Method for detecting quality factor by transmitter, and transmitter

Abstract

The invention provides a method for detecting a quality factor of an emitter and the emitter, the emitter comprises a switch unit, a capacitor unit and a resonant cavity which are in cascade connection, the resonant cavity comprises a resonant capacitor and an emitter coil which are in series connection, a first end of the resonant cavity is connected with a first end of the capacitor unit, and a second end of the resonant cavity is connected with a second end of the capacitor unit. The second end of the resonant cavity is connected with the second end of the capacitor unit, and the method for detecting the quality factor comprises the following steps: S1, controlling the switch unit to enable a voltage source to charge the resonant cavity; and S2, controlling the switch unit to enable a loop formed by the resonant cavity and the capacitor unit to perform free oscillation, and performing quality factor detection during the free oscillation period. The precision of the quality factor value can be improved, and the foreign matter detection precision and sensitivity are further improved.

Description

Technical Field

[0001] The present application relates to wireless power transmission, and in particular to a method for detecting a quality factor of a transmitter, and a transmitter. Background Art

[0002] As technology develops, wireless power transfer has become an efficient and convenient mechanism for powering or charging battery-based mobile devices such as mobile phones, tablets, digital cameras, MP3 players, and / or similar devices.

[0003] The wireless power transmission system includes a transmitter and a receiver. When the receiver is placed within the output power range of the transmitter, magnetic coupling is established between the transmitter coil in the transmitter and the receiver coil in the receiver, and the output power of the transmitter is transmitted to the receiver, that is, wireless power transmission is formed between the transmitter and the receiver to charge the load (such as a rechargeable battery and / or battery pack in a mobile device).

[0004] In actual applications, there may be foreign objects (such as paper clips, coins, etc.) between or near the transmitter and receiver. When transmitting power between the transmitter and the receiver, foreign objects will not only cause unnecessary power consumption, thereby reducing the efficiency of power transmission in the wireless power transmission system, but also cause the temperature of the foreign object itself to rise, affecting the user experience. For example, the new standard IEC62368 stipulates that the target temperature of foreign objects should be lower than 60 degrees Celsius. For foreign objects such as paper clips, the power loss that causes the temperature to reach 60 degrees Celsius is only about 300 milliwatts, so a higher-precision foreign object detection method is required.

[0005] In addition, after the transmitter is powered on, foreign matter between or near the transmitter and the receiver will be magnetically coupled to the wireless power transmission system, causing the quality factor of the transmitter to decrease. Therefore, the quality factor of the transmitter can reflect the condition of the foreign matter. Generally, the greater the impact of the foreign matter on the wireless power transmission system, the smaller the current quality factor. Based on this, after the transmitter is powered on, the current quality factor of the transmitter can be detected, and the condition of the foreign matter between or near the transmitter and the receiver can be judged based on the quality factor.

[0006] In the current quality factor detection method, there is a problem of large impedance in the quality factor detection path, especially for complex resonant systems, such as the equivalent impedance of inductors and the impedance brought by PCB traces, which affects the accuracy of quality factor detection and causes failure of tiny foreign object detection, and cannot meet the requirements of foreign object detection accuracy and sensitivity. Summary of the invention

[0007] According to one embodiment, the present application provides a method for a transmitter to detect a quality factor, which is applied to a wireless power transmission system, wherein the transmitter includes a switch unit, a capacitor unit and a resonant cavity connected in cascade, the resonant cavity includes a resonant capacitor and a transmitter coil connected in series, the first end of the resonant cavity is connected to the first end of the capacitor unit, and the second end of the resonant cavity is connected to the second end of the capacitor unit, including: S1: controlling the switch unit so that a voltage source charges the resonant cavity; S2: controlling the switch unit so that the loop formed by the resonant cavity and the capacitor unit oscillates freely, and performing quality factor detection during the free oscillation.

[0008] Furthermore, in step S1, the switch unit is controlled so that the first end of the resonant cavity is connected to the voltage source, and the second end of the resonant cavity is connected to the ground; in step S2, the switch unit is controlled so that the first end of the resonant cavity is connected to the ground.

[0009] Furthermore, the switch unit includes: a first switch bridge arm formed by a first switch tube and a second switch tube connected in series between a voltage bus and a ground terminal, wherein a connection point between the first switch tube and the second switch tube forms a first output terminal of the switch unit; a second switch bridge arm formed by a third switch tube and a fourth switch tube connected in series between the voltage bus and the ground terminal, wherein a connection point between the third switch tube and the fourth switch tube forms the second output terminal of the switch unit, wherein the first end of the resonant cavity is connected to the first output terminal of the switch unit, and the second end of the resonant cavity is connected to the second output terminal of the switch unit, wherein in step S1 The step of controlling the switch unit so that a voltage source charges the resonant cavity comprises: controlling the first switch tube and the fourth switch tube to be turned on, and controlling the second switch tube and the third switch tube to be turned off, so that the voltage source provided by the voltage bus charges the resonant cavity through the turned-on first switch tube and the fourth switch tube; the step of controlling the switch unit so that the loop formed by the resonant cavity and the capacitor unit performs free oscillation comprises: controlling the second switch tube to be turned on, and controlling the first switch tube, the third switch tube and the fourth switch tube to be turned off, so that the loop formed by the resonant cavity and the capacitor unit performs free oscillation.

