Foreign matter detection circuit and chip

Abstract

The embodiment of the application discloses a foreign matter detection circuit and a chip, which comprise a first half-bridge, a second half-bridge, an inductor and a first capacitor connected in series, a fifth switch tube and an energy consumption element connected in series and connected between a voltage supply end and a first common connection point formed by the inductor and the first capacitor, a control module connected with the controlled ends of each switch tube, the control module controlling the fifth switch tube to be turned on for a first preset time period and then turned off, and each switch tube actively establishing an initial voltage for the first common connection point through the voltage supply end, a detection module connected with the first common connection point, and the control module controlling the on-off state of each switch tube after the first switch tube is turned on for the first preset time period, so that the first common connection point is free to oscillate and it is detected whether there is foreign matter. The first preset time period for establishing the initial voltage is extremely small, a detection circuit for judging whether the first common connection point reaches the initial voltage needs not to be specially arranged, the design difficulty is reduced, the chip area is reduced, and the situation of false detection is prevented.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit technology, specifically to a foreign object detection circuit and chip. Background Technology

[0002] Current foreign object detection solutions for wireless charging typically detect the following: Figure 1 The oscillating voltage waveform at node M shown is used to determine the presence of foreign objects. Specifically, during foreign object detection, the following steps are typically taken first: Figure 1 The power transistors Q1 and Q4 shown are turned on for a period of time and then turned off. Then, power transistors Q2 and Q4 are turned on again to detect the self-oscillation waveform at node M. This method requires a large number of circuits to process the voltage at node M and has the problem of low detection accuracy. Summary of the Invention

[0003] The purpose of this invention is to provide a foreign object detection circuit and chip to solve the above-mentioned problems. This invention achieves the above objective through the following technical solutions.

[0004] This invention provides a foreign object detection circuit, comprising: a foreign object detection circuit and chip, including a first half-bridge and a second half-bridge connected in parallel between an input terminal and a common terminal, an inductor and a first capacitor connected in series between the half-bridge nodes of the first half-bridge and the second half-bridge, the first half-bridge including a first switch and a second switch, the second half-bridge including a third switch and a fourth switch, including: a fifth switch and a power-consuming element connected in series, connected between the voltage supply terminal and a first common junction formed by the inductor and the first capacitor; a control module connected to the controlled terminals of each switch, controlling the fifth switch to conduct for a first preset time period and then turn it off, cooperating with the first, second, third, and fourth switches to actively establish an initial voltage for the first common junction through the voltage supply terminal; and a detection module connected to the first common junction, after the first switch is conducted for the first preset time period, the control module controls the on / off state of the first, second, third, and fourth switches to allow the first common junction to oscillate freely, and the detection module detects the voltage of the first common junction to determine whether a foreign object exists.

[0005] In some embodiments, the detection module uses envelope detection, and the detection module includes: a diode whose anode is connected to a first common junction; a first resistor and a second capacitor connected in parallel between the first common junction and a common terminal; and the second capacitor having established an operating point when the first common junction has established an initial voltage.

[0006] In some embodiments, the control module controls the first and fourth switches to conduct for a second preset time period, and controls the second and third switches to turn off for a second preset time period; or, the control module controls the first and fourth switches to turn off for a second preset time period, and controls the second and third switches to conduct for a second preset time period.

[0007] In some embodiments, the first preset time period is within the second preset time period, or the second preset time period is before the first preset time period.

[0008] In some embodiments, the start time of the second preset time period is earlier than or equal to the start time of the first preset time period, and the end time of the second preset time period is equal to the end time of the first preset time period.

[0009] In some embodiments, the control module controls the first, second, and third switches to turn off for a third preset time period and controls the fourth switch to turn on for a third preset time period; or, the control module controls the first, third, and fourth switches to turn off for a third preset time period and controls the second switch to turn on for a third preset time period; wherein the start time and end time of the third preset time period are the same as those of the first preset time period.

