CN112994419A - Composite modulation method for pulse width modulation and orthogonal frequency division multiplexing modulation - Google Patents
Composite modulation method for pulse width modulation and orthogonal frequency division multiplexing modulation Download PDFInfo
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- CN112994419A CN112994419A CN202110220011.0A CN202110220011A CN112994419A CN 112994419 A CN112994419 A CN 112994419A CN 202110220011 A CN202110220011 A CN 202110220011A CN 112994419 A CN112994419 A CN 112994419A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
- H02M3/157—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators with digital control
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
- H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
- H02M3/1582—Buck-boost converters
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
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Abstract
The invention discloses a composite modulation method of pulse width modulation and orthogonal frequency division multiplexing modulation, which is used for controlling a power electronic converter, wherein an orthogonal frequency division multiplexing technology is adopted in communication, serial data is converted into multi-channel communication subcarriers for parallel transmission, and active equalization of electric energy among different converters can be realized under the condition of more complex power electronic converter combination so as to improve the efficiency of energy transfer to the maximum extent; and the real-time monitoring of the power electronic conversion circuit is realized, so that the power electronic conversion circuit is protected. The invention can enable the power electronic converter to realize multiple functions of information acquisition, data communication, active electric energy equalization, converter protection and the like, and has the characteristics of low communication cost, simple maintenance, wiring harness saving and compact structure.
Description
Technical Field
The invention belongs to the technical field of power electronics, and particularly relates to a composite modulation method of pulse width modulation and orthogonal frequency division multiplexing modulation.
Background
On the one hand, power electronics technology is one of the most widely used technologies in the present day, and is a fundamental component in various aspects of industrial production and daily life. On the other hand, the twenty-first century is an information age, and especially in the process of accelerating digitization and intellectualization of the traditional industry, the application of information technology is extremely important. Power electronic information modulation technology has also been developed in the future as a product of cross-fusion of power electronic technology and information technology. The power electronic equipment has the information transmission capability in the energy conversion process, the process is that electric energy is input by analog quantity and becomes electric energy pulse after being dispersed, the pulse can load digital information, and then the electric energy is converted into the analog quantity by the filter and is output.
In the field of power electronic information modulation technology, communication technology has various methods. Single carrier modulation technology is adopted in patents CN 200810241190.0 and CN201510918583.0, power and communication signals are in the same carrier, and the problem of limited modulation method is brought by sharing one carrier; in patents CN200910077269.9 and CN200810241952.7, power line carrier communication technology is adopted, which generates signals through an additional hardware circuit and couples the signals to a power line through an impedance matching circuit, and a transmission line is required to be shared with power. The invention adopts a double-carrier modulation technology, namely independent communication carriers are adopted for modulation, the power and the communication frequency are not mutually influenced, data is firstly modulated onto a low-frequency data carrier and then modulated onto a power carrier through Pulse Width Modulation (PWM), and in order to modulate the data carrier onto the power carrier, the frequency of the data carrier is far less than that of the power carrier. Compared with a single carrier modulation technology and a power line carrier communication technology, the modulation technology adopted by the invention has the advantages of strong anti-interference capability and easiness in remote transmission, and meanwhile, the implementation cost is low and the technical scheme is simpler.
In the occasion with higher requirement on communication speed, Orthogonal Frequency Division Multiplexing (OFDM) technology can be adopted to convert serial data into multi-channel parallel communication subcarriers for transmission, so that the communication speed can be greatly improved. The ofdm modulation technique has the advantage of high bandwidth utilization, but because the time domain signal is the superposition of a plurality of sinusoidal sub-carrier signals, when the signal phases of all the sub-carriers are relatively close or identical, a peak with a larger amplitude appears, i.e., a higher peak-to-average power ratio (PAPR) exists. The current methods for solving the problem in the communication field are as follows: signal predistortion methods, coding-like methods, probability-like methods, etc. The signal predistortion method is to avoid the appearance of an overlarge peak-to-average power ratio by windowing or amplitude conversion on a signal with larger peak power; the coding method is that the peak-to-average power ratio of all code blocks generated by different coding methods is calculated, and then the code block with lower peak-to-average power ratio is selected for transmission; the probabilistic method mainly uses some algorithms, with the goal of reducing the probability of high peak-to-average power ratio occurrence.
In the specific way of communication coding, there are generally three ways: amplitude shift keying, frequency shift keying, phase shift keying, differential phase shift keying. The amplitude shift keying method is to take different values according to digital data to modulate the amplitude of the carrier, for example, binary 0 corresponds to an amplitude of 0, and binary 1 corresponds to an amplitude of 1. Such a modulation technique is relatively simple to implement, but is easily affected by gain variation, and is an inefficient modulation technique; the frequency shift keying method is to take different values according to the digital data to modulate the frequency of the carrier, for example, binary 0 corresponds to a frequency of 1kHz, and binary 1 corresponds to a frequency of 2 kHz. The modulation technology has good anti-interference performance, but occupies larger bandwidth; the phase shift keying method is to take different values according to digital data to modulate the phase of a carrier, for example, binary 0 corresponds to phase shift of 0 °, binary 1 corresponds to phase shift of 90 °, and the modulation technique has the best anti-interference performance, and the phase change can also be used as many other functions such as clock of a timing information synchronization transmitting end and a receiving end. The differential phase shift keying method is similar to the phase shift keying method, and the difference is only that different values are taken according to the difference between adjacent digital data to modulate the phase of a carrier wave, so that the modulation technology can solve the problem of reverse work of the phase shift keying method.
