JP4835930B2 - Inverter device provided with ground fault detection means - Google Patents

Description

  The present invention relates to an inverter device for converting a DC voltage obtained by rectifying an AC power source into an AC voltage having an arbitrary voltage and an arbitrary frequency, and capable of instantaneously detecting a ground fault when a ground fault occurs. It is about.

  As a first conventional example of an inverter device capable of instantaneous ground fault detection, an output current on the output side is detected for all phases in a three-phase output inverter device, and when normal, all three-phase output currents are detected. However, when a ground fault occurs, there is a technique that detects the occurrence of a ground fault by utilizing the fact that the total value does not become zero.

In the second conventional example shown in FIG. 13, a positive / negative DC bus between the output side of a rectifier constituted by a rectifier diode or the like and a smoothing capacitor serving as a DC power supply is inserted into a zero-phase reactor (in other words, positive / negative The occurrence of a ground fault is detected based on the induced current generated in the secondary winding wound around the zero-phase reactor. (For example, refer to Patent Document 1).
The inverter device shown in FIG. 13 converts and outputs an AC input voltage to a DC voltage, a smoothing capacitor 103 that smoothes the DC output voltage of the rectifier 102, and converts and outputs the DC output voltage from the rectifier 102 to a three-phase AC voltage. The converter 104, the freewheeling diode 4D constituting the converter 104, the gate drive circuit 4G and the IGBT 4T, the induction motor 105, the zero-phase reactor 111, the four sets of filter capacitors 112 to 115, the secondary winding 121, and the like. Yes. In addition, a current detector 131 is connected to the secondary winding 121, and a low-pass filter circuit 130 including the current detector 131 is inserted between the rectifier 102 and the smoothing capacitor 103. Here, if the impedance of the current detector 131 is selected to an appropriate value, the occurrence of a resonance phenomenon between the wiring inductance of the main circuit and the filter capacitor can be suppressed. Further, for example, when a grounding accident occurs at point A, a difference occurs between the current flowing through the positive DC bus and the current flowing through the negative DC bus, and this difference current is generated in the secondary winding 121 of the zero-phase reactor 111. A current corresponding to If the current detector 131 detects the secondary winding current, and the secondary winding current exceeds a preset value, the ground fault detector 132 is activated and a ground fault has occurred in the inverter device. Is done. In the case of this conventional example, the zero-phase reactor 111 used for ground fault detection and the secondary winding 121 wound around this are originally constituent elements of a low-pass filter circuit for suppressing a leakage current to the ground. Therefore, since it is not a dedicated product for ground fault detection, there is an advantage that an increase in cost for ground fault detection can be suppressed.
JP-A-8-237936 (page 4, FIG. 6)

  In the first conventional example capable of instantaneous ground fault detection, since it is necessary to detect all three-phase output currents as an inverter device, three current detectors are required. For this reason, if it is normal only, current detection for two phases (in other words, two current detectors) is sufficient, and an expensive current detector having an insulation function only for ground fault detection is used. It is necessary to detect the current for all phases by adding them.

  On the other hand, in the second conventional example, since insulation is already ensured between the secondary winding wound around the zero-phase reactor and the positive / negative DC bus, the newly added current detector itself has an insulation function. It is not necessary to have. Therefore, although the cost increase of the added current detector itself is small, a special zero-phase reactor having a secondary winding is indispensable. Therefore, there is a problem of cost increase due to the special zero-phase reactor, in the zero-phase reactor. The problem of the troublesomeness regarding the process for ensuring the insulation between the secondary winding and the primary winding and the connection of the secondary winding to the printed circuit board wiring pattern occurs.

An object of the present invention is to provide an inverter device capable of realizing this at a low price while being able to detect an instantaneous ground fault in the inverter device. When a ground fault occurs, an instantaneous ground fault is detected. An object of the present invention is to provide an inverter device capable of preventing breakage of a converter composed of semiconductor switching elements such as IGBT transistors based on functions.

In order to solve the above-mentioned problem, an invention according to claim 1 is an inverter device including a rectifier that converts and outputs an AC input voltage into a DC voltage, and a converter that converts and outputs the DC output voltage from the rectifier into a three-phase AC voltage. In the direction in which both windings inserted and connected to the positive and negative DC buses connecting the rectifier and the converter prevent inflow of common mode current from the AC power supply side. It is characterized by comprising means for monitoring the voltage between the terminals of the wound common mode coil and the winding inserted and connected to the negative side DC bus to detect the occurrence of a ground fault.
The common mode coil used as part of the filter circuit that reduces leakage current and generated noise in the inverter device is also used as a component for detecting the occurrence of ground faults, and is also inserted into the negative DC bus Since the voltage between terminals of the connected windings is monitored to detect the occurrence of a ground fault, a current detector is also unnecessary. For this reason, it is possible to provide an instantaneous ground fault detection function with an extremely inexpensive configuration.