[0010] Furthermore, the switch unit includes: a first switch bridge arm formed by a first switch tube and a second switch tube connected in series between a voltage bus and a ground terminal, and the connection point of the first switch tube and the second switch tube forms the first output terminal of the switch unit; a second switch bridge arm formed by a third switch tube and a fourth switch tube connected in series between the voltage bus and the ground terminal, and the connection point of the third switch tube and the fourth switch tube forms the second output terminal of the switch unit; a fifth switch tube, one end of which is connected to the first output terminal of the switch unit and the other end is used to connect to an auxiliary voltage source, wherein the first end of the resonant cavity is connected to the first output terminal of the switch unit, and the second end of the resonant cavity is connected to the The second output end, wherein the controlling of the switch unit in step S1 so that a voltage source charges the resonant cavity includes: controlling the fifth switch tube and the fourth switch tube to be turned on, and controlling the first switch tube, the second switch tube and the third switch tube to be turned off, so that the auxiliary voltage source charges the resonant cavity through the turned-on fifth switch tube and the fourth switch tube; the controlling of the switch unit in step S2 so that the loop formed by the resonant cavity and the capacitor unit oscillates freely includes: controlling the second switch tube to be turned on, and controlling the first switch tube, the third switch tube, the fourth switch tube and the fifth switch tube to be turned off, so that the loop formed by the resonant cavity and the capacitor unit oscillates freely.

[0011] Furthermore, before step S1, the method further includes: controlling the switch unit to discharge the resonant cavity.

[0012] The present application also provides a transmitter in a wireless power transmission system, comprising: a switch unit, comprising at least one switch tube; a capacitor unit, comprising at least one capacitor, wherein the first end of the capacitor unit is connected to the first output end of the switch unit, and the second end of the capacitor unit is connected to the second output end of the switch unit; a resonant cavity, comprising a resonant capacitor and a transmitter coil connected in series, wherein the first end of the resonant cavity is connected to the first end of the capacitor unit, and the second end of the resonant cavity is connected to the second end of the capacitor unit; wherein the switch unit is configured to allow a voltage source to charge the resonant cavity; then, the switch unit is configured to allow the loop formed by the resonant cavity and the capacitor unit to oscillate freely for quality factor detection.

[0013] Furthermore, the switch unit includes: a first switch bridge arm formed by a first switch tube and a second switch tube connected in series between a voltage bus and a ground terminal, and a connection point between the first switch tube and the second switch tube forms the first output terminal of the switch unit; a second switch bridge arm formed by a third switch tube and a fourth switch tube connected in series between the voltage bus and the ground terminal, and a connection point between the third switch tube and the fourth switch tube forms the second output terminal of the switch unit, wherein the first switch tube and the fourth switch tube are configured to be turned on, and the second switch tube and the third switch tube are configured to be turned off, so that the voltage source provided by the voltage bus charges the resonant cavity through the turned-on first switch tube and the fourth switch tube; then, the second switch tube is configured to be turned on, and the first switch tube, the third switch tube and the fourth switch tube are configured to be turned off, so that the loop formed by the resonant cavity and the capacitor unit oscillates freely.

[0014] Furthermore, the switch unit includes: a first switch bridge arm formed by a first switch tube and a second switch tube connected in series between a voltage bus and a ground terminal, and a connection point between the first switch tube and the second switch tube forms the first output terminal of the switch unit; a second switch bridge arm formed by a third switch tube and a fourth switch tube connected in series between the voltage bus and the ground terminal, and a connection point between the third switch tube and the fourth switch tube forms the second output terminal of the switch unit; a fifth switch tube, one end of which is connected to the first output terminal of the switch unit, and the other end is used to connect an auxiliary voltage source, wherein the fifth switch tube and the fourth switch tube are configured to be turned on, and the first switch tube, the second switch tube and the third switch tube are configured to be turned off, so that the auxiliary voltage source charges the resonant cavity through the turned-on fifth switch tube and the fourth switch tube; then, the second switch tube is configured to be turned on, and the first switch tube, the third switch tube, the fourth switch tube and the fifth switch tube are configured to be turned off, so that the loop formed by the resonant cavity and the capacitor unit oscillates freely.

[0015] Furthermore, the transmitter also includes: a first inductor connected between the first end of the capacitor unit and the first output end of the switch unit; and a second inductor connected between the second end of the capacitor unit and the second output end of the switch unit.

[0016] Furthermore, the capacitor unit includes at least one capacitor switch series branch, which is connected in parallel with the resonant cavity and includes a capacitor and a selection switch connected in series.

