DE102013105585B4 - Arrangement and method for generating a voltage - Google Patents

Abstract

Arrangement for generating a voltage, comprising a converter (2) which generates an electrical input alternating voltage (V (t)) using a piezoelectric effect, and an interface arrangement (3) which is connected to the converter (2) and the in the converter (2) generated AC input voltage (V (t)) converts into a DC voltage and buffered and this DC voltage as output voltage (12, Ua) provides for a consumer at an output of the interface arrangement (3), wherein the interface arrangement ( 3) has a rectifier (11) whose inputs are connected to the converter (2) and whose outputs are connected to a series circuit consisting of an inductance (7, L) and an electronic switch (5), that a first terminal of the inductance (7, L) having a first terminal of a capacitance (10, Cs) and a first terminal of the output (12) and a second terminal of the inductance (7, L) via a diode (9) having a m second terminal of a capacitance (10, Cs) and a second terminal of the output (12) of the interface arrangement (3) is connected, characterized in that the electronic switch (5) has a control input, which with a drive circuit (13) for the transmission of a drive signal is connected and that the voltage supply terminals of the drive circuit (13) are connected to the outputs of the rectifier (11).

Description

The invention relates to an arrangement for generating a voltage, comprising a converter which generates an electrical input alternating voltage (V (t)) using a piezoelectric effect, and an interface arrangement which is connected to the converter and the input AC voltage generated in the converter ( V (t)) converts into a DC voltage (U _a ), caches and this DC voltage (U _a ) provides as an output voltage for a consumer at an output of the interface arrangement, wherein the interface arrangement comprises a rectifier whose inputs to the converter are connected and whose outputs are connected to a series circuit consisting of an inductance and an electronic switch, wherein a first terminal of the inductor having a first terminal of a capacitor and a first terminal of the output and a second terminal of the inductance via a diode having a second terminal a capacity and a m is connected to the second terminal of the output of the interface arrangement

The invention also relates to a method for generating a voltage which is generated by a piezoelectric effect, wherein the electrical input AC voltage thus generated (V (t)) in the same direction, stored, and as the output voltage (U _a) for a connectable consumer by means of an interface arrangement is provided, wherein at least at a zero crossing of the electrical input alternating voltage (V (t)) a connection between the input AC voltage (V (t)) and an inductive and a capacitive element energy storage means is separated, that this separation when reaching a maximum or Minimums (minimum - for the amplitude of the negative half-wave of V (t)) of the input AC voltage (V (t)) at a time t ₁ canceled and a charging of the energy storage means is started.

The invention belongs to the field of research "Energy Harvesting". Content of this research area is to supply small, portable electrical systems, such as a radio sensor node for structural monitoring of a component, with energy from its immediate environment.

Possible forms of energy which can be converted into electrical energy in a simple manner are solar energy in the field of photovoltaics, thermal energy, for example by means of a thermocouple, and mechanical energy, for example by means of a piezoelectric transducer.

Since the energy is usually provided by an AC signal source, an electrical interface consists in the simplest case only of a full-wave rectifier (standard interface), at the input of the converter and at the output of the memory element is connected. With this interface, the maximum energy generated can only be extracted by converters with very high coupling factors.

In order to derive the maximum energy provided by low coupling transducers, A. Badel, D. Guyomar, E. Lefeuvre, and C. Richard, "Efficiency Enhancement of a Piezoelectric Energy Harvesting Device in Pulsed Operation by Synchronous Charge Inversion," "Journal of Intelligent Material Systems and Structures, vol 16, pp. 889-901, 2005 featured Synchronized Switch Harvesting on Inductor (SSHI) interface.

In converters with intermediate coupling factors, the method described in E. Lefeuvre, A. Badel, C. Richard, and D. Guyomar, "Piezoelectric Energy Harvesting Device Optimization by Synchronous Electric Charge Extraction," Journal of Intelligent Material Systems and Structures, vol. 16, pp. 865-876, 2005, which is also independent of the operating point of the connected load.

