High-power microwave rectifying circuit based on series dc synthesis

Abstract

The application discloses a high-power microwave rectifying circuit based on series connection type direct current synthesis and belongs to the technical field of wireless energy transmission. The circuit comprises a dielectric substrate, a circuit structure on the front surface of the dielectric substrate and a metal floor on the back surface of the dielectric substrate; the circuit structure comprises a one-to-two power divider, two rectifying circuits, a load resistor, a grounding via and the metal floor. The input radio frequency signal is equally divided to the two rectifying circuits for rectification by the one-to-two power divider, so that the input radio frequency power value of the whole circuit is doubled; the series connection type direct current synthesis structure is adopted, the maximum direct current output power and the rectifying efficiency of the microwave rectifying circuit are improved, the defect that the voltage output of one of the rectifying circuits cannot be achieved in the traditional parallel connection type direct current synthesis structure is avoided, and the rectifying efficiency is higher and the output power capacity is higher.

Description

Technical Field

[0001] This invention belongs to the field of wireless power transmission technology, specifically relating to a high-power microwave rectifier circuit based on series DC synthesis. Background Technology

[0002] Wireless Power Transmission (WPT) eliminates the need for physical cables, enabling wireless energy transfer between multiple points in space via electric fields, magnetic fields, electromagnetic waves, ultrasound, or lasers. WPT technology is primarily categorized into two types based on its operating mechanism: near-field coupling and far-field radiation. Near-field coupling WPT utilizes methods such as magnetic induction coupling, magnetic resonance coupling, and electric field coupling for wireless energy transfer. However, electric field coupling WPT has received relatively little research due to its short transmission distance and the potential harm of its strong electric field to living organisms, resulting in few commercial applications. Far-field radiation WPT, on the other hand, uses electromagnetic waves (radio frequency, microwave, millimeter wave, and light waves) as the energy carrier and possesses the potential for long-distance wireless energy transfer between multiple points.

[0003] Compared to the relatively mature electrical near-field coupling (WPT) technology, microwave wireless power transfer technology enables long-distance wireless power transfer and long-distance wireless charging of slowly moving receiving devices. It can also charge multiple moving receiving devices simultaneously. A microwave wireless power transfer system mainly consists of a transmitter and a receiver. The transmitter comprises a DC power supply, a microwave power source, a main control module, and a transmitting antenna / array module. The receiver consists of a receiving antenna / array, a rectifier circuit unit / array module, a power management module, and a battery. The rectifier circuit module converts radio frequency energy into DC energy, then transmits the DC energy to the power management module, and finally to the battery for charging. Since the performance of the rectifier circuit module directly affects the performance of the entire wireless power transfer system, it plays a crucial role.

[0004] Traditional single-channel microwave rectifier circuits generally suffer from low output power, making them unsuitable for high-power wireless power transfer systems. For example, the patent application number CN202210791394.1 uses a lumped-element design for its single-channel rectifier circuit, which has the advantage of small size, but its maximum RF input power is only 23dBm and its maximum DC output power is only 140mW, making it unsuitable for high-power (input power above 30dBm) wireless power transfer systems.

[0005] Because a single-channel rectifier circuit cannot meet the demands of high power, researchers have proposed using a power divider combined with a rectifier circuit. The power divider splits the radio frequency signal into two, supplying the signal to two rectifier circuits, thereby increasing the input and output power of the rectifier circuits. Traditional power dividers combined with microwave rectifier circuits typically use parallel DC-DC combining at the output. However, for the two rectifier circuits actually soldered, errors make it almost impossible to guarantee that the DC output voltages of the two rectifiers are identical. When the output voltages of the two rectifiers are different, the higher voltage will suppress the lower voltage, preventing current from flowing out of the lower voltage circuit. This is equivalent to the lower voltage rectifier circuit not working, thus reducing the overall rectification efficiency and output power of the rectifier circuit. For example, patent application number CN202010248844.3 uses a combination of a power divider and a rectifier circuit to increase DC output power; however, when performing DC combining, this patent uses a traditional parallel DC-DC combining method, with an optimal input power of only 14dBm, resulting in a limited input power range. Summary of the Invention

[0006] To overcome the problems of low output power and low efficiency of traditional microwave rectifier circuits, this invention proposes a high-power microwave rectifier circuit based on series DC synthesis, combining principles such as DC synthesis, harmonic impedance control and harmonic recovery, and external power divider to increase output power.

