A piezoelectric ceramic compensation circuit

Abstract

This utility model discloses a piezoelectric ceramic compensation circuit, comprising: a half-bridge drive circuit, the switching drive input terminal of which is connected to the PWM control signal output terminal of a control chip; a filter circuit, the input terminal of which is connected to the output terminal of the half-bridge drive circuit, and the output terminal of the filter circuit connected to the first input terminal of the piezoelectric ceramic; a temperature detection circuit for acquiring temperature information from the piezoelectric ceramic; a microcontroller connected to the temperature detection circuit for generating a small signal based on the temperature information; a control chip, the signal feedback pin of which is connected to the output terminal of the microcontroller for receiving the small signal; a sampling resistor connected in series in the first loop formed by the signal feedback pin of the control chip and the output terminal of the microcontroller; and a feedback resistor connected in series in the second loop formed by the signal feedback pin of the control chip and the output terminal of the half-bridge drive circuit. The control chip is configured to adjust the duty cycle of the output PWM control signal based on the small signal and the feedback signal from the half-bridge drive circuit.

Description

Technical Field

[0001] This utility model relates to the field of piezoelectric valve control circuit technology, specifically to a piezoelectric ceramic compensation circuit. Background Technology

[0002] A piezoelectric valve is an industrial control valve based on the properties of piezoelectric ceramic materials. It achieves precise regulation of fluids or gases through voltage control and is used in electronics manufacturing for high-precision dispensing and encapsulation. The piezoelectric element is the core component of the piezoelectric valve, typically made of piezoelectric crystal material. When voltage or force is applied to the piezoelectric crystal, it deforms, producing displacement or pressure changes. Based on this piezoelectric effect, the piezoelectric valve can open and close the fluid. The control circuit of the piezoelectric valve is the component used to control the operation of the piezoelectric element. It typically consists of a power supply, a switch, and a circuit board. The control circuit activates and deactivates the piezoelectric element by controlling the switch and adjusting the voltage or force, thereby controlling the opening and closing of the valve.

[0003] The ceramic travel in a piezoelectric valve is affected by temperature. Changes in travel can lead to slight variations in the amount of adhesive, thus impacting the stability of the adhesive volume. Current control methods employ temperature detection to achieve a simple closed-loop control. By reading the ceramic's temperature, the travel is adjusted to compensate for temperature-induced changes. However, this method results in unnecessary travel loss; for example, the ceramic may only utilize 95% or even less of its travel, requiring a sacrifice of some travel for compensation. Utility Model Content

[0004] In view of this, the present invention provides a piezoelectric ceramic compensation circuit to solve the problem that the existing piezoelectric valve control circuit uses closed-loop control based on temperature detection, which requires sacrificing a portion of the ceramic travel, resulting in changes in adhesive volume and unstable dispensing process.

[0005] This utility model embodiment provides a piezoelectric ceramic compensation circuit, including:

[0006] The half-bridge drive circuit has its switch drive input terminal connected to the PWM control signal output terminal of the control chip;

[0007] The filter circuit has its input terminal connected to the output terminal of the half-bridge drive circuit, and its output terminal connected to the first input terminal of the piezoelectric ceramic.

[0008] Temperature detection circuit collects temperature information from piezoelectric ceramic;

[0009] A microcontroller is connected to the temperature detection circuit to generate a small signal based on the temperature information.

[0010] The control chip has a signal feedback pin connected to the output of the microcontroller to receive small signals.

[0011] The sampling resistor is connected in series in the first loop formed by the signal feedback pin of the control chip and the output terminal of the microcontroller.

[0012] The feedback resistor is connected in series in the second loop formed by the signal feedback pin of the control chip and the output of the half-bridge drive circuit.

[0013] The control chip is configured to adjust the duty cycle of the output PWM control signal based on the small signal and the feedback signal from the half-bridge drive circuit.

[0014] Optionally, it also includes:

[0015] A buffer circuit is installed between the control chip and the half-bridge drive circuit. The input of the buffer circuit is connected to the PWM control signal output of the control chip, and the output of the buffer circuit is connected to the switch drive input of the half-bridge drive circuit.

