Shunt resistance value measuring circuit for shunt type current sensor

Abstract

To provide a shunt resistance value measuring circuit for a shunt type current sensor, capable of measuring a resistance value of a shunt resistance without requiring a current source for energizing highly accurate current.SOLUTION: A shunt resistance value measuring circuit 1 comprises: a control circuit 10 outputting a signal including an AC carrier signal SC; and a switching power supply circuit 11 including a switching element, driving the switching element on the basis of the signal including the carrier signal SC, and outputting a power supply due to an AC exciting current IE. Output of the power supply of the switching power supply circuit 11 is inputted to a shunt resistance 12. The first voltage measuring circuit 13 measures a voltage applied to the shunt resistance 12. A signal processing circuit 14 processes the signal on the basis of the measured voltage of the first voltage measuring circuit 13 and measures a resistance value RS of the shunt resistance 12.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a shunt resistance measurement circuit for a shunt-type current sensor. [Background technology]

[0002] Electric vehicles such as electric vehicles (EV) and hybrid electric vehicles (HEV) are equipped with batteries. In order to estimate the remaining capacity of this type of battery, a circuit is required to measure the current flowing through the battery. A shunt current sensor is provided to measure the current flowing through the battery. The shunt current sensor measures the current by connecting a shunt resistor in series to the battery and measuring the voltage across the shunt resistor. The resistance value of the shunt resistor changes due to deterioration over time. Therefore, the current can be measured with high accuracy by accurately determining the resistance value of the shunt resistor and then correcting it. An example of a shunt current sensor is disclosed in Patent Document 1. According to the technology described in Patent Document 1, a highly accurate reference excitation current is applied to a shunt resistor, the voltage across the shunt resistor is measured, the shunt resistance value is determined from the applied excitation current and the measured voltage across the shunt, and the shunt resistance value is corrected to improve accuracy. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Pat. No. 1,052,7651 Summary of the Invention [Problem to be solved by the invention]

[0004] When applying the technology described in Patent Document 1, a reference current source that generates a highly accurate reference current is required. A reference current source with small temperature characteristics and degradation is not preferable because the reference diode or transistor becomes large and the correction circuit becomes large, resulting in high costs. In addition, the power supply power for passing the excitation current tends to become large, which is also undesirable.

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and its object is to provide a shunt resistance measurement circuit for a shunt-type current sensor that can measure the resistance value of a shunt resistor without requiring a current source for passing a highly accurate current. [Means for solving the problem]

[0006] The invention of claim 1 is directed to a shunt resistance measurement circuit for a shunt-type current sensor. The shunt resistance measurement circuit includes a control circuit, a switching power supply circuit, and a first voltage measurement circuit. The control circuit outputs a signal including an AC carrier signal. The switching power supply circuit includes a switching element, drives the switching element based on the signal including the carrier signal, and outputs power based on an AC excitation current. The power output of the switching power supply circuit is applied to the shunt resistor. The first voltage measurement circuit measures the voltage across the shunt resistor. The signal processing circuit processes the signal based on the voltage measured by the first voltage measurement circuit, and measures the resistance value of the shunt resistor.

[0007] According to the invention described in claim 1, the resistance value of the shunt resistor can be measured based on the AC excitation current generated by the switching power supply circuit, so that the resistance value of the shunt resistor can be measured without needing a current source for passing a highly accurate current. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is an electrical configuration diagram showing a shunt resistance measurement circuit according to a first embodiment; [Diagram 2] FIG. 1 is an electrical block diagram showing a battery monitoring system according to a first embodiment of the present invention; [Diagram 3] Electrical configuration diagram of a switching power supply circuit according to a first embodiment [Figure 4] FIG. 1 is a timing chart showing waveforms of various parts in the first embodiment; [Diagram 5] FIG. 5 is an enlarged view of a portion A in FIG. 4 according to the first embodiment; [Figure 6]FIG. 11 is an electrical configuration diagram showing a shunt resistance value measuring circuit according to a second embodiment. [Figure 7] FIG. 11 is an explanatory diagram of the processing contents of a signal processing circuit in the second embodiment; [Figure 8] FIG. 13 is an electrical diagram showing a schematic configuration of a shunt resistance value measuring circuit according to a third embodiment. [Figure 9] Configuration example of a shunt resistance value measuring circuit in the fourth embodiment [Figure 10] Configuration example of a shunt resistance value measuring circuit in the fifth embodiment [Figure 11] Configuration example 1 of the shunt resistance measurement circuit in the sixth embodiment [Figure 12] Configuration example 2 of the shunt resistance measurement circuit in the sixth embodiment [Figure 13] FIG. 13 is an electrical configuration diagram illustrating a shunt resistance value measuring circuit according to the seventh embodiment. [Figure 14] FIG. 13 is an electrical configuration diagram showing an example of the configuration of a shunt resistance value measuring circuit according to the seventh embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, several embodiments of the shunt resistance measurement circuit will be described. In each embodiment described below, components that perform the same or similar operations are denoted by the same or similar reference numerals, and descriptions thereof will be omitted as necessary.

[0010] (First embodiment) The first embodiment will be described with reference to Fig. 1 to Fig. 5. Fig. 2 shows a schematic diagram of a battery monitoring system 100. As shown in Fig. 2, the battery monitoring system 100 is mainly composed of a battery monitoring integrated circuit 55, a temperature sensor 56, an MCU 57, and a shunt resistance measurement circuit 1. The shunt resistance measurement circuit 1 includes an analog front end (AFE) 50a, a DSP 51, a current excitation circuit 52, and an analog front end (AFE) 53 for temperature measurement.

[0011] DSP is an abbreviation of Digital Signal Processor. MCU is an abbreviation of Micro Controller Unit. The MCU 57 includes a processor and a memory, and operates based on a program prestored in the memory. The memory is configured as a non-transient tangible recording medium. The current excitation circuit 52 includes, for example, a switching power supply circuit 11 (see below), and outputs an AC excitation current I E is applied to the shunt resistor 12. The analog front end 50a is connected between the terminals of the shunt resistor 12, measures the voltage across the shunt resistor 12, and performs analog processing. The shunt resistor 12 is connected in series to a battery 58. The shunt resistor 12 detects a load current I L It is provided to measure with high accuracy.

[0012] The battery 58 is a main battery and / or an auxiliary battery, which is a combination of battery cells in series or series-parallel. The battery 58 is provided to drive a load 80, which is a main motor or a DC-DC converter of a vehicle such as an electric vehicle or a hybrid vehicle, and / or to supply power to a vehicle electronic control device provided in the vehicle.

[0013] A relay 59 and a load 80 are connected in series to the battery 58 and the shunt resistor 12. When the ignition switch is turned on by the user to start the vehicle, the relay 59 is turned on. When the relay 59 is turned on, the load 80, the battery 58, and the shunt resistor 12 are connected. As a result, a load current I L is energized.

[0014] The shunt resistor 12 is on the order of several tens of micro-ohms and supplies a load current I L When a current is applied, a current of the order of several thousand amperes flows through the shunt resistor 12. The shunt resistor 12 deteriorates with age and its resistance value R S Therefore, the shunt resistance measurement circuit 1 detects the resistance R of the shunt resistor 12. S By accurately calculating the load current I Lcan be measured accurately.

