Clock synchronization-based dynamic wireless charging system efficiency calculation method and system

Abstract

The application relates to the technical field of wireless power transmission, and particularly discloses a dynamic wireless charging system efficiency calculation method and system based on clock synchronization, which is characterized in that a satellite tamed clock is arranged at each of a transmitting end and a receiving end, a first frequency and a second frequency pulse signal and a timestamp signal are generated through the satellite tamed clock, when the control unit of the receiving end or the transmitting end receives the first frequency pulse signal, the second frequency pulse signal is used to start counting, when the count reaches a preset value, the average power of the sampling voltage and the sampling current in the preset value is calculated, and the average power is labeled with a timestamp according to the timestamp signal, when the timestamp labels of the transmitting end and the receiving end are the same, the system efficiency corresponding to the moment is calculated according to the power of the transmitting end and the receiving end. The method and the system use the satellite tamed clock to realize time synchronization of the transmitting end and the receiving end, can accurately calculate the system efficiency, and have a low error.

Description

Technical Field

[0001] This invention relates to the field of wireless power transmission technology, and in particular to a method and system for calculating the efficiency of a dynamic wireless charging system based on clock synchronization. Background Technology

[0002] Over the past decade, many mobile electrical devices (such as electric vehicles, rail vehicles, and warehouse robots) have relied on plug-in charging and battery charging, severely limiting their range and intelligence. Furthermore, contact charging suffers from issues like easily worn plugs and low safety. Wireless Power Transfer (WPT) technology offers significant advantages over traditional plug-in charging. However, in EV-DWPT (Dynamic Wireless Charging), the transmitting coil is constantly changing due to rail switching, and a wired connection between the transmitter and receiver is impossible. This inability to synchronize the wireless transmission clock during efficiency calculations leads to values ​​greater than one or close to zero. Summary of the Invention

[0003] This invention provides a method and system for calculating the efficiency of a dynamic wireless charging system based on clock synchronization. The technical problem it solves is: how to achieve clock synchronization between the transmitter and receiver in order to accurately calculate the system efficiency.

[0004] This invention provides a method for calculating the efficiency of a clock-synchronized dynamic wireless charging system. The dynamic wireless charging system includes a receiver and a multi-rail transmitter, and includes the following steps:

[0005] The output current and output voltage of the receiving end are sampled;

[0006] A first pulse signal of a first frequency, a second pulse signal of a second frequency, and a first timestamp signal are generated by a first satellite discipline clock. When the receiving end control unit receives the first pulse signal, it starts counting according to the second pulse signal to obtain the output current and output voltage of the receiving end, and marks the output current and output voltage of the receiving end that have reached the pre-designed value with the first timestamp signal.

[0007] The average power of the receiver tagged with the first timestamp is calculated based on the output current and output voltage of the receiver that have reached the pre-designed values.

[0008] The average power of the transmitter is calculated using the same procedure as that used to calculate the average power of the receiver.

[0009] The system efficiency corresponding to the same timestamp tag is calculated based on the average power of the transmitter and the average power of the receiver, which have the same timestamp tag.

[0010] Furthermore, the calculation of the average power of the transmitting end using the same process as calculating the average power of the receiving end specifically includes the following steps:

[0011] The input current and input voltage of the transmitting end are sampled;

[0012] A third pulse signal at the first frequency, a fourth pulse signal at the second frequency, and a second timestamp signal are generated by a second satellite discipline clock. When the transmitter control unit receives the third pulse signal, it starts counting based on the fourth pulse signal to obtain the input current and input voltage of the transmitter, and adds a second timestamp tag to the input current and input voltage of the transmitter that have reached the pre-designed value using the second timestamp signal.

[0013] The average power of the transmitter, tagged with the second timestamp, is calculated based on the input current and input voltage of the transmitter, which are within the pre-designed values.

[0014] Further, the step of calculating the average power of the receiver tagged with the first timestamp based on the output current and output voltage of the receiver reaching the pre-designed value specifically involves:

[0015] Calculate the output power once for the output current and output voltage of the receiving end for each sampling count within the pre-designed value;

[0016] The average power of the receiver tagged with the first timestamp is obtained by taking the arithmetic mean of all output power within the pre-designed value.

[0017] Further, the step of calculating the average power of the transmitter tagged with the second timestamp based on the input current and input voltage of the transmitter reaching the pre-designed value specifically involves:

[0018] For each sample count within the pre-designed values, the input power of the transmitter is calculated once based on the input current and input voltage.

[0019] The average power of the transmitter, tagged with the second timestamp, is obtained by taking the arithmetic mean of all input power within the pre-designed values.

[0020] Furthermore, when the pre-designed value is reached once, the average power of the transmitting end and the average power of the receiving end are calculated once.

[0021] The first frequency and the second frequency satisfy the condition that the first frequency is divisible by the second frequency.

