JP3215164B2 - Voltage source inverter device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a voltage type inverter device.
And Seki, in particular, the present invention provides protection of the voltage type inverter device,
Alternatively, it relates to a voltage source inverter device capable of a minimum number of current detectors used for the control.

[0002]

2. Description of the Related Art FIG. 7 is a diagram showing an arrangement of a conventional current detector in a voltage source inverter device. In the figure, reference numeral 1 denotes a DC power supply of a voltage source inverter device. The DC power supply is usually obtained by converting an AC power supply into a direct current by a rectifier circuit composed of a diode or the like and filtering by a capacitor.

[0003] Reference numeral 10 denotes a bridge circuit in an inverter device that converts DC to AC, and has a bridge configuration in which transistors 3a to 3f, which are self-extinguishing elements, and diodes 2a to 2f are connected in antiparallel, respectively. The control of the output voltage of the inverter device is performed by driving each of the transistors 3a to 3f by a PWM signal given from a control device (not shown).

[0004] 4 is a current detector provided on the DC side of the bridge circuit 10, 11, 12, and 13 are current detectors provided on the AC side of the bridge circuit 10, and 9 is an AC motor driven by an inverter device. The DC input current of the bridge circuit 10 and the AC output current of the bridge circuit 10 are detected by the current detectors 4, 11, 12, and 13, respectively.

[0005] 14 is a rectifier, 15 and 16 are resistors,
The AC signals output from the current detectors 11, 12, and 13 are converted to DC by the rectifier 14 and the resistors 15 and 16. 17
Is an absolute value circuit, which outputs an inverter output current converted into a direct current by the rectifier 14 and the resistors 15 and 16 to an absolute value signal 1.
Convert to 01. Reference numeral 18 denotes a priority circuit, and the current detector 4
Out of the current detection signals detected by the current detectors 11, 12, and 13 and converted into direct current by the rectifiers 14 and the resistors 15 and 16 to select and output a large signal. Reference numeral 8 denotes an overcurrent detector, which compares the output of the priority circuit 18 with the set value 104 and outputs an inverter abnormality signal 105.

In FIG. 1, a DC current flowing from a DC power supply 1 to a bridge circuit 10 is detected by a current detector 4 and supplied to a priority circuit 18. Also, bridge circuit 1
An AC current flowing from 0 to a load AC motor 9 (hereinafter referred to as a load 9) is detected by current detectors 11, 12, and 13, converted into a DC signal by a rectifier circuit 14, and resistors R15 and R16. , An absolute value is obtained and given to the priority circuit 18. The priority circuit 18 selects and outputs the larger one of the input current detection signals.

The output 103 of the priority circuit 18 is supplied to the overcurrent detector 8 and compared with a set value 104. The output 103 is supplied to an inverter current limiting circuit or the like (not shown) and used for limiting the current of the inverter device. When an overcurrent flows from the DC power supply 1 through the transistors 3 a to 3 f in the bridge circuit 10 and the load 9, or when a load short circuit occurs, the output of the current detectors 11, 12, and 13 becomes overcurrent via the priority circuit 18. The signal is supplied to a detector 8 to detect an overcurrent state or a load short circuit. Further, a ground fault overcurrent flowing from one phase of the load 9 to the ground is detected by one of the current detectors 11 to 13 provided for each phase of the bridge circuit 10.

Further, when an arcing state, that is, a so-called upper and lower arm short circuit, which occurs due to a failure of the transistors 3a to 3f, occurs, the current detected by the current detector 4 becomes an overcurrent state, and this detection signal is output to the priority circuit 18 To the overcurrent detector 8 to detect the arcing state.

[0009]

In the above-mentioned voltage type inverter device, the following can be considered as possible overcurrent modes. DC power supply 1 when PWM control is abnormal
And a general overcurrent mode flowing between the load 9 via the bridge circuit 10. A reflux mode of the AC motor current flowing through the load 9 and the upper and lower transistors and diodes in the bridge circuit 10. Upper and lower short-circuit mode caused by erroneous firing or breakage of one of the transistors 3a to 3f in the bridge circuit 10. Inverter DC power supply 1 plus or minus input line and bridge circuit 10
A ground fault mode that flows from the AC motor 9 of the load to the ground via the ground.

