JP5940389B2 - AC resistance measuring device and AC resistance measuring method - Google Patents

Description

  The present invention relates to an AC resistance measuring device and an AC resistance measuring method for measuring an AC resistance to be measured.

  As this type of measurement apparatus, a measurement apparatus (degradation determination apparatus) disclosed as a conventional technique in Patent Document 1 below is known. This measuring apparatus includes a resistance measuring unit that measures a resistance value of an effective resistance in a battery pack as a measurement target, and the resistance measuring unit measures an effective resistance in the battery pack according to an AC four-terminal method.

  Specifically, the resistance measurement unit supplies an AC constant current of, for example, 1 kHz to the battery pack via a pair of probes, and inputs an AC voltage generated at both ends of the battery pack at this time via each probe. Next, the resistance measurement unit multiplies the reference signal voltage of the supplied AC constant current by the input AC voltage, and passes the signal obtained by the multiplication through the low-pass filter, so that the effective in the battery pack is obtained. Calculate the power loss caused by the resistance. In this case, since the current value of the AC constant current is determined in advance, the resistance value of the effective resistance is measured by dividing the power loss calculated by the square value of the current value.

  According to this measuring apparatus, a configuration in which the supplied AC voltage reference signal voltage and the input AC voltage are multiplied with each other, that is, a configuration in which synchronous detection is performed using the AC constant current reference signal voltage (reference signal) is adopted. As a result, the same frequency component as that of the AC constant current can be extracted, so that the influence of noise can be greatly reduced.

JP-A-11-174136 (2nd page, FIG. 7)

  However, the above measuring apparatus has the following problems to be improved. That is, in this measuring apparatus, it is difficult to reduce noise having the same frequency as the reference signal voltage (reference signal) of the AC constant current even if synchronous detection is performed. For this reason, this measuring apparatus has a problem to be improved that, under the situation where such noise is generated, the measurement accuracy is lowered due to the influence of the noise.

  The present invention has been made to improve such a problem, and an AC resistance measurement device and an AC resistance measurement capable of ensuring sufficient measurement accuracy even in the presence of noise having the same frequency as the AC current supplied to the object to be measured. The main purpose is to provide a method.

  In order to achieve the above object, an AC resistance measuring device according to claim 1 is a current source for supplying an alternating current to a measurement object, and a voltage detection unit for detecting an alternating voltage generated in the measurement object in the supply state of the alternating current. A synchronous detection unit that synchronously detects the detected AC voltage with a reference signal that is synchronized with the AC current and outputs a detection signal, a filter unit that extracts a DC component of the detection signal, and the extracted DC And a processing unit that calculates an AC resistance value of the measurement object based on a component and a current value of the AC current, wherein the current source determines a current value of the AC current as a first value. The processing unit is configured to be switchable to one of a current value and a second current value different from the first current value, and the processing unit outputs from the filter unit in the supply state of the alternating current of the first current value The The first DC component as the DC component, the first current value, the second DC component as the DC component output from the filter unit in the supply state of the AC current of the second current value, and the first The AC resistance value is calculated based on the two current values.

The AC resistance measurement device according to claim 2 is the AC resistance measurement device according to claim 1, wherein the synchronous detection unit includes a signal inverter and a switch, and the detected AC voltage. The inverted signal is inverted by the signal inverter to generate an inverted AC voltage, and the AC voltage and the inverted AC signal are switched in synchronization with the reference signal by the switch to be output as the detection signal, The processing unit is equivalent to the following equation when the first current value is I1, the first DC component is Vdc1, the second current value is I2, and the second DC component is Vdc2. Based on this, the AC resistance value is calculated.
π / 2 × (Vdc1−Vdc2) / (I1−I2)

The AC resistance measurement device according to claim 3 is the AC resistance measurement device according to claim 1, wherein the synchronous detection unit includes a multiplier, and inputs the AC current as the reference signal. The detected AC voltage and the AC current are multiplied by the multiplier and output as the detection signal, and the processing unit equivalently converts the first DC component to the square value of the first current value. To calculate the first divided value and divide the second DC component by the square value of the second current value to calculate the second divided value. The first current value is I1, and the first When the division value is A1, the second current value is I2, and the second division value is A2, the AC resistance value is calculated based on the following equation.
2 × (I1 × A1-I2 × A2) / (I1-I2)

  According to a fourth aspect of the present invention, there is provided an AC resistance measurement method that detects an AC voltage generated in the measurement target in a state where an AC current is supplied to the measurement target, and synchronizes the detected AC voltage with the AC current. AC resistance for synchronous detection with a reference signal, outputting a detection signal, extracting a DC component of the detection signal, and calculating an AC resistance value of the measurement object based on the extracted DC component and the current value of the AC current In the measurement method, the first direct current component as the direct current component extracted in the supply state of the alternating current of the first current value, the first current value, and the second current value different from the first current value. The AC resistance value is calculated based on the second DC component as the DC component extracted in the supply state of the AC current and the second current value.

