Device and method for converting at least one input signal into a low-frequency periodically varying oscillation signal

Abstract

The invention relates to a device and a method for converting at least one input signal into a low-frequency periodically varying oscillation signal. The device comprises a first signal path between a first connection (100a) and a second connection (100b), a second signal path between a third connection (100c) and a fourth connection (100d), and at least one multi-stage electrical filter (200, 400, 500). The multi-stage electrical filter (200, 400, 500) comprises at least two filter stages (100, 300) successively connected for converting an input signal into an electrical periodically varying oscillation signal. The first filter stage (100-1, 300-1) comprises a first LC resonant circuit having a first inductor (L1) and a first capacitor (C1), and the second filter stage (100-2, 300-2) comprises a second LC resonant circuit having a second inductor (L2) and a second capacitor (C2). The first and second inductors (L1, L2) are connected in series along the first signal path, and the first and second capacitors (C1, C2) are each connected in parallel between the first signal path and the second signal path. The converted periodically varying oscillation signal lies in a frequency range from 5 kHz to 200 kHz, preferably from 16 kHz to 60 kHz, particularly preferably 20 kHz.

Description

Device and method for converting at least one input signal into a low-frequency periodically varying oscillation signal

[0001] The invention relates to a device and method for converting at least one input signal into a low-frequency periodically varying oscillation signal. Background of the invention

[0002] When generating control signals for a resonator to generate ultrasonic waves using a low-frequency, periodically varying oscillation signal, unwanted feedback effects often occur, placing a strain on electronic components and cables. In particular, protective diodes are subjected to significant electrical and thermal stress due to feedback from the residual energy stored in the components of the LC resonant circuit, which impairs the service life of ultrasonic devices. High-frequency interference also occurs, which negatively impacts EMC (electromagnetic compatibility) and thus complicates compliance with the limits of the EMC Directive. Description

[0003] The invention is based on the object of developing a device for converting an input signal into a low-frequency periodically varying oscillation signal with less feedback and thus increased service life and less high-frequency interference.

[0004] The object of the invention is achieved by a device and a method according to the independent patent claims. Preferred developments are the subject of the respective dependent claims.

[0005] The device according to the invention for converting at least one input signal into a low-frequency, periodically varying oscillation signal comprises a first signal path between a first terminal, for example a first input, and a second terminal, for example a first output, a second signal path between a third terminal, for example a second input, and a fourth terminal, for example a second output, and at least one multi-stage electrical filter with at least two series-connected filter stages for converting an input signal into an electrical, periodically varying oscillation signal. The first filter stage comprises a first LC resonant circuit with a first inductance, for example a coil, and a first capacitance, for example a capacitor.The second filter stage comprises a second LC resonant circuit with a second inductance, for example, a coil, and a second capacitance, for example, a capacitor. The first and second inductances are connected in series along the first signal path. The first and second capacitances are each connected in parallel between the first signal path and the second signal path. the second signal path. The converted periodically varying oscillation signal lies in a frequency range from 5 kHz to 200 kHz, preferably from 16 kHz to 60 kHz, particularly preferably from 20 kHz. In other words, the first inductance is connected to the first terminal and the second terminal, and the second inductance is connected to the third terminal and the fourth terminal. Multi-stage electrical filters allow the respective inductances and capacitances of each stage to be specifically adapted or optimized to the respective application by cascading or connecting filter stages in series, in order to improve the characteristics of the converted low-frequency periodically varying signals.It has been found that – in contrast to a single-stage LC resonant circuit – with each additional stage, the occurrence of unwanted feedback effects at the inputs can be reduced, thereby correspondingly reducing the load on the components and lines caused by the feedback effects. By reducing the load on the components and lines (e.g., heating of the protection diodes and / or MOSFETs (or transistors, IGBTs, or GaN)), the efficiency and thus the efficiency of power transmission are increased. The upstream filter stage preferably represents an intermediate processing step for the input signal. The downstream filter stage therefore receives the intermediately processed input signal and converts it into the desired low-frequency, periodically varying oscillation signal.Intermediate processing also allows for reliable conversion of input signals with narrow pulse widths, which cannot be converted into the desired oscillation signals in a single-stage LC resonant circuit. Low frequency refers, for example, to frequencies in the range from 3 kHz to 200 kHz, particularly preferably from 3 kHz to 20,000 kHz.

