A power electronic converter energy and information synchronous modulation method and system
By superimposing a digital baseband signal during the PWM modulation process of the power electronic converter, the problems of high complexity and low bandwidth utilization in the existing technology are solved, achieving efficient synchronous transmission of energy and information, reducing system costs and improving communication reliability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG UNIV
- Filing Date
- 2026-04-13
- Publication Date
- 2026-07-14
AI Technical Summary
Existing power electronic converters require additional modulation and demodulation circuits for signal co-modulation technology, resulting in low signal bandwidth utilization, complex demodulation processes, and impacts system reliability and cost.
In the PWM modulation process of the power electronic converter, the digital baseband signal is directly superimposed in the form of a small disturbance, and the energy and information composite signal is output through the power switching device. The digital signal is then recovered by the receiving filter and the channel equalizer.
It achieves efficient energy information transmission without the need for additional components, reduces system complexity and cost, improves communication speed and reliability, and maintains converter stability and efficiency.
Smart Images
Figure CN122394537A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of communication technology for power electronic equipment, and specifically relates to a method and system for synchronous modulation of energy and information in a power electronic converter. Background Technology
[0002] Power electronic converters, as core devices for power conversion and transmission, are widely used in new energy power generation, energy storage systems, electric vehicles, industrial automation, and wireless power transmission. In practical engineering applications, converters often need to interact with other units in the system to achieve functions such as status monitoring, coordinated control, and fault diagnosis.
[0003] Traditional converter information transmission methods typically rely on independent communication lines (such as RS-485, CAN bus, etc.) or wireless communication modules. This not only increases system cost and wiring complexity but also affects system reliability. Therefore, an energy and information synchronous modulation technology (referred to as "energy-information synchronization modulation")—which utilizes the inherent characteristics of power electronic devices and transmits energy and information simultaneously through existing energy transmission lines—has become a research hotspot.
[0004] Current energy-information co-modulation technology modulates the degrees of freedom of a modulating wave or carrier wave according to certain rules in power electronic converters, thereby superimposing the data to be transmitted onto the converter's control signal and generating a composite energy information signal in the system. Therefore, energy-information co-modulation technology can achieve communication without affecting the normal operation of the converter system. Patent CN117811232A discloses a communication method for a wireless power information cooperative transmission system, which includes superimposing a digitally modulated signal onto a modulating wave to achieve communication. Patent CN116155069A discloses a high-speed power information fusion PFM modulation method, which achieves communication by fusing and modulating the frequency and phase of the PFM signal carrier wave with power information.
[0005] The aforementioned existing technologies have the following shortcomings: digital modulation methods require additional modulation and demodulation circuits, increasing system complexity; the modulated signal is a bandpass signal with low bandwidth utilization, limiting the improvement of communication speed; and the demodulation process requires carrier synchronization recovery, which is relatively complex. Therefore, how to achieve more efficient synchronous transmission of energy information in a simpler way is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention
[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method and system for synchronous modulation of energy and information in power electronic converters. Without adding additional components, energy and information synchronization is achieved by directly superimposing the digital baseband signal in the form of a small perturbation into the pulse width modulation (PWM) modulation process.
[0007] The objective of this invention is achieved through the following technical solution: a method for synchronous modulation of energy and information in a power electronic converter, used in a power electronic system containing a source-side converter, a load-side converter, and an energy transmission link. Without affecting the converter's PWM modulation, the digital baseband signal to be transmitted is superimposed on the PWM modulation process with a small perturbation, enabling the converter output to simultaneously carry both energy and digital signals. The specific process is as follows: For source-side and load-side converters, when they do not transmit digital signals, they are controlled using PWM. The PWM reference signal is compared with the carrier to generate a PWM drive signal, which is then used by power switching devices to enable the converter to output an energy signal. For a source or load converter that acts as a transmitter, when transmitting digital signals, the digital baseband signal to be transmitted is directly superimposed on the PWM reference signal to generate a composite modulation wave. The superposition amplitude of the digital baseband signal is configured to be no greater than a preset threshold. The composite modulation wave is compared with the carrier wave to generate a composite PWM drive signal. Through power switching devices, the converter simultaneously outputs energy signals and digital signals to form a composite energy information signal. The energy transmission link serves as a power transmission path and a bidirectional communication channel between the source and the load, and is used to transmit the composite energy information signal. For the load or source converter acting as the receiving end, the composite energy information signal is obtained by sampling the voltage or current signal at the corresponding position of the energy transmission link. For the energy information composite signal obtained by sampling, the energy signal and switching ripple are filtered out by the receiving filter to recover the digital baseband signal.
