CN107834712B - Method for detecting power receiving module and power supply module - Google Patents
Method for detecting power receiving module and power supply module Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
- H02J50/10—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling
- H02J50/12—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling of the resonant type
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
- H02J50/90—Circuit arrangements or systems for wireless supply or distribution of electric power involving detection or optimisation of position, e.g. alignment
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Abstract
The invention discloses a method for detecting a power receiving module, which is used for a power supply module of an induction type power supply, wherein the power supply module comprises a power supply coil; judging whether the self-resonance frequency is less than a basic frequency; when the self-resonant frequency is judged to be smaller than the basic frequency and the amplitude smaller than the basic frequency exceeds a critical value, acquiring first output power corresponding to the self-resonant frequency; and sending a starting signal through the first output power, and starting to supply power when receiving a data code corresponding to the starting signal.
Description
Technical Field
The present invention relates to a method for detecting a power receiving module and a power supply module, and more particularly, to a method for detecting a power receiving module by detecting a coil distance and a power supply module thereof.
Background
In an inductive power supply, for safe operation, the power supply end needs to confirm that the inductive area on the power supply coil is the correct power receiving device, and power transmission is performed only in a condition that power can be received. The data code is transmitted by driving the power supply coil to generate resonance through the power supply end, transmitting electromagnetic energy to the power receiving end to transmit power, and when the power receiving end receives power, the impedance state on the receiving coil can be changed through a signal modulation technology, and then the resonance carrier signal on the power supply coil is influenced through feedback to change so as to transmit the data code.
When the power supply terminal is in standby state, it is necessary to periodically detect whether there is a power receiving terminal to identify whether the power receiving terminal enters its power supply range. In the prior art, the power receiving end periodically sends energy in a manner that the power receiving end detects the power receiving end, when the power receiving end enters the coil induction range of the power supplying end and receives the energy transmitted by the power supplying end, the power receiving end starts and reflects data to the power supplying end, and the power supplying end judges that the received data is correct and can start to operate.
However, the operation of the power supply terminal transmitting energy detection power receiving terminal is accompanied by continuous energy transmission, and if the transmitted energy is not received by the coil of the power receiving terminal, a problem of excessive Electromagnetic Interference (EMI) is likely to occur. When no power receiving terminal enters the coil induction range of the power supply terminal for a long time, excessive power loss is generated by continuously transmitting energy. In addition, when the power receiving end is close to the power supply end, the power supply end cannot judge the distance to the power receiving end. If the power receiving end is close to the power supply end and the energy sent by the power supply end is too large, the power receiving end can be burnt out by receiving too large energy instantly; if the power receiving end is far away from the power supply end and the energy transmitted by the power supply end is too small, the existence of the power receiving end cannot be effectively detected. In view of this, there is a need for improvement in the art.
Disclosure of Invention
Therefore, the present invention is directed to a method for detecting a power receiving module and a power supply module thereof, which can determine whether the power receiving module exists and determine a distance between the power receiving module and the power supply coil by detecting a self-resonant frequency of the power supply coil, so as to control the power supply coil to output a suitable power.
The invention discloses a method for detecting a power receiving module, which is used for a power supply module of an induction type power supply. The method comprises detecting the power supply coil to obtain a self-resonant frequency of the power supply coil; judging whether the self-resonance frequency is less than a basic frequency; when the self-resonant frequency is judged to be smaller than the basic frequency and the amplitude smaller than the basic frequency exceeds a critical value, acquiring first output power corresponding to the self-resonant frequency; and sending a starting signal through the first output power, and starting to supply power when receiving a data code corresponding to the starting signal.
The invention also discloses a power supply module which is used for the induction type power supply and is used for detecting a power receiving module of the induction type power supply. The power supply module comprises a power supply coil and a processor. The processor may be configured to perform the steps of: detecting the power supply coil to obtain a self-resonant frequency of the power supply coil; judging whether the self-resonance frequency is less than a basic frequency; when the self-resonant frequency is judged to be smaller than the basic frequency and the amplitude smaller than the basic frequency exceeds a critical value, acquiring first output power corresponding to the self-resonant frequency; and controlling the power supply coil to send a starting signal through the first output power, and controlling the power supply coil to start supplying power when receiving a data code corresponding to the starting signal.
Drawings
Fig. 1 is a schematic diagram of a power supply module according to an embodiment of the invention.
FIG. 2 is a waveform diagram illustrating detection of a self-resonant frequency according to an embodiment of the present invention.
Fig. 3 is a flowchart of a detection process according to an embodiment of the invention.
Fig. 4 is a flowchart of a maximum output power setting process according to an embodiment of the invention.