In addition, there is the Double Synchronized Switch Harvesting (DSSH) interface, which is described in M. Lallart, L. Garbuio, L. Petit, C. Richard, D. Guyomar, "Double Synchronized Switch Harvesting (DSSH): A new energy harvesting scheme for efficient energy extraction, "IEEE Trans. Ultrason. Ferroelectrics Freq. Contr., Vol 55, pp. 2119-2130, 2008, and the Enhanced Synchronized Switch Harvesting (ESSH) interface disclosed in H. Shen, J. Qiu, H. Ji, K. Zhu, M. Balsi, "Enhanced synchronized switch harvesting: A new energy harvesting scheme for efficient energy extraction. "Smart Mater. Struct., 115017, 2010.

Both methods are based on a combination of SSHI and SECE interface to combine their advantages. An almost complete overview of all possible interface circuits from the prior art known in the art can be found in D. Guyomar, M. Lallart, "Recent Progress in Piezoelectric Conversion and Energy Harvesting Using Nonlinear Electronic Interfaces and Issues in Small Scale Implementation "Micromachines, vol. 2, pp. 274-294, 2011.

The standard and SSHI interface have the great disadvantage that the power generated is dependent on the operating point of the load (memory element and / or consumer). The SECE interface, on the other hand, provides power independent of the load element.

The standard, SSHI, and SECE interfaces have the disadvantage that the maximum power provided by the converter depends on its coupling factor. Consequently, it is necessary to adapt the energy converter to the specific characteristics of these interface circuits. This limitation in the design of the converter leads to the fact that the overall system is limited by the transducer characteristic. In addition, the manufacturing tolerances of the converter prevent optimal adaptation to the respective interface circuit.

The DSSH and ESSH interfaces combine the SSHI and SECE interfaces. Both methods are independent of the load and can be adapted to converters of any coupling.

The disadvantage of these combined methods is the double the number of lossy components compared to the normal SECE interface. The control electronics are more complex with the DSSH and ESSH interface than with the classic SECE interface. The large number of lossy components and the complex control logic with high own energy consumption lead to a low efficiency.

From D. GUYOMAR, M. LALLART: Recent Progress in Piezoelectric Conversion and Energy Harvesting Using Nonlinear Electronic Interfaces and Issues in Small Scale Implementation. In: Micromachines, 2011, 274-294 an arrangement according to the preamble of claim 1 and a method according to the preamble of claim 5 are known.

Thus, the object of the invention is to provide an arrangement and method for generating a voltage, which is independent of the load and the converter used, the power output for feeding the connected load is maximized.

Furthermore, the self-consumption of the transducer assembly is to be minimized and thus the efficiency can be improved.

In an arrangement for generating a voltage is therefore proposed that the electronic switch has a control input, which is connected to a drive circuit for transmitting a drive signal and that the power supply terminals of the drive circuit are connected to the outputs of the rectifier.

The switch of the interface arrangement is a controllable with a control signal electronic switch. The control signal controlling the switch is generated by a drive circuit which is connected with its control output to the control input of the electronic switch. The generation of the control signal is carried out according to the method shown in this description.

In one embodiment of the invention, it is provided that the drive circuit has a voltage divider, an electronic switch, a comparator, a maximum detector and a logic gate.

A first input of the drive circuit is connected to the voltage output of the rectifier arrangement. Within the drive circuit, this input is connected to the maximum detector, a first input of a comparator and a first terminal of an electronic switch P1. The maximum detector has an output which is connected to a first input of a logic gate. The output of this logic gate is connected to the control input of the electronic switch of the interface arrangement and the control input of the electronic switch P1, which is arranged within the drive circuit.

The second terminal of the electronic switch P1 is connected via a voltage divider to the second terminal of the rectifier arrangement. The center tap of the voltage divider is connected to a second input of the comparator.

In a particular embodiment it is provided that the voltage divider is a capacitive voltage divider.

In one embodiment of the invention it is provided that the logic gate is an RS flip-flop.

The voltage part can be implemented by means of two adjustable capacitances, since the input voltage V (t) is an alternating voltage. By varying the values of the adjustable capacitances, the timing for generating a control signal for opening the electronic switch in the interface arrangement can be accurately adjusted.

In one embodiment, it is provided that the charging process of the energy storage device is terminated at a time t ₂ 'before reaching the zero crossing of the input AC voltage (V (t)).

