

[0023] (Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that each of the embodiments described below represents a specific example of the present disclosure. The numerical values, shapes, materials, circuit elements, layout and connection of circuit elements, signal waveforms, signal timing, etc. shown in the following embodiments are merely examples and are not intended to limit the present invention. Furthermore, each figure is not necessarily an exact illustration. In each figure, substantially identical configurations are assigned the same reference numerals, and redundant explanations are omitted or simplified. Furthermore, "connection" means electrical connection, and includes not only cases where two circuit elements are directly connected, but also cases where two circuit elements are indirectly connected with another circuit element inserted between them.

[0024] 1 is a circuit block diagram showing the configuration of a current measurement semiconductor device 30 according to an embodiment. The diagram also shows a measurement target device 3 that is the target of current measurement by the current measurement semiconductor device 30, a host system 90 that is the destination of the measurement results by the current measurement semiconductor device 30, and the like.

[0025] The current measuring semiconductor device 30 is a semiconductor device that measures the current flowing through the shunt resistor 4 provided in the device to be measured 3 and notifies the host system 90, and is realized, for example, as a single semiconductor chip or a semiconductor in which multiple chips are mixed in a single package, excluding the temperature sensor 75. Note that the temperature sensor 75 may also be provided in a single semiconductor chip or in a single package, like other circuit components.

[0026] In this embodiment, the measurement target device 3 is a lithium-ion battery system for an electric vehicle, and includes a lithium-ion battery pack 3a, a shunt resistor 4 connected in series with the battery pack 3a, and bus bars 8a and 8b connecting the battery pack 3a and the shunt resistor 4. The higher-level system 90 is, for example, an ECU (Electronic Control Unit) or the like as a controller provided in the electric vehicle.

[0027] The current measurement semiconductor device 30 includes a first current measurement circuit 10 that measures the current flowing through the shunt resistor 4 by detecting the voltage across the shunt resistor 4 provided in the device to be measured 3, a second current measurement circuit 20 that redundantly measures the current flowing through the shunt resistor 4 using a coreless magnetic sensor 50, a temperature measurement circuit 70 that measures the temperature of the coreless magnetic sensor 50 and the shunt resistor 4, a signal processing circuit 60 that performs corrections and abnormality detection on the measurements of the first current measurement circuit 10 and the second current measurement circuit 20, and a reference clock generation circuit 80 and a clock distribution circuit 81 for supplying clock signals to each circuit element.

[0028] A reference clock generation circuit 80 generates a single reference clock. A clock distribution circuit 81 divides the reference clock from the reference clock generation circuit 80, and supplies reference clocks CK11 to CK13, CK21 to CK23, CK31 to CK33, and CK4 to chopping circuits 18a to 18f, etc., as shown in the figure.

[0029] The first current measurement circuit 10 is a circuit that measures the current flowing through a shunt resistor 4 provided in the device under test 3, and has input terminals 10a and 10b, a differential variable gain amplifier (VGA) 11, an analog-to-digital converter (ADC) 12 such as a ΔΣ AD converter, a filter 13 such as a decimation filter, and chopping circuits 18a to 18f. Note that a noise-cutting filter circuit 5 (chip resistors 5a and 5b, chip capacitor 6) is provided between the shunt resistor 4 and the input terminals 10a and 10b.

[0030] The voltage generated across the shunt resistor 4 has noise removed by the filter circuit 5, is input to the variable gain amplifier 11 via chopping circuits 18a and 18b, is amplified by the variable gain amplifier 11, and is then input to the analog-to-digital converter 12 via chopping circuits 18c and 18d, is converted into a digital signal series by the analog-to-digital converter 12, is input to the filter 13 via chopping circuit 18e, is averaged by the filter 13 and converted into a parallel signal, and is then output as a measured value via chopping circuit 18f.

[0031] The chopping circuits 18a and 18f chop the signal in synchronization with the reference clock CK11 from the clock distribution circuit 81, thereby globally removing offsets that may occur mainly in signal processing in the first current measurement circuit 10. The chopping circuits 18b and 18c chop the differential signal in synchronization with the reference clock CK12 from the clock distribution circuit 81 to switch the positive and negative signs, and the chopping circuits 18d and 18e chop the differential signal in synchronization with the reference clock CK13 from the clock distribution circuit 81 to switch the positive and negative signs, thereby mainly removing 1 / f noise that may occur in signal processing in the variable gain amplifier 11 and the analog-to-digital converter 12, respectively.

