JP6614265B2 - Judgment method of current detector installation state - Google Patents

Description

  The present disclosure relates to the determination of the mounting state of a current detector.

  In Patent Document 1 described below, the power supply voltage phase is compared with the waveform pattern of the current detected by the current detector, and thereby the connection state of the current detector is determined.

JP 2001-91600 A

  Patent Document 1 does not explain the case where the current is unbalanced. With reference to FIG. 4 and FIG. 5 in Patent Document 1, there is no description about the case where the current exhibits a waveform other than the so-called 120-degree conduction waveform.

  In the present disclosure, it is not assumed that the current is balanced and / or the current exhibits a 120-degree conduction waveform, and the current detector is attached and is determined.

  A first current detector (CT1) and a second current detector with respect to three power lines (Lr, Ls, Lt) for inputting a three-phase current (Ir, Is, It) to the power converter (100) A method for determining the state in which (CT2) is attached is disclosed.

The method includes (i) a first condition: an instantaneous value at an appropriate timing with respect to a first value (| i1 |) that is an absolute value of a first current (i1) detected by the first current detector or the first value. The average value of one value (| i1 | ^) or the effective value or peak value of the first value and the second value (| i2) that is the absolute value of the second current (i2) detected by the second current detector |) Is an instantaneous value at an appropriate timing or an average value (| i2 | ^) of the second value or an effective value or a peak value of the second value from the positive first threshold (ε). Is larger (S11), (ii) Second condition: appropriate for the third value (| i3 |) which is the absolute value of the difference between the first value (| i1 |) and the second value (| i2 |) the instantaneous value or the average value of the third value at timing (| i3 | ^) or before When the effective value or peak value of the third value is smaller than the positive second threshold value (δ) (S12), any of the first current detector and the second current detector is satisfied. This is a method for determining the state of attachment of the current detector, in which it is determined that the terminal is attached to one power supply line (D3).

  For example, when the first condition is satisfied and the second condition is not satisfied, the first current detector (CT1) is attached to the first power supply line (Lr), and the second current detector (CT2). Determines that it is attached to the second power supply line (Lt) different from the first power supply line (D0).

For example, the first condition is not satisfied and the instantaneous value or the average value (| i1 | ^) of the first value or the first value at an appropriate timing for the first value (| i1 |) When the effective value is smaller than the positive third threshold (ε ′), it is determined that the first current detector (CT1) is not attached to any of the power supply lines (D1).

For example, the first condition is not satisfied and the instantaneous value or the average value (| i2 | ^) of the second value or the second value at an appropriate timing for the second value (| i2 |) When the effective value is smaller than the positive fourth threshold value (ε ″), it is determined that the second current detector (CT2) is not attached to any of the power supply lines (D2).

  According to the method of the present disclosure, it is not assumed that the current is balanced and / or the current exhibits a waveform of 120-degree conduction, and the attachment state of the current detector is determined.

It is a circuit diagram which illustrates the composition which can apply the judgment method concerning a 1st embodiment and a 2nd embodiment. It is a graph which shows the waveform of an alternating voltage and an electric current. It is a graph which shows the waveform of an alternating voltage and an electric current. It is a graph which shows the waveform of alternating voltage and an electric current. It is a graph explaining operation | movement of 1st Embodiment. It is a graph explaining operation | movement of 1st Embodiment. It is a graph explaining operation | movement of 1st Embodiment. It is a graph explaining operation | movement of 1st Embodiment. It is a graph explaining operation | movement of 1st Embodiment. It is a graph explaining operation | movement of 1st Embodiment. It is a flowchart explaining the judgment routine which is an example of operation | movement of 1st Embodiment. It is a block diagram which illustrates the composition of a 2nd embodiment. It is a graph explaining operation | movement of 2nd Embodiment. It is a graph explaining operation | movement of 2nd Embodiment. It is a flowchart explaining the judgment routine which is an example of operation | movement of 2nd Embodiment. It is a flowchart explaining the attachment state judgment processing of 2nd Embodiment. It is a flowchart explaining the attachment state judgment processing of 2nd Embodiment. It is a graph explaining operation | movement of 2nd Embodiment. It is a graph explaining operation | movement of 2nd Embodiment. It is a graph explaining operation | movement of 2nd Embodiment.

  FIG. 1 is a circuit diagram illustrating a configuration to which the determination method according to the first embodiment and the second embodiment can be applied. The configuration includes a power converter 100 and an active filter 200.

  Power converter 100 includes a pair of DC buses LH and LL, rectifier circuit 2, and inverter 4. The active filter 200 is a parallel type active filter and includes an inverter 21 and a capacitor 22.

  The power converter 100 and the active filter 200 are all connected to the three-phase power source 1 via three power lines Lr, Ls, and Lt. Three-phase AC voltages Vr, Vs, and Vt with a period T output from the power source 1 are applied to the power lines Lr, Ls, and Lt, respectively. In the following, for the sake of convenience, a case will be described in which the AC voltage Vr advances by T / 3 from the AC voltage Vs, and the AC voltage Vs advances by T / 3 from the AC voltage Vt.

  The power converter 100 includes, for example, a noise filter 5 on the power supply lines Lr, Ls, and Lt, and the rectifier circuit 2 is connected to the power supply 1 via the noise filter 5.

  The inverter 21 converts the current input from the capacitor 22 into a three-phase compensation current Ia and outputs it. The active filter 200 further includes a grid reactor 26. The interconnected reactor 26 is realized by a reactor for three phases. The inverter 21 is connected to the power supply lines Lr, Ls, and Lt between the power supply 1 and the rectifier circuit 2 via the interconnection reactor 26.

  For example, the noise filter 5 is provided on the side closer to the power supply 1 than the position where the active filter 200 is connected to the power supply lines Lr, Ls, Lt (in the above example, the inverter 21 via the interconnection reactor 26).

  A three-phase power source current Ih is output from the power source 1 to the power source lines Lr, Ls, and Lt. A compensation current Ia is output from the active filter 200 to the power supply lines Lr, Ls, and Lt. Therefore, a three-phase load current Ii that is the sum of the power supply current Ih and the compensation current Ia is input to the rectifier circuit 2. The positive direction of the load current Ii is a direction toward the rectifier circuit 2.

  Hereinafter, for convenience of explanation, the load current Ii may be described separately from the currents Ir, Is, It flowing through the power supply lines Lr, Ls, Lt, respectively. Similarly, the compensation current Ia may be described separately from the currents Iu, Iv, and Iw flowing through the power supply lines Lr, Ls, and Lt.

  The rectifier circuit 2 applies a DC voltage obtained by rectifying the AC voltages Vr, Vs, and Vt to the DC buses LH and LL. The DC bus LH has a higher potential than the DC bus LL. The rectifier circuit 2 is realized by a diode bridge, for example.

  Two current detectors CT1 and CT2 are provided on the power supply lines Lr, Ls, and Lt. Current detectors CT1 and CT2 output their detection results as currents i1 and i2, respectively.

  FIG. 1 illustrates a state where the current detectors CT1 and CT2 are attached to the power supply lines Lr and Lt, respectively. In this case, the currents i1 and i2 correspond to the currents Ir and It, respectively.

  However, as will be described later, both current detectors CT1 and CT2 are attached to one power supply line, or at least one of current detectors CT1 and CT2 is not attached to any power supply line. Is also envisaged.

  The power converter 100 further includes a smoothing filter 6 provided on the DC buses LH and LL. The smoothing filter 6 is, for example, a choke input type LC filter, and includes an inductor L6 and a capacitor C6. The smoothing filter 6 smoothes the DC voltage applied to the DC buses LH and LL by the rectifier circuit 2 and inputs the smoothed DC voltage to the inverter 4.

