Method, program, and apparatus

Abstract

A method according to the present disclosure includes: acquiring at least two inter-wire voltage values among a wire voltage value between a first wire and a second wire, a wire voltage value between the second wire and a third wire, and a wire voltage value between the third wire and the first wire, and a wire current value of at least two among the first wire, the second wire, and the third wire; and calculating the resistance value of each phase of the three-phase heater according to the obtained inter-line voltage value and the line current value. In a first state in which no current flows only in the first electric wire and a second state in which no current flows only in the second electric wire, an inter-wire voltage value and a wire current value are acquired.

Description

Technical Field

[0001] The present disclosure relates to a method, a program, and an apparatus for calculating a resistance value of each phase of a three-phase heater. Background Art

[0002] Patent Document 1 discloses a three-phase heater resistance value detection device that calculates the resistance value of each of three resistors based on power consumption of the three-phase heater and effective values ​​of current or voltage applied to the three-phase heater.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2020-148697 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] The device of Patent Document 1 has room for improvement in terms of easily calculating the resistance value of each phase of the three-phase heater.

[0008] An object of the present disclosure is to provide a method, a program, and a device that can easily calculate the resistance value of each phase of a three-phase heater.

[0009] Means for solving problems

[0010] A method according to one embodiment of the present disclosure obtains line-to-line voltage values ​​of a first electric wire, a second electric wire, and a third electric wire respectively connecting a three-phase power supply and a three-phase heater including three resistors, at least two of the line-to-line voltage values ​​of the first electric wire and the second electric wire, the line-to-line voltage values ​​of the second electric wire and the third electric wire, and the line-to-line voltage values ​​of the third electric wire and the first electric wire, and line current values ​​of at least two of the first electric wire, the second electric wire, and the third electric wire, and calculates the resistance value of each phase of the three-phase heater based on the obtained line-to-line voltage values ​​and the line current values, wherein the line-to-line voltage values ​​and the line current values ​​are obtained in a first state in which no current flows only in the first electric wire and a second state in which no current flows only in the second electric wire.

[0011] A program according to one embodiment of the present disclosure causes a computer to execute the following method: obtaining line-to-line voltage values ​​of a first electric wire and a second electric wire, a line-to-line voltage value of a second electric wire, and a line-to-line voltage value of a third electric wire, which respectively connect a three-phase power supply and a three-phase heater including three resistors, and obtaining at least two line-to-line voltage values ​​of the first electric wire and the second electric wire, a line-to-line voltage value of the second electric wire and the third electric wire, and a line-to-line voltage value of the third electric wire and the first electric wire, as well as line current values ​​of at least two of the first electric wire, the second electric wire, and the third electric wire, and calculating the resistance value of each phase of the three-phase heater based on the obtained line-to-line voltage values ​​and the line current values. In this method, the line-to-line voltage values ​​and the line current values ​​are obtained in a first state in which no current flows only in the first electric wire and a second state in which no current flows only in the second electric wire.

[0012] An apparatus according to one embodiment of the present disclosure comprises: an acquisition unit configured to acquire line-to-line voltage values ​​of a first electric wire and a second electric wire, a line-to-line voltage value of a second electric wire, and a line-to-line voltage value of a third electric wire, which respectively connect a three-phase power supply and a three-phase heater including three resistors, and at least two line-to-line voltage values ​​of the first electric wire and the second electric wire, the line-to-line voltage value of the second electric wire and the third electric wire, and the line-to-line voltage value of the third electric wire and the first electric wire, and line current values ​​of at least two of the first electric wire, the second electric wire, and the third electric wire; and a calculation unit configured to calculate the resistance value of each phase of the three-phase heater based on the acquired line-to-line voltage values ​​and the line current values, the acquisition unit configured to acquire the line-to-line voltage values ​​and the line current values ​​in a first state in which no current flows only in the first electric wire and a second state in which no current flows only in the second electric wire.

[0013] Effects of the Invention

[0014] According to the present disclosure, it is possible to realize a method, a program, and a device capable of easily calculating the resistance value of each phase of a three-phase heater. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a block diagram illustrating an apparatus according to one embodiment of the present disclosure.

[0016] Figure 2 1 is a block diagram showing a three-phase heater in which three resistors are connected in a delta (Δ) configuration.

[0017] Figure 3 This is a diagram showing an example of the current waveform of each electric wire when the current supplied to the three-phase heater is adjusted by the adjustment unit including three SSRs.

[0018] Figure 4 This is a diagram for explaining the characteristics of a triac-type SSR.

[0019] Figure 5 This is a diagram showing an example of current waveforms in the respective electric wires when the current supplied to the three-phase heater is adjusted by an adjustment unit including a power regulator.

[0020] Figure 6 It shows Figure 2 The first block diagram of the first state of the three-phase heater.

[0021] Figure 7 It shows Figure 2 The first block diagram of the second state of the three-phase heater.

[0022] Figure 8 It shows Figure 2 Block diagram of the 3rd state of the three-phase heater.

[0023] Figure 9 It shows Figure 2 The second block diagram of the first state of the three-phase heater.

[0024] Figure 10 It shows Figure 2 The second block diagram of the second state of the three-phase heater.

[0025] Figure 11 It shows Figure 2 Block diagram of the 2nd state of the three-phase heater.

[0026] Figure 12 1 is a block diagram showing a three-phase heater in which three resistors are connected in a star shape.

[0027] Figure 13 It shows Figure 12 Block diagram of the 1st state of the three-phase heater.

[0028] Figure 14 It shows Figure 12 Block diagram of the 2nd state of the three-phase heater.

[0029] Figure 15 It shows Figure 12 Block diagram of the 3rd state of the three-phase heater.

[0030] Figure 16 This is a flowchart showing an example of the method of the present disclosure. DETAILED DESCRIPTION

[0031] Below, an example of the present disclosure is described with reference to the accompanying drawings. The following description is merely illustrative in nature and is not intended to limit the present disclosure, its applications, or its uses. The accompanying drawings are schematic, and the ratios of dimensions and other factors may not necessarily correspond to actual conditions.