[0006] In a preferred embodiment, at least one of the series-connected filter stages contains at least two inductors, one of which is arranged in the second signal path. The two inductors are arranged relative to each other in such a way that both inductors contribute to the inductance required for the function of the LC resonant circuit, thus amplifying each other in a superimposed manner.

[0007] In a further preferred embodiment, the at least two inductances are magnetically coupled to one another.

[0008] In a further preferred embodiment, the coupled inductances have a Coupling factor or coupling factor K, which lies between > 0 and < 1, preferably approximately 1.

[0009] In a further preferred embodiment, the coupled inductances have a coupling factor K, which is zero.

[0010] In a further preferred embodiment, the inductance of the upstream filter stage is smaller than the inductance of the downstream filter stage and / or the capacitance of the upstream filter stage is greater than the capacitance of the downstream filter stage. Preferably, the inductance of the upstream filter stage is less than or equal to 0.9 times, 0.8 times, 0.7 times, 0.6 times or 0.5 times the inductance of the downstream filter stage. Preferably, the capacitance of the upstream filter stage is more than or equal to 1.1 times, 1.2 times, 1.3 times, 1.4 times or 1.5 times greater than the capacitance of the downstream filter stage. Because the capacitance of the upstream stage is greater than the capacitance of the downstream stage, the focus of the feedback effects available energy is shifted towards the output, so that feedback at the input is less likely, particularly due to the comparatively smaller inductance of the upstream filter stage at the input, especially because the feedback signals between the stages of the multi-stage electrical filter can at least partially cancel each other out.

[0011] In a further preferred embodiment, at least one signal, also called an input signal, is present between the first and third terminals, the form of which preferably corresponds specifically or approximately to a PWM signal or triangular signal, wherein each input signal is preferably a periodically and / or time-varying input signal.

[0012] In a further preferred embodiment, the second terminal and the fourth terminal are each connected via at least the first capacitance.

[0013] In a further preferred embodiment, the first terminal and the third terminal are each connected via at least the first capacitance.

[0014] In a further preferred embodiment, the device further comprises at least one load, preferably a sound transducer, e.g., a piezoelectric transducer. The second connection and the fourth connection are connected to the at least one load. The surge or piezoelectric transducer is preferably configured to be connected to a resonator and to control it to transmit ultrasonic waves. The ultrasonic waves are preferably controlled at the frequency corresponding to the converted vibration signal. The device preferably comprises said resonator.

[0015] In a further preferred embodiment, the coupled inductors are preferably operated in push-pull mode. Due to the resulting effective series connection of the inductors, this leads to a doubling of the inductance values.

[0016] In a further preferred embodiment, the connection points of the input signal(s) and load(s) are interchangeable. The input signal(s) are then coupled to the second and fourth terminals, and the load(s) are applied to the first and third terminals.

[0017] In a further preferred embodiment, the multi-stage electrical filter is in a Half-bridge circuit integrated.

[0018] In a further preferred embodiment, the multi-stage electrical filter is in a Full bridge circuit integrated.

[0019] In a further preferred embodiment, the multi-stage electronic filter is configured to convert an input signal with a pulse width of less than 2 ps into a low-frequency, periodically varying oscillation signal, e.g., in the preferred frequency range from 16 kHz to 60 kHz. Single-stage electronic filters cannot convert such short pulse widths into a corresponding oscillation signal of sufficient quality.

[0020] Furthermore, a method for converting at least one input signal into a low-frequency, periodically varying oscillation signal is provided. An input signal is input into the above-mentioned device, and the input signal is converted into a low-frequency, periodically varying oscillation signal using the device. The advantages and features mentioned with the device are achieved analogously with the method. A repetitive description is therefore omitted.