Wherein the reference numerals are as follows:
1 Power supply module
111 processor
112 clock generator
113. 114 powered drive unit
115 resonant capacitor
116 supply coil
117 magnetic conductor
118 memory
120 comparator module
130 voltage dividing circuit
131. 132 voltage dividing resistor
D1, D2 drive signals
C1 coil signal
30 detection process
300 to 316 steps
40 maximum output Power setting procedure
400 to 408 steps
Detailed Description
Referring to fig. 1, fig. 1 is a schematic diagram of a power supply module 1 according to an embodiment of the invention. The power supply module 1 may be used in an inductive power supply for sending power to a power receiving module of the inductive power supply. The power supply module 1 includes a power supply coil 116 and a resonant capacitor 115. The power supply coil 116 can be used to send electromagnetic energy to the power receiving module for power supply, and the resonant capacitor 115 is coupled to the power supply coil 116 and can be used to cooperate with the power supply coil 116 for resonance. In addition, in the power supply module 1, a magnetic conductor 117 made of a magnetic material can be selectively used to enhance the electromagnetic induction capability of the power supply coil 116, and at the same time, prevent the electromagnetic energy from affecting the object in the direction of the non-inductive surface of the coil.
In order to control the operations of the power coil 116 and the resonant capacitor 115, the power module 1 further includes a processor 111, a clock generator 112, power driving units 113 and 114, a memory 118, a comparator module 120, and a voltage divider circuit 130. The power driving units 113 and 114 are coupled to the power coil 116 and the resonant capacitor 115, and respectively send driving signals D1 and D2 to the power coil 116, which can receive the control of the processor 111 to drive the power coil 116 to generate and send energy. When both the power supply driving units 113 and 114 operate simultaneously, full-bridge driving can be performed. In some embodiments, only one of the power driving units 113 and 114 may be turned on, or only one power driving unit 113 or 114 may be disposed to perform half-bridge driving. The clock generator 112 is coupled to the power driving units 113 and 114, and is used for controlling the power driving units 113 and 114 to send the driving signals D1 and D2 or interrupt the driving signals D1 and D2. The clock generator 112 may be a Pulse Width Modulation (PWM) generator or other type of clock generator, and is used for outputting a clock signal to the power driving units 113 and 114. The processor 111 may receive information related to the coil signal C1 (i.e. the voltage signal between the power coil 116 and the resonant capacitor 115) on the power coil 116, and control the output power of the power coil 116 according to the coil signal C1. In detail, the processor 111 may control the switching frequency of the driving signals D1 and D2 output by the power driving units 113 and 114 to change the amplitude of the resonant signal of the power coil 116 and the resonant capacitor 115, thereby controlling the output power of the power coil 116. The processor 111 may be a Central Processing Unit (CPU), a microprocessor (microprocessor), a Micro Controller Unit (MCU), or other types of Processing devices or computing devices. The comparator module 120 may be used to track the self-resonant frequency or period of the coil signal C1 and provide information regarding the self-resonant frequency or period to the processor 111 for subsequent interpretation. The comparator module 120 may include one or more comparators in combination with a Digital-to-Analog Converter (DAC). For a detailed operation manner of the comparator module 120 to obtain the coil self-resonant frequency or period, refer to the description of chinese patent application publication No. CN 106094041a, which is not repeated herein. The voltage divider circuit 130 includes voltage divider resistors 131 and 132, which attenuate the coil signal C1 on the power coil 116 and output the attenuated signal to the processor 111 and the comparator module 120. In some embodiments, if the circuits such as the processor 111 and the comparator module 120 have sufficient voltage endurance, the coil signal C1 on the power supply coil 116 may be directly received by the processor 111 without using the voltage divider circuit 130. The memory 118 can be used to store the self-resonant frequency/period information of the power supply coil 116 and its corresponding operating frequency and/or output voltage information. The Memory 118 may be various types of Memory devices, such as a Read-Only Memory (ROM), a flash Memory (flash Memory), a Random-Access Memory (RAM), and the like, but is not limited thereto. 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.
Generally, the self-resonant frequency of the coil is related to the inductance and capacitance of the coil assembly, and when the inductance or capacitance rises, the self-resonant frequency of the coil falls; when the inductance or capacitance value decreases, the coil self-resonant frequency increases. In the power supply module 1, the capacitance value is determined by the capacitance value of the resonant capacitor 115, and the value is approximately fixed and the variation is small; the inductance is determined by the inductance of the power coil 116, but varies with the surrounding magnetic material. When the wrapping property of the magnetic material on the periphery of the power supply coil 116 is increased, the inductance is increased; when the wrapping of the magnetic material around the power supply coil 116 is reduced, the inductance is reduced. Further, the power receiving coil of the inductive power supply is often provided with a magnetic material, so that when the power receiving coil approaches the power supply coil 116, the covering property of the magnetic material is increased, so that the inductance is correspondingly increased, and the resonant frequency of the power supply coil 116 is further reduced; conversely, when the power receiving coil is far from the power supply coil 116, the covering property of the magnetic material is reduced, so that the inductance is correspondingly reduced, and the resonant frequency of the power supply coil 116 is increased. Therefore, the distance between the power receiving coil (or power receiving module) and the power supply coil 116 can completely correspond to the self-resonant frequency of the power supply coil 116, and the closer the distance, the lower the self-resonant frequency. In this case, the present invention can determine whether there is a power receiving module near the power supply module by detecting the self-resonant frequency of the power supply coil 116, so as to replace the conventional method in which the power supply terminal continuously transmits energy to detect the power receiving terminal. In addition, by detecting the self-resonant frequency of the power supply coil 116, the distance between the power receiving module and the power supply module 1 can be accurately determined, so that the power supply module 1 can properly adjust the coil output power.
