Power meter, current correction method, and power opening / closing module

Abstract

To provide a power meter with a small processing load for power calculation.SOLUTION: A power meter for measuring AC power supplied through an electric path connecting an AC power supply and a load comprises: a current measurement section for measuring an AC current flowing through the electric path; a voltage measurement section for measuring an AC voltage applied to the electric path; a current correction value calculation section for calculating a correction value for correcting a current measurement value; a current computation section for correcting the current measurement value on the basis of the correction value and calculating an AC current value flowing through the electric path; a voltage computation section for calculating an AC voltage value applied to the electric path on the basis of a voltage measurement value; and a power calculation section for calculating an AC power value supplied through the electric path on the basis of the AC voltage value and the AC current value. The current correction value calculation section estimates an effective value of the current measurement value by averaging peak values of waveforms of the current measurement value, and calculates the correction value by comparing the effective value of the estimated current measurement value with the effective value of a reference value of the AC current flowing through the electric path.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a power meter, a current correction method, and a power switching module. [Background technology]

[0002] Recently, the specified measurement system has permitted the use of measuring instruments that do not undergo inspection under the Weights and Measures Act as special measuring instruments. Under this specified measurement system, businesses that have submitted a notification in advance can measure using measuring instruments with appropriate accuracy. In this case, the accuracy is assumed to be a power factor of 1, and it is sufficient to guarantee the accuracy at a specified power consumption, making the conventional high-precision power measurement function unnecessary.

[0003] Conventionally, when measuring the amount of electric power, the voltage of the distribution line connected to the AC power system and the current flowing through the distribution line are converted into analog to digital, and the amount of electric power is calculated using software installed in a microcomputer. Although it is sufficient to guarantee a measurement accuracy of about ±2% within a voltage range of ±10% of the rated voltage for the input voltage, the input current has a wide range from 0.5A to the rated value (e.g., 16A), and the accuracy is significantly affected by the variations in the current detection circuit and current detection sensor (e.g., Hall element), so a method of performing slope correction (gain correction) of the detected value is used (see, for example, Patent Document 1).

[0004] However, when making corrections while still using the original AC power supply, it is necessary to use the effective current value to convert the AC current to DC, but due to reasons such as the need to perform square root calculations, it was necessary to use a high-performance microcomputer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2023-28478 A Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in consideration of the above problems, and has an object to provide a power meter with a small processing load for power calculation. [Means for solving the problem]

[0007] To solve the above problems, the present invention provides: A power meter that is provided in an electric circuit that connects an AC power source and a load, and measures AC power supplied from the AC power source to the load through the electric circuit, A current measuring unit that measures an AC current flowing through the electric circuit; A voltage measuring unit that measures an AC voltage applied to the electric circuit; a current correction value calculation unit that calculates a correction value for correcting the current measurement value output from the current measurement unit; a current calculation unit that corrects the current measurement value output from the current measurement unit based on the correction value and calculates an AC current value flowing through the electric circuit; a voltage calculation unit that calculates an AC voltage value applied to the electric circuit based on the voltage measurement value output from the voltage measurement unit; a power calculation unit that calculates an AC power value supplied through the electric path based on the AC voltage value calculated by the voltage calculation unit and the AC current value calculated by the current calculation unit; Equipped with The current correction value calculation unit is characterized in that it averages peak values ​​of the waveform of the current measurement value to estimate an effective value of the current measurement value, and calculates the correction value by comparing the estimated effective value of the current measurement value with the effective value of a reference value of the AC current flowing through the electric circuit.

[0008] According to this method, the peak values ​​of the waveform of the measured current value are averaged to estimate the effective value of the measured current value, so the processing load for estimating the effective value is smaller than when a calculation with a large processing load such as square root calculation is performed, and therefore a wattmeter with a low processing load for power calculation can be provided.

[0009] In the present invention, The current measurement value may be a voltage value indicative of the alternating current.

[0010] According to this, by treating the current measurement value as a voltage value indicating an AC current, data with high resolution can be processed, so that highly accurate power calculation is possible.

[0011] In the present invention, The reference value may be a measurement value of the AC current flowing through the electrical path that is more accurate than the current measurement unit.

[0012] According to this, the correction value for the measured current value can be calculated with high accuracy based on the highly accurate reference value from the current measuring unit, so that the power can be calculated with high accuracy.

