JP4286166B2 - Railway vehicle - Google Patents

Description

  The present invention relates to a railway vehicle in which vibration energy of a vehicle body is dissipated to reduce vibration.

  In recent years, the weight of railway vehicles has been reduced, and accordingly, the rigidity of the vehicle body tends to decrease. When the rigidity of the vehicle body decreases, the occurrence of elastic vibration (vertical bending vibration) of the vehicle body becomes significant. Such elastic vibration often occurs in a frequency band that is most sensitive to humans, and causes a deterioration in riding comfort. On the other hand, at present, it has been proposed to reduce the elastic vibration of the vehicle body by attaching a damping material consisting of a viscoelastic layer and a constraining layer to the vehicle body, or by performing active or semi-active control, Research is ongoing. In addition, the example which adds a damping material to a vehicle body and aims at reduction of elastic vibration has already been put into practical use on the Shinkansen (see Non-Patent Document 1).

On the other hand, recently, research for reducing elastic vibration of a vehicle body by using a passive vibration suppression technique has been attracting attention. One type of passive vibration damping is a vibration damping method in which vibration energy of a piezo element is converted into electric energy, and this electric energy (electric power) is dissipated in an external circuit to obtain mechanical damping.
Yasufumi Suzuki, et al., “Dampening Method of Bending Vibration of Railway Vehicles”, Proceedings of the 74th General Meeting of the Japan Society of Mechanical Engineers (I), Vol. 97, No. 1, p. 691-692

  Therefore, in view of the above points, an object of the present invention is to increase the vibration reduction effect without increasing the size of the apparatus when the vibration of a vehicle body for a railway vehicle is reduced using a piezoelectric element. Another object of the present invention is to broaden the selection range of circuit characteristics, further enhance the effect of vibration reduction, and to realize vibration suppression for a plurality of vibration modes.

In order to solve the above-described problem, a railway vehicle according to one aspect of the present invention is attached to a vehicle body structure for a railway vehicle, and generates at least one piezo that generates a voltage by being elastically deformed by the vibration of the vehicle body. An output voltage is generated based on the element and a voltage generated at the first terminal of the piezo element, and the output voltage is supplied to the second terminal of the piezo element, thereby at least a part of the electric energy generated by the piezo element. An energy conversion circuit for converting the energy into thermal energy, the energy conversion circuit comprising : (i) a first passive element connected to the first terminal of the piezo element; and (ii) an insulation amplifier circuit. Based on the voltage generated across the first passive element or the second passive element connected in series to the first passive element, the capacitive component of the piezo element at at least one frequency is obtained. An active circuit that equivalently generates an impedance component for cancellation, and the first passive element, or the first and second passive elements connected in series, are isolated from the first terminal of the piezo element. It is connected between the inverting input terminal of the circuit .

According to one aspect of the present invention, an apparatus is increased in size by using an energy conversion circuit that includes an active circuit having an insulation amplifier circuit and converts at least a part of the electric energy generated by the piezoelectric element into thermal energy. The effect of reducing the vibration can be enhanced without any problem, and the deterioration of the riding comfort of the vehicle can be improved. In the present invention, an active circuit including a power supply is used. However, unlike the conventional case where active vibration suppression control is performed, there is an advantage that a vibration sensor for use in control is unnecessary.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.
First, the basic configuration of the present invention will be described with reference to FIG.
FIG. 1 is a conceptual diagram showing a basic configuration of the present invention. A plurality of piezo elements 2 are attached to the railway vehicle structure 1. In FIG. 1, only one piezo element 2 is shown for simplicity of explanation. The piezoelectric element 2 is manufactured by forming electrodes 4 and 5 on both sides of the piezoelectric material 3 in the thickness direction. As the structure 1 vibrates, the piezoelectric element 2 is elastically deformed, and the piezoelectric element 2 generates a voltage by the elastic deformation. Further, an energy conversion circuit 6 including an active circuit is connected to the piezo element 2. The energy conversion circuit 6 efficiently absorbs the electric energy generated by the piezo element 2 and converts it into thermal energy. In this way, the mechanical energy in the vibration of the structure 1 is finally converted into thermal energy, and the vibration of the structure 1 is braked.

Next, a model applied to the vibration test for confirming the vibration damping performance will be described with reference to FIG.
FIG. 2 is a diagram showing a vehicle model of a railway vehicle used in the vibration test. As shown in FIG. 2, the vehicle body model 10 of this railway vehicle is manufactured at a scale that is 1/5 of the actual Shinkansen vehicle body, and has a total length L _B = 4.9 m, a width W _B = 0.672 m, and a height H _B. = 0.6 m. The mass m _B of the vehicle body model 10 is 290 kg. The vehicle body model 10 is supported by air springs 11 at four positions corresponding to the support positions of the vehicle body. The position supported by the air spring 11 is 0.7 m from both ends of the vehicle body. Here, let the longitudinal direction of the vehicle body model 10 be the x axis, the width direction be the y axis, and the height direction be the z axis. In the left diagram of FIG. 2, the left end of the vehicle body is the x-axis origin, and the right direction is the x-axis positive direction.