[0022] This invention also provides a clock-synchronized dynamic wireless charging system efficiency calculation system. The key features of the clock-synchronized dynamic wireless charging system efficiency calculation method described above are: a receiver sampling module, a receiver power calculation module, a transmitter sampling module, a transmitter power calculation module, and an efficiency calculation module; the receiver power calculation module includes a receiver control unit and a first satellite discipline clock and a receiver wireless communication unit connected to the receiver control unit.

[0023] The receiving end sampling module is used to sample the output current and output voltage of the receiving end;

[0024] The first satellite discipline clock is used to generate a first pulse signal at a first frequency, a second pulse signal at a second frequency, and a first timestamp signal, and send them to the receiving end control unit.

[0025] When the receiving end control unit receives the first pulse signal, it starts counting according to the second pulse signal to obtain the output current and output voltage of the receiving end, and marks the output current and output voltage of the receiving end that have reached the pre-design value with the first timestamp signal; the receiving end control unit also calculates the average power of the receiving end marked with the first timestamp based on the output current and output voltage of the receiving end that have reached the pre-design value, and sends it to the efficiency calculation module through the receiving end wireless communication unit;

[0026] The transmitter sampling module is used to sample the input current and input voltage of the transmitter.

[0027] The transmitting power calculation module and the receiving power calculation module are configured to calculate the average power of the transmitting end using the same process as the receiving power calculation module and send it to the efficiency calculation module.

[0028] The efficiency calculation module is used to calculate the system efficiency corresponding to the same timestamp tag based on the average power of the transmitter and the average power of the receiver with the same timestamp tag.

[0029] Preferably, the transmitter power calculation module includes a transmitter control unit and a second satellite discipline clock and a transmitter wireless communication unit connected to the transmitter control unit;

[0030] The second satellite discipline clock is used to generate a third pulse signal at the first frequency, a fourth pulse signal at the second frequency, and a second timestamp signal, and send them to the transmitter control unit.

[0031] When the transmitter control unit receives the third pulse signal, it starts counting based on the fourth pulse signal to obtain the input current and input voltage of the transmitter, and adds a second timestamp tag to the input current and input voltage of the transmitter that reach the pre-design value using the second timestamp signal; the transmitter control unit also calculates the average power of the transmitter with the second timestamp tag based on the input current and input voltage of the transmitter that reach the pre-design value, and sends it to the efficiency calculation module through the transmitter wireless communication unit.

[0032] Preferably, the receiving end control unit calculates the average power of the receiving end tagged with the first timestamp based on the output current and output voltage of the receiving end reaching the pre-designed value, specifically as follows:

[0033] Calculate the output power once for the output current and output voltage of the receiving end for each sampling count within the pre-designed value;

[0034] The average power of the receiver tagged with the first timestamp is obtained by taking the arithmetic mean of all output power within the pre-designed value.

[0035] The transmitter control unit calculates the average power of the transmitter, tagged with the second timestamp, based on the input current and input voltage of the transmitter, which are within the pre-designed values. Specifically:

[0036] For each sample count within the pre-designed values, the input power of the transmitter is calculated once based on the input current and input voltage.

[0037] The average power of the transmitter, tagged with the second timestamp, is obtained by taking the arithmetic mean of all input power within the pre-designed values.

[0038] Preferably, the receiver control unit calculates the average power of the transmitter once when the count reaches the pre-designed value once; the transmitter control unit calculates the average power of the receiver once when the count reaches the pre-designed value once; the first frequency and the second frequency satisfy the condition that the first frequency is divisible by the second frequency.

[0039] Preferably, the transmitting end includes a DC bus and multiple high-frequency inverter circuits connected in parallel to the DC bus, as well as multiple transmitting end resonant circuits connected one-to-one with the multiple high-frequency inverter circuits. Each transmitting end resonant circuit includes a transmitting end compensation network and a transmitting coil. A switching switch is connected between the DC power supply and each transmitting coil. The receiving end includes a receiving coil, a receiving end compensation network, a power conversion circuit, and a battery pack connected in sequence. The sampling point of the receiving end sampling module is located between the power conversion circuit and the battery pack. The sampling point of the transmitting end sampling module is located on the DC bus.

[0040] The present invention provides a method and system for calculating the efficiency of a dynamic wireless charging system based on clock synchronization. It sets a satellite disciplined clock at both the transmitting and receiving ends, generating three signals: pulse signals at a first frequency and a second frequency, and a timestamp signal. When the control unit at the receiving or transmitting end receives the pulse signal at the first frequency, it begins counting using the pulse signal at the second frequency. When the count reaches a pre-designed value, the average power of the sampled voltage and sampled current within the pre-designed value is calculated, and a timestamp is added to this average power based on the timestamp signal. When the timestamps at the transmitting and receiving ends are identical, it indicates that the power at the receiving end and the power at the transmitting end under that label were sampled at the same time. The system efficiency at that time is then calculated based on the power at both the transmitting and receiving ends.