[0013] In the present invention, The reference value may be a command value of the AC current flowing through the electrical path by the load.

[0014] According to this, since the correction value can be calculated with high accuracy based on a preset reference value as a command value of the AC current flowing through the electric circuit by the load, it is possible to perform highly accurate power calculation. Also, since it is not necessary to pass the reference value to the current correction value calculation unit from the outside, unnecessary communication means can be omitted.

[0015] The present invention relates to 1. A current correction method for correcting a measured value of an AC current flowing through an electric circuit connecting an AC power source and a load, the measured value being used for calculating AC power supplied through the electric circuit, the method comprising the steps of: measuring said alternating current to obtain said measurement value; averaging the peak values ​​of the waveform of the measurement to estimate an effective value of the measurement; comparing the estimated effective value with an effective value of the reference value of the AC current to calculate a correction value for correcting the measured value; The present invention is characterized by comprising:

[0016] According to this method, the peak values ​​of the waveform of the measured AC current are averaged to estimate the effective value of the measured value, so the processing load when estimating the effective value is smaller than when performing a calculation with a large processing load such as square root calculation, and therefore the processing load when calculating AC power can be reduced.

[0017] In the present invention, The measurement value may be a voltage value indicative of the AC current.

[0018] According to this, by converting the measured value of the AC current into a voltage value indicating the AC current, data with high resolution can be processed, so that highly accurate power calculation is possible.

[0019] In the present invention, The reference value may be a measurement of the AC current flowing through the electrical path that is more accurate than the measurement value.

[0020] According to this, the correction value for the measured current value can be calculated with high accuracy based on the highly accurate reference value from the current measuring unit, so that the power can be calculated with high accuracy.

[0021] In the present invention, The reference value may be a command value of the AC current flowing through the electrical path by the load.

[0022] According to this, since the correction value can be calculated with high accuracy based on a preset reference value as a command value of the AC current flowing through the electric circuit by the load, it is possible to perform highly accurate power calculation. Also, since it is not necessary to pass the reference value to the current correction value calculation unit from the outside, unnecessary communication means can be omitted.

[0023] The present invention also provides a method for producing a semiconductor device comprising the steps of: An electric power switching module that switches an electric circuit connecting an AC power source and an electric vehicle, A power switching unit that switches the electric circuit; a power measurement unit that measures the amount of power supplied to the electric vehicle through the electric path; a communication unit that receives an opening / closing instruction signal that instructs the power opening / closing unit to open / close the electric circuit and transmits the amount of electric power measured by the power measurement unit; A control unit; Equipped with The power measurement unit A current measuring unit that measures an AC current flowing through the electric circuit; A voltage measuring unit that measures an AC voltage applied to the electric circuit; a current correction value calculation unit that calculates a correction value for correcting the current measurement value output from the current measurement unit; a current calculation unit that corrects the current measurement value output from the current measurement unit based on the correction value and calculates an AC current value flowing through the electric circuit; a voltage calculation unit that calculates an AC voltage value applied to the electric circuit based on the voltage measurement value output from the voltage measurement unit; a power calculation unit that calculates an AC power value supplied through the electric path based on the AC voltage value calculated by the voltage calculation unit and the AC current value calculated by the current calculation unit; having The current correction value calculation unit is characterized in that it averages peak values ​​of the waveform of the current measurement value to estimate an effective value of the current measurement value, and calculates the correction value by comparing the estimated effective value of the current measurement value with the effective value of a reference value of the AC current flowing through the electric circuit.

[0024] According to this, the peak values ​​of the waveform of the measured current value are averaged to estimate the effective value of the measured current value, so the processing load when estimating the effective value is smaller than when performing a calculation with a large processing load such as square root calculation. Also, the memory area (ROM, RAM, etc.) for storing the calculation functions required for square root calculation can be reduced. Therefore, it is possible to provide a power switching module with a low processing load for power calculation and which does not use unnecessary memory area. Effect of the Invention

[0025] According to the present invention, it is possible to provide a power meter that requires a small processing load for power calculation and does not use unnecessary storage areas. [Brief description of the drawings]

[0026] [Figure 1] 1 is a diagram showing a schematic configuration of a power meter according to an embodiment of the present invention; [Diagram 2] 4 is a flowchart illustrating a current correction method according to an embodiment of the present invention. [Diagram 3] 1 is an overall configuration diagram of a charging system including a power switching module according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] [Application example] Hereinafter, application examples of the present invention will be described with reference to the drawings. FIG. 1 shows an energy meter 100 to which the present invention is applied.

