A high efficiency piezoelectric energy converter

Abstract

The application relates to the technical field of energy conversion, and discloses a high-efficiency piezoelectric energy converter which comprises a phase control circuit, the phase control circuit comprises a piezoelectric unit made of piezoelectric material, a transformer, an electronic commutation switch, an AND gate and a signal generator, the first electrode and the second electrode of the piezoelectric unit are connected with the first input end and the second input end of the primary inductance of the transformer through the commutation electronic switch, the signal generator is used for outputting a high-frequency signal, the frequency of the high-frequency signal is the same as the inherent frequency of the phase control circuit, the two input ends of the AND gate are respectively connected with the output end of the signal generator and the first electrode of the piezoelectric unit, the output end of the AND gate is connected with the control end of the electronic commutation switch, and the electronic commutation switch is used for controlling the commutation of the electronic commutation switch so that the first electrode and the second electrode of the piezoelectric unit are respectively connected with the first input end and the second input end of the primary inductance of the transformer or are respectively connected with the second input end and the first input end of the primary inductance of the transformer.

Description

Technical Field

[0001] This invention belongs to the field of energy conversion technology, and specifically relates to a high-efficiency piezoelectric energy converter suitable for low-frequency vibration. Background Technology

[0002] Piezoelectric materials are crystalline materials that exhibit a voltage between their two ends when subjected to pressure. They can directly convert wave energy and various vibrational energies into electrical energy. Energy converters that utilize piezoelectric materials to collect vibrational energy and convert it into electrical energy have advantages such as simple structure, low cost, and environmental friendliness, and thus show promising application prospects. However, currently developed piezoelectric energy converters are mainly designed for high-frequency vibrations. For lower-frequency vibrational energy (such as wave energy), the energy conversion efficiency of existing piezoelectric energy converters is generally very low, failing to meet application requirements. Therefore, it is necessary to improve them. Summary of the Invention

[0003] The purpose of this invention is to provide a high-efficiency piezoelectric energy converter suitable for low-frequency vibrations to solve the aforementioned technical problems.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a high-efficiency piezoelectric energy converter, comprising a phase control circuit, the phase control circuit comprising a piezoelectric unit made of piezoelectric material, a transformer, an electronic commutation switch, an AND gate, and a signal generator, the first electrode and the second electrode of the piezoelectric unit being connected to the first and second input terminals of the primary inductance of the transformer via the electronic commutation switch, the signal generator being used to output a high-frequency signal with the same frequency as the inherent frequency of the phase control circuit, the two input terminals of the AND gate being respectively connected to the output terminal of the signal generator and the first electrode of the piezoelectric unit, the output terminal of the AND gate being connected to the control terminal of the electronic commutation switch, for controlling the electronic commutation switch to commutate so that the first electrode and the second electrode of the piezoelectric unit are respectively connected to the first and second input terminals of the primary inductance of the transformer or respectively connected to the second and first input terminals of the primary inductance of the transformer.

[0005] Furthermore, the first electrode of the piezoelectric unit is connected to an electronic commutation switch via a resistor R1, and the node between the resistor R1 and the electronic commutation switch is grounded.

[0006] Furthermore, the piezoelectric unit is a piezoelectric film.

[0007] Furthermore, the piezoelectric unit is made of piezoelectric ceramic or piezoelectric polymer.

[0008] Furthermore, the inductance value of the primary inductor is adjustable.

[0009] Furthermore, the primary-side inductance includes a fixed inductor and an adjustable inductor connected in series.

[0010] Beneficial technical effects of the present invention:

[0011] This invention can greatly improve the piezoelectric conversion efficiency of low-frequency vibration energy, and is particularly suitable for low-frequency vibration energy conversion. Moreover, the circuit structure is simple and easy to implement. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a circuit diagram of a specific embodiment of the present invention;

[0014] Figure 2 This is a circuit diagram of the electronic commutation switch according to a specific embodiment of the present invention;

[0015] Figure 3 This is a circuit diagram of a specific embodiment two of the present invention. Detailed Implementation

[0016] To further illustrate the various embodiments, the present invention provides accompanying drawings. These drawings are part of the disclosure of the present invention, primarily used to illustrate the embodiments and to explain the operating principles of the embodiments in conjunction with the relevant descriptions in the specification. With reference to these drawings, those skilled in the art should be able to understand other possible implementations and the advantages of the present invention. Components in the drawings are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0017] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments.

[0018] Example 1

[0019] like Figure 1 As shown, a high-efficiency piezoelectric energy converter includes a phase control circuit. The phase control circuit includes a piezoelectric unit P1 made of piezoelectric material, a transformer T1, an electronic commutation switch S1, an AND gate A1, and a signal generator C1. The transformer T1 includes a primary inductance L1 and a secondary inductance L2.