[0041] This method and system utilize a satellite disciplined clock to achieve time synchronization between the transmitter and receiver, enabling accurate calculation of system efficiency with low error (within one percent). Moreover, compared to the expensive cost of large power analyzers, this invention is relatively inexpensive. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the interface of the satellite discipline clock provided in an embodiment of the present invention;

[0043] Figure 2 This is a comparison chart of indoor and outdoor frequency errors of the satellite disciplined clock provided in an embodiment of the present invention;

[0044] Figure 3 This is a circuit diagram of the dynamic wireless charging system provided in an embodiment of the present invention;

[0045] Figure 4 This is a structural diagram of the dynamic wireless charging system provided in an embodiment of the present invention;

[0046] Figure 5 This is a circuit diagram of a dynamic wireless charging system with only one set of transmitting coils coupled to receiving coils, provided in an embodiment of the present invention.

[0047] Figure 6This is a flowchart of the method for calculating the efficiency of a dynamic wireless charging system based on clock synchronization, provided in an embodiment of the present invention.

[0048] Figure 7 This is a structural diagram of the efficiency calculation system for a dynamic wireless charging system based on clock synchronization provided in an embodiment of the present invention;

[0049] Figure 8 This is a comparison chart of the input power obtained from experiments provided in the embodiments of the present invention;

[0050] Figure 9 This is a comparison chart of the output power obtained from experiments provided in the embodiments of the present invention;

[0051] Figure 10 This is a comparison chart of the efficiency obtained from experiments provided in the embodiments of the present invention. Detailed Implementation

[0052] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. The embodiments are given for illustrative purposes only and should not be construed as limiting the present invention. The accompanying drawings are for reference and illustration only and do not constitute a limitation on the scope of patent protection of the present invention, because many changes can be made to the present invention without departing from the spirit and scope of the present invention.

[0053] Example 1

[0054] A satellite disciplined clock synchronization system is a system that calibrates its own clock. Its working principle is to receive navigation satellite signals for timing and correct the local clock accordingly. The system compares a received fixed-frequency signal with the oscillation signal generated by a local oscillator to obtain the frequency difference, and then adjusts the local oscillator to bring its frequency close to the satellite's frequency. During frequency adjustment, phase compensation of the local oscillator is also required to ensure that the time signal output by the local oscillator and the signal output by the receiver maintain a difference within a certain range.

[0055] Satellite-disciplined clock systems are typically used to provide a clock source for local systems. Satellite timing receivers recover the navigation satellite system time by capturing and tracking navigation satellite signals and using correlation peaks for time delay compensation.

[0056] To prevent time discrepancies and reduce costs, this invention selects a disciplined clock from satellite communication as the time synchronization module. Figure 1 The diagram shows an interface of a satellite disciplined clock, where the GPS ANT port is connected to the GPS antenna to receive navigation satellite signals; the RS232 serial port is used to send serial signals; the 1PPS port and the 10MHz port are used to send 1Hz and 10MHz pulse signals, respectively; and finally, the power connection port is used to connect to the power supply. Figure 1The pulse frequency of the satellite discipline clock shown is fixed at 10MHz or 1Hz. When it outputs second pulses to both the transmitter and receiver simultaneously, it can be used for timestamp synchronization.

[0057] However, outputting pulses at the same frequency is still insufficient; it is currently impossible to align the start time. Therefore, a fixed timestamp is still needed as the starting point. The satellite discipline clock also has the function of outputting a TOD (Time of Day) signal via the RS232 serial port as shown in the figure. Regular users typically obtain accurate time information from the carrier device via the 1PPS+TOD protocol. The TOD message baud rate is 9600 by default, with no parity check, one start bit (represented by a low level), one stop bit (represented by a high level), and an idle frame is high. It contains 8 data bits. This TOD message indicates the current 1PPS trigger rise edge time. The TOD protocol message is sent once per second. The TOD signal contains the year, month, day, hour, minute, second, and latitude and longitude of the location, which can be used as the starting point for signal statistics during transmission and reception.

[0058] Since satellite disciplined clocks require an antenna and perform better outdoors than indoors where satellite signals are weaker, and considering the mobile testing of electric vehicles, indoor and outdoor error tests were conducted first. Two satellite disciplined clocks were provided, and their errors were observed when both were connected to the same oscilloscope. Figure 2 As shown, the upper left represents the indoor 1Hz pulse test, and the upper right represents the indoor 10MHz pulse test; the lower left represents the outdoor 1Hz pulse test, and the lower right represents the outdoor 10MHz pulse test. From Figure 2 It is evident that the indoor 1Hz pulse test error is 124ms, while the outdoor 1Hz pulse test error is virtually negligible; the indoor 10MHz pulse test error is 8.4ns, while the outdoor 10MHz pulse test error is 5ns. This indicates that the satellite discipline clock error is larger indoors and smaller and negligible outdoors. Therefore, the 10MHz pulse can be used to measure the signal, while the 1Hz pulse can be used as a marker.

