CN108565976B

CN108565976B - Power supply module of induction type power supply system and signal detection method thereof

Info

Publication number: CN108565976B
Application number: CN201810223784.2A
Authority: CN
Inventors: 蔡明球; 詹其哲
Original assignee: Fu Da Tong Technology Co Ltd
Current assignee: Fu Da Tong Technology Co Ltd
Priority date: 2018-02-12
Filing date: 2018-03-19
Publication date: 2021-11-02
Anticipated expiration: 2038-03-19
Also published as: TW201820745A; TWI663806B; CN108565976A

Abstract

The invention discloses a power supply module and a signal detection method, which are used for an induction type power supply system. The first driving device is coupled to the power supply coil and used for driving the power supply coil to send power. The second driving device is coupled to the power supply coil and used for controlling the power supply coil to output a detection signal. The signal detection module is coupled to the power supply coil and used for detecting a reflection signal corresponding to the detection signal.

Description

Power supply module of induction type power supply system and signal detection method thereof

Technical Field

The present invention relates to a power supply module of an inductive power supply system and a signal detection method thereof, and more particularly, to a method for detecting a smart card for a power supply module of an inductive power supply system.

Background

In the induction type power supply, a power supply end pushes a power supply coil to generate resonance through a driving circuit so as to emit radio frequency electromagnetic waves, and then the coil of a power receiving end receives electromagnetic wave energy and then carries out electrical conversion so as to generate direct current power to be supplied to a power receiving end device. If electromagnetic energy sent by the power supply coil is applied to the metal body, a heating effect is generated on the metal body, and the metal body is possibly burnt and damaged after heat is accumulated. In the prior art, the inductive power supply includes a technology for detecting a metal object, which can effectively detect the metal object that may be affected by electromagnetic energy to generate heat, and interrupt energy transmission for protection after the metal object is found.

Smart cards have been used in a large number of everyday lives, and communicate using, for example, Near Field Communication (NFC), Radio Frequency Identification (RFID), or other similar technologies, and an internal chip is started to perform data feedback transmission after capturing micro electromagnetic energy.

In other words, the electromagnetic energy transmitted by the inductive power supply is too strong for the smart card, and the internal chip is often burned directly after being received by the smart card. However, the electromagnetic energy that the smart card can receive is so small that it cannot be identified by the detection technique of the conventional inductive power supply. The only reliable way is to set up a corresponding card reader on the sending coil of the induction power supply, and before sending power, the card reader determines whether the smart card exists. However, the additional cost is required for arranging the additional card reading device, and a plurality of different card reading devices are required for the smart cards with various specifications, so that the cost is increased, and the volume of the device is greatly increased by the card reading coil. In view of this, there is a need for improvement in the art.

Disclosure of Invention

Therefore, it is a primary objective of the present invention to provide a smart card detection method for a power supply module of an inductive power supply system, which can output a detection signal for a smart card through a power supply coil of the inductive power supply system to achieve smart card detection and improve the above-mentioned problems.

The invention discloses a power supply module, which is used for an induction type power supply system. The first driving device is coupled to the power supply coil and used for driving the power supply coil to send power. The second driving device is coupled to the power supply coil and used for controlling the power supply coil to output a detection signal. The signal detection module is coupled to the power supply coil and used for detecting a reflection signal corresponding to the detection signal.

The invention also discloses a signal detection method, which is used for a power supply module of an induction type power supply system, wherein the power supply module comprises a power supply coil. The signal detection method comprises the steps that a first driving device stops driving to control the power supply coil to suspend outputting power; driving the power supply coil to resonate by a second driving device during a period when the power supply coil is suspended from outputting power; detecting a coil signal of the power supply coil to obtain a peak voltage level of the coil signal; setting a reference voltage to the peak voltage level minus a predetermined voltage; the second driving device stops driving the power supply coil and restarts driving the power supply coil for a certain number of times to output a detection signal; and after outputting the detection signal, comparing the reference voltage with the coil signal to judge whether a reflection signal corresponding to the detection signal is received.