[0032] The device 1 of one embodiment of the present disclosure is configured to be able to calculate the resistance value of each phase of the three-phase heater 100. Figure 1 As shown, the three-phase heater 100 includes three resistors (hereinafter referred to as the first resistor 101, the second resistor 102 and the third resistor 103). Figure 2 As shown, the three-phase heater 100 is connected to a three-phase power supply 120 via three wires (hereinafter referred to as a first wire 111, a second wire 112, and a third wire 113). An adjustment unit 130 is located between the three-phase heater 100 and the three-phase power supply 120. The adjustment unit 130 is configured to be on and off controllable, and when turned on, current is supplied from the three-phase power supply 120 to the three-phase heater 100.

[0033] In this embodiment, as an example, the first resistor 101, the second resistor 102, and the third resistor 103 of the three-phase heater 100 are connected in a delta connection, and the adjustment unit 130 includes three SSRs 131, 132, and 133. The second wire 112 and the other end of the second resistor 102 are electrically connected to one end of the first resistor 101. The third wire 113 and the other end of the third resistor 103 are electrically connected to one end of the second resistor 102. The first wire 111 and the other end of the first resistor 101 are electrically connected to one end of the third resistor 103. The SSR 131 is configured to adjust the current supplied to the three-phase heater 100 via the first wire 111. The SSR 132 is configured to adjust the current supplied to the three-phase heater 100 via the second wire 112. The SSR 133 is configured to adjust the current supplied to the three-phase heater 100 via the third wire 113. The SSRs 131 , 132 , and 133 are controlled by, for example, a common input signal.

[0034] The line current values ​​Ir, Is, and It of each electric wire are detected by current measuring circuit 140 and transmitted to device 1 as, for example, analog signals. Current measuring circuit 140 is configured to detect at least two line currents. The line voltage value Vrs between the first electric wire 111 and the second electric wire 112, the line voltage value Vst between the second electric wire 112 and the third electric wire 113, and the line voltage value Vtr between the third electric wire 113 and the first electric wire 111 are detected by voltage measuring circuit 150 and transmitted to device 1 as, for example, analog signals. Voltage measuring circuit 150 is configured to detect at least two line voltage values.

[0035] like Figure 1 As shown, the device 1 includes an acquisition unit 21 and a calculation unit 22. In this embodiment, the device 1 includes a processor 11 and a storage unit 12. The acquisition unit 21 and the calculation unit 22 are implemented by, for example, the processor 11 executing a predetermined program stored in the storage unit 12.

[0036] The processor 11 includes, for example, a CPU, an MPU, a GPU, a DSP, an FPGA, or an ASIC. The storage unit 12 includes, for example, an internal recording medium or an external recording medium. The internal recording medium includes, for example, a nonvolatile memory. The external recording medium includes, for example, a hard disk drive (HDD), a solid-state drive (SSD), or an optical disk device.

[0037] The acquisition unit 21 is configured to acquire at least two of the line voltage values ​​Vrs of the first and second electric wires 111 and 112, the line voltage value Vst of the second and third electric wires 112 and 113, and the line voltage value Vtr of the third electric wire 113 and the first electric wire 111, as well as at least two of the line current values ​​of the first, second, and third electric wires 111 and 112. In this embodiment, the acquisition unit 21 is configured to acquire the line voltage values ​​Vrs, Vst, and Vtr and the line current values ​​Ir, Is, and It at the same timing. "The same timing" is not limited to completely identical timing and also includes, for example, timing within a range where the performance of the current measurement circuit 140 and the voltage measurement circuit 150 can be considered equivalent.

[0038] Specifically, the acquisition unit 21 is configured to acquire line voltage and line current values ​​in at least two of the following three states. The line voltage values ​​Vrs, Vst, and Vtr and the line current values ​​Ir, Is, and It are instantaneous values ​​and are acquired, for example, at fixed sampling intervals. The acquired line voltage values ​​Vrs, Vst, Vtr and line current values ​​Ir, Is, and It at each sampling point are classified into one of a first state, a second state, a third state, and another state. Another state is a state in which the three line current values ​​Ir, Is, and It are all zero, or a state in which none of the three line current values ​​Ir, Is, and It are zero. Due to the properties of the three-phase heater 100, the sum of the three line current values ​​Ir, Is, and It and the sum of the three line voltage values ​​Vrs, Vst, and Vtr is zero. Therefore, if at least two arbitrary line voltage values ​​and at least two arbitrary line current values ​​can be obtained, the remaining line voltage value and line current value can be calculated based on the obtained line voltage values ​​and line current values. The remaining line voltage value and line current value can be calculated by an external device such as a server, or by device 1.

[0039] (First State) A state in which no current flows through any one of the first electric wire 111 , the second electric wire 112 , and the third electric wire 113 .

[0040] (Second state) A state in which no current flows through only one of the first electric wire 111, the second electric wire 112, and the third electric wire 113, excluding the electric wire that did not flow in the first state. For example, if no current flows through the first electric wire 111 in the first state, no current flows through either the second electric wire 112 or the third electric wire 113 in the second state.

[0041] (Third state) A state in which current does not flow only through the first electric wire 111, the second electric wire 112, and the third electric wire 113, excluding the electric wires that did not flow in the first and second states. For example, if current does not flow only through the first electric wire 111 in the first state and only through the second electric wire 112 in the second state, current does not flow only through the third electric wire in the third state.

[0042] Figure 3 An example of the current waveform of each electric wire when the current supplied to the three-phase heater 100 is adjusted by the adjustment unit 130 including three solid-state relays (SSR) is shown. Figure 3 In FIG, the solid line shows the line current value Ir of the first electric wire 111, the dotted line shows the line current value Is of the second electric wire 112, and the dashed line shows the line current value It of the third electric wire 113. The adjustment unit 130 is not limited to including three SSRs, and may include at least two SSRs.