[0010] In some embodiments, during a first preset time period, the control module controls the first and third switches to turn off, and the second and fourth switches to turn on; or, during the first preset time period, the control module controls the first and third switches to turn on, and the second and fourth switches to turn off.

[0011] In some embodiments, a second resistor is provided between the second common contact formed by the second switching transistor and the fourth switching transistor and a common terminal.

[0012] In some embodiments, the energy-consuming element is a resistor, and the larger the resistance value, the shorter the time to establish the initial voltage.

[0013] This invention also provides a foreign object detection chip, including the foreign object detection circuit described in any of the above embodiments.

[0014] Compared to existing technologies, the foreign object detection circuit and chip provided in this embodiment enable the following steps during foreign object detection: First, the fifth switch is turned on until a starting voltage is established at the first common contact point. Then, the fifth switch is turned off, allowing the voltage at the first common contact point to oscillate freely. The detection module then detects the voltage at the first common contact point to determine the presence of a foreign object. Since a starting voltage can be directly provided to the first common contact point through the voltage supply terminal, the first preset time period for establishing the starting voltage at the first common contact point is extremely short. Furthermore, there is no need to specifically include a detection circuit in the circuit to determine whether the starting voltage has been reached at the first common contact point, effectively reducing design complexity, minimizing chip area, and preventing false detections. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of an application of the foreign object detection circuit provided in this embodiment;

[0017] Figure 2 This is a schematic diagram of the foreign object detection circuit provided in this embodiment;

[0018] Figure 3 This is a waveform diagram of the foreign object detection circuit provided in this embodiment;

[0019] Figure 4 This is another structural schematic diagram of the foreign object detection circuit provided in this embodiment;

[0020] Figure 5 This is a waveform diagram of the foreign object detection circuit provided in this embodiment. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] The term "coupled" or "connected" in this invention includes both direct and indirect connections, such as connections made through some active devices, passive devices, or electrical conduction media; it may also include connections made by other active or passive devices that are known to those skilled in the art and can achieve the same or similar functional purpose, such as connections made through circuits or components such as switches or follower circuits.

[0023] To better understand the technical solution of the foreign object detection circuit and chip provided by this invention, the background technology is further explained below. Specifically, power transistors Q1 and Q4 are first controlled to conduct for a period of time, followed by power transistors Q2 and Q3, until a steady-state voltage is formed at node M. Then, power transistor Q1 is controlled to turn off, and power transistor Q2 is controlled to turn on, causing the voltage at node M to oscillate. The presence of a foreign object is then determined based on the number of effective waves at node M. Theoretically, this method meets the requirements for foreign object detection. However, in practical applications, the inventors of this invention have found that this method requires at least two conditions to be met. The first condition is that a dedicated circuit is needed to detect whether the voltage at node M has reached a steady state. The second condition is that the time period for controlling power transistors Q1 and Q4 to conduct is long enough. To ensure that the voltage at node M has reached a steady state, redundant circuits are usually required to prevent low detection accuracy. Moreover, in actual foreign object detection, a relatively long waiting time is required for the voltage at node M to reach a steady state, which is obviously not conducive to rapid detection of foreign objects and cannot achieve timely detection of foreign objects.

[0024] In summary, the inventors of this invention have discovered the above-mentioned problems and, based on these problems, proposed a foreign object detection circuit and chip provided in this embodiment. For the specific implementation of the foreign object detection circuit and chip, please refer to the description of the following embodiment.