  A load cell 12 for measuring the excitation force is attached between the electrodynamic exciter 13 disposed on the base and the lower end of the vehicle body model 10. On the other hand, an acceleration pickup (acceleration sensor) is attached to the floor, side, and roof of the vehicle body model 10 (not shown). The excitation force of the vehicle body model 10 by the electrodynamic exciter 13 is measured by the load cell 12, and the vibration acceleration of the vehicle body model 10 at that time is measured by an acceleration sensor. Thereby, the vibration response of the vehicle body model 10 is measured.

The vehicle body model 10 is regarded as an Euler beam supported by the air spring 11, and the displacement of the beam is separated into variables and expressed as the following equation (1).
w (x, t) = φ Z (x) q Z (t) + φ P (x) q P (t) + φ 1 (x) q 1 (t)
... (1)
Here, φ (x) is an eigenmode shape function, and q (t) is a mode displacement. Subscripts Z, P, and 1 indicate translational vibration, pitching vibration, and primary bending vibration as a rigid body, respectively. Specifically, φ _Z (x) = 1, φ _P (x) = 2x / L _B −1, and φ ₁ (x) is a shape function of a free beam at both ends. Note that secondary and higher bending vibrations are ignored.

Thus, equation (1), and, by using the matrix _{q = [q Z q P q} 1] T, the vertical exciting force applied by the electro-dynamic exciter 13 f, the piezoelectric element generates moment the equation of motion when the M _P is expressed by the following equation (2).

Here, the symbol “·” represents time differentiation, and the matrix M, the matrix C, the matrix K, the matrix b ₁ , and the matrix b ₂ are expressed by the following equations (3) to (7). Is done.

Here, the symbol “′” represents partial differential with x, J represents the moment of inertia of the beam, x _M represents the position of the air spring, and L _M represents the air spring. represents a half of the distance between, K _M represents the spring constant of 2 per air spring, C _M denotes the damper coefficients of two per air spring. X ₁ and x ₂ represent the positions of both ends of the piezo element, x _F represents the position of excitation, and ω ₁ represents the natural angular frequency of the primary bending vibration. , Ζ ₁ represents the damping ratio of the primary bending vibration. Note that the mass of the piezo element is ignored as it is smaller than that of the vehicle body model 10.

Next, the piezoelectric element used in this embodiment will be described.
A piezoelectric element as an actuator, when energized v _A, generates a moment M _P shown in the following equation (8). Equation (8) is called an actuator equation.
M _P = K _A (u (x−x ₁ ) −u (x−x ₂ )) v _A (8)

Here, K _A is a coefficient determined by the performance and shape of the piezoelectric element, u (x) is a step function. Note that _MP is a moment component generated by converting the voltage v _A and does not include a mechanical rigidity component. The effect of the stiffness added by the piezoelectric element can be taken into account by adding the M _P equivalent to the right side as a moment component.

On the other hand, when distortion is generated in the piezo element as a sensor, the piezo element generates a voltage v _S represented by the following equation (9). Equation (9) is called a sensor equation.

Here, K _S is a coefficient determined by the performance and shape of the piezoelectric element, C _P ^S is the capacitance of the piezoelectric element was measured under constant strain conditions. Further, w ′ (x) is a partial differentiation of the displacement w (x) of the beam at the position x by x, and w ′ (x ₁ ) and w ′ (x ₂ ) are w at both ends of the piezo element. 'Is the value of (x). In Expression (9) and below, t indicating time is omitted. In the present embodiment, the vehicle body model 10 is damped by converting vibration into electric power in the piezo element and dissipating the converted electric power in the resistor.

Next, in order to grasp the vibration characteristics of the railway vehicle, a preliminary vibration test performed without a piezo element will be described.
In this preliminary excitation test, a band random signal having a uniform frequency component in the range of 5 to 100 Hz is input to the electrodynamic exciter 13 so that the end of the vehicle body model 10 is connected to the end of the vehicle body model 10 via the load cell 12. The vibration acceleration of the vehicle body model 10 is measured by exciting vertically from below. Here, the measurement of vibration acceleration was performed by sampling the output signal of the acceleration sensor at a sampling frequency of 200 Hz via a low-pass filter with a cutoff frequency of 80 Hz.

FIG. 3 shows the FRF (frequency response function) gain of the acceleration on the floor at a position 0.9 m from the end of the vehicle body model. In FIG. 3, the FRF when the excitation force (unit N) is input and the vibration acceleration (unit m / s ² ) at the position of x = 0.9 m on the floor of the vehicle body model 10 shown in FIG. 2 is output. For the gain, a calculated value based on modeling and an actual measurement value are shown.