  The inverter 4 converts the DC voltage into other AC voltages Vu, Vv, Vw and outputs them. For example, the inverter 4 applies AC voltages Vu, Vv, and Vw to the load 9 connected to the power converter 100.

  The operation of the inverter 4 is controlled by the inverter control unit 7. For example, in the inverter 4, three current paths each having an upper arm switching element and a lower arm switching element are connected in parallel between the DC buses LH and LL. The inverter control unit 7 supplies the inverter 4 with a drive signal Gi that controls opening and closing of the three pairs of upper arm switching element and lower arm switching element. Since the technique by which the inverter control unit 7 generates the drive signal Gi is well known, further detailed description is omitted here.

  The active filter 200 further includes voltage detectors 24, 28 and 29. The voltage detector 24 detects the voltage Vdc. The voltage detectors 28 and 29 detect line voltages Vrs and Vst, respectively. The voltage Vdc is a voltage supported by the capacitor 22. The line voltage Vrs is an AC voltage Vs based on the AC voltage Vr. The line voltage Vst is an AC voltage Vt based on the AC voltage Vs.

  The active filter 200 further includes current detectors CT3 and CT4. Current detectors CT3 and CT4 detect currents Iu and Iw, respectively.

  Since the configuration itself of the voltage detectors 24, 28, 29 and the current detectors CT1, CT2, CT3, CT4 can be realized by a known technique, the description thereof is omitted here.

  The active filter 200 further includes zero cross detectors 25rs and 25st. The zero cross detectors 25rs and 25st detect the zero crosses of the line voltages Vrs and Vst, respectively, for example, when the polarity changes from negative to positive (and / or when the polarity changes from positive to negative), and detect the time as a zero cross signal. Output as Xrs, Xst. The functions of the zero-cross detectors 25rs and 25st are known, for example, from Patent Document 1.

  The operation of the active filter 200 is controlled by the active filter control unit 27. For example, in the inverter 21, three current paths each having an upper arm switching element and a lower arm switching element are connected in parallel between the DC buses LH and LL. The active filter control unit 27 supplies a drive signal Ga for controlling opening and closing of the three pairs of upper arm switching element and lower arm switching element to the inverter 21 and maintains the voltage Vdc.

  The currents Iu, Iv, and Iw are obtained by driving the inverter 21 with the drive signal Ga. The drive signal Ga includes zero-cross signals Xrs and Xst, two of the voltage Vdc and the load current Ii (for example, current Ir and Is), and two of the compensation current Ia (for example, currents Iu and Iw) (more specifically, Is generated based on these values (the same applies hereinafter). Since the technique itself by which the active filter control unit 27 generates the drive signal Ga is well known, further detailed description is omitted here.

  However, it is obvious that the drive signal Ga cannot be obtained correctly unless the currents Ir and Is are detected. Therefore, it is desirable to determine whether one of the current detectors CT1 and CT2 is attached to any one of the power supply lines Lr, Ls, and Lt. Of course, the situation where such a determination is desirable is not limited to the situation where the active filter 200 is employed.

  2 to 4 are graphs showing waveforms of the AC voltage Vr and the currents Ir, Is, It. In the graph, time (unit is second) is adopted on the horizontal axis, and arbitrary unit is adopted on the vertical axis. For example, the unit of the vertical axis of the AC voltage Vr is volts (V). For example, the unit of the vertical axis of the currents Ir, Is, It is common, for example, ampere (A). The phase will be described on the basis that the phase when the AC voltage Vr transitions from negative to positive is used as a reference, and the cycle T of the AC voltage Vr corresponds to a phase of 360 degrees. Hereinafter, the unit and phase of voltage and current are similarly adopted.

  FIG. 2 illustrates a case where the currents Ir, Is, It are in a three-phase balanced state and the load 9 consumes its rated power. The current Ir is exemplified by a so-called 120-degree conduction state in which the current Ir flows in a 120-degree section that is positive and negative with respect to the positive and negative of the AC voltage Vr. The current Is is delayed by 120 degrees from the current Ir, the current It is delayed by 120 degrees from the current Is, and both currents are energized by 120 degrees.

  As shown in FIG. 2, when the currents Ir, Is, It are in a 120-degree energization state, it is determined from the zero cross signals Xrs, Xst that the current detectors CT1, CT2 are normally attached. For example, this is performed by knowing the phase of the AC voltage Vr (for example, Patent Document 1).

  FIG. 3 exemplifies a case where the current Ir, Is, It is in a three-phase equilibrium state, but power lower than the rated power is consumed by the load 9. The waveform of the current Ir in FIG. 3 is the same as that in FIG. 2 in that the positive / negative of the current Ir corresponds to the positive / negative of the AC voltage Vr. However, the amplitudes of the currents Ir, Is, It shown in FIG. 3 are smaller than those shown in FIG.

  FIG. 4 shows that the currents Ir, Is and It are in a three-phase unbalanced state (the T phase of the AC voltage is 100/97 with respect to the R and S phases), and power lower than the rated power is consumed by the load 9. An example is given.

<First Embodiment>
In the first embodiment, it is not assumed that the current is balanced and that the current exhibits a 120-degree conduction waveform, and the attachment state of the current detector is determined.

  5 to 10 are graphs for explaining the operation of the first embodiment. The graphs show AC voltage Vr, absolute values | i1 |, | i2 |, | i3 |, and average values | i1 | ^, The waveform of | i2 | ^, | i3 | ^ (indicated by the overline in place of the symbol "^") is shown.

  The absolute values | i1 | and | i2 | are the absolute values of the currents i1 and i2, respectively. The absolute value | i3 | is the absolute value of the difference between the absolute values | i1 | and | i2 |. The average value | i3 | ^ is the average value of the absolute values | i3 |, and does not always match the absolute value of the difference between the average values | i1 | ^ and | i2 | ^.

  In any of FIGS. 5 to 10, the average values | i1 | ^, | i2 | ^, | i3 | ^ are shown to take almost constant values.

  5 to 7 exemplify a case where the currents Ir, Is, and It are in a three-phase balanced state, but power lower than the rated power is consumed by the load 9. Although not shown in FIGS. 5 to 7, this corresponds to the case where currents Ir, Is, and It having the waveforms shown in FIG. 3 are flowing.

  8 to 10 show that the currents Ir, Is, It are in a three-phase non-equilibrium state (here, the case where the T phase is 100/97 with respect to the R and S phases is exemplified) and the current is more than the rated power. The case where low electric power is consumed with the load 9 is illustrated. Although not shown in FIGS. 8 to 10, this corresponds to the case where currents Ir, Is, It having the waveform shown in FIG. 4 are flowing.

  5 and 8 illustrate a case where the current detectors CT1 and CT2 are normally attached to the power supply lines Lr and Lt, respectively.

  6 and 9, the current detector CT1 is normally attached to the power supply line Lr here, but the current detector CT2 is not attached to any of the power supply lines Lr, Ls, and Lt (current detector CT2 is detached without being attached: Therefore, normal attachment is not performed: the case where it is hereinafter referred to as “disconnected state” is exemplified. 6 and 9, the absolute value | i2 | and the average value | i2 | ^ are almost 0.

  7 and 10 have the current detectors CT1 and CT2 attached, but overlapped (therefore, normal attachment has not been performed: hereinafter, tentatively referred to as “overlap attachment”), both of which are power lines. The case where it attaches to Lr is illustrated. 7 and 10, the absolute value | i3 | and the average value | i3 | ^ both have almost the value 0.

