JP2020063946A - Voltage measuring device - Google Patents

Abstract

To measure an electromotive voltage by considering an influence of resistance other than voltage dividing resistance included in a path composed of resistance elements connected between a pair of measurement terminals.SOLUTION: A voltage measuring device includes: an AC power supply part 5 for supplying an AC current Ito a measurement terminal 2; an AC measurement part 7A for measuring an AC voltage value Vof an AC voltage Vgenerated between measurement terminals 2, 3 when supplying the AC current I; a voltage dividing circuit part 8 composed of voltage dividing resistors 21, 22 to output a divided voltage Vdv; a DC measurement part 9 for measuring a DC voltage value Vdv1 of a DC component of the divided voltage Vdv; and a processing part 10. The processing part 10 calculates a combined resistance value between the measurement terminals 2, 3 from the AC voltage value Vand a current value of the AC current I, calculates a battery-side resistance value Rwhen a side of a battery 61 is viewed from the measurement terminals 2, 3 based on the combined resistance value and respective resistance values R1, R2 of the voltage dividing resistors 21, 22, and calculates an electromotive voltage Vx based on the DC voltage value Vdv1, the resistance values R1, R2, and the battery-side resistance value R.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a voltage measuring device that measures electromotive force of a battery.

  As this type of voltage measuring device, for example, a voltage measuring device (voltage detection circuit) disclosed in Patent Document 1 below is known. In this voltage detection circuit, the voltage dividing circuit unit divides the voltage (for example, the voltage (electromotive force) of the battery) input via the input switching circuit unit and outputs the divided voltage, and the operational amplifier The divided voltage is compared with the reference voltage and a signal according to the comparison result is output. Specifically, the voltage dividing circuit section is composed of a series circuit of a plurality of adjusting resistors and two voltage dividing resistors, but in the initial state where each adjusting resistor is short-circuited by the corresponding fuse. , The input voltage is divided by two resistors for dividing voltage, and the divided voltage is output.

  By the way, in the above-mentioned Patent Document 1, since the input switching circuit section (specifically, the transmission gate constituting the input switching circuit section) is interposed in the detection path to the voltage dividing circuit section, Strictly speaking, the voltage is affected not only by the resistance for voltage division but also by the on resistance of this transmission gate (usually a resistance value of several Ω or less), but the resistance value of the voltage division resistance is compared with the resistance value of the on resistance. Since it is usually sufficiently large, the effect of the ON resistance is ignored and the voltage is processed as being divided by the two voltage dividing resistors.

Further, even in the voltage measuring device 51 having a configuration in which the input switching circuit unit is not interposed as shown in FIG. 3, the pair of measurement terminals 2 and 3 has each terminal (positive electrode) of the battery 61 (electromotive force Vx) to be measured. 62 and the negative electrode 63) are connected to the probes 52 and 53 via the probes 52 and 53, the wiring resistance of each probe 52 and 53, and between the probes 52 and 53 and the positive electrode 62 and the negative electrode 63 of the battery 61. (Hereinafter, the combined resistance Rc1 of the contact resistance on the positive electrode 62 side and the wiring resistance is denoted by R _HP, and the combined resistance Rc2 of the contact resistance on the negative electrode 63 side and the wiring resistance is denoted by R _LP . Notation) exists.

Therefore, in the voltage measuring device 51, the voltage division is performed in the path L1 (the path formed by the resistance element connected between the pair of measurement terminals 2 and 3) in which the direct current caused by the electromotive force Vx of the battery 61 flows. Since the combined resistors Rc1 and Rc2 described above are included together with the two voltage dividing resistors 21 and 22 that form the circuit unit 8, the divided voltage Vdv output from the voltage dividing circuit unit 8 is affected by the combined resistors Rc1 and Rc2. Will be received. However, also in the voltage measuring device 51, the resistance values R1 and R2 of the two voltage dividing resistors 21 and 22 that form the voltage dividing circuit unit 8 are changed to the resistance values R _HP and R _LP of the combined resistors Rc1 and Rc2. By defining the voltage as a sufficiently large value for comparison, the divided voltage Vdv output from the voltage dividing circuit unit 8 is divided only by the voltage dividing resistors 21 and 22, ignoring the influence of the combined resistors Rc1 and Rc2. Have been treated as

