KR101893174B1 - System and method for localizing multiple open-switch faults in inverter - Google Patents

Abstract

The present invention relates to a system and method for identifying multiple switch open faults in an inverter. The method for discriminating multiple switch open faults of an inverter according to the present invention groups and sets open fault types of multiple switches of an inverter and obtains current waveform data for each fault type of each group through computer- Storing; Determining whether an open fault of the inverter switch is generated based on the measured voltage or current waveform data of the inverter and a fault diagnosis algorithm; Detecting a fault group based on data stored in a memory when an open fault of the inverter switch is determined to have occurred; And a step of discriminating a fault generating unit of the multiple switches of the inverter by applying a moving window method in which the control unit calculates detection variables for every sampling period on the basis of the detected fault groups and discriminates multiple switch open fault portions of the inverter in real time .
According to the present invention, by using the fault group detection technique and the moving window method capable of calculating the detection variable every sampling period and realizing the multiple switch open failure portion of the inverter in real time, the efficiency and accuracy of the fault portion discrimination can be improved Can be further improved.

Description

FIELD OF THE INVENTION [0001] The present invention relates to an open-

The present invention relates to a system and method for identifying multiple switch open faults in an inverter and more particularly to a fault group detection technique for grouping and setting open fault types of multiple switches of an inverter, The present invention relates to a system and method for multiple switch open-end discrimination of an inverter capable of improving the efficiency and accuracy of discrimination of a fault occurrence section by applying a moving window technique that identifies multiple switch open faults of an inverter in real time.

The variable-speed AC motor drive and control system employing an inverter is a key component widely applied to various process and industrial fields, electronic parts, electric vehicles, and railroad drives.

Failures in power converters and power switches are often regarded as critical and critical to the overall drive system, since they cause an operating (shutdown) stop of the entire system. In this case, unexpected and unscheduled maintenance work must be performed, which requires a great deal of cost and time. In general, faults in inverter power devices are largely classified into open circuit (open switch) failures and short circuit failures. Short circuit failures are so damaging (very destructive) that their effect is so severe that special measures are required to immediately stop the drive system. An open-circuit (open-switch) fault does not inevitably lead to a system shutdown and may not be detected in an extended period of operation (operating) time. However, if left undetected, such failures can quickly propagate to other components because they can cause overvoltages as well as large voltage and current stresses on the inverter power devices. Thus, accurate on-line fault diagnosis and early detection of fault sources and locations are critical to avoid additional accidents and ensure continuous operation (operation) to reduce repair costs and motor downtime.

Various techniques have been studied to diagnose the open failure of power semiconductor devices in inverters and power conversion circuits. However, in actual systems, there are various types of failures, which makes it difficult to detect failures and determine the location of failures.

Most conventional fault detection and fault location identification techniques use periodic information of the current, so that after one cycle of current information is acquired by the CPU, the fault occurrence and the fault occurrence location can be grasped. Therefore, it takes much time to diagnose and distinguish the fault, and the accuracy of the discrimination is lowered depending on the operating conditions such as load.

In addition, in the conventional technique, the period of the current data is processed to determine the detection variable and the position of the fault generator is determined using the detected variable. Therefore, there is a problem that the update period of the detection variable is large and the time delay is increased.

Korean Patent Laid-Open Publication No. 10-2011-0062945 (Patent Document 1) discloses "a multi-stage switch failure diagnosis apparatus and method for a multi-level inverter ", and a multi- Stage inverter of a multi-level inverter for driving a motor by outputting an AC power of three phases, the method comprising the steps of: sequentially switching the switches constituting the multi-stage switch to output alternating current waveforms, A process of making a feature vector (reference feature vector) at the time of failure in advance into a codebook and creating a database; And a step of converting a fault diagnosis current waveform output from the inverter into a fault feature vector and determining a switch corresponding to a codebooked feature vector having a minimum distance error between the feature vector and the fault feature vector as a fault switch .