[0059] A typical circuit of a dynamic wireless charging system is as follows: Figure 3 As shown, it includes a receiver and a multi-rail transmitter. The transmitter includes a DC bus (using a DC power supply U). dc The equivalent, corresponding DC current is I. dc ) and n≥2 high-frequency inverter circuits connected in parallel to the DC bus (a full-bridge inverter consisting of four MOSFETs, including Q 11 To Q 4n ), and multiple transmitter resonant circuits connected one-to-one with n high-frequency inverter circuits, each transmitter resonant circuit including a transmitter compensation network and a transmitter coil (LPi Its current is expressed as I Pi Its internal resistance is expressed as R. LPi (i = 1, 2, ..., n), a switching switch is connected between the DC power supply and each transmitting coil. The receiving end includes sequentially connected receiving coils (L... S Its current is expressed as I S Its internal resistance is expressed as R. LS ), receiver compensation network, power conversion circuit (including a rectifier consisting of four diodes D1 to D4 and a filter capacitor C) d The input voltage and current of the power conversion circuit are expressed as U. S ) and battery pack (with load resistor R) L Equivalently, its voltage is U L The current is i L As an example, the dynamic wireless charging system provided in this embodiment adopts an LCC-S type compensation topology, that is, the transmitter resonant network consists of an inductor (L... fi Let i = 1, 2, ..., n, and its internal resistance be expressed as R. Lfi ), and a parallel compensation capacitor (C) fi (i = 1, 2, ..., n) and a series compensation capacitor (C) Pi The receiver resonant network consists of (i = 1, 2, ..., n) and uses a series compensation capacitor C. S The output voltage and current of a high-frequency inverter circuit are expressed as U. ini and I ini , i = 1, 2, ..., n. M1 to M n Indicates transmitting coil L P1 To L Pn With receiving coil L S Mutual intuition between them, R eq This is the equivalent load.

[0060] Figure 3 The corresponding structure diagram of the dynamic wireless charging system is as follows: Figure 4 As shown. A switch is used to switch between different transmitting coils to power the receiving coil. When only one set of transmitting coils is coupled to the receiving coil, Figure 3 The circuit shown can be equivalent to Figure 5 , where: U in =U ini I T =I ini Q1 = Q 1i Q2 = Q 2i Q3 = Q 3i Q4 = Q 4i L f =L fi R Lf=R Lfi C f =C fi C P =C Pi L P =L Pi I P =I Pi M = M i , i = 1, 2, ..., n.

[0061] Let the receiving impedance be Z. S , which is:

[0062]

[0063] According to the reflection impedance theorem, the reflection impedance Z can be obtained. r for:

[0064]

[0065] Then the emission impedance Z P for:

[0066]

[0067] To achieve perfect resonance, the imaginary part of the transmitting impedance should be zero, then Z P It should meet the following requirements:

[0068]

[0069] In this example, L is set. P =L S =100μF, L f =10μF, therefore C can be calculated. f C P C S The corresponding value. Based on the power calculation principle, the output power can be obtained as:

[0070] P in =U dc I dc

[0071] The output power is the power at both ends of the load, i.e.:

[0072] P out =U L i L

[0073] Therefore, the efficiency is:

[0074]

[0075] Based on the above analysis, embodiments of the present invention provide a method for calculating the efficiency of a dynamic wireless charging system based on clock synchronization, such as... Figure 5 As shown in the flowchart, the method includes:

[0076] The output current and output voltage of the receiving end are sampled;

[0077] The first satellite discipline clock generates a first pulse signal at a first frequency, a second pulse signal at a second frequency, and a first timestamp signal (also known as a TOD signal). When the receiving end control unit receives the first pulse signal, it starts counting based on the second pulse signal to obtain the output current and output voltage of the receiving end, and uses the first timestamp signal to mark the output current and output voltage of the receiving end that have reached the pre-designed values ​​(the timestamp tag is also known as a TOD tag).

[0078] The average power of the receiver, marked with the first timestamp, is calculated based on the output current and output voltage of the receiver that have reached the pre-designed values.

[0079] The average power of the transmitter is calculated using the same procedure as that used to calculate the average power of the receiver.

[0080] The system efficiency corresponding to the same timestamp label is calculated based on the average power of the transmitter and the average power of the receiver with the same timestamp label.

[0081] Sampling points at the receiving end (e.g.) Figure 3 , Figure 4 The T shown P3 and T P4 It is positioned between the power conversion circuit and the battery pack to sample the load resistance R. L voltage U L and current i L Sampling points at the transmitting end (e.g.) Figure 3 , Figure 4 The T shown P1 and T P2 The transmitter coil is positioned on the DC bus. Because the guide rails constantly switch during vehicle wireless charging, and the transmitting coil is always in a switching state, it is difficult to directly measure the voltage and current values ​​after inversion. Therefore, the DC terminal voltage and current, U, are measured instead. dc and I dc .