[0015] Further, a temperature sensor 54 is disposed near the shunt resistor 12. The temperature sensor 54 is connected to an analog front end 53 for temperature measurement. The analog front end 53 for temperature measurement receives a temperature measurement signal T S When the input is input, the waveform is shaped, noise is removed, and the temperature measurement signal T S Output.

[0016] The DSP51 outputs the temperature measurement signal T S The load current I flows through the shunt resistor 12 according to L , the resistance value R of shunt resistor 12 S and outputs the corrected signal to the MCU 57. The DSP 51 functions as the signal processing circuit 14 shown in FIG.

[0017] On the other hand, an integrated circuit 55 for monitoring the battery cells is connected to the battery 58. The integrated circuit 55 monitors the voltage V C The integrated circuit 55 is provided to monitor the battery 58 and measure the remaining battery capacity (SOC). A temperature sensor 56 is disposed near the battery 58 and is connected to the integrated circuit 55. The integrated circuit 55 receives a temperature measurement signal T CELL When you input CELL Depending on the battery cell voltage V C The integrated circuit 55 corrects the temperature measurement signal T CELL The MCU57 sends the temperature measurement signal T CELL Depending on the battery cell voltage V C may be corrected.

[0018] The MCU57 receives the load current I L , the resistance value R of shunt resistor 12 S Therefore, the MCU 57 receives the resistance value R S A load current I flows through the battery cells constituting the battery 58 according to L This information can be measured accurately.

[0019] The components of the shunt resistance measurement circuit 1 will be described below with reference to FIG. 1. The shunt resistance measurement circuit 1 shown in FIG. S The shunt resistance measurement circuit 1 includes a control circuit 10, a switching power supply circuit 11, a voltage measurement circuit 13, a signal processing circuit 14 using a DSP 51, and a mixer 15, and is connected to a shunt resistor 12. The shunt resistance measurement circuit 1 measures the resistance R S When measuring, the control circuit 10 turns off the relay 59 and supplies the AC carrier signal S C and AC modulation signal S M In practice, a driver circuit 11a is configured between the switching power supply circuit 11 and the mixer 15 (see below), but the driver circuit 11a is omitted from FIG. 1 and other figures which show the characteristic parts of the present disclosure in the form of a block diagram.

[0020] Carrier signal S C is a frequency f of several hundred kHz, for example, about 100 kHz. C The square wave signal is of frequency f C The reciprocal of period T C The modulation signal S M is the carrier signal S C Lower frequency f M The signal is, for example, a rectangular wave signal of several hundred Hz. M The reciprocal of period T M The mixer 15 mixes the carrier signal S C and the modulating signal S M After multiplication, the modulated carrier signal S MC and outputs it to the switching power supply circuit 11.

[0021] Modulated carrier signal S MC is used as a signal for driving the switching power supply circuit 11. The modulated carrier signal S MC is a relatively low frequency modulating signal S M A relatively high frequency carrier signal S CIn this application, a signal having the above relationship is referred to as a carrier signal S C , the modulated signal S M These carrier signals S C , the modulated signal S M The name is not limited to this name.

[0022] The switching power supply circuit 11 shown in FIG. 3 is driven through a driver circuit 11a, which outputs a drive signal S M1 , S M2 , S M3 By inputting the above, the switching elements M1 to M3 are driven, and the AC excitation current I E The switching elements M1 and M2 are configured with P-channel MOSFETs, and the switching element M3 is configured with an N-channel MOSFET. Although an example of the configuration of the switching power supply circuit 11 is shown in FIG. 3, the configuration of the switching power supply circuit 11 is not limited to this example.

[0023] The switching power supply circuit 11 illustrated in FIG. 3 is configured as a synchronous rectification type switching power supply, and a power supply V 0 The power supply V has two switching elements M2 and M3 connected in series between a power supply node Ni and a ground node Ng, and an inductor L1 disposed between an intermediate node Na between the two switching elements M2 and M3 and an output node No of the switching power supply circuit 11. 0 is generated by stepping down the power supply of the battery 58. Since the impedance of the shunt resistor 12 that applies the AC excitation current IE is small at several tens of micro-ohms, IE is about 1 A. Therefore, by disposing the switching element M3 and using an element that satisfies the condition of a lower on-resistance as a synchronous rectification type switching power supply configuration, it is possible to output power under conditions of lower power consumption than in the case of diode rectification.

[0024] Furthermore, the switching power supply circuit 11 includes a charge sampling switching element M1 connected in series between the DC power supply node Ni and the upstream switching element M2. The switching power supply circuit 11 also includes a capacitor C1 disposed in a charge sampling stage between an intermediate node Nb between the upstream switching element M2 and the charge sampling switching element M1 and a ground node Ng.

[0025] FIG. 4 shows the AC excitation current I E FIG. 5 shows an enlarged view of a portion A of the timing chart of FIG. 1. The driver circuit 11a receives the modulated carrier signal S MC When the carrier signal S C A drive signal S that becomes a high voltage for a predetermined period of time from the generation timing M1 At the same time, the drive signal S M1 A driving signal S that changes voltage complementary to M3 Output.

[0026] Drive signal S M1 The driving signal S drives the gate of the switching element M1, which is a P-channel MOSFET. M3 The driver circuit 11a drives the gate of the switching element M3, which is an N-channel MOSFET. Therefore, the switching elements M1 and M3 are simultaneously turned on or off. M1 and S M3 The drive signal S becomes low voltage only for a part of the time while it is an off drive signal. M2 The drive signal S M2 is applied to the gate of the switching element M2, which is a P-channel MOSFET.

[0027] When the switching elements M1 and M3 are in the ON state, the switching element M2 is maintained in the OFF state. In this case, the capacitor C1 is charged from the node Ni through the switching element M1. Conversely, when the switching elements M1 and M3 are in the OFF state, the switching element M2 is in the ON state only for a part of the time.

[0028] The switching power supply circuit 11 supplies AC excitation current I E As a result, the AC excitation current I E As shown in Figure 4, the modulated signal S M A small amplitude carrier signal S is added to a large amplitude waveform of frequency fm. C The AC excitation current I E is the modulating signal S M The amplitude of the waveform of the carrier signal S C In other words, the switching power supply circuit 11 generates the carrier signal S so as to have a larger amplitude than that of the frequency of the carrier signal S in order to ensure a predetermined supply current. C While maintaining the switching frequency at the frequency fc, the low-frequency AC excitation current I E Output.

[0029] The switching power supply circuit 11 is provided with a charge sampling stage consisting of a switching element M1 and a capacitor C1. This allows a large current to be supplied from the capacitor C1 of the charge sampling stage, and the switching power supply circuit 11 can be configured with a low power supply capacity. As a result, the switching power supply circuit 11 can be configured at low cost.

[0030] In addition, since a large current during operation of the switching power supply circuit 11 can be supplied from the capacitor C1 of the charge sampling stage, fluctuations in the power output of the switching power supply circuit 11 can be suppressed. As a result, interference with other circuits can be suppressed, and the resistance value R of the shunt resistor 12 can be reduced. S can be measured with high accuracy.