Drawings

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

Fig. 2 is a schematic diagram of a signal detection process according to an embodiment of the invention.

Fig. 3 is a waveform diagram illustrating sending detection signals and detecting corresponding reflection signals according to an embodiment of the invention.

Fig. 4 and 5 are schematic diagrams of another inductive power supply system according to another embodiment of the invention.

Wherein the reference numerals are as follows:

100. 400, 500 induction type power supply system

1 Power supply module

10 power supply

11 processor

12 clock generation module

121. 421 clock generator

13 power supply driving device

43 high-frequency driving device

14. 141, 451, 452 resonance capacitance

15 coil for power supply

16 signal detecting module

17 comparator

18D/A converter

160 voltage division circuit

161. 162 voltage dividing resistor

19 prompting device

44 switch module

441. 442, 443 switch

152 inductance

Vc coil signal

2 Power receiving Module

21 load cell

22 power receiving coil

3 smart card

31 coil

32 integrated circuit

20 Signal detection procedure

200 to 214 steps

Peak voltage level of V1

Reference voltage of V2

Sdet detection signal

Sref reflected signal

R1 resistor

Detailed Description

Referring to fig. 1, fig. 1 is a schematic diagram of an inductive power supply system 100 according to an embodiment of the invention. As shown in fig. 1, the inductive power supply system 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. The power supply module 1 includes a processor 11, a clock generating module 12, a power supply driving device 13,

resonant capacitors

14 and 451, a high frequency driving device 43, a switch module 44, a power supply coil 15, a signal detecting module 16, a prompting device 19, and a voltage dividing circuit 160. The power supply coil 15 can be used to send electromagnetic energy to the power receiving module 2 for power supply, and the resonant capacitor 14 is coupled to the power supply coil 15 and can be used to cooperate with the power supply coil 14 for resonance when power supply is performed. The power supply driving device 13 is coupled to the resonant capacitor 14 and the power supply coil 15, and is controlled by the processor 11 to transmit a driving signal to drive the power supply coil 15 to transmit power. The power supply driving device 13 may be driven by a full-bridge or a half-bridge, and the driving manner should not be a limitation of the present invention. In addition, in the power supply module 1, a magnetic conductor made of a magnetic material can be selectively used to improve the electromagnetic induction capability of the power supply coil 15, and simultaneously prevent electromagnetic energy from affecting objects in the direction of the non-induction surface of the coil.

In the embodiment of the present invention, the power supply coil 15 can be used for smart card detection, in addition to transmitting power. In detail, the high frequency driving device 43 is coupled to the power coil 15 through the resonant capacitor 451, and is used for controlling the power coil 15 to output a detection signal, which is used for detecting the presence of the smart card. The switch module 44 includes a switch 441 coupled between the high-frequency driving device 43 and the resonant capacitor 451, for controlling the operation of the high-frequency driving device 43. When the power supply coil 15 is to output power, the switch 441 can be controlled to be turned off; when the power coil 15 is going to output the detection signal, the switch 441 is controlled to be turned on, so that the high frequency driving device 43 can drive the power coil 15 to operate. In addition, the power supply driving device 13 may also be provided with a switch (not shown), which activates the power supply driving device 13 when outputting power, and deactivates the power supply driving device 13 when outputting the detection signal and controls the end of the power supply coil 15 that does not receive the driving signal of the high frequency driving device 43 to be coupled to the ground end.

After the power coil 15 outputs the detection signal, the signal detection module 16 can detect a reflection signal corresponding to the detection signal. In one embodiment, the signal detecting module 16 may be composed of a comparator 17 and a Digital to Analog Converter (DAC) 18, and is configured to track a peak value of a coil signal Vc of the power coil 15 and detect a reflected signal according to the peak value. The voltage divider circuit 160 includes

voltage divider resistors

161 and 162, which attenuate the coil signal Vc on the power coil 15 and output the attenuated signal to the signal detection module 16. In some embodiments, if the circuits such as the processor 11 and the signal detection module 16 have sufficient voltage endurance, the signal detection module 16 may directly receive the coil signal Vc on the power supply coil 15 without using the voltage division circuit 160.