  FIG. 11 is a flowchart illustrating a determination routine that is an example of the operation of the first embodiment. The determination routine is an interrupt process for a main routine (not shown), for example, and is started by the interrupt process, and the process returns to the main routine when the determination routine ends. The determination routine is performed by the active filter control unit 27 or the inverter control unit 7 together with the main routine, for example. FIG. 1 illustrates a case where the values of the currents i1 and i2 are given to the active filter control unit 27. In this case, the determination routine can be performed in the active filter control unit 27.

  After the determination routine is started, it is determined in step S11 whether or not the absolute values | i1 | and | i2 | are both greater than the positive first threshold value ε.

  Referring to FIGS. 5 to 10, when the current detectors CT <b> 1, CT <b> 2 consumes a small amount of power at the load 9, for example, the AC voltage Vr regardless of whether or not three-phase equilibrium is obtained. Are 90 degrees, 180 degrees, 270 degrees, and 360 degrees, the absolute values | i1 | and | i2 | are zero. Therefore, it is not desirable to execute the steps of the determination routine using the absolute values | i1 | and | i2 | only at these times from the viewpoint of determining the distinction between normal attachment, disengaged state, and duplicate attachment. . From this viewpoint, when the determination routine is performed using the instantaneous values of the absolute values | i1 | and | i2 |, the timing for obtaining the instantaneous values should be set appropriately, for example, at a phase around 45 degrees or 135 degrees. It is desirable to use absolute values | i1 | and | i2 |. This is because the amplitudes of currents Ir, Is, It are close to their maximum values in these phases with reference to FIGS.

  In all steps of the determination routine, instead of the absolute values | i1 |, | i2 |, | i3 |, their average values | i1 | ^, | i2 | ^, | i3 | ^ may be adopted. Alternatively, the effective value or peak value of absolute values | i1 |, | i2 |, | i3 | By adopting these values, it is less necessary to select the timing for obtaining the absolute values | i1 | and | i2 | than when using the instantaneous values of the absolute values | i1 | and | i2 |.

  Of course, for example, the timing may be set appropriately, and each step may be determined using the instantaneous values of the absolute values | i1 | and | i2 |.

  In the determination routine shown in FIG. 11, the case where absolute values | i1 |, | i2 |, | i3 | are used as an example, but in FIGS. 5 to 10, absolute values | i1 |, | i2 |, In addition to | i3 |, average values | i1 | ^, | i2 | ^, and | i3 | ^ are also shown.

  If the current detectors CT1 and CT2 are disconnected, the currents i1 and i2 are ideally zero at any time. Therefore, the first threshold value ε is a threshold value for determining whether or not the current detectors CT1 and CT2 are in a disconnected state. Therefore, the value may be set larger than the minimum value at which the current detectors CT1 and CT2 can detect a current, noise applied to the power supply lines Lr, Ls, and Lt.

  If the determination in step S11 is affirmative, that is, if it is determined that both of the absolute values | i1 | and | i2 | are larger than the positive first threshold value ε, the current detectors CT1 and CT2 are both in the disconnected state. Equivalent to not. FIG. 5, FIG. 7, FIG. 8, and FIG. 10 illustrate this case. In this case, step S12 is executed ("Yes" route from step S11 to step S12).

  In step S12, it is determined whether or not the absolute value | i3 | is smaller than the positive second threshold δ.

  As long as the current detectors CT1 and CT2 detect the same current, the currents i1 and i2 are ideally equal at any time. Therefore, the second threshold δ is a threshold for determining whether or not the current detectors CT1 and CT2 detect the same current. The value may be set larger than the minimum value at which the current detectors CT1, CT2 can detect a current, noise applied to the power supply lines Lr, Ls, Lt, or the like.

  If the determination in step S12 is affirmative, that is, if it is determined that the absolute value | i3 | is smaller than the positive second threshold δ, this corresponds to the current detectors CT1 and CT2 detecting the same current. 7 and 10 illustrate this case. Therefore, the determination D3 that the duplicate attachment is performed is performed ("Yes" route from the step S12 to the determination D3).

  When a negative determination is made in step S12, that is, when the absolute value | i3 | is determined to be greater than or equal to the positive second threshold value δ, this corresponds to the current detectors CT1 and CT2 detecting different currents. FIG. 5 and FIG. 8 illustrate this case. Therefore, determination D0 that normal attachment is performed is performed ("No" route from step S12 to determination D0).

  If negative determination is made in step S11, that is, if any one of the absolute values | i1 | and | i2 | is less than or equal to the first threshold value ε, one or both of the current detectors CT1 and CT2 are in a disconnected state. It corresponds to a certain thing. 6 and 9 correspond to this case. More specifically, both FIG. 6 and FIG. 9 illustrate the case where only the current detector CT2 is in the disconnected state.

  If a negative determination is made in step S11, step S13 is executed ("No" route from step S11 to step S13). In step S13, it is determined whether or not the absolute value | i1 | is equal to or less than the positive first threshold value ε.

  If the current detector CT1 is disconnected, the current i1 is ideally zero at any time. Therefore, instead of the determination, it may be determined whether or not the absolute value | i1 | is smaller than the positive third threshold ε ′.

  If the determination result in step S13 is affirmative ("Yes" route from step S13), this corresponds to the current detector CT1 being in a disconnected state. Therefore, determination D1 (denoted as “CT1 detachment” in the drawing) that the current detector CT1 is in a disconnected state is performed.

  Even if the determination result of step S13 is negative ("No" route from step S13), even if the determination result of step S13 is affirmative and determination D1 is performed, step S14 is Executed. In step S14, it is determined whether or not the absolute value | i2 | is equal to or less than the positive first threshold value ε.

  If the current detector CT2 is disconnected, the current i2 is ideally zero at any time. Therefore, instead of the determination, it may be determined whether or not the absolute value | i2 | is smaller than the positive fourth threshold value ε ″.

  If the determination result in step S14 is affirmative ("Yes" route from step S14), this corresponds to the current detector CT2 being in a disconnected state. Therefore, judgment D2 (denoted as “CT2 off” in the figure) that the current detector CT2 is in the off state is performed. 6 and 9 illustrate this case.

  In the determination routine of FIG. 11, at least one of determinations D1 and D2, either determination D0 or determination D3 is made, and the process returns to the main routine. Such determinations D0 to D3 are used for controlling the active filter 200 by the active filter control unit 27, for example.

The determination routine can be summarized as follows. The determination routine determines whether the current detectors CT1 and CT2 are attached to the power supply lines Lr, Ls, and Lt that input the three-phase currents Ir, Is, and It to the power converter 100. The decision routine uses the following two conditions:
(I) First condition “both the absolute value | i1 | of the current i1 detected by the current detector CT1 and the absolute value | i2 | of the current i2 detected by the current detector CT2 are positive Greater than one threshold ε (corresponding to step S11) ";
(Ii) The second condition “the absolute value | i3 | = || i1 | − | i2 || of the difference between the absolute value | i1 | and the absolute value | i2 | is smaller than the positive second threshold δ (step Corresponding to S12). "

  When both the first condition and the second condition are satisfied, it is determined that both of the current detectors CT1 and CT2 are attached to one power supply line (corresponding to determination D3).

  When the first condition is satisfied and the second condition is not satisfied, it is determined that the current detectors CT1 and CT2 are attached to two different power supply lines (corresponding to determination D0). According to FIGS. 3, 5 and 8, the currents i1 and i2 measure the currents Ir and It, respectively. The current detector CT1 is attached to the power supply line Lr, and the current detector CT2 It is determined that it is attached to the power supply line Lt (different from the line Lr).

