CN102420465B - Control device capable of inhibiting residual vibration of piezoelectric element - Google Patents

Abstract

The invention provides a control device capable of inhibiting residual vibration of a piezoelectric element. The control device includes a capacitive energy storage element and a switch unit. The control device can be operated in a non-operating mode; and in the non-operating mode, the switch unit is controlled to perform switching so as to enable the piezoelectric element to charge or discharge the capacitive energy storage element and supply the voltage of the capacitive energy storage element to the piezoelectric element for inhibiting the residual vibration of the piezoelectric element. The capacitive energy storage element is provided with a capacitive value, which is sufficient to ensure that the voltage of the capacitive energy storage element can substantially change along with the change of the amplitude of the residual vibration of the piezoelectric element in the non-operating mode, and is substantially reduced to zero when the residual vibration of the piezoelectric element is stopped.

Description

The control device that can suppress the residual oscillation of a piezoelectric element

Technical field

The present invention relates to a kind of control technology, particularly relate to a kind of control device that can suppress the residual oscillation of a piezoelectricity (piezoelectric) element.

Background technology

Radar for backing car equipment is normally realized with an aluminum hull that is adhesive with a piezoelectric element.Drive signal and import radar for backing car equipment into when one, piezoelectric element can be changed out a control because of piezoelectric effect, guides aluminum hull to produce vibration and sends a ultrasonic waves signal.Touch a barrier soon if be equiped with the vehicle of radar for backing car equipment, radar for backing car equipment can be received the echo-signal that barrier reflects because of the ultrasonic waves signal, so as to the distance between estimation vehicle and barrier, in time reminds the driver.But, after the driving signal stops, piezoelectric element and aluminum hull still have remaining mechanical oscillation (reverberation just), when radar for backing car and obstacle spacing are close to cross, this remaining mechanical oscillation signal can with the echo-signal overlaid, cause radar for backing car equipment exactly the sensing echo-signal the position and lose the estimation distance function.In order to shorten the minimum range that radar for backing car equipment can be estimated, must suppress the mechanical oscillation of piezoelectric element remnants.

Consult Fig. 1 and Fig. 2, a kind of control device that can suppress the residual oscillation of a piezoelectric element 1 comprises one drive circuit 2, a reverberation control circuit 3 and switches circuit 4.Control device can operate in a mode of operation and a non-operating mode.Under mode of operation, commutation circuit 4 is electrically connected to piezoelectric element 1 with drive circuit 2, and drive circuit 2 outputs one provide the driving signal of string waveform shape electric current to order about piezoelectric element 1 and produce vibration.Under non-operating mode, commutation circuit 4 is electrically connected to piezoelectric element 1 with reverberation control circuit 11, and reverberation control circuit 3 suppresses the residual oscillation of piezoelectric element 1.Piezoelectric element 1 is during residual oscillation, because piezoelectric effect can flow out interior electric current, electric current still keeps string waveform shape in this, and just amplitude phase shape is less.

Reverberation control circuit 3 in the past comprises a direct current power supply 31 and a switch element 32.DC power supply 31 provides a direct current reference voltage.Switch element 32 comprises four switches 321～324.Under non-operating mode, when the electric current of piezoelectric element 1 for just (just being electrically connected to switch 321 from piezoelectric element 1, one first end of a common ground of 322 is electrically connected to switch 323 toward piezoelectric element 1, one second end of a common ground of 324 flows) time, the switch element 32 controlled switches 321 that make, 323 conductings, switch 322,324 not conductings, thereby 31 pairs of piezoelectric elements 1 of DC power supply provide a voltage that is equivalent to the positive direct-current reference voltage, and when the electric current of piezoelectric element 1 is negative (just mobile toward first end of piezoelectric element 1 from second end of piezoelectric element 1), the switch element 32 controlled switches 322 that make, 324 conductings, switch 321,323 not conductings, thereby 31 pairs of piezoelectric elements 1 of DC power supply provide a voltage that is equivalent to negative DC reference voltage, thus, the electric current of piezoelectric element 1 and voltage homophase, cause the dissipation energy maximization in each cycle, so can suppress the residual oscillation of piezoelectric element 1.