[0032] The second current measurement circuit 20 is a circuit that redundantly measures the current flowing through the shunt resistor 4 using the coreless magnetic sensor 50, and includes the coreless magnetic sensor 50, a differential variable gain amplifier (VGA) 21, an analog-to-digital converter (ADC) 22 such as a ΔΣ AD converter, a filter 23 such as a decimation filter, and chopping circuits 28a to 28f. The coreless magnetic sensor 50 is composed of a Hall element 51, a current source 52 that applies current to the Hall element 51, and a switch circuit 53 that switches the connection between the Hall element 51 and the current source 52 and the chopping circuit 28a.

[0033] The voltage generated by the Hall element 51 is input to the variable gain amplifier 21 via the switch circuit 53 and the chopping circuit 28a, amplified by the variable gain amplifier 21, and then input to the analog-to-digital converter 22 via the chopping circuits 28b and 28c, converted into a digital signal series by the analog-to-digital converter 22, and then input to the filter 23 via the chopping circuit 28d, averaged by the filter 23, converted into a parallel signal, and then output as a measurement value via the chopping circuit 28e.

[0034] The switch circuit 53 and chopping circuit 28e switch the current application and voltage measurement points for the Hall element 51 and chop the signal, respectively, in synchronization with the reference clock CK21 from the clock distribution circuit 81, thereby globally removing offsets that may occur mainly in signal processing by the second current measurement circuit 20. The chopping circuits 28a and 28b perform chopping to switch the positive and negative signs of the differential signal in synchronization with the reference clock CK22 from the clock distribution circuit 81, and the chopping circuits 28c and 28d perform chopping to switch the positive and negative signs of the differential signal in synchronization with the reference clock CK23 from the clock distribution circuit 81, thereby mainly removing 1 / f noise that may occur in signal processing by the variable gain amplifier 21 and the analog-to-digital converter 22, respectively.

[0035] The temperature measurement circuit 70 is a circuit that measures the temperatures of the coreless magnetic sensor 50 and the shunt resistor 4, and includes temperature sensors 74 and 75, a multiplexer (MUX) 76, a differential amplifier (Amp) 71, an analog-to-digital converter (ADC) 72 such as a ΔΣ AD converter, a filter (Filter) 73 such as a decimation filter, and chopping circuits 78a to 78g. The temperature sensor 74 is disposed in contact with or close to the coreless magnetic sensor 50 and detects the temperature of the coreless magnetic sensor 50, and is, for example, a semiconductor temperature sensor such as a diode. The temperature sensor 75 is disposed in contact with or close to the shunt resistor 4 and detects the temperature of the shunt resistor 4, and is, for example, a thermistor.

[0036] A voltage corresponding to the temperature of the Hall element 51 detected by the temperature sensor 74 is input to one input terminal of the multiplexer 76 via a chopping circuit 78a, while a voltage corresponding to the temperature of the shunt resistor 4 detected by the temperature sensor 75 is input to the other input terminal of the multiplexer 76 via a chopping circuit 78b. Only one of the input signals is selected and output by the multiplexer 76, input to the amplifier 71 via a chopping circuit 78c, amplified by the amplifier 71, input to the analog-to-digital converter 72 via chopping circuits 78d and 78e, converted into a digital signal series by the analog-to-digital converter 72, input to the filter 73 via a chopping circuit 78f, averaged and converted into a parallel signal by the filter 73, and output as a measurement value via a chopping circuit 78g.

[0037] Chopping circuits 78a, 78b, and 78g chop signals in synchronization with reference clock CK31 from clock distribution circuit 81, thereby globally removing offsets that may occur mainly in signal processing in temperature measurement circuit 70. Chopping circuits 78c and 78d chop differential signals in synchronization with reference clock CK32 from clock distribution circuit 81 to switch the positive and negative signs of the differential signals, and chopping circuits 78e and 78f chop differential signals in synchronization with reference clock CK33 from clock distribution circuit 81 to switch the positive and negative signs of the differential signals, thereby mainly removing 1 / f noise that may occur in signal processing in amplifier 71 and analog-to-digital converter 72, respectively.

[0038] The signal processing circuit 60 is a processing circuit that corrects the measured values ​​of the first current measurement circuit 10 and the second current measurement circuit 20 and detects abnormalities in the current measurement semiconductor device 30, the coreless magnetic sensor 50, and the shunt resistor 4, and includes correction units 61 and 62, a calculation unit 63, a memory unit 64, a comparison unit 65, abnormality detection units 66 to 68, and a data I / F (interface) 69. The correction units 61 and 62, the calculation unit 63, the comparison unit 65, and the abnormality detection units 66 to 68 are realized, for example, by a gate array, or a semiconductor memory that stores a program and a processor that executes the program. The memory unit 64 is realized, for example, by a semiconductor memory such as an SRAM. The data I / F (interface) 69 is realized, for example, by a logic circuit.