[0007] The technical solution adopted in this invention is as follows:

[0008] A high-power microwave rectifier circuit based on series DC synthesis is characterized by comprising a dielectric substrate, a circuit structure disposed on the upper surface of the dielectric substrate, and a metal ground plane disposed on the lower surface of the dielectric substrate.

[0009] The circuit structure includes a 1-to-2 microstrip power divider, a first rectifier circuit, a second rectifier circuit, a load resistor, a grounding via, and a metal ground plane.

[0010] The 1-to-2 microstrip power divider includes one input port and two output ports. The input port is connected to the RF signal input pin, and the two output ports are connected to the first rectifier circuit and the second rectifier circuit, respectively. Since each rectifier circuit has a limited maximum input power capacity, the 1-to-2 power divider splits the input RF signal equally between the two rectifier circuits for rectification, thereby doubling the RF input power of the entire circuit and further increasing the rectified DC output power.

[0011] Both the first rectifier circuit and the second rectifier circuit include an inductor, a Schottky diode, a first capacitor, a second capacitor, an open-circuit microstrip line, and a short-circuit microstrip line.

[0012] In the first rectifier circuit, one end of the first capacitor is connected to the output port of the 1-to-2 microstrip power divider, and the other end is connected to the negative terminal of the Schottky diode, the inductor, and the open-circuit microstrip line; the positive terminal of the Schottky diode is connected to one end of the short-circuit microstrip line; the other end of the short-circuit microstrip line is connected to the metal ground plane through a grounding via; the other end of the inductor is connected to the load resistor and the second capacitor; the other end of the second capacitor is connected to the metal ground plane through a grounding via.

[0013] In the second rectifier circuit, one end of the first capacitor is connected to the output port of the 1-to-2 microstrip power divider, and the other end is connected to the positive terminal of the Schottky diode, the inductor, and the open-circuit microstrip line; the negative terminal of the Schottky diode is connected to one end of the short-circuit microstrip line; the other end of the short-circuit microstrip line is connected to the metal ground plane through a grounding via; the other end of the inductor is connected to the other end of the load resistor and the second capacitor; the other end of the second capacitor is connected to the metal ground plane through a grounding via.

[0014] Furthermore, the open-circuit microstrip line is a λ / 12 microstrip line, and the short-circuit microstrip line is a λ / 8 microstrip line.

[0015] Furthermore, the first capacitor and the second capacitor are Murata capacitors, and the inductor is a Murata inductor.

[0016] In this invention, an LC pass-through filter composed of an inductor and a first capacitor is placed at the output end of the rectifier circuit to filter out radio frequency components and allow DC components to pass through, preventing radio frequency components from flowing to the load resistor RL and allowing the DC signal to be output to the load resistor RL.

[0017] In this invention, a high impedance to the second harmonic is achieved by connecting a λ / 8 short-circuited microstrip line in series at one end of the diode. The inductive property at the fundamental frequency counteracts the diode's capacitive property, reducing the difficulty of subsequent impedance matching. The low impedance at the DC level allows DC to pass smoothly. A λ / 12 open-circuited microstrip line is connected in parallel at the other end of the diode to achieve low impedance to the third harmonic, exhibiting capacitive properties at the fundamental frequency and high impedance at the DC level. Simultaneously, the series-connected short-circuited microstrip line and the parallel-connected open-circuited microstrip line reflect the second and third harmonics back to the diode, preventing them from entering the DC output terminal and signal source, thus allowing harmonic energy to be reused and increasing rectification efficiency. Furthermore, the series-connected short-circuited microstrip line and the parallel-connected open-circuited microstrip line respectively present low impedance to the third harmonic and high impedance to the second harmonic, thereby achieving inverse Class F harmonic impedance control. This reduces the overlap of voltage and current across the diode in the time domain, reducing diode losses and further improving rectification efficiency. Finally, this microstrip structure also eliminates the input filter / matching network found in traditional rectifier structures, reducing the size of the rectifier circuit.

[0018] In this invention, by reversing the diodes in the two rectifier circuits and connecting the load resistor in series between the DC output terminals of the two rectifier circuits, a series DC combining structure is formed, allowing the load resistor to bear the DC output power of the two rectifier circuits. Secondly, this series DC combining structure avoids the disadvantage of the traditional parallel DC combining structure where the current output of the rectifier circuit at the lower voltage end cannot be achieved. Therefore, the series DC combining structure has higher rectification efficiency and higher output power capacity.

[0019] Compared with the prior art, the main advantages of the present invention are:

[0020] 1. The series DC combining structure improves the maximum DC output power and rectification efficiency of the microwave rectifier circuit. The series DC combining structure avoids the drawback of the traditional parallel DC combining structure, where one end of the rectifier circuit cannot output voltage. Therefore, the series DC combining structure has higher rectification efficiency and higher output power capacity.

