Method for calculating power and efficiency of phase-shift full-bridge LCC-S wireless power transmission system

Abstract

The application provides a method for calculating power and efficiency of a phase-shift full-bridge LCC-S wireless power transmission system, and relates to the field of wireless power transmission, and the method comprises the following steps: determining the voltage of an inverter output end; determining an equivalent load resistance containing a rectifier bridge, a filter capacitor and a load; determining the receiving end impedance, the reflected impedance, the input end inverter equivalent load impedance and the transmitting end impedance, and then determining the active power of the input power; determining the current flowing through the transmitting coil and the current flowing through the receiving coil according to the KVL equation, and determining the active power in the output power; and obtaining the output efficiency based on the active power in the input power and the active power in the output power. The application can calculate the relatively accurate output power and output efficiency of the circuit system, the calculation process has strong reproducibility and operability, and provides strong theoretical support for the design of the wireless power transmission system.

Description

Technical Field

[0001] This invention relates to the field of wireless power transmission, and more particularly to a method for calculating the power and efficiency of a phase-shifted full-bridge LCC-S wireless power transmission system. Background Technology

[0002] Wireless power transfer technology is a charging and energy transfer method that utilizes invisible soft media (such as electric fields, magnetic fields, etc.) in space to transfer electrical energy from the power source to the user device. Because no physical contact is required during power transfer, it greatly increases the flexibility of power supply. Furthermore, wireless power transfer technology transfers energy through coil coupling, which is more flexible and safer than traditional wire connections. Existing power conversion efficiency (referred to as "efficiency") for wireless power transfer systems is... η ) and output power (abbreviated as "power", English notation is P The calculation formulas / methods are mainly based on: 1) experimental method and 2) theoretical method. The experimental method involves actual measurement and analysis of the physical system (built, fabricated, or purchased) under a given operating condition (i.e., load resistance, input voltage, coil distance) using an oscilloscope or power analyzer. The theoretical method does not require physical components; it directly inputs any given circuit parameters and, based on one or more theoretically derived calculation formulas, obtains the efficiency and power values ​​in one step. However, the experimental method has the following drawbacks: complex wiring for physical experiments; only one operating condition can be measured at a time, making it impossible to quickly measure multiple operating conditions in batches; therefore, it inherently lacks scalability; and it relies on expensive measuring instruments. The (existing) theoretical method has the following drawbacks: it only considers simple circuit topologies (referred to as "topology," meaning a specific circuit element and its interconnections), without considering detailed topologies (such as the "phase-shifted full-bridge LCC-S" topology). Summary of the Invention

[0003] To address the limitations of existing technologies in handling complex circuit topologies, rapidly measuring multiple points in batches, and the high cost associated with complex physical wiring, this invention provides a method for calculating the power and efficiency of a phase-shifted full-bridge LCC-S wireless power transfer system. This system includes: a voltage source U for providing DC voltage. d Switches Q1, Q2, Q3, and Q4 form a rectifier bridge to achieve rectification; diodes D1, D2, D3, and D4 form a compensation bridge; capacitors C1, C2, and C3 form a compensation bridge. p C s Compensating inductor L1, line resistors R1 and R2, load resistor R L A pair of coupled inductors including a transmitting coil and a receiving coil; wherein Q1 and Q4 switch simultaneously, Q2 and Q3 switch simultaneously, and the two sets of switching transistors are alternately turned on to realize DC-AC inversion;

[0004] Voltage source Ud The positive terminals of transistors Q1 and Q2 are connected in parallel to each other. The emitter of transistor Q1 is connected to the collector of transistor Q3 and one end of inductor L1, respectively. The emitters of transistors Q3 and Q4 are connected to voltage source U. d The negative terminal of each of the switching transistors Q1, Q2, Q3, and Q4 contains an internal body diode between its collector and emitter. Switches Q1 and Q4 are connected to the same trigger voltage, while Q2 and Q3 are connected to a different trigger voltage with the same frequency and magnitude. Q4 lags Q1 by 180 degrees, and Q3 lags Q2 by 180 degrees. The emitter of switch Q2 is connected to the collector of switch Q4 and one end of resistor R1. The collector of switch Q4 is also connected to the other end of inductor L1 through capacitor C1. p Connect the other end of inductor L1 and the coupled inductor transmitting coil L1 respectively. p One end, coupled inductor, emitter coil L p The other end is connected to the other end of resistor R1, and the receiving coil L... s Connect capacitor C to each end s One end is connected to one end of resistor R2, and capacitor C s The other end is connected to the positive terminal of diode D1 and the negative terminal of diode D3, respectively. The other end of resistor R2 is connected to the positive terminal of diode D2 and the negative terminal of diode D4, respectively. The negative terminals of diodes D1 and D2 are connected in parallel to one end of capacitor C2 and load resistor R. L One end of the diode is connected in parallel with the positive terminals of diodes D3 and D4 to capacitor C2. The other end is connected to the load resistor R. L The other end;