[0039] The memory unit 64 stores in advance a temperature coefficient for correcting the temperature dependence of the coreless magnetic sensor 50 and the shunt resistor 4 obtained by the temperature measurement circuit 70, and stores correction parameters (slope, offset) for the measurement value of the second current measurement circuit 20 calculated by the calculation unit 63.

[0040] The calculation unit 63 has a calibration mode in which it corrects the measurement value of the second current measurement circuit 20 using the coreless magnetic sensor 50 using the measurement value of the first current measurement circuit 10 using the shunt resistor 4 and stores the obtained correction information (correction parameters indicating the slope and offset) in the storage unit 64, and a normal measurement mode in which it notifies the correction unit 61 of the stored correction information, thereby enabling correction of the measurement value of the second current measurement circuit 20 and causing current measurement to be performed. In the normal measurement mode, the calculation unit 63 reads from the storage unit 64 the temperature coefficients corresponding to the temperatures of the coreless magnetic sensor 50 and the shunt resistor 4 obtained by the temperature measurement circuit 70 and notifies the correction units 61 and 62, respectively, thereby enabling correction of the temperature dependency of the measurement value of the first current measurement circuit 10 and the measurement value of the second current measurement circuit 20.

[0041] The correction unit 61 corrects the temperature dependency of the measurement value of the second current measurement circuit 20 using the coreless magnetic sensor 50 based on the temperature coefficient notified by the calculation unit 63, and corrects the measurement value after temperature correction based on the correction information (correction parameters indicating the slope and offset) notified by the calculation unit 63.

[0042] The correction unit 62 corrects the temperature dependency of the measured value of the first current measuring circuit 10 using the shunt resistor 4 based on the temperature coefficient notified by the calculation unit 63 .

[0043] In the normal measurement mode, the comparison unit 65 compares the first measurement value obtained by correcting the measurement value of the first current measurement circuit 10 by the correction unit 62 with the second measurement value obtained by correcting the measurement value of the second current measurement circuit 20 by the correction unit 61, and notifies the abnormality detection unit 67 of the comparison result. More specifically, when the second measurement value obtained by correcting the measurement value of the second current measurement circuit 20 using the coreless magnetic sensor 50 by the correction unit 61 is within a range in which both the coreless magnetic sensor 50 and the shunt resistor 4 indicate valid measurement currents, the comparison unit 65 compares the first measurement value obtained by correcting the measurement value of the first current measurement circuit 10 using the shunt resistor 4 by the correction unit 62 with the second measurement value obtained by correcting the measurement value of the second current measurement circuit 20 using the coreless magnetic sensor 50 by the correction unit 61, and notifies the abnormality detection unit 67 of the comparison result.

[0044] If the first measurement value and the second measurement value do not match within a certain range based on the comparison result notified by the comparison unit 65, the abnormality detection unit 67 outputs an abnormality signal indicating this to the data I / F 69. For example, if the notified comparison result indicates that the first measurement value is lower than the second measurement value by more than a certain range, the abnormality detection unit 67 determines that a short mode failure has occurred in the shunt resistor 4, and outputs an abnormality signal indicating this to the data I / F 69.

[0045] The abnormality detection unit 66 determines whether the second measurement value after correction by the correction unit 61 for the measurement value of the second current measurement circuit 20 using the coreless magnetic sensor 50 exceeds a predetermined normal operating current range (i.e., the range of current that can flow when the device to be measured 3 is operating normally), and if it does exceed the range, outputs an abnormality signal to the data I / F 69 indicating that the current value flowing through the shunt resistor 4 in the device to be measured 3 is abnormally large.

[0046] Similarly, the abnormality detection unit 68 determines whether the first measurement value after correction by the correction unit 62 for the measurement value of the first current measurement circuit 10 using the shunt resistor 4 exceeds a predetermined normal operating current range, and if it does, outputs an abnormality signal to the data I / F 69 indicating that the current value flowing through the shunt resistor 4 in the device to be measured 3 is abnormally large.

[0047] The data I / F 69 transmits to the host system 90 the first measurement value obtained by correcting the measurement value of the first current measurement circuit 10 using the correction unit 62, the second measurement value obtained by correcting the measurement value of the second current measurement circuit 20 using the coreless magnetic sensor 50 using the correction unit 61, and the abnormality signals output from the abnormality detection units 66 to 68 in synchronization with the reference clock CK4 from the clock distribution circuit 81. Note that when the data I / F 69 determines, by using at least one of the first measurement value and the second measurement value, that the current flowing through the shunt resistor 4 is within a predetermined minute current range in which the second current measurement circuit 20 cannot measure the current, the data I / F 69 discards the measurement value of the second current measurement circuit 20 (i.e., does not notify the host system 90) and outputs only the measurement value of the first current measurement circuit 10 (i.e., notifies the host system 90).

