Piezoelectric actuator precision driving circuit capable of switching working modes

Abstract

The invention provides a piezoelectric actuator precision driving circuit capable of switching working modes, and belongs to the field of driving circuits. Comprising a voltage open-loop driving circuit, a charge driving circuit and a feedback driving circuit based on a strain gauge, the voltage open-loop driving circuit, the charge driving circuit and the feedback driving circuit based on the strain gauge are connected in parallel, the input end of each branch is connected with a relay, and the output end of each branch is connected with a proportional regulator. The mode of driving the piezoelectric element can be selected by controlling the relays on the three branches, so that the driving circuit has the advantages of three driving modes, the effect of adjustable hybrid driving of each driving mode can be achieved by utilizing the proportional regulator, and the problems that an existing driving circuit is single in working mode and limited in use scene are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of drive circuits, and in particular to a piezoelectric actuator precision drive circuit capable of switching working modes. Background Art

[0002] Micro-nano precision positioning technology is widely used in precision manufacturing, semiconductors, aerospace, biomedicine, micro-optical systems and other fields. Piezoelectric materials have the characteristics of fast response, large output force, high rigidity, and no electromagnetic interference. Piezoelectric actuators based on piezoelectric materials work by using the inverse piezoelectric effect of piezoelectric materials to convert electrical energy into mechanical energy. Due to their high displacement resolution, wide frequency response, compact size and high rigidity, they are widely used for precise positioning control from microns to sub-nanometers.

[0003] Piezoelectric actuators can be driven by three precise driving methods: voltage open-loop drive, charge drive, and strain gauge-based feedback drive. The voltage open-loop drive method is simple and not affected by sensor noise. It can be used to test the displacement resolution of piezoelectric actuators, but it has the disadvantages of poor linearity and large hysteresis. Charge drive can achieve high linearity without using a displacement sensor, and can also achieve a higher driving frequency, but the stiffness of the actuator will be reduced when driven under voltage control. Strain gauge feedback drive is a closed-loop drive method that uses strain gauges as feedback elements. It has low cost, good effect, and can be integrated with the actuator, but the driving frequency is low.

[0004] In the prior art, the driving mode of the driving circuit is often relatively single, and it is impossible to combine the advantages of multiple driving modes. For example, the patent publication number CN102025339A discloses a piezoelectric actuator driving circuit, which can stably drive the piezoelectric actuator with a lower power supply voltage and a larger amplitude without setting a boost circuit of a DC-DC converter. However, it still only provides one driving mode, and it cannot combine the advantages of multiple driving modes, and the product performance and scope of use are limited. Summary of the invention

[0005] The technical problem to be solved by the present invention is how to solve the problem that the existing piezoelectric actuator driving circuit adopts a single driving mode and has limitations.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a precision driving circuit of a piezoelectric actuator with switchable working modes, comprising a voltage open-loop driving circuit, a charge driving circuit and a feedback driving circuit based on a strain gauge, wherein the voltage open-loop driving circuit, the charge driving circuit and the feedback driving circuit based on the strain gauge are connected in parallel, each branch is connected to a relay at the input end and a proportional regulator at the output end, and the feedback driving circuit based on the strain gauge comprises a full-bridge unit, a strain amplifier unit, an instrument amplifier unit and a high-voltage amplifier unit and is connected in sequence.

[0007] Preferably, the full-bridge unit of the strain gauge-based feedback drive circuit includes resistance strain gauges R10, R11, R13, and R12, and the resistance strain gauges R10, R11, R13, and R12 are connected in sequence to form a closed loop, and one end of the resistance strain gauge R10 connected to the resistance strain gauge R11 is connected to a power supply, and one end of the resistance strain gauge R12 connected to the resistance strain gauge R13 is grounded.

[0008] In the present invention, the resistance strain gauges R11 and R13 are oriented along the length direction, while R10 and R12 are oriented along the transverse direction. This arrangement can effectively eliminate the influence of temperature changes on resistance and improve sensitivity.