In the case of Patent Document 1 as described above, there is an advantage in that each failure of the multi-stage switch composed of multiple stages can be diagnosed. However, since it also uses the periodic information of the current, And the accuracy of the discrimination is deteriorated according to operating conditions such as load.

Korean Patent Publication No. 10-2011-0062945 (June 10, 2011)

SUMMARY OF THE INVENTION The present invention has been made to overcome the problems of the prior art as described above, and it is an object of the present invention to provide a fault group detection technique for grouping open fault types of multiple switches of an inverter, And an object of the present invention is to provide a system and a method for discriminating multiple open-circuit faults of an inverter, which can improve the efficiency and accuracy of discrimination of a fault occurrence section by applying a moving window technique for discriminating multiple open-circuit faults of an inverter in real time.

According to an aspect of the present invention, there is provided a multiple switch open failure determination system for an inverter,

A system for discriminating an open failure of a multi-semiconductor switch element in an inverter, which is employed in a drive system of an inverter-based three-phase AC motor,

An inverter for receiving a DC voltage from a DC power source and converting the AC voltage into an AC voltage for driving the three-phase AC motor, and controlling the operation of the three-phase AC motor by on / off operations of the multiple semiconductor switch elements therein;

A gate drive for converting the voltage input from the upper layer into a voltage for driving the inverter and driving the gate of the multiple semiconductor switch elements in the inverter;

An analog / digital (A / D) converter for converting a voltage and current signal (analog signal) inputted from the inverter and input to the three-phase AC motor into a digital signal;

A controller for receiving and processing an output signal from the analog-to-digital converter, diagnosing whether or not the inverter is faulty based on the processing result, and a digital signal A processor (DSP); And

And a host computer for monitoring a system controlled through the digital signal processor and for displaying a faulty portion and a fault occurrence site on the monitor screen by the digital signal processor when a fault occurs,

The digital signal processor includes a fault group detection technique for grouping open fault types of multiple switches of an inverter in determining the open fault of the multiple semiconductor switch elements in the inverter, The present invention is characterized in that an open fault portion of a multi-semiconductor switch device is discriminated by applying a moving window technique that calculates and identifies multiple switch open faults of the inverter in real time.

Preferably, when an overvoltage or an overcurrent more than a set value flows in the drive system of the inverter-based three-phase alternating-current motor between the output terminal of the inverter and the input terminal of the three-phase alternating-current motor, Phase AC electric motor by interrupting the three-phase AC motor.

According to another aspect of the present invention, there is provided a method of determining an open-

A method for discriminating an open fault portion of a multiple semiconductor switch element in an inverter, which is employed in a drive system of an inverter-based three-phase AC motor,

a) grouping and setting open fault types of multiple switches of an inverter as a preliminary preparation step, obtaining current waveform data for a fault type of each group through a computer simulation and storing the current waveform data in a memory;

b) determining whether an open fault of the inverter switch is generated based on the measured voltage or current waveform data of the inverter and a fault diagnosis algorithm;

c) if the open failure of the inverter switch is determined to have occurred, the control unit detects the fault group based on the data stored in the memory; And

d) Based on the detected fault group, the control unit computes detection variables for every sampling period and applies a moving window method to determine the open switch fault of the inverter in real time. And a step of discriminating the fault generating unit.

The fault diagnosis algorithm in step b)

b-1) calculating a root mean square (RMS) (i _arms , i _brms , i _crms ) of each phase of the three-phase AC motor;

b-2) Calculating the normalized RMS current (i _an , i _bn , i _cn ) of each phase based on the calculated current effective values (i _arms , i _brms , i _crms ) step;

b-3) detecting and counting a failure occurrence by comparing the calculated normalized current effective values (i _an , i _bn , i _cn ) of each phase with a predetermined threshold value (K _th ); And

b-4) If the failure occurrence count value is greater than or equal to a predetermined value, it is determined that the failure state is included.