[0021] 2. By adding a 1-to-2 power divider, the maximum DC output power of the entire rectifier circuit is increased. By adding a 1-to-2 power divider, the input RF signal is split equally between two rectifier circuits for rectification, thereby doubling the input RF power of the entire circuit and further increasing the rectified DC output power. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of the rectifier circuit in an embodiment.

[0023] Figure 2 This is a circuit diagram of the rectifier circuit of the present invention.

[0024] Figure 3 This is a DC circuit diagram of the rectifier circuit of the present invention.

[0025] Figure 4 The simulation and measured results of the rectification efficiency of the rectifier circuit as a function of input power are presented as an example. Detailed Implementation

[0026] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0027] A high-power microwave rectifier circuit based on series DC-DC synthesis, operating at a center frequency of 2.5 GHz, comprises a dielectric substrate, a circuit structure disposed on the upper surface of the dielectric substrate, and a metal ground plane disposed on the lower surface of the dielectric substrate. The dielectric substrate is Rogers RO4003C, with a thickness of 0.508 mm, a relative permittivity of 3.55, a loss tangent of 0.0027, and the overall circuit dimensions are 2.4 cm × 3.2 cm.

[0028] Figure 1 This is a schematic diagram of the overall structure of the rectifier circuit in the embodiment, including a 1-to-2 microstrip power divider DV, four capacitors Cin1, Cin2, Cout1, and Cout2, two inductors Lout1 and Lout2, two Schottky diodes D1 and D2, four microstrip lines ML12_1, ML12_2, ML8_1, and ML8_2, a load resistor RL, four grounding vias, and a radio frequency input source Pin.

[0029] The input port of the 1-to-2 microstrip power divider DV is connected to the RF signal input pin, and the two output ports are connected to capacitors Cin1 and Cin2 respectively. The other ends of the two capacitors are connected to the λ / 12 microstrip lines ML12_1 and ML12_2 of the two rectifier circuits.

[0030] The left end of microstrip line ML12_1 is connected to capacitor Cin1, the right end is connected to the negative terminal of Schottky diode D1, and the lower end is connected to inductor Lout1; while the left end of microstrip line ML8_1 is connected to the positive terminal of Schottky diode D1, and the right end is connected to a metallized via for grounding; one end of inductor Lout1 is connected to microstrip line ML12_1, and the other end is connected to capacitor Cout1. The other end of capacitor Cout1 is connected to the metal grounding via on the lower surface of the dielectric substrate.

[0031] The left end of microstrip line ML12_2 is connected to capacitor Cin2, the right end is connected to the positive terminal of Schottky diode D2, and the lower end is connected to inductor Lout2. The left end of microstrip line ML8_2 is connected to the negative terminal of Schottky diode D2, and the right end is connected to a metallized via for grounding. One end of inductor Lout2 is connected to microstrip line ML12_2, and the other end is connected to capacitor Cout2. The other end of capacitor Cout2 is connected to the metal grounding via on the lower surface of the dielectric substrate.

[0032] The load resistor RL is connected to the DC output terminals of the two rectifier circuits. One end of the load resistor is connected at the connection point of inductor Lout1 and capacitor Cout1, and the other end is connected at the connection point of inductor Lout2 and capacitor Cout2.

[0033] Capacitors Cin1 and Cin2 are 24pF, Cout1 and Cout2 are 100pF, inductors Lout1 and Lout2 are 27nH, load resistance is 240Ω, microstrip lines ML12_1 and ML12_2 have a length × width of 9mm × 2mm, and microstrip lines ML8_1 and ML8_2 have a length × width of 9mm × 7mm.