To accurately obtain the self-resonant frequency of the power coil 116 and the distance between the power coil 116 and the power receiving coil, the power module 1 may start a learning mode, and detect the self-resonant frequency of the coil under different situations in the learning mode. When no object is placed in the coil sensing range of the power coil 116, the processor 111 obtains the self-resonant frequency of the power coil 116, which is regarded as a fundamental frequency and stored in the memory 118 as a basis for a subsequent comparison. Then, when the power supply module 1 is started and starts to operate, as long as the power supply module 1 detects that the self-resonant frequency of the power supply coil 116 is smaller than the fundamental frequency, and the amplitude of the self-resonant frequency smaller than the fundamental frequency exceeds a threshold value, it indicates that a power receiving module may have entered the coil induction range of the power supply coil 116.
Referring to fig. 2, fig. 2 is a waveform diagram of detecting a self-resonant frequency according to an embodiment of the invention, and fig. 2 shows waveforms of a coil signal C1 and a driving signal D1 or D2. Specifically, to detect the self-resonant frequency of the power coil 116, the power driving unit 113 or 114 may generate a pulse signal on the driving signal D1 or D2, and the coil signal C1 oscillates with the pulse signal and continues to oscillate naturally and attenuate after the pulse signal ends. During the natural oscillation, the processor 111 can obtain the frequency of the oscillation of the coil signal C1, which is the self-resonant frequency of the power coil 116, through the comparator module 120. Generally, the driving signal D1 or D2 only needs a very short pulse signal to trigger the oscillation of the coil signal C1, the length of the pulse signal can reach as long as several or tens of microseconds (microsecond), and the amplitude of the natural oscillation of the coil signal C1 falls within about 2-3V. In contrast, the prior art performs the power-receiving end detection by sending energy to activate the power-receiving module, wherein the energy sent by the power coil 116 needs to be enough to be received by the power-receiving module and activate the power-receiving module, so the driving signals D1 and D2 need to drive the power coil 116 for a period of time (about 2-3 milliseconds) each cycle, at least enough energy needs to be output by the power coil 116, and the amplitude of the coil signal C1 may be as high as 20-30V. In this case, the power loss and the Electromagnetic Interference (EMI) generated in the power supply module 1 of the present invention during the process of detecting the power receiving end are much smaller than those of the conventional power supply module. Therefore, the power receiving end detection method can solve the problem of overlarge electromagnetic interference in the prior art. In addition, the method for detecting the resonant frequency of the coil of the present invention can be completed only by a plurality of oscillation cycles (e.g. 2-3 cycles) of the coil signal C1, and the detection speed is much faster than the conventional method for transmitting energy to start the power receiving module. The increase of the detection speed enables the power supply module 1 to be quickly known when the power receiving module enters the power supply range, so as to improve the sensitivity of the system.
In addition, in the learning mode, the processor 111 may further obtain the self-resonant frequency of the power supply coil 116 and the corresponding output voltage and/or operating frequency thereof when the power receiving module is located at different positions. As described above, when the power receiving coil is closer to the power supplying coil 116, the self-resonant frequency is lower, so that different positions can correspond to different self-resonant frequencies, and the power supplying module 1 can determine the position of the power receiving coil according to the detected self-resonant frequency to adopt a suitable output voltage or output power for power supply. In the learning mode, the processor 111 may obtain the operating frequency and/or the output voltage of the inductive power supply in an unloaded state or a fully loaded state, respectively, and obtain the corresponding relationship between the operating frequency and the self-resonant frequency.
In detail, in the learning mode, a power receiving module can be set to be idle, and at this time, the power supply module 1 can instruct a user or a tester to set the power receiving module at a plurality of positions within the coil sensing range of the power supply coil 116 for performing a test respectively. When the power receiving module is located at different positions in the coil induction range, the power supply module 1 can respectively supply power to the power receiving module, and the operating frequency, the no-load output voltage and the self-resonant frequency of the power supply coil 1 are measured in the power supply process. Further, the operating frequency and the idle output voltage are the optimal operating points for the power supply module 1 to supply power to the power receiving module in the idle state, where the operating frequency is the frequency of the power supply coil 116 and the oscillation of the driving signals D1 and D2 during power supply, and the idle output voltage is the output voltage of the power supply coil 116 during idle, which corresponds to the amplitude of the sine wave of the power supply coil 116. The self-resonant frequency is the natural oscillation frequency of the power coil 116 during the short-term interruption of the driving signals D1 and D2, and when the power coil is located at different positions, the measured self-resonant frequency is different, which is related to the distance between the power coil and the power coil 116. For a detailed operation manner of the driving signals D1 and D2 for temporarily interrupting the driving to measure the self-resonant frequency of the power coil 116, reference is made to the description of chinese patent application publication No. CN 106094041a, which is not repeated herein.
