Inductive power supply and object detection method therefor

Abstract

The present disclosure provides an inductive power supply. A resonant signal is generated when a resonant capacitor resonates with a power coil. A driving unit outputs a driving signal to drive the power coil. A voltage detector receives the resonant signal and converts it into a detection signal. A processor controls the driving unit and acquires a resonant period of the resonant signal according to the detection signal when the resonant capacitor resonates with the power coil. When the driving unit drives the power coil, the resonant capacitor resonates with the power coil, and a timer of the processor starts timing. When the resonant period exceeds a period threshold, the timer stops timing, and the processor calculates a measured time length obtained from the time when the timer starts timing to the time when the timer stops timing. The processor determines that an object exists in a power transmission range of the power supply module when the measured time length is less than a preset time length. The present disclosure also relates to an object detection method of an inductive power supply.

Description

Technical Field

[0001] This disclosure relates to an inductive power supply and a method for detecting objects thereon, and particularly to an inductive power supply and a method for detecting objects thereon that improves detection accuracy. Background Technology

[0002] In inductive power supplies (such as wireless charging devices that transmit energy via coil induction), foreign object detection (FOD) is a crucial safety mechanism. It detects the presence of metallic foreign objects around the power supply module. If a metallic foreign object is present around the power supply module when the power supply coil is activating power transmission but before power is being officially transmitted to the receiving module, the temperature of the foreign object will rise rapidly, posing a danger.

[0003] In existing inductive power sensors, the presence of metallic foreign objects around the power supply coil is often determined by the resonant signal generated by the power supply coil and capacitor on the power supply module. This detection method directly uses the attenuated voltage of the resonant signal for discrimination. However, in the low-signal range, this resonant signal is easily confused with noise, resulting in low detection accuracy. Furthermore, since the resonant signal generated by the power supply coil and capacitor has only a single frequency characteristic, it can only produce a large response to a single type of metallic foreign object, meaning it can only detect a single type of metal, thus having poor versatility.

[0004] Therefore, developing an inductive power supply and its object detection method that can improve upon the shortcomings of the existing technology is an urgent need. Summary of the Invention

[0005] The purpose of this disclosure is to provide an inductive power supply and a method for detecting objects therein. This method utilizes the resonant period of a resonant signal and the total duration of the resonant period within a specific range to determine whether an object exists within the power transmission range of the power supply module. This object detection method is less susceptible to noise, thus improving detection accuracy.

[0006] According to one aspect of the present disclosure, an inductive power supply is provided, comprising a power supply module, a resonant capacitor, a drive unit, a voltage detector, and a processor. The power supply module includes a power supply coil. The resonant capacitor is electrically connected to a first end of the power supply coil. A node is formed between the first end of the power supply coil and the resonant capacitor, and the power supply coil and the resonant capacitor form a resonant circuit. When the resonant capacitor and the power supply coil resonate, a resonant signal is generated. The drive unit is electrically connected to the resonant capacitor and outputs a drive signal to drive the power supply coil. The voltage detector is electrically connected to the node to receive the resonant signal and convert it into a detection signal. The processor is electrically connected to the voltage detector and the drive unit, and controls the drive unit. When the resonant capacitor and the power supply coil resonate, the processor obtains the resonant period of the resonant signal based on the detection signal. After the drive unit drives the power supply coil, the resonant capacitor and the power supply coil resonate, and the processor's timer starts counting. When the resonant period exceeds a period threshold, the timer stops counting, and the processor calculates the measurement duration from the start of the timer to its stop. If the measurement duration is less than a preset duration, the processor determines that an object exists within the power transmission range of the power supply module.

[0007] According to another aspect of the present disclosure, the present disclosure provides an object detection method for an inductive power supply, comprising the steps of: (a) after the driving unit drives the power supply coil, resonating the resonant capacitor and the power supply coil to generate a resonant signal, and controlling the processor's timer to start timing; (b) receiving the resonant signal using a voltage detector and converting the resonant signal into a detection signal; (c) when the resonant period exceeds a period threshold, controlling the timer to stop timing; (d) using the processor to calculate the measurement duration from the start of timing to the stop of timing; and (e) using the processor to determine that an object exists within the power transmission range of the power supply module when the measurement duration is less than a preset duration. Attached Figure Description

[0008] Figure 1 This is a schematic diagram of the circuit structure of an inductive power supply according to a preferred embodiment of the present disclosure.