[0028] The electricity meter 100 includes a current detection unit 11, a voltage detection unit 12, a current AD conversion unit 13, a voltage AD conversion unit 14, a current correction calculation unit 15, a current calculation unit 16, a voltage calculation unit 17, a power calculation unit 18, and a communication unit 19.

[0029] The watt-hour meter 100 is a device that is disposed, for example, on an electric line PL1 that supplies AC power from an AC power source 120 to a load 130, and measures the power or the amount of power supplied from the AC power source 120 to the load 130.

[0030] The current detection unit 11 includes a current sensor that detects the current in the electric circuit PL1, and outputs a value indicating the current in the electric circuit PL1 as an analog value. Here, the value indicating the current in the electric circuit PL1 is output as a voltage value. The current AD conversion unit 13 converts the value indicating the current in the electric circuit PL1 input from the current detection unit 11 into a digital value (referred to as a current measurement value).

[0031] The current correction calculation unit 15 calculates a gain correction value used in the current calculation unit 16. The process of the current correction calculation unit 15 will be described with reference to the flowchart shown in FIG. First, an AC current is applied from the AC power source 120 to the load 130 via the watt-hour meter 100 (step S1). Here, the current correction calculation unit 15 acquires the current measurement value from the current AD conversion unit 13 (step S2). Then, the current correction calculation unit 15 extracts peak points from the waveform of the acquired current measurement value, and calculates the average value of the extracted peak points (step S3). Based on the average value of the peak points of the current measurements, the effective value of the current input to the watt-hour meter 100 is estimated, and this estimated effective value of the current is compared with the true value of the current input to the watt-hour meter 100, which is input from the adjustment equipment 110, to calculate a gain correction value (step S4). The gain correction value and the adjustment value correspond to the correction value of the present invention. Then, the calculated gain correction value is set as a current adjustment value used in the current calculation unit 16 (described later) (step S5).

[0032] The current calculation unit 16 calculates the current value to be input to the watt-hour meter 100 from the current measurement value input from the current AD conversion unit 13, using a gain correction value set as an adjustment value.

[0033] The voltage detection unit 12 outputs a value indicating the voltage of the electric line PL1 as an analog value. The voltage AD conversion unit 14 converts the value indicating the voltage of the electric line PL1 input from the voltage detection unit 12 into a digital value (referred to as a voltage measurement value).

[0034] The voltage calculation unit 17 calculates the value of a voltage to be input to the load from the voltage measurement value input from the voltage AD conversion unit 14 .

[0035] The power calculation unit 18 calculates the power input to the watt-hour meter 100 based on the current value and the voltage value. The amount of power is then calculated by integrating this for a predetermined period of time.

[0036] By calculating the gain correction value by the method described for the current correction calculation unit 15, the processing load when calculating the gain correction value can be reduced compared to the case where the effective value is calculated by calculating the square root, and thus the processing load when calculating the power can be reduced.

[0037] Example 1 Hereinafter, the watt-hour meter 100 according to the first embodiment of the present invention will be described in more detail with reference to the drawings. However, the configurations of the device and system described in this embodiment should be appropriately changed depending on various conditions. In other words, it is not intended to limit the scope of the present invention to the following embodiment.

[0038] FIG. 1 shows a functional block diagram of a power meter 100. As shown in FIG. The watt-hour meter 100 includes a current detection unit 11, a voltage detection unit 12, a current AD conversion unit 13, a voltage AD conversion unit 14, a current correction calculation unit 15, a current calculation unit 16, a voltage calculation unit 17, a power calculation unit 18, and a communication unit 19. Here, the current correction calculation unit 15, the current calculation unit 16, the voltage calculation unit 17, and the power calculation unit 18 are functional units realized by a watt-hour meter control unit 10 including a processor such as an MPU executing a predetermined program. The watt-hour meter 10 can calculate power and power amount, and corresponds to the watt-hour meter of the present invention. Moreover, the current detection unit 11 and the current AD conversion unit 13 correspond to the current measurement unit of the present invention, and the voltage detection unit 12 and the voltage AD conversion unit 14 correspond to the voltage detection unit of the present invention. Moreover, the current correction calculation unit 15 corresponds to the current correction value calculation unit of the present invention, and the current calculation unit 16 and the voltage calculation unit 17 correspond to the current calculation unit and the voltage calculation unit of the present invention. Moreover, the power calculation unit 18 corresponds to the power calculation unit of the present invention.