[0043] In a normal AC waveform, the timing when the current value becomes zero is the zero-crossing point of the current waveform, and it is considered that the sampling point does not coincide with the zero-crossing point. Figure 3 As shown, in a triac-type SSR, the end of conduction (when switched on) always corresponds to a zero-crossing point for the line current. During the specified period P1 immediately before the SSR switches from on to off, the line current in only one of the three power lines is guaranteed to be zero. This specified period P1 has a wide range, so even with a fixed sampling period, if the sampling period is sufficiently short compared to the power supply cycle, there are abundant sampling points where the line current reaches zero. In other words, when the adjustment unit 130 is comprised of a triac-type SSR, the line-to-line voltage values ​​Vrs, Vst, and Vtr and the line current values ​​Ir, Is, and It in the first through third states can be easily acquired.

[0044] In the bidirectional thyristor type SSR, in the SSR with zero cross function, such as Figure 3As shown, the line current zero-crossing point is guaranteed at the beginning of conduction, not just the end of conduction. During the predetermined period P2 immediately after the SSR switches from off to on, the line current in one of the three wires is guaranteed to be zero. Specifically, when adjustment unit 130 includes a triac-type SSR with a zero-crossing function, the line voltage values ​​Vrs, Vst, and Vtr and the line current values ​​Ir, Is, and It in the first through third states can be easily obtained.

[0045] The bidirectional thyristor type SSR has the following characteristics: even if the output is 100%, the line current value will not be a perfect sine wave, such as Figure 4 As shown, after temporarily becoming non-conductive at the zero-crossing point P0, it is temporarily conductive (a period T0 during which the current value is zero). Specifically, when the adjustment unit 130 includes a triac-type SSR, there is a period with a width during which the line current value is zero at each zero-crossing point. Therefore, for example, even when control is continued with 100% output and there are no initial and final periods of conduction, the line voltage values ​​Vrs, Vst, and Vtr and the line current values ​​Ir, Is, and It in the first to third states can be easily obtained.

[0046] In this specification, an SSR using a triac or a thyristor as a switching element is referred to as a "triac-type SSR."

[0047] The adjustment unit 130 is not limited to the one including at least two SSRs, and may be formed of a power regulator capable of controlling the phase of the current supplied from the three-phase power supply 120 .

[0048] Figure 5 FIG. 1 shows an example of the current waveform of each electric wire when the current supplied to the three-phase heater 100 is adjusted by the adjustment unit 130 including the power regulator. Figure 5 In FIG. 1 , the line current value Ir of the first electric wire 111 is shown by a solid line, the line current value Is of the second electric wire 112 is shown by a dotted line, and the line current value It of the third electric wire 113 is shown by a dashed line.

[0049] like Figure 5As shown, in phase control using the power conditioner, within the power supply cycle, period P3, where only the line current value in the first power line 111 is zero, period P4, where only the line current value in the second power line 112 is zero, and period P5, where only the line current value in the third power line 113 is zero, each occur at least once. The prescribed periods P3-P5 have a certain width, so even with a fixed sampling period, if the sampling period is sufficiently small compared to the power supply cycle, there are abundant sampling points where the line current value is zero. In other words, even when the adjustment unit 130 includes a power conditioner, the line voltage values ​​Vrs, Vst, and Vtr and the line current values ​​Ir, Is, and It in the first to third states can be easily acquired. When the power conditioner output is 100%, the line current values ​​in each power line exhibit the same waveform as when the adjustment unit 130 includes three SSRs, each with an output of 100%.

[0050] When the current supplied to the three-phase heater is adjusted by the adjustment unit 130 , the detected line current value may not be completely zero due to the following two reasons.

[0051] SSRs and power regulators have snubber circuits for noise suppression, so even when they are off (non-conducting), a leakage current of approximately 10 to 20 mA is generated.

[0052] Due to measurement accuracy, the detected line current value may not be zero even when the current is zero.

[0053] In this embodiment, if one of the three acquired line current values ​​Ir, Is, and It is less than a first threshold value (e.g., 10 mA) and the remaining two line current values ​​are greater than a second threshold value (e.g., 20 mA), the acquisition unit 21 determines that no current is flowing only in the electric wire corresponding to the line current value less than the first threshold value. For example, suppose the acquired line current value Ir of the first electric wire 111 is less than the first threshold value, and the acquired line current values ​​Is and It of the second and third electric wires 112 and 113 are greater than the second threshold value. In this case, the acquisition unit 21 determines that no current is flowing only in the first electric wire 111.

[0054] The appropriate values ​​for the first and second thresholds vary depending on the current measurement range, for example. For example, the first threshold is set within a range that allows for determining when the adjustment unit 130 is disconnected and does not significantly affect the resistance measurement accuracy. The second threshold is set within a range that eliminates the possibility that all three acquired line current values, Ir, Is, and It, are zero. The first and second thresholds can be preset or user-settable. For example, the second threshold can be set to the same value as the first threshold or slightly higher (e.g., approximately 10 mA).

[0055] The calculation unit 22 is configured to calculate the resistance value of each phase of the three-phase heater 100 based on the acquired line voltage values ​​Vrs, Vst, and Vtr and the line current values ​​Ir, Is, and It.

[0056] For example, a state in which no current flows only through the first electric wire 111 is referred to as the first state, a state in which no current flows only through the second electric wire 112 is referred to as the second state, and a state in which no current flows only through the third electric wire 113 is referred to as the third state. In this case, the calculation unit 22 calculates at least the first and second combined resistance values ​​R1, R2, and R3 of the three-phase heater 100 based on the line voltage values ​​Vrs, Vst, and Vtr and the line current values ​​Ir, Is, and It in the first to third states. Once the first, second, and third combined resistance values ​​R1, R2, and R3 are calculated, the resistance values ​​Rrs, Rst, and Rtr of each phase of the three-phase heater 100 are calculated based on the calculated first, second, and third combined resistance values ​​R3. When the first and second combined resistance values ​​R1 and R2 are calculated, the resistance values ​​of the phases of the three-phase heater 100 are calculated based on the first and second combined resistance values ​​R1 and R2 and the resistance ratios K and P of the phases of the three-phase heater 100 .