[0048] 2A is an external view showing an example of mounting a current measuring semiconductor device 30 according to an embodiment. Here, the example shows a current measuring semiconductor device 30 mounted on a printed circuit board 31 as a one-chip semiconductor or a single semiconductor package.

[0049] As shown in the figure, a shunt resistor 4, both ends of which are connected to bus bars 8a and 8b, is disposed on the top surface of a printed circuit board 31. A filter circuit 5 (chip resistors 5a and 5b, chip capacitor 6) is provided, connected to the shunt resistor 4 via a wiring pattern. Furthermore, a current measuring semiconductor device 30, connected to the filter circuit 5 via a wiring pattern, is mounted on the top surface of the printed circuit board 31. The current measuring semiconductor device 30 incorporates a coreless magnetic sensor 50 and is disposed adjacent to the shunt resistor 4, sandwiching the small filter circuit 5, which is composed of chip components. This allows the coreless magnetic sensor 50, incorporated in the current measuring semiconductor device 30, to detect with high sensitivity the magnetic flux generated by the current flowing through the shunt resistor 4. Note that a temperature sensor 75 for detecting the temperature of the shunt resistor 4 is not shown in the figure.

[0050] 2B is a diagram showing an example layout of the main circuit elements in the current measuring semiconductor device 30 according to the embodiment. In this layout example, a diode, which is an example of a temperature sensor 74, is arranged in contact with or in close proximity to the Hall element 51. Since the forward voltage of a diode such as a Si diode has a constant negative temperature coefficient, the temperature can be measured by measuring the voltage across the diode.

[0051] 3 is a diagram illustrating the current-voltage characteristics of the shunt resistor 4 included in the device under test 3 and the coreless magnetic sensor 50 included in the current measuring semiconductor device 30, and the correction in the current measuring semiconductor device 30. The horizontal axis represents the current flowing through the shunt resistor 4 to be detected, and the vertical axis represents the output voltage from the shunt resistor 4 and the coreless magnetic sensor 50.

[0052] On the horizontal axis, the "microcurrent range" indicates the current range that the coreless magnetic sensor 50 cannot accurately detect (the "coreless magnetic sensor dead zone"), and the "coreless magnetic sensor effective area" indicates the current range that the coreless magnetic sensor 50 can effectively detect. The "normal operating area" indicates the range of current that can flow when the measurement target device 3 is operating normally (also called the "normal operating current range"), and is used to determine whether or not an abnormality has occurred in the measurement target device 3.

[0053] In this figure, the thick solid line shows the current-voltage characteristics of the shunt resistor 4. It shows linearity over a wide current range, including the "normal operating region," but in an extremely large current range, it shows saturation characteristics due to the limit of the dynamic range in the measurement circuit.

[0054] In this figure, the dashed dotted line and the thin solid line that follows it represent the current-voltage characteristics of the coreless magnetic sensor 50. The dashed dotted line represents the current-voltage characteristics of the coreless magnetic sensor 50 in the "microcurrent region" where the coreless magnetic sensor 50 cannot accurately detect current.

[0055] In this figure, the dashed line partially overlapping the thick solid line indicates the current-voltage characteristics of the coreless magnetic sensor 50 after correction using the shunt resistor 4. Essentially, the current-voltage characteristics of the coreless magnetic sensor 50 have a smaller slope than the shunt resistor 4, as shown by the dashed-dotted line and the thin solid line following it, and also have an offset in the output voltage when the current value is zero. Therefore, when the current flowing through the shunt resistor 4 is in the "normal operating range" and the "coreless magnetic sensor effective range" (at two or more different current values), the calculation unit 63 of the signal processing circuit 60 included in the current measuring semiconductor device 30 according to this embodiment records the measurement value of the first current measurement circuit 10 using the shunt resistor 4 and the measurement value of the second current measurement circuit 20 using the coreless magnetic sensor 50, and calculates the relationship therebetween using a linear approximation equation or the like, thereby enabling "gain correction" and "offset correction" for the measurement value of the second current measurement circuit 20 using the coreless magnetic sensor 50 (i.e., use of the corrected current-voltage characteristic of the coreless magnetic sensor 50 indicated by the dashed line partially overlapping the thick solid line). In other words, the correction unit 61 of the signal processing circuit 60 can output the corrected measurement value of the second current measurement circuit 20 using the coreless magnetic sensor 50 by using the corrected current-voltage characteristic of the coreless magnetic sensor 50.