  When the first condition is not satisfied and the absolute value | i1 | is smaller than the positive third threshold ε ′ (for example, equal to or less than the first threshold ε), the current detector CT1 is connected to the power supply lines Lr, Ls, and Lt. It is determined that neither is attached (corresponding to determination D1).

  When the first condition is not satisfied and the absolute value | i2 | is smaller than the positive fourth threshold value ε ″ (for example, equal to or less than the first threshold value ε), the current detector CT2 is connected to the power supply lines Lr, Ls, and Lt. It is determined that neither is attached (corresponds to determination D2).

  In these determination routines, instead of the absolute values | i1 |, | i2 |, | i3 |, the respective average values | i1 | ^, | i2 | ^, | i3 | ^, or the respective effective values or peak values. May be adopted. In this case, it is desirable from the viewpoint that it is less necessary to consider the detection timing of the currents i1 and i2 compared to the case where the instantaneous values of the absolute values | i1 |, | i2 |, and | i3 | are used.

<Second Embodiment>
FIG. 12 is a block diagram illustrating the configuration of the attachment determination unit 270 employed when executing the second determination of the attachment state of the current detector. The attachment determination unit 270 can be provided in the active filter control unit 27, for example. Moreover, you may provide in the inverter control part 7. FIG.

  In the example of FIG. 12, the attachment determination unit 270 includes a threshold generation circuit 271, comparators 272 and 276, a mode determination circuit 273, a counter control circuit 274, and counter groups 2751 and 2752.

  The threshold value generation circuit 271 receives the values of currents i1 and i2, the threshold value generation circuit 271 generates threshold values Ip1, Im1, Ip2, and Im2, and the comparator 272 outputs comparison results Q1 and Q2.

  The threshold values Ip1, Im1 are the threshold values for the current i1, and the threshold values Ip2, Im2 are the respective threshold values for the current i2. However, there is a relationship of Ip1> Im1, Ip2> Im2.

  For example, an average value or an effective value of absolute values | i1 | can be adopted as the threshold value Ip1, and a value (−Ip1) can be adopted as the threshold value Im1. Similarly, an average value or an effective value of absolute values | i2 | can be adopted as the threshold value Ip2, and a value (−Ip2) can be adopted as the threshold value Im2. Hereinafter, the threshold values Ip1 and Im1 will be described by taking as an example the case where the effective values of the absolute values | i1 | and | i2 |

  The comparison result Q1 shows the result of comparing the current i1 with the threshold values Ip1, Im1, and the comparison result Q2 shows the result of comparing the current i2 with the threshold values Ip2, Im2. The comparison result Q1 takes a logical value “H” if the current i1 exceeds the threshold value Ip1 or less than the threshold value Im1, and takes a logical value “L” if the current value i1 is not less than the threshold value Im1 and not more than the threshold value Ip1. The comparison result Q2 takes a logical value “H” if the current i2 exceeds the threshold value Ip2 or less than the threshold value Im2, and takes a logical value “L” if the current value i2 is greater than or equal to the threshold value Im2 and less than or equal to the threshold value Ip2.

  FIG. 13 is a graph illustrating a case where power lower than the rated power is consumed by the load 9 while the currents Ir, Is, and It are in a three-phase equilibrium state. The relationship between the AC voltage Vr and the currents Ir, Is, It is the same as that in FIG. Here, the effective value of the absolute value of the current Ir is adopted as the threshold value Ip, and the value (−Ip) is adopted as the threshold value Im. Since the currents Ir, Is, It are in a three-phase equilibrium state, the thresholds Ip, Im are commonly used for all of the currents Ir, Is, It. That is, Ip = Ip1 = Ip2, Im = Im1 = Im2.

  FIG. 13 shows periods Zrp1, Zrp2, Ir <Im, periods Zrm1, Zrm2, and Is> Ip, periods Zsp1, Zsp2, and Is <Im, periods Zsm1, Zsm2, and It> Ip. The periods Ztm1 and Ztm2 in which Ztp1, Ztp2, It <Im are also added.

  Since the currents Ir, Is, It are in a three-phase equilibrium state, the period Zrp1 and the period Zsm2 coincide, the period Zrp2 and the period Ztm1 coincide, the period Zsp1 and the period Ztm2 coincide, and the period Zsp2 and the period Zrm1 matches, the period Ztp1 matches the period Zrm2, and the period Ztp2 matches the period Zsm1.

  In the second determination, it is determined in which direction the current detectors CT1 and CT2 are attached to any of the power supply lines Lr, Ls, and Lt. For example, if the current Ir is detected as the current i1, the current detector CT1 is attached to the power supply line Lr, and the attached direction is regarded as the positive direction. For example, if a current i2 has a value that is opposite in polarity to the current Is, that is, a current -Is is detected, the current detector CT2 is attached to the power line Ls, and the direction in which the current detector CT2 is attached is regarded as a negative direction. .

  As is apparent from FIGS. 3 and 13, the period during which the current Ir can take a positive value is limited to a 120-degree interval of 30 to 150 degrees in terms of the phase of the AC voltage Vr, and the current Ir takes a negative value. The period to obtain is limited to a section of 120 degrees of 210 to 330 degrees in terms of the phase of the AC voltage Vr. The current Is is a 120-degree section that is 120 degrees behind the current Ir, and the current It is a 120-degree section that is 120 degrees behind the current Is, and the period of taking a positive value and a negative value is limited.

  Therefore, from the comparison result Q1 in a specific 120 degree section, whether the current i1 corresponds to any of the currents Ir, Is, It, -Ir, -Is, -It, in other words, the current detector CT1 is connected to the power supply line Lr, It can be determined in which direction it is attached to either Ls or Lt. Similarly, the attachment state of the current detector CT2 can be determined from the comparison result Q2.

  A 60-degree section that bisects the specific 120-degree section is treated as a “mode”. At least one of the zero cross signals Xrs and Xst is input to the mode determination circuit 273, and the mode determination circuit 273 sets the phases at the time when the currents i1 and i2 are measured from at least one of the zero cross signals Xrs and Xst as six modes. The mode value of this mode is output. Specifically, in terms of the phase of the AC voltage Vr, the value mode is 0 in the 90 to 150 degree interval, 2, 270 to 330 degree in the 1,210 to 270 degree interval, and 270 to 330 degree. In the section, it is set to 3, 330 to 360 degrees, 4 in the section of 0 to 30 degrees, and 5 in the section of 30 to 90 degrees. The value mode is also appended in FIG.

  Hereinafter, when both the current detectors CT1 and CT2 can be handled in the same manner for convenience, they may be collectively referred to as the current detector CTk. Similarly, when both the currents i1 and i2 can be handled in the same manner, they may be collectively referred to as the current ik. Similarly, when both of the comparison results Q1 and Q2 can be handled in the same manner, they may be collectively referred to as a comparison result Qk.

  Table 1 is a correspondence table showing the relationship between the mode and the state in which the current detector CTk is attached in a three-phase equilibrium state. The descriptions “mode0”, “mode1”, “mode2”, “mode3”, “mode4”, and “mode5” in the top row indicate types of modes. The description “R phase voltage phase” in the second stage from the top indicates the relationship between the phase of the R phase AC voltage Vr and the mode type. This relationship represents the setting of the value mode described above. Hereinafter, for the sake of simplicity, sections of 60 degrees corresponding to modes in which the value mode is set to 0, 1, 2, 3, 4, 5 are designated as 0th mode, 1st mode, 2nd mode, 3rd mode, respectively. Also referred to as a fourth mode and a fifth mode.