[0020] The first and second electrodes of piezoelectric unit P1 are connected to the first and second input terminals of the primary inductance L1 of transformer T1 via electronic commutation switch S1. Specifically, the first electrode of piezoelectric unit P1 is connected in series with resistor R1 to the first input terminal (pin 1) of electronic commutation switch S1, and the node between resistor R1 and the first input terminal of electronic commutation switch S1 is grounded. The second electrode of piezoelectric unit P1 is connected to the second input terminal (pin 3) of electronic commutation switch S1, and the first output terminal (pin 2) of electronic commutation switch S1 is connected to the first input terminal of primary inductance L1. The second output terminal (pin 4) of the piezoelectric unit P1 is connected to the second input terminal of the primary inductor L1. The control terminal (pin 5) of the electronic commutation switch S1 is connected to the output terminal (pin 3) of the AND gate A1. When the output terminal of the AND gate A1 outputs a high level, pins 1 and 2 of the electronic commutation switch S1 are connected, and pins 3 and 4 are connected. When the output terminal of the AND gate A1 outputs a low level, pins 1 and 4 of the electronic commutation switch S1 are connected, and pins 3 and 2 are connected, thereby commutating the first electrode and the second electrode of the piezoelectric unit P1 with the first input terminal and the second input terminal of the primary inductor L1, respectively.

[0021] In this specific embodiment, the electronic commutation switch S1 is composed of four bidirectional thyristors VT1-VT4 and one NOT gate O1, as shown in the specific circuit diagram. Figure 2 As shown, but not limited to this.

[0022] Signal generator C1 is used to output a high-frequency signal (alternating signal), and the frequency of this high-frequency signal is the same as the inherent frequency of the phase control circuit. The two input terminals (pin 2 and pin 1) of AND gate A1 are connected to the output terminal of signal generator C1 and the first electrode of piezoelectric unit P1, respectively. Signal generator C1 can be implemented using Hangchen MAX038CPP high-frequency precision function signal generator, but is not limited to this.

[0023] In this specific embodiment, the piezoelectric unit P1 is a piezoelectric film, and the piezoelectric unit P1 can be made of piezoelectric materials such as piezoelectric ceramics and piezoelectric polymers.

[0024] In practical applications, the output voltage value often cannot be too high. Therefore, in this embodiment, a transformer T1 is used to reduce the output voltage. The two ends O1 and O2 of the secondary inductor L2 of the transformer T1 are used as the output terminals of the high-efficiency piezoelectric energy converter to output electrical energy. The inductance value of the secondary inductor L2 is generally much smaller than that of the primary inductor L1.

[0025] Under vibration load, the piezoelectric unit P1 generates charges on its first and second electrodes. Under vibration load, the charges on the first and second electrodes of the piezoelectric unit P1 also oscillate over time. Therefore, a current is generated in the circuit connected to the primary inductor L1, and the output power of the piezoelectric unit P1 is equal to the product of the voltage across the primary inductor L1 and the current flowing through it. The piezoelectric constant of the piezoelectric unit P1 is generally low, making it very difficult to increase the current. Therefore, this invention obtains a larger output power by increasing the voltage across the primary inductor L1. There are two methods to increase the voltage across the primary inductor L1: (1) increasing the inductance value of the primary inductor L1; (2) increasing the oscillation frequency of the current (voltage). Due to limitations imposed by materials, size, and cost, the inductance value of the primary inductor L1 cannot be increased indefinitely. Therefore, this invention increases the output power by increasing the oscillation frequency of the current (voltage).

[0026] To generate a high-frequency oscillating current (voltage) under low-frequency vibration load, this invention uses a signal generator C1 to generate a high-frequency signal. The high-frequency signal and the piezoelectric signal of the first electrode of the piezoelectric unit P1 are connected to the two input terminals (pin 2 and pin 1) of AND gate A1. The output terminal (pin 3) of AND gate A1 is connected to the control terminal (pin 5) of electronic commutation switch S1. When the voltages of pin 1 and pin 2 of AND gate A1 are both positive (or negative), pin 3 of AND gate A1 outputs a 5V voltage, and pins 1 and 2 of electronic commutation switch S1 are connected, and pins 3 and 4 are connected. When the voltages of pins 1 and 2 of AND gate A1 are not both positive (or negative), pin 3 of AND gate A1 outputs a 0V voltage, and pins 1 and 4 of electronic commutation switch S1 are connected, and pins 3 and 2 are connected, thereby performing commutation input.

