JP4765550B2 - Inverter circuit - Google Patents

Description

  The present invention relates to downsizing of a snubber circuit in an inverter circuit, particularly an inverter circuit provided with a snubber circuit.

  FIG. 4A is a circuit diagram for one phase of an inverter circuit provided with a conventional snubber circuit, where 1 is a DC positive terminal, 2 is a DC negative terminal, and 3 is an AC output terminal. Further, 4 is connected to the upper arm 5 between the positive terminal 1 and the AC output terminal 3, and the IGBT, which is a semiconductor switching element constituting the inverter, 6 is the lower arm between the AC output terminal 3 and the negative terminal 2. 7, IGBTs 8, 9 which are switching elements constituting the inverter are capacitors and diodes connected in series with each other, and this series circuit is connected in parallel between the emitter and collector terminals of the IGBT 4. Similarly, the capacitor 10 and the diode 11 are connected in series with each other, and this series circuit is connected in parallel to the IGBT 6. A discharge resistor 12 is connected between the connection point of the capacitor 8 and the diode 9 and the negative electrode terminal 2, and a discharge resistor 13 is connected between the connection point of the capacitor 10 and the diode 11 and the positive electrode terminal 1. .

  In the inverter circuit shown in FIG. 4A, the IGBTs 4 and 6 are turned on alternately, and, for example, the pulse voltage-modulated AC voltage is output from the AC output terminal 3 by changing the ON period. Here, for example, if a current flows through the IGBT 4 and the current is cut off, a surge voltage is generated at both ends of the IGBT 4 due to the floating inductance of the circuit. Therefore, a snubber circuit is provided to suppress this voltage. The snubber circuit is composed of, for example, a capacitor 8, a diode 9, and a resistor 12, and the current interrupted by the IGBT 4 flows into the snubber circuit, thereby suppressing overvoltage. Similarly, for the IGBT 6, a snubber circuit is configured by the capacitor 10, the diode 11, and the discharge resistor 13.

In addition, there exists patent documents 1-4 as prior art document information relevant to the invention of this application.
Utility Model Registration No. 2502637 JP-A-7-16591 JP-A-9-190901 JP 2001-307902 A

  By the way, the capacitor 8 and the diode 9 and the capacitor 10 and the diode 11 constituting the snubber circuit may be integrated modules 14 and 15 for the purpose of space saving and low inductance wiring, and the surge voltage suppression effect is improved. Therefore, as shown in FIG. 4B, the terminals 14a and 15a of the integrated modules 14 and 15 may be directly attached by screws 16 to the terminals 4a and 6a of the IGBTs 4 and 6 which are semiconductor switching elements. In addition, as the semiconductor switching elements 4 and 6 increase in withstand voltage, increase in current, and increase in frequency, the loss of the snubber circuit, particularly its diode, increases, and its heat generation (heat dissipation) often becomes a problem. In this case, a countermeasure may be taken by attaching a cooling fin to the diode, but the size of the device cannot be reduced because the cooling fin becomes large or a cooling fan is required separately. Reference numeral 17 denotes a water-cooling fin to which the IGBTs 4 and 6 are attached and cools the heat generated therein, and the cooling water flows therethrough.

  The present invention has been made to solve the above problems, and in an inverter circuit provided with a snubber circuit, the snubber circuit can be miniaturized and the effect of suppressing a surge voltage can be improved. The purpose is to obtain.

According to a first aspect of the present invention, there is provided an inverter circuit comprising: a semiconductor switching element that constitutes the inverter circuit; and a snubber circuit that includes a capacitor, a diode, and a discharge resistor and that suppresses a switching surge voltage. The element is attached to the upper part of the water-cooling fin through which cooling water flows, and the capacitor and diode of the snubber circuit are made into an integrated module, the terminal of the integrated module is attached to the terminal of the semiconductor switching element, and the diode is mounted insulated on end of the heat conductor, in which the lower end of該良thermal conductor attached to the water-cooled fins.

The inverter circuit according to claim 2, in each of the semiconductor switching elements constituting the inverter circuit, a capacitor, a diode and a discharge resistor, the inverter circuit connected suppressing snubber circuit switching surge voltage, each of the semiconductor switching elements At the top of the water cooling fin through which the cooling water is passed, a snubber circuit capacitor and a diode are integrated into a unitary module, and the terminal of the unitary module is attached to the terminal of the semiconductor switching element . Insulation is attached to the lower surface, and a water-cooling resistance casing having cooling water flowing inside and having a snubber circuit discharge resistance is attached to the upper surface of the good heat conductor.