[0082] The average power of the transmitter is calculated using the same process as that used to calculate the average power of the receiver, specifically including the following steps:

[0083] The input current and input voltage at the transmitting end are sampled;

[0084] The second satellite discipline clock generates a third pulse signal at a first frequency, a fourth pulse signal at a second frequency, and a second timestamp signal. When the transmitter control unit receives the third pulse signal, it starts counting based on the fourth pulse signal to obtain the transmitter's input current and input voltage, and uses the second timestamp signal to tag the transmitter's input current and input voltage that have reached the pre-designed values.

[0085] The average power of the transmitter, marked with a second timestamp, is calculated based on the input current and input voltage of the transmitter, which are within the pre-design values.

[0086] The average power of the receiver, tagged with the first timestamp, is calculated based on the output current and output voltage of the receiver, which are within the pre-designed values. Specifically:

[0087] Calculate the output power once for each sampling count at the receiver within the pre-designed value range, based on the output current and output voltage.

[0088] The average power of the receiver with the first timestamp is obtained by averaging all the output power within the pre-designed values.

[0089] The average power of the transmitter, marked with the second timestamp, is calculated based on the input current and input voltage of the transmitter, which are within the pre-design values. Specifically:

[0090] Calculate the input power once for each sampling count of the transmitter's input current and input voltage within the pre-designed value range;

[0091] The average power of the transmitter, tagged with the second timestamp, is obtained by averaging all input power within the pre-designed values.

[0092] As a specific example, the first frequency is 1Hz and the second frequency is 10MHz.

[0093] Since the satellite discipline clock simultaneously transmits a 1PPS (1Hz) pulse signal and a 10MHz pulse signal, and especially a TOD (Transmission of Delay) signal transmitted synchronously with the 1Hz signal (the TOD signal reception has a delay, averaging less than 0.5s), a "tag" can be attached to the previously received 1Hz signal via the TOD serial port signal. When a 1Hz signal is received, a 10MHz pulse signal counter is started simultaneously. The average power calculation frequency is determined, i.e., after how many 10MHz pulse signals are received, the power signal obtained during the previous counting period is calculated, stored, and the power signal of the previous sampling circuit is cleared. Sampling starts again, and the cycle repeats. When the next 1Hz signal is received, the previously stored average power value and the TOD signal tag for this period are wirelessly transmitted to the host receiver. This cycle continues, assigning a new tag to each new 1Hz signal and starting a new 10MHz calculation. Therefore, the chosen frequency is best if it is divisible by 10MHz.

[0094] Finally, the asynchronous communication signals transmitted by the transmitter and receiver are obtained, which are average power measurements of the TOD signal tags. Further comparison is made between the TOD signal tags. If the tag signals of the receiver and transmitter are the same, efficiency calculations are performed on their corresponding signals. If the tag signals are different, they are stored and compared again when the next average power value of the tag signal is transmitted. This prevents time errors in wireless signal transmission and ultimately achieves synchronization of efficiency calculations due to asynchronous communication.

[0095] In summary, this invention provides a method for calculating the efficiency of a dynamic wireless charging system based on clock synchronization. A satellite-disciplined clock is set at both the transmitting and receiving ends. Three signals are generated by the satellite-disciplined clock: pulse signals at a first frequency and a second frequency, and a timestamp signal. When the control unit at the receiving or transmitting end receives the pulse signal at the first frequency, it begins counting using the pulse signal at the second frequency. When the count reaches a preset value, the average power of the sampled voltage and sampled current within the preset value is calculated, and a timestamp is added to this average power. When the timestamps at the transmitting and receiving ends are the same, it means that the power at the receiving end and the power at the transmitting end under that tag were sampled at the same time. The system efficiency at that time is then calculated based on the power at the transmitting and receiving ends. This method and system utilize a satellite-disciplined clock to achieve time synchronization between the transmitting and receiving ends, enabling accurate calculation of system efficiency.

[0096] Example 2

[0097] To facilitate the implementation of the clock-synchronized dynamic wireless charging system efficiency calculation method provided in the embodiments, this embodiment provides a clock-synchronized dynamic wireless charging system efficiency calculation system, such as... Figure 6 As shown, it includes a receiver sampling module, a receiver power calculation module, a transmitter sampling module, a transmitter power calculation module, and an efficiency calculation module.

[0098] The receiver power calculation module includes a receiver control unit and a first satellite discipline clock and a receiver wireless communication unit connected to the receiver control unit;

[0099] The receiving end sampling module is used to sample the output current and output voltage of the receiving end;

[0100] The first satellite discipline clock is used to generate a first pulse signal at a first frequency, a second pulse signal at a second frequency, and a first timestamp signal, and send them to the receiving control unit.

[0101] When the receiving end control unit receives the first pulse signal, it starts counting based on the second pulse signal to obtain the output current and output voltage of the receiving end, and marks the output current and output voltage of the receiving end that have reached the preset value with the first timestamp signal; the receiving end control unit also calculates the average power of the receiving end marked with the first timestamp based on the output current and output voltage of the receiving end that have reached the preset value, and sends it to the efficiency calculation module through the receiving end wireless communication unit.