[0039] 1 also shows an adjustment facility 110 in addition to the watt-hour meter 100. The adjustment facility 110 is a facility used to set an adjustment value used for controlling the load 130 and correcting the current when the watt-hour meter 100 is manufactured.

[0040] The current detection unit 11 includes a current sensor that detects the current of the electrical circuit PL1, and outputs a value indicating the current of the electrical circuit PL1 as an analog value. Here, the value indicating the current of the electrical circuit PL1 is output as a voltage value. The current AD conversion unit 13 converts the value indicating the current of the electrical circuit PL1 input from the current detection unit 11 into a digital value. The digital value indicating the current of the electrical circuit PL1 output from the current AD conversion unit 13 is called a current measurement value. By using a voltage value as a value indicating the current of the electrical circuit PL1, data with high resolution can be processed, making it possible to calculate power with high accuracy.

[0041] The current correction calculation unit 15 calculates a gain correction value used in the current calculation unit 16. A flowchart for explaining a method for setting the gain correction value is shown in FIG. 2, and will be explained together with the function of the current correction calculation unit 15. The setting of this gain correction value is performed based on an instruction from the adjustment facility 110. First, an AC current is applied from the AC power source 120 to the load 130 via the watt-hour meter 100 (step S1). Here, the current correction calculation unit 15 acquires the current measurement value from the current AD conversion unit 13 (step S2). Then, the current correction calculation unit 15 extracts peak points from the waveform of the acquired current measurement value, and calculates the average value of the extracted peak points (step S3). Based on the average value of the peak points of the current measurement values ​​thus calculated, the effective value of the current input to the watt-hour meter 100 is estimated, and the estimated effective value of the current is compared with the true value of the current input to the watt-hour meter 100 input from the adjustment equipment 110 to calculate a gain correction value. In this way, the effective value of the current input to the watt-hour meter 100 is estimated based on the average value of the peak points of the current measurement values, and the estimated effective value is used to calculate the gain correction value, thereby making it possible to reduce the processing load when calculating the gain correction value, compared to the case where the effective value is calculated by calculating the square root. Then, the calculated gain correction value is set as a current adjustment value used in the current calculation unit 16, which will be described later (step S5). That is, the gain correction value is stored in a predetermined area of ​​the storage unit.

[0042] The current calculation unit 16 calculates a current value to be input to the watt-hour meter 100 from the current measurement value input from the current AD conversion unit 13. In the process of calculating the current to be input to the watt-hour meter 100, the current calculation unit 16 performs correction using the gain correction value calculated in the current correction calculation unit 15 and set as an adjustment value.

[0043] The voltage detection unit 12 outputs a value indicating the voltage of the electric circuit PL1 as an analog value. The voltage AD conversion unit 14 converts the value indicating the voltage of the electric circuit PL1 input from the voltage detection unit 12 into a digital value. The digital value indicating the voltage of the electric circuit PL1 output from the voltage AD conversion unit 14 is called a voltage measurement value.

[0044] The voltage calculation unit 17 calculates the value of a voltage to be input to the load from the voltage measurement value input from the voltage AD conversion unit 14 .

[0045] The power calculation unit 18 calculates the power input to the power meter 100 and the amount of power accumulated over a specified period of time based on the current value and voltage value input to the power meter 100 calculated by the current calculation unit 16 and the voltage calculation unit 17.

[0046] The adjustment equipment 110 has a function of measuring a current value input to the watt-hour meter 100. The adjustment equipment 110 is capable of measuring a current with higher accuracy than the current detection unit 11 of the watt-hour meter 100. For this reason, the current value measured in the adjustment equipment 110 is called a true value. The adjustment equipment 110 also transmits to the watt-hour meter 100 the true value of the current value input to the watt-hour meter 100, and transmits an instruction to perform a correction during current calculation. The adjustment equipment 110 is independent of the watt-hour meter 100, and is connected to and used by the watt-hour meter 100 only during manufacturing inspection of the watt-hour meter 100. The portion and method of the adjustment equipment 110 that measures the current value supplied to the watt-hour meter 100 are not limited.