The invention according to claim 2 is an inverter device comprising a rectifier that converts and outputs an AC input voltage to a DC voltage, and a converter that converts and outputs a DC output voltage from the rectifier to a three-phase AC voltage. A common mode in which both windings inserted and connected to the positive and negative DC buses connecting to the converter are wound in a direction that prevents common mode current from flowing in from the AC power supply side. The present invention is characterized in that there is provided a means for monitoring the voltage between the terminals of the coil and the winding inserted and connected to the positive side DC bus to detect the occurrence of a ground fault.
The common mode coil used here has two windings, a winding inserted and connected to the positive DC bus and a winding inserted and connected to the negative DC bus. Therefore, the invention according to claim 1 is connected to the positive DC bus, whereas the terminal voltage of the winding inserted and connected to the negative DC bus is monitored to detect the occurrence of a ground fault. It is noted that even if the voltage between the terminals of the winding is monitored, it is possible to detect the occurrence of a ground fault by the same principle.

The invention according to claim 3 is an inverter device comprising a rectifier that converts and outputs an alternating current input voltage into a direct current voltage, and a converter that converts and outputs the direct current output voltage from the rectifier into a three-phase alternating current voltage. A common mode in which both windings inserted and connected to the positive and negative DC buses connecting to the converter are wound in a direction that prevents common mode current from flowing in from the AC power supply side. Means for detecting the presence or absence of occurrence of a ground fault using a coil and a voltage between terminals of the winding inserted and connected to the negative DC bus and a voltage between terminals of the winding inserted and connected to the positive DC bus It is characterized by having prepared.
For each voltage generated between both winding terminals inserted and connected to the DC bus on the positive side and the negative side, the terminal voltages generated by the current that normally flows between both windings (current in the normal mode) are opposite in polarity. However, by utilizing the fact that the voltages between the terminals caused by the ground fault current have the same polarity, an attempt is made to eliminate the influence of the voltage between the terminals caused by the current flowing under normal conditions. For this purpose, the presence or absence of the occurrence of ground fault is detected using the voltage between the terminals of both windings.

Invention of Claim 4 is the inverter apparatus provided with the rectifier which converts and outputs the alternating current input voltage into a direct current voltage, and the converter which converts the direct current output voltage from the said rectifier into the three-phase alternating current voltage, The rectifier and the said A common mode in which both windings inserted and connected to the positive and negative DC buses connecting to the converter are wound in a direction that prevents common mode current from flowing in from the AC power supply side. A coil, means for monitoring the magnitude and direction of the terminal voltage of the winding inserted and connected to the positive side DC bus, and the terminal voltage and positive side DC of the winding inserted and connected to the negative side DC bus It is characterized by comprising means for detecting the occurrence of a ground fault based on monitoring information relating to the magnitude and direction of the inter-terminal voltage of the winding inserted and connected to the bus.
As information for determining whether or not a ground fault has occurred, the voltage between terminals of the winding inserted and connected to the negative DC bus is monitored to detect the presence or absence of a ground fault. Information on the magnitude and direction of the inter-terminal voltage of the winding inserted and connected to the positive DC bus is also used, thereby improving the detection accuracy of the occurrence of ground fault.

The invention according to claim 5 is an inverter device including a rectifier that converts and outputs an input voltage from a single-phase AC power source to a DC voltage, and a converter that converts and outputs the DC output voltage from the rectifier to a three-phase AC voltage. A common mode coil in which both windings inserted and connected between the single-phase AC power source and the rectifier are wound in a direction to prevent a common-mode current from flowing from the single-phase AC power source side, It is characterized by comprising means for monitoring the voltage between the terminals of one of the windings and detecting the presence or absence of ground fault.
In the first aspect of the invention, the common mode coil is inserted and connected to the DC bus, whereas in the present invention, the common mode coil is inserted and connected to the connection line connecting the single-phase AC power source and the rectifier. Since there are two windings of the common mode coil connected to the single-phase AC power supply, it is noted that the presence or absence of the occurrence of ground fault can be detected by the same principle as in the first aspect of the invention.

The invention according to claim 6 is an inverter device comprising a rectifier that converts and outputs an input voltage from a single-phase AC power source to a DC voltage, and a converter that converts and outputs the DC output voltage from the rectifier to a three-phase AC voltage. A common mode coil wound in a direction to prevent a common mode current from flowing from the single phase AC power supply side, the two windings inserted and connected between the single phase AC power supply and the rectifier, Means is provided for detecting the presence or absence of the occurrence of a ground fault using the voltage between the terminals of both windings.
In contrast to the invention according to claim 3, in which the common mode coil is inserted and connected to the DC bus, in the present invention, the common mode coil is inserted and connected to the connection line connecting the single-phase AC power source and the rectifier. Since there are two windings of the common mode coil connected to the single-phase AC power supply, it is noted that the presence or absence of the occurrence of ground fault can be detected by the same principle as that of the third aspect of the invention.

The invention according to claim 7 is an inverter device including a rectifier that converts and outputs an input voltage from a single-phase AC power source to a DC voltage, and a converter that converts and outputs the DC output voltage from the rectifier to a three-phase AC voltage. A common mode coil in which both windings inserted and connected between the single-phase AC power source and the rectifier are wound in a direction to prevent a common-mode current from flowing from the single-phase AC power source side, Means for monitoring the magnitude and direction of the voltage between the terminals of one of the windings, monitoring information on the magnitude and direction of the voltage between the terminals, and generation of a ground fault based on the voltage between the terminals of the other winding It is characterized by having means for detecting the presence or absence of.
In contrast to the invention according to claim 4, in which the common mode coil is inserted and connected to the DC bus, in the present invention, the common mode coil is inserted and connected to the connection line connecting the single-phase AC power source and the rectifier. Since there are also two windings of the common mode coil connected to the single-phase AC power supply, it is noted that the presence or absence of the occurrence of ground fault can be detected by the same principle as that of the invention of claim 4.