[0102] The transmitter sampling module is used to sample the input current and input voltage of the transmitter.

[0103] The transmitter power calculation module and the receiver power calculation module have the same settings. They are used to calculate the average power of the transmitter using the same process as the receiver power calculation module and send it to the efficiency calculation module.

[0104] The efficiency calculation module is used to calculate the system efficiency corresponding to the same timestamp tag based on the average power of the transmitter and the average power of the receiver with the same timestamp tag.

[0105] like Figure 6 As shown, the transmitter power calculation module includes a transmitter control unit, a second satellite discipline clock connected to the transmitter control unit, and a transmitter wireless communication unit.

[0106] The second satellite discipline clock is used to generate a third pulse signal at a first frequency, a fourth pulse signal at a second frequency, and a second timestamp signal, and send them to the transmitter control unit.

[0107] When the transmitter control unit receives the third pulse signal, it starts counting based on the fourth pulse signal to obtain the input current and input voltage of the transmitter. It then uses the second timestamp signal to tag the input current and input voltage of the transmitter that have reached the pre-designed values. The transmitter control unit also calculates the average power of the transmitter with the second timestamp tag based on the input current and input voltage of the transmitter that have reached the pre-designed values, and sends it to the efficiency calculation module through the transmitter wireless communication unit.

[0108] The receiver control unit calculates the average power of the receiver, marked with the first timestamp, based on the receiver's output current and output voltage, which are within the pre-designed values. Specifically:

[0109] Calculate the output power once for each sampling count at the receiver within the pre-designed value range, based on the output current and output voltage.

[0110] The average power of the receiver with the first timestamp is obtained by taking the arithmetic mean of all output power within the pre-designed values.

[0111] The transmitter control unit calculates the average power of the transmitter, marked with the second timestamp, based on the input current and input voltage of the transmitter, which are within the pre-designed values. Specifically:

[0112] Calculate the input power once for each sampling count of the transmitter's input current and input voltage within the pre-designed value range;

[0113] The average power of the transmitter, tagged with the second timestamp, is obtained by averaging all input power within the pre-designed values.

[0114] The receiver control unit calculates the average power of the transmitter once when the count reaches a pre-designed value; the transmitter control unit calculates the average power of the receiver once when the count reaches a pre-designed value; the first frequency and the second frequency satisfy the condition that the first frequency is divisible by the second frequency.

[0115] The receiving end sampling module has a current sampling circuit and a voltage sampling circuit. It is placed at the intermediate connection point between the battery pack and the power conversion module, and T is set. P3 and T P4 Two sampling points. These two sampling circuits sample the current and voltage signals between these two sampling points at a set sampling frequency to obtain the required power at the load end.

[0116] The receiver power calculation module uses an STM32 main control chip, which is directly connected to T P3 and T P4The sampling circuits at two sampling points obtain a series of voltage and current signals at the set frequency. After processing, these signals generate a series of power signals, which are stored in the STM32. Since the satellite discipline clock simultaneously transmits a 1PPS (1Hz) pulse signal and a 10MHz pulse signal, and especially a TOD (Transmission of Delay) signal transmitted synchronously with the 1Hz signal (with a reception delay averaging less than 0.5s), a "tag" can be attached to the previously received 1Hz signal via the TOD serial port signal. When a 1Hz signal is received, a 10MHz pulse signal counter is started simultaneously. The average power calculation frequency is determined, i.e., after how many 10MHz pulse signals are received, the power signals obtained during the previous counting period are calculated, arranged, and stored. The power signals from the previous sampling circuit are cleared, and sampling restarts, repeating the cycle. When the next 1Hz signal is received, the previously stored average power value and the TOD signal tag for this period are sent to the host receiver (efficiency calculation module) via the receiving end wireless communication unit (RS485 module). Then the cycle continues, giving a new label to the new 1Hz signal and starting a new 10MHz calculation. Therefore, the chosen frequency should ideally be divisible by 10MHz.

[0117] The transmitter is configured the same as the receiver. It also transmits the stored average power value and the TOD signal tag for this period to the host receiver via RS485 wireless serial communication. Its transmission frequency and average power calculation frequency are the same as those of the receiver's power measurement module.

[0118] The input power P can also be obtained by measuring the current and voltage on the DC bus. in Furthermore, the DC bus will not move, making measurement easier. Choose as follows: Figure 4 As shown, two sampling points T are set on both sides of the DC power supply. P1 and T P2 Similar to the receiving end, both sampling points are connected to voltage sampling circuits and circuit sampling circuits, and the voltage and current sampled are fed to the transmitting end power calculation module at the same frequency as the receiving end.

[0119] Finally, we will receive asynchronous communication signals from the two power calculation modules, which are average power measurements tagged with TOD signals, thus completing the efficiency calculation synchronization brought about by asynchronous communication.