The classical SECE method is modified in such a way that the power optimum for any loads and coupling factors connected as load, between the converter and the interface arrangement, can be adjusted.

According to the invention, the switching means customary in a SECE interface is controlled by means of the method according to the invention. Nothing changes in the basic structure of the SECE interface itself. In the classic SECE interface, a switch is used as the switching means and closed whenever the input AC voltage V (t) at the converter terminals becomes maximum, and then immediately after the voltage V (t) at the converter terminals becomes zero. By this driving method, the maximum power occurs only with converters with a certain coupling factor (converter characteristic).

In the here presented, improved SECE interface according to the invention, the time of opening of the switching means is not set to the zero crossing of the voltage V (t) at the converter terminals. The electronic switch is opened in the SECE interface according to the invention at a time in which the terminal voltage of the converter V (t) reaches a specific, adjustable value. As a result, the power maximum can be shifted to other coupling factors. This results in an additional degree of freedom in the design of the converter for a SECE interface.

The SECE interface can be operated by the inventive control with almost any converters, in terms of achievable coupling factor, as well as any systems that represent the load to be connected, so that maximum performance is achieved.

By adapting the SECE interface to converters with almost any coupling factor, both can now be designed and optimized independently of each other.

The small number of components and the low self-consumption of the SECE interface itself allow a high degree of efficiency and expand the possible application space towards energy self-sufficient systems. These are systems that can and should consume very little power, for example due to space constraints or low or rare excitation of the converter.

Furthermore, a reduced number of components leads to a reduction in manufacturing costs. The implementation of such a system as an integrated circuit is thereby favored (reducing the number of connections). In addition, the robustness of the system is increased by the reduced number of components, since there are fewer potential sources of error, such as cold solder joints.

In one embodiment of the invention, it is provided that the time t ₂ 'is adjustable.

The method provides that the switch-off for the charging of the energy storage means is arbitrarily adjustable. In this way, adaptation to different coupling factors, for example between a piezo transducer and the interface arrangement, can be achieved. Since the piezoelectric transducers deviate from one another in their parameters even when the same production method is used with the same production steps, optimum adaptation can be achieved by means of the method according to the invention.

In one embodiment, it is provided that the time t ₂ 'can be set according to the magnitude of a desired residual voltage V (t ₂ ') to V (t ₂ ') = qV _M with a factor q in the range between zero and one.

It is intended to select the switching time t ₂ 'according to a desired residual voltage of the input AC voltage V (t). For this purpose, a ratio of the instantaneous voltage at the moment of switching the electronic switch to interrupt the charging of the energy storage means and the maximum amplitude V _{M of} the input AC voltage V (t) may be formed. By introducing a factor q, which can assume the value range between zero and one, this ratio can be represented according to V (t ₂ ') = qV _M.

In a further embodiment, it is provided that the factor q can be set by means of a capacitive voltage division means according to q = C ₂ / (C ₁ + C ₂ ).

One possible realization for setting the switching time t ₂ 'is the use of a capacitive voltage divider, via which the input AC voltage (V (t)) can be applied at least indirectly. Another possibility is to rectify the AC input voltage (V (t)) before applying to the voltage divider.

The factor q can always be set by the ratio of the capacities according to q = C ₂ / (C ₁ + C ₂ ).

The invention will be explained in more detail with reference to an embodiment. In the accompanying drawings shows

1 a spring-mass-system model for modeling a piezoelectric transducer from the prior art,

2 a representation of a SECE interface with a part of a Piezowandlermodells from the prior art,

3 a representation of a current-time curve for the current I _p (t) for the current of the piezo transducer source and a representation of a voltage-time curve of the output voltage V (t) of the piezoelectric transducer,

4 a representation of the normalized ratio between the powers P and P _max as a function of the parameters / material properties of the piezoelectric transducer,

5 a representation of a voltage-time curve of the output voltage V (t) of the piezoelectric transducer in the application of the control method according to the invention for the switching means,

6 a further representation of the normalized ratio between the powers P and P _max as a function of the parameters / material properties of the piezoelectric transducer in the application of the control method according to the invention for the switching means with different values of the factor q (q = 0, q = 0.4, and q = 0.7),

7 an inventive realization of a drive circuit by means of a drive circuit and

8th a further realization of a drive circuit according to the invention with a representation of the elements used in the drive circuit.