  FIG. 4 shows the measured natural frequency and vibration mode shape of the railway vehicle model. Here, the main natural vibration modes are shown. In FIG. 4, the thin line indicates a shape in which the position of each acceleration sensor (measurement point) in the body model 10 before deformation is connected by a line, and the thick line indicates each acceleration sensor (measurement point) in the body model 10 after deformation. ) Shows a vibration mode shape in which the positions are connected by a line. The numerical values shown in the figure are the natural frequencies in each vibration mode.

  Here, FIG. 4A shows the translational vibration mode when the vehicle body model 10 is a rigid body, and FIG. 4B shows the pitching vibration mode. FIG. 4C shows a vibration mode considered as a primary bending vibration, and FIG. 4D shows a vibration mode that cannot be expressed by beam bending. Furthermore, many local vibration modes were observed in this preliminary excitation test.

  When the vibration suppression target is limited to the primary bending vibration shown in FIG. 4C by these preliminary excitation tests, judging from the FRF gain shown in FIG. 3 and the vibration shape shown in FIG. It was found that applying the beam model is reasonable.

  By the way, the voltage generated in the piezo element due to strain greatly affects the vibration damping performance. Therefore, strain measurement was performed when primary bending vibration occurred. In this strain measurement, the central portion of the body model 10 in the x-axis direction, which is the longitudinal direction, is used as a measurement cross section, and nine strain measurement points are provided in the z-axis direction, which is the height direction. The measured value of the change in the amount of strain in the direction is compared with the calculated theoretical value.

ここで、ｄ_Ｚは、中立軸からの距離であり、ｘ_Ｃは、車体模型１０の中央部のｘ座標であり、ｗ_Ｌは、式（１）における第３項のφ_Ｌ（ｘ）ｑ_Ｌ（ｔ）である。即ち、ｗ_Ｌは、はりのたわみに相当する。 On the other hand, when only the primary bending vibration in the vehicle body model 10 is generated, the theoretical value S _ID of the strain in the cross section of the central portion is expressed by the following equation (10). However, it is assumed that the bending deformation of the vehicle body model 10 follows Euler's beam theory in which shear deformation can be ignored.

Here, d _Z is the distance from the neutral axis, x _C is the x coordinate of the central part of the vehicle body model 10, and w _L is φ _L (x) q of the third term in the equation (1). _L (t). That is, w _L corresponds to the deflection of the beam.

Moreover, as shown in the theoretical formula of the middle side in the equation (10), in order to calculate the strain, a curvature which is a second-order partial differentiation with respect to the deflection x is required, but this cannot be directly measured. Therefore, first, the primary bending component is extracted from the acceleration at the central portion, then, the deflection w _L (x) is obtained from the second-order integration by the time of the primary bending component, and further, the primary of the free support beam at both ends is obtained. Using the ratio of the values at x = x _C between the eigen-shape function φ _L (x) of the mode and the second-order partial differential φ _L ″ (x) by x, an approximate expression of the right side in equation (10) The strain is calculated by

  Here, the measured value of the strain and the theoretical value calculated using the equation (10) are both 0.3 m in height where the neutral axis that does not cause strain is the center in the height direction of the vehicle body model 10. It was confirmed that it was in position.

On the other hand, the measured strain value at a place other than the neutral axis was generally smaller than the theoretical value calculated using Equation (10). That is, it was found that considering the vehicle body model 10 as an Euler beam is appropriate for the vibration shape of the primary bending, but is inappropriate for the strain. This is considered to be due to the effect of shear deformation between the roof and the floor of the vehicle body model 10, and in order to accurately express such deformation, Timoshenko beam or FEM (finite element model: finite) It is considered desirable to use a model such as an element model. However, by multiplying K _A in Equation (8) and K _S in Equation (9) by the correction coefficient obtained from the ratio of the measured value of the strain to the theoretical value, a model using the Euler beam is obtained. By correcting, it is possible to confirm the vibration suppression performance by the piezo element by performing a simulation.

Next, the arrangement of the piezoelectric elements in the vibration test for confirming the vibration damping performance of the railway vehicle according to the present embodiment will be described.
FIG. 5 shows a model of a railway vehicle model according to an embodiment of the present invention. As shown in FIG. 5, eight piezo elements 2 are divided into four pieces and arranged in tiles at the lower part of the left and right side beams attached over the entire length of the body model 10 in the longitudinal direction. It is attached by adhesion via an aluminum C-type stiffener. Each piezo element 2 has a length L _P = 155 mm, a width W _P = 40 mm, and a thickness t _P = 3 mm, and the mass ratio of the piezo element to the vehicle body is about 0.4%. The electrodes of the piezo element 2 are all connected in parallel. Other configurations are the same as those shown in FIG.