Though reverberation control circuit 3 in the past can suppress the residual oscillation of piezoelectric element 1 really at the initial stage of non-operating mode, but when the Oscillation Amplitude of piezoelectric element 1 is down to when very little, the energy of DC power supply 31 but may see through the vibration convergence that switch element 32 disturbs piezoelectric element 1, even causes the vibration of piezoelectric element 1 to become big again once again.

In addition, people such as Y.P.Liu in " Velocity-Controlled Piezoelectric Switching Energy Harvesting Device " paper of delivering in April, 2009, disclosed a kind of can be from the energy capture device of piezoelectric element acquisition energy.This energy capture device utilizes an appearance to be worth the energy that sizable capacitive character energy-storage travelling wave tube comes storage retrieval to arrive.

Summary of the invention

The objective of the invention is is providing a kind of control device that can suppress the residual oscillation of a piezoelectric element, can make the residual oscillation of piezoelectric element converge to static in fact smoothly.

The control device that the present invention can suppress the residual oscillation of a piezoelectric element comprises a capacitive character energy-storage travelling wave tube and a switch element.This piezoelectric element is applied to have a system of an equivalent mass.This switch element is electrically connected to this capacitive character energy-storage travelling wave tube, and is applicable to and is electrically connected to this piezoelectric element.This control device can operate in a non-operating mode, under this non-operating mode, this switch element is controlled to be switched, so that this piezoelectric element this capacitive character energy-storage travelling wave tube is charged and discharge at least one, and the voltage of this capacitive character energy-storage travelling wave tube offered this piezoelectric element, to suppress the residual oscillation of this piezoelectric element.This capacitive character energy-storage travelling wave tube has an appearance value, this appearance value is enough to make under this non-operating mode, the voltage of this capacitive character energy-storage travelling wave tube is followed the variation of the residual oscillation amplitude of this piezoelectric element in fact, and is down to after the residual oscillation of this piezoelectric element finishes and is essentially zero.The voltage conforms following formula of this capacitive character energy-storage travelling wave tube:

$V_{\mathrm{DC}}\≤\frac{\mathrm{\π}}{4n}\frac{F_M}{\sin \left(\mathrm{\πd}\right)},$

Wherein, V _DCBe the voltage of this capacitive character energy-storage travelling wave tube, n is the power electric coupling coefficient of this system, F _MBe the amplitude of the suffered external force of this equivalence mass under resonance frequency, d is the work period of this switch element.

Beneficial effect of the present invention is: by using this capacitive character energy-storage travelling wave tube to replace a direct current power supply, when the Oscillation Amplitude of this piezoelectric element is down to when very little, the voltage of this capacitive character energy-storage travelling wave tube also and then is down to very little, therefore the energy of this capacitive character energy-storage travelling wave tube can not see through the vibration convergence that this switch element disturbs this piezoelectric element, makes the residual oscillation of this piezoelectric element can converge to static in fact smoothly.

Description of drawings

Fig. 1 is a calcspar, and a kind of control device that can suppress the residual oscillation of a piezoelectric element is described;

Fig. 2 is a circuit diagram, and the reverberation control circuit of the control device of a kind of Fig. 1 of applying in the past is described;

Fig. 3 is a circuit diagram, illustrates that the present invention can suppress the reverberation control circuit of first preferred embodiment of control device of the residual oscillation of a piezoelectric element;

Fig. 4 is an oscillogram, and the state of a switch element of the electric current of piezoelectric element and first preferred embodiment is described;

Fig. 5 is an oscillogram, and the voltage of a capacitive character energy-storage travelling wave tube of first preferred embodiment is described;

Fig. 6 is a circuit diagram, illustrates that the present invention can suppress second preferred embodiment of control device of the residual oscillation of a piezoelectric element;

Fig. 7 is an oscillogram, and a power supply unit and the state of a switch element and the electric current of piezoelectric element of second preferred embodiment is described;

Fig. 8 is an oscillogram, and the voltage of a capacitive character energy-storage travelling wave tube of second preferred embodiment is described.