The invention relates to a method by which the electrical energy provided by an excited converter with the highest possible efficiency of a memory device (large capacitor or battery) or a consumer should be made available directly. It can be used any energy sources, as long as the electrical subsystem of the converter or the source can be modeled as a high-impedance alternating signal source. This circuit, which implements this method, is referred to below as an interface.

First, the basics for the derivation of the known from the prior art SECE method (Synchronous Electric Charge Extraction) will be described.

A piezo transducer can be used as a spring-mass system, as in the 1 imaged, model. The electrical subsystem of the piezo converter 2 can as a capacitance C _P 6 with parallel-connected AC power source αu. 4 are modeled. This power source 4 is about the electromechanical Conversion coefficients α from the speed of the deflection u. controlled by the piezoelectric transducer. Ie. on the capacitance C _p 6, an electrical charge is generated which is proportional to the deflection u of the piezoelectric transducer 2 is what corresponds to the piezoelectric effect. The frequency of the AC source 4 corresponds to the resonant frequency of the piezoelectric transducer.

This system can be described by a differential equation system of (1) and (2): F (t) = M * ü (t) + C * u (t) + K * u (t) + α * V (t), (1) I (t) = α * u (t) -C _P * V (t). (2)

M

– Masse

K

– Federkonstante

C

– mechanischer Verlustkoeffizient (Reibungskoeffizient)

α

– Wandlungskoeffizient

C_P

– Piezowandlerkapazität

F(t)

– Kraft,

u(t)

– Auslenkung,

I(t)

– Ausgangsstrom,

V(t)

– Ausgangsspannung

The following symbols are used:

M

- Dimensions

K

- Spring constant

C

- mechanical loss coefficient (friction coefficient)

α

- conversion coefficient

C _P

- Piezo converter capacity

F (t)

- Force,

u (t)

- deflection,

I (t)

Output current,

V (t)

- Output voltage

The in the 2 illustrated arrangement for generating a voltage 1 includes an electrical SECE interface 2 and a piezo-transducer connected to it 5 which only simplifies in the 2 is shown.

The signal curves necessary for the derivation are in the 3 shown.

• • alle Dioden haben eine Schwellspannung von 0 V
• • alle Bauelemente sind verlustlos
• • der Wandler wird mit einer sinusförmigen Kraft F(t) mit der Amplitude F_M bei seiner Resonanz betrieben
• • Aufgrund der Filterwirkung des Feder-Masse-Systems wird angenommen, dass die Auslenkung u(t) und damit auch die Geschwindigkeit der Auslenkung u .(t) ebenfalls sinusförmige Signale sind, obwohl durch den Schaltbetrieb Oberwellen auf V(t) erzeugt werden.
• • Es wird angenommen, dass das Zeitintervall [t1...t2] sehr klein gegenüber der Schwingungsperiode des Piezowandlers ist. Das Intervall [t1...t2] in der 3 ist lediglich zu Erklärungszwecken vergrößert dargestellt.

The following assumptions were made for the derivation:

• • all diodes have a threshold voltage of 0V
• • all components are lossless
• • The transducer is operated with a sinusoidal force F (t) with the amplitude F _M at its resonance
• • Due to the filtering effect of the spring-mass system, it is assumed that the deflection u (t) and thus also the speed of the deflection and (t) are also sinusoidal signals, although harmonics are generated at V (t) by the switching operation.
• • It is assumed that the time interval [t1 ... t2] is very small compared to the oscillation period of the piezo converter. The interval [t1 ... t2] in the 3 is shown enlarged only for explanatory purposes.

From time t ₀ to time t ₁ is the switch 5 opened, so that the converter 2 is idle. During this time, a charge and thus a voltage V (t) builds up on the piezo-transducer capacitance C _P 6. At time t ₁ , this voltage becomes V (t), as in FIG 3 shown, maximum and thus the energy on C _P 6. At time t ₁ then the switch 5 closed, reducing the capacitance C _P 6 and the coil L 7, via the rectifier 11 coupled, form a kind of parallel resonant circuit. In this description, the two elements coil L and capacitance C _{S of} the interface arrangement are also referred to as energy storage means, since the energy generated by the transducer is temporarily stored in the inductance L and subsequently as a charge on the capacitance C _S.

