JP2791157B2 - Inverter device abnormality detection device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter device used for variable speed operation of an induction motor, and more particularly, to a voltage source having a smoothing capacitor on the DC side of a forward converter. The present invention relates to an abnormality detection device for an inverter device suitable for an inverter device.

[Conventional technology]

Inverters, especially voltage-type inverters, have a smoothing capacitor in the DC section, so even if a minor abnormality such as a power-supply phase error occurs on the input side of the inverter including the forward converter, the operation can be performed anyway. It is possible, and therefore, even in the state where the above-mentioned minor abnormality has occurred, the operation is continued as it is, leading to burnout of the resistor for suppressing inrush current and finally to more serious abnormality due to overload. There is a risk of migration.

Therefore, conventionally, as disclosed in Japanese Patent Application Laid-Open No. 61-293118, a temperature relay is provided on a rush current suppressing resistor inserted between a forward conversion unit and an inverse conversion unit of an inverter device. However, as disclosed in Japanese Patent Application Laid-Open No. 62-107633, a method for performing a predetermined protection operation by the operation of this relay,
A method is adopted in which an exciting coil of an electromagnetic contactor for short-circuiting a resistor for suppressing inrush current during normal operation is connected between predetermined phases of a multi-phase AC input so that open-phase protection can be obtained. I was

[Problems to be solved by the invention]

In the above prior art, no consideration is given to the investigation of the cause of the occurrence of an abnormality, and although the inverter device is protected, there is a problem that it is difficult to find out the cause thereafter, and it takes much time to elucidate the cause. Was.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an abnormality detection device for an inverter device capable of performing self-diagnosis of the content of the abnormality when the abnormality occurs in the inverter device.

[Means for solving the problem]

In order to achieve the above object, an inverter including a forward conversion unit that converts input polyphase AC to DC, and an inverse conversion unit that converts DC output from the forward conversion unit to polyphase AC and outputs the same. In the device, power supply voltage detection means for detecting an inter-phase voltage on the input side of the forward conversion unit, and output side detection means for detecting at least one change in voltage or current at the output side of the quasi-conversion unit, Arithmetic processing means for comparing and analyzing the detection output of the power supply voltage detection means and the detection output of the output side detection means, wherein the arithmetic processing means is configured to detect the absence of the interphase voltage in the change within one cycle period. Based on the number and the missing timing, the occurrence of an open phase at the input side of the forward converter, the identification of the phase in which the open phase occurred, and the occurrence of an open fault in a plurality of diodes in the forward converter Open failure occurs In which specific and diode are configured to obtain.

[Action]

The timing of the voltage change on the input side and the timing of the voltage change on the output side of the forward converter of the inverter device have a predetermined relationship due to the function of the forward converter.

Therefore, if these relationships are analyzed by comparing the two, the occurrence of an open phase on the input side of the forward converter, the identification of the phase in which the open phase has occurred, and the occurrence of an open fault in a plurality of diodes in the forward converter will be described. Occurrence and the diode in which the open fault has occurred can be specified.

〔Example〕

Hereinafter, an abnormality detection device for an inverter device according to the present invention will be described in detail with reference to the illustrated embodiment.

FIG. 1 shows an embodiment of the present invention, in which 1 is an AC power supply, 2 is a forward converter, 3 is a smoothing capacitor, 4 is an inverse converter, 5 is an induction motor serving as a load, and 6 is an electromagnetic motor. Contactor,
7 is a resistor for suppressing inrush current, 8 and 9 are current detectors, 1
Reference numerals 0 and 11 are filter circuits, 12 is a comparator circuit, 13 is a power supply voltage detector, 14 is a microcomputer, and 15 is an alarm device. Note that reference numeral 16 denotes the entire inverter device.

The three-phase AC power supplied from the AC power source 1 is
Is converted into a direct current, and the capacitor 3 is charged. The DC voltage smoothed by charging the capacitor 3 is converted into a three-phase AC having a predetermined voltage and a predetermined frequency by the inverse converter 4 and supplied to the induction motor 5. The induction motor 5 can be operated at any rotational speed.

The electromagnetic contactor 6 performs a delay operation. After a predetermined time has elapsed after the power is turned on, the contact 6a is closed and the resistor 7 is short-circuited. Therefore, the charging current of the capacitor 3 when the power is turned on is suppressed to a predetermined value by the resistor 7, and the operation of suppressing the inrush current is obtained.

The comparator circuit 12 is connected to the ripple component Vcr included in the terminal voltage Vc of the capacitor 3 via the filter circuit 10.
And converts it into an on / off signal Vcs by binarizing it at a predetermined level. Instead of this, the current detector 8 is used to extract the current Ic of the capacitor 3, and the ripple component Icr included in the current Ic is extracted by the filter circuit 11, converted into an on / off signal Ics, and output. May be.

The power supply voltage detector 13 has a function of detecting a three-phase AC interphase voltage supplied to the inverter device 16 and inputting the same to the microcomputer 14.
The positive-going part and the negative-going part of the phase-to-phase voltage V _UW serve to generate an on / off signal V _UWS whose level is “1” and “0”, respectively.

