JP2004357437A - Power converter and failure diagnosis method for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power converter that is relatively simple in constitution, does not break a sound power device and has an element fault diagnosis function high in reliability, and to provide a fault diagnosis method for the same. <P>SOLUTION: The power converter comprises a DC power supply 1, a smoothing capacitor 2 for smoothing an output voltage of the DC power supply 1, an inversion circuit 3 that is constituted by bridge-connecting the power devices of a positive side and a negative side for converting the smoothed DC voltage to an AC voltage, a voltage lowering means that lowers the DC voltage, and a diagnosis circuit 9 that diagnoses a fault of the power device. The diagnosis means selectively turns on the power device of the inversion circuit 3 when the DC voltage is not higher than a prescribed value, and detects a variation in the electrical quantity of the smoothing capacitor 2 or the inversion circuit 3, thus diagnosing the fault of the power device. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a power conversion device including a self-extinguishing type power device and a failure diagnosis method thereof.
[0002]
[Prior art]
In order to perform a self-diagnosis of a short-circuit fault or an open fault of a power device used in a self-excited power converter, the power devices of the upper and lower arms of the conversion circuit are alternately turned on and off in an energized state, and a change in the voltage of each part at that time. Although a detection method is known, for example, if this method is used in a state where one of the power devices has a short-circuit abnormality, an excessive current flows and even a healthy power device may be destroyed. For this reason, the voltage between the control terminal and the second terminal of each power device is detected, and when this voltage exceeds a predetermined value, the corresponding power device is cut off, and before the short-circuit current flows, Countermeasures such as quickly protecting a power device have been considered (for example, see Patent Document 1).
[0003]
[Patent Document 1]
JP-A-8-23683 (pages 9-11, FIG. 1)
[0004]
[Problems to be solved by the invention]
However, if such measures are taken, a voltage detector must be provided between the control terminal and the second terminal of the power device, which not only complicates the circuit, but also increases the reliability and reliability of each voltage detector. Depending on the detection accuracy, the power device may be destroyed by an overcurrent or an overvoltage when the current is cut off.
[0005]
Therefore, the present invention has been made in view of the above problems, and has a relatively simple configuration and does not destroy a sound power device, and has a highly reliable element failure diagnosis function and a power conversion device. An object of the present invention is to provide a failure diagnosis method.
[0006]
[Means for Solving the Problems]
To achieve the above object, a power converter of the present invention comprises a DC power supply, a smoothing capacitor for smoothing an output voltage of the DC power supply, and a positive side for converting the smoothed DC voltage to an AC voltage. And an inverse conversion circuit configured by bridge-connecting the power device on the negative side, voltage reducing means for reducing the DC voltage, and diagnostic means for diagnosing a failure of the power device, wherein the diagnostic means comprises: When the DC voltage is equal to or less than a predetermined value, a power device of the inversion circuit is selectively turned on, and a failure of the power device is diagnosed by detecting a change in the amount of electricity of the smoothing capacitor or the inversion circuit. It is characterized by the following.
[0007]
In order to achieve the above object, a failure diagnosis method for a power converter according to the present invention includes a DC power supply, a smoothing capacitor for smoothing an output voltage of the DC power supply, and converting the smoothed DC voltage to an AC voltage. In order to perform the conversion, in a power converter including a reverse conversion circuit configured by bridge-connecting a positive side power device and a negative side power device, and a voltage reducing unit configured to reduce the DC voltage, the DC voltage is equal to or less than a predetermined value. At this time, a failure of the power device is diagnosed by selectively turning on a power device of the inverse conversion circuit and detecting a change in the amount of electricity of the smoothing capacitor or the inverse conversion circuit.
[0008]
According to the present invention, there is provided a power conversion device having a highly reliable element failure diagnosis function and a failure diagnosis method thereof, which do not destroy a sound power device by adding a relatively simple voltage reduction means. Can be provided.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
(First Embodiment)
Hereinafter, a first embodiment of a power converter according to the present invention will be described with reference to FIG. FIG. 1 is a block diagram of the power converter of the present invention.
