DE102019122756B3 - Capacitor system to compensate for mechanical disturbances - Google Patents

Abstract

The disclosure relates to a capacitor system comprising: a capacitor element with a predetermined capacitance; a piezo element which can be deflected in a predetermined manner by applying a voltage; wherein the piezo element is set up to at least partially compensate for a movement that is caused by the capacitor element.

Description

Technical field

In the following, embodiments are disclosed which relate to capacitor systems which are set up by a piezo element to compensate for vibrations of a capacitor element.

background

In-house experiments have shown that the use of a capacitor in an intermediate circuit of an electrical circuit with a DC voltage source for operating an AC consumer can lead to acoustic impairments. The reason for this could be identified as voltage ripples that were generated by the power electronics of the AC consumer and with which the capacitor was excited. As a result of the electrical excitation, the capacitor or its environment, for example a printed circuit board (PCB), begins to vibrate mechanically. This leads in particular to interfering noises and / or faster aging of the capacitor and its coupling to the PCB. The voltage ripples can be generated, for example, by switching operations of IGBTs or by carrier frequencies of PWM amplifiers. Compared to a similar problem, the US 2014/0076621 A1 propose to mechanically isolate the capacitor from the PCB by placing it on stilts. The stilts accommodate the rectangular capacitor at its corners, where the oscillation amplitude is lowest. However, stilts can only be used for simple capacitor geometries and / or if space is available. In addition, other influences have also been observed which stimulate mechanical vibrations in a capacitor, which in particular lead to disturbing noises.

The DE 10 2007 012 925 A1 relates to a device for damping structural vibrations for a carrier device by means of a piezoelectric actuator device which has piezoelectrically excitable strips for damping longitudinal and / or transverse vibrations

description

In contrast, the object arises to provide an improved capacitor.

This problem is solved by the invention, which is defined by the subjects of the independent claims. The dependent claims relate to corresponding developments. Various aspects and embodiments of these aspects are disclosed below that provide additional features and advantages.

Some embodiments solve the problem of damping mechanical vibrations that are triggered by electrical interference signals. This can reduce background noises generated by mechanical vibrations. In particular, a piezo element which is deflected in phase opposition to an oscillating capacitor element can help to reduce oscillations in an overall system which comprises a capacitor element and a piezo element. The piezo element can bring about a reduction in the change in size of the overall system in particular by means of an essentially simultaneous, complementary change in size to the change in size of the capacitor element.

• - ein Kondensatorelement mit einer vorgegebenen Kapazität;
• - ein Piezoelement, welches durch Anlegen einer Spannung vorgegeben auslenkbar ist; wobei das Piezoelement dazu eingerichtet ist, eine Bewegung, die durch das Kondensatorelement bewirkt wird, zumindest teilweise zu kompensieren. Verschiedene Kondensatortypen können für ein solches Kondensatorsystem in Betracht kommen. Als Kondensatoren kommen Kondensatoren mit fester Kapazität als auch Kondensatoren mit variabler Kapazität oder eine Kombination von beiden Kondensatortypen in Betracht. Ein Kondensator kann ein Folienkondensator sein, beispielsweise ein Papierfolienkondensator und/oder ein Kunststofffolienkondensator. Ein Kondensator kann alternativ oder als Kombination ein Keramikkondensator sein, beispielsweise ein MDK-Keramikkondensator oder ein HDK-Kondensator. Ebenso kann ein Kondensator ein Glimmerkondensator sein. Beispielsweise kann ein Kondensator ein Aluminium-Elektrolyt-Kondensator umfassen und/oder ein Tantal-Elektrolytkondensator und/oder ein Doppelschicht-Kondensator. Als Kondensator mit variabler Kapazität, der ebenso als Kondensatortyp Verwendung finden kann, kann insbesondere ein Drehkondensator in Betracht kommen oder ein Trimmkondensator.