[0025] Please see Figure 2This invention provides a foreign object detection circuit, which includes a first half-bridge 11 and a second half-bridge 12 connected in parallel between the input terminal VIN and the common terminal GND. An inductor L and a first capacitor C1 are connected in series between the half-bridge nodes of the first half-bridge 11 and the second half-bridge 12. The first half-bridge 11 includes a first switch K1 and a second switch K2, and the second half-bridge 12 includes a third switch K3 and a fourth switch K4. The foreign object detection circuit further includes a fifth switch K5 and a power-consuming element 13 connected in series, connected between the voltage supply terminal VX and the first common junction X1 formed by the inductor L and the first capacitor C1; and connected to each switch K1. The control module 14, which is connected to the controlled end of the shut-off tube, controls the fifth switch tube K5 to conduct for a first preset time period and then turn it off. In conjunction with the first switch tube K1, the second switch tube K2, the third switch tube K3, and the fourth switch tube K4, the starting voltage for the first common contact point X1 is actively established through the voltage supply terminal VX. The detection module 15, which is connected to the first common contact point X1, controls the on / off state of the first switch tube K1, the second switch tube K2, the third switch tube K3, and the fourth switch tube K4 after the first switch tube K1 conducts for a first preset time period, so that the first common contact point X1 can oscillate freely. The detection module 15 detects the voltage of the first common contact point X1 to determine whether there is a foreign object.

[0026] In this embodiment, the half-bridge node of the first half-bridge 11 is the common connection point formed by the first switch K1 and the second switch K2, and the half-bridge node of the second half-bridge 12 is the common connection point formed by the third switch K3 and the fourth switch K4. It should be noted that the "common connection point" described in this embodiment is for the convenience of explaining the circuit structure and should not be limited to a specific intersection point formed by connecting two wires. It can also be a wire extending from a specific intersection point formed by connecting two wires. Here, only the term "common connection point" is used to describe the circuit structure of the foreign object detection circuit.

[0027] In this embodiment, the first switch K1, the second switch K2, the third switch K3, and the fourth switch K4 can all include MOS transistors (Metal-Oxide-Semiconductor Field-Effect Transistors), bipolar transistors, BJT transistors (Bipolar Junction Transistors), etc. The first switch K1, the second switch K2, the third switch K3, and the fourth switch K4 have the same switching type.

[0028] In this embodiment, the inductor L and the first capacitor C1 form a first common contact point X1. Regarding the series connection of the inductor L and the first capacitor C1, the first common contact point X1, the energy-consuming element 13, the fifth switch K5, and the voltage supply terminal VX can be connected in sequence, or the first common contact point X1, the fifth switch K5, the energy-consuming element 13, and the voltage supply terminal VX can be connected in sequence.

[0029] In this embodiment, the energy-consuming element 13 can be a resistor, and the resistance value can be configured based on actual needs.

[0030] In this embodiment, the control module 14 can control the on / off states of the first switch K1, the second switch K2, the third switch K3, the fourth switch K4, and the fifth switch K5. During foreign object detection, the fifth switch K5 can be turned on first until a starting voltage is established at the first common contact X1. Then, the fifth switch K5 is turned off, allowing the voltage at the first common contact X1 to oscillate freely. The detection module 15 detects the voltage at the first common contact X1 to determine if a foreign object is present. Since a starting voltage can be directly provided to the first common contact X1 through the voltage supply terminal VX, the first preset time period for establishing the starting voltage at the first common contact X1 is extremely short. Furthermore, there is no need to specifically set up a detection circuit in the circuit to determine whether the starting voltage has been reached at the first common contact X1, effectively reducing design complexity, chip area, and preventing false detections.

[0031] It should be noted that the detection module 15 can determine whether there is a foreign object by detecting the voltage waveform at the first common contact point X1. The detection module 15 can use methods such as effective waveform counting and envelope detection. Here, no specific restrictions are placed on the specific detection method and circuit structure of the detection module 15.

[0032] The inventors of this invention discovered through actual testing that the envelope obtained by envelope detection of the voltage waveform at the first common contact X1 is as follows: Figure 3 As shown in (a), the envelope should be approximately close to the upper and lower edges of the voltage waveform. However, in practical applications, if there are capacitive devices in the detection module 15, the capacitor in the detection module 15 needs to be charged to establish the operating point in the early stage of the oscillation circuit. This results in the voltage after detection of the oscillation waveform being inconsistent with the expected voltage waveform, and the obtained envelope is as follows. Figure 3 As shown in (b), this will cause severe distortion of the peak values ​​of the detected envelope waveform and oscillation waveform, making it impossible to detect foreign objects.