[0008] Furthermore, the PWM reference signals of the source-end and load-end converters are determined by the control objectives and circuit state variables of the power electronic system, wherein the control objectives are selected from one or more of the following: output voltage, output current, output power, input impedance, output impedance, and system efficiency.
[0009] Furthermore, the digital baseband signal to be transmitted is a baseband pulse sequence that has not been digitally modulated (such as Amplitude Shift Keying (ASK), Frequency Shift Keying (FSK), Phase Shift Keying (PSK), etc.), and it adopts a transmission code pattern without DC component to ensure that power transmission is not interfered with; the symbol length of the digital baseband signal is an integer multiple of the converter switching period to avoid beat frequency phenomenon in the PWM drive signal.
[0010] Furthermore, the preset threshold is determined based on the amplitude of the PWM reference signal, and the superposition amplitude of the digital baseband signal is not greater than a preset ratio of the amplitude of the PWM reference signal.
[0011] Furthermore, the preset ratio is 10%, and this disturbance threshold can ensure reliable communication without affecting the stability and efficiency of the converter.
[0012] Furthermore, the receiving filter includes a cascaded bandpass filter and a channel equalizer; The bandpass filter is used to filter out high-frequency switching ripple in the composite energy information signal and isolate the DC component corresponding to the energy signal to obtain the communication ripple. The channel equalizer is used to compensate for channel distortion in the communication ripple and restore the original digital baseband signal.
[0013] Furthermore, the channel equalizer includes the following two generation methods: (1) The channel transmission characteristics from the transmitter to the receiver are obtained through theoretical modeling, and the inverse system of the channel is designed as a channel equalizer accordingly. (2) By performing adaptive equalization processing on the received communication ripple, the parameters of the channel equalizer are generated and updated in real time.
[0014] The present invention also provides a power electronic converter energy and information synchronization modulation system, comprising: The system includes a source-side converter, a load-side converter, and an energy transmission link. The source-side converter and the load-side converter employ PWM modulation, and both the source-side converter and the load-side converter integrate a signal injection module and a signal sampling and receiving processing module. The energy transmission link serves as a power transmission path and a bidirectional communication channel between the source and the load, and is used to transmit the composite energy information signal. The signal injection module is used to directly superimpose the digital baseband signal to be transmitted onto the PWM reference signal to generate a composite modulation wave. The superposition amplitude of the digital baseband signal is configured to be no greater than a preset threshold. The composite modulation wave is compared with the carrier wave to generate a composite PWM drive signal. Through the power switching device, the converter simultaneously outputs energy signal and digital signal to form a composite energy information signal. The signal sampling and receiving processing module is used to sample the voltage or current signal at the corresponding position of the energy transmission link to obtain the energy information composite signal; wherein, the signal sampling and receiving processing module includes a receiving filter, used to filter out the energy signal and switching ripple in the energy information composite signal and recover the digital baseband signal.
[0015] Furthermore, the receiving filter includes a cascaded bandpass filter and a channel equalizer; The bandpass filter is used to filter out high-frequency switching ripple in the composite energy information signal and isolate the DC component corresponding to the energy signal to obtain the communication ripple. The channel equalizer is used to compensate for channel distortion in the communication ripple and restore the original digital baseband signal.
