A power splitting method for a magnetoelectric power splitter under low-frequency conditions

Abstract

This invention belongs to the field of solid-state power electronic devices and discloses a power splitting method for a magnetoelectric power splitter under low-frequency conditions, comprising the following steps: 1) Fabricating a three-part four-wire-four-port magnetoelectric power splitter: The three-part four-wire-four-port magnetoelectric power splitter is formed by laminating and bonding a layer of magnetostrictive material and a layer of piezoelectric ceramic material, and then tightly winding a copper coil around the bare die. The magnetostrictive material is magnetized along its length, and the upper surface of the piezoelectric ceramic material is coated with three silver electrodes of unequal area and polarized along its thickness; 2) By changing the coating area of ​​the three silver electrodes on the upper surface of the piezoelectric ceramic material, the three output ports of the magnetoelectric power splitter have impedance gradient differences, thereby achieving power splitting of the magnetoelectric power splitter. This invention's three-part four-wire-four-port magnetoelectric power splitter, with its three output ports having impedance gradient differences, achieves power splitting of the magnetoelectric power splitter under low-frequency conditions.

Description

Technical Field

[0001] This invention belongs to the field of solid-state power electronic devices and relates to a power division method for a magnetoelectric power divider under low-frequency conditions. Background Technology

[0002] A power divider is a non-reciprocal passive network element that splits the energy of one input signal into two or more outputs of equal or unequal energy. A certain degree of isolation must be maintained between the output ports of a power divider. Power dividers are typically classified by output type, such as 1-to-2 (one input, two outputs) or 1-to-3 (one input, three outputs). The nature of a three-port network dictates that it is impossible for all ports to be lossless, reciprocal, and matched simultaneously. In 1959, Ernest Wilkinson proposed a new type of power divider, the Wilkinson power divider. This power divider uses resistive loads to achieve isolation between output ports while ensuring matching between input and output ports. The advantages of the Wilkinson power divider are high isolation, low insertion loss, wide bandwidth, and compact structure. However, its disadvantage is that the power dissipation of the resistive load limits its power handling capacity. In 1975, Ulrich Gysel proposed an improved power divider, the Gysel power divider. The advantages of Gysel power dividers include their ability to handle high power and high power imbalance, and the fact that transmission lines with the same characteristic impedance as the load impedance can be led to any location on the circuit. Therefore, the load can be externally connected to the circuit as needed, facilitating the use of high-power loads. Over the past few decades, various types of power dividers have been proposed, such as microstrip power dividers, plasma waveguide power dividers, and substrate waveguide power dividers.

[0003] Among these power dividers, microstrip power dividers, represented by Wilkinson power dividers and implemented using T / Y junctions or multimode interference couplers, have low insertion loss and good balance in high-power applications. However, due to their large size, they can only operate within a very narrow bandwidth and mainly operate in high-frequency environments. Although many miniaturization techniques have been explored, most are aimed at 620MHz-4.6GHz RF. However, in some cases, power division is urgently needed to be implemented at low frequencies or even power supply frequencies. Summary of the Invention

[0004] This invention addresses the technical problem that existing magnetoelectric power dividers cannot perform power division at low frequencies by providing a power division method for magnetoelectric power dividers under low-frequency conditions. By changing the coating area of ​​the three silver electrodes on the upper surface of the piezoelectric ceramic material, the three output ports of the magnetoelectric power divider are made to have impedance gradient differences, thereby realizing power division of the magnetoelectric power divider under low-frequency conditions and achieving maximum working efficiency at the resonant frequency.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention provides a power splitting method for a magnetoelectric power splitter under low-frequency conditions, comprising the following steps:

[0007] 1) Construct a three-part four-wire-four-port magnetoelectric power divider:

[0008] The three-part four-wire-four-port magnetoelectric power divider is made by laminating and bonding a layer of magnetostrictive material and a layer of piezoelectric ceramic material, and then tightly winding a copper coil around the bare die. The magnetostrictive material is magnetized along its length. The port of the copper coil serves as the input port of the magnetoelectric power divider. The upper surface of the piezoelectric ceramic material is coated with three silver electrodes of unequal area and polarized along its thickness. The lower surface of the piezoelectric ceramic material is coated with a silver electrode covering half its area and grounded. The three silver electrodes on the upper surface of the piezoelectric ceramic material serve as output ports I, II, and III of the magnetoelectric power divider, respectively.

[0009] 2) By changing the coating area of ​​the three silver electrodes on the upper surface of the piezoelectric ceramic material, the three output ports of the magnetoelectric power divider are made to have impedance gradient differences, thereby realizing the power division of the magnetoelectric power divider.