Embodiment

The present invention is described in detail below in conjunction with drawings and Examples:

First preferred embodiment

Consult Fig. 1 and Fig. 3, first preferred embodiment of control device that the present invention enough suppresses the residual oscillation of a piezoelectric element 1 comprises that one drive circuit 2, a reverberation control circuit 3 and switch circuit 4.Control device can operate in a mode of operation and a non-operating mode.Under mode of operation, commutation circuit 4 is electrically connected to piezoelectric element 1 with drive circuit 2, and drive circuit 2 outputs one provide the driving signal of string waveform shape electric current to order about piezoelectric element 1 and produce vibration.Under non-operating mode, commutation circuit 4 is electrically connected to piezoelectric element 1 with reverberation control circuit 3, and reverberation control circuit 3 suppresses the residual oscillation of piezoelectric element 1.Piezoelectric element 1 is during residual oscillation, because piezoelectric effect can flow out interior electric current, electric current still keeps string waveform shape in this, and just amplitude phase shape is less.

Piezoelectric element 1 has one first end and one second end.Reverberation control circuit 3 comprises a capacitive character energy-storage travelling wave tube 33, a switch element 34, diode 35, a resistance 36, an inductance 37, a current sense device 38 and a control unit 39.Capacitive character energy-storage travelling wave tube 33 has one first end and one second end, and is an electric capacity in the present embodiment.Switch element 34 comprises and is connected into one first ring-like switch 341, a second switch 342, one the 3rd switch 343 and one the 4th switch 344 in regular turn.The first and the 4th switch 341, a common ground of 344 see through first end that diode 35 is electrically connected to capacitive character energy-storage travelling wave tube 33.Diode 35 can be set up from the first and the 4th switch 341,344 common ground to a current path of first end of capacitive character energy-storage travelling wave tube 33, just diode 35 has one and is electrically connected to the first and the 4th switch 341,344 the anode of common ground, and a negative electrode that is electrically connected to first end of capacitive character energy-storage travelling wave tube 33.The second and the 3rd switch 342, a common ground of 343 are electrically connected to second end of capacitive character energy-storage travelling wave tube 33.First and second switch 341, a common ground of 342 see through first end that inductance 37, current sense device 38 and commutation circuit 4 are electrically connected to piezoelectric element 1 in regular turn.The the 3rd and the 4th switch 343, a common ground of 344 see through second end that commutation circuit 4 is electrically connected to piezoelectric element 1.Resistance 36 is in parallel with capacitive character energy-storage travelling wave tube 33.Control unit 39 is electrically connected to switch element 34 and current sensor 38.

Consult Fig. 3 and Fig. 4, in Fig. 4, the electric current of waveform 81 explanation piezoelectric elements 1 (see figure 1), waveform 82 explanation the first and the 3rd switch 341,343 state, waveform 83 explanation the second and the 4th switch 342,344 state, in waveform 82,83, high levle is represented conducting, and low level is represented not conducting.Under non-operating mode, the electric current of current sensor 38 detecting piezoelectric elements 1, control unit 39 control switch unit 34, be just when (just second end from first end of piezoelectric element 1 toward piezoelectric element 1 flows) at the electric current of piezoelectric element 1, make the first and the 3rd switch 341,343 conductings, the second and the 4th switch 342,344 not conductings, and when the electric current of piezoelectric element 1 is negative (just mobile toward first end of piezoelectric element 1 from second end of piezoelectric element 1), make the second and the 4th switch 342,344 conductings, the first and the 3rd switch 341,343 not conductings, therefore, switch element 34 controlled switchings (first and second switch 341 just, 342 alternate conduction, the the 3rd and the 4th switch 343,344 alternate conduction, and the first and the 3rd switch 341,343 conductings simultaneously), so that 1 pair of capacitive character energy-storage travelling wave tube 33 of piezoelectric element charges, and be timing at the voltage of piezoelectric element 1, provide a voltage that is equivalent to positive capacitive character energy-storage travelling wave tube 33 voltages to piezoelectric element 1, and at the voltage of piezoelectric element 1 when negative, provide the voltage of capacitive character energy-storage travelling wave tube 33 voltages that are equivalent to bear to piezoelectric element 1, to suppress the residual oscillation of piezoelectric element 1.