[0017] The features and technical advantages of the present disclosure have been summarized quite extensively above so that the detailed description disclosed below may be better understood. Additional features and advantages of the present disclosure will be described below, which constitute the subject matter of the claims of the present disclosure. It will be appreciated by those skilled in the art that the disclosed concepts and specific embodiments may be easily used as a basis for modifying or designing other structures or processes for achieving the same purpose of the present disclosure. It will also be appreciated by those skilled in the art that such equivalent structures do not depart from the spirit and scope of the present disclosure as set forth in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description in conjunction with the accompanying drawings, in which:

[0019] Figure 1 A schematic diagram of a transmitter block diagram according to an embodiment of the present application is shown;

[0020] Figure 2 A schematic diagram of a transmitter block diagram of another embodiment of the present application is shown;

[0021] Figure 3 A schematic diagram of a process of detecting quality factor of a transmitter according to an embodiment of the present application is shown;

[0022] Figure 4 A schematic diagram of a transmitter according to a first specific embodiment of the present application is shown;

[0023] Figure 5 A schematic diagram showing a transmitter of the first specific embodiment of the present application working in the resonant cavity discharge stage;

[0024] Figure 6 A schematic diagram showing a transmitter of the first specific embodiment of the present application working in the stage of charging the resonant cavity;

[0025] Figure 7 A schematic diagram showing a transmitter in the first specific embodiment of the present application working in a free oscillation stage;

[0026] Figure 8 A schematic diagram of the operating waveform of the transmitter of the first specific embodiment of the present application is shown;

[0027] Fig. 9 A schematic diagram showing a transmitter of the first specific embodiment of the present application working in the first stage of free oscillation;

[0028] Fig.10 A schematic diagram showing the transmitter of the first specific embodiment of the present application working in the second stage of free oscillation;

[0029] Fig.11 A schematic diagram of a transmitter according to a second specific embodiment of the present application is shown;

[0030] Fig.12 A schematic diagram of a transmitter according to a third specific embodiment of the present application is shown;

[0031] Fig.13 A schematic diagram of a transmitter according to a fourth specific embodiment of the present application is shown;

[0032] Fig.14 A schematic diagram of a capacitor unit according to an embodiment of the present application is shown;

[0033] Fig.15 A schematic diagram of a receiver according to an embodiment of the present application is shown.

[0034] Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated.The figures are drawn to clearly illustrate the relevant aspects of the various embodiments and are not necessarily drawn to scale. DETAILED DESCRIPTION

[0035] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0036] In one embodiment of the present application, a method for detecting a quality factor of a transmitter is provided, which is applied to a wireless power transmission system. Figure 1 The transmitter block diagram of an embodiment of the present application is shown, and Figure 2 The transmitter block diagram of another embodiment of the present application is shown in FIG. As we know, the transmitter generally includes a switch unit 110 and a resonant cavity 130 connected in cascade, the resonant cavity 130 includes a resonant capacitor Cp and a transmitter coil Lp connected in series, the switch unit 110 is used to achieve power conversion, and the transmitter coil Lp is used to couple with a receiver coil in the receiver to transmit power to the receiver. Figure 2 , Figure 1 The transmitter in the embodiment further includes a first inductor L1 and a second inductor L2, wherein the first inductor L1 is connected between the first end of the resonant cavity 130 and the first output end SW1 of the switch unit 110, and the second inductor L2 is connected between the second end of the resonant cavity 130 and the second output end SW2 of the switch unit 110. Figure 1 The transmitters in the transmitter form a complex resonant system.

[0037] In practical applications, Figure 1 The transmitter shown can be used in in-vehicle wireless charging. Figure 2 The transmitter shown can be applied to wireless charging of consumer electronics, such as mobile phones, watches, etc.

[0038] For this application, Figure 1 and Figure 2 As shown, the transmitter further includes a capacitor unit 120, and the capacitor unit 120 includes at least one capacitor Cf. The switch unit 110, the capacitor unit 120, and the resonant cavity 130 are connected in cascade, that is, the capacitor unit 120 is further connected between the switch unit 110 and the resonant cavity 130. Specifically, the first end of the resonant cavity 130 is connected to the first end of the capacitor unit 120, and the second end of the resonant cavity 130 is connected to the second end of the capacitor unit 120.

[0039] based on Figure 1 and Figure 2 The transmitter shown can be found in Figure 3 The flowchart of the transmitter detecting the quality factor of an embodiment of the present application is shown in FIG. 1 . The method for detecting the quality factor of the transmitter provided by the present application includes:

[0040] S1: Control the switch unit 110 so that a voltage source charges the resonant cavity 130;

[0041] S2: Control the switch unit 110 so that the loop formed by the resonant cavity 130 and the capacitor unit 120 performs free oscillation, and perform quality factor detection during the free oscillation.

[0042] As described above, by controlling the switch unit 110, the loop formed by the resonant cavity 130 and the capacitor unit 120 has a free oscillation period, and the quality factor is detected by the free oscillation of the loop formed by the resonant cavity 130 and the capacitor unit 120 to obtain the quality factor of the transmitter. It can be seen that there is only the equivalent impedance of the necessary transmitter coil in the detection loop, and there is no equivalent impedance of other inductors or switching devices. The total impedance value is small, so the accuracy of the quality factor value can be improved, thereby improving the accuracy and sensitivity of foreign object detection. In addition, before performing the quality factor detection, the switch unit 110 is controlled so that the voltage source charges the resonant cavity 130 and provides energy during the free oscillation period, so as to provide sufficient free oscillation energy and improve the accuracy of the quality factor value.