[0016] Optionally, the voltage inputs at both ends of the half-bridge drive circuit are connected to +70V and -70V respectively.

[0017] Optionally, the buffer circuit includes:

[0018] The base of the first transistor Q1 and the base of the second transistor Q2 are connected in parallel to the first PWM signal output terminal of the control chip; the emitter of the first transistor Q1 and the emitter of the second transistor Q2 are connected in series to form the first output terminal of the buffer circuit, which is connected to the first switch drive input terminal of the half-bridge drive circuit.

[0019] The bases of the third transistor Q3 and the fourth transistor Q4 are connected in parallel to the second PWM signal output terminal of the control chip; the emitters of the third transistor Q3 and the fourth transistor Q4 are connected in series to form the second output terminal of the buffer circuit, which is connected to the second switch drive input terminal of the half-bridge drive circuit.

[0020] Optionally, the half-bridge drive circuit includes:

[0021] The first MOSFET Q5 has its gate connected to the first output terminal of the buffer circuit through the first resistor, its source is the output terminal, and its drain is the first voltage input terminal.

[0022] The gate of the second MOSFET Q6 is connected to the second output terminal of the buffer circuit through the second resistor, the source is the output terminal, and the drain is the second voltage input terminal.

[0023] In this circuit, the source of the first MOSFET Q5 is connected in series with the source of the second MOSFET Q6 to form the output terminal of the half-bridge drive circuit.

[0024] Optionally, it also includes:

[0025] The third resistor has one end connected between the first resistor and the gate of the first MOSFET Q5, and the other end connected to the source of the first MOSFET Q5.

[0026] The fourth resistor has one end connected between the second resistor and the gate of the second MOSFET Q6, and the other end connected to the source of the second MOSFET Q6.

[0027] Optionally, the PWM signals output from the first PWM signal output terminal and the second PWM signal output terminal of the control chip are synchronization signals.

[0028] Optionally, the filter circuit includes:

[0029] The first inductor L1 has one end connected to the output of the half-bridge drive circuit.

[0030] The second inductor L2 has one end connected to the other end of the first inductor L1, and the other end of the second inductor L2 is connected to the first input terminal of the piezoelectric ceramic.

[0031] The first capacitor has one end connected between the first inductor L1 and the second inductor L2;

[0032] The fifth resistor has one end connected to the other end of the first capacitor, and the other end of the fifth resistor is grounded.

[0033] Optionally, the second input terminal of the piezoelectric ceramic is connected to a +48V voltage.

[0034] The beneficial effects of this utility model are:

[0035] This utility model embodiment provides a piezoelectric ceramic compensation circuit, which adopts dual piezoelectric control technology to provide a wider range of voltage input control for the piezoelectric ceramic to adapt to the piezoelectric ceramic stroke under different temperature conditions. Compared with the existing temperature closed-loop control scheme, it does not require a 5% reserve for piezoelectric ceramic stroke compensation. Instead, it addresses the characteristic of piezoelectric ceramic elongation changing under different temperature conditions by using a wider range of voltage input to correspond to different piezoelectric ceramic strokes. It compensates for this change in piezoelectric ceramic elongation according to temperature, resulting in better repeatability. This can significantly improve the control accuracy of the piezoelectric valve by reducing the impact of temperature changes, thereby improving the accuracy of the piezoelectric valve. Attached Figure Description

[0036] The features and advantages of this utility model will be more clearly understood by referring to the accompanying drawings. The drawings are schematic and should not be construed as limiting the utility model in any way. In the drawings:

[0037] Figure 1 A structural block diagram of a piezoelectric ceramic compensation circuit according to an embodiment of the present invention is shown;

[0038] Figure 2 A schematic diagram of a piezoelectric ceramic compensation circuit according to an embodiment of the present invention is shown;

[0039] Figure 3 A partial schematic diagram of the buffer circuit and half-bridge drive circuit of a piezoelectric ceramic compensation circuit according to an embodiment of the present invention is shown.