The desk 5 remains closed so long until the time t _2, the piezo terminal voltage V (t ₂ ) = 0 and the coil current is maximum. Now, the entire energy of the resonant circuit, which was still stored at time t ₀ on C _P 6, in the coil L 7. If now the switch 5 is reopened, the coil L 7 discharges through the diode 9 to the memory element C _S 10, the current I 8 flows. After discharging the coil L 7, the next cycle starts from the front, but now with the opposite (negative) half wave of V (t).

The transfer of energy from C _P 6 to L 7 happens very quickly, since the oscillation period of the piezoelectric transducer 2 much larger than the period of the resonant circuit of L 7 and C _P 6.

auf die Speicherkapazität C_S 10 transferiert. Der Faktor 2 ist begründet durch die positive und negative Halbwelle.So, the SECE interface gets an energy of:

transferred to the storage capacity C _S 10. The factor 2 is due to the positive and negative half wave.

This corresponds to a power flow averaged over time of:

mit I(t) = αu .(t) = I_Msin(ω_Pt) und V(t₀) = 0. (6) Because the converter 1 Most of the time is idle, the switch 5 in the 2 is open most of the time, the voltage V _M can be calculated by solving the following equation (ω _P resonant frequency of the piezo).

With I (t) = αu (t) = I _M sin (ω _P t) and V (t ₀ ) = 0. (6)

If one solves the integral (5) with the boundary conditions of (6), then for V _M :

From (6) the calculation of the current amplitude I _M results in αω _P u _M (u _M - amplitude of the deflection). For V _M this results in:

If one now uses (8) in (4), one obtains the power flow as a function of the amplitude of the displacement u _M :

This is only dependent on the amplitude of the deflection u _M. Now to calculate u _M , a power balance is set up at resonance. For a power balance must be (1) on both sides with the deflection speed and (t) be multiplied. On the left is then the power supplied to the system, and then on the right is how the power supplied to the individual components of the spring-mass system from the 1 divides.

At a resonance, the energy in a resonant circuit is constant (the energy is constantly switched back and forth between spring and mass), d. h. that no power in spring and ground is fed. The complete power that is supplied, on the one hand in the damper C as mechanical losses and on the other hand, it is converted into the electric power P.

This results in the following current account (P was calculated in (9)):

F (t) and (t) and are sinusoidal signals, which are replaced by their RMS to calculate the power.

Due to the fact that and (t) is sinusoidal, its amplitude v _M is calculated as: ν _M = ω _P u _M. (12)

With (11) and (12) u _M can now be calculated:

If one now uses (13) in (9), the power transferred to the memory Cs is obtained as a function of the force amplitude F _M.

The maximum transferable capacity is:

A key figure that summarizes the parameters of the piezos is the product of electromechanical coupling k ² and quality factor of the mechanical spring-mass system Q _m :

If one now uses (16) in (14) and normalizes this resulting equation to (15), one obtains:

Equation (17) describes the transmitted power as a function of the piezoparameters (in the form of k ² Q _m ) normalized to the maximum transmittable power (without depending on the magnitude of the applied force F _M ). This feature is very useful for comparing different methods. From (17) results in the normalized representation P / P _max in the diagram in 4 according to the state of the art SECE method.

This diagram in 4 For comparison, the curve of a simple bridge rectifier was added as an interface circuit labeled "standard". It should also be mentioned that the standard interface for the maximum transmitted power also applies (15).

However, the standard interface still has to be terminated with an optimal load resistor.

The problem with the known from the prior art method is that with each cycle of the piezoelectric transducer 2 taken energy leads to an attenuation of the mechanical subsystem of the transducer (inverse piezoelectric effect). The greater the electromechanical coupling factor, the stronger the damping of the mechanical subsystem. An attenuation of the mechanical subsystem means that the deflection speed u. is reduced, which in turn reduces the amplitude of the current source in the 2 and thus reduces the electrical energy generated by the transducer.

The method according to the invention for controlling the SECE interface will be described below 2 explained.