  In the AC resistance measuring device according to claim 1 and the AC resistance measuring method according to claim 4, the AC resistance value is calculated without being affected by the noise voltage. Specifically, the AC resistance value is calculated using an equation for calculating an AC resistance value not including a noise voltage as a parameter, as in the AC resistance measuring device according to claims 2 and 3. Therefore, according to these AC resistance measuring devices and AC resistance measuring methods, in the case where noise is included in the AC voltage generated across the measurement object and the frequency of this noise is the same frequency as the AC current, However, when the amplitude of the noise can be considered to be constant, the AC resistance value can be measured with sufficient measurement accuracy without being affected by the noise.

It is a block diagram of alternating current resistance measuring apparatus 1 (1A). It is a circuit diagram of the synchronous detection part 4 in FIG. 3 is a flowchart for explaining the operation of the AC resistance measuring device 1; It is a circuit diagram of the synchronous detection part 4A in FIG. It is a flowchart for demonstrating operation | movement of AC resistance measuring apparatus 1A.

  Hereinafter, embodiments of an AC resistance measuring device and an AC resistance measuring method will be described with reference to the accompanying drawings. In this example, an example in which the AC resistance value of a battery as a measurement target is measured will be described.

(First embodiment)
First, the configuration of an AC resistance measuring device (hereinafter also simply referred to as “measuring device”) 1 will be described with reference to FIG.

  As shown in FIG. 1, the measuring device 1 includes, as an example, a current source 2, a voltage detection unit 3, a synchronous detection unit 4, a filter unit 5, an A / D conversion unit 6, a processing unit 7, and an output unit 8. An AC resistance value (AC effective resistance value) Rx of a measurement object (battery in this example) 9 is configured to be measurable. In this example, since the measuring object 9 is a battery, capacitors C1, C2, and C3 that block the application of a DC voltage from the measuring object 9 to the measuring device 1 are provided between the current source 2 and the measuring object 9, and It is disposed between the voltage detector 3 and the measurement object 9. Unlike the battery, when the measurement object 9 is not configured to always output a DC voltage, the capacitors C1, C2, and C3 can be omitted.

  The current source 2 is composed of an alternating current source, and is configured to be able to supply the alternating current I to the measuring object 9 via the capacitor C1. Further, the current source 2 controls the current value (amplitude) of the alternating current I with the known first current value I1 and the first current value under the control of the processing unit 7 in a state where the frequency of the alternating current I is kept constant. It is configured to be switchable to at least two stages of a known second current value I2 different from the current value I1. That is, the current source 2 switches and outputs the alternating current I between I1 × sin (w1 × t) and I2 × sin (w1 × t). The angular velocity w1 is represented by 2 × π × f1, where the frequency of the alternating current I is f1. Further, the current source 2 has a reference signal Sr synchronized with the alternating current I (in this example, the phase is adjusted so as to be in phase with a detection signal S1 described later output from the voltage detection unit 3 and the duty ratio is 0. .5 rectangular wave signal) is generated and output to the synchronous detector 4. In order to facilitate understanding of the invention, it is assumed that there is no signal delay in each component of the measuring apparatus 1 such as each of C1, C2, and C3 and the voltage detector 3.

  The voltage detection unit 3 detects the AC voltage Vob generated between both ends of the measurement object 9 in the supply state of the AC current I through the capacitors C2 and C3, and according to a change in the voltage value of the AC voltage Vob (specifically Specifically, the detection signal S1 whose voltage value changes is output in proportion. In this case, the AC voltage Vob is basically composed of an AC voltage generated when the AC current I flows through the AC resistance value Rx of the measurement target 9. That is, when the current value of the alternating current I is the first current value I1, the alternating voltage Vob is expressed by Rx × I1 × sin (w1 × t), and when the current value of the alternating current I is the second current value I2. The AC voltage Vob is represented by Rx × I2 × sin (w1 × t).

