FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
&
PATENTS RULES, 2006
COMPLETE SPECIFICATION (SECTION 10; RULE 13)
"IMPROVEMENTS IN HEAT DISSIPATION OF CAPACITORS IN POWER
ELECTRONICS"
ALCON ELECTRONICS PVT. LTD, A-COMPANY INCORPORATED UNDER THE COMPANIES ACT, 1956, HAVING ITS REGD. OFFICE AT 34-B, MIDC, INDUSTRIAL ESTATE, STAPUR, NASHIK- 422 007, MAHARASHTRA, INDIA.
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE NATURE OF THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED:

Technical Field:
The present invention relates to improvements in capacitors. Particularly, the present invention relates to improvements in heat dissipation of capacitors in Power electronics.
Background:
Capacitors known in the prior art, which are used as filters in power electronics are described with reference to the following figures wherein
Fig (la) shows a schematic of a capacitor.
Fig (lb) shows mounting of the capacitor shown in Figure 1 on a mounting plate with the help of a metallic /plastic circular clamp.
Heat dissipation, particularly in capacitors is a known method which is being achieved through (i) casing and by natural convection; (ii) by water or forced cooling; or (iii) through heat sinks.
Due to case size and/or traditional design, dissipation cannot be improved further. Water or forced cooling requires water circulation/ force cooling arrangements and adds extra
costs and space. Alternatively, heat sinks are connected to the capacitor base, wherein

heat is dissipated through the base of the case. Although the above methods are effective methods of heat transfer, they require extra cost and space.
As shown in fig (la) the capacitor consists of a capacitor housing (2), terminal regions (la), (lb), an insulating sleeve (3) to electrically isolate the capacitor housing (2) in the radial direction and an insulating disc(4) is isolating the capacitor housing(2) in the axial direction.
Figure (lb) shows the capacitor at figure 1(a) is mounted on a metal plate (7) with the help of a circular metal clamp (5) with two or more bolts (6a), (6b). In this mounting arrangement there exists an air gap (8) between the metal plate (7) and insulating disc (4). This air gap acts as an insulation to the transfer of heat from the capacitor housing (2) to the metal-plate (7).
These practical constraints lead to invent new effective method of heat transfer.
Object of the invention:
The present invention obviates the aforesaid drawbacks by removing the air gap (8) between the capacitor housing (2) and the metal plate (7).

Summary of the invention:
The present invention relates to a capacitor comprising of a capacitor housing (2), capacitor element with terminal regions (la), (lb), an insulating sleeve (3) to electrically isolate said capacitor housing (2) in the radial direction and 'a laminated disc (4) and an aluminum disc (9) attached to said laminated disc at its bottom; said aluminum disc with a height such that air gap (8) between the metal plate (7) on which said capacitor is mounted and said laminated disc is minimized to isolate said capacitor housing (2) in the axial direction.
Further, the present invention relates to a capacitor comprising of a capacitor housing (2), capacitor element with terminal regions (la), (lb), an insulating sleeve (3) to electrically isolate said capacitor housing (2) in the radial direction and a laminated disc (4) of known heat conducting but electrically isolating materials on both sides of said laminated disc (4) and an aluminum disc (9) with a specific profile such that air gap (8) between the metal plate (7) on which said capacitor is mounted and said lamination is minimized to isolate said capacitor housing (2) in the axial direction.
Detailed description of the invention:
The present invention will now be described with reference to Figures 2 to 7.

Figure 2 shows capacitor with an integrated circular metal plate insulated from the capacitor case and slightiy protruding outside.
Figure 3 shows the mounting of the capacitor on die mounting plate with the help of a circular metal/plastic clamp.
Figure 4 shows a three dimensional view of the capacitor showing the bottom side of the capacitor.
Figure 5 shows capacitor assembled with laminated disc pasted from both sides with insulating compound.
Figure 6 shows the mounting arrangement of capacitor with mounting plate with pasted laminated disc.
Figure 7 shows a three dimensional view of the capacitor showing the bottom side of the capacitor with the laminated disc.
Figure 8 shows the cross sectional top and front view of the aluminum disc.