[0047] The communication unit 19 is an interface that performs communication such as transmitting power or an amount of power to a device or system provided outside the watt-hour meter 100 in accordance with a predetermined communication method.

[0048] Such an electric power meter 100 can realize a current correction method that can reduce the processing load and perform accurate current calculation without using unnecessary storage areas.

[0049] [Modifications] In the above-described first embodiment, the adjustment equipment 110 measures the current flowing through the electric circuit PL1 with higher accuracy than the current detection unit 11 and the current AD conversion unit 13, and provides the current to the current correction calculation unit 15 as a reference value (true value). However, as shown in FIG. 1, the adjustment equipment 110 may also utilize a function of controlling the load 130. That is, the same effect can be achieved by having the adjustment equipment 110 control the load 130 so that the current value consumed by the load 130 becomes a preset reference value (command value). In this case, the adjustment equipment 110 adjusts the current value flowing through the load 130 with higher accuracy than the current detection unit 11 and the current AD conversion unit 13. The process in the current correction calculation unit 15 is similar, but when calculating the gain correction value, a preset current value is used as the true value of the current input to the watt-hour meter 100, instead of the current value measured by the adjustment equipment 110. A current value (command value) is used. For example, a true value is set in advance to 16 A, and the adjustment equipment 110 adjusts with high precision the current value consumed by the load 130 to 16 A, and transmits a correction command for current calculation. In this manner, a current correction method capable of accurate current calculation can be realized, and the function of transmitting the true current value from outside to the watt-hour meter 100 can be omitted.

[0050] Example 2 FIG. 3 shows a charging system 300 including a power switching module 200 equipped with the watt-hour meter 100 according to the first embodiment. The charging system 300 includes an EV charging outlet 220, a power switching module 200 that opens and closes an electric circuit PL2 that charges a storage battery of an EV (Electric Vehicle) 230 connected via the EV charging outlet 220 using power supplied from an AC power source 210, and a charging management system 250 that is connected to the power switching module 200 via a network NT1.

[0051] The power switching module 200 mainly includes a relay 21, a power measurement unit 22, a communication unit 23, and a control unit 24. The relay 21 opens and closes an electric circuit PL2 that connects an AC power source 210 and an EV charging outlet 220. The power measurement unit 22 measures the power supplied to the EV 230 through the electric circuit PL2. The communication unit 23 is an interface that transmits and receives information between the power switching module 200 and an external device using a predetermined communication method. The control unit 24 overall controls the relay 21, the power measurement unit 22, and the communication unit 23.

[0052] The power measurement unit 22 includes the current detection unit 11, the voltage detection unit 12, the current AD conversion unit 13, the voltage AD conversion unit 14, the current correction calculation unit 15, the current calculation unit 16, the voltage calculation unit 17, and the power calculation unit 18 of the watthour meter 100 according to the first embodiment, and the control unit 24 includes a processor such as an MPU and a memory, and also functions as the watthour meter control unit 10. The communication unit 23 functions as the communication unit 19 of the watthour meter 100 according to the first embodiment. The control unit 24 may operate in cooperation with the watthour meter control unit 10 that is provided independently.

[0053] An example of the operation of the charging system 300 described above will be described below. The charging management system 250 is, for example, a computer device such as a plurality of servers arranged on a cloud.

[0054] The charging management system 250 monitors and controls the power switching modules 200 connected via the network NT1, via the target EV charging outlets 220.

[0055] Power switching module 200 is housed as a module in a housing of a pole or a box that is charging equipment 260 provided with EV charging outlet 220, for example. Relay 21 and power measurement unit 22 are arranged on electric circuit PL2 that connects AC power source 210 and EV charging outlet 220 and supplies AC power supplied from AC power source 210 to EV 230 via EV charging outlet 220. Relay 21 opens and closes electric circuit PL2 in response to an instruction from control unit 24, and charges the storage battery of EV 230. Power measurement unit 22 measures the power or the amount of power supplied from AC power source 210 to EV 230 via EV charging outlet 220. Charging management system 250 monitors and controls the operation of power switching module 200 based on necessary information transmitted from communication unit 23.

[0056] In such a charging system 300, the current input to the power switching module 200 can be corrected without increasing the processing load, so that a power switching module 200 can be provided that can accurately measure power or amount of power without increasing the processing load.

