JP5626869B2 - measuring device - Google Patents

Description

  The present invention relates to a measuring apparatus that measures at least one of a pure resistance component and a reactance component of a circuit to be measured.

  As this type of measuring apparatus, a resistance measuring apparatus disclosed in Patent Document 1 below is known. This resistance measuring device includes an injection transformer for injecting into the circuit network a current at a second frequency that can be distinguished from the current at the first frequency flowing in the circuit network to be measured (circuit to be measured), A detection transformer (detection coil) that detects the two types of current flowing above, a frequency selection circuit that extracts a second frequency component from the output of the detection transformer, and an output of the frequency selection circuit are displayed. And an injection transformer having an injection coil that receives the output voltage of the oscillator and injects a second frequency current into the circuit under test, and a feedback coil. The feedback loop is configured to vary the voltage supplied to the injection coil so that the induced voltage is controlled to a constant value.

  In this resistance measuring apparatus, the voltage induced in the feedback coil is obtained by dividing the voltage induced in the feedback coil by the ratio of the number of windings of the feedback coil to the number of connected wires of the circuit under test (the number of the transformers for injection, one). Since the injection voltage is also controlled to a constant value, it is connected to this detection transformer by detecting the voltage generated in the resistor connected to this detection transformer due to the current flowing through the detection transformer. A resistance element connected to the circuit under test based on the resistance value of the resistor, the voltage generated in the resistor, the voltage generated in the feedback coil, the number of turns of the injection coil and the number of turns of the detection transformer (detection coil) The value (resistance to be measured) can be measured.

JP 55-90862 A (page 1-4, FIG. 2)

  By the way, since the inductance of the wiring always exists in the circuit to be measured to which the resistance to be measured is connected, the value of the resistance to be measured measured by the above resistance measuring device includes the pure resistance of the resistance to be measured. In addition to the resistance component, a reactance component due to the inductance is included. For this reason, there is a desire to accurately measure the pure resistance component of the resistance to be measured, but the resistance value measured by the resistance measuring device includes the pure resistance component of the resistance to be measured and the reactance component. Therefore, there is a problem that this request cannot be realized. In some cases, it may be necessary to separate and measure only the reactance component. However, the resistance measuring apparatus has a problem that the reactance component cannot be separated and measured.

  The present invention has been made to solve such a problem, and a main object of the present invention is to provide a measuring apparatus that can measure at least one of a pure resistance component and a reactance component of a circuit to be measured.

In order to achieve the above object, the measuring apparatus according to claim 1 is caused by injecting an AC signal for inspection into a circuit to be measured by applying an AC voltage to the injection coil, and injecting the AC signal for inspection. And detecting the alternating current flowing in the circuit to be measured by the detection coil and outputting a detection signal whose amplitude changes according to the amplitude of the alternating current based on the current detection signal output from the detection coil And calculating a current value of the alternating current based on the detection signal and a pure resistance component of the circuit to be measured based on the calculated current value of the alternating current and a voltage value of the injected AC signal for inspection And a processing unit that calculates at least one of the reactance components as a measurement value, the measurement device having the same period as the fundamental wave of the AC voltage, and the AC voltage A first signal generation unit that generates and outputs a first signal synchronized with the main wave; and a second signal generation unit that generates and outputs a second signal whose phase is orthogonal to the first signal; The current detection unit outputs, as the detection signal, a first detection signal whose amplitude changes according to the amplitude of the real component of the alternating current by synchronously detecting the current detection signal using the first signal. The second detection signal whose amplitude varies according to the amplitude of the imaginary component of the alternating current by synchronously detecting the current detection signal using the second signal is output as the detection signal. An absolute value of the current value of the alternating current is calculated based on the first detection signal and the second detection signal, and the measurement target circuit is calculated based on the calculated absolute value and the voltage value of the inspection AC signal. Impi A resistance value calculating process for calculating an absolute value of a dance, and a phase angle calculating process for calculating a phase angle between the AC current and the AC signal for inspection based on the first detection signal and the second detection signal; In the measurement device that performs the measurement value calculation process for calculating the measurement value based on the calculated absolute value of the impedance and the phase angle , the operation unit includes a display unit, and the processing unit includes the operation unit According to the operation content of the circuit, the inductance and capacitance of the measurement target circuit calculated based on the pure resistance component, the reactance component, the absolute value of the impedance, the reactance component, and the frequency of the AC voltage, respectively, and the first One of the phase angles calculated based on one detection signal and the second detection signal is selected and displayed on the display unit In addition, when the phase angle is out of a predetermined angle range, a symbol indicating that is displayed on the display unit.
According to a second aspect of the present invention, there is provided the measuring apparatus according to the second aspect, wherein a voltage injection unit that injects an AC signal for inspection into a circuit to be measured by applying an AC voltage to the injection coil, and the measurement due to the injection of the AC signal for inspection. A current detection unit that detects an alternating current flowing through the target circuit with a detection coil and outputs a detection signal whose amplitude changes in accordance with the amplitude of the alternating current based on a current detection signal output from the detection coil; and the detection The current value of the alternating current is calculated based on the signal, and the pure resistance component and reactance component of the circuit under measurement are calculated based on the calculated current value of the alternating current and the voltage value of the injected alternating current signal for inspection. A measuring unit including at least one processing unit that calculates a measurement value, and having the same period as the fundamental wave of the AC voltage and synchronized with the fundamental wave of the AC voltage. A first signal generation unit that generates and outputs a first signal; and a second signal generation unit that generates and outputs a second signal whose phase is orthogonal to the first signal, and the current detection unit includes: The first detection signal whose amplitude changes according to the amplitude of the real component of the alternating current by synchronously detecting the current detection signal using the first signal is output as the detection signal, and the current detection signal Is detected using the second signal to output a second detection signal whose amplitude changes according to the amplitude of the imaginary component of the alternating current as the detection signal, and the processing unit is configured to output the first detection signal. And calculating the absolute value of the current value of the alternating current based on the second detection signal and calculating the absolute value of the impedance of the circuit to be measured based on the calculated absolute value and the voltage value of the AC signal for inspection. A resistance value calculation process for calculating a phase angle calculation process for calculating a phase angle between the AC current and the AC signal for inspection based on the first detection signal and the second detection signal, and the calculated In a measurement apparatus that executes a measurement value calculation process for calculating the measurement value based on an absolute value of impedance and the phase angle, the operation unit, and a display unit having a main numerical value display region and a sub numerical value display region, The processing unit is respectively calculated based on the pure resistance component, the reactance component, the absolute value of the impedance, the reactance component, and the frequency of the AC voltage according to the operation content of the operation unit. And the phase angle calculated based on the first detection signal and the second detection signal. Two are selected and displayed in the main numerical value display region and the sub numerical value display region, and when the phase angle is outside a predetermined angle range, a symbol indicating that is displayed on the display unit.
According to a third aspect of the present invention, there is provided a measuring apparatus that injects an AC signal for inspection into a circuit to be measured by applying an AC voltage to an injection coil, and the measurement due to the injection of the AC signal for inspection. A current detection unit that detects an alternating current flowing through the target circuit with a detection coil and outputs a detection signal whose amplitude changes in accordance with the amplitude of the alternating current based on a current detection signal output from the detection coil; and the detection The current value of the alternating current is calculated based on the signal, and the pure resistance component and reactance component of the circuit under measurement are calculated based on the calculated current value of the alternating current and the voltage value of the injected alternating current signal for inspection. A measuring unit including at least one processing unit that calculates a measurement value, and having the same period as the fundamental wave of the AC voltage and synchronized with the fundamental wave of the AC voltage. A first signal generation unit that generates and outputs a first signal; and a second signal generation unit that generates and outputs a second signal whose phase is orthogonal to the first signal, and the current detection unit includes: The first detection signal whose amplitude changes according to the amplitude of the real component of the alternating current by synchronously detecting the current detection signal using the first signal is output as the detection signal, and the current detection signal Is detected using the second signal to output a second detection signal whose amplitude changes according to the amplitude of the imaginary component of the alternating current as the detection signal, and the processing unit is configured to output the first detection signal. And calculating the absolute value of the current value of the alternating current based on the second detection signal and calculating the absolute value of the impedance of the circuit to be measured based on the calculated absolute value and the voltage value of the AC signal for inspection. A resistance value calculation process for calculating a phase angle calculation process for calculating a phase angle between the AC current and the AC signal for inspection based on the first detection signal and the second detection signal, and the calculated In a measurement apparatus that executes a measurement value calculation process for calculating the measurement value based on an absolute value of impedance and the phase angle, the operation unit, and a display unit having a main numerical value display region and a sub numerical value display region, The processing unit calculates at least one of an inductance and a capacitance of the measurement target circuit based on the reactance component and the frequency of the AC voltage, and the pure resistance component and the reactance component according to an operation content on the operation unit. And one of the absolute values of the impedance is selected and displayed in the main numerical value display area, and the net resistance is selected. Select one of the anti-component, the reactance component, and the absolute value of the impedance other than those displayed in the main numerical value display area, the calculated inductance, capacitance, and the phase angle. When the phase value is displayed in the sub-numerical value display area and the phase angle is out of a predetermined angle range, a symbol indicating that is displayed on the display unit.

According to a fourth aspect of the present invention, in the measurement apparatus according to any one of the first to third aspects, the voltage injection unit is based on an original signal generation unit that generates an alternating current original signal, and the alternating current original signal. A phase shift unit that generates two AC signals whose phases are orthogonal to each other, and applies one AC signal of the two AC signals as the AC voltage to the injection coil, and the first signal generation unit Generates the first signal based on the one of the two signals generated in the voltage injection unit, and the second signal generation unit generates the second signal generated in the voltage injection unit. The second signal is generated based on the other signal of the two signals.

