Wireless power transfer system based on semi-active rectifier

Abstract

The invention discloses a wireless power transmission system based on a semi-active rectifier, comprising an input power supply V in , transmitting side inverter unit, transmitting side compensation circuit, transmitting coil L p , receiving coil L s , receiving side compensation circuit, receiving side semi-active rectifier and load R L The present invention replaces an active bridge arm of the full-bridge active rectifier with a passive bridge arm composed of two diodes that does not require control. This method simplifies the rectifier control while ensuring the soft switching of all switch tubes on the receiving side, and uses the passive rectification characteristics of the passive bridge arm to simplify the secondary side resonant current zero-crossing sampling circuit. The designed output voltage control and secondary side resonant current zero-crossing detection circuit has a simple circuit, is convenient to control, is easy to implement, and has good application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of direct current to direct current converters of electric energy conversion devices, and in particular to a wireless power transmission system based on a semi-active rectifier. Background Art

[0002] In recent years, with the vigorous development of new energy electric vehicles, contact-type wired charging solutions have problems such as bulky connectors, complicated operation, easy wear, poor reliability, and easy leakage in rainy and snowy weather. In addition, the length and drag of the transmission cables limit the flexibility of charging and the maintenance cost is high. The above reasons have greatly restricted the application and promotion of new energy electric vehicles.

[0003] In order to improve the safety, reliability and flexibility of the charging system, the use of inductive wireless solutions for energy transmission has become a hot topic of research today. Compared with the traditional plug-in charging method, the use of wireless power transmission technology to power electric vehicles can realize the charging of electric vehicles at the same time, which is convenient and fast, has a wide range of application scenarios, and can reduce the cost and utilization of urban land. Since there is no direct electrical contact between the on-board end and the power supply end of the electric vehicle, and there are no exposed metal joints, this technology is safer and more reliable, and is not affected by bad weather. It can be combined with technologies such as autonomous driving to achieve automation. Therefore, the many advantages of wireless power transmission technology give it a broad development space in the field of power supply for future transportation systems.

[0004] In the prior art, the full-bridge active rectifier used in the inductive wireless power transmission system is composed of four switching tubes, which has the advantage of flexible control. However, there are many control variables, the need to accurately control the zero voltage conduction time of the switching tube, and the complexity of the secondary side resonant current zero-crossing sampling circuit. These problems limit the rapid development of the inductive wireless power transmission system and are currently an urgent problem to be solved. Summary of the invention

[0005] The purpose of the present invention is to overcome the existing problems of the inductive wireless power transmission system, in which the full-bridge active rectifier is composed of four switch tubes. The wireless power transmission system based on the semi-active rectifier provided by the present invention replaces an active bridge arm of the full-bridge active rectifier with a passive bridge arm composed of two diodes that does not require control. This method can simplify the rectifier control while ensuring the soft switching of all the switch tubes on the receiving side, and use the passive rectification characteristics of the passive bridge arm to simplify the secondary side resonant current zero-crossing sampling circuit. The designed output voltage control and secondary side resonant current zero-crossing detection circuit have simple circuits, convenient control, easy implementation, and good application prospects.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A wireless power transmission system based on a semi-active rectifier includes an input power source V in , transmitting side inverter unit, transmitting side compensation circuit, transmitting coil L p , receiving coil L s , receiving side compensation circuit, receiving side semi-active rectifier and load R L ,

[0008] The input power supply V in The output end of the transmitting side inverter unit is connected to the input end of the transmitting side inverter unit, the midpoint of the two bridge arms of the transmitting side inverter unit is connected to the input end of the transmitting side compensation circuit as the output end of the transmitting side inverter unit, and the output end of the transmitting side compensation circuit is connected to the transmitting coil L p Connect to realize wireless transmission of electric energy;

[0009] The receiving coil L s With the transmitting coil L p Magnetic coupling is formed between the transmitting coil L and the receiving coil L p The wirelessly transmitted electrical energy, the receiving coil L s The receiving side compensation circuit is connected to the input end thereof, an output end thereof is connected to the midpoint of the active bridge arm of the receiving side semi-active rectifier, another output end thereof is connected to the midpoint of the passive bridge arm of the receiving side semi-active rectifier, and the output end thereof is connected to the load R L are connected.

