CN102801203A - Piezoelectric power-generation charger - Google Patents

Abstract

The invention discloses a piezoelectric power generation charger, which is mainly composed of a piezoelectric power generation body, a rectification and voltage stabilization circuit, a voltage boosting circuit, an automatic polarity discrimination and charging circuit, and an energy storage rechargeable battery. The piezoelectric generator includes a movable column, a fixed wall, a piezoelectric ceramic sheet and a return spring. The input end of the rectification and voltage stabilization circuit is connected to the power output end of the piezoelectric generator, and the output end of the rectification and voltage stabilization circuit is connected to the input end of the energy storage rechargeable battery; the output end of the energy storage rechargeable battery passes through the boost circuit and automatic polarity Discrimination and charging circuit is connected. The invention has the characteristics of simple structure and energy saving.

Description

Piezoelectric generator charger

technical field

The invention relates to a charger, in particular to a piezoelectric generator charger.

Background technique

A charger is a device that converts alternating current to low voltage direct current. Chargers are widely used in various fields, especially in the field of life, they are widely used in common electrical appliances such as mobile phones and cameras. The traditional charger is a static converter device that uses power electronic semiconductor devices to convert the alternating current of the mains with a fixed voltage and frequency into direct current. Although the power consumption required by the charger is less, it is still a considerable expense to use the mains as the power supply for a long time.

We all know that stress is everywhere, and stress is also a kind of energy. If these energies that we ignore unconsciously can be collected and converted into electrical energy for use, it will be a supplement to the increasingly scarce energy in human society. If a pressure is applied to a piezoelectric material, it produces a potential difference (called the direct piezoelectric effect), whereas if a voltage is applied, a mechanical stress occurs (called the inverse piezoelectric effect). Piezoelectric ceramics have the function of conversion and inverse conversion between mechanical energy and electrical energy. The advantages of piezoelectric ceramic power generation devices are simple structure, no pollution, high energy density, and easy processing. Piezoelectric ceramic transducers can be made into power supply energy for various electronic equipment through certain processing techniques, which can make electronic equipment adapt to the environment for self-power supply, and improve the maintenance-free nature of the equipment. Based on these considerations, we propose a charger based on pressure power generation. It converts pressure into electrical energy and stores it for charging peripherals.

Contents of the invention

The technical problem to be solved by the present invention is to provide a piezoelectric generator charger, which has the characteristics of simple structure and energy saving.

In order to solve the above problems, a piezoelectric generator charger designed by the present invention is mainly composed of a piezoelectric generator, a rectification and voltage stabilization circuit, a boost circuit, an automatic polarity discrimination and charging circuit, and an energy storage rechargeable battery. . The above-mentioned piezoelectric generator includes a movable column, a fixed wall, a piezoelectric ceramic sheet and a return spring; wherein the fixed wall is a hollow cylindrical wall, and the elongated movable column runs through the middle of the cylindrical wall, and the movable group The axis coincides with the axis of the cylindrical wall. One end of the movable column is the force application end, and the other end is fixed with a return spring. One end of the spring is connected to the movable column, and the other end is connected to the bottom surface of the cylindrical wall. Multiple piezoelectric ceramics The slices take the movable column as the center, the radial direction of the fixed wall is the extension direction, and are radially distributed inside the fixed wall. Each piezoelectric ceramic slice is horizontally arranged inside the cylindrical wall, and one end of the piezoelectric slice is fixed on the movable The outer wall of the column and the other end are fixed on the inner wall of the movable wall; the output electrodes of multiple piezoelectric ceramic sheets are connected in parallel to form the power output end of the piezoelectric generator. The input end of the rectification and voltage stabilization circuit is connected to the power output end of the piezoelectric generator, and the output end of the rectification and voltage stabilization circuit is connected to the input end of the energy storage rechargeable battery; the output end of the energy storage rechargeable battery passes through the boost circuit and automatic polarity Discrimination and charging circuit is connected.