Specifically, the divided voltage Vdv when the influence of the combined resistances Rc1 and Rc2 is taken into consideration is represented by the following formula (1), but the influence of the combined resistances Rc1 and Rc2 is negligible. Considering that the resistance values R1 and R2 are sufficiently larger than the resistance values R _HP and R _LP , the resistance values R1 and R2 are treated as those represented by the following equation (2).
Vdv = Vx × R2 / (R1 + R2 + R _HP + R _LP ) (1)
Vdv = Vx × R2 / (R1 + R2) (2)

Further, in the voltage measuring device 51, a processing unit (not shown) to which the divided voltage Vdv is input via the buffer 57 (an operational amplifier configured as a voltage follower) is derived from the above equation (2) and is given by: The electromotive force Vx of the battery 61 is measured (calculated) based on the equation (3).
Vx = Vdv × (R1 + R2) / R2 (3)

JP-A-2003-75477 (pages 6-7, FIG. 1)

  However, in the voltage measurement device 51 described above, other resistors (in the above example, other than the voltage dividing resistors 21 and 22 existing in the path L1 formed of the resistance element connected between the pair of measurement terminals 2 and 3). Although the combined resistances Rc1 and Rc2) are ignored (the resistance value is regarded as zero ohms), the electromotive force Vx is measured. However, in order to measure the electromotive force Vx more accurately, except for the voltage dividing resistors 21 and 22, It is preferable to consider the other resistances.

  The present invention has been made in view of such problems to be solved, in consideration of the influence of the resistance other than the voltage dividing resistance included in the path constituted by the resistance element connected between the pair of measurement terminals, The main object of the present invention is to provide a voltage measuring device that can measure the electromotive force of a battery more accurately.

  In order to achieve the above object, the voltage measuring device according to claim 1 is connected to a pair of measuring terminals and one measuring terminal of the pair of measuring terminals via a first coupling capacitor, and the one of the measuring terminals is connected. An AC power supply unit that supplies an AC current to a path from the measurement terminal to the other measurement terminal connected to the reference potential of the pair of measurement terminals, and is connected to the one measurement terminal via a second coupling capacitor. Then, an AC measurement unit that measures the voltage value of the AC voltage generated between the pair of measurement terminals when the AC current is supplied as an AC voltage value, and a first component of a known resistance value connected in series. A voltage resistor and a second voltage dividing resistor are connected between the pair of measuring terminals, and a voltage generated between both ends of the second voltage dividing resistor is applied to the one measuring terminal with reference to the reference potential. Generated electricity A voltage dividing circuit unit for outputting as a divided voltage, a DC measuring unit for measuring a voltage value of a DC component included in the divided voltage as a DC voltage value, and a processing unit, and the processing unit, In the state where the battery is connected between the pair of measurement terminals, all the resistors that are AC- and DC-connected between the pair of measurement terminals based on the AC voltage value and the current value of the AC current. Based on a first calculation process for calculating a combined resistance value of the element, the combined resistance value, and each of the known resistance values of the first voltage dividing resistance and the second voltage dividing resistance, from the pair of measurement terminals A second calculation process for calculating a resistance value between the pair of measurement terminals when looking at the battery side as a battery side resistance value, and the known DC voltage value, the first voltage dividing resistance, and the second voltage dividing resistance. Each resistance value of, and the battery side resistance Based on, performing a third calculation process of calculating the electromotive force of the battery.

  Further, the voltage measuring device according to claim 2 is the voltage measuring device according to claim 1, wherein one end of the AC measuring unit is connected to the one measuring terminal via the second coupling capacitor. An input stage circuit having an input resistance of a known resistance value whose end is connected to the reference potential, and an operational amplifier for inputting, amplifying and outputting the AC voltage generated at the one end of the input resistance with the reference potential as a reference. In addition, in the second calculation process, the processing unit includes the known resistance value of the input resistance in addition to the known resistance values of the combined resistance value and the first voltage division resistance and the second voltage division resistance. The battery-side resistance value is calculated based on the resistance value.

