CN108258811B - A composite energy harvesting circuit - Google Patents

Abstract

The invention discloses a composite energy acquisition circuit which is characterized by comprising a thermoelectric generation sheet, a piezoelectric sheet, a positive and negative peak detection module, a zero potential switching module, a first inductor, a first diode, a first energy storage capacitor, a second energy storage capacitor and a load; the energy collection device has the advantages that the parasitic capacitance in the piezoelectric sheet and the first energy storage capacitor are connected in series to generate LC oscillation, charges accumulated on the parasitic capacitance in the piezoelectric sheet and the first energy storage capacitor are transferred to the first inductance, when the current on the first inductance reaches the maximum value, the first PNP tube or the second PNP tube is immediately disconnected through the positive and negative peak detection module, then the energy stored on the first inductance is fully flowed to the load and the second energy storage capacitor through the first diode, and the whole circuit is completely self-started and self-powered and can continuously collect thermoelectric energy and piezoelectric vibration energy in the environment, so that the energy collection efficiency of the whole circuit is improved, and the use cost is reduced.

Description

A composite energy harvesting circuit

Technical field

The invention relates to an energy harvesting circuit, in particular to a composite energy harvesting circuit.

Background technique

Piezoelectric vibration energy harvesting is a method that uses the piezoelectric effect of piezoelectric materials to collect vibration energy in the environment. Since the output voltage of the piezoelectric sheet is an AC signal, general electronic equipment is powered by a DC power supply. , therefore, an interface circuit is needed between the piezoelectric sheet and the electronic device, through which the conversion of AC voltage to DC voltage is achieved, and the higher the conversion efficiency of this interface circuit, the better. The interface circuit that was first proposed It is a standard energy capture circuit, consisting of a diode bridge rectifier circuit and a filter capacitor. The advantage of this structure is that the circuit is simple, stable and reliable. However, due to the threshold voltage loss of the diode, the collection efficiency of the circuit is low, and this The collection efficiency of the structure is easily affected by the size of the load.

Thermoelectric generators can use the temperature difference in the environment to collect energy. However, the temperature difference in the environment is usually small. The open circuit voltage of the thermoelectric generator is very low. Factors such as the efficiency of the energy collection circuit between the generator and the load increase the temperature difference energy. Difficulty of utilization; currently, thermoelectric energy harvesting circuits are mainly divided into capacitive charge pump circuits and inductive boost circuits. Although the charge pump circuit can increase the voltage of the thermoelectric power generation chip, the driving ability of the charge pump structure is very weak, and the low-voltage charge pump The circuit is even more inefficient; although the inductive boost circuit has high efficiency and strong ability to drive the load, the open circuit voltage of the thermoelectric generator is generally lower than the threshold voltage of the switching tube, which results in the inductive boost circuit often It requires an external power supply and cannot start automatically when the external power supply is not connected, which increases the cost of use.

In order to obtain more energy from the environment and increase the total power of environmental energy harvesting, some researchers have proposed the idea of multi-source energy harvesting, that is, harvesting various forms of energy such as vibration energy, thermal energy, and microwave radiation in the environment. However, since the signals generated by different energy sources are completely different, different signals cannot be directly coupled together. Therefore, the general multi-source energy collection system usually uses the comparison method, that is, by comparing the magnitude of the two energy densities, the one with the stronger energy is selected and collected. One kind of energy will cause another kind of energy to be unable to be collected, affecting the overall collection efficiency.

Contents of the invention

The technical problem to be solved by the present invention is to provide a composite energy harvesting circuit that can simultaneously collect piezoelectric vibration energy and temperature difference thermoelectric energy, and has high energy collection efficiency.

The technical solution adopted by the present invention to solve the above technical problems is: a composite energy collection circuit, including a thermoelectric power generation piece, a piezoelectric piece, a positive and negative peak detection module, a zero-potential switching module, a first inductor, a first diode, The first energy storage capacitor, the second energy storage capacitor and the load. The positive and negative peak detection module includes a first NPN tube, a second NPN tube, a first PNP tube, a second PNP tube, a fourth diode, Five diodes and the first capacitor are connected to the first pin of the thermoelectric power generation piece, one end of the first energy storage capacitor and one end of the first inductor, and the other end of the first inductor is connected One end, the anode of the first diode, the emitter of the first PNP tube and the emitter of the second PNP tube are connected, and the cathode of the first diode, the emitter of the first PNP tube and the emitter of the second PNP tube are connected. The anode of the second energy storage capacitor is connected to one end of the load, the collector of the second PNP tube, the base of the second NPN tube, the cathode of the fifth diode, the The first input end of the zero-potential switching module is connected to the first pin of the piezoelectric sheet, the collector of the first PNP tube, the base of the first NPN tube, the The cathode of the fourth diode, the second input end of the zero-potential switching module and the second pin of the piezoelectric sheet are connected, and the base of the first PNP tube is connected to the first The collector of the NPN tube is connected, the base of the second PNP tube is connected to the collector of the second NPN tube, the anode of the fifth diode and the emitter of the second NPN tube The electrode is connected to one end of the first capacitor, the other end of the first capacitor, the anode of the fourth diode and the emitter of the first NPN tube are connected, and the temperature difference generates electricity The second pin of the chip, the other end of the first energy storage capacitor, the negative electrode of the second energy storage capacitor, the other end of the load and the ground end of the zero potential switching module are all grounded .

