JPH05284731A - Power converter - Google Patents

Abstract

PURPOSE:To simplify circuit structure and facilitate the lowering of inductance an keep the cutoff property high by making a plurality of IGBT elements share a snubber capacitor and a snubber resistor, in the upper arm, and making a plurality of IGBT elements share a snubber capacitor and a snubber resistor, also in the lower arm. CONSTITUTION:In an upper arm, this converter absorbs surge voltage by the route of a snubber capacitor 72 a snubber diode 13 while one IGBT element 11 is OFF, and discharges the electricity corresponding to the amount of leaped voltage by the rout of a snubber resistor 74 a snubber capacitor 72. Also while another IGBT element 31 in the same upper arm is OFF, it absorbs surge voltage by the route of the snubber capacitor 72 the snubber diode 13, and discharges the electricity corresponding to the amount of leaped voltage by the rout of the snubber resistor 74 the snubber capacitor 72. This way, the circuit structure is simplified by putting the lower arm in the same circuit wherein the IGBT elements 11 and 31 share the snubber circuit 72 and the snubber resistor 74.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulated gate bipolar transistor element (hereinafter referred to as an IGBT element).
The present invention relates to a power conversion device equipped with a snubber circuit.

[0002]

2. Description of the Related Art Conventionally, as a power converter having a snubber circuit using an IGBT element, a single-phase inverter having a structure as shown in FIG. 3 is known. That is, the snubber capacitors 12 and 32 and the snubber diode 1 are provided in the upper arm IGBT elements 11 and 31, respectively.
3, 33 and snubber resistors 14, 34 are respectively connected to the snubber circuits, the snubber capacitors 12, 32 are respectively connected to the snubber diodes 13, 32.
One end on the side opposite to the 33 side is connected to the collector side of each of the IGBT elements 11 and 31, the other end is connected to the anode side of each of the snubber diodes 13 and 33, and the cathode of each of the snubber diodes 13 and 33 is the IGBT element 11. ，
31 is connected to the emitter side of each, and snubber resistors 14 and 34 are connected between the connection point between the snubber capacitors 12 and 32 and the anodes of the snubber diodes 13 and 33 and the low potential side of the power supply line. .

On the other hand, the IGBT elements 21 and 41 of the lower arm
Each of them is connected to a snubber circuit composed of each of snubber capacitors 22, 42, each of snubber diodes 23, 43 and each of snubber resistors 24, 44. One end on the opposite side to the IGBT element 2
1, 41 are connected to the respective emitter sides, the other ends are connected to the respective cathode sides of the snubber diodes 23, 43, and the respective anodes of the snubber diodes 23, 43 are I
The snubber resistors 24 and 44 are connected to the collector sides of the GBT elements 21 and 41, and between the connection points of the snubber capacitors 22 and 42 and the cathodes of the snubber diodes 23 and 43 and the high potential side of the power supply line. It is connected. In addition, 90 is a filter capacitor and 91 is a load.

In the conventional power conversion device having such a structure, the snubber circuit operates as follows. Explaining a snubber circuit including the upper arm IGBT element 11, a substantially stable voltage is constantly applied to the filter capacitor 90, and the upper arm snubber capacitor 12 is connected to both ends of the filter capacitor 90 through the snubber resistor 14. Therefore, it is normally applied to the same power supply voltage as the voltage of the filter capacitor 90. Therefore, when the IGBT element 11 is turned on and the current is turned off, the snubber capacitor 1
The current that has flowed from the filter capacitor 90 to the IGBT element 11 up to then shifts to 2, so that the snubber capacitor 12 is charged, and the voltage jumps above the power supply voltage due to the inductance of the circuit. After that, when the IGBT element 11 is completely turned off, the voltage that has jumped up to that point is also reduced by the snubber resistor 14
Will be discharged through and will return to the power supply voltage again.

The above operation is performed by the IGB of the upper arm.
The snubber circuits for the T element 31 and the lower arm IGBT elements 21 and 41 are also independently performed.

[0006]

However, such a conventional power converter has the following problems.
That is, in the conventional power conversion device, since the snubber circuit for each of the IGBT elements is configured by using independent circuit elements, when the IGBT element becomes large in size, especially as a large-capacity inverter, Since the snubber circuit also becomes larger, the circuit configuration becomes complicated. On the other hand, in the power conversion device using the IGBT element, the parts other than the load must be extremely compact in order to reduce the inductance, but the snubber capacitor is added to each snubber circuit, which makes the structure compact. However, there is a problem that the main circuit space must be made large, and as a result, the inductance becomes large, and the cutoff characteristics of the IGBT element cannot be fully utilized.

The present invention has been made in view of the above-mentioned problems of the prior art, and by reducing the number of parts and simplifying the circuit structure, it is possible to reduce the inductance and to have a high-performance cutoff characteristic. It is an object to provide a power converter with high reliability.