The microcomputer 14 has a predetermined program,
The output current taken through the current detector 9 and others,
It takes in various data (not shown) and executes processing necessary for control of the inverse conversion unit 4 and other various controls described later.

 Next, the operation of this embodiment will be described.

Note that the general operation of the drive control of the induction motor 5 by the inverter device 16 is the same as that of a known inverter device, and a description thereof will be omitted.

First, regarding the terminal voltage Vc of the capacitor 3, since the inverter device 16 is charged by the output of the forward converter 2 during the operation of the inverter device 16, the period is determined by the peak value pulsation of the three-phase AC voltage of the AC power supply 1. Appears with ripple.

Therefore, if there is no abnormality in the power supply from the AC power supply 1 and there is no abnormality in the forward conversion unit 2 as well, the terminal voltage Vc of the capacitor 3 becomes as shown in FIG.
The voltage fluctuates at a constant cycle. As a result, the ripple component Vcr obtained at the output of the filter circuit 10 is also the terminal voltage Vcr.
As shown in FIG. 2 (a), the on / off signal Vcs output from the comparator circuit 12 also changes periodically in response to c, as in the case of the ripple component Vcr. ), It changes periodically.

Therefore, now, regarding the pulse period Δt of the on / off signal Vcs, when there is no abnormality in the power supply from the AC power supply 1 and there is no abnormality in the forward conversion unit 2, , The number of phases P of the AC power supplied from the AC power supply 1 is equal to the period ΔT determined by the frequency f.

ΔT = 1 / (2P · f) (1) That is, when there is no abnormality on the input side of the inverter device and it is operating normally, Δt = ΔT.

Now, if an abnormality appears on the input side of the inverter device, such as the occurrence of a phase loss in the AC power supplied from the AC power supply 1 or the occurrence of an abnormality in the forward conversion unit 2, the forward conversion of the capacitor 3 is performed. Since the normal charge state from the part 2 cannot be maintained, the terminal voltage Vc and the ripple component
Vcr and the on / off signal Vcs are as shown in FIG. 2 (b), respectively.
The relationship of the above equation (1) with respect to t also breaks down as shown in the figure, losing periodicity, and a period Δt ′ larger than the period Δt in the normal state appears in the pulse period of the on / off signal Vcs.

This also applies to the terminal current of the capacitor 3 detected by the current detector 8.
The state of Ic, the ripple component Icr included in the current Ic, and the state of the on / off signal Ics are as shown in FIG. As shown in FIG. 3B, a difference appears between the pulse period Δt of the on / off signal Ics in the normal state and the pulse period Δt ′ of the on / off signal Ics in the abnormal state.

Then, the microcomputer 14 executes a process according to a predetermined program, takes in at least one of the on / off signal Vcs or the on / off signal Ics from the comparator circuit 12, sequentially measures and monitors the cycle Δt, and inputs the signal to the inverter device. The abnormality is detected on the side.

FIG. 4 is a flowchart showing the contents of processing by the microcomputer 14 at this time.
Each time, the pulse period Δt is measured, and in the subsequent processing of step 102, this is compared with the pulse period ΔT determined from the above equation (1) to check whether or not the following equation is satisfied. In the following equation, m is a constant for giving a predetermined allowable range for the determination.

Δt ≦ ΔT + m When the result is N, that is, when it is determined to be negative, each processing of steps 103 and 104 is further executed. First, a predetermined alarm signal is output as the processing of step 103, and the alarm device 15 (first FIG. 4), a predetermined alarm is displayed, and then, as a process of step 104, either a process of suppressing the output of the inverter device 16 to a predetermined value or less or a process of stopping the operation is executed. Then, the processing according to this flowchart is terminated.

On the other hand, if the result of the determination in step 102 is Y, that is, affirmative, it means that there is no abnormality on the input side of the inverter device and it is operating normally, and the process is terminated as it is.

Therefore, according to this embodiment, the phase loss of the AC power supply 1,
An abnormality on the input side of the inverter device such as a failure of the forward converter 2 can always be reliably detected, and the operation of the inverter device is stopped by an abnormal alarm signal obtained as a result, or the output is reduced to a predetermined value or less. Thus, it is possible to control to reduce the number of times and continue the operation, and it is possible to sufficiently prevent the shift to a serious abnormality.

In this embodiment, when the inverter device 16 is operated under a very light load condition, that is, in this case, when the power required by the induction motor 5 is much smaller than the rated value, the input side of the inverter device It is possible that the level of the ripple component Vcr or Icr is too low to detect even if an abnormality occurs, but if the load is light like this, there is a danger that even if the operation is continued, the transition to a further abnormality may occur. There is no particular problem.

 Next, another embodiment of the present invention will be described.

Considering the above-described abnormality on the input side of the inverter device with reference to FIG. 5, the abnormality can be classified into the following modes.

a. U-phase, V of three-phase AC supplied from AC power supply 1
Phase, or W phase.

b. The six diodes D _U , D _V ,
At least one open fault of D _W , D _X , D _Y , D _Z.

c. Combination of the above abnormality a and abnormality b.