[0057] In the following, the components of the present invention will be described with reference to the reference numerals in the drawings in order to make it possible to compare the components of the present invention with the configurations of the embodiments. <Appendix 1> A power meter (100) is provided in an electric circuit (PL1) connecting an AC power source (120) and a load (130), and measures AC power supplied from the AC power source (120) to the load (130) through the electric circuit (PL1), a current measuring unit (11, 13) for measuring an AC current flowing through the electric circuit (PL1); a voltage measuring unit (12, 14) for measuring an AC voltage applied to the electric circuit (PL1); a current correction value calculation unit (15) that calculates a correction value for correcting the current measurement value output from the current measurement unit (11, 13); a current calculation unit (16) that corrects the current measurement values ​​output from the current measurement units (11, 13) based on the correction value and calculates an AC current value flowing through the electric circuit (PL1); a voltage calculation unit (17) that calculates an AC voltage value applied to the electric circuit based on the voltage measurement value output from the voltage measurement unit; a power calculation unit (18) that calculates a value of AC power supplied through the electric circuit (PL1) based on the AC voltage value calculated in the voltage calculation unit (17) and the AC current value calculated in the current calculation unit (16); and Equipped with The power meter (100) is characterized in that the current correction value calculation unit (15) averages peak values ​​of the waveform of the current measurement value to estimate an effective value of the current measurement value, and calculates the correction value by comparing the estimated effective value of the current measurement value with an effective value of a reference value of the AC current flowing through the electric circuit (PL1). <Appendix 2> 2. The power meter (100) of claim 1, wherein the current measurement value is a voltage value indicative of the AC current. <Appendix 3> The power meter (100) according to claim 1 or 2, wherein the reference value is a measurement value of the AC current flowing through the electrical circuit (PL1) that is more accurate than the current measurement unit (11, 13). <Appendix 4> 3. The power meter (100) according to claim 1 or 2, wherein the reference value is a command value of the AC current flowing through the electric circuit (PL1) by the load (130). <Appendix 5> A current correction method for correcting a measured value of an AC current flowing through an electric circuit (PL1) connecting an AC power source (120) and a load (110), the measured value being used for calculating AC power supplied through the electric circuit (PL1), the method comprising the steps of: measuring the AC current to obtain the measured value (S1, S2); A step (S3) of averaging peak values ​​of the waveform of the measurement value to estimate an effective value of the measurement value; A step (S4) of calculating a correction value for correcting the measured value by comparing the estimated effective value with an effective value of the reference value of the AC current; A current correction method comprising: <Appendix 6> 6. The current correction method according to claim 5, wherein the current measurement value is a voltage value indicating the AC current. <Appendix 7> The current correction method according to claim 5 or 6, wherein the reference value is a measurement value of the AC current flowing through the electrical circuit (PL1) that is more accurate than the measurement value. <Appendix 8> The reference value is the value of the AC current flowing through the electrical circuit (PL1) by the load (130). 7. The current correction method according to claim 5 or 6, wherein the current correction value is a command value. <Appendix 9> An electric power switching module (200) for switching an electric circuit (PL2) connecting an AC power source (210) and an electric vehicle (230), a power switching unit (21) that switches the electric circuit (PL2); a power measurement unit (22) for measuring the amount of power supplied to the electric vehicle (230) through the electric line (PL2); a communication unit (23) that receives an opening / closing instruction signal that instructs the power switching unit (21) to open or close the electric circuit (PL2) and transmits the amount of electric power measured by the power measurement unit (22); A control unit (24); Equipped with The power measuring unit (22) a current measuring unit (11, 13) for measuring an AC current flowing through the electric circuit (PL2); a voltage measuring unit (12, 14) for measuring an AC voltage applied to the electric circuit (PL2); a current correction value calculation unit (15) that calculates a correction value for correcting the current measurement value output from the current measurement unit (11, 13); a current calculation unit (16) that corrects the current measurement values ​​output from the current measurement units (11, 13) based on the correction value and calculates an AC current value flowing through the electric circuit (PL2); a voltage calculation unit (17) that calculates an AC voltage value applied to the electric circuit (PL2) based on the current measurement values ​​output from the voltage measurement units (12, 14); a power calculation unit (18) that calculates a value of AC power supplied through the electric path (PL2) based on the AC voltage value calculated in the voltage calculation unit (17) and the AC current value calculated in the current calculation unit (16); having The power switching module (200) is characterized in that the current correction value calculation unit (15) averages peak values ​​of the waveform of the current measurement value to estimate an effective value of the current measurement value, and calculates the correction value by comparing the estimated effective value of the current measurement value with an effective value of a reference value of the AC current flowing through the electric circuit. [Explanation of symbols]