The measuring apparatus according to claim 5 is the measuring apparatus according to any one of claims 1 to 4 , wherein the first signal generation unit shapes and outputs the first signal into a rectangular wave, and The two-signal generation unit shapes and outputs the second signal into a rectangular wave, and the current detection unit inverts the current detection signal and outputs the inverted signal as an inverted detection signal, the current detection signal, and the current detection signal First and second switching units that input an inversion detection signal and selectively output either one of the current detection signal and the inversion detection signal based on the first signal. The current detection signal is synchronously detected by switching and output, and the second switching unit switches and outputs the current detection signal and the inverted detection signal based on the second signal. Same Detection to.

Further, the measurement device according to claim 6 is the measurement device according to any one of claims 1 to 3 , wherein the voltage injection unit includes a memory, a CPU, a D / A conversion circuit, a filter, and a power amplification unit. Digital data for alternating current original signal, digital data for the first signal whose phase matches the alternating current original signal, and digital data for the second signal whose phase is shifted by 90 ° with respect to the alternating current original signal Is stored in advance in the memory, and the CPU stores the digital data for the AC original signal, the first signal, and the second signal in a predetermined cycle from the data table. And repeatedly executing the operation of sequentially reading out at the same time, outputting the digital data for the AC original signal to the D / A conversion circuit, and for the first signal and the first signal. Each digital data for signal is output from a corresponding output port to generate the first signal and the second signal, and the D / A converter circuit converts the input digital data for the AC original signal into a triangular wave The filter converts the triangular wave signal into the alternating current signal and outputs the alternating current signal, and the power amplifier generates the alternating voltage based on the alternating current signal to generate the injection coil. Apply to.

According to the measuring apparatus of claims 1 , 2, and 3 , the current detection unit synchronizes (same phase) the current detection signal output from the injection coil with the same period as the fundamental wave of the AC voltage. By performing synchronous detection using one signal, a first detection signal whose amplitude changes in accordance with the amplitude of the real component of the alternating current flowing in the circuit to be measured is output, and the current detection signal is orthogonal to the first signal in phase. By performing synchronous detection using the second signal, the second detection signal whose amplitude changes according to the amplitude of the imaginary component of the alternating current flowing in the measurement target circuit is output, and the processing unit outputs the first and second signals. By executing the resistance value calculation process, the phase angle calculation process, and the measurement value calculation process based on the detection signal, the pure resistance component and the reactance component of the circuit to be measured can be separately calculated.
In addition, according to the measuring apparatus of the first aspect, the user operates the operation unit to obtain a desired measured value (from the absolute value of impedance, the pure resistance component, the reactance component, the inductance, the capacitance, and the phase angle). Parameter) can be selected and displayed on the display unit for confirmation.
According to the measuring apparatus of the second aspect, the desired two measured values (parameters) are selected from the absolute value of the impedance, the pure resistance component, the reactance component, the inductance, the capacitance, and the phase angle, and the display unit is selected. Since it can be displayed in the main numerical value display area and the sub numerical value display area, two measured values can be confirmed simultaneously.
In addition, according to the measuring apparatus of the third aspect, it is possible to confirm one parameter selected from the absolute value of impedance, the pure resistance component, and the reactance component, and the absolute value of impedance, the pure resistance component, and the reactance component. It is possible to simultaneously confirm another parameter selected from the parameters other than the one parameter, the inductance of the measurement target circuit, the capacitance of the measurement target circuit, and the phase angle.
In addition, according to the measurement apparatus of the first, second, and third aspects, when the calculated phase angle is out of a predetermined angle range, the reactance component of the measurement target circuit is relatively increased on the display unit. Since the symbol indicating that it is (dominant) is displayed, the error is large for the pure resistance component displayed on the display unit, that is, the accuracy is reduced. This can be notified.

In the measurement device according to claim 4 , the phase shift unit of the voltage injection unit generates two AC signals whose phases are orthogonal to each other based on the AC original signal output from the original signal generation unit, and the voltage injection unit Applies one AC signal of the two AC signals as an AC voltage to the injection coil, and the first signal generator generates one of the AC signals described above of the two AC signals generated by the phase shift unit. The first signal is generated based on the second signal generation unit, and the second signal generation unit generates the second signal based on the other AC signal of the two AC signals generated by the phase shift unit.

  Therefore, according to this measuring apparatus, the phase shift unit is arranged inside the measuring apparatus, and two alternating currents that are orthogonal to each other based on the alternating current original signal output from the original signal generating unit that is not easily affected by the outside. A signal can be generated. For this reason, according to this measuring apparatus, as a result that the phase difference between the first signal and the second signal generated based on the two AC signals can be stably maintained at 90 °, the first switching unit and the second switching unit can be maintained. The synchronous detection of the first detection signal whose amplitude changes according to the amplitude of the real component of the alternating current flowing through the circuit to be measured and the second detection signal whose amplitude changes according to the amplitude of the imaginary component of this alternating current Since the data can be output with high accuracy, the processing unit can calculate the pure resistance component and the reactance component of the measurement target circuit with high accuracy based on the first and second detection signals with high accuracy.

Further, in the measuring apparatus according to claim 5 , the first signal generation unit and the second signal generation unit adopt a configuration in which the first signal and the second signal are shaped into a rectangular wave and output, respectively. In the first detection unit and the second switching unit that selectively output one of the current detection signal and the inversion detection signal, the first detection signal and the second detection signal can be synchronously detected based on the current detection signal. Since detection is possible, for example, the first switching unit and the second switching unit can be configured using analog switches, and as a result, the configuration of the current detection unit can be simplified.

According to the measuring apparatus of the sixth aspect , the digital circuit is used, and the triangular wave signal, the first signal, and the second signal are based on the digital data for the AC original signal, the first signal, and the second signal. With the configuration for generating a signal, a first signal having a phase difference of zero (phase matched) and a second signal having a phase shifted by 90 ° with respect to the AC voltage generated from the triangular wave signal , Stable and easy to produce.

It is a block diagram which shows the structure of the measuring apparatus 1, 1B, 1C. 3 is a circuit diagram excluding a direct current amplifier 35 in a current detector 6 of the measuring apparatus 1. FIG. It is a wave form diagram for demonstrating the operation | movement of the synchronous detection in the electric current detection part. It is a block diagram which shows the structure of 1 A of other measuring devices. It is a circuit diagram except the direct current amplifier 35 in the other current detector 6A. It is a wave form diagram for demonstrating the operation | movement of the synchronous detection in 6 A of electric current detection parts. It is explanatory drawing for demonstrating the structure of an example of the output part 8 as a display part. It is explanatory drawing for demonstrating the structure of another example of the output part 8 as a display part. FIG. 9 is an explanatory diagram showing combinations of parameters displayed in a numerical value display area 51 and a sub numerical value display area 54 in the output unit 8 of FIG. 8. It is explanatory drawing for demonstrating the structure of another example of the output part 8 as a display part. It is explanatory drawing for demonstrating the structure of another example of the output part 8 as a display part. FIG. 12 is an explanatory diagram showing additional combinations of parameters displayed in the numerical value display area 51 and the sub numerical value display area 54 in the output unit 8 of FIG. 11. 4 is a block diagram for explaining a configuration of a general signal generation unit 61. FIG. It is explanatory drawing for demonstrating the content of the data table Dst memorize | stored in the memory 62b of FIG. 6 is a waveform diagram for explaining the operation of the overall signal generation unit 61. FIG.

  Hereinafter, embodiments of a measuring apparatus will be described with reference to the accompanying drawings.

  First, the configuration of the measuring apparatus 1 will be described with reference to the drawings.

  A measuring apparatus 1 shown in FIG. 1 includes a clamp sensor 2, a voltage injection unit 3, a first signal generation unit 4, a second signal generation unit 5, a current detection unit 6, a processing unit 7, and an output unit 8, and includes a measurement target circuit. 9 resistance (loop resistance) R of pure resistance component Rr and reactance component Rx can be measured as measured values.

  As an example, the clamp sensor 2 includes an injection clamp 11 and a detection clamp 12 configured to be attachable (clampable) to the measurement target circuit 9 as shown in FIG.

  As shown in FIG. 1, the injection clamp 11 includes a ring-shaped core 11a configured to be separable, an injection coil 11b (known number of turns: N1) wound around the core 11a, and a feedback coil 11c. Since the core 11a is divided, the measurement target circuit 9 can be mounted. As shown in FIG. 1, the detection clamp 12 includes an annular core 12a configured to be separable, and a detection coil 12b (known number of turns: N2) wound around the core 12a. The core 12a is divided. As a result, it can be mounted on the circuit 9 to be measured. In addition, when the injection clamp 11 and the detection clamp 12 are attached (clamped) to the wiring 9a constituting a part of the measurement target circuit 9, the wiring 9a is wound by one turn in each of the cores 11a and 12a. Acts as a line.

  As an example, the voltage injection unit 3 includes an original signal generation unit 21, a phase shift unit (90 ° phase shift) 22, a power amplification unit 23, and a feedback unit 24. As an example, the original signal generation unit 21 includes a staircase wave generation unit 21a and a low-pass filter (hereinafter also referred to as “LPF”) 21b, and generates and outputs an AC voltage (AC original signal) Va. Specifically, the staircase wave generation unit 21a generates and outputs a triangular wave signal Vt having a predetermined period T (frequency f). This triangular wave signal Vt is an example of a staircase wave, and, as shown in the figure, the shape of a triangular wave having a constant amplitude as a whole, with the amplitude changing stepwise (stepwise) in the cycle Tc of the reference clock CLK. Is a signal.