  The description in the third and subsequent stages from the top indicates what value the current ik takes in the corresponding mode and in what direction it is provided with respect to which phase power supply line.

  “Positive” indicates that the value obtained by subtracting any of the threshold values Ip and Im from the current ik is positive, and “Negative” indicates that the value obtained by subtracting any of the threshold values Ip and Im from the current ik is negative. "Indicates that the current ik is between the thresholds Ip and Im, respectively. In other words, the magnitude relationship between the threshold value and the current ik with the width of the value from the threshold value Im to the threshold value Ip as the dead zone is represented as “positive”, “negative”, and “0”.

  For example, referring also to FIG. 13, if current Ir is detected as current ik, period Zrp2 exists in the 0th mode, period Zrp1 exists in the fifth mode, and period Zrm1 exists in the second mode. In the third mode, there is a period Zrm2, and in the first mode and the fourth mode, Ip ≧ Ir ≧ Im is always satisfied. Such a pattern corresponds to “R-phase positive direction” in Table 1, and the current detector CTk that detects the current ik is attached in the positive direction with respect to the power supply line Lr, that is, the direction in which the current toward the rectifier circuit 2 is positive. It is judged that

  If the current detector CTk is attached in the negative direction with respect to the power supply line Lr, that is, in the direction opposite to the direction in which the current toward the rectifier circuit 2 is positive, the current ik detected by the current detector CTk is , The polarity is opposite to the pattern indicated by “R-phase positive direction”, and the result is indicated by “R-phase negative direction”.

  The existence of the above-described periods Zrp1 and Zrp2 can be confirmed by obtaining Ir> Ip, and the existence of the periods Zrm1 and Zrm2 can be obtained by obtaining Ir <Ip by a plurality of measurements.

  Returning to FIG. 12, the counter control circuit 274 performs counting in a flowchart described later based on the value mode and the determination results Q1 and Q2. The counter group 2751 is used for counting the current i1, and the counter group 2752 is used for counting the current i2.

  The counter group 2751 includes counters RpCNT, RmCNT, SpCNT, SmCNT, SpCNT, and SmCNT. The current detector CT1 is “R-phase positive”, “R-phase negative”, “S-phase positive”, and “S-phase negative”. The possibility of being attached in “direction”, “T phase positive direction”, and “T phase negative direction” is counted.

  Similarly to the counter group 2751, the counter group 2752 also has counters RpCNT, RmCNT, SpCNT, SmCNT, SpCNT, and SmCNT. Accordingly, both currents i1 and i2 can be processed in parallel.

  The comparator 276 adopts the values counted by these counters RpCNT, RmCNT, SpCNT, SmCNT, TpCNT, and TmCNT (hereinafter, for convenience, the values of these counters are also used. For example, the counter RpCNT is used. Is counted as “count value RpCNT”) with a predetermined threshold value CA. As a result, among the “R-phase positive direction”, “R-phase negative direction”, “S-phase positive direction”, “S-phase negative direction”, “T-phase positive direction”, and “T-phase negative direction”, the current detector CTk is attached. The most likely one is determined.

  FIG. 14 shows that the currents Ir, Is and It are in a three-phase unbalanced state (the T phase of the AC voltage is 100/97 with respect to the R and S phases), and power lower than the rated power is consumed by the load 9. It is a graph which illustrates the case. The relationship between the AC voltage Vr and the currents Ir, Is, It is the same as that in FIG.

  Here, the threshold values Im1, Im2 correspond to the case where the absolute values of the currents i1, i2 are effective values, and the threshold values Ipr, Ips, Ipt indicate the effective values of the absolute values of the currents Ir, Is, It, respectively. The threshold values Imr, Ims, and Imt were set to values -Ipr, -Ips, and -Ipt, respectively.

  Due to the above three-phase non-equilibrium state, the period where Ir> Ipr exists as the period Zrp only in the 0th mode, and the period where Ir <Imr exists as the period Zmp only in the third mode. A period in which Is> Ips exists as the period Zsp only in the first mode, and a period in which Is <Ims exists as the period Zms only in the fourth mode. Periods Ztp1 and Ztp2 in which It> Ip exist in the third mode and the fourth mode, respectively, and periods Ztm1 and Ztm2 in which It <Im exist in the 0th mode and the first mode, respectively. Therefore, according to Table 1, in the second mode and the fifth mode, “R-phase positive”, “R-phase negative”, “S-phase positive”, “S-phase negative”, “T-phase positive”, “ The notation in all the columns of “T phase negative” is “0”.

  In any mode, any of Imr ≦ Ir ≦ Ipr, Ims ≦ Is ≦ Ips, Imt ≦ It ≦ Ipt is established, and there is a relationship of Ir + Is + It = 0. Therefore, it can be seen that any of the values -Ipr and -Ips can be adopted as the threshold value Imt, and any of the values -Imr and -Ims can be adopted as the threshold value Ipt. Then, considering the relationship of Imt = −Ipt, it can be seen that the same values can be adopted for the thresholds Ipr, Ips, and Ipt. This situation is the same as the property of the threshold value in the three-phase equilibrium state. Eventually, the threshold value generation circuit 271 shown in FIG. 12 has a common value as the threshold values Ip1 and Ip2, for example, the effective value or average of the absolute value | i1 | It is understood that a value or a predetermined value, for example, the above-described effective value or a value corresponding to the average value can be adopted as the threshold value Ip, and a common value −Ip can be adopted as the threshold values Im1 and Im2.

  FIG. 15 is a flowchart illustrating a determination routine which is an example of the operation of the second embodiment. The determination routine is an interrupt process for a main routine (not shown), for example, and is started by the interrupt process, and the process returns to the main routine when the determination routine ends. The determination routine is performed by the attachment determination unit 270 together with the main routine, for example. FIG. 1 illustrates the case where the values of the currents i1 and i2 are given to the active filter control unit 27. In this case, the determination routine can be performed in the active filter control unit 27 including the attachment determination unit 270.

  The determination routine is repeated a predetermined number of times in a period that is an integral multiple of 180 degrees in terms of the phase of the AC voltage Vr. This period and the number of times will be described later.

  After the determination routine is started, in step S9, the counter is reset, specifically, all the counters RpCNT, RmCNT, SpCNT, SmCNT, SpCNT, and SmCNT included in the counter groups 2751 and 2752 are reset. As a result, the count values RpCNT, RmCNT, SpCNT, SmCNT, TpCNT, and TmCNT are 0 in both the counter groups 2751 and 2752.

  After step S9 ends, step S1 is executed. In step S1, the currents i1 and i2 are detected. Speaking in accordance with FIG. 12, step S1 corresponds to input of the values of currents i1 and i2 to threshold generation circuit 271.

  After step S1, step S2 is executed. In step S2, the phase of the AC voltage Vr is detected. Referring to FIG. 12, step S2 corresponds to a process for setting at least one of the zero cross signals Xst and Xrs to the mode determination circuit 273 and setting a mode based thereon.

  Steps S41 and S42 are executed after step S2. These are processes based on the values of the currents i1 and i2, respectively, and can be executed in parallel. Step S41 is a process of determining the mounting state of the current detector CT1 using the value of the current i1 and the mode value mode, and is denoted as “CT1 mounting state determination process” in FIG. Step S42 is a process of determining the mounting state of the current detector CT2 using the value of the current i2 and the mode value mode, and is denoted as “CT2 mounting state determination process” in FIG.

  In steps S51 and S52, it is determined whether any of the count values RpCNT, RmCNT, SpCNT, SmCNT, TpCNT, and TmCNT in the counter groups 2751 and 2752 has become a predetermined value or more. The above threshold value CA corresponds to this predetermined value.