[0016] Furthermore, the channel equalizer includes the following two generation methods: (1) The channel transmission characteristics from the transmitter to the receiver are obtained through theoretical modeling, and the inverse system of the channel is designed as a channel equalizer accordingly. (2) By performing adaptive equalization processing on the received communication ripple, the parameters of the channel equalizer are generated and updated in real time.
[0017] Based on the above technical solution, the present invention has the following beneficial technical effects: 1. This invention directly reuses the existing power switching devices and transmission lines in the converter as information modulators and communication channels, without the need to add additional signal generating devices, coupling circuits or communication chips, which greatly reduces system cost and complexity.
[0018] 2. This invention uses baseband transmission, where signal energy is concentrated in the mid-to-low frequency band. Compared to digital modulation, this method can maximize the use of the available bandwidth of the energy transmission link, theoretically enabling higher communication rates.
[0019] 3. This invention adopts a demodulation method of direct sampling and baseband recovery, which eliminates the need for complex carrier synchronization circuits and phase-locked loops. Combined with a channel equalizer, it can effectively compensate for channel distortion, improve communication reliability, and reduce the bit error rate.
[0020] 4. This invention adopts a small perturbation injection method, and the perturbation depth is controllable. While achieving reliable communication, it hardly affects the steady-state performance and power transmission efficiency of the converter.
[0021] 5. This invention is applicable to various power electronic converters using PWM control, and has good versatility and promotional value. Attached Figure Description
[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0023] Figure 1 A schematic diagram of the principle of a PWM modulator for synchronous modulation of energy and information in a power electronic converter; Figure 2 This is a schematic diagram of the waveforms at various points in the system when AMI code is used as the baseband code type; Figure 3 This is a schematic diagram of the circuit topology of a wireless power transmission system according to an embodiment of the present invention and the principle of downlink communication thereon; Figure 4 This is a waveform diagram illustrating the downlink communication process according to an embodiment of the present invention; Figure 5 This is a waveform diagram of the uplink communication process in an embodiment of the present invention. Detailed Implementation
[0024] To enable those skilled in the art to better understand the technical solutions in the embodiments of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art should fall within the protection scope of the embodiments of this application.
[0025] This invention provides a method for energy and information synchronization modulation of a power electronic converter, comprising the following steps: S1. For source-end and load-end converters, when they do not transmit digital signals, they are controlled by PWM. The PWM reference signal is compared with the carrier to generate a PWM drive signal, which is then used by power switching devices to make the converter output an energy signal.
[0026] S2. For a source-end or load-end converter acting as a transmitter, when transmitting digital signals, such as Figure 1As shown, the digital baseband signal to be transmitted is directly superimposed on the PWM reference signal in the form of a small disturbance to generate a composite modulation wave. The composite modulation wave is compared with the carrier wave to generate a composite PWM drive signal. Through the power switching device, the converter simultaneously outputs the energy signal and the digital signal to form a composite energy information signal.
[0027] S3. The energy transmission link serves as a power transmission path and a bidirectional communication channel between the source and the load, and is used to transmit the composite energy information signal.
[0028] S4. For the load or source converter that serves as the receiving end, the energy information composite signal is obtained by sampling the voltage or current signal at the corresponding position of the energy transmission link.
[0029] S5. For the energy information composite signal obtained by sampling, the energy signal and switching ripple are filtered out by the receiving filter to recover the digital baseband signal.
[0030] Preferably, in step S1, the PWM reference signal is calculated from the control target and circuit state variables. This calculation process is typically performed using a PID (Proportional-Integral-Derivative) closed-loop control algorithm, but other control algorithms may also be used. The control target is generally selected from one or more of the following: output voltage, output current, output power, input impedance, output impedance, and system efficiency. The circuit state variables are the voltage and current quantities in the circuit, which are generally obtained through a sampling circuit.