[0033] In some embodiments, such as Figure 4As shown, the detection type of the detection module 15 can be envelope detection. The detection module 15 may include: a diode D, whose anode is connected to the first common junction X1; a first resistor R1 and a second capacitor C2 connected in parallel between the first common junction X1 and the common terminal GND; when the first common junction X1 has established an initial voltage, the second capacitor C2 has established an operating point.

[0034] In this embodiment, when the first common contact X1 has established the initial voltage state and the second capacitor C2 has established the operating point, when performing detection envelope detection, the cathode of diode D can be used as the detection terminal VY. At this time, the edge envelope detected by the envelope detection method is basically close to the edge part of the voltage oscillation wave, and the detection result is more accurate.

[0035] It is important to note that in this embodiment, both the effective wave counting method and the envelope detection method can improve the accuracy of foreign object detection. Specifically, when using the effective wave counting method, the starting voltage of the first common contact point X1 is used as the starting point of the free oscillation of the common contact point. Since the frequency of this free oscillation is consistent with the counting frequency, it is easy to set the peak region of each count to be basically consistent with the clock pulse width region, and the number of effective waves counted is less likely to be wrong in practical applications. At the same time, when using the envelope detection method, since the capacitive device in the detection module 15 has already established its operating point before detecting the envelope, there is no need to charge the capacitive device in the detection module 15 during subsequent oscillations. Figure 5 As shown, in this method, the envelope obtained under free oscillation is basically consistent with the edge of the oscillation waveform, which greatly improves the detection accuracy under the envelope detection method.

[0036] In some embodiments, the control module 14 can control the first switch K1 and the fourth switch K4 to conduct for a second preset time period, and control the second switch K2 and the third switch K3 to turn off for a second preset time period; or, the control module 14 can control the first switch K1 and the fourth switch K4 to turn off for a second preset time period, and control the second switch K2 and the third switch K3 to conduct for a second preset time period.

[0037] In this embodiment, when the control module 14 controls the first switch K1 and the fourth switch K4 to conduct for a second preset time period, and controls the second switch K2 and the third switch K3 to turn off for a second preset time period, the input terminal VIN, the first switch K1, the inductor L, the series-connected energy-consuming element 13 and the fifth switch K5, and the voltage supply terminal VX can form a first path, and the input terminal VIN, the first switch K1, the inductor L, the first capacitor C1, the fourth switch K4, and the common terminal GND can form a second path. When the control module 14 controls the first switch K1 and the fourth switch K4 to turn off for a second preset time period, and controls the second switch K2 and the third switch K3 to conduct for a second preset time period, the input terminal VIN, the third switch K3, the first capacitor C1, the series-connected energy-consuming element 13 and the fifth switch K5, and the voltage supply terminal VX can form a third path, and the input terminal VIN, the third switch K3, the first capacitor C1, the inductor L, the second switch K2, and the common terminal GND can form a fourth path. During the formation of the above-mentioned path, the starting voltage for the first common contact X1 can be established more quickly due to the combined effect of the input terminal VIN and the supply terminal VX.

[0038] In some embodiments, the first preset time period is within the second preset time period, or the second preset time period is before the first preset time period.

[0039] Specifically, the first preset time period can be represented as being within the second preset time period, and the first preset time period can fall within any interval of the second time period. The control module 14 can control the fifth switch K5 to conduct during the first preset time period while controlling the first switch K1 and the fourth switch K4 to conduct and the second switch K2 and the third switch K3 to conduct during the second preset time period. Alternatively, the control module 14 can control the fifth switch K5 to conduct during the first preset time period while controlling the first switch K1 and the fourth switch K4 to conduct and the second switch K2 and the third switch K3 to conduct during the second preset time period.