[0009] Figure 2 for Figure 1 A schematic diagram of the drive signal of the drive unit, the resonant signal of the power supply coil, and the detection signal of the voltage detector.

[0010] Figure 3 for Figure 2 Enlarged view of box A in the middle.

[0011] Figure 4 When the change value is greater than the preset change value, Figure 1 A schematic diagram of the drive signal of the drive unit, the resonant signal of the power supply coil, and the detection signal of the voltage detector.

[0012] Figure 5 This is a schematic diagram of the circuit structure of an inductive power supply according to another preferred embodiment of the present disclosure.

[0013] Figure 6 This is a schematic diagram of the circuit structure of an inductive power supply according to another preferred embodiment of the present disclosure.

[0014] Figure 7 This is a flowchart of an object detection method for an inductive power supply according to a preferred embodiment of the present disclosure.

[0015] Figure 8 and Figure 9 This is a flowchart of an object detection method for an inductive power supply according to another preferred embodiment of the present disclosure.

[0016] Figure 10 and Figure 11 This is a flowchart of an object detection method for an inductive power supply according to another preferred embodiment of the present disclosure.

[0017] Explanation of reference numerals in the attached figures:

[0018] 1, 1a, 1b, 1c: Inductive power supply

[0019] 2: Power supply module

[0020] 20: Power supply coil

[0021] 201: First End

[0022] 202: Second End

[0023] 30, 30a: Resonant capacitors

[0024] 31, 31a: Drive unit

[0025] 32: Voltage detector

[0026] 4: Processor

[0027] A: Box

[0028] O: Node

[0029] S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S100: Steps Detailed Implementation

[0030] Some typical embodiments embodying the features and advantages of this disclosure will be described in detail in the following description. It should be understood that this disclosure can be varied in different implementations without departing from the scope of this disclosure, and the descriptions and illustrations therein are for illustrative purposes only and are not intended to limit this disclosure.

[0031] Figure 1 This is a schematic diagram of the circuit structure of an inductive power supply 1 according to a preferred embodiment of this disclosure. Figure 1 As shown, the inductive power supply 1 includes a power supply module 2, a resonant capacitor 30, a drive unit 31, a voltage detector 32, and a processor 4. The power supply module 2 includes a power supply coil 20, and the resonant capacitor 30 is electrically connected to the first end 201 of the power supply coil 20. There is a node O between the first end 201 of the power supply coil 20 and the resonant capacitor 30, and the power supply coil 20 and the resonant capacitor 30 form a resonant circuit. When the resonant capacitor 30 resonates with the power supply coil 20, a resonant signal is generated.

[0032] The drive unit 31 is electrically connected to the resonant capacitor 30 and outputs a drive signal to drive the power supply coil 20. A resonant signal is generated when the resonant capacitor 30 resonates with the power supply coil 20. The voltage detector 32 is electrically connected to node O to receive the resonant signal and convert it into a detection signal.

[0033] Processor 4 is electrically connected to voltage detector 32 and drive unit 31. Processor 4 controls drive unit 31 and acquires the resonance period of the resonant signal based on the detection signal when resonant capacitor 30 resonates with power supply coil 20. Processor 4 may be, for example, but not limited to, a microcontroller (MCU). In some embodiments, processor 4 controls drive unit 31 with software.

[0034] Please also refer to Figure 1 , 2 and 3, Figure 2 for Figure 1 A schematic diagram of the driving signal of the driving unit 31, the resonant signal of the power supply coil 20, and the detection signal of the voltage detector 32. Figure 3 for Figure 2Enlarged view of box A. When the driving unit 31 outputs a high-level driving signal (i.e., the driving unit 31 drives the power supply coil 20), the resonant capacitor 30 and the power supply coil 20 begin to resonate, generating a resonant signal. At this time, the voltage detector 32 receives the resonant signal and converts it into a detection signal. In this disclosure, the resonant signal generated on the power supply coil 20 corresponds to the detection signal converted by the voltage detector 32. The resonant signal and the detection signal are a sine wave and a digital signal, respectively, and the digital signal can be, for example, but not limited to, a square wave. When the value of the resonant signal (sine wave) is greater than zero, the voltage detector 32 converts the resonant signal into a high-level detection signal (square wave); conversely, when the value of the resonant signal (sine wave) is less than zero, the voltage detector 32 converts the resonant signal into a zero-level detection signal (square wave). Furthermore, since the resonant signal and the detection signal correspond to each other and have the same period, the processor 4 can obtain the resonant period of the resonant signal based on the period of the detection signal, wherein the period of the detection signal is the time difference between the rising edges of two adjacent square waves.