[0031] Preferably, in step S2, the PWM drive signal causes a small disturbance change through the operation of the power switching device, causing the converter to simultaneously output both an energy signal and a digital signal, injecting a composite energy information signal into the circuit. Example waveforms of the composite modulation wave and the PWM drive signal during this process are shown below. Figure 2 As shown in the third and fourth lines.
[0032] In order for the converter to maintain stable energy transmission when transmitting digital signals, the digital baseband signal needs to be selected with a transmission code pattern that does not contain DC components, such as Manchester code, Alternate Mark Inversion (AMI) code, etc., so that the average value of the modulated wave is the same in the communication and non-communication states.
[0033] For example, such as Figure 2 As shown, AMI code is used as the transmission code type. The encoding rule of AMI code is to alternately change the "1" (transmission number) of the message code to "+1" and "-1", while the "0" (space number) remains unchanged.
[0034] In addition, the amplitude of the digital baseband signal needs to be adjusted to limit the amplitude of the composite modulation wave fluctuation caused by the superposition of digital baseband signals, so as to avoid the amplitude being too large and affecting the stability of the system. Preferably, the disturbance threshold is limited to no more than 10% of the reference signal size. In addition, the symbol length of the digital baseband signal should be an integer multiple of the switching period (which is also the carrier period) to avoid the beat frequency phenomenon of the PWM drive signal. Figure 2 The third line shows the case where the symbol length is 4 times the switching period.
[0035] Preferably, in step S3, the composite energy information signal is transmitted through an energy transmission link, so communication ripple can be extracted at any point in the energy transmission link. For example... Figure 2 As shown in the fifth line, the received waveform contains energy signals and the communication ripple exhibits significant inter-symbol interference (ISI). Therefore, the waveform needs to be processed by a receiving filter, which includes a bandpass filter and a channel equalizer. The bandpass filter is used to isolate the DC signal and suppress switching ripple, extracting the communication ripple from the composite energy information signal. The channel equalizer is used to suppress ISI, and then the digital baseband signal is recovered through sampling and decision.
[0036] Preferably, the channel equalizer can be implemented in two ways: one is to establish a system model through the modeling theory of power electronic systems, solve for the theoretical results of channel characteristics, and design a corresponding inverse system based on this, which can serve as a channel equalizer; the other is to perform adaptive equalization processing on the received communication ripple, such as the Least Mean Square (LMS) algorithm, to generate and update the parameters of the channel equalizer in real time.
[0037] As a preferred embodiment, the present invention takes a magnetic resonant wireless power transfer system as an example. Figure 3 As shown, its basic structure consists of a source-side DC / DC converter, an inverter, a magnetically coupled resonant cavity, a rectifier, and a load-side DC / DC converter. This invention is not limited to wireless power transmission systems; it can also be adapted to various DC systems and supports bidirectional communication. The implementation process is basically the same for different systems, with the only difference being the system's channel characteristics.
[0038] The magnetically coupled resonant cavity is composed of multiple self-resonant coils, providing a highly efficient non-contact energy transfer path. Electrical energy passes through the cavity in the form of an alternating magnetic field. The DC / DC converters at the source and load ends are used to adjust and optimize the output power and efficiency. In this invention, they also function as data transmission converters; a Boost converter is used at the source, and a Buck-Boost converter is used at the load. Circuit parameters are shown in Table 1. Table 1: Circuit Parameters .
[0039] Applying the power electronic converter energy and information synchronization modulation method of this invention to this wireless power transmission system enables half-duplex bidirectional communication. The duty cycle of both the source and load converters is set to 0.5, and the disturbance threshold is set to 9%. The AMI code is selected as the transmission code for the digital baseband signal, with a symbol length of 4 switching cycles, resulting in a communication baud rate of 125 kbps. DC bus voltages are acquired at the input capacitor of the load converter and the output capacitor of the source converter to obtain the composite energy information signal. The bandpass filter of the receiving filter is an analog filter, consisting of a cascaded first-order high-pass filter with a cutoff frequency of 5 kHz and a third-order Type I Chebyshev low-pass filter with a cutoff frequency of 125 kHz and a passband ripple of 1 dB. The channel equalizer is a digital IIR filter, specifically a fractional-interval equalizer, with a sampling frequency of 500 kHz. In this embodiment, the model of the wireless power transmission system is established using the Generalized State-Space Averaging (GSSA) method to obtain the transfer function, which reflects the channel characteristics of the system. The inverse system is designed using the zero-pole cancellation method as a channel equalizer to compensate for channel characteristics and suppress inter-symbol interference within the communication frequency band. In this embodiment, since the uplink and downlink channels have different channel characteristics, their channel equalizer parameters are different, but the rest are the same.