In addition, in the learning mode, the power receiving module can be set to be full and corresponding data can be acquired. In detail, in the fully loaded state, the power module 1 can instruct the user or the tester to place the power receiving module at a plurality of positions within the coil sensing range of the power coil 116 for performing the test respectively. When the power receiving module is located at different positions within the coil induction range, the power supply module 1 can respectively supply power to the power receiving module, and the operating frequency, the full-load output voltage and the self-resonant frequency of the power supply coil 1 are measured in the power supply process. The measurements of the learning mode may be stored in the memory 118, and in one embodiment, the measurements may be summarized in a table for storage, as shown in Table 1.
TABLE 1
As shown in table 1, different self-resonant frequencies can be measured by moving the power receiving coil to different positions in the learning mode, and the closer the distance between the power receiving coil and the power transmitting coil 116 is, the lower the self-resonant frequency is, and the farther the distance is, the higher the self-resonant frequency is. When the receiving coil is located at different positions, the output voltage and the operating frequency of the no-load and the output voltage and the operating frequency of the full-load can be obtained respectively. Then, the power supply module 1 can detect and adjust the output power of the power receiving module according to the data stored in table 1.
Referring to fig. 3, fig. 3 is a flowchart of a detection process 30 according to an embodiment of the invention. The detection process 30 can be applied to a processor in a power supply module of an inductive power supply, such as the processor 111 in the power supply module 1 of fig. 1, for detecting whether a power receiving end enters a coil sensing range of the power supply module 1. As shown in fig. 3, the detection process 30 includes the following steps:
step 300: and starting.
Step 302: the power coil 116 is detected to obtain a self-resonant frequency of the power coil 116.
Step 304: whether the self-resonance frequency is smaller than a basic frequency and whether the amplitude of the self-resonance frequency smaller than the basic frequency exceeds a critical value is judged. If yes, go to step 306; if not, go back to step 302.
Step 306: and judging whether the self-resonant frequency stops changing for a period of time. If yes, go to step 308; if not, go back to step 304.
Step 308: a first output power corresponding to the self-resonant frequency is retrieved from the memory 118.
Step 310: the control power supply coil 116 transmits an activation signal through the first output power and detects a data code corresponding to the activation signal.
Step 312: and judging whether the data code is received. If yes, go to step 314; if not, go back to step 310; if the start signal is sent multiple times but the corresponding data code is not received, go back to step 302.
Step 314: the power supply coil 116 is controlled to start supplying power.
Step 316: and (6) ending.
According to the detection process 30, the power supply module 1 continuously detects a self-resonant frequency of the power supply coil 116 during the standby (step 302), for example, the processor 111 may control the driving signal D1 or D2 to generate a very short pulse signal to trigger the oscillation of the coil signal C1 (as shown in the method of fig. 2), so that the processor 111 may obtain the frequency of the oscillation of the coil signal C1 as the self-resonant frequency of the power supply coil 116 through the comparator module 120. Next, the processor 111 determines whether the self-resonant frequency is smaller than the base frequency and whether the amplitude of the self-resonant frequency smaller than the base frequency exceeds a threshold (step 304). In particular, the fundamental frequency may be retrieved and stored in the memory 118 during the learn mode, and the processor 111 may retrieve the fundamental frequency from the memory 118 and compare it to the self-resonant frequency measured in step 302. Taking table 1 as an example, assuming that the fundamental frequency is 170kHz and the coil induction range of the power supply coil 116 corresponds to the range between the self-resonant frequency 100kHz to 150kHz, in this case, the threshold value may be set to 20kHz (170kHz to 150kHz), that is, when the processor 111 detects that the self-resonant frequency is less than a target value of 150kHz, it determines that a power receiving coil or a power receiving module may exist in the induction range of the power supply coil 116, and performs the subsequent determination procedure.
Next, the processor 111 may determine whether the self-resonant frequency of the power supply coil 116 stops changing for a period of time (step 306). When it is determined that the self-resonant frequency has not changed within a period of time, which indicates that the power-receiving module has reached the fixed position, the processor 111 may obtain a first output power corresponding to the current self-resonant frequency (step 308). In the learn mode, the processor 111 has first retrieved the unloaded output voltage from the resonant frequency and stored in the memory 118 (as shown in Table 1). In step 308, the processor 111 retrieves the corresponding idle output voltage from the memory 118 according to the detected self-resonant frequency and sets the first output power according to the idle output voltage. Next, the processor 111 controls the power supply coil 116 to send a start signal through the first output power and detect a corresponding data code (step 310). In other words, the processor 111 may determine the distance between the power receiving module and the power supply coil 116 according to the self-resonant frequency, so as to transmit the start signal with the most suitable output power at the distance. The output power adopted by the power supply module 1 corresponds to the no-load output voltage measured during no-load, because the powered module often does not apply a load when receiving the start signal for starting, and subsequently when the load of the powered module increases, a data code can be returned to inform the power supply module 1 to increase the output power.