  Lead wires attached to the electrodes of the piezo element 2 are connected to the energy conversion circuit 6. This energy conversion circuit 6 includes an active circuit using an active element, and equivalently, a circuit in which a pure resistance R and an inductance L are connected in series (hereinafter also referred to as “LR circuit”), It can be expressed as a circuit in which a negative capacitance and a pure resistance R are connected in series (hereinafter also referred to as a “negative CR circuit”).

Next, an excitation test for confirming the damping performance performed using the model of the railway vehicle shown in FIG. 5 will be described.
In the vibration test described here, the right end portion of the vehicle body model 10 is vibrated by being vibrated vertically by the electrodynamic exciter 13, and the electric energy generated by elastic deformation of the piezoelectric element 2 is generated by the energy conversion circuit 6. Vibration control is performed by converting to thermal energy, and vibration acceleration of the vehicle body model 10 at that time is measured by an acceleration sensor. Thereby, the vibration response of the vehicle body model 10 is measured.

  FIG. 6 shows an equivalent circuit when an equivalent LR circuit is used as the first energy conversion circuit. In this case, as shown in FIG. 6, the LR circuit is equivalently connected to the piezo element. Here, an equivalent circuit of the piezo element is represented by a series connection of a capacitance and an AC voltage source. In order to cancel the capacitance component of the piezo element at a specific frequency and make the load of the AC voltage source a pure resistance, the first energy conversion circuit equivalently constitutes an LR circuit.

ここで、Ｌ＝１／（ω_１ ^２Ｃ_Ｐ）を満たすように調整することにより、インダクタンスＬとピエゾ素子のキャパシタンスＣ_Ｐとにより共振回路が構成される。これにより、ピエゾ素子が発生する電力を効率的に抵抗Ｒによって散逸させ、高い制振性能を得ることができる。なお、第１のエネルギー変換回路におけるインダクタンスＬと抵抗Ｒの調整は、力学系の動吸収器におけるマスとダンパの調整にそれぞれ相当する。 In the equivalent circuit shown in FIG. 6, the transfer function G _L−R (s) when the voltage generated by the AC voltage source is the input voltage and the voltage applied to the LR circuit is the output voltage is 11). In addition, the description which attached | subjected (s) to the capital letter of the alphabet represents Laplace conversion.

Here, by adjusting to satisfy ^{_{L = 1 / (ω 1 2}} C P), the resonant circuit is formed by a capacitance _{C P} of inductance L and a piezoelectric element. Thereby, the electric power which a piezo element generate | occur | produces can be dissipated efficiently by resistance R, and high damping performance can be obtained. The adjustment of the inductance L and the resistance R in the first energy conversion circuit corresponds to the adjustment of the mass and the damper in the dynamic system dynamic absorber, respectively.

The basis for obtaining the inductance L in this way is as follows. That is, in order to attenuate the vibration of the railway vehicle, it is necessary to efficiently convert mechanical vibration energy into electric energy and dissipate it as heat energy. Since the capacitance C _P of the inductance L and the piezoelectric element does not consume power, when the current flowing through the resistor R is maximum, the most energy is dissipated. For this purpose, the series impedance the smaller is preferably between inductance L and a capacitance C _P, if they meet the above expression becomes theoretically zero. This condition is nothing but a condition that constitutes a resonant circuit. Note that it is desirable to optimize the value of the resistance R so that mechanical vibration is minimized.

  However, in the case of bending vibration of a large structure such as a railway vehicle, since the frequency is relatively low, the value of the inductance L becomes extremely large. It becomes a device. Therefore, in the present embodiment, by using an active element, the inductance L is equivalently realized and the apparatus is downsized.

FIG. 7 shows the configuration of the first energy conversion circuit used in the present embodiment. As shown in FIG. 6, since the same current i flows through the resistor R and the inductance L, the expression by Laplace transform of the both-end voltages v _R and v _L is expressed as the following equation.
V _R (s) = RI (s)
V _L (s) = LsI (s)
In this way, _{v L} is proportional to the derivative of _{v R.}

Therefore, as shown in FIG. 7, in the first energy conversion circuit used in the present embodiment, a differentiation circuit is configured by using active elements. The first stage of the energy conversion circuit is an input protection buffer, and the second stage is an incomplete differentiation circuit that performs incomplete differentiation and inversion using a high-voltage operational amplifier. The transfer characteristic of this energy conversion circuit is expressed as the following equation (12).

一方、図６に示す等価回路の伝達特性において、抵抗Ｒの両端電圧を入力電圧ｖ_ＩＮとし、インダクタンスＬの両端電圧を出力電圧ｖ_ＯＵＴとした場合の伝達関数において、ｓ＝ｊωと置くと、次式（１４）が得られる。

In Expression (12), when s = jω is set and divided into a real part and an imaginary part, the following Expression (13) is obtained.