Preferably, under non-operating mode, control unit 39 control switch unit 34, make first and second switch 341, conduction period of 342 be separated by an of short duration preset time T (for easy understanding, amplified T among Fig. 4), the 3rd and the 4th switch 343, conduction period of 344 preset time T of being separated by, preset time T enough allows inductance 37 that piezoelectric element 1 is charged to a predeterminated voltage, thus, can reduce the switch cost that causes because of switch element 34 switchings.

Consult Fig. 3 and Fig. 5, the voltage of waveform 84 explanation capacitive character energy-storage travelling wave tubes 33.It should be noted that, disclosed in " Velocity-Controlled Piezoelectric Switching Energy Harvesting Device " paper that people such as reverberation control circuit 3 and Y.P.Liu delivered in April, 2009 can be similar from the energy capture device of piezoelectric element acquisition energy, different places is that the appearance value of capacitive character energy-storage travelling wave tube 33 of reverberation control circuit 3 is enough little, make under non-operating mode, by the charging of 1 pair of capacitive character energy-storage travelling wave tube 33 of piezoelectric element and the discharge of 36 pairs of capacitive character energy-storage travelling wave tubes 33 of resistance, the voltage of capacitive character energy-storage travelling wave tube 33 is followed the variation of the residual oscillation amplitude of piezoelectric element 1 in fact (just when the residual oscillation amplitude of piezoelectric element 1 is big, 33 energy that can capture of capacitive character energy-storage travelling wave tube are bigger, make its voltage also and then bigger, and in the residual oscillation amplitude of piezoelectric element 1 hour, 33 energy that can capture of capacitive character energy-storage travelling wave tube are less, its voltage is also and then less), and after the residual oscillation of piezoelectric element 1 finishes, be down to and be essentially zero.The disclosed energy capture device of people such as Y.P.Liu does not then possess such characteristic because having utilized appearance to be worth sizable capacitive character energy-storage travelling wave tube.

Consult Fig. 1 and Fig. 3, piezoelectric element 1 is applied to have system's (not shown) of an equivalent mass (not shown), and the single mode of piezoelectric element 1 controls equation (single-mode governing equation) as follows:

$M\stackrel{\·\·}{u}+D\stackrel{\·}{u}+\mathrm{Ku}=f-{\mathrm{nv}}_p,$ Formula (1)

Wherein, u is the displacement (displacement) of equivalent mass piece, M is the quality (mass) of equivalent mass piece, D is the equivalent mechanical damping (mechanical damping) of system, K is the equivalent toughness (stiffness) of system, f is the suffered external force of equivalent mass piece, and n is the power electric coupling coefficient (electro-mechanical ratio) of system, v _pBe the voltage of piezoelectric element 1.

(v just under short-circuit condition _p=0), shown in dynamically being expressed as follows in frequency domain of piezoelectric element 1:

$\frac{u}{f}{|}_{\mathrm{short}}=\frac{1}{K-M{\mathrm{\ω}}^2+\mathrm{jD\ω}},$ Formula (2)

${\mathrm{\ω}}_r=\sqrt{\frac{K}{M}},$ Formula (3)

$U_M^{\mathrm{short}}=\frac{F_M}{\mathrm{D\ω}},$ Formula (4)

Wherein, ω is angular frequency, ω _rBe resonant angular frequency,

Be amplitude, the F of displacement under resonance frequency of piezoelectric element 1 _MBe the suffered amplitude of external force under resonance frequency of piezoelectric element 1.

Under non-operating mode, the voltage of piezoelectric element 1 is determined by capacitive character energy-storage travelling wave tube 33 and switch element 34.According to Fu Li Yeli opinion, the single order harmonic voltage of piezoelectric element 1 is as follows:

$v_p=\frac{4}{\mathrm{\π}}{V}_{\mathrm{DC}}\sin \left(\mathrm{\πd}\right)\mathrm{signe}\left(\stackrel{\·}{x}\right),$ Formula (5)

Wherein, V _DCBe the voltage of capacitive character energy-storage travelling wave tube 33, d is the work period (duty cycle) of the switch 341～344 of switch element 34,

It is the signal function of the electric current variation of reaction pressure electric device 1.

