Electric power conversion systems – Current conversion – Integrated circuit
Reexamination Certificate
2001-09-06
2002-12-03
Riley, Shawn (Department: 2838)
Electric power conversion systems
Current conversion
Integrated circuit
Reexamination Certificate
active
06490187
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates in general to semiconductor devices for electric power conversion using semiconductor switching elements and, in more particular, to a technique for suppressing occurrence of rapid potential variation or “jump-up” of voltages during switching operations while reducing the device in size or dimension.
In recent years, electric power conversion devices employing high-speed semiconductor switching elements typically including insulated-gate bipolar transistors (IGBTS) have been used in a wide variety of technical fields. As the capacity increases, the power converter devices are in many cases configured from a converter and more than one smoothing capacitor plus an inverter rather than a mere rectifier circuit in order to let electrical power “reincarnate” to the power supply.
As one example of such approach, the circuit configuration of a three-phase power converter apparatus such as a variable frequency power supply is shown in FIG.
3
. In brief, a converter
3
and an inverter
4
are connected together via a group of smoothing capacitors
1
. The converter
3
is generally constituted from IGBT modules
311
-
323
and conductors
331
-
363
for connection therebetween.
In addition, the IGBT modules
311
-
323
are each formed of a switching element (here, IGBT) and a diode operatively associated therewith. The positive polarity-side conductors
331
-
333
are connected through a common conductor
21
a
to a conductor
21
for connecting capacitors— positive polarities together via a common conductor
37
. Similarly the negative polarity-side conductors
341
-
343
are connected through a common conductor
22
a
to a conductor
22
for connecting the capacitors' negative polarities together via a common conductor
38
. As in the converter
3
, the inverter
4
is similarly constituted from IGBT modules
411
-
423
and conductors
431
-
463
, wherein positive polarity-side conductors
431
-
433
are connected through a common conductor
21
b
to a conductor
21
for connecting the capacitors' positive polarities together via a common conductor
47
. Similarly negative polarity-side conductors
441
-
443
are connected via a common conductor
22
b
to a conductor
22
for connecting the capacitors' negative polarities together by a common conductor
48
. Although not specifically shown in the drawing, an alternate current (AC) power supply part is connected to the converter
3
via AC conductors
361
-
363
whereas a load, such as a motor, is coupled to the inverter
4
via AC conductors
461
-
463
.
In the power converter device thus arranged, a voltage can potentially jump up in turn-off events due to an energy being accumulated upon power-up or electrization to the lead wire inductance of circuitry. If this “jump-up” voltage potentially goes beyond the inherent withstanding or breakdown voltage level of switching elements, then the elements might lead to destruction; thus, an attempt is made to suppress such voltage jump-up by connecting a snubber circuit, although not shown in FIG.
3
. Unfortunately the use of such snubber circuit serves as a bar to achievement of the device downsizing; thus, it is important to suppress or minimize the lead wire inductance of the circuit. In order to suppress such circuit lead wire inductance, a variety of approaches have been employed until today including, but not limited to, a technique for using a multilayer conductor structure with reverse-direction currents opposing each other.
One example is disclosed in Japanese Application Patent Laid-Open Publication No. Hei 08-19245, wherein the lead wire inductance is reduced by arranging a group of semiconductor switching elements and a capacitor group so that all of them are arranged by a multilayered conductor.
However, in cases where the power converter device further increases in size resulting in a likewise increase in parallel array number of capacitors and/or an increase in dimensions of switching elements, the multilayer conductor per se is made larger in size, which leads to difficulties in the manufacture of such multilayer conductor while at the same time increasing workloads for connection to respective terminals during conductor connection processes, resulting in unwanted increases in production costs.
SUMMARY OF THE INVENTION
The prior art electric power conversion device made up from a plurality of semiconductor switching elements and a plurality of capacitors in the way stated above is encountered with a problem that unwanted increases in costs in conductor manufacturing parts assembly processes occur due to inductance reduction for suppression of a rapidly potentially varying or “jump-up” voltage in accordance with an increase in capacity of the power conversion device.
It is therefore a primary object of the present invention to provide a semiconductor electric power conversion device preferably adapted to achieve inductance reduction by use of conductors of simplified structure to thereby suppress any possible jump-up voltages.
To attain the foregoing object the instant invention provides an improved semiconductor electric power conversion device including a converter unit and an inverter unit each having a group of parallel-connected capacitors and a plurality of positive polarity side switching elements being connected to a positive polarity terminal of the capacitor group plus a plurality of negative polarity side switching elements as connected to a negative polarity terminal of the capacitor group, wherein the device comprises a first connection section for connecting together a first conductor being connected to the positive terminal of the capacitor group and a second conductor as connected to the positive polarity of the positive polarity side switching elements making up the inverter and a second connection section for connecting thereto a third conductor as connected to the positive polarity of the positive polarity side switching elements making up the inverter, and a third connection section for connecting together a fourth conductor being connected to the negative terminal of the capacitor group and a fifth conductor as connected to the negative polarity of the negative polarity side switching elements making up the converter and a fourth connection section for connecting thereto a sixth conductor as connected to the negative polarity of the negative polarity side switching elements constituting the inverter, and wherein the first conductor and the fourth conductor are formed to have a multilayer structure while letting the second conductor and fifth conductor be formed into a multilayer structure with the third conductor and sixth conductor being formed into a multilayer structure.
It should be noted here that respective capacitors making up the capacitor group are on the same plane while disposing the first connection section and the third connection section on the same side with respect to an infinite plane containing therein a line segment coupling together at least two terminals of the terminals of the capacitor group and being at right angles to the aforesaid plane and also disposing the second connection section and the fourth connection section be disposed at the opposite side thereto, wherein the first to fourth connection sections have a plurality of subdivided connection conductors with the first connection section and the third connection section being disposed in close proximity to each other in the state that these are electrically isolated from each other and also with the second connection section and fourth connection section being disposed adjacent to each other in the state that these are electrically isolated from each other.
In addition, respective capacitors making up the capacitor group are all the same in shape and are disposed in the same direction.
Additionally, the subdivided connection conductors of the first to fourth connection sections are all the same in width.
Additionally the connection conductors of the first connection section and the second connection s
Fukuda Satoshi
Kishikawa Takao
Koyanagi Asako
Mine Toshisuke
Mori Kazuhisa
Crowell & Moring LLP
Hitachi , Ltd.
Riley Shawn
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