  As an example, such a staircase wave generation unit 21a includes a counter that can selectively execute one of an up-count operation and a down-count operation in synchronization with the reference clock CLK, and an up-count operation and a down-count for this counter. Flip-flop for repeatedly executing the count operation, D / A conversion circuit for generating a staircase wave based on the count value output from each counter output terminal of the counter, and a capacitor for cutting a DC component included in the staircase wave (Both not shown). The LPF 21b receives the triangular wave signal Vt and mainly passes the fundamental frequency component (frequency f) and attenuates the other frequency components (by selectively passing the fundamental frequency component), thereby generating an AC voltage ( In this example, it is converted into a pseudo sine wave voltage (Va) and output as an example.

  For example, the phase shift unit 22 includes two systems of phase shift circuits (not shown) that input a sine wave voltage (pseudo sine wave voltage) Va and shift the waveform by a predetermined phase and output it. The difference in phase shift amount in the phase shift circuit is defined as 90 °. With this configuration, the phase shift unit 22 generates and outputs two types of alternating current signals Va1 and Va2 (in this example, sinusoidal voltages) whose phases are 90 ° different from each other (the phases are orthogonal to each other). To do. In this example, as an example, it is assumed that the phase of the sine wave voltage Va1 is advanced by 90 ° with respect to the phase of the sine wave voltage Va2.

  In this example, the power amplifying unit 23 is configured as a class D amplifier, for example, and amplifies the sine wave voltage Va1 with an amplification factor controlled by the feedback unit 24, thereby preliminarily defining a voltage value (in this example, a voltage effective value). ) AC voltage (in this example, as an example, a sine wave voltage (specifically, pseudo sine wave voltage)) V1 is generated, and the generated sine wave voltage V1 is applied to the injection coil 11b of the injection clamp 11. Although not shown, the power amplifying unit 23 compares the sawtooth signal and the sine wave voltage Va1 with a signal generation circuit that generates a sawtooth signal having a constant frequency, for example, and sets the amplitude of the sine wave voltage Va1. From a PWM signal generation circuit that generates a pulse signal (PWM signal) having a predetermined period in which the pulse width (duty ratio) changes in proportion, a class D power amplification circuit that amplifies the PWM signal, and a class D power amplification circuit And a low-pass filter circuit that generates a sine wave voltage V1 by filtering the output signal.

  The feedback unit 24 detects the voltage V2 induced in the feedback coil 11c, and controls the amplification factor of the power amplification unit 23 so that the voltage V2 becomes a predetermined voltage (a constant voltage). With this configuration, the power amplifying unit 23 can always generate a sine wave voltage V1 having a constant voltage value even if the input level of the sine wave voltage Va1 and the joining condition of the annular core 11a slightly change. .

  As a result, the test AC signal Vo having a predetermined frequency f and a predetermined effective voltage value is injected into the measurement target circuit 9 via the injection clamp 11. In this case, since the wiring 9a functions as a one-turn winding in the core 11a as described above, the voltage value of the test AC signal Vo injected into the circuit to be measured 9 is the sine wave voltage V1 and the number of turns N1. The voltage value obtained by dividing by (Vo = V1 / N1). In the detection clamp 12, since the wiring 9a functions as a one-turn winding in the core 12a, the detection clamp 12 detects the alternating current Io flowing in the circuit to be measured 9, and detects the detection current (current flowing in the detection coil) I1 in the detection coil 12b. (= Io / N2) is output.

  As shown in FIG. 1, the first signal generation unit 4 includes, as an example, a comparator 4 a and a flip-flop (in this example, a D-type flip-flop (also referred to as “D-type FF”)) 4 b. A first signal S1 having the same cycle as the fundamental wave of the voltage Va1 and synchronized with the fundamental wave of the sine wave voltage Va1 is generated and output. In the first signal generation unit 4, first, the comparator 4a compares the sine wave voltage Va1 with a reference voltage (zero volts), so that the polarity is inverted at the zero cross of the sine wave voltage Va1 and the duty ratio is 0. 0. 5 (for example, a binarized signal in which the voltage is at a high level when the sine wave voltage Va1 is positive and is zero volts when the sine wave voltage Va1 is negative). Next, the D-type FF 4b samples the rectangular wave signal in synchronization with the reference clock CLK, thereby synchronizing the rising and falling edges of the rectangular wave signal, which are varied during the comparison in the comparator 4a, with the reference clock CLK. A noise component asynchronous with the reference clock CLK included in the rectangular wave signal is removed (shaped into a rectangular wave) and output as the first signal S1.

  As shown in FIG. 1, the second signal generation unit 5 includes a comparator 5 a and a D-type FF 5 b and is configured in the same circuit as the first signal generation unit 4. In the second signal generation unit 5, the comparator 5a compares the sine wave voltage Va2 with the reference voltage (zero volts), so that the polarity is inverted at the zero cross of the sine wave voltage Va2, similarly to the comparator 4a, and A rectangular wave signal with a duty ratio of 0.5 is output, and the D-type FF 5b samples the rectangular wave signal in synchronization with the reference clock CLK to output it as the second signal S2.

  The current detection unit 6 includes an IV conversion (current / voltage conversion) unit 31, an inversion unit 32, a first switching unit 33, a second switching unit 34, and a DC amplification unit 35. The current detection unit 6 has an amplitude of a real component of the AC current Io. A first detection signal (detection signal) Vd1 whose amplitude changes in response to this and a second detection signal (detection signal) Vd2 whose amplitude changes in accordance with the amplitude of the imaginary component of the alternating current Io are output. In this case, the IV conversion unit 31 is connected to one end of the detection coil 12b, converts the detection current I1 generated at the one end into a current detection signal Vb1, and outputs the current detection signal Vb1. The inverting unit 32 inputs the current detection signal Vb1, inverts the polarity (in other words, shifts the phase by 180 °), and outputs the inverted detection signal Vb2.

  As shown in FIGS. 1 and 2, the first switching unit 33 inputs the current detection signal Vb1 and the inverted detection signal Vb2, and sets one of these signals Vb1 and Vb2 to the level of the first signal S1. Select and output based on (selectively output). As an example, as shown in FIG. 2, the first switching unit 33 is configured by a changeover switch (analog switch), and outputs a current detection signal Vb1 when the first signal S1 is at a high level. When the voltage is zero volts, the inversion detection signal Vb2 is output. By operating in this way, the first switching unit 33 equivalently detects the current detection signal Vb1 synchronously with the first signal S1, and outputs it as the detection signal Vc1.

  As shown in FIGS. 1 and 2, the second switching unit 34 also receives the current detection signal Vb1 and the inverted detection signal Vb2 as well as the first switching unit 33, and any one of these signals Vb1 and Vb2. One of them is selected and output based on the level of the second signal S2 (selectively output). As an example, the second switching unit 34 is configured by a switching switch (analog switch) as shown in FIG. 2 in the same manner as the first switching unit 33, and when the second signal S2 is at a high level, the current detection signal Vb1. When the second signal S2 is zero volts, the inversion detection signal Vb2 is output. By operating in this way, the second switching unit 34 equivalently detects the current detection signal Vb1 synchronously with the second signal S2 (a signal whose phase is orthogonal to the first signal S1), and outputs it as the detection signal Vc2. To do.

  In this case, the detection signal Vc1 output by the first switching unit 33 synchronously detecting and outputting based on the first signal S1 generated from the sine wave voltage Va1 having the same phase as the sine wave voltage V1 applied to the injection coil 11b is The signal changes in amplitude according to the amplitude of the current regulated by the pure resistance component Rr of the resistance R of the measurement target circuit 9 (that is, the real number component of the alternating current Io). On the other hand, the second switching unit is based on the second signal S2 generated from the sine wave voltage Va2 that is 90 ° out of phase (in this example, delayed by 90 °) with respect to the sine wave voltage V1 applied to the injection coil 11b. The detection signal Vc2 output by synchronous detection by the 34 is a signal whose amplitude changes according to the amplitude of the current regulated by the reactance component Rx of the resistance R of the measurement target circuit 9 (that is, the imaginary component of the alternating current Io). Become.

  The DC amplifying unit 35 has two systems of DC amplifying circuits (not shown), inputs the detection signals Vc1 and Vc2, and amplifies the signals at the same amplification factor in the DC amplifying circuits as first detection signals Vd1 and Vd2. Output to the processing unit 7.

  The processing unit 7 includes an A / D conversion unit 7a, a CPU 7b, and a memory (not shown). In this case, the A / D conversion unit 7a has two systems of A / D conversion circuits, inputs the first detection signals Vd1 and Vd2, and converts them into digital data Di1 and Di2 in each A / D conversion circuit. Output. In this case, as described above, the detection signal Vc1 is a signal whose amplitude changes according to the amplitude of the real component of the alternating current Io. Therefore, the digital data Di1 for the first detection signal Vd1 generated by amplifying the detection signal Vc1 is data indicating the current value of the real component of the alternating current Io (hereinafter also referred to as “current data Di1”). . Further, as described above, the detection signal Vc2 is a signal whose amplitude changes according to the amplitude of the imaginary component of the alternating current Io. Therefore, the digital data Di2 for the second detection signal Vd2 generated by amplifying the detection signal Vc2 is data indicating the current value of the imaginary component of the alternating current Io (hereinafter also referred to as “current data Di2”). . The CPU 7b has a function of generating and outputting a reference clock CLK, and executes a resistance value calculation process, a phase angle calculation process, and a measurement value calculation process. For example, the output unit 8 includes a display unit such as a monitor device, and displays the result of the measurement value calculation process.