Conventionally, in order to protect the inverter device from all the above modes, as shown in FIG. 7, a current detector 4 for detecting a current on the DC side of the inverter device and an output side of the inverter device. It is necessary to provide the current detectors 11, 12, and 13 for detecting the currents of all the phases, and there is a disadvantage that the configuration of the inverter device is complicated and expensive. SUMMARY OF THE INVENTION The present invention has been made in order to improve the above-mentioned drawbacks of the prior art, and provides a voltage-type inverter device capable of detecting overcurrents in all the above modes by a minimum number of current detectors. The purpose is to:

[0011]

In order to solve the above-mentioned problems, the present invention provides a multi-phase bridge-connected diode.
Connect the bridge circuit and the switching element / bridge circuit in anti-parallel, and connect them to the DC side of the diode / bridge circuit.
Connect a DC power supply and switch the diode bridge circuit .
In a voltage- source inverter device in which the upstream side and the AC side of the switching element / bridge circuit are directly connected to the load, both the DC positive side line and the negative side line between the diode / bridge circuit and the switching element / bridge circuit are used as the primary side. a first current detector passed through, the diode
And a second current detector for detecting a current on the DC input side of the bridge circuit, and an output of the first and second current detectors.
A priority circuit to be supplied , and a signal having a larger output of the first and second current detectors is selected by the priority circuit;
The current in each conduction mode of the voltage type inverter device is detected.

[0012]

In a drive mode in which a current flows from a DC power supply to a load via a diode bridge circuit and a switching element / bridge circuit, or in a regenerative mode in which a current flows from a load to a DC power supply side, the current always flows through the second power supply. Since the current flows to the current detector, the current can be detected by this. In the freewheeling mode in which the energy stored in the load flows through the diode of the diode bridge circuit and the switching element of the switching element / bridge circuit, the current always flows through the DC between the diode bridge circuit and the switching element / bridge circuit. Because it flows to the plus side line or the minus side line, the first
The current can be detected by the current detector. Further, in an inverter device having a DC power supply composed of a commercial power supply having one wire grounded and a rectifier, if a ground fault occurs in one phase of the load, the ground fault current is always reduced to a diode bridge circuit as described above. Since the current flows through the DC plus line or the minus line between the switching element and the bridge circuit, the ground fault current can be detected by the first current detector.

[0013]

FIG. 1 is a view showing one embodiment of the present invention. In FIG. 1, the same components as those shown in FIG. 7 are denoted by the same reference numerals, and 1 is a voltage type inverter. DC power supply 2, 2 is a diode bridge circuit including diodes 2a to 2f, 3 is a transistor bridge circuit including transistors 3a to 3f, and diode bridge circuit 2 is provided as a flywheel diode of transistor bridge circuit 3. The diode bridge circuit 2 and the transistor bridge circuit 3 constitute an inverter unit. Similarly to the conventional example, the output voltage of the inverter device is controlled by a PWM signal supplied from a control device (not shown) by the transistors 3a to 3a.
This is performed by driving f.

Reference numeral 4 denotes a first current detector, which is provided on the DC stage before the diode bridge circuit 2 and the transistor bridge circuit 3, and has an output 102 connected to the diode 7. Reference numeral 5 denotes a second current detector, which connects the positive and negative connection lines of the diode bridge circuit 2 and the transistor bridge circuit 3 in common and serves as a primary input, and its output 101 'is rectified. Circuit 6 is provided.

Reference numeral 6 denotes a rectifier circuit for converting the output of the current detector 5 into a DC signal, 7 a diode that forms a priority circuit together with the rectifier circuit 6, and 8 a set value of the output of the priority circuit including the rectifier circuit 6 and the diode 7. This is an overcurrent detection circuit that detects an overcurrent as compared with 104. The output 103 of the priority circuit including the rectifier circuit 6 and the diode 7 is supplied to the overcurrent detector 8 and used as an output current limiting signal of the inverter device.

Reference numeral 9 denotes a load composed of an AC motor or the like, which is connected by directly connecting the diode bridge circuit 2 and the AC side of the transistor bridge circuit 3. FIGS. 2 to 6 are diagrams for explaining the respective flow modes in the embodiment shown in FIG. 1. The current detection method in this embodiment will be described with reference to FIGS.

FIG. 2 shows a conduction mode (drive mode) flowing from the DC power supply 1 through the transistor 3a to the load 9 and the transistor 3f. In this mode, no current flows in the diode bridge circuit 2, and in the current detector 5, the current flowing on the positive DC side and the current flowing on the negative DC side cancel each other out, and the output signal 101 'thereof.
Is “0”. On the other hand, since a current flowing on the negative DC side flows through the current detector 4, by detecting this current, an abnormal state occurring in the inverter device can be detected.

FIG. 3 shows a conduction mode (reflux mode) when the transistor 3a is on and the transistor 3f is off.
In this case, the energy stored in the inductance of the load 9 flows back through the transistor 3a, the winding 9 'in the load 9, and the diode 2a of the diode bridge circuit 2. In this mode, the current detector 5
Since only the DC plus current flows in the primary side of
The current detector 5 can it detect the current.

FIG. 4 shows a conduction mode (reflux mode) when the transistor 3f is on and the transistor 3a is off.
In this case, the inductance energy of the load 9 is returned through the transistor 3f, the winding 9 'of the load 9, and the diode 2f of the diode bridge circuit 2. In this mode, since the primary side of the current detector 5 has only the DC negative current flows, can it detect the current by the current detector 5.