  On the other hand, when the noise voltage Vn (the voltage value is also expressed by Vn) is generated between both ends of the measurement object 9 due to the influence of the external noise, the AC voltage Vob is the above Rx × I1 × sin (w1 × t). ) Or Rx × I2 × sin (w1 × t) and a signal obtained by adding the noise voltage Vn. For this reason, the voltage detection unit 3 detects the AC voltage Vob and outputs a detection signal S1 in which the voltage value changes in accordance with a change in the voltage value of the AC voltage Vob. In this case, the noise voltage Vn is composed of various frequency components. As an example, the same frequency component (Vn × sin (w1 × t)) and amplitude (noise voltage value) as the frequency f1 of the alternating current I are included. It is assumed that the frequency components other than the frequency f1 (for example, frequency components of the frequency f2: Vn × sin (w2 × t); angular velocity w2 = 2 × π × f2) are the same. Therefore, the AC voltage Vob under the influence of external noise is Rx × I1 × sin (w1 × t) + Vn × [sin (w1 × t) when the current value of the alternating current I is the first current value I1. ) + Sin (w2 × t)], and when the current value of the alternating current I is the second current value I2, Rx × I2 × sin (w1 × t) + Vn × [sin (w1 × t) + sin (w2 ×) t)].

  As an example, the synchronous detection unit 4 includes a signal inverter 11 and a switch 12 as shown in FIG. 2, and changes the polarity of the detection signal S1 output from the voltage detection unit 3 to the signal inverter 11. And the inverted AC signal (inverted AC voltage) S1a is generated, and the detection signal S1 and the inverted AC signal S1a are switched in synchronism with the reference signal Sr by the switch 12 and output as the detection signal S2.

With this configuration, the detection signal S2 is equivalent to a signal obtained by full-wave rectification of the detection signal S1 (that is, a signal indicating the absolute value | S1 | of the detection signal S1). In this case, the absolute value | S1 | of the detection signal S1, which is a sine wave signal, is expressed by the following equation when S1 is sinx.
| S1 |
= | Sinx |
= 2 / π × (1-2 × Σ [n = 1, ∞] (cos2nx) / (4n ² −1))

Thereby, when the above-described noise voltage is generated in the measurement object 9 and the current value of the alternating current I is the first current value I1, the detection signal S2 is
Rx × I1 × | sin (w1 × t) | + Vn × [| sin (w1 × t) | + | sin (w2 × t) |]
= Rx × I1 × 2 / π × (1-2 × Σ [n = 1, ∞] (cos2n × w1 × t) / (4n ² −1))
+ Vn × 2 / π × (1-2 × Σ [n = 1, ∞] (cos2n × w1 × t) / (4n ² −1))
+ Vn × 2 / π × (1-2 × Σ [n = 1, ∞] (cos2n × w2 × t) / (4n ² −1))
When the current value of the alternating current I is the second current value I2, the detection signal S2 is
Rx × I2 × | sin (w1 × t) | + Vn × [| sin (w1 × t) | + | sin (w2 × t) |]
= Rx × I2 × 2 / π × (1-2 × Σ [n = 1, ∞] (cos2n × w1 × t) / (4n ² −1))
+ Vn × 2 / π × (1-2 × Σ [n = 1, ∞] (cos2n × w1 × t) / (4n ² −1))
+ Vn × 2 / π × (1-2 × Σ [n = 1, ∞] (cos2n × w2 × t) / (4n ² −1))
It is represented by

The filter unit 5 is composed of a low-pass filter, and extracts and outputs the DC component Vdc of the detection signal S2. With this configuration, the DC voltage Vdc (first DC component Vdc1) when the noise voltage is generated in the measurement target 9 and the current value of the AC current I is the first current value I1 is:
Vdc1 = Rx × I1 × 2 / π + Vn × 4 / π
The DC component Vdc (second DC component Vdc2) when the current value of the AC current I is the second current value I2 is
Vdc2 = Rx × I2 × 2 / π + Vn × 4 / π
It is represented by

  The A / D converter 6 converts the DC component Vdc (the first DC component Vdc1 or the second DC component Vdc2) into voltage data Dv indicating the voltage value of the DC component Vdc by sampling in a predetermined sampling cycle. And output to the processing unit 7.

The processing unit 7 includes a CPU and a memory (both not shown), and executes a resistance measurement process for measuring the AC resistance value Rx and an output process for the measured AC resistance value Rx. In this case, the memory stores in advance a first current value I1 and a second current value that are already known, and the following equation (1) for calculating the AC resistance value Rx.
Rx = π / 2 × (Vdc1−Vdc2) / (I1−I2) (1)

  In this resistance measurement process, the processing unit 7 calculates the first DC component Vdc1 based on the voltage data Dv when the current value of the AC current I is the first current value I1. Further, the processing unit 7 calculates the second DC component Vdc2 based on the voltage data Dv when the current value of the AC current I is the second current value I2. Further, the processing unit 7 substitutes the calculated DC components Vdc1 and Vdc2 and the known current values I1 and I2 into the above-described equation (1) of the AC resistance value Rx to calculate the AC resistance value Rx. .

