Patent Application
20080112135
High- and medium-voltage (e.g., greater than 2000 volts) power electronics assemblies, such as adjustable speed drives, often use groups of power transistors and diodes switched on and off in a predetermined timing sequence to supply the level and frequency of power desired. Because of the high voltage levels in which they operate (e.g., 3300 volts, 4500 volts, 6500 volts, etc.), and the associated levels of current, these devices tend to generate significant amounts of excess heat.
The devices 101 used in medium-voltage drive assemblies today do not have adequate voltage isolation between their terminals and their base to support the potential developed between their terminals and ground when the base is grounded. Accordingly, as shown in
This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features, essential features, or required advantages of the claimed subject matter, or in limiting the scope of the appended claims.
Within the cabinet 200 may be one or more power devices 201. These power devices have a high isolation capability from their terminals to their base. An example of such a device is the Mitsubishi Type CM400HG-66H IGBT, another power transistor or diode device in the medium-voltage range with high isolation (e.g., isolation voltage levels of 10.2 kv or more), or any other such high isolation power transistor or diode device. The devices 201 may be mounted on a grounded heat exchanger 202. Heat exchanger 202 may have a body made of any type of heat absorbing material, such as aluminum or other metal, and may be coupled to the devices 201 using heat transfer mounting materials, such as thermally conductive fasteners (e.g., metallic bolts, screws, etc.), adhesives and/or pastes. As the heat exchanger 202 can be grounded, it may be installed with one portion on the interior of the cabinet 200, and another portion external to the cabinet 200, such that the exchanger 202 forms part of a barrier between the cabinet 200 interior and external elements without the risk of electrical breakdown or shock due to inadvertent contact with personnel. To preserve this barrier, an moisture/contaminant seal may be placed at the junction between the exchanger 202 and the cabinet 200 wall, to prevent moisture and other contaminants from entering the cabinet 200 interior.
The exchanger 202 may have a plurality of heat dissipating, or radiating, elements 203 to help transfer heat from the exchanger 202 body to the air surrounding the exterior of the cabinet 200. The elements 203 may be, for example, heat-dissipating metallic fins (e.g., aluminum or other metal or metal alloy), radiator coils, or any other desired dissipating or radiating configuration that absorbs and transfers heat away from the devices 201 and to the air surrounding the eternal portion of the exchanger 202. The elements 203, and the exchanger 202 body, may be made of a heat-conducting material, such as aluminum, metal or metal alloy, and may also be corrosion resistant (e.g., stainless steel or other resistant material). One or more fans 204 may also be used to generate air flow around the exterior portion of the exchanger, and this air flow may serve to draw heat away from the devices 201 and into the exterior air.
The cabinet 200 may be coupled to an airflow housing 205 to guide the airflow through the heat dissipation elements 203 and to protect against certain outdoor elements (e.g., prevent precipitation from entering the airflow). Airflow housing 205 may be, for example, an air duct. The air flowing through dissipation elements 203 may be unfiltered air obtained directly from the outside environment, or it may pass through one or more filters 206 before reaching the elements 203 to remove external contaminants and to reduce the risk of animals/birds/insects interfering with the operation of the exchanger 202.
The airflow housing 205 and fan 204 are optional, however, and may be omitted if desired. For example, the heat exchanger 202 may simply have its external portion directly exposed to the outdoor elements. This may be advantageous, for example, in locations where the outdoor climate is cool enough such that additional cooling through forced air is unnecessary. In such a configuration, the exchanger 202 body and dissipation elements 203 may be made of corrosion-resistant metals and/or coated with corrosion- and contaminant-resistant material, to help prolong life.
Using one or more of the features and approaches described above, heat management in power devices may be effectively achieved. Although the description above provides illustrative examples and sequences of actions, it should be understood that the various examples and sequences may be rearranged, divided, combined and subcombined as desired. For example, steps and features described may be omitted, or additional steps and features may be added. Accordingly, although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.