[0120] Since the wireless charging platform for electric vehicles is mainly built using the LCC-S topology, according to Figure 3 Construct an LCC-S topology model, where the parameters are configured to allow the system to reach resonance, including the constant voltage power supply U. dc =200V, the stable frequency of the system is f=85kHz, ω=2πf.

[0121] The simulation did not consider its power loss, but for the system, the internal resistance R of the transmitting coil is... LP and the internal resistance R of the receiving coil LS and the internal resistance R of the power supply U The power loss of the component has the greatest impact on the system power loss.

[0122] Given the emission current I P For the internal resistance R of the transmitting coil LP Losses include:

[0123] P loss1 =I P 2 R LP

[0124] It is also known that the received current I S For the internal resistance R of the receiving coil S Losses include:

[0125] P loss2 =I S 2 R S

[0126] And we know the DC side current I dc For the internal resistance R of the power supply U Losses include:

[0127] P loss3 =I dc 2 R U

[0128] At this point, the system resistance loss should be:

[0129] P loss =P loss1 +P loss2 +P loss3

[0130] The experiment first sets up a clock synchronization system device, such as... Figure 7 As shown, it mainly consists of a microcontroller, a disciplined clock, and current and voltage sampling circuits. Based on the previous description, a test platform is built to measure the power and efficiency on both sides. The experiment is set up so that the power analyzer and clock synchronization system calculate the power and efficiency respectively when the receiver passes the guide rail.

[0131] Since the test vehicle moves at a constant speed, the input and output power and efficiency of the power analyzer and clock synchronization system can be obtained regarding the translation distance, such as... Figures 8 to 10 As shown.

[0132] Figure 8 For the input power comparison graph, from Figure 8 It can be seen that the error in input power is extremely small, only about 1%.

[0133] Figure 9 For the output power comparison chart, from Figure 9 It can be seen that the error in output power is extremely small, only about 1%.

[0134] Figure 10 For the efficiency comparison chart, from Figure 10 It can be seen that the efficiency error is extremely small, only about 1%.

[0135] comprehensive Figures 8 to 10 The errors in input power, output power, and efficiency are only about 1 percent, which can be ignored when considering experimental measurement errors.

[0136] In summary, this invention aims to measure the accurate real-time efficiency value of electric vehicles during dynamic wireless charging, and accurately measures the wireless dynamic efficiency value of electric vehicles within a 1% error range, offering the following significant advantages:

[0137] (1) It can be used for long-distance dynamic efficiency measurement;

[0138] (2) It uses a wireless connection and has a high real-time update rate;

[0139] (3) The error is low, within one percent;

[0140] (4) Compared to the expensive price of large power analyzers, the present invention is cheaper.

[0141] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for calculating the efficiency of a dynamic wireless charging system based on clock synchronization, wherein the dynamic wireless charging system includes a receiver and a multi-rail transmitter, characterized in that... Including the following steps: The output current and output voltage of the receiving end are sampled; A first pulse signal of a first frequency, a second pulse signal of a second frequency, and a first timestamp signal are generated by a first satellite discipline clock. When the receiving end control unit receives the first pulse signal, it starts counting according to the second pulse signal to obtain the output current and output voltage of the receiving end, and marks the output current and output voltage of the receiving end that have reached the pre-designed value with the first timestamp signal. The average power of the receiver tagged with the first timestamp is calculated based on the output current and output voltage of the receiver that have reached the pre-designed values. The average power of the transmitter is calculated using the same process as that used to calculate the average power of the receiver, specifically including the following steps: The input current and input voltage of the transmitting end are sampled; The third pulse signal at the first frequency, the fourth pulse signal at the second frequency, and the second timestamp signal are generated by the second satellite discipline clock. When the transmitter control unit receives the third pulse signal, it starts counting based on the fourth pulse signal to obtain the input current and input voltage of the transmitter, and adds a second timestamp tag to the input current and input voltage of the transmitter that have reached the pre-designed value through the second timestamp signal; The average power of the transmitter, tagged with the second timestamp, is calculated based on the input current and input voltage of the transmitter that have reached the pre-designed values. The system efficiency corresponding to the same timestamp tag is calculated based on the average power of the transmitter and the average power of the receiver, which have the same timestamp tag.

2. The method for calculating the efficiency of a dynamic wireless charging system based on clock synchronization according to claim 1, characterized in that, The calculation of the average power of the receiver tagged with the first timestamp based on the output current and output voltage of the receiver within the pre-designed value specifically involves: Calculate the output power once for the output current and output voltage of the receiving end for each sampling count within the pre-designed value; The average power of the receiver tagged with the first timestamp is obtained by taking the arithmetic mean of all output power within the pre-designed value.