[0021] The invention is explained below in exemplary embodiments with reference to the accompanying drawings. They show:

[0022] Fig. 1 is a schematic representation of a filter stage according to a first embodiment,

[0023] Fig. 2 is a schematic representation of a device for converting at least one input signal into a low-frequency periodically varying oscillation signal according to a first embodiment,

[0024] Fig. 3 is a schematic representation of a filter stage according to a second embodiment,

[0025] Fig. 4 is a schematic representation of a device for converting at least one input signal into a low-frequency periodically varying oscillation signal according to a second embodiment,

[0026] Fig. 5 is a schematic representation of a device for converting at least one input signal into a low-frequency periodically varying oscillation signal according to a third embodiment,

[0027] Fig. 6 is a schematic representation of a device integrated in a half-bridge circuit for converting at least one input signal into a low-frequency periodically varying oscillation signal, and

[0028] Fig. 7 is a schematic representation of a device integrated in a full-bridge circuit for converting at least one input signal into a low-frequency periodically varying oscillation signal.

[0029] The present invention preferably relates to a device and method for converting at least one signal into low-frequency periodically varying signals by at least one electrical filter 100, 300, preferably for conversion into an electrical oscillation, e.g., a sine signal. The electrical filter according to the invention can also consist of at least one combination of the electrical filters 100, 300. The periodically varying signals are in a frequency range from 5 kHz to 200 kHz, preferably from 16 kHz to 60 kHz, e.g., 20 kHz.

[0030] The present invention preferably contains at least two inductors and at least one capacitor.

[0031] At least two inductors can preferably be coupled together.

[0032] The coupled inductances preferably have a coupling factor K which is between > 0 and < 1, preferably approximately 1.

[0033] The coupled inductors preferably have a coupling factor K of zero. If the coupling factor is zero, both inductors are not coupled, i.e., decoupled from each other.

[0034] Between terminals 100a and 100c, there is preferably at least one signal, also called an input signal, the form of which preferably corresponds specifically or approximately to a PWM signal or triangular signal, wherein each input signal is preferably a periodically and / or time-varying input signal.

[0035] In addition, the two terminals 100a and 100c may preferably each be connected via at least one capacitance.

[0036] Terminals 100b and 100d are preferably connected to at least one load, preferably a sound transducer, e.g., a piezoelectric sound transducer.

[0037] The connection points of the input signal(s) and load(s) can be swapped. Then the input signal(s) are connected to terminals 100b and 100d, and the load(s) are connected to terminals 100a and 100c.

[0038] The apparatus and method for converting at least one input signal into low-frequency periodically varying signals by at least one electrical filter preferably comprises, as shown in Figure 1, a transformer filter 100.

[0039] The transformer filter is a low-pass filter.

[0040] The transformer filter 100 has a first inductance 110, which is connected to a first terminal 100a and a second terminal 100b of the filter 100. Furthermore, the filter 100 has a second inductance 120, which is connected to a third terminal 100c and a fourth terminal 100d of the filter 100. The two inductances 110 and 120 can be inductively coupled to one another, forming a transformer with a coupling factor K. The two inductances 110 and 120 also have a winding orientation, which is indicated by the two white dots in the figure. The winding orientation is accordingly so pronounced that the two inductances complement one another and do not diminish or even cancel each other out.

[0041] In addition, the two terminals 100b and 100d of the transformer filter 100 are each connected via at least one capacitor 130.

[0042] The capacitance 130 or the corresponding capacitive contributions in the filter 100 can be formed using normal capacitances, such as capacitors.

[0043] The differential mode and the common mode of the coupled inductors differ on the one hand due to the effective circuit, which in common mode leads to a halving due to the resulting effective parallel connection of the inductors and in differential mode to a doubling due to the effective series connection of the inductors.

[0044] The coupled inductors are preferably operated in push-pull mode, as indicated by the two white dots in Fig. 2. This leads to a doubling of the inductance values ​​due to the resulting effective series connection of the inductors. This allows the size of the inductors to be reduced.

[0045] The coupling factor K indicates the ratio of the two magnetic fluxes in the two inductances

[0046] In addition to single-stage transformer filters, any multi-stage transformer filter can be manufactured and implemented. The respective inductances and capacitances in each stage can be specifically adapted or optimized to the specific application. For example, by cascading or connecting filter stages in series, the characteristics of the converted low-frequency periodically varying signals can be improved, as the following embodiments show.