With formula (5) substitution formula (1), shown in dynamically being expressed as follows in frequency domain of piezoelectric element 1:

$(K-M{\mathrm{\&omega;}}^2)u+\mathrm{jD\&omega;u}=f-\mathrm{<figure-callout\; id="4"\; label="jn"\; filenames="HSA00000288617600011.png"\; state="\{\{state\}\}">jn</figure-callout>}\frac{4}{\mathrm{\&pi;}}{V}_{\mathrm{DC}}\sin \left(\mathrm{\&pi;d}\right),$ Formula (6)

$U_M=\frac{F_M-\mathrm{<figure-callout\; id="4"\; label="n"\; filenames="HSA00000288617600011.png"\; state="\{\{state\}\}">n</figure-callout>}\frac{4}{\mathrm{\&pi;}}{V}_{\mathrm{DC}}\sin \left(\mathrm{\&pi;d}\right)}{\mathrm{D\&omega;}},$ Formula (7)

Wherein, U _MBe the amplitude of displacement under resonance frequency of piezoelectric element 1.

Comparison expression (7) and formula (4), the theory decay of the displacement of piezoelectric element 1 is as follows:

$A=20{\log }_{10}(1-\mathrm{<figure-callout\; id="4"\; label="n"\; filenames="HSA00000288617600011.png"\; state="\{\{state\}\}">n</figure-callout>}\frac{4}{\mathrm{\&pi;}}\frac{V_{\mathrm{DC}}}{F_M}\sin \left(\mathrm{\&pi;d}\right)).$ Formula (8)

According to formula (8), when following formula was set up, the residual oscillation of piezoelectric element 1 can be suppressed, otherwise the residual oscillation of piezoelectric element 1 can be encouraged:

$V_{\mathrm{DC}}=\frac{\mathrm{\&pi;}}{4n}\frac{F_M}{\sin \left(\mathrm{\&pi;d}\right)}.$ Formula (9)

Because the voltage of capacitive character energy-storage travelling wave tube 33 is followed the variation of the residual oscillation amplitude of piezoelectric element 1 in fact, therefore preferably the maximum of the voltage of capacitive character energy-storage travelling wave tube 33 can meet formula (9), and more near upper limit inhibition better, and the appearance value of capacitive character energy-storage travelling wave tube 33 can calculate according to following formula:

$V_{\mathrm{DC}}=\frac{1}{C}\&Integral;I\left(t\right)\mathrm{dt},$ Formula (10)

Wherein, C is the appearance value of capacitive character energy-storage travelling wave tube 33, and I (t) is the electric current of capacitive character energy-storage travelling wave tube 33.

Preferably, the appearance value of capacitive character energy-storage travelling wave tube 33 be no more than piezoelectric element 1 equivalent electric circuit direct capacitance the appearance value 1/10.Preferably, the appearance value of capacitive character energy-storage travelling wave tube 33 drops in the scope of 1pF～10 μ F.

For instance, be applied to suppress at present embodiment under the situation of residual oscillation of piezoelectric element of cantilever beam (cantilever beam) system, the appearance value of capacitive character energy-storage travelling wave tube 33 is about μ F grade, and not as limit, decides with the parameter of cantilever beam system and the size of piezoelectric element.

Consult Fig. 2 and Fig. 3, compare with reverberation control circuit 3 in the past, the reverberation control circuit 3 of present embodiment is by using the little capacitive character energy-storage travelling wave tube 33 of appearance value to replace DC power supply 31, when the Oscillation Amplitude of piezoelectric element 1 is down to when very little, the voltage of capacitive character energy-storage travelling wave tube 33 also and then is down to very little, therefore the energy of capacitive character energy-storage travelling wave tube 33 can not see through the vibration convergence that switch element 34 disturbs piezoelectric element 1, it is static in fact to make that the residual oscillation of piezoelectric element 1 can converge to smoothly, can reach purpose of the present invention really.

