JP4575876B2 - Inverter device and inverter system - Google Patents

Description

  The present invention relates to an inverter device used for parallel redundant operation and an inverter system that performs parallel redundant operation.

  As shown in FIG. 3, a plurality of inverter devices (# 1 to #n) 1 to n connected to a single DC power supply (DC power supply) 31 are operated in parallel redundancy to supply AC power to one load 32. There is an inverter system. The DC power supply 31 is a converter obtained by, for example, rectifying a commercial AC power supply with a diode and smoothing it with a capacitor or the like, and the inverter devices 1 to n are voltage type inverter devices that convert DC into AC. The output side of each of the plurality of inverter devices (# 1 to #n) 1 to n is connected to the bus 32 via the relays 4-1 to 4-n and the load 32.

Thus, a highly reliable power supply system can be obtained by configuring a plurality of inverter devices to perform parallel redundant operation with respect to a single load (see Non-Patent Document 1).
IEEJ Transactions D, Vol. 114, No. 3, 1994, “Highly reliable technology for large-scale uninterruptible power supply systems”, p262-266

However, in the case of an inverter system in which a plurality of inverter devices are operated in parallel redundancy in the form as shown in FIG. 3, an internal short circuit or failure in any one of the inverter devices (# 1 to #n) 1 to n. If this occurs, there is a problem that the bus 3 of the inverter system is short-circuited, resulting in a system down and a decrease in system reliability.
In particular, in an inverter system that operates two inverter devices in parallel and redundantly, when an internal short circuit occurs in one inverter device, a cross current flows from the healthy device to the failed device, and the two inverters are in a one-to-one relationship. There was a problem that the device became overcurrent at the same time and both inverter devices were in a failure state.

  The present invention has been made in view of such circumstances, and provides an inverter device and an inverter system capable of reliably detecting an accident such as an internal short circuit of the inverter device and disconnecting a faulty machine from the bus. For the purpose.

  In order to achieve the above object, an inverter device according to the present invention is an inverter device used for performing parallel redundant operation of a plurality of units, wherein the output of the inverter device is disconnected from a parallel bus. Column means, current detection means for detecting current flowing in the output line of the inverter device, polarity of the output current of the inverter device detected by the current detection means, and polarity of the output voltage command value given to the own device Until a time when a preset time elapses, it is determined that an internal short-circuit has occurred in the device when a current of a polarity opposite to the voltage command value flows that exceeds the preset current value. And control means for controlling the disconnecting means so as to disconnect the own machine from the bus.

In the inverter device of the present invention having the above-mentioned configuration, the current flowing through the output line of the inverter device is detected by the current detecting means, and the control means gives the polarity of the output current of the inverter device detected by the current detecting means to the own device. The polarity of the output voltage command value is compared, and when a current having a polarity opposite to that of the voltage command value exceeding the preset current value flows until the preset time elapses, It is determined that a short circuit has occurred, and the disconnecting means is controlled to disconnect the own device from the bus. As a result, the disconnecting means disconnects its own output from the parallel bus to the output line of the inverter device.
As a result, the malfunctioning machine among the plurality of inverter devices can reliably detect the occurrence of an internal short circuit accident, and can disconnect the own machine from the bus, thereby improving the reliability of the inverter system.

  Further, in the inverter device of the present invention, the control means compares the polarity of the output current of the inverter device detected by the current detection means with the polarity of the output voltage command value, and the polarity of the output current is the output When the polarity determination means outputs a signal indicating the level of the output current when the polarity is opposite to the voltage command value, the output signal of the polarity determination means is compared with an abnormality determination threshold value for determining abnormality, Continues until the level determination means for outputting an abnormality determination signal when the output signal of the polarity determination means exceeds the abnormality determination threshold, and the time when the abnormality determination signal output from the level determination means has been set in advance And a time detecting means for determining that an internal short circuit has occurred in the inverter device and driving the disconnecting means.

In the inverter device of the present invention having the above-described configuration, the polarity determination means compares the polarity of the output current of the inverter device detected by the current detection means with the polarity of the output voltage command value, and the polarity of the output current is the output When the polarity is opposite to the voltage command value, a signal indicating the level of the output current is output, and the level determination means compares the output signal of the polarity determination means with an abnormality determination threshold for determining abnormality, An abnormality determination signal is output when the output signal of the polarity determination means exceeds the abnormality determination threshold. When the abnormality determination signal output from the level determination unit by the time detection unit is continuously output until a preset time has elapsed, it is determined that an internal short circuit has occurred in the inverter device, and Drive the disconnection means.
As a result, the malfunctioning machine among the plurality of inverter devices can reliably detect the occurrence of an internal short circuit accident, and can disconnect the own machine from the bus, thereby improving the reliability of the inverter system.

Further, the inverter device according to the present invention is characterized in that the abnormality determination threshold is set to a level equal to or lower than a limit value of an output current of the inverter device.
Thereby, it is possible to determine whether or not an accident such as an internal short circuit accident has occurred in the inverter device within the range of the limit value of the output current of the inverter device.