CATEGORY A
As shown in the Figure 2, the capacitor consists of a capacitor housing (2), terminal regions (la), (lb). Capacitor housing (2), is electrically active, therefore needs electrical isolation. The PVC sleeve (3) isolates the capacitor housing (2) in the radial direction and the specially designed laminated disc (4). An aluminum disc is attached to the laminated disc (4) at its bottom. The aluminum disc is having a height so as to fill up the air gap (8). The air gap (8) shown in fig (2) is now minimized. Figure 3 shows the capacitor mounted on a metal plate (7) with the help of a circular metal clamp (5) with two or more bolts (6a), (6b). Fig (4) shows a three dimensional view of the bottom laminated disc (4) and integrated circular aluminum plate (9) J
CATEGORY B
In another preferred embodiment, as shown in Figure 5, wherein the capacitor is assembled with laminated discs pasted from both sides with an insulating compound. Figures 6 and 7 show the mounting arrangement of capacitor with mounting plate with laminated disc (4) pasted from both sides with thermally conductive but electrically insulating compound so as to fill gap completely between capacitor housing (2) and laminated disc (4) and laminated disc (4) and integrated circular aluminum disc (9) and thereby reducing thermal resistance of the capacitor.

Figure 8 shows the cross sectional top and front view of the aluminum disc. In a preferred
embodiment, the height of the aluminum disc (9) is 0.5 ± 0.05. This height of the
aluminum disc may vary depending on the requirements.
Examples:
The thermal resistances of the capacitors in the prior art with the capacitors manufactured
using the present invention have been compared in the table below:

Capacitors W Th Tb Ts Rctob Rce to s
Prior Art 7.56 73 55 55 2.3 2.3.

Present Invention
Category A
With integrated circular 7.56 68 60 55 1.05 1.71
aluminum disc (9) and
Laminated disc (4)

Present Invention
Category B
With laminated disc (4) 7.56 66 63 55 0.39 1.45
pasted from both sides
with thermally conductive
but electrically insulating
compound.
Abbreviations used in the above table with units:
W = Wattage in watts.
Th = Core Temperature (deg C)

Tb = Bottom Temperature (deg C)
Ts = Surface Temperature (deg C)
R c to b = Thermal Resistance core to bottom, (deg C / w )
R c to s = Thermal Resistance core to surface, (deg C / w)
Above comparison shows improvement in following parameters
• Heat dissipation improved by 10% in Category A and 5% in Category B
• Thermal resistance is reduced by 54% in Category A and 62% in Category B and 83% total in comparison with the prior art stage (Refer parameter R c to b) in axial direction.
• Thermal resistance is reduced by 26% in Category A and 15% in Category B (refer parameter R c to s) and 37% total in comparison with prior art stage in radial direction.
• Core Temperature (Th) reduced by 7% in Category A and 2% in Category B and 9% total in comparison with prior art stage.
The present invention is able to reduce thermal resistance of the Capacitor with minor changes in the manufacturing process with improved heat dissipation.

We Claim:
1. A capacitor comprising of a capacitor housing (2), capacitor element with
terminal regions (la), (lb), an insulating sleeve (3) to electrically isolate said
capacitor housing (2) in the radial direction and a laminated disc (4) and an
aluminum disc (9) attached to the bottom of said laminated disc; said aluminum
disc having a height such that air gap (8) between the metal plate (7) on which
said capacitor is mounted and said laminated disc is minimized to isolate said
capacitor housing (2) in the axial direction.
2. "A capacitor comprising of a capacitor housing (2), capacitor element with
terminal regions (la), (lb), an insulating sleeve (3) to electrically isolate said capacitor housing (2) in the radial direction and a laminated disc (4) of known heat conducting but electrically isolating materials on both sides of said laminated disc(4) and an aluminum disc (9) with a specific profile such that air gap (8) between the metal plate (7) on which said capacitor is mounted and said lamination is minimized to isolate said capacitor housing (2) in the axial direction.
3. A capacitor as claimed in Claim 1 or 2 wherein the height of said aluminum disc (9) is 0.5 ±0.05 mm.
4. A capacitor as herein described with reference to the drawings accompanying the
specification.