Disclosure of Invention
The present invention aims to provide a composite modulation method of pulse width modulation and orthogonal frequency division multiplexing modulation aiming at the defects of the prior art.
The purpose of the invention is realized by the following technical scheme: a power electronic converter adopts PWM modulation to realize output voltage or current control, and simultaneously superposes OFDM signals in voltage or current ripples to realize data communication. The power electronic converter comprises a power control loop and a data transmission loop in control: the power control loop calculates the output PWM value d according to the given voltage or current value of the converterPWM(ii) a The data transmitting loop calculates and obtains a corresponding OFDM modulation signal d according to the transmitted dataOFDMThe actual output duty cycle of the converter is dPWM+dOFDM。
The orthogonal frequency division multiplexing modulation adopts multi-channel subcarrier signal superposition, the frequency of each signal subcarrier is an integer fraction of PWM frequency, and every two signals are orthogonal in a code element period, and the subcarrier frequency fckExpressed as:
wherein K is a positive integer, TbIs the symbol period.
Further, a cyclic adaptive μ -law companding transform method is adopted to perform predistortion on the orthogonal frequency division multiplexing modulation signal at the sending end, reduce the PAPR and simultaneously keep the signal power before and after the transform unchanged, specifically:
(1) the amplitude of the modulation signal of each path of subcarrier is dkInitially, modulating the peak value of the signal
(2) D 'is judged'maxWhether the following conditions are satisfied:
d'max＜d'u_max
wherein, d'u_maxIs the peak upper limit of the modulated signal. If the condition is satisfied, executing the step (4)) And (4) if the condition is not met, executing the step (3).
(3) Will dkReduced to 0.8 times of the original, dk＝0.8dkThe peak value d 'of the modulated signal after the one-cycle adaptive mu-law companding transform is calculated'maxComprises the following steps:
wherein A is an inflection point value of a cycle adaptive mu-law companding transform method, and mu is a constant; and (3) jumping to the step (2) and judging whether the peak value of the modulated signal after conversion meets the condition.
(4) And outputting the modulation signal.
Furthermore, the selection of the inflection point value A is adaptive to the number of subcarrier lines for sending signals, and when the number of the subcarrier lines is less than 4, a circular adaptive mu-law compression-expansion transformation method is not needed; when the number of subcarrier paths is greater than or equal to 4, the average power of the signal is selected as the inflection point value.
Furthermore, the value of mu needs to comprehensively consider two requirements of actual system performance and PAPR value reduction, and the best mu value is selected to obtain the maximum compression of PAPR under the condition of the allowable bit error rate of the system, and generally mu does not exceed 25.
Further, a signal peak upper limit d 'is modulated'u_maxThe value is adapted to the system performance and transmission requirements.
Further, the method specifically comprises the following steps:
firstly, according to a voltage-current double closed-loop control algorithm, calculating to obtain an output PWM value dPWM；
Then, data to be transmitted is serial-to-parallel converted, converted into N baseband data streams and allocated to N subcarriers. Per sub-band data stream sub-carrier xk(t) modulating the signal to a communication carrier to form an orthogonal frequency division multiplexing communication carrier s (t) composed of N paths of subcarrier signals, wherein the s (t) is expressed as:
and finally, obtaining the output duty ratio of the converter as follows:
d＝dPWM+dOFDM
wherein d isOFDMIs the average value of s (t) over one PWM carrier period.
Further, in step (2), the modulation technique adopted by the sub-carriers is multilevel phase shift keying, multilevel differential phase shift keying or quadrature amplitude modulation.
Further, subcarrier xk(t) employs multi-ary phase shift keying modulation, represented as:
wherein d iskFor the amplitude of each of the sub-carriers,
the phase of each path of subcarrier after modulation; by selecting dkGuarantee dPWM+dOFDM<1。
Further, the communication carrier wave is a sine wave.
Further, the internal power topology of the power electronic converter adopts a Buck circuit, a Boost circuit, a DC-DC, an AC-DC or a DC-AC.
The invention has the beneficial effects that: the invention is used for controlling the power electronic converter, the orthogonal frequency division multiplexing technology is adopted in communication, serial data is converted into multi-channel communication subcarriers for parallel transmission, and under the condition of more complicated power electronic converter combination, the active balance of electric energy among different converters can be realized, so that the efficiency of energy transfer is improved to the maximum extent; and the real-time monitoring of the power electronic conversion circuit is realized, so that the power electronic conversion circuit is protected. The invention can enable the power electronic converter to realize multiple functions of information acquisition, data communication, active electric energy equalization, converter protection and the like, and has the characteristics of low communication cost, simple maintenance, wiring harness saving and compact structure.
Drawings
FIG. 1 is a diagram of a controller hardware architecture employing a complex modulation approach;
FIG. 2 is a schematic diagram of a controller function block employing a complex modulation method;
FIG. 3 is a schematic diagram of an architecture of a controller application scenario employing a complex modulation method;
FIG. 4 is a topological structure and a control schematic diagram of a Buck/Boost type DC/DC converter;
fig. 5 is a schematic diagram of a transmission process of power signal complex modulation information;
FIG. 6 is a diagram illustrating a mapping between transmitted data and phase sectors;
FIG. 7 is a diagram illustrating data frame composition and data modulation method;
fig. 8 is a flowchart illustrating a mu-law companding method for cyclic adaptation of a modulation signal.
Detailed Description
The invention relates to a composite modulation method of pulse width modulation and orthogonal frequency division multiplexing modulation, which specifically comprises the following steps: the power electronic converter is subjected to PWM modulation to realize output voltage or current control, and meanwhile, OFDM signals are superposed in voltage or current ripples to realize data communication. The power electronic converter