[0040] The second preset time period can be indicated as occurring before the first preset time period, and the first preset time period begins after the second preset time period. The control module 14 can control the fifth switch K5 to conduct for the first preset time period after controlling the first switch K1 and the fourth switch K4 to conduct for the second preset time period and controlling the second switch K2 and the third switch K3 to conduct for the third preset time period. Alternatively, the control module 14 can control the first switch K1 and the fourth switch K4 to conduct for the second preset time period after controlling the second switch K2 and the third switch K3 to conduct for the third preset time period. In this case, it is preferable that the second preset time period and the first preset time period are continuous and without interruption.

[0041] In some embodiments, the start time of the second preset time period may be earlier than or equal to the start time of the first preset time period, and the end time of the second preset time period may be equal to the end time of the first preset time period. That is, the control module 14 can control the first switch K1 and the fourth switch K4 to be turned on, and control the second switch K2 and the third switch K3 to be turned off at a time earlier than or equal to the turn-on time of the fifth switch K5. Alternatively, the control module 14 can control the first switch K1 and the fourth switch K4 to be turned off, control the second switch K2 and the third switch K3 to be turned on at a time earlier than or equal to the turn-on time of the fifth switch K5, and control the fifth switch K5 to be turned on for the first preset time period.

[0042] In some embodiments, the control module 14 can control the first switch K1, the second switch K2, and the third switch K3 to turn off the third preset time period, and control the fourth switch K4 to turn on the third preset time period; or, the control module 14 can control the first switch K1, the third switch K3, and the fourth switch K4 to turn off the third preset time period, and control the second switch K2 to turn on the third preset time period; wherein the start time and end time of the third preset time period are the same as those of the first preset time period.

[0043] In this embodiment, when the control module 14 controls the first switch K1, the second switch K2, and the third switch K3 to turn off for a third preset time period, and controls the fourth switch K4 to turn on for a third preset time period, the voltage supply terminal VX, the series-connected energy-consuming element 13, the fifth switch K5, the first capacitor C1, the fourth switch K4, and the common terminal GND form a fifth path. When the control module 14 controls the first switch K1, the third switch K3, and the fourth switch K4 to turn off for a third preset time period, and controls the second switch K2 to turn on for a third preset time period, the voltage supply terminal VX, the series-connected energy-consuming element 13, the fifth switch K5, the inductor L, the second switch K2, and the common terminal GND form a sixth path.

[0044] In some embodiments, during a first preset time period, the control module 14 can control the first switch K1 and the third switch K3 to turn off, and the second switch K2 and the fourth switch K4 to turn on; or, during the first preset time period, the control module 14 can control the first switch K1 and the third switch K3 to turn on, and the second switch K2 and the fourth switch K4 to turn off.

[0045] In this embodiment, when the control module 14 controls the first switch K1 and the third switch K3 to turn off and the second switch K2 and the fourth switch K4 to turn on during the first preset time period, the voltage supply terminal VX, the series-connected energy-consuming element 13, the fifth switch K5, the second switch K2, and the common terminal GND form a seventh path, and the voltage supply terminal VX, the series-connected energy-consuming element 13, the fifth switch K5, the fourth switch K4, and the common terminal GND form an eighth path. During the first preset time period, when the control module 14 controls the first switch K1 and the third switch K3 to turn on and the second switch K2 and the fourth switch K4 to turn off, the input terminal VIN, the first switch K1, the inductor L, the series-connected energy-consuming element 13, the fifth switch K5, and the voltage supply terminal VX form a ninth path, and the input terminal VIN, the third switch K3, the first capacitor C1, the series-connected energy-consuming element 13, the fifth switch K5, and the voltage supply terminal VX form a tenth path.

[0046] In some embodiments, after the first common contact X1 establishes the starting voltage, the second switch K2 and the fourth switch K4 can be turned on, while the first switch K1, the third switch K3, and the fifth switch K5 are turned off, so that the first common contact X1 is in a free oscillation state.

[0047] In some embodiments, the fourth switch K4 and the fifth switch K5 can be turned on first, while the first switch K1, the second switch K2, and the third switch K3 are turned off. After the initial voltage is established at the first common contact X1, the first switch K1, the third switch K3, and the fifth switch K5 are turned off, while the second switch K2 and the fourth switch K4 are turned on, so that the first common contact X1 is in a free oscillation state.