[0005] Based on the above system, the method for calculating the output power and output efficiency of the system includes the following steps:

[0006] S1: Determine the voltage at the inverter output terminal based on the voltage-source single-phase bridge inverter topology and the Fourier pole number method; determine the equivalent load resistance including the rectifier bridge, filter capacitor and load based on the single-phase full-wave rectifier circuit topology.

[0007] S2: Determine the equivalent impedance of the receiver based on the inverter output voltage and equivalent load resistance determined in step S1. Z s Reflection impedance Z R Transmitter equivalent impedance Z p Equivalent load impedance of the input inverter Z y This allows us to determine the active power within the input power.

[0008] S3: Determine the current flowing through the transmitting coil and the receiving coil according to the KVL equation, and thus determine the active power in the output power;

[0009] S4: Based on the active power in the input power determined in step S2 and the active power in the output power determined in step S3, the output efficiency is obtained.

[0010] A storage device that stores instructions and data for implementing a method for calculating the power and efficiency of a phase-shifted full-bridge LCC-S wireless power transfer system.

[0011] An apparatus for calculating the power and efficiency of a phase-shifted full-bridge LCC-S wireless power transmission system includes: a processor and a storage device; the processor loads and executes instructions and data in the storage device to implement a method for calculating the power and efficiency of the phase-shifted full-bridge LCC-S wireless power transmission system.

[0012] The beneficial effects of the technical solution provided by this invention are as follows: This invention targets a wireless power transmission system with a "phase-shifted full-bridge LCC-S" topology. Utilizing the fundamental conclusions of Fourier series, it employs a method that treats the power at the output of the phase-shifted full-bridge inverter as the system input power and the total power consumed by the receiving rectifier bridge and the actual load resistance as the system output power. Combined with a series of equivalent transformations, it finally derives calculation formulas for the output power and efficiency of the wireless power transmission system under this specific circuit topology, and its accuracy has been verified through simulation. The calculation process of this invention is clear, reproducible, and highly operable, providing strong theoretical support for the design of wireless power transmission systems. When used in the design of wireless power transmission systems, this invention can quickly and in batches estimate the system output power and efficiency under multiple different operating conditions through the calculation formulas, helping to improve the design efficiency of this type of circuit system and reduce the trial-and-error costs during the development process. Attached Figure Description

[0013] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0014] Figure 1 This is a schematic diagram of the wireless power transmission system based on the "phase-shifted full-bridge LCC-S topology" of the present invention.

[0015] Figure 2 This is a flowchart of the calculation method for output power and output efficiency in this invention.

[0016] Figure 3 This is a diagram showing the results of symbolic formula derivation and calculation using MWORKS software in an embodiment of the present invention.

[0017] Figure 4 This is a simulation model diagram of the test circuit built using Simulink software in an embodiment of the present invention.

[0018] Figure 5 This is a simulation result diagram of Simulink software in an embodiment of the present invention.

[0019] Figure 6 This is a schematic diagram of the hardware device working in an embodiment of the present invention. Detailed Implementation

[0020] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0021] Example 1

[0022] Please refer to Figure 1-2 , Figure 1 This is a flowchart illustrating a method for calculating the power and efficiency of a phase-shifted full-bridge LCC-S wireless power transfer system according to an embodiment of the present invention. Figure 2 This is a schematic diagram of a wireless power transfer system based on the "phase-shifted full-bridge LCC-S" topology. Specifically, the wireless power transfer system based on the "phase-shifted full-bridge LCC-S" topology includes: a voltage source U for providing DC voltage. d The switching transistors Q1, Q2, Q3, and Q4 form a rectifier bridge to achieve rectification; diodes D1, D2, D3, and D4 form a rectifier bridge; and capacitors C1, C2, and C3 are used. p C s Compensating inductor L1, line resistors R1 and R2, load resistor R L A pair of coupled inductors comprising a transmitting coil and a receiving coil; wherein, capacitors C1, C2, and C... p C s These are compensation capacitors for the transmitting and receiving circuits. Q1 and Q4 switch simultaneously, and Q2 and Q3 switch simultaneously. The two sets of switching transistors conduct alternately to achieve DC-AC inversion.