Like from the 4 can be seen, the maximum transferable power can only be achieved for a specific piezo parameter set (k ² Q _m = 1/2 ≈ 0.707). The idea behind the new SECE method is not to open the switch until time t ₂ as in the 3 (If V (t ₂ ) = 0 and thus the energy transfer from C _P to L is completely completed), but earlier again to t ₂ 'to open when still a certain residual energy and thus a certain residual stress (qV _M ; q = [0 ... 1) is preserved on C _P , as in the 5 is shown. The factor q is the ratio of the voltage at the time of opening the switch V (t ₂ ') to the amplitude V _M (q = V (t ₂ ') / V _M ).

In comparison with (3), the energy converted per piezoelectric period is thus:

The performance averaged over time is thus:

V _M can be calculated again by solving (5). This time, however, with the boundary condition V (t ₀ ) = -qV _M (see 5 ).

Inserting (20) in (19) gives:

As with the derivation of the old SECE method, u _M can be determined by evaluating the power balance at resonance. It follows:

With (21) and (22), the transmitted power can now be calculated as a function of the force F _M and the ratio q.

Equation (23) shows that the power can be influenced by varying q. If q = 0, then equation (23) exactly matches equation (14), which corresponds to classic SECE operation. Substituting (16) into (23) and normalizing the resulting equation to (15) yields:

This equation is in the diagram ( 6 ) for different values of q. It can be seen that by setting q, the power maximum can be achieved in a wide range of k ² Q _m . This makes the new SECE method much more independent of the parameters of the piezo converter.

As in the classic SECE method, the switch 5 is open from time t ₀ to time t ₁ . If then at time t _1, the voltage V (t) and thus the energy on the capacitance C _P 6 is maximum, the switch 5 closed and the energy is transported by C _P 6 in the coil L 7.

But instead of waiting until the energy transport into the coil L 7 has been completed (V (t) = 0), the switch now appears 5 already opened, as it is in the 5 at time t ₂ 'is shown, so that a residual voltage V (t ₂ ') = qV _M (q = [0 ... 1]) and thus a residual energy to C _P 6 remains. This reduces the damping of the mechanical subsystem of the transducer 2 For large electromechanical coupling factors and leads to an increase in the electrical energy generated by the converter 2 in the steady state.

According to the invention, it is provided that the parameter q is variably adjustable in the range between 0 and 1. In this way, the maximum power is taken from converters with almost any coupling with this novel SECE method. In the 6 the generated power is represented as a function of the electromechanical coupling for different q values, where q = 0 corresponds to the classical SECE method.

For comparison, the characteristic of the standard interface has been added.

The switching means 5 For example, as a transistor switch, as in the 7 represented, realized. For a transistor switch 5 triggering drive circuit 13 , which technically implements the inventive method described above, there are many possibilities. Therefore, the drive of the transistor switch N1 is 5 in the 7 initially shown only as a black box.

A possible only exemplary realization of the drive circuit 13 is in the 8th shown.

The drive circuit is connected with its voltage supply inputs to the arranged in the interface arrangement rectifier circuit. This ensures that the overall arrangement works without an external or internal additional voltage source.

Except for the voltage supply of the elements of the drive circuit, the voltage input for detecting a voltage maximum of the input AC voltage V (t) with the input of a maximum detector 15 , a first input of a comparator 17 and the electronic switch P1. That of the maximum detector 15 generated output signal is connected to a set input of an RS flip-flop 18 coupled. With the detection of the maximum is at the output of the RS flip-flop 18 a control signal is provided which includes both the electronic switch 5 as well as the electronic switch 16 by controls. Thus, the charging of the energy storage means in the interface arrangement starts 3 , The energy storage means here consists of the charging capacitor C _S 10 and the necessary for the production of energy from the converter inductance L 7 ,

The switching of the switch P1 16 causes the input AC voltage V (t) via this switch also at the voltage divider 14 is applied. This is designed as a capacitive voltage divider with two adjustable capacitances. A partial voltage of this voltage divider 14 , which is established between the partial capacitances C ₁ and C ₂ , from this node to the second input of the comparator 17 guided. By means of this voltage divider, the factor q is set and thus the turn-off time t ₂ 'in which the comparator 17 a control signal for resetting the RS flip-flop 18 generated. With this reset controls the control signal of the RS flip-flop 18 both the switch 5 as well as the switch P1 again, whereby the charging of the energy storage means is terminated.