[0040] To test communication performance, both the source-side Boost converter and the load-side Buck-Boost converter were instructed to send a data frame containing 18 symbols every 400μs. This data frame included a start bit and a parity bit: the start bit was "1" for bit synchronization, and the sampling decision time was selected at the moment corresponding to the maximum output value of the channel equalizer at the start bit; the transmitted information symbol was "0100110101100001"; even parity was used, ensuring that the number of "1"s in a frame was even, therefore the actual transmitted frame was "101001101011000010".
[0041] Figure 4 The relevant waveforms of downlink communication are shown. Figure 5 The waveforms related to the uplink communication are shown. Figure 4 , 5 The topmost waveform is the voltage waveform on the DC bus at the receiving side, representing the received composite energy information signal. This signal is processed by a bandpass filter to obtain the communication ripple, i.e., the second row of waveforms. At this point, the communication ripple still exhibits significant inter-symbol interference (ISI). The third row of waveforms then passes through a channel equalizer to obtain a waveform with less ISI. Finally, the original digital baseband signal is recovered through sampling and decision-making.
[0042] This invention also provides a power electronic converter energy and information synchronization modulation system, comprising: The system includes a source converter, a load converter, and an energy transmission link. The source converter and the load converter employ PWM modulation, and both the source converter and the load converter integrate a signal injection module and a signal sampling and receiving processing module.
[0043] The energy transmission link serves as a power transmission path and a bidirectional communication channel between the source and the load, and is used to transmit the composite energy information signal.
[0044] The signal injection module is used to directly superimpose the digital baseband signal to be transmitted onto the PWM reference signal to generate a composite modulation wave. The superposition amplitude of the digital baseband signal is configured to be no greater than a preset threshold. The composite modulation wave is compared with the carrier wave to generate a composite PWM drive signal. Through the power switching device, the converter simultaneously outputs energy signal and digital signal to form a composite energy information signal.
[0045] The signal sampling and receiving processing module is used to sample the voltage or current signal at the corresponding position of the energy transmission link to obtain the energy information composite signal; wherein, the signal sampling and receiving processing module includes a receiving filter, used to filter out the energy signal and switching ripple in the energy information composite signal and recover the digital baseband signal.
[0046] It should be noted that the system embodiment shown in this embodiment matches the content of the above method embodiment, and the content of the above method embodiment can be referred to, and will not be repeated here.
[0047] The above description of the embodiments is provided to enable those skilled in the art to understand and apply the present invention. Those skilled in the art can readily make various modifications to the above embodiments and apply the general principles described herein to other embodiments without creative effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made to the present invention by those skilled in the art based on the disclosure thereof should be within the scope of protection of the present invention.
Claims
1. A method for synchronous modulation of energy and information in a power electronic converter, used in a power electronic system comprising a source-side converter, a load-side converter, and an energy transmission link, characterized in that, include: For source-side and load-side converters, when they do not transmit digital signals, they are controlled using PWM. The PWM reference signal is compared with the carrier to generate a PWM drive signal, which is then used by power switching devices to enable the converter to output an energy signal. For a source or load converter that acts as a transmitter, when transmitting digital signals, the digital baseband signal to be transmitted is directly superimposed on the PWM reference signal to generate a composite modulation wave. The superposition amplitude of the digital baseband signal is configured to be no greater than a preset threshold. The composite modulation wave is compared with the carrier wave to generate a composite PWM drive signal. Through power switching devices, the converter simultaneously outputs energy signals and digital signals to form a composite energy information signal. The energy transmission link serves as a power transmission path and a bidirectional communication channel between the source and the load, and is used to transmit the composite energy information signal. For the load or source converter acting as the receiving end, the composite energy information signal is obtained by sampling the voltage or current signal at the corresponding position of the energy transmission link. For the energy information composite signal obtained by sampling, the energy signal and switching ripple are filtered out by the receiving filter to recover the digital baseband signal.