  Here, even if the voltage value of the noise voltage Vn fluctuates, the detection signal S1 at the second current value I2 from the start of detection of the detection signal S1 at the first current value I1 by the voltage detector 3. By sufficiently shortening the period until the end of the detection, it is possible to make the voltage value of the noise voltage Vn substantially constant during this period. Therefore, when the voltage value of the noise voltage Vn can be regarded as being constant, the noise voltage Vn is eliminated from each of the above-described equations of the DC components Vdc1 and Vdc2, and the AC resistance value Rx is solved. Equation (1) for calculating the AC resistance value Rx is obtained.

  For example, the output unit 8 is configured by a display device such as a liquid crystal display, and displays the AC resistance value Rx measured by the processing unit 7 on the screen. The output unit 8 may be configured by an interface device that performs data communication with an external device instead of the display device, and may adopt a configuration that outputs an AC resistance value Rx to the external device.

  Next, the measurement operation of the AC resistance value Rx for the measurement object 9 by the measurement apparatus 1 will be described with reference to the drawings.

  In the measurement of the AC resistance value Rx, in the measuring apparatus 1, the processing unit 7 executes the resistance measurement process 50 shown in FIG. In the resistance measurement process 50, the processing unit 7 first executes a detection process of the detection signal S1 when the current value of the alternating current I is the first current value I1 (step 51). In this detection process, the processing unit 7 controls the current source 2 to start the supply of the alternating current I having the first current value I1 to the measurement target 9 with respect to the current source 2. In this case, the current source 2 starts outputting the reference signal Sr (rectangular wave signal whose phase is adjusted) to the synchronous detection unit 4 in conjunction with the start of supply of the alternating current I having the first current value I1.

  As a result, the voltage detection unit 3 outputs a detection signal S1 whose voltage value changes in accordance with a change in the voltage value of the AC voltage Vob generated in the measurement object 9, and the synchronous detection unit 4 outputs the detection signal S1 as a current. The detection signal S2 is generated by synchronous detection with the reference signal Sr output from the source 2 and output to the filter unit 5. The filter unit 5 outputs the first DC component Vdc1 of the detection signal S2, and the A / D The converter 6 outputs voltage data Dv indicating the voltage value of the first DC component Vdc1 to the processor 7. The processing unit 7 inputs the voltage data Dv and stores it in correspondence with the first current value I1. Thereby, the detection process of the detection signal S1 when the current value of the alternating current I is the first current value I1 is completed.

  Next, the processing unit 7 performs detection processing of the detection signal S1 when the current value of the alternating current I is the second current value I2 (step 52). In this detection process, the processing unit 7 controls the current source 2 to cause the current source 2 to start supplying the alternating current I having the second current value I2 to the measurement target 9. In this case, the current source 2 starts outputting the reference signal Sr (rectangular wave signal whose phase is adjusted) to the synchronous detection unit 4 in conjunction with the start of supply of the alternating current I having the second current value I2.

  As a result, the voltage detection unit 3 outputs a detection signal S1 whose voltage value changes in accordance with a change in the voltage value of the AC voltage Vob generated in the measurement object 9, and the synchronous detection unit 4 outputs the detection signal S1 as a current. Synchronous detection with the reference signal Sr output from the source 2 generates a detection signal S2 and outputs the detection signal S2 to the filter unit 5. The filter unit 5 outputs the second DC component Vdc2 of the detection signal S2, and A / D The converter 6 outputs voltage data Dv indicating the voltage value of the second DC component Vdc2 to the processor 7. The processing unit 7 inputs the voltage data Dv and stores it in correspondence with the second current value I2. Thereby, the detection process of the detection signal S1 when the current value of the alternating current I is the second current value I2 is completed.

  Subsequently, the processing unit 7 performs a calculation process of the AC resistance value Rx (step 53). In this calculation process, the processing unit 7 calculates the first DC component Vdc1 based on the stored voltage data Dv indicating the voltage value of the first DC component Vdc1, and indicates the stored voltage value of the second DC component Vdc2. The second DC component Vdc2 is calculated based on the voltage data Dv, and the calculated DC components Vdc1 and Vdc2 and the known current values I1 and I2 are substituted into the above-described AC resistance value Rx equation (1). Then, the AC resistance value Rx is calculated. Further, the processing unit 7 stores the calculated AC resistance value Rx in a memory. Thereby, the resistance measurement process 50 is completed.