[0010]
The AC voltage is converted into a DC voltage by a rectifier circuit 1 composed of a diode, and the converted DC voltage is smoothed by a smoothing capacitor 2. This smoothed DC voltage is converted into an AC voltage of an arbitrary frequency and voltage by the inverse conversion circuit 3. The inversion circuit 3 is configured by bridge-connecting the power devices IGBTU, IGBTX, IGBTV, and IGBTY, and the timing of turning on or off each power device is controlled by the gate control circuit 4. The power devices IGBTU and IGBTV are referred to as positive-side power devices, and the power devices IGBTX and IGBTY are referred to as negative-side power devices. Flywheel diodes are connected in anti-parallel to these power devices.
[0011]
A signal for controlling the output of the inverse conversion circuit 3 is input to the gate control circuit 4 from another control circuit, but is not shown here. Also, in FIG. 1, for the sake of simplicity, the inverse conversion circuit 3 has a single-phase output, but the following description does not change even with a three-phase output.
[0012]
A parallel circuit provided between the rectifier circuit 1 and the smoothing capacitor 2 and configured by the DC resistor 5 and the bypass switch 8 is called a precharge circuit, and when an AC input voltage is supplied to the power converter, This is a circuit for suppressing an inrush current flowing through the smoothing capacitor 2. The bypass control circuit 6 detects the voltage across the parallel circuit composed of the smoothing capacitor 2 and the discharge resistor 10 with the DC voltage detector 7, and when the smoothing capacitor 2 is charged to a predetermined voltage and precharge is completed. Then, the DC switch 5 is bypassed by turning on the bypass switch 8. The diagnostic circuit 9 performs a failure diagnosis of the power devices IGBTU, IGBTX, IGBTV, and IGBTY of the inverse conversion circuit 3.
[0013]
Hereinafter, the operations of the bypass control circuit 6 and the diagnostic circuit 9 will be described in detail.
[0014]
The bypass control circuit 6 outputs a low voltage charging signal to the diagnostic circuit 9 when the bypass switch 8 is off and the DC voltage being charged through the DC resistor 5 is still low. When the low-voltage charging signal is turned on, the diagnostic circuit 9 supplies a gate-on signal to the positive-side power devices IGBTU and IGBTV or to the negative-side power devices IGBTX and IGBTY and applies the signal to both ends of the smoothing capacitor 2 at that time. Monitor DC voltage. A short-circuit failure of the power device is detected based on whether the DC voltage is equal to or less than a predetermined value. That is, when the diagnostic circuit 9 supplies a gate-on signal to, for example, the positive power device IGBTU, it can be diagnosed that the negative power device IGBTX is not short-circuited unless the DC voltage decreases. Conversely, at this time, if the DC voltage decreases, it can be diagnosed that the power device IGBTX is short-circuited. If similar operations are sequentially performed, it is possible to detect short-circuit faults in all power devices.
[0015]
Further, when the diagnostic circuit 9 simultaneously supplies the gate-on signal to the positive power device IGBTU and the negative power device IGBTX, if the DC voltage decreases, the positive power device IGBTU and the negative power device IGBTX will either end. Can be diagnosed that there is no open failure. Conversely, at this time, if the DC voltage does not drop, it can be diagnosed that at least one of the positive power device IGBTU or the negative power device IGBTX has an open fault. Open faults can be detected similarly for the power device IGBTV and the power device IGBTY.
[0016]
The above operation principle will be described in detail below.
[0017]
A voltage drop corresponding to the ON resistance of each power device is 1 V, and a signal during low-voltage charging is output during charging near DC voltage 3 V. Consider a case where the DC voltage is 3 V now. At this time, if all the power devices are normal, there is no discharge current from the smoothing capacitor 2 even if, for example, either the positive power device IGBTU or the negative power device IGBTX is turned on. Conversely, if either the positive-side power device IGBTU or the negative-side power device IGBTX has a short-circuit fault, the smoothing capacitor 2 divides 2 V (DC voltage 3 V-voltage drop 1 V) by the resistance of the short circuit. The discharge is started with the current value as an initial value, and the DC voltage sharply drops to 1 V (voltage drop 1 V). Therefore, by monitoring a drop in the DC voltage, a short-circuit failure can be detected.