  According to the voltage measuring device according to claim 1, resistances other than the respective voltage dividing resistors connected between the pair of measurement terminals, for example, contact resistance and wiring resistance with the measurement target are considered without neglecting. Since it is possible to measure the electromotive force of the battery, the electromotive force can be measured more accurately (with a small error).

  Further, according to the voltage measuring device of claim 2, even in the configuration including the AC measuring unit having the input resistance, the resistance other than the voltage dividing resistances connected between the pair of measurement terminals, for example, the measurement target Since the electromotive force of the battery can be measured without considering the contact resistance and the wiring resistance between them, the electromotive force can be measured more accurately (with a small error).

It is a block diagram which shows the structure of the voltage measuring device 1A. It is a block diagram which shows the structure of the voltage measuring device 1B. It is a block diagram which shows the structure of the conventional voltage measuring device 51.

  Hereinafter, an embodiment of a voltage measuring device will be described with reference to the accompanying drawings.

  First, the configuration of the voltage measuring device 1A as the voltage measuring device will be described with reference to FIG.

  The voltage measuring device 1A includes a pair of measuring terminals 2, 3, a first coupling capacitor 4, an AC power supply unit 5, a second coupling capacitor 6, an AC measuring unit 7A, a voltage dividing circuit unit 8, a DC measuring unit 9, and a processing. The unit 10 and the output unit 11 are provided so that the electromotive force Vx of the battery 61 that is the measurement target can be measured. In the battery 61, as an example, a DC voltage source that generates an electromotive force Vx and an internal resistance Rx (a resistance value is also represented by Rx for easy understanding) are provided between a positive electrode 62 and a negative electrode 63. Equivalently connected in series.

In the voltage measurement device 1A of this example, as an example, one measurement terminal 2 of the pair of measurement terminals 2 and 3 is connected to the positive electrode 62 of the battery 61 via a measurement cable (in this example, the probe 52). The other measurement terminal 3 is connected to the negative electrode 63 of the battery 61 via another measurement cable (probe 53 as an example in this example). The other measuring terminal 3 is connected to the internal ground G which is a reference potential (zero volt) in the voltage measuring device 1A. Further, in the state where one measurement terminal 2 is connected to the positive electrode 62 of the battery 61 via the probe 52, the wiring resistance of the probe 52 and the probe 52 are connected between the one measurement terminal 2 and the positive electrode 62. Although there is a contact resistance between the positive electrode 62 and the positive electrode 62, the resistance value of the series combined resistance Rc1 of the wiring resistance and the contact resistance is expressed as R _HP in FIG. Similarly, the resistance value of the series combined resistance Rc2 of the wiring resistance of the probe 53 existing between the other measurement terminal 3 and the negative electrode 63 and the contact resistance between the probe 53 and the negative electrode 63 is expressed as R _LP. To do.

One end of the first coupling capacitor 4 is connected to one measurement terminal 2. The AC power supply unit 5 is connected between the other end of the first coupling capacitor 4 and the internal ground G. In addition, the AC power supply unit 5 is configured by an AC constant current source as an example, and supplies an AC current (AC constant current) I _AC having a known current value to one measurement terminal 2. This alternating current I _{AC passes} from one measurement terminal 2 to the other measurement terminal 3 connected to the internal ground G, and all the paths existing between the measurement terminals 2 and 3 (in this example, as will be described later). Flow through two paths). The AC power supply unit 5 is not limited to the one configured by an AC constant current source. For example, although not shown, an AC voltage source that supplies an AC voltage based on the potential (zero volt) of the internal ground G to one of the measurement terminals 2 and one of the measurement terminals 2 from the AC voltage source when the AC voltage is applied. It may be configured with an alternating current ammeter that measures the current value of the alternating current flowing toward and outputs it to the processing unit 10.

The second coupling capacitor 6 has one end connected to the one measurement terminal 2. The AC measuring unit 7A has an input unit connected to the other end of the second coupling capacitor 6 and supplies the AC voltage V _AC generated between the pair of measuring terminals 2 and 3 when the _AC current I _AC is supplied. The voltage value (for example, effective value) is measured as the AC voltage value V _AC1 and output to the processing unit 10. Further, in the AC measuring section 7A, the input impedance of the input section is infinite (specifically, the input impedance is connected to the input terminal of an operational amplifier (not shown) that constitutes the input stage circuit of the AC measuring section 7A. , An extremely high resistance value such as several M ohms). With this configuration, it can be considered that no current flows into the input section of the AC measuring section 7A.