[0043] In one embodiment, in step S1 , the switch unit 110 is controlled so that the first end of the resonant cavity 130 is connected to the voltage source, and the second end of the resonant cavity 130 is connected to the ground, so as to form a loop for charging the resonant cavity 130 .

[0044] In step S2, the switch unit 110 is controlled to connect the first end of the resonant cavity 130 to the ground, so that the first end of the resonant cavity 130 provides a stable reference ground, and the loop formed by the resonant cavity 130 and the capacitor unit 120 can oscillate freely.

[0045] In actual implementation, the switch unit 110 may be a full-bridge switch unit or a half-bridge switch unit. However, the present application does not limit the specific structure of the switch unit 110, as long as the above-mentioned functions of charging the resonant cavity 130 and free oscillating the loop formed by the resonant cavity 130 and the capacitor unit 120 can be achieved by controlling the switch unit 110. For example, in one embodiment, it may also be a multi-level full-bridge switch unit.

[0046] The following will be Figure 1 The transmitter shown in the figure is implemented as a full-bridge switch unit to illustrate its working principle. Figure 4 The transmitter circuit diagram of the first specific embodiment of the present application is shown in FIG. Figure 4 As shown, the switch unit 110 includes a first switch bridge arm formed by a first switch tube Q1 and a second switch tube Q2 connected in series between a voltage bus Vbus and a ground terminal GND, and the connection point between the first switch tube Q1 and the second switch tube Q2 forms the first output terminal SW1 of the switch unit 110; a second switch bridge arm formed by a third switch tube Q3 and a fourth switch tube Q4 connected in series between the voltage bus Vbus and the ground terminal GND, and the connection point between the third switch tube Q3 and the fourth switch tube Q4 forms the second output terminal SW2 of the switch unit 110, wherein the first end of the resonant cavity 130 is connected to the first output terminal SW1 of the switch unit 110, and the second end of the resonant cavity 130 is connected to the second output terminal SW2 of the switch unit 110. That is, the switch unit 110 is a full-bridge switch unit 110. And as Figure 4 As shown, the switch unit 110 further includes a fifth switch tube Q5, one end of which is connected to the first output terminal SW1 of the switch unit 110, and the other end is used to connect an auxiliary voltage source Vdc. The auxiliary voltage source Vdc can be a DC voltage source or other forms of voltage sources, which are not specifically limited in this application.

[0047] In actual implementation, please refer to Figure 3 Before entering step S1, the method may further include: controlling the switch unit 110 to discharge the resonant cavity 130 to improve the reliability of the operation of the resonant cavity 130.

[0048] For details, please refer to Figure 5 The schematic diagram of the transmitter of the first specific embodiment of the present application working in the resonant cavity discharge stage is shown. Specifically, the second switch tube Q2 and the fourth switch tube Q4 are controlled to be turned on, and the first switch tube Q1, the fifth switch tube Q5 and the third switch tube Q3 are controlled to be turned off, so that the resonant cavity 130 discharges through the turned-on second switch tube Q2 and the fourth switch tube Q4.

[0049] Then, the process proceeds to step S1, which is the stage of charging the resonant cavity. Figure 6The schematic diagram of the transmitter of the first specific embodiment of the present application working in the stage of charging the resonant cavity is shown. Specifically, the fifth switch tube Q5 and the fourth switch tube Q4 are controlled to be turned on, and the first switch tube Q1, the second switch tube Q2 and the third switch tube Q3 are controlled to be turned off, so that the auxiliary voltage source Vdc charges the resonant cavity 130 through the turned-on fifth switch tube Q5 and the fourth switch tube Q4. Figure 6 As shown, the auxiliary voltage source Vdc, the resonant cavity 130, the turned-on fourth switch tube Q4, and the ground terminal GND form a charging loop.

[0050] Then, the switch unit 110 is controlled to make the loop formed by the resonant cavity 130 and the capacitor unit 120 oscillate freely. Figure 7 The schematic diagram of the transmitter of the first specific embodiment of the present application working in the free oscillation stage of the resonant cavity is shown. Specifically, the second switch tube Q2 is controlled to be turned on, and the first switch tube Q1, the third switch tube Q3, the fourth switch tube Q4 and the fifth switch tube Q5 are controlled to be turned off.

[0051] In a specific implementation, before entering into a stable free oscillation, the transmitter may also go through a short first stage, a second stage and a third stage.

[0052] For details, please refer to Figure 8 The schematic diagram of the operating waveform of the transmitter of the first specific embodiment of the present application is shown, where IQ2 is the current flowing through the second switch tube Q2, VPai-1 is the voltage of the node Pai-1, VPai-2 is the voltage of the node Pai-2, and VS is the voltage on the resonant capacitor Cp. In actual implementation, at the beginning of step S2, the voltage of the second end Pai-2 of the capacitor unit 120 is usually less than -0.7V, then the body diode of the fourth switch tube Q4 will be turned on, and the first end Pai-1 of the capacitor unit 120 forms a resonant first loop through the first inductor L1, the turned-on second switch tube Q2, the body diode of the fourth switch tube Q4, and the second inductor L2, and the first end Pai-1 of the capacitor unit 120 is discharged. At the same time, the resonant cavity 130 and the capacitor unit 120 form a free oscillation second loop, but the current in the second loop is very small, which can be seen in Fig. 9 The schematic diagram of the transmitter of the first specific embodiment of the present application when it is working in the first stage of free oscillation is shown. Figure 8 In this first stage, the resonant current in the first loop (i.e., the current IQ2 flowing through the second switch tube Q2) first increases and then gradually decreases to 0A, and the first stage ends. It can be seen that in this first stage, while the loop formed by the resonant cavity 130 and the capacitor unit 120 is freely oscillating, there is resonance in the first loop.

