Phase detection circuit for output square wave voltage of wireless power transmission high-frequency inverter stage

Abstract

The invention relates to a wireless power transmission high-frequency inverter stage output square wave voltage phase detection circuit. One end of a current-limiting high-voltage non-inductive resistor is connected with the positive electrode output end of a high-frequency inverter; the cathode of the clamping diode is connected with the other end of the current-limiting high-voltage non-inductive resistor, and the anode of the clamping diode is connected with the cathode output end of the high-frequency inverter; the first input end of the optocoupler is connected with a connection node between the current-limiting high-voltage non-inductive resistor and the cathode of the clamping diode, and the second input end of the optocoupler is respectively connected with the anode of the clamping diode and the cathode output end of the high-frequency inverter; the first input end of the phase discrimination circuit is connected with the first output end of the optocoupler, the second input end of the phase discrimination circuit is connected with the second output end of the optocoupler, and the phase discrimination circuit is used for outputting phase information of the square wave to be detected. The problems of estimation delay and distortion occurring in a power electronic system during phase detection are solved, the real-time performance and accuracy of phase detection are improved, and the method is convenient to implement, simple in design and low in cost.

Description

Technical Field

[0001] The invention relates to the technical field of power electronics, and in particular to a wireless power transmission high-frequency inverter output square wave voltage phase detection circuit. Background Art

[0002] At the transmitting end of magnetically coupled resonant wireless power transmission, there is usually a high-frequency inverter stage based on power electronics, which efficiently converts DC or industrial frequency electrical energy into high-frequency AC with a frequency of tens of kHz or higher to excite the transmitting coil and its resonant circuit. Due to the strong resonance characteristics of the back-end load, the above-mentioned high-frequency inverter stage usually outputs electrical energy directly in the form of a high-frequency square wave voltage, which is then filtered by the back-end resonant circuit into a high-frequency sinusoidal current of the same frequency. For some high-performance control strategies, such as maximum efficiency point tracking control, primary and secondary bidirectional switching coordinated control, etc., the precise phase information of the above-mentioned square wave voltage is required, and the time accuracy of phase detection often directly affects the control performance.

[0003] In the related art, there are usually two methods to obtain phase information. One is to infer the phase of the power stage output voltage through the control pulse sent by the control system. The other is to detect the output voltage value through the voltage sensor, and then obtain its phase information through the conditioning circuit and the phase detection circuit. The function of the phase detection circuit can also be realized by the core controller.

[0004] However, in power electronic systems, unpredictable delays and distortions will inevitably occur from control pulses to drive pulses and then to energy pulses, resulting in reduced accuracy of the obtained phase information. In addition, high-frequency square waves contain very rich high-frequency components, and the bandwidth of conventional voltage sensors is difficult to meet the requirements. At the same time, the accompanying conditioning circuit will also introduce signal delays and distortions, making it difficult to achieve real-time and accurate phase detection, which needs to be solved urgently. Summary of the invention

[0005] The present invention provides a wireless power transmission high frequency inverter stage output square wave voltage phase detection circuit to solve the problem of estimated delay and distortion in power electronic systems during phase detection, which can significantly reduce the delay of the detection system and improve the phase detection accuracy, and has the advantages of easy implementation, simple design and low cost.

[0006] The first aspect of the present invention provides a wireless power transmission high-frequency inverter stage output square wave voltage phase detection circuit, including: a current-limiting high-voltage non-inductive resistor, one end of the current-limiting high-voltage non-inductive resistor is connected to the positive output end of the high-frequency inverter; a clamping diode, the cathode of the clamping diode is connected to the other end of the current-limiting high-voltage non-inductive resistor, and the anode of the clamping diode is connected to the negative output end of the high-frequency inverter; an optical coupler, the first input end of the optical coupler is connected to the connection node between the current-limiting high-voltage non-inductive resistor and the cathode of the clamping diode, and the second input end of the optical coupler is respectively connected to the anode of the clamping diode and the negative output end of the high-frequency inverter; a phase detection circuit, the first input end of the phase detection circuit is connected to the first output end of the optical coupler, and the second input end of the phase detection circuit is connected to the second output end of the optical coupler, for outputting the phase information of the square wave to be detected.

[0007] Furthermore, in some embodiments, the resistance of the current-limiting high-voltage non-inductive resistor is determined by the maximum current limit of the clamping diode and the normal operating current value of the optocoupler.

[0008] Furthermore, in some embodiments, the voltage withstand capability of the current-limiting high-voltage non-inductive resistor is greater than 1.5 times the voltage amplitude of the square wave to be detected.

[0009] Furthermore, in some embodiments, the operating frequency of the optical coupler is higher than the maximum voltage frequency of the square wave to be detected.