[0047] Error! Reference source could not be found, shows an embodiment of an electrical multi-stage transformer filter 200 according to the invention, which is essentially a series connection of two filter stages 100-1, 100-2 of the filter 100 according to the invention, which is shown in Error! Reference source could not be found.

[0048] The first filter stage 100-1 has a first inductance 110 and a second inductance 120. The two inductances 110 and 120 are inductively coupled to each other, forming a transformer with a coupling factor K. Furthermore, the two inductances 110 and 120 have a winding orientation indicated by the two white dots in the figure.

[0049] At least one capacitor 130 is connected in series between the first inductance 110 and the second inductance 120.

[0050] The second filter stage 100-2 has a first inductance 210 and a second inductance 220. The two inductances 210 and 220 are inductively coupled to each other, forming a transformer with a coupling factor K. Furthermore, the two inductances 210 and 220 have a winding orientation indicated by the two white dots in the figure.

[0051] At least one capacitor 230 is connected in series between the first inductance 210 and the second inductance 220.

[0052] The number of filter stages connected in series of the filter 100 according to the invention, which is shown in Figure 1, can be combined as desired with the filters 100, 300.

[0053] With a multi-stage transformer filter, very small pulse widths, e.g., less than 2 ps, can be converted into a proper low-frequency, periodically varying signal, preferably a periodic signal such as a sine wave, for example, in the preferred frequency range of 16 kHz to 60 kHz. This is not possible with a conventional single-stage transformer filter.

[0054] The apparatus and method for converting at least one input signal into low-frequency periodically varying signals by at least one electrical filter preferably comprises an LC filter 300, as shown in Fig. 3.

[0055] The LC filter is a low-pass filter.

[0056] The LC filter 300 has an inductance 310 connected to a first terminal 100a and a second terminal 100b of the filter 300.

[0057] In addition, the two terminals 100b and 100d of the LC filter 300 are each connected via at least one capacitor 330.

[0058] The capacitance 330 or the corresponding capacitive contributions in the filter 300 can be formed using normal capacitances, such as capacitors.

[0059] The electrical filters for conversion into oscillations in the mentioned frequency range generally consist of a simple LC combination Error! Reference source could not can be found, with which the voltage of the PWM signal(s) is converted into an electrical oscillation and usually highly transformed.

[0060] In addition to single-stage LC filters, any multi-stage LC filter can be manufactured and implemented. The respective inductances and capacitances in each stage can be specifically adapted or optimized to the specific application. For example, cascading or connecting filter stages in series can improve the characteristics of the converted low-frequency periodically varying signals, as the following examples demonstrate.

[0061] Error! Reference source could not be found, shows an embodiment of an electrical multi-stage LC filter 400 according to the invention, which is essentially a series connection of two filter stages 300-1, 300-2 of the filter 300 according to the invention, which is shown in Error! Reference source could not be found.

[0062] The first filter stage 300-1 has an inductance 310.

[0063] Between the inductance 310 there is at least one capacitance 330 in series.

[0064] The second filter stage 300-2 has an inductance 410.

[0065] Between the inductance 410 there is at least one capacitance 430 in series.

[0066] The number of filter stages connected in series of the filter 300 according to the invention, which is shown in Figure 3, can be combined as desired.

[0067] With a multi-stage LC filter, very small pulse widths, e.g., less than 2 ps, can be converted into a proper low-frequency, periodically varying signal, preferably a periodic signal such as a sine wave, for example, in the preferred frequency range of 16 kHz to 60 kHz. This is not possible with a conventional single-stage LC filter.

[0068] The filter stages connected in series can be combined not only in their number but also in their type between filters 100 and 300.

[0069] An example of a possible combination is shown in the filter arrangement 500.

[0070] The inventive electrical filter of type 100, 200, 300, or 400, or their combinations, as shown in type 500 as an example, can be integrated into a half-bridge circuit. Error! Reference source could not be found, shows an exemplary embodiment.

[0071] The inventive electrical filter of type 100, 200, 300, or 400, or their combinations, as shown in the example of type 500, can be integrated into a full-bridge circuit. Error! Reference source could not be found, shows an exemplary embodiment.