A first aspect relates to a capacitor system comprising:

• a capacitor element with a predetermined capacitance;
• - A piezo element which can be deflected in a predetermined manner by applying a voltage; wherein the piezo element is set up to at least partially compensate for a movement that is caused by the capacitor element. Different types of capacitors can be considered for such a capacitor system. Suitable capacitors are capacitors with a fixed capacitance and capacitors with a variable capacitance or a combination of both types of capacitors. A capacitor can be a film capacitor, for example a paper film capacitor and / or a plastic film capacitor. A capacitor can alternatively or as a combination be a ceramic capacitor, for example an MDK ceramic capacitor or an HDK capacitor. A capacitor can also be a mica capacitor. For example, a capacitor can comprise an aluminum electrolytic capacitor and / or a tantalum electrolytic capacitor and / or a double-layer capacitor. A variable capacitor or a trimming capacitor can in particular be considered as the capacitor with variable capacitance, which can also be used as a capacitor type.

A capacitor element can in particular comprise one or more of the abovementioned capacitor types, in particular different capacitor types, as capacitors. In particular, a capacitor element can comprise a plurality of capacitors which are arranged at different points in the capacitor system. In particular, a capacitor system can comprise a layered capacitor or a plurality of layered capacitors. A given capacity can in particular be an absolutely given capacity. Additionally or alternatively, a predefined capacitance can be a relative capacitance which, for example, was predefined relative to a capacitance of another capacitor, in particular another capacitor in the capacitor element.

A piezo element is a component which uses the piezo effect or which achieves a change in size through the piezo effect. A piezo element can in particular comprise a ceramic. In particular, a piezo element can comprise a ceramic which can be used in a ceramic capacitor. In particular, the piezo element can also be used as part of a capacitor, so that in addition to the change in size and thus the compensation effect (which is described below), the piezo element can also function as a capacitor and thus provide capacitance for the capacitor system. A piezo element can in particular also be understood to mean an element which has an electrostrictive effect and in particular is not piezoelectric. Thus, in the most general case, a piezo element can be an element which changes in size under the influence of an electric field.

A compensation effect can be aimed directly at movements of the capacitor element. In particular, compensation by the piezo element can consist in the fact that the piezo element contracts when the capacitor element expands. An expansion of the capacitor element can, as described above, take place in particular through interference voltages or interference currents and in particular lead to undesired noise generation. In particular, the piezo element can be specified in such a way that it compensates for certain deflections of the capacitor element in that it contracts by a similar length when the capacitor element expands by a certain length and, conversely, that it expands by a similar length when the Condenser system contracts by a certain length. The change in length of the overall system consisting of capacitor element and piezo element is then advantageously less than the change in length which is brought about by the capacitor element alone. With this compensation, i.e. complementary length adjustment of the piezo element, the vibrations of the excited capacitor element are only partially passed on to the outside, in particular to a negligibly small extent, so that the vibration caused by the capacitor element is effectively damped to the outside. As a result, interfering noises caused by the vibrations of the capacitor element can be reduced or completely reduced. Additionally or alternatively, a compensation can also consist in reducing movements which are caused by movements of the capacitor element. In particular, movements of elements in the vicinity of the capacitor element and / or the capacitor system can be compensated accordingly.

One embodiment of the first aspect relates to a capacitor system, the piezo element being shaped as a layer.

The layer can in particular have essentially the same length and / or the same depth as the capacitor element. The term “essentially” means that the corresponding lengths and / or the corresponding depths differ by less than 20%.

One embodiment of the first aspect relates to a capacitor system, wherein the piezo element is arranged such that it acts between the capacitor element and a PCB when the capacitor system is arranged on a PCB, in particular on and / or in a base.

In particular, a potting compound can also be arranged between the piezo element and the PBC. In particular, a potting compound can represent a base in which the piezo element is mounted on the PCB. The base can in particular be made of metal and / or a plastic. In particular, a base can consist of a substrate on which the piezo element is arranged and, in particular, was produced.

One embodiment of the first aspect relates to a capacitor system, the piezo element comprising several piezo sub-elements.

In particular, the plurality of sub-elements of the piezo element can be arranged on a plane below or above an expansion plane of the capacitor element.

One embodiment of the first aspect relates to a capacitor system, piezo sub-elements being arranged on several sides of the capacitor element.