On the other hand, in the transfer characteristic of the equivalent circuit shown in FIG. 6, when s = jω is set in the transfer function when the voltage across the resistor R is the input voltage v _IN and the voltage across the inductance L is the output voltage v _OUT , The following formula (14) is obtained.

By comparing the imaginary components of the equations (13) and (14), the relationship between the value of the inductance L at the primary mode natural angular frequency ω ₁ of the vehicle body model 10 and the element constant of the first energy conversion circuit. However, it is required as follows.
L = C ₁ R ₂ R ₀ (15)
However, R ₀ = R / (1 + ω ₁ ² C ₁ ² R ₁ ² ). Note that ω _L = 1 / (C ₁ R ₁ ) indicates the cutoff angular frequency of the first-order lag element of the incomplete differentiation expressed by the equation (12), and ω _L is the primary bending natural angular frequency ω. If it is set to be sufficiently larger than ₁ , it can be considered that L≈C ₁ R ₁ R in the frequency band near ω ₁ of interest.

The cut-off angular frequency ω _L of the first-order lag element prevents the high-frequency gain of the circuit transfer characteristic from becoming very large, and the frequency response phase of the equation (12) near the first-order bending frequency of the vehicle body model 10 It is set to be about 100 times the primary mode natural angular frequency ω ₁ of the vehicle body model 10 so as to reduce the deviation from 90 °.

  Note that according to the present embodiment, not all voltages generated by the piezo elements are input to the first stage circuit, but the voltage across the resistor R is input to the first stage circuit. In general, it is considered that the voltage across the resistor R is often much smaller than the voltage across the inductance L, so the voltage input to the first stage circuit can be reduced. Furthermore, in the first stage circuit, by providing an input protection buffer having a limiter characteristic by a diode, the second stage high voltage operational amplifier is prevented from being damaged.

  Further, both ends of the piezoelectric element are switched to be short-circuited, opened, or connected to the energy conversion circuit by the switch SW, and the vibration response in each case is measured in the vibration test.

  FIG. 8 shows the FRF gain in the vibration test using the first energy conversion circuit. FIG. 8 shows the FRF gain when both end electrodes of the piezo element are short-circuited and the FRF gain when both end electrodes of the piezo element are connected to the energy conversion circuit. Note that the FRF gain when both end electrodes of the piezo element are open shows substantially the same frequency characteristics as the FRF gain when both end electrodes of the piezo element are short-circuited.

  As shown in FIG. 8, the peak height of the FRF gain when both end electrodes of the piezo element are connected to the first energy conversion circuit is the peak height of the FRF gain when both end electrodes of the piezo element are short-circuited. It is found that the vibration of the vehicle body model 10 can be reduced.

  In the equivalent LR circuit shown in FIG. 6, when the optimum resistance value is small or the internal resistance of the piezo element is relatively large, the value of the resistance R needs to be small. However, even if the optimum inductance L value is the same, if the resistance R value is small, it is necessary to increase the amplification factor of the incomplete differentiation circuit in FIG. This is undesirable from the viewpoint of system stability. Therefore, it is conceivable to modify the energy conversion circuit shown in FIG. 7 as shown in FIG.

FIG. 9 shows a modification of the first energy conversion circuit, and FIG. 10 shows an equivalent circuit thereof. In the energy converter shown in Figure 9, connects the small inductance L _K than the optimum inductance L to the input terminal of the first-stage circuit, the input voltage v _IN (-α) is amplified doubles obtain an output voltage v _OUT by constitute a virtually inductance .alpha.L _K at the output terminal. Therefore, by setting the amplification factor α of the energy conversion circuit so as to satisfy (1 + α) L _K = L, a desired inductance L value can be realized. In this way, even if the value of the desired inductance L is relatively large, the inductance L _K of implementation requires only that 1 / alpha.

The amplification factor α of the energy conversion circuit is determined by the negative feedback of the second stage circuit, and becomes R ₂ / R ₁ . In this energy conversion circuit can be set independently and values of the resistance R of the inductance L, by appropriately selecting the values of inductance L _K that implements, it is possible to suppress the amplification rate α less. Further, since the amplification factor does not increase in the high frequency band unlike the incomplete differentiation circuit, the amplification factor is constant over all frequency bands.

  FIG. 11 shows an equivalent circuit when an equivalent negative CR circuit is used as the second energy conversion circuit. In this case, as shown in FIG. 11, a negative CR circuit is equivalently connected to the piezo element. In order to cancel the capacitance of the piezo element in a wide range of frequencies and make the load of the AC voltage source a pure resistance, the second energy conversion circuit equivalently constitutes a negative CR circuit. That is, by setting C = Cp, the combined impedance of the capacitance Cp of the piezo element and the negative capacitance (−C) of the energy conversion circuit can theoretically be zero at all frequencies. It is considered that a vibration damping effect can be obtained at a frequency and that vibrations in a plurality of modes are possible. However, since negative capacitance cannot be realized only by passive elements, it is necessary to configure it by an active circuit such as using an operational amplifier.