The zero-potential switching module includes a second diode and a third diode, the anode of the second diode is connected to the first pin of the piezoelectric sheet, and the third diode The anode of the diode is connected to the second pin of the piezoelectric piece, and the cathode of the second diode and the cathode of the third diode are both grounded.

Compared with the prior art, the advantage of the present invention is that by connecting the first inductor in series with the parasitic capacitance in the piezoelectric sheet and the first energy storage capacitor charged by the thermoelectric generator sheet, LC oscillation is generated, and the parasitic capacitance in the piezoelectric sheet is generated. The charge accumulated on the capacitor and the charge accumulated on the first energy storage capacitor are transferred to the first inductor. When the current on the first inductor reaches the maximum value, the first PNP tube or the first PNP tube is immediately disconnected through the positive and negative peak detection module. Two PNP tubes, and then all the energy stored in the first inductor flows to the load and the second energy storage capacitor through the first diode. The overall circuit is completely self-starting and self-powered, and can continuously respond to the temperature difference in the environment. Thermoelectric energy and piezoelectric vibration energy are collected, thereby improving the energy collection efficiency of the overall circuit and reducing the cost of use.

Description of the drawings

Figure 1 is a schematic diagram of the circuit structure of the present invention.

Detailed ways

The present invention will be described in further detail below with reference to the embodiments of the drawings.

A composite energy harvesting circuit, including a thermoelectric power generating sheet U1, a piezoelectric sheet U2, a positive and negative peak detection module, a zero-potential switching module, a first inductor L1, a first diode D1, a first energy storage capacitor Ct, a second Energy storage capacitor Cr and load RL, the positive and negative peak detection module includes the first NPN tube Q1, the second NPN tube Q3, the first PNP tube Q2, the second PNP tube Q4, the fourth diode D4, and the fifth diode D5 is connected to the first capacitor C1, the first pin of the thermoelectric generator U1, one end of the first energy storage capacitor Ct and one end of the first inductor L1, and the other end of the first inductor L1 and the anode of the first diode D1 , the emitter of the first PNP tube Q2 and the emitter of the second PNP tube Q4 are connected, the cathode of the first diode D1, the anode of the second energy storage capacitor Cr and one end of the load RL are connected, the second PNP tube Q4 The collector, the base of the second NPN tube Q3, the cathode of the fifth diode D5, the first input terminal of the zero-potential switching module and the first pin of the piezoelectric sheet U2 are connected, and the collector of the first PNP tube Q2 , the base of the first NPN tube Q1, the cathode of the fourth diode D4, the second input terminal of the zero-potential switching module and the second pin of the piezoelectric sheet U2 are connected, and the base of the first PNP tube Q2 is connected to the second pin of the piezoelectric sheet U2. The collector of an NPN tube Q1 is connected, the base of the second PNP tube Q4 is connected to the collector of the second NPN tube Q3, the anode of the fifth diode D5, the emitter of the second NPN tube Q3 and the first capacitor C1 One end is connected, the other end of the first capacitor C1, the anode of the fourth diode D4 and the emitter of the first NPN tube Q1 are connected, the second pin of the thermoelectric generator U1 and the other end of the first energy storage capacitor Ct are connected , the negative electrode of the second energy storage capacitor Cr, the other end of the load RL and the ground end of the zero-potential switching module are all grounded.

The zero-potential switching module includes a second diode D2 and a third diode D3. The anode of the second diode D2 is connected to the first pin of the piezoelectric sheet U2, and the anode of the third diode D3 is connected to the piezoelectric sheet U2. The second pin of chip U2 is connected, the cathode of the second diode D2 and the cathode of the third diode D3 are both grounded.