[0056] 4 is a flowchart showing the operation of the current measuring semiconductor device 30 according to the embodiment. This flowchart mainly shows the operation of the correction process by the calculation unit 63 of the signal processing circuit 60 included in the current measuring semiconductor device 30 (i.e., correction of the measurement value of the second current measuring circuit 20 using the measurement value of the first current measuring circuit 10, and correction of the temperature dependence of the coreless magnetic sensor 50 and the shunt resistor 4).

[0057] The operation of the current measurement semiconductor device 30 consists of a calibration mode (S10 to S17) followed by a normal measurement mode (S18 to S21). The calibration mode may be performed before the current measurement semiconductor device 30 is manufactured and shipped from the manufacturer, or may be performed during operation after shipment.

[0058] In the calibration mode (S10 to S17), first, the calculation unit 63 of the signal processing circuit 60 acquires a measurement value from the first current measuring circuit 10 using the shunt resistor 4 (S11).

[0059] Next, the calculation unit 63 determines whether the acquired measurement value is within the "normal operating range" and the "coreless magnetic sensor effective range" shown in Figure 3 (S12). If the determination is negative (No in S12), the calculation unit 63 returns to step S11 and repeats the process. If the determination is positive (Yes in S12), the calculation unit 63 further acquires measurement values ​​of the second current measurement circuit 20 using the coreless magnetic sensor 50 (S13), and stores these measurement values ​​in the memory unit 64 as pre-correction measurement data (S14).

[0060] Next, the calculation unit 63 determines whether the number of data points required for correction has been obtained (S15). If the determination is negative (No in S15), the calculation unit 63 returns to step S11 and repeats the process. If the determination is positive (Yes in S15), the calculation unit 63 uses the pre-correction measurement data accumulated in the memory unit 64 up to that point to calculate the relationship between them using a linear approximation equation, etc., to calculate correction parameters (slope, offset) that enable ``gain correction'' and ``offset correction'' for the measurement value of the second current measurement circuit 20 using the coreless magnetic sensor 50, and stores them in the memory unit 64 (S16).

[0061] The storage unit 64 previously stores temperature coefficients for correcting the temperature dependence of the coreless magnetic sensor 50 and the shunt resistor 4. Therefore, in the calibration mode in steps S10 to S17, the temperature-corrected measurement values ​​may be used as the measurement values ​​of the first current measurement circuit 10 and the second current measurement circuit 20.

[0062] Next, in the normal measurement mode (S18 to S21), the calculation unit 63 of the signal processing circuit 60 first acquires measurement values ​​from each of the first current measurement circuit 10 using the shunt resistor 4 and the second current measurement circuit 20 using the coreless magnetic sensor 50, and acquires the temperatures of the coreless magnetic sensor 50 and the shunt resistor 4 from the temperature measurement circuit 70 (S19).

[0063] Then, the calculation unit 63 reads out the temperature coefficients corresponding to the acquired temperatures of the coreless magnetic sensor 50 and shunt resistor 4 from the memory unit 64 and notifies the correction units 61 and 62, respectively, thereby enabling the correction unit 61 to correct the temperature dependency of the measurement value of the second current measurement circuit 20, and the correction unit 62 to correct the temperature dependency of the measurement value of the first current measurement circuit 10.Furthermore, by reading out the correction information (correction parameters indicating the slope and offset) from the memory unit 64 and notifying the correction unit 61, the correction unit 61 can perform ``gain correction'' and ``offset correction'' on the measurement value of the second current measurement circuit 20 using the coreless magnetic sensor 50 (S20).

[0064] Next, the calculation unit 63 determines whether re-correction is necessary by determining whether a predetermined period of time has passed since the last execution of the calibration mode (S21). If the determination is affirmative (Yes in S21), the calculation unit 63 returns to the calibration mode (S10 to S17) and repeats the process. If the determination is negative (No in S21), the calculation unit 63 returns to the normal measurement mode (S18 to S21) and repeats the process.

[0065] In this way, the current measuring semiconductor device 30 of the embodiment corrects the measurement value of the second current measuring circuit 20 using the measurement value of the first current measuring circuit 10, and corrects the temperature dependence of the coreless magnetic sensor 50 and the shunt resistor 4, thereby achieving highly accurate current measurement using the redundant current measuring semiconductor device 30 to prevent common cause failures.

[0066] 5 is a flowchart showing the operation of the current measuring semiconductor device 30 according to the embodiment to detect an abnormality in the shunt resistor 4. The flowchart mainly shows the process of detecting an abnormality in the shunt resistor 4 by the comparison unit 65 and the abnormality detection unit 67 of the signal processing circuit 60 included in the current measuring semiconductor device 30.