An invention according to claim 8 is an inverter device including a rectifier that converts and outputs an input voltage from a three-phase AC power source to a DC voltage, and a converter that converts and outputs the DC output voltage from the rectifier to a three-phase AC voltage. Each of the windings inserted and connected between the three-phase AC power supply and the rectifier is a common mode coil wound in a direction that prevents a common mode current from flowing from the three-phase AC power supply side, It is characterized by comprising means for monitoring the voltage between the terminals of one of the windings and detecting the presence or absence of occurrence of a ground fault.
In contrast to the invention according to claim 5, wherein the common mode coil is inserted and connected to a connection line connecting the single-phase AC power source and the rectifier, in the present invention, the common mode coil is a connection connecting the three-phase AC power source and the rectifier. Inserted and connected to the wire. Although the number of windings of the common mode coil is 3, paying attention to the fact that the induced voltage is generated between each winding terminal due to the ground fault current, regardless of the number of windings, The voltage between the terminals of the line is monitored to detect the occurrence of a ground fault.

The invention according to claim 9 is an inverter device comprising a rectifier that converts and outputs an alternating current input voltage to a direct current voltage, and a converter that converts and outputs the direct current output voltage from the rectifier to a three-phase alternating current voltage. Each of the windings inserted and connected between the three-phase output terminal and the three-phase load has a common mode coil wound in a direction that prevents a common mode current from flowing in from the converter side. The present invention is characterized by comprising means for monitoring the voltage between the terminals of the two windings and detecting the occurrence of a ground fault.
In contrast to the invention according to claim 8, wherein the common mode coil is inserted and connected to a connection line connecting the three-phase AC power source and the rectifier, in the present invention, the common mode coil is connected to the three-phase output terminal of the converter, the three-phase load, and the like. Inserted and connected between.
Regarding the three-phase output current of the converter, the total value of the three-phase output current is zero when normal, but when the ground fault occurs, the total value of the three-phase output current does not become zero. In the point that an induced voltage is generated between the wire terminals, attention is paid to what is common with the invention of claim 8. Therefore, similarly to the invention described in claim 8, if the voltage between the terminals of any one of the windings is monitored, it is possible to detect whether or not a ground fault has occurred.

According to a tenth aspect of the present invention, in the inverter device according to any one of the first to eighth aspects, the means for detecting the occurrence of the ground fault is configured to detect the presence or absence of the ground fault when the AC power supply recovers from the instantaneous power failure. It is characterized by not detecting.
When a short-time power failure occurs in an AC power source such as a single-phase AC power source or a three-phase AC power source, the inverter device continues to operate as long as the voltage between the DC terminals of the smoothing capacitor is at an operable level. However, during operation, the voltage between the DC terminals of the smoothing capacitor drops rapidly. When the AC power supply recovers from a power failure in such a situation, a large inrush current is charged to charge the smoothing capacitor with the reduced DC terminal voltage. Supplied from the power supply side. When such a large inrush current flows through each winding of the common mode coil, a voltage across the terminals that cannot be ignored is generated between the winding terminals due to the leakage inductance that exists in the windings, resulting in erroneous ground fault detection. May occur. Therefore, it is decided not to detect the occurrence of a ground fault when the AC power supply recovers from an instantaneous power failure.

The present invention according to claim 11 is the inverter apparatus according to any one of claims 1 to 9, further comprising a filter circuit including the common mode coil.
The common mode coil in the present invention is a component for detecting a ground fault, and at the same time, a filter circuit configuration that reduces leakage current and noise generated by the inverter device or reduces the influence of noise entering from the outside. It is also an element.

  According to a twelfth aspect of the present invention, in the inverter device according to the first to ninth aspects of the present invention, all the windings of the common mode coil are merely penetrated through the magnetic core holes. Some common mode coils have only windings penetrated through the magnetic core hole, and they have the same effect as when they are wound. Therefore, it is clearly included in the present invention. It is a thing.

The invention according to claim 13 is an inverter device comprising a rectifier that converts and outputs an AC input voltage to a DC voltage, and a converter that converts and outputs a DC output voltage from the rectifier to a three-phase AC voltage. A first DC reactor inserted and connected to a positive DC bus connecting the converter, and a second DC inserted and connected to a negative DC bus connecting the rectifier and the converter. A means for detecting the presence or absence of occurrence of a ground fault using a reactor, a voltage between terminals of the first DC reactor and a voltage between terminals of the second DC reactor is provided.
In contrast to the invention according to claim 3, wherein both windings of the common mode coil are inserted and connected to the positive and negative DC buses respectively, the present invention inserts and connects the first DC reactor to the positive DC bus, A second DC reactor is inserted and connected to the negative DC bus. Since the voltage between the terminals of the first DC reactor and the voltage between the terminals of the second DC reactor are used, the influence of the normal current flowing in the normal mode can be removed, and the voltage between the terminals due to the ground fault current can be extracted. As a result, it is possible to detect whether or not a ground fault has occurred.