[0057] The first combined resistance value R1 , the second combined resistance value R2 , and the third combined resistance value R3 are calculated, for example, as shown below.

[0058] Calculate the first combined resistance R1 based on the absolute value of the line current value Is or It of the second electric wire 112 or the third electric wire 113 in the first state and the absolute value of the line voltage value Vst of the second electric wire 112 and the third electric wire 113 (refer to Figure 6 ).

[0059] The second combined resistance R2 is calculated based on the absolute value of the line current value Ir or It of the first electric wire 111 or the third electric wire 113 in the second state and the absolute value of the line voltage value Vtr of the first electric wire 111 and the third electric wire 113 (see Figure 7 ).

[0060] The third combined resistance R3 is calculated based on the absolute value of the line current value Ir or Is of the first electric wire 111 or the second electric wire 112 in the third state and the absolute value of the line voltage value Vrs between the first electric wire 111 and the second electric wire 112 (see Figure 8 ).

[0061] The resistance value of each phase of the three-phase heater 100 is calculated by solving the following simultaneous equations, for example. In the following simultaneous equations, f1, f2, and f3 are functions that differ depending on the connection method of the three-phase heater 100 (eg, delta connection or star connection).

[0062] <Delta connection>

[0063] ･R1=f1(Rrs,Rst,Rtr)

[0064] ･R2=f2(Rrs,Rst,Rtr)

[0065] ･R3=f3(Rrs,Rst,Rtr)

[0066] <Star connection>

[0067] ･R1=f1(Rs,Rt)

[0068] ･R2=f2(Rt,Rr)

[0069] ･R3=f3(Rr,Rs)

[0070] When calculating the first combined resistance value R1, the second combined resistance value R2, and the third combined resistance value R3 using the instantaneous values ​​of the line voltage values ​​Vrs, Vst, and Vtr and the line current values ​​Ir, Is, and It obtained in the first through third states, it is considered that calculation accuracy may be reduced due to, for example, input errors in the instantaneous values. In this embodiment, the calculation unit 22 smoothes the instantaneous values ​​of the line voltage values ​​Vrs, Vst, and Vtr and the line current values ​​Ir, Is, and It obtained in the first through third states before calculating the first combined resistance value R1, the second combined resistance value R2, and the third combined resistance value R3. Smoothing includes, for example, RMS (root mean square) processing, moving average processing, and primary delay processing.

[0071] The following example shows how the first combined resistance value R1 is calculated using RMS processing. For example, assume that the calculation period for the first combined resistance value R1 is 1 second, and there are n sampling points where "Ir = 0" is determined. If the instantaneous values ​​of Is and Vst at the nth sampling time are "Is = Isn, Vst = Vstn," respectively, the RMS values ​​of Is and Vst for the first through nth sampling times are calculated using the following equations 1 and 2. Calculating the first combined resistance value R1 using "R1 = Vst (rms) / Is (rms)" improves the accuracy of the calculation.

[0072]

Formula 1

[0073]

[0074]

Formula 2

[0075]

[0076] For example, in Figure 2 In the three-phase heater 100 shown, where the three resistors are connected in a delta configuration, the resistance values ​​Rrs, Rst, and Rtr of each phase of the three-phase heater 100 are calculated using Equations 6 to 8 derived from Equations 3 to 5 below. Specifically, when the three resistors are connected in a delta configuration, the calculation unit 22 calculates the resistance values ​​Rrs, Rst, and Rtr of each phase of the three-phase heater 100 without using the current values ​​of each phase. In this case, the acquisition unit 21 is configured, for example, not to acquire the current values ​​of each phase of the three-phase heater 100. Figure 9 The first state of the delta-connected three-phase heater 100 is shown. Figure 10 The second state of the delta-connected three-phase heater 100 is shown. Figure 11 The third state of the delta-connected three-phase heater 100 is shown.

[0077]

Formula 3

[0078]

[0079]

Formula 4

[0080]

[0081]

Formula 5

[0082]

[0083]

Formula 6

[0084]

[0085]

Formula 7

[0086]

[0087]

Formula 8

[0088]

[0089] For example, in Figure 12In the three-phase heater 100 shown, in which the three resistors 101, 102, and 103 are connected in a star configuration, the resistance values ​​Rr, Rs, and Rt of each phase of the three-phase heater 100 are calculated using equations 12 to 14 derived from equations 9 to 11 below. Specifically, when the three resistors 101, 102, and 103 are connected in a star configuration, the calculation unit 22 calculates the resistance values ​​Rr, Rs, and Rt of each phase of the three-phase heater 100 without using the voltage values ​​of each phase. In this case, the acquisition unit 21 is configured not to acquire the voltage value of the neutral point 104 of the three-phase heater 100. Figure 13 The first state of the three-phase heater 100 connected in star configuration is shown. Figure 14 The second state of the three-phase heater 100 connected in star configuration is shown. Figure 15 The third state of the star-connected three-phase heater 100 is shown.

[0090]

Formula 9

[0091]

[0092]

Formula 10

[0093]

[0094]

Formula 11

[0095]

[0096]

Formula 12

[0097]

[0098]

Formula 13

[0099]

[0100]

Formula 14

[0101]

[0102] For example, in Figure 2 In the case where SSR 133 is not provided (i.e., when adjustment unit 130 is composed of two SSRs 131 and 132), the resistance values ​​Rrs, Rst, and Rtr of each phase of three-phase heater 100 are calculated using Equations 17 to 19 derived from Equations 3, 4, and 15, or Equations 20 to 22 derived from Equations 3, 4, and 16. K is the ratio calculated as Vtr / Vrs, and P is the ratio calculated as Vrs / Vst. In this case, acquisition unit 21 is also configured not to acquire the current values ​​of each phase of three-phase heater 100, for example.