[0023] Voltage source U d The positive terminals of transistors Q1 and Q2 are connected in parallel to each other. The emitter of transistor Q1 is connected to the collector of transistor Q3 and one end of inductor L1, respectively. The emitters of transistors Q3 and Q4 are connected to voltage source U. d The negative terminal of each of the switching transistors Q1, Q2, Q3, and Q4 contains an internal body diode between its collector and emitter. Switches Q1 and Q4 are connected to the same trigger voltage, while Q2 and Q3 are connected to a different trigger voltage with the same frequency and magnitude. Q4 lags Q1 by 180 degrees, and Q3 lags Q2 by 180 degrees. The emitter of switch Q2 is connected to the collector of switch Q4 and one end of resistor R1. The collector of switch Q4 is also connected to the other end of inductor L1 through capacitor C1. p Connect the other end of inductor L1 and the coupled inductor transmitting coil L1 respectively. p One end, coupled inductor, emitter coil L pThe other end is connected to the other end of resistor R1, and the receiving coil L... s Connect capacitor C to each end s One end is connected to one end of resistor R2, and capacitor C s The other end is connected to the positive terminal of diode D1 and the negative terminal of diode D3, respectively. The other end of resistor R2 is connected to the positive terminal of diode D2 and the negative terminal of diode D4, respectively. The negative terminals of diodes D1 and D2 are connected in parallel to one end of capacitor C2 and load resistor R. L One end of the diode is connected in parallel with the positive terminals of diodes D3 and D4 to capacitor C2. The other end is connected to the load resistor R. L At the other end, the bases of switching transistors Q1, Q2, Q3, and Q4 are connected to the circuit related to the trigger signal. In this embodiment, Q1, Q2, Q3, and Q4 are all IGBT type switching transistors. If Q1, Q2, Q3, and Q4 were selected as MOSFET type switching transistors in this embodiment, then the voltage source U... d The positive terminals are connected in parallel to the drains of switching transistors Q1 and Q2, and the source of switching transistor Q1 is connected to the drain of switching transistor Q3 and one end of inductor L1.

[0024] The method for calculating the output power and output efficiency of the wireless power transfer system based on the above-mentioned "phase-shifted full-bridge LCC-S" topology includes the following steps:

[0025] S1: Determine the voltage at the inverter output terminal based on the voltage-source single-phase bridge inverter topology and the Fourier pole number method; determine the equivalent load resistance including the rectifier bridge, filter capacitor and load based on the single-phase full-wave rectifier circuit topology.

[0026] S2: Determine the equivalent impedance of the receiver based on the inverter output voltage and equivalent load resistance determined in step S1. Z s Reflection impedance Z R The equivalent impedance of the transmitter compensation capacitor C1 when viewed from behind. Z p (refer to Figure 2 and the equivalent load impedance of the input inverter Z y This allows us to determine the active power within the input power. The calculation of active power within the input power is based on the voltage and current after passing through the DC-AC inverter, specifically:

[0027] Step A: Determine the voltage after inversion U A Taking a voltage-source single-phase bridge inverter as an example, the voltage becomes a square wave after passing through the DC-AC inverter. Based on the fundamental conclusions of Fourier series, and considering that the fundamental frequency accounts for a much larger proportion than harmonics, the square wave is replaced by the fundamental frequency, resulting in... ,in ω The angular frequency of the fundamental wave.U d If the input DC voltage is the system voltage, then U A The valid values ​​are shown below:

[0028]

[0029] Step B: In the full-wave rectifier circuit, for the load resistor R L In terms of the bridge circuit's input port, its equivalent load resistance is:

[0030]

[0031] Step C: Analyze the receiving loop to obtain the equivalent impedance. Determine the reflection impedance Then, the equivalent impedance of the transmitting circuit is obtained by analysis. ,in M represents the mutual inductance between the coupled inductors. The expressions for each impedance are obtained by rearranging them as follows:

[0032]

[0033] in

[0034] Step D: Calculate the active power in the input power:

[0035]

[0036] Among them, input current , U A_rms for U A The effective value, Z y The input inverter is the equivalent load impedance. Indicates input current I in The conjugate value.

