Clock synchronization-based method and system for calculating efficiency of dynamic wireless charging system

Abstract

The present invention relates to the technical field of wireless power transfer. Specifically disclosed are a clock synchronization-based method and system for calculating the efficiency of a dynamic wireless charging system. The method comprises: providing a satellite-disciplined clock at both a transmitting end and a receiving end; generating pulse signals of a first frequency and a second frequency and timestamp signals by means of satellite-disciplined clocks; when a control unit of the receiving end / the transmitting end receives the pulse signal of the first frequency, starting counting on the basis of the pulse signal of the second frequency, when the count reaches a preset count value, calculating the average power of a sampled voltage and a sampled current within the preset count value, and marking the average power with a timestamp tag on the basis of the timestamp signal; and when timestamp tags of the transmitting end and the receiving end are the same, on the basis of the power of the transmitting end and the power of the receiving end, calculating the system efficiency corresponding to this moment. In the present method and system, by using the satellite-disciplined clocks to realize time synchronization between the transmitting end and the receiving end, system efficiency can be calculated with high accuracy and minimal error.

Description

A method and system for calculating the efficiency of a dynamic wireless charging system based on clock synchronization 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 (Electronic Electric Vehicle-Dual-Way 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 with 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 value, 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 value.

[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 value, 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 value.

[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] This invention provides a method and system for calculating the efficiency of a dynamic wireless charging system based on clock synchronization. It sets up a satellite-disciplined clock at both the transmitting and receiving ends. The satellite-disciplined clock generates 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. When the timestamps at the transmitting and receiving ends are the same, it means that the power at the receiving and transmitting ends under that tag was sampled at the same time. The system efficiency at that time is then calculated based on the power at both 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 with a low error (within one percent). Furthermore, compared to the expensive cost of large power analyzers, this invention is inexpensive. Attached Figure Description

[0041] Figure 1 is a schematic diagram of the interface of the satellite discipline clock provided in an embodiment of the present invention;

[0042] Figure 2 is a comparison chart of indoor and outdoor frequency errors of the satellite disciplined clock provided in an embodiment of the present invention;

[0043] Figure 3 is a circuit diagram of the dynamic wireless charging system provided in an embodiment of the present invention;

[0044] Figure 4 is a structural diagram of the dynamic wireless charging system provided in an embodiment of the present invention;

[0045] Figure 5 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;

[0046] Figure 6 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;

[0047] Figure 7 is a structural diagram of the efficiency calculation system of the dynamic wireless charging system based on clock synchronization provided in an embodiment of the present invention;

[0048] Figure 8 is a comparison chart of the input power obtained from the experiment provided in the embodiment of the present invention;

[0049] Figure 9 is a comparison chart of the output power obtained from the experiment provided in the embodiment of the present invention;

[0050] Figure 10 is a comparison chart of the experimental efficiencies provided in the embodiments of the present invention. Detailed Implementation

[0051] Example 1

[0052] 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.

[0053] 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.

[0054] To prevent time discrepancies and reduce costs, this invention selects a disciplined clock from satellite communication as the time synchronization module. Figure 1 shows a schematic diagram of the 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 the power supply. The pulse frequency of the satellite disciplined clock shown in Figure 1 is fixed at 10MHz or 1Hz. When it simultaneously outputs second pulses to both the transmitter and receiver, it can perform timestamp synchronization.

[0055] However, outputting pulses at the same frequency is still insufficient; the start time cannot be aligned. 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.

[0056] Since satellite disciplined clocks require an antenna connection 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 simultaneously connected to the same oscilloscope. As shown in Figure 2, 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. Figure 2 clearly shows that the indoor 1Hz pulse test error is 124ms, while the outdoor 1Hz pulse test has virtually no error; the indoor 10MHz pulse test error is 8.4ns, while the outdoor 10MHz pulse test error is 5ns. This indicates that the satellite disciplined 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 is used as a marker.

[0057] A typical circuit of a dynamic wireless charging system is shown in Figure 3. 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 (L Pi 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 IS 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.

[0058] The structural diagram of the dynamic wireless charging system corresponding to Figure 3 is shown in Figure 4. A switch is used to switch different transmitting coils to power the receiving coil. When only one set of transmitting coils is coupled to the receiving coil, the circuit shown in Figure 3 can be equivalent to the circuit in Figure 5, where: U in =U ini I T =I ini Q1=Q 1i Q 2 =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.