[0103]

Formula 15

[0104]

[0105]

Formula 16

[0106]

[0107]

Formula 17

[0108]

[0109]

Formula 18

[0110]

[0111]

Formula 19

[0112]

[0113]

Formula 20

[0114]

[0115]

Formula 21

[0116]

[0117]

Formula 22

[0118]

[0119] For example, in Figure 12 In the case where SSR 133 is not provided (i.e., when adjustment unit 130 is composed of two SSRs 131 and 132), the resistance values ​​Rr, Rs, and Rt of each phase of three-phase heater 100 are calculated using Equations 25 to 27 derived from Equations 9, 10, and 23, or Equations 28 to 30 derived from Equations 9, 10, and 24. K is the ratio calculated as Vtr / Vrs, and P is the ratio calculated as Vrs / Vst. In this case, acquisition unit 21 is also configured not to acquire the voltage value relative to neutral point 104 of three-phase heater 100.

[0120]

Formula 23

[0121]

[0122]

Formula 24

[0123]

[0124]

Formula 25

[0125]

[0126]

Formula 26

[0127]

[0128]

Formula 27

[0129]

[0130]

Formula 28

[0131]

[0132]

Formula 29

[0133]

[0134]

Formula 30

[0135]

[0136] Reference Figure 16 right Figure 2 or Figure 12 The calculation process of the resistance value of each phase of the three-phase heater 100 (an example of the method disclosed in the present invention) will be described. As an example, Figure 6 The processing shown is implemented by the processor 11 executing a predetermined program stored in the storage unit 12 .

[0137] like Figure 16 As shown, after the calculation process of the resistance value of each phase of the three-phase heater 100 is started, initial setting is performed (step S1). The initial setting includes the following settings, for example.

[0138] ･Wiring method of three-phase heater 100 (e.g. delta connection or star connection)

[0139] The number of SSRs or power regulators that make up the regulator 130 (e.g., zero, two, or three)

[0140] ･Resistance value calculation period (e.g. 1 second)

[0141] After initialization, the acquisition unit 21 (e.g., simultaneously) acquires the line voltage values ​​Vrs, Vst, and Vtr and the line current values ​​Ir, Is, and It (step S2). The cycle for acquiring the line voltage values ​​Vrs, Vst, and Vtr and the line current values ​​Ir, Is, and It can be set to a fixed period using a timer interrupt or other means, preferably sufficiently smaller than the power supply cycle. In this case, steps S2 through S5, described below, are executed once during the acquisition period, and steps S6 and S7 are executed once during the resistance calculation period.

[0142] After acquiring the line voltage values ​​Vrs, Vst, Vtr and the line current values ​​Ir, Is, It, the calculation unit 22 determines whether the line voltage values ​​Vrs, Vst, Vtr and the line current values ​​Ir, Is, It for at least two of the first to third states have been acquired (step S3). For example, during the acquisition cycle, each time the line voltage values ​​Vrs, Vst, Vtr and the line current values ​​Ir, Is, It are acquired, the calculation unit 22 classifies the acquired line current values ​​Ir, Is, It into the first to third states. Based on the classification results, it is determined whether the line voltage values ​​Vrs, Vst, Vtr and the line current values ​​Ir, Is, It for at least two states have been acquired. If it is determined that the line voltage values ​​Vrs, Vst, Vtr and the line current values ​​Ir, Is, It for at least two states have not been acquired, the process returns to step S2 and acquires the line voltage values ​​Vrs, Vst, Vtr and the line current values ​​Ir, Is, It at the next acquisition timing.

[0143] If the calculation unit 22 determines that the line voltage values ​​Vrs, Vst, and Vtr and the line current values ​​Ir, Is, and It for at least two states have been acquired, it performs smoothing on the acquired line voltage values ​​Vrs, Vst, and Vtr and the line current values ​​Ir, Is, and It (step S4). For example, the smoothing process targets the data of the line voltage and line current values ​​for at least two states. The smoothing process includes adding a newly sampled value that matches any of the first through third states to the smoothed value for the previous first through third states and performing further smoothing.

[0144] After smoothing the acquired line voltage values ​​Vrs, Vst, and Vtr and the line current values ​​Ir, Is, and It, the calculation unit 22 determines whether the set resistance value calculation cycle has elapsed (step S5). If the set resistance value calculation cycle has elapsed, the calculation unit 22 calculates the resistance value of each phase of the three-phase heater 100 based on the smoothed line voltage values ​​Vrs, Vst, and Vtr and the line current values ​​Ir, Is, and It (step S6).

[0145] After calculating the resistance value of each phase of three-phase heater 100, the calculated resistance value is stored in storage unit 12 (step S7), completing the resistance value calculation process. If it is determined that the set resistance value calculation cycle has not elapsed, the process returns to step S2, and the line voltage values ​​Vrs, Vst, and Vtr and the line current values ​​Ir, Is, and It are acquired at the next acquisition timing.

[0146] According to the method disclosed in the present invention, the following effects can be achieved.

[0147] Generally speaking, in three-phase heaters with three resistors, measuring the phase voltage or current values ​​for each phase can be difficult due to their structure. For example, measuring the phase current values ​​can be difficult in a three-phase heater with three resistors connected in a delta configuration, and measuring the phase voltage values ​​can be difficult in a three-phase heater with three resistors connected in a star configuration. In contrast, the line current values ​​and line voltage values ​​of the three wires connecting the three-phase heater to the three-phase power supply can be measured relatively easily. Therefore, when calculating the resistance values ​​of each phase of a three-phase heater, it is considered appropriate to use the line voltage and line current values.

[0148] In the invention of Patent Document 1, the resistance value of each phase of the three-phase heater is calculated using the line voltage and line current values, as well as the power consumption calculated from the line voltage and line current values. Therefore, the calculation of the resistance value of each phase of the three-phase heater becomes complicated, and sometimes the resistance value of each phase of the three-phase heater cannot be easily calculated.