  The voltage dividing circuit unit 8 is composed of a first voltage dividing resistor 21 (resistance value R1) and a second voltage dividing resistor 22 (resistance value R2) of known resistance values, which are connected in series. , 3 are connected. Since the first voltage dividing resistor 21 is connected to one measuring terminal 2 and the second voltage dividing resistor 22 is connected to the other measuring terminal 3 (that is, the internal ground G), the voltage dividing circuit unit 8 is The voltage generated across the second voltage dividing resistor 22 with reference to the potential of the internal ground G (zero volt) is the divided voltage Vdv with respect to the voltage generated at one of the measurement terminals 2 with the potential of the internal ground G as the reference. Output. The first voltage dividing resistor 21 and the second voltage dividing resistor 22 may be configured by one resistor, or may be configured by connecting a plurality of resistors in series or in parallel.

  The DC measuring unit 9 measures the voltage value of the DC component included in the divided voltage Vdv input to the input unit as the DC voltage value Vdv1 and outputs it to the processing unit 10. Further, in the DC measuring unit 9, the input impedance of the input unit is infinite (specifically, the input impedance of the input unit is connected to the input terminal of an operational amplifier (not shown) forming the input stage circuit of the DC measuring unit 9. , An extremely high resistance value such as several M ohms). With this configuration, it can be considered that no current flows into the input section of the DC measuring section 9.

As an example, the processing unit 10 is configured to include an A / D converter, a CPU, and a memory, and is input by executing a first calculation process, a second calculation process, and a third calculation process described later. The AC voltage value V _AC1 and the DC voltage value V _DC , the known current value of the _AC current I _AC , and the known resistance values R1 and R2 of the first voltage _dividing resistor 21 and the second voltage _dividing resistor 22 are used. Based on this, the electromotive force Vx of the battery 61 is measured (calculated). The processing unit 10 also executes an output process of causing the output unit 11 to output the measured electromotive force Vx.

  The output unit 11 is configured by a display device, for example, and displays (outputs) the electromotive force Vx output from the processing unit 10 on the screen. The output unit 11 can be configured by various interface circuits instead of the display device. When configured by an external interface circuit, the output unit 11 is measured by an external device connected by a transmission line via the external interface circuit. When the electromotive force Vx is output, and when it is configured by the medium interface circuit, the measured electromotive force Vx is stored in the storage medium connected to the medium interface circuit.

  Next, the operation of the voltage measuring device 1A will be described with reference to the drawings. The voltage measuring device 1A is connected to the battery 61 via a pair of probes 52 and 53.

In this state, in the voltage measuring device 1A, the AC power supply unit 5 is DC-separated by the first coupling capacitor 4 and the AC measurement unit 7A is the second coupling capacitor 6 with respect to the one measurement terminal 2. Separated from direct current. Further, no current flows into the input section of the DC measuring section 9. Therefore, in the voltage measuring device 1A, based on the electromotive force Vx of the battery 61, from the positive electrode 62 of the battery 61 to the probe 52, one measuring terminal 2, the voltage dividing circuit unit 8, the internal ground G, and the other measuring terminal 3 Further, the direct current I _DC flows through the path L1 that reaches the negative electrode 63 of the battery 61 via the probe 53.

Further, the voltage measuring device 1A is configured so that no current flows into the input section of the AC measuring section 7A. Therefore, in the voltage measuring device 1A, the AC current I _AC supplied from the AC power supply unit 5 to the one measuring terminal 2 is supplied from the one measuring terminal 2 to the probe 52, the battery 61, the probe 53, and the other measuring terminal 3. The current is divided into a path L2 that leads to the internal ground G via the, and a path L3 that goes from the one measurement terminal 2 to the internal ground G through the voltage dividing circuit section 8.