[0059] Let the receiving impedance be... , which is: According to the reflection impedance theorem, the reflection impedance can be obtained. for: Then the emission impedance for: To achieve perfect resonance, the imaginary part of the transmitting impedance should be zero. Should meet: This example is set up. , Therefore, it can be calculated that The corresponding value. Based on the power calculation principle, the output power can be obtained as: The output power is the power at both ends of the load, i.e.: Therefore, the efficiency is: .

[0060] Based on the above analysis, this embodiment of the invention provides a method for calculating the efficiency of a dynamic wireless charging system based on clock synchronization, as shown in the flowchart of Figure 5. The method includes:

[0061] The output current and output voltage of the receiving end are sampled;

[0062] 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) 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 timestamp tag is also known as a TOD tag).

[0063] 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.

[0064] The average power of the transmitter is calculated using the same procedure as that used to calculate the average power of the receiver.

[0065] 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.

[0066] The sampling points at the receiving end (as shown in Figures 3 and 4, T) 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 Land current i L The sampling points at the transmitting end (as shown in Figures 3 and 4, T) 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 .

[0067] 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:

[0068] The input current and input voltage at the transmitting end are sampled;

[0069] 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.

[0070] 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.

[0071] 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:

[0072] Calculate the output power once for the output current and output voltage of the receiver for each sampling count within the pre-designed values; calculate the arithmetic mean of all output powers within the pre-designed values ​​to obtain the average power of the receiver with the first timestamp tag.

[0073] 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:

[0074] Calculate the input power once for each sampling count of the transmitter's input current and input voltage within the pre-designed values; calculate the arithmetic mean of all input powers within the pre-designed values ​​to obtain the average power of the transmitter with the second timestamp tag.

[0075] As a specific example, the first frequency is 1Hz and the second frequency is 10MHz.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] Example 2

[0080] 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, as shown in Figure 6. This system 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 includes a receiver control unit and a first satellite disciplined clock and a receiver wireless communication unit connected to the receiver control unit. The receiver sampling module samples the output current and output voltage of the receiver. The first satellite disciplined clock generates a first pulse signal at a first frequency, a second pulse signal at a second frequency, and a first timestamp signal, and sends them to the receiver control unit. When the receiver 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 receiver, and uses the first timestamp signal to tag the output current and output voltage of the receiver that have reached the pre-designed values. The receiver control unit also calculates the average power of the receiver with the first timestamp tag based on the output current and output voltage of the receiver that have reached the pre-designed values, and sends this average power to the efficiency calculation module through the receiver wireless communication unit. The transmitter sampling module samples the input current and input voltage of the transmitter. The transmitter power calculation module has the same configuration as the receiver power calculation module, and calculates the average power of the transmitter using the same process as the receiver power calculation module, then sends the result to the efficiency calculation module. The efficiency calculation module calculates the system efficiency corresponding to the same timestamp based on the average power of the transmitter and the average power of the receiver with the same timestamp.

[0081] As shown in Figure 6, 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; 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;

[0082] 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.

[0083] The receiver control unit calculates the average power of the receiver, tagged with the first timestamp, based on the receiver's output current and output voltage, which are within the pre-designed values. Specifically:

[0084] Calculate the output power once for the output current and output voltage of the receiver for each sampling count within the pre-designed values; calculate the arithmetic mean of all output powers within the pre-designed values ​​to obtain the average power of the receiver with the first timestamp tag.

[0085] 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:

[0086] Calculate the input power once for each sampling count of the transmitter's input current and input voltage within the pre-designed values; calculate the arithmetic mean of all input powers within the pre-designed values ​​to obtain the average power of the transmitter with the second timestamp tag.

[0087] The receiver control unit calculates the average power of the transmitter when the count reaches a pre-designed value; the transmitter control unit calculates the average power of the receiver 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. The receiver sampling module has a current sampling circuit and a voltage sampling circuit. These are placed at the intermediate connection point between the battery pack and the power conversion module, and T is set. P 3 and T P 4. 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.

[0088] The receiver power calculation module uses an STM32 main control chip, which is directly connected to T P 3 and T PThe 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 also 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 receiving a certain number of 10MHz pulse signals, the power signals obtained during the previous counting period are averaged, stored, and the power signals from the previous sampling circuits are cleared. Sampling restarts, 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 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.

[0089] 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.

[0090] The input power can also be obtained by measuring the current and voltage on the DC bus. Furthermore, the DC bus will not move, making measurement easier. As shown in Figure 4, two sampling points are set on both sides of the DC power supply. and 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.

[0091] 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.