Taking table 1 as an example, if the self-resonant frequency is detected to be 140kHz, the power supply coil 116 can use 90V output voltage and corresponding output power to send the start signal; if the self-resonant frequency is detected to be 100kHz, which represents that the power receiving module is close to the power supply coil 116, the power supply coil 116 can transmit the start signal by using the 50V output voltage and the corresponding output power.
In contrast, in the prior art, the power supply coil transmits energy with a predetermined output power before the power receiving end is not detected, that is, when the power receiving coil enters the induction range of the power supply coil, the power supply end cannot immediately know the distance to the power receiving coil, only the predetermined output power is used to transmit energy, and the output power can be adjusted according to the information carried by the data code after the data code returned by the power receiving end is received. Therefore, before the power supply module receives the data code, the power receiving module cannot be detected with the most suitable output power, which may cause a problem that the power receiving module is burned due to too large output power (when the power receiving module is too close), or the power receiving module cannot be effectively detected due to too small output power (when the power receiving module is too far). The above problems can be solved by the embodiment of the present invention in a manner of determining the distance between the power supply module and the power receiving module according to the self-resonant frequency.
In addition, in the process 30, the processor 111 may first determine whether the self-resonant frequency of the power supply coil 116 stops changing for a certain period of time, and then perform the subsequent step of transmitting the start signal. Generally, when the power receiving module is going to be charged, the power receiving module gradually approaches the power supply module 1. For example, a user holds a mobile phone to be charged close to a wireless charging station, or an electric vehicle or an automatic vehicle moves to the charging station, and the mobile phone or the automatic vehicle must gradually approach the charging module and cannot be instantly located. If the processor 111 drives the power supply coil 116 to send the start signal according to the position of the power receiving module immediately after detecting that the self-resonant frequency drops to the specific value, due to the delay of signal transmission inside the power supply module 1, when the power supply coil 116 sends the start signal, the moving power receiving module tends to be closer to the power supply coil 116, so that the output power of the power supply coil 116 sending the start signal is too large. To avoid the above problem, the processor 111 of the present invention may determine that the self-resonant frequency stops changing (representing that the receiving coil stops moving), and then control the power coil 116 to transmit the start signal through the first output power, where the first output power is the most suitable output power under the position of the receiving coil.
After the power coil 116 of the power module 1 sends the start signal, it is determined whether a data code is received (step 312). If the data code is not received, it is not possible to determine whether the power receiving module exists, and at this time, the power supply coil 116 may send the start signal again and continuously detect the start signal by the processor 111 to determine whether the data code responded by the power receiving module exists again. If the data code is not received after the start signal is sent for multiple times, it represents that there is no valid powered module in the coil sensing range of the power supply module 1, at this time, the sending of the start signal may be stopped, and the procedure of periodically detecting the self-resonant frequency of the coil is performed (step 302). For example, a user may inadvertently place a wireless-power-receivable cell phone, having a coil and magnetic material for receiving wireless power, in a location near a wireless charging cradle, but without turning on the wireless charging function of the cell phone. In this case, the power supply module 1 can detect that the mobile phone is close to the mobile phone through the change of the self-resonant frequency, but cannot receive the correct data code. In one embodiment, a maximum number of times of sending the start signal may be set, and when the number of times of sending the start signal exceeds the maximum number of times but the power supply module 1 still does not receive the data code, the power supply coil 116 stops sending the start signal and the power supply module 1 returns to the process of periodically detecting the coil self-resonant frequency. Until the self-resonant frequency is detected to change again, the power supply module 1 executes subsequent judgment and starts sending of signals.
If the processor 111 of the power supply module 1 receives the data code and determines that the received data code is correct, it indicates that a valid powered module has entered the power supply range of the power supply module 1 and is located, and at this time, the power supply module 1 may start to supply power. The processor 111 may be powered by any method, for example, the power may be powered according to the first output power corresponding to the self-resonant frequency, or the output power may be adjusted according to the condition that the data code obtains the power received by the power receiving terminal, and then the output power is adjusted according to the load size.
It should be noted that, during the power supplying process, the power supplying module 1 may also continuously detect the self-resonant frequency of the power supplying coil 116, and adjust the output power according to the change of the self-resonant frequency. For example, when the self-resonant frequency decreases, which means that the power receiving module is closer to the power supply coil 116, the output power should be reduced to avoid the excessive energy received by the power receiving end; when the self-resonant frequency rises, which means that the power receiving module is further away from the power supply coil 116, the output power should be increased to make the power receiving end effectively receive power. In addition, during the power supply process, the power supply module 1 still continuously determines whether the self-resonant frequency of the power supply coil 116 is close to or greater than the basic resonant frequency, and if the self-resonant frequency is close to or greater than the basic resonant frequency, it represents that the power receiving module has left the coil induction range of the power supply module 1, in this case, the power supply module 1 may stop supplying power and return to the procedure of periodically detecting the self-resonant frequency of the coil.