[0035] When the driving unit 31 drives the power supply coil 20, the resonant capacitor 30 resonates with the power supply coil 20, and the timer of the processor 4 starts counting. The timer of the processor 4 starts counting at the rising edge of the first square wave of the detection signal. In some embodiments, the timer of the processor 4 is not limited to starting counting at the rising edge of the first square wave of the detection signal; the timer may start counting at the rising edge of the second or third square wave of the detection signal.

[0036] When the resonant period of the resonant signal exceeds the period threshold, the timer stops counting, and the processor 4 calculates the measurement duration from the start of the timer to its stop. In this disclosure, the measurement duration represents the attenuation rate of the resonant signal. If an object is present within the power transmission range of the power supply module 2, the resonant signal will attenuate faster due to the additional resistance generated by the object. Therefore, the attenuation rate of the resonant signal is faster when an object is present within the power transmission range than when no object is present. In some embodiments, the processor 4 calculates the period threshold based on the average value of multiple periods of the detection signal. The multiple periods can be selected from the 1st to the Nth period of the detection signal, where N is greater than 1 and less than or equal to 3. The period of the detection signal is defined as the duration between the rising edges of two adjacent square waves.

[0037] Therefore, the processor 4 determines that an object exists within the power transmission range of the power supply module 2 when the measurement duration is less than the preset duration; conversely, the processor 4 determines that no object exists within the power transmission range of the power supply module 2 when the measurement duration is greater than the preset duration. In some embodiments, the object may be a receiving device or a metallic foreign object. The receiving device is correspondingly located within the power transmission range of the power supply module 2 of the inductive power supply 1 to receive electrical energy provided by the power supply coil 20 of the power supply module 2. The metallic foreign object is a metal that cannot accept electrical energy.

[0038] This disclosure utilizes the resonant period of a resonant signal and the total duration of the resonant period within a specific range to determine the presence of an object within the power transmission range of the power supply module. This object detection method is less susceptible to noise, thus improving detection accuracy.

[0039] When the measurement duration acquired by the processor 4 is less than the preset duration, the inductive power supply 1 of this disclosure can further determine whether the object within the power transmission range of the power supply module 2 is a receiving device or a metallic foreign object using the resonant signal. Specifically, the processor 4 records the maximum and minimum period values ​​of the resonant signal during the timing process of the timer, and obtains the variation value based on the maximum and minimum period values. In this disclosure, the maximum period value is the maximum value of the resonant period, and the minimum period value is the minimum value of the resonant period. Since the resonant signal and the detection signal correspond to each other and have the same period, the maximum and minimum values ​​of the resonant period of the resonant signal can be obtained through the period of the detection signal, thereby obtaining the variation value representing the amplitude of the resonant period variation. If the object within the power transmission range of the power supply module 2 is a receiving device, the amplitude of the resonant signal variation is larger than when the object within the power transmission range is a metallic foreign object. The reason is explained below.

[0040] The receiving coil of the power receiving device is connected to the rectifier and the filter capacitor. When the filter capacitor is not yet charged, it rapidly absorbs power. At this time, because the input signal to the rectifier is less than the component specifications, the rectifier will not operate and will be in an open-circuit state. The rectifier will only operate when the input signal is greater than the component specifications. Therefore, the circuit characteristics of the power receiving device (changes in the rectifier's operating state) affect the resonant signal, causing a significant variation in the resonant period. On the other hand, if the object within the power transmission range of power module 2 is a metallic foreign object, the metallic foreign object will continuously absorb electrical energy, causing the resonant signal to decay rapidly. Due to the continuous energy absorption characteristics of the metallic foreign object, the change in the resonant signal is linear, thus the variation in the resonant period is relatively small.