As a result, in the voltage measuring device 1A, the DC voltage V _DC generated by the DC current I _DC flowing through the voltage dividing circuit unit 8 and the current flowing into the path L3 of the _AC current I _AC are divided by the voltage dividing circuit unit 8A. A combined voltage (V _DC + V _AC ) with the _AC voltage V _AC that is generated by flowing to the one side is generated at one measurement terminal 2.

Therefore, the voltage measurement apparatus 1A, an AC measurement unit 7A is, composite voltage an AC voltage _{V AC} of _(V DC _{+ V AC)} and detects via the second coupling capacitor 6, the AC voltage _{V AC} of the AC voltage The value V _AC1 is measured and output to the processing unit 10. Further, the voltage dividing circuit unit 8 divides the combined voltage (V _DC + V _AC ) to output the divided voltage Vdv, and the DC measuring unit 9 outputs the DC component (the voltage dividing circuit unit) included in the divided voltage Vdv. The DC voltage value Vdv1 of the DC voltage V _DC divided by 8 is measured and output to the processing unit 10.

In this state, the processing unit 10 first executes the first calculation process based on the alternating current voltage value V _AC1 measured by the alternating current measuring unit 7A and the known current value of the alternating current I _AC , and a pair of A combined resistance value R _TOTAL of all resistance elements connected AC and DC between the measurement terminals 2 and 3 is calculated. Specifically, the processing unit 10 divides the AC voltage value V _AC1 by a known current value of the _AC current I _AC to calculate and store a combined resistance value R _TOTAL .

Considering that no current flows into the input parts of the AC measuring unit 7A and the DC measuring unit 9, in this example, between the pair of measuring terminals 2 and 3, the resistance elements existing in the path L2 (mutually). The series combined resistance Rc1 (resistance value R _HP ), the internal resistance Rx (resistance value Rx) and the series combination resistance Rc2 (resistance value R _LP ), which are connected in series, and the resistance elements existing in the path L3 (connected to each other in series). The first voltage dividing resistor 21 (resistance value R1) and the second voltage dividing resistor 22 (resistance value R2) are connected in direct current. Therefore, the resistance value between the pair of measurement terminals 2 and 3 when the battery 61 side is viewed from the pair of measurement terminals 2 and 3, that is, the resistance value of the entire resistance element existing in the path L2 is the battery side. When the resistance value R _BT (= R _HP + Rx + R _LP ), the calculated combined resistance value R _TOTAL is a value that satisfies the following formula (4).
1 / R _TOTAL = 1 / R _BT + 1 / (R1 + R2) (4)

Next, the processing unit 10 executes the second calculation process based on the calculated combined resistance value R _TOTAL and the known resistance values R1 and R2 of the first _{voltage dividing} resistor 21 and the second _{voltage dividing} resistor 22. , The battery side resistance value R _BT is calculated. Specifically, the processing unit 10 substitutes the combined resistance value R _TOTAL and the resistance values R1 and R2 into the above-described equation (4) stored in the memory in advance to organize the battery-side resistance. The value R _BT is calculated and stored.

Subsequently, the processing unit 10 calculates the DC voltage value Vdv1 measured by the DC measuring unit 9, the known resistance values R1 and R2 of the first voltage dividing resistor 21 and the second voltage dividing resistor 22, and the calculated battery side. The third calculation process is executed based on the resistance value R _BT to measure (calculate) the electromotive force Vx.

In this case, the direct current I _DC flows through the path L1 due to the electromotive force Vx. From this, the following formula (5) is established.
Vx = I _DC × (R _BT + R1 + R2) (5)
Accordingly, the direct current I _DC is expressed by the following equation (6).
I _DC = Vx / (R _BT + R1 + R2) (6)
Further, as a result, the DC voltage value Vdv1 is represented by the following equation (7).
Vdv1 = R2 × _{I DC}
= Vx × R2 / (R _BT + R1 + R2) (7)
Further, by modifying the equation (7), the electromotive force Vx is represented by the following equation (8).
Vx = Vdv1 × (R _BT + R1 + R2) / R2 (8)

Therefore, the processing unit 10 substitutes the DC voltage value Vdv1, the battery-side resistance value R _BT, and the resistance values R1 and R2 into the above-described formula (8) stored in the memory to start the process. The electric power Vx is measured (calculated) and stored.