In the inverter device of the present invention, the time for determining whether or not an internal short circuit is set in the time detection means is set within a time during which an instantaneous interruption occurring in the bus is allowed. Features.
As a result, when an internal short circuit accident occurs in the inverter device, the inverter device of the faulty machine is disconnected from the bus line within the time when the instantaneous interruption occurring in the bus line is allowed. Reliability can be improved.

The inverter system according to the present invention is characterized in that a plurality of the inverter devices described above are operated in parallel redundant operation with respect to a load.
As a result, an accident such as an internal short circuit of the inverter device can be reliably detected, the faulty machine can be disconnected from the bus, and an inverter system with improved reliability can be realized.

According to the inverter device of the present invention, an accident such as an internal short circuit of the inverter device can be reliably detected, and the own device can be disconnected from the bus.
According to the inverter system of the present invention, it is possible to reliably detect an accident such as an internal short circuit of the inverter device, disconnect the faulty machine from the busbar, and improve the reliability of the system.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing a configuration example of an inverter system using the inverter device of the present invention. In the inverter system shown in FIG. 1, the input terminals DCin of the inverter device (# 1) 1 and the inverter device (# 2) 2 are connected to a common DC power supply (DC power supply) 31, and the output terminal OUT is shared through the bus 3. It is an example connected to a load 32. The inverter devices 1 and 2 are operated in parallel redundancy to supply AC power to the load 32. The inverter devices 1 and 2 are voltage type inverter devices, and the inverter devices 1 and 2 have the same internal configuration. Three or more inverter devices may be provided.

  In FIG. 1, a power conversion device 11 in an inverter device (# 1) 1 is connected to a DC power source 31 via an input terminal DCin, and converts a DC power source into an AC power source by DC (Pulse Width Modulation) control (DC / (AC conversion). The power converter 11 is composed of a power element such as an IGBT (Insulated Gate Bipolar Transistor). When the power element is subjected to PWM control, the output AC voltage value, period (frequency), and phase are changed to other inverter devices. Control to synchronize with (bus voltage).

The AC output that has been DC / AC converted by the power converter 11 is supplied to the load 32 from the output terminal OUT.
Further, a current detector 12 and a disconnecting means 13 are provided on the output line connected to the bus 3 of the inverter device (# 1) 1.
The current detector 12 detects a current flowing through the output line of the inverter device (# 1) 1.
The disconnecting means 13 has a function of disconnecting the output of the inverter device (# 1) 1 from the bus 3. The disconnecting means 13 is constituted by, for example, a relay or a semiconductor switch.

  14 is a control circuit, and the control circuit 14 compares the polarity of the output current of the inverter device (# 1) 1 detected by the current detector 12 with the polarity of the output voltage command value given to itself. It is determined that an internal short-circuit has occurred in the own device when a current having a polarity opposite to the output voltage command value flows that exceeds the preset current value until a preset time elapses, and the own device (# 1 ) It has a function of controlling the disconnecting means 13 so as to disconnect 1 from the bus 3.

  The control circuit 14 determines the polarity of the output current of the inverter device (# 1) 1 detected by the current detector 12 and the polarity of the output voltage command value from the output control unit that outputs an output voltage command (not shown). The polarity comparator 141 that outputs a signal indicating the level of the output current when the polarity of the output current is opposite to the output voltage command value, and the abnormality determination of the output signal of the polarity comparator 141 A level comparator 142 that outputs an abnormality determination signal when the output signal of the polarity comparator 141 exceeds the abnormality determination threshold, and an abnormality determination signal output from the level comparator 142 A time detector for determining that an internal short circuit has occurred in the inverter device (# 1) and outputting a time detector 143 when the output continues until the preset time elapses; It is configured to include a.

The abnormality determination threshold set in the level comparator 142 is a reference value for determining the abnormality of the output of the polarity comparator 141, and is equal to or less than the output current limit value I _{LIM of} the inverter device (# 1) 1. Is set to the level of Thus, it is possible to determine whether or not an accident such as an internal short circuit accident has occurred in the inverter device within the range of the output current limit value I _LIM of the inverter device.

  Further, it is determined whether or not an internal short circuit is set in the time detector 143, and the current detector 12 detects an overcurrent during the time T for outputting the disconnection signal SR for driving the disconnection means 13. And the time required for driving the disconnecting means 13 by the time detector 143 and the voltage waveform and phase are shifted by π / 2 when the load 32 is an inductive load or a capacitive load. In order to avoid erroneous detection, the current detection time is determined in consideration of allowance.

  Further, this time T is set within a time during which an instantaneous interruption occurring on the bus 3 is allowed. As a result, when an internal short circuit accident occurs in the inverter device, the inverter device of the faulty machine is disconnected from the bus line within the time when the instantaneous interruption occurring in the bus line is allowed. Reliability can be improved.

  The current detector 12 is the current detection means of the present invention, the control circuit 14 is the control means of the present invention, the polarity comparator 141 is the polarity determination means of the present invention, and the level comparator 142 is the level determination means of the present invention. In addition, the time detector 143 corresponds to the time detection means of the present invention.