In addition, the processor 11 is configured to receive the detection result of the signal detection module 16 to determine whether the smart card exists, and further control the operations of the power supply driving device 13 and the power supply coil 15, such as controlling whether to output power. The processor 11 may be any type of Processing device, such as a Central Processing Unit (CPU), a Microprocessor (Microprocessor), a single chip Microcomputer (MCU), and the like. The clock generating module 12 includes

clock generators

121 and 421 for outputting clock signals to the power supply driving device 13 and the high frequency driving device 43, respectively. The clock generating module 12 may be implemented by a Pulse Width Modulation (PWM) generator or other types of clock generators. The prompting device 19 is optionally disposed on the power supply module 1, and generates a prompting signal to notify the user of the inductive power supply system 100 to remove the smart card when the processor 11 determines that the smart card exists. The prompting device 19 may notify the user in any manner, such as displaying a light, a buzzer, a speaker, or by a screen display, etc. As for other possible components or modules, such as a power supply unit, a display unit, etc., which may be increased or decreased according to the system requirements, they are not shown in the description of the embodiment.

Please continue to refer to fig. 1. The power receiving module 2 includes a load unit 21 and a power receiving coil 22. The power receiving coil 22 is operable to receive power from the power supply coil 15. The load unit 21 generally refers to various internal components or modules of the power receiving coil 22, such as a voltage stabilizing circuit, a resonant capacitor, a rectifying circuit, a signal feedback circuit, a power receiving end processor, and the like, which may be increased or decreased according to system requirements, and should not be a limitation of the present invention. In addition, a smart card 3 is not included in the inductive power supply system 100 but is shown in fig. 1, and the smart card 3 may be, for example, a smart card conforming to Near Field Communication (NFC) standard, which includes a coil 31 and an Integrated Circuit (IC) 32.

Referring to fig. 2, fig. 2 is a schematic diagram of a signal detection process 20 according to an embodiment of the invention. The signal detection process 20 can be applied to a power supply module of an inductive power supply system (e.g., the power supply module 1 of the inductive power supply system 100 of fig. 1), and includes the following steps:

step 200: and starting.

Step 202: the driving is stopped by the power supply driving device 13 to control the power supply coil 15 to suspend outputting the power.

Step 203: switch 441 is engaged.

Step 204: while the power supply coil 15 is suspended from outputting power, the power supply coil 15 is driven by the high-frequency driving device 43 to resonate.

Step 206: the coil signal Vc of the power coil 15 is detected to obtain a peak voltage level V1 of the coil signal Vc.

Step 208: a reference voltage V2 is set at the peak voltage level V1 minus a predetermined voltage.

Step 210: the high frequency driving device 43 stops driving the power supply coil 15 and restarts driving the power supply coil 15 a certain number of times to output a detection signal Sdet.

Step 212: after outputting the detection signal Sdet, the reference voltage V2 is compared with the coil signal Vc to determine whether a reflected signal Sref corresponding to the detection signal Sdet is received.

Step 213: switch 441 is turned off.

Step 214: and (6) ending.