FIG. 12 shows the configuration of the second energy conversion circuit used in the present embodiment. As shown in FIG. 12, in the second energy conversion circuit, an integrating circuit is configured using active elements in order to realize negative capacitance (-C). The first stage of the energy conversion circuit is an inversion buffer for input protection, and the second stage is an incomplete integration circuit that performs incomplete integration and inversion using a high-voltage operational amplifier. The transfer characteristic of this energy conversion circuit is expressed by the following equation (16).

一方、図１１に示す等価回路の伝達特性において、抵抗Ｒの両端電圧を入力電圧ｖ_ＩＮとし、負性キャパシタンス（−Ｃ）の両端電圧を出力電圧ｖ_ＯＵＴとした場合の伝達関数において、ｓ＝ｊωと置くと、次式（１８）が得られる。

In Expression (16), when s = jω is set and divided into a real part and an imaginary part, the following Expression (17) is obtained.

On the other hand, in the transfer function of the equivalent circuit shown in FIG. 11, in the transfer function when the voltage across the resistor R is the input voltage v _IN and the voltage across the negative capacitance (−C) is the output voltage v _OUT , s = When jω is set, the following equation (18) is obtained.

By comparing the imaginary components of Expression (17) and Expression (18), the relationship between the value of the capacitance C at the first-order mode natural angular frequency ω ₁ of the vehicle body model 10 and the element constant of the second energy conversion circuit. However, it is required as follows.
C = C ₂ R ₁ / R ₀ (19)
_However, it is ^{_{R 0 = R × ω 1 2}} C 2 2 R 2 2 / (1 + ω 1 2 C 2 2 R 2 2). Note that ω _C = 1 / (C ₂ R ₂ ) indicates the cutoff angular frequency of the first-order lag element of the incomplete integration represented by the equation (16), and ω _C is the first-order bending natural angular frequency ω. If it is set to be sufficiently smaller than ₁ , it can be considered that C≈C ₂ R ₁ / R in the frequency band near ω ₁ of interest.

Here, the optimal conditions for dissipating power piezoelectric element generates a C = C _P, C <in the case of C _P is negative capacitance of the capacitance C _P and energy conversion circuit of the piezoelectric element ( The combined capacitance with -C) becomes negative and the system becomes unstable. Therefore, in this embodiment, it is slightly greater than the value of the value of C C _P. Further, the cutoff angular frequency ω _C of the incomplete integration circuit is set to be about 1/100 of the first-order mode natural angular frequency ω ₁ of the vehicle body model 10.

  In this embodiment, an input protection buffer having a limiter characteristic using a diode is provided as the first stage circuit to prevent the second stage high voltage operational amplifier from being damaged.

  Further, both ends of the piezoelectric element are switched to be short-circuited, opened, or connected to the energy conversion circuit by the switch SW, and the vibration response in each case is measured in the vibration test.

  FIG. 13 shows the FRF gain in the vibration test using the second energy conversion circuit. FIG. 13 shows the FRF gain when both end electrodes of the piezo element are short-circuited and the FRF gain when both end electrodes of the piezo element are connected to the energy conversion circuit. Note that the FRF gain when both end electrodes of the piezo element are open shows substantially the same frequency characteristics as the FRF gain when both end electrodes of the piezo element are short-circuited.

  As shown in FIG. 13, it can be seen that higher performance than that of the first energy conversion circuit is obtained by connecting both end electrodes of the piezoelectric element to the second energy conversion circuit. This is because the incomplete differentiation circuit used in the first energy conversion circuit increases the resistance component, whereas the incomplete integration circuit used in the second energy conversion circuit has a function of reducing the resistance component. This is probably because the combined resistance value approaches the optimum value as a result of the internal resistance of the piezo element being offset.

FIG. 14 shows a modification of the second energy conversion circuit, and FIG. 15 shows an equivalent circuit thereof. In energy conversion circuit shown in FIG. 14, by the capacitance C _K is connected to the input terminal of the first-stage circuit, the input voltage v _IN is amplified in the β multiplied to obtain an output voltage v _OUT, virtually negative at the output terminal A negative capacitance (−βC _K ). Therefore, by setting the amplification factor β of the energy conversion circuit so as to satisfy C _K / (1−β) = − C, a desired negative capacitance (−C) is obtained using a capacitor having a normal positive value. The value of can be realized.