[0010] Preferably, the transmitter-side inverter unit is a junction field effect transistor S p1 -S p4 The bridge inverter circuit is composed of.

[0011] Preferably, the receiving side semi-active rectifier includes a passive bridge arm unit, an active bridge arm unit and an output filter capacitor C o The passive bridge arm unit includes a diode D1 and a diode D2; the active bridge arm unit includes a switch tube S s1 , switch tube S s2 ,

[0012] The switch tube S s1 The source of the switch tube S s2 The drain of the receiving side is connected to the active bridge arm midpoint of the receiving side semi-active rectifier and connected to an output end of the receiving side compensation circuit.

[0013] The anode of the diode D1 and the cathode of the diode D2 are connected, and the midpoint of the passive bridge arm of the receiving-side semi-active rectifier is connected to the other output end of the receiving-side compensation circuit.

[0014] The cathode of the diode D1 and the switch tube S s1 The drain is common with the output filter capacitor C o The positive electrode of the diode D2 and the switch tube S s2 The source electrode is common with the output filter capacitor C o The negative pole is connected to

[0015] The output filter capacitor C o The positive and negative electrodes are used as the output terminals of the receiving side semi-active rectifier and the load R L are connected.

[0016] Preferably, it also includes an output voltage control and secondary side resonant current zero-crossing detection circuit, the output voltage control and secondary side resonant current zero-crossing detection circuit includes a switch tube Q1, a main control chip MCU and a switch tube driver chip Driver,

[0017] The other output end of the receiving side compensation circuit is respectively connected to one end of the resistor R1 and the drain of the switch tube Q1, the other end of the resistor R1 is connected to the positive output end of the receiving side semi-active rectifier, the gate of the switch tube Q1 is connected to the power supply of the main control chip MCU, the gate of the switch tube Q1 is also connected to the external trigger pin of the main control chip MCU through the resistor R2, the source of the switch tube Q1 is directly connected to the external trigger pin of the main control chip MCU, the PWM output pin of the main control chip MCU is connected to the input end of the switch tube driver Driver, and the output end of the switch tube driver Driver is respectively connected to the active bridge arm unit switch tube S s1 , switch tube S s2 The gate is connected.

[0018] Preferably, the transmitting side compensation circuit and the receiving side compensation circuit may be a series capacitor compensation circuit, a parallel capacitor compensation circuit, an LCC compensation circuit, or an LCL compensation circuit, so as to meet different load characteristic requirements.

[0019] Preferably, the main control chip MCU can be selected from STM32G474, TMS320F28335 or TMS32F28377 micro integrated IC circuits.

[0020] The switch tube driver Driver can be selected from 2EDF7275KXUMA1 or TPS51604DSGR micro integrated gate drive IC circuit.

[0021] The beneficial effects of the present invention are as follows: the wireless power transmission system based on the semi-active rectifier of the present invention replaces an active bridge arm of the full-bridge active rectifier with a passive bridge arm composed of two diodes that does not require control. This method can simplify the rectifier control while ensuring the soft switching of all the switch tubes on the receiving side, and utilizes the passive rectification characteristics of the passive bridge arm to simplify the secondary side resonant current zero-crossing sampling circuit, and the designed output voltage control and secondary side resonant current zero-crossing detection circuits have simple circuits and convenient control; the semi-active rectifier used in the present invention has only one active bridge arm, which can reduce the control variables on the receiving side, thereby significantly simplifying the control strategy of the active rectifier on the receiving side. At the same time, due to the passive rectification characteristics of the passive bridge arm, all the switch tubes of the semi-active rectifier on the receiving side can realize the zero voltage conduction characteristics, and the output voltage control and secondary side resonant current zero-crossing detection circuits are also simplified to only consist of one switch tube and two resistors, which is easy to implement and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A topological schematic diagram of a wireless power transmission system based on a semi-active rectifier according to the present invention;

[0023] Figure 2 is a circuit diagram of a specific embodiment of the present invention;

[0024] Figure 3 for Figure 2 The main waveform diagram of the embodiment when working;

