Electrical control unit

Abstract

Electrical control device (10), comprising: - a plurality of components to be cooled (120, 121, 122), - a heat sink (110), wherein the heat sink (110) is electrically insulated from a reference potential and the components (120, 121, 122) to be cooled are thermally conductively coupled to the heat sink (110), - a housing (100), wherein the components (120, 121, 122) to be cooled and the heat sink (110) are arranged within the housing (100), - a number of interference suppression capacitors, each of which is electrically connected to the heat sink (110) at one of its electrical terminals and is electrically connected to an electrical intermediate circuit of the electrical control unit (10) at another of its terminals, and - an EMC filter (140) which is electrically and thermally decoupled from the heat sink (110).

Description

[0001] The invention relates to an electrical control device.

[0002] DE 10 2006 025 531 A1 shows a power converter module in which power semiconductor chips are arranged on associated heat sinks, wherein the heat sinks are electrically insulated from one another.

[0003] DE 10 2012 001 119 A1 shows a control cabinet in which several modules are arranged, whereby the respective modules have a cooling air duct.

[0004] DE 10 2014 012 349 A1 describes a frequency converter with a cooling arrangement. The frequency converter has power semiconductors that generate a time-varying voltage from an intermediate circuit DC voltage.

[0005] The invention is based on the object of providing an electrical control unit that enables the best possible heat dissipation.

[0006] The invention solves this problem by an electrical control device according to claim 1.

[0007] The electrical control unit has a plurality (for example, between 2 and 50) of components to be cooled. The components to be cooled can be heat-generating components that, for example, convert at least partially the electrical energy supplied during their operation into thermal energy.

[0008] The electrical control unit further comprises a heat sink, in particular an electrically conductive one, which is electrically insulated from a reference potential, for example, protective earth (PE). The components to be cooled are coupled to the heat sink in such a way that heat can be conducted from the components to be cooled toward the heat sink in order to cool the components to be cooled. The heat sink can be made of a metal, for example, in particular copper, brass, or aluminum. The heat sink can have a higher thermal conductivity than a housing of the electrical control unit.

[0009] The electrical control unit further comprises a housing, wherein the components to be cooled and the heat sink are arranged within the housing. The housing is preferably designed such that the components to be cooled and / or the heat sink cannot be touched by a user when the housing is closed or operational. In other words, the components to be cooled and / or the heat sink are preferably arranged within the housing in a touch-safe manner. For this purpose, for example, any openings in the housing can be geometrically designed such that a standard finger cannot reach or touch the touch-safe components.

[0010] In one embodiment, the housing is a metal housing. In this case, the electrical control unit has an electrically insulating holding element designed to mechanically fix the heat sink within the metal housing, electrically insulating it from the metal housing.

[0011] In one embodiment, the holding element is designed to mechanically fix the heat sink within the housing by means of a positive connection.

[0012] In one embodiment, the holding element comprises a first plastic molded body and a second plastic molded body, wherein the heat sink is positively connected to the first plastic molded body at its first end face, for example by means of a snap-in connection, and is positively connected to the second plastic molded body at its second end face, for example by means of a snap-in connection. The plastic molded bodies can be produced by an injection molding process.

[0013] In one embodiment, the heat sink forms a closed cooling air duct, for example with a rectangular, in particular square, cross-section, wherein cooling fins are provided within the cooling air duct. The components to be cooled are thermally coupled to at least one of the sides of the heat sink that delimit the cooling air duct. The cooling air duct can have an inlet opening and an outlet opening. The cooling air duct can be closed around its circumference. The cooling air duct can run between cooling air openings on different housing sides. The cooling air duct can connect the cooling air openings on the different housing sides to one another in a fluid-conducting manner. Cooling air can enter the housing interior through a cooling air opening on one housing side and be guided through the cooling air duct to the other housing side, wherein the cooling air exits the housing again from the cooling air openings on the other housing side.