The process of detecting the fault group in step c) and the fault generator of the multiple switches of the inverter in step d)

cd-1) absolute values (│i _{a, avg} │ the average value of the instantaneous current of each phase (phase) of the three-phase alternating current _{motor, │i b, avg │, │i} c, avg │) are all pre-set critical determining whether or not the value is less than (K _th);

cd-2) In the determination of the step cd-1, the absolute values (│i _{a, avg} │, │i _{b, avg} │, │i _{c, avg} │) of the average values of the instantaneous currents of the respective phases K _th ), it is determined to be the fault group 2, and a subsequent process for determining the corresponding fault switch in the fault group 2 is performed;

cd-3) either one of any critical step in the determination of the cd-1), the absolute value of the average value of the instantaneous current of each phase _{(│i a, avg │, │i} b, avg │, │i c, avg │) Determining if the zero current is 1, if not less than the value;

cd-4) In the determination of step cd-3), if the zero current is 1, it is determined as fault group 1, and a subsequent process for determining the corresponding fault switch in fault group 1 is performed; And

cd-5) In the determination of the step cd-3), if the zero current is not 1, it is determined as the failure group 3, 4, and the subsequent process for determining the corresponding failure switch in the failure group 3 or 4, .

According to the present invention, there is provided a fault group detection technique that enables accurate fault detection when an open fault occurs in an inverter switch, and a moving fault detection method that can detect multiple switch open faults of the inverter in real time by calculating detection variables every sampling period By applying the window technique, it is possible to further improve the efficiency and accuracy of discrimination of the fault occurrence part.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram schematically showing the overall configuration of a multiple switch open fault discrimination system of an inverter according to an embodiment of the present invention; Fig.
FIG. 2 is a diagram schematically showing a connection relationship between an inverter and a three-phase AC motor in the multiple switch open fault discrimination system of the inverter of FIG.
FIG. 3 is a flowchart illustrating an operation of a method for determining multiple switch open-circuit failure of an inverter according to an embodiment of the present invention.
4 is a flowchart illustrating an execution procedure of the fault diagnosis algorithm in the multiple switch open fault determination method of the inverter according to the embodiment of the present invention.
FIG. 5 is a flowchart illustrating a process of detecting a fault group and identifying a fault generating unit of multiple switches according to a method of identifying multiple switch open faults in an inverter according to the present invention.
6 is _a diagram showing waveforms of currents (i _a , i _b , i _c ) of respective phases of a three-phase AC motor under normal conditions (state).
Fig. 7 is a diagram showing the phase current response characteristics of the three-phase alternating-current motor under the failure of the open-circuit switch of the inverter. Fig.
FIG. 8 is a diagram showing the results of the fault diagnosis and the determination of the open switch failure part according to the multiple switch open failure portion discrimination method of the inverter according to the present invention.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor can properly define the concept of the term to describe its invention in the best way Should be construed in accordance with the principles and meanings and concepts consistent with the technical idea of the present invention.

Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise. Also, the terms " part, "" module, "and" device " Lt; / RTI >

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic view showing the overall configuration of a system, and FIG. 2 is a block diagram of an inverter and a three-phase AC motor according to an embodiment of the present invention. Referring to FIG. And FIG.

1 and 2, the multi-switch open-circuit failure discrimination system 100 of the inverter according to the present invention is employed in a drive system of an inverter-based three-phase ac motor 190, A gate drive 120, an analog / digital (A / D) converter 130, a digital signal processor (DSP) 140, and a host computer 150. The system includes an inverter 110, .

Inverter 110 gives the sun for receiving the DC voltage from the DC power source 170 is converted into AC voltage for driving the three-phase alternating current motor 190, a multi-semiconductor switch elements of internal (S ₁ ~S ₆₎ on / OFF operation to control the operation of the three-phase AC motor 190. [ Here, as the inverter 110, a pulse width modulation (PWM) inverter is preferably used.

The gate drive 120 supplies a voltage (for example, 0 to 3.3 V) input from an upper layer (DSP 140 described later) to a voltage (for example, -15 to 15 V) for driving the inverter 110, And drives the gates of the multiple semiconductor switch elements S _{1 to} S _{6 in the} inverter 110.

