TWI669880B - Method of detecting intruding metal for induction type power supply system and related supplying-end module - Google Patents

Abstract

A metal foreign object detection method for a power supply module of an inductive power supply. The power supply module includes a power supply coil. The metal foreign object detection method includes at least interrupting the inductive power supply during a measurement period. A driving signal to stop driving the power supply coil to generate a coil signal of the power supply coil; measuring the multiple peaks of the coil signal during successive oscillation cycles of the coil signal to obtain a plurality of peak trigger voltages respectively ; Calculating a first attenuation parameter according to a first peak trigger voltage and a second peak trigger voltage of the plurality of peak trigger voltages; and comparing the first attenuation parameter with a first threshold value to determine the inductive type Whether a metal foreign object exists in the power transmission range of one of the power supplies.

Description

Method for detecting metal foreign body in inductive power supply and power supply module thereof

The present invention relates to a method for detecting a foreign metal object, and more particularly to a method for detecting a foreign metal object that can be used in an inductive power supply.

In an inductive power supply, the power supply end drives the power supply coil to resonate through a drive circuit, and then emits radio frequency electromagnetic waves. The electromagnetic power is then converted through the power receiving coil to generate a DC power supply to the power receiving end device. If the electromagnetic energy sent by the power supply coil is applied to a metal body, it will have a heating effect. After the heat is accumulated, the metal body may cause high temperature to cause combustion and cause harm. In the prior art, the inductive power supply may periodically interrupt the driving during the power transmission process to detect metal foreign objects, and the judgment is made by measuring the change in the slope of the measurement. However, the power output by the coil at the power supply end will be adjusted at any time according to the distance between the power supply end and the power receiving end. For example, when the coil distance is far away, a higher power is output, and when the coil distance is closer, a lower power is output. With the change of output power, the amplitude of the coil signal also changes, so that the resonance signal attenuation will be different when the coil is interrupted. Therefore, when the power changes, the power supply needs to spend several detection cycles to adjust the voltage set by the comparator to track the signal peak. If the coil voltage is unstable due to power or load, it is difficult to lock the signal peak to determine the attenuation slope.

In addition, in order to determine the attenuation slope, the driving signal needs to be interrupted for a period of time. However, interrupting the driving signal during the wireless charging process will reduce the overall power output capability. If the interruption time is too long, it will affect the power supply efficiency, and re-engaging the driving signal after an excessively long interruption time is likely to cause excessive electromagnetic interference (Electromagnetic Interference, EMI). ). In the prior art, multiple peak voltage levels are obtained through a comparator module to determine the change in the slope of the coil signal attenuation in multiple stages, which requires a longer interruption time. Taking the patent case TW I577108 of the Republic of China as an example, it requires 7 to 15 different coil oscillation periods to complete the measurement of the four peak voltage levels to determine the change in the attenuation slope.

In view of this, it is necessary to propose another metal foreign object detection method, which can complete the detection in a very short interrupted driving time, while avoiding power or load changes affecting the effectiveness of metal foreign object detection.

Therefore, the main object of the present invention is to provide a metal foreign object detection method that can complete the detection in a very short interrupted driving time, which can complete the metal foreign object detection at least in 2 to 3 coil oscillation cycles. In addition, the method for detecting a metal foreign object of the present invention can be judged by the attenuation ratio of the coil signal, which can solve the disadvantage that the attenuation slope determination method of the prior art is easily affected by the coil amplitude and load.

The invention discloses a metal foreign object detection method for a power supply module of an inductive power supply. The power supply module includes a power supply coil. The metal foreign object detection method includes interrupting the inductive power supply during a measurement period. At least one driving signal of the generator to stop driving the power supply coil to generate a coil signal of the power supply coil; measuring a plurality of peaks of the coil signal during a plurality of consecutive oscillation cycles of the coil signal to obtain a plurality of each Peak trigger voltage; calculates a first trigger voltage based on a first peak trigger voltage and a second peak trigger voltage of the plurality of peak trigger voltages. An attenuation parameter; and comparing the first attenuation parameter with a first threshold value to determine whether a metal foreign object exists within a power transmission range of the inductive power supply.

The invention also discloses a power supply module for an inductive power supply, which is used to perform a metal foreign object detection method. The power supply module includes a power supply coil, a resonance capacitor, at least a power supply drive unit, and a signal receiving module. Group and a processor. The resonance capacitor is coupled to the power supply coil, and is used for resonance with the power supply coil. The at least one power supply driving unit is coupled to the power supply coil and the resonance capacitor, and is used to send at least one driving signal to the power supply coil to drive the power supply coil to generate energy, and interrupt the at least one driving signal during a measurement period to Stop driving the power supply coil to generate a coil signal of one of the power supply coils. The signal receiving module is coupled to the power supply coil for receiving the coil signal of the power supply coil. The processor is coupled to the signal receiving module, and is used to perform the following steps: measuring multiple peaks of the coil signal during a plurality of consecutive oscillation cycles of the coil signal to obtain a plurality of peak trigger voltages respectively; according to the complex number A first peak trigger voltage and a second peak trigger voltage among the peak trigger voltages are used to calculate a first attenuation parameter; and the first attenuation parameter is compared with a first threshold value to determine the value of the inductive power supply. Whether there is metal foreign matter in a power transmission range.

The invention further discloses a metal foreign object detection method for a power supply module of an inductive power supply. The power supply module includes a power supply coil, and the metal foreign object detection method includes a corresponding measurement obtained during a previous measurement period. One of the previous peak trigger voltages is set to a reference voltage value; at least one driving signal of the inductive power supply is interrupted during a measurement period to stop driving the power supply coil to generate a coil signal of the power supply coil; Measuring a first peak of the coil signal during an oscillation period of the coil signal to obtain a first peak trigger voltage; comparing the first peak trigger voltage with the reference voltage value; and when the first peak trigger voltage is equal to Or close to the reference When the voltage value is determined, it is determined that there is no metal foreign object in the power transmission range of one of the inductive power supplies.

100‧‧‧ Inductive Power Supply

1‧‧‧power supply module

10‧‧‧ Power Supply

111‧‧‧ processor

112‧‧‧Clock Generator

113‧‧‧Voltage generating device

114‧‧‧ Comparator

120‧‧‧Signal receiving module

121, 122‧‧‧ Power supply drive unit

130‧‧‧Divided voltage circuit

131, 132‧‧‧ divided voltage resistor

141, 142‧‧‧Resonant capacitor

16‧‧‧Power supply coil

161, 261‧‧‧ magnetic conductor

D1, D2‧‧‧ drive signal

C1‧‧‧coil signal

2‧‧‧ Power receiving module

21‧‧‧load unit

22‧‧‧Capacitor

230‧‧‧ rectifier circuit

241, 242‧‧‧Resonant capacitor

26‧‧‧Power receiving coil

3‧‧‧ metal foreign body

20、80‧‧‧ Metal foreign object detection process

200 ~ 222, 800 ~ 818‧‧‧ steps

CP1‧‧‧ comparison results

A, B, C, D, E, F‧‧‧ peaks

VB, VC, VD, VE, VF‧‧‧Peak trigger voltage

V0_B, V0_C, V0_D, V0_E, V0_F‧‧‧Trigger start potential

PAR1‧‧‧First attenuation parameter

PAR2‧‧‧Second attenuation parameter

PAR3‧‧‧Third attenuation parameter

PAR4‧‧‧Fourth attenuation parameter

TH1‧‧‧First critical value

TH2‧‧‧The second critical value

TH3‧‧‧three critical value

TH0‧‧‧Basic critical value

FIG. 1 is a schematic diagram of an inductive power supply according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a metal foreign object detection process according to an embodiment of the present invention.

FIG. 3 is a schematic diagram of stopping driving the power supply coil during a measurement period.

4 to 7 are schematic diagrams of obtaining a peak trigger voltage during a measurement period according to an embodiment of the present invention.

FIG. 8 is a schematic diagram of another metal foreign object detection process according to an embodiment of the present invention.

FIG. 9 is a schematic diagram of identifying a metal foreign object through a peak trigger voltage during a measurement period according to an embodiment of the present invention.