[0092] Since the wireless charging platform for electric vehicles is mainly built using an LCC-S topology, the LCC-S topology model is constructed according to Figure 3. The parameters are configured to allow the system to reach resonance, including the constant voltage power supply. The system's stable frequency is ,

[0093] The simulation did not consider power loss, but for the system, the internal resistance of the transmitting coil is... and the internal resistance of the receiving coil and power supply internal resistance The power loss of the component has the greatest impact on the system power loss.

[0094] Given emission current For the internal resistance of the transmitting coil Losses include: It is also known that the received current For the internal resistance of the receiving coil Losses include: And we know the DC side current. For the internal resistance of the power supply Losses include: At this point, the system resistance loss should be: .

[0095] The experiment first sets up a clock synchronization system, as shown in Figure 7, which mainly consists of a microcontroller, a disciplined clock, and current and voltage sampling circuits. As described above, 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 the clock synchronization system calculate the power and efficiency respectively when the receiver passes the guide rail.

[0096] 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, as shown in Figures 8 to 10. Figure 8 is a comparison of input power; it can be seen from Figure 8 that the error in input power is extremely small, only about 1%. Figure 9 is a comparison of output power; it can be seen from Figure 9 that the error in output power is extremely small, only about 1%. Figure 10 is a comparison of efficiency; it can be seen from Figure 10 that the error in efficiency is extremely small, only about 1%. In summary, the errors in input power, output power, and efficiency are only about 1%, which can be ignored when considering experimental measurement errors.

[0097] 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 one percent error range. It has the following outstanding advantages: it can be used for long-distance dynamic efficiency measurement; it uses wireless connection and has a high real-time update rate; the error is low, within one percent; and the price of this invention is lower than that of large power analyzers.

Claims

1. A method for calculating the efficiency of a dynamic wireless charging system based on clock synchronization, the dynamic wireless charging system comprising a receiving end and a multi-rail transmitting end, characterized in that, The method comprises the steps of: sampling the output current and output voltage of the receiving end; generating a first pulse signal of a first frequency, a second pulse signal of a second frequency and a first timestamp signal by a first satellite disciplined clock; when the receiving end control unit receives the first pulse signal, starting to count the output current and output voltage of the receiving end according to the second pulse signal, and marking the output current and output voltage of the receiving end reaching a preset design value with a first timestamp label by the first timestamp signal; calculating the average power of the receiving end marked with the first timestamp label according to the output current and output voltage of the receiving end reaching the preset design value; calculating the average power of the transmitting end by the same process of calculating the average power of the receiving end; calculating the system efficiency corresponding to the same timestamp label according to the average power of the transmitting end and the average power of the receiving end with the same timestamp label.

2. The clock synchronization-based dynamic wireless charging system efficiency calculation method of claim 1, wherein, The method of calculating the average power of the transmitting end by the same process of calculating the average power of the receiving end comprises the steps of: sampling the input current and input voltage of the transmitting end; generating a third pulse signal of the first frequency, a fourth pulse signal of the second frequency and a second timestamp signal by a second satellite disciplined clock; when the transmitting end control unit receives the third pulse signal, starting to count the input current and input voltage of the transmitting end according to the fourth pulse signal, and marking the input current and input voltage of the transmitting end reaching the preset design value with a second timestamp label by the second timestamp signal; calculating the average power of the transmitting end marked with the second timestamp label according to the input current and input voltage of the transmitting end reaching the preset design value. 3.The clock synchronization based dynamic wireless charging system efficiency calculation method of claim 2, wherein, The method of calculating the average power of the receiving end marked with the first timestamp label according to the output current and output voltage of the receiving end reaching the preset design value comprises the steps of: calculating an output power for each time of sampling the output current and output voltage of the receiving end within the preset design value; calculating the average power of the receiving end marked with the first timestamp label by calculating the arithmetic mean of all the output powers within the preset design value.

4. The clock synchronization-based dynamic wireless charging system efficiency calculation method of claim 3, wherein, The method of calculating the average power of the transmitting end marked with the second timestamp label according to the input current and input voltage of the transmitting end reaching the preset design value comprises the steps of: calculating an input power for each time of sampling the input current and input voltage of the transmitting end within the preset design value; calculating the average power of the transmitting end marked with the second timestamp label by calculating the arithmetic mean of all the input powers within the preset design value. 5.The clock synchronization based dynamic wireless charging system efficiency calculation method of claim 4, wherein, The average power of the transmitting end and the average power of the receiving end are calculated once for each time of reaching the preset design value. The first frequency and the second frequency satisfy that the first frequency can be divided by the second frequency.