According to the signal detection process 20, the detection signal Sdet is sent during a period when the power supply coil 15 stops outputting power. Since the same power supply coil 15 is used for both power transmission and detection signal output, the power transmission and detection signal output are performed in a time-sharing manner. In this case, the power supply driving device 13 may stop driving to control the power supply coil 15 to suspend outputting the power, and the high frequency driving device 43 drives the power supply coil 15 to resonate. Generally, the energy output by the power supply coil 15 depends on the amplitude of the driving signal output by the driving device, the capacitance value of the resonant capacitor, the inductance value and the operating frequency of the power supply coil 15, and other factors. When the power supply driving device 13 drives the power supply coil 15 to output power, the output energy is larger, so that the power supply driving device 13 needs to output a larger signal amplitude, and the resonant capacitor 14 with a larger capacitance value is used, so that the power supply coil 15 operates at a lower frequency. When the high frequency driving means 43 drives the power supply coil 15 to resonate, the capacitance value of the resonant capacitor 451 is smaller (typically much smaller than the resonant capacitor 14) when the same power supply coil 15 (having the same inductance value) is used, so that the power supply coil 15 operates at a higher frequency while having a lower output signal amplitude that can be received by the smart card. In one embodiment, the driving capability of the high frequency driving device 43 may be reduced, or a resistor may be disposed between the high frequency driving device 43 and the power supply coil 15 to reduce the amplitude of the output signal of the power supply coil 15 driven by the high frequency driving device 43.

According to the specification of a general short-range Communication interface (such as Near Field Communication (NFC)), a Communication device is divided into a host side and a slave side, wherein the host side can be, for example, a card reader, and the slave side can be, for example, a smart card. The slave generally adopts a power-free mechanism, i.e., the slave does not need to receive power during standby. The host end can intermittently send a signal which is provided with electromagnetic energy and has a specific frequency, and when the slave end is close to the host end, if the received signal conforms to the recognizable frequency, the operation can be started through the received signal energy. When the slave is enabled, the signal/data may be reflected on the coil carrier by a load modulation technique. In other words, the host device may transmit a signal by polling (polling), and the slave device may feed back the identifier to the host at a specific time point after receiving the polling signal. In case the slave does not receive the polling signal, no action is performed.

In one embodiment, in order to detect the smart card of the nfc standard, the high frequency driving device 43 is required to drive the power supply coil 15 to operate at a frequency of 13.56MHz, so that the power supply coil 15 can output a detection signal corresponding to the nfc standard. In contrast, when the power supply driving device 13 drives the power supply coil 15 to output power, the operating frequency thereof is about 100 kHz. In this case, the capacitance value of the resonant capacitor 14 should be larger than that of the resonant capacitor 451 to control the power supply coil 15 to operate at a suitable frequency.

In this case, the step of driving the power supply coil 15 to output the detection signal by the high frequency driving device 43 may be performed during the period of time when the power supply driving device 13 controls the power supply coil 15 to suspend outputting the power. In another embodiment, the step of outputting the detection signal may be performed before the power coil 15 starts outputting power, so as to determine whether the smart card is present before outputting power.

Then, the power supply coil 15 may transmit a detection signal similar to the polling signal. Referring to fig. 3, fig. 3 is a schematic waveform diagram of sending a detection signal Sdet and detecting a corresponding reflection signal Sref according to an embodiment of the invention. Fig. 3 shows a waveform of a coil signal Vc of the power supply coil 15 (i.e., a voltage signal between the power supply coil 15 and the resonance capacitor 14). The coil signal Vc at the power supply coil 15 is oscillated by the driving of the high-frequency driving device 43. Then, the high frequency driving device 43 intermittently stops driving the power supply coil 15 for a plurality of times, i.e., stops driving the power supply coil 15 and restarts driving the power supply coil 15 for a certain number of times, so as to control the power supply coil 15 to output the detection signal Sdet. The specific number is the number specified by the relevant specification of the smart card, but it should not be limited thereto. At this time, if a smart card 3 exists near the power supply coil 15, the coil 31 of the smart card 3 can detect the detection signal Sdet and return the reflected signal Sref after a predetermined time, and the reflected signal Sref generates a modulation on the amplitude of the coil signal Vc, so that a section with a decreased amplitude appears on the coil signal Vc, as shown in fig. 3.