The amplification factor β of the energy conversion circuit is determined by the negative feedback of the second stage circuit and becomes R ₂ / R ₁ . In this energy conversion circuit, it is possible independently set the values of the resistance R of the negative capacitance (-C), by appropriately selecting the value of the capacitance C _K that implements a low amplification factor β Can be suppressed. In addition, the gain is constant over all frequency bands.

  In the above example, in order to cancel out the capacitance component of the piezo element, an inductance component and a negative capacitance component are equivalently generated. However, the more general concept of the present invention is applied to the third to fifth energy. The conversion circuit will be described below.

FIG. 16 shows a third energy conversion circuit. In the third energy conversion circuit, passive elements having impedances Z ₀ and Z ₁ are connected in series between one terminal of the piezo element and a reference potential (here, ground potential). Amplifier circuit amplifies the voltage across v _IN passive components having an impedance Z _1, the output voltage v _OUT of the amplifier circuit is supplied to the other terminal of the piezoelectric element. Thus, the amplifier circuit, the impedance Z ₂ of the desired to be realized, are equivalently is generated between the other terminal and a reference potential of the piezo element.

Here, when Z ₀ = 0, Z ₁ = R, and Z ₂ = jωL, it is equal to the first energy conversion circuit shown in FIG. In that case, the energy conversion circuit shown in FIG. 7 is realized by designing the amplifier circuit as an incomplete differentiation circuit and determining the gain G (jω) so as to generate Z ₂ = jωL equivalently. Can do.

In general, the impedance Z _OPT to be realized by the energy conversion circuit is obtained based on the impedance of the piezo element, and the impedances Z ₀ and Z ₁ and the gain of the amplifier circuit are satisfied so as to satisfy the following equation (20). G (jω) is determined.
Z _OPT = Z ₀ + Z ₁ + Z ₂ = Z ₀ + (1-G (jω)) Z ₁ (20)

Note that the combination of Z ₀ , Z ₁ , and G (jω) is not uniquely determined only by the condition that the expression (20) is satisfied, so that the gain of the amplifier circuit can be kept low, component mounting can be facilitated, etc. It may be determined according to the request. As described above, according to the third energy conversion circuit, an arbitrary impedance Z _OPT can be realized. Therefore, it is possible to cope with a case where a complicated impedance characteristic is desired to be realized.

On the other hand, when it is desired to ground one end of the piezo element to the vehicle body, a fourth energy conversion circuit shown in FIG. 17 can be used. In the fourth energy conversion circuit, a passive element having impedances Z ₀ and Z ₁ is connected in series between one terminal of the piezoelectric element and the inverting input terminal of the insulation amplifier circuit, and the other terminal of the piezoelectric element. Are connected to a reference potential (here, ground potential). Insulation amplifier circuit, the voltage across v _IN passive components having an impedance Z ₁ and the differential amplifier, the output voltage v _OUT insulating amplifier circuit is fed back to the inverting input terminal. Thus, the insulation amplifier circuit, the impedance Z ₂ of the desired to be realized, are equivalently is generated between the inverting input terminal of the other terminal and the insulation amplifier circuit of the piezoelectric element. Here, assuming that the gain of the insulation amplifier circuit is −G (jω), the impedance of the entire energy conversion circuit is Z ₀ + (1−G (jω)) Z ₁ .

According to the fourth energy conversion circuit, one end of the piezoelectric element can be grounded to the vehicle body in common with the output side of the insulation amplifier circuit. Further, even if one end is inappropriate grounding the passive element having an impedance Z ₁ when considering the influence of noise or the like, it can be insulated from the output side to the input side by using an insulating amplifier circuit It is.

In the above example, the energy conversion circuit is configured using an analog amplifier circuit. However, the energy conversion circuit may be configured using digital signal processing.
FIG. 18 shows a fifth energy conversion circuit. The fifth energy conversion circuit includes an analog amplification circuit in the third energy conversion circuit shown in FIG. 16, an ADC (analog to digital converter) 16 and a DSP (digital signal processor). Circuit) 17, DAC (digital to analog converter) 18, and driver amplifier 19. The gain of the system including these is represented by G (jω).

The ADC 16 converts the voltage v _IN across the passive element having the impedance Z ₁ into a digital signal. The DSP 17 performs digital signal processing such as incomplete differentiation, incomplete integration, or amplification on the digital signal generated by the ADC 16. The DAC 18 generates an analog signal based on the digital signal subjected to signal processing by the DSP 17. The driver amplifier 19 amplifies the analog signal generated by the DAC 18 and supplies the output voltage v _OUT to the other terminal of the piezo element.