  If the determination result in step S51 is negative, that is, if any of the count values RpCNT, RmCNT, SpCNT, SmCNT, TpCNT, and TmCNT in the counter group 2751 is less than the threshold value CA, the process proceeds to step S3. If the determination result in step S52 is negative, that is, if any of the count values RpCNT, RmCNT, SpCNT, SmCNT, TpCNT, and TmCNT in the counter group 2752 is less than the threshold value CA, the process proceeds to step S3.

  If the determination result in step S51 is affirmative, it is determined in step S61 that the attachment state of the current detector CT1 has been determined (denoted as “attachment state determination of CT1” in FIG. 15). If the determination result in step S52 is affirmative, it is determined in step S62 that the attachment state of the current detector CT2 has been determined (denoted as “attachment state determination of CT2” in FIG. 15). The reason for this determination will be described later. The process proceeds to step S3 both after step S61 and after step S62.

  In step S3, it is determined whether or not the processing of steps S61 and S62 has been performed for both of the current detectors CT1 and CT2 (indicated as “fixed state of both CT1 and CT2?” In FIG. 15). . If the determination result in step S3 is affirmative, that is, if it is determined that both the current detectors CT1 and CT2 have been attached, the process returns to the main routine. If the determination result in step S3 is negative, that is, if one or both of the processes in steps S61 and S62 are not performed, the mounting state of one or both of the current detectors CT1 and CT2 is not fixed. The process returns to step S1.

  If the result of determination in step S3 is negative in at least one of steps S51 and S52, the determination routine is not terminated. However, since the currents i1 and i2 are detected in parallel by different current detectors CT1 and CT2, the period in which step S1 is repeatedly executed with only one of steps S61 and S62 being executed is short.

  FIGS. 16 and 17 are flowcharts showing the details of the attachment state determination process employed in both steps S41 and S42. The flowchart of FIG. 16 and the flowchart of FIG. 17 are connected to each other by connectors J1 and J2. However, the connectors J1 and J2 are introduced because the attachment state determination processing is divided into two flowcharts due to the limitation of the size of the drawing, and has no other meaning.

  In the attachment state determination process, step S10 (FIG. 16) is first executed. In step S10, it is determined whether or not the current ik is larger than the threshold value Ip. As described above, any one of the threshold values Ip1 and Ip2 may be adopted as the threshold value Ip. If the determination result in step S10 is negative, that is, if ik ≦ Ip, the process proceeds to step S40 (FIG. 17) via the connector J1.

  In step S40, it is determined whether or not the current ik is smaller than the threshold value Im. As described above, any one of the thresholds Im1 and Im2 may be adopted as the threshold Im. If the determination result in step S40 is negative, that is, if ik ≧ Im, the process returns from the attachment state determination process to the flowchart of FIG. 15 via the connector J2. That is, if the attachment state determination process is adopted as step S41, the process returns to step S51. If the attachment state determination process is adopted as step S42, the process returns to step S52.

  In this manner, only steps S10 and S40 are executed in the attachment state determination process, and the process returns to step S51 or step S52 is an event that occurs when Im ≦ ik ≦ Ip, and the above-described period Zrp, This is an event that occurs in a period that is not any of Zrp1, Zrp2, Zsp, Zsp1, Zsp2, Ztp1, Ztp2, Zrm, Zrm1, Zrm2, Zsm, Zsm1, Zsm2, Ztm1, and Ztm2. Accordingly, in this case, neither the counter is incremented nor reset, and the count value is maintained.

  In FIG. 16 and FIG. 17, the count value is counted up by “+ = 1” and the reset by “= 0”.

  If the determination result in step S10 is affirmative, that is, if ik> Ip, an event corresponding to any of the periods Zrp, Zrp1, Zrp2, Zsp, Zsp1, Zsp2, Ztp1, and Ztp2 occurs. Therefore, the counter is incremented and reset according to the mode.

  If the determination result in step S10 is affirmative, the process proceeds to step S200 to determine whether or not the timing at which the current ik is detected is the 0th mode. If the determination result of step S200 is negative, the process proceeds to step S201 to determine whether or not the timing is in the first mode. If the determination result of step S201 is negative, the process proceeds to step S202 to determine whether or not the timing is in the second mode. If the determination result of step S202 is negative, the process proceeds to step S203 to determine whether or not the timing is in the third mode. If the determination result of step S203 is negative, the process proceeds to step S204 to determine whether or not the timing is in the fourth mode. If the determination result of step S204 is negative, the process proceeds to step S205 to determine whether or not the timing is in the fifth mode. If the determination result of step S205 is negative, the process returns from the attachment state determination process to the flowchart of FIG. For example, such a path can be assumed when the timing is at the boundary between modes (the phase of the AC voltage Vr is (30 + 60 × N) degrees (where N is an integer).

  If the determination results in steps S200, S201, S202, S203, S204, and S205 are positive, the process proceeds to steps S300, S301, S302, S303, S304, and S305, respectively.

  A positive determination is made in step S200 when the current ik having a value larger than the threshold value Ip is detected in the 0th mode. In the first case, the period Zrp2 shown in FIG. Alternatively, the current ik is detected at the timing in the period Zrp shown in FIG. This corresponds to the case where the current Ir is detected as the current ik. In the second mode when the current ik having a value larger than the threshold value Ip is measured in the 0th mode, the current ik is detected at the timing in the period Ztm1 shown in FIGS. is there. This corresponds to the case where the current −It is detected as the current ik.

  That is, a positive determination is made in step S200 when the current detector CTk is mounted in the “R-phase positive direction” or the “T-phase negative direction”. Therefore, in step S300, the count values RpCNT and TmCNT are counted up, and the other count values RmCNT, TpCNT, SpCNT, and SmCNT are reset.

  Similarly, a positive determination is made in step S201 when the current detector CTk is attached in “S-phase positive direction” or “T-phase negative direction”. Therefore, in step S301, the count values SpCNT, TmCNT are counted up, and the other count values SmCNT, TpCNT, RpCNT, RmCNT are reset.

  A positive determination is made in step S202 when the current detector CTk is mounted in the “S phase positive direction” or the “R phase negative direction”. Therefore, in step S302, the count values SpCNT, RmCNT are counted up, and the other count values SmCNT, RpCNT, TpCNT, TmCNT are reset.

  An affirmative determination is made in step S203 when the current detector CTk is mounted in “T phase positive direction” or “R phase negative direction”. Therefore, in step S303, the count values TpCNT and RmCNT are counted up, and the other count values TmCNT, RpCNT, SpCNT, and SmCNT are reset.

  A positive determination is made in step S204 when the current detector CTk is mounted in the “T phase positive direction” or the “S phase negative direction”. Therefore, in step S304, the count values TpCNT and SmCNT are counted up, and the other count values TmCNT, SpCNT, RpCNT, and RmCNT are reset.

  A positive determination is made in step S205 when the current detector CTk is mounted in the “R-phase positive direction” or “S-phase negative direction”. Therefore, in step S305, the count values RpCNT and SmCNT are counted up, and the other count values RmCNT, SpCNT, TpCNT, and TmCNT are reset.

  When any of steps S300, S301, S302, S303, S304, and S305 is executed, the attachment state determination process ends, and the process returns to the flowchart of FIG.

  If the determination result in step S40 is affirmative, that is, if ik <Im, an event corresponding to any of the periods Zrm, Zrm1, Zrm2, Zsm, Zsm1, Zsm2, Ztm1, and Ztm2 occurs. Therefore, the counter is incremented and reset according to the mode.