  Next, the measurement operation of the measurement values (pure resistance component Rr and reactance component Rx) of the measurement target circuit 9 by the measurement apparatus 1 will be described.

  In the measurement apparatus 1, the processing unit 7 first starts outputting the reference clock CLK. This reference clock CLK is output to the staircase wave generator 21a and the D-type FFs 4b and 5b of the signal generators 4 and 5, respectively. Thereby, in the voltage injection unit 3, the staircase wave generation unit 21a starts generating and outputting the triangular wave signal Vt synchronized with the reference clock CLK, and the LPF 21b converts the triangular wave signal Vt into a sine wave voltage (AC voltage) Va. . Next, the phase shift unit 22 starts generating the sine wave voltages Va1 and Va2 whose phases are orthogonal to each other (the phases are different by 90 °) based on the AC voltage Va. In this example, the phase of the sine wave voltage Va1 is advanced by 90 ° with respect to the phase of the sine wave voltage Va2.

  The power amplifying unit 23 performs a class D amplification operation, amplifies the input sine wave voltage Va1 to the sine wave voltage V1, and applies it to the injection coil 11b of the injection clamp 11. At this time, the feedback unit 24 detects the voltage V2 induced in the feedback coil 11c due to the application of the sine wave voltage Va1 to the injection coil 11b, and this voltage V2 is a predetermined voltage (a constant voltage). The amplification factor of the power amplifying unit 23 is controlled so as to be (voltage). Therefore, the power amplifying unit 23 generates a sine wave voltage V1 having a constant voltage value and applies it to the injection coil 11b. As a result, the inspection AC signal Vo (frequency f) is injected from the injection clamp 11 to the measurement target circuit 9, and the AC current Io having the frequency f is injected into the measurement target circuit 9 due to the injection of the inspection AC signal Vo. Flows.

  On the other hand, in the first signal generating unit 4, the comparator 4a compares the sine wave voltage Va1 with the reference voltage to start generating a rectangular wave signal whose polarity is inverted at the zero cross of the sine wave voltage Va1, and the D type The FF 4b starts processing to output the rectangular wave signal as the first signal S1 in synchronization with the reference clock CLK. Further, in the second signal generation unit 5, the comparator 5a compares the sine wave voltage Va2 with the reference voltage to start generating a rectangular wave signal whose polarity is inverted at the zero cross of the sine wave voltage Va2. The FF 4b starts processing to output the rectangular wave signal as the second signal S2 in synchronization with the reference clock CLK. Thereby, the supply of the first signal S1 and the second signal S2 reference signal Sr is started from the signal generation units 4 and 5 to the switching units 33 and 34 of the current detection unit 6.

  In this case, since the sine wave voltage Va1 is amplified to the sine wave voltage V1 in the power amplifying unit 23, the phase of the sine wave voltage V1 is the same. Therefore, in the first signal generation unit 4, the first signal S1 generated from the sine wave voltage Va1 is in phase with the sine wave voltage V1, as shown in FIG. On the other hand, in the second signal generator 5, the second signal S2 generated from the sine wave voltage Va2 whose phase is orthogonal to the sine wave voltage Va1 (in this example, the phase is delayed by 90 °) is shown in FIG. As shown, the phase is delayed by 90 ° with respect to the first signal S1 (that is, with respect to the sine wave voltage V1).

  In a state in which the inspection AC signal Vo having the frequency f is injected into the measurement target circuit 9, the current detection unit 6 performs a process of detecting the AC current Io and generating current data Di1 and Di2. Specifically, in the current detection unit 6, the detection clamp 12 detects the alternating current Io flowing through the measurement target circuit 9, outputs the detection current I1 from the detection coil 12b, and the IV conversion unit 31 This detection current I1 is converted into a current detection signal Vb1 and output. The inverting unit 32 receives the current detection signal Vb1, inverts its polarity (shifts the phase by 180 °), and outputs the inverted detection signal Vb2. In this case, the resistance R of the measurement target circuit 9 includes the pure resistance component Rr and the reactance component Rx as described above. Therefore, there is a phase difference θ between the sine wave voltage V1 applied from the power amplifier 23 to the injection clamp 11 and the alternating current Io flowing through the measurement target circuit 9 due to the sine wave voltage V1. As a result, between the sine wave voltage V1 and the detection current I1 generated due to the alternating current Io, and further, the current detection signal Vb1 generated from the detection current I1, as shown in FIG. A phase difference θ is generated.

  Next, the first switching unit 33 switches and outputs the current detection signal Vb1 and the inverted detection signal Vb2 in synchronization with the first signal S1 (by synchronously detecting the current detection signal Vb1 with the first signal S1). The detection signal Vc1 is output, and the second switching unit 34 switches the current detection signal Vb1 and the inverted detection signal Vb2 in synchronization with the second signal S2 and outputs it (the current detection signal Vb1 is output as the second signal S2). The detection signal Vc2 is output (see FIG. 3). In addition, the DC amplifying unit 35 inputs and amplifies the detection signals Vc1 and Vc2, and outputs them as first detection signals Vd1 and Vd2.

  Subsequently, the processing unit 7 (specifically, the A / D conversion unit 7a) receives the first detection signals Vd1 and Vd2 and converts them into current data Di1 and Di2 and outputs them. In this case, as described above, the current data Di1 is data indicating the current value of the real component of the alternating current Io, and the current data Di2 is data indicating the current value of the imaginary component of the alternating current Io.

  Subsequently, the processing unit 7 (specifically, the CPU 7b) executes a calculation process for calculating the measurement values (the pure resistance component Rr and the reactance component Rx of the resistor R) of the measurement target circuit 9. Specifically, in this calculation process, the processing unit 7 first calculates the absolute value of the resistance R of the measurement target circuit 9 (the absolute value | Z | of the impedance Z of the measurement target circuit 9). Execute.

  In this resistance value calculation process, the processing unit 7 first calculates a current value (current value of the real component) of the detection current I1 based on the current data Di1, and the calculated current value and the number of turns of the detection coil 12b ( N2) and the current value of the alternating current Io (the current value Ior of the real number component (hereinafter also simply referred to as “real number component Ior”)) is calculated. Further, the processing unit 7 calculates a current value (current value of an imaginary component) of the detection current I1 based on the current data Di2, and AC based on the calculated current value and the number of turns (N2) of the detection coil 12b. The current value of the current Io (current value Iox of the imaginary component (hereinafter also simply referred to as “imaginary component Iox”)) is calculated.

  Subsequently, the processing unit 7 calculates the absolute value of the alternating current Io based on the calculated real number component Ior and imaginary number component Iox. In this case, the processing unit 7 calculates the absolute value (| Io |) of the alternating current Io by squaring and adding the real number component Ior and the imaginary number component Iox, and calculating the square root of the added value.

  Next, the processing unit 7 calculates the voltage effective value of the AC signal Vx for inspection based on the voltage effective value of the AC voltage V1 (known as described above) and the number of turns (N1) of the injection coil 11b, and finally, The absolute value | Z | of the impedance of the circuit 9 to be measured is calculated by dividing the calculated voltage effective value of the AC signal Vx for inspection by the absolute value (| Io |) of the AC current Io.

  Subsequently, the processing unit 7 executes a phase angle calculation process. In this phase angle calculation process, the processing unit 7 based on the real number component Ior and the imaginary number component Iox calculated in the resistance value calculation process, the phase angle θ (= arctan (Iox / Ior) of the real number component Ior and the imaginary number component Iox. )) Is calculated. This phase angle θ is also a phase angle (phase difference) between the test AC signal Vo injected into the measurement target circuit 9 and the AC current Io flowing through the measurement target circuit 9 due to the test AC signal Vo. .

  Finally, the processing unit 7 executes a measurement value calculation process. In the measurement value calculation process, the processing unit 7 calculates the pure resistance component Rr of the resistance R of the measurement target circuit 9 by multiplying the calculated absolute value (| Z |) of the impedance of the measurement target circuit 9 by cos θ. Further, by multiplying the absolute value (| Z |) by sin θ, the reactance component Rx of the resistance R of the circuit to be measured 9 is calculated, and these are output to the output unit 8 as measured values (in this example, Display as an example). Thereby, the calculation processing of the measurement values (the pure resistance component Rr and the reactance component Rx of the resistor R) of the measurement target circuit 9 by the processing unit 7 is completed.

  Thus, according to this measuring apparatus 1, the current detection unit 6 uses the first signal S1 having the same phase as the sine wave voltage V1 as the current detection signal Vb1 output from the injection coil 11b of the injection clamp 11. By performing synchronous detection, the first detection signal Vd1 whose amplitude changes according to the amplitude of the real component Ior of the alternating current Io is output, and the current detection signal Vb1 is a second signal S2 whose phase is orthogonal to the first signal S1. Is used to output a second detection signal Vd2 whose amplitude changes according to the amplitude of the imaginary component Iox of the alternating current Io, and the processing unit 7 based on the detection signals Vd1 and Vd2 By executing the resistance value calculation process, the phase angle calculation process, and the measurement value calculation process, the pure resistance component Rr and the reactance component Rx of the measurement target circuit 9 can be separately calculated. .

  Further, in this measuring apparatus 1, the phase shift unit 22 of the voltage injection unit 3 is based on the sine wave voltage Va output from the original signal generation unit 21, and the two sine wave voltages Va 1 and sine waves whose phases are orthogonal to each other. While generating the voltage Va2, the power amplifier 23 amplifies the sine wave voltage Va1 to the sine wave voltage V1 and applies it to the injection coil 11b, and the first signal generator 4 has the same phase as the sine wave voltage V1. The first signal S1 is generated based on Va1, and the second signal generator 5 generates the second signal S2 based on the sine wave voltage Va2.