[0072] After the oscillation signal generation, feedback effects usually occur, which in particular pass from the filter 100, 200, 300, 400, 500 into the inputs 100a and 100c and from there act on the protective diodes D1 to D4 and / or MOSFETs M1 to M4 (or transistors, IGBT or GaN), unless the MOSFETs M1 to M4 (or transistors, IGBT or GaN) shown in Fig. 6 and 7 are closed by a corresponding control signal A, B, G and / or H. In this case, excessive electrical and thermal stress on the diodes D1 to D4 occurs. and / or MOSFETs M1 to M4 (or transistors, IGBTs, or GaN), which reduces their service life. The inventive use of the multi-stage electrical filter reduces the occurrence or extent of such feedback effects, thus increasing the service life of ultrasound devices that use the inventive multi-stage electrical filter for signal conversion. By reducing thermal stress (heating of the protective diodes and / or MOSFETs M1 to M4 (or transistors, IGBTs, or GaN)), the efficiency and thus the effectiveness of power transmission are increased.

[0073] One aspect is directed to a device and method for converting at least one signal into low-frequency periodically varying signals by at least one electrical filter 100, preferably for conversion into an electrical oscillation, e.g. a sinusoidal signal, wherein the electrical filter according to the invention can also consist of at least one combination of the electrical filters 100, 300, characterized in that the converted periodically varying signals are in a frequency range from 5 kHz to 200 kHz, preferably from 16 kHz to 60 kHz, e.g. 20 kHz.

[0074] Device and method according to aspect 1, characterized in that the electrical filter 100 contains at least two inductances and at least one capacitor.

[0075] Device and method according to aspect 1, characterized in that at least two inductors are coupled to one another.

[0076] Device and method according to aspect 1, characterized in that the coupled inductances have a coupling factor K which is between > 0 and < 1, preferably approximately 1.

[0077] Device and method according to aspect 1, characterized in that the coupled inductances have a coupling factor or coupling factor K which is zero.

[0078] Device and method according to aspect 1, characterized in that a first inductance 110 is connected to a first terminal 100a, a second terminal 100b and a second inductance 120 is connected to a third terminal 100c, a fourth terminal 100d of the filter 100.

[0079] Device and method according to aspect 1, characterized in that between terminals 100a and 100c at least one signal, also called input signal, is present, the form of which preferably corresponds specifically or approximately to a PWM signal or triangular signal, wherein each input signal is preferably a periodically and / or time-varying input signal.

[0080] Device and method according to aspect 1, characterized in that the two terminals 100b and 100d are each connected via at least one capacitor 130.

[0081] Device and method according to aspect 1, characterized in that the two terminals 100a and 100c are each connected via at least one capacitor 130.

[0082] Device and method according to aspect 1, characterized in that the terminals 100b and 100d are connected to at least one load, preferably a sound transducer, e.g., a piezoelectric sound transducer.

[0083] Device and method according to aspect 1, characterized in that the coupled inductances are preferably operated in push-pull, which leads to a doubling of the inductance values ​​due to the resulting effective series connection of the inductances.

[0084] The device and method according to aspect 1, characterized in that the connection points of the input signal(s) and load(s) can be swapped. Then, the input signal(s) are connected to terminals 100b and 100d, and the load(s) are connected to terminals 100a and 100c.

[0085] Device and method according to aspect 1, characterized in that electrical filters of type 100 or 200 or 300 or 400 or their combinations, as shown as an example in type 500, can be integrated in a half-bridge circuit.

[0086] Device and method according to aspect 1, characterized in that electrical filters of type 100 or 200 or 300 or 400 or their combinations, as shown as an example in type 500, can be integrated in a full-bridge circuit.

[0087] Device and method according to aspect 1, characterized in that in the case of multi-stage filters 200, 400, 500, by such a cascading or series connection of filter stages with each stage, the respective inductances and capacitances can be specifically adapted or optimized to the respective application in order to improve the characteristics of the converted low-frequency periodically varying signals.

