Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N30/00—Piezoelectric or electrostrictive devices
  • H10N30/40—Piezoelectric or electrostrictive devices with electrical input and electrical output, e.g. functioning as transformers

Definitions

• the invention relates to a piezoelectric transformer having a body containing a piezoelectric material.
• US 2001/0028206 A1 discloses a piezoelectric transformer in which internal electrodes are provided in the interior of a body.
• a problem to be solved is to provide a further piezoelectric transformer, the risk is reduced from voltage sparkovers between different electrical poles 'with "'.
• a piezoelectric material may be, for example, a lead zirconate titanate ceramic.
• the main body comprises an input part and a mechanically connected thereto output part.
• internal electrodes are provided, which are arranged in the base body.
• the transformer further comprises an auxiliary electrode which is galvanically isolated from the input part and from the output part and from the internal electrodes.
• the inverse piezoelectric effect is understood to mean that the piezoelectric ceramic, which may still need to be polarized for use of the component, undergoes deformation when an electric field is applied in parallel or in anti-parallel or at an angle to the polarization direction.
• Direct piezoelectric effect is understood to mean that a voltage drops in the body when deformations occur.
• mechanical vibrations are generated in the body of the transformer by means of electrical voltages.
• mechanical vibrations of the body are converted into electrical fields, which can be tapped by suitable electrodes.
• At least a part of the auxiliary electrode is arranged parallel to the inner electrodes of the input part and the output part.
• Internal electrodes are arranged in the main body, which are perpendicular to the polarization axis of the transformer.
• the polarization axis of the transformer is preferably directed along the longitudinal axis of the base body. Upon excitation longitudinal vibrations of the body are excited, with mechanical vibrations propagate both in the input part and in the output part in the longitudinal direction of the body.
• the polarization axis of the transformer can also be directed in a thickness direction of the base body.
• thick vibrations of the main body are excited, with mechanical vibrations occurring both in the input part and in the output part in the thickness direction of the main body. wide.
• the arranged parallel to the internal electrodes part of the auxiliary electrode may, for. B. arranged in the interior of the Grundk ⁇ rpers, so be formed as an internal electrode.
• An inner auxiliary electrode is preferably connected to an auxiliary contact, which is arranged on the surface of the base body.
• At least a part of the auxiliary electrode, in one variant even the entire auxiliary electrode can also be arranged on the surface of the base body and be suitable as an auxiliary contact.
• auxiliary electrode is arranged in the main body interior.
• input and output parts are preferably also arranged in each case a plurality of inner electrodes which "do."
• inner electrodes Perpendicular to the polarization axis -des- transformer
• the arranged in the "main body portion of the auxiliary electrode is arranged preferably parallel to the internal electrodes of the input and output parts.
• the two preferred embodiments can be combined with each other.
• the internal electrodes of the input and output parts are connected to input and output contacts of the transformer, which are accessible from the outside.
• An internal auxiliary electrode is provided with at least one externally accessible auxiliary contact of the transformer conductively connected.
• the input and output contacts are in contact with the main body, wherein they are preferably arranged on its surface.
• all external contacts of the transformer, including its input and output contacts and the auxiliary contact, are solderable.
• the transformer may be driven by a driver circuit with an input voltage applied to its input contacts.
• the transformer is characterized by the fact that the output voltage to be picked up at its output contacts differs from the "" input voltage. In particular, the output voltage may be greater than the input voltage.
• the output voltage can also be smaller than the input voltage.
• the transformer is also preferably characterized by the fact that a control voltage to be picked up at the auxiliary contact differs from the input and output voltage of the transformer. This control voltage can be used in a feedback circuit to monitor the driver circuit through which the transformer is driven. Because the auxiliary selector is galvanically decoupled both from the input part and from the output part of the transformer, in the feedback circuit for controlling the transformer cost-intensive decoupling elements such. B. optocouplers are dispensed with. In the following, an exemplary control of the transformer by means of a feedback loop is explained.
• the auxiliary electrode of the transformer forms an auxiliary output.
• the ratio of the voltage picked up at the auxiliary output to the input voltage is referred to below as a transmission coefficient of the transformer.