Please refer to FIG. 1. FIG. 1 is a schematic diagram of an inductive power supply 100 according to an embodiment of the present invention. As shown in FIG. 1, the inductive power supply 100 includes a power supply module 1 and a power receiving module 2. The power supply module 1 can receive power from a power supply 10 and output wireless power to the power receiving module 2. The power supply module 1 includes a power supply coil 16 and resonance capacitors 141 and 142, and is arranged in a C-L-C structure. The power supply coil 16 can be used to send electromagnetic energy to the power receiving module 2 for power supply. The resonance capacitors 141 and 142 are respectively coupled to both ends of the power supply coil 16 and can be used to resonate with the power supply coil 16 when power is supplied. In addition, in the power supply module 1, a magnetic conductor 161 made of a magnetic material may be selectively used to improve the electromagnetic induction capability of the power supply coil 16 while avoiding electromagnetic energy from affecting objects in the direction of the non-inductive surface of the coil.

In order to control the operation of the power supply coil 16 and the resonance capacitors 141 and 142, the power supply module 1 further includes A processor 111, a clock generator 112, power supply driving units 121 and 122, a signal receiving module 120, and a voltage dividing circuit 130. The power supply driving units 121 and 122 are coupled to the power supply coil 16 and the resonance capacitors 141 and 142, and can send driving signals D1 and D2 to the power supply coil 16, respectively. It can receive the control of the processor 111 to drive the power supply coil 16 to generate and send energy. When both the power supply driving units 121 and 122 are operated at the same time, full-bridge driving can be performed. In some embodiments, only one of the power supply driving units 121 and 122 may be turned on, or only one power supply driving unit 121 or 122 may be configured for half-bridge driving. The clock generator 112 is coupled to the power supply driving units 121 and 122 and can be used to control the power supply driving units 121 and 122 to send driving signals D1 and D2. The clock generator 112 may be a pulse width modulation generator (PWM generator) or other types of clock generators, and is used to output a clock signal to the power supply driving units 121 and 122. The processor 111 can receive information about the coil signal C1 on the power supply coil 16 (that is, the voltage signal between the power supply coil 16 and the resonance capacitor 142), such as the resonance frequency or attenuation range of the coil signal C1, and discriminate metal foreign objects based thereon. does it exist. The processor 111 may be a central processing unit (CPU), a microprocessor, a micro controller unit (MCU), or other types of processing devices or computing devices. The signal receiving module 120 can be used to track the resonance frequency and the peak value of the coil signal C1, and provide the information about the resonance frequency and the peak value to the processor 111 for subsequent interpretation. The voltage dividing circuit 130 includes voltage dividing resistors 131 and 132, which can attenuate the coil signal C1 on the power supply coil 16 and output it to the processor 111 and the signal receiving module 120. In some embodiments, if the circuits such as the processor 111 and the signal receiving module 120 have sufficient withstand voltage, the processor 111 may directly receive the coil signal C1 on the power supply coil 16 without using the voltage dividing circuit 130. As for other possible constituent elements or modules, such as a power supply unit, a display unit, etc., they may be increased or decreased according to the system requirements, so they are not shown without affecting the description of this embodiment.

In an embodiment, the signal receiving module 120 includes a voltage generating device 113 and a ratio Comparator 114 is shown in FIG. 1. The voltage generating device 113 can be a digital to analog converter (DAC), which can receive a reference voltage information from the processor 111, convert it to an analog voltage and output it. One input of the comparator 114 can receive the reference voltage, and the other input can receive the coil signal C1 from the power supply coil 16. It can compare the coil signal C1 with the reference voltage, and the processor 111 performs subsequent judgments based on the results of the above comparison. And signal processing. It should be noted that the signal receiving module 120 may also be integrated in the processor 111, but is not limited thereto.

Please continue to refer to Figure 1. The power receiving module 2 includes a load unit 21, a capacitor 22, a rectifier circuit 230, a power receiving coil 26, and resonance capacitors 241, 242. In the power receiving module 2, a magnetic conductor 261 made of a magnetic material can also be selectively used to improve the electromagnetic induction capability of the power receiving coil 26, and at the same time to prevent electromagnetic energy from affecting objects in the direction of the non-inductive surface of the coil. The power receiving coil 26 can be used to receive power from the power supply coil 16 and transmit the received power to the rectifier circuit 230 for rectification. After the rectification is completed, the power is transmitted to the back-end capacitor 22 and the load unit 21. The capacitor 22 may be a filtering capacitor for filtering or a voltage stabilizing capacitor for stabilizing the output voltage, and should not be limited thereto. In the power receiving module 2, other possible constituent elements or modules, such as a signal feedback circuit, a power receiving microprocessor, etc. may be increased or decreased according to the needs of the system. Therefore, it is not shown without affecting the description of this embodiment. .

In addition, a metallic foreign object 3 is not included in the inductive power supply 100, but is shown between the power supply module 1 and the power receiving module 2 in FIG. 1 for convenience of description. When the metal foreign object 3 is within the power transmission range of the inductive power supply 100, it may receive electromagnetic energy sent by the power supply module 1 and generate heat. The metal foreign object detection method of the present invention can be used to determine whether a metal foreign object 3 exists within the power transmission range of the inductive power supply 100, and stop power transmission when it is determined that the metal foreign object 3 exists.

Different from the conventional technology, the power supply module judges the gold by measuring the change in the attenuation slope of the coil. It is a foreign object. The present invention determines the metal foreign object by measuring the voltage attenuation ratio of the coil signal. Please refer to FIG. 2, which is a schematic diagram of a metal foreign object detection process 20 according to an embodiment of the present invention. As shown in FIG. 2, the metal foreign object detection process 20 can be used for the power supply end of an inductive power supply (such as the power supply module 1 of the inductive power supply 100 in FIG. 1), which includes the following steps: step 200: Start.

Step 202: Interrupt the driving signals D1 and D2 of the inductive power supply 100 during a measurement period to stop driving the power supply coil 16 to generate a coil signal C1 of the power supply coil 16.

Step 204: Measure two peaks of the coil signal C1 during two consecutive oscillation cycles of the coil signal C1 to obtain two peak trigger voltages respectively.

Step 206: Calculate an attenuation parameter based on the two peak trigger voltages.

Step 208: Compare the attenuation parameter with a corresponding critical value, and determine whether the attenuation parameter is greater than the critical value. If yes, go to step 216; if no, go to step 210.

Step 210: Determine whether the measured number of oscillation cycles reaches a predetermined number. If yes, go to step 216; if no, go to step 212.

Step 212: Measure the peak of the coil signal C1 within an oscillation period below the coil signal C1 to obtain a peak trigger voltage.

Step 214: Calculate an attenuation parameter according to the peak trigger voltage and the peak trigger voltage obtained in the previous oscillation period.

Step 216: The obtained attenuation parameters are averaged to generate an average result, and the average result is compared with a basic threshold value to determine whether the average result is greater than the basic threshold value. If yes, go to step 218; if no, go to step 220.

Step 218: It is determined that there is no metal foreign object 3 in the power transmission range of the inductive power supply 100.

Step 220: Determine whether there is metal in the power transmission range of the inductive power supply 100 Foreign body 3.

Step 222: End.

According to the metal foreign object detection process 20, in the power supply module 1 of the inductive power supply 100, the driving signals D1 and D2 are interrupted for a period of time during the driving process. At this time, the power supply driving units 121 and 122 will stop the power supply coil 16 Drive. When the power supply coil 16 stops driving, because there is still energy between the power supply coil 16 and the resonance capacitors 141 and 142, the coil signal C1 will continue to oscillate and gradually decay. As shown in Figure 3, when the drive is stopped, the drive signals D1 and D2 stay at the high and low potentials for a period of time, respectively. At this time, the coil signal C1 presents a waveform that oscillates and gradually decays, and then the power supply drive units 121 and 122 re-engage To output square wave driving signals D1 and D2 and drive the power supply coil 16 again to output power. In other embodiments, the driving signals D1 and D2 can also be controlled to stay at a high potential at the same time or stay at a low potential at the same time to stop driving, but not limited to this. The period during which the driving signals D1 and D2 are interrupted is used to measure the resonance of the coil signal C1 to detect the metal foreign object 3, which is hereinafter referred to as a measurement period for convenience of description.