[0031] 1, the power output of the switching power supply circuit 11 is applied to the shunt resistor 12, and the first voltage measurement circuit 13 measures the voltage across the shunt resistor 12. The first voltage measurement circuit 13 includes an AD converter 18 equipped with a ΔΣ modulator. The control circuit 10 includes a timing generation circuit 10a, and outputs the sampling timing of the AD converter 18 of the first voltage measurement circuit 13 to the first voltage measurement circuit 13 as a timing signal.

[0032] When the timing signal is input, the first voltage measurement circuit 13 samples and holds the measured voltage and outputs it to the signal processing circuit 14. This allows the control circuit 10 to control so as to synchronize the power output of the switching power supply circuit 11 with the measurement timing of the voltage measurement circuits 13, 13a. Also, the first voltage measurement circuit 13 can measure the voltage applied to the shunt resistor 12 at a timing synchronized with the power output of the switching power supply circuit 11, and the resistance value R of the shunt resistor 12 can be calculated. S and AC excitation current I E The multiplied value of can be obtained.

[0033] The signal processing circuit 14 is configured by a DSP 51 (see FIG. 2) equipped with a volatile memory and a non-volatile memory. The signal processing circuit 14 processes a signal based on the voltage measured by the first voltage measuring circuit 13 and calculates the resistance value R S The memory is configured as a non-transient real recording medium. For example, the signal processing circuit 14 processes a signal in synchronization with the output frequency of the digital output of the AD converter 18 of the first voltage measuring circuit 13, and the modulated signal S M AC excitation current I E (See a specific example of the synchronous detection circuit 14a in the embodiment described later.) E This allows the voltage across the shunt resistor 12 to be measured with high accuracy.

[0034] Modulated carrier signal S MC is, for example, a relatively low frequency modulating signal S M A relatively high frequency carrier signal S CTherefore, the modulated signal S M A carrier signal S with a higher frequency than C In accordance with this embodiment, the switching power supply circuit 11 is designed to output a modulated carrier signal S. In the case where the switching elements M1 to M3 are selected to correspond to a low frequency, the element values ​​of the inductor L1 and the capacitor C1 become large, resulting in high costs. MC By driving with E can be produced easily and at low cost.

[0035] <Summary of this embodiment> According to this embodiment, the carrier signal S output by the control circuit 10 C and the modulating signal S M The modulated carrier signal S multiplied by MC is applied to the switching power supply circuit 11 to drive the switching power supply circuit 11, and an AC excitation current I E A power supply including the above is applied to the shunt resistor 12. The signal processing circuit 14 calculates the resistance R S As a result, the resistance value R of the shunt resistor 12 is calculated based on the AC excitation current IE generated by the switching power supply circuit 11. S can be measured.

[0036] Also, the power supply V 0 is a step-down power supply for the battery 58, and the switching power supply circuit 11 is a power supply V 0 Using the AC excitation current I E Therefore, the power consumption can be reduced and the cost can be reduced. The switching power supply circuit 11 generates the AC excitation current I without providing a separate power supply circuit such as an extra regulator. E Since the above-mentioned can be generated, the configuration can be made with low power consumption and low cost.

[0037] According to this embodiment, the carrier signal S C The modulated signal SM This embodiment can provide AC excitation at a relatively low frequency, thereby preventing the influence of the skin effect of the shunt resistor 12 as much as possible, and can minimize measurement errors due to the influence of the skin effect of the shunt resistor 12, thereby enabling the resistance value RS of the shunt resistor 12 to be measured with high accuracy. M Using the AC excitation current I E Since the inductor L1 and the capacitor C1 have small capacitance, the inductor L1 and the capacitor C1 can be constructed at low cost.

[0038] Second embodiment The second embodiment will be described with reference to Figs. 6 and 7. In addition to the components of the shunt resistance measurement circuit 1, the shunt resistance measurement circuit 201 also includes a reference resistor 12a and a second voltage measurement circuit 13a. The reference resistor 12a is connected in series with the shunt resistor 12, and the output of the power supply of the switching power supply circuit 11 is applied to the reference resistor 12a. It is desirable that the material of the reference resistor 12a contains tantalum nitride, titanium nitride, or nitride. By forming the reference resistor 12a using a material that has small changes in characteristics due to temperature changes and a material that has small durability deterioration, the resistance value R of the shunt resistor 12 can be reduced. S can be measured with high accuracy.

[0039] A reference resistor 12a and a shunt resistor 12 are connected in series between a power output node No and a ground node Ng of the switching power supply circuit 11. The reference resistor 12a is a highly accurate resistor that serves as a measurement standard, and its resistance value is set to 2 to 3 to 6 orders of magnitude greater than the resistance value of the shunt resistor 12, for example, about 10Ω. As will be described later, the resistance value R of the shunt resistor 12 is calculated by taking the ratio between the shunt resistor 12 and the reference resistor 12a. S Therefore, it is easier to measure by selecting resistance values ​​of approximately the same value. However, the commonly available high-precision, low-degradation standard resistor 12a has a resistance value of 10 Ω or more, so the resistance value R REF1 , R S are composed of resistances that differ greatly from each other.

[0040] The second voltage measurement circuit 13a measures the voltage across the reference resistor 12a. The control circuit 10 controls the timing generation circuit 10a to synchronize the power output of the switching power supply circuit 11 with the measurement timing of the first voltage measurement circuit 13 and the second voltage measurement circuit 13a. The timing at which the second voltage measurement circuit 13a measures the voltage across the reference resistor 12a is synchronized with the timing at which the first voltage measurement circuit 13 measures the voltage across the shunt resistor 12. Since the first voltage measurement circuit 13 and the second voltage measurement circuit 13a are synchronized on a sample basis, it is not necessary to synchronize the signal processing circuit 14 and the control circuit 10. This makes it possible to reduce wiring and other synchronization circuits.

[0041] The signal processing circuit 14 processes the signal based on the voltage measured by the first voltage measurement circuit 13 and the voltage measured by the second voltage measurement circuit 13a, and measures the resistance value Rs of the shunt resistor 12. The other configurations are the same as those in the first embodiment.

[0042] According to this configuration, since the reference resistor 12a is used as the measurement reference, a highly accurate reference current generating circuit is not required, and the configuration can be made at low cost. Since the measurement timing of the first voltage measurement circuit 13 and the second voltage measurement circuit 13a is synchronized with the power output of the switching power supply circuit 11, the signal processing circuit 14 can perform synchronous detection with high accuracy, and the AC excitation current I E The main component of the modulation signal S M It is possible to eliminate noise other than the fundamental frequency of the amplifier.

[0043] The first voltage measurement circuit 13 measures the AC excitation current I E The second voltage measurement circuit 13a is provided with an AD converter 18 that measures the voltage across the shunt resistor 12 by the AC excitation current I E and an AD converter 18a that measures the voltage across the reference resistor 12a and digitally converts the voltage measurement result of the reference resistor 12a.

[0044] The signal processing circuit 14 processes signals in synchronization with the output frequency of the digital outputs of the AD converter 18 of the first voltage measurement circuit 13 and the AD converter 18a of the second voltage measurement circuit 13a, and outputs a modulated signal S M AC excitation current I E The frequency is synchronously detected using the same frequency as the frequency of the signal.

[0045] 7, the signal processing circuit 14 includes a synchronous detection circuit 14a, a divider 43, and a multiplier 44. The synchronous detection circuit 14a includes mixers 21i, 21q, 22i, and 22q, filters 31i, 31q, 32i, and 32q, and absolute value calculators 41 and .