In the above scheme, the piezoelectric ceramic sheet is preferably composed of 2 piezoelectric crystal sheets and a metal gasket, and the 2 piezoelectric crystal sheets are respectively glued on the upper and lower sides of the metal gasket; the poles of the 2 piezoelectric crystal sheets The polarization direction is the same, that is, they are all polarized along the direction perpendicular to the plane of the metal gasket; two piezoelectric crystal sheets are shorted to form one of the output electrodes of the piezoelectric ceramic sheet, and the metal gasket is used to form the other of the piezoelectric ceramic sheet output electrode.

In the above solution, preferably, the two ends of the piezoelectric ceramic sheet are respectively connected to the outer side wall of the movable column and the inner side wall of the movable wall through fixing fixtures.

In the above scheme, the piezoelectric generator charger preferably further includes a double-throw switch, an analog-to-digital conversion circuit, a controller, and a liquid crystal display; The input end of the circuit is connected, and the other end of the double-throw switch is connected with the controller; the output end of the analog-to-digital conversion circuit is connected with the input end of the controller, and the output end of the controller is connected with the liquid crystal display.

Compared with the prior art, the present invention utilizes piezoelectric ceramics to design and manufacture a piezoelectric generator, and converts the pressure of feet or other pressures into electrical energy through the piezoelectric ceramics and stores them. Utilizing the characteristics and principle of the positive piezoelectric effect of piezoelectric ceramics, the piezoelectric ceramics will generate electric energy through the positive piezoelectric effect. By selecting the appropriate piezoelectric sheet, and designing the piezoelectric mode and connection method of the piezoelectric ceramic sheet. The piezoelectric method adopts the electrode parallel connection piezoelectric sheet cantilever beam power generation structure, the connected piezoelectric ceramic sheet, through filtering, rectification, and voltage stabilization, the energy is temporarily stored in the energy storage rechargeable battery, and then through the DC-DC boost circuit and charging The circuit output is charged to the outside. In addition, if you want to check the charging status during the charging process, close the switch and connect the auxiliary circuit, and control the A/D module to collect the voltage signal through the controller, and display it on the LCD.

Description of drawings

Figure 1 is a circuit schematic diagram of a piezoelectric generator charger.

Fig. 2 is a schematic diagram of the structure of the piezoelectric generator.

Fig. 3 is a schematic diagram of the structure of the piezoelectric ceramic sheet.

Figure 4 is a schematic diagram of the rectification and voltage stabilization circuit.

Figure 5 is a schematic diagram of the boost circuit.

Figure 6 is a schematic diagram of the automatic polarity discrimination and charging circuit.

Marked in the figure: 1. Movable column; 2. Fixed wall; 3. Piezoelectric ceramic sheet; 4. Return spring; 5. Fixing fixture.

Detailed ways

Referring to Figure 1, a piezoelectric generator charger is mainly composed of a piezoelectric generator, a rectification and voltage stabilization circuit, a boost circuit, an automatic polarity discrimination and charging circuit, an energy storage rechargeable battery, a double-throw switch, an analog-to-digital conversion circuit, Consists of a controller and a liquid crystal display.

The piezoelectric generator can convert external pressure into electrical energy, and its structure is shown in Figure 2. In this embodiment, the piezoelectric generator is mainly composed of a movable column 1 , a fixed wall 2 , a piezoelectric ceramic sheet 3 and a return spring 4 . Wherein the fixed wall 2 is a hollow cylindrical wall, and the strip-shaped movable column 1 runs through the middle part of the cylindrical wall, and the axis of the movable group coincides with the axis of the cylindrical wall, and one end of the movable column 1 is the force application end, The other end is fixed with a return spring 4, one end of the spring is connected to the movable column 1, and the other end is connected to the bottom surface of the cylindrical wall. A plurality of piezoelectric ceramic sheets 3 are centered on the movable column 1, and the radial direction of the fixed wall 2 is The direction of extension is radially distributed inside the fixed wall 2, and each piezoelectric ceramic sheet 3 is horizontally arranged inside the cylindrical wall, and one end of the piezoelectric sheet is fixed on the outer wall of the movable column 1, and the other end is fixed on the outer wall of the movable column 1. It is fixed on the inner side wall of the movable wall; the output electrodes of multiple piezoelectric ceramic sheets 3 are connected in parallel to form the power output end of the piezoelectric generator. In order to better fix the piezoelectric ceramic sheet 3 , the two ends of the piezoelectric ceramic sheet 3 are also connected to the outer sidewall and the inner sidewall of the movable column 1 through fixing fixtures 5 . When generating electricity, a downward force is applied to the movable column 1 . After release, due to the return spring 4, the movable column 1 will vibrate up and down in the inner cavity of the fixed wall 2 for a period of time. At this time, the end of the piezoelectric ceramic sheet 3 fixed on the movable column 1 will vibrate with the movable column 1, while the end fixed on the fixed wall 2 will not move, so the piezoelectric ceramic sheet 3 will continue to generate electricity for a period of time. Time, no need to apply pressure all the time, thus greatly improving the efficiency of power generation.