[0025] Figure 4 for Figure 2 Fundamental wave decoupling equivalent circuit diagram of the system at the resonant frequency of the embodiment;

[0026] Figure 5 for Figure 2 Schematic diagram of the output voltage control and secondary side resonant current zero-crossing detection circuit of the embodiment;

[0027] Figure 6 for Figure 2 A schematic diagram of a modulation strategy for a semi-active rectifier of an embodiment;

[0028] Figure 7 for Figure 2 A timing diagram of the modulation strategy adopted in the embodiment;

[0029] Figure 8 for Figure 2 Voltage and current waveforms of the transmitting side and the receiving side when different couplers have mutual inductance in the embodiments. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with the accompanying drawings.

[0031] Compared with the traditional full-bridge active rectifier used in wireless power transmission systems, which is composed of four switching tubes, there are problems such as many control variables, the need to accurately control the zero voltage conduction time of the switching tubes, and the complex secondary resonant current zero-crossing sampling circuit. The wireless power transmission system based on the semi-active rectifier of the present invention reduces the control parameters of the active rectifier on the receiving side by replacing an active bridge arm of the traditional full-bridge active rectifier with a passive bridge arm, thereby simplifying the control strategy on the receiving side. In addition, due to the passive rectification characteristics of the passive bridge arm, all the switching tubes of the semi-active rectifier on the receiving side can achieve zero voltage conduction characteristics without additional control. At the same time, the output voltage control and the secondary resonant current zero-crossing detection circuit are also simplified to only consist of one switching tube and two resistors, such as Figure 1 As shown, including the input power supply V in , transmitting side inverter unit, transmitting side compensation circuit, transmitting coil L p , receiving coil L s , receiving side compensation circuit, receiving side semi-active rectifier and load R L ,

[0032] The input power supply V in The output end of the transmitting side inverter unit is connected to the input end of the transmitting side inverter unit, the midpoint of the two bridge arms of the transmitting side inverter unit is connected to the input end of the transmitting side compensation circuit as the output end of the transmitting side inverter unit, and the output end of the transmitting side compensation circuit is connected to the transmitting coil L p Connect to realize wireless transmission of electric energy;

[0033] The receiving coil L s With the transmitting coil L p Magnetic coupling is formed between the transmitting coil L and the receiving coil L p The wirelessly transmitted electrical energy, the receiving coil L s The receiving side compensation circuit is connected to the input end thereof, an output end thereof is connected to the midpoint of the active bridge arm of the receiving side semi-active rectifier, another output end thereof is connected to the midpoint of the passive bridge arm of the receiving side semi-active rectifier, and the output end thereof is connected to the load R L are connected.

[0034] Preferably, the transmitter-side inverter unit is a junction field effect transistor S p1 -S p4 The bridge inverter circuit is composed of.

[0035] Preferably, the receiving side semi-active rectifier includes a passive bridge arm unit, an active bridge arm unit and an output filter capacitor C o The passive bridge arm unit includes a diode D1 and a diode D2; the active bridge arm unit includes a switch tube S s1, switch tube S s2 ,

[0036] The switch tube S s1 The source of the switch tube S s2 The drain of the receiving side is connected to the active bridge arm midpoint of the receiving side semi-active rectifier and connected to an output end of the receiving side compensation circuit.

[0037] The anode of the diode D1 and the cathode of the diode D2 are connected, and the midpoint of the passive bridge arm of the receiving-side semi-active rectifier is connected to the other output end of the receiving-side compensation circuit.

[0038] The cathode of the diode D1 and the switch tube S s1 The drain is common with the output filter capacitor C o The positive electrode of the diode D2 and the switch tube S s2 The source electrode is common with the output filter capacitor C o The negative pole is connected to

[0039] The output filter capacitor C o The positive and negative electrodes are used as the output terminals of the receiving side semi-active rectifier and the load R L are connected.