[0040] Figure 4 A partial schematic diagram of the feedback circuit of a piezoelectric ceramic compensation circuit according to an embodiment of the present invention is shown;

[0041] Figure 5 A schematic diagram of a piezoelectric ceramic compensation circuit according to an embodiment of the present invention is shown;

[0042] Figure 6 A circuit diagram of a piezoelectric ceramic temperature detection circuit according to an embodiment of the present invention is shown. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0044] like Figure 1 As shown, this embodiment of the invention provides a piezoelectric ceramic compensation circuit, including a half-bridge drive circuit, a filter circuit, a temperature detection circuit, a microcontroller, a control chip, a sampling resistor, and a feedback resistor. The switching input terminal of the half-bridge drive circuit is connected to the PWM control signal output terminal of the control chip. The input terminal of the filter circuit is connected to the output terminal of the half-bridge drive circuit, and the output terminal of the filter circuit is connected to the first input terminal of the piezoelectric ceramic. The temperature detection circuit collects temperature information from the piezoelectric ceramic. The microcontroller is connected to the temperature detection circuit and generates a small signal based on the temperature information. The signal feedback pin of the control chip is connected to the output terminal of the microcontroller to receive the small signal. The sampling resistor is connected in series in the first loop formed by the signal feedback pin of the control chip and the output terminal of the microcontroller. The feedback resistor is connected in series in the second loop formed by the signal feedback pin of the control chip and the output terminal of the half-bridge drive circuit. The control chip is configured to adjust the duty cycle of the output PWM control signal based on the small signal and the feedback signal from the half-bridge drive circuit.

[0045] like Figure 2As shown, the piezoelectric ceramic compensation circuit provided in this embodiment also includes a buffer circuit between the control chip and the half-bridge drive circuit. The input terminal of the buffer circuit is connected to the PWM control signal output terminal of the control chip, and the output terminal of the buffer circuit is connected to the switch drive input terminal of the half-bridge drive circuit. The buffer circuit is directly driven by the PWM signal output by the control chip, while the half-bridge drive circuit achieves switch drive through the switch signal output by the buffer circuit. The switch signal output by the buffer circuit is consistent with the PWM signal wave output by the control chip, and the function of the buffer circuit is to buffer and protect the half-bridge drive circuit. In a specific embodiment, the PWM signals output by the first PWM signal output terminal and the second PWM signal output terminal of the control chip are synchronization signals.

[0046] As an optional implementation, the voltage inputs at both ends of the half-bridge drive circuit are connected to +70V and -70V respectively.

[0047] like Figure 2 As shown, the two ends of the half-bridge drive circuit are connected to +70V and -70V respectively. The switching part of the half-bridge drive circuit is driven and controlled by the PWM modulation wave output by the buffer circuit at the front end. The final output voltage of the half-bridge drive circuit is affected by the +70V and -70V voltages at both ends. Combined with different duty cycles of the PWM modulation wave, it can output voltages from -20V to 120V.

[0048] In a specific implementation, the first input terminal of the piezoelectric ceramic is connected to the output terminal of the half-bridge drive circuit, and the second input terminal is connected to a +48V voltage. Dual piezoelectric control technology is employed to provide a wider range of voltage input control for the piezoelectric ceramic, adapting to different temperature conditions and piezoelectric ceramic stroke. Compared to existing temperature closed-loop control schemes, there is no need to reserve 5% for piezoelectric ceramic stroke compensation. Instead, addressing the characteristic of varying piezoelectric ceramic elongation under different temperature conditions, the compensation circuit provided in this implementation uses a wider range of voltage inputs to correspond to different piezoelectric ceramic strokes. This temperature-based compensation offsets the variation in piezoelectric ceramic elongation, resulting in better repeatability and significantly improving the control accuracy of the piezoelectric valve by reducing the impact of temperature changes.