In particular, sub-elements of the piezo element can be arranged above and / or below the longest and / or deepest sides of the capacitor element. The longest and / or the deepest sides or the sides of the Capacitor elements with the largest area can have the largest deflections when the sides bend, in particular when a corresponding voltage signal is applied to the capacitor element. In addition to these sides, by arranging a corresponding sub-element of the piezo element, vibration damping of the entire capacitor system can be effectively achieved in that the deflections of the capacitor element are compensated for by deflections of the sub-elements of the piezo element in antiphase. Additionally or alternatively, one or more piezo sub-elements can also be arranged on the other sides of the capacitor element.

One embodiment of the first aspect relates to a capacitor system, piezo sub-elements having different piezoelectric charge constants.

The piezoelectric charge constant describes the functional relationship between the electrical field strength acting on the piezo element and the change in length that it generates. The piezoelectric charge constant can also relate to a change in length that occurs at right angles to the electric field or to a change in length that acts parallel to the electric field. By using different piezo sub-elements with different charge constants, different properties, e.g. different frequencies of an interfering signal can be better compensated.

One embodiment of the first aspect relates to a capacitor system, a plurality of piezo sub-elements being stacked on at least one side.

One or more stacked piezo sub-elements can in particular be used to adapt amplitudes of the piezo element, in particular one or more piezo sub-elements, to the surface speed and / or vibrations of the capacitor element. The maximum possible change in length can be increased by a stacked piezo element or a stacked piezo sub-element. A better compensation effect can thus be achieved through appropriately configured stacks. In particular, different piezo stacks can be arranged on different sides of the capacitor element in order to optimally compensate for the vibrations of the capacitor element occurring there.

One embodiment of the first aspect relates to a capacitor system, the capacitor element being enclosed by the piezo element.

In particular, the capacitor element can be enclosed by several piezo sub-elements. Additionally or alternatively, the capacitor element can have a casting compound that represents a piezo element. In particular, the capacitor element can be enclosed in the shape of a ring by the piezo element, wherein in particular one or more rings, which represent piezo sub-elements, enclose the capacitor system. In particular, the capacitor element can also have one or more bases which support the capacitor element. Such a base can also enclose the capacitor element at least on one side.

One embodiment of the first aspect relates to a capacitor system, the piezo element, in particular one or more piezo sub-elements, being arranged on a rigid plate, in particular a metal plate.

The plate can in particular serve to ensure that the change in length of the piezo element results from the rigid plate. This means that the piezo element is supported on the rigid plate when it expands. This can reduce or prevent the vibration from being passed on to the housing of the capacitor system. The plate can in particular be a substrate on which the piezo element is arranged or was produced. The plate can in particular consist of copper. In particular, a voltage potential can be applied to the piezo element via the plate in order to mechanically deflect the piezo element accordingly.

One embodiment of the first aspect relates to a capacitor system which has a rigid plate between a capacitor element and a piezo element, in particular one or more piezo sub-elements, in particular a metal plate.

Additionally or alternatively, a rigid plate can be arranged on the opposite side of the piezo element, so that the piezo element is provided with a rigid plate, in particular from two sides. The rigid plate between the piezo element and the capacitor element can be designed to transmit the change in length through the piezo element uniformly over the entire surface of the rigid plate to the capacitor element. In this way, particularly in the case of a piezo element which does not have the dimensions of the capacitor element, the change in length is advantageously transmitted uniformly to the capacitor element via the rigid plate.

One embodiment of the first aspect relates to a capacitor system, the rigid Plate is arranged movable in the direction of the deflection of the piezo element.

In particular, the rigid plate can be floating between the capacitor element and the piezo element, d. H. movable so that a change in length of the piezo element causes a displacement of the rigid plate in the direction of the capacitor element and / or that a change in length of the capacitor element causes a displacement of the rigid plate in the direction of the piezo element. In this way, changes in length of the capacitor element and / or the piezo element can advantageously be transmitted uniformly and with little or no friction losses. In particular, the floating rigid plate can provide a contact for applying a voltage potential to the capacitor element or the piezo element. Then the floating rigid plate can be connected to the corresponding output contact of the capacitor system with a flexible connection. Such a flexible connection can for example comprise a copper braid.