Above-mentioned piezoelectric ceramic sheet 3 can adopt the known piezoelectric ceramic sheet 3 of prior art, and in the present embodiment, described piezoelectric ceramic sheet 3 structure is as shown in Figure 3, promptly piezoelectric ceramic sheet 3 is pressed by 2 pieces Composed of a transistor sheet and a metal gasket, two piezoelectric crystal sheets are glued on the upper and lower sides of the metal gasket; the polarization directions of the two piezoelectric crystal sheets are the same, that is, they are all along the direction perpendicular to the plane of the metal gasket. Polarization (the direction shown by x in the figure); two piezoelectric crystal sheets are shorted to each other to form one of the output electrodes of the piezoelectric ceramic sheet 3, and the metal gasket is used to form the other output electrode of the piezoelectric ceramic sheet 3. The piezoelectric crystal sheet used in this embodiment is PZT ceramics, raw material: PbZrxTi{1-x}O3 lead zirconate titanate.

Let the length of the beam be L, the width be a, the thickness of the metal shim be t _sh , and the thickness of the wafer be t _c . The deflection in the x direction caused by external force is h=Hsinwt.

Output current:

①

①

The output voltage:

②

②

Output Power:

$P=\frac{{9a}^2{(t_c+t_{\mathrm{sh}})}^2{d}_{31}^2{\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="HDA00002092053300021.png,HDA00002092053300033.png"\; state="\{\{state\}\}">h</figure-callout>}}^2\mathrm{\&omega;}{t}_C^{2}R}{8{\left({\mathrm{the\; s}}_{11}^{\mathrm{E.}}\right)}^2{l}^2\{{\mathrm{<figure-callout\; id="2"\; label="t\; c"\; filenames="HDA00002092053300021.png,HDA00002092053300033.png"\; state="\{\{state\}\}">t</figure-callout>}}_c^{}+{4a}^2{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="HDA00002092053300021.png,HDA00002092053300033.png"\; state="\{\{state\}\}">l</figure-callout>}}^2{\mathrm{\&omega;}}^2{R}^2[{\stackrel{\&OverBar;}{{\mathrm{\&epsiv;}}_{33}}}^2+{\left({\mathrm{\&epsiv;}}_{33}^T\right)}^2\left]\right\}}$ ③

Maximum power:

$p_{\mathrm{MAX}}=\frac{9w(t_c+t_{\mathrm{sh}})d_{31}^2{\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="HDA00002092053300021.png,HDA00002092053300033.png"\; state="\{\{state\}\}">h</figure-callout>}}^2\mathrm{\&omega;}{t}_c}{32{\left({\mathrm{the\; s}}_{11}^{\mathrm{E.}}\right)}^2{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="HDA00002092053300021.png,HDA00002092053300033.png"\; state="\{\{state\}\}">l</figure-callout>}}^2\sqrt{{\stackrel{\&OverBar;}{{\mathrm{\&epsiv;}}_{33}}}^2+{\left({\mathrm{\&epsiv;}}_{33}^T\right)}^2}}$ ④

Ideal load:

$R_{\mathrm{OPT}}=\frac{{\mathrm{<figure-callout\; id="2"\; label="t\; c"\; filenames="HDA00002092053300021.png,HDA00002092053300033.png"\; state="\{\{state\}\}">t</figure-callout>}}_c}{2\mathrm{al\&omega;}\sqrt{{\stackrel{\&OverBar;}{{\mathrm{\&epsiv;}}_{33}}}^2+{\left({\mathrm{\&epsiv;}}_{33}^T\right)}^2}}$ ⑤

Piezoelectric ceramics generate signals by bending piezoelectric sheets, and quickly bend to a certain angle and then quickly return to the original state, and use the piezoelectric generators in parallel to increase the output current.