According to the present invention, since the ground fault detection is performed using the common mode coil constituting the filter circuit, there is an effect that an extremely low cost ground fault detection circuit can be configured. Further, even when the degree of magnetic coupling between the windings of the common mode coil is low and the presence of leakage inductance cannot be ignored, it is possible to perform ground fault detection with high detection accuracy that eliminates adverse effects due to leakage inductance. In addition, the detection principle is simple and flexible, and there is an advantage that the degree of freedom regarding the arrangement of the common mode coil on the main circuit is high. For this reason, ground fault detection can be realized in various filter circuits.
In addition, the present invention is not limited to a filter circuit using a common mode coil, and can also be implemented when using a DC reactor arranged separately on each of the positive and negative DC buses. However, there is an effect that an extremely low cost ground fault detection circuit can be configured.

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is an overall configuration diagram of an inverter device corresponding to the first embodiment of the present invention. In FIG. 1, 1 is a rectifier, 2 is a common mode coil, 3 is a smoothing capacitor, 4 is a converter, and the converter 4 includes six IGBT transistors, six freewheeling diodes, and transistor drive circuits 11 to 16. 5 and 6 are current detectors for detecting the U-phase and V-phase output currents of the inverter device, 7 is a ground fault detection circuit, and the ground fault detection circuit 7 is the negative side DC mother of the common mode coil 2. Whether or not a ground fault has occurred is determined based on the voltage between the winding terminals on the wire. 8 is a control device, and the control device 8 controls on / off of each IGBT transistor constituting the converter 4, or stops the operation of the converter 4 based on the ground fault detection signal from the ground fault detection circuit 7, etc. Various processes necessary as an inverter device are performed. Reference numeral 9 denotes an S-phase grounded three-phase AC power source, and reference numeral 17 denotes a three-phase motor serving as a three-phase load. Both windings constituting the common mode coil 2 are connected and arranged in a direction to prevent a common mode current from flowing in from the input side of the AC power supply. In addition, the winding of the common mode coil 2 in this embodiment and each of the following embodiments is not only wound around the magnetic core of the common mode coil 2 but also simply passing through the core hole. Is also included. When electrical insulation is required between the main circuit side such as the converter 4 or the ground fault detection circuit 7 and the control device 8, the control device 8 and the ground fault detection circuit 7 or the control device 8 Insulated signal transmission means such as a photocoupler is inserted between the converter 4 and the converter 4.

FIG. 2 is an overall configuration diagram of the same inverter device as FIG. 1 and also shows an internal configuration of the ground fault detection circuit 7. Here, for example, when a ground fault occurs at point B (U-phase output side) in FIG. 2 at the timing when the R-phase potential of the three-phase AC power supply is the highest and the S-phase potential is the lowest, the ground flowing through the route indicated by the dotted line A fault current is generated. At this time, since the ground fault current flows only through the positive DC bus, a magnetic flux corresponding to the ground fault current is generated in the core of the common mode coil 2. Depending on the rate of increase of the magnetic flux generated in the core, the (1) side of the winding terminal is set to a positive potential between the winding terminals constituting the negative DC bus where no ground fault current flows. An induced voltage is generated. On the other hand, during normal operation without a ground fault, currents that are equal in magnitude and different only in direction always flow through the positive and negative windings of the common mode coil 2. The generated magnetic flux is suppressed to zero, and no induced voltage is generated between the winding terminals on the side constituting the negative DC bus. Therefore, the ground fault detection circuit 7 monitors the voltage between the winding terminals on the side constituting the negative DC bus, and determines that a ground fault has occurred if the voltage between the terminals exceeds a predetermined positive threshold. it can.
On the other hand, when a ground fault occurs at a timing different from the previous time, for example, at the timing when the S-phase potential of the three-phase AC power supply is the highest and the R-phase potential is the lowest, the route indicated by the one-dot chain line in FIG. A ground fault current is generated. In this case, since the ground fault current flows only through the negative DC bus, an induced voltage having a negative potential on the (1) side of the winding terminal is present between the winding terminals on the negative DC bus. appear. Therefore, if the voltage between the terminals exceeds a predetermined negative threshold, it can be determined that a ground fault has occurred.

  This is realized by the ground fault detection circuit 7 of FIG. In the ground fault detection circuit 7, 33, 34 and 37 are resistors, 35 is a positive reference voltage corresponding to a positive threshold, 36 is a negative reference voltage corresponding to a negative threshold, and 31 and 32 are comparisons of open collector outputs. Each output terminal is commonly connected to form an OR circuit. Therefore, the occurrence of a ground fault is detected by the ground fault detection circuit 7 regardless of whether the ground fault current flows through the negative side winding or the positive side winding of the common mode coil 2 (the comparators 31 and 32). When the connection point of both outputs is L output, the ground fault can be detected). Thus, an expensive current detector for detecting a ground fault is unnecessary, and an extremely inexpensive ground fault detection circuit can be configured. If the control device 7 receives the ground fault detection signal from the ground fault detection circuit 7 and immediately stops the on / off operation of the converter 4, the ground fault overcurrent (the ground fault current increases if the ground fault resistance is small). Therefore, it is possible to prevent the IGBT transistor constituting the converter 4 from being damaged. Although a filter circuit including the common mode coil 2 as a constituent element is not shown here, the filter circuit of only the common mode coil 2 or the filter circuit shown in FIG. A case where various filter circuits including 2 as a component are added is assumed as an application example.