One embodiment of the first aspect relates to a capacitor system, the capacitor element and the piezo element, in particular one or more piezo sub-elements, being connected in parallel.

In particular, it is important to ensure that the piezo element is connected in such a way that it contracts when the capacitor element expands and expands when the capacitor element contracts. The piezo element can thus interact with the capacitor element, in particular in antiphase and / or in particular out of phase. If the capacitor element and the piezo element are connected in parallel, care must be taken to install the piezo element accordingly.

One embodiment of the first aspect relates to a capacitor system, the piezo element, in particular one or more piezo sub-elements, being set up to move in phase opposition to the capacitor element.

A corresponding control of the piezo element, in particular an anti-phase control, can in particular be implemented by a control and / or by a regulation. In particular, the control or regulation can be configured in such a way that certain frequencies, in particular certain harmonics, of the excitation frequencies are compensated by the piezo element. Additionally or alternatively, a control system can be set up in such a way that it reduces vibrations on a PCB on which the capacitor system is arranged. In particular, a sensor can measure information about an actual deflection of the capacitor element and / or about an actual deflection of an element influenced by the oscillating capacitor element in its surroundings, for example the PCB on which the capacitor element is arranged, for regulation purposes. Such a sensor can in particular be arranged within the capacitor system. In addition or as an alternative, such a sensor can be arranged outside the capacitor system and its information can be communicated to the control system or the control system, which can be arranged in the capacitor system. In particular, a sensor can be arranged on a PCB in order to measure the vibrations which are transmitted to the PCB by the capacitor system.

One embodiment of the first aspect relates to a capacitor system, the capacitor element and the piezo element being galvanically separated.

A galvanic coupling (also called impedance coupling) is a coupling in which the currents of two circuits flow over a common impedance. The currents each cause a voltage drop at the coupling impedance, which can have a disruptive effect and is therefore undesirable. This common impedance is often a common reference conductor, a common forward conductor or, on circuit boards, the common ground of different circuits. It can be an ohmic as well as an inductive or capacitive resistor. In the embodiment given above, the piezo element can be supplied by another voltage source. In particular, the other voltage source can be coupled by a control and / or regulation system, so that the piezo element is supplied with voltage in a targeted manner in order to achieve a predetermined compensation effect. This can be, for example, a compensation for the movement of the capacitor element or a compensation for a movement which is caused by the capacitor element, for example a compensation for a movement of a PCB.

One embodiment of the first aspect relates to a capacitor system, the piezo element being set up to be at least partially supplied by the capacitor element.

In particular, the piezo element can be coupled to the capacitor element via an electric field. In particular, energy can thus be transferred to the piezo element through the electric field in the capacitor, so that the piezo element moves in particular in such a way that it develops a compensation effect on the vibrations of the capacitor element. In particular, the piezo element can be coupled in phase opposition to the capacitor element, but galvanically separated, so that the piezo element is at least partially supplied with energy via the electrical field caused by the capacitor element.

In particular, the capacitor system can be used as an intermediate circuit capacitor. In particular as an intermediate circuit capacitor for solar converters or within the power electronics of an electric vehicle.

Figure list

• 1 ein Kondensatorsystem mit einem Piezoelement;
• 2 ein Kondensatorsystem mit einem Piezoelement, welches mehrere Piezoteilelemente aufweist.

Further advantages and features emerge from the following embodiments, which refer to the figures. The figures do not always show the embodiments true to scale. The dimensions of the various features can be increased or decreased accordingly, in particular for the clarity of the description. This shows, partly schematically:

• 1 a capacitor system with a piezo element;
• 2 a capacitor system with a piezo element, which has several piezo sub-elements.

In the following descriptions, identical reference symbols relate to identical or at least functionally similar and / or equivalent features.

In the following description, reference is made to the accompanying drawings, which form a part of the disclosure and in which there are shown, for purposes of illustration, specific aspects in which the present disclosure may be understood. It is understood that other aspects and / or features can be used and functional, structural or logical changes are possible without departing from the scope of the present disclosure. The following detailed description is therefore not to be interpreted in a limiting sense, as the scope of the present invention is defined by the appended claims.