In detail, the power supply module 1 can control the driving signals D1 and D2 to temporarily interrupt driving during the power supply period, so that the power supply coil 116 naturally oscillates to detect the self-resonant frequency, and the operation manner of the power supply module is the same as the manner of the driving interruption in the learning mode, i.e., the manner adopted by chinese patent application publication No. CN 106094041 a.
In addition, in the learning mode, the processor 111 obtains the full-load output voltage and the corresponding operating frequency of the power-receiving module at different positions. Taking table 1 as an example, when the power receiving module is closer to the power supply coil 116 (for example, the self-resonant frequency is 100kHz), the measured full-load output voltage is 100V and the corresponding operating frequency is 110 kHz; when the powered module is far from the power coil 116 (e.g., 150kHz from the resonant frequency), the measured full-load output voltage is 150V and the corresponding operating frequency is 160 kHz. In other words, when the coil is far away, the power supply coil 116 needs to increase the output voltage and output power to transmit power to the far power receiving coil.
Generally, in an inductive power supply, a power supply module needs to set a maximum value of a coil output power as an upper limit to prevent the power supply coil from being over-powered to burn out a power receiving device. That is, the processor of the power supply module may control the output power of the power supply coil not to exceed the upper limit, or the inductive power supply may initiate a protection measure or actively power off when the power supply module or the power receiving module detects that the output power exceeds the upper limit. Considering that the power receiving module is more likely to receive excessive energy when being closer to the power supply coil, if the power receiving module is to avoid burning due to excessive energy received by the power receiving module, the power supply module should set the maximum output power (for example, set the maximum output voltage to 100V) according to the full-load output voltage corresponding to the power receiving module located at a close distance, however, this setting may not provide sufficient power supply capability when the power receiving module is farther from the power supply coil. In other words, when the power receiving coil is far away, the power supply coil should output 150V to supply the power required by the full load, but limited to the preset maximum output power, the power supply coil can only provide 100V of output voltage at most. In order to solve the above problem, the present invention may use the full-load output voltage obtained in the learning mode to set the maximum output power, and as the distance between the power receiving coil and the power supplying coil is different, the processor 111 may determine the distance between the power receiving coil and the power supplying coil according to the detected self-resonant frequency, and set the appropriate maximum output power accordingly.
Referring to fig. 4, fig. 4 is a flowchart of a maximum output power setting process 40 according to an embodiment of the invention. The maximum output power setting process 40 can be applied to a processor in a power supply module of an inductive power supply, such as the processor 111 in the power supply module 1 of fig. 1, for setting the maximum output power of the power supply coil 116. As shown in fig. 4, the maximum output power setting process 40 includes the following steps:
step 400: and starting.
Step 402: during the power supply of the power supply module 1, the power supply coil 116 is detected to obtain a self-resonant frequency of the power supply coil 116.
Step 404: a full load output voltage corresponding to the self-resonant frequency is retrieved from memory 118.
Step 406: the maximum output power of the power supply coil 116 is set according to the full-load output voltage.
Step 408: and (6) ending.
According to the maximum output power setting process 40, the power supply module 1 can control the driving signals D1 and D2 to temporarily interrupt the driving during the power supply period, so that the power supply coil 116 naturally oscillates to detect the self-resonant frequency (step 402). Next, the processor 111 retrieves the full-load output voltage obtained in the learning mode from the memory 118 according to the current coil self-resonant frequency (step 404), and sets the maximum output power of the power supply coil 116 accordingly (step 406). Taking table 1 as an example, if the self-resonant frequency of the coil is detected to be 100kHz, the maximum output voltage of the power supply coil 116 can be set to 100V; if the coil self-resonant frequency is detected to be 150kHz, the maximum output voltage of the power supply coil 116 can be set to be 150V. That is, if it is detected that the coil self-resonant frequency is higher, it represents that the power receiving module is farther from the power supply coil, and at this time, the maximum output voltage or the maximum output power can be set to a larger value, so that the power supply module 1 can output a larger power to push the power receiving module located farther.