[0041] Therefore, when the measurement duration is less than the preset duration and the change value is greater than the preset change value, the processor 4 determines that the object within the power transmission range of the power supply module 2 is a receiving device. Conversely, when the measurement duration is less than the preset duration and the change value is less than the preset change value, the processor 4 determines that the object within the power transmission range of the power supply module 2 is a metallic foreign object. Please refer to [link / reference]. Figure 4 , Figure 4 This is a schematic diagram showing the driving signal of the driving unit 31, the resonant signal of the power supply coil 20, and the detection signal of the voltage detector 32 when the change value exceeds the preset change value. Figure 4 It can be seen that the change value obtained from the maximum and minimum values ​​of the cycle is greater than the preset change value. Therefore, the processor 4 determines that the object within the power transmission range of the power supply module 2 is a power receiving device.

[0042] Please refer to the following: Figure 1 When the resonant capacitor 30 resonates with the power supply coil 20, it has a resonant frequency, and the capacitance value of the resonant capacitor 30 affects the resonant frequency. In other words, the resonant frequency is determined by the capacitance value of the resonant capacitor 30. In some embodiments, the resonant frequency is determined by the resonant capacitor 30 and the power supply coil 20. If the same power supply coil 20 is used, the resonant frequency is determined by the resonant capacitor 30. Furthermore, the resonant frequency corresponds to a preset duration and a preset variation value. Therefore, when the resonant capacitor 30 has different capacitance values, the resonant frequency is different, and different resonant frequencies correspond to different preset durations and preset variation values. Thus, it can be seen that the capacitance value of the resonant capacitor 30 can determine the resonant frequency and its corresponding preset duration and preset variation value. Therefore, based on the preset duration and preset variation value determined by the capacitance value of the resonant capacitor 30, the processor 4 can determine whether there is an object within the power transmission range of the power supply module 2 during the resonance process by using the relationship between the measured duration and the preset duration, and determine whether the object within the power transmission range of the power supply module 2 is a receiving device or a metallic foreign object by using the relationship between the variation value and the preset variation value.

[0043] Please see Figure 5 , Figure 5This is a schematic diagram of the structure of an inductive power supply 1a according to another preferred embodiment of the present disclosure. Components with similar structures and functions to those in the inductive power supply 1a of the present disclosure are represented by the same reference numerals and will not be described again here. In this embodiment, the inductive power supply 1a has a plurality of resonant capacitors 30 and a plurality of driving units 31. Each resonant capacitor 30 is electrically connected to a corresponding driving unit 31. Each resonant capacitor 30 and its corresponding driving unit 31 are electrically connected between the processor 4 and the first end 201 of the power supply coil 20. Each resonant capacitor 30 is electrically connected to node O. The processor 4 controls at least one driving unit 31 to output a driving signal to the corresponding resonant capacitor 30, causing the corresponding resonant capacitor 30 and the power supply coil 20 to form a resonant circuit and resonate, generating a resonant signal. The resonant frequency is determined by the sum of the capacitance values ​​of the resonant capacitors 30 that resonate with the power supply coil 20. In some embodiments, the processor 4 controls a plurality of drive units 31 to output drive signals to their respective resonant capacitors 30, causing the corresponding resonant capacitors 30 to resonate with the power supply coil 20 and generate a resonant signal. The resonant frequency is determined by the sum of the capacitance values ​​of the plurality of resonant capacitors 30. This disclosure controls the number of resonant capacitors 30 resonating with the power supply coil 20, thus generating a variety of different resonant frequencies, each corresponding to a specific preset duration and preset variation value.

[0044] In the above embodiment with multiple resonant capacitors 30 and multiple driving units 31, the various resonant frequencies generated by controlling the number of resonant capacitors 30 resonating with the power supply coil 20 can be used to determine whether there are different types of metallic foreign objects within the power transmission range of the power supply module 2. Specifically, each type of metallic foreign object has its own metallic characteristics, and different metallic characteristics correspond to different resonant frequencies. Therefore, different types of metallic foreign objects correspond to different resonant frequencies. Thus, specific types of metallic foreign objects can be detected using specific resonant frequencies and their corresponding preset durations and preset variation values.