[0149] The method disclosed herein has the following configuration. This configuration allows calculation of the resistance value of each phase of the three-phase heater 100 based on the line voltage values ​​Vrs, Vst, and Vtr and the line current values ​​Ir, Is, and It. Therefore, calculation of the resistance value of each phase of the three-phase heater 100 can be easily performed. Furthermore, the method disclosed herein can calculate the resistance value of each phase of the three-phase heater 100 using only the instantaneous values ​​of the line voltage values ​​Vrs, Vst, and Vtr and the line current values ​​Ir, Is, and It, or using only smoothed instantaneous values.

[0150] At least two of the line voltage values ​​Vrs between the first electric wire 111 and the second electric wire 112, the line voltage value Vst between the second electric wire 112 and the third electric wire 113, and the line voltage value Vtr between the third electric wire 113 and the first electric wire 111, and the line current values ​​of at least two of the first electric wire 111, the second electric wire 112, and the third electric wire 113 are obtained. The first electric wire 111, the second electric wire 112, and the third electric wire 113 are connected to a three-phase heater 100 including three resistors and a three-phase power supply 120, respectively.

[0151] The resistance value of each phase of the three-phase heater 100 is calculated based on the obtained line voltage values ​​Vrs, Vst, and Vtr and the line current values ​​Ir, Is, and It.

[0152] The line voltage values ​​Vrs, Vst, and Vtr and the line current values ​​Ir, Is, and It are obtained in a first state in which no current flows through only one of the first electric wire 111, the second electric wire 112, and the third electric wire 113, and in a second state in which no current flows through only two of the first electric wire 111, the second electric wire 112, and the third electric wire 113, excluding the electric wire through which no current flows in the first state.

[0153] The method disclosed herein can arbitrarily employ any one or more of the following multiple configurations. Specifically, any one or more of the following multiple configurations can be arbitrarily deleted if included in the embodiments, or added if not. By employing such a configuration, the resistance value of each phase of a three-phase heater can be more easily calculated.

[0154] If one of the three acquired line current values ​​(Ir, Is, and It) is less than a first threshold value and the remaining two line current values ​​are greater than a second threshold value, it is determined that no current is flowing through the electric wire corresponding to the line current value less than the first threshold value. This configuration allows for more accurate calculation of the resistance value of each phase of the three-phase heater.

[0155] When three resistors are connected in a delta configuration, the current value of each phase is not obtained.

[0156] When three resistors are connected in a star configuration, a voltage value with reference to the neutral point 104 is not obtained.

[0157] The state in which no current flows only through the first electric wire 111, the second electric wire 112, and the third electric wire 113, excluding the electric wire that does not flow in the first and second states, is referred to as the third state. The first combined resistance value R1, which represents the combined resistance of the three-phase heater 100 in the first state, the second combined resistance value R2, which represents the combined resistance of the three-phase heater 100 in the second state, and the third combined resistance value R3, which represents the combined resistance of the three-phase heater 100 in the third state, are calculated. The resistance value of each phase of the three-phase heater 100 is calculated based on the first combined resistance value R1, the second combined resistance value R2, and the third combined resistance value R3.

[0158] The first combined resistance value R1, which is the combined resistance value of the three-phase heater 100 in the first state, and the second combined resistance value R2, which is the combined resistance value of the three-phase heater 100 in the second state, are calculated. The resistance value of each phase of the three-phase heater 100 is calculated based on the ratio between the first combined resistance value R1 and the second combined resistance value R2, and the resistance value of each phase of the three-phase heater 100.

[0159] An adjustment unit 130 capable of adjusting the current supplied to the three-phase heater 100 is provided in at least two of the first electric wire 111, the second electric wire 112, and the third electric wire 113. The adjustment unit 130 is configured to be capable of on / off control and, when switched on, supplies current to the three-phase heater 100. The line voltage values ​​Vrs, Vst, and Vtr and the line current values ​​Ir, Is, and It are obtained for a predetermined period immediately before the adjustment unit 130 switches from on to off.

[0160] The adjustment unit 130 includes at least two bidirectional thyristor type solid-state relays.

[0161] After smoothing the acquired line voltage values ​​Vrs, Vst, and Vtr and the line current values ​​Ir, Is, and It, the resistance value of each phase of the three-phase heater 100 is calculated.

[0162] The method of the present disclosure can be executed by a computer. That is, the present disclosure includes a program for causing a computer to execute the method of the present disclosure, and a computer-readable storage medium storing the program for causing a computer to execute the method of the present disclosure.

[0163] According to the device 1, the following effects can be achieved.

[0164] The device 1 includes an acquisition unit 21 and a calculation unit 22. The acquisition unit 21 is configured to acquire at least two of the line voltage values ​​Vrs of the first and second electric wires 111 and 112, the line voltage value Vst of the second and third electric wires 112 and 113, and the line voltage value Vtr of the third electric wire 113 and the first electric wire 111, as well as the line current values ​​of at least two of the first, second, and third electric wires 111, 112, and 113. The first, second, and third electric wires 111, 112, and 113 are connected to a three-phase heater 100 including three resistors and a three-phase power supply 120, respectively. The calculation unit 22 is configured to calculate the resistance value of each phase of the three-phase heater 100 based on the acquired line voltage values ​​Vrs, Vst, and Vtr and the line current values ​​Ir, Is, and It. The acquisition unit 21 is configured to acquire the line voltage values ​​Vrs, Vst, and Vtr and the line current values ​​Ir, Is, and It in a first state in which no current flows through only one of the first electric wire 111, the second electric wire 112, and the third electric wire 113, and in a second state in which no current flows through only two of the first electric wire 111, the second electric wire 112, and the third electric wire 113, excluding the electric wire that did not flow in the first state. This configuration allows the resistance value of each phase of the three-phase heater 100 to be calculated based on the line voltage values ​​Vrs, Vst, and Vtr and the line current values ​​Ir, Is, and It, making it easy to calculate the resistance value of each phase of the three-phase heater 100. Furthermore, the device 1 can calculate the resistance value of each phase of the three-phase heater 100 using only the instantaneous values ​​of the line voltage values ​​Vrs, Vst, and Vtr and the line current values ​​Ir, Is, and It, or using only smoothed values ​​of the instantaneous values.