[0010] Furthermore, in some embodiments, the forward conduction voltage drop of the clamping diode is less than the maximum reverse withstand voltage value of the light-emitting diode in the optocoupler, and the maximum reverse withstand voltage value of the clamping diode is greater than the forward conduction voltage drop of the light-emitting diode in the optocoupler.

[0011] Furthermore, in some embodiments, the phase detection circuit adopts an edge triggered circuit.

[0012] Furthermore, in some embodiments, the phase detection circuit adopts a capture module in a DSP.

[0013] Furthermore, in some embodiments, the wireless power transmission high-frequency inverter stage output square wave voltage phase detection circuit also includes: a pull-up resistor, one end of the pull-up resistor is connected to the power access node, and the other end of the pull-up resistor is respectively connected to the first output end of the optocoupler and the first input end of the phase detection circuit.

[0014] Furthermore, in some embodiments, the wireless power transmission high-frequency inverter stage output square wave voltage phase detection circuit further includes: a power supply component, the output end of the power supply component is connected to one end of the pull-up resistor through the power access node.

[0015] According to the wireless power transmission high-frequency inverter output square wave voltage phase detection circuit provided by the embodiment of the present invention, the current can be limited by a high-voltage non-inductive resistor, so that the power level output voltage directly drives the optocoupler, realizes the judgment of the output voltage polarity, and ensures the isolation of the power level and the signal level. The problem of estimated delay and distortion in the power electronic system during phase detection is solved, and the real-time and accuracy of phase detection are improved.

[0016] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0018] Figure 1 It is a schematic diagram of the structure of a typical wireless power transmission system;

[0019] Figure 2 It is a schematic diagram of the structure of a traditional square wave voltage phase detection system;

[0020] Figure 3 Schematic diagram of the structure of a square wave voltage phase detection circuit output by a wireless power transmission high frequency inverter stage according to an embodiment of the present invention. DETAILED DESCRIPTION

[0021] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0022] Before introducing the wireless power transmission high frequency inverter output square wave voltage phase detection circuit according to the embodiment of the present invention, the structure of a typical wireless power transmission system and the schematic diagram of the structure of a traditional square wave voltage phase detection system are briefly introduced.

[0023] Specifically, Figure 1 As shown, Figure 1 The schematic diagram of the structure of a typical wireless power transmission system is shown in Figure 1. The structure of the typical wireless power transmission system includes a high-frequency inverter, a resonant network, a high-frequency rectifier, and a phase detection device. The output of the high-frequency inverter stage at the transmitter is a bipolar high-frequency square wave voltage. In some high-performance controls, a phase detection circuit needs to be installed here.

[0024] Furthermore, if Figure 2 As shown, Figure 2The figure is a schematic diagram of the structure of a traditional square wave voltage phase detection system. The traditional square wave voltage phase detection method includes a high-frequency inverter, a back-end circuit, a voltage sensor VS, a conditioning circuit, and a phase monitoring circuit. Among them, the voltage sensor VS is usually used to convert the power level voltage into a proportional weak current signal, and then the phase information is obtained through the conditioning circuit and the phase detection circuit.

[0025] However, the accuracy of the phase information detected by the above traditional method will be reduced. Based on the above problem, the present invention proposes a wireless power transmission high-frequency inverter stage output square wave voltage phase detection circuit. The circuit can limit the current through a high-voltage non-inductive resistor, so that the power stage output voltage directly drives the optocoupler, realizes the judgment of the output voltage polarity, and ensures the isolation of the power stage and the signal level, which solves the problems of estimated delay and distortion in the power electronic system during phase detection.

[0026] Figure 3 A schematic diagram of the structure of a square wave voltage phase detection circuit for a high frequency inverter stage output of wireless power transmission provided by an embodiment of the present invention.

[0027] like Figure 3 As shown, the wireless power transmission high frequency inverter output square wave voltage phase detection circuit 10 includes: a current limiting high voltage non-inductive resistor R1, a clamping diode D1, an optical coupler OP1 and a phase detection circuit 100.

[0028] Among them, one end of the current-limiting high-voltage non-inductive resistor R1 is connected to the positive output end of the high-frequency inverter; the clamping diode D1, the cathode of the clamping diode D1 is connected to the other end of the current-limiting high-voltage non-inductive resistor R1, and the anode of the clamping diode D1 is connected to the negative output end of the high-frequency inverter; the first input end of the optical coupler OP1 is connected to the connection node between the current-limiting high-voltage non-inductive resistor R1 and the cathode of the clamping diode D1, and the second input end of the optical coupler OP1 is respectively connected to the anode of the clamping diode D1 and the negative output end of the high-frequency inverter; the first input end of the phase detection circuit 100 is connected to the first output end of the optical coupler OP1, and the second input end of the phase detection circuit 100 is connected to the second output end of the optical coupler OP1, for outputting the phase information of the square wave to be detected.