  Finally, the processing unit 7 executes an output process to display the calculated AC resistance value Rx on the screen of the output unit 8 as the measured AC resistance value Rx of the measuring object 9. Thus, the measurement for the AC resistance value Rx of the measuring object 9 is completed.

  As described above, in the AC resistance measurement device 1 and the AC resistance measurement method, the current value of the AC current I supplied to the measurement target 9 is switched between the first current value I1 and the second current value I2, and each current value I1 is switched. , I2 and DC components Vdc1 and Vdc2 are calculated, and the AC resistance value Rx is calculated based on only the current values I1 and I2 and the DC components Vdc1 and Vdc2, that is, without being affected by the noise voltage Vn ( taking measurement. Specifically, the AC resistance value Rx is calculated by substituting the current values I1 and I2 and the DC components Vdc1 and Vdc2 into the above equation (1) of the AC resistance value Rx that does not include the noise voltage Vn as parameters. (taking measurement.

  Therefore, according to the AC resistance measuring device 1 and the AC resistance measuring method, the noise voltage Vn is included in the AC voltage Vob generated between both ends of the measurement object 9, and the frequency of the noise voltage Vn is equal to the AC current I. If the amplitude of the noise voltage Vn can be considered to be constant even when the frequency is the same frequency as the AC frequency Rn, the AC resistance value Rx can be calculated (measured) with sufficient measurement accuracy without being affected by the noise voltage Vn. it can.

(Second Embodiment)
First, the configuration of an AC resistance measuring device (hereinafter also simply referred to as “measuring device”) 1A will be described with reference to FIG. In addition, about the structure same as the measuring apparatus 1, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  As shown in FIG. 1, the measurement apparatus 1A includes, as an example, a current source 2A, a voltage detection unit 3, a synchronous detection unit 4A, a filter unit 5, an A / D conversion unit 6, a processing unit 7A, and an output unit 8. The AC resistance value Rx of the measuring object 9 can be measured.

  The current source 2A is composed of an alternating current source, and is configured to be able to supply the alternating current I to the measuring object 9 via the capacitor C1. In addition, the current source 2A controls the current value (amplitude) of the alternating current I with the known first current value I1 and the first current value under the control of the processing unit 7A in a state where the frequency of the alternating current I is kept constant. It is configured to be switchable to at least two stages of a known second current value I2 different from the current value I1. That is, the current source 2A switches and outputs the alternating current I between I1 × sin (w1 × t) and I2 × sin (w1 × t). Further, the current source 2A is a reference signal Sr synchronized with the alternating current I (in this example, the alternating current I whose phase is adjusted to be in phase with a detection signal S1 described later output from the voltage detector 3). Is output to the synchronous detector 4A.

  The voltage detector 3 detects the AC voltage Vob generated between both ends of the measurement object 9 and outputs a detection signal S1. In this case, the AC voltage Vob is represented by Rx × I1 × sin (w1 × t) when the current value of the AC current I is the first current value I1, and the current value of the AC current I is the second current value I2. Is represented by Rx × I2 × sin (w1 × t).

  On the other hand, when the noise voltage Vn (the voltage value is also expressed by Vn) is generated between both ends of the measurement object 9 due to the influence of the external noise, the AC voltage Vob has the current value of the alternating current I as the first current value. When I1, it is expressed as Rx × I1 × sin (w1 × t) + Vn × [sin (w1 × t) + sin (w2 × t)], and when the current value of the alternating current I is the second current value I2, Rx XI2 * sin (w1 * t) + Vn * [sin (w1 * t) + sin (w2 * t)]

As shown in FIG. 4, the synchronous detection unit 4 </ b> A is configured to include a multiplier 21, and the detection signal S <b> 1 output from the voltage detection unit 3 and the reference signal Sr output from the current source 2 </ b> A are multiplier 21. And is output as a detection signal (multiplication signal) S2. Thereby, when the above-described noise voltage is generated in the measurement object 9 and the current value of the alternating current I is the first current value I1, the detection signal S2 is
Rx × I1 ² × sin ² (w1 × t) + Vn × I1 × [sin ² (w1 × t) + sin (w1 × t) × sin (w2 × t)]
= Rx × I1 ² × [1-cos (2 × w1 × t)] / 2
+ Vn × I1 × [1-cos (2 × w1 × t)] / 2
+ Vn × I1 × sin (w1 × t) × sin (w2 × t)
When the current value of the alternating current I is the second current value I2, the detection signal S2 is
Rx × I2 ² × sin ² (w1 × t) + Vn × I2 × [sin ² (w1 × t) + sin (w1 × t) × sin (w2 × t)]
= Rx * I2 < ² > * [1-cos (2 * w1 * t)] / 2
+ Vn × I2 × [1-cos (2 × w1 × t)] / 2
+ Vn × I2 × sin (w1 × t) × sin (w2 × t)
It is represented by