The analog / digital (A / D) converter 130 feeds back the voltage and current signals (analog signals) that are output from the inverter 110 and input to the three-phase AC motor 190, .

The digital signal processor (DSP) 140 receives and processes the output signal from the A / D converter 130, diagnoses whether the inverter 110 is faulty or not based on the processing result, It determines the opening failure of the multiple semiconductor switching elements (S ₁ ~S ₆₎ inside. The digital signal processor (DSP) 140 includes a control system setting program (DC voltage value, period setting, DC link capacitor value, motor torque value, etc.) for driving the three-phase AC motor 190, (Software) for the control system design and various control programs.

The host computer 150 monitors the system controlled through the digital signal processor 140, and displays the failure diagnosis by the digital signal processor 140 and the failure occurrence site on the monitor screen when a failure occurs. That is, when driving the three-phase AC motor 190, the host computer 150 displays on the screen the output values and waveforms of the variables to be checked by the user such as current, voltage, speed, etc., And a fault occurrence switch on the screen.

The three-phase AC motor 190 is preferably connected between the output terminal of the inverter 110 and the input terminal of the three-phase AC motor 190 when an overvoltage or an overcurrent greater than a set value flows in the drive system of the inverter- Phase AC electric motor 190 by interrupting the voltage and current supplied to the three-phase AC motor 190). 1, reference numeral 180 denotes a DC link capacitor.

In the multi-switch open-circuit fault discrimination system 100 of the inverter according to the present invention having the above-described configuration, the digital signal processor 140 includes an open fault portion of the multiple semiconductor switch elements S _{1 to} S ₆ inside the inverter A fault group detection technique for grouping open fault types of multiple switches of the inverter and a moving window for discriminating multiple switch open faults of the inverter in real time by calculating detection variables every sampling period (S ₁ -S ₆ ) by using a moving window technique.

Hereinafter, a description will be made of a process for determining the multiple switch open failure portion of the inverter based on the multiple switch open failure portion discrimination system 100 of the inverter according to the present invention.

FIG. 3 is a flowchart illustrating an operation of a method for determining multiple switch open-circuit failure of an inverter according to an embodiment of the present invention.

Referring to FIG. 3, a method for discriminating multiple open-circuit failure portions of an inverter according to the present invention is employed in a drive system of an inverter-based three-phase alternating-current motor to discriminate open fault portions of multiple semiconductor switch elements in an inverter First, as a preliminary preparation step, open fault types of multiple switches of the inverter are grouped and set, and current waveform data for the fault type of each group is obtained through computer simulation (step S301). Here, it is assumed that the open-switch failure occurs in only one switch or two multiple switches in the multiple switch open fault portion discrimination method of the inverter according to the embodiment of the present invention. Classify.

Regarding the fault groups classified as above, for the current waveforms (i _a , i _b , i _c ) of each phase of the three-phase AC motor in the normal condition (state) , Current waveform data for each group of fault types is acquired and stored in a memory (not shown).

In this way, in the state where the fault group setting and the acquisition of the fault group related current waveform data are completed, the control unit (DSP 140 in this case) checks whether the open fault of the inverter switch has occurred by comparing the measured voltage or current waveform data of the inverter with the fault diagnosis algorithm (Step S302). The fault diagnosis algorithm will be described later.

If it is determined in step S302 that an open failure of the inverter switch has occurred, the control unit detects a fault group based on the data stored in the memory (step S303). That is, one of the four fault groups described above is detected.

Then, based on the detected fault group, the control unit computes a detection variable for each sampling period to apply a moving window technique that identifies multiple switch open faults of the inverter in real time, (Step S304). That is, when a fault group is detected, it is determined which fault actually occurred in the fault group (the position of the faulty switch). This is explained later.

4 is a flowchart illustrating an execution procedure of the fault diagnosis algorithm in the multiple switch open fault determination method of the inverter according to the embodiment of the present invention.

Referring to FIG. 4, the process of executing the failure diagnosis algorithm in step S302 in the flowchart of FIG. 3 described above is performed. First, the root mean square (RMS) value of each phase of the three- i _arms , i _brms , i _crms ) (step S401).