The energy harvesting principle of the circuit using the above structure is as follows: It is defined as a positive half cycle when the voltage of the first pin of the piezoelectric sheet U2 is higher than the voltage of the second pin. In the positive half cycle, the thermoelectric power generating sheet U1 supplies energy to the first storage The capacitor Ct is charged, the voltage difference between the first pin and the second pin of the piezoelectric sheet U2 gradually increases, and the second NPN tube Q3, the fourth diode D4, the first capacitor C1 and the piezoelectric sheet U2 A loop is formed, through which the piezoelectric sheet U2 charges the first capacitor C1, until the voltage difference between the first pin and the second pin of the piezoelectric sheet U2 reaches a peak value, the voltage difference begins to decrease, and then the voltage difference The voltage at the second pin of the electronic chip U2 begins to increase, but since the charge accumulated on the first capacitor C1 is not released in the loop, the base voltage of the first NPN transistor Q1 will be higher than the emitter voltage of the first NPN transistor Q1. Moreover, the voltage difference between the two will gradually increase until the voltage difference between the two is greater than the threshold voltage of the first NPN transistor Q1. At this time, the first NPN transistor Q1 is turned on, causing the first PNP transistor Q2 to be turned on. At the same time, since the voltage of the first pin of the piezoelectric sheet U2 is higher than the voltage of the second pin, the first pin of the piezoelectric sheet U2 is grounded through the second diode D2. Therefore, the piezoelectric sheet U2 and the second pin of the piezoelectric sheet U2 are grounded. The diode D2, the first inductor L1, the first energy storage capacitor Ct and the first PNP tube Q2 will form an LC oscillation circuit, and the LC oscillation circuit can convert the first capacitor through a quarter of an LC oscillation cycle. The charge accumulated on C1 is transferred to the first inductor L1, and the conversion from electrical energy to magnetic energy is completed at the same time; when the current on the first inductor L1 reaches the maximum value, the charge on the first capacitor C1 is released, resulting in the first PNP The tube Q2 is disconnected, so the current on the first inductor L1 can only flow to the second energy storage capacitor Cr and the load RL through the first diode D1, completing the conversion of magnetic energy to electrical energy, thereby realizing energy extraction in the positive half cycle. ;Define when the voltage of the first pin of the piezoelectric sheet U2 is lower than the voltage of the second pin, it is in the negative half cycle. In the negative half cycle, the thermoelectric power generating sheet U1 charges the first energy storage capacitor Ct, and the piezoelectric sheet U2 The voltage difference between the two ends gradually increases, and the first NPN tube Q1, the fifth diode D5, the first capacitor C1 and the piezoelectric sheet U2 form a loop. The piezoelectric sheet U2 charges the first capacitor C1 through the loop until the voltage is After the voltage difference across the piezoelectric piece U2 reaches the peak value, the voltage difference begins to decrease, and the voltage at the first pin of the piezoelectric piece U2 begins to increase. However, since the charge accumulated on the first capacitor C1 is not released in the loop, the second NPN transistor Q3 The base voltage of will be higher than the emitter voltage of the second NPN transistor Q3, and the voltage difference between the two will gradually become larger, until the voltage difference between the two is greater than the threshold voltage of the second NPN transistor Q3, at this time The second NPN transistor Q3 is turned on, causing the second PNP transistor Q4 to be turned on. At the same time, because the voltage of the first pin of the piezoelectric sheet U2 is lower than the voltage of the second pin, the second pin of the piezoelectric sheet U2 is turned on. The pin is connected to the ground through the third diode D3. Therefore, the piezoelectric piece U2, the third diode D3, the first inductor L1, the first energy storage capacitor Ct and the second PNP tube Q4 will form an LC oscillation circuit, and The LC oscillation circuit can transfer the charge accumulated on the first capacitor C1 to the first inductor L1 through a quarter of the LC oscillation cycle, and at the same time completes the conversion from electrical energy to magnetic energy. When the current on the first inductor L1 When reaching the maximum value, the charge on the first capacitor C1 is completely released, causing the second PNP transistor Q4 to be disconnected. Therefore, the current on the first inductor L1 can only flow to the second energy storage capacitor Cr and the load through the first diode D1. RL, completes the conversion of magnetic energy into electrical energy, thereby achieving negative half-cycle energy extraction.

Claims (2)

1. A composite energy harvesting circuit, which is characterized by comprising a thermoelectric power generation piece, a piezoelectric piece, a positive and negative peak detection module, a zero-potential switching module, a first inductor, a first diode, a first energy storage capacitor, a second Energy storage capacitor and load, the positive and negative peak detection module includes a first NPN tube, a second NPN tube, a first PNP tube, a second PNP tube, a fourth diode, a fifth diode and a first capacitor , the first pin of the thermoelectric power generation piece, one end of the first energy storage capacitor and one end of the first inductor are connected, the other end of the first inductor, the first two The anode of the diode, the emitter of the first PNP tube and the emitter of the second PNP tube are connected, the cathode of the first diode, the anode of the second energy storage capacitor and One end of the load is connected to the collector of the second PNP tube, the base of the second NPN tube, the cathode of the fifth diode, and the third terminal of the zero-potential switching module. An input terminal is connected to the first pin of the piezoelectric film, the collector of the first PNP tube, the base of the first NPN tube, the cathode of the fourth diode, The second input end of the zero-potential switching module is connected to the second pin of the piezoelectric sheet, and the base of the first PNP tube is connected to the collector of the first NPN tube, so The base of the second PNP tube is connected to the collector of the second NPN tube, the anode of the fifth diode, the emitter of the second NPN tube and the first capacitor One end is connected, the other end of the first capacitor, the anode of the fourth diode and the emitter of the first NPN tube are connected, the second pin of the thermoelectric power generation piece, the The other end of the first energy storage capacitor, the negative electrode of the second energy storage capacitor, the other end of the load and the ground end of the zero-potential switching module are all grounded. 2. A composite energy harvesting circuit according to claim 1, characterized in that the zero-potential switching module includes a second diode and a third diode, and the anode of the second diode is connected to the anode of the second diode. The first pin of the piezoelectric sheet is connected, the anode of the third diode is connected to the second pin of the piezoelectric sheet, and the cathode of the second diode is connected to the cathode of the piezoelectric sheet. The cathodes of the third diodes are connected to ground.