Second preferred embodiment

Consult Fig. 6, second preferred embodiment of control device that the present invention enough suppresses the residual oscillation of a piezoelectric element 5 comprises a capacitive character energy-storage travelling wave tube 61, a switch element 62, a power supply unit 63, a transformer 64 and a control unit 65.

Piezoelectric element 5 has one first end and one second end.Capacitive character energy-storage travelling wave tube 61 has one first end and one second end, and is an electric capacity in the present embodiment.Switch element 62 comprises and is connected into one first ring-like switch 621, a second switch 622, one the 3rd switch 623 and one the 4th switch 624 in regular turn.The first and the 4th switch 621, a common ground of 624 are electrically connected to first end of capacitive character energy-storage travelling wave tube 61.The second and the 3rd switch 622, a common ground of 623 are electrically connected to second end of capacitive character energy-storage travelling wave tube 61.First and second switch 621, a common ground of 622 and the 3rd and the 4th switch 623, a common ground of 624 see through first end and second end that transformer 64 is electrically connected to piezoelectric element 5 respectively.Power supply unit 63 comprises an inductance 631, diode 632 and a switch 633.Inductance 631 has first end that is electrically connected to first end of capacitive character energy-storage travelling wave tube 61, and one second end.Diode 632 has an anode that is electrically connected to the negative terminal of second end of capacitive character energy-storage travelling wave tube 61 and an external dc power 7, and a negative electrode that is electrically connected to second end of inductance 631.Switch 633 is connected electrically between the anode of second end of inductance 631 and external dc power 7.Control unit 65 is electrically connected to switch element 62 and power supply unit 63.

Consult Fig. 6 and Fig. 7, in Fig. 6, the state of waveform 91 explanation switches 633, waveform 92 explanation the first and the 3rd switch 621,623 state, waveform 93 explanation the second and the 4th switch 622,624 state, waveform 94 illustrates the electric current of piezoelectric elements 5, in waveform 91～93, high levle is represented conducting, and low level is represented not conducting.Control device can operate in a mode of operation and a non-operating mode.Under mode of operation, control unit 65 control switch unit 62 and power supply unit 63, make switch 633 conductings, first and second switch 621,622 alternate conduction, the the 3rd and the 4th switch 623,624 alternate conduction, and the first and the 3rd switch 621,623 conductings simultaneously, at this moment, power supply unit 63 provides a direct current voltage to capacitive character energy-storage travelling wave tube (just to 61 chargings of capacitive character energy-storage travelling wave tube) from first end of this inductance 631, the driving signal that switch element 62 outputs one amplitude equates with the voltage of this capacitive character energy-storage travelling wave tube 61, this drives signal and be used for ordering about piezoelectric element 5 generation vibrations after transformer 64 amplifies, at the first and the 3rd switch 621, during 623 conductings, the electric current of piezoelectric element 5 is negative (just mobile toward first end of piezoelectric element 5 from second end of piezoelectric element 5), and at the second and the 4th switch 622, during 624 conductings, the electric current of piezoelectric element 5 is just (just second end from first end of piezoelectric element 5 toward piezoelectric element 5 flows).

Under non-operating mode, control unit 65 control switch unit 62 and power supply unit 63, make switch 633 not conductings, first and second switch 621,622 alternate conduction, the the 3rd and the 4th switch 623,624 alternate conduction, the first and the 3rd switch 621,623 conductings simultaneously, and first and second switch 621 under non-operating mode, the phase place of 622 alternate conduction and first and second switch 621 under mode of operation, the phase place of 622 alternate conduction differs 180 degree in fact, cause power supply unit 63 to stop to provide direct voltage to capacitive character energy-storage travelling wave tube 61 (just stopping 61 chargings of capacitive character energy-storage travelling wave tube) from first end of this inductance 631, switch element 62 is at the first and the 3rd switch 621, during 623 conductings, provide a voltage that the is equivalent to positive capacitive character energy-storage travelling wave tube 61 voltages electric current of piezoelectric element 5 (this moment for just) to transformer 64, and at the second and the 4th switch 622, during 624 conductings, transformer 64 is provided the voltage (this moment, the electric current of piezoelectric element 5 was negative) of capacitive character energy-storage travelling wave tube 61 voltages that are equivalent to bear, after amplifying the voltage that receives, transformer 64 offers piezoelectric element 5, to suppress the residual oscillation of piezoelectric element 5.