[0010] In one technical solution, the magnetostrictive material is Ni. 0.8 Zn 0.2 Fe2O4, the piezoelectric ceramic material is PZT-8.

[0011] In one technical solution, the magnetostrictive material has a thickness of 1 mm, a width of 8 mm, and a length of 37 mm; the piezoelectric ceramic material has a thickness of 1 mm, a width of 8 mm, and a length of 40 mm, and the lengths of the three silver electrodes on the upper surface of the piezoelectric ceramic material are 8 mm, 8 mm, and 20 mm, respectively.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0013] This invention relates to a three-part magnetoelectric power divider with a double-layer stacked block structure. The upper surface of the piezoelectric ceramic material is coated with three silver electrodes of unequal area without altering the polarization of the piezoelectric ceramic material. Simultaneously, half the total area of ​​the silver electrodes on the lower surface of the piezoelectric ceramic material is removed, creating symmetry between the silver-free lower surface and the silver electrodes on the upper surface. This alters the different lengths from the grounding terminal to the three output ports during operation, resulting in different internal impedances at each output port. This creates impedance gradient differences among the three output ports of the magnetoelectric power divider, enabling power division under low-frequency conditions and maximizing operating efficiency at the resonant frequency.

[0014] This invention uses the coil port as the power input port and the three ports on the piezoelectric ceramic surface as the three output ports of the magnetoelectric power divider, achieving power division at a small size and low frequency (53.258kHz). It has outstanding advantages such as being passive, efficient, simple to manufacture, compact in structure, and highly electrically isolated, and has potential application value in fields such as low-power switching power supplies, AC / DC converters, and LED light intensity adjustment. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the magnetoelectric power divider of the present invention.

[0016] Figure 2 This is a schematic diagram of the impedance gradient of the magnetoelectric power divider of the present invention.

[0017] Figure 3 This is a schematic diagram of the measuring device used in this invention to measure the magnetoelectric voltage coefficient of a magnetoelectric power divider.

[0018] Figure 4 The image shows the magnetoelectric voltage coefficient response curve of the magnetoelectric power divider of the present invention in the range of 51.5kHz-55kHz.

[0019] Figure 5 This is a schematic diagram of the measuring device used in this invention to measure the energy conversion efficiency of a magnetoelectric power divider.

[0020] Figure 6 The output voltage and energy conversion efficiency of the magnetoelectric power divider of the present invention are response curves as resistance changes.

[0021] Figure 7 This is a schematic diagram of the measuring device used in this invention to measure the hysteresis curve of a magnetoelectric power divider.

[0022] Figure 8 The image shows the hysteresis curve of the magnetoelectric power divider of this invention. Detailed Implementation

[0023] The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the test methods in the following embodiments are conventional methods.

[0024] Example 1

[0025] like Figure 1 As shown, this invention designs a three-part four-wire-four-port magnetoelectric power divider, which is formed by laminating and bonding a layer of magnetostrictive material and a layer of piezoelectric ceramic material, and then tightly winding a copper coil around the bare die. The magnetostrictive material is magnetized along its length direction, and the port of the copper coil serves as the input port of the magnetoelectric power divider. The upper surface of the piezoelectric ceramic material is coated with three silver electrodes of unequal area and polarized along its thickness direction. The lower surface of the piezoelectric ceramic material is coated with a silver electrode covering half its area and grounded. The three silver electrodes on the upper surface of the piezoelectric ceramic material serve as output ports I, II, and III of the magnetoelectric power divider, respectively.

[0026] In this embodiment, the magnetostrictive material used in the magnetoelectric power divider is Ni. 0.8 Zn 0.2 Fe2O4, piezoelectric ceramic material is PZT-8. The magnetostrictive material has a thickness of 1 mm, a width of 8 mm, and a length of 37 mm; the bare piezoelectric ceramic material has a thickness of 1 mm, a width of 8 mm, and a length of 40 mm. The three silver electrodes on the upper surface of the piezoelectric ceramic material have lengths of 8 mm, 8 mm, and 20 mm, respectively, with a 2 mm spacing between adjacent silver electrodes. Therefore, the areas of the three silver electrodes on the upper surface of the piezoelectric ceramic material are 20 × 8 mm². 2 8×8mm 2 and 8×8mm 2 , Figure 1 From right to left, the three ports are output port I, output port II, and output port III. The grounding terminal on the lower surface has a surface area of ​​20×5mm. 2 The specific manufacturing method is as follows: First, silver electrodes are coated on the surface of the PZT-8 sample, making its upper and lower surfaces exhibit... Figure 1 The three-port structure shown has ports spaced 2 mm apart, and the oxide layer and impurities on the surface were removed with acetone solution. Then, the lower surface of the PZT-8 sample was bonded to the nickel-zinc ferrite sample using acrylic adhesive, leaving the three ports on the upper surface as output electrodes. Next, the composite sample was cured in a 70°C oven for 2 hours, then cooled to room temperature. Subsequently, electrode wires were led out from the three ports of the piezoelectric ceramic to serve as the output ports of the element. Finally, 210 turns of 0.2 mm enameled wire were evenly wound around the periphery of the composite element to form an input coil, leaving two ends as input ports.