During the measurement period, there are multiple consecutive oscillation cycles on the coil signal C1. The processor 111 can measure the peaks of the coil signal C1 in multiple oscillation cycles to obtain multiple peak trigger voltages, respectively. Please refer to FIG. 4, which is a schematic diagram of obtaining peak trigger voltages VB and VC during a measurement period according to an embodiment of the present invention. As shown in Figure 4, the coil signal C1 includes three peaks A, B, and C during the measurement period. Because the first peak A occurs at the time when the driving signals D1 and D2 have just stopped driving, the signal oscillation of the peak A may still be affected by the driving signals D1 and D2 instead of the natural oscillation of the power supply coil 16 itself. Therefore, the peak of the peak A The altitude may not have reached the height of the natural oscillation. In this case, in order to avoid that the judgment of the metal foreign body 3 is distorted by the driving signals D1 and D2, the peak trigger voltage measurement of the peak A can be discarded, and only the peak trigger voltages VB and VC of the peaks B and C can be measured.

During the oscillation period of the wave to be measured, the processor 111 may set a reference voltage (shown in dotted line in Figure 4), and output the reference voltage to the comparator 114 through the voltage generating device 113, and the comparator 114 compares the reference voltage A comparison result CP1 is generated with the coil signal C1. In detail, before entering the oscillation period corresponding to the peak B, the processor 111 may first set the reference voltage to a trigger starting potential V0_B. Then, when the level of the coil signal C1 rises above the reference voltage, a trigger signal appears on the output end of the comparator 114 (that is, the comparison result CP1 appears high), and the processor 111 can control the reference voltage to gradually rise. When the reference voltage rises above the level of the coil signal C1, it can be judged that the trigger signal ends (that is, the comparison result CP1 returns to a low level). At this time, the processor 111 can obtain the level of the reference voltage as the peak corresponding to the peak B Trigger voltage VB. Similarly, in the oscillation period corresponding to the peak C, the processor 111 may first set the reference voltage to a trigger starting potential V0_C, and then obtain the peak trigger voltage VC corresponding to the peak C in the same manner.

Then, the processor 111 may calculate a first attenuation parameter PAR1 according to the peak trigger voltage VB and the peak trigger voltage VC. In detail, the first attenuation parameter PAR1 may be a ratio of an average value of the peak trigger voltage VB and the peak trigger voltage VC to a difference between the peak trigger voltage VB and the peak trigger voltage VC. In one embodiment, the result of adding the peak trigger voltage VB and the peak trigger voltage VC divided by the result of subtracting the peak trigger voltage VB and the peak trigger voltage VC to obtain the first attenuation parameter PAR1, the detailed calculation method is as follows:

It is worth noting that the patent case TW I577108 of the Republic of China is based on the change of the attenuation slope to judge the metal foreign body, that is, the change of the attenuation. However, in the absence of metallic foreign matter, when the output power is high (that is, the coil signal C1 has a larger amplitude), the attenuation after the coil is interrupted is greater; when the output power is lower (that is, the coil signal C1 has a smaller amplitude ), The attenuation after the coil is interrupted is small. That is, the ratio of the attenuation to the output power will be approximately the same. For example, in the case of no metal foreign matter, if the peak trigger voltage VB is 100 unit voltage, the peak trigger voltage VC is about 90 unit voltage; if the peak trigger voltage VB is 50 unit voltage, the peak trigger voltage VC is about It is 45 units of voltage, and they have different peak attenuation. Therefore, in the present invention, the average value or the ratio of the peak trigger voltage to the difference (ie, the attenuation amount) of the peak trigger voltage is used to calculate the attenuation parameter, which can eliminate the influence of different output power on the coil signal attenuation, thereby achieving a more effective Judge foreign metal. In this example, the larger the attenuation parameter, the slower the signal attenuation speed, that is, the lower the possibility of the presence of metal foreign bodies; the smaller the attenuation parameter, the faster the signal attenuation speed, that is, the higher the possibility of the existence of metal foreign bodies.

It should also be noted that the above-mentioned peak trigger voltage is often not equal to the peak voltage of the corresponding peak. In fact, the peak trigger voltage is slightly lower than the peak voltage of the corresponding peak. It can be seen from FIG. 4 that the peak trigger voltage VB is close to and slightly lower than the peak voltage of the peak B, and the peak trigger voltage VC is close to and slightly lower than the peak voltage of the peak C. Since the trigger starting potentials V0_B and V0_C can be set to slightly lower than the voltage levels of peak B and peak C, respectively, the rising reference voltage and the coil signal C1 cross on the right side of the peak, so that the trigger based on the peak value obtained by the reference voltage The voltages VB and VC are also slightly lower and close to their corresponding peak voltages. In addition, according to the calculation method of the above attenuation parameter, it can be known that the size of the attenuation parameter is mainly affected by the attenuation ratio. Therefore, using the peak trigger voltage whose value is slightly lower than the peak voltage as the calculation basis, the obtained judgment result of the metal foreign body is still substantially the same as Judgment results obtained based on the peak voltage. As long as the attenuation parameter can reflect the attenuation amount or attenuation ratio, it can be used to discriminate metal foreign objects.

As described above, the first attenuation parameter PAR1 is equal to the result of adding the peak trigger voltage VB and the peak trigger voltage VC divided by the result of subtracting the peak trigger voltage VB and the peak trigger voltage VC. After obtaining the first attenuation parameter PAR1, the processor 111 may set a first threshold value TH1, and compare the first attenuation parameter PAR1 and the first threshold value TH1 to determine whether the power transmission range of one of the inductive power supplies 100 is No metal foreign matter 3 is present. In an embodiment, when the first attenuation parameter PAR1 is larger than the first threshold TH1, it can be determined that there is no metal foreign matter 3 in the power transmission range of the inductive power supply 100; when the first attenuation parameter PAR1 is smaller than the first threshold At TH1, follow-up discrimination is further performed. In an inductive power supply system, there is often a lot of noise on the power supply or load side, which is likely to interfere with the analysis and detection of the coil signal. Therefore, in order to accurately discriminate metal foreign objects, it is necessary to continuously obtain data or results determined as metal foreign objects multiple times. Avoid misinterpretation of metal foreign objects caused by noise interference, so that the power output is turned off by mistake.

In one embodiment, the processor 111 may set a basic threshold value TH0. During the product testing process of the inductive power supply, the variability of attenuation parameters may exist in different products and different environments. The basic threshold value TH0 can be set according to the lowest attenuation parameter measured in the absence of metal foreign objects. Preferably, the basic threshold value TH0 can be set to a lower value, which has a looser discrimination criterion to avoid noise interference from being misjudged as the presence of metallic foreign objects. Then, the processor 111 may add different thresholds to the base threshold TH0, respectively, to obtain a plurality of thresholds, such as a first threshold TH1, a second threshold TH2, a third threshold TH3, and the like. The processor 111 may compare the first attenuation parameter PAR1, the second attenuation parameter PAR2, the third attenuation parameter PAR3, and the fourth attenuation parameter PAR4 obtained during a measurement period with the first threshold TH1, the second threshold TH2, and the third The threshold value TH3 and the basic threshold value TH0 are compared to determine the foreign metal 3. For example, the processor may set the basic threshold value TH0 to 150, and set the first threshold value TH1 to the basic threshold value TH0 = 150 plus 30, which is 180; and the second threshold value TH2 to the basic threshold value TH0 = 150. Add 20, which is 170; the third threshold TH3 is set to the basic threshold TH0 = 150 plus 10, which is 160. The first threshold value TH1 is larger than the second threshold value TH2, and the second threshold value TH2 is larger than the third threshold value TH3.

First, the processor 111 compares the first attenuation parameter PAR1 with a first threshold TH1. In an embodiment (as shown in Table 1), the processor 111 may obtain a peak trigger voltage VB of 1000 unit voltage and The peak trigger voltage VC is 990 unit voltages. After calculation, the first attenuation parameter PAR1 is 199. Since the first attenuation parameter PAR1 = 199 is larger than the first threshold TH1 = 180, which means that it is much larger than the basic threshold TH0, the processor 111 directly determines that the metal foreign object 3 does not exist.

In this example, the first attenuation parameter PAR1 is larger than the first critical value TH1 and much larger than the basic critical value TH0, which indicates that the probability of the presence of the metal foreign body 3 is extremely low and belongs to a very safe state, so the system directly determines that the metal foreign body 3 does not exist . In this case, the processor 111 only needs to measure two oscillation cycles to complete the determination of the metal foreign object 3. In other words, during the measurement period when the drive signals D1 and D2 are interrupted, only three oscillation periods are required. Among them, the oscillation period corresponding to the peak A is not measured, and the measurement is completed within the oscillation periods corresponding to the peaks B and C. After the attenuation parameter PAR1, the discrimination of the metal foreign body 3 can be completed.

