Power converter module

Details Power converter module Power converter module

2001-11-05

2003-06-24

Sherry, Michael (Department: 2838)

Electric power conversion systems

Current conversion

With conductive support mounting

C363S132000, C363S147000, C257S691000, C257S724000, C307S147000, C307S150000, C327S565000, C361S730000

Reexamination Certificate

active

06584001

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to a power converter module in which optionally either a first input area designed to be connected to a first, predetermined electric potential or a second input area intended to be connected to a second predetermined electric potential can be electrically connected to an output area. The module includes at least one group of switches, where the minimum of one group of switches has two semiconductor switch units, each of which has a gate terminal. An input terminal of one of the semiconductor switch units is connected to the first input area and an input terminal of the other semiconductor switch unit is connected to the second input area, and each of the semiconductor switch units has an output terminal connected to the output area.
2. Description of the Related Art
These types of power converter modules are used, for example, in the devices called converters, which serve to excite multiphase electric motors such as those of the synchronous or asynchronous type. A schematic circuit diagram of a converter of this type for a three-phase electric motor is shown in FIG.
1
. It can be seen that the converter
10
shown there has three converter modules
12
,
14
,
16
. Each of the three motor phases
18
,
20
,
22
is excited by one of the converter modules
12
,
14
,
16
. Because the three modules
12
,
14
,
16
are identical to each other in principle, the basic design of the modules will be described below with reference to the converter module
12
.
The converter module
12
has, for example, four groups
24
,
26
,
28
,
30
of semiconductor switch units
32
,
34
, these groups being connected in parallel to each other. Each of the semiconductor switch units shown in the example consists of an IGBT (insulated gate bipolar transistor), serving as a so-called power switch element. Each of these IGBTs has a gate G, serving as the gate terminal, and emitter and collector terminals, which are to be connected to each other. The collector terminal of the IGBT
32
is connected conductively to the emitter terminal of the IGBT
34
. These two terminals C and E of the IGBTs
32
and
34
form the output terminals connected to the associated phase
18
. The emitter terminal E of the IGBT
32
forms the input terminal of its transistor and is connected conductively to the input side
36
, which is at the potential −V. In a corresponding manner, the collector terminal C of the IGBT
34
forms the input terminal of its transistor and is connected conductively to the input side
38
, which is at the potential +V. Depending on whether the potential +V or −V is to be applied to the phase
18
, one of the IGBTs
32
or
34
of the associated groups of switches
24
,
26
,
28
,
30
will be switched to the conducting state, while the other remains nonconducting. In this way, it is possible to reverse the polarity of the various motor phases as required. Several IGBTs must be connected in parallel especially because, in the case of powerful electric motors, the currents flowing through the system during operation are very high, reaching as much as 400 A, for example. The individual power switch elements such as IGBTs or even MOSFETs, however, are usually suitable for currents of up to only 50 A. By connecting several of these power semiconductor switch elements in parallel, therefore, it is possible to adapt the power conversion in a stepwise manner to the requirements of the concrete application.
Adapting the individual modules of a converter of this type to the prevailing requirements usually calls for the development of special circuits. This process includes the production of the appropriate printed-circuit boards, the substrates of which are usually made of ceramic, and the insertion of the various power transistors, these circuits being designed with the goal of minimizing the inductances and maximizing the thermal tie-in to the existing cooling systems. It is very expensive to develop modules of this type, but even with the use of very expensive materials such as the ceramic substrates and expensive fabrication techniques for inserting the individual power transistors, the end result is still an assembly which is susceptible to damage from the loads which occur during actual operation. Especially the alternating thermal loads associated with the switching processes can lead to fractures, a susceptibility which is also promoted by the vibrations which occur when such units are used in motor vehicles, for example. As a result of the internal inductances which are present, the problem of so-called over-voltage transients also occurs frequently when current is switched from one transistor to another.
SUMMARY OF THE INVENTION
It is the object of the present invention to provide a power converter module which can be produced at favorable cost and which offers improved operating characteristics at the same time.
According to the invention, the two semiconductor switch units of the minimum of one group of switches are positioned facing each other in such a way that at least the output terminals thereof are opposite each other.
Because the arrangement according to the invention is designed so that the distance between two semiconductor switch units is as short as possible, especially with respect to the current pathway extending from the first to the second input area, it is ensured that the inductances of these groups of switches, which can be referred to as half-bridges, are low. Orienting the individual units of a group of switches so that they are facing each other, furthermore, also makes it possible to “stack” several of these groups easily on top of each other, with the result that it becomes comparatively simple to design the substrate during the development process, and at the same time the overall arrangement becomes highly compact.
It is possible, for example, for each of the semiconductor switch units of the power converter module according to the invention to have a switch housing, for the connecting sides of the switch housings to be arranged facing each other, at least the output terminals being provided on these connecting sides of the housings, and for the switch housings of the two semiconductor switch units to be offset with respect to each other in a housing offset direction in such a way that the two output terminals face each other essentially without any offset in the housing offset direction.
The use of switch housings for the individual semiconductor switch units has the result that the essential switching elements of the units are protected within the housing and thus more effectively shielded from external influences, especially mechanical influences.
In a preferred embodiment of the present invention, it is possible to provide the gate terminal, a first contact area of a first contact terminal, and a second contact terminal on the connecting side of the housing of each semiconductor switch unit and also to situate the second contact terminal of one of the semiconductor switch units, i.e., the terminal serving as the unit's output terminal, opposite, and thus in electrical contact with, the first contact area of the first contact terminal of the other semiconductor switch unit, i.e., the area serving as at least part of its output terminal.
So that it is possible to make the most efficient possible use of the space which is available or required in the power converter module according to the invention, it is proposed that a second contact area of the first contact terminal be provided on the switch housing of the semiconductor switch unit, which second contact area is connected conductively to the first contact area; that the second contact area of the one semiconductor switch unit, i.e., the area serving as its input terminal, be connected conductively to the first input area; and that the second contact area of the other semiconductor switch unit, i.e., the area serving as part of its output terminal, be connected conductively to the output area.
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