[0053] Then refer to Fig.10The schematic diagram shown is a diagram of the transmitter of the first specific embodiment of the present application operating in the second stage of free oscillation. During this period, the second loop of free oscillation formed by the resonant cavity 130 and the capacitor unit 120 continues, the resonance of the first loop ends, and the current IQ2 flowing through the second switch tube Q2 is zero (the first loop is represented by a dotted line). When the voltage difference between the first end Pai-1 of the capacitor unit 120 and the second end Pai-2 of the capacitor unit 120 is equal to the voltage drop of the body diode of the fourth switch tube Q4, the second stage ends.

[0054] Then it enters the third stage of free oscillation, which is the same as the first stage of free oscillation. Fig. 9 , the first circuit resonates again, and the second circuit still oscillates freely, but the current in the second circuit is very small. The resonant current in the first circuit still increases first and then gradually decreases to 0A, and the third stage ends.

[0055] Then, the resonant cavity 130 and the capacitor unit 120 work for a long time in the stable free oscillation stage. Fig.10 Generally, compared with the stable free oscillation stage, the first stage, the second stage and the third stage are short and can be ignored in practical work.

[0056] During the period when the transmitter is operating in the stable free oscillation phase, such as Fig.10 As shown, the quality factor is detected by the free oscillation of the loop formed by the resonant cavity 130 and the capacitor unit 120. It can be seen that only the equivalent impedance of the necessary transmitter coil exists in the detection loop, and there is no equivalent impedance of other inductors or switching devices. The total impedance value is small, so the accuracy of the quality factor value can be improved, thereby improving the accuracy and sensitivity of foreign object detection.

[0057] In actual implementation, the auxiliary voltage source Vdc and the matching fifth switch tube Q5 may not be provided to charge the resonant cavity 130. Fig.11 The transmitter circuit diagram of the second specific embodiment of the present application is shown in FIG. Figure 4 , the switch unit 110 does not include the fifth switch tube Q5, and the transmitter does not include the auxiliary voltage source Vdc. At this time, the resonant cavity 130 can be charged by the voltage source connected to the voltage bus Vbus for powering the transmitter. For example, in the stage of charging the resonant cavity in step S1, the first switch tube Q1 and the fourth switch tube Q4 are controlled to be turned on, and the second switch tube Q2 and the third switch tube Q3 are controlled to be turned off, so that the voltage source connected to the voltage bus Vbus charges the resonant cavity 130 through the turned-on first switch tube Q1 and the fourth switch tube Q4. In the discharge stage and free oscillation stage of the resonant cavity 130, its control of the switch unit 110 is the same as Figure 4 The transmitter shown is the same except that the control of the fifth switch tube Q5 is not included, which will not be described in detail here.

[0058] In another embodiment, see Fig.12 The transmitter schematic diagram of the third specific embodiment of the present application is shown in FIG. Fig.12 As shown, the switch unit 110 includes: a first switch bridge arm formed by a first switch tube Q1 and a second switch tube Q2 connected in series between a voltage bus Vbus and a ground terminal GND, and the connection point between the first switch tube Q1 and the second switch tube Q2 forms a first output terminal SW1 of the switch unit 110; wherein the first end of the resonant cavity 130 is connected to the first output terminal SW1 of the switch unit 110 through a first inductor L1, and the second end of the resonant cavity 130 is connected to the ground terminal GND through a second inductor L2, and at this time, the ground terminal GND constitutes the second output terminal SW2 of the switch unit 110. That is, the switch unit 110 is a half-bridge switch unit 110.

[0059] See also Fig.13 The transmitter schematic diagram of the fourth specific embodiment of the present application is shown in FIG. Fig.12 The difference is that the switch unit 110 further includes a fifth switch tube Q5 , one end of which is connected to the first output terminal SW1 of the switch unit 110 , and the other end is used to connect to an auxiliary voltage source Vdc. That is, the auxiliary voltage source Vdc provides a power source for charging the resonant cavity 130 .

[0060] In actual implementation, the present application does not limit the specific structure of the resonant cavity 130. As mentioned above, the resonant cavity 130 includes a primary resonant capacitor Lp and a primary resonant capacitor Cp, but the present application does not limit this.

[0061] In actual implementation, the capacitor unit 120 includes at least one capacitor, such as Figures 4 to 7 ,and Figures 9 to 13 As shown, it includes a capacitor Cf. Of course, it may also include multiple capacitors connected in series and in parallel to obtain ideal EMI, gain and required resonant frequency.