In one embodiment, the first attenuation parameter PAR1 is smaller than the first threshold value TH1. At this time, the processor 111 further performs the subsequent determination of the metallic foreign object 3, as shown in Table 2.

In detail, the processor 111 first compares the first attenuation parameter PAR1 and the first threshold TH1. After determining that the first attenuation parameter PAR1 = 166 is smaller than the first critical value TH1 = 180, the processor 111 can measure the next oscillation period (corresponding to the oscillation period of the peak D) of the coil signal C1. As shown in FIG. 5, during the oscillation period of the peak D, the processor 111 may first set the reference voltage to a trigger starting potential V0_D, and obtain the peak trigger voltage VD corresponding to the peak D in the above manner. Then, the processor 111 may calculate a second attenuation parameter PAR2 according to the peak trigger voltage VC and the peak trigger voltage VD. In detail, the processor 111 may calculate the result of adding the peak trigger voltage VC and the peak trigger voltage VD and dividing it by the result of subtracting the peak trigger voltage VC and the peak trigger voltage VD to obtain the second attenuation parameter PAR2. The detailed calculation method is as follows: :

In this example, the peak trigger voltage VC is 988 unit voltage and the peak trigger voltage VD is 977 unit voltage. After calculation, the second attenuation parameter PAR2 is 179 (rounded to the decimal point). Next, the processor 111 compares the second attenuation parameter PAR2 and the second threshold TH2, and determines that the second attenuation parameter PAR2 = 179 is greater than the second threshold TH2 = 170. In this case, the processor 111 stops measuring the subsequent oscillation period during this measurement period, and averages the obtained first attenuation parameter PAR1 and the second attenuation parameter PAR2, and compares the above average result with the basic threshold TH0. To determine the metal foreign object 3. In this example, the average value of the first attenuation parameter PAR1 and the second attenuation parameter PAR2 is greater than the basic threshold value TH0. Therefore, the processor 111 determines that there is no metal foreign object 3 in the power transmission range of the inductive power supply 100.

In another embodiment, the second attenuation parameter PAR2 may also be smaller than the second critical value TH2. At this time, the processor 111 further performs the subsequent determination of the metallic foreign object 3, as shown in Table 3.

In detail, the processor 111 first compares the first attenuation parameter PAR1 and the first threshold TH1. After determining that the first attenuation parameter PAR1 = 142 is smaller than the first critical value TH1 = 180, the processor 111 may measure the next oscillation period (corresponding to the oscillation period of the peak D) of the coil signal C1 to obtain the second attenuation parameter PAR2, Compare the second attenuation parameter PAR2 with the second threshold TH2. Then, after determining that the second attenuation parameter PAR2 = 163 is smaller than the second critical value TH2 = 170, the processor 111 can measure the next oscillation period (corresponding to the oscillation period of the wave peak E) of the coil signal C1. As shown in FIG. 6, during the oscillation period of the peak E, the processor 111 may first set the reference voltage to a trigger starting potential V0_E, and obtain the peak trigger voltage VE corresponding to the peak E in the above manner. Then, the processor 111 may calculate a third attenuation parameter PAR3 according to the peak trigger voltage VD and the peak trigger voltage VE. In detail, the processor 111 may calculate the result of adding the peak trigger voltage VD and the peak trigger voltage VE and divide it by the result of subtracting the peak trigger voltage VD and the peak trigger voltage VE to obtain a third attenuation parameter PAR3. The detailed calculation method is as follows: :

In this example, the peak trigger voltage VD is 974 unit voltage and the peak trigger voltage VE is 962 unit voltage. After calculation, the third attenuation parameter PAR3 is 161 (rounded up to the decimal point). Next, the processor 111 compares the third attenuation parameter PAR3 and the third threshold TH3, and determines that the third attenuation parameter PAR3 = 161 is greater than the third threshold TH2 = 160. In this case, the processor 111 during this measurement period Stop measuring subsequent oscillation cycles, meanwhile average the obtained first attenuation parameter PAR1, second attenuation parameter PAR2, and third attenuation parameter PAR3, and compare the above average result with the basic threshold TH0 to perform the measurement of the metal foreign body 3. Judge. In this example, the average value of the first attenuation parameter PAR1, the second attenuation parameter PAR2, and the third attenuation parameter PAR3 is greater than the basic threshold TH0. Therefore, the processor 111 determines that no metal exists in the power transmission range of the inductive power supply 100. Foreign body 3.

In another embodiment, the third attenuation parameter PAR3 may also be smaller than the third critical value TH3. At this time, the processor 111 further performs the subsequent determination of the metal foreign object 3, as shown in Table 4.

In detail, the processor 111 first compares the first attenuation parameter PAR1 and the first threshold TH1. After determining that the first attenuation parameter PAR1 = 124 is smaller than the first critical value TH1 = 180, the processor 111 may measure the next oscillation period (corresponding to the oscillation period of the peak D) of the coil signal C1 to obtain the second attenuation parameter PAR2, and Compare the second attenuation parameter PAR2 with the second threshold TH2. Then, after determining that the second attenuation parameter PAR2 = 122 is smaller than the second critical value TH2 = 170, the processor 111 may measure an oscillation period (corresponding to the oscillation period of the wave peak E) under the coil signal C1 to obtain a third attenuation parameter PAR3. And compare the third attenuation parameter PAR3 with the third critical value TH3. Then, after determining that the third attenuation parameter PAR3 = 120 is smaller than the third critical value TH3 = 160, the processor 111 can measure the next oscillation period (corresponding to the oscillation period of the wave peak F) of the coil signal C1. As shown in FIG. 7, during the oscillation period of the peak F, the processor 111 may first set the reference voltage to a trigger starting potential V0_F, and obtain the peak trigger voltage VF corresponding to the peak F in the above manner. Then, the processor 111 may calculate a fourth attenuation parameter PAR4 according to the peak trigger voltage VE and the peak trigger voltage VF. In detail, the processor 111 can calculate the result of adding the peak trigger voltage VE and the peak trigger voltage VF and dividing it by the result of subtracting the peak trigger voltage VE and the peak trigger voltage VF to obtain a fourth attenuation parameter PAR4. The detailed calculation method is as follows: :

In this example, the peak trigger voltage VE is 952 unit voltage and the peak trigger voltage VF is 936 unit voltage. After calculation, the fourth attenuation parameter PAR4 is 118. Since the number of oscillation cycles measured by the processor 111 during this measurement period has reached a predetermined number, the processor 111 may perform the first attenuation parameter PAR1, the second attenuation parameter PAR2, the third attenuation parameter PAR3, and the fourth attenuation. The parameter PAR4 is averaged, and the above averaged result is compared with the basic threshold value TH0 to determine the metal foreign object 3. In this example, the average value of the first attenuation parameter PAR1, the second attenuation parameter PAR2, the third attenuation parameter PAR3, and the fourth attenuation parameter PAR4 is less than the basic threshold value TH0, so the processor 111 determines the power of the inductive power supply 100. There is a metal foreign object 3 in the transmission range.