In general, a disclosure about a described method also applies to a corresponding device in order to carry out the method, or a corresponding system which comprises one or more devices, and vice versa. If, for example, a special method step is described, a corresponding device can comprise a feature in order to carry out the method step described, even if this feature is not explicitly described or shown in the figure. On the other hand, if, for example, a special device is described on the basis of functional units, a corresponding method can comprise a step that executes the functionality described, even if such steps are not explicitly described or illustrated in the figures. Likewise, a system can be provided with corresponding device features or with features in order to carry out a specific method step. It goes without saying that features of the various exemplary aspects and embodiments described above or below can be combined with one another, unless expressly stated otherwise.

Description of the figures

1 shows a capacitor system 100 which is on a PCB 150 is arranged. The capacitor system has contact connections 102a and 102b which each provide a positive and a negative contact. The capacitor system has a dielectric 103 on, which is in the middle of a potting compound 104 is arranged. By applying a corresponding electrical disturbance, as indicated in the introductory part of the patent application, the dielectric performs vibrations, which are indicated by the arrows 105 are made clear. These vibrations can, for example, represent oscillations through which the dielectric simultaneously expands upwards and downwards and then simultaneously contracts inwards. The potting compound is also replaced by the vibrations 104 set in vibrations and these mechanical vibrations can lead to acoustic noise. In order to reduce these acoustic noises, the condenser system 101 a piezo element 106 on which is below the dielectric 103 is arranged. Between the piezo element 106 and the PCB 150 is a copper layer 107 arranged. This copper layer is with a contact element 102a of the condenser system 100 connected. About the piezo element 106 is another copper layer 108 arranged. This copper layer is with the other contact element 102b of the condenser system 100 electrically connected. This is the piezo element 106 to the dielectric 103 connected in parallel because the dielectric 103 is just like the piezo element 106 via the electrical connector 103a and 103b with the contact elements 102a , 102b connected to the condenser system. Accordingly, both elements become that dielectric 103 and the piezo element 106 , operated with the same voltage. In addition, the piezo element is so in the capacitor system 100 integrates that it contracts at a voltage at which the dielectric breaks down 103 expands and that it expands at a voltage that causes the dielectric to expand 103 contracts. Through this anti-phase operation of the piezo element 106 to the dielectric 103 the deflection, which the capacitor system is reduced 100 on the PCB 150 causes. This is by the arrow 112 shown. Due to the reduced excitation of the PCB150 by the capacitor system 100 noise as well as effects by which the PCB 150 experiences faster wear and tear.

2 discloses a capacitor system 200 with different features to illustrate different developments of the capacitor system 1 . The fact that these different developments are shown in a single embodiment does not mean that individual developments and / or individual features cannot be used alone in a capacitor system. The condenser system 200 is on a PCB 150 arranged and has contact elements 102a , 102b on through which a dielectric 103 a voltage can be provided. Furthermore, the capacitor system 200 a first piezo sub-element 106 which is adjacent to a copper plate above and below. The lower copper plate 107 is firmly attached to the PCB 150 connected. The top copper plate 108 is floating and between the piezo element 106 and the potting compound 104 of the dielectric 103 arranged. Due to the floating mounting, the upper copper plate 108 Movements through the piezo part element 106 and movements through the dielectric 103 Record well and uniformly either to the piezo sub-element 106 or to the potting compound 104 in which the dielectric 103 is stored, pass it on. This allows the through the lower piezo sub-element 106 caused compensation effect with lower losses, which might arise from a fixed plate, unfold. The copper plates 107 and 108 , which is the lower piezo sub-element 106 include, are also each with a flexible strand 107a , 108a to the contact elements 102a , 102b connected. Furthermore, the capacitor system 200 a layered dielectric 103 on. The different layers are through the metallizations 103a or. 103b to recognize the respective electrical connections to the corresponding contact elements 102a , 102b of the condenser system 200 produce. In the individual layers of the dielectric 103 The electrical interference signals described above have a smaller effect, but their interference effect increases with the number of layers. This is indicated by the enlarged arrows 105 shown at the top and bottom of the dielectric. The lower piezo sub-element compensates in particular for the deflections of the dielectric 103 or the potting compound 104 in which the dielectric 103 is embedded, down. This is by the arrow 112 shown. The condenser system 200 also points above the dielectric 103 a piezo sub-element 109 on. The second piezo sub-element 109 is also in two layers of copper 110 and 111 embedded. The lower copper layer 111 is floating and has no fixed connection to the contact elements 102a , 102b or to the housing 113 on. The top copper layer is solid to the case 113 connected. The case 113 can, for example, represent a heat sink to remove heat that is in the condenser system 200 arises to be released to the outside The piezo part element 109 is about the two copper plates 110 , 111 supplied with a voltage whose source is not shown. By galvanic decoupling of the piezo sub-element 109 from the dielectric 103 can the piezo element 109 can be controlled more flexibly. In particular, a position regulator can be used for this, which in particular by means of a sensor (not shown) an expansion or contraction of the piezo component element 109 in the condenser system 200 measures. Additionally or alternatively, an external sensor can be used to measure the expansion or contraction of the piezo sub-element 103 observed only indirectly, for example by placing this sensor on the PCB 150 is arranged. This architecture allows the piezo sub-element 109 not only in phase opposition to the dielectric 103 be controlled. Instead, other phases and other frequencies of the piezo sub-element or other mechanical disturbances can also be compensated for by a suitable control.