[0014] In one embodiment, the electrical control unit has a fan that is designed to cause an air flow in the cooling air duct.

[0015] In one embodiment, the plurality of components to be cooled comprises power semiconductors, and / or coils, and / or capacitors.

[0016] The electrical control unit has a number (e.g., between 1 and 20) of interference suppression capacitors, for example, in the form of so-called Cy capacitors, each of which is electrically connected to the heat sink at one of its electrical terminals and to an electrical intermediate circuit of the electrical control unit at another of its terminals. Regarding the intermediate circuit, reference is made to the relevant technical literature.

[0017] The electrical control unit includes an electromagnetic compatibility (EMC) filter that is electrically and thermally decoupled from the heat sink. The EMC filter may include an EMC choke.

[0018] In one embodiment, the electrical control unit has a rated power that is greater than 25 kW, in particular greater than 48 kW.

[0019] In one embodiment, the electrical control device is a frequency converter, a servo converter or a regenerative unit, which is designed, for example, to feed excess electrical energy present in an electrical intermediate circuit back into a supply network.

[0020] In one embodiment, the power semiconductors are designed to generate a time-varying voltage from an intermediate circuit DC voltage, for example for feeding power back into the grid or for supplying an electrical machine.

[0021] When switching power semiconductors, high-frequency interference voltage is coupled into the heat sink through the typically very thin-walled ceramic insulation beneath the power semiconductors. Similar interference is also transmitted to the heat sink in power chokes, which are cooled via a heat sink.

[0022] These disturbances cannot be directly influenced due to the high switching speeds and the necessary heat dissipation towards the heat sink.

[0023] Therefore, as a countermeasure, Cy capacitors are usually inserted between the intermediate circuit and the heat sink, which ensure that at least some of the resulting interference currents are fed directly back into the intermediate circuit.

[0024] If the heat sink is accessible from the outside, it must be connected to PE (Protective Earth), for example, in accordance with Protection Class I according to EN 61140. However, some of the interference currents flow into the supply network via this low-resistance connection to PE and thus become visible in both conducted and radiated EMC measurements.

[0025] To comply with EMC standards, the Cy capacitors must be increased in size, which, however, increases the earth wire current. This increase in the earth wire current, in turn, leads to problems with residual current devices (RCDs).

[0026] If a ground fault occurs at the inverter output in IT networks, these Cy capacitors are subjected to high thermal stress and can fail. To prevent failures, an IT isolation point must be installed to separate these Cy capacitors from the PE potential. Many users are overwhelmed by this problem, resulting in additional support costs.

[0027] According to the invention, the heat sink is integrated into the housing of the control unit in such a way that it can no longer be touched from the outside, so that the heat sink can also be insulated from PE in a device, for example, of protection class I according to EN 61140.

[0028] This eliminates the need for a low-impedance connection to PE, and the interference currents coupled into the heat sink cannot leave the control unit. This allows for smaller dimensions of the Cy capacitors, and the return of the interference currents to the intermediate circuit functions significantly better.

[0029] In IT networks, thermal overload of the Cy capacitors can no longer occur because they are no longer connected to PE. Disconnecting a PE connection is therefore no longer necessary.

[0030] According to the invention, electrical insulation of the heat sink can be achieved in an air-cooled device at very low additional costs, which are significantly lower than the additional EMC suppression measures required. Overall, this allows control units with power electronics to be implemented, which can be manufactured significantly more cost-effectively for comparable EMC requirements than if the heat sink had to be connected to PE.

[0031] According to the invention, the heat sink is packed in a housing, for example a sheet metal housing, which absorbs the mechanical forces and the weight of the heat sink and all components attached or screwed to it (and cooled at the same time) (in particular chokes and power semiconductors) and transmits them to the attachment points of the housing, for example to a rear wall of the housing.