In the above embodiment, the measurement period of the interruption of the driving signals D1 and D2 need only include 3 to 6 oscillating periods, and the determination of the metal foreign object 3 can be completed. Compared with the patent case of the Republic of China TWI577108, it takes 7 to 15 different coil oscillation cycles to complete the measurement of the four peak voltage levels to determine the change in attenuation slope. The method for detecting metal foreign objects in the present invention can be performed in less time. Completed, thereby shortening the interruption time of the driving signals D1 and D2. Generally speaking, when the metal foreign body 3 does not exist and the coil signal C1 is judged not to be disturbed by noise, the first attenuation parameter PAR1 obtained is often much larger than the basic threshold TH0. At this time, only two oscillation periods need to be measured. The determination of the metal foreign object 3 can be completed, and after the determination is completed, the power supply driving units 121 and 122 can immediately join the lines to start the driving signals D1 and D2, as shown in FIG. 3. On the other hand, measurement is only needed when the metal is approaching or noise interferes with the attenuation parameter. More oscillation cycles. In other words, the smaller the value of the attenuation parameter, the higher the possibility of the presence of metallic foreign objects, and the number of oscillation cycles measured at this time also increases simultaneously. In the end, no matter how many oscillation periods are measured or how many attenuation parameters are obtained, the processor 111 averages the obtained attenuation parameters, and compares the average result with the basic threshold value TH0 to determine whether the metal foreign body 3 exists. In general, when the coil stops driving, its signal is in a state of natural resonance. If no metal foreign matter is present, the amount of change in the attenuation slope of the coil signal relative to the value of the signal amplitude is extremely small. Since each attenuation parameter is calculated based on the peak trigger voltage of adjacent oscillation cycles and calculated in the same way, the value of the attenuation parameter is quite stable. In an inductive power supply system, the judgment of the signal is necessarily affected by power or circuit noise, but most of the power / circuit noise is reflected in the attenuation parameter with only small amplitude fluctuations. At this time, the attenuation parameter is often much larger than the foregoing. Critical value without affecting the discrimination result. Conversely, when a metal foreign object occurs, the peak trigger voltage will rapidly decay. By calculating the addition result divided by the subtraction result, the attenuation parameter will decrease rapidly, which can effectively detect and discriminate metal foreign objects.

In each measurement period, the number of oscillation cycles to be measured can be determined according to the comparison result between the attenuation parameter and the corresponding critical value, and the average value of all attenuation parameters can be obtained to discriminate metal foreign objects. Generally, when any one of the first, second, and third attenuation parameters PAR1 to PAR3 is greater than the corresponding critical value, the calculation of the last fourth attenuation parameter PAR4 is not performed. Because the first, second, and third thresholds TH1 ~ TH3 are all larger than the basic threshold TH0, the average of the first three attenuation parameters PAR1 ~ PAR3 is usually larger than the basic threshold without calculating the fourth attenuation parameter PAR4. The value TH0 determines the result of the absence of the metallic foreign object 3. In this case, the processor 111 may also determine the number of attenuation parameters obtained or the number of measured oscillation cycles. Only when the number of obtained attenuation parameters reaches a preset value (for example, four attenuation parameters), the attenuation parameter is calculated. The average value is used to determine the metal foreign body 3; if the number of attenuation parameters obtained does not reach the preset value, the processor 111 directly determines that the metal foreign body 3 does not exist.

In addition, in order to improve the discrimination accuracy and prevent the power output from being turned off due to incorrect discrimination, the processor 111 may set a metal foreign object counter. If the average value of the attenuation parameter obtained during a measurement period is less than the basic threshold value, the metal foreign matter counter can be increased by one. When the metal foreign object counter reaches a specific value within a predetermined period, it is determined that the metal foreign object 3 exists. Alternatively, it can also be determined that the presence of the metal foreign object 3 is obtained when the average value of the attenuation parameter is less than the basic critical value within several consecutive measurement periods.

It is worth noting that in the above embodiment, the processor 111 first sets a reference voltage to a trigger starting potential, and controls the reference voltage to rise when a trigger occurs at the output terminal of the comparator 114, and then obtains a reference at the end of the trigger. The voltage level is used as the peak trigger voltage. In order for the peak trigger voltage to effectively reflect the voltage level of the corresponding peak, the trigger starting potential should be set to a position close to and slightly below the peak voltage, in order to successfully trigger and make the peak trigger voltage close to the peak voltage level. If the trigger start potential is set too high, it may happen that the trigger start potential is higher than the peak voltage and the trigger cannot be successfully triggered; if the trigger start potential is set too low, although the trigger can be successfully triggered, the peak trigger voltage may be too low to be able to trigger Reflects the true peak voltage.

In an embodiment, the processor 111 may calculate a trigger starting potential used in the current measurement according to a corresponding previous peak trigger voltage obtained in the previous measurement period, for example, subtracting a preset peak trigger voltage from a preset value. The value obtained from the voltage value is set as the trigger starting potential. For example, for the oscillation period of the peak B, if the peak trigger voltage VB obtained in the previous measurement period is 1000 unit voltage, the trigger starting potential V0_B during the current measurement period can be set to 900 unit voltage (ie 1000 minus For the oscillation period of the peak C, if the peak trigger voltage VC obtained in the previous measurement period is 980 unit voltage, the trigger starting potential V0_C during this measurement period can be set to 880 unit voltage (that is, 980 minus the preset voltage value 100). Based on the peak trigger voltage during the previous measurement period, the processor 111 can know the possible level of the peak voltage to set the trigger starting potential to a slightly lower level. Set lower level The trigger starting potential can increase the probability of triggering. Unless the peak voltage drops rapidly, in most cases, the trigger can be successfully generated and the judgment result of the metal foreign body can be obtained.

The method of judging the peak voltage level of the Taiwanese patent case TW I577108 is to determine whether the reference voltage needs to be raised or lowered according to the result of the trigger in the previous measurement period, and it is triggered from time to time without triggering in several measurement periods Under the circumstances, it is judged that the reference voltage is locked at the peak voltage level. Therefore, when the load and output power do not change, multiple reference periods are required to lock the reference voltage to the peak voltage level. In contrast, according to the method for obtaining the peak trigger voltage according to the present invention, setting the trigger starting potential to a lower potential can increase the probability of triggering. As long as the trigger occurs, the attenuation parameter can be calculated immediately to discriminate metal foreign objects. Therefore, The invention can quickly complete the determination without spending multiple measurement periods to lock to the peak voltage level. In addition, the triggering start potential can still be adjusted to a better level during the discrimination process. For example, during the measurement period, the triggering start potential V0_B is set to 900 unit voltage and the trigger ends when the reference voltage rises to 910 unit voltage. The peak drop reduces the peak trigger voltage VB to 910 unit voltage. In this case, the trigger starting potential V0_B can be set to 810 unit voltage (that is, 910 minus the preset voltage value 100) in the next measurement period to achieve a better The triggering effect also increases the chance of successful triggering.

It is worth noting that, in some cases, the processor 111 cannot obtain the peak trigger voltage corresponding to the previous measurement period. For example, during the previous measurement period, the processor 111 calculates the first attenuation parameter PAR1 according to the peak trigger voltage VB and the peak trigger voltage VC, and judges that the first attenuation parameter PAR1 is greater than the first threshold TH1, so there is no need to measure subsequent Oscillation period and calculation of other attenuation parameters. However, during this measurement period, the processor 111 determines that the first attenuation parameter PAR1 is smaller than the first critical value TH1 and needs to measure a subsequent oscillation period. In other words, the trigger starting potential V0_D corresponding to the peak D needs to be obtained during this measurement period, but the oscillation period of the peak D was not measured in the previous measurement period, so there is no peak contact The voltage VD is used as the basis for estimating the current starting potential V0_D. In this case, the processor 111 may use another previous peak trigger voltage (that is, the peak trigger voltage VC corresponding to the peak C) as the basis for the previous oscillation cycle in this measurement period, and estimate the peak corresponding to the peak D The trigger voltage VD may be lower than the amplitude of the peak trigger voltage VC, and then the trigger starting potential V0_D is calculated. For example, if the peak trigger voltage VC is 900 unit voltage, the peak trigger voltage VD of the peak D can be estimated as 870 unit voltage, and the trigger starting potential V0_D is set to 770 unit voltage (that is, 870 minus the preset Voltage value 100). In another embodiment, the peak trigger voltage VD of the peak D can also be estimated according to the peak trigger voltage VB and VC during the same measurement period. For example, if the peak trigger voltage VB is 100 unit voltage and the peak trigger voltage VC is 90 unit voltage, the peak trigger voltage VD of the peak D can be estimated to be about 80 unit voltage, and the trigger starting potential V0_D can be set to 70. Unit voltage to detect the actual peak trigger voltage VD.

Generally, if the oscillation period corresponding to the peak D is not measured in the previous measurement period, the record representing the previous peak trigger voltage corresponding to the peak D may come from the measurement result before a long time. However, during the power supply process of the inductive power supply 100, changes in load and / or power output may occur, causing the peak voltage on the coil signal C1 to vary greatly. This change may be as many as tens or hundreds of times. In this case, the record of the peak trigger voltage before a long time often has no reference value. Therefore, using the peak trigger voltage of the previous oscillation period in the same measurement period as the basis can obtain a more suitable trigger starting potential, and then increase The probability of successfully triggering and obtaining the attenuation parameter and the judgment result of the metal foreign body.