The filter unit 5 is composed of a low-pass filter, and extracts and outputs the DC component Vdc of the detection signal S2. With this configuration, the DC voltage Vdc (first DC component Vdc1) when the noise voltage is generated in the measurement target 9 and the current value of the AC current I is the first current value I1 is:
Vdc1 = (Rx × I1 ² + Vn × I1) / 2
The DC component Vdc (second DC component Vdc2) when the current value of the AC current I is the second current value I2 is
Vdc2 = (Rx × I2 ² + Vn × I2) / 2
It is represented by The DC component Vdc represents the power loss in the measurement object 9 when the AC current I is supplied.

  The A / D converter 6 converts the DC component Vdc (the first DC component Vdc1 or the second DC component Vdc2) into voltage data Dv indicating the voltage value of the DC component Vdc by sampling in a predetermined sampling cycle. And output to the processing unit 7A.

The processing unit 7A includes a CPU and a memory (both not shown), and executes a resistance measurement process for measuring the AC resistance value Rx and an output process for the measured AC resistance value Rx. In this case, the known first current value I1 and second current value, and the following equation (2) for calculating the AC resistance value Rx are stored in advance in the memory.
Rx = 2 × (I1 × A1-I2 × A2) / (I1-I2) (2)

In the resistance measurement process, the processing unit 7A calculates the first DC component Vdc1 and the calculated first DC component Vdc1 based on the voltage data Dv when the current value of the AC current I is the first current value I1. the by dividing by the square value I1 ² of the first current value I1, and calculates the first division value A1. Further, the processing unit 7A calculates the second DC component Vdc2 based on the voltage data Dv when the current value of the AC current I is the second current value I2, and the calculated second DC component Vdc2 as the second current. It is divided by the square value I2 ² value I2, and calculates the second division value A2. Further, the processing unit 7A calculates the AC resistance value Rx by substituting the calculated divided values A1 and A2 and the known current values I1 and I2 into the above-described equation (2) of the AC resistance value Rx. .

  Next, the above formula (2) for calculating the AC resistance value Rx will be described.

First, the first division value A1 calculated as described above is expressed by the following equation.
A1 = Vdc1 / I1 ² = (Rx × I1 ² + Vn × I1) / (2 × I1 ² )
= Rx / 2 + Vn / (2 × I1)

Further, the second division value A2 calculated as described above is represented by the following equation.
A2 = Vdc2 / I2 ² = (Rx × I2 ² + Vn × I2) / (2 × I2 ² )
= Rx / 2 + Vn / (2 × I2)

  Here, even if the voltage value of the noise voltage Vn fluctuates, the detection signal S1 at the second current value I2 from the start of detection of the detection signal S1 at the first current value I1 by the voltage detector 3. By sufficiently shortening the period until the end of the detection, it is possible to make the voltage value of the noise voltage Vn substantially constant during this period. Therefore, when the voltage value of the noise voltage Vn can be considered to be constant, the noise voltage Vn is eliminated from the respective expressions of the above-described divided values A1 and A2, and the AC resistance value Rx is solved to solve the above. Equation (2) for calculating the AC resistance value Rx is obtained.

  The output unit 8 includes a display device as an example, and displays the AC resistance value Rx measured by the processing unit 7A on the screen.

  Next, the measuring operation of the AC resistance value Rx for the measuring object 9 by the measuring apparatus 1A will be described with reference to the drawings.

  In the measurement of the AC resistance value Rx, in the measurement apparatus 1A, the processing unit 7A executes the resistance measurement process 60 shown in FIG. In the resistance measurement process 60, the processing unit 7A first executes a detection process of the detection signal S1 when the current value of the alternating current I is the first current value I1 (step 61). In this detection process, the processing unit 7A executes control of the current source 2A, thereby causing the current source 2A to start supplying the alternating current I having the first current value I1 to the measurement target 9. In this case, the current source 2A is configured to supply the reference signal Sr (the alternating current I having the first current value I1 whose phase is adjusted) to the synchronous detection unit 4A in conjunction with the start of the supply of the alternating current I having the first current value I1. Start output.