[0032] Two plastic parts can take over the function of electrical insulation by mechanically fixing the heat sink through a positive connection without a conductive connection (e.g. via a metal screw) bridging the insulation.

[0033] The thermal connection of all coils or chokes to the heat sink, which, as described above, couple interference voltage into the heat sink in a similar way, supports the EMC behavior in that these interferences can also be retained in the device with little effort and fed back into the intermediate circuit.

[0034] Optimally arranged and correctly dimensioned Cy capacitors reduce the interference voltages in the heat sink by guiding the coupled energy back into the intermediate circuit via a short and thus low-inductance connection.

[0035] To avoid capacitive coupling to a downstream EMC filter at a control unit output, for example, in the form of a regenerative power unit, the EMC filter is installed separately from the heat sink and cooled exclusively by the circulating air within the device. This is easily achieved due to the significantly lower power dissipation of the EMC filter. The spatial separation of the EMC filter prevents capacitive coupling of interference to the supply lines (DC and AC).

[0036] The invention is described in detail below with reference to the drawings, in which: Fig. 1 a perspective view of a partially opened control device according to the invention in a first view and Fig. 2 a perspective view of the partially opened control device according to the invention in a further view.

[0037] Fig. 1 shows a perspective view of a partially opened electrical control device 10 according to the invention in a first view. Fig. 2 shows a perspective view of the partially opened control device 10 according to the invention in a further view.

[0038] In this case, the control unit 10 is a (mains) regenerative power unit designed to feed any excess electrical energy present in an intermediate circuit back into a supply network. In this regard, reference is also made to the relevant specialist literature.

[0039] The control unit has a rated power greater than 48 kW.

[0040] Referring to Fig. 1 and Fig. 2, the control unit 10 further comprises a number of heat-generating components in the form of coils 120, 121 and power semiconductors 122. The power semiconductors are designed to generate a time-varying voltage for feeding into the grid from an intermediate circuit DC voltage.

[0041] The control unit 10 further comprises a heat sink 110, wherein the heat sink 110 is electrically insulated from protective earth PE and the heat-generating components 120, 121, 122 are thermally conductively coupled to the heat sink 110.

[0042] The heat-generating components 120, 121, 122 and the heat sink 110 are arranged in a touch-safe manner within a metal housing 100 of the control unit 10. It is understood that in the Fig. 1 and Fig.2, the housing 100 is shown partially open for the purpose of describing the invention. In an operating state of the control unit 10, the housing 100 is closed, for example by adding additional housing parts not shown, in such a way that contact with potentially live components, such as the heat sink 110, is not possible.

[0043] The housing 100 has cooling air openings 105 on a first housing side 101 and on a second housing side 102, which is opposite the first housing side. The heat sink forms a closed cooling air channel 111 that runs between the cooling air openings 105 on the first housing side 101 and the second housing side 102.

[0044] The electrical control unit 10 further comprises an electrically insulating holding element with a first plastic molded body 115 and a second plastic molded body 115', wherein the heat sink 110 is positively connected to the first plastic molded body 115 on a first end face and is positively connected to the second plastic molded body 115' on a second end face, wherein the plastic molded bodies 115 and 115' are in turn each mechanically fixed to associated housing regions.

[0045] The heat sink 110 forms a closed cooling air channel 111, with a number of cooling fins 112 provided within the cooling air channel 111. The components 120, 121, 122 are thermally coupled to various outer sides 130, 131, 132, 133 of the heat sink 110, relative to the cooling air channel 111. On a first side 133 of the heat sink 110, the coils 120 are thermally coupled to the heat sink 110. On a second side 132 of the heat sink 110, the coils 121 are thermally coupled to the heat sink 110. The first side 133 of the heat sink 110 is opposite the second side 132 of the heat sink 110. On the third side 131 of the heat sink 110, the power semiconductors 122 are thermally coupled to the heat sink 110, wherein the third side 131 is perpendicular to the first side 133 and the second side 132.