[0048] In some embodiments, such as Figure 2 As shown, the second common contact point X2 is formed by the second switch K2 and the fourth switch K4, and a second resistor R2 is provided between the second common contact point X2 and the common terminal GND.

[0049] In this embodiment, based on the second resistor R2, current detection can be performed based on the second common contact point X2 to determine whether the current is abnormal during wireless charging, and the oscillation amplitude can be adjusted based on the second resistor R2 to easily obtain a suitable oscillation waveform at the first common contact point X1.

[0050] In some embodiments, the energy-consuming element 13 can be a resistor, and the larger the resistance value, the shorter the time to establish the initial voltage.

[0051] In some embodiments, the detection module 15 may also include an effective wave counting method.

[0052] This invention also provides a foreign object detection chip, which includes a foreign object detection circuit as described in any of the above embodiments.

[0053] Since the circuit structure and operation mode of the foreign object detection circuit in the foreign object detection chip in this embodiment are the same as those in the previous embodiment, they will not be described again here.

[0054] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A foreign object detection circuit, comprising a first half-bridge and a second half-bridge connected in parallel between an input terminal and a common terminal, wherein an inductor and a first capacitor are connected in series between a half-bridge node of the first half-bridge and a half-bridge node of the second half-bridge, the first half-bridge comprising a first switching transistor and a second switching transistor, and the second half-bridge comprising a third switching transistor and a fourth switching transistor, characterized in that, include: The fifth switching transistor and the energy-consuming element, connected in series, are connected between the voltage supply terminal and the first common contact point formed by the inductor and the first capacitor; The control module, which is connected to the controlled terminal of each switch, controls the fifth switch to turn on for a first preset time period and then turn off. In conjunction with the first switch, the second switch, the third switch, and the fourth switch, the first switch actively establishes an initial voltage for the first common contact point through the voltage supply terminal. The detection module connected to the first common contact point controls the on / off states of the first, second, third, and fourth switching transistors after the first switching transistor is turned on for a first preset time period, so that the first common contact point can oscillate freely, and the detection module detects the voltage of the first common contact point to determine whether there is a foreign object. The control module controls the first switch and the fourth switch to conduct for a second preset time period, and controls the second switch and the third switch to turn off for the second preset time period; or, the control module controls the first switch and the fourth switch to turn off for the second preset time period, and controls the second switch and the third switch to conduct for the second preset time period. The first preset time period is within the second preset time period.

2. The foreign object detection circuit according to claim 1, characterized in that, The detection module uses envelope detection and includes the following components: A diode, the anode of which is connected to the first common junction; A first resistor and a second capacitor are connected in parallel between the first common contact and the common terminal; the second capacitor has established its operating point when the first common contact has established an initial voltage.

3. The foreign object detection circuit according to claim 1, characterized in that, The start time of the second preset time period is earlier than or equal to the start time of the first preset time period, and the end time of the second preset time period is equal to the end time of the first preset time period.

4. The foreign object detection circuit according to claim 1, characterized in that, The control module controls the first switch, the second switch, and the third switch to turn off for a third preset time period, and controls the fourth switch to turn on for the third preset time period; or, the control module controls the first switch, the third switch, and the fourth switch to turn off for the third preset time period, and controls the second switch to turn on for the third preset time period. The start and end times of the third preset time period are the same as those of the first preset time period.

5. The foreign object detection circuit according to claim 1, characterized in that, The second common contact formed by the second switch and the fourth switch has a second resistor provided between the second common contact and the common terminal.

6. The foreign object detection circuit according to claim 1, characterized in that, The energy-consuming element is a resistor, and the larger the resistance value of the resistor, the shorter the time to establish the initial voltage.

7. A foreign object detection chip, characterized in that, Includes the foreign object detection circuit as described in any one of claims 1 to 6 above.

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