  FIG. 3 is an overall configuration diagram of an inverter device corresponding to the second embodiment of the present invention. In FIG. 3, 38 is a resistor, and 39 is a photocoupler. Compared to the first embodiment, the ground fault detection circuit 7 is connected to the positive DC bus and monitors the voltage between the winding terminals on the positive DC bus. The principle of detection is the same as in the first embodiment. If the voltage between the winding terminals exceeds a predetermined positive or negative threshold value, it is determined that a ground fault has occurred, but the control device 8 that is the transmission destination of the ground fault detection signal is connected to the negative DC bus. Therefore, the transmission of the ground fault detection signal from the ground fault detection circuit 7 to the control device 8 is performed via the photocoupler 39 (when the photocoupler 39 is turned on, the ground fault is detected). Any insulation signal transmission means may be used as long as it has an insulation function similar to that of a photocoupler. For example, signal transmission using a pulse transformer is also possible.

  Since the magnetic coupling degree of the two windings constituting the common mode coil 2, in other words, the two windings on the positive side and the negative side of the DC bus is not 100%, there is a leakage inductance. Therefore, in the first and second embodiments, a certain amount of voltage between the winding terminals is generated even during normal operation. In order to avoid erroneous ground fault detection due to the voltage between the terminals, ground fault detection is performed. It is necessary to increase the threshold level. That is, it is necessary to reduce the sensitivity of ground fault detection. Therefore, the third embodiment shown in FIG. 4 tries to avoid the problem of sensitivity reduction. FIG. 4 shows only a different part (specifically, the ground fault detection circuit 7) from FIG. 2, and the other parts are omitted because they are the same as FIG. For easy understanding, the leakage inductances l1 and l2 are inserted and displayed in each winding of the common mode coil 2. In FIG. 4, R1, R2 and R3 are resistors (the same sign has the same resistance value), and 41 and 42 are operational amplifiers.

  When a ground fault occurs at point B shown in FIG. 2 and, for example, a ground fault current flows only through the winding on the positive DC bus of the common mode coil 2, 1) An induced voltage is generated with a positive potential on the side. Due to this induced voltage, the output voltage V1 of the operational amplifier 41 and the output voltage V2 of the operational amplifier 42 both move to the negative side to lower the voltage at the point V0, so that the voltage at the point V0 falls below the reference voltage 36 of the comparator 32. The ground fault detection signal is output. When the ground fault current flows only through the winding on the negative DC bus, an induced voltage having a negative potential on the (1) side is generated between the two winding terminals, and this induced voltage causes an operational amplifier. Since the output voltage V1 of 41 and the output voltage V2 of the operational amplifier 42 both move to the positive side, the voltage at the point V0 exceeds the reference voltage 35 of the comparator 31 and outputs a ground fault detection signal. On the other hand, a normal mode current flows through the common mode coil 2 during normal operation, but due to the presence of the leakage inductances l1 and l2, the (1) side is set to a positive potential between the winding terminals on the positive DC bus. The inter-terminal voltage is generated, and the inter-terminal voltage having a negative potential on the (1) side is generated between the winding terminals on the negative DC bus. However, the output voltage V1 is reduced by the voltage between the terminals due to the leakage inductance, but is increased in the output voltage V2, so the voltage value at the connection point V0 of both outputs is not affected at all. The influence of the voltage between both terminals generated by is eliminated. In particular, when a ground fault occurs at the timing when the S-phase potential of the three-phase AC power supply (the potential of the ground phase) becomes an intermediate potential between the R-phase and the T-phase, the winding on the positive DC bus and the negative Since ground fault currents in opposite directions flow through both windings on the side DC bus, it is necessary to detect ground faults using only the difference between the two ground fault currents, while the amount of voltage generated between terminals due to leakage inductance is Since it becomes large, it can be said that the contribution by this invention is very large.

  In the third embodiment, the voltage between both winding terminals is used as an analog value, but the voltage between the winding terminals on the positive DC bus is used after being compressed into necessary information. It is the 4th Embodiment of this invention shown in FIG. The fourth embodiment also has an effect of eliminating the influence of leakage inductance. In FIG. 5, 57 is a positive reference voltage corresponding to a positive threshold, 58 is a negative reference voltage corresponding to a negative threshold, 55 and 56 open collector output comparators, 59 and 60 are photocouplers, 51 to 56. , And 61 through 64 are resistors.

  When a ground fault occurs at point B in FIG. 5 and, for example, a ground fault current flows only through the winding on the positive DC bus of the common mode coil 2, both of the winding terminals (1) An induced voltage with a positive potential on the side is generated. The comparator 31 detects a ground fault from this induced voltage, but at the same time, the comparator 55 also detects a ground fault. Similarly, when a ground fault current flows only through the winding on the negative DC bus of the common mode coil 2, an induced voltage having a negative potential on the (1) side is generated between both winding terminals. The comparator 32 detects a ground fault from the induced voltage, but at the same time, the comparator 56 also detects a ground fault. Therefore, the control device 8 detects a true ground fault only when both the comparators 31 and 55 or the comparators 32 and 56 detect a ground fault. Since the polarity of the voltage between the two winding terminals generated by the influence of the leakage inductance during normal operation is different from each other, even if the ground fault detection threshold is lowered, the comparator that erroneously detects the ground fault is compared. Since this is a combination of the devices 31 and 56 or the comparators 32 and 55, there is no possibility of being detected as a true ground fault.