Here, the DSP 17 performs digital signal processing based on software programmed so as to realize a desired impedance Z _OPT as a load of the piezo element so that the impedance in the entire energy conversion circuit satisfies Expression (20). Yes. Accordingly, the impedance of the entire energy _{converter, Z 0 + (1-G} (jω)) may be _{Z 1.}

  Further, when the characteristic of the gain G (jω) becomes complicated due to a demand for performance improvement or when it is necessary to change the characteristic according to the situation, the digital signal processing part is taken into the computer to obtain the desired value. The impedance can be realized easily and immediately. Note that the analog signal processing in the fourth energy conversion circuit shown in FIG. 17 can be replaced with digital signal processing.

FIG. 19 is a diagram showing a specific example of the fifth energy conversion circuit shown in FIG. As shown in FIG. 19, in this energy circuit, Z ₀ = 0 and Z ₁ = R. Therefore, the DSP 17 performs incomplete differentiation as digital signal processing.

  The present invention can be used in a railway vehicle in which vibration energy of the vehicle body is dissipated to reduce vibration.

It is a conceptual diagram which shows the basic composition of this invention. It is a figure which shows the vehicle body model of the railway vehicle used in a vibration test. It is a figure which shows the FRF gain of the acceleration on the floor in the position of 0.9 m from the vehicle end of a vehicle body model. It is a figure which shows the natural frequency and vibration mode shape of a railway vehicle model. 1 is a diagram illustrating a model of a railway vehicle model according to an embodiment of the present invention. It is a figure which shows the equivalent circuit of a 1st energy conversion circuit. It is a figure which shows a 1st energy conversion circuit. It is a figure which shows the FRF gain in the vibration test using a 1st energy conversion circuit. It is a figure which shows the modification of a 1st energy conversion circuit. FIG. 10 is a diagram showing an equivalent circuit of the circuit shown in FIG. 9. It is a figure which shows the equivalent circuit of a 2nd energy conversion circuit. It is a figure which shows a 2nd energy conversion circuit. It is a figure which shows the FRF gain in the vibration test using a 2nd energy conversion circuit. It is a figure which shows the modification of a 2nd energy conversion circuit. It is a figure which shows the equivalent circuit of the circuit shown in FIG. It is a figure which shows a 3rd energy conversion circuit. It is a figure which shows a 4th energy conversion circuit. It is a figure which shows the 5th energy conversion circuit. It is a figure which shows the specific example of a 5th energy conversion circuit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Structure 2 Piezo element 3 Piezoelectric material 4, 5 Electrode 6 Energy conversion circuit 10 Body model 11 Air spring 12 Load cell 13 Electrodynamic exciter 16 ADC
17 DSP
18 DAC
19 Driver amplifier

Claims (9)

At least one piezo element that is attached to a structure of a vehicle body for a railway vehicle and generates a voltage by elastically deforming in response to vibration of the vehicle body;
By generating an output voltage based on the voltage generated at the first terminal of the piezo element and supplying the output voltage to the second terminal of the piezo element, at least part of the electric energy generated by the piezo element. An energy conversion circuit that converts heat into thermal energy;
And the energy conversion circuit comprises:
A first passive element connected to a first terminal of the piezo element;
The piezoelectric element having at least one frequency based on a voltage generated at both ends of the first passive element or a second passive element connected in series to the first passive element, having an insulation amplifier circuit An active circuit that equivalently generates an impedance component for canceling the capacitance component of
The first passive element or the first and second passive elements connected in series are connected between a first terminal of the piezo element and an inverting input terminal of the insulation amplifier circuit. A rail vehicle. The first passive element includes a resistor;
The active circuit generates an inductance component equivalently by incomplete differentiation and inversion of the voltage generated across the resistor,
The railway vehicle according to claim 1 . The first passive element includes a resistor;
The active circuit equivalently generates a negative capacitance component by incompletely integrating the voltage generated across the resistor;
The railway vehicle according to claim 1 . The first and second passive elements include a resistor and an inductance connected in series;
The active circuit generates an inductance component equivalently by inverting and amplifying the voltage generated across the inductance.
The railway vehicle according to claim 1 . The first and second passive elements comprise resistors and capacitances connected in series;
The active circuit amplifies the voltage generated across the capacitance to generate a negative capacitance component equivalently;
The railway vehicle according to claim 1 . The railway vehicle according to claim 1, wherein the active circuit includes an amplifying unit that converts an analog voltage into a digital signal and amplifies the analog signal with a predetermined gain . The amplifying section,
An analog / digital converter for converting an analog voltage into a digital signal;
A digital signal processing circuit for performing signal processing on a digital signal output from the analog / digital converter;
A digital / analog converter for converting a digital signal output from the digital signal processing circuit into an analog signal;
The railway vehicle according to claim 6 . The railway vehicle according to claim 7 , wherein the active circuit further includes an output circuit that supplies an output voltage of the digital / analog converter to a second terminal of the piezo element. The railway vehicle according to any one of claims 1 to 8 , wherein a plurality of piezo elements are attached to the vehicle body.

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