[0058] 11: Current detection section 12: Voltage detection section 13: Current AD conversion section 14: Voltage AD conversion section 15: Current correction value calculation section 16: Current calculation section 17: Voltage calculation section 18: Power calculation section 100: Power meter 120: AC power supply 130: Load PL1: Electrical line

Claims

1. A power meter that is provided in an electric circuit that connects an AC power source and a load, and measures AC power supplied from the AC power source to the load through the electric circuit, A current measuring unit that measures an AC current flowing through the electric circuit; A voltage measuring unit that measures an AC voltage applied to the electric circuit; a current correction value calculation unit that calculates a correction value for correcting the current measurement value output from the current measurement unit; a current calculation unit that corrects the current measurement value output from the current measurement unit based on the correction value and calculates an AC current value flowing through the electric circuit; a voltage calculation unit that calculates an AC voltage value applied to the electric circuit based on the voltage measurement value output from the voltage measurement unit; a power calculation unit that calculates an AC power value supplied through the electric path based on the AC voltage value calculated by the voltage calculation unit and the AC current value calculated by the current calculation unit; Equipped with the current correction value calculation unit estimates an effective value of the measured current value by averaging peak values ​​of a waveform of the measured current value, and calculates the correction value by comparing the estimated effective value of the measured current value with an effective value of a reference value of the AC current flowing through the electric circuit.

2. 2. The power meter of claim 1, wherein the current measurement value is a voltage value indicative of the alternating current.

3. 3. The wattmeter according to claim 1, wherein the reference value is a measurement value of the AC current flowing through the electrical path that is more accurate than the current measurement unit.

4. 3. The power meter according to claim 1, wherein the reference value is a command value of the AC current flowing through the electrical path by the load.

5. 1. A current correction method for correcting a measured value of an AC current flowing through an electric circuit connecting an AC power source and a load, the measured value being used for calculating AC power supplied through the electric circuit, the method comprising the steps of: measuring said alternating current to obtain said measurement; averaging the peak values ​​of the waveform of the measurement to estimate an effective value of the measurement; comparing the estimated effective value with an effective value of the reference value of the AC current to calculate a correction value for correcting the measured value; A current correction method comprising:

6. 6. The current correction method according to claim 5, wherein the measured value is a voltage value indicating the AC current.

7. 7. The current correction method according to claim 5, wherein the reference value is a measurement value of the AC current flowing through the electrical path that is more accurate than the measurement value.

8. 7. The current correction method according to claim 5, wherein the reference value is a command value of the AC current flowing through the electrical path by the load.

9. An electric power switching module that switches an electric circuit connecting an AC power source and an electric vehicle, a power switching unit that switches the electric circuit; a power measurement unit that measures the amount of power supplied to the electric vehicle through the electric path; A switching instruction signal is received to instruct the power switching unit to open or close the electric circuit, and a communication unit that transmits the amount of power measured by the power measurement unit; A control unit; Equipped with The power measurement unit A current measuring unit that measures an AC current flowing through the electric circuit; A voltage measuring unit that measures an AC voltage applied to the electric circuit; a current correction value calculation unit that calculates a correction value for correcting the current measurement value output from the current measurement unit; a current calculation unit that corrects the current measurement value output from the current measurement unit based on the correction value and calculates an AC current value flowing through the electric circuit; a voltage calculation unit that calculates an AC voltage value applied to the electric circuit based on the voltage measurement value output from the voltage measurement unit; a power calculation unit that calculates an AC power value supplied through the electric path based on the AC voltage value calculated by the voltage calculation unit and the AC current value calculated by the current calculation unit; having The current correction value calculation unit calculates the correction value by averaging peak values ​​of the waveform of the current measurement value, estimating an effective value of the current measurement value, and comparing the estimated effective value of the current measurement value with an effective value of a reference value of the AC current flowing through the electric circuit.

Images