3. The method for calculating the efficiency of a dynamic wireless charging system based on clock synchronization according to claim 2, characterized in that, The calculation of the average power of the transmitter, tagged with the second timestamp, based on the input current and input voltage of the transmitter within the pre-designed values ​​is specifically as follows: For each sample count within the pre-designed values, the input power of the transmitter is calculated once based on the input current and input voltage. The average power of the transmitter, tagged with the second timestamp, is obtained by taking the arithmetic mean of all input power within the pre-designed values.

4. The method for calculating the efficiency of a dynamic wireless charging system based on clock synchronization according to claim 3, characterized in that, When the pre-designed value is reached, calculate the average power of the transmitter and the average power of the receiver once. The first frequency and the second frequency satisfy the condition that the first frequency is divisible by the second frequency.

5. A clock-synchronized dynamic wireless charging system efficiency calculation system, using the clock-synchronized dynamic wireless charging system efficiency calculation method according to any one of claims 1 to 4, characterized in that: It includes a receiver sampling module, a receiver power calculation module, a transmitter sampling module, a transmitter power calculation module, and an efficiency calculation module; the receiver power calculation module is equipped with a receiver control unit and a first satellite discipline clock and a receiver wireless communication unit connected to the receiver control unit; The receiving end sampling module is used to sample the output current and output voltage of the receiving end; The first satellite discipline clock is used to generate a first pulse signal at a first frequency, a second pulse signal at a second frequency, and a first timestamp signal, and send them to the receiving end control unit. When the receiving end control unit receives the first pulse signal, it starts counting according to the second pulse signal to obtain the output current and output voltage of the receiving end, and marks the output current and output voltage of the receiving end that have reached the pre-design value with the first timestamp signal; the receiving end control unit also calculates the average power of the receiving end marked with the first timestamp based on the output current and output voltage of the receiving end that have reached the pre-design value, and sends it to the efficiency calculation module through the receiving end wireless communication unit; The transmitter sampling module is used to sample the input current and input voltage of the transmitter. The transmitting power calculation module and the receiving power calculation module are configured to calculate the average power of the transmitting end using the same process as the receiving power calculation module and send it to the efficiency calculation module. The transmitter power calculation module includes a transmitter control unit and a second satellite discipline clock and a transmitter wireless communication unit connected to the transmitter control unit. The second satellite discipline clock is used to generate a third pulse signal at the first frequency, a fourth pulse signal at the second frequency, and a second timestamp signal, and send them to the transmitter control unit. When the transmitter control unit receives the third pulse signal, it starts counting based on the fourth pulse signal to obtain the input current and input voltage of the transmitter, and adds a second timestamp tag to the input current and input voltage of the transmitter that reach the pre-design value using the second timestamp signal; the transmitter control unit also calculates the average power of the transmitter with the second timestamp tag based on the input current and input voltage of the transmitter that reach the pre-design value, and sends it to the efficiency calculation module through the transmitter wireless communication unit; The efficiency calculation module is used to calculate the system efficiency corresponding to the same timestamp tag based on the average power of the transmitter and the average power of the receiver with the same timestamp tag.

6. The efficiency calculation system for a dynamic wireless charging system based on clock synchronization according to claim 5, characterized in that: The receiving end control unit calculates the average power of the receiving end tagged with the first timestamp based on the output current and output voltage of the receiving end that reach the pre-designed value. Specifically: Calculate the output power once for the output current and output voltage of the receiving end for each sampling count within the pre-designed value; The average power of the receiver tagged with the first timestamp is obtained by taking the arithmetic mean of all output power within the pre-designed value. The transmitter control unit calculates the average power of the transmitter, tagged with the second timestamp, based on the input current and input voltage of the transmitter, which are within the pre-designed values. Specifically: For each sample count within the pre-designed values, the input power of the transmitter is calculated once based on the input current and input voltage. The average power of the transmitter, tagged with the second timestamp, is obtained by taking the arithmetic mean of all input power within the pre-designed value.

7. The efficiency calculation system for a dynamic wireless charging system based on clock synchronization according to claim 6, characterized in that: The receiver control unit calculates the average power of the transmitter once when the count reaches the pre-designed value; the transmitter control unit calculates the average power of the receiver once when the count reaches the pre-designed value; the first frequency and the second frequency satisfy the following condition: the first frequency is divisible by the second frequency.

8. The efficiency calculation system for a clock-synchronized dynamic wireless charging system according to any one of claims 5 to 7, characterized in that: The transmitting end includes a DC bus and multiple high-frequency inverter circuits connected in parallel to the DC bus, as well as multiple transmitting end resonant circuits connected one-to-one with the multiple high-frequency inverter circuits. Each transmitting end resonant circuit includes a transmitting end compensation network and a transmitting coil. A switching switch is connected between the DC bus and each transmitting coil. The receiving end includes a receiving coil, a receiving end compensation network, a power conversion circuit, and a battery pack connected in sequence. The sampling point of the receiving end sampling module is located between the power conversion circuit and the battery pack. The sampling point of the transmitting end sampling module is located on the DC bus.

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