  Therefore, according to this measuring apparatus 1, the phase shift unit 22 is arranged on the basis of the sine wave voltage Va that is disposed inside the measuring apparatus 1 and is output from the original signal generating unit 21 that is not easily affected by the outside. Sinusoidal voltages Va1 and Va2 can be generated. For this reason, according to this measuring apparatus 1, the phase difference between the first signal S1 and the second signal S2 generated based on the both sine wave voltages Va1 and Va2 can be stably maintained at 90 °, so that the first switching is performed. The second switching unit 34 and the second switching unit 34 change the amplitude according to the first detection signal Vd1 whose amplitude changes according to the amplitude of the real component Ior of the alternating current Io and the amplitude of the imaginary component Iox of the alternating current Io. Since the detection signal Vd2 can be output with high accuracy by synchronous detection, the processing unit 7 can accurately calculate the pure resistance component Rr and the reactance component Rx of the measurement target circuit 9 based on the detection signals Vd1 and Vd2 with high accuracy. Can be calculated.

  Moreover, according to this measuring apparatus 1, the 1st signal generation part 4 and the 2nd signal generation part 5 employ | adopted the structure which shapes the 1st signal S1 and the 2nd signal S2 into a rectangular wave, and each outputs them, The current detection unit 6 uses the first switching unit 33 and the second switching unit 34 that selectively output one of the current detection signal Vb1 and the inverted detection signal Vb2, and uses the first detection signal based on the current detection signal Vb1. Since Vd1 and the second detection signal Vd2 can be detected by synchronous detection, for example, the first switching unit 33 and the second switching unit 34 can be configured using analog switches. As a result, the configuration of the current detection unit 6 is simplified. can do.

  In the measurement apparatus 1, as described above, the phase shift unit 22 is based on the sine wave voltage Va so that the phase difference between the first signal S1 and the second signal S2 is stably maintained at 90 °. The two sine wave voltages Va1 and Va2 having a phase difference of 90 ° are employed. However, as in the measuring apparatus 1A shown in FIG. A configuration including a phase shift unit 22A that generates and outputs different signals may be employed. Hereinafter, the measuring apparatus 1A will be described. In addition, since it is different from the measurement apparatus 1 only in having a phase shift unit 22A instead of the phase shift unit 22, and other components are the same as those of the measurement device 1, the same components as those of the measurement device 1 are described. The same reference numerals are assigned and duplicate descriptions are omitted.

  This measuring apparatus 1A includes a clamp sensor 2, a voltage injection unit 3A, a first signal generation unit 4, a second signal generation unit 5, a current detection unit 6, a processing unit 7, and an output unit 8. In this case, the voltage injection unit 3A is configured to directly output the sine wave voltage Va from the original signal generation unit 21 to the power amplification unit 23 as compared with the voltage injection unit 3 of the measurement apparatus 1, and the phase shift unit 22 Instead, a phase shift unit 22A is provided, and the phase shift unit 22A inputs a sine wave voltage V1 applied to the injection coil 11b from the power amplification unit 23 and a signal whose phase is different by 90 ° with reference to the sine wave voltage V1. Is generated and output to the second signal generator 5 as the sine wave voltage Va2, and the first signal generator 4 inputs the sine wave voltage V1 instead of the sine wave voltage Va1 to generate the first signal S1. The configuration is different.

  In this measurement apparatus 1A, as in the measurement apparatus 1, the current detection unit 6 uses the current detection signal Vb1 output from the injection coil 11b of the injection clamp 11 as the first signal S1 in phase with the sine wave voltage V1. Is used to output the first detection signal Vd1 whose amplitude changes according to the amplitude of the real component Ior of the alternating current Io, and at the same time, the current detection signal Vb1 has a phase orthogonal to the first signal S1. By performing synchronous detection using the two signals S2, the second detection signal Vd2 whose amplitude changes according to the amplitude of the imaginary component Iox of the alternating current Io is output, and the processing unit 7 outputs the detection signals Vd1 and Vd2 Based on this, by executing the resistance value calculation process, the phase angle calculation process, and the measurement value calculation process, the pure resistance component Rr and the reactance component Rx of the measurement target circuit 9 are separated and calculated. It can be.

  Further, in each of the measurement apparatuses 1 and 1A described above, a configuration in which the reversing unit 32 is provided in the current detection unit 6 is adopted, and the first switching unit 33 and the second switching unit 34 are configured so that the current detection signal Vb1 and the reversing unit 32 are provided. The inversion detection signal Vb2 (a signal whose polarity (phase) is inverted from that of the current detection signal Vb1) is switched and output based on the first signal S1 and the second signal S2 (that is, full-wave rectification is performed). Thus, by increasing the level of each detection signal Vc1, Vc2 that is the output of the synchronous detection, a preferable configuration that can further improve the accuracy of the synchronous detection is provided. However, like the current detection unit 6A shown in FIG. Instead of providing 32, a configuration in which a reference potential (ground potential) is input instead of the inversion detection signal Vb2 to the first switching unit 33 and the second switching unit 34 may be employed.

  In the current detection unit 6A employing the configuration of FIG. 5, as shown in FIGS. 5 and 6, the first switching unit 33 outputs the current detection signal Vb1 for a half cycle during one cycle of the first signal S1. The detection signal Vc1 is generated by (that is, half-wave rectification), and the second switching unit 34 similarly outputs the current detection signal Vb1 for a half cycle during one cycle of the second signal S2 (that is, half-wave). The detection signal Vc2 is generated. Therefore, although the levels of the detection signals Vc1 and Vc2 are reduced by half compared to the current detection unit 6 described above, the detection signal Vc1 is a signal whose amplitude changes according to the amplitude of the real component Ior of the alternating current Io. Since the detection signal Vc2 is a signal whose amplitude changes in accordance with the amplitude of the imaginary component Iox of the alternating current Io, the processing unit 7 is based on the detection signals Vd1 and Vd2 generated from the detection signals Vc1 and Vc2. By executing the resistance value calculation process, the phase angle calculation process, and the measurement value calculation process, the pure resistance component Rr and the reactance component Rx of the measurement target circuit 9 can be calculated separately.

  In the above configuration, since the synchronous detection circuit that generates the detection signals Vc1 and Vc2 by synchronous detection is simply configured using the first switching unit 33 and the second switching unit 34, the first signal generating unit 4 and The second signal generation unit 5 employs a configuration in which the first signal S1 and the second signal S2 that are rectangular waves are generated and output, but the detection signals Vc1 and Vc2 are also obtained by synchronous detection using a multiplier. Can be generated. In the configuration using this multiplier, the analog signals input to the first signal generation unit 4 and the second signal generation unit 5 (for example, the sine wave voltages Va1, Va2 in the measuring apparatus 1 employing the phase shift unit 22). In the measuring apparatus 1A employing the phase shift unit 22A, the sine wave voltage V1 and the sine wave voltage Va2) are directly output to the multipliers disposed in place of the first switching unit 33 and the second switching unit 34, respectively. It can be set as a structure, and arrangement | positioning of the 1st signal generation part 4 and the 2nd signal generation part 5 can be omitted. Moreover, although the configuration for measuring both the pure resistance component Rr and the reactance component Rx of the measurement target circuit 9 has been described above, a configuration for measuring only one of them can be employed. In the configuration in which both the pure resistance component Rr and the reactance component Rx of the measurement target circuit 9 are measured, the absolute value | Z | of the impedance of the measurement target circuit 9 is calculated based on the pure resistance component Rr and the reactance component Rx. Then, it can also be output to the output unit 8.

  Further, as a configuration for outputting the calculated absolute value | Z | of impedance, etc. (specifically, a configuration for displaying), the output unit 8 has a configuration (configuration as a display unit) shown in FIG. 7 or FIG. 8 as an example. Can be adopted. Hereinafter, the measuring apparatuses 1B and 1C having the output unit 8 having this configuration will be described. In addition, about the structure same as the structure of above-described measuring apparatus 1 and 1A, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  A measuring apparatus 1B having the output unit 8 having the configuration shown in FIG. 7 includes an operation unit 41 in addition to the configuration of the measuring apparatus 1, as indicated by a broken line in FIG. The operation unit 41 includes, for example, a touch panel, a keyboard, a mouse, and the like. The operation unit 41 generates a selection signal Sse for selecting display content to be displayed on the output unit 8 according to the operation content, and the processing unit 7 (Specifically, it outputs to CPU7b). When the selection signal Sse is input, the processing unit 7 causes the output unit 8 to display the display content specified by the selection signal Sse.

  The output unit 8 configured as a display unit is configured by using an LCD (Liquid Crystal Display) as an example, and as shown in FIG. 7, a numerical value display region 51, a first symbol display region 52, and a phase state display region 53. It has. In this case, the numerical value display area 51 is configured to be able to display a number with a predetermined number of digits (four digits as an example in the figure) together with a decimal symbol (dot) and a unit symbol (“Ω”). Yes. In the numerical display area 51, any one of the absolute value | Z | of impedance, the pure resistance component Rr, and the reactance component Rx is selected and displayed. In the first symbol display area 52, the symbol “| Z |” indicating the absolute value | Z | of the impedance, and the pure resistance component Rr are displayed as symbols indicating the display contents (meaning of numerical values) displayed in the numerical display area 51. Any one of the symbol “R” indicating the reactance component Rx and the symbol “x” indicating the reactance component Rx is displayed. In the phase state display area 53, either a coil symbol or a capacitor symbol is selected as a symbol indicating the phase state of the reactance component Rx with respect to the pure resistance component Rr (specifically, the phase angle state). Displayed.