[0018]
Further, in the above state, when a gate-on signal is simultaneously applied to, for example, the positive power device IGBTU and the negative power device IGBTX, if both power devices IGBTU and IGBTX are normal, the smoothing capacitor 2 becomes 1 V (DC Discharge is started with a current value obtained by dividing the voltage of 3V-voltage drop of 1V × 2) by the resistance of the short circuit as an initial value, and the DC voltage sharply drops to 2V (voltage drop of 1V × 2). Conversely, if any one of the power devices IGBTU and IGBTX has an open fault, no short-circuit current flows, and thus no change in the DC voltage.
[0019]
As described above, according to the first embodiment of the present invention, a failure diagnosis of a power device can be performed by a relatively simple diagnostic circuit of DC voltage detection.
[0020]
(Second embodiment)
FIG. 2 is a block diagram of a power conversion device according to a second embodiment of the present invention. Regarding each part of the second embodiment, the same parts as those of the power converter according to the first embodiment of FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. The difference between the second embodiment and the first embodiment is that the diagnostic circuit 9 in FIG. 1 detects a DC voltage, whereas the diagnostic circuit 9A in FIG. 2 includes a power device IGBTX. And the current detectors 11A and 11B that are newly added for detecting the currents of the IGBTY and the IGBTY, respectively.
[0021]
With such a configuration, when the low-voltage charging signal output from the bypass control circuit 6 is on, the gate-on signal is supplied to the positive power devices IGBTU and IGBTV or to the negative power devices IGBTX and IGBTY, and By detecting the short-circuit current flowing through the positive-side and negative-side power devices by the detectors 11A and 11B, a short-circuit fault of the element can be detected. If a short-circuit current does not flow when the gate-on signal is given to the positive power device IGBTU, it can be diagnosed that the negative power device IGBTX is not short-circuited. Conversely, when a short-circuit current flows, it can be diagnosed that the power device IGBTX is short-circuited.
[0022]
When the diagnostic circuit 9A simultaneously supplies the gate-on signal to the positive power device IGBTU and the negative power device IGBTX, if a short-circuit current flows, both the positive power device and the negative power device have an open fault. If not, you can diagnose. If no short-circuit current flows, it can be diagnosed that at least one of the positive or negative power devices has an open fault.
[0023]
The quantitative description of the operation principle of the failure diagnosis in the above-described second embodiment is basically the same as that described in the description of the first embodiment, and will not be repeated. Further, the description of the third embodiment and thereafter will be omitted.
[0024]
In the present embodiment, the method of detecting the short-circuit current flowing through the power device using the current detectors 11A and 11B has been described. However, the current flowing through the smoothing capacitor 2 and the output current of the rectifier circuit 1 may be detected. . There are also a method of indirectly detecting that an overcurrent has flowed into the power device due to a rise in the voltage between the collector and the emitter of the power device that has been turned on, and a device having a function of detecting the overcurrent in the power device itself. It is also possible to detect a short-circuit current using these methods.
[0025]
As described above, according to the second embodiment of the present invention, the failure diagnosis of the power device can be performed by the relatively simple diagnostic circuit of directly or indirectly detecting the power device current at the time of low voltage charging. it can.
[0026]
(Third embodiment)
FIG. 3 is a block configuration diagram of a power converter according to a third embodiment of the present invention. Regarding each part of the third embodiment, the same parts as those of the power converter according to the first embodiment of FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. The difference between the third embodiment and the first embodiment is that the bypass control circuit 6 of FIG. 1 outputs a signal during low-voltage charging to the diagnostic circuit 9. 3 does not output this signal, and before the smoothing capacitor 2 is charged, the diagnostic circuit 9B in FIG. 3 outputs a failure diagnosis start signal to the bypass control circuit 6A, and the bypass control circuit 6A 5 is that the failure diagnosis of the power device is started with the bypass circuit 8 opened. The diagnosing circuit 9B provides a gate-on signal to the positive power device IGBTU before the rectifier circuit 1 receives power, and if the DC voltage rises above the voltage drop of the power device after a lapse of a predetermined time after the rectifier circuit 1 receives power. , It can be diagnosed that the power device IGBTX on the negative side is not short-circuited. Conversely, if the DC voltage does not rise beyond the voltage drop of the power device, it can be diagnosed that the power device IGBTX is short-circuited.