[0067] In the normal measurement mode, the comparison unit 65 acquires a first measurement value after correction by the correction unit 62 for the measurement value of the first current measurement circuit 10 using the shunt resistor 4, and a second measurement value after correction by the correction unit 61 for the measurement value of the second current measurement circuit 20 using the coreless magnetic sensor 50 (S30).

[0068] Then, the comparison unit 65 determines whether the acquired second measurement value is within a range in which both the coreless magnetic sensor 50 and the shunt resistor 4 indicate a valid measurement current (S31), and if the determination is negative (No in S31), it returns to step S30 and repeats the process, and if the determination is positive (Yes in S31), it compares the acquired first measurement value with the second measurement value and notifies the abnormality detection unit 67 of the comparison result (S32).

[0069] The anomaly detection unit 67 determines whether the first measurement value and the second measurement value match within a certain range based on the comparison result notified by the comparison unit 65 (S33), and if the determination is affirmative (Yes in S33), it determines that there is no anomaly and returns to step S30 to repeat the process, and if the determination is negative (No in S33), it generates an anomaly signal indicating this (S34) and notifies the upper system 90 via the data I / F 69. For example, if the notified comparison result indicates that the first measurement value is lower than the second measurement value by more than a certain range, the anomaly detection unit 67 determines that a short mode failure has occurred in the shunt resistor 4 and generates an anomaly signal indicating this.

[0070] In this way, the current measuring semiconductor device 30 of the embodiment compares the measurement value of the first current measuring circuit 10 with the corrected measurement value of the second current measuring circuit 20, thereby detecting a short mode failure of the shunt resistor 4 and ensuring safe operation.

[0071] 6 is a flowchart showing an operation of the current measurement semiconductor device 30 according to the embodiment to detect an abnormality in the measurement target device 3. The flowchart mainly shows a process in which the abnormality detection units 68 and 66 of the signal processing circuit 60 included in the current measurement semiconductor device 30 detect an abnormality in the current value in the measurement target device 3.

[0072] First, the abnormality detection units 68 and 66 respectively acquire a first measurement value after correction by the correction unit 62 for the measurement value of the first current measurement circuit 10 using the shunt resistor 4, and a second measurement value after correction by the correction unit 61 for the measurement value of the second current measurement circuit 20 using the coreless magnetic sensor 50 (S40).

[0073] Then, the abnormality detection units 68 and 66 respectively determine whether the acquired first measurement value and second measurement value are within a predetermined normal operating current range (i.e., the range of current that can flow when the measurement target device 3 is operating normally) (S41).

[0074] As a result, if the abnormality detection units 66 and 68 make a positive judgment (i.e., both the first measurement value and the second measurement value are within the predetermined normal operating current range) (Yes in S41), they determine that there is no abnormality and return to step S40 to repeat the process; if they make a negative judgment (i.e., at least one of the first measurement value and the second measurement value is not within the predetermined normal operating current range) (No in S41), they generate an abnormality signal indicating that the current value flowing through the shunt resistor 4 in the device to be measured 3 is abnormally large (S42), and notify the upper system 90 via the data I / F 69, thereby activating a circuit breaker (not shown) connected in series with the battery pack 3a and cutting off the current flowing through the shunt resistor 4.

[0075] In this way, the current measuring semiconductor device 30 according to the embodiment compares the first and second measured values ​​with the normal operating current range, thereby detecting that an abnormally large current is flowing in the device to be measured 3, and ensuring safe operation of the device to be measured 3.

[0076] As described above, the current measurement semiconductor device 30 relating to technology 1 of this embodiment is a device that measures the current flowing through the shunt resistor 4 provided in the device to be measured 3, and includes a first current measurement circuit 10 that measures the current flowing through the shunt resistor 4 by detecting the voltage across the shunt resistor 4, and a second current measurement circuit 20 that has a coreless magnetic sensor 50 and measures the current flowing through the shunt resistor 4 using the coreless magnetic sensor 50.

[0077] As a result, the current measuring semiconductor device 30 according to the embodiment is a single semiconductor device that measures the current flowing through the shunt resistor 4, and is equipped with a coreless magnetic sensor 50 that is free from magnetic saturation due to the magnetic core and is capable of measuring in a larger current range, and is configured as a single semiconductor that can be placed in close proximity to the shunt resistor 4, thereby realizing a current measuring semiconductor device in which common cause failures are suppressed.