[0009] Preferably, the strain amplifier unit of the strain gauge-based feedback drive circuit includes amplifiers U4, U5, and U6, and also includes resistors R7, R8, R15 and a signal compensator. The in-phase input terminal of the amplifier U4 is connected to the end where the resistance strain gauges R11 and R13 are connected in the full-bridge unit, and the inverting input terminal of the amplifier U4 is connected to the end where the resistance strain gauges R10 and R12 are connected in the full-bridge unit. The output terminal of the amplifier U4 is connected to one end of the resistor R8, and the other end of the resistor R8 is connected to the inverting input terminal of the amplifier U5. The in-phase input terminal of the amplifier U5 is connected to one end of the resistor R15, and the other end of the resistor R15 is connected to the signal compensator. The output terminal of the amplifier U5 is connected to one end of the resistor R7, and the other end of the resistor R7 is connected to the inverting input terminal of the amplifier U6, and the in-phase input terminal of the amplifier U6 is grounded.

[0010] Preferably, the strain amplifier unit of the strain gauge-based feedback drive circuit includes capacitors C2 and C3, and also includes resistors R6 and R9, the two ends of the capacitor C3 are respectively connected to the inverting input and output ends of the amplifier U5, the resistor R9 is connected in parallel with the capacitor C3, the two ends of the capacitor C2 are respectively connected to the inverting input and output ends of the amplifier U6, and the resistor R6 is connected in parallel with the capacitor C2.

[0011] The capacitors C2 and C3 in the strain amplifier unit of the strain gauge-based feedback drive circuit of the present invention can block high-frequency noise.

[0012] Preferably, the instrument amplifier unit of the strain gauge-based feedback drive circuit includes an amplifier U7, a non-inverting input terminal of the amplifier U7 is connected to an output terminal of an amplifier U6 in the strain gauge amplifier unit, and an inverting input terminal of the amplifier U7 is connected to a relay.

[0013] Preferably, the high-voltage amplifier unit of the strain gauge-based feedback drive circuit includes an amplifier U8, resistors R14, R16, and R17, one end of the resistor R14 is connected to the output end of the amplifier U7 in the instrument amplifier unit, the other end of the resistor R14 is connected to the inverting input end of the amplifier U8, the non-inverting input end of the amplifier U8 is connected to one end of the resistor R16, the other end of the resistor R16 is grounded, the two ends of the resistor R17 are respectively connected to the non-inverting input end and the output end of the amplifier U8, and the output end of the amplifier U8 is connected to a proportional regulator.

[0014] The feedback drive circuit based on the strain gauge in the present invention has low driving cost, can be integrated with the actuator, and has high stability at low frequency.

[0015] Preferably, the voltage open-loop drive circuit includes an amplifier U3 and a resistor R3, one end of the resistor R3 is connected to a relay, and the other end is connected to the inverting input of the amplifier U3, the non-inverting input of the amplifier U3 is grounded, and the output of the amplifier U3 is connected to a proportional regulator.

[0016] Preferably, the voltage open-loop driving circuit further includes resistors R4 and R5, wherein two ends of the resistor R4 are respectively connected to the inverting input terminal and the output terminal of the amplifier U3, and two ends of the resistor R5 are respectively connected to the offset idle terminal and the output terminal of the amplifier U3.

[0017] The voltage open-loop driving circuit of the present invention is equivalent to a high-voltage amplifier, outputting a high-gain voltage signal to drive the target piezoelectric actuator. The circuit structure is simple and can avoid sensor noise interference.

[0018] Preferably, the charge drive circuit includes amplifiers U1 and U2, a capacitor C1, and resistors R1 and R2, one end of the capacitor C1 is connected to the inverting input of the amplifier U1, the non-inverting input of the amplifier U1 is grounded, the other end of the capacitor C1 is connected to one end of the resistor R1 and to a relay, the other end of the resistor R1 is connected to one end of the resistor R2, the other end of the resistor R2 is connected to the output of the amplifier U1, the end of the resistor R1 connected to the resistor R2 is connected to the reverse input of the amplifier U1, the output of the amplifier U1 is connected to the inverting input of the amplifier U2, the non-inverting input of the amplifier U2 is grounded, and the output of the amplifier U2 is connected to a proportional regulator.