[0027]
When the diagnostic circuit 9B simultaneously supplies the gate-on signal to the positive power device IGBTU and the negative power device IGBTX before the rectifier circuit 1 receives power, the DC voltage becomes lower than the power device voltage after the rectifier circuit 1 receives power. If it does not rise above the drop, it can be diagnosed that neither the positive side power device nor the negative side power device IGBTU or IGBTX has an open fault. Conversely, if the DC voltage rises above the voltage drop of the power device, it can be diagnosed that at least one of the positive or negative power devices has an open fault.
[0028]
In the above description, the function of automatically detecting the state before the rectifier circuit 1 receives power and the function of automatically receiving power of the rectifier circuit 1 after the diagnostic circuit 9B outputs a diagnosis start signal are not described. However, it is of course possible to configure the power converter of the present invention so that these two functions are performed automatically. For example, the former detection function can be realized by the output of the DC voltage detector 7 and the operation command of the power converter, and the diagnostic circuit 9B is configured to link the output of the diagnosis start signal with the operation command of the power converter. If the latter function can be realized.
[0029]
As described above, according to the third embodiment of the present invention, a failure diagnosis of a power device can be performed by a relatively simple diagnostic circuit for detecting a DC voltage at an early stage of operation.
[0030]
(Fourth embodiment)
FIG. 4 is a block diagram of a power conversion device according to a fourth embodiment of the present invention. Regarding each part of the fourth embodiment, the same parts as those of the power converter according to the third embodiment of FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted. The fourth embodiment differs from the third embodiment in that the diagnostic circuit 9B in FIG. 3 detects a DC voltage, whereas the diagnostic circuit 9C in FIG. 4 includes a power device IGBTX. And the currents of the current detectors 11 </ b> A and 11 </ b> B for detecting the current of each of the IGBTY and IGBTY.
[0031]
Before the smoothing capacitor 2 is charged, the diagnosis circuit 9C outputs a failure diagnosis start signal to the bypass control circuit 6A, and the bypass control circuit 6A opens the bypass switch 8. The point that the short-circuit fault of the power device is detected by detecting the short-circuit current flowing through the positive-side and negative-side power devices by the current detectors 11A and 11B is the same as that of the second embodiment shown in FIG. . The diagnostic circuit 9C supplies a gate-on signal to the positive power device IGBTU before the rectifier circuit 1 receives power, and the negative power device IGBTX is not short-circuited if a short-circuit current does not flow after the rectifier circuit 1 receives power. Can be diagnosed. Conversely, when a short-circuit current flows, it can be diagnosed that the power device IGBTX is short-circuited.
[0032]
The diagnostic circuit 9C also provides a gate-on signal to the positive-side power device IGBTU and the negative-side power device IGBTX simultaneously before the rectifier circuit 1 receives power, and a short-circuit current flows after a predetermined time after the rectifier circuit 1 receives power. Then, it can be diagnosed that none of the positive and negative power devices has an open failure. Conversely, if no short-circuit current flows, it can be diagnosed that at least one of the positive or negative power devices has an open fault.
[0033]
In the present embodiment, the method of detecting the short-circuit current flowing through the power device using the current detectors 11A and 11B has been described. However, the current flowing through the smoothing capacitor 2 and the output current of the rectifier circuit 1 may be detected. . In addition, there is also a method of indirectly detecting that an overcurrent has flowed into the element due to a rise in the voltage between the collector and the emitter of the power device that has been turned on, and a device having a function of detecting the overcurrent in the power device itself. It is also possible to detect a short-circuit current using these methods.
[0034]
As described above, according to the fourth embodiment of the present invention, the failure diagnosis of the power device can be performed by a relatively simple diagnostic circuit for directly or indirectly detecting the power device current at the beginning of operation.
[0035]
(Fifth embodiment)
FIG. 5 is a block diagram of a power conversion device according to a fifth embodiment of the present invention. Regarding each part of the fifth embodiment, the same parts as those of the power converter according to the fourth embodiment of FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted. The fifth embodiment is different from the fourth embodiment in that a low-voltage power supply 12 and a DC power supply switching circuit 13 are added, and the output of the diagnostic circuit 9D is bypassed via a bypass control circuit 6B. The point is that the switch 8 is short-circuited, and the DC power supply switching circuit 13 selects the low voltage power supply 12 according to the failure diagnosis start signal of the diagnostic circuit 9D.