An inverter circuit according to claim 3 is an inverter circuit in which each semiconductor switching element constituting the inverter circuit is connected to a snubber circuit that includes a capacitor, a diode, and a discharge resistor and suppresses a switching surge voltage. The switching element is made into one package, and the capacitor and the diode of the snubber circuit of the two semiconductor switching elements are attached to the terminals of the package of the two semiconductor switching elements as an integrated module, and the diode is made of a good heat conductor. Insulation is attached to the lower surface , and a water-cooling resistance casing having cooling water flowing inside and having a snubber circuit discharge resistance is attached to the upper surface of the good heat conductor.

  As described above, according to the first aspect of the present invention, the diode in the integrated module of the capacitor and the diode of the snubber circuit is attached to the water-cooling fin for cooling the semiconductor switching element through the good thermal conductor. The heat is effectively cooled by water-cooled fins, and it is not necessary to separately provide a large cooling fin, and the snubber circuit can be miniaturized. In addition, since the integrated module is attached to the terminal of the semiconductor switching element, the inductance of the wiring of the snubber circuit can be reduced, the size can be reduced, and the surge voltage can be suppressed.

  According to a second aspect of the present invention, the diode in the integrated module of the snubber circuit capacitor and diode is attached to the water-cooled resistance housing through the good heat conductor, and the heat of the diode is transferred to the water-cooled resistance housing. The body can be effectively cooled, and it is not necessary to separately provide a large cooling fin, and the snubber circuit can be downsized. In addition, since the water-cooled resistance housing has a discharge resistance, the capacitor, diode and discharge resistance of the snubber circuit can be integrated, the space can be reduced, and the size can be reduced. . Furthermore, since the integrated module is attached to the terminal of the semiconductor switching element, the inductance of the snubber circuit wiring can be reduced, the size can be reduced, and the surge voltage can be suppressed.

  According to claim 3, the capacitor and the diode of the snubber circuit of the two semiconductor switching elements are made into an integrated module, and it is possible to reduce the size in a space-saving manner, and to reduce the inductance of the wiring of the snubber circuit, The surge voltage suppression effect can be improved. In addition, the diode in the integrated package is attached to the water-cooled resistance housing having a discharge resistance through a good heat conductor, so that the heat of the diode can be effectively cooled by the water-cooled resistance housing. There is no need to provide cooling fins, and the size can be reduced. Furthermore, a capacitor, a diode, and a discharge resistor constituting the snubber circuit of two IGBTs are integrally formed, and the space can be reduced in size. In addition, since the integrated module is connected to the terminal of two semiconductor switching elements in one package, the inductance of the wiring of the snubber circuit can be reduced, and space saving and miniaturization are possible, and surge suppression is possible. The effect can be improved.

Best Embodiment 1
The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a partial configuration diagram of an inverter circuit according to the first embodiment of the present invention. Each of the IGBTs 4 and 6 (meaning 4 or 6 and the same applies hereinafter) is water-cooled in which cooling water is passed through. The snubber circuit that is attached to the fin 17 and suppresses the switching surge voltage of the IGBTs 4 and 6 is composed of capacitors 8 and 10, diodes 9 and 11, and discharge resistors 12 and 13 as in the prior art. 10 and diodes 9 and 11 are integrated modules 14 and 15, and their terminals 14 a and 15 a are attached to terminals 4 a and 6 a of IGBTs 4 and 6 by screws 16. The discharge resistors 12 and 13 of the snubber circuit are provided separately. Good heat conductor diode 9,11 in the integrated module 14, 15 (by conductors like.) 18 mounted on the end and insulation, under end of the good heat conductor 18 is attached by screws 19 to the water-cooled fins 17 .

  In the first embodiment, the diodes 9 and 11 are connected to the water-cooled fins 17 via the good heat conductor 18, and the heat of the diodes 9 and 11 can be effectively cooled by the water-cooled fins 17. For this reason, it is not necessary to provide a large cooling fin, and the size can be reduced. In addition, since the terminals 14a and 15a of the integrated modules 14 and 15 are connected to the terminals 4a and 6a of the IGBTs 4 and 6, the inductance of the snubber circuit wiring can be reduced, miniaturization is possible, and surge suppression is possible. An effect can be obtained.

Embodiment 2
FIG. 2 is a partial configuration diagram of an inverter circuit according to the second embodiment, in which the diodes 9 and 11 of the integrated modules 14 and 15 are insulated and attached to the lower surface of a good heat conductor 20 made of a conductor or the like. On the upper surface of the body 20, a cooling water flow is provided, and a water-cooled resistance housing 21 having discharge resistances 12 and 13 of a snubber circuit is attached. The water-cooled resistance casing 21 is commercially available, and the discharge resistors 12 and 13 are attached to the casing 21. Other configurations are the same as those of the first embodiment.