[0045] In some embodiments, a plurality of resonant capacitors 30 may form a plurality of resonant capacitor combinations according to their respective resonant states, wherein a resonant capacitor combination represents the resonant capacitors 30 that resonate with the power supply coil 20 among the plurality of resonant capacitors 30. Specifically, when multiple resonant capacitors 30 receive the drive signal from their respective drive units 31 and resonate with the power supply coil 20, all the resonant capacitors 30 resonating with the power supply coil 20 form a resonant capacitor combination. Therefore, when different combinations of resonant capacitors 30 among the plurality of resonant capacitors 30 resonate with the power supply coil 20, these different combinations of resonant capacitors 30 form different resonant capacitor combinations.

[0046] In this disclosure, the resonant signal decays rapidly, and in some embodiments, the measurement duration is less than one-thousandth of a second. Therefore, the time required to detect a specific type of metallic foreign object using a single resonant frequency is much shorter than the user's perceived time (e.g., the time it takes for a metal foreign object to move near the powered device or onto the power supply module 2), thus eliminating any perceived detection delay and allowing detection with minimal power consumption. Furthermore, if detection is performed using different resonant frequencies until all different resonant frequencies have been detected, since each detection time is much shorter than the user's perceived time, even after all resonant frequencies have been detected, there is no perceived detection delay.

[0047] In the inductive power supply 1 disclosed herein, the connection relationship of the second terminal 202 of the power supply coil 20 of the power supply module 2 is not limited. For example, it can be grounded or electrically connected to other resonant capacitors and driving units. An embodiment in which the second terminal 202 of the power supply coil 20 of the power supply module 2 is grounded is as follows: Figure 1 and Figure 5 As shown, in an embodiment where the second end 202 of the power supply coil 20 of the power supply module 2 is electrically connected to other resonant capacitors and the driving unit, the connection is as follows: Figure 6 As shown.

[0048] Please see Figure 6 , Figure 6 This is a schematic diagram of the structure of an inductive power supply 1b according to another preferred embodiment of the present disclosure. Components with similar structures and functions to those in the inductive power supply 1b of this disclosure are represented by the same reference numerals and will not be described again here. In this embodiment, the inductive power supply 1b further includes a plurality of resonant capacitors 30a and a plurality of driving units 31a. The resonant capacitors 30a are electrically connected to their corresponding driving units 31a. The resonant capacitors 30a and their corresponding driving units 31a are electrically connected between the second end 202 of the power supply coil 20 and the processor 4. The driving units 31a are electrically connected to the processor 4, and the resonant capacitors 30a are electrically connected to the second end 202 of the power supply coil 20. Figure 6 The embodiment shown uses two resonant capacitors 30a and two driving units 31a as an example, but the actual number is not limited to this.

[0049] Figure 7 This is a flowchart illustrating a preferred embodiment of an object detection method for an inductive power supply. The object detection method of this embodiment is applicable to the aforementioned inductive power supply 1. Please also refer to... Figure 1 and Figure 7The method disclosed herein includes steps S1, S2, S3, S4, S5, S6, and S7. In step S1, after the driving unit 31 drives the power supply coil 20, the resonant capacitor 30 and the power supply coil 20 resonate to generate a resonant signal, and the timer of the processor 4 is started. In step S2, the voltage detector 32 receives the resonant signal and converts it into a detection signal. In step S3, when the resonant period exceeds the period threshold, the timer is stopped. In step S4, the processor 4 calculates the measurement duration from the start of the timer to its stop. In step S5, the processor 4 determines whether the measurement duration is less than a preset duration. If the determination result of step S5 is yes, i.e., the measurement duration is less than the preset duration, step S6 is executed. Conversely, if the determination result of step S5 is no, i.e., the measurement duration is greater than the preset duration, step S7 is executed. In step S6, it is determined that an object exists within the power transmission range of the power supply module 2. In step S7, it is determined that there are no objects within the power transmission range of the power supply module 2.