  In this measurement apparatus 1B, by operating the operation unit 41, for example, the operation unit 41 generates a selection signal Sse indicating that the impedance absolute value | Z | is selected as display content, and outputs the selection signal Sse to the processing unit 7. When 7 receives this selection signal Sse, the processing unit 7 displays the calculated absolute value | Z | of the impedance as a measurement value in the numerical display area 51 of the output unit 8 together with the unit symbol (“Ω”). In addition, the processing unit 7 causes the first symbol display area 52 to display only the symbol “| Z |” corresponding to the absolute value | Z | of the impedance displayed in the numerical value display area 51.

  In addition, by operating the operation unit 41, for example, the operation unit 41 generates a selection signal Sse indicating that the pure resistance component Rr is selected as display content, and outputs the selection signal Sse to the processing unit 7. The processing unit 7 outputs the selection signal Sse. When input, the processing unit 7 displays the calculated pure resistance component Rr as a measured value in the numerical display area 51 of the output unit 8 together with the unit symbol (“Ω”). Further, the processing unit 7 displays only the symbol “R” corresponding to the pure resistance component Rr displayed in the numerical value display area 51 in the first symbol display area 52.

  In addition, by operating the operation unit 41, for example, the operation unit 41 generates a selection signal Sse indicating that the reactance component Rx is selected as display content, and outputs the selection signal Sse to the processing unit 7. The processing unit 7 inputs the selection signal Sse. In this case, the processing unit 7 displays the calculated reactance component Rx as a measured value in the numerical display area 51 of the output unit 8 together with the unit symbol (“Ω”). In addition, the processing unit 7 displays only the symbol “x” corresponding to the reactance component Rx displayed in the numerical value display area 51 in the first symbol display area 52.

  Further, when the pure resistance component Rr of the resistance R of the measurement target circuit 9 is small, the reactance component Rx of the measurement target circuit 9 becomes relatively large (dominates), and as a result, a measurement error with respect to the pure resistance component Rr. Becomes larger. For this reason, in the measurement apparatus 1B, the processing unit 7 determines that the reactance component Rx is dominant when the calculated phase angle θ is outside the pre-defined angle range. Either one is displayed in the phase state display area 53. In this example, as an example of an angle range with respect to the phase angle θ, a range of + 45 ° or less and −45 ° or more is defined. When the phase angle θ exceeds + 45 °, the processing unit 7 is out of the angle range. The symbol of the coil indicating that the reactance component Rx of the measurement target circuit 9 that is dominant is an inductive reactance component is displayed in the phase state display area 53. On the other hand, when the phase angle θ is less than −45 ° and out of the angle range, the processing unit 7 is a capacitor that indicates that the reactance component Rx of the measurement target circuit 9 that is dominant is a capacitive reactance component. The symbol is displayed in the phase state display area 53.

  As described above, according to the measurement apparatus 1B, the user operates the operation unit 41 to obtain a desired measurement value (parameter) from the absolute value | Z | of the impedance, the pure resistance component Rr, and the reactance component Rx. It can be confirmed by selecting and displaying it on the output unit 8. Also, according to this measuring apparatus 1B, when the calculated phase angle θ is outside the pre-defined angle range, the reactance component Rx of the measurement target circuit 9 is relatively increased (dominated) in the output unit 8. Since a symbol (coil symbol or capacitor symbol) is displayed, the error of the pure resistance component Rr displayed on the output unit 8 is large for the user. That is, it is possible to notify that the accuracy is lowered. As a method for determining whether or not the phase angle θ is outside the angle range, a method for comparing the absolute value of the phase angle θ with the angle range may be employed. In this case, in the above example, the angle range is defined as + 45 ° or less and 0 ° or more.

  Next, the measuring apparatus 1C having the output unit 8 having the configuration shown in FIG. 8 will be described. In addition, about the structure same as above-described measuring apparatus 1B, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  The output unit 8 configured as a display unit is configured by using an LCD (Liquid Crystal Display) as an example, and as illustrated in FIG. 8, a numerical value display region 51 as a main numerical value display region, and a first symbol display region 52. A phase state display area 53, a sub-value display area 54, a unit display area 55, and a second symbol display area 56. In this case, the numerical display area 51 is configured such that the display area thereof is larger than the display area of the sub-numerical value display area 54, so that a larger number can be displayed. Similarly to the measuring apparatus 1B, in the numerical value display area 51, any one of the absolute value | Z | of the impedance, the pure resistance component Rr, and the reactance component Rx is selected and displayed, and the first symbol is displayed. In the area 52, any one of a symbol “| Z |” indicating the absolute value | Z | of the impedance, a symbol “R” indicating the pure resistance component Rr, and a symbol “x” indicating the reactance component Rx is displayed. In the phase state display area 53, either the coil symbol or the capacitor symbol is selected and displayed.

  On the other hand, the sub-numerical value display area 54 is configured to be able to display a number having a predetermined number of digits (four digits as an example in the figure) together with a symbol (dot) for a decimal point. In the sub-value display area 54, any one of an absolute value | Z | of impedance, a pure resistance component Rr, a reactance component Rx, an inductance L, a capacitance C, and a phase angle θ is selected and displayed. The unit display area 55 includes an impedance absolute value | Z |, a symbol “Ω” indicating a unit of the pure resistance component Rr and a reactance component Rx, a symbol “mH” indicating a unit of the inductance L, and a terminal of the capacitance C. Any one of a symbol “μF” and a symbol “°” indicating a unit of the phase angle θ is displayed. Similarly to the first symbol display region 52, the second symbol display region 56 includes a symbol “| Z |” indicating the absolute value | Z | of the impedance, a symbol “R” indicating the pure resistance component Rr, and a reactance component Rx. Any one of the indicated symbols “x” is displayed.

  In this measuring apparatus 1 </ b> C, by operating the operation unit 41, the operation unit 41 selects the display content of the numerical value display area 51 and the display content of the sub numerical value display area 54 for the processing unit 7. A signal Sse is generated and output. In this example, as an example, the operation unit 41 causes the numeric display area 51 and the sub-numerical value display area 54 to display any one set (two parameters) of the combinations illustrated in FIG. A selection signal Sse is generated and output. In the figure, symbol Z indicates the absolute value | Z | of the impedance, symbol R indicates the pure resistance component Rr, symbol x indicates the reactance component Rx, symbol L indicates the inductance L, and symbol C indicates the capacitance. C denotes the symbol θ, which indicates the phase angle θ.

  When the selection signal Sse is input from the operation unit 41, the processing unit 7 according to the display content of the numerical display area 51 indicated by the selection signal Sse, in the same manner as the measurement apparatus 1B described above, the absolute value of impedance | One of Z |, pure resistance component Rr, and reactance component Rx is displayed in numerical display area 51, and a symbol corresponding to the display content (any one of symbols | Z |, R, x) Is displayed in the first symbol display area 52. Further, the processing unit 7 determines whether or not to display each symbol of the coil and the capacitor in the phase state display area 53 according to the relationship between the value of the phase angle θ and the predetermined angle range, and displays it. In this case, the type of the symbol is determined and the symbol is displayed in the phase state display area 53.

  Further, the processing unit 7 determines the absolute value of the impedance | Z |, the pure resistance component Rr, the reactance component Rx, the inductance L, the capacitance C, and the phase angle in accordance with the display contents of the sub-value display area 54 indicated by the selection signal Sse. The sub-value display area 54 is shifted to either a display state in which any one of θ is displayed or a non-display state in which no numerical value is displayed.

  Specifically, when the display content of the sub-value display area 54 indicated by the selection signal Sse is the impedance absolute value | Z |, the processing unit 7 displays the calculated impedance absolute value | Z | 54. Further, the processing unit 7 displays the symbol “| Z |” indicating the absolute value | Z | of the impedance in the second symbol display area 56 and also displays the symbol “Ω” indicating the unit of the absolute value | Z | It is displayed in the unit display area 55.

  The processing unit 7 displays the calculated pure resistance component Rr in the sub-value display area 54 when the display content of the sub-value display area 54 indicated by the selection signal Sse is the pure resistance component Rr. Further, the processing unit 7 displays the symbol “R” indicating the pure resistance component Rr in the second symbol display area 56 and displays the symbol “Ω” indicating the unit of the pure resistance component Rr in the unit display area 55. Further, when the display content of the sub-value display area 54 indicated by the selection signal Sse is the reactance component Rx, the processing unit 7 displays the calculated reactance component Rx in the sub-value display area 54. Further, the processing unit 7 displays the symbol “x” indicating the reactance component Rx in the second symbol display area 56 and displays the symbol “Ω” indicating the unit of the reactance component Rx in the unit display area 55.

  Further, when the display content of the sub-value display area 54 indicated by the selection signal Sse is an inductance L or a capacitance C, the processing unit 7 is represented by a reactance component Rx based on the calculated polarity of the phase angle θ. Is an inductive reactance component or a capacitive reactance component, and if it is an inductive reactance component, the inductance L is calculated based on the reactance component Rx and the frequency f of the sinusoidal voltage Va. To do. On the other hand, in the case of the capacitive reactance component, the capacitance C is calculated based on the reactance component Rx and the frequency f of the sine wave voltage Va. Next, the processing unit 7 displays the calculated inductance L or capacitance C in the sub-value display area 54. Further, the processing unit causes the unit display area 55 to display a symbol (symbol “mH” or “μF”) indicating a unit corresponding to the display content of the sub-value display area 54. In this case, the processing unit 7 shifts the second symbol display area 56 to a state where no symbol is displayed.