[0046] When the mixers 21i and 21q receive the measurement result of the first voltage measurement circuit 13, they mix (multiply) the sample synchronization signals of the first voltage measurement circuit 13 and the second voltage measurement circuit 13a as signal data that are out of phase with each other by 90°, and output the mixed data to the filters 31i and 31q, respectively. The filters 31i and 31q are low-pass filters that band-limit the signal data that is input, and output the signal data that has passed the low frequency range to the absolute value calculator 41.

[0047] The outputs of the filters 31i and 31q are components representing the real part Re and the imaginary part Im, respectively, and the absolute value calculator 41 calculates the square root of the sum of the squares of the real part Re and the imaginary part Im to output the synchronous detection circuit 14a. This result is output to a divider 43. The synchronous detection circuit 14a calculates the AC excitation current I E × Resistance value R of shunt resistor 12 S The measurement result of the shunt resistor 12 calculated above is output to the divider 43.

[0048] On the other hand, when the mixers 22i and 22q receive the measurement result of the second voltage measurement circuit 13a, they mix (multiply) the sample synchronization signals of the first voltage measurement circuit 13 and the second voltage measurement circuit 13a as signal data that are out of phase with each other by 90°, and output the mixed data to the filters 32i and 32q, respectively. The filters 32i and 32q are low-pass filters that band-limit the signal data that is input, and output the signal data that has passed through the low frequency range to the absolute value calculator 42.

[0049] The output voltages of the filters 32i and 32q are components representing the real part Re and the imaginary part Im, respectively, and the absolute value calculator 42 calculates the square root of the sum of the squares of the real part Re and the imaginary part Im to output the synchronous detection circuit 14a. This result is output to a divider 43. The synchronous detection circuit 14a calculates the AC excitation current I E × Resistance value R of reference resistor 12a REF1 Measurement result of reference resistor 12a calculated by I E ×R REF1 is output to the divider 43.

[0050] The signal processing circuit 14 performs calculations using a divider 43 and a multiplier 44 based on the two output results of the synchronous detection circuit 14a. E ×R S The measurement result of the reference resistor 12a is I E ×R REF1 The divided value is multiplied by the reference resistance value R of the reference resistor 12a recorded in advance using a divider 43. REF1 is multiplied by a multiplier 44 to obtain the resistance value R S Measure.

[0051] Reference resistance value R of reference resistor 12a REF1 is measured in advance when the reference resistor 12a is manufactured or inspected, and is recorded in advance in a non-volatile memory (not shown) of the signal processing circuit 14. Therefore, the signal processing circuit 14 executes the above-mentioned predetermined calculation using the divider 43 and the multiplier 44 to obtain the AC excitation current I E Therefore, the effect of the AC excitation current I E It is possible to eliminate the influence of noise other than the main component included in the first voltage measurement circuit 13 and the second voltage measurement circuit 13a, such as disturbances and low-frequency noise (1 / f noise, offset, etc.). As a result, the resistance value R S can be measured with high accuracy.

[0052] Third embodiment The third embodiment will be described with reference to Fig. 8. The specific configuration of the switching power supply circuit 11 shown in Fig. 3 of the first embodiment is sufficiently effective even when the reference resistor 12a as shown in the second embodiment is connected in series to the shunt resistor 12. Fig. 8 shows a specific configuration of a shunt resistance value measuring circuit 301 to which the specific configuration of the switching power supply circuit 11 in Fig. 3 is applied and to which the reference resistor 12a is applied.

[0053] According to the configuration of this shunt resistance value measuring circuit 301, the resistance value R of the reference resistor 12a to which the AC excitation current IE is applied is REF1 The impedance of the shunt resistor 12 is small at 10 Ω, and the resistance R S Therefore, by using an element that satisfies the condition of a lower on-resistance as the switching element M3, the switching power supply circuit 11 can output power with lower power consumption than in the form of so-called diode rectification.

[0054] Furthermore, by providing a charge sampling stage consisting of switching element M1 and capacitor C1, a large current can be supplied from capacitor C1 of the charge sampling stage, and the power supply capacity of switching power supply circuit 11 can be reduced. As a result, switching power supply circuit 11 can be constructed at low cost.

[0055] In addition, since the large current during operation of the switching power supply circuit 11 can be supplied from the capacitor C1 of the charge sampling stage, it is possible to suppress fluctuations in the power output of the switching power supply circuit 11. As a result, interference with other circuits can be suppressed, and the resistance value of the shunt resistor 12 can be measured with high accuracy.

[0056] (Fourth embodiment) The fourth embodiment will be described with reference to Fig. 9. A shunt resistance value measuring circuit 401 shown in Fig. 9 includes a first reference resistor 12a and a second reference resistor 12b. The first reference resistor 12a and the second reference resistor 12b are connected in series to the shunt resistor 12. In this embodiment, the resistance value R of the shunt resistor 12 is calculated by taking the ratio between the reference resistor 12a and the reference resistor 12b and the ratio between the shunt resistor 12 and the reference resistor 12b. S Therefore, it is easier to measure by selecting resistance values ​​of approximately the same value. However, the commonly available high-precision, low-degradation standard resistor 12a has a resistance value of 10 Ω or more, so the resistance value R REF1 , R S The resistance ratio is made up of resistors that are significantly different from each other. If the resistance ratio becomes too small, the signal entering the voltage measurement circuit becomes small, the signal-to-noise ratio becomes poor, and the resistance measurement accuracy deteriorates. Therefore, R is set to a large resistance ratio. REF2 By selecting a resistor of several tens of milliohms, which is between the shunt resistor 12 of several tens of microohms and the reference resistor 12a of 10 ohms or more, the resistance value can be measured with high accuracy. As a result, the resistance value R REF1 , R REF2 , R S The relationship between R REF1 >>R REF2 >>R S The resistance value R REF1 and resistance value R REF2 The relationship between the resistance value R REF2 and resistance value R S The relationship between them is preferably set to a difference of one to two digits, or two to three digits, for example, about 10:1 to 100:1, or 100:1 to 1000:1.

[0057] The shunt resistance measurement circuit 401 also includes a DC excitation circuit 16 as a power supply different from the switching power supply circuit 11. The shunt resistance measurement circuit 401 also includes a multiplexer 19. The DC excitation circuit 16 is configured with a regulator that can turn on and off the output based on the control of the control circuit 10, and outputs a DC current I E1 A first reference resistor 12a, a second reference resistor 12b, and a shunt resistor 12 are connected in series between the DC excitation circuit 16 and a ground node Ng.

[0058] A multiplexer 19 is arranged between the first reference resistor 12a, the second reference resistor 12b, and the shunt resistor 12 and the first voltage measurement circuit 13 and the second voltage measurement circuit 13a. The multiplexer 19 is configured to be capable of switching between input and output based on the control of the control circuit 10. In this embodiment, the three-series circuit of the second reference resistor 12b, the first reference resistor 12a, and the shunt resistor 12 is configured to be capable of supplying power from a DC excitation circuit 16.

[0059] The material of the first reference resistor 12a and the second reference resistor 12b preferably includes tantalum nitride, titanium nitride, or nitride. By forming the first reference resistor 12a and the second reference resistor 12b using a material that has little characteristic change due to temperature change and little durability deterioration, the resistance value R of the shunt resistor 12 can be reduced. S can be measured with high accuracy.