[0027] The working principle of the magnetoelectric power divider of this invention is as follows: Unpolarized piezoelectric ceramics have randomly arranged domains and do not exhibit piezoelectric effect. After polarization, the spontaneous polarization of each domain aligns to a certain extent with the orientation of the external electric field. Therefore, the polarization intensity within the piezoelectric ceramic sheet is no longer zero, and equal numbers of bound charges with opposite signs appear on two surfaces perpendicular to the electric moment direction, resembling a large electric dipole. However, the charges on its surface are quickly neutralized by free charges migrating from the outside or inside, forming a so-called ionosphere. If a pressure parallel to the polarization direction is applied to the piezoelectric ceramic sheet, the piezoelectric ceramic will undergo compressive deformation, reducing the distance between the positive and negative bound charges within the sheet, and decreasing the polarization intensity. Some of the previously migrated free charges will be released, resulting in a discharge phenomenon when the piezoelectric ceramic sheet is compressed along the polarization direction. When the pressure is removed, the ceramic sheet returns to its original shape, the distance between the positive and negative charges within the sheet increases, and the polarization intensity also increases. Therefore, some charges will be adsorbed on the electrodes, resulting in a charging phenomenon.

[0028] During operation, the output port I of the magnetoelectric power divider of this invention is polarized along the thickness direction. The silver electrode on the upper surface releases the positive charges that migrated there, and the silver electrode on the lower surface releases the negative charges that migrated there, thereby forming an electric field along the thickness direction. This electric field is perpendicular to the magnetic field, as determined by the piezoelectric equation. It can be concluded that Then it was concluded From the definition of electromechanical coupling coefficient, we can obtain Therefore, the above equation becomes Let the length of PZT-8 be l and the width be w, and the charge on the electrode surface of output port I be... It can be seen that the amount of free charge released is directly proportional to the surface area of ​​the silver electrode, which is... Furthermore, at this time, the impedance of output port I is the impedance in the thickness direction of PZT-8, which is the smallest among the three ports (see...). Figure 2 d), therefore, output port I is the device's maximum power output port. When output port II is operating, its surface silver electrode area is... Since the positive and negative charges released by the upper and lower plates should be equal, the area of ​​the lower surface can also be equivalent to S2, resulting in a decrease in surface charge and consequently a drop in output voltage. The impedance of output port II consists of the impedance along the thickness of the PZT-8 plate and the impedance along its length, which is higher than that of output port I. This inherent intrinsic impedance gradient difference further reduces the output voltage. The same applies when output port III is operating; its surface area is the same as output port II. However, because output port III is farther from the ground and its impedance along its length is greater than that of output port II (see...),... Figure 2d) Therefore, output port III is the smallest output port. Finally, the coil port is used as the input port of the device. When a signal is received, a longitudinal alternating magnetic field is generated inside the coil. The magnetostrictive layer of the bare die senses the longitudinal alternating magnetic field and generates tensile strain at the same frequency. The strain is then transferred to the piezoelectric ceramic material layer through the interlayer interface. With the help of the piezoelectric effect of the piezoelectric ceramic material and its inherent intrinsic impedance gradient difference, the three output ports of the piezoelectric ceramic material can output voltages simultaneously, thereby achieving the division of the input power of the coil port. At the same time, the good electrical isolation characteristics caused by the impedance gradient difference are also utilized in the process of realizing the power division function.

[0029] Construct a measurement device for a magnetoelectric power divider using the following instruments: Doppler vibration meter, lock-in amplifier, neodymium iron boron magnetic rail, support frame, electromagnet, PCIe acquisition card, signal generator, adjustable rheostat box, impedance analyzer, and LED light board. Characterize the magnetoelectric voltage coefficient, conversion efficiency, impedance and capacitance of each port, output voltage waveform, hysteresis curves of each port, and conduct a lighting experiment.