[0036]
In the above configuration, when the diagnosis start signal of the diagnosis circuit 9D is output, the bypass control circuit 6B short-circuits the bypass switch 8, selects the low-voltage power supply 12 by the DC power supply switching circuit 13, and directly reverses the low voltage. It is supplied to the conversion circuit 3. In this state, when the diagnosis circuit 9D supplies the gate-on signal to the positive power device IGBTU, if no short-circuit current flows through the current detectors 11A and 11B, it can be diagnosed that the negative power device IGBTX is not short-circuited. Conversely, when a short-circuit current flows, it can be diagnosed that the power device IGBTX is short-circuited.
[0037]
If the diagnostic circuit 9D simultaneously supplies the gate-on signal to the positive power device IGBTU and the negative power device IGBTX after the low-voltage power supply 12 is selected by the DC power supply switching circuit 13, if a short-circuit current flows, It can be diagnosed that none of the positive and negative power devices has an open fault. Conversely, if no short-circuit current flows, it can be diagnosed that at least one of the positive or negative power devices has an open fault.
[0038]
Further, in the present embodiment, the method of detecting the short-circuit current flowing through the power device using the current detectors 11A and 11B has been described. However, as in the second and fourth embodiments, the current flowing through the smoothing capacitor 2 and the The output current of the low-voltage power supply 12 may be detected, a method of indirectly detecting that an overcurrent flows in the power device due to a rise in the voltage between the collector and the emitter of the turned on power device, or a method of detecting the power device itself. Some have a function of detecting an overcurrent, and it is also possible to detect a short-circuit current by using these methods.
[0039]
As described above, according to the fifth embodiment of the present invention, a failure diagnosis of a power device is performed by a relatively simple diagnostic circuit of direct or indirect power device current detection using another low-voltage power supply. It can be carried out.
[0040]
(Sixth embodiment)
FIG. 6 is a block diagram of a power converter according to a sixth embodiment of the present invention. Regarding each part of the sixth embodiment, the same parts as those of the power conversion device according to the fourth embodiment of FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted. The difference of the sixth embodiment from the fourth embodiment is that the diagnostic circuit 9E does not output a diagnostic start signal to the bypass control circuit 6C, and instead uses the newly added input switch 15 instead. The difference is that the switching control is provided to the input switch control circuit 14, and the bypass control circuit 6C outputs a signal during the low voltage discharge to the diagnostic circuit 9E. The diagnostic circuit 9E outputs a failure diagnosis start signal to the input switch control circuit 14 while the smoothing capacitor 2 is charged, and the input switch control circuit 14 switches the input switch 15 when receiving the failure diagnosis start signal. Open. The bypass control circuit 6C detects that the voltage of the smoothing capacitor 2 has dropped to a predetermined voltage, and supplies a signal during low-voltage discharge to the diagnostic circuit 9E. Then, the diagnostic circuit 9E supplies a gate-on signal to the positive-side power devices IGBTU and IGBTV or to the negative-side power devices IGBTX and IGBTY, and the current detectors 11A and 11B detect a short-circuit current flowing through the positive-side and negative-side power devices. To detect. When the input switch 15 is opened, the voltage of the smoothing capacitor 2 is gradually decreased by the discharge resistor 10, so that the failure diagnosis of the power device is started after the DC voltage is sufficiently reduced.
[0041]
Here, as described above, when the gate-on signal is given to the positive-side power device IGBTU, if the short-circuit current does not flow, the negative-side power device IGBTX is not short-circuited, so that it can be diagnosed that the power device is sound. Conversely, when a short-circuit current flows, it can be diagnosed that the power device IGBTX is short-circuited.
[0042]
When the diagnostic circuit 9E simultaneously supplies a gate-on signal to the positive power device IGBTU and the negative power device IGBTX, if a short-circuit current flows, it is determined that both the positive power device and the negative power device are sound. Diagnose. If no short-circuit current flows, it can be diagnosed that at least one of the positive or negative power devices has an open fault.
[0043]
In this embodiment, the current flowing through the smoothing capacitor 2 may be detected instead of using the current detectors 11A and 11B to detect the short-circuit current flowing through the power device. There are also a method of indirectly detecting that an overcurrent has flowed into the power device due to a rise in the voltage between the collector and the emitter of the power device that has been turned on, and a device having a function of detecting the overcurrent in the power device itself. It is also possible to detect a short-circuit current using these methods.