[0060] The signal processing circuit 14 measures the resistance R of the shunt resistor 12 through the first measurement step and the second measurement step. S In the first measurement step, the control circuit 10 stops the operation of the switching power supply circuit 11 by turning off all of the switching elements M1 to M3 that configure the switching power supply circuit 11. Then, the control circuit 10 measures the current I E1 In addition, the control circuit 10 switches the input and output of the multiplexer 19 to cause the second voltage measurement circuit 13a to measure the voltage across the first reference resistor 12a and the first voltage measurement circuit 13 to measure the voltage across the second reference resistor 12b.

[0061] In the first measurement step, the signal processing circuit 14 processes a signal based on the measurement results of the first reference resistor 12a and the second reference resistor 12b measured by the second voltage measurement circuit 13a and the first voltage measurement circuit 13, respectively, to obtain a resistance value R REF1 and the resistance value R of the second reference resistor 12b REF2 Measure.

[0062] In the first measurement step, the signal processing circuit 14 measures the resistance value R of the first reference resistor 12a using the DC measurement path 14c shown in FIG. REF1 and the resistance value R of the second reference resistor 12b REF2 The resistance ratio of these is measured. In the DC measurement path 14c, filters 45 and 46 are formed, as well as adders / subtractors 47 and 48 and a divider 49.

[0063] Filter 45 passes the low frequency components of the voltage measured by first voltage measurement circuit 13 and cuts out high frequency noise exceeding the DC component. Filter 46 passes the low frequency components of the voltage measured by second voltage measurement circuit 13a and cuts out high frequency noise exceeding the DC component.

[0064] Adder-subtractor 47 subtracts a pre-recorded offset from the DC component of the measured voltage of first voltage measurement circuit 13. Adder-subtractor 48 subtracts a pre-recorded offset from the DC component of the measured voltage of second voltage measurement circuit 13a. This offset is added or subtracted to minimize the influence of low-frequency noise (1 / f noise, offset, etc.) of first voltage measurement circuit 13 and second voltage measurement circuit 13a.

[0065] The divider 49 divides the output of the adder / subtractor 48 by the output of the adder / subtractor 47. As a result, the divider 49 divides the current I E1 While eliminating the influence of REF2 The resistance value R of the first reference resistor 12a REF1 The result of dividing by R REF2 / R REF1 The output of the divider 49 is output to the multiplier 44a.

[0066] On the other hand, in the second measurement step, the signal processing circuit 14 performs signal processing based on the measured voltage across the second reference resistor 12b and the measured voltage across the shunt resistor 12 to obtain the resistance value R REF2 and the resistance value R of shunt resistor 12 S In the second measurement step, it is preferable that the signal processing circuit 14 measures the resistance ratio using the AC measurement path 14b.

[0067] The AC measurement path 14b includes a synchronous detection circuit 14a and a divider 43. In the second measurement step, the control circuit 10 detects the AC excitation current I E and the current I E1 The control circuit 10 switches the input / output of the multiplexer 19 to cause the second voltage measurement circuit 13a to measure the voltage across the second reference resistor 12b and the first voltage measurement circuit 13 to measure the voltage across the shunt resistor 12.

[0068] When the synchronous detection circuit 14a performs synchronous detection by the operation described in the above embodiment, the AC excitation current I E × (resistance value R of the second reference resistor 12b) REF2 ) to the divider 43, and the AC excitation current I E × (resistance value R of shunt resistor 12) S ) to the divider 43. The divider 43 calculates the ratio of these values ​​to obtain the resistance value R S and the resistance value R of the second reference resistor 12b REF2 Resistance ratio R S / R REF2 The resistor ratio R S / R REF2 By multiplying this by a specified gain adjustment (GainCal), it can be adjusted to a value that is easy to handle in practice.

[0069] The signal processing circuit 14 includes a multiplier 44a provided after the DC measurement path 14c and the AC measurement path 14b. The multiplier 44a multiplies the resistance value R REF1 and R REF2 Resistance ratio R REF2 / R REF1 and the resistance value R measured in the second measurement step. REF2 and R S Resistance ratio R S / R REF2 By multiplying by S / R REF1 The multiplier 44a calculates the resistance ratio R S / R REF1 The reference resistance value R REF1 The resistance value R of shunt resistor 12 is calculated by multiplying S In this way, the resistance value R of the shunt resistor 12 can be measured. S can be measured.

[0070] As mentioned above, the resistance R REF1 and resistance value R REF2 The relationship between the resistance value R REF2 and resistance value R S The relationship between the first and second reference resistors 12a, 12b, and the shunt resistor 12 is set to a difference of one to two digits, or two to three digits, for example, about 10:1 to 100:1, or about 100:1 to 1000:1. The first voltage measurement circuit 13 and the second voltage measurement circuit 13a measure the resistance values ​​R REF1 , R REF1 , R S The signal processing circuit 14 selectively measures the resistance value R REF1 , R REF2 , R S The resistance value R of shunt resistor 12 is calculated using the voltage ratio and resistance ratio of the two terminal voltages. S is being measured.

[0071] According to this configuration, the difference between the inter-terminal voltages measured by the first voltage measurement circuit 13 and the second voltage measurement circuit 13a can be suppressed to, for example, about −60 dB, and the resistance value R S Even if the measurement is performed, the effect of noise can be suppressed as much as possible.

[0072] As described above, the resistance value R of the first reference resistor 12a serving as a reference REF1 is set to 10 Ω, a high-precision resistor, and the resistance value R S However, as shown in the first and second measurement steps, the resistance value R of the shunt resistor 12 is measured in two steps. SBy measuring the resistance R of the shunt resistor 12, it is possible to cancel and reduce the influence of various noises generated in the first voltage measurement circuit 13 and the second voltage measurement circuit 13a. S can be measured with high accuracy.

[0073] According to this embodiment, three resistors can be switched by the multiplexer 19, and voltages can be measured by the two voltage measurement circuits 13, 13a, so that the configuration can be made at low cost. Furthermore, when the signal processing circuit 14 executes the first measurement step, the operation of the switching power supply circuit 11 used in the second measurement step is stopped. This is because the effect of the output impedance of the switching power supply circuit 11 is eliminated, and the resistance value R of the shunt resistor 12 is S This is because it is possible to reduce measurement errors.

[0074] When the output of the switching power supply circuit 11 is directly connected to the first reference resistor 12a as in this embodiment, the output impedance of the switching power supply circuit 11 can be kept high by turning off all of the switching elements M1 to M3 of the switching power supply circuit 11. As a result, the resistance value R of the shunt resistor 12 can be kept high while minimizing the influence of the switching power supply circuit 11. S It should be noted that an additional switch may be provided between the output node No of the switching power supply circuit 11 and the first reference resistor 12a.

[0075] <Modification> In the previous example, the resistance value R S However, the present invention is not limited to this example, and may be divided into three or more measurement steps. In other words, it is possible to configure a configuration in which other reference resistors, such as a third reference resistor, are connected in series to the shunt resistor 12, and the voltages of these reference resistors are measured two by two to measure the resistance ratio between them, and finally multiplying them to obtain the resistance value R of the shunt resistor 12. S It is possible to measure the above. A detailed explanation of this will be omitted.