Then, the normalized RMS current (i _an , i _bn , i _cn ) of each phase is calculated based on the calculated current effective values (i _arms , i _brms , i _crms ) of each phase S402). Here, the normalized current effective value (i _an , i _bn , i _cn ) can be expressed as follows.

i _an = i _arms / i _sm , i _bn = i _brms / i _sm , i _cn = i _crms / i _sm

Here, i _sm represents the magnitude of the current.

Then, the fault occurrence is detected and counted by comparing the calculated normalized current effective values (i _an , i _bn , i _cn ) of each phase with a predetermined threshold value (K _th ) (steps S 403 to S 407) . That is, first i _an a, and proceeds to the threshold (K _th) if the determination (step S403) to more than, the threshold fault cumulative count step (S407) is (K _th) or higher, or a threshold value or more (K _th) It determines whether i _bn over the threshold (K _th) (step S404). It determines whether this determination, i _bn the threshold value is (K _th) or higher, and proceeds to the failure cumulative count step (S407), or the threshold value or more (K _th) i _cn the threshold or more (K _th) ( Step S405). In this determination, if i _cn is not less than the threshold value K _th , the process proceeds to the failure cumulative counting step S407. If it is not equal to or greater than the threshold value K _th , it is judged that the failure state is 0 (Step S406), and returns to step S402.

On the other hand, it is determined whether or not the cumulative failure count value in the failure cumulative counting step S407 is equal to or greater than a predetermined value (for example, 10) (step S408). If the count is less than the set value, the process returns to step S403, Quot; failure state = 1 "(failure) (step S409).

Thereafter, the process proceeds to step S410 of executing a failure detection routine for detecting a switch in which an actual open failure has occurred.

FIG. 5 is a flowchart illustrating a process of detecting a fault group and identifying a fault generating unit of multiple switches according to a method of identifying multiple switch open faults in an inverter according to the present invention.

Referring to FIG. 5, this corresponds to the process of executing the fixed detection routine of step S410 of FIG. 4 (i.e., the process of detecting the fault group in step S303 of FIG. 3 and the fault generating unit of multiple switches of the inverter in step S304) First, the absolute values (│i _{a, avg} │, │i _{b, avg} │, │i _{c, avg} │) of the average values of the instantaneous currents in the phases of the three-phase AC electric motor 190 it is determined whether the set threshold is less than (K _th) (step S501).

In the determination of step S501, if the absolute values (ia _{, avg} |, ib _{, avg} |, | i _{c, avg} |) of the average values of the instantaneous currents of the respective phases are all less than the threshold value (K _th ) 2 (step S502), and proceeds to the subsequent process for determining the corresponding failure switch in the failure group 2 (steps S503 to S508). That is, it is determined whether i _an is the minimum value (i _an = Min) (step S503), and if it is the minimum value, the failure switches 1 and 4 are determined (step S504). And in the determination of the step S503 i _an is not a minimum value _{(i an = Min), i} bn , the minimum value (i _bn = Min) to determine whether or not (step S505), the minimum value when it is determined as a fault switches 2 and 5 (step S506). If i _bn is not the minimum value (i _bn = Min) in step S505, it is determined whether i _cn is the minimum value (i _cn = Min) (step S507) S508).

If it is determined in step S501 that any one of the absolute values (ia _{, avg} |, | Ib _{, avg} |, | _{c, avg} |) of the average value of the instantaneous currents in each phase is not less than the threshold value, It is determined whether the zero current is 1 (step S509).