[0049] like Figure 3As shown, the buffer circuit includes a first transistor Q1, a second transistor Q2, a third transistor Q3, and a fourth transistor Q4. The bases of the first transistor Q1 and the second transistor Q2 are connected in parallel to the first PWM signal output terminal of the control chip. The emitters of the first transistor Q1 and the second transistor Q2 are connected in series to form the first output terminal of the buffer circuit, which is connected to the first switch drive input terminal of the half-bridge drive circuit. The bases of the third transistor Q3 and the fourth transistor Q4 are connected in parallel to the second PWM signal output terminal of the control chip. The emitters of the third transistor Q3 and the fourth transistor Q4 are connected in series to form the second output terminal of the buffer circuit, which is connected to the second switch drive input terminal of the half-bridge drive circuit. The half-bridge drive circuit includes a first MOSFET Q5 and a second MOSFET Q6. The gate of the first MOSFET Q5 is connected to the first output terminal of the buffer circuit through a first resistor R21, its source is the output terminal, and its drain is the first voltage input terminal. The gate of the second MOSFET Q6 is connected to the second output terminal of the buffer circuit through the second resistor R22, its source is the output terminal, and its drain is the second voltage input terminal. The source of the first MOSFET Q5 and the source of the second MOSFET Q6 are connected in series to form the output terminal of the half-bridge drive circuit.

[0050] like Figure 3 As shown, the half-bridge drive circuit also includes:

[0051] The third resistor R23 has one end connected between the first resistor and the gate of the first MOSFET Q5, and the other end connected to the source of the first MOSFET Q5.

[0052] The fourth resistor R24 ​​has one end connected between the gate of the second resistor and the second MOSFET Q6, and the other end connected to the source of the second MOSFET Q6.

[0053] Taking the two resistors R21 and R23 related to the first MOSFET Q5 as an example, resistor R21 is a 13Ω resistor, which is used to increase the drive damping. Resistor R23 is a 10KΩ resistor to prevent floating at this point.

[0054] like Figure 4As shown, the signal feedback pin of the control chip receives two signals: a small signal from the microcontroller, input to the control chip via sampling resistor R3, and a feedback signal from the half-bridge drive circuit, input to the control chip via two feedback resistors R11 and R13. It should be noted that the microcontroller receives the temperature acquisition signal from the piezoelectric ceramic, processes it, and combines it with the piezoelectric ceramic's travel conditions at different temperatures to obtain a small signal. This small signal is input to the control chip, resulting in different PWM modulation signal waves. Through the related circuit of the sampling resistor and feedback resistor, the signal is amplified, with an amplification factor of Vout / Vin = (R11 + R13) / R3. Specifically, by connecting external +70V and -70V voltages to both ends of the half-bridge drive circuit, a wide voltage amplitude range is provided, and the range of the piezoelectric ceramic input voltage is expanded through a linear amplifier.

[0055] The on-resistance of Q5 and Q6 can be used to detect the current in the circuit, thereby realizing the overcurrent protection of the ceramic circuit.

[0056] like Figure 5 As shown, the filter circuit includes a first inductor L1, a second inductor L2, a first capacitor C18, and a fifth resistor R28. One end of the first inductor L1 is connected to the output terminal of the half-bridge drive circuit; one end of the second inductor L2 is connected to the other end of the first inductor L1, and the other end of the second inductor L2 is connected to the first input terminal of the piezoelectric ceramic; one end of the first capacitor C18 is connected between the first inductor L1 and the second inductor L2; one end of the fifth resistor R28 is connected to the other end of the first capacitor, and the other end of the fifth resistor is grounded. In a specific embodiment, the fifth resistor R28 is a 0Ω resistor.

[0057] The control signal output from the half-bridge drive circuit is sent to the LC filter circuit. After second-order filtering, the DC component in the signal is removed, ultimately amplifying the signal. The LC filter circuit then restores the PWM signal to an analog signal, which ultimately drives the ceramic element.

[0058] like Figure 6 As shown, the ADC interface is connected to an NTC resistor. Through voltage division in series with resistor R11, the signal is transmitted to the MCU (microcontroller) for AD sampling to obtain the temperature detection signal. Capacitor C9 is used to filter out some noise interference, resistor R17 is used to increase a certain damping, and diode D3 is used to protect the sampling pin voltage from being too high.