In order to detect the amplitude variation of the coil signal Vc to determine the reflected signal Sref, before receiving the reflected signal Sref, the signal detecting module 16 may first obtain and track the peak voltage level V1 of the coil signal Vc, and the tracking manner of the peak voltage level V1 is described in chinese patent publication No. CN106094041A, which is not repeated herein. Then, the processor 11 sets the reference voltage V2 to the peak voltage level V1 minus a predetermined voltage level, which is determined according to the specification of the smart card and the type of the reflected signal Sref. In one embodiment, if the smart card meets the nfc specification, the reflected signal Sref is fed back by using 10% amplitude modulation, i.e., the amplitude of the peak voltage of the reflected signal Sref on the coil signal Vc is reduced to about 10% of the amplitude. In this case, the magnitude of the preset voltage may be set to be close to but not more than one tenth of the amplitude at which the high-frequency driving device 43 drives the power supply coil 15 to resonate, that is, the height of the control reference voltage V2 is slightly higher than 90% of the resonant amplitude, as shown in fig. 3. In this case, the processor 11 may control the digital-to-analog converter 18 to output the reference voltage V2 to an input terminal of the comparator 17, and another input terminal of the comparator 17 receives the coil signal Vc, so as to compare the coil signal Vc with the reference voltage V2, and further determine whether the reflected signal Sref is received.

As can be seen from the above, the signal detection module of the present invention can be configured in the same manner as the comparator module for detecting metal foreign objects in chinese patent publication No. CN106094041A, i.e., the same circuit configuration can be used for metal foreign object detection and smart card detection, thereby reducing additional circuit cost.

Further, when the reflected signal Sref occurs, the comparator 17 of the signal detecting module 16 can detect that the peak voltage lower than the reference voltage V2 appears on the coil signal Vc, and then determine that the reflected signal Sref is received and transmit the related information to the processor 11. The processor 11 in turn determines that the smart card 3 is present within the power supply range of the power supply coil 15. It should be noted that, according to the nfc specification, the smart card 3 needs to respond to the reflected signal Sref 86 microseconds (μ s) after receiving the detection signal Sdet, and therefore, the setting of the reference voltage V2 can be completed within 86 microseconds after outputting the detection signal Sdet for detecting the reflected signal Sref.

In this case, if the smart card detection is performed during the period in which the power supply coil 15 suspends outputting power, the processor 11 may control the power supply coil 15 to completely stop transmitting power when the smart card 3 is detected. If the smart card detection is performed before the power supply coil 15 has not started outputting power, the processor 11 may control the power supply coil 15 not to start sending power when the smart card 3 is detected. In one embodiment, the processor 11 may control the prompting device 19 to generate a prompting signal to be provided to the user of the inductive power supply system 100 to notify the user to remove the smart card, and then the power supply module 1 re-executes the above-mentioned step of detecting whether the smart card 3 exists, until the power supply module starts to send power after determining that the smart card 3 is removed.

In addition, if the reflected signal Sref is not detected in a detection period, it indicates that the smart card 3 is not present in the power supply range of the power coil 15. In this case, the processor 11 may control the power supply coil 15 to continue to transmit power through the power supply driving device 13, and may suspend power supply again after outputting power for a certain period of time to perform the step of detecting whether the smart card 3 is present. Alternatively, after confirming that the smart card is not present, the power supply module 1 may further perform other detection, such as metal foreign object detection, before sending power.

It is noted that the present invention is directed to detecting whether the smart card is near the coil or within the power range of the coil by the coil of the inductive power supply, so as to prevent the smart card from being burnt by the electromagnetic energy output from the coil. Therefore, taking the power supply module 1 in fig. 1 as an example, when the processor 11 determines that the reflected signal Sref is received, the power supply coil 15 can be controlled to stop outputting power without performing subsequent decoding on the reflected signal Sref. In other words, unlike the conventional card reader which needs to decode to obtain the detailed information of the smart card after receiving the data fed back by the smart card, the present invention only needs to determine whether the smart card exists, and does not need to obtain the number, content or other related information of the smart card.