[0040] Preferably, it also includes an output voltage control and secondary side resonant current zero-crossing detection circuit, the output voltage control and secondary side resonant current zero-crossing detection circuit includes a switch tube Q1, a main control chip MCU and a switch tube driver chip Driver,

[0041] The other output end of the receiving side compensation circuit is respectively connected to one end of the resistor R1 and the drain of the switch tube Q1, the other end of the resistor R1 is connected to the positive output end of the receiving side semi-active rectifier, the gate of the switch tube Q1 is connected to the power supply of the main control chip MCU, the gate of the switch tube Q1 is also connected to the external trigger pin of the main control chip MCU through the resistor R2, the source of the switch tube Q1 is directly connected to the external trigger pin of the main control chip MCU, the PWM output pin of the main control chip MCU is connected to the input end of the switch tube driver Driver, and the output end of the switch tube driver Driver is respectively connected to the active bridge arm unit switch tube S s1 , switch tube S s2 The gate is connected.

[0042] Preferably, the transmitting side compensation circuit and the receiving side compensation circuit may be a series capacitor compensation circuit, a parallel capacitor compensation circuit, an LCC compensation circuit, or an LCL compensation circuit, so as to meet different load characteristic requirements.

[0043] Preferably, the main control chip MCU can be selected from STM32G474, TMS320F28335 or TMS32F28377 micro integrated IC circuits.

[0044] The switch tube driver Driver can be selected from 2EDF7275KXUMA1 or TPS51604DSGR micro integrated gate drive IC circuit.

[0045] The following describes a specific embodiment of the wireless power transmission system based on a semi-active rectifier of the present invention, and analyzes the following. Figure 2 The transmitter side compensation circuit is an LCC compensation circuit, and the receiver side compensation circuit is a series compensation circuit. Figure 1 A compensation circuit combination is shown in FIG. 1 . The following is an analysis taking this circuit as an example.

[0046] like Figure 3 For the present invention Figure 2 The main waveforms of the working embodiment, the upper part of the figure is the waveform of the full-bridge inverter, the full-bridge inverter is mainly composed of 4 switch tubes, the duty cycle of all switches is 50%, and the upper and lower switch tubes of the same bridge arm are complementary. In the inverter waveform, α is the phase shift angle between the two bridge arms of the inverter. According to Fourier analysis, the inverter output voltage u p The effective value of the AC component U p for

[0047]

[0048] The transmitter side compensation circuit adopts LCC compensation topology, L r is the series compensation inductor, C p is the series compensation capacitor, C r For parallel compensation capacitors, the calculation formula for the compensation element is:

[0049]

[0050] Figure 3 The lower middle part is the waveform of the receiving side semi-active rectifier. The passive bridge arm diode of the semi-active rectifier follows the secondary side resonant current i s Passive conduction, when the resonant current flows forward, the diode D1 is turned on, and when the resonant current flows in the reverse direction, the diode D2 is turned on. The two MOSFETs of the active bridge arm are complementary turned on, and the duty cycle is 50%. β is the phase shift angle between the active bridge arm and the passive bridge arm. According to Fourier analysis, the rectifier input voltage u s The effective value of the AC component U s for

[0051]

[0052] It should be noted that since only one bridge arm of the semi-active rectifier can be controlled, the receiving side voltage u s Will lag the secondary coil current i s Phase Difference .

[0053] The receiving side compensation circuit is a series compensation circuit, with a series compensation capacitor C s The calculation formula is

[0054]

[0055] like Figure 4 For the present invention Figure 2 The fundamental wave decoupling equivalent circuit of the system at the resonant frequency of the embodiment is sufficiently accurate for a high-quality resonant circuit operating at the resonant frequency. s and R p Represent the loss resistance of the coupler transmitting coil, receiving coil and resonant capacitor respectively, R Lr Represents the equivalent loss resistance of the series compensation inductor, the mutual inductance is equivalent to the controlled voltage source, the inverter is equivalent to the AC power supply, and the active rectifier is equivalent to the equivalent reactance. According to the equivalent circuit in the figure, Figure 5 The voltage-current vector relationship of the resonant circuit can be expressed as

[0056]

[0057] Where ω0=2πf s , because the circuit R Lr , R p and R s It is much smaller than ω0M, so it is omitted in the above formula.