Since the power emitted by the piezoelectric generator is small, when many peripheral circuits are added, these circuit components have all consumed the generated electric energy, making the efficiency of collecting electric energy too low, so the power consumption of other components of the circuit should be reduced as much as possible. In this embodiment, the input end of the rectification and voltage stabilization circuit is connected to the power output end of the piezoelectric generator, and the output end of the rectification and voltage stabilization circuit is connected to the input end of the energy storage rechargeable battery; The pressure circuit is connected with the automatic polarity discrimination and charging circuit. The output end of the energy storage rechargeable battery is connected to the input end of the analog-to-digital conversion circuit through one end of the double-throw switch, and the other end of the double-throw switch is connected to the controller; the output end of the analog-to-digital conversion circuit is connected to the input of the controller Terminal, the output terminal of the controller is connected with the liquid crystal display. Piezoelectric generating body, rectification and voltage stabilizing circuit, boosting circuit, automatic polarity discrimination and charging circuit, energy storage rechargeable battery constitute the core circuit of this charger, in order to realize the main purpose of the present invention. Double-throw switch, analog-to-digital conversion circuit, controller and liquid crystal display constitute the auxiliary circuit of the charger. In order to save energy consumption, the auxiliary circuit can be selectively connected to the core circuit. That is, when the user needs to save energy, the double-throw switch is turned off to cut off the auxiliary circuit; and when the user needs to check the charging status, the double-throw switch is closed to connect the auxiliary circuit. The working process of the present invention is: 1. the core circuit part of the charging circuit: first, the piezoelectric ceramic generating sheet generates an electric signal through a rectifier circuit, a filter capacitor, and a voltage stabilizing circuit to charge the nickel-cadmium rechargeable battery; 2. the auxiliary circuit part of the charging circuit: The A/D module and the LCD module are controlled by the controller, and the A/D module measures the battery voltage, which indicates the current battery power through the voltage, and is displayed by the controller through the LCD module. ③The core circuit part and the auxiliary circuit part are controlled by a double-throw switch. If you want to charge quickly, you don't need to connect the auxiliary circuit part. If you want to check the status, you can connect the auxiliary circuit part.

In this embodiment, the rectification and voltage stabilization circuit is shown in Figure 4. It uses bridge rectification, filter capacitor filtering, voltage regulator tube to stabilize the voltage, and directly charges the rechargeable battery. It uses few devices, and the circuit has almost no power consumption. The electrical energy generated by the generator sheet is largely absorbed by the battery. The bridge rectifier circuit transforms the AC signal of the piezoelectric film into a DC signal, and the frequency of the signal of the bridge rectifier circuit increases and decreases according to the vibration speed of the movable column 1. After passing the signal through the filter capacitor and the voltage regulator tube, Charge the energy storage rechargeable battery directly. The nickel-cadmium rechargeable battery selected for the energy storage rechargeable battery is charged. The battery has strong overcharge resistance, large capacity, small internal resistance, and large output current.

In this embodiment, the voltage boosting circuit is shown in FIG. 5 , which boosts the voltage of the energy storage rechargeable battery. The boost circuit DC/DC converter used is a monolithic bipolar linear integrated circuit. On-chip includes a temperature compensated bandgap reference, a duty cycle controlled oscillator, drivers and high current output switches capable of outputting 1.5A switching current. It can form a switching boost converter, a buck converter and a power inverter with a minimum of external components. It can work under the input voltage of 3.0-40V, the short-circuit current is limited, the quiescent current is low, the output switch current can reach 1.5A without external triode, and the output voltage is adjustable. Its output voltage value is also adjusted by changing the resistance values of R4 and R5, and its output voltage conforms to the following formula: Vout=(1+R4/R5)×1.25V.