In the fifth embodiment shown in FIG. 6, the common mode coil 2 is replaced with two DC reactors 61 and 62 in the third embodiment shown in FIG. 4. The inductance values of the DC reactor 61 arranged on the positive electrode side of the DC bus and the DC reactor 62 arranged on the negative electrode side are set equal.
In the case of a DC reactor, a large voltage is generated between the winding terminals of both DC reactors even during normal operation, but the voltages between both winding terminals during normal operation are equal in magnitude and opposite to each other. Therefore, as in the case of the third embodiment, the voltage at the point V0 is not affected, and there is no possibility of erroneous ground fault detection. Similarly to the third embodiment, when a ground fault occurs, the ground fault current flowing through the DC reactor 61 arranged on the positive DC bus and the DC reactor 62 arranged on the negative DC bus are flown. Since the voltage difference between both winding terminals resulting from the difference between both ground fault currents is extracted using the voltage between the terminals of the DC reactor 61 and the voltage between the terminals of the DC reactor 62, the ground fault can be reliably detected. .
Further, when different inductance values are used for the DC reactors 61 and 62, if the difference in amplification factor is set between the operational amplifier 41 and the operational amplifier 42 in a direction that cancels out the difference between both inductance values, the same applies. The effect of can be produced.

The sixth embodiment shown in FIG. 7 is similar to the first embodiment shown in FIG. 2 except that the common mode coil 2 arranged on the DC bus is arranged on the single-phase AC power line, and then the control device 8. And the ground fault detection circuit 7 is different in that an insulating signal transmission means such as a photocoupler is inserted. Since a high voltage is generated between the single-phase AC power supply line and the negative electrode side of the DC bus, an insulating signal transmission means such as a photocoupler is inserted between the ground fault detection circuit 7 and the control device 8. In FIG. 7, 21 is a rectifier for a single-phase AC power source, and 22 is a single-phase AC power source.
For example, if the S phase of a single-phase AC power supply is grounded and a ground fault occurs at point B, only the winding on the R phase side will be used if the R phase potential is higher than the S phase potential. If the ground fault current of the route indicated by the dotted line is generated and the S phase potential is higher than the R phase potential, the ground fault in the reverse direction of the route indicated by only the R phase side winding is indicated by the dashed line. Electric current is generated. Therefore, since an induced voltage due to a ground fault current is generated between the S-phase winding terminals, the occurrence of a ground fault can be detected by the same principle as in the first embodiment.

  Further, if a method of detecting the differential voltage between the S-phase side winding terminals via R1 after setting R1 to a high resistance value in FIG. 8, the insulated signal transmission means becomes unnecessary. In FIG. 8, 71 is an operational amplifier, R1 and R2 are resistors, and those having the same appliance sign of the resistor are set to the same resistance value. In this embodiment, the differential voltage between the winding terminals on the S phase side is input to the control device 8 as an analog value, and when the absolute value of the analog input value exceeds a predetermined magnitude, the control device 8 detects a ground fault.

  Further, on the basis of the third embodiment shown in FIG. 4, the common mode coil 2 is arranged on the single-phase AC power supply line as in the sixth embodiment, and the S-phase side of the single-phase AC power supply ( The ground fault is detected by the same principle as in the third embodiment, and the ground fault detection from the ground fault detection circuit 7 is performed. The signal can also be transmitted to the control device 8 via an insulating signal transmission means such as a photocoupler.

  Alternatively, in FIG. 4, the windings on the positive DC bus are replaced with R-phase windings, and the windings on the negative DC bus are replaced with S-phase windings. A ground fault can also be detected using the voltage between terminals. Also in this case, if the resistor R1 has a high resistance value, an insulating signal transmission means such as a photocoupler becomes unnecessary.

  An embodiment shown in FIG. 9 is also conceivable. On the basis of the fourth embodiment shown in FIG. 5, the common mode coil 2 is arranged on the single-phase AC power supply line, and then the ground fault detection circuit 7 is connected between the terminals of the S-phase winding shown in FIG. A method of detecting the voltage as a differential voltage is used, and an analog value is input to the control device 8. The control device 8 obtains the voltage value between the terminals of the S-phase winding (analog value), information about the magnitude of the voltage between the terminals of the R-phase winding (information that the predetermined value has been exceeded), and direction information of the voltage value between the terminals. To detect the occurrence of ground fault.

  In the seventh embodiment shown in FIG. 10, the common mode coil 2 in the sixth embodiment shown in FIG. 7 is replaced with a three-phase common mode coil 23 and then arranged on a three-phase AC power supply line. . Whether a three-phase AC power source or a single-phase AC power source, the principle of generating a magnetic flux in the core of the three-phase common mode coil 23 in the case of a ground fault is the same. It is only necessary to monitor the voltage between the winding terminals of any one phase among the windings of the phase. Insulated signal transmission means such as a photocoupler is inserted between the ground fault detection circuit 7 and the control device 8. If the method of detecting the voltage difference between the winding terminals shown in FIG. 8 is used, the insulated signal transmission means is not necessary.