  In addition, the processing unit 10 executes an output process and causes the output unit 11 to display the calculated electromotive force Vx. This completes the measurement of the electromotive force Vx by the voltage measuring device 1A.

As described above, according to the voltage measuring device 1A, the processing unit 10 ignores the influence on the resistance value (each resistance value R1, R2) of the voltage dividing circuit unit 8 in the conventional voltage measuring device 51. Value (that is, resistances other than the voltage dividing resistors 21 and 22 connected between the pair of measurement terminals 2 and 3, in this example, battery-side resistance value R including resistance values R _HP and R _LP of combined resistances Rc1 and Rc2 _The electromotive force Vx is measured by considering _BT ) without ignoring it. Therefore, according to the voltage measuring device 1A, the electromotive force Vx can be measured more accurately (with a small error).

  Next, a voltage measuring device 1B as another voltage measuring device will be described with reference to FIG. The same components as those of the voltage measuring device 1A are designated by the same reference numerals, and duplicate description will be omitted.

  The voltage measuring device 1B includes a pair of measuring terminals 2, 3, a first coupling capacitor 4, an AC power supply unit 5, a second coupling capacitor 6, an AC measuring unit 7B, a voltage dividing circuit unit 8, a DC measuring unit 9, and a processing. The unit 10 and the output unit 11 are provided so that the electromotive force Vx of the battery 61 can be measured.

  The AC measuring section 7B has an input section connected to the other end of the second coupling capacitor 6. Further, the AC measuring unit 7B includes, for example, an input resistor 31, an amplifier 32, a first filter unit 33, a detection circuit 34, and a second filter unit 35.

The input resistor 31 has one end connected to the input unit of the AC measurement unit 7B (that is, connected to the other end of the second coupling capacitor 6) and the other end connected to the internal ground G. With this configuration, the input resistance 31 becomes a resistance element that is AC-connected between the pair of measurement terminals 2 and 3. As a result, the AC current I _AC is shunted not only to the paths L2 and L3 described above, but also to the path L4 from the one measurement terminal 2 to the internal ground G via the second coupling capacitor 6 and the input resistor 31. It Therefore, the AC voltage V _AC is generated across the input resistor 31. Further, since the resistance value R3 (known) of the input resistor 31 affects the combined resistance value R _TOTAL , in this voltage measuring device 1B, the combined resistance value R _{TOTAL is} expressed by the equation (4) of the voltage measuring device 1A. Instead, the following equation (9) is established.
1 / R _TOTAL = 1 / R _BT + 1 / (R1 + R2) + 1 / R3 (9)
The impedance of the second coupling capacitor 6 is 1 / when the capacitance value of the second coupling capacitor 6 is C and the frequency of the alternating current I _AC (also the frequency of the alternating voltage V _AC ) is f. It is represented by (2πfC), but is sufficiently small with respect to the resistance value R3, and is therefore ignored.

The amplifier 32 has an operational amplifier 32a having a non-inverting input terminal connected to one end of the input resistor 31, a resistor 32b having one end connected to the inverting input terminal of the operational amplifier 32a and the other end connected to the internal ground G, and The feedback resistor 32c is connected between the inverting input terminal and the output terminal of the operational amplifier 32a, and is configured as a non-inverting amplifier. Further, the amplifier 32 amplifies the AC voltage V _AC generated between both ends of the input resistor 31 with an amplification factor defined in advance by the resistance values of the resistors 32b and 32c, and outputs it as an amplified signal. The first filter unit 33 is configured as a narrow band pass filter that mainly passes a signal component having the same frequency as the frequency of the alternating current I _AC (also the frequency of the alternating voltage V _AC ). With this configuration, the first filter unit 33 inputs the amplified signal output from the amplifier 32, removes the frequency component (noise component) outside the pass band included in the amplified signal, and outputs it.