[0037] After substituting, we get:

[0038]

[0039] Substituting the expressions for each quantity into the formula for calculating active power in input power, and expanding, we get:

[0040] ,

[0041] in .

[0042] S3: Determine the current flowing through the transmitting coil and the receiving coil using the KVL equations, and thus determine the active power in the output power; the output power refers to the equivalent load resistance R, including the entire rectifier bridge and filter capacitors. eq The power. The specific steps for calculating the active power in the output power are as follows:

[0043] Step A: Analyze the "phase-shifted full-bridge LCC-S topology" wireless power transfer system, and list loop 1 (the loop consisting of inductor L1, capacitor C1, and inverter output); refer to... Figure 2 The KVL equations for the receiving loop and the receiving loop are as follows:

[0044]

[0045] in, ω The angular frequency of the fundamental wave. M Mutual inductance is used to describe the coupling relationship between a group of coils.

[0046] After solving, we can obtain the current flowing through the transmitting coil L. p current I p and flowing through the receiving coil L s current I s , I p For the flow through the transmitting coil L p The current, I s For the current flowing through the receiving coil L s The current.

[0047] Step B: Calculate the active power in the output power. .

[0048] Expanded to:

[0049] ,

[0050] in, Z s and Z R The expression for has been derived in step C of S3 above.

[0051] The above formula derivation was completed using the scientific computing software MWORKS, and the results are consistent with those derived manually.

[0052] S4: Based on the active power in the input power determined in step S2 and the active power in the output power determined in step S3, the output efficiency is obtained: η = P out / Pin .

[0053] Based on the above technical solution, using MWORKS software, numerical calculations were performed by substituting the following circuit component parameters into the above formula. The example parameters are: U d =15V, L1=6e-6H, C1=4.2217e-7F, L p =30e-6H, L s =14e-6H, C p =1.0554e-7F, C s =1.8093e-7F, R1=0.2Ω, R2=0.2Ω, C2=2.5e-6F, R L =10Ω, M=5e-6H, base voltage frequency f=1e5Hz. Input power calculated using MWORKS is: P in =17.8152w, output power P out =14.8816w, output efficiency eff=83.53% (that is, the output efficiency mentioned above) η ), specifically as Figure 3 As shown.

[0054] Then, Simulink software is used to build such as Figure 4 The detailed circuit model is shown, and the input power, output power, and output efficiency of the circuit are measured using RMS components combined with the definition of power. The measurement results are as follows: Figure 5 As shown, these are: input power P in =17.98w (see) Figure 5 (a)), output power P out =15.02w (see) Figure 5 (b)), output efficiency eff = 83.55% (see Figure 5 (c)). Therefore, the result here is basically consistent with the result obtained from the theoretical calculation using the MWROKS software.

[0055] Example 2

[0056] A device 601 for calculating the power and efficiency of a phase-shifted full-bridge LCC-S wireless power transfer system, such as... Figure 6 As shown, it includes: a processor 602 and a storage device 603; the processor 602 loads and executes instructions and data in the storage device 603 to implement the method for calculating the power and efficiency of the phase-shifted full-bridge LCC-S wireless power transfer system.

[0057] Example 3

[0058] A storage device that stores instructions and data for implementing a method for calculating the power and efficiency of a phase-shifted full-bridge LCC-S wireless power transfer system.