  In the eighth embodiment shown in FIG. 11, the three-phase common mode coil 23 in the seventh embodiment shown in FIG. 10 is arranged in the three-phase output line of the inverter device. During normal operation, the total value of the three-phase output current is zero, so the magnetic flux in the core of the three-phase common mode coil 23 is suppressed to zero. However, when a ground fault occurs, the three-phase The total value of the output current does not become zero, and a magnetic flux corresponding to the ground fault current is generated in the core. Since an induced voltage corresponding to the rate of increase of the magnetic flux generated in the core is generated between the terminals of each winding, if one of the voltages between the winding terminals is monitored, the ground fault is the same as in the seventh embodiment. Detection can be performed.

When the AC power supply recovers from the instantaneous power failure, an inrush current for rapidly charging the smoothing capacitor whose voltage has decreased during the power failure period is supplied from the AC power supply side, and the inrush current at that time is extremely large. For this reason, a large inter-terminal voltage is generated between the terminals of each winding due to leakage inductance existing in each winding of the common mode coil and a large inrush current flowing through each winding of the common mode coil when the power supply recovers from an instantaneous power failure. appear. Therefore, in each of the first to seventh embodiments in which a large inrush current due to the instantaneous power failure return flows to each winding of the common mode coil, there is a risk of a ground fault being erroneously detected when the instantaneous power failure is recovered. It may be better not to detect.
Therefore, as in the ninth embodiment shown in FIG. 12, the voltage across the terminals of the smoothing capacitor 3 is divided by the resistors 72 and 73 and then input to the control device 8, and the voltage across the terminals of the smoothing capacitor 3 is calculated. The control device 8 detects whether or not a power failure has occurred, and when the power failure occurs (in other words, when the voltage across the terminals of the smoothing capacitor 3 is greatly reduced), the control device 8 is connected to the terminals of the smoothing capacitor 3. It is only necessary that the ground fault is not detected until the inter-voltage returns to normal. In FIG. 12, the presence / absence of an instantaneous drop is detected by monitoring the DC bus voltage value, but a method of directly monitoring the AC power supply voltage may be used.

  According to the present invention, in an inverter device that converts a DC voltage obtained by rectifying an AC power source into an AC voltage of an arbitrary voltage and an arbitrary frequency and outputs it, when a ground fault occurs, instantaneous ground fault detection and high sensitivity Since ground fault detection can be realized with a low cost configuration, it is necessary for applications that require prevention of damage to semiconductor switching elements due to ground fault overcurrent, or for applications that require early and reliable detection of ground faults. It can be easily applied without any restrictions.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram of the inverter apparatus provided with the ground fault detection function which is the 1st Embodiment of this invention. It is a block diagram of the inverter apparatus provided with the ground fault detection function which is the 1st Embodiment of this invention. It is a block diagram of the inverter apparatus provided with the ground fault detection function which is the 2nd Embodiment of this invention. It is the ground fault detection circuit part of the inverter apparatus provided with the ground fault detection function which is the 3rd Embodiment of this invention. It is a block diagram of the inverter apparatus provided with the ground fault detection function which is the 4th Embodiment of this invention. It is a block diagram of the inverter apparatus provided with the ground fault detection function which is the 5th Embodiment of this invention. It is a block diagram of the inverter apparatus provided with the ground fault detection function which is the 6th Embodiment of this invention. In the sixth embodiment of the present invention, a modified configuration example is shown in which a photocoupler between the ground fault detection circuit and the control device is unnecessary. In the 6th Embodiment of this invention, the modification structural example using the voltage between both winding terminals of a common mode coil is shown. It is a block diagram of the inverter apparatus provided with the ground fault detection function which is the 7th Embodiment of this invention. It is a block diagram of the inverter apparatus provided with the ground fault detection function which is the 8th Embodiment of this invention. It is a block diagram of the inverter apparatus provided with the ground fault detection function which is the 9th Embodiment of this invention. It is a block diagram of the inverter apparatus provided with the conventional ground fault detection function.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rectifier 2 Common mode coil 3 Smoothing capacitor 4 Converters 5, 6 Current detector 7 Ground fault detection circuit 8 Controller 9 AC power supply 11-16 Transistor drive circuit 17 Three-phase motor 21 Rectifier 22 for single-phase AC power supply Single-phase AC power supply 23 Three-phase common mode coils 31, 32, 55, 56 Open collector output comparators 33, 34, 37, 38 Resistor 35 Positive reference voltage 36 corresponding to positive threshold Negative input corresponding to negative threshold Reference voltage 39, 59, 60 Photocoupler 41, 42, 71 Operational amplifier 51-54, 61-64 Resistor 61, 62 DC reactor 72, 73 Resistor 102 Rectifier 103 Smoothing capacitor 104 Converter 105 Induction motor 111 Zero-phase reactor 112 to 115 Filter capacitor 121 Secondary winding 130 Low pass filter circuit 131 Current detection Decoder 132 Ground fault detector 4D Freewheeling diode 4G Gate drive circuit 4T IGBT

Claims (13)