[0050] Figure 8 and Figure 9 This is a flowchart of an object detection method for an inductive power supply 1 according to another preferred embodiment of the present disclosure. The object detection method for the inductive power supply 1 in this embodiment is applicable to... Figure 1 The inductive power supply 1 and the aforementioned object detection method. Please also refer to... Figure 1 , 8 In addition to step S6, the object detection method of the inductive power supply 1 disclosed herein further includes steps S8, S9, S10, S11, and S12. In step S8, the processor 4 records the maximum and minimum period values ​​of the resonant signal during the timing process, and obtains the variation value based on the maximum and minimum period values. In step S9, it is determined whether the variation value is greater than a preset variation value. If the determination result of step S9 is yes, i.e., the variation value is greater than the preset variation value, step S10 is executed. Conversely, if the determination result of step S9 is no, i.e., the variation value is less than the preset variation value, step S11 is executed. In step S10, the processor 4 determines that the object within the power transmission range of the power supply module 2 is a receiving device, and executes S12 after completing step S10. In step S11, the processor 4 determines that the object within the power transmission range of the power supply module 2 is a metallic foreign object, and prohibits power transmission from the power supply module 2. In step S12, power transmission from the power supply module 2 is allowed.

[0051] Figure 10 and 11 This is a flowchart of an object detection method for an inductive power supply 1a according to another preferred embodiment of the present disclosure. The object detection method for the inductive power supply 1a in this embodiment is applicable to... Figure 5The inductive power supply 1a and the aforementioned object detection method. Please also refer to... Figure 5 , 10 In addition to step S1, the object detection method of the inductive power supply 1a disclosed herein further includes step S100 in step S1. In step S100, at least one drive unit 31 is controlled to output a drive signal to the corresponding resonant capacitor 30, so that the corresponding resonant capacitor 30 resonates with the power supply coil 20 to generate a resonant signal, and the timer of the processor 4 starts timing at the start time. In this embodiment, step S13 is further included after steps S7 and S10. In step S13, it is determined whether all the resonant capacitor combinations of the plurality of resonant capacitors 30 have resonated with the power supply coil 20 to generate the resonant signal. When the determination result of step S13 is yes, that is, all the resonant capacitor combinations of the plurality of resonant capacitors 30 have resonated with the power supply coil 20 to generate the resonant signal, step S12 is executed. Conversely, if the judgment result of step S13 is negative, that is, if not all of the multiple resonant capacitor combinations of the multiple resonant capacitors 30 resonate with the power supply coil 20 to generate a resonant signal, step S100 is executed again, and in step S100, the resonant capacitor combination that does not resonate with the power supply coil 20 among the multiple resonant capacitor combinations is selected to resonate.

[0052] In summary, the inductive power supply and its object detection method disclosed herein determine the presence of an object within the power transmission range of the power supply module by utilizing the resonant period of the resonant signal and the total duration of the resonant period within a specific range. This object detection method is less susceptible to noise, thus improving detection accuracy.

[0053] It should be noted that the above are merely preferred embodiments for illustrating this disclosure, and this disclosure is not limited to the described embodiments. The scope of this disclosure is determined by the scope of the patent application. Furthermore, this disclosure may be modified in various ways by those skilled in the art, but all such modifications shall not depart from the scope of protection sought in the patent application.

Claims

1. An inductive power supply, comprising: A power supply module, comprising a power supply coil; A resonant capacitor is electrically connected to a first terminal of the power supply coil, wherein, There is a node between the first end of the power supply coil and the resonant capacitor, and the power supply coil and the resonant capacitor form a resonant circuit. When the resonant capacitor and the power supply coil resonate, a resonant signal is generated. A driving unit is electrically connected to the resonant capacitor and outputs a driving signal to drive the power supply coil. A voltage detector is electrically connected to the node to receive the resonant signal and convert the resonant signal into a detection signal; as well as A processor is electrically connected to the voltage detector and the drive unit. The processor controls the drive unit and, when the resonant capacitor resonates with the power supply coil, acquires a resonant period of the resonant signal based on the detection signal. When the driving unit drives the power supply coil, the resonant capacitor resonates with the power supply coil, and a timer of the processor starts counting. When the resonant period exceeds a one-period threshold, the timer stops counting. The processor calculates the measurement duration from the start of the timer to the stop of counting. The processor determines that an object exists within the power transmission range of the power supply module when the measurement duration is less than a preset duration.

2. The inductive power supply as described in claim 1, wherein, When the measurement duration exceeds the preset duration, the processor determines that the object does not exist within the power transmission range of the power supply module.

3. The inductive power supply as described in claim 1, wherein, The resonant capacitor has a resonant frequency when it resonates with the power supply coil, and the resonant frequency corresponds to the preset duration.