• the voltage at the auxiliary output is substantially proportional to the output voltage of the transformer.
• the input part of the transformer is connected to a primary path and its output part to a secondary path.
• the input voltage to be applied to the input part of the transformer is supplied by an RF generator, which may comprise a circuit arranged in the primary path with an oscillator, a driver and one or more switches.
• the driver is z. B. suitable for driving the switch.
• the oscillator may be " a voltage controlled oscillator - the oscillator is connected to the switch or switches, for example, via the driver.
• a feedback path is provided with a feedback circuit disposed therein.
• the feedback path can be galvanically decoupled from both the primary and secondary parts.
• the feedback circuit may, for. B. comprise a comparator, an amplifier and / or further elements for processing a tapped at the auxiliary electrode feedback signal to a control signal that arrives at the driver input of the RF generator and the oscillator of the RF generator to controls, which in particular the frequency of the oscillator can be adjusted.
• the specified piezoelectric transformer preferably has a resonance characteristic, d. H. its transmission coefficient is characterized by a resonance curve.
• the operating point of the transformer can z. B. be selected on the left or right flank of its resonance curve, ie below or above its resonance frequency.
• this voltage difference is processed by means of the feedback circuit to a control signal for driving the driver of the RF generator, wherein the frequency of the input voltage is changed in such a way to counteract the voltage deviation
• the frequency of the input signal must be slightly lowered if the operating point is above the resonant frequency of the transformer, thus setting a higher transmission coefficient and a higher output voltage
• the frequency of the input signal must be slightly increased if the operating point is below the resonant frequency of the transformer.
• the tapped off at the auxiliary electrode signal can be used not only for setting the generator frequency, but also otherwise, preferably as a control signal for setting the desired or required input voltage.
• the length and / or width of the auxiliary electrode may be chosen to be equal to the corresponding dimension of an inner electrode of the input or output part facing it.
• the length and / or width of the auxiliary electrode may also be smaller or larger than the corresponding dimension of this inner electrode.
• auxiliary electrode extends for the purpose of contacting an auxiliary contact to the surface of the Grundk ⁇ rpers.
• An inner auxiliary electrode " may in one variant be so large that two extend from their edges or all their edges to the surface of the main body.
• the auxiliary contact can be arranged on the front side.
• the auxiliary contact can be limited to the end face of the base body, wherein it preferably forms the auxiliary electrode.
• the auxiliary contact may also be formed cap-shaped, wherein it preferably completely covers the end face of the body, and wherein it has areas which are arranged on the side surfaces and the main surfaces of the base body.
• the main body can z. B. cuboid or - especially in a working with thickness vibrations transformer - be cylindrical.
• the inner electrodes are arranged perpendicular to the cylinder axis, which is directed parallel to the polarization axis.
• the auxiliary electrode or the auxiliary contact connected to an inner auxiliary electrode can advantageously be arranged on an end face of the cylindrical base body.
• the base body can be flat in an advantageous variant, its thickness being significantly smaller (eg by at least a factor of four) than its length and width.
• the input contacts, the output contacts and the at least one auxiliary contact can all be arranged on side surfaces of the main body.
• the input contacts are preferably arranged on opposite first surfaces of the base body.
• the output contacts are preferably arranged on opposite first surfaces of the base body.
• At least part of the at least one auxiliary contact clock may be "at least" arranged a 'perpendicular' to the first surfaces lying second surface of the base body on.
• the first surfaces are preferably first side surfaces of the main body.
• the second surface may, for. B. be a second side surface or a main surface of the body.
• the arrangement of the auxiliary electrode in a terminal, in particular frontal part of the body is considered to be particularly advantageous.
• the input part between the auxiliary electrode and the output part is arranged.
• the output part between the auxiliary electrode and the input part may also be arranged in an insulating part which mechanically connects the input part and the output part of the transformer.
• auxiliary electrode instead of only one auxiliary electrode, it is also possible to provide a plurality of such electrodes which are galvanically connected to one another and preferably follow one another. But it is also possible to form galvanically separated auxiliary electrodes, which are arranged in different parts of the body. For example, an auxiliary electrode arranged in the region of the input part for monitoring the input part and a further auxiliary electrode arranged in the region of the output part for monitoring the output part can be provided.