[0062] In actual implementation, the capacitor unit 120 may include a selection switch connected in series with the capacitor in addition to the capacitor, so that the switching in and out of the capacitor can be controlled, so that the EMI, gain and resonant frequency of the transmitter can be controlled. Fig.14 The schematic diagram of the capacitor unit 120 of an embodiment of the present application is shown, wherein the capacitor unit 120 in (a) includes a capacitor switch series branch, and the capacitor switch series branch is also connected in parallel with the resonant cavity 130, and the capacitor switch series branch includes a capacitor Cf1 and a selection switch Sf1 connected in series.

[0063] Fig.14The capacitor unit 120 in (b) adds a capacitor switch series branch connected in parallel with the capacitor Cf, and the capacitor switch series branch is also connected in parallel with the resonant cavity 130. The capacitor switch series branch includes a capacitor Cf1 and a selection switch Sf1 connected in series. Fig.14 The capacitor unit 120 in (c) includes two parallel capacitor switch series branches, and the capacitor switch series branches are also connected in parallel with the resonant cavity 130, wherein one capacitor switch series branch includes a capacitor Cf1 and a selection switch Sf1 connected in series, and the other capacitor switch series branch includes a capacitor Cf2 and a selection switch Sf2 connected in series. In actual implementation, the transmitter needs to wirelessly charge multiple different receivers, and different receivers operate at different resonant frequencies. The introduction of capacitor switch series branches can realize wireless charging of different receivers by a single transmitter. Fig.14 Taking (b) in FIG. 1 as an example, when working at the first resonant frequency, the selection switch Sf1 in the capacitor unit 120 is disconnected; when working at the second resonant frequency, the selection switch Sf1 in the capacitor unit 120 is closed.

[0064] Fig.14 Only some embodiments are shown, and the number of capacitor switch series branches is not limited in actual applications.

[0065] In actual work, Fig.14 In the capacitor unit 120 shown, the selection switches are configured to be turned on during the period of charging the resonant cavity 130 for quality factor detection and during the free oscillation period. Of course, the number of the selection switches turned on can also be selected.

[0066] Furthermore, for Fig.14 The capacitor unit 120 shown, when the transmitter is working normally, such as when wireless charging is performed, the selection switch is configured to be turned off. Of course, the number of the selection switches that are turned off can also be selected so that the capacitor unit 120 also has the function of adjusting the EMI, gain and resonant frequency of the transmitter.

[0067] In a specific implementation, any suitable quality factor detection method can be selected during the free oscillation period. In a specific embodiment, the transmitter further includes a comparator. One end of the comparator receives the coil voltage from the transmitter coil Lp, and the other end of the comparator receives the first threshold value V th1 Or the second threshold V th2 ; When the attenuated coil voltage reaches the first threshold V th1 When reversing, the reversal time of the comparator is recorded as the first time t1; when the coil voltage reaches the second threshold value V th2 When reversing, the reversal time of the comparator is recorded as the second time t2; according to the formula

[0068]

[0069] Calculate the quality factor, where Q is the quality factor and T is the period of the decaying sine wave of the transmitter coil during free oscillation.

[0070] As described above, in the method for detecting the quality factor of a transmitter provided by the present application, the quality factor detection circuit only contains the equivalent impedance of the necessary transmitter coil, and there is no equivalent impedance of other inductors or switching devices. The total impedance value is small, thereby improving the accuracy of the quality factor value, thereby improving the accuracy and sensitivity of foreign object detection.

[0071] In one embodiment of the present application, a transmitter in a wireless power transmission system is provided. Figure 1 and Figure 2 The transmitter includes: a switch unit 110, including at least one switch tube; a capacitor unit 120, including at least one capacitor, a first end of the capacitor unit 120 is connected to a first output end SW1 of the switch unit 110, and a second end of the capacitor unit 120 is connected to a second output end SW2 of the switch unit 110; a resonant cavity 130, including a resonant capacitor Cp and a transmitter coil Lp connected in series, a first end of the resonant cavity 130 is connected to a first end of the capacitor unit 120, and a second end of the resonant cavity 130 is connected to a second end of the capacitor unit 120; wherein the switch unit 110 is configured to allow a voltage source to charge the resonant cavity 130; then, the switch unit 110 is configured to allow a loop formed by the resonant cavity 130 and the capacitor unit 120 to oscillate freely to perform quality factor detection.

[0072] Similarly, the quality factor detection is performed during the free oscillation of the loop formed by the resonant cavity 130 and the capacitor unit 120. It can be seen that only the equivalent impedance of the necessary transmitter coil exists in the detection loop, and there is no equivalent impedance of other inductors or switching devices. The total impedance value is small, so the accuracy of the quality factor value can be improved, thereby improving the accuracy and sensitivity of foreign object detection.

[0073] In one embodiment, see Figure 4 The transmitter shown, for Figure 4 The transmitter shown can be found in Figure 6 and Figure 7The schematic diagram of the working process is shown. The fifth switch tube Q5 and the fourth switch tube Q4 are configured to be turned on, and the first switch tube Q1, the second switch tube Q2 and the third switch tube Q3 are configured to be turned off, so that the auxiliary voltage source Vdc charges the resonant cavity 130 through the turned-on fifth switch tube Q5 and the fourth switch tube Q4; then, the second switch tube Q2 is configured to be turned on, and the first switch tube Q1, the third switch tube Q3, the fourth switch tube Q4 and the fifth switch tube Q5 are configured to be turned off, so that the loop formed by the resonant cavity 130 and the capacitor unit 120 oscillates freely. Specifically, the free oscillation process is the same as described above and will not be repeated here. Similarly, the discharge process of the resonant cavity 130 is also the same as described above and will not be repeated here.

