JP4190904B2 - Piezoelectric actuator drive - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a piezoelectric actuator and a piezoelectric actuator driving apparatus that determines a failure on the side that supplies power to the piezoelectric actuator and protects the piezoelectric actuator from the power supply in the event of an abnormality.
[0002]
[Prior art]
In a conventional protection circuit for a piezoelectric actuator drive power supply, a high voltage power supply for driving a piezoelectric actuator and a control power supply are connected to the high voltage power supply circuit, a high voltage power supply circuit and an input signal are connected to the voltage control circuit, and the voltage control circuit The output signal is connected to the piezoelectric actuator via the protection circuit, and the current flowing through the piezoelectric actuator is detected in the protection circuit. If the detected current value is larger than the specified value, the switching circuit provided in the protection circuit The current is limited by the element (for example, see Patent Document 1 below).
[0003]
[Patent Document 1]
JP-A-9-271136
[Problems to be solved by the invention]
Since the conventional piezoelectric actuator driving device is configured as described above, when the current value detected by the protection circuit is 0, it is impossible to distinguish between a piezoelectric actuator driving circuit open failure and a piezoelectric actuator open failure. was there. Further, when the current value detected by the protection circuit is larger than the specified value, there is a problem that it is impossible to distinguish between a piezoelectric actuator drive circuit short circuit failure and a piezoelectric actuator short circuit failure. Furthermore, there has been a problem that the piezoelectric actuator fails when a voltage exceeding the rating is applied to the piezoelectric actuator.
[0005]
The present invention has been made in order to solve the above-described problems, and obtains a piezoelectric actuator driving apparatus that determines a failure of a piezoelectric actuator and a drive signal amplifier circuit and protects the piezoelectric actuator from an abnormal applied voltage at the time of the failure. For the purpose.
[0006]
[Means for Solving the Problems]
The piezoelectric actuator drive device according to the present invention estimates the applied voltage and current to the piezoelectric actuator based on the drive signal generated by the drive signal generator, and also detects the estimated voltage, the estimated current and the voltage detected by the voltage detection circuit, and A failure determination unit that determines failure of the piezoelectric actuator and the drive signal amplification circuit by comparing with a detection current by the current detection circuit, and a switching circuit that switches voltage supply from the drive signal amplification circuit to the piezoelectric actuator according to the determination result It is provided.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below.
Embodiment 1 FIG.
FIG. 1 is a block diagram showing a piezoelectric actuator driving apparatus according to Embodiment 1 of the present invention. In the figure, a driving signal generator 1 generates a piezoelectric actuator driving signal so that the piezoelectric actuator performs a desired expansion / contraction operation. The high voltage power supply 2 generates a high voltage power supply, and the drive signal amplification circuit 4 in the piezoelectric actuator drive circuit 3 amplifies the piezoelectric actuator drive signal based on the high voltage power supply. The on / off switch (switching circuit) 5 in the piezoelectric actuator driving circuit 3 is switched on / off by a switch switching determination unit (switching circuit) 16 described later.
The output current limit circuit 6 limits the current flowing from the piezoelectric actuator drive circuit 3 to the piezoelectric actuator 9, and the output voltage limit circuit 7 limits the voltage applied from the piezoelectric actuator drive circuit 3 to the piezoelectric actuator 9.
The voltage detection circuit 8 detects an applied voltage from the piezoelectric actuator drive circuit 3 to the piezoelectric actuator 9. The piezoelectric actuator 9 expands and contracts according to the applied voltage, and the current detection circuit 10 flows to the piezoelectric actuator 9. The current is detected.
The failure determiner 11 estimates the applied voltage and current to the piezoelectric actuator 9 based on the piezoelectric actuator drive signal generated by the drive signal generator 1, and the estimated voltage, the estimated current, and the voltage detected by the voltage detection circuit 8. The failure of the piezoelectric actuator 9 and the drive signal amplifying circuit 4 is determined by comparison with the current detected by the current detection circuit 10. The state output unit 12 outputs the determination result by the failure determination unit 11 to the outside, the failure state storage unit 13 stores the determination result by the failure determination unit 11, and the reset signal generator 14 responds to the operation. A reset signal for resetting the determination result stored in the failure state storage unit 13 is generated.
The piezoelectric actuator drive circuit on / off signal generator 15 generates an on signal when it is desired to operate the piezoelectric actuator 9, and the switch switching determiner 16 is a piezoelectric actuator drive circuit on / off signal generator 15. The on / off switch 5 is turned on when an ON signal is generated from the control signal and the determination result by the failure determination unit 11 stored in the failure state storage unit 13 permits the voltage supply to the piezoelectric actuator 9. Is.
[0008]
Next, the operation will be described.
In FIG. 1, a drive signal generator 1 generates a piezoelectric actuator drive signal, and a drive signal amplification circuit 4 amplifies the piezoelectric actuator drive signal. Since the piezoelectric actuator 9 needs to be driven at a high voltage, the drive signal amplification circuit 4 is driven by the high voltage power supply 2.
When the piezoelectric actuator drive circuit on / off signal generator 15 generates a drive circuit on signal, and the drive signal amplifier circuit 4 and the piezoelectric actuator 9 are normal, the switch changeover determination unit 16 selects the piezoelectric actuator drive circuit on / off switch. 5 is switched on, the piezoelectric actuator drive circuit 3 is turned on, and a desired voltage can be applied to the piezoelectric actuator 9.
The current flowing through the piezoelectric actuator 9 is limited by the output current limiting circuit 6, and the voltage applied to the piezoelectric actuator 9 is limited by the output voltage limiting circuit 7. The voltage applied to the piezoelectric actuator 9 is detected by the voltage detection circuit 8, and the current flowing through the piezoelectric actuator 9 is detected by the current detection circuit 10.
FIG. 2 is a circuit diagram showing the configuration of the current detection circuit. The voltage detection circuit 8 is connected to one of the piezoelectric actuators (C) 9, and one of the current detection resistors R of the current detection circuit 10 is connected to the other. The other of the current detection resistor R is grounded. By detecting the voltage V across the current detection resistor R, the current I flowing through the piezoelectric actuator 9 can be detected.
The piezoelectric actuator drive signal of the drive signal generator 1, the piezoelectric actuator applied voltage obtained by the voltage detection circuit 8, and the current flowing through the piezoelectric actuator 9 obtained by the current detection circuit 10 are input to the failure determiner 11, and the failure determiner 11 Based on the piezoelectric actuator drive signal of the drive signal generator 1, the piezoelectric actuator applied voltage and the current flowing through the piezoelectric actuator are estimated, and the estimated voltage and estimated current, and the piezoelectric actuator applied voltage and current detection circuit obtained by the voltage detection circuit 8 are estimated. When the current flowing through the piezoelectric actuator obtained by 10 is different, it is determined that the piezoelectric actuator 9 or the drive signal amplifier circuit 4 is abnormal, and a failure detection signal is output to the failure state storage unit 13 and a state output device. 12 is output. The piezoelectric actuator drive signal of the drive signal generator 1 is v, the amplification factor of the drive signal amplifier circuit 4 is A, the voltage applied to the piezoelectric actuator 9 is V0, the current flowing through the piezoelectric actuator 9 is I, and the capacitance of the piezoelectric actuator 9 is When C, the resistance value of the current detection circuit 10 is R, and the voltage across the resistance of the current detection circuit 10 is V, the estimated voltage applied to the piezoelectric actuator is expressed by Equation (1).
V0 = A · v (1)
Further, the estimated current value flowing through the piezoelectric actuator 9 is expressed by Expression (2).
C ・ V0 ＝ ∫I ・ dt
I = C · (dV0 / dt) = V / R (2)
V = R · C · (dV0 / dt)
FIG. 3 is an explanatory diagram showing an abnormality detection pattern determined by the failure determiner.
When the voltage detection value obtained by the voltage detection circuit 8 and the current detection value obtained by the current detection circuit 10 indicate normal values equivalent to the estimated values, the failure determiner 11 indicates that the piezoelectric actuator 9 and the drive signal amplification circuit 4 are normal. It is judged that. When the voltage detection value obtained by the voltage detection circuit 8 indicates a normal value equivalent to the estimated value, and the current detection value obtained by the current detection circuit 10 indicates 0, the failure determination unit 11 has a piezoelectric actuator open failure. to decide. When the voltage detection value obtained by the voltage detection circuit 8 indicates a pulse and the current detection value obtained by the current detection circuit 10 indicates an overcurrent, the failure determination unit 11 determines that there is a piezoelectric actuator short-circuit failure. When the voltage detection value obtained by the voltage detection circuit 8 indicates 0 and the current detection value obtained by the current detection circuit 10 indicates 0, the failure determiner 11 determines that the drive signal amplifier circuit is open failure. When the voltage detection value obtained by the voltage detection circuit 8 indicates a high-voltage power supply voltage and the current detection value obtained by the current detection circuit 10 indicates a pulse, the failure determiner 11 determines that the drive signal amplifier circuit is short-circuited. . Therefore, the failure determination unit 11 identifies the piezoelectric actuator and drive signal amplifier circuit normal, the piezoelectric actuator open failure, the piezoelectric actuator short circuit failure, the drive signal amplifier circuit open failure, and the drive signal amplifier circuit short circuit failure based on the abnormality detection pattern shown in FIG. .
The failure state storage unit 13 stores failure detection information when a failure occurs in the piezoelectric actuator 9 or the drive signal amplification circuit 4, and resets the failure detection information even when the piezoelectric actuator 9 or the drive signal amplification circuit 4 returns to a normal state. do not do. The failure detection information from the failure state storage unit 13 and the drive circuit ON / OFF signal from the piezoelectric actuator drive circuit ON / OFF signal generator 15 are input to the switch changeover determination unit 16, and the piezoelectric actuator drive circuit ON / OFF signal generator 15 is input. When a drive circuit off signal is output from the failure state or when failure detection information is output from the failure state storage 13, the piezoelectric actuator drive circuit on / off switch 5 is switched off. Based on the failure information from the status output unit 12, the failure location and the cause of the failure of the piezoelectric actuator 9 or the drive signal amplifier circuit 4 are estimated, and when the piezoelectric actuator 9 or the drive signal amplifier circuit 4 returns to the normal state due to failure repair or the like, the reset signal The fault detection information of the fault state storage 13 is reset by the generator 14 and normal operation is performed.
[0009]
As described above, according to the first embodiment, the voltage applied to the piezoelectric actuator 9 can be limited by providing the output voltage limiting circuit 7, and an unexpectedly large voltage is applied to the piezoelectric actuator 9. This can prevent the piezoelectric actuator 9 from being broken. Further, by providing the output current limiting circuit 6, the current flowing through the piezoelectric actuator 9 can be limited. When the current flowing through the piezoelectric actuator 9 increases, the mechanical vibration frequency of the piezoelectric actuator 9 increases, and the mechanical vibration frequency reaches the resonance frequency of the piezoelectric actuator 9. By setting the current limit value to an appropriate value at, the drive frequency band of the piezoelectric actuator drive device can be set lower than the resonance frequency of the piezoelectric actuator 9, and the piezoelectric actuator 9 can be prevented from being broken.
Further, the voltage applied to the piezoelectric actuator 9 can be detected by providing the voltage detection circuit 8, and the current flowing through the piezoelectric actuator 9 can be detected by providing the current detection circuit 10, and the failure determination unit 11 is provided. Thus, the piezoelectric actuator applied voltage and the current flowing through the piezoelectric actuator 9 are estimated based on the piezoelectric actuator drive signal of the drive signal generator 1, the estimated values thereof, and the piezoelectric actuator applied voltage and current detection circuit obtained by the voltage detection circuit 8 10 is compared with the current flowing in the piezoelectric actuator, and the abnormality detection pattern determines that the piezoelectric actuator and the drive signal amplifier circuit are normal, the piezoelectric actuator is open, the piezoelectric actuator is short-circuited, the drive signal amplifier is open, and the drive signal is amplified. Identify short circuit faults Bets can be, it is possible to estimate the fault location and failure cause.
Furthermore, when a failure occurs in the piezoelectric actuator 9 or the drive signal amplifier circuit 4 by providing the status output device 12, the failure can be immediately understood. Further, by providing the failure state storage unit 13, failure detection information can be stored when a failure occurs in the piezoelectric actuator 9 or the drive signal amplifier circuit 4, and the piezoelectric actuator 9 or the drive signal amplifier circuit 4 is in a normal state. Even in the case of return, failure detection information is not automatically reset, and the failure state is saved, so that the failure location and cause of failure of the piezoelectric actuator 9 or the drive signal amplifier circuit 4 can be estimated based on the failure detection information. it can. Further, by providing the reset signal generator 14, when a failure occurs, the failure state storage unit 13 can be initialized after specifying the failure location and the cause.
Further, by providing the switch changeover determination device 16, the piezoelectric actuator drive circuit can be turned off when a failure occurs, and the piezoelectric actuator 9 can be protected from an abnormal applied voltage at the time of the failure.
[0010]
Embodiment 2. FIG.
FIG. 4 is a block diagram showing a piezoelectric actuator driving apparatus according to Embodiment 2 of the present invention. In the figure, the first false detection prevention circuit 21 detects electrical noise of the voltage detected by the voltage detection circuit 8. The second false detection prevention circuit 22 removes electrical noise of the current detected by the current detection circuit 10. Other configurations are the same as those in FIG.
[0011]
Next, the operation will be described.
In FIG. 4, the voltage applied to the piezoelectric actuator 9 is detected by the voltage detection circuit 8, and the current flowing through the piezoelectric actuator 9 is detected by the current detection circuit 10. The voltage detected by the voltage detection circuit 8 is input to the failure determination unit 11 via the first erroneous detection prevention circuit 21 configured by, for example, a low-pass filter, and the current detected by the current detection circuit 10 is For example, it is input to the failure determination unit 11 via the second erroneous detection prevention circuit 22 configured by a low-pass filter, and the failure determination unit 11 includes the first erroneous detection prevention circuit 21 and the second erroneous detection prevention circuit. The failure of the piezoelectric actuator 9 or the drive signal amplifier circuit 4 corresponding to the detected voltage and detected current via 22 is determined.
[0012]
As described above, according to the second embodiment, by providing the first false detection prevention circuit 21 and the second false detection prevention circuit 22, the electrical noise of the voltage applied to the piezoelectric actuator 9 is removed. Thus, the voltage can be detected, the electric noise of the current flowing through the piezoelectric actuator 9 can be removed, and the current can be detected, so that the failure determination unit 11 can be prevented from erroneously detecting a failure.
[0013]
Embodiment 3 FIG.
FIG. 5 is a block diagram showing a piezoelectric actuator driving apparatus according to Embodiment 3 of the present invention. In the figure, a noise removing circuit 31 is an electric noise of a voltage supplied from the piezoelectric actuator driving circuit 3 to the piezoelectric actuator 9. Is to be removed. Other configurations are the same as those in FIG.
[0014]
Next, the operation will be described.
In FIG. 5, the output voltage of the drive signal amplification circuit 4 is applied to the piezoelectric actuator 9 via the noise removal circuit 31.
FIG. 6 is a circuit diagram showing the configuration of the noise removal circuit. By inserting a resistor R1 in series with the piezoelectric actuator 9, a low-pass filter can be configured by the resistor R1 and the capacitance C of the piezoelectric actuator 9. The voltage applied to the actuator 9 is a voltage signal that has passed through the low-pass filter.
[0015]
As described above, according to the third embodiment, by providing the noise removing circuit 31, the electrical noise of the voltage applied to the piezoelectric actuator 9 can be removed, and an unexpected operation of the piezoelectric actuator 9 can be performed. Therefore, a desired operation of the piezoelectric actuator 9 can be realized.
[0016]
Embodiment 4 FIG.
FIG. 7 is a block diagram showing a piezoelectric actuator driving apparatus according to Embodiment 4 of the present invention. In the figure, the current detection circuit 10 is deleted, and the noise removal circuit 41 is shared with the current detection circuit. Is. Other configurations are the same as those in FIG.
[0017]
Next, the operation will be described.
In FIG. 5, the current detection circuit 10 is provided in the subsequent stage of the piezoelectric actuator 9 to detect the current flowing through the piezoelectric actuator 9. However, as shown in FIG. 7, the noise removal circuit 41 is shared with the current detection circuit. It is good also as a structure.
FIG. 8 is a circuit diagram showing the configuration of the noise removal circuit. By detecting the voltage V1 across the resistor R1 constituting the low-pass filter, the current flowing through the piezoelectric actuator 9 is detected from the relational expression of I = V1 / R1. be able to.
[0018]
As described above, according to the fourth embodiment, by sharing the noise removal circuit 41 with the current detection circuit, the current detection circuit 10 becomes unnecessary, and the circuit configuration can be simplified.
[0019]
Embodiment 5 FIG.
FIG. 9 is a block diagram showing a piezoelectric actuator driving apparatus according to Embodiment 5 of the present invention. In the figure, the high voltage power supplies are a first high voltage power supply 51 and a second high voltage power supply 52. The drive signal amplifier circuit 4 including the third high-voltage power supply 53 is configured by a plurality of high-voltage power supplies. Other configurations are the same as those in FIG.
[0020]
Next, the operation will be described.
In FIG. 9, since the piezoelectric actuator 9 needs to be driven at a high voltage, the drive signal amplification circuit 4 includes a first high-voltage power supply 51, a second high-voltage power supply 52, and a third high-voltage power supply. It is driven by the power source 53 for use.
FIG. 10 is a block diagram showing the configuration of the high-voltage power supply. The high-voltage power supply is composed of, for example, a three-stage DC / DC converter connected in series. When the high voltage required for the drive signal amplifier circuit 4 is V0 and the voltages of the high-voltage power supplies 51 to 53 are V1, V2, and V3, respectively, the high-voltage power supplies are adjusted so that V0 = V1 + V2 + V3 holds. To do. In general, each high-voltage power supply is adjusted so that V1 = V2 = V3 = V0 / 3.
[0021]
As described above, according to the fifth embodiment, the first high-voltage power supply 51, the second high-voltage power supply 52, and the third high-voltage power supply are used as the high-voltage power supply for the drive signal amplifier circuit 4. By connecting the power supply 53 for power supply in series, the output voltage is reduced when one or two power supplies for high-voltage power supply fails, but the piezoelectric actuator drive circuit 3 can operate and the power supply system is redundant. Therefore, it is possible to realize a circuit configuration that is robust against power failure.
In the fifth embodiment, the first high-voltage power source 51, the second high-voltage power source 52, and the third high-voltage power source 53 are used as the high-voltage power sources for the drive signal amplifier circuit 4. The power supply for the high-voltage power supply includes two or more.
[0022]
【The invention's effect】
As described above, according to the present invention, the failure determiner determines the failure location and the cause of failure of the piezoelectric actuator and the drive signal amplifier circuit according to the comparison of the estimated voltage and estimated current with the detected voltage and detected current. Can do. For example, the abnormality detection pattern can identify a piezoelectric actuator and drive signal amplifier circuit normal, a piezoelectric actuator open failure, a piezoelectric actuator short circuit failure, a drive signal amplifier circuit open failure, a drive signal amplifier circuit short circuit failure, and the like.
Further, the switching circuit has an effect of blocking the voltage supply from the drive signal amplification circuit to the piezoelectric actuator when the failure is determined by the failure determination device, and protecting the piezoelectric actuator from an abnormal applied voltage at the time of the failure. is there.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a piezoelectric actuator driving apparatus according to Embodiment 1 of the present invention.
FIG. 2 is a circuit diagram showing a configuration of a current detection circuit.
FIG. 3 is an explanatory diagram showing an abnormality detection pattern determined by a failure determiner.
FIG. 4 is a block diagram showing a piezoelectric actuator driving apparatus according to Embodiment 2 of the present invention.
FIG. 5 is a block diagram showing a piezoelectric actuator driving apparatus according to Embodiment 3 of the present invention.
FIG. 6 is a circuit diagram showing a configuration of a noise removal circuit.
FIG. 7 is a block diagram showing a piezoelectric actuator driving apparatus according to Embodiment 4 of the present invention.
FIG. 8 is a circuit diagram showing a configuration of a noise removal circuit.
FIG. 9 is a block diagram showing a piezoelectric actuator driving apparatus according to Embodiment 5 of the present invention.
FIG. 10 is a block diagram showing a configuration of a high voltage power supply.
[Explanation of symbols]
1 drive signal generator, 2 high voltage power supply, 3 piezoelectric actuator drive circuit, 4 drive signal amplification circuit, 5 on / off switch (switching circuit), 6 output current limit circuit, 7 output voltage limit circuit, 8 voltage detection circuit, 9 Piezoelectric actuator, 10 Current detection circuit, 11 Failure judgment device, 12 State output device, 13 Failure state storage device, 14 Reset signal generator, 15 Piezoelectric actuator drive circuit on / off signal generator, 16 Switch switching judgment device (switching) Circuit), 21 first false detection prevention circuit, 22 second false detection prevention circuit, 31 noise removal circuit, 41 noise removal circuit, 51 first high voltage power supply, 52 second high voltage power supply 53 A third power source for the high voltage power source.

Claims (7)

A piezoelectric actuator that expands and contracts according to the applied voltage;
A drive signal generator for generating a drive signal so that the piezoelectric actuator performs a desired expansion and contraction operation;
A drive signal amplifier circuit that amplifies the drive signal generated by the drive signal generator based on a high-voltage power supply and supplies the amplified signal to the piezoelectric actuator;
A voltage detection circuit for detecting a voltage applied to the piezoelectric actuator;
A current detection circuit for detecting a current flowing through the piezoelectric actuator;
Based on the drive signal generated by the drive signal generator, the applied voltage and current to the piezoelectric actuator are estimated, and the estimated voltage and estimated current, the detection voltage by the voltage detection circuit, and the detection current by the current detection circuit A failure determination device for determining failure of the piezoelectric actuator and the drive signal amplifier circuit by comparison with
A piezoelectric actuator drive device comprising: a switching circuit that switches voltage supply from the drive signal amplifier circuit to the piezoelectric actuator in accordance with a determination result by the failure determiner. An output current limiting circuit for limiting the current flowing from the drive signal amplifier circuit to the piezoelectric actuator;
2. The piezoelectric actuator driving apparatus according to claim 1, further comprising an output voltage limiting circuit for limiting a voltage applied to the piezoelectric actuator. A status output device for outputting the determination result by the failure determiner;
A failure state storage device for storing the determination result by the failure determination device;
The piezoelectric actuator driving apparatus according to claim 1, further comprising a reset signal generator that resets the determination result stored in the failure state storage unit. A first false detection prevention circuit for removing electrical noise of the voltage detected by the voltage detection circuit;
The piezoelectric actuator drive according to any one of claims 1 to 3, further comprising: a second false detection prevention circuit that removes electrical noise of a current detected by the current detection circuit. apparatus. 5. The piezoelectric actuator driving device according to claim 1, further comprising a noise removal circuit that removes electrical noise of a voltage supplied from the drive signal amplification circuit to the piezoelectric actuator. . 6. The piezoelectric actuator driving apparatus according to claim 5, wherein the noise removal circuit is shared with the current detection circuit. The piezoelectric actuator driving apparatus according to any one of claims 1 to 6, wherein the high-voltage power supply includes a plurality of high-voltage power supplies that drive the drive signal amplifier circuit.

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