It should be noted that the present invention can determine whether the power receiving module enters the power supply range thereof and the distance between the power receiving module and the power supply module by detecting the self-resonant frequency of the power supply coil, and accordingly select the appropriate output power to transmit the start signal and set the appropriate maximum output power. Those skilled in the art can make modifications or changes thereto without being limited thereto. For example, in the detection process 30, the processor 111 may first determine whether the self-resonant frequency stops changing for a period of time, and control the power coil 116 to send the start signal after confirming that the self-resonant frequency does not change for a period of time. However, in other embodiments, to speed up the detection of the power receiving end, the processor 111 may also drive the power supply coil 116 to send the start signal when detecting the drop of the self-resonant frequency and determining that the power receiving module enters the coil sensing range of the power supply module 1. In addition, in the embodiment of the present invention, it is one of the main technical features to determine the distance between the power supplying terminal and the power receiving terminal, wherein the power supplying terminal may represent a power supplying coil or a power supplying module, and the power receiving terminal may represent a power receiving coil or a power receiving module. That is, the distance determined by the present invention may be a distance between the power supply module and the power receiving module, a distance between the power supply coil and the power receiving coil, a distance between the power supply coil and the power receiving module, or a distance between the power supply module and the power receiving coil. The above names are used interchangeably in this specification and all can be replaced with each other, and the above distances can all correspond to the self-resonant frequency of the power supply coil, so as to be used as the basis for detecting the power receiving end and setting the output power.
Besides, in the embodiment of the present invention, the coil output power (including the maximum output power) can also be regarded as the coil output voltage. It will be appreciated by those skilled in the art that the coil output voltage and the output power are positively correlated, i.e., a greater coil output voltage represents a greater coil output power. Therefore, the setting of the coil output voltage can be regarded as the setting of the coil output power. In addition, in the learning mode, the corresponding operating frequencies can be obtained under no load and full load, respectively, as shown in table 1. It should be noted that, in the actual operation of the inductive power supply, the coil output voltage may be affected by the load condition, and the operating frequency may reflect the magnitude of the output power, in this case, the maximum and minimum values of the output power may be controlled by using the no-load and full-load operating frequencies of the inductive power supply as the upper and lower limits. As illustrated in Table 1, if the detected self-resonant frequency is 140kHz, the upper limit of the operating frequency can be set to 170kHz (no-load operating frequency) and the lower limit of the operating frequency can be set to 150kHz (full-load operating frequency). That is, the processor 111 can control the operating frequency of the power supply coil 116 between 150kHz and 170kHz, thereby controlling the output voltage of the power supply coil 116 to fall within a range between 90V and 140V.
Therefore, the invention can obtain the no-load and full-load output voltages and/or the corresponding operating frequencies of the power receiving module under different positions in the learning mode and store the no-load and full-load output voltages and/or the corresponding operating frequencies in the memory. Therefore, the power supply module can acquire the position of the power receiving module by detecting the self-resonant frequency of the coil and set the output power according to the position. Compared with the prior art that the power supply module cannot know the position of the power receiving module, the power supply module can detect the distance between the power receiving module and the power receiving module, and further control the power supply coil to send the starting signal with the proper output power.
In summary, the present invention can determine whether the power receiving module enters the power supply range and the distance between the power receiving module and the power supply module by detecting the self-resonant frequency of the power supply coil. The power supply module can obtain the basic frequency in the learning mode, and obtain the no-load and full-load output voltages and/or the corresponding operating frequencies of the power receiving module under different positions according to the self-resonant frequency. In the operation process, the power supply module judges whether the power receiving module exists in the coil induction range according to whether the detected self-resonant frequency is smaller than the basic frequency, and the power loss and the electromagnetic interference generated by the judgment mode are extremely low. When the power receiving module is detected, the power supply module can judge the distance between the power receiving module and the power supply module according to the self-resonant frequency, so as to control the power supply coil to send a starting signal with proper output power and set the proper maximum output power. Therefore, the invention can effectively control the output power of the power supply coil, so as to avoid the problem that the power receiving end device is burnt due to overlarge output power of the coil when the power receiving module is close to the power receiving module, and simultaneously avoid the problem that the power receiving end device cannot be effectively detected when the power receiving module is far from the power receiving module.
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 (20)
1. A method for detecting a power receiving module of an inductive power supply, the power receiving module including a power coil, the method comprising:
detecting the power supply coil to obtain a self-resonant frequency of the power supply coil;
judging whether the self-resonance frequency is less than a basic frequency;
when the self-resonant frequency is judged to be smaller than the basic frequency and the amplitude smaller than the basic frequency exceeds a critical value, acquiring first output power corresponding to the self-resonant frequency; and
a start signal is transmitted through the first output power, and power supply is started when a data code corresponding to the start signal is received.
2. The method of claim 1, further comprising initiating a learning mode and performing the following steps in the learning mode:
when no object is placed in a coil induction range of the power supply coil, the self-resonant frequency of the power supply coil is obtained, and the self-resonant frequency is stored as the fundamental frequency.
3. The method as claimed in claim 2, wherein in the learning mode, when the power receiving module is disposed in the coil sensing range of the power supply coil and the power receiving module is set to be idle, the following steps are further performed:
when the power receiving module is positioned at different positions in the coil induction range, the power receiving module is respectively powered, and at least one of the self-resonant frequency of the power supply coil and an operation frequency and a no-load output voltage of the power supply coil is measured; and
and corresponding the self-resonant frequency obtained at each position to the operating frequency or the no-load output voltage, and storing the corresponding relation.