[0165] The method and apparatus 1 of the present disclosure can be configured as follows.

[0166] Whether or not current is not flowing in the electric wire is not limited to being determined using the first and second thresholds. For example, when the line current value detected by the current measuring circuit 140 is zero, it may be determined that current is not flowing in the electric wire.

[0167] The acquisition unit 21 may be configured to acquire the line voltage values ​​Vrs, Vst, and Vtr and the line current values ​​Ir, Is, and It via a communication circuit or a communication module for transmitting and receiving data with an external device such as a server.

[0168] The calculation unit 22 may be configured to use any formula capable of calculating the resistance value of each phase of the three-phase heater 100 without being limited to the above formula.

[0169] The calculation unit 22 may be configured to calculate the resistance value of each phase of the three-phase heater without smoothing the acquired line voltage values ​​Vrs, Vst, Vtr and line current values ​​Ir, Is, It.

[0170] The line voltage values ​​and line current values ​​in the first state and the second state are not limited to being detected by providing the adjustment unit 130 , and may be detected by other methods.

[0171] The line current value and the line voltage value are not limited to being measured by the current measuring circuit 140 and the voltage measuring circuit 150 , but may be measured by any configuration capable of measuring the line current value or the line voltage value.

[0172] While various embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, various aspects of the present disclosure will now be described.

[0173] The method of the first embodiment of the present disclosure obtains at least two of the line-to-line voltage values ​​of a first electric wire 111, a second electric wire 112, and a third electric wire 113, which respectively connect a three-phase power supply 120 to a three-phase heater 100 including three resistors: the line-to-line voltage values ​​of the first electric wire 111 and the second electric wire 112, the line-to-line voltage values ​​of the second electric wire 112 and the third electric wire 113, and the line-to-line voltage values ​​of the third electric wire 113 and the first electric wire 111; and the line current values ​​of at least two of the first electric wire 111, the second electric wire 112, and the third electric wire 113, and calculates the resistance value of each phase of the three-phase heater 100 based on the obtained line-to-line voltage values ​​and the line current values. The line-to-line voltage values ​​and the line current values ​​are obtained in a first state in which no current flows only through the first electric wire 111 and a second state in which no current flows only through the second electric wire 112.

[0174] The method of the second aspect of the present disclosure is such that, in the method of the first aspect, when one of the three line current values ​​obtained is smaller than the first threshold value and the other two line current values ​​are larger than the second threshold value, it is determined that no current flows through the electric wire corresponding to the line current value smaller than the first threshold value.

[0175] The method of the third aspect of the present disclosure is the method of the first aspect or the second aspect, wherein when the three resistors are delta-connected, the current value of each phase is not acquired.

[0176] The method of the fourth aspect of the present disclosure is the method of the first aspect or the second aspect, in which, when the three resistors are star-connected, the voltage value with reference to the neutral point 104 is not acquired.

[0177] The method of the fifth mode of the present disclosure is any one of the methods of the first to fourth modes. When the state in which no current flows only in the third electric wire 113 is set to the third state, the synthetic resistance value of the three-phase heater 100 in the first state, i.e., the first synthetic resistance value, the synthetic resistance value of the three-phase heater 100 in the second state, i.e., the second synthetic resistance value, and the synthetic resistance value of the three-phase heater 100 in the third state, i.e., the third synthetic resistance value, are calculated, and the resistance value of each phase of the three-phase heater 100 is calculated based on the first synthetic resistance value, the second synthetic resistance value, and the third synthetic resistance value.

[0178] The method of the sixth mode of the present disclosure calculates the synthetic resistance value of the three-phase heater 100 in the first state, i.e., the first synthetic resistance value, and the synthetic resistance value of the three-phase heater 100 in the second state, i.e., the second synthetic resistance value, in any one of the methods in the first to fourth modes, and calculates the resistance value of each phase of the three-phase heater 100 based on the ratio of the first synthetic resistance value, the second synthetic resistance value, and the resistance value of each phase of the three-phase heater 100.

[0179] In the method of the seventh embodiment of the present disclosure, in any one of the methods of the first to sixth embodiments, an adjustment unit 130 capable of adjusting the current supplied to the three-phase heater 100 is provided in at least any two of the first electric wire 111, the second electric wire 112 and the third electric wire 113, and the adjustment unit 130 is configured to be capable of on-off control and to supply current to the three-phase heater 100 by being turned on.

[0180] According to an eighth aspect of the present disclosure, in the seventh aspect, the adjustment unit 130 includes at least two bidirectional thyristor type solid-state relays.

[0181] A method according to a ninth aspect of the present disclosure is the method according to any one of the first to eighth aspects, wherein the resistance value is calculated after smoothing the acquired line voltage value and line current value.

[0182] The tenth embodiment of the present disclosure is a program that causes a computer to execute the following method: obtaining line-to-line voltage values ​​of a first electric wire 111, a second electric wire 112, and a third electric wire 113, which respectively connect a three-phase power supply 120 to a three-phase heater 100 including three resistors, at least two of the line-to-line voltage values ​​of the first electric wire 111 and the second electric wire 112, the line-to-line voltage value of the second electric wire 112 and the third electric wire 113, and the line-to-line voltage value of the third electric wire 113 and the first electric wire 111, and line current values ​​of at least two of the first electric wire 111, the second electric wire 112, and the third electric wire 113, and calculating the resistance value of each phase of the three-phase heater 100 based on the obtained line-to-line voltage values ​​and the line current values. In this method, the line-to-line voltage values ​​and the line current values ​​are obtained in a first state in which no current flows only through the first electric wire 111 and a second state in which no current flows only through the second electric wire 112.