[0044]
As described above, according to the fifth embodiment of the present invention, the failure diagnosis of the power device can be performed by the relatively simple diagnostic circuit of directly or indirectly detecting the power device current during the low voltage discharge. it can.
[0045]
(Seventh embodiment)
FIG. 7 is a block diagram of a power conversion device according to a seventh embodiment of the present invention. Regarding each part of the seventh embodiment, the same parts as those of the power converter according to the second embodiment of FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted. The seventh embodiment differs from the second embodiment in that the gate-on signal output from the diagnostic circuit 9F is changed to the voltage of the normal gate-on signal of the diagnostic circuit 6A in the second embodiment of FIG. This is a point that a low-voltage gate signal having a lower value than that of the first embodiment is used. By applying the gate-on signal to the positive-side power devices IGBTU and IGBTV or the negative-side power devices IGBTX and IGBTY at a voltage lower than the normal voltage, the on-state current of the power device is limited.
[0046]
Similarly, when a gate-on signal is given to the positive-side power device IGBTU, if the short-circuit current does not flow, the negative-side power device IGBTX is not short-circuited and can be diagnosed as sound. Conversely, when a short-circuit current flows, it can be diagnosed that the power device IGBTX is short-circuited.
[0047]
When the diagnostic circuit 9F simultaneously supplies the gate-on signal to the positive-side power device IGBTU and the negative-side power device IGBTX, if a short-circuit current flows, it is diagnosed that both the positive-side and negative-side elements are sound. it can. Conversely, if no short-circuit current flows, it can be diagnosed that at least one of the positive or negative power devices has an open fault.
[0048]
In the present embodiment, the method of suppressing the current by lowering the gate-on voltage of the power device has been described. However, as another method of suppressing the current, there is a method of inserting a limiting resistor in a short circuit. If a technique for limiting these currents is used, it is not always necessary to make a diagnosis with a very small circuit voltage of several volts.
[0049]
Furthermore, in the present embodiment, the method of detecting the short-circuit current flowing through the power device using the current detectors 11A and 11B has been described. However, the second and fourth embodiments may use other direct or indirect current detection. This is the same as the description of the sixth to sixth embodiments.
[0050]
As described above, according to the seventh embodiment of the present invention, a failure diagnosis of a power device can be performed by a relatively simple diagnostic circuit for directly or indirectly detecting a power device current during low-voltage discharge. .
[0051]
Further, as a common effect of all the embodiments of the present invention, since there is no possibility that an overcurrent flows, diagnosis can be performed by giving a sufficiently long gate-on signal to the power device, and generation of a gate-on signal for diagnosis can be performed. In some cases, it becomes easier and the reliability of the failure diagnosis is improved.
[0052]
In the above description of the first to seventh embodiments, the power converter having a configuration in which a DC is obtained from an AC input and the output of the rectifier circuit 1 has been described. However, a DC power supply such as a battery or a fuel cell may be used instead. May be used. In a power converter using a variable voltage DC power supply, the voltage may be reduced by controlling the power converter.
[0053]
【The invention's effect】
As described above, according to the present invention, a power converter having a relatively simple configuration and having a highly reliable element failure diagnosis function that does not destroy sound power devices, and failure diagnosis thereof A method can be provided.
[Brief description of the drawings]
FIG. 1 is a block diagram of a power conversion device according to a first embodiment of the present invention.
FIG. 2 is a block configuration diagram of a power conversion device according to a second embodiment of the present invention.
FIG. 3 is a block diagram of a power conversion device according to a third embodiment of the present invention.
FIG. 4 is a block configuration diagram of a power conversion device according to a fourth embodiment of the present invention.
FIG. 5 is a block diagram of a power converter according to a fifth embodiment of the present invention.
FIG. 6 is a block diagram of a power converter according to a sixth embodiment of the present invention.