4. The inductive power supply as described in claim 3, wherein, The processor records the maximum and minimum values ​​of the resonant signal during the timing process and obtains a variation value based on the maximum and minimum values. When the measurement duration is less than the preset duration and the variation value is greater than a preset variation value, the processor determines that the object within the power transmission range of the power supply module is a power receiving device. When the measurement duration is less than the preset duration and the variation value is less than the preset variation value, the processor determines that the object within the power transmission range of the power supply module is a metallic foreign object. In this case, the power receiving device receives power from the power supply module.

5. The inductive power supply as described in claim 4, wherein, The resonant frequency corresponds to the preset variation value, and the capacitance value of the resonant capacitor affects the resonant frequency.

6. The inductive power supply as claimed in claim 1 further comprises a plurality of resonant capacitors and a plurality of driving units, wherein, Each resonant capacitor is electrically connected to the corresponding driving unit. Each resonant capacitor and the corresponding driving unit are electrically connected between the processor and the first terminal of the power supply coil. Each resonant capacitor is electrically connected to the node. The processor controls at least one driving unit to output the driving signal to the corresponding resonant capacitor, so that the corresponding resonant capacitor resonates with the power supply coil and generates the resonant signal.

7. The inductive power supply as described in claim 6, wherein, When the corresponding resonant capacitor resonates with the power supply coil, it has a resonant frequency, and the resonant frequency corresponds to the preset duration.

8. A method for detecting objects in an inductive power supply, applicable to the inductive power supply as described in claim 1, wherein the method comprises the steps of: (a) When the driving unit drives the power supply coil, it uses the resonant capacitor and the power supply coil to resonate to generate the resonant signal, and controls the processor's timer to start timing; (b) Using the voltage detector to receive the resonant signal and convert the resonant signal into the detection signal; (c) When the resonant period exceeds the period threshold, control the timer to stop counting; (d) Calculate the measurement duration from the start of the timer to its stop using the processor; and (e) If the measurement duration is less than the preset duration, it is determined that the object exists within the power transmission range of the power supply module.

9. The object detection method for an inductive power supply as described in claim 8, wherein, When the resonant capacitor resonates with the power supply coil, it has a resonant frequency, and the resonant frequency corresponds to the preset duration. The capacitance value of the resonant capacitor affects the resonant frequency.

10. The object detection method for an inductive power supply as described in claim 8, further comprising the step of: (f) If the measurement duration is longer than the preset duration, it is determined that the object does not exist within the power transmission range of the power supply module.

11. The object detection method for an inductive power supply as described in claim 10, wherein, Step (e) is followed by the following steps: (g) Using the processor, record a maximum and a minimum value of the resonant signal during the timing process, and obtain a variation value based on the maximum and minimum values; and (h) Determine whether the change value is greater than a preset change value.

12. The object detection method for an inductive power supply as described in claim 11, wherein step (h) further comprises the step of: (h1) When the judgment result of step (h) is yes, the processor determines that the object within the power transmission range of the power supply module is a power receiving device, and executes step (i) after completing step (h1). (h2) If the determination result of step (h) is negative, the processor determines that the object within the power transmission range of the power supply module is a metallic foreign object, and prohibits the power transmission of the power supply module; and (i) Allow power transmission to the power supply module.

13. The object detection method for an inductive power supply as described in claim 12, wherein, The inductive power supply also includes a plurality of the resonant capacitors and a plurality of the driving units, wherein step (a) further includes the step: (a1) Control at least one of the drive units to output the drive signal to the corresponding resonant capacitor, so that the corresponding resonant capacitor resonates with the power supply coil to generate the resonant signal, and control the processor's timer to start counting at the start time.

14. The object detection method for an inductive power supply as described in claim 13, wherein, The steps following step (f) and step (h1) include: (k) Determine whether the combination of the multiple resonant capacitors has resonated with the power supply coil to generate the resonant signal. If the determination result of step (k) is yes, execute step (i); if the determination result of step (k) is no, execute step (a1). The combination of the multiple resonant capacitors is composed of the resonant states of the multiple resonant capacitors.

15. The object detection method for an inductive power supply as described in claim 14, wherein, The at least one resonant capacitor has a resonant frequency when it resonates with the power supply coil, and the resonant frequency corresponds to the preset duration.

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