  As a result, the voltage detection unit 3 outputs a detection signal S1 whose voltage value changes in accordance with a change in the voltage value of the AC voltage Vob generated in the measuring object 9, and the synchronous detection unit 4A outputs the detection signal S1 and the current The reference signal Sr output from the source 2A is multiplied and output to the filter unit 5 as the detection signal S2. The filter unit 5 outputs the first DC component Vdc1 of the detection signal S2, and the A / D conversion unit 6 Outputs voltage data Dv indicating the voltage value of the first DC component Vdc1 to the processing unit 7A. The processing unit 7A receives the voltage data Dv and stores it corresponding to the first current value I1. Thereby, the detection process of the detection signal S1 when the current value of the alternating current I is the first current value I1 is completed.

  Next, the processing unit 7A performs detection processing of the detection signal S1 when the current value of the alternating current I is the second current value I2 (step 62). In this detection process, the processing unit 7A executes control of the current source 2A, thereby causing the current source 2A to start supplying the alternating current I having the second current value I2 to the measurement target 9. In this case, the current source 2A is configured to supply the reference signal Sr (the AC current I having the second current value I2 whose phase is adjusted) to the synchronous detection unit 4A together with the start of the supply of the AC current I having the second current value I2. Start output.

  As a result, the voltage detection unit 3 outputs a detection signal S1 whose voltage value changes in accordance with a change in the voltage value of the AC voltage Vob generated in the measuring object 9, and the synchronous detection unit 4A outputs the detection signal S1 and the current The reference signal Sr output from the source 2A is multiplied and output to the filter unit 5 as the detection signal S2. The filter unit 5 outputs the second DC component Vdc2 of the detection signal S2, and the A / D conversion unit 6 Outputs the voltage data Dv indicating the voltage value of the second DC component Vdc2 to the processing unit 7A. The processing unit 7A receives the voltage data Dv and stores it corresponding to the second current value I2. Thereby, the detection process of the detection signal S1 when the current value of the alternating current I is the second current value I2 is completed.

Subsequently, the processing unit 7A executes a calculation process of the first division value A1 (step 63). In this calculation process, the processing unit 7A calculates the first DC component Vdc1 based on the voltage data Dv when the current value of the AC current I is the first current value I1, and the calculated first DC component Vdc1. It is divided by the square value I1 ² of the first current value I1, and calculates the first division value A1. Further, the calculated first division value A1 is stored in the memory.

Next, the processing unit 7A executes a calculation process of the second division value A2 (step 64). In this calculation process, the processing unit 7A calculates the second DC component Vdc2 based on the voltage data Dv when the current value of the AC current I is the second current value I2, and calculates the calculated second DC component Vdc2. It is divided by the square value I2 ² of the second current value I2, to calculate a second division value A2. The processing unit 7A stores the calculated second division value A2 in the memory.

  Subsequently, the processing unit 7A executes a calculation process of the AC resistance value Rx (step 65). In this calculation process, the processing unit 7A substitutes the calculated divided values A1 and A2 and the known current values I1 and I2 into the above-described equation (2) of the AC resistance value Rx, and the AC resistance value Rx. Is calculated. Further, the processing unit 7A stores the calculated AC resistance value Rx in a memory. Thereby, the resistance measurement process 60 is completed.

  Finally, the processing unit 7A executes an output process to display the calculated AC resistance value Rx on the screen of the output unit 8 as the measured AC resistance value Rx of the measuring object 9. Thus, the measurement for the AC resistance value Rx of the measuring object 9 is completed.

  As described above, in the AC resistance measuring apparatus 1A and the AC resistance measuring method, the current value of the AC current I supplied to the measurement target 9 is switched between the first current value I1 and the second current value I2, and each current value I1 is switched. , I2 is calculated, and the AC resistance value Rx is calculated based on only the current values I1, I2 and the divided values A1, A2, that is, without being affected by the noise voltage Vn ( taking measurement. Specifically, the AC resistance value Rx is calculated by substituting the current values I1 and I2 and the divided values A1 and A2 as parameters into the above-described AC resistance value Rx expression (2) not including the noise voltage Vn. (taking measurement.

  Therefore, according to the AC resistance measuring apparatus 1A and the AC resistance measuring method, the noise voltage Vn is included in the AC voltage Vob generated across the measurement object 9, and the frequency of the noise voltage Vn is equal to the AC current I. If the amplitude of the noise voltage Vn can be considered to be constant even when the frequency is the same frequency as the AC frequency Rn, the AC resistance value Rx can be calculated (measured) with sufficient measurement accuracy without being affected by the noise voltage Vn. it can.