[0059] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A piezoelectric ceramic compensation circuit, characterized by, include: The half-bridge drive circuit has its switch drive input terminal connected to the PWM control signal output terminal of the control chip; A filter circuit, the input of which is connected to the output of the half-bridge drive circuit, and the output of the filter circuit is connected to the first input of the piezoelectric ceramic. The temperature detection circuit collects temperature information from the piezoelectric ceramic. A microcontroller is connected to the temperature detection circuit and generates a small signal based on the temperature information. The control chip has a signal feedback pin connected to the output terminal of the microcontroller to receive the small signal. A sampling resistor is connected in series in the first loop formed by the signal feedback pin of the control chip and the output terminal of the microcontroller. A feedback resistor is connected in series in the second loop formed by the signal feedback pin of the control chip and the output terminal of the half-bridge drive circuit. The control chip is configured to adjust the duty cycle of the output PWM control signal based on the small signal and the feedback signal from the half-bridge drive circuit.

2. The piezoelectric ceramic compensation circuit according to claim 1, characterized in that, Also includes: A buffer circuit is disposed between the control chip and the half-bridge drive circuit, wherein the input terminal of the buffer circuit is connected to the PWM control signal output terminal of the control chip, and the output terminal of the buffer circuit is connected to the switch drive input terminal of the half-bridge drive circuit.

3. The piezoelectric ceramic compensation circuit according to claim 1, characterized in that, The voltage inputs at both ends of the half-bridge drive circuit are connected to +70V and -70V respectively.

4. The piezoelectric ceramic compensation circuit according to claim 2, characterized in that, The buffer circuit includes: The base of the first transistor Q1 and the base of the second transistor Q2 are connected in parallel to the first PWM signal output terminal of the control chip; the emitter of the first transistor Q1 and the emitter of the second transistor Q2 are connected in series to form the first output terminal of the buffer circuit, which is connected to the first switch drive input terminal of the half-bridge drive circuit. The bases of the third transistor Q3 and the fourth transistor Q4 are connected in parallel to the second PWM signal output terminal of the control chip; the emitters of the third transistor Q3 and the fourth transistor Q4 are connected in series to form the second output terminal of the buffer circuit, which is connected to the second switch drive input terminal of the half-bridge drive circuit.

5. The piezoelectric ceramic compensation circuit according to claim 4, characterized in that, The half-bridge drive circuit includes: The first MOSFET Q5 has its gate connected to the first output terminal of the buffer circuit through a first resistor, its source is the output terminal, and its drain is the first voltage input terminal. The second MOSFET Q6 has its gate connected to the second output terminal of the buffer circuit through a second resistor, its source is the output terminal, and its drain is the second voltage input terminal. The source of the first MOSFET Q5 is connected in series with the source of the second MOSFET Q6 to form the output terminal of the half-bridge drive circuit.

6. The piezoelectric ceramic compensation circuit according to claim 5, characterized in that, Also includes: The third resistor has one end connected between the first resistor and the gate of the first MOS transistor Q5, and the other end of the third resistor is connected to the source of the first MOS transistor Q5. A fourth resistor has one end connected between the second resistor and the gate of the second MOS transistor Q6, and the other end of the fourth resistor is connected to the source of the second MOS transistor Q6.

7. The piezoelectric ceramic compensation circuit according to claim 4, characterized in that, The PWM signals output from the first PWM signal output terminal and the second PWM signal output terminal of the control chip are synchronization signals.

8. The piezoelectric ceramic compensation circuit according to claim 1, characterized in that, The filtering circuit includes: The first inductor L1 has one end connected to the output terminal of the half-bridge drive circuit; The second inductor L2 has one end connected to the other end of the first inductor L1, and the other end of the second inductor L2 is connected to the first input terminal of the piezoelectric ceramic. The first capacitor has one end connected between the first inductor L1 and the second inductor L2; The fifth resistor has one end connected to the other end of the first capacitor, and the other end of the fifth resistor is grounded.

9. The electro-ceramic compensation circuit according to claim 1, characterized in that, The second input terminal of the piezoelectric ceramic is connected to a +48V voltage.

Images