In addition, the power supply module and the signal detection method can be used for detecting the smart card which accords with the near field communication specification and can also be used for other types of smart cards. Referring to fig. 4, fig. 4 is a schematic diagram of another inductive power supply system 400 according to an embodiment of the invention. The inductive power supply system 400 is similar to the inductive power supply system 100 in structure, and therefore, signals or components having the same functions are represented by the same symbols. The main difference between the inductive power supply system 400 and the inductive power supply system 100 is that the power module 1 of the inductive power supply system 400 further includes a resonant capacitor 452 coupled between the power coil 15 and the high-frequency driving device 43, and is controlled by another switch 442 of the switch module 44. In addition, in the inductive power supply system 400, the power supply module 1 adopts a C-L-C coil structure, that is, one end of the power supply coil 15 is coupled to the resonant capacitor 14, and the other end is coupled to another resonant capacitor 141, so that the power supply driving device 13 can be driven by the two resonant capacitors. In addition, in the power supply module 1 of the inductive power supply system 400, the switch module 44 further includes a switch 443 coupled between one end of the power supply coil 15 and the ground. In this example, the

switches

441, 442 and 443 are included in the switch module 44, which may be implemented by a chip. But in other embodiments each switch may be independently set. In addition, a resistor R1 is provided at the output of the high-frequency driving device 43 for reducing the output power of the high-frequency driving device 43 for driving the power supply coil 15.

In the power supply module 1 of the inductive power supply system 400, the high frequency driving device 43 is coupled to the power supply coil 15 through the

resonant capacitors

451 and 452, respectively, and the switch module 44 can selectively turn on the

switch

441 or 442 to resonate through the

resonant capacitor

451 or 452. Preferably, the

resonant capacitors

451 and 452 have different capacitance values, so that the high frequency driving device 43 can generate resonance of different frequencies on the coil signal Vc through the different

resonant capacitors

451 and 452 for smart card detection in different frequency bands, which can be used for different types of smart cards or smart cards with different specifications. In one embodiment, the

switches

441 and 442 of the switch module 44 can be turned on simultaneously, so that the

resonant capacitors

451 and 452 are connected in parallel to form another capacitance value, thereby generating another different resonant frequency. In addition, more than two capacitors may be disposed between the high-frequency driving device 43 and the power supply coil 15, and the switch module 44 may control the high-frequency driving device 43 to couple to the power supply coil 15 through any one or more capacitors, so as to realize resonance of more different frequencies on the coil signal Vc. The number and arrangement of the capacitors and the corresponding resonant frequency can be determined according to various smart card specifications and detection requirements, which should not be construed as a limitation of the present invention.

In another embodiment, besides the high-frequency driving device 43, one or more additional high-frequency driving devices capable of outputting different detection signals may be disposed in the power supply module 1, and these high-frequency driving devices may generate different resonant frequencies on the coil signal Vc for detecting different types or different specifications of smart cards.

Please continue to refer to fig. 4. In the power supply module 1 of the inductive power supply system 400, all the

switches

441 and 442 for the high-frequency driving device 43 can be turned off during the power output period of the power supply coil 15, so as to avoid the strong driving signal output by the power supply driving device 13 from being transmitted to the high-frequency driving device 43 and causing the damage of the high-frequency driving device 43. During the smart card detection, in addition to turning on the switches 441 and/or 442 for the high frequency driving device 43, the switch 443 can be controlled to be turned on, so that the other end of the power supply coil 15 is coupled to the ground terminal as a resonance reference point. Similarly, in the power supply module 1 of fig. 1, there is also a switch inside the power supply driving device 13, which can be connected to the ground terminal, and can be turned on during the smart card detection.