In the determination of step S509, if the zero current is 1, it is determined to be the failure group 1 (step S510), and a subsequent process for determining the failure switch in the failure group 1 is performed (steps S511 to S522) . That is, it is determined whether i _an is the minimum value (i _an = Min) (step S 511), and if it is the minimum value, it is determined whether the average value (i _{a, avg} ) of the instantaneous current on _a is less than zero (step S 512). In this determination, if the average value (i _{a, avg} ) of the instantaneous current on the a phase is less than 0, the failure switch 1 is determined. If the average value is not less than 0, the failure switch 4 is determined (steps S513 and S514). And in the determination of the step S511 i _an the minimum value (i _an = Min) is not in, i _bn, the minimum value (i _bn = Min) to determine whether or not (step S515), the minimum value if the instantaneous current average value (i _b of on the b _{, avg} ) is smaller than 0 (step S516). In this determination, if the average value (i _{b, avg} ) of the instantaneous current on the b phase is less than 0, the fault switch 2 is judged. If the average value is not less than 0, the fault switch 5 is judged respectively (steps S517 and S518).

If i _bn is not the minimum value (i _bn = Min) in step S515, it is determined whether i _cn is the minimum value (i _cn = Min) (step S519) i _{c, avg} ) is smaller than 0 (step S520). In this determination, if the average value (i _{c, avg} ) of the instantaneous current on the c-phase is less than 0, it is judged by the failure switch 3, and if it is not less than 0, it is judged by the failure switch 6 respectively (steps S 521 and S 522).

On the other hand, in the determination of step S509, if the zero current is not 1, it is determined to be the failure group 3 or 4 (step S523). Thereafter, the process proceeds to the subsequent process for determining the corresponding fault switch in the fault group 3 or 4, respectively.

FIG. 8 is a diagram showing the results of the fault diagnosis and the determination of the open switch failure part according to the multiple switch open failure portion discrimination method of the inverter according to the present invention.

Referring to FIG. 8, (a) shows the results of fault diagnosis and fault detection (position detection) under open switch failures in switch S ₁ (fault group 1) among multiple switches of the inverter, (Location detection) under open-switch failures in switches S ₁ and S ₄ (fault group 2) of the multiple switches of FIG. It can be seen that the fault and fault switches can be effectively detected.

As described above, according to the present invention, there is provided a fault group detection method for enabling accurate fault detection when an open fault of an inverter switch occurs, and a fault group detection method for detecting a fault in a real time , It is possible to further improve the efficiency and accuracy of discrimination of a fault occurrence portion by applying a moving window method capable of discriminating open fault portions of multiple switches of the inverter.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but many variations and modifications may be made without departing from the spirit and scope of the invention. Be clear to the technician. Accordingly, the true scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of the same should be construed as being included in the scope of the present invention.

110: inverter 120: gate drive
130: analog-to-digital converter 140: digital signal processor
150: host computer 160: safety circuit
170: DC power supply 180: DC link capacitor
190: Three phase alternating current motor

Claims (5)