6. A system for calculating the efficiency of a clock-synchronization-based dynamic wireless charging system, applying the method for calculating the efficiency of a clock-synchronization-based dynamic wireless charging system according to any one of claims 1 to 5, characterized in that: The system comprises a receiving end sampling module, a receiving end power calculation module, a transmitting end sampling module, a transmitting end power calculation module and an efficiency calculation module; the receiving end power calculation module is provided with a receiving end control unit and a first satellite tamed clock and a receiving end wireless communication unit connected to the receiving end control unit; The receiving end sampling module is used for sampling the output current and output voltage of the receiving end; The first satellite tamed clock is used for generating a first pulse signal of a first frequency, a second pulse signal of a second frequency and a first timestamp signal and sending them to the receiving end control unit; When the first pulse signal is received, the receiving end control unit 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 reaching a preset design value with a first timestamp label through the first timestamp signal; the receiving end control unit also calculates the average power of the receiving end marked with the first timestamp label according to the output current and output voltage of the receiving end reaching the preset design value and sends it to the efficiency calculation module through the receiving end wireless communication unit; The transmitting end sampling module is used for sampling the input current and input voltage of the transmitting end; The transmitting end power calculation module is provided with a transmitting end control unit and a second satellite tamed clock and a transmitting end wireless communication unit connected to the transmitting end control unit; The efficiency calculation module is used for calculating the system efficiency corresponding to the same timestamp label according to the average power of the transmitting end and the average power of the receiving end with the same timestamp label.

7. The clock synchronization based dynamic wireless charging system efficiency calculation system of claim 6, wherein: The transmitting end power calculation module is provided with a transmitting end control unit and a second satellite tamed clock and a transmitting end wireless communication unit connected to the transmitting end control unit; The second satellite tamed clock is used for generating a third pulse signal of the first frequency, a fourth pulse signal of the second frequency and a second timestamp signal and sending them to the transmitting end control unit; When the third pulse signal is received, the transmitting end control unit starts counting according to the fourth pulse signal to obtain the input current and input voltage of the transmitting end, and marks the input current and input voltage of the transmitting end reaching the preset design value with a second timestamp label through the second timestamp signal; the transmitting end control unit also calculates the average power of the transmitting end marked with the second timestamp label according to the input current and input voltage of the transmitting end reaching the preset design value and sends it to the efficiency calculation module through the transmitting end wireless communication unit.

8. The clock synchronization based dynamic wireless charging system efficiency calculation system of claim 7, wherein: The receiving end control unit calculates the average power of the receiving end marked with the first timestamp label according to the output current and output voltage of the receiving end reaching the preset design value, specifically: The output power of the receiving end is calculated once for each sampling count in the preset design value; The output power of the receiving end is calculated once for each sampling count in the preset design value; The average power of the receiving end marked with the first time stamp is obtained by arithmetically averaging all the output powers within the pre-designed value; The transmitting end control unit calculates the average power of the transmitting end marked with the second time stamp according to the input current and input voltage of the transmitting end reaching the pre-designed value, specifically: The input power of the transmitting end counted for each sampling within the pre-designed value is calculated; The average power of the transmitting end marked with the second time stamp is obtained by arithmetically averaging all the input powers within the pre-designed value.

9. The clock synchronization based dynamic wireless charging system efficiency calculation system of claim 8, wherein: The receiving end control unit calculates the average power of the transmitting end once the count reaches the pre-designed value; the transmitting end control unit calculates the average power of the receiving end once the count reaches the pre-designed value; the first frequency and the second frequency satisfy: the first frequency can be divided by the second frequency.

10. The clock synchronization based dynamic wireless charging system efficiency calculation system of any one of claims 6 to 9, wherein: The transmitting end comprises a direct current bus and a plurality of high-frequency inverter circuits connected in parallel to the direct current bus, and a plurality of transmitting end resonant circuits connected one-to-one with the plurality of high-frequency inverter circuits, each of the transmitting end resonant circuits comprising a transmitting end compensation network and a transmitting coil, and a switching switch connected between the direct current power supply and each of the transmitting coils; the receiving end comprises a receiving coil, a receiving end compensation network, an electric energy conversion circuit and a battery pack connected in sequence; a sampling point of the receiving end sampling module is arranged between the electric energy conversion circuit and the battery pack; a sampling point of the transmitting end sampling module is arranged on the direct current bus.

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