[0078] Furthermore, the current measurement semiconductor device 30 according to Technology 2 further includes a reference clock generation circuit 80 in addition to the components of the current measurement semiconductor device 30 according to Technology 1, and the first current measurement circuit 10 and the second current measurement circuit 20 each have chopping circuits 18a to 18f and 28a to 28e that operate in synchronization with the reference clock generated by the reference clock generation circuit 80. This suppresses error factors such as offset and 1 / f noise that may occur in the first current measurement circuit 10 and the second current measurement circuit 20, thereby achieving highly accurate current measurement.

[0079] Furthermore, the current measurement semiconductor device 30 according to Technology 3 further includes temperature sensors 74 and 75 that detect the temperatures of the coreless magnetic sensor 50 and the shunt resistor 4, and a signal processing circuit 60 that corrects the temperature dependence of the first current measurement circuit 10 and the second current measurement circuit 20 based on the temperatures detected by the temperature sensors 74 and 75. This corrects the temperature dependence of the coreless magnetic sensor 50 and the shunt resistor 4, thereby achieving highly accurate current measurement.

[0080] Furthermore, the current measuring semiconductor device 30 according to Technology 4 is a current measuring semiconductor device 30 according to any one of Technologies 1 to 3, further comprising a signal processing circuit 60 that corrects the measurement value of the second current measuring circuit 20 based on the measurement value of the first current measuring circuit 10.

[0081] Furthermore, in a current measurement semiconductor device 30 according to Technology 5, in the current measurement semiconductor device 30 according to any one of Technology 1 to 4, the signal processing circuit 60 has a calibration mode in which the measurement value of the second current measurement circuit 20 is corrected using the measurement value of the first current measurement circuit 10 and the obtained correction information is stored, and a normal measurement mode in which current is measured using the measurement value of the second current measurement circuit 20 corrected based on the stored correction information, and in the normal measurement mode, the measurement value of the first current measurement circuit 10 is compared with the corrected measurement value of the second current measurement circuit 20 to detect an abnormality in the shunt resistor 4. In this way, the measurement value of the second current measurement circuit 20 is corrected using the measurement value of the first current measurement circuit 10, and further, the agreement of the two measurement values ​​is confirmed, and a short-circuit mode failure of the shunt resistor 4 can be detected.

[0082] Furthermore, in the current measurement semiconductor device 30 according to Technology 6, in the current measurement semiconductor device 30 according to any one of Technologies 1 to 5, the signal processing circuit 60 detects that the device under test 3 is abnormal when either the measurement value of the first current measurement circuit 10 or the corrected measurement value of the second current measurement circuit 20 exceeds a predetermined normal operating current range. This detects that an abnormally large current is flowing in the device under test 3, and ensures safe operation of the device under test 3.

[0083] Furthermore, in the current measurement semiconductor device 30 according to Technology 7, in the current measurement semiconductor device 30 according to any one of Technologies 1 to 6, the signal processing circuit 60 discards the measurement value of the second current measurement circuit 20 in a predetermined minute current region where the second current measurement circuit 20 is unable to measure, and outputs the measurement value of the first current measurement circuit 10. As a result, the measurement value of the second current measurement circuit 20, which has low accuracy, is discarded in the minute current region, and only valid measurement values ​​are output in the entire current region.

[0084] In the current measuring semiconductor device 30 according to any one of the techniques 1 to 7, the coreless magnetic sensor 50 may be a Hall element or a magnetoresistive element.

[0085] Although the current measurement semiconductor device 30 according to the present invention has been described above based on the embodiment, the present invention is not limited to this embodiment. As long as it does not deviate from the gist of the present invention, various modifications that a person skilled in the art can make to this embodiment and other forms constructed by combining some of the components in the embodiment are also included within the scope of the present disclosure.

[0086] For example, in the above embodiment, the Hall element 51 is used as the coreless magnetic sensor 50, but this is not limiting, and a highly sensitive MR (Magneto Resistive) element or a GMR (Giant Magneto Resistive) element may be formed on the substrate surface of the current measuring semiconductor device 30 using thin film formation technology.

[0087] Furthermore, in the above embodiment, the temperature sensor 75 that detects the temperature of the shunt resistor 4 is provided outside the one-chip semiconductor or semiconductor package that constitutes the current measurement semiconductor device 30, but this is not limited to such a form and the temperature sensor 75 may be provided inside the one-chip semiconductor or semiconductor package that constitutes the current measurement semiconductor device 30.

[0088] Furthermore, in the above embodiment, the filter circuit 5 is mounted on the printed circuit board 31 as a circuit separate from the current measuring semiconductor device 30, but this is not limited to this form, and the filter circuit 5 may be incorporated into the current measuring semiconductor device 30 as a circuit provided in the current measuring semiconductor device 30.