[0019] The resistor R1 and the resistor R2 in the charge driving circuit of the present invention form a DC feedback, which can eliminate the input offset voltage of the operational amplifier saturation, achieve higher linearity when a displacement sensor is not used, and achieve a higher driving frequency.

[0020] Preferably, the charge driving circuit further includes a reference actuator Cf, and two ends of the reference actuator Cf are respectively connected to the inverting input terminal and the output terminal of the amplifier U1.

[0021] Compared with the prior art, the advantages of the present invention are: since the voltage open-loop drive circuit, the charge drive circuit and the feedback drive circuit based on the strain gauge are connected in parallel and a relay is connected to the input end of each branch, the user can use the relay to select the piezoelectric drive mode to be used according to the measurement requirements and the measurement object, that is, the drive circuit of the present invention has the advantages of three drive modes: the voltage open-loop drive structure is simple and is not affected by the sensor noise; the charge drive can also achieve higher linearity and high drive frequency when the displacement sensor is not applicable; the feedback drive based on the strain gauge has high stability at low frequency. Therefore, the present invention can effectively improve the performance of high-voltage electric drive, solve the problem that the existing piezoelectric actuator drive circuit adopts a single drive mode with limitations, and has a wide range of applications. And due to the presence of proportional regulators on the output ends of the three branches, the present invention can achieve the effect of continuous adjustable and hybrid drive of the target piezoelectric driver. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the structure of a piezoelectric actuator precision driving circuit in an embodiment of the present invention;

[0023] Figure 2 is a schematic diagram of a voltage open-loop drive circuit in an embodiment of the present invention;

[0024] Figure 3 is a schematic diagram of a charge driving circuit in an embodiment of the present invention;

[0025] Figure 4 is a schematic diagram of a feedback drive circuit based on a strain gauge in an embodiment of the present invention;

[0026] Figure 5 4 is an overall circuit diagram of a piezoelectric actuator precision driving circuit in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Example

[0029] like Figure 1As shown, this embodiment provides a piezoelectric actuator precision drive circuit, including a voltage open-loop drive circuit, a charge drive circuit and a feedback drive circuit based on a strain gauge. The voltage open-loop drive circuit, the charge drive circuit and the feedback drive circuit based on the strain gauge are connected in parallel, and each branch is connected to a relay at the input end and a proportional regulator at the output end.

[0030] like Figure 2 As shown, the voltage open-loop driving circuit in this embodiment includes a high-power operational amplifier U3, and resistors R3, R4, and R5. One end of the resistor R3 is connected to the signal source, and the other end is connected to the inverting input of the amplifier U3. The non-inverting input of the amplifier U3 is grounded. The two ends of the resistor R4 are respectively connected to the inverting input and output of the amplifier U3. One end of the resistor R5 is connected to the offset idle end of the amplifier U3, and the other end is connected to the output of the amplifier U3. The output of the amplifier U3 is connected to one end of the target piezoelectric actuator CL, and the other end of the target piezoelectric actuator CL is grounded. In this embodiment, the positive power supply terminal and the negative power supply terminal of the amplifier U3 are respectively connected to +400V and -400V power supplies.

[0031] The safe working area of ​​the amplifier U3 in the voltage open-loop driving circuit has no secondary breakdown limitation, and all load types can be observed by selecting a suitable current limiting resistor. The voltage open-loop driving circuit can provide a high-gain output voltage to drive the target piezoelectric actuator CL with voltage, and the voltage gain can be adjusted by adjusting the resistance values ​​of the resistors R3 and R4. It can be seen that the voltage driving method of the present invention has a simple structure, is not interfered by sensor noise, and can be used to test the displacement resolution of the piezoelectric actuator.