The detection circuit 34 is configured using a multiplier as an example, and multiplies the signal output from the first filter unit 33 by the synchronization signal S1 output from the AC power supply unit 5 (in other words, the first By synchronously detecting the signal output from the filter unit 33 with this synchronization signal), a DC signal whose voltage value changes according to the voltage value (for example, amplitude) of the _AC voltage V _AC is output. The second filter unit 35 is configured as a low-pass filter, receives the DC signal output from the detection circuit 34, removes the AC component and smoothes it, and outputs the AC voltage value V _AC1 . To do.

  The DC measuring unit 9 is configured in the same manner as the DC measuring unit 9 of the voltage measuring device 1A and outputs the DC voltage value Vdv1. As shown in FIG. 2 as an example, the DC measuring unit 9 can be configured by an operational amplifier 41 configured as a voltage follower and a third filter unit 42 configured as a low pass filter. As a result, the DC measuring unit 9 measures the voltage value of the DC component included in the divided voltage Vdv input to the input unit as the DC voltage value Vdv1 when the input impedance of the input unit is defined to be infinite. , Can be output.

  Next, the operation of the voltage measuring device 1B will be described with reference to the drawings. The voltage measuring device 1B is connected to the battery 61 via a pair of probes 52 and 53.

In this state, also in the voltage measuring device 1B, the AC power supply unit 5 is DC-separated by the first coupling capacitor 4 and the AC measurement unit 7B is the second coupling capacitor 6 with respect to the one measurement terminal 2. Since they are separated in terms of direct current, a direct current I _DC based on the electromotive force Vx of the battery 61 flows in the path L1.

In the voltage measuring device 1B, the AC current I _AC supplied from the AC power supply unit 5 to the one measurement terminal 2 is shunted into the three paths L2, L3, L4 as described above.

Thereby, in the voltage measuring device 1B, the AC measuring unit 7B detects the _AC voltage V _AC of the combined voltage (V _DC + V _AC ) generated at the one measurement terminal 2 via the second coupling capacitor 6. together, by measuring the AC voltage _{V AC1} of the AC voltage _{V AC,} and outputs to the processing unit 10. Further, the voltage dividing circuit unit 8 divides the combined voltage (V _DC + V _AC ) to output the divided voltage Vdv, and the DC measuring unit 9 outputs the DC component (voltage dividing circuit unit) included in the divided voltage Vdv. The DC voltage value Vdv1 of the DC voltage V _DC divided by 8 is measured and output to the processing unit 10.

In this state, the processing unit 10 first executes the first calculation process based on the alternating current voltage value V _AC1 measured by the alternating current measuring unit 7B and the known current value of the alternating current I _AC to perform a pair of processing. A combined resistance value R _TOTAL of all resistance elements connected AC and DC between the measurement terminals 2 and 3 is calculated. Specifically, the processing unit 10 divides the AC voltage value V _AC1 by a known current value of the _AC current I _AC to calculate and store a combined resistance value R _TOTAL . In this case, the calculated combined resistance value R _TOTAL is a value that satisfies the above equation (9).

Then, the processing unit 10 calculates the combined resistance value R _TOTAL , the known resistance values R1 and R2 of the first _{voltage dividing} resistor 21 and the second _{voltage dividing} resistor 22, and the known input resistance 31 of the AC measuring unit 7B. The second calculation process is executed based on the resistance value R3 of R.sub.2 and the battery side resistance value _R.sub.BT. Specifically, the processing unit 10 substitutes the combined resistance value R _TOTAL and the resistance values R1, R2, and R3 into the above-described formula (9) stored in the memory, and rearranges the battery. The side resistance value R _BT is calculated and stored.

Subsequently, the processing unit 10 calculates the DC voltage value Vdv1 measured by the DC measuring unit 9, the known resistance values R1 and R2 of the first voltage dividing resistor 21 and the second voltage dividing resistor 22, and the calculated battery side. The third calculation process is executed based on the resistance value R _BT to measure (calculate) the electromotive force Vx.

In this case, the direct current I _DC flows through the path L1 due to the electromotive force Vx. From this, the above formula (5) is established. Accordingly, the direct current I _DC is represented by the above equation (6). Further, as a result, the DC voltage value Vdv1 is represented by the above equation (7). Further, by modifying the equation (7), the electromotive force Vx is represented by the above equation (8).