[0089] In the above embodiment, the shunt resistor 4 is provided in the device under test 3, but the present invention is not limited to this, and the shunt resistor 4 may be a circuit element provided in the semiconductor device 30 for current measurement.

[0090] Furthermore, the present invention can be realized not only as a semiconductor device for current measurement, but also as a method (for example, a method for correcting the temperature dependence of the first current measurement circuit and the second current measurement circuit, or a method for detecting an abnormality in a shunt resistor) related to processing by a signal processing circuit provided in the semiconductor device for current measurement (processing shown in the flowcharts of Figures 4 to 6), or as a program for causing a processor to execute the method, or as a computer-readable recording medium on which the program is recorded, or as a program product including the program.

[0091] The present invention uses a current measurement circuit that measures current using a shunt resistor, which is capable of measuring current with high accuracy and a wide dynamic range, primarily in measuring lithium-ion battery current for electric vehicles, as a current measurement semiconductor device that measures the current flowing through a shunt resistor provided in a device to be measured, and easily realizes redundancy using a coreless magnetic sensor that suppresses common cause failures in terms of functional safety.High-accuracy current measurement using a shunt resistor enables highly accurate calculation of the SOC and SOH (State of Health) of the lithium-ion battery for electric vehicles, thereby extending the driving range of the electric vehicle.

[0092] 3 Measurement target device 3a Battery pack 4 Shunt resistor 5 Filter circuit 5a, 5b Chip resistor 6 Chip capacitor 8a, 8b Bus bar 10 First current measurement circuit 10a, 10b Input terminal 11, 21 Variable gain amplifier (VGA) 12, 22, 72 Analog-to-digital converter (ADC) 13, 23, 73 Filter 18a to 18f, 28a to 28e, 78a to 78g Chopping circuit 20 Second current measurement circuit 30 Current measurement semiconductor device 31 Printed circuit board 50 Coreless magnetic sensor 51 Hall element 52 Current source 53 Switch circuit 60 Signal processing circuit 61, 62 Correction unit 63 Calculation unit 64 Memory unit 65 Comparison unit 66 to 68 Abnormality detection unit 69 Data I / F (interface) 70 Temperature measurement circuit 71 Amplifier (Amp) 74, 75 Temperature sensor 76 Multiplexer (MUX) 80 Reference clock generation circuit 81 Clock distribution circuit 90 Upper system

Claims

1. A current measuring semiconductor device that measures a current flowing through a shunt resistor provided in a device to be measured, comprising: a first current measuring circuit that measures the current flowing through the shunt resistor by detecting a voltage across the shunt resistor; and a second current measuring circuit that has a coreless magnetic sensor and measures the current flowing through the shunt resistor using the coreless magnetic sensor.

2. The current measuring semiconductor device according to claim 1, further comprising a reference clock generating circuit, wherein each of the first current measuring circuit and the second current measuring circuit has a chopping circuit that operates in synchronization with a reference clock generated by the reference clock generating circuit.

3. The current measuring semiconductor device according to claim 1 or 2, further comprising: a temperature sensor which detects the temperatures of the coreless magnetic sensor and the shunt resistor; and a signal processing circuit which corrects the temperature dependence of the first current measuring circuit and the second current measuring circuit based on the temperature detected by the temperature sensor.

4. The current measuring semiconductor device according to claim 1 or 2, further comprising a signal processing circuit that corrects the measurement value of said second current measuring circuit based on the measurement value of said first current measuring circuit.

5. The current measuring semiconductor device according to claim 4, wherein the signal processing circuit has a calibration mode in which the measurement value of the second current measuring circuit is corrected based on the measurement value of the first current measuring circuit and the obtained correction information is stored, and a normal measurement mode in which current is measured using the measurement value of the second current measuring circuit corrected based on the stored correction information, and in the normal measurement mode, the measurement value of the first current measuring circuit is compared with the corrected measurement value of the second current measuring circuit to detect an abnormality in the shunt resistor.

6. The current measuring semiconductor device according to claim 5, wherein the signal processing circuit detects that the device being measured is abnormal when either the measurement value of the first current measuring circuit or the corrected measurement value of the second current measuring circuit exceeds a predetermined normal operating current range.

7. The current measuring semiconductor device according to claim 4, wherein the signal processing circuit discards the measurement value of the second current measuring circuit and outputs the measurement value of the first current measuring circuit in a predetermined small current region where the second current measuring circuit is unable to make measurements.

8. The current measuring semiconductor device according to claim 1 or 2, wherein the coreless magnetic sensor is a Hall element.

9. The semiconductor device for measuring current according to claim 1 or 2, wherein the coreless magnetic sensor is a magnetoresistance element.

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