In addition, as a cause of the occurrence of such an abnormality, in addition to the occurrence of a disconnection in the tangential line or the element, a connection error at the time of manufacturing or repair, or a connection failure may be considered.

Therefore, in one embodiment of the present invention, these abnormalities are analyzed, classified and detected, and self-diagnosis can be performed.

First, FIG. 6 shows the waveforms of the three-phase AC inter-phase voltages V _UW , V _VU , V _WV supplied from the AC power supply 1 and the on / off signal V _UWS output from the power supply voltage detector 13. FIG. 4 is a timing chart showing on / off signals Vcs and Ics output from the comparator circuit 12. FIG.
The six diodes D _U , D _V , D _W , D _X , D _Y ,
A state diagram in which each of the conducting state and the non-conducting state of D _Z is represented by ○ and × is added. As is clear from this, when the input side of the inverter device is in a normal state, the AC power supply 1 In the cycle T of one cycle determined from the frequency f of the three-phase AC power supplied from the RP, six on / off signals Vcs and Ics due to the ripple components described above appear. As described above, when an abnormality occurs, the on / off signals Vcs and Ics are missing.

Then, next, these six ON / OFF signals Vcs, Ics
According to the relationship between the ON / OFF signal V _{UWS at} which the level is “1” and “0” at the positive polarity portion and the negative polarity portion of the U-phase and W-phase inter-phase voltage V _UW described above, respectively. Like, numbers are assigned in order.

Then, at the time of abnormality, when a lack appears in the on / off signals Vcs and Ics of these, it is possible to know which of the above-described modes is the content of the abnormality depending on which signal is the signal of be able to.

For example, now, the ON-OFF signal Vcs, when a lack in Ics appeared, from the state table of FIG. 6 diode is shown below the open failure diode D _U in order converter 2 is generated And then,
If the four ON / OFF signals Vcs and Ics are missing, it can be known that a phase loss has occurred in the U phase.

Therefore, the microcomputer 14, various signals described above, i.e., on-off signal Vcs output from the comparator circuit 12, and Ics, the power supply voltage detector 13 output is turned-off and the signal V _UWS from each uptake The arithmetic processing is executed in accordance with a predetermined processing program stored in advance, and the judgment processing described in FIG. 6, that is, the comparison analysis processing of the voltage change on the input side and the voltage change on the output side of the forward converter is performed. The self-diagnosis of the contents of the abnormality is performed, and the result is output to the alarm device 15 to provide a predetermined alarm display.

Therefore, according to this embodiment, when an abnormality occurs, it is warned and an abnormality countermeasure such as operation stop of the inverter device or continuation of operation under a predetermined output reduction is automatically obtained. Since the self-diagnosis result is given, an appropriate abnormality countermeasure can be easily taken.

〔The invention's effect〕

According to the present invention, the inverter device is usually provided with:
By simply adding a simple processing function to the control microcomputer, abnormality detection and self-diagnosis can always be performed reliably, so that a low-cost and highly reliable inverter device can be easily provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the inverter device according to the present invention, FIGS. 2 and 3 are waveform diagrams for explaining the operation, and FIG. 4 is a flowchart explaining the operation of the embodiment of the present invention. FIG. 5 is a circuit diagram on the input side in one embodiment of the present invention, and FIG. 6 is a timing chart for explaining the operation of another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... AC power supply 2 ... Forward conversion part 3 ... Capacitor for smoothing 4 ... Reverse conversion part 5 ... Induction motor 6 ... Electromagnetic contactor 7 ... Resistor for suppressing inrush current Containers, 8, 9 ...
Current detector, 10, 11 ... Filter circuit, 12 ... Comparator circuit, 13 ... Power supply voltage detector, 14 ... Microcomputer, 15 ... Alarm device, 16 ... Overall inverter device.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Katsuhiro Tamada 7-1-1 Higashi Narashino, Narashino City, Chiba Prefecture Within Hitachi Keiyo Engineering Co., Ltd. (56) References JP-A-54-82624 (JP, A) JP-A Sho 57-113772 (JP, A) JP-A-63-69462 (JP, A) JP-A-60-118065 (JP, A) Japanese Utility Model Application No. Sho 61-14838 (JP, U) Japanese Utility Model Application No. Sho 62-70632 (JP, A) U) Japanese Utility Model Showa 60-177686 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H02M 7/00-7/98

Claims (1)

(57) [Claims] 1. An inverter device comprising: a forward converter for converting an input polyphase alternating current into a direct current; and an inverse converter for converting a direct current output from the forward converter to a polyphase alternating current and outputting the same. Power supply voltage detection means for detecting an inter-phase voltage on the input side of the forward conversion unit; output side detection means for detecting at least one change in voltage or current at the output side of the quasi-conversion unit; Arithmetic processing means for comparing and analyzing the detected output of the voltage detecting means and the detected output of the output side detecting means, wherein the arithmetic processing means comprises: Based on the missing timing, the occurrence of an open phase on the input side of the forward conversion unit, the identification of the phase in which the open phase has occurred, and the occurrence of an open fault in a plurality of diodes in the forward conversion unit, Daio with open failure An abnormality detection device for an inverter device, wherein the abnormality detection device is configured to be able to specify a node.