In addition, the capacitance for resonating with the high-frequency driving device 43 may be set by other means. For example, referring to fig. 5, fig. 5 is a schematic diagram of another inductive power supply system 500 according to an embodiment of the invention. The inductive power supply system 500 is similar to the inductive power supply system 100 in structure, and therefore, signals or components having the same functions are represented by the same symbols. The main difference between the inductive power supply system 500 and the inductive power supply system 100 is that the power supply module 1 of the inductive power supply system 500 further includes a resonant capacitor 141 coupled between the power supply coil 15 and the power supply driving device 13, and the resonant capacitor 141, the power supply coil 15 and the resonant capacitor 14 form a C-L-C coil structure. In addition, in the power supply module 1 of the inductive power supply system 500, the resonant capacitor 451 for resonating with the high-frequency driving device 43 is connected in parallel with the power supply coil 15, and an inductor 152 (which can be implemented by a smaller coil) is further added between the high-frequency driving device 43 and the power supply coil 15.

In the power supply module 1 of the inductive power supply system 500, the

resonant capacitors

14 and 141 and the power supply coil 15 form a low-frequency resonant circuit, and resonance occurs when the power supply driving device 13 is driven. The resonant capacitor 451 is connected to the power coil 15 and the inductor 152 to form a resonant circuit with a higher frequency, which can generate a high frequency resonant signal by the driving of the high frequency driving device 43 during the detection of the smart card. Since the value of the resonant capacitor 451 is much smaller than that of the

resonant capacitors

14 and 141, when the power driving apparatus 13 pushes the C-L-C structure of the resonant capacitor 141, the power coil 15 and the resonant capacitor 14 to output power, the frequency is much lower than the resonant circuit formed by the resonant capacitor 451, and therefore, the influence of the resonant capacitor 451 can be ignored.

In summary, the present invention provides a signal detecting method for an inductive power supply, which is used to detect whether a smart card exists in a coil power supply range of the inductive power supply, so as to prevent the smart card from being burned out due to an excessive energy output by a power supply coil of the inductive power supply. In the embodiment of the invention, the power output and the smart card detection can be realized by the same coil and are performed in a time-sharing manner. The signal detection of the smart card can be carried out during the period that the power supply coil stops outputting power, when the processor detects the reflected signal and judges that the smart card exists, the power supply coil can be controlled to stop sending power or not to start sending power, and the processor only needs to judge whether the smart card exists or not, and does not need to decode the reflected signal to obtain other information of the smart card. In addition, in the embodiment of the invention, the power supply coil of the inductive power supply system can realize the functions of sending power and detecting the smart card, so that a card reader is not required to be additionally arranged, the cost for arranging the card reader can be saved, meanwhile, a user can arrange different numbers of capacitors with different values and/or adopt a plurality of high-frequency driving circuits corresponding to different resonant frequencies to detect in different frequency bands, and the invention can be applied to the detection of various different types of smart cards.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A power supply module for an inductive power supply system, the power supply module comprising:

a power supply coil;

a first driving device coupled to the power supply coil for driving the power supply coil to transmit power;

a second driving device, coupled to the power supply coil, for stopping driving the power supply coil and then restarting driving the power supply coil for a certain number of times to control the power supply coil to output a detection signal, wherein the detection signal is used for detecting a smart card, and a frequency of the detection signal is different from a frequency of the first driving device driving the power supply coil to transmit power;

a processor, coupled to the first driving device and the second driving device, for performing the following steps:

controlling the first driving device to stop driving so as to control the power supply coil to suspend outputting power;

controlling the second driving device to drive the power supply coil to resonate during a period when the power supply coil suspends outputting power;

detecting a coil signal of the power supply coil to obtain a peak voltage level of the coil signal; and

setting a reference voltage to the peak voltage level minus a predetermined voltage; and

and the signal detection module is coupled with the power supply coil and used for comparing the reference voltage with the coil signal so as to judge whether a reflected signal corresponding to the detection signal is received or not.

2. The power supply module of claim 1, further comprising:

a first resonant capacitor coupled between the power supply coil and the first driving device; and

a second resonance capacitor coupled between the power supply coil and the second driving device;

the capacitance value of the first resonance capacitor is larger than that of the second resonance capacitor.