[0074] In one embodiment, for Fig.11 In the transmitter shown, the first switch tube Q1 and the fourth switch tube Q4 are configured to be turned on, and the second switch tube Q2 and the third switch tube Q3 are configured to be turned off, so that the voltage source provided by the voltage bus Vbus charges the resonant cavity 130 through the turned-on first switch tube Q1 and the fourth switch tube Q4; then, the second switch tube Q2 is configured to be turned on, and the first switch tube Q1, the third switch tube Q3 and the fourth switch tube Q4 are configured to be turned off, so that the loop formed by the resonant cavity 130 and the capacitor unit 120 is free oscillated. Specifically, the free oscillation process is the same as described above and will not be repeated here. Similarly, the discharge process of the resonant cavity 130 is also the same as described above and will not be repeated here.

[0075] We know that the wireless power transmission system includes a transmitter and a receiver, and wireless power transmission is formed between the two through the magnetic coupling established between the transmitter coil in the transmitter and the receiver coil in the receiver.

[0076] In one embodiment, see Fig.15 A schematic diagram of a receiver of an embodiment of the present application is shown. Similar to the above-mentioned transmitter, the receiver may also include a switch unit, a capacitor unit and a resonant cavity connected in cascade. Then the wireless power transmission system can realize bidirectional power transmission.

[0077] The switch unit 210 is used to realize power conversion, and the resonant cavity 230 includes a resonant capacitor Cs and a receiver coil Ls connected in series, which is used to couple with the resonant cavity 130 of the transmitter. The switch unit 210 is also similar to the switch unit 110 in the transmitter, for example Figure 4 , Fig.11 , Fig.12 and Fig.13 The capacitor unit 220 is also similar to the capacitor unit 120 in the transmitter. Fig.15The receiver shown can work in any of the working states described above similarly to the transmitter described above, realize the same function, and perform quality factor detection based on the same principle and advantages. That is, the receiver can also perform quality factor detection using the method of detecting quality factor of the transmitter described above.

[0078] Since the method, principle and advantages of the receiver and the method of detecting the quality factor are the same as those of the transmitter, the receiver and the method of detecting the quality factor are not described in detail here. Specifically, when the wireless power transmission system works in the reverse charging state, the quality factor is detected by the receiver.

[0079] Although the embodiments of the present disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims.

[0080] In addition, the scope of the present application is not intended to be limited to the specific embodiments of the processes, machines, manufactures, material compositions, devices, methods, and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of this disclosure, processes, machines, manufactures, material compositions, means, methods, or steps that perform substantially the same functions currently exist or will later be developed or achieve substantially the same results as the corresponding embodiments described herein that can be used according to this disclosure. Therefore, the appended claims are intended to include such processes, machines, manufactures, material compositions, devices, methods, or steps within their scope.

Claims

1. A method for detecting a quality factor of a transmitter, applied to a wireless power transmission system, wherein the transmitter comprises a switch unit, a capacitor unit and a resonant cavity connected in cascade, the resonant cavity comprises a resonant capacitor and a transmitter coil connected in series, a first end of the resonant cavity is connected to a first end of the capacitor unit, and a second end of the resonant cavity is connected to a second end of the capacitor unit, characterized in that: include: S1: Control the switch unit so that a voltage source charges the resonant cavity; S2: Control the switch unit so that the loop formed by the resonant cavity and the capacitor unit performs free oscillation, and perform quality factor detection during the free oscillation.

2. The method for detecting quality factor of a transmitter according to claim 1, characterized in that: In step S1, the switch unit is controlled so that the first end of the resonant cavity is connected to the voltage source, and the second end of the resonant cavity is connected to the ground; In step S2, the switch unit is controlled so that the first end of the resonant cavity is connected to the ground end.

3. The method for detecting quality factor of a transmitter according to claim 2, characterized in that: The switch unit comprises: A first switch bridge arm is formed by a first switch tube and a second switch tube connected in series between a voltage bus and a ground terminal, wherein a connection point between the first switch tube and the second switch tube forms a first output terminal of the switch unit; a second switch bridge arm formed by a third switch tube and a fourth switch tube connected in series between the voltage bus and the ground terminal, wherein a connection point between the third switch tube and the fourth switch tube forms the second output terminal of the switch unit, The first end of the resonant cavity is connected to the first output end of the switch unit, and the second end of the resonant cavity is connected to the second output end of the switch unit. Controlling the switch unit in step S1 so that a voltage source charges the resonant cavity includes: Controlling the first switch tube and the fourth switch tube to be turned on, and controlling the second switch tube and the third switch tube to be turned off, so that the voltage source provided by the voltage bus charges the resonant cavity through the turned-on first switch tube and the fourth switch tube; Controlling the switch unit in step S2 so that the loop formed by the resonant cavity and the capacitor unit performs free oscillation includes: The second switch tube is controlled to be turned on, and the first switch tube, the third switch tube and the fourth switch tube are controlled to be turned off, so that the loop formed by the resonant cavity and the capacitor unit performs free oscillation.