In an inverter device comprising a rectifier that converts and outputs an AC input voltage to a DC voltage, and a converter that converts and outputs a DC output voltage from the rectifier to a three-phase AC voltage,
Both windings inserted and connected to the positive and negative DC buses connecting the rectifier and the converter are wound in a direction to prevent the common mode current from flowing in from the AC power supply side. A common mode coil,
An inverter device comprising means for monitoring the voltage between terminals of the winding inserted and connected to the negative side DC bus to detect the presence or absence of a ground fault. In an inverter device comprising a rectifier that converts and outputs an AC input voltage to a DC voltage, and a converter that converts and outputs a DC output voltage from the rectifier to a three-phase AC voltage,
Both windings inserted and connected to the positive and negative DC buses connecting the rectifier and the converter are wound in a direction to prevent the common mode current from flowing in from the AC power supply side. A common mode coil,
An inverter device comprising means for monitoring the voltage between the terminals of the winding inserted and connected to the positive DC bus to detect the presence or absence of a ground fault. In an inverter device comprising a rectifier that converts and outputs an AC input voltage to a DC voltage, and a converter that converts and outputs a DC output voltage from the rectifier to a three-phase AC voltage,
Both windings inserted and connected to the positive and negative DC buses connecting the rectifier and the converter are wound in a direction to prevent the common mode current from flowing in from the AC power supply side. A common mode coil,
Means for detecting the occurrence of a ground fault using the voltage between the terminals of the winding inserted and connected to the negative DC bus and the voltage between the terminals of the winding inserted and connected to the positive DC bus An inverter device characterized by. In an inverter device comprising a rectifier that converts and outputs an AC input voltage to a DC voltage, and a converter that converts and outputs a DC output voltage from the rectifier to a three-phase AC voltage,
Both windings inserted and connected to the positive and negative DC buses connecting the rectifier and the converter are wound in a direction to prevent the common mode current from flowing in from the AC power supply side. A common mode coil,
Means for monitoring the magnitude and direction of the inter-terminal voltage of the winding inserted and connected to the positive DC bus;
Whether or not a ground fault has occurred based on monitoring information regarding the voltage between terminals of the winding inserted and connected to the negative DC bus and the magnitude and direction of the voltage between terminals of the winding inserted and connected to the positive DC bus An inverter device comprising means for detecting. In an inverter device comprising a rectifier that converts and outputs an input voltage from a single-phase AC power source to a DC voltage, and a converter that converts and outputs a DC output voltage from the rectifier to a three-phase AC voltage,
Both windings inserted and connected between the single-phase AC power supply and the rectifier, a common mode coil wound in a direction to prevent the common-mode current from flowing from the single-phase AC power supply side,
An inverter device comprising: means for monitoring a voltage between terminals of any one of the windings and detecting the presence or absence of occurrence of a ground fault. In an inverter device comprising a rectifier that converts and outputs an input voltage from a single-phase AC power source to a DC voltage, and a converter that converts and outputs a DC output voltage from the rectifier to a three-phase AC voltage,
Both windings inserted and connected between the single-phase AC power supply and the rectifier, a common mode coil wound in a direction to prevent the common-mode current from flowing from the single-phase AC power supply side,
An inverter device comprising means for detecting the presence or absence of occurrence of a ground fault by using a voltage between terminals of both windings. In an inverter device comprising a rectifier that converts and outputs an input voltage from a single-phase AC power source to a DC voltage, and a converter that converts and outputs a DC output voltage from the rectifier to a three-phase AC voltage,
Both windings inserted and connected between the single-phase AC power supply and the rectifier, a common mode coil wound in a direction to prevent the common-mode current from flowing from the single-phase AC power supply side,
Means for monitoring the magnitude and direction of the voltage across the terminals of any one of the windings;
An inverter device comprising: means for detecting the presence / absence of a ground fault based on monitoring information relating to the magnitude and direction of the inter-terminal voltage and the inter-terminal voltage of the other winding. In an inverter device comprising a rectifier that converts and outputs an input voltage from a three-phase AC power source to a DC voltage, and a converter that converts and outputs a DC output voltage from the rectifier to a three-phase AC voltage,
Each winding inserted and connected between the three-phase AC power source and the rectifier is a common mode coil wound in a direction to prevent a common mode current from flowing in from the three-phase AC power source side,
An inverter device comprising means for monitoring the voltage between terminals of any one of the windings and detecting the presence or absence of occurrence of a ground fault. In an inverter device comprising a rectifier that converts and outputs an AC input voltage to a DC voltage, and a converter that converts and outputs a DC output voltage from the rectifier to a three-phase AC voltage,
Each winding inserted and connected between the three-phase output terminal of the converter and a three-phase load is a common mode coil wound in a direction that prevents a common mode current from flowing from the converter side. ,
An inverter device comprising means for monitoring the voltage between terminals of any one of the windings and detecting the presence or absence of occurrence of a ground fault. 9. The inverter apparatus according to claim 1, wherein the means for detecting the presence or absence of the occurrence of a ground fault does not detect the presence or absence of the occurrence of a ground fault when the AC power supply recovers from an instantaneous power failure. 10. The inverter device according to claim 1, further comprising a filter circuit including the common mode coil. 10. The inverter device according to claim 1, wherein all the windings of the common mode coil are only passed through the magnetic core hole. In an inverter device comprising a rectifier that converts and outputs an AC input voltage to a DC voltage, and a converter that converts and outputs a DC output voltage from the rectifier to a three-phase AC voltage,
A first DC reactor inserted and connected to a positive DC bus connecting between the rectifier and the converter;
A second DC reactor inserted and connected to a negative DC bus connecting between the rectifier and the converter;
An inverter device comprising means for detecting the presence or absence of occurrence of a ground fault by using a voltage between terminals of the first DC reactor and a voltage between terminals of the second DC reactor.

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