[0046] The electrical control unit 10 further comprises a first circuit board 145 which is arranged parallel and offset to the third side 131 of the heat sink 110 and which is electrically connected to the power semiconductors 122.

[0047] The electrical control unit 10 further comprises a second circuit board 146 which is arranged parallel and offset to the second side 132 of the heat sink 110 and which is electrically connected to the coils 121.

[0048] The electrical control unit 10 further comprises a third circuit board 147, which is arranged parallel and offset from the second side 132 of the heat sink 110 and which carries a number of electrical contacts 150, wherein the electrical contacts 150 are configured to connect an electrical supply line to the electrical control unit 10. The second circuit board 146 is mechanically attached to the third circuit board 147.

[0049] The electrical control unit 10 has a fan 135 which is designed to cause an air flow in the cooling air duct 111.

[0050] The electrical control unit 10 further comprises a number (for example two) of Cy interference suppression capacitors 123, each of which is electrically connected to the heat sink 110 at one of its electrical terminals and is electrically connected to an electrical intermediate circuit of the electrical control unit 10 at another of its terminals.

[0051] The electrical control unit 10 further comprises an EMC filter 140, which is electrically and thermally decoupled from the heat sink 110.

Claims

[1] Electrical control device (10), comprising: - a plurality of components to be cooled (120, 121, 122), - a heat sink (110), wherein the heat sink (110) is electrically insulated from a reference potential and the components (120, 121, 122) to be cooled are thermally conductively coupled to the heat sink (110), - a housing (100), wherein the components (120, 121, 122) to be cooled and the heat sink (110) are arranged within the housing (100), - a number of interference suppression capacitors, each of which is electrically connected to the heat sink (110) at one of its electrical terminals and is electrically connected to an electrical intermediate circuit of the electrical control unit (10) at another of its terminals, and - an EMC filter (140) which is electrically and thermally decoupled from the heat sink (110). [2] Electrical control device (10) according to claim 1, characterized by , that - the housing (100) is a metal housing, and - the electrical control unit (10) has an electrically insulating holding element (115, 115') which is designed to mechanically fix the heat sink (110) within the housing (100) in an electrically insulated manner from the housing (100). [3] Electrical control device (10) according to claim 2, characterized by , that - the holding element (115, 115') is designed to mechanically fix the heat sink (110) within the housing (100) by means of a positive connection. [4] Electrical control device (10) according to claim 2 or 3, characterized by , that - the holding element (115, 115') has a first plastic molded body (115) and a second plastic molded body (115'), wherein the cooling body (110) is positively connected to the first plastic molded body (115) at a first end face and is positively connected to the second plastic molded body (115') at a second end face. [5] Electrical control device (10) according to one of the preceding claims, characterized by , that - the heat sink (110) forms a closed cooling air channel (111), wherein cooling fins (112) are provided within the cooling air channel (111), wherein the components (120, 121, 122) to be cooled are thermally conductively coupled to a side of the heat sink (110) which delimits the cooling air channel (111). [6] Electrical control device (10) according to claim 5, characterized by , that - the electrical control unit (10) has a fan (135) which is designed to cause an air flow in the cooling air duct (111). [7] Electrical control device (10) according to one of the preceding claims, characterized by , that - the plurality of components (120, 121, 122) to be cooled comprise power semiconductors and / or coils and / or capacitors. [8] Electrical control device (10) according to one of the preceding claims, characterized by , that - the electrical control unit (10) has a rated power greater than 25 kW, in particular greater than 48 kW. [9] Electrical control device (10) according to one of the preceding claims, characterized by , that - the electrical control device (10) is a frequency converter, a servo converter or a regenerative unit. [10] Electrical control device (10) according to one of the preceding claims, characterized by , that - the plurality of components (120, 121, 122) to be cooled comprise power semiconductors which are designed to generate a time-varying voltage from an intermediate circuit DC voltage.

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