4. The method for detecting quality factor of a transmitter according to claim 2, characterized in that: The switch unit comprises: A first switch bridge arm is formed by a first switch tube and a second switch tube connected in series between a voltage bus and a ground terminal, wherein a connection point between the first switch tube and the second switch tube forms a first output terminal of the switch unit; A second switch bridge arm formed by a third switch tube and a fourth switch tube connected in series between the voltage bus and the ground terminal, wherein a connection point between the third switch tube and the fourth switch tube forms the second output terminal of the switch unit; a fifth switch tube, one end of which is connected to the first output end of the switch unit, and the other end of which is used to connect to an auxiliary voltage source, The first end of the resonant cavity is connected to the first output end of the switch unit, and the second end of the resonant cavity is connected to the second output end of the switch unit. Controlling the switch unit in step S1 so that a voltage source charges the resonant cavity includes: Controlling the fifth switch tube and the fourth switch tube to be turned on, and controlling the first switch tube, the second switch tube, and the third switch tube to be turned off, so that the auxiliary voltage source charges the resonant cavity through the turned-on fifth switch tube and the fourth switch tube; Controlling the switch unit in step S2 so that the loop formed by the resonant cavity and the capacitor unit performs free oscillation includes: The second switch tube is controlled to be turned on, and the first switch tube, the third switch tube, the fourth switch tube and the fifth switch tube are controlled to be turned off, so that the loop formed by the resonant cavity and the capacitor unit performs free oscillation.

5. The method for detecting quality factor of a transmitter according to claim 1, characterized in that: Before step S1, the method further includes: controlling the switch unit to discharge the resonant cavity.

6. A transmitter in a wireless power transmission system, characterized in that: include: The switch unit comprises at least one switch tube; A capacitor unit, comprising at least one capacitor, wherein a first end of the capacitor unit is connected to a first output end of the switch unit, and a second end of the capacitor unit is connected to a second output end of the switch unit; A resonant cavity, comprising a resonant capacitor and a transmitter coil connected in series, wherein a first end of the resonant cavity is connected to the first end of the capacitor unit, and a second end of the resonant cavity is connected to the second end of the capacitor unit; The switch unit is configured to enable a voltage source to charge the resonant cavity; then, the switch unit is configured to enable a loop formed by the resonant cavity and the capacitor unit to oscillate freely to perform quality factor detection.

7. The transmitter according to claim 6, characterized in that The switch unit comprises: A first switch bridge arm is formed by a first switch tube and a second switch tube connected in series between a voltage bus and a ground terminal, wherein a connection point between the first switch tube and the second switch tube forms the first output terminal of the switch unit; a second switch bridge arm formed by a third switch tube and a fourth switch tube connected in series between the voltage bus and the ground terminal, wherein a connection point between the third switch tube and the fourth switch tube forms the second output terminal of the switch unit, Among them, the first switch tube and the fourth switch tube are configured to be turned on, and the second switch tube and the third switch tube are configured to be turned off, so that the voltage source provided by the voltage bus charges the resonant cavity through the turned-on first switch tube and the fourth switch tube; then, the second switch tube is configured to be turned on, and the first switch tube, the third switch tube and the fourth switch tube are configured to be turned off, so that the loop formed by the resonant cavity and the capacitor unit oscillates freely.

8. The transmitter according to claim 6, characterized in that The switch unit comprises: A first switch bridge arm is formed by a first switch tube and a second switch tube connected in series between a voltage bus and a ground terminal, wherein a connection point between the first switch tube and the second switch tube forms the first output terminal of the switch unit; A second switch bridge arm formed by a third switch tube and a fourth switch tube connected in series between the voltage bus and the ground terminal, wherein a connection point between the third switch tube and the fourth switch tube forms the second output terminal of the switch unit; a fifth switch tube, one end of which is connected to the first output end of the switch unit, and the other end of which is used to connect to an auxiliary voltage source, Among them, the fifth switch tube and the fourth switch tube are configured to be turned on, and the first switch tube, the second switch tube and the third switch tube are configured to be turned off, so that the auxiliary voltage source charges the resonant cavity through the turned-on fifth switch tube and the fourth switch tube; then, the second switch tube is configured to be turned on, and the first switch tube, the third switch tube, the fourth switch tube and the fifth switch tube are configured to be turned off, so that the loop formed by the resonant cavity and the capacitor unit oscillates freely.

9. The transmitter according to any one of claims 6 to 8, characterized in that: The transmitter also includes: A first inductor connected between the first end of the capacitor unit and the first output end of the switch unit; The second inductor is connected between the second end of the capacitor unit and the second output end of the switch unit.

10. The transmitter according to any one of claims 6 to 9, characterized in that: The capacitor unit includes at least one capacitor switch series branch, which is connected in parallel with the resonant cavity and includes a capacitor and a selection switch connected in series.

Images