[0076] Fifth embodiment The fifth embodiment will be described with reference to Fig. 10. Differences from the fourth embodiment will be described and descriptions of the same parts will be omitted. Fig. 10 shows the overall configuration of a shunt resistance value measurement circuit 501, and Fig. 11 shows details of a signal processing circuit 514. As shown in Fig. 10, the shunt resistance value measurement circuit 501 is configured with an AC excitation circuit 516 as a power supply in place of the DC excitation circuit 16 described in the previous embodiment.

[0077] The AC excitation circuit 516 is configured to connect the configuration of the control circuit 10 described in the above embodiment to generate an AC excitation current I E1 The AC excitation circuit 516 generates the modulation signal S M In this case, the linear regulator 516a is configured to receive the input DC voltage V IN is input to the switching element M4, and a modulation signal S given from the control circuit 10 is M By toggling the switching element M4 with E1 can be generated.

[0078] The AC excitation circuit 516 receives the modulation signal S output from the control circuit 10. M The switching element M4 may be driven by the linear regulator 516a. By using such a linear regulator 516a, the power supply capacity of the AC excitation circuit 516 can be reduced, and a low-cost product can be used. This embodiment has the same effects as the previous embodiment.

[0079] Moreover, the shunt resistance value measuring circuit 501 includes a signal processing circuit 514 instead of the signal processing circuit 14. As shown in FIG. 10, the signal processing circuit 514 includes an AC measurement path 14b without including a DC measurement path 14c. The signal processing circuit 514 may also be configured in the DSP 51. In this embodiment, in the first measurement step, the current to be applied to the first reference resistor 12a and the second reference resistor 12b is an AC excitation current I E1 It is recommended to do so.

[0080] An AC excitation circuit 516 generates an AC excitation current IE1 In this case, the synchronous detection process of the signal processing circuit 514 in the first measurement step and the second measurement step can be shared. M The control circuit 10 for generating the signal can be shared, and can be implemented at low cost.

[0081] The signal processing circuit 514 measures both the first measurement step and the second measurement step through the synchronous detection circuit 14a of the AC measurement path 14b. If synchronous detection is performed in the first measurement step in addition to the second measurement step, the AC excitation current I E1 Noise other than the main component, such as disturbance and low-frequency noise (1 / f noise, offset, etc.) of the first voltage measurement circuit 13 and the second voltage measurement circuit 13a, can be removed, allowing for highly accurate measurement.

[0082] The signal processing circuit 514 includes dividers 43a and 43b and a multiplier 44a. In the first measurement step, the divider 43a multiplies the output value I E1 ×R REF2 The output value I of the absolute value calculator 42 E1 ×R REF1 By dividing by and multiplying by the gain, the resistance value R of the second reference resistor 12b is obtained. REF2 The resistance value R of the first reference resistor 12a REF1 The divider 43a outputs the division result to the multiplier 44a. In the second measurement step, the signal processing circuit 514 divides the output value I of the absolute value calculator 41 by E ×R S The output value I of the absolute value calculator 42 E ×R REF2 By dividing by and multiplying by the gain, the resistance value R of shunt resistor 12 is S The resistance value R of the second reference resistor 12b REF2 The divider 43b outputs the result of this division to the multiplier 44a.

[0083] The signal processing circuit 514 multiplies the measurement result of the first measurement step by the measurement result of the second measurement step using the multiplier 44a, and multiplies the measurement result of the first measurement step by the reference resistance value RREF1 The resistance value R of shunt resistor 12 is calculated by multiplying S Since the output of one of the first voltage measurement circuit 13 and the second voltage measurement circuit 13a is divided by the output of the other, the AC excitation current I E , I E1 The noise contained in the shunt resistor 12 can be removed. S The elements of the signal processing circuit 514 used in the first measurement step and the second measurement step (for example, the multiplier 44a) can be shared, and can be implemented at low cost.

[0084] Sixth embodiment The sixth embodiment will be described with reference to Fig. 11 and Fig. 12. Fig. 11 and Fig. 12 show a desirable hardware configuration of the shunt resistance measurement circuits 401a, 401b of the fourth embodiment. As shown in Fig. 11 or 12, each block constituting the shunt resistance measurement circuits 401a, 401b may be configured as separate hardware components, such as an ASIC 50, a DSP 51, and a current excitation circuit 52, which serve as integrated circuits.

[0085] As shown in the configuration example in FIG. 11, the ASIC 50 includes a driver circuit 11a, a control circuit 10 including a timing generation circuit 10a, a first voltage measurement circuit 13, a second voltage measurement circuit 13a, and a multiplexer 19.

[0086] The first voltage measurement circuit 13 includes a differential switched capacitor amplifier 17 and an AD converter 18 equipped with a ΔΣ modulator in the downstream thereof, forming an analog front-end 50a. The second voltage measurement circuit 13a includes a differential switched capacitor amplifier 17a and an AD converter 18a equipped with a ΔΣ modulator in the downstream thereof, forming an analog front-end 50a.

[0087] As shown in Fig. 11, the first reference resistor 12a, the second reference resistor 12b, and the anti-aliasing filters 20a, 20b, and 20 may be provided externally to the ASIC 50, but it is preferable to configure the first reference resistor 12a in the ASIC 50 as shown in Fig. 12. In particular, it is preferable that the first reference resistor 12a is mounted on the same ASIC 50 (equivalent to an integrated circuit) on which the first voltage measurement circuit 13 and the second voltage measurement circuit 13a are mounted. By mounting the first reference resistor 12a on the same ASIC 50 on which the first voltage measurement circuit 13 and the second voltage measurement circuit 13a are mounted, it becomes unnecessary to separately provide an external reference resistor, and the first reference resistor 12a can be configured in a small area.

[0088] 12 also includes an anti-aliasing filter 20a. The anti-aliasing filter 20a is configured between the first reference resistor 12a and the multiplexer 19, and cuts frequency components higher than the Nyquist frequency before the measurement voltage of the first reference resistor 12a is input to the AD converters 18 and 18a.

[0089] Anti-aliasing filters 20b, 20 are configured outside the ASIC 50. The anti-aliasing filter 20b is configured between the second reference resistor 12b and the multiplexer 19, and cuts off frequency components higher than the Nyquist frequency before the measurement voltage of the second reference resistor 12b is input to the AD converters 18, 18a. The anti-aliasing filter 20 is configured between the shunt resistor 12 and the multiplexer 19, and cuts off frequency components higher than the Nyquist frequency before the measurement voltage of the shunt resistor 12 is input to the AD converters 18, 18a.

[0090] The current excitation circuit 52 includes a switching power supply circuit 11 as an AC excitation circuit, and also includes a DC excitation circuit 16. In addition, in Fig. 11 and Fig. 12, the same parts as those in the fourth embodiment are denoted by the same reference numerals, and the description of the same parts will be omitted. This embodiment also provides the same effects as the above-mentioned embodiment.

[0091] Seventh embodiment The seventh embodiment will be described with reference to Figs. 13 and 14. As described in the first embodiment, the carrier signal S C When the frequency fc of the modulated signal S overlaps with the frequency range in which the skin effect of the shunt resistor 12 is small, M A shunt resistance value measuring circuit 701 may be configured as shown in FIG. 13 without providing any related circuitry, such as the mixer 15.