[0029] Furthermore, in some embodiments, the resistance of the current-limiting high-voltage non-inductive resistor R1 is determined by the maximum current limit of the clamping diode D1 and the normal operating current value of the optocoupler OP1.

[0030] Among them, the current-limiting high-voltage non-inductive resistor R1 is connected in series with the clamping diode D1 and the optocoupler OP1, and its resistance value should meet the current limiting requirements of the clamping diode D1 and the optocoupler OP1, that is, when the square wave voltage to be measured is positive, the current flowing through the light-emitting diode in the optocoupler OP1 meets the normal working requirements of the optocoupler; when the square wave voltage to be measured is negative, the current flowing through the clamping diode D1 does not exceed its maximum current limit.

[0031] Furthermore, in some embodiments, the voltage withstand capability of the current-limiting high-voltage non-inductive resistor R1 is greater than 1.5 times the voltage amplitude of the square wave to be detected.

[0032] It should be noted that the voltage withstand capability of the current limiting high-voltage non-inductive resistor R1 is a key parameter, which ensures that the resistor will not be damaged due to excessive voltage under normal working conditions, so as to ensure that the resistor can withstand possible voltage fluctuations or transient overvoltages.

[0033] Furthermore, in some embodiments, the operating frequency of the optical coupler OP1 is higher than the highest voltage frequency of the square wave to be detected.

[0034] Among them, the isolation voltage level should meet the isolation requirements of the system power level and signal level.

[0035] Furthermore, in some embodiments, the forward conduction voltage drop of the clamping diode D1 is less than the maximum reverse withstand voltage of the light emitting diode in the optocoupler OP1, and the maximum reverse withstand voltage of the clamping diode D1 is greater than the forward conduction voltage drop of the light emitting diode in the optocoupler OP1.

[0036] Wherein, the clamping diode D1 and the optical coupler OP1 are connected in anti-parallel.

[0037] Furthermore, in some embodiments, the phase detection circuit 100 adopts an edge triggered circuit.

[0038] The phase detection circuit 100 adopts an edge-triggered circuit to achieve low power consumption, simple structure, and maintain a wide phase detection range without a dead zone in phase detection accuracy.

[0039] Furthermore, in some embodiments, the phase detection circuit 100 adopts a capture module in a DSP.

[0040] Among them, the capture module in DSP is used to realize the phase detection circuit, which can make full use of the high-speed processing capability and rich peripheral resources of DSP to achieve high-precision phase detection.

[0041] Furthermore, in some embodiments, Figure 3 As shown, the wireless power transmission high-frequency inverter stage output square wave voltage phase detection circuit 10 also includes: a pull-up resistor R2, one end of the pull-up resistor R2 is connected to the power access node, and the other end of the pull-up resistor R2 is respectively connected to the first output end of the optical coupler OP1 and the first input end of the phase detection circuit 100.

[0042] Furthermore, in some embodiments, the wireless power transmission high frequency inverter stage output square wave voltage phase detection circuit 10 further includes: a power supply component, the output end of the power supply component is connected to one end of the pull-up resistor R2R2 through a power access node.

[0043] The phase detection process of the square wave voltage output by the high-frequency inverter stage of wireless power transmission will be described in detail below in conjunction with specific embodiments.

[0044] Among them, the current-limiting high-voltage non-inductive resistor R1 is connected in series with the light-emitting diode of the optocoupler OP1 and then connected in parallel to the output end of the H bridge. The clamping diode D1 is connected in anti-parallel with the light-emitting diode of the optocoupler OP1; the pull-up resistor R2 may be omitted or replaced with other configurations depending on the output form of the optocoupler OP1; the phase detection circuit 100 may be implemented by a capture module in a core controller (such as a DSP) or by a dedicated external functional circuit.

[0045] For example, under the current limiting effect of the current limiting high-voltage non-inductive resistor R1, u1 turns on the light-emitting diode in the optocoupler OP1, and the output level of the optocoupler OP1 is 0. At this time, the clamping diode D1 is subjected to the conduction voltage drop of the light-emitting diode in the optocoupler OP1.

[0046] For example, when u1 is negative, the clamping diode D1 is turned on. At this time, the current-limiting high-voltage non-inductive resistor R1 also plays a current-limiting role. The light-emitting diode of the optocoupler OP1 is cut off, and its reverse pressure is the conduction voltage drop of the clamping diode D1. The output level of the optocoupler OP1 is 1.