[0058] General With Substituting into the above formula, we can get the output voltage V of the system when it is fully loaded. o The relationship between the inverter phase shift angle α and the semi-active rectifier phase shift angle β is

[0059]

[0060] From the above formula, we can know that the output voltage V of the system when fully loaded o It is positively correlated with the inverter phase shift angle α and negatively correlated with the rectifier phase shift angle β. Therefore, the output voltage can be controlled by coordinated control of the transmitting-side inverter and the receiving-side semi-active rectifier.

[0061] like Figure 5 For the present invention Figure 2 The output voltage control and secondary resonant current zero-crossing detection circuit of the embodiment, the main function of the circuit in the figure is to convert the amplitude to Vo The midpoint voltage V of the passive bridge arm of the semi-active rectifier mid Converted into a 3.3V signal V that can be accepted by the main control chip MCU zcd The principle is that when the midpoint voltage of the passive bridge arm V mid When the gate-source voltage of the switch tube Q1 is high, the switch tube Q1 remains off. zcd is pulled up to 3.3V by resistor R2. When the midpoint voltage of the passive bridge arm V mid When the voltage is low, the switch tube Q1 will not conduct first, and the body diode of the switch tube will turn the signal V zcd Pull it down to a low level, at this time the gate-source voltage of the switch tube Q1 is equal to 3.3V, the switch tube Q1 will be turned on, further pulling down the signal V zcd The PWM counter of the active bridge arm is set using V zcd Triggered by the rising edge of the signal. Figure 3 From the working principle of the semi-active rectifier, we know that the midpoint voltage V mid and the secondary resonant current i s The phase is consistent, so by sampling the voltage V zcd The rising edge of the secondary resonant current i can be accurately sampled s Passing zero.

[0062] like Figure 6 For the present invention Figure 2 The modulation strategy of the semi-active rectifier of the embodiment, the actual output voltage V o With the required output voltage V ref The error value is used to generate the phase shift angle β of the secondary active rectifier through a proportional-integral closed loop to control the output voltage. Figure 7 The present invention is shown Figure 2 The modulation strategy timing diagram adopted in the embodiment, since the diodes D1 and D2 are uncontrolled rectifiers, the synchronization signal V zcd The resonant current i s The present invention utilizes the signal V zcd The rising edge of resets the timer of the active bridge arm PWM to achieve synchronization of the drive signals of the receiving side semi-active rectifier and the transmitting side inverter. In the figure, the comparison value Comp1 is half a cycle larger than Comp2 to achieve a duty cycle of 50% for the upper and lower switches of the active bridge arm. The modulation of the phase shift angle β is achieved by adjusting and changing the comparison value Comp2.

[0063] According to the above-described implementation method, a 100W prototype was built in the laboratory, and its main parameters are shown in Table 1.

[0064] Table 1 Main parameters of the experimental prototype

[0065]

[0066] like Figure 8 For the present invention Figure 2 The voltage and current waveforms of the transmitting side and the receiving side when the couplers of different embodiments are mutually inducted are shown in FIG. Figure 8 It can be seen that as the mutual inductance of the coupler decreases, the phase shift angle α of the transmitter inverter gradually increases, and the phase shift angle β of the receiving side semi-active rectifier is also modulated together to ensure that the output voltage Vo meets the requirements. At the same time, it can be seen that the switching of the upper and lower switches of the passive bridge arm of the semi-active rectifier coincides with the commutation time of the secondary resonant current is, and the switching time of the switch in the active bridge arm and the secondary resonant current can ensure the zero voltage turn-on characteristic.

[0067] In summary, the wireless power transmission system based on the semi-active rectifier of the present invention replaces an active bridge arm of the full-bridge active rectifier with a passive bridge arm composed of two diodes that does not require control. This method can simplify the rectifier control while ensuring the soft switching of all the switch tubes on the receiving side, and use the passive rectification characteristics of the passive bridge arm to simplify the secondary side resonant current zero-crossing sampling circuit, and the designed output voltage control and secondary side resonant current zero-crossing detection circuits have simple circuits and convenient control; the semi-active rectifier used in the present invention has only one active bridge arm, which can reduce the control variables on the receiving side, thereby significantly simplifying the control strategy of the active rectifier on the receiving side. At the same time, due to the passive rectification characteristics of the passive bridge arm, all the switch tubes of the semi-active rectifier on the receiving side can achieve zero voltage conduction characteristics, and the output voltage control and secondary side resonant current zero-crossing detection circuits are also simplified to only consist of one switch tube and two resistors, which is easy to implement and has good application prospects.