In this embodiment, the automatic polarity discrimination and charging circuit is shown in Figure 6. This circuit has functions such as battery detection, battery no-load voltage regulation output, normal charging and saturation detection, and short circuit protection. The corresponding status is displayed via DS1, DS2, DS3. When the battery is connected when the power is disconnected, the automatic polarity identification and charging circuit chip will control the external battery to be charged through the automatic "polarity identification" system, so that the battery detection indicators DS1, DS2 and DS3 display different state. When the power supply is connected but not connected to the external battery to be charged, the voltage difference between the two ends of the charger is a typical value of 4.25V, and the indicator lights DS1, DS2 and DS3 display different states. When the power supply is connected and the battery is not fully charged, the power supply starts to charge the battery normally through the control of the charging circuit chip. As mentioned above, no matter what polarity the battery is connected to the circuit, it can be charged normally. Slowly increase, when the battery voltage rises to a typical value of 4.25V, the charging process ends and the battery is saturated. Indicator lights DS1, DS2 and DS3 show different states. If the battery is short-circuited after the power is connected, the automatic polarity discrimination and the "short-circuit protection" system inside the charging circuit chip will automatically cut off the charging circuit to avoid large current. Indicator lights DS1, DS2 and DS3 show different states.

Claims (5)

1. A piezoelectric generator charger, characterized in that it is mainly composed of a piezoelectric generator, a rectification and voltage stabilization circuit, a boost circuit, an automatic polarity discrimination and charging circuit, and an energy storage rechargeable battery; The above-mentioned piezoelectric generator includes a movable column (1), a fixed wall (2), a piezoelectric ceramic sheet (3) and a return spring (4); the fixed wall (2) is a hollow cylindrical wall with a long strip The movable column (1) runs through the middle of the cylindrical wall, and the axis of the movable group coincides with the axis of the cylindrical wall. One end of the movable column (1) is the force application end, and the other end is fixed with a return spring (4). , one end of the above-mentioned spring is connected to the movable column (1), and the other end is connected to the bottom surface of the cylindrical wall. A plurality of piezoelectric ceramic sheets (3) center on the movable column (1) and extend in the radial direction of the fixed wall (2). direction, distributed radially inside the fixed wall (2), each piezoelectric ceramic sheet (3) is horizontally arranged inside the cylindrical wall, and one end of the piezoelectric sheet is fixed on the outer wall of the movable column (1) The upper end and the other end are fixed on the inner side wall of the movable wall; the output electrodes of multiple piezoelectric ceramic sheets (3) are connected in parallel to form the power output end of the piezoelectric generator; The input end of the rectification and voltage stabilization circuit is connected to the power output end of the piezoelectric generator, and the output end of the rectification and voltage stabilization circuit is connected to the input end of the energy storage rechargeable battery; the output end of the energy storage rechargeable battery passes through the boost circuit and automatic polarity Discrimination and charging circuit is connected. 2. The piezoelectric generator charger according to claim 1, characterized in that: the piezoelectric ceramic sheet (3) is composed of two piezoelectric crystal sheets and metal gaskets, and the two piezoelectric crystal sheets are respectively glued to the metal gasket. On the upper and lower sides of the gasket; the polarization directions of the two piezoelectric crystal sheets are the same, that is, they are all polarized along the direction perpendicular to the plane of the metal gasket; the two piezoelectric crystal sheets are short-circuited to form a piezoelectric ceramic sheet (3 ) of one of the output electrodes and the metal pad as the other output electrode of the piezoelectric ceramic sheet (3). 3. The piezoelectric generator charger according to claim 1, characterized in that: the two ends of the piezoelectric ceramic sheet (3) pass through the fixing fixture (5) and the outer wall of the movable column (1) and the inner side of the movable wall respectively The walls are connected. 4. The piezoelectric generator charger according to any one of claims 1 to 3, characterized in that: it further comprises a double-throw switch, an analog-to-digital conversion circuit, a controller and a liquid crystal display; the output terminal of the energy storage rechargeable battery One end of the double-throw switch is connected to the input end of the analog-to-digital conversion circuit, and the other end of the double-throw switch is connected to the controller; the output end of the analog-to-digital conversion circuit is connected to the input end of the controller, and the output end of the controller Connected to LCD display. 5. The piezoelectric generator charger according to claim 1, wherein the energy storage rechargeable battery is a nickel-cadmium rechargeable battery.

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