[0092] The shunt resistance value measuring circuit 701 of this embodiment includes a control circuit 710, a switching power supply circuit 11, a first voltage measuring circuit 13, and a signal processing circuit 14. The control circuit 710 outputs an AC carrier signal S C The switching power supply circuit 11 includes switching elements M1 to M3 and outputs a carrier signal S C The switching elements M1 to M3 are driven based on a signal including E The output of the switching power supply circuit 11 is applied to the shunt resistor 12.

[0093] The first voltage measurement circuit 13 measures the voltage across the shunt resistor 12. The signal processing circuit 14 processes a signal based on the voltage measured by the first voltage measurement circuit 13 and outputs the resistance value R S The other configurations are the same as those of the above-mentioned embodiment, so the description thereof will be omitted.

[0094] The carrier signal S of the shunt resistance measurement circuit 701 C When the frequency is lowered to a frequency where the influence of the skin effect of the shunt resistor 12 is small, the element values ​​of the inductor L1 and the capacitor C1 tend to be larger than those normally used.

[0095] At this time, the sizes of the inductor L1 and the capacitor C1 constituting the switching power supply circuit 11 are adjusted while the carrier signal S C By driving the switching elements M1 to M3 with C Frequency f C where AC excitation current I E may be output.

[0096] As shown in FIG. 14 as a specific example of a shunt resistance value measuring circuit 701, the switching power supply circuit 11 receives a carrier signal S C The other configurations are similar to those of the above-described embodiments (particularly the fourth embodiment), and therefore the description thereof will be omitted.

[0097] According to this embodiment, the carrier signal S C For signal processing, the modulated signal S M Since the power required to generate an excitation current of this frequency is not required, power consumption can be reduced. Since the modulation circuit (for example, mixer 15) is not required, the configuration area can be reduced.

[0098] (Other embodiments) The present invention is not limited to the above-described embodiment, but can be implemented in various modifications and can be applied to various embodiments without departing from the spirit of the present invention. For example, the following modifications or extensions are possible. Each component is conceptual, and is not limited to the above-described embodiment.

[0099] The present disclosure includes the following inventions in addition to the inventions described in the claims. [1] A shunt resistance measurement circuit for a shunt-type current sensor that measures a resistance value of a shunt resistor (12), A control circuit (10; 710) that outputs a control signal including an AC carrier signal; a switching power supply circuit (11) that operates in response to the control signal; an output of a power supply of the switching power supply circuit is applied to the shunt resistor; a first voltage measurement circuit (13) that measures a voltage across the shunt resistor; A shunt resistance value measuring circuit for a shunt-type current sensor comprising: a signal processing circuit (14; 514) that processes a signal based on the measured voltage of the first voltage measuring circuit and measures the resistance value of the shunt resistor.

[0100] [2] The control circuit (10) outputs an AC modulated signal as the control signal in addition to the AC carrier signal, The switching power supply circuit (11) has a switching element, drives the switching element with a modulated carrier signal obtained by multiplying the carrier signal and a modulation signal, and outputs a power supply including an AC excitation current due to the modulated carrier signal. [1] A shunt resistance value measurement circuit for a shunt type current sensor.

[0101] [3] a reference resistor (12a) connected in series with the shunt resistor and to which an output of a power supply of the switching power supply circuit is applied; a second voltage measurement circuit (13a) that measures a voltage across the reference resistor; The signal processing circuit performs signal processing based on the measured voltage of the first voltage measurement circuit and the measured voltage of the second voltage measurement circuit, thereby measuring the resistance value of the shunt resistor [2].

[0102] [4] The control circuit controls so as to synchronize the power output of the switching power supply circuit with the measurement timing of the first voltage measurement circuit and the measurement timing of the second voltage measurement circuit [3].

[0103] [5] the first voltage measurement circuit includes an AD converter (18) that measures a voltage applied to the shunt resistor by the AC excitation current and digitally converts a voltage measurement result of the shunt resistor; the second voltage measurement circuit includes an AD converter (18a) that measures a voltage applied to the reference resistor by the AC excitation current and digitally converts a voltage measurement result of the reference resistor; The signal processing circuit processes signals in synchronization with the output frequency of the digital outputs of the AD converter of the first voltage measurement circuit and the AD converter of the second voltage measurement circuit, and performs synchronous detection at the same frequency as the frequency of the AC excitation current generated by the modulated signal. [3] or [4] A shunt resistance value measurement circuit for a shunt-type current sensor.

[0104] [6] The signal processing circuit measures the resistance value of the shunt resistor by dividing the measurement result of the shunt resistor by the measurement result of the reference resistor, and multiplying the divided value by a reference resistance value of a reference resistor that is recorded in advance.

[0105] [7] The switching power supply circuit is a shunt resistance measurement circuit for a shunt type current sensor according to any one of [1] to [6], comprising: two switching elements (M2, M3) connected in series between a DC power supply node and a ground node; and an inductor (L1) arranged between an intermediate node between the two switching elements and an output node of the switching power supply circuit.

[0106] [8] a charge sampling switching element (M1) connected in series between the DC power supply node and the upstream switching element (M2); The shunt resistance measurement circuit for a shunt-type current sensor according to [7] further comprises a capacitor (C1) arranged between an intermediate node between the upstream switching element and the charge sampling switching element and a ground node.

[0107] [9] The reference resistor is composed of a first reference resistor and a second reference resistor connected in series to the shunt resistor, and a second power supply (16; 516) is provided to a triple series circuit of the first reference resistor, the second reference resistor, and the shunt resistor; a first measurement step of measuring a resistance ratio between a resistance value of the first reference resistor and a resistance value of the second reference resistor based on a measurement voltage applied to the first reference resistor and the second reference resistor measured by the first voltage measurement circuit and the second voltage measurement circuit, respectively; a second measurement step of measuring a resistance ratio between a resistance value of the second reference resistor and a resistance value of the shunt resistor by performing signal processing based on a measured voltage applied to the second reference resistor and a measured voltage applied to the shunt resistor; A shunt resistance measurement circuit for a shunt-type current sensor comprising any one of [3] to [8].

[0108]

[10] The second power supply (516) outputs an AC excitation current using a linear regulator (516a) to which the modulation signal is applied. [9] A shunt resistance measurement circuit for a shunt-type current sensor.

[0109]

[11] The shunt resistance measurement circuit for a shunt-type current sensor according to [9] or

[10] , wherein the second power supply (516) makes the current applied to the first reference resistor and the second reference resistor in the first measurement step an AC excitation current.

[0110]

[12] The signal processing circuit includes: In the first measuring step, a resistance value of the second reference resistor is divided by a resistance value of the first reference resistor; In the second measuring step, a resistance value of the shunt resistor is divided by a resistance value of the second reference resistor; A shunt resistance measurement circuit for a shunt-type current sensor according to any one of [9] to

[11] , which measures the resistance value of the shunt resistor by multiplying the measurement result of the first measurement step by the measurement result of the second measurement step and by a pre-recorded reference resistance value of the first reference resistor.

[0111]

[13] The shunt resistance value measurement circuit for a shunt-type current sensor according to

[12] , wherein the power supply makes the current applied to the first reference resistor and the second reference resistor in the first measurement step an AC excitation current.