[0088] Device and method according to aspect 1, characterized in that with a multi-stage filter 100, 300, for example in the preferred frequency range from 16 kHz to 60 kHz, the very small pulse widths as input signal, for example less than 2 ps, can be converted into a regular low-frequency periodically varying signal, preferably a periodic signal, such as a sine wave. List of reference symbols 100 transformer filters 100a first connection 100b second connection 100c third connection 100d fourth connection 110 first inductance (L) 120 second inductance (L) 130 capacity(s) (C) 200 multi-stage transformer filter 210 third inductance 220 fourth inductance 230 capacity(s) (C) 300 LC filters 310 Inductance (L) 330 capacity(s) 400 multi-stage LC filter 410 third inductance (L) 420 fourth inductance (L) 430 capacity(s) (C) 500 filter combinations Ue input voltage A, B control signals G, H control signals M1 to M4 MOSFET or Transistor or IGBT or GaN D1 to D4 diode

Claims

Patent claims 1 . Device for converting at least one input signal into a low-frequency periodically varying oscillation signal, comprising: a first signal path between a first terminal (100a) and a second terminal (100b), a second signal path between a third terminal (100c) and a fourth terminal (100d) and at least one multi-stage electrical filter (200, 400, 500) with at least two series-connected filter stages (100, 300) for converting an input signal into an electrical periodically varying oscillation signal, wherein the first filter stage (100-1, 300-1) has a first LC resonant circuit with a first inductance (L1) and a first capacitance (C1) and the second filter stage (100-2, 300-2) has a second LC resonant circuit with a second inductance (L2) and a second capacitance (C2), wherein the first and the second inductance (L1,L2) are connected in series along the first signal path and the first and second capacitors (C1, C2) are each connected in parallel between the first signal path and the second signal path, characterized in that the converted periodically varying oscillation signal lies in a frequency range of 5 kHz to 200 kHz, preferably from 16 kHz to 60 kHz, particularly preferably from 20 kHz.

2. Device according to claim 1, characterized in that at least one of the series-connected filter stages (100, 300) contains at least two inductances, of which one of the at least two inductances is arranged in the second signal path.

3. Device according to claim 2, characterized in that the at least two inductances are magnetically coupled to one another.

4. Device according to claim 3, characterized in that the coupled inductances have a coupling factor K which is between > 0 and < 1, preferably approximately 1.

5. Device according to claim 3, characterized in that the coupled inductances have a coupling factor K which is zero.

6. Device according to one of the preceding claims, characterized in that the inductance of the upstream filter stage (100-2, 300-2) is smaller than the inductance of the downstream filter stage (100-1, 300-1) and / or the capacitance of the upstream filter stage (100-2, 300-2) is greater than the capacitance of the downstream filter stage (100-1, 300-1).

7. Device according to one of the preceding claims, characterized in that between the first and third terminals (100a, 100c) at least one signal, also input signal called, whose shape corresponds, preferably concretely or approximately, to a PWM signal or triangular signal, wherein each input signal is preferably a periodically and / or time-varying input signal.

8. Device according to one of the preceding claims, characterized in that the second terminal (100b) and the fourth terminal (100d) are each connected via at least the first capacitor (C1).

9. Device according to one of the preceding claims, characterized in that the first terminal (100a) and the third terminal (100c) are each connected via at least the first capacitor (C1).

10. Device according to one of the preceding claims, characterized in that the device further comprises at least one load, preferably a sound transducer, e.g. a piezoelectric sound transducer, and the second terminal (100b) and the fourth terminal (100d) are connected to the at least one load.

11. Device according to one of claims 3 to 5, characterized in that the coupled inductances are operated in push-pull mode.

12. Device according to one of the preceding claims, characterized in that the connection points of input signal(s) and load(s) are interchangeable.

13. Device according to one of the preceding claims, characterized in that the multi-stage electrical filter (200, 400, 500) is integrated in a half-bridge circuit.

14. Device according to one of claims 1 to 11, characterized in that the multi-stage electrical filter (200, 400, 500) is integrated in a full-bridge circuit.

15. Device according to one of the preceding claims, characterized in that the multi-stage electronic filter (200, 400, 500) is configured to convert an input signal with a pulse width of less than 2 ps into a low-frequency periodically varying oscillation signal, e.g. in the preferred frequency range from 16 kHz to 60 kHz.

16. A method for converting at least one input signal into a low-frequency periodically varying oscillation signal, comprising the steps: Inputting an input signal into the device according to any one of the preceding claims and Converting the input signal into a low-frequency periodically varying oscillation signal using the device.

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