A system for discriminating an open failure of a multi-semiconductor switch element in an inverter, which is employed in a drive system of an inverter-based three-phase AC motor,
An inverter for receiving a DC voltage from a DC power source and converting the AC voltage into an AC voltage for driving the three-phase AC motor, and controlling the operation of the three-phase AC motor by on / off operations of the multiple semiconductor switch elements therein;
A gate drive for converting the voltage input from the upper layer into a voltage for driving the inverter and driving the gate of the multiple semiconductor switch elements in the inverter;
An analog / digital (A / D) converter for converting a voltage and current signal (analog signal) inputted from the inverter and input to the three-phase AC motor into a digital signal;
A controller for receiving and processing an output signal from the analog-to-digital converter, diagnosing whether or not the inverter is faulty based on the processing result, and a digital signal A processor (DSP); And
And a host computer for monitoring a system controlled through the digital signal processor and for displaying a faulty portion and a fault occurrence site on the monitor screen by the digital signal processor when a fault occurs,
The digital signal processor includes a fault group detection technique for grouping open fault types of multiple switches of an inverter in determining the open fault of the multiple semiconductor switch elements in the inverter, The open fault of the multiple semiconductor switch device is discriminated by applying the moving window method which calculates the open fault of the multiple switch of the inverter in real time,
The absolute value of the average value of the instantaneous current of each phase (phase) of the three-phase alternating current motor _{(│i a, avg │, │i} b, avg │, │i c, avg │) are all pre-set threshold (K _th ); ≪ / RTI >
The threshold value in the determination whether or not less than (K _th), the absolute value of the mean value of the instantaneous current in each _{(│i a, avg │, │i} b, avg │, │i c, avg │) are both thresholds ( If it is less than K _th) it is determined as a fault group 2, and proceeds to the subsequent procedure for determining the failure in the failure switch group 2;
In determining whether or not the threshold value is less than (K _th), the absolute value of the average value of the instantaneous current of each phase _{(│i a, avg │, │i} b, avg │, │i c, avg │) at any one of the critical If it is not less than the value, it is determined whether the zero current is 1;
If it is determined that the zero current is 1, it is determined that the zero current is 1, and a subsequent process for determining the corresponding failure switch in the failure group 1 is performed;
If it is determined that the zero current is 1, it is determined that the zero current is not 1, and the subsequent process for determining the corresponding failure switch in the failure group 3 or 4, respectively, Characterized by the multiple switch open fault detection system of the inverter.
The method according to claim 1,
When the overvoltage or overcurrent more than the set value flows in the drive system of the inverter-based three-phase alternating-current motor, the voltage and current supplied to the three-phase alternating-current motor are cut off between the output terminal of the inverter and the input terminal of the three- Further comprising a safety circuit for protecting the AC motor.
A method for discriminating an open fault portion of a multiple semiconductor switch element in an inverter, which is employed in a drive system of an inverter-based three-phase AC motor,
a) grouping and setting open fault types of multiple switches of an inverter as a preliminary preparation step, obtaining current waveform data for a fault type of each group through a computer simulation and storing the current waveform data in a memory;
b) determining whether an open fault of the inverter switch is generated based on the measured voltage or current waveform data of the inverter and a fault diagnosis algorithm;
c) if the open failure of the inverter switch is determined to have occurred, the control unit detects the fault group based on the data stored in the memory; And
d) Based on the detected fault group, the control unit computes detection variables for every sampling period and applies a moving window method to determine the open switch fault of the inverter in real time. And a step of discriminating a fault generating unit,
The process of detecting the fault group in the step c) and the fault generator of the multiple switches of the inverter in the step d)
cd-1) absolute values (│i _{a, avg} │ the average value of the instantaneous current of each phase (phase) of the three-phase alternating current _{motor, │i b, avg │, │i} c, avg │) are all pre-set critical determining whether or not the value is less than (K _th);
cd-2) In the determination of the step cd-1, the absolute values (│i _{a, avg} │, │i _{b, avg} │, │i _{c, avg} │) of the average values of the instantaneous currents of the respective phases K _th ), it is determined to be the fault group 2, and a subsequent process for determining the corresponding fault switch in the fault group 2 is performed;
cd-3) either one of any critical step in the determination of the cd-1), the absolute value of the average value of the instantaneous current of each phase _{(│i a, avg │, │i} b, avg │, │i c, avg │) Determining if the zero current is 1, if not less than the value;
cd-4) In the determination of step cd-3), if the zero current is 1, it is determined as fault group 1, and a subsequent process for determining the corresponding fault switch in fault group 1 is performed; And
cd-5) In the determination of the step cd-3), if the zero current is not 1, it is determined as the failure group 3, 4, and the subsequent process for determining the corresponding failure switch in the failure group 3 or 4, The method comprising the steps of:
The method of claim 3,
The fault diagnosis algorithm in step b)
b-1) calculating a root mean square (RMS) (i _arms , i _brms , i _crms ) of each phase of the three-phase AC motor;
b-2) Calculating the normalized RMS current (i _an , i _bn , i _cn ) of each phase based on the calculated current effective values (i _arms , i _brms , i _crms ) step;
b-3) detecting and counting a failure occurrence by comparing the calculated normalized current effective values (i _an , i _bn , i _cn ) of each phase with a predetermined threshold value (K _th ); And
and b-4) determining that the fault occurrence counting value is greater than or equal to a predetermined value, and determining that the fault has occurred.
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