[0008]

According to the present invention, in a power converter having a snubber circuit using an IGBT element, a snubber capacitor and an upper arm common to the upper arm IGBT elements are provided for a plurality of upper arm IGBT elements. A snubber circuit is composed of a snubber diode for each element and a snubber resistor common to each upper arm element, and one end of the snubber capacitor opposite to the snubber diode side is connected to the collector side of the IGBT element of each upper arm, and the other. One end of each of the upper arms is connected to the anode side of each snubber diode of each element, and the cathode side of each snubber diode of each element is connected to the emitter side of each IGBT element of each of the upper arms to connect the snubber capacitor and each snubber diode. Each element of the upper arm is connected between the node of the diode and the low potential side of the power line. Connect a common snubber resistor, and for multiple lower arm IGBT elements, create a snubber circuit with a snubber capacitor common to each lower arm element, a snubber diode individual to each lower arm element, and a snag resistor common to each lower arm element. One end of the snubber capacitor opposite to the snubber diode is connected to the IG of each lower arm.
The other side is connected to the emitter side of the BT element and the other end is connected to the cathode side of the snubber diode for each element of the lower arm, and the anode side of the snubber diode for each element is connected to the collector side of the IGBT element of each of the lower arms. And a snubber resistor common to the lower arm elements is connected between the connection point between the snubber capacitor and the cathode of each snubber diode and the high potential side of the power supply line.

[0009]

In the power converter of the present invention, the upper arm has one
When the two IGBT elements are turned off, the surge voltage is absorbed by the route of the snubber capacitor-snubber diode, and the voltage jump is discharged by the route of the snubber resistor-snubber capacitor. Even when one of the other IGBT elements in the same upper arm is turned off, the surge voltage is absorbed in the same snubber capacitor-snubber diode route, and the voltage jump is discharged in the snubber resistor-snubber capacitor route. In this way, multiple IGBTs can be
The element shares the snubber resistance with the snubber capacitor.

The lower arm also operates symmetrically with the upper arm, and the plurality of IGBT elements in the lower arm share the snubber capacitor and the snubber resistor.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 shows, as an embodiment of the present invention, a circuit configuration of a power converter for a single-phase inverter, and a snubber capacitor 72 common to the two upper arm IGBT elements 11 and 31 is provided. And snubber diodes 13 and 33 individually for each element and a snubber resistor 74 common to each element
Constitutes a snubber circuit, and one end of the common snubber capacitor 72 opposite to the snubber diodes 13 and 33 is connected to the collector side of each of the IGBT elements 11 and 31.
The other end has snubber diodes 13 and 33 for individual devices.
Connected to each anode side, each cathode side of each snubber diode 13, 33 of each element is IGBT
A snubber resistor 74, which is connected to the emitter side of each of the elements 11 and 31 and is connected between the snubber capacitor 72 and the common anode of the snubber diodes 13 and 33 and the low potential side of the power supply line, is used between the upper arm elements. It is connected.

Further, the two lower arm IGBT elements 2
Snubber capacitor 8 common to each element for 1 and 41
2, a snubber diode 23, 43 for each element, and a snubber resistor 84 common to each element constitute a snubber circuit,
Snubber diode 2 of common snubber capacitor 82
One end on the side opposite to the 3,43 side is connected to the emitter side of each IGBT element 21, 41 of the lower arm, and the other end is connected to the cathode side of each snubber diode 23, 43 for each element individually. Snubber diode 23,
The anode side of each 43 is connected to the collector side of each of the IGBT elements 21 and 41, and is connected between the connection point between the common snubber capacitor 82 and the common cathode of the snubber diodes 23 and 33 and the high potential side of the power supply line. A snubber resistor 84 common to the arm elements 21 and 41 is connected.

Reference numeral 90 is a filter capacitor, and 91 is a load.

Next, the operation of the power converter having the above configuration will be described.

The filter capacitor 90 maintains a substantially stable voltage, and due to the inductance of the circuit, the IGBT
The surge voltage generated at the time of T element switching is IGBT
It is absorbed by a snubber circuit connected in parallel with the device.

Now, when the current is flowing in the route of the filter capacitor 90-IGBT element 11-load 91-IGBT element 41-filter capacitor 90, if the IGBT element 11 of the upper arm is turned off, the IGBT element 11 until then. The current flowing through the route shifts to the route of the snubber capacitor 72-snubber diode 13. This allows
The snubber capacitor 72 includes a filter capacitor 90.
Overcharged above the voltage stored in. This is a filter capacitor 90-IGBT element 11-load 91-
This is due to the influence of the inductance of the wiring in the path between the IGBT element 41 and the filter capacitor 90.