List of reference symbols

100

Condenser system

102a

Contact element, negative or positive

102b

to 102a complementary contact element

103

dielectric

103a

Metallization of the dielectric to the contact element 102a

103b

Metallization of the dielectric to the contact element 102b

104

Casting compound

105

Direction of movement and strength

106

lower piezo element, first piezo sub-element

107

lower copper layer

108

upper copper layer

109

second piezo sub-element

110

upper copper layer of the second piezo sub-element

111

lower copper layer of the second piezo sub-element

112

Direction of movement and strength

113

casing

150

Printed Circuit Board (PCB)

200

Condenser system

Claims (14)

A capacitor system (100, 200), in particular a film capacitor system and / or layered capacitor system, comprising: - A capacitor element (103) with a predetermined capacitance; - A piezo element (106) which can be deflected in a predetermined manner by applying a voltage; wherein the piezo element is set up to at least partially compensate for a movement which is caused by the capacitor element; and wherein the piezo element (106) is arranged such that it acts between the capacitor element (103) and a PCB (150) when the capacitor system is arranged on a PCB, in particular on and / or in a base. A capacitor system according to the preceding claim, wherein the piezo element (106) is shaped as a layer. Capacitor system according to one of the preceding claims, wherein the piezo element comprises a plurality of piezo sub-elements (106, 109). Capacitor system according to the preceding claim, wherein piezo sub-elements (106, 109) are arranged on several sides of the capacitor element (103). Capacitor system according to one of the two preceding claims, wherein piezo sub-elements (106, 109) have different piezoelectric charge constants. Capacitor system according to one of the three preceding claims, wherein piezo sub-elements are stacked on at least one side. Capacitor system according to one of the preceding claims, wherein the capacitor element (103) is enclosed by the piezo element. Capacitor system according to one of the preceding claims, wherein the piezo element (106, 109), in particular one or more piezo sub-elements, is arranged on a rigid plate, in particular a metal plate (107). Capacitor system according to one of the preceding claims, wherein a rigid plate (108) between the capacitor element and the piezo element, in particular one or more piezo sub-elements, in particular a metal plate. Capacitor system according to the preceding claim, wherein the rigid plate (108) is arranged movably in the direction of the deflection of the piezo element. Capacitor system according to one of the preceding claims, wherein the capacitor element (103) and the piezo element (106, 109), in particular one or more piezo sub-elements, are connected in parallel. Capacitor system according to one of the preceding claims, wherein the piezo element (106, 109), in particular one or more piezo sub-elements, is set up to move in phase opposition to the capacitor element (103). The capacitor system according to the preceding claim, wherein the capacitor element (103) and the piezo element (106, 109) are galvanically separated. The capacitor system according to one of the preceding claims, wherein the piezo element (106, 109) is set up to be at least partially supplied with energy by the capacitor element (103).

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