It is worth noting that the aforementioned methods cannot successfully trigger and obtain attenuation parameters during each measurement period. If no trigger occurs in one of the oscillation cycles and the corresponding peak trigger voltage cannot be obtained, the processor 111 discards the calculation and judgment results during the measurement period, and at the same time lowers the trigger starting potential to increase the successful trigger in the next measurement period Chance. In addition, in order to effectively obtain the peak trigger voltage, The processor 111 may first measure the resonance frequency of the coil, and obtain a position interval where a wave peak may occur in each resonance period. If no trigger occurs in this interval, it means that the trigger starting potential is too high, so the processor 111 reduces the trigger starting potential during the next measurement period and tries to trigger again to obtain the corresponding peak trigger voltage.

It can be known from the above that the present invention can measure the coil signal to obtain the peak trigger voltage corresponding to a plurality of peaks during the measurement period when the driving signal is interrupted, and according to the ratio of the average value of the two adjacent peak trigger voltages to the difference thereof Calculate the attenuation parameter, and then compare the attenuation parameter with the corresponding threshold value to determine whether it is necessary to obtain the peak trigger voltage of more crests to perform subsequent judgments, and at the same time to discriminate metal foreign objects. The processor can set the reference voltage at a trigger starting potential, and control the reference voltage to gradually rise when a trigger occurs, thereby obtaining a peak trigger voltage. Those skilled in the art can make modifications or changes based on this, without being limited thereto. For example, in the above embodiment, a maximum of 5 oscillation periods are measured in a measurement period to obtain 5 peak trigger voltages to calculate 4 attenuation parameters. In other embodiments, the maximum number of measurement oscillation periods and the maximum number of attenuation parameters obtained can be adjusted according to system requirements, and are not limited thereto. In addition, in the above embodiments, the values of the peak trigger voltage and the trigger starting potential are just examples. Those skilled in the art can set and obtain appropriate voltage values according to system requirements. For example, the voltage generating device 113 may be implemented by a digital analog converter, and the above unit voltage may be a digital value set by the processor 111, which is converted into a corresponding analog voltage by the digital analog converter and then output. For digital analog converters of different specifications, the peak trigger voltage and trigger start potential may have different values. For example, if the voltage generating device 113 is a 12-bit digital analog converter, it can receive a digital value from 0 to 4095 and generate an output voltage corresponding to the possible voltage range of the coil signal C1 (after passing through the voltage dividing circuit 130). . In addition, the peak trigger voltage refers to the reference voltage rising from the trigger starting potential to the level at the end of the trigger, and the processor 111 can adjust the speed of the reference voltage rising. For example, the processor 111 can control the reference voltage to rise at a fixed speed, and Will rise The degree is adjusted to a better value so that the level at the end of the trigger can effectively reflect the level of the peak voltage.

The method for detecting metal foreign objects in the present invention can effectively reduce the interruption time of the driving signal, so as to reduce the influence of interrupted driving on the power supply. Therefore, the process of judging metal foreign objects must be completed in the shortest time possible. In the above-mentioned embodiment, it is only required to measure at least two oscillation cycles to complete the determination of the metal foreign body. Together with the discarded oscillation period of the first wave, the driving signal only needs to be interrupted for a minimum of three oscillation cycles. In another embodiment, the driving signal interruption time can be further reduced.

Please refer to FIG. 8, which is a schematic diagram of another metal foreign object detection process 80 according to an embodiment of the present invention. As shown in FIG. 8, the metal foreign object detection process 80 can be used for the power supply end of an inductive power supply (such as the power supply module 1 of the inductive power supply 100 in FIG. 1), which includes the following steps: Step 800: Start.

Step 802: Obtain a corresponding one of the previous peak trigger voltages measured in the previous measurement period, and set it as a reference voltage value.

Step 804: Interrupt the driving signals D1 and D2 of the inductive power supply 100 to stop driving the power supply coil 16 during a measurement period, so as to generate a coil signal C1 of the power supply coil 16.

Step 806: Measure a first peak of the coil signal C1 during an oscillation period of the coil signal C1 to obtain a first peak trigger voltage.

Step 808: Compare the first peak trigger voltage with the reference voltage value, and determine whether the first peak trigger voltage is equal to or close to the reference voltage value. If yes, go to step 810; if no, go to step 812.

Step 810: It is determined that there is no metal foreign object 3 in the power transmission range of one of the inductive power supplies 100, and then step 818 is performed.

Step 812: Measure one of the coil signals C1 in an oscillation period below the coil signal C1. A second peak to obtain a second peak trigger voltage.

Step 814: Calculate an attenuation parameter according to the first peak trigger voltage and the second peak trigger voltage.

Step 816: Compare the attenuation parameter with a critical value to determine whether there is a metal foreign object 3 in the power transmission range of the inductive power supply 100.

Step 818: End.

The difference between the metal foreign object detection process 80 and the metal foreign object detection process 20 is that in the metal foreign object detection process 80, the processor 111 needs to measure at least one peak of the coil signal C1 during the measurement period when the driving signals D1 and D2 are interrupted and obtain a The peak trigger voltage can complete the discrimination of the metal foreign body 3.

For example, please refer to FIG. 9, which is a schematic diagram of discriminating a metal foreign object through a peak trigger voltage VB during a measurement period according to an embodiment of the present invention. As shown in Figure 9, the coil signal C1 contains only two peaks A and B during the measurement period. Similarly, in order to avoid the judgment of the metal foreign object 3 being distorted by the driving signals D1 and D2, the peak trigger voltage measurement of the peak A can be discarded. Then, in the oscillation period corresponding to the peak B, the processor 111 may set the reference voltage at a trigger starting potential V0_B, and obtain the peak trigger voltage VB corresponding to the peak B in the manner described above.

It is worth noting that in the previous measurement period, the processor 111 may first measure a corresponding one of the previous peak trigger voltages, that is, the peak trigger voltage VB corresponding to the peak B in the previous measurement period, and record the peak trigger voltage VB As a reference voltage value, for example, the processor 111 may store the reference voltage value in a memory. At the same time, only the peak trigger voltage VB was obtained during the previous measurement period and the judgment result indicated that no metallic foreign matter 3 was present; or, only the peak trigger voltage VB and VC were obtained during the previous measurement period. The calculated first attenuation parameter PAR1 is greater than the first A threshold value TH1 is used to indicate that no metallic foreign matter 3 is present. Then, in this During the second measurement, the processor 111 only needs to obtain the peak trigger voltage VB corresponding to the peak B, and then the metal foreign object 3 can be determined. In detail, the processor 111 can compare the peak trigger voltage VB with a reference voltage value. When the peak trigger voltage VB is equal to or close to the reference voltage value, it can be determined that there is no metal foreign object in the power transmission range of the inductive power supply 100. 3. In this case, after the measurement of the peak trigger voltage VB is completed, the power supply driving units 121 and 122 can be re-engaged to drive the power supply coil 16 to output power again through the driving signals D1 and D2.

In general, when the metal foreign matter does not exist and the coil output power and load state are unchanged, the peak trigger voltage VB corresponding to the peak B is also substantially unchanged. Conversely, when a metal foreign object 3 enters the power transmission range of the inductive power supply 100, if other conditions (such as coil output power and load) remain unchanged, the peak trigger voltage VB will be greatly affected by the metal foreign object 3. In this case, the processor 111 only needs to measure the peak trigger voltage VB to complete the determination of the metal foreign object 3. In this way, during the measurement period when the driving signals D1 and D2 are interrupted, it is only necessary to include at least 2 oscillation periods. Among them, the oscillation period corresponding to the peak A is not measured, and the measurement is completed and obtained within the oscillation period corresponding to the peak B. After the peak trigger voltage VB, the discrimination of the metal foreign object 3 can be completed by comparing the peak trigger voltage VB with a previously obtained reference voltage value.

In one embodiment, when the peak trigger voltage VB is determined to be equal to or close to the reference voltage value, it means that there is no metal foreign matter in the power transmission range of the inductive power supply 100. At this time, the processor 111 can update the stored reference voltage value and set it as the current peak trigger voltage VB for determination in the next measurement period.