In the present embodiment, transformer 64 can be omitted, in this case, first and second switch 621 of switch element 62,622 common ground and the 3rd and the 4th switch 623,624 common ground are applicable to first end and second end that is electrically connected to piezoelectric element 5 respectively.

Consult Fig. 6 and Fig. 8, the voltage of waveform 85 explanation capacitive character energy-storage travelling wave tubes 61.It should be noted that, capacitive character energy-storage travelling wave tube 61 has an appearance value, this appearance value is enough to make under mode of operation, capacitive character energy-storage travelling wave tube 61 is powered unit 63 precharge, and under non-operating mode, discharge by 1 pair of capacitive character energy-storage travelling wave tube 61 of piezoelectric element, the voltage of capacitive character energy-storage travelling wave tube 61 is followed the residual oscillation oscillation amplitude change of piezoelectric element 5 in fact, and after the residual oscillation of piezoelectric element 5 finishes, be down to and be essentially zero, thus, can avoid the vibration convergence of piezoelectric element 5 to be interfered, make the residual oscillation of piezoelectric element 5 can converge to static in fact smoothly.

Because the voltage of capacitive character energy-storage travelling wave tube 61 is followed the variation of the residual oscillation amplitude of piezoelectric element 5 in fact, therefore preferably the maximum of the voltage of capacitive character energy-storage travelling wave tube 61 can meet formula (9), and more near upper limit inhibition better, and the appearance value of capacitive character energy-storage travelling wave tube 61 can calculate according to formula (10).Preferably, the appearance value of capacitive character energy-storage travelling wave tube 61 be no more than piezoelectric element 5 equivalent electric circuit direct capacitance the appearance value 1/10.Preferably, the appearance value of capacitive character energy-storage travelling wave tube 61 drops in the scope of 1pF～10 μ F.

Claims (11)

1. control device that can suppress the residual oscillation of a piezoelectric element, described piezoelectric element is applied to have a system of an equivalent mass piece, and described control device is characterised in that it comprises:

A capacitive character energy-storage travelling wave tube; And

A switch element is electrically connected to described capacitive character energy-storage travelling wave tube, and is applicable to and is electrically connected to described piezoelectric element;

Described control device can operate in a non-operating mode, under described non-operating mode, described switch element is controlled to be switched, so that described piezoelectric element described capacitive character energy-storage travelling wave tube is charged and discharge at least one, and the voltage of described capacitive character energy-storage travelling wave tube offered described piezoelectric element, to suppress the residual oscillation of described piezoelectric element;

Described capacitive character energy-storage travelling wave tube has an appearance value, described appearance value is enough to make under described non-operating mode, the voltage of described capacitive character energy-storage travelling wave tube is followed the variation of the residual oscillation amplitude of described piezoelectric element in fact, and is down to after the residual oscillation of described piezoelectric element finishes and is essentially zero;

The voltage conforms following formula of described capacitive character energy-storage travelling wave tube:

$V_{\mathrm{DC}}\&le;\frac{\mathrm{\&pi;}}{4n}\frac{F_M}{\sin \left(\mathrm{\&pi;d}\right)},$

Wherein, V _DCBe the voltage of described capacitive character energy-storage travelling wave tube, n is the power electric coupling coefficient of described system, F _MBe the suffered amplitude of external force under resonance frequency of described equivalent mass piece, d is the work period of described switch element.

2. control device according to claim 1, described piezoelectric element has first end and second end, and described control device is characterised in that:

Described capacitive character energy-storage travelling wave tube has first end and second end;

Described switch element comprises and is connected into the first, second, third and the 4th ring-like switch in regular turn, described first and common ground of the 4th switch room and described second and a common ground of the 3rd switch room be electrically connected to first and second end of described capacitive character energy-storage travelling wave tube respectively, common ground of described first and second switch room and the described the 3rd and a common ground of the 4th switch room be applicable to first end and second end that is electrically connected to described piezoelectric element respectively;

Under described non-operating mode, described switch element is controlled, makes described first and second switch alternate conduction, the described the 3rd and the 4th switch alternate conduction, and the conducting simultaneously of the described first and the 3rd switch.