FIG. 7 is a block diagram of a power converter according to a seventh embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rectifier circuit 2 Smoothing capacitor 3 Inverting circuit 4 Gate control circuit 5 DC resistance 6, 6A, 6B, 6C Bypass control circuit 7 DC voltage detector 8 Bypass switch 9, 9A, 9B, 9C, 9D, 9E Diagnostic circuit 10 Discharge resistors 11A, 11B Current detector 12 Low voltage power supply 13 Switching control circuit 14 Input switch control circuit 15 Input switch

Claims (16)

DC power supply,
A smoothing capacitor for smoothing the output voltage of the DC power supply,
In order to convert the smoothed DC voltage to an AC voltage, an inverting circuit configured by bridge-connecting the positive and negative power devices,
Voltage reducing means for reducing the DC voltage,
Diagnostic means for diagnosing a failure of the power device,
The diagnostic means, when the DC voltage is a predetermined value or less,
Selectively turning on the power device of the inverse conversion circuit,
A power converter, wherein a failure of the power device is diagnosed by detecting a change in the amount of electricity of the smoothing capacitor or the inverse conversion circuit. The diagnostic means detects a short-circuit fault of the power device by turning on one of a power device on a positive side and a power device on a negative side of the inverse conversion circuit and monitoring a decrease in DC voltage. 2. The power converter according to 1. The diagnostic means detects a short-circuit fault of the power device by turning on either the positive or negative power device of the inversion circuit and directly or indirectly monitoring the DC current flowing through the arm. The power conversion device according to claim 1, wherein: 2. The electric power according to claim 1, wherein the diagnosis unit detects an open failure of the power device by turning on both the positive and negative power devices of the inverse conversion circuit and monitoring a DC voltage. Conversion device. The diagnostic means turns on both the positive and negative power devices of the inverse conversion circuit, and directly or indirectly monitors the direct current flowing through the arm to detect an open failure of the power device. The power converter according to claim 1, wherein: The power conversion device according to claim 1, wherein the voltage reduction unit uses a method that utilizes that the DC voltage immediately after the start of the initial charging of the power conversion device is sufficiently low. 2. The power conversion device according to claim 1, wherein the voltage reduction unit uses a method of switching to another DC power supply having a low voltage for use. 2. The power converter according to claim 1, wherein the voltage reducing unit discharges a residual voltage of the smoothing circuit to reduce a DC voltage. DC power supply,
A smoothing capacitor for smoothing the output voltage of the DC power supply,
An inverse conversion circuit including a power device for converting the smoothed DC voltage to an AC voltage,
Current suppressing means for suppressing an input current of the inverting circuit;
Diagnostic means for diagnosing a failure of the power device,
The diagnostic means selectively turns on a power device of the inverse conversion circuit,
A power converter, wherein a failure of the power device is diagnosed by detecting a change in the amount of electricity of the smoothing capacitor or the inverse conversion circuit. 10. The diagnostic device according to claim 9, wherein one of the power devices on the positive side and the negative side of the inverse conversion circuit is turned on, and a short-circuit fault of the power device is detected by monitoring a decrease in DC voltage. The power converter according to any one of the preceding claims. The diagnostic means detects a short-circuit fault of the power device by turning on either the positive or negative power device of the inversion circuit and directly or indirectly monitoring the DC current flowing through the arm. The power converter according to claim 9, wherein: 10. The electric power according to claim 9, wherein the diagnostic unit detects an open failure of the power device by turning on both the positive and negative power devices of the inverse conversion circuit and monitoring a DC voltage. Conversion device. The diagnostic unit detects an open failure of the power device by turning on both the positive and negative power devices of the inverse conversion circuit and directly or indirectly monitoring the DC current flowing through the arm. The power converter according to claim 9, wherein: 10. The power converter according to claim 9, wherein said current suppressing means is based on a method of limiting a current with a limiting resistor. 10. The power conversion device according to claim 9, wherein the current suppressing unit uses a method of reducing a gate-on voltage of the power device from that during normal switching. DC power supply,
A smoothing capacitor for smoothing the output voltage of the DC power supply,
In order to convert the smoothed DC voltage to an AC voltage, an inverting circuit configured by bridge-connecting the positive and negative power devices,
In a power conversion device including a voltage reducing unit configured to reduce the DC voltage,
When the DC voltage is below a predetermined value,
Selectively turning on the power device of the inverse conversion circuit,
A failure diagnosis method for a power conversion device, wherein a failure of the power device is diagnosed by detecting a change in an amount of electricity of the smoothing capacitor or the inverse conversion circuit.

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