[0059] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for calculating the power and efficiency of a phase-shifted full-bridge LCC-S wireless power transfer system, characterized in that: The system includes: a voltage source U for providing DC voltage. d Switches Q1, Q2, Q3, and Q4 form a rectifier bridge to achieve rectification; diodes D1, D2, D3, and D4 form a compensation bridge; capacitors C1, C2, and C3 form a compensation bridge. p C s Compensating inductor L1, line resistors R1 and R2, load resistor R L A pair of coupled inductors including a transmitting coil and a receiving coil; wherein Q1 and Q4 switch simultaneously, Q2 and Q3 switch simultaneously, and the two sets of switching transistors are alternately turned on to realize DC-AC inversion; Voltage source U d The positive terminals of transistors Q1 and Q2 are connected in parallel to each other. The emitter of transistor Q1 is connected to the collector of transistor Q3 and one end of inductor L1, respectively. The emitters of transistors Q3 and Q4 are connected to voltage source U. d The negative terminal of each of the switching transistors Q1, Q2, Q3, and Q4 contains an internal body diode between its collector and emitter. Switches Q1 and Q4 are connected to the same trigger voltage, while Q2 and Q3 are connected to a different trigger voltage with the same frequency and magnitude. Q4 lags Q1 by 180 degrees, and Q3 lags Q2 by 180 degrees. The emitter of switch Q2 is connected to the collector of switch Q4 and one end of resistor R1. The collector of switch Q4 is also connected to the other end of inductor L1 through capacitor C1. p Connect the other end of inductor L1 and the coupled inductor transmitting coil L1 respectively. p One end, coupled inductor, emitter coil L p The other end is connected to the other end of resistor R1, and the receiving coil L... s Connect capacitor C to each end s One end is connected to one end of resistor R2, and capacitor C s The other end is connected to the positive terminal of diode D1 and the negative terminal of diode D3, respectively. The other end of resistor R2 is connected to the positive terminal of diode D2 and the negative terminal of diode D4, respectively. The negative terminals of diodes D1 and D2 are connected in parallel to one end of capacitor C2 and load resistor R. L One end of the diode is connected in parallel with the positive terminals of diodes D3 and D4 to capacitor C2. The other end is connected to the load resistor R. L The other end; Based on the above system, the method for calculating the output power and output efficiency of the system includes the following steps: S1: Determine the voltage at the inverter output terminal based on the voltage-source single-phase bridge inverter topology and the Fourier pole number method; determine the equivalent load resistance including the rectifier bridge, filter capacitor and load based on the single-phase full-wave rectifier circuit topology. S2: Determine the equivalent impedance of the receiver based on the inverter output voltage and equivalent load resistance determined in step S1. Z s Reflection impedance Z R Transmitter equivalent impedance Z p Equivalent load impedance of the input inverter Z y This allows us to determine the active power within the input power. In step S2, the equivalent impedance of the receiving end Thus, the reflection impedance is determined. ;Analyze the equivalent load impedance of the input inverter ,in , ω Let M represent the operating angular frequency of the circuit, and M represent the mutual inductance between the coupled inductors. The expressions for each impedance are obtained by rearranging the expression as follows: in ; The active power in the input power is: in, U A_rms for U A The effective value, Z y The input inverter is the equivalent load impedance. express Z y The conjugate of the complex number, Re[] denotes the operation of taking the real part of the complex number; U A The voltage after inversion; Substituting the expressions for each quantity into the formula for calculating active power in input power, and expanding, we get: ， in ; S3: Determine the current flowing through the transmitting coil and the receiving coil according to the KVL equation, and thus determine the active power in the output power; S4: Based on the active power of the input power determined in step S2 and the active power of the output power determined in step S3, the output efficiency is obtained.

2. The method for calculating the power and efficiency of a phase-shifted full-bridge LCC-S wireless power transfer system as described in claim 1, characterized in that: In step S1, after passing through the DC-AC inverter, the voltage of the voltage-source single-phase bridge inverter... U A Transforming it into a square wave, replacing the square wave with the fundamental wave, and performing a Fourier series expansion, we obtain... ; U A effective value U A_rms for: in, U A This is the voltage after inversion. ω The angular frequency of the fundamental wave. t For time, U d This is the input DC voltage of the system.

3. The method for calculating the power and efficiency of a phase-shifted full-bridge LCC-S wireless power transfer system as described in claim 1, characterized in that: In step S1, the equivalent load resistance is: Among them, R L This is the load resistance.

4. The method for calculating the power and efficiency of a phase-shifted full-bridge LCC-S wireless power transfer system as described in claim 1, characterized in that: In step S3, according to the KVL equation, we obtain: in, , ω The angular frequency of the fundamental wave. M Indicates mutual intuition; The active power in the output power is: in, I p For the flow through the transmitting coil L p The current, I s For the current flowing through the receiving coil L s The current; Expanded to: 。 5. The method for calculating the power and efficiency of a phase-shifted full-bridge LCC-S wireless power transfer system as described in claim 1, characterized in that: In step S4, the output efficiency is: in, P out The active power in the output power. P in This refers to the active power in the input power.

6. A storage device, characterized in that: The storage device stores instructions and data for implementing the method for calculating the power and efficiency of the phase-shifted full-bridge LCC-S wireless power transmission system as described in any one of claims 1 to 5.

7. A device for calculating the power and efficiency of a phase-shifted full-bridge LCC-S wireless power transfer system, characterized in that: include: A processor and a storage device; the processor loads and executes instructions and data in the storage device to implement the method for calculating the power and efficiency of the phase-shifted full-bridge LCC-S wireless power transmission system as described in any one of claims 1 to 5.

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