The present invention relates to a power converting device. More particularly, the present invention relates to a power converting device which is used for a large-volume frequency converting device for use to control electric motors for railway vehicles and large industries, and for power systems, and includes a power semiconductor switching element.
Conventionally, as a technique of avoiding damages on a device when a power semiconductor abnormally operates, there is a technique of comparing a control drive instruction signal for a drive circuit which drives the power semiconductor, and operation information for detecting an operation state where the drive circuit drives the power semiconductor to conduct or interrupt, and determining the abnormal operation of the drive circuit when a mismatch continues for a certain period of time (see, for example, PTL 1).
Further, conventionally, as a technique of directly sensing a temperature abnormality of a semiconductor chip, there is a technique of detecting a control instruction signal and a delay time taken until the power semiconductor is interrupted, and thereby detecting a temperature rise of a power bipolar transistor (see, for example, PTL 2).
PTL 1: JP 5049817 B2
PTL 2: JP 7-170724 A
A power converter such as a large-volume frequency converter for use to control electric motors for railway vehicles and large industries and for power systems controls power of a high voltage and a large current. However, when an element failure occurs, a power supply short-circuits, and the power converter is likely to fall in a remarkable troubled state. It is necessary to stop a power converter as early as possible and avoid damages on the device when a power semiconductor abnormally operates to prevent such a situation. Hence, there is adopted an abnormality detecting method for comparing a control drive instruction signal for a drive circuit which drives the power semiconductor, and operation information for detecting an operation state where the drive circuit drives the power semiconductor to conduct or interrupt, and determining the abnormal operation of the drive circuit when a mismatch continues for a certain period of time. A conventional example of such a method is the technique disclosed in PTL 1, and
Hence, it is desirable to detect in advance an abnormality of a device which results in such power supply short-circuiting, and take an appropriate measure. Hence, there is a method for, for example, providing a temperature sensor near a power semiconductor and detecting an overtemperature abnormality of the power semiconductor. However, this method has difficulty in detecting a temperature rise of a semiconductor chip caused by a rise in a thermal resistance in the power semiconductor. Hence, it is demanded to directly detect a temperature abnormality of the semiconductor chip. A technique disclosed in PTL 2 is conventionally such a technical example.
In this example, a circuit which determines an output voltage of the power semiconductor is necessary to detect an abnormal rise in a temperature of the power semiconductor. However, a large-volume power converting device controls a high voltage. Therefore, it is difficult to install a voltage divider of a large size, it is necessary to provide at least six power semiconductors when three-phase alternating currents are controlled and provide at least three voltage dividers to evaluate voltages of the power semiconductors, it is necessary to take a measure for significant noise during switching since a large current is handled, and therefore it is difficult to apply the large-voltage power converting device.
Hence, an object is to precisely detect an abnormality and deterioration of a power semiconductor and a power converting device related to the power semiconductor device and precisely prevent a trouble such as a failure while employing a simple configuration. Further, an object is to provide a method for enabling long-term use of the power semiconductor and the power converting device.
To solve the above problem, a power converting device according to the present invention is, for example, a power converting device which includes a power semiconductor device; and an arithmetic operation circuit which gives a drive instruction to the power semiconductor, and the power converting device has a function of calculating for a drive instruction to conduct or interrupt the power semiconductor a delay time taken until an output voltage of a drive circuit applied to the power semiconductor in response to a change in the drive instruction reaches a determination value, and compares and determines the delay time and a reference value under a specific drive condition, records or displays and outputs a result of the determination, or changes at least one of the drive instruction and the drive voltage based on a result of the comparison and the determination.
According to the present invention, it is possible to provide a method which can precisely detect an abnormality or detection of a power semiconductor and a power converting device related to the power semiconductor and precisely prevent a trouble such as a failure while employing a simple configuration, and which enables long-term use of the power semiconductor and the power converting device.