It should be noted that the above-mentioned determinations that are equal to or close to can be made in any manner. For example, if the peak trigger voltage VB is within the next specific value range above the reference voltage value, it can be judged as both. Equal or close, for example, the reference voltage value can be set to be close to the reference voltage value within a range of 50 unit voltages up and down, and the reference voltage value obtained in the previous measurement period is 1000 unit voltages. In this case, if the peak trigger voltage VB is within a range of 950 to 1050 unit voltages, the processor 111 can determine that the peak trigger voltage VB is equal to or close to the reference voltage value, and further determine that the metal foreign object 3 does not exist. In another embodiment, the value range within the next specific ratio of the reference voltage value can be set to be equal to or close to, for example, the reference voltage value can be set to be regarded as being close to the reference voltage within a range of five percent each up and down. Value, and the reference voltage value obtained in the previous measurement period is 500 unit voltages. In this case, if the peak trigger voltage VB is within a range of 475 to 525 unit voltages, the processor 111 can determine that the peak trigger voltage VB is equal to or close to the reference voltage value, and further determine that the metal foreign object 3 does not exist.

In addition, if the peak trigger voltage VB is judged to be not equal to or close to the reference voltage value during this measurement period, it means that there may be metal foreign matter 3 or the output power and / or load of the system may change. At this time, the processor 111 needs to further measure the next oscillation period of the coil signal C1 and obtain a corresponding peak trigger voltage. Next, the processor 111 calculates an attenuation parameter according to the peak trigger voltage measured in two adjacent oscillation periods, and compares the attenuation parameter with a corresponding threshold value to determine the metal foreign object 3. In other words, in the metal foreign object detection process 80, if a first peak trigger voltage (such as VB) is determined to be not equal to or close to the reference voltage value, it is necessary to continue to measure the next oscillation cycle to obtain a second peak trigger voltage ( (For example, VC in FIG. 4), to further determine the metal foreign object 3, the above discrimination can be realized by the metal foreign object detection method 20 shown in FIG. 2 described above.

It is worth noting that, under certain circumstances, a situation may occur where the metal foreign object 3 approaches and the peak trigger voltage VB is still equal to or close to the reference voltage value due to coil movement or load change. In order to prevent the metal foreign object 3 from being effectively discriminated in the above-mentioned situation, the processor 111 may set the peak trigger voltage VB to be determined to be equal to or close to a continuous number of reference voltage values or an upper limit of a continuous time, and reach When the upper limit is reached, the steps of measuring the next oscillation period to obtain a second peak trigger voltage (such as VC in FIG. 4) and calculating the attenuation parameters are performed, that is, through the aforementioned metal foreign object detection method 20 shown in FIG. 2 Discrimination of metallic foreign matter 3. In an embodiment, the processor 111 may include a counter for calculating that the peak trigger voltage VB is judged to be equal to or close to the reference voltage value and thus only measures the number of consecutive times of a peak trigger voltage VB. When the counter reaches the upper limit, it changes to The metal foreign object detection method 20 shown in FIG. 2 is executed. At this time, the processor 111 resets the counter to recalculate the continuous number of times. Alternatively, the processor 111 may include a timer for determining that the peak trigger voltage VB is determined to be equal to or close to the continuous time of the reference voltage value. When the counting period expires, a metal foreign object as shown in FIG. 2 is executed instead. The method 20 is detected. At this time, the processor 111 resets the timer to recalculate the continuous time. Or, the operation of the timer may not consider the determination result of the peak trigger voltage VB. For example, the timer operates periodically according to a fixed timing period. Usually, a metal foreign object detection method as shown in FIG. 8 can be used. When the counting period expires, the foreign metal detection method 20 shown in FIG. 2 is enforced.

In summary, the present invention provides a method for detecting metal foreign objects, which can measure the coil signal to obtain one or more peak trigger voltages during the measurement period when the drive signal is interrupted, and can compare the peak trigger voltage with one of the previously obtained references Voltage value to discriminate metal foreign objects, or calculate the attenuation parameter according to the ratio of the average value of the trigger voltage of two adjacent peaks to its difference, and then compare the attenuation parameter with the corresponding threshold value to determine whether more peaks need to be obtained The voltage is triggered to perform subsequent judgments to achieve the discrimination of metallic foreign objects. The processor may set the reference voltage to a trigger starting potential at a lower level, and control the reference voltage to gradually rise when a trigger occurs, thereby obtaining a peak trigger voltage. Setting the trigger starting potential to a lower level can increase the probability of successful triggering and obtaining a peak trigger voltage. In addition, when the metal foreign body does not exist, the metal foreign body detection method of the present invention only needs to measure one or two coil oscillation periods and obtain one or two peak trigger voltages correspondingly to complete the determination of the metal foreign body. Even if the first peak that is not measured is added, the measurement period of the drive signal interruption contains at least 2 ~ 3 lines The ring oscillation period can greatly reduce the impact of driving signal interruption on power output. In addition, the method for detecting a metal foreign object according to the present invention can be judged by the attenuation ratio of the coil signal, instead of using the attenuation method or the attenuation slope to judge in the past, and can solve the disadvantage of judging by the attenuation slope that is easily affected by the coil amplitude and load.

The above description is only a preferred embodiment of the present invention, and all equivalent changes and modifications made in accordance with the scope of patent application of the present invention shall fall within the scope of the present invention.

Claims (25)