4. The method of claim 3, wherein the step of obtaining the first output power corresponding to the self-resonant frequency comprises:
the no-load output voltage corresponding to the self-resonant frequency is obtained, and the first output power is set according to the no-load output voltage.
5. The method of claim 2, wherein in the learning mode, when the power receiving module is disposed in the coil sensing range of the power supply coil and the power receiving module is set to be fully loaded, the following steps are further performed:
when the power receiving module is positioned at different positions in the coil induction range, the power receiving module is respectively supplied with power, and at least one of the self-resonance frequency of the power supply coil and the operating frequency and full-load output voltage of the power supply coil is measured; and
and corresponding the self-resonant frequency obtained from each position to the operating frequency or the full-load output voltage, and storing the corresponding relation.
6. The method of claim 5, further comprising:
and obtaining the corresponding full-load output voltage according to the self-resonant frequency measured in the operation of the power supply coil, and setting the maximum output power of the power supply coil according to the full-load output voltage.
7. The method of claim 1, wherein when the power module does not receive the data code corresponding to the activation signal, performing the following steps:
resending the start signal;
stopping sending the starting signal when the number of sending the starting signal reaches a specific number and the data code is not received, and detecting the self-resonant frequency of the power supply coil; and
re-executing the steps of claim 1 when detecting the change in the self-resonant frequency of the power supply coil.
8. The method of claim 1, wherein the power coil is powered by the first output power when the data code corresponding to the start signal is received.
9. The method of claim 1, wherein the step of obtaining the first output power corresponding to the self-resonant frequency is performed after the self-resonant frequency stops changing for a period of time.
10. The method of claim 1, further comprising:
when the self-resonant frequency is judged to be close to or larger than the basic frequency, the power supply is stopped.
11. A power supply module for an inductive power supply for detecting a power receiving module of the inductive power supply, the power supply module comprising:
a power supply coil; and
a processor configured to perform the steps of:
detecting the power supply coil to obtain a self-resonant frequency of the power supply coil;
judging whether the self-resonance frequency is less than a basic frequency;
when the self-resonant frequency is judged to be smaller than the basic frequency and the amplitude smaller than the basic frequency exceeds a critical value, acquiring first output power corresponding to the self-resonant frequency; and
the power supply coil is controlled to send a starting signal through the first output power, and when a data code corresponding to the starting signal is received, the power supply coil is controlled to start to supply power.
12. The power module of claim 11 further comprising a memory, wherein the processor further initiates a learn mode and performs the following steps in the learn mode:
when no object is placed in a coil induction range of the power supply coil, the self-resonant frequency of the power supply coil is obtained, and the self-resonant frequency is stored in the memory as the basic frequency.
13. The power supply module of claim 12, wherein in the learning mode, when the power receiving module is disposed in the coil sensing range of the power supply coil and the power receiving module is set to be idle, the processor further performs the following steps:
when the power receiving module is positioned at different positions in the coil induction range, the power receiving module is respectively powered, and at least one of the self-resonant frequency of the power supply coil and an operation frequency and a no-load output voltage of the power supply coil is measured; and
and corresponding the self-resonant frequency obtained at each position to the operating frequency or the no-load output voltage, and storing the corresponding relation in the memory.
14. The power supply module of claim 13 wherein the step of obtaining the first output power corresponding to the self-resonant frequency comprises:
the no-load output voltage corresponding to the self-resonant frequency is obtained, and the first output power is set according to the no-load output voltage.
15. The power supply module of claim 12 wherein in the learning mode, when the powered module is disposed within the coil sensing range of the power supply coil and the powered module is set to full load, the processor further performs the following steps:
when the power receiving module is positioned at different positions in the coil induction range, the power receiving module is respectively supplied with power, and at least one of the self-resonance frequency of the power supply coil and the operating frequency and full-load output voltage of the power supply coil is measured; and
the self-resonant frequency obtained from each position is corresponding to the operating frequency or the full-load output voltage, and the corresponding relation is stored in the memory.
16. The power module of claim 15 wherein the processor further performs the steps of: and obtaining the corresponding full-load output voltage according to the self-resonant frequency measured in the operation of the power supply coil, and setting the maximum output power of the power supply coil according to the full-load output voltage.
17. The power supply module of claim 11, wherein when the power supply module does not receive the data code corresponding to the activation signal, the processor performs the following steps:
resending the start signal;
stopping sending the starting signal when the number of sending the starting signal reaches a specific number and the data code is not received, and detecting the self-resonant frequency of the power supply coil; and
re-executing the steps of claim 11 when detecting the change in the self-resonant frequency of the power supply coil.
18. The power supply module of claim 11 wherein the power supply coil supplies power through the first output power upon receiving the data code corresponding to the start signal.
19. The power supply module of claim 11 wherein the step of obtaining the first output power corresponding to the resonant frequency is performed after the resonant frequency stops changing for a period of time.
20. The power module of claim 11 wherein the processor further performs the steps of: and controlling the power supply coil to stop supplying power when the self-resonant frequency is judged to be close to or larger than the basic frequency.
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