[0034] Figure 2 The circuit diagram shows the rectifier circuit of this invention. The rectifier circuit operates as follows: Radio frequency (RF) energy is input from the left input port of the power divider. The power divider splits the RF energy into two, which are then rectified at the input ports of the two rectifiers. Since the two rectifier circuits are identical except for the diode orientation, the above rectifier circuit will be used as an example. First, the RF energy after being split into two enters the rectifier circuit and passes through a DC blocking capacitor Cin1 to prevent the rectified DC from entering the input terminal and causing DC energy loss. Then, the RF energy simultaneously flows to the HSMS270C diode and the through-pass filter circuit formed by the inductor Lout1 and the capacitor Cout1. When radio frequency (RF) energy flows to the HSMS270C diode, the rectifier diode converts the RF energy into DC energy. Simultaneously, due to the nonlinear nature of the diode, higher harmonics are generated. Therefore, by connecting a λ / 8 short-circuited microstrip line ML8_1 in series at one end of the diode and a λ / 12 open-circuited microstrip line ML12_1 in parallel at the other end, impedance control of the second and third harmonics can be achieved. This results in a high impedance for the second harmonic and a low impedance for the third harmonic, thus achieving inverse Class F harmonic impedance control, reducing diode losses, and improving rectification efficiency. In addition to impedance control of higher harmonics, the λ / 8 short-circuited microstrip line ML8_1 and the λ / 12 open-circuit microstrip line ML12_1 can also reflect the harmonics back to the diode for re-rectification, increasing energy utilization and improving rectification efficiency. When radio frequency energy flows to the through-pass filter circuit composed of inductor Lout1 and capacitor Cout1, the DC signal rectified by the diode can pass through the through-pass filter circuit. However, radio frequency energy and high-order harmonics will be filtered out by the filter circuit and cannot reach the load resistance RL at the output end. Thus, the through-pass filter circuit ensures the purity of the DC signal at the output end.

[0035] Similarly, the rectifier circuit below works on the same principle. The only difference is that, due to the different placement directions of the two diodes, the DC signal generated by the upper rectifier circuit flows into the load resistor RL, while the DC signal generated by the lower rectifier circuit flows out of the load resistor RL. Thus, a DC signal loop with a top-to-bottom direction is generated, which is a series DC synthesis loop rotating counterclockwise.

[0036] Figure 3This is a DC circuit diagram of the rectifier circuit of the present invention. The DC circuit rotates counterclockwise as a whole, that is, it flows sequentially through diode D1, inductor Lout1, load resistor RL, inductor Lout2, diode D2, microstrip line ML8_2, microstrip line ML8_1, and diode D1, forming a counterclockwise rotating series DC synthesis circuit.

[0037] Figure 4 The simulation and measured results of the rectification efficiency of the rectifier circuit as a function of input power are shown in the figure. As can be seen from the figure, the rectifier circuit operates at 2.5GHz, with a simulated maximum efficiency of 66% (input power = 37dBm) and a measured maximum efficiency of 55% (input power = 37dBm). The measured maximum DC output power reaches 2.7W.

[0038] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A high-power microwave rectifier circuit based on series DC synthesis, characterized in that, It includes a dielectric substrate, a circuit structure disposed on the upper surface of the dielectric substrate, and a metal ground plane disposed on the lower surface of the dielectric substrate; The circuit structure includes a 1-to-2 microstrip power divider, a first rectifier circuit, a second rectifier circuit, a load resistor, a grounding via, and a metal ground plane. The one-to-two microstrip power divider includes one input port and two output ports; the input port is connected to the radio frequency signal input pin, and the two output ports are respectively connected to the first rectifier circuit and the second rectifier circuit. Both the first rectifier circuit and the second rectifier circuit include an inductor, a Schottky diode, a first capacitor, a second capacitor, an open-circuit microstrip line, and a short-circuit microstrip line; In the first rectifier circuit, one end of the first capacitor is connected to the output port of the 1-to-2 microstrip power divider, and the other end is connected to the negative terminal of the Schottky diode, the inductor, and the open-circuit microstrip line; the positive terminal of the Schottky diode is connected to one end of the short-circuit microstrip line; the other end of the short-circuit microstrip line is connected to the metal ground plane through a grounding via; the other end of the inductor is connected to the load resistor and the second capacitor; the other end of the second capacitor is connected to the metal ground plane through a grounding via. In the second rectifier circuit, one end of the first capacitor is connected to the output port of the 1-to-2 microstrip power divider, and the other end is connected to the positive terminal of the Schottky diode, the inductor, and the open-circuit microstrip line; the negative terminal of the Schottky diode is connected to one end of the short-circuit microstrip line; the other end of the short-circuit microstrip line is connected to the metal ground plane through a grounding via; the other end of the inductor is connected to the other end of the load resistor and the second capacitor; the other end of the second capacitor is connected to the metal ground plane through a grounding via.

2. The high-power microwave rectifier circuit based on series DC synthesis as described in claim 1, characterized in that, The open-circuit microstrip line is a λ / 12 microstrip line, and the short-circuit microstrip line is a λ / 8 microstrip line.

3. A high-power microwave rectifier circuit based on series DC synthesis as described in claim 1 or 2, characterized in that, The first capacitor and the second capacitor are Murata capacitors, and the inductor is a Murata inductor.

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