A method for detecting a metal foreign object is used for a power supply module of an inductive power supply. The power supply module includes a power supply coil. The method for detecting a metal foreign object includes: interrupting the inductive power supply during a measurement period. At least one driving signal to stop driving the power supply coil to generate a coil signal of the power supply coil; measuring multiple peaks of the coil signal during successive oscillation cycles of the coil signal to obtain multiple peak triggers respectively Voltage; calculating a first attenuation parameter according to a first peak trigger voltage and a second peak trigger voltage of the plurality of peak trigger voltages corresponding to two adjacent peaks; and comparing the first attenuation parameter with a first threshold Value to determine whether a metal foreign object exists within the power transmission range of one of the inductive power supplies. The method for detecting a metal foreign object according to claim 1, wherein the step of calculating the first attenuation parameter according to the first peak trigger voltage and the second peak trigger voltage of the plurality of peak trigger voltages includes: according to the first A ratio of a peak trigger voltage and an average value of the second peak trigger voltage to a difference between the first peak trigger voltage and the second peak trigger voltage is used to calculate the first attenuation parameter. The method for detecting a metal foreign object according to claim 1, wherein the first attenuation parameter is equal to a result of adding the first peak trigger voltage and the second peak trigger voltage divided by the first peak trigger voltage and the second peak trigger The result of voltage subtraction. The method for detecting a metal foreign body according to claim 1, wherein the first peak trigger voltage is close to and lower than a corresponding one of the plurality of peaks, and the second peak trigger voltage is close to and lower than The peak voltage of the corresponding second peak among the plurality of peaks. The method for detecting a metal foreign object according to claim 1, wherein the steps of measuring the plurality of peaks of the coil signal within the continuous plurality of oscillation cycles of the coil signal to obtain the plurality of peak trigger voltages include: In one of the plurality of oscillation cycles, the following steps are performed: setting a reference voltage at a trigger starting potential; after a trigger signal appears, controlling the reference voltage to gradually rise; and obtaining the reference voltage at the end of the trigger signal The standard level is used as a peak trigger voltage of the plurality of peak trigger voltages. The method for detecting a metal foreign object according to claim 5, wherein the steps of measuring the plurality of wave peaks of the coil signal within the continuous plurality of oscillation cycles of the coil signal to obtain the plurality of peak trigger voltages respectively further include: Obtain a corresponding first previous peak trigger voltage obtained during the previous measurement period, and set a value obtained by subtracting a preset voltage value from the first previous peak trigger voltage as the trigger starting potential; or when the When the corresponding first previous peak trigger voltage is not obtained in the previous measurement period, the following steps are performed: obtaining a second previous peak trigger voltage in the previous oscillation period of the plurality of oscillation periods; according to the second previous The peak trigger voltage is used to calculate an estimated peak trigger voltage; and a value obtained by subtracting the preset voltage value from the estimated peak trigger voltage is set as the trigger starting potential. The method for detecting a metal foreign object according to claim 1, wherein the step of comparing the first attenuation parameter with the first threshold value to determine whether a metal foreign object exists in the power transmission range of the inductive power supply includes: when When the first attenuation parameter is greater than the first critical value, it is determined that there is no metal foreign object in the power transmission range of the inductive power supply; and when the first attenuation parameter is less than the first critical value, the following steps are additionally performed. : Obtaining a third peak trigger voltage of the plurality of peak trigger voltages; calculating a second attenuation parameter based on the second peak trigger voltage and the third peak trigger voltage; and comparing the second attenuation parameter with a second Critical value. The method for detecting a foreign metal substance according to claim 7, wherein the first threshold value is obtained by adding a predetermined basic threshold value to a first value, and the second threshold value is obtained by adding the first threshold value to a first threshold value. Derived from two values, wherein the second value is smaller than the first value. The method for detecting a metal foreign object according to claim 1, further comprising: calculating a plurality of attenuation parameters according to the plurality of peak trigger voltages; and averaging the plurality of attenuation parameters to determine the inductive power supply. Is there any foreign metal in the power transmission range? The method for detecting a metal foreign object according to claim 9, wherein the step of averaging the plurality of attenuation parameters to determine whether a metal foreign object exists in the power transmission range of the inductive power supply includes: obtaining the plurality of attenuations Averaging the parameters to produce an average result; comparing the average result with a basic threshold value; when the average result is greater than the basic threshold value, judging that there are no metal foreign objects in the power transmission range of the inductive power supply; and When the average result is less than the basic threshold, it is determined that there is a metal foreign object in the power transmission range of the inductive power supply. A power supply module for an inductive power supply is used to perform a metal foreign object detection method. The power supply module includes: a power supply coil; and a resonance capacitor coupled to the power supply coil for matching the power supply. The coil resonates; at least one power supply driving unit is coupled to the power supply coil and the resonance capacitor, and is used to send at least one driving signal to the power supply coil to drive the power supply coil to generate energy, and interrupt the at least one during a measurement period. A driving signal to stop driving the power supply coil to generate a coil signal of the power supply coil; a signal receiving module coupled to the power supply coil to receive the coil signal of the power supply coil; and a processor , Coupled to the signal receiving module, for performing the following steps: measuring multiple peaks of the coil signal in successive multiple oscillation cycles of the coil signal to obtain a plurality of peak trigger voltages respectively; according to the plurality of peaks A first peak trigger voltage and a second peak trigger voltage of the trigger voltages corresponding to two adjacent peaks are calculated as a first Save parameter; and comparing the first attenuation parameter to a first threshold value to determine whether there is a metal foreign substance within the power transmission range of one of the inductive power supply. The power supply module according to claim 11, wherein the processor is based on a difference between an average value of the first peak trigger voltage and the second peak trigger voltage with respect to the first peak trigger voltage and the second peak trigger voltage. Ratio, calculate the first attenuation parameter. The power supply module according to claim 11, wherein the first attenuation parameter is equal to a result of adding the first peak trigger voltage and the second peak trigger voltage divided by the first peak trigger voltage and the second peak trigger voltage Subtraction result. The power supply module according to claim 11, wherein the first peak trigger voltage is close to and lower than a corresponding first peak voltage of the plurality of peaks, and the second peak trigger voltage is close to and lower than the complex number The peak voltage corresponding to one of the two peaks. The power supply module according to claim 11, wherein the processor executes the following steps to measure the plurality of peaks of the coil signal within the continuous plurality of oscillation cycles of the coil signal to obtain the plurality of peak trigger voltages, respectively : Performing the following steps in one of the plurality of oscillation cycles: setting a reference voltage at a trigger starting potential; after a trigger signal appears, controlling the reference voltage to gradually rise; and when obtaining the trigger signal, the The reference voltage level is used as a peak trigger voltage of the plurality of peak trigger voltages. The power supply module according to claim 15, wherein the processor further performs the following steps to measure the plurality of peaks of the coil signal within the continuous plurality of oscillation periods of the coil signal to obtain the plurality of peak triggers respectively Voltage: Obtain a corresponding first previous peak trigger voltage obtained in the previous measurement period, and set the value obtained by subtracting a preset voltage value from the first previous peak trigger voltage as the trigger starting potential; or When the corresponding first previous peak trigger voltage is not obtained during the previous measurement period, the processor performs the following steps: obtaining a second previous peak trigger voltage within a previous oscillation period of the plurality of oscillation periods; Calculating an estimated peak trigger voltage according to the second previous peak trigger voltage; and setting a value obtained by subtracting the preset voltage value from the estimated peak trigger voltage as the trigger starting potential. The power supply module according to claim 11, wherein the processor executes the following steps to compare the first attenuation parameter and the first threshold value to determine whether a metal foreign object exists in the power transmission range of the inductive power supply. : When the first attenuation parameter is greater than the first critical value, judging that there is no metal foreign object in the power transmission range of the inductive power supply; and when the first attenuation parameter is less than the first critical value, the process The controller further performs the following steps: obtaining a third peak trigger voltage of the plurality of peak trigger voltages; calculating a second attenuation parameter according to the second peak trigger voltage and the third peak trigger voltage; and comparing the second attenuation Parameters and a second critical value. The power supply module according to claim 17, wherein the first threshold value is obtained by adding a predetermined first threshold value to a first threshold value, and the second threshold value is obtained by adding the second threshold value to a second threshold value. Value, wherein the second value is smaller than the first value. The power supply module according to claim 11, wherein the processor further performs the following steps: calculating a plurality of attenuation parameters according to the plurality of peak trigger voltages; and averaging the plurality of attenuation parameters to determine the inductive power supply Is there any metal foreign object in the power transmission range of the power supply. The power supply module according to claim 19, wherein the processor executes the following steps to average the plurality of attenuation parameters to determine whether there is a metal foreign object in the power transmission range of the inductive power supply: obtaining the plurality An average result is generated by averaging the attenuation parameters; comparing the average result with a basic threshold value; when the average result is greater than the basic threshold value, it is determined that there is no metal foreign object in the power transmission range of the inductive power supply And when the average result is less than the basic threshold value, it is determined that there is a metal foreign object in the power transmission range of the inductive power supply. A metal foreign object detection method is used for a power supply module of an inductive power supply. The power supply module includes a power supply coil. The metal foreign object detection method includes: obtaining a corresponding one of the previous measurements during the previous measurement period. The peak trigger voltage is set to a reference voltage value; at least one driving signal of the inductive power supply is interrupted during a measurement period to stop driving the power supply coil to generate a coil signal of the power supply coil; Measuring a first peak of the coil signal during an oscillation period of the signal to obtain a first peak trigger voltage; comparing the first peak trigger voltage with the reference voltage value; and when the first peak trigger voltage is equal to or close to At the reference voltage value, it is determined that there is no metal foreign object in a power transmission range of one of the inductive power supplies. The method for detecting a metal foreign object according to claim 21, wherein when the first peak trigger voltage is not equal to or close to the reference voltage value, the method for detecting a metal foreign object further includes the following steps: an oscillation period below the coil signal Measure a second peak of the coil signal internally to obtain a second peak trigger voltage; calculate an attenuation parameter based on the first peak trigger voltage and the second peak trigger voltage; and compare the attenuation parameter with a threshold value, To determine whether there is a metal foreign object in the power transmission range of the inductive power supply. The method for detecting a metal foreign object according to claim 21, further comprising: when the first peak trigger voltage is equal to or close to the reference voltage value, setting the reference voltage value to be equal to the first peak trigger voltage. The method for detecting a foreign metal object according to claim 21, further comprising: calculating the first peak trigger voltage to be determined to be equal to or close to a continuous number or a continuous time of the reference voltage value; and when the continuous number or the When the continuous time reaches an upper limit, the following steps are performed: measuring a second peak of the coil signal within an oscillation period below the coil signal to obtain a second peak trigger voltage; according to the first peak trigger voltage and the first Calculate an attenuation parameter with two peak trigger voltages; compare the attenuation parameter with a critical value to determine whether there is a metal foreign object in the power transmission range of the inductive power supply; and reset a counter to recalculate the continuous number of times, Or reset a timer to recalculate the continuous time. The method for detecting a metal foreign object according to claim 21, further comprising: setting a timer, and performing the following steps when the timer expires: measuring one of the coil signals within an oscillation period below the coil signal A second peak to obtain a second peak trigger voltage; calculate an attenuation parameter based on the first peak trigger voltage and the second peak trigger voltage; and compare the attenuation parameter with a threshold value to determine the inductive power supply Whether there is a metal foreign object within the power transmission range of the device.