[0112]

[14] The shunt resistance value measuring circuit for a shunt-type current sensor according to any one of [9] to

[13] , wherein the first reference resistor is mounted on the same integrated circuit as the integrated circuit on which the first voltage measurement circuit is mounted.

[0113]

[15] The shunt resistance measurement circuit for a shunt-type current sensor according to any one of [9] to

[14] , wherein a material of the first reference resistor includes tantalum nitride, titanium nitride, or nitride.

[0114] The techniques described in the present disclosure may be implemented by a special purpose computer provided by configuring a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the techniques described in the present disclosure may be implemented by a special purpose computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the techniques described in the present disclosure may be implemented by one or more special purpose computers configured by a combination of a processor and memory programmed to perform one or more functions and a processor configured with one or more hardware logic circuits. Also, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions executed by the computer.

[0115] Although the present disclosure has been described based on the above-mentioned embodiment, it is understood that the present disclosure is not limited to the embodiment or the structure described in the embodiment. The present disclosure also includes various modifications and modifications within the equivalent range. In addition, various combinations and forms, and other combinations and forms including only one element, more than one element, or less than one element, are also within the scope and concept of the present disclosure. [Explanation of symbols]

[0116] In the drawings, 1, 201, 301, 401, 501, 601, and 701 indicate shunt resistance measuring circuits (shunt resistance measuring circuits for shunt-type current sensors), 10 and 710 indicate control circuits, 12 indicates a shunt resistor, 12a indicates a reference resistor (first reference resistor), 12b indicates a second reference resistor, 13 indicates a first voltage measuring circuit, 13a indicates a second voltage measuring circuit, and 14 and 514 indicate a signal processing circuit.

Claims

1. A shunt resistance measurement circuit for a shunt-type current sensor that measures a resistance value of a shunt resistor (12), A control circuit (10; 710) that outputs a control signal including an AC carrier signal; A switching power supply circuit (11) that operates in response to the control signal, an output of a power supply of the switching power supply circuit is applied to the shunt resistor; A first voltage measurement circuit (13) that measures a voltage across the shunt resistor; A shunt resistance value measuring circuit for a shunt-type current sensor comprising: a signal processing circuit (14; 514) that processes a signal based on the measured voltage of the first voltage measuring circuit and measures the resistance value of the shunt resistor.

2. The control circuit (10) outputs an AC modulated signal as the control signal in addition to the AC carrier signal, 2. The shunt resistance value measurement circuit for a shunt-type current sensor according to claim 1, wherein the switching power supply circuit (11) includes a switching element, drives the switching element with a modulated carrier signal obtained by multiplying the carrier signal and a modulation signal, and outputs a power supply including an AC excitation current due to the modulated carrier signal.

3. a reference resistor (12a) connected in series to the shunt resistor and to which an output of a power supply of the switching power supply circuit is applied; a second voltage measurement circuit (13a) for measuring a voltage across the reference resistor; 3. The shunt resistance measurement circuit for a shunt-type current sensor according to claim 2, wherein the signal processing circuit processes a signal based on the measured voltage of the first voltage measurement circuit and the measured voltage of the second voltage measurement circuit to measure the resistance value of the shunt resistor.

4. 4. The shunt resistance value measurement circuit for a shunt type current sensor according to claim 3, wherein the control circuit controls so as to synchronize the power output of the switching power supply circuit with the measurement timing of the first voltage measurement circuit and the measurement timing of the second voltage measurement circuit.

5. the first voltage measurement circuit includes an AD converter (18) that measures a voltage applied to the shunt resistor by the AC excitation current and digitally converts a voltage measurement result of the shunt resistor; the second voltage measurement circuit includes an AD converter (18a) that measures a voltage applied to the reference resistor by the AC excitation current and digitally converts a voltage measurement result of the reference resistor; 5. The shunt resistance value measurement circuit for a shunt type current sensor as described in claim 4, wherein the signal processing circuit processes signals in synchronization with the output frequency of the digital outputs of the AD converter of the first voltage measurement circuit and the AD converter of the second voltage measurement circuit, and performs synchronous detection at the same frequency as the frequency of the AC excitation current generated by the modulated signal.

6. 6. The shunt resistance measurement circuit for a shunt-type current sensor as described in claim 5, wherein the signal processing circuit measures the resistance value of the shunt resistor by dividing the measurement result of the shunt resistor by the measurement result of the reference resistor and multiplying the divided value by a reference resistance value of a reference resistor that is recorded in advance.

7. 7. The shunt resistance measurement circuit for a shunt type current sensor as described in claim 6, wherein the switching power supply circuit comprises two switching elements (M2, M3) connected in series between a DC power supply node and a ground node, and an inductor (L1) arranged between an intermediate node between the two switching elements and an output node of the switching power supply circuit.

8. A charge sampling switching element (M1) connected in series between the DC power supply node and the upstream switching element (M2); The shunt resistance value measurement circuit for a shunt-type current sensor according to claim 7, further comprising: a capacitor (C1) arranged between an intermediate node between the upstream switching element and the charge sampling switching element and a ground node.

9. the reference resistor is composed of a first reference resistor and a second reference resistor connected in series to the shunt resistor, and a second power supply (16; 516) is provided to a triple series circuit of the first reference resistor, the second reference resistor, and the shunt resistor; a first measurement step in which the signal processing circuit measures a resistance ratio between a resistance value of the first reference resistor and a resistance value of the second reference resistor based on a measurement voltage applied to the first reference resistor and a measurement voltage applied to the second reference resistor measured by the first voltage measurement circuit and the second voltage measurement circuit, respectively; a second measurement step of measuring a resistance ratio between a resistance value of the second reference resistor and a resistance value of the shunt resistor by performing signal processing based on a measured voltage applied to the second reference resistor and a measured voltage applied to the shunt resistor; The shunt resistance value measuring circuit for a shunt type current sensor according to claim 5 , comprising:

10. The shunt resistance value measurement circuit for a shunt-type current sensor according to claim 9 , wherein the second power supply outputs an AC excitation current using a linear regulator (516 a) to which the modulation signal is applied.

11. 11. The shunt resistance value measuring circuit for a shunt-type current sensor according to claim 10, wherein the second power supply applies an AC excitation current to the first reference resistor and the second reference resistor in the first measuring step.

12. The signal processing circuit includes: In the first measuring step, a resistance value of the second reference resistor is divided by a resistance value of the first reference resistor; In the second measuring step, a resistance value of the shunt resistor is divided by a resistance value of the second reference resistor; A shunt resistance measurement circuit for a shunt-type current sensor as described in claim 10, which measures the resistance value of the shunt resistor by multiplying the measurement result of the first measurement step by the measurement result of the second measurement step and by a reference resistance value of the first reference resistor that is recorded in advance.

13. 13. The shunt resistance value measuring circuit for a shunt-type current sensor according to claim 12, wherein the power supply applies an AC excitation current to the first reference resistor and the second reference resistor in the first measuring step.

14. 10. The shunt resistance value measuring circuit for a shunt-type current sensor according to claim 9, wherein the first reference resistor is mounted on the same integrated circuit as the integrated circuit on which the first voltage measuring circuit is mounted.

15. The shunt resistance value measuring circuit for a shunt-type current sensor according to claim 14 , wherein a material of the first reference resistor includes tantalum nitride, titanium nitride, or nitride.

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