FIG. 5 shows a conduction mode (regeneration mode) when the transistors 3a and 3f are turned off from the conduction mode of FIG. In this case, the inductance energy of the load 9 is equivalent to the diode bridge circuit 2
DC power supply 1 via the diodes 2c and 2d
The power is regenerated. In this mode, no current flows through the current detector 5, and the regenerative current is detected by the current detector 4.

FIG. 6 shows a conduction mode (ground fault mode) when a ground fault occurs on the input side of the load 9. In FIG. 1, the DC power supply 1 in FIG. 1 is shown by a commercial power supply 20, a rectifier 22, and a filter 23 so that the current path is clear. One line of the commercial power supply 20 is connected to the ground 21. As shown in the figure, when a ground fault occurs on the load 9 side,
The ground fault current flows from the commercial power supply 20 to the ground via the rectifier 22, the current detector 5, and the transistor 3a, as shown by the solid line in FIG. Further, as shown by a dotted line in FIG. 3, the current flows from the ground 21 to the ground 21 via the transistor 3d, the current detector 5, the current detector 4, the rectifier 22, and the commercial power supply 20. As is clear from the figure, the ground fault current always flows through the current detector 5 regardless of whether the current flows as shown by the solid line or the dotted line, so that the current detector 5 detects the ground fault current. can do.

As is apparent from FIGS. 2 to 6, the current detector 4 is provided on the DC side, and the positive connection line and the negative connection line of the diode bridge circuit 2 and the transistor bridge circuit 3 are connected in common. By providing the current detector 5 as the primary side input, the current in all the conduction modes shown in FIGS. 2 to 6 can be detected by the current detector 4 or the current detector 5. It is possible to cope with all possible overcurrent modes in the voltage-source inverter device.

In the above embodiment, an example in which a transistor is used as a switching element of an inverter device has been described. However, the present invention is not limited to the above embodiment, and may include an FET, an IGBT (insulated gate bipolar transistor).
lar Transister) and other known switching devices. Further, in the above embodiment, the example in which the AC motor is connected as the load of the inverter device has been described. However, the load of the inverter device in the present invention is not limited to the above embodiment, and the present invention The present invention can be applied to an inverter device having a load. Furthermore, in order to absorb the surge voltage of the transistor of the inverter device, it is effective to put the current detector 5 and the diode bridge circuit 2 in the same package, and the size can be reduced.

[0024]

As is apparent from the above description,
In the present invention, only two current detectors are provided,
It is possible to detect current in all conduction modes such as powering and regeneration of the voltage type inverter device, and to protect against accidents such as load short-circuits and ground faults in these conduction modes or to control current limit etc. be able to. Therefore, an inexpensive and compact inverter device can be provided, and its practical effect is extremely large.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 shows a current flow mode (drive mode) in the embodiment.
FIG.

FIG. 3 is an explanatory diagram of a current flow mode (recirculation mode 1) in the embodiment.

FIG. 4 is an explanatory diagram of a current flow mode (recirculation mode 2) in the embodiment.

FIG. 5 is a current flow mode (regeneration mode) in the embodiment.
FIG.

FIG. 6 is a diagram showing a current conduction mode (ground fault mode) in the embodiment.
FIG.

FIG. 7 is a diagram showing a conventional example.

[Explanation of symbols]

Reference Signs List 1 DC power supply 2 Diode bridge circuit 2a, 2b, 2c, 2d, 2e, 2f, 7 diode 3 Transistor bridge circuit 3a, 3b, 3c, 3d, 3e, 3f Transistor 4, 5, 11, 12, 13 Current detection Unit 6, 14 Rectifier circuit 8 Overcurrent detector 9 AC motor 9 'Winding in AC motor 10 Bridge circuit consisting of diode and transistor 15, 16 Current detection resistor 17 Absolute circuit 18 Priority circuit 20 Commercial power supply 21 Earth ground 22 Rectifier circuit 23 Filter

Claims (1)

(57) [Claims] 1. A diode having a polyphase bridge connection.
Connect the bridge circuit and the switching element / bridge circuit in anti-parallel, and connect them to the DC side of the diode / bridge circuit.
Connect the DC power source, a voltage source inverter apparatus connected to a load directly connected to AC side of the AC-side switching element bridge circuit of the diode bridge circuit, between the diode bridge circuit and the switching element bridge circuit a first current detector passed through a DC positive line and the negative side line both as a primary side of the diode
Second to detect the DC input side of the current over de bridge circuit
And the outputs of the first and second current detectors are
A priority circuit is provided for inputting, and the output of the first and second current detectors is set to a larger signal.
A voltage type inverter device, wherein a current in each conduction mode of the voltage type inverter device is detected by selecting a signal in the priority circuit .