  As described above, according to the measurement apparatus 1C, a desired measurement value is selected from the absolute value | Z | of the impedance, the pure resistance component Rr, and the reactance component Rx and displayed in the numerical display area 51 of the output unit 8. In addition to the effect of the measuring apparatus 1B that can be confirmed, any one parameter (pure resistance component Rr, reactance component Rx, and absolute value of impedance | Z | of those other than those displayed in the main numerical value display area 51 of Z |, any one parameter of inductance L, capacitance C, and phase angle θ) are also displayed in the sub numerical value display area 54. Can be confirmed. That is, according to this measuring apparatus 1C, two desired parameters are selected from the impedance absolute value | Z |, the pure resistance component Rr, and the reactance component Rx, and the impedance absolute value | Z | Two desired parameters can be selected from the resistance component Rr, the reactance component Rx, the inductance L, the capacitance C, and the phase angle θ, displayed on the output unit 8, and simultaneously confirmed.

  In the measuring apparatus 1C, parameters other than the absolute value | Z | of the impedance, the pure resistance component Rr, and the reactance component Rx, such as the inductance L and the capacitance C, are calculated and selectively displayed in the sub-value display area 54. In the configuration for calculating only the absolute value | Z |, the pure resistance component Rr, and the reactance component Rx, the configuration having the numerical value display area 51 and the sub numerical value display area 54 is adopted. A configuration is adopted in which parameters other than the parameters displayed in the numerical display area 51 among the absolute value | Z | of the impedance, the pure resistance component Rr, and the reactance component Rx are selectively displayed in the sub numerical display area 54. You can also. The output unit 8 of the measuring apparatus 1C employs a configuration in which the numerical value display area 51 and the sub numerical value display area 54 are arranged in one LCD. However, the numerical value display area 51 and the sub numerical value display area 54 are individually provided. It can also be composed of an LCD or a 7-segment display.

  Further, in each of the measuring apparatuses 1B and 1C described above, the output unit 8 has the phase state display region 53, and the phase state display region 53 displays either the coil symbol or the capacitor symbol. Although employed, a configuration without the phase state display area 53 may be employed.

  Further, each of the measuring devices 1B and 1C described above is configured based on the measuring device 1 shown in FIG. 1, but based on the measuring device 1A shown in FIG. 4, the operation unit 41 is indicated by a broken line. Of course, the processing unit 7 and the output unit 8 may be configured in the same manner as the measuring apparatuses 1B and 1C.

  Also, the unit display area 55 of the output unit 8 shown in FIG. 8 (the symbol “Ω” indicating the unit of the absolute value of impedance | Z |, the pure resistance component Rr and the reactance component Rx, and the symbol “mH” indicating the unit of the inductance L). ”, A symbol“ μF ”indicating a terminal of the capacitance C, and a symbol“ ° ”indicating a unit of the phase angle θ are displayed as numerical values of the output unit 8 illustrated in FIG. As the output unit 8 having the configuration shown in FIG. 10 by disposing it with respect to the display area 51, the absolute value of impedance | Z |, the pure resistance component Rr, the reactance component Rx, the inductance L, the capacitance C, and the phase angle θ. Any one of them may be displayed in the numerical value display area 51 and a symbol indicating a unit corresponding thereto may be displayed in the unit display area 55.

  Also, the unit display area 55 of the output unit 8 shown in FIG. 8 (the symbol “Ω” indicating the unit of the absolute value of impedance | Z |, the pure resistance component Rr and the reactance component Rx, and the symbol “mH” indicating the unit of the inductance L). , A symbol “μF” indicating the terminal of the capacitance C, and a symbol “°” indicating the unit of the phase angle θ are displayed on the numerical display region 51 of FIG. 11 is added to the combination shown in FIG. 9 as the output unit 8 having the configuration shown in FIG. 11, and any one of these combinations (two parameters) is added. Each of the numerical display area 51 and the sub numerical value display area 54 may be configured to display a symbol indicating a corresponding unit while being displayed in each unit display area 55.

  Further, in each of the measuring devices 1, 1A, 1B, and 1C described above, the first signal S1 and the first signal S1 are synchronized with the fundamental wave of the sine wave voltage Va1 in the same cycle as the fundamental wave of the sine wave voltage Va1. On the other hand, as a configuration for generating the second signal S2 whose phase is shifted by 90 °, a configuration using the first signal generation unit 4, the second signal generation unit 5 and the phase shift unit 22 (22A) is adopted. The phase shift unit 22 (22A) has two types of sine wave voltages Va1 and Va2 (sine wave voltages) in which the phase of the alternating voltage (pseudo sine wave voltage) Va generated by the original signal generation unit 21 is shifted by 90 °. V1, Va2), the first signal generator 4 generates a first signal S1 synchronized with the reference clock CLK based on one sine wave voltage Va1 (sine wave voltage V1), and a second signal generator 5 is the other sine wave voltage Va2. Is configured to generate the second signal S2 synchronized with the reference clock CLK, but the original signal generation unit 21, the first signal generation unit 4, the second signal generation unit 5 and the phase shift unit 22 (22A) Using a digital circuit using a CPU, FPGA (Field Programmable Gate Array), or CPLD (Complex Programmable Logic Device), a filter that converts the triangular wave signal Vt into an alternating voltage (pseudo sine wave voltage) Va and outputs it. It is also possible to adopt a configuration in which the other constituent elements are excluded as a single digital circuit and used as a general signal generation unit that generates the AC voltage Va, the first signal S1, and the second signal S2.

  As an example, an example in which the overall signal generation unit 61 is configured using a digital circuit using a CPU will be described with reference to FIGS.

  First, the configuration of the overall signal generation unit 61 will be described. The overall signal generation unit 61 includes a signal generation circuit 62 and a BPF 63 as shown in FIG. The signal generation circuit 62 includes a CPU 62a, a memory 62b, and a D / A conversion circuit 62c. In this case, the data table Dst for signal generation shown in FIG. 14 is stored in advance in the memory 62b together with the operation program of the CPU 62a. The data table Dst includes digital data (in this example, 2-bit digital data) DA1 and DA0 for generating the triangular wave signal Vt, digital data CLK0 for generating the first signal S1, and the second signal. Digital data CLK90 for generating S2 is stored in groups of 1 bit, and 12 sets of addresses 1 to 12 are stored.

  Next, the operation of the overall signal generation unit 61 will be described. In the overall signal generation unit 61, the CPU 62a operates according to the operation program, and from the data table Dst stored in the memory 62b, the digital data DA1, DA0, CLK0, and CLK90 stored in the addresses 1 to 12 are obtained. As shown in FIG. 15, the operation of sequentially reading out at the cycle Tc in the order of the addresses 1, 2, 3,... Further, the CPU 62a outputs the digital data DA1 and DA0 of the read digital data of each address to the D / A conversion circuit 62c with the digital data DA1 as the upper bits and the digital data DA0 as the lower bits. CLK0 is output to one of its own output ports, and digital data CLK90 is output to the other one of its own output ports. The D / A conversion circuit 62c sequentially converts the digital data DA1 and DA0 output from the CPU 62a into an analog signal Vt and outputs the analog signal Vt. Further, the BPF 63 receives the triangular wave signal Vt and mainly passes the fundamental frequency component (frequency f) and attenuates other frequency components (by selectively passing the fundamental frequency component). An alternating voltage (pseudo sine wave voltage) Va is converted and output.

  Thereby, as shown in FIG. 15, the D / A conversion circuit 62c generates and outputs an analog signal whose value changes with the period Tc in accordance with the digital data DA1 and DA0 as a triangular wave signal Vt. As shown in FIG. 15, the first signal S1 and the second signal S2 are output from the output port. In this case, the digital data CLK0 stored in the data table Dst is changed from the first “2” to the next “2” in the period in which the numerical values indicated by the digital data DA1, DA0 are “2” and “2”. In synchronization with the transition timing, it changes from “0” to “1”, or conversely changes from “1” to “0”. For this reason, the first signal S1 generated based on the digital data CLK0 is in phase with the signal whose amplitude changes in synchronization with the zero cross point of the AC voltage Va output from the BPF 63, that is, the AC voltage Va. Signal. That is, the CPU 62a functions as an original signal generation unit together with the D / A conversion circuit 62c and the BPF 63, and the CPU 62a functions as a first signal generation unit.

  On the other hand, the digital data CLK90 stored in the data table Dst is the second “3” in the period in which the numerical values indicated by the digital data DA1, DA0 are “3”, “3”, “3”, “3”. “0” is changed to “1” in synchronization with the timing of shifting from “3” to the third “3”, and the numerical values indicated by the digital data DA1, DA0 are “1”, “1”, “1”, “ It changes from “1” to “0” in synchronization with the timing of transition from the second “1” to the third “1” in a period consecutive to “1”. For this reason, the second signal S <b> 2 generated based on the digital data CLK <b> 90 is a signal whose phase is shifted by 90 ° with respect to the AC voltage Va output from the BPF 63. That is, the CPU 62a also functions as a second signal generation unit.

  By adopting a configuration that uses a digital circuit such as the integrated signal generation unit 61 and generates the triangular wave signal Vt, the first signal S1, and the second signal S2 based on the digital data DA1, DA0, CLK0, and CLK90. The first signal S1 having a phase difference of zero (phase matched) and the second signal S2 having a phase shifted by 90 ° with respect to the triangular wave signal Vt and the AC voltage Va generated from the triangular wave signal Vt. , Stable and easy to produce. Further, since the phase shift unit 22 (22A) can be omitted, the phase adjustment work for the phase shift unit 22 (22A) can be omitted, and the work process can be simplified.