[0027] When the frequency of the high-frequency signal generated by signal generator C1 is the same as the natural frequency of the phase control circuit (resonance), the voltage across the primary inductor L1 will eventually have the same phase and frequency as the high-frequency signal generated by signal generator C1. In the resonant state, the piezoelectric unit P1 performs positive work at all times, and its output power reaches its maximum value. The natural frequency of this phase control circuit is related to the area, thickness, and dielectric constant of the primary inductor L1, the secondary inductor L2, and the piezoelectric unit P1. Once the circuit is fabricated, its natural frequency is fixed and can be calculated using theoretical formulas; this is a very mature existing technology and will not be discussed further. Since the natural frequency of this phase control circuit is generally much higher than the frequency of low-frequency vibrations such as wave motion, the low-frequency vibration energy of the piezoelectric unit P1 can be converted into high-frequency oscillation energy of the circuit in the resonant state. This achieves the purpose of increasing the voltage across the primary inductor L1 and the output power, thereby improving the piezoelectric energy conversion effect of low-frequency vibrations. Furthermore, the circuit structure is simple and easy to implement.

[0028] Generally, there will be some error between the natural frequency of the phase control circuit calculated according to the theoretical formula and the actual natural frequency of the phase control circuit. Therefore, the frequency of the high-frequency signal generated by the signal generator C1 can be adjusted near the theoretical value, and the output power of the high-efficiency piezoelectric energy converter can be measured. The frequency corresponding to the maximum output power is the natural frequency of the phase control circuit. Setting this natural frequency as the output frequency of the signal generator C1 can ensure that the high-efficiency piezoelectric energy converter operates in a resonant state after leaving the factory.

[0029] Example 2

[0030] like Figure 3 As shown, the main difference between this embodiment and Embodiment 1 is that in this specific embodiment, the inductance value of the primary inductance L1 of the transformer T1 is adjustable. While ensuring that the output frequency of the signal generator C1 remains constant, adjusting the inductance value of the primary inductance L1 can change the inherent frequency of the phase control circuit, making it have the same frequency as the high-frequency signal generated by the signal generator C1. This achieves resonance between the external vibration load acting on the piezoelectric unit P1 and the phase control circuit, making the manufacturing and use process more flexible and convenient, and further improving energy conversion efficiency.

[0031] In this specific embodiment, the primary inductor L1 includes a fixed inductor L11 and an adjustable inductor L12 connected in series, which is easy to implement, but is not limited to this. In some embodiments, the primary inductor L1 can also be implemented by directly using an adjustable inductor, etc.

[0032] The working principle of this embodiment is the same as that of Embodiment 1. For details, please refer to Embodiment 1, which will not be elaborated here.

[0033] Although the invention has been specifically shown and described in conjunction with preferred embodiments, those skilled in the art should understand that various changes in form and detail may be made to the invention without departing from the spirit and scope of the invention as defined in the appended claims, all of which shall be within the scope of protection of the invention.

Claims

1. A high-efficiency piezoelectric energy converter, characterized in that: The circuit includes a phase control circuit, comprising a piezoelectric element made of piezoelectric material, a transformer, an electronic commutation switch, an AND gate, and a signal generator. The first and second electrodes of the piezoelectric element are connected to the first and second input terminals of the primary inductance of the transformer via the electronic commutation switch. The signal generator outputs a high-frequency signal with the same frequency as the phase control circuit. The two input terminals of the AND gate are connected to the output terminal of the signal generator and the first electrode of the piezoelectric element, respectively. The output terminal of the AND gate is connected to the control terminal of the electronic commutation switch to control the electronic commutation switch. The first and second electrodes of the piezoelectric unit are connected to the first and second input terminals of the primary inductor of the transformer, respectively, or to the second and first input terminals of the primary inductor of the transformer, respectively. When the output of the AND gate is high, pins 1 and 2 of the electronic commutation switch are connected, and pins 3 and 4 are connected. When the output of the AND gate is low, pins 1 and 4 of the electronic commutation switch are connected, and pins 3 and 2 are connected, thereby commutating the first and second electrodes of the piezoelectric unit to the first and second input terminals of the primary inductor, respectively.

2. The high-efficiency piezoelectric energy converter according to claim 1, characterized in that: The first electrode of the piezoelectric unit is connected to an electronic commutation switch via a resistor R1, and the node between the resistor R1 and the electronic commutation switch is grounded.

3. The high-efficiency piezoelectric energy converter according to claim 1, characterized in that: The piezoelectric unit is a piezoelectric film.

4. The high-efficiency piezoelectric energy converter according to claim 3, characterized in that: The piezoelectric unit is made of piezoelectric ceramic or piezoelectric polymer.

5. The high-efficiency piezoelectric energy converter according to claim 1, characterized in that: The inductance value of the primary inductor is adjustable.

6. The high-efficiency piezoelectric energy converter according to claim 5, characterized in that: The primary-side inductance includes a fixed inductor and an adjustable inductor connected in series.

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