The factor q can be obtained by means of a capacitive voltage divider 14 set here as follows:

The switch P1 16 is closed all the time, so via the voltage divider 14 the voltage V _rect (t) drops. If now a maximum / vertex in V _rect (t) by means of the maximum detector 15 is detected and the switch N1 5 is closed, the switch P1 16 is opened in parallel, so that this maximum value / amplitude value V _M on the divider 14 remains stored.

About the partial capacitance C _{2 of} the voltage divider 14 then drops off qV _M and is the comparator 17 as a reference to open the switch N1 5 available. When the switch N1 5 P1 16 is closed again and the cycle starts again.

LIST OF REFERENCE NUMBERS

1

Arrangement for voltage generation

2

converter

3

Interface arrangement (SECE)

4

AC power source αu.

5

electronic switching device / switch

6

Capacity C _p

7

Inductance L

8th

Electricity I

9

diode

10

Capacity C _s

11

rectifier

12

Output / output voltage U _a

13

drive circuit

14

capacitive voltage divider

15

maximum detector

16

Switch P1

17

comparator

18

RS flip-flop

Claims (8)

Arrangement for generating a voltage, comprising a converter ( 2 ), which generates an electrical input alternating voltage (V (t)) using a piezoelectric effect, and an interface arrangement ( 3 ), which with the converter ( 2 ) and in the converter ( 2 ) generated alternating voltage (V (t)) converts into a DC voltage and cached and this DC voltage as an output voltage ( 12 , U _a ) for a consumer at an output of the interface arrangement ( 3 ), the interface arrangement ( 3 ) a rectifier ( 11 ) whose inputs to the converter ( 2 ) and whose outputs are connected in series with an inductance ( 7 , L) and an electronic switch ( 5 ), that a first terminal of the inductance ( 7 , L) with a first connection of a capacity ( 10 , C _s ) and a first terminal of the output ( 12 ) and a second terminal of the inductance ( 7 , L) via a diode ( 9 ) with a second terminal of a capacity ( 10 , C _s ) and a second terminal of the output ( 12 ) of the interface arrangement ( 3 ), characterized in that the electronic switch ( 5 ) has a control input which is connected to a drive circuit ( 13 ) is connected to transmit a drive signal and that the power supply terminals of the drive circuit ( 13 ) with the outputs of the rectifier ( 11 ) are connected. Arrangement according to claim 1, characterized in that the drive circuit ( 13 ) a voltage divider ( 14 ), an electronic switch ( 16 . 21 ), a comparator ( 17 ), a maximum detector ( 15 ) and a logic gate ( 18 ) having. Arrangement according to claim 2, characterized in that the voltage divider ( 14 ) is a capacitive voltage divider. Arrangement according to claim 2, characterized in that the logic gate ( 18 ) is an RS flip-flop. A method for generating a voltage which is generated by means of a piezoelectric effect, wherein the thus generated electrical input AC voltage (V (t)) rectified by means of an interface arrangement, stored and provided as an output voltage (U _a ) for a connectable consumer, wherein at least at a zero crossing of the electrical input alternating voltage (V (t)) a connection between the input alternating voltage (V (t)) and an energy storage means consisting of an inductive and a capacitive element is separated, that this separation when reaching a maximum of the input alternating voltage (V ( t)) is canceled at a time t ₁ and a charging of the energy storage means is started, characterized in that the charging of the energy storage means at a time t ₂ 'before reaching the zero crossing of the input AC voltage (V (t)) is aborted. A method according to claim 5, characterized in that the time t ₂ 'is adjustable. A method according to claim 5 or 6, characterized in that the time t ₂ 'according to the size of a desired residual voltage V (t ₂ ') to V (t ₂ ') = qV _M with a factor q in the range between zero and one is adjustable , A method according to claim 7, characterized in that the factor q by means of a capacitive voltage division means according to q = C ₂ / (C ₁ + C ₂ ) is adjustable.

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