[0047] Among them, u1 is the output voltage of the high-frequency inverter, which can use a 100kHz square wave of -350V to 350V. The optocoupler OP1 can select TLP2368, whose transmission rate can reach 20MBd, which can fully meet the 100kHz frequency requirement, and its isolation voltage is 3750Vrms, which can also meet the isolation requirements of the present invention. The current-limiting high-voltage non-inductive resistor R1 is used as the current-limiting resistor, and a 25k / 10W high-voltage non-inductive resistor can be selected. In this way, the current flowing through the light-emitting diode in the optocoupler OP1 is about 14mA, which meets the recommended input current value of the optocoupler OP1. At this time, the resistance loss is about 4.9W. The clamping diode D1 can be FDLL4448, whose maximum on-state current is 300mA, which is sufficient to meet the above-mentioned 14mA requirement; its on-state voltage drop is less than 1V, which is much smaller than the 5V reverse withstand voltage of the light-emitting diode in the optocoupler OP1; its reverse withstand voltage is 100V, which is also much smaller than the on-state voltage drop of the light-emitting diode in the optocoupler OP1, so the clamping diode D1 and the optocoupler OP1 can play a role of mutual clamping.

[0048] Therefore, the power-level square wave voltage u1 output by the H-bridge can directly drive the optocoupler OP1, so that a signal-level pulse with the same frequency and opposite phase as u1 is obtained at the output end of the optocoupler OP1, and then processed by the back-end phase detection circuit 100 to obtain accurate and real-time u1 phase information.

[0049] According to the wireless power transmission high-frequency inverter output square wave voltage phase detection circuit provided by the embodiment of the present invention, the current can be limited by a high-voltage non-inductive resistor, so that the power level output voltage directly drives the optocoupler, realizes the judgment of the output voltage polarity, and ensures the isolation of the power level and the signal level. It solves the problem of estimated delay and distortion in the power electronic system during phase detection, can significantly reduce the delay of the detection system, improve the phase detection accuracy, and has the advantages of easy implementation, simple design, and low cost.

[0050] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0051] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "N" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0052] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or more executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present invention includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present invention belong.

[0053] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above embodiment, the N steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0054] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

Claims

1. A wireless power transmission high frequency inverter output square wave voltage phase detection circuit, characterized in that: include: A current-limiting high-voltage non-inductive resistor, one end of which is connected to the positive output end of the high-frequency inverter; A clamping diode, wherein the cathode of the clamping diode is connected to the other end of the current-limiting high-voltage non-inductive resistor, and the anode of the clamping diode is connected to the negative output end of the high-frequency inverter; An optical coupler, wherein a first input end of the optical coupler is connected to a connection node between the current-limiting high-voltage non-inductive resistor and the cathode of the clamping diode, and a second input end of the optical coupler is respectively connected to an anode of the clamping diode and a negative output end of the high-frequency inverter; A phase detection circuit, wherein a first input end of the phase detection circuit is connected to a first output end of the optical coupler, and a second input end of the phase detection circuit is connected to a second output end of the optical coupler, and is used to output phase information of a square wave to be detected.

2. The wireless power transmission high frequency inverter output square wave voltage phase detection circuit according to claim 1, characterized in that: The resistance value of the current-limiting high-voltage non-inductive resistor is determined by the maximum current limit of the clamping diode and the normal operating current value of the optocoupler.

3. The wireless power transmission high frequency inverter output square wave voltage phase detection circuit according to claim 2, characterized in that: The voltage-withstanding capability of the current-limiting high-voltage non-inductive resistor is greater than 1.5 times the voltage amplitude of the square wave to be detected.

4. The wireless power transmission high frequency inverter output square wave voltage phase detection circuit according to claim 3, characterized in that: The operating frequency of the optical coupler is higher than the maximum voltage frequency of the square wave to be detected.

5. The wireless power transmission high frequency inverter output square wave voltage phase detection circuit according to claim 1, characterized in that: The forward conduction voltage drop of the clamping diode is less than the maximum reverse withstand voltage value of the light emitting diode in the optocoupler, and the maximum reverse withstand voltage value of the clamping diode is greater than the forward conduction voltage drop of the light emitting diode in the optocoupler.

6. The wireless power transmission high frequency inverter output square wave voltage phase detection circuit according to claim 1, characterized in that: The phase detection circuit adopts an edge trigger circuit.

7. The wireless power transmission high frequency inverter output square wave voltage phase detection circuit according to claim 1, characterized in that: The phase detection circuit adopts the capture module in DSP.

8. The wireless power transmission high frequency inverter output square wave voltage phase detection circuit according to claim 1, characterized in that: Also includes: A pull-up resistor, one end of which is connected to a power access node, and the other end of which is respectively connected to a first output end of the optical coupler and a first input end of the phase detector circuit.

9. The wireless power transmission high frequency inverter output square wave voltage phase detection circuit according to claim 8, characterized in that: Also includes: A power supply component, wherein the output end of the power supply component is connected to one end of the pull-up resistor through the power access node.

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