Further, the overcharged charges are the snubber capacitor 72, the filter capacitor 90, and the snubber resistor 7.
The loop of the 4-snubber capacitor 72 is discharged to the original power supply voltage.

Even when the other IGBT element 31 of the upper arm is turned off, the snubber capacitor 72 absorbs the surge voltage applied to the IGBT element 31 through the snubber diode 33, and the subsequent discharge also causes the IGBT element 1 to discharge.
Similar to when 1 is turned off, a loop of snubber capacitor 72-filter capacitor 90-snubber resistor 74-snubber capacitor 72 is performed.

On the other hand, also in the lower arm, similarly to the upper arm, the surge voltage is absorbed and the overcharged electric charge of the filter capacitor 90 is discharged through the snubber capacitor 82 and the snubber resistor 84 common to the two IGBT elements 21 and 41.

Thus, in the power converter having a plurality of snubber circuits on the upper and lower sides, the snubber capacitor and the snubber resistor can be shared by the upper arm and the lower arm, respectively, and the number of circuit elements can be reduced and simplified. It is possible to reduce the inductance of the circuit.

FIG. 2 shows, as another embodiment of the present invention, a circuit configuration of a power converter for a three-phase inverter. This embodiment differs from the first embodiment in FIG. 1 in that the upper arm side is provided with an IGBT element 51 in addition to the IGBT elements 11 and 31, and the collector side of these is connected to a common snubber capacitor 72, An IGBT element 61 is provided on the side in addition to the IGBT elements 21 and 41, and the emitter side of these is connected to a common snubber capacitor 82.

Further, in addition to the snubber diodes 13, 23, 33, 43 for each snubber circuit, snubber diodes 53, 63 corresponding to the IGBT elements 51, 61 are provided, and the snubber diodes 13, 33, 53 of the upper arm are provided.
Each anode is commonly connected to the snubber capacitor 72, a snubber resistor 74 is connected between the connection point and the low potential side of the power supply line, and the cathodes of the snubber diodes 23, 43, 63 of the lower arms are commonly connected. It is connected to the snubber capacitor 82, and a snubber resistor 84 is connected between the connection point and the high potential side of the power supply line. In addition, 92 is a three-phase load.

Even in the power converter of this three-phase inverter, the snubber capacitors 72 and 8 having the same surge voltage of the upper and lower IGBT elements as in the first embodiment.
2. It is absorbed through the snubber resistors 74 and 84 to discharge the overcharged electric charge of the filter capacitor 90.

In this way, in the power converter having a plurality of snubber circuits on the upper and lower sides, the snubber capacitor and the snubber resistor can be shared by the upper arm and the lower arm, respectively, and the number of circuit elements can be reduced and simplified. It is possible to reduce the inductance of the circuit.

[0026]

As described above, according to the present invention, the snubber capacitor and the snubber resistor are shared by the upper and lower arms, and only the snubber diode is individually provided in correspondence with each IGBT element. The number can be reduced, the circuit can be simplified, and the size and the inductance can be easily reduced. Further, since the inductance can be reduced, the cutoff characteristics of the IGBT element can be improved and the reliability of the operation can be improved.

[Brief description of drawings]

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

FIG. 2 is a circuit diagram of another embodiment of the present invention.

FIG. 3 is a circuit diagram of a conventional example.

[Explanation of symbols]

11,21,31,41,51,61 IGBT element 13,23,33,43,53,63 Snubber diode 72,82 Snubber capacitor 74,84 Snubber resistor 90 Filter capacitor 91,92 Load

Claims (1)

[Claims] 1. A power converter having a snubber circuit using an insulated gate bipolar transistor (IGBT) element, wherein a snubber capacitor common to each of the upper arm insulated gate bipolar transistor elements is provided. And a snubber diode for each element of the upper arm and a snubber resistor common to each element of the upper arm constitute a snubber circuit, and one end of the snubber capacitor is connected to the collector side of the insulated gate bipolar transistor element of each upper arm, One end of each of the upper arms is connected to the anode side of the snubber diode of each element, and the cathode side of each snubber diode of each element is connected to the emitter side of the insulated gate bipolar transistor element of each of the upper arms. Capacitor and each snubber diode Connect a snubber resistor common to each element of the upper arm between the connection point with the node and the low potential side of the power supply line. A snubber circuit is composed of a capacitor and a snubber diode for each element of the lower arm and a snubber resistor common to each element of the lower arm, and one end of the snubber capacitor is connected to the emitter side of the insulated gate bipolar transistor element of each of the lower arms, The other end is connected to the cathode side of the snubber diode of each element of the lower arm, the anode side of the snubber diode of each element is connected to the collector side of the insulated gate bipolar transistor element of each of the lower arms, The connection point between the snubber capacitor and the cathode of each snubber diode and the power supply line Power converter formed by connecting a common snubber resistors each lower arm element between the high potential side of the emission.