  As an example, the configuration for generating the triangular wave signal Vt from the 2-bit digital data DA1 and DA0 has been described above, but the configuration for generating the triangular wave signal Vt as a signal whose waveform is closer to a sine wave by increasing the number of bits. Of course, it may be adopted. Further, it is possible to adopt a configuration in which the CPU 7b constituting the processing unit 7 also serves as the CPU 62a, and the memory constituting the processing unit 7 also serves as the memory 62b.

DESCRIPTION OF SYMBOLS 1 Measuring apparatus 3 Voltage injection part 4 1st signal generation part 5 2nd signal generation part 6 Current detection part 7 Processing part 8 Output part (display part)
DESCRIPTION OF SYMBOLS 9 Measurement object circuit 11b Injection coil 12b Detection coil 33 1st switching part 34 2nd switching part 41 Operation part Io AC current Rr Pure resistance component Rx Reactance component V1 Sine wave voltage Vb1 Current detection signal Vb2 Inversion detection signal Vd1 1st detection signal Vd2 Second detection signal Vo AC signal for inspection

Claims (6)

A voltage injection unit that injects an inspection AC signal into the measurement target circuit by applying an AC voltage to the injection coil, and an AC current that flows through the measurement target circuit due to the injection of the inspection AC signal is detected by the detection coil And a current detection unit that outputs a detection signal whose amplitude changes according to the amplitude of the alternating current based on the current detection signal output from the detection coil, and a current value of the alternating current based on the detection signal. A processing unit that calculates and calculates at least one of a pure resistance component and a reactance component of the measurement target circuit as a measured value based on the calculated current value of the alternating current and the voltage value of the injected inspection AC signal; A measuring device comprising:
A first signal generation unit that generates and outputs a first signal that has the same period as the fundamental wave of the alternating voltage and is synchronized with the fundamental wave of the alternating voltage;
A second signal generation unit that generates and outputs a second signal whose phase is orthogonal to the first signal;
The current detection unit outputs, as the detection signal, a first detection signal whose amplitude changes according to the amplitude of the real component of the alternating current by synchronously detecting the current detection signal using the first signal. , By synchronously detecting the current detection signal using the second signal, a second detection signal whose amplitude changes according to the amplitude of the imaginary component of the alternating current is output as the detection signal,
The processing unit calculates an absolute value of the current value of the alternating current based on the first detection signal and the second detection signal, and based on the calculated absolute value and a voltage value of the inspection AC signal. A resistance value calculation process for calculating an absolute value of the impedance of the circuit to be measured, and a phase angle between the AC current and the AC signal for inspection based on the first detection signal and the second detection signal In a measurement device that performs a phase angle calculation process, and a measurement value calculation process that calculates the measurement value based on the calculated absolute value of the impedance and the phase angle ,
It has an operation unit and display unit,
The processing unit is respectively calculated based on the pure resistance component, the reactance component, the absolute value of the impedance, the reactance component, and the frequency of the AC voltage according to the operation content of the operation unit. And one of the phase angles calculated based on the first detection signal and the second detection signal is selected and displayed on the display unit, and the phase angle is defined in advance. A measuring device that displays a symbol indicating that on the display unit when the angle is out of the range. A voltage injection unit that injects an inspection AC signal into the measurement target circuit by applying an AC voltage to the injection coil, and an AC current that flows through the measurement target circuit due to the injection of the inspection AC signal is detected by the detection coil And a current detection unit that outputs a detection signal whose amplitude changes according to the amplitude of the alternating current based on the current detection signal output from the detection coil, and a current value of the alternating current based on the detection signal. A processing unit that calculates and calculates at least one of a pure resistance component and a reactance component of the measurement target circuit as a measured value based on the calculated current value of the alternating current and the voltage value of the injected inspection AC signal; A measuring device comprising:
A first signal generation unit that generates and outputs a first signal that has the same period as the fundamental wave of the alternating voltage and is synchronized with the fundamental wave of the alternating voltage;
A second signal generation unit that generates and outputs a second signal whose phase is orthogonal to the first signal;
The current detection unit outputs, as the detection signal, a first detection signal whose amplitude changes according to the amplitude of the real component of the alternating current by synchronously detecting the current detection signal using the first signal. , By synchronously detecting the current detection signal using the second signal, a second detection signal whose amplitude changes according to the amplitude of the imaginary component of the alternating current is output as the detection signal,
The processing unit calculates an absolute value of the current value of the alternating current based on the first detection signal and the second detection signal, and based on the calculated absolute value and a voltage value of the inspection AC signal. A resistance value calculation process for calculating an absolute value of the impedance of the circuit to be measured, and a phase angle between the AC current and the AC signal for inspection based on the first detection signal and the second detection signal In a measurement device that performs a phase angle calculation process, and a measurement value calculation process that calculates the measurement value based on the calculated absolute value of the impedance and the phase angle,
An operation unit, and a display unit having a main numerical value display region and a sub numerical value display region;
The processing unit is respectively calculated based on the pure resistance component, the reactance component, the absolute value of the impedance, the reactance component, and the frequency of the AC voltage according to the operation content of the operation unit. And selecting two of the phase angle calculated based on the inductance and capacitance of the first detection signal and the second detection signal and displaying them in the main numerical value display area and the sub numerical value display area, A measuring apparatus for displaying a symbol indicating that on the display unit when the phase angle is outside a predetermined angle range. A voltage injection unit that injects an inspection AC signal into the measurement target circuit by applying an AC voltage to the injection coil, and an AC current that flows through the measurement target circuit due to the injection of the inspection AC signal is detected by the detection coil And a current detection unit that outputs a detection signal whose amplitude changes according to the amplitude of the alternating current based on the current detection signal output from the detection coil, and a current value of the alternating current based on the detection signal. A processing unit that calculates and calculates at least one of a pure resistance component and a reactance component of the measurement target circuit as a measured value based on the calculated current value of the alternating current and the voltage value of the injected inspection AC signal; A measuring device comprising:
A first signal generation unit that generates and outputs a first signal that has the same period as the fundamental wave of the alternating voltage and is synchronized with the fundamental wave of the alternating voltage;
A second signal generation unit that generates and outputs a second signal whose phase is orthogonal to the first signal;
The current detection unit outputs, as the detection signal, a first detection signal whose amplitude changes according to the amplitude of the real component of the alternating current by synchronously detecting the current detection signal using the first signal. , By synchronously detecting the current detection signal using the second signal, a second detection signal whose amplitude changes according to the amplitude of the imaginary component of the alternating current is output as the detection signal,
The processing unit calculates an absolute value of the current value of the alternating current based on the first detection signal and the second detection signal, and based on the calculated absolute value and a voltage value of the inspection AC signal. A resistance value calculation process for calculating an absolute value of the impedance of the circuit to be measured, and a phase angle between the AC current and the AC signal for inspection based on the first detection signal and the second detection signal In a measurement device that performs a phase angle calculation process, and a measurement value calculation process that calculates the measurement value based on the calculated absolute value of the impedance and the phase angle,
An operation unit, and a display unit having a main numerical value display region and a sub numerical value display region;
The processing unit calculates at least one of an inductance and a capacitance of the measurement target circuit based on the reactance component and the frequency of the AC voltage, and the pure resistance component and the reactance component according to an operation content on the operation unit. And one of the absolute values of the impedance is selected and displayed in the main value display area, and the main value display area of the pure resistance component, the reactance component, and the absolute value of the impedance is selected. One other than the one displayed, one selected from the calculated inductance, capacitance, and phase angle is selected and displayed in the sub-value display area, and the phase angle is outside a predetermined angle range. Sometimes, a measuring device that displays a symbol indicating that on the display unit. The voltage injection unit includes an original signal generation unit that generates an AC original signal, and a phase shift unit that generates two AC signals whose phases are orthogonal to each other based on the AC original signal. One of the AC signals is applied to the injection coil as the AC voltage,
The first signal generation unit generates the first signal based on the one of the two signals generated in the voltage injection unit,
The second signal generator, the measuring device according to any one of claims 1-3 for generating a second signal based on the other signal of said two signals generated in the voltage injection unit. The first signal generation unit shapes and outputs the first signal into a rectangular wave,
The second signal generation unit shapes the second signal into a rectangular wave and outputs it,
The current detection unit inverts the current detection signal and outputs it as an inverted detection signal, and inputs the current detection signal and the inverted detection signal and selectively outputs one of the first and first 2 switching section, and the first switching section synchronously detects the current detection signal by switching and outputting the current detection signal and the inverted detection signal based on the first signal, and the second switching section. parts are measurement apparatus according to any one of 4 claims 1 to synchronous detection of the current detection signal by switching and outputting the current detection signal and the inversion detection signal based on the second signal. The voltage injection unit includes a memory, a CPU, a D / A conversion circuit, a filter, and a power amplification unit,
Digital data for alternating current original signal, digital data for the first signal whose phase matches the alternating current original signal, and digital data for the second signal whose phase is shifted by 90 ° with respect to the alternating current original signal Is stored in advance in the memory,
The CPU repeatedly executes an operation of sequentially reading the digital data for the AC original signal, the first signal, and the second signal from the data table in a predetermined cycle, and the AC original signal The digital data for the first signal and the second signal are output to the D / A conversion circuit, and the digital data for the first signal and the second signal are output from the corresponding output ports. Generate a signal,
The D / A conversion circuit converts the input digital data for the AC original signal into a triangular wave signal, and outputs it.
The filter converts the triangular wave signal into the AC original signal and outputs the alternating current signal,
Said power amplifier unit, the measuring device according to any one of claims 1-3, wherein the AC voltage is generated and applied to the injection coil based on the alternating current source signal.

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