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A power converting device according to the present invention is a power converting device which includes a power semiconductor device; and an arithmetic operation circuit which gives a drive instruction to the power semiconductor, and the power converting device has a function of calculating for a drive instruction to conduct or interrupt the power semiconductor a delay time taken until an output voltage of a drive circuit applied to the power semiconductor in response to the drive instruction reaches a determination value, and compares and determines the delay time and a reference value under a specific drive condition, records or displays and outputs a result of the determination, or changes at least one of the drive instruction and the drive voltage based on a result of the comparison and the determination. For the power semiconductor, an insulation gate bipolar transistor, a power MOSFET or a MOS gate control power semiconductor element may be used. According to this configuration, the specific drive condition for making comparison and determination using the reference value maybe configured to be one of an output current value of the power converting device, a direction of an output current flowing in the power semiconductor, an inter-output terminal voltage of the power semiconductor, a power voltage and a temperature in the power converting device or may be configured to be a combination of the output current value, the direction, the inter-output terminal voltage, the power voltage and the temperature. Further, the delay time measured in advance by the power converting device may be recorded and a value calculated by performing an arithmetic operation on a value of the delay time may be used for the reference value used to make comparison with and determination on the delay time. Furthermore, when a result obtained by the comparison and the determination is recorded, and a number of times of the recording or a time interval of the recording satisfies a given condition, a display output or at least one of the drive instruction and the drive voltage may be configured to be changed. Still further, the drive instruction or the drive voltage may be configured to be changed to interrupt the power semiconductor for a certain period of time based on a result of the comparison and the determination. Moreover, a time width of a conduction instruction of the power semiconductor according to the drive instruction may be configured to be decreased based on a result of the comparison and the determination. Besides the power converting device may further include: means which communicates a signal of the drive instruction, and a signal of a result indicating that the output voltage of the drive circuit has reached the determination value between the arithmetic operation circuit and the power semiconductor; and a determination circuit which receives an input of the signal of the communication means and a signal related to the specific drive condition, and compares and determines the delay times and the reference value, and a result of the determination may be configured to be outputted to the arithmetic operation circuit or the drive circuit. Further, the power converting device may be configured to include communication means which records the result of the determination and outputs a result of the recording to an outside.
Embodiments of a power converting device according to the present invention will be described in detail below as each example with reference to drawings.
For example, an insulation gate bipolar transistor which is a MOS gate control power semiconductor, i.e., an IGBT can measure and confirm an increase in a delay time of approximately 1 ns per 1° C. of a temperature rise in the power semiconductor by setting an appropriate state determination voltage during on/off switching at +15 V and −12 V of a voltage amplitude of a control circuit. This reflects a threshold of a control voltage for turning on and off the power converting device and temperature dependency of a delay time for conducting and interrupting a current. Hence, MOSFET and other MOS control power converting devices also have the same temperature dependency, and can detect a temperature change by determining a delay time.
As is clear from a signal waveform in
Furthermore, a configuration where a drive instruction is changed for a certain period of time and is outputted to prevent heat generation of a power conversion semiconductor whose temperature rise has been detected includes decreasing heat generation of the power conversion semiconductor by limiting and lowering an upper limit value of a current flowing in the power semiconductor for a certain period of time from a point of time at which the temperature rise has been detected, setting or decreasing an upper limit of a time width of a conduction instruction for turning on the power semiconductor, decreasing a period in which a current flows and a temperature rises, and increasing a period in which the power semiconductor is turned off and the temperature lowers, or decreasing a control cycle, decreasing the number of times of switching and decreasing switching loss caused by conduction and interruption.
In this regard,
The delay time recorded in this way and a subsequent delay time under a defined drive condition during an operation of the power converting device are compared on a regular basis and, when a delay time change amount exceeds a set value or the number of times that the delay time change amount exceeds the set value exceeds a fixed frequency, an abnormality is determined. Further, the delay time is recorded at a fixed timing or a point of time at which an abnormality is determined, and, when the delay time change amount exceeds a fixed change amount during this recording time, an abnormality can be determined, too. In this regard, a drive condition for recording or determining a delay time defined herein does not need to be one condition and, by increasing the number of conditions, it is possible to further enhance temperature rise determination precision.
The external output circuit 8 is configured to output the delay time recorded by the recording determination circuit 6 and a drive condition in this case together, and an external PC can perform numerical analysis and history survey, and evaluate whether or not there is an abnormality and a remaining operational life in detail. Further, the instruction arithmetic operation circuit 7 changes a drive instruction according to an abnormality determination result, so that it is possible to reduce heat generation of the power semiconductor. Even when the power semiconductor deteriorates, it is possible to enable long-term use by reducing an output of the power semiconductor by the above-described method.
As described above, according each of the examples of the present invention, it is possible to provide a power converting device which can precisely detect an abnormality and deterioration of a power semiconductor and the power converting device related to the power semiconductor by detecting a temperature based on a delay time of a drive instruction to the power semiconductor and a drive voltage and precisely prevent a trouble such as a failure while employing a simple configuration, and enable long-time use.
In addition, a method for diagnosing and protecting an abnormality and deterioration by detecting a temperature rise of a power semiconductor according to the present embodiment has been described above. However, it is possible to diagnose and protect deterioration and an abnormality of each unit of a power converting device which causes the same temperature abnormality by the same method, too.
Number | Date | Country | Kind |
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2014-190673 | Sep 2014 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2015/073451 | 8/21/2015 | WO | 00 |