  In the second embodiment, the diodes 9 and 11 are attached to the water-cooled resistance casing 21 via the good heat conductor 20, and the heat of the diodes 9 and 11 is effectively cooled by the water-cooling resistance casing 21. Therefore, it is not necessary to provide a large cooling fin, and the size can be reduced. In the first embodiment, it is necessary to separately provide the snubber circuit discharge resistors 12 and 13 and a space for this is required. In the second embodiment, however, the snubber circuit capacitors 8 and 10 and the diode 9 are used. 11 and the discharge resistors 12 and 13 are integrally formed, the space can be reduced and the size can be reduced. Furthermore, since the terminals 14a and 15a of the integrated modules 14 and 15 are connected to the terminals 4a and 6a of the IGBTs 4 and 6, the inductance of the snubber circuit wiring can be reduced, miniaturization is possible, and surge suppression is possible. An effect can be obtained.

Embodiment 3
FIG. 3 is a partial configuration diagram according to the third embodiment, and shows two IGBTs 4 connected to the upper and lower arms 5 and 7 of the inverter circuit (meaning 5 and 7 and the same applies in the third embodiment). , 6 and the capacitors 8 and 10 and the diodes 9 and 11 constituting the snubber circuit connected to the terminal 22a are attached to the terminal having the IGBTs 4 and 6 as one package. The diodes 9 and 11 are attached to the lower surface of the good heat conductor 23 made of a conductor, and a commercially available water-cooled resistance case 21 is attached to the upper surface of the good heat conductor 23 , and the discharge resistance 12 is attached to the case 21. , 13 are attached.

  In the third embodiment, the capacitors 8 and 10 and the diodes 9 and 11 of the snubber circuit of the two IGBTs 4 and 6 are integrated into the integrated module 22, which can be reduced in space and can be reduced, and the wiring inductance of the snubber circuit can be reduced. Can be reduced, the size can be reduced, and the surge voltage can be suppressed. Further, the diodes 9 and 11 in the integrated package 22 are attached to the water-cooled resistance casing 21 having the discharge resistors 12 and 13 via the good heat conductor 23, and the heat of the diodes 9 and 11 is transferred to the water-cooling resistance casing. 21 can be effectively cooled, and it is not necessary to provide a large cooling fin, and the size can be reduced. Further, the capacitors 8 and 10, the diodes 9 and 11 and the discharge resistors 12 and 13 constituting the snubber circuit of the two IGBTs 4 and 6 are integrally formed, so that the space can be reduced and the size can be reduced. Furthermore, since the terminals 22a of the integrated module 22 are connected to the terminals of the IGBTs 4 and 6 in one package, the inductance of the snubber circuit wiring can be reduced, and the size can be reduced in a space-saving manner. The surge suppression effect can be improved.

It is a partial block diagram of the inverter circuit by Embodiment 1 of this invention. It is a partial block diagram of the inverter circuit by Embodiment 2. It is a partial block diagram of the inverter circuit by Embodiment 3. It is the circuit diagram and partial block diagram for 1 phase of the inverter circuit provided with the conventional snubber circuit.

Explanation of symbols

4, 6 ... IGBT
4a, 6a, 14a, 15a, 22a ... terminal 5, 7 ... arm 8, 10 ... capacitor 9, 11 ... diode 12, 13 ... discharge resistance 14, 15, 22 ... integrated module 17 ... water-cooled fins 18, 20, 23 ... good thermal conductor 21 ... water-cooled resistance housing

Claims (3)

In an inverter circuit in which a snubber circuit composed of a capacitor, a diode and a discharge resistor is connected to each semiconductor switching element constituting the inverter circuit, and a cooling water is passed through each semiconductor switching element. of is attached to the upper, the capacitor and the diode of the snubber circuit is an integrated module, attaching a terminal of the integrated module to the terminals of the semiconductor switching element, and mounted in insulating the diode upper end of the good heat conductor, inverter circuit, characterized in that attached to the water cooled fin under end of該良heat conductor. In an inverter circuit in which a snubber circuit composed of a capacitor, a diode and a discharge resistor is connected to each semiconductor switching element constituting the inverter circuit, and a cooling water is passed through each semiconductor switching element. And a snubber circuit capacitor and diode as an integrated module, the terminal of the integrated module is attached to the terminal of the semiconductor switching element, and the diode is insulated and attached to the lower surface of the good thermal conductor. An inverter circuit, characterized in that a water-cooled resistance housing having cooling water flowing therein and having a discharge resistance of a snubber circuit is attached to the upper surface of the heat conductor. In an inverter circuit in which each semiconductor switching element constituting the inverter circuit is connected to a snubber circuit that includes a capacitor, a diode, and a discharge resistor and suppresses a switching surge voltage, the two semiconductor switching elements of the upper and lower arms are combined into one package. The capacitor and the diode of the snubber circuit of the two semiconductor switching elements are attached to the terminals of the package of the two semiconductor switching elements as an integrated module, and the diode is insulated and attached to the lower surface of the good heat conductor. An inverter circuit, characterized in that a water-cooled resistance housing having cooling water flowing therein and having a discharge resistance of a snubber circuit is attached to the upper surface of the heat conductor.

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