2. The method according to claim 1, characterized in that, The PWM reference signals of the source and load converters are determined by the control objectives and circuit state variables of the power electronic system. The control objectives are selected from one or more of the following: output voltage, output current, output power, input impedance, output impedance, and system efficiency.
3. The method according to claim 1, characterized in that, The digital baseband signal to be transmitted is a baseband pulse sequence without digital modulation, and adopts a transmission code pattern without DC component. Its code length is an integer multiple of the converter switching period.
4. The method according to claim 1, characterized in that, The preset threshold is determined based on the amplitude of the PWM reference signal, and the superposition amplitude of the digital baseband signal is not greater than a preset ratio of the amplitude of the PWM reference signal.
5. The method according to claim 4, characterized in that, The preset ratio is 10%.
6. The method according to claim 1, characterized in that, The receiving filter includes a cascaded bandpass filter and a channel equalizer; The bandpass filter is used to filter out high-frequency switching ripple in the composite energy information signal and isolate the DC component corresponding to the energy signal to obtain the communication ripple. The channel equalizer is used to compensate for channel distortion in the communication ripple and restore the original digital baseband signal.
7. The method according to claim 6, characterized in that, The channel equalizer includes the following two generation methods: (1) The channel transmission characteristics from the transmitter to the receiver are obtained through theoretical modeling, and the inverse system of the channel is designed as a channel equalizer accordingly. (2) By performing adaptive equalization processing on the received communication ripple, the parameters of the channel equalizer are generated and updated in real time.
8. A power electronic converter energy and information synchronization modulation system, characterized in that, include: The system includes a source-side converter, a load-side converter, and an energy transmission link. The source-side converter and the load-side converter employ PWM modulation, and both the source-side converter and the load-side converter integrate a signal injection module and a signal sampling and receiving processing module. The energy transmission link serves as a power transmission path and a bidirectional communication channel between the source and the load, and is used to transmit the composite energy information signal. The signal injection module is used to directly superimpose the digital baseband signal to be transmitted onto the PWM reference signal to generate a composite modulation wave. The superposition amplitude of the digital baseband signal is configured to be no greater than a preset threshold. The composite modulation wave is compared with the carrier wave to generate a composite PWM drive signal. Through the power switching device, the converter simultaneously outputs energy signal and digital signal to form a composite energy information signal. The signal sampling and receiving processing module is used to sample the voltage or current signal at the corresponding position of the energy transmission link to obtain the energy information composite signal; wherein, the signal sampling and receiving processing module includes a receiving filter, used to filter out the energy signal and switching ripple in the energy information composite signal and recover the digital baseband signal.
9. The system according to claim 8, characterized in that, The receiving filter includes a cascaded bandpass filter and a channel equalizer; The bandpass filter is used to filter out high-frequency switching ripple in the composite energy information signal and isolate the DC component corresponding to the energy signal to obtain the communication ripple. The channel equalizer is used to compensate for channel distortion in the communication ripple and restore the original digital baseband signal.
10. The system according to claim 9, characterized in that, The channel equalizer includes the following two generation methods: (1) The channel transmission characteristics from the transmitter to the receiver are obtained through theoretical modeling, and the inverse system of the channel is designed as a channel equalizer accordingly. (2) By performing adaptive equalization processing on the received communication ripple, the parameters of the channel equalizer are generated and updated in real time.