  If the determination result in step S40 is affirmative, the process proceeds to step S500, and it is determined whether or not the timing at which the current ik is detected is the 0th mode. If the determination result of step S500 is negative, the process proceeds to step S501 to determine whether or not the timing is in the first mode. If the determination result of step S501 is negative, the process proceeds to step S502 to determine whether or not the timing is in the second mode. If the determination result of step S502 is negative, the process proceeds to step S503 to determine whether or not the timing is in the third mode. If the determination result of step S503 is negative, the process proceeds to step S504 to determine whether or not the timing is in the fourth mode. If the determination result of step S504 is negative, the process proceeds to step S505 to determine whether or not the timing is in the fifth mode. If the determination result of step S505 is negative, the process returns from the attachment state determination process to the flowchart of FIG. For example, such a path can be assumed when the timing is at the boundary between modes (the phase of the AC voltage Vr is (30 + 60 × N) degrees (where N is an integer).

  If the determination results in steps S500, S501, S502, S503, S504, and S505 are positive, the process proceeds to steps S600, S601, S602, S603, S604, and S605, respectively.

  A positive determination is made in step S500 when the current detector CTk is attached in the “T phase positive direction” or the “R phase negative direction”. Therefore, the process of step S600 is the same as the process of step S303.

  A positive determination is made in step S501 when the current detector CTk is mounted in the “T phase positive direction” or the “S phase negative direction”. Therefore, the process of step S601 is the same as the process of step S304.

  A positive determination is made in step S502 when the current detector CTk is mounted in the “R-phase positive direction” or the “S-phase negative direction”. Therefore, the process of step S602 is the same as the process of step S305.

  A positive determination is made in step S503 when the current detector CTk is mounted in the “R-phase positive direction” or the “T-phase negative direction”. Therefore, the process of step S603 is the same as the process of step S300.

  A positive determination is made in step S504 when the current detector CTk is mounted in the “S-phase positive direction” or the “T-phase negative direction”. Therefore, the process of step S604 is the same as the process of step S301.

  A positive determination is made in step S505 when the current detector CTk is mounted in the “S phase positive direction” or the “R phase negative direction”. Therefore, the process of step S605 is the same as the process of step S302.

  When any of steps S600, S601, S602, S603, S604, and S605 is executed, the attachment state determination process ends, and the process returns to the flowchart of FIG.

  Tables 2 and 3 show that the mode value mode and each counter when the current detector CTk is mounted in the “R-phase positive direction” when power lower than the rated power is consumed by the load 9. The operation is shown in association with it. Regarding the operation of the counter, the count-up is indicated as “increase”, and the time when neither the count-up nor reset is indicated as “maintain”.

  Table 2 illustrates a case where the currents Ir, Is, It are in a three-phase equilibrium state.

  In the fifth mode (mode = 5), step S305 is executed in the period Zrp1. Therefore, the counters RpCNT and SmCNT are counted up and the other counters are reset.

  In the 0th mode (mode = 0), step S300 is executed in the period Zrp2. Therefore, the counters RpCNT and TmCNT are counted up and the other counters are reset.

  In the first mode (mode = 1), since the determination results in steps S10 and S40 are negative, the count values of all the counters are maintained.

  In the second mode (mode = 2), step S602 is executed in the period Zrm1. Therefore, the counters RpCNT and SmCNT are counted up and the other counters are reset.

  In the third mode (mode = 3), step S603 is executed in the period Zrm2. Therefore, the counters RpCNT and TmCNT are counted up and the other counters are reset.

  In the fourth mode (mode = 4), since the determination results of steps S10 and S40 are negative, the count values of all the counters are maintained.

  FIG. 18 corresponds to Table 2 and is a graph showing the relationship between the current ik, the comparison result Qk, and the count value RpCNT. In the periods Zrp1, Zrp2, Zrm1, and Zrm2, the comparison result Q1 becomes “H”, indicating that the count value RpCNT increases.

  As can be seen from Table 2, no matter how the three consecutive modes are selected, the count value RpCNT increases in the two modes, is maintained in the one mode, and is not reset. The count values SmCNT and TmCNT increase in one mode, are maintained in one mode, and are reset in one mode. Other count values are reset in two modes and maintained in one mode.

  As described above, when the three-phase balanced state is obtained, the count value RpCNT becomes the maximum among the count values of all the counters when the current detector CTk is attached in the “R-phase positive direction”. Although six types of attachment states of which current detector CTk is attached to which power supply line can be assumed, each corresponds to a counter having the maximum count value, similar to the above-described count value RpCNT. Therefore, there is a one-to-one correspondence between the counter having the maximum count value and the attached state of the current detector CTk.

  When the three-phase equilibrium state is obtained, in steps S61 and S62, for example, a counter having the maximum count value is obtained, and the attachment state of the current detector CTk can be determined corresponding to the counter.

  Table 3 exemplifies a case where the currents Ir, Is, It are in a three-phase unbalanced state (the T phase of the AC voltage is 100/97 with respect to the R and S phases).

  In the fifth mode (mode = 5), since the determination results in steps S10 and S40 are negative, the count values of all the counters are maintained.

  In the 0th mode (mode = 0), step S300 is executed in the period Zrp. Therefore, the counters RpCNT and TmCNT are counted up and the other counters are reset.

  In both the first mode (mode = 1) and the second mode (mode = 2), the determination results in steps S10 and S40 are negative, so the count values of all counters are maintained.

  In the third mode (mode = 3), step S603 is executed in the period Zrm. Therefore, the counters RpCNT and TmCNT are counted up and the other counters are reset.

  In the fourth mode (mode = 4), since the determination results of steps S10 and S40 are negative, the count values of all the counters are maintained.

  FIG. 19 corresponds to Table 3 and is a graph showing the relationship between the current ik, the comparison result Qk, and the count value RpCNT. In the periods Zrp and Zrm, the comparison result Q1 becomes “H”, indicating that the count value RpCNT is increased.

  As can be seen from Table 3, no matter how the three consecutive modes are selected, the count values RpCNT and TmCNT are increased in one mode (0th mode), maintained in two modes, and reset. It will not be done. Other count values are reset in one mode and maintained in two modes.

  Thus, when the current detector CTk is mounted in the “R-phase positive direction” in the three-phase unbalanced state, the count values other than the count values RpCNT and TmCNT are substantially zero. Although the count values RpCNT and TmCNT are substantially equal, it is assumed that the count value TmCNT is larger than the count value RpCNT. Considering this, there is a possibility that the attachment state of the current detector CTk cannot be determined correctly only by obtaining the counter having the maximum count value.

  For example, in steps S61 and S62, the maximum count value is compared with the next largest count value. If the difference between the two is a predetermined number or more, the attachment state of the current detector CTk can be determined corresponding to the counter having the maximum count value.

  If the difference between the maximum count value and the next largest count value is less than the above-mentioned predetermined number, further determinations are made in steps S61 and S62. In the example described above, this determination is a determination for distinguishing between “R-phase positive direction” corresponding to the counter RpCNT and “T-phase negative direction” corresponding to the counter TmCNT.

  In order to make the determination, the current i3 is calculated using the currents i1 and i2 from the relationship of Ir + Is + It = 0, and further determination is performed using the current i3.

  If the current detector CT1 is mounted in the “R phase positive direction”, the current i3 = −i1−i2 is calculated when the current detector CT2 is mounted in the “S phase positive direction”. When attached in the “negative direction”, the current is calculated as i3 = −i1 + i2. The current i3 is the current It shown in FIG. 14. If the determination result in step S10 is affirmative, that is, if ik> Ip, step S303 and step S304 are also executed, and the current i3 is “T-phase positive. Direction "current. That is, it is determined that the current i1 is detected by the current detector CT1 attached in the “R-phase positive direction”.