3. control device according to claim 2 is characterized in that it also comprises:

A diode, be connected electrically between the common ground and described capacitive character energy-storage travelling wave tube of the first and the 4th switch room of described switch element, and can set up a current path from the common ground of the first and the 4th switch room of described switch element to described capacitive character energy-storage travelling wave tube; And

A resistance, in parallel with described capacitive character energy-storage travelling wave tube.

4. control device according to claim 3 is characterized in that it also comprises:

An inductance is connected electrically between the common ground and described piezoelectric element of first and second switch room of described switch element.

5. control device according to claim 4 is characterized in that it also comprises:

A current sensor is connected electrically between described inductance and described piezoelectric element; And

A control unit is electrically connected to described switch element and described current sensor;

Under described non-operating mode, described current sensor is detected the electric current of described piezoelectric element, described control unit is when the electric current of described piezoelectric element is mobile toward second end of described piezoelectric element from first end of described piezoelectric element, make the first and the 3rd switch conduction, the second and the 4th not conducting of switch of described switch element, and when the electric current of described piezoelectric element is mobile toward first end of described piezoelectric element from second end of described piezoelectric element, make the second and the 4th switch conduction, the first and the 3rd not conducting of switch of described switch element.

6. control device according to claim 5, it is characterized in that: under described non-operating mode, described control unit make the conduction period of described first and second switch be separated by one section Preset Time, the described the 3rd and conduction period of the 4th switch the described Preset Time of being separated by, described Preset Time enough allows described inductance that described piezoelectric element is charged to a predeterminated voltage.

7. control device according to claim 2 is characterized in that it also comprises:

A power supply unit is electrically connected to described capacitive character energy-storage travelling wave tube;

Described control device also can operate in a mode of operation, under described mode of operation, described power supply unit is controlled to provide a direct voltage to described capacitive character energy-storage travelling wave tube, described switch element is controlled, make described first and second switch alternate conduction, the the described the 3rd and the 4th switch alternate conduction, and the conducting simultaneously of the described first and the 3rd switch are ordered about described piezoelectric element generation vibration thereby one of described switch element output drives signal;

Under described non-operating mode, described power supply unit is controlled to stop to provide described direct voltage to described capacitive character energy-storage travelling wave tube, described switch element is controlled, makes to differ 180 degree in fact in the phase place of described first and second switch alternate conduction under the described non-operating mode and the phase place of described first and second switch alternate conduction under described mode of operation.

8. control device according to claim 7 is characterized in that described power supply unit comprises:

An inductance has first end that is electrically connected to first end of described capacitive character energy-storage travelling wave tube, and second end;

A diode has an anode that is electrically connected to second end of described capacitive character energy-storage travelling wave tube, and a negative electrode that is electrically connected to second end of described inductance, and described anode also is applicable to the negative terminal that is electrically connected to an external dc power; And

One switch is connected electrically between the anode of second end of described inductance and described external dc power;

Under described mode of operation, described power supply unit is controlled to make described switch conduction, thereby provides described direct voltage to described capacitive character energy-storage travelling wave tube from first end of described inductance;

Under described non-operating mode, described power supply unit is controlled to make the not conducting of described switch, thereby stops to provide described direct voltage to described capacitive character energy-storage travelling wave tube from first end of described inductance.

9. control device according to claim 8 is characterized in that it also comprises:

A transformer is connected electrically between described switch element and described piezoelectric element, be used for to amplify signal that described switch element exports to offer described piezoelectric element.

10. control device according to claim 1 is characterized in that: the appearance value of described capacitive character energy-storage travelling wave tube be no more than described piezoelectric element equivalent electric circuit direct capacitance the appearance value 1/10.

11. control device according to claim 1 is characterized in that: the appearance value of described capacitive character energy-storage travelling wave tube drops in the scope of 1pF～10 μ F.

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