[0068] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A wireless power transmission system based on a semi-active rectifier, characterized in that: Including input power supply V in , transmitting side inverter unit, transmitting side compensation circuit, transmitting coil L p , receiving coil L s , receiving side compensation circuit, receiving side semi-active rectifier and load R L , The input power supply V in The output end of the transmitting side inverter unit is connected to the input end of the transmitting side inverter unit, the midpoint of the two bridge arms of the transmitting side inverter unit is connected to the input end of the transmitting side compensation circuit as the output end of the transmitting side inverter unit, and the output end of the transmitting side compensation circuit is connected to the transmitting coil L p Connect to realize wireless transmission of electric energy; The receiving coil L s With the transmitting coil L p Magnetic coupling is formed between the transmitting coil L and the receiving coil L p The wirelessly transmitted electrical energy, the receiving coil L s The receiving side compensation circuit is connected to the input end thereof, an output end thereof is connected to the midpoint of the active bridge arm of the receiving side semi-active rectifier, another output end thereof is connected to the midpoint of the passive bridge arm of the receiving side semi-active rectifier, and the output end thereof is connected to the load R L The receiving side semi-active rectifier includes a passive bridge arm unit, an active bridge arm unit and an output filter capacitor C o The passive bridge arm unit includes a diode D1 and a diode D2; the active bridge arm unit includes a switch tube S s1 , switch tube S s2 , The switch tube S s1 The source of the switch tube S s2 The drain of the receiving side is connected to the receiving side, and the midpoint of the active bridge arm of the receiving side semi-active rectifier is connected to an output end of the receiving side compensation circuit. The anode of the diode D1 and the cathode of the diode D2 are connected, and the midpoint of the passive bridge arm of the receiving-side semi-active rectifier is connected to the other output end of the receiving-side compensation circuit. The cathode of the diode D1 and the switch tube S s1 The drain is common with the output filter capacitor C o The positive electrode of the diode D2 and the switch tube S s2 The source electrode is common with the output filter capacitor C o The negative pole is connected to The output filter capacitor C o The positive and negative electrodes are used as the output terminals of the receiving side semi-active rectifier and the load R L Connected, It also includes an output voltage control and secondary side resonant current zero-crossing detection circuit, the output voltage control and secondary side resonant current zero-crossing detection circuit includes a switch tube Q1, a main control chip MCU and a switch tube driver chip Driver, The other output end of the receiving side compensation circuit is respectively connected to one end of the resistor R1 and the drain of the switch tube Q1, the other end of the resistor R1 is connected to the positive output end of the receiving side semi-active rectifier, the gate of the switch tube Q1 is connected to the power supply of the main control chip MCU, the gate of the switch tube Q1 is also connected to the external trigger pin of the main control chip MCU through the resistor R2, the source of the switch tube Q1 is directly connected to the external trigger pin of the main control chip MCU, the PWM output pin of the main control chip MCU is connected to the input end of the switch tube driver Driver, and the output end of the switch tube driver Driver is respectively connected to the active bridge arm unit switch tube S s1 , switch tube S s2 The gate is connected.

2. The wireless power transmission system based on a semi-active rectifier according to claim 1, characterized in that: The transmitting side inverter unit is a junction field effect transistor S p1 -S p4 The bridge inverter circuit is composed of.

3. The wireless power transmission system based on a semi-active rectifier according to claim 1, characterized in that: The transmitting side compensation circuit and the receiving side compensation circuit are a series capacitor compensation circuit, a parallel capacitor compensation circuit, an LCC compensation circuit, and an LCL compensation circuit, which are used to meet different load characteristic requirements.

4. The wireless power transmission system based on a semi-active rectifier according to claim 3, characterized in that: The main control chip MCU is selected from STM32G474, TMS320F28335 or TMS32F28377 micro integrated IC circuit, The switch tube driver Driver uses a 2EDF7275KXUMA1 or TPS51604DSGR micro integrated gate drive IC circuit.

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