3. The power supply module of claim 1, wherein when the signal detection module determines that the power supply coil receives the reflected signal, the processor determines that a smart card exists within a power supply range of the power supply coil.

4. The power supply module of claim 3, wherein the processor controls the power supply coil to stop or not to start sending power when the processor determines that the smart card is present within the power supply range of the power supply coil.

5. The power supply module of claim 3, further comprising:

and the prompting device is used for generating a prompting signal to be provided for a user of the induction type power supply system when the processor judges that the intelligent card exists in the power supply range of the power supply coil.

6. The power supply module of claim 1 wherein the processor does not decode the reflected signal when the power coil receives the reflected signal.

7. The power supply module of claim 1, wherein the signal detection module comprises:

a digital-to-analog converter for receiving the reference voltage from the processor; and

and the comparator is coupled with the digital-to-analog converter and used for comparing the reference voltage with the coil signal of the power supply coil so as to judge whether the reflected signal is received or not.

8. The power supply module of claim 2, further comprising:

at least one third resonant capacitor coupled between the power supply coil and the second driving device, wherein the capacitance values of the at least one third resonant capacitor are different from each other and different from the capacitance value of the second resonant capacitor; and

a switch module for controlling the second driving device to selectively connect to the power supply coil through at least one of the second resonant capacitor and the at least one third resonant capacitor.

9. The power supply module of claim 8 wherein the switch module further controls the power coil to be coupled to a ground terminal.

10. The power supply module of claim 1, further comprising:

at least one third driving device, coupled to the power supply coil, for controlling the power supply coil to output another detection signal;

the frequencies of the at least one third driving device for driving the power supply coil to resonate are different from each other and different from the frequencies of the second driving device for driving the power supply coil to resonate.

11. The power supply module of claim 1, further comprising:

and the resistor is coupled between the power supply coil and the second driving device.

12. The power supply module of claim 1, further comprising:

a first resonant capacitor coupled between the power supply coil and the first driving device;

a second resonant capacitor coupled in parallel with the power supply coil; and

an inductor coupled between the power supply coil and the second driving device.

13. A signal detection method is used for a power supply module of an induction type power supply system, the power supply module comprises a power supply coil, and the signal detection method comprises the following steps:

stopping driving by a first driving device to control the power supply coil to suspend outputting power;

driving the power supply coil to resonate by a second driving device during a period when the power supply coil is suspended from outputting power;

detecting a coil signal of the power supply coil to obtain a peak voltage level of the coil signal;

setting a reference voltage to the peak voltage level minus a predetermined voltage;

the second driving device stops driving the power supply coil and restarts driving the power supply coil for a certain number of times to output a detection signal; and

after the detection signal is output, the reference voltage is compared with the coil signal to judge whether a reflection signal corresponding to the detection signal is received.

14. The signal detection method as claimed in claim 13, wherein the predetermined voltage is close to but not more than one tenth of a resonant amplitude of the second driving means for driving the power coil to resonate.

15. The signal detection method as claimed in claim 13, wherein the step of comparing the reference voltage with the coil signal after outputting the detection signal to determine whether the reflected signal corresponding to the detection signal is received comprises:

and judging that the reflected signal is received when a peak voltage of the coil signal is detected to be lower than the reference voltage in a period after the detection signal is output.

16. The signal detection method as claimed in claim 13, further comprising:

when the reflected signal is judged to be received, the intelligent card is judged to exist in a power supply range of the power supply coil.

17. The signal detection method as claimed in claim 16, further comprising:

when the smart card is judged to be in the power supply range of the power supply coil, the power supply coil stops or does not start to transmit power.

18. The signal detection method as claimed in claim 16, further comprising:

when the smart card is judged to exist in the power supply range of the power supply coil, a prompt signal is generated and provided for a user of the induction type power supply system.

19. The signal detection method as claimed in claim 13, wherein when the power coil receives the reflected signal, the power module does not decode the reflected signal.