• the input part is preferably galvanically isolated from the output part. It is also possible that the two transformer parts z. B. have a common ground contact.
• Figure 1 shows an exemplary transformer with an arranged on its side surface auxiliary contact
• FIG. 2 shows a transformer with auxiliary contacts arranged on its main surfaces; 3 shows a transformer with a frontally arranged auxiliary contact.
• Figure 1 shows a piezoelectric transformer with a flat body, which consists of two parts, a primary part (input part) and a secondary part (output part).
• the two parts are mechanically connected.
• input part, output part and insulating part are integrally connected to each other.
• An electrical signal is converted in the input part into mechanical vibrations of the transformer body by means of the inverse piezoelectric effect.
• the mechanical vibrations propagate through the body of the transformer and reach the secondary side of the transformer, where they are converted back to an electrical signal by means of the direct piezoelectric effect.
• both the input part and the output part consist of several layers of piezoelectric ceramic, which are separated from each other by internal electrodes. The ceramic layers are preferably connected in parallel electrically.
• a layer of insulating material (insulating part) is arranged between the two sides.
• This layer can be made, for example, of the same piezoelectric material as the other parts of the trans-process consist of formators.
• This layer may comprise a plurality of stacked ceramic sublayers.
• FIG. 1 shows a transformer with a transformer body which has an input part 2 and an output part 3.
• the two parts 2, 3 are connected by means of an insulating part 1.
• the input part 2 is provided with electrodes 21 of a first kind and with electrodes 22 of a second kind. These electrodes 21, 22 form interlocking electrode structures, with the aid of which electrical fields can be generated in the interior of the input part 2.
• the electrodes 21 of the first kind are electrically contacted with the external contact 23.
• the electrodes 22 of the second kind are contacted with the external contact 24.
• two groups of electrodes 31 and 32 are provided, which serve to pick up an electrical voltage, wherein the electrical voltage through the connected to the electrodes 31 ⁇ ußkoritakt 33 or by the external contact 34 connected to the electrodes 32 is accomplished.
• an auxiliary electrode 25 is arranged, which is connected to an auxiliary contact 26.
• the auxiliary electrode is formed with the same length and width as the inner electrodes 22 of the output part.
• the auxiliary electrode 25 is galvanically isolated from the external contacts 23, 24, 33 and 34.
• the external contacts 23 and 24 of the input part are arranged on opposite side surfaces of the base body. This also applies to the external contacts 33 and 34 of the output part.
• the external contacts 24, 34 and the auxiliary contact 26 are on the same surface - here the front side surface - arranged the base body. In this case, the main surfaces and the end faces of the base body are preferably metallization-free.
• the electrical contacts 23, 24, 33, 34 and 26 of the transformer are contacted by means of the connecting wires 4, 5.
• the auxiliary electrode 25 is shorter than the inner electrodes of the input or output part.
• the auxiliary electrode is connected to a first auxiliary contact 26 arranged on a first main surface of the main body and to a second auxiliary contact 26 'arranged on its second main surface.
• the end faces of the main body preferably remain free of metallization.
• the contact 26 ' is contacted by means of a connecting wire 5'.
• the auxiliary electrode 25 is designed longer than the inner electrodes of the input or output part. It is connected to a cap-shaped auxiliary contact 26. Such a contact has the advantage that it provides a particularly large soldering surface for soldering the connecting wire 5.
• auxiliary contact such as a piezotransformer with a trained on the front side of the body auxiliary contact such.
• an auxiliary electrode 25 located inside the main body can be dispensed with, since such an auxiliary contact per se is suitable as an auxiliary electrode.
• the specified transformer is not limited to the embodiments presented in the figures, the shape or the number of schematically illustrated elements.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Dc-Dc Converters (AREA)

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Publications (1)

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Citations (6)

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• 2005
  • 2005-10-04 DE DE102005047368A patent/DE102005047368A1/de not_active Ceased
• 2006
  • 2006-09-29 WO PCT/DE2006/001737 patent/WO2007038914A1/de not_active Ceased
  • 2006-09-29 DE DE502006008955T patent/DE502006008955D1/de active Active
  • 2006-09-29 JP JP2008533859A patent/JP5371434B2/ja not_active Expired - Fee Related
  • 2006-09-29 EP EP06818014A patent/EP1932191B1/de not_active Not-in-force
  • 2006-09-29 US US12/089,076 patent/US7723902B2/en not_active Expired - Fee Related

Patent Citations (6)

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