[0030] When measuring the MEVC (magnetic voltage coefficient) of a magnetoelectric power divider, the measuring device is as follows: Figure 3 As shown, the output of a lock-in amplifier is connected to the tightly wound coil of the magnetoelectric power divider. The three outputs of the laminated composite material are respectively connected to the voltage input measurement port of the lock-in amplifier. The lock-in amplifier is connected to a PC via a communication cable. The magnetoelectric power divider is fixed to a neodymium iron boron magnetic track. The PC adjusts the input voltage, AC magnetic field, and frequency of the lock-in amplifier to the magnetoelectric power divider through a program, and manually adjusts the magnitude of the bias magnetic field applied by the neodymium iron boron permanent magnet device. Figure 4 The magnetoelectric voltage coefficient response curve of the magnetoelectric power divider of this invention is shown in the range of 51.5kHz-55kHz. With an excitation voltage of 282.8mV, the amplitude-frequency response of the piezoelectric ceramic material within the resonant range was measured. Figure 4 As shown, the resonant characteristics and optimal bias magnetic field of the device were measured. The resonant frequency was 53.21kHz and the optimal bias magnetic field was 20Oe.

[0031] When measuring the energy conversion efficiency of a magnetoelectric power divider, the measuring device is as follows: Figure 5 As shown, the device is first placed on a neodymium iron boron magnetic track and adjusted to the optimal bias magnetic field. Then, the signal generator is connected to the input terminal of the device and adjusted to the resonant frequency. A sliding rheostat is connected in series at the output port of the magnetoelectric power divider. Changing the resistance will cause the output voltage and power to change accordingly. That is, as the resistance increases, the output voltage increases significantly, and eventually the increasing trend tends to level off. Figure 6The output voltage and power of the magnetoelectric power divider at the resonant point (53.258kHz) are given by the output load response curves. The maximum conversion efficiencies of the output ports I to III are 29.83%, 7.93%, and 1.34% at 25kΩ, 14kΩ, and 14kΩ, respectively. The maximum efficiency of the device at the optimal bias and resonant point is 39.1%.

[0032] When measuring the hysteresis curve of a magnetoelectric power divider, the measuring device is as follows: Figure 7 As shown, a magnetoelectric power divider is placed inside an electromagnet. By changing the current in the electromagnet, the magnitude of its magnetic field is altered, providing a DC bias magnetic field for the power divider. Finally, the output of a signal generator is connected to the input of the device, and the excitation frequency is set to the resonant frequency of 53.258kHz, with a voltage of 200mV, to provide an AC magnetic field for the magnetoelectric power divider. Figure 8 The output voltage at different ports of the magnetoelectric power divider is shown as a response curve to changes in the magnetic field.

[0033] The embodiments described above are merely preferred embodiments of the present invention and are only used to explain the present invention. They are not intended to limit the scope of the present invention. For those skilled in the art, other implementation methods can be easily made by substitution or modification based on the technical content disclosed in this specification. Therefore, all changes and improvements made on the principle of the present invention should be included within the scope of the patent application of the present invention.

Claims

1. A power splitting method of a magneto-electric power splitter under low frequency conditions, characterized by, Includes the following steps: 1) Fabrication of a three-part four-wire-four-port magnetoelectric power divider: The three-part four-wire-four-port magnetoelectric power divider is made by laminating and bonding a layer of magnetostrictive material and a layer of piezoelectric ceramic material, and then tightly winding a copper coil around the bare die. The magnetostrictive material is magnetized along its length. The port of the copper coil serves as the input port of the magnetoelectric power divider. The upper surface of the piezoelectric ceramic material is coated with three silver electrodes of unequal area and polarized along its thickness. The lower surface of the piezoelectric ceramic material is coated with a silver electrode covering half its area and grounded. The three silver electrodes on the upper surface of the piezoelectric ceramic material serve as output ports I, II, and III of the magnetoelectric power divider, respectively. 2) By changing the coating area of ​​the three silver electrodes on the upper surface of the piezoelectric ceramic material, the three output ports of the magnetoelectric power divider are made to have impedance gradient differences, thereby realizing the power division of the magnetoelectric power divider.

2. The power splitting method of a magneto-electric power splitter under low frequency conditions according to claim 1, characterized in that, The magnetostrictive material is Ni. 0.8 Zn 0.2 Fe2O4, the piezoelectric ceramic material is PZT-8.

3. The power splitting method of a magneto-electric power splitter under low frequency conditions according to claim 1, characterized in that, The magnetostrictive material has a thickness of 1 mm, a width of 8 mm, and a length of 37 mm; the piezoelectric ceramic material has a thickness of 1 mm, a width of 8 mm, and a length of 40 mm, and the lengths of the three silver electrodes on the upper surface of the piezoelectric ceramic material are 8 mm, 8 mm, and 20 mm, respectively.

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