Incidentally, the first DC component Vdc1 in the supply state of the AC current I of the first current value I1 is divided by the square value I1 ² of the first current value I1 to calculate a first division value A1, the second current value I2 The second DC component Vdc2 in the supply state of the AC current I is divided by the square value I2 ² of the second current value I2 to calculate a second divided value A2, and each current value I1, I2 and each divided value A1, A2 is calculated. The configuration for calculating the AC resistance value Rx using the equation (2) for the AC resistance value Rx as a parameter has been described above, but the calculation of the first division value A1 and the calculation of the second division value A2 should be executed. In the following equation (3) for the AC resistance value Rx obtained by eliminating the noise voltage Vn from the equation for each DC component Vdc1, Vdc2 representing the power loss in the measurement object 9, the DC component Vdc1 , Vdc2 and each By substituting current values I1, I2, it is possible to use a construction for calculating (measuring) the alternating current resistance value Rx. However, the following expression (3) is obtained by substituting the above-described expression A1 (Vdc1 / I1 ² ) and the expression A2 (Vdc2 / I2 ² ) into the expression (2) for the AC resistance value Rx. Since this is an equation, it is substantially equivalent to this equation (2).
Rx = 2 × (Vdc1 × I2−Vdc2 × I1) / (I1 ² × I2−I2 ² × I1) (3)

  In addition, although the case where the battery was mentioned as an example of the measuring object 9 and the case where the alternating current resistance value (internal resistance) was calculated was demonstrated, it is not limited to a battery, the alternating current resistance value of an electronic component, the alternating current resistance value of an apparatus The AC resistance measuring device 1A and the AC resistance measuring method described above can also be applied to measurements such as (AC insulation resistance value).

DESCRIPTION OF SYMBOLS 1,1A AC resistance measuring apparatus 2,2A Current source 3 Voltage detection part 4,4A Synchronous detection part 5 Filter part 7,7A Processing part 9 Measuring object A1 1st division value A2 2nd division value I AC current I1 1st current Value I2 Second current value Rx AC resistance value Vdc DC component Vdc1 First DC component Vdc2 Second DC component Vob AC voltage

Claims (4)

A current source that supplies an alternating current to the measurement target, a voltage detection unit that detects an alternating voltage generated in the measurement target in the supply state of the alternating current, and a reference signal that synchronizes the detected alternating voltage with the alternating current A synchronous detection unit that performs synchronous detection and outputs a detection signal; a filter unit that extracts a DC component of the detection signal; and an AC resistance of the measurement object based on the extracted DC component and the current value of the AC current An AC resistance measuring device comprising a processing unit for calculating a value,
The current source is configured to be able to switch the current value of the alternating current to one of a first current value and a second current value different from the first current value,
The processing unit is configured to output the first direct current component as the direct current component output from the filter unit in the supply state of the alternating current having the first current value, the first current value, and the alternating current having the second current value. An AC resistance measuring device that calculates the AC resistance value based on the second DC component as the DC component output from the filter unit and the second current value in the supply state. The synchronous detection unit is configured to include a signal inverter and a switch, and generates an inverted AC voltage by inverting the polarity of the detected AC voltage using the signal inverter, and the AC voltage and the inverter Output as the detection signal by switching the AC signal in synchronization with the reference signal in the switch,
When the first current value is I1, the first DC component is Vdc1, the second current value is I2, and the second DC component is Vdc2, the processing unit is equivalent to the following formula: The AC resistance measuring device according to claim 1, wherein the AC resistance value is calculated based on
π / 2 × (Vdc1−Vdc2) / (I1−I2) The synchronous detection unit includes a multiplier, and inputs the alternating current as the reference signal, and multiplies the detected alternating voltage and the alternating current by the multiplier as the detection signal. Output,
The processing unit equivalently calculates the first divided value by dividing the first DC component by the square value of the first current value, and calculates the second DC component by the square value of the second current value. Dividing and calculating the second divided value, when the first current value is I1, the first divided value is A1, the second current value is I2, and the second divided value is A2, The AC resistance measuring device according to claim 1, wherein the AC resistance value is calculated based on the following formula.
2 × (I1 × A1-I2 × A2) / (I1-I2) Detecting an alternating voltage generated in the measurement target in a state where an alternating current is supplied to the measurement target, synchronously detecting the detected alternating voltage with a reference signal synchronized with the alternating current, and outputting a detection signal, An AC resistance measurement method for extracting a DC component of the detection signal and calculating an AC resistance value of the measurement object based on the extracted DC component and the current value of the AC current,
In the supply state of the alternating current of the first direct current component as the direct current component extracted in the supply state of the alternating current of the first current value, the first current value, and the second current value different from the first current value. An AC resistance measurement method for calculating the AC resistance value based on the extracted second DC component as the DC component and the second current value.

Images