  Further, if the current detector CT1 is mounted in the “T-phase negative direction”, the current i3 = i1−i2 (or i3 = i1 + i2) is calculated. In this case, if the determination result in step S10 is affirmative, that is, if i3> Ip, the current i3 (not shown) is executed, and step S300 is executed to count up the count value RpCNT. However, if the determination result in step S40 is affirmative, that is, if i3 <Im, step S601 is executed and the count value RpCNT is reset. Therefore, the current i3 is not determined to be “R-phase positive” current. That is, it is determined that the current i1 is detected by the current detector CT1 attached in the “T-phase negative direction”.

  As described above, the mounting state can be determined by calculating the current in the non-detection phase in the current in the three-phase non-equilibrium state.

  Since the length corresponding to the three consecutive modes corresponds to the half cycle of the AC voltage Vr, the determination routine (see FIG. 15) is executed over at least the half cycle or an integral multiple of the length. Is desirable. However, for the following reason, it is desirable that the determination routine is executed over at least twice the half cycle, that is, over one cycle of the AC voltage Vr and an integral multiple of the half cycle.

  The case where the frequency of the AC voltage Vr is 50 Hz and the execution frequency of the determination routine (see FIG. 15) is performed at a period (1/6000) s (6 kHz in terms of frequency) will be described as an example. In this case, a determination routine of 20 times (= 6 kHz / 50 Hz) / 6) is executed in each mode.

  If three-phase equilibrium is obtained, for example, the periods Zrp1, Zrp2, Zrm1, and Zrm2 (see FIG. 13) occupy about 50% of the length of the mode in which each exists. Therefore, the count value RpCNT is counted up 10 times in the periods Zrp1, Zrp2, Zrm1, and Zrm2. In view of Table 2, it is desirable that the attachment state determination process (see FIGS. 16 and 17) is performed over three consecutive modes. Therefore, assuming that the count value is increased by 1 by one count-up, the value 20 can be adopted as the predetermined value (threshold value CA in the case of FIG. 12) serving as the determination criterion in steps S51 and S52.

  On the other hand, in the case of three-phase non-equilibrium, the periods Zrp, Zmp (see FIG. 14) occupy half the length of the periods Zrp1, Zrp2, Zrm1, Zrm2 (see FIG. 13). Therefore, if the attachment state determination process (see FIGS. 16 and 17) is executed over three consecutive modes, the value 10 can be adopted as the predetermined value.

  However, since it is unknown in advance whether or not three-phase equilibrium is obtained, the predetermined value that is the determination criterion in steps S51 and S52 is set assuming that three-phase equilibrium is obtained. Is desirable. At this time, if three-phase equilibrium is not obtained (that is, if three-phase non-equilibrium), the length corresponding to six consecutive modes will be taken until the attachment state is determined in view of Table 3. An attachment state determination process is executed. Therefore, as described above, it is desirable that the determination routine is executed at an integral multiple of a half cycle of the AC voltage Vr (where the integer is 2 or more).

<Effect of inverter control>
In the first embodiment and the second embodiment, the case where a capacitor input type circuit using a large-capacity capacitor as the smoothing filter 6 is adopted as a general inverter circuit has been described as an example. In a so-called electrolytic capacitorless inverter circuit using a small-capacitance capacitor for the smoothing filter 6, the AC voltage Vr, Vs, Vt is three-phase unbalanced by performing inverter control by a known method to suppress the pulsating current of the DC current. Even so, the currents Ir, Is, It can be brought close to three-phase equilibrium.

  FIG. 20 is a graph showing the currents Ir, Is, It, the comparison result Qk, and the count value RpCNT when the inverter 21 is controlled so as to suppress the DC current pulsating flow in a three-phase electrolytic capacitor-less inverter circuit. The power consumed by the load 9 is lower than the rated power and is in a three-phase unbalanced state (the T phase of the AC voltage is 100/97 with respect to the R and S phases). Unlike the case shown in FIG. 13, there is not only the period Zrp1 in which Ir> Irp in the 0th mode, but also the period Zrp2 in which Ir> Irp in the fifth mode, unlike the case shown in FIG. . Therefore, the attachment state (corresponding to steps S61 and S62 in FIG. 15) can be determined based on Table 2 instead of Table 3.

  Both the inverter control unit 7 and the active filter control unit 27 may implement various procedures executed by them, or various means or various functions realized or a part or all of them by hardware.

  For example, both the inverter control unit 7 and the active filter control unit 27 can be configured to include a microcomputer and a storage device. The microcomputer executes each processing step (in other words, a procedure) described in the program. The storage device can be composed of one or a plurality of various storage devices such as ROM (Read Only Memory), RAM (Random Access Memory), and rewritable nonvolatile memory (EPROM (Erasable Programmable ROM), etc.). . The storage device stores various information, data, and the like, stores a program executed by the microcomputer, and provides a work area for executing the program. It can be understood that the microcomputer functions as various means corresponding to each processing step described in the program, or can realize that various functions corresponding to each processing step are realized.

  While the embodiments have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the appended claims. The various embodiments and modifications described above can be combined with each other.

100 Power converter CT1, CT2 Current detector Ir, Is, It (Three-phase) current Lr, Ls, Lt Power supply line i1, i2 Current ε, ε ', ε ", δ Threshold

Claims (4)

A first current detector (CT1) and a second current detector with respect to three power lines (Lr, Ls, Lt) for inputting a three-phase current (Ir, Is, It) to the power converter (100) (CT2) is a method for determining the state of being attached,
(I) First condition: an instantaneous value at an appropriate timing or an average of the first value with respect to a first value (| i1 |) as an absolute value of the first current (i1) detected by the first current detector Value (| i1 | ^) or the effective value or peak value of the first value and the second value (| i2 |) that is the absolute value of the second current (i2) detected by the second current detector. Either an instantaneous value at an appropriate timing or an average value (| i2 | ^) of the second value or an effective value or a peak value of the second value is larger than the positive first threshold (ε) (S11). ),
(Ii) Second condition: an instantaneous value at an appropriate timing for a third value (| i3 |) as an absolute value of a difference between the first value (| i1 |) and the second value (| i2 |) or The average value (| i3 | ^) of the third value or the effective value or peak value of the third value is smaller than the positive second threshold (δ) (S12),
When any of is satisfied,
A method of determining whether or not the first current detector and the second current detector are attached to one power supply line (D3).   When the first condition is satisfied and the second condition is not satisfied, the first current detector (CT1) is attached to the first power supply line (Lr), and the second current detector (CT2) is The determination method of the attachment state of the current detector according to claim 1, wherein it is determined that the second power supply line (Lt) is different from the first power supply line (D0). The first condition is not satisfied, and the instantaneous value or the average value (| i1 | ^) of the first value or the first value of the first value (| i1 |) at an appropriate timing When the effective value is smaller than the positive third threshold (ε ′), it is determined that the first current detector (CT1) is not attached to any of the power supply lines (D1). Item 3. A method for determining the mounting state of the current detector according to Item 2. The first condition is not satisfied and the instantaneous value or the average value (| i2 | ^) of the second value or the second value at the appropriate timing for the second value (| i2 |) When the effective value is smaller than the positive fourth threshold value (ε ″), it is determined that the second current detector (CT2) is not attached to any of the power lines (D2). The judgment method of the attachment state of the current detector as described in any one of.

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