  In the above configuration, when the inverter device (# 1) 1 and the inverter device (# 2) 2 are in parallel redundant operation with respect to the load 32, an internal short circuit accident occurs in the inverter device (# 1) 1 at time t1. Suppose that an overcurrent flows through the output line of the inverter device (# 1) 1. Since the current I1 flowing through the output line is a current flowing from the inverter device (# 2) into the output line of the inverter device (# 1) 1, it has a polarity opposite to that of the voltage command value Vi. The current flowing into the output line of the inverter device (# 1) 1 is apparently detected by the current detector 12 as the output current of the inverter device (# 1) 1.

  The detection output of the current detector 12 (current flowing through the output line of the inverter device (# 1) 1) I1 (FIG. 2C) is input to the polarity comparator 141, and the polarity comparator 141 causes the current detector 12 to The polarity of the output current I1 of the inverter device (# 1) 1 detected by the above and the polarity of the output voltage command value Vi (FIG. 2A) from the output control unit that outputs an output voltage command (not shown) The polarity comparator 141 outputs a signal indicating the level of the output current I1 to the level comparator 142 when the polarity of the output current I1 is opposite to the output voltage command value Vi. Incidentally, the output voltage VINV of the inverter device (# 1) 1 is as shown in FIG.

The level comparator 142 compares the output signal of the polarity comparator 141 with an abnormality determination threshold value ± I _TH (−I _{TH in the} example shown in FIG. 2) for determining abnormality, and outputs the output signal of the polarity comparator 141. When the value exceeds the abnormality determination threshold, an abnormality determination signal is output to the time detector 143.

The time detector 143 generates an internal short circuit in the inverter device (# 1) when the abnormality determination signal output from the level comparator 142 is continuously output until a preset time T elapses. At time t2, the disconnection signal SR (FIG. 2D) is output to the disconnection means 13, and the disconnection means 13 is driven.
Disconnecting means 113 disconnects the output of inverter device (# 1) 1 from bus 3.

As described above, according to the inverter device according to the embodiment of the present invention, it is possible to reliably detect an accident such as an internal short circuit of the inverter device, and to disconnect the own device from the bus.
In addition, according to the inverter system according to the embodiment of the present invention, it is possible to reliably detect an accident such as an internal short circuit of the inverter device, disconnect the faulty machine from the bus, and improve the reliability of the system.
Further, it is not necessary to add a failure detection circuit, and the cost can be reduced.
Furthermore, the reliability can be improved by reducing the number of parts.

  Although the embodiment of the present invention has been described above, the inverter device of the present invention is not limited to the illustrated example described above, and various modifications can be made without departing from the scope of the present invention. Of course.

The block diagram which shows the structure of the inverter apparatus and inverter system which concern on embodiment of this invention. The signal waveform diagram of each part which shows operation | movement of the inverter apparatus which concerns on embodiment of this invention shown in FIG. The block diagram which shows the structure of the inverter system which carries out the parallel redundant operation of the conventional several inverter apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1-n ... Inverter device, 3 ... Bus, 4-1-4-n ... Relay, 11 ... Power converter, 12 ... Current detector, 13 ... Disconnection means, 14 ... Control circuit, 31 ... DC power supply, 32 ... Load, 141 ... Polarity comparator, 142 ... Level comparator, 143 ... Time detector

Claims (5)

An inverter device used for performing parallel redundant operation of a plurality of units,
Disconnecting means for disconnecting the output of the own device from the parallel bus to the output line of the inverter device;
Current detection means for detecting a current flowing in the output line of the inverter device;
The polarity of the output current of the inverter device detected by the current detection means is compared with the polarity of the output voltage command value given to the own device, and the current value set in advance until the time when the preset time elapses When a current having a polarity opposite to the voltage command value flows, it is determined that an internal short circuit has occurred in the own machine, and the control means for controlling the disconnection means to disconnect the own machine from the bus;
An inverter device comprising: The control means includes
The polarity of the output current of the inverter device detected by the current detection means is compared with the polarity of the output voltage command value. When the polarity of the output current is opposite to the output voltage command value, the output current Polarity determination means for outputting a signal indicating the level of
A level determination unit that compares an output signal of the polarity determination unit with an abnormality determination threshold for determining an abnormality, and outputs an abnormality determination signal when the output signal of the polarity determination unit exceeds the abnormality determination threshold;
When the abnormality determination signal output from the level determination means is continuously output until a preset time has elapsed, it is determined that an internal short circuit has occurred in the inverter device, and the disconnection means is Driving time detection means;
The inverter device according to claim 1, comprising: The inverter apparatus according to claim 2, wherein the abnormality determination threshold is set to a level equal to or less than a limit value of an output current of the inverter apparatus. Wherein the time for determining whether an internal short circuit that is set to the time detecting means, according to claim 2, characterized in that a short break occur bus is set in the time allowed Inverter device.   5. An inverter system comprising a plurality of the inverter devices according to claim 1 that are operated in parallel and redundant with respect to a load.

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