Therefore, the processing unit 10 substitutes the DC voltage value Vdv1, the battery-side resistance value R _BT, and the resistance values R1 and R2 into the above-described formula (8) stored in the memory to start the process. The electric power Vx is measured (calculated) and stored.

  In addition, the processing unit 10 executes an output process and causes the output unit 11 to display the calculated electromotive force Vx. This completes the measurement of the electromotive force Vx by the voltage measuring device 1B.

As described above, also in the voltage measuring device 1B configured to include the AC measuring unit 7B having the input resistance 31, the processing unit 10 in the conventional voltage measuring device 51 has the resistance value (each resistance value R1 of the voltage dividing circuit unit 8). , R2) which has neglected the influence on the resistance (that is, the resistances other than the voltage dividing resistors 21 and 22 connected between the pair of measurement terminals 2 and 3, in this example, the combined resistances Rc1 and Rc2). Since the electromotive force Vx can be measured without considering the battery side resistance value R _BT including R _HP and R _LP , the electromotive force Vx can be measured more accurately (with a small error). be able to.

  Although each of the voltage measuring devices 1A and 1B described above adopts a configuration in which the electromotive force Vx is measured in consideration of the internal resistance Rx of the battery 61, the internal resistance Rx is not considered (that is, the internal resistance Rx Can be used as a resistor having an extremely small resistance value such as zero ohm), and a configuration for measuring the electromotive force Vx can be employed.

1A, 1B voltage measuring device
2,3 A pair of measuring terminals
4 First coupling capacitor
5 AC power supply
6 Second coupling capacitor 7A, 7B AC measuring section
8 voltage divider
9 DC measuring unit 10 Processing unit 21 First voltage dividing resistor 22 Second voltage dividing resistor
G Internal ground I _AC AC current V _AC AC voltage V _AC1 AC voltage value Vdv Divided voltage Vdv1 DC voltage value Vx electromotive force

Claims (2)

A pair of measuring terminals,
The measuring terminal is connected to one measuring terminal of the pair of measuring terminals via a first coupling capacitor, and is connected from the one measuring terminal to the other measuring terminal connected to the reference potential of the pair of measuring terminals. An AC power supply unit that supplies an AC current to the route,
AC measurement in which a voltage value of an AC voltage generated between the pair of measurement terminals when the AC current is supplied is measured as an AC voltage value, which is connected to the one measurement terminal via a second coupling capacitor. Department,
It is composed of a first voltage dividing resistor and a second voltage dividing resistor of known resistance value connected in series, and is connected between the pair of measurement terminals to generate a voltage generated between both ends of the second voltage dividing resistor. A voltage dividing circuit unit that outputs a divided voltage for the voltage generated at the one measurement terminal with reference to the reference potential,
A direct current measuring unit for measuring a voltage value of a direct current component included in the divided voltage as a direct current voltage value,
And a processing unit,
The processing unit, in a state where a battery is connected between the pair of measurement terminals, connects AC and DC between the pair of measurement terminals based on the AC voltage value and the current value of the AC current. A first calculation process for calculating a combined resistance value of all the resistance elements that are set,
Between the pair of measurement terminals when the battery side is viewed from the pair of measurement terminals, based on the combined resistance value and the known resistance values of the first voltage division resistance and the second voltage division resistance. A second calculation process for calculating the resistance value as the battery-side resistance value;
And a third calculation process for calculating an electromotive force of the battery based on the DC voltage value, the known resistance values of the first voltage dividing resistor and the second voltage dividing resistor, and the battery-side resistance value. Voltage measuring device. The AC measuring unit,
An input resistance having a known resistance value, one end of which is connected to the one measurement terminal via the second coupling capacitor and the other end of which is connected to the reference potential, and the input resistance of the input resistance with the reference potential as a reference. An operational amplifier that inputs and amplifies and outputs an AC voltage generated at the one end is provided as an input stage circuit,
In the second calculation process, the processing unit adds to the known resistance value of the input resistance in addition to the combined resistance value and the known resistance values of the first voltage dividing resistance and the second voltage dividing resistance. The voltage measuring device according to claim 1, wherein the battery-side resistance value is calculated based on the above.

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