[0183] The device 1 of the 11th embodiment of the present disclosure includes: an acquisition unit 21 configured to acquire at least two of the line voltage values ​​of the first electric wire 111, the second electric wire 112, and the third electric wire 113, which respectively connect the three-phase power supply 120 and the three-phase heater 100 including three resistors, among the line voltage values ​​of the first electric wire 111 and the second electric wire 112, the line voltage value of the second electric wire 112 and the third electric wire 113, and the line voltage value of the third electric wire 113 and the first electric wire 111. values ​​and line current values ​​of at least any two of the first electric wire 111, the second electric wire 112 and the third electric wire 113; and a calculation unit 22, which is configured to calculate the resistance value of each phase of the three-phase heater 100 based on the obtained line-to-line voltage value and the line current value, and the acquisition unit 21 is configured to acquire the line-to-line voltage value and the line current value in a first state in which no current flows only in the first electric wire 111 and in a second state in which no current flows only in the second electric wire 112.

[0184] By appropriately combining any of the various embodiments or modifications described above, the effects possessed by each can be exerted. In addition, it is possible to combine the embodiments with each other, or to combine the embodiments with each other, or to combine the embodiments and the embodiments, and it is also possible to combine the features of different embodiments or embodiments with each other.

[0185] While the present disclosure has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, various modifications and variations will be apparent to those skilled in the art and should be understood to be included therein without departing from the scope of the present disclosure as defined by the appended claims.

[0186] Industrial applicability

[0187] The present disclosure can be applied to, for example, a device for determining abnormality in a three-phase heater.

[0188] Label Description

[0189] 1 device

[0190] 11 Processor

[0191] 12 Storage

[0192] 21 Acquisition Department

[0193] 22 Computing Department

[0194] 100 three-phase heater

[0195] 101 1st resistor

[0196] 102 2nd resistor

[0197] 103 3rd resistor

[0198] 104 Neutral Point

[0199] 111 First Electric Wire

[0200] 112 Second Wire

[0201] 113 3rd Wire

[0202] 120 three-phase power supply

[0203] 130 Adjustment Department

[0204] 140 Current Measuring Circuit

[0205] 150 Voltage measurement circuit

Claims

1. A method for obtaining, for each of a first electric wire, a second electric wire, and a third electric wire connecting a three-phase power supply and a three-phase heater including three resistors, at least two of the line-to-line voltage values ​​of the first electric wire and the second electric wire, the line-to-line voltage value of the second electric wire and the third electric wire, and the line-to-line voltage value of the third electric wire and the first electric wire, and line current values ​​of at least two of the first electric wire, the second electric wire, and the third electric wire, respectively. The resistance value of each phase of the three-phase heater is calculated based on the obtained line voltage value and the line current value, wherein: The line voltage value and the line current value are acquired in a first state in which no current flows only in the first electric wire and a second state in which no current flows only in the second electric wire.

2. The method according to claim 1, wherein When one of the three acquired line current values ​​is smaller than a first threshold and the remaining two line current values ​​are larger than a second threshold, it is determined that no current flows through the electric wire corresponding to the line current value smaller than the first threshold.

3. The method according to claim 1 or 2, wherein: When the three resistors are connected in a delta configuration, the current value of each phase is not obtained.

4. The method according to claim 1 or 2, wherein: When the three resistors are connected in a star configuration, a voltage value with respect to the neutral point is not obtained.

5. The method according to claim 1 or 2, wherein: When a state in which no current flows only in the third electric wire is set as a third state, calculating a first combined resistance value of the three-phase heater in the first state, a second combined resistance value of the three-phase heater in the second state, and a third combined resistance value of the three-phase heater in the third state; The resistance value of each phase of the three-phase heater is calculated based on the first combined resistance value, the second combined resistance value, and the third combined resistance value.

6. The method according to claim 1 or 2, wherein: calculating a first combined resistance value, which is a combined resistance value of the three-phase heater in the first state, and a second combined resistance value, which is a combined resistance value of the three-phase heater in the second state; The resistance value of each phase of the three-phase heater is calculated based on a ratio among the first combined resistance value, the second combined resistance value, and the resistance value of each phase of the three-phase heater.

7. The method according to claim 1 or 2, wherein: At least any two of the first electric wire, the second electric wire, and the third electric wire are provided with an adjustment unit capable of adjusting the current supplied to the three-phase heater. The adjustment unit is configured to be capable of on / off control, and supplies current to the three-phase heater by being turned on.

8. The method according to claim 7, wherein: The adjustment unit includes at least two bidirectional thyristor type solid-state relays.

9. The method according to claim 1 or 2, wherein: The resistance value is calculated after smoothing the acquired line voltage value and line current value.

10. A program causing a computer to execute the following method: obtaining at least any two of the line-to-line voltage values ​​of a first electric wire, a second electric wire, and a third electric wire, which respectively connect a three-phase power supply and a three-phase heater including three resistors, of the first electric wire and the second electric wire, the second electric wire and the third electric wire, and the third electric wire and the first electric wire, and obtaining line current values ​​of at least any two of the first electric wire, the second electric wire, and the third electric wire; calculating the resistance value of each phase of the three-phase heater based on the obtained line voltage value and the line current value, In this method, the line voltage value and the line current value are acquired in a first state in which no current flows only in the first electric wire and a second state in which no current flows only in the second electric wire.

11. A device comprising: an acquisition unit configured to acquire at least any two of line-to-line voltage values ​​of a first electric wire, a second electric wire, and a third electric wire, respectively connecting a three-phase power supply and a three-phase heater including three resistors, of a first electric wire and a second electric wire, a line-to-line voltage value of the second electric wire and the third electric wire, and a line-to-line voltage value of the third electric wire and the first electric wire, and line current values ​​of at least any two of the first electric wire, the second electric wire, and the third electric wire; and a calculation unit configured to calculate a resistance value of each phase of the three-phase heater based on the acquired line voltage value and the line current value; The acquisition unit is configured to acquire the line voltage value and the line current value in a first state in which no current flows only through the first electric wire and a second state in which no current flows only through the second electric wire.

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