[0032] like Figure 3 As shown, in this embodiment, the charge driving circuit includes amplifiers U1 and U2, as well as resistors R1 and R2, capacitor C1 and reference actuator Cf. One end of capacitor C1 is connected to the signal source, and the other end is connected to the inverting input of amplifier U1. The non-inverting input of amplifier U1 is grounded. The output of amplifier U1 is connected to the inverting input of amplifier U2. The non-inverting input of amplifier U2 is grounded. The output of amplifier U2 is connected to one end of target piezoelectric actuator CL, and the other end of target piezoelectric actuator CL is grounded. Resistors R1 and R2 are connected, and the other end of resistor R1 is connected to the signal source. The other end of resistor R2 is connected to the output of amplifier U1. One end of resistor R1 and R2 is connected to the inverting input of amplifier U1. Two ends of reference actuator Cf are connected to the inverting input and output of amplifier U1, respectively. In this embodiment, the positive power supply terminal and negative power supply terminal of amplifier U1 are connected to +15V and -15V power supplies, respectively, and the positive power supply terminal and negative power supply terminal of amplifier U2 are connected to +400V and -400V power supplies, respectively.

[0033] In this embodiment, the reference actuator Cf is made of the same piezoelectric material as the target piezoelectric actuator CL and is driven by a charge control method to generate a voltage containing hysteresis information. Resistors R1 and R2 form a DC feedback to eliminate the input offset voltage that saturates the driving operational amplifier. Amplifier U1 has a very low bias current, and amplifier U2 is used to make the target piezoelectric actuator CL operate under the same electric field strength as the reference actuator Cf.

[0034] Through experiments, it is found that at a frequency of 0.05 to 10 Hz, the displacement hysteresis driven by the output voltage of the charge drive circuit of this embodiment is significantly reduced compared to the linear voltage drive. At 0.05 Hz, 2 Hz, and 10 Hz, the hysteresis is reduced by 85.3%, 90.2%, and 84.0%, respectively. It can be predicted that at higher frequencies, the target displacement will still have good linearity under the drive of the output voltage of the charge drive circuit. Therefore, the charge drive method in the present invention eliminates the hysteresis of the piezoelectric element, and can achieve higher linearity when a displacement sensor is not used, and can also achieve a higher driving frequency.

[0035] like Figure 4 As shown, the feedback drive circuit based on the strain gauge of this embodiment includes a full-bridge unit 1, a strain amplifier unit 2, an instrument amplifier unit 3 and a high-voltage amplifier unit 4, and the four units are connected in sequence. The structure of each unit and the connection relationship between the units are described in detail below:

[0036] The full-bridge unit 1 is used for strain detection, and includes four resistance strain gauges R10, R11, R13, and R12. The above four resistance strain gauges are connected in sequence to form a closed loop, and the four resistance strain gauges are respectively pasted on the four sides of the piezoelectric actuator. Among them, R11 and R13 are oriented along the elongation direction, while R10 and R12 are oriented in the transverse direction. This arrangement can effectively eliminate the influence of temperature changes on resistance and improve sensitivity. One end of the resistance strain gauges R10 and R11 is connected to a 15V power supply, and one end of the resistance strain gauges R12 and R13 is connected to ground.

[0037] The strain amplifier unit 2 includes amplifiers U4, U5, U6, resistors R6, R7, R8, R9, capacitors C2, C3 and a signal compensator. One end of the resistance strain gauge R10 and R12 is connected to the inverting input of the amplifier U4, one end of the resistance strain gauge R11 and R13 is connected to the non-inverting input of the amplifier U4, the output of the amplifier U4 is connected to one end of the resistor R8, the other end of the resistor R8 is connected to the inverting input of the amplifier U5, the non-inverting input of the amplifier U5 is connected to one end of the resistor R15, the other end of the resistor R15 is connected to the signal compensator, the output of the amplifier U5 is connected to one end of the resistor R7, the other end of the resistor R7 is connected to the inverting input of the amplifier U6, the non-inverting input of the amplifier U6 is grounded, the two ends of the capacitor C3 are respectively connected to the inverting input and output of the amplifier U5, the resistor R9 is connected in parallel with the capacitor C3, the two ends of the capacitor C2 are respectively connected to the inverting input and output of the amplifier U6, the resistor R6 is connected in parallel with the capacitor C2, and the capacitors C2 and C3 can block high-frequency noise. In this embodiment, the positive power supply terminal and the negative power supply terminal of the amplifiers U4, U5, and U6 are connected to +15V and -15V power supplies.

[0038] In this embodiment, U4 is an instrument amplifier that integrates a three-op-amp high common-mode rejection amplifier circuit, and the total gain of the strain amplifier unit 2 is set to match the output voltage with the input reference voltage. Since the bridge is not initially balanced, a voltage for offset adjustment is applied to minimize the output offset of the strain amplifier unit 2.

[0039] The instrument amplifier unit 3 is used to generate an error between the feedback signal and the reference input, and includes an amplifier U7. The non-inverting input terminal of the amplifier U7 is connected to the output terminal of the amplifier U6, and the inverting input terminal of the amplifier U7 is connected to the signal source. In this embodiment, the positive power supply terminal and the negative power supply terminal of the amplifier U7 are connected to +15V and -15V power supplies respectively.

[0040] The high-voltage amplifier unit 4 includes an amplifier U8, and resistors R14, R16, and R17. One end of the resistor R14 is connected to the output end of the amplifier U7, and the other end is connected to the inverting input end of the amplifier U8. The non-inverting input end of the amplifier U8 is connected to one end of the resistor R16. The other end of the resistor R16 is grounded, and the two ends of the resistor R17 are respectively connected to the non-inverting input end and the output end of the amplifier U8. The output end of the amplifier U8 is connected to one end of the target piezoelectric actuator CL, and the other end of the target piezoelectric actuator CL is grounded, that is, the feedback drive circuit based on the strain gauge in this embodiment finally outputs a high voltage to drive the target piezoelectric actuator CL through the amplifier U8. In this embodiment, the positive power supply end and the negative power supply end of the amplifier U8 are respectively connected to +400V and -400V power supplies.

[0041] The strain gauge-based feedback drive method of the present invention is low-cost and effective, can be integrated with an actuator, and has high stability at low frequencies.

[0042] like Figure 5 As shown, it is an overall circuit diagram of a piezoelectric actuator precision driving circuit with switchable working modes provided in this embodiment, in which a voltage open-loop driving circuit 6, a charge driving circuit 5 and a feedback driving circuit 7 based on a strain gauge are connected in parallel, and each circuit has a relay at the input end and is connected to a signal source, and has a proportional regulator at the output end and is connected to a target piezoelectric actuator CL, that is, the present invention can realize three piezoelectric driving modes by controlling three relays, so that the driving circuit has the advantages of the three driving modes, and can realize the effect of continuously adjustable hybrid driving by controlling the proportional regulator, thereby realizing precision driving of the target piezoelectric actuator.

[0043] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A piezoelectric actuator precision drive circuit with switchable working modes, characterized in that: It includes a voltage open-loop drive circuit, a charge drive circuit and a feedback drive circuit based on a strain gauge. The voltage open-loop drive circuit, the charge drive circuit and the feedback drive circuit based on the strain gauge are connected in parallel. Each branch is connected to a relay at the input end and a proportional regulator at the output end. The feedback drive circuit based on the strain gauge includes a full-bridge unit, a strain amplifier unit, an instrument amplifier unit and a high-voltage amplifier unit, which are connected in sequence.

2. The piezoelectric actuator precision driving circuit with switchable working modes according to claim 1, characterized in that: The full-bridge unit of the strain gauge-based feedback drive circuit includes resistance strain gauges R10, R11, R13, and R12, which are connected in sequence to form a closed loop, and one end of the resistance strain gauge R10 connected to the resistance strain gauge R11 is connected to a power supply, and one end of the resistance strain gauge R12 connected to the resistance strain gauge R13 is grounded.

3. The piezoelectric actuator precision driving circuit with switchable working modes according to claim 2, characterized in that: The strain amplifier unit of the strain gauge-based feedback drive circuit includes amplifiers U4, U5, and U6, and also includes resistors R7, R8, R15 and a signal compensator. The non-inverting input terminal of the amplifier U4 is connected to the end where the resistance strain gauges R11 and R13 are connected in the full-bridge unit, and the inverting input terminal of the amplifier U4 is connected to the end where the resistance strain gauges R10 and R12 are connected in the full-bridge unit. The output terminal of the amplifier U4 is connected to one end of the resistor R8, and the other end of the resistor R8 is connected to the inverting input terminal of the amplifier U5. The non-inverting input terminal of the amplifier U5 is connected to one end of the resistor R15, and the other end of the resistor R15 is connected to the signal compensator. The output terminal of the amplifier U5 is connected to one end of the resistor R7, and the other end of the resistor R7 is connected to the inverting input terminal of the amplifier U6, and the non-inverting input terminal of the amplifier U6 is grounded.

4. The piezoelectric actuator precision driving circuit with switchable working modes according to claim 3, characterized in that: The strain amplifier unit of the strain gauge-based feedback drive circuit includes capacitors C2 and C3, and also includes resistors R6 and R9. The two ends of the capacitor C3 are respectively connected to the inverting input terminal and the output terminal of the amplifier U5, and the resistor R9 is connected in parallel with the capacitor C3. The two ends of the capacitor C2 are respectively connected to the inverting input terminal and the output terminal of the amplifier U6, and the resistor R6 is connected in parallel with the capacitor C2.

5. The piezoelectric actuator precision driving circuit with switchable working modes according to claim 4, characterized in that: The instrument amplifier unit of the strain gauge-based feedback drive circuit includes an amplifier U7, a non-inverting input terminal of the amplifier U7 is connected to the output terminal of the amplifier U6 in the strain gauge amplifier unit, and an inverting input terminal of the amplifier U7 is connected to a relay.

6. The piezoelectric actuator precision driving circuit with switchable working modes according to claim 5, characterized in that: The high-voltage amplifier unit of the strain gauge-based feedback drive circuit includes an amplifier U8, resistors R14, R16, and R17, one end of the resistor R14 is connected to the output end of the amplifier U7 in the instrument amplifier unit, the other end of the resistor R14 is connected to the inverting input end of the amplifier U8, the non-inverting input end of the amplifier U8 is connected to one end of the resistor R16, the other end of the resistor R16 is grounded, the two ends of the resistor R17 are respectively connected to the non-inverting input end and the output end of the amplifier U8, and the output end of the amplifier U8 is connected to a proportional regulator.

7. The piezoelectric actuator precision driving circuit with switchable working modes according to claim 1, characterized in that: The voltage open-loop driving circuit includes an amplifier U3 and a resistor R3. One end of the resistor R3 is connected to a relay, and the other end is connected to the inverting input of the amplifier U3. The non-inverting input of the amplifier U3 is grounded, and the output of the amplifier U3 is connected to a proportional regulator.

8. The piezoelectric actuator precision driving circuit with switchable working modes according to claim 7, characterized in that: The voltage open-loop driving circuit further includes resistors R4 and R5. The two ends of the resistor R4 are respectively connected to the inverting input terminal and the output terminal of the amplifier U3. The two ends of the resistor R5 are respectively connected to the offset idle terminal and the output terminal of the amplifier U3.

9. The piezoelectric actuator precision driving circuit with switchable working modes according to claim 1, characterized in that: The charge drive circuit includes amplifiers U1 and U2, a capacitor C1, and resistors R1 and R2. One end of the capacitor C1 is connected to the inverting input of the amplifier U1, and the non-inverting input of the amplifier U1 is grounded. The other end of the capacitor C1 is connected to one end of the resistor R1 and to a relay. The other end of the resistor R1 is connected to one end of the resistor R2, and the other end of the resistor R2 is connected to the output of the amplifier U1. The end of the resistor R1 connected to the resistor R2 is connected to the reverse input of the amplifier U1. The output of the amplifier U1 is connected to the inverting input of the amplifier U2, the non-inverting input of the amplifier U2 is grounded, and the output of the amplifier U2 is connected to a proportional regulator.

10. The piezoelectric actuator precision driving circuit with switchable working modes according to claim 9, characterized in that: The charge driving circuit further includes a reference actuator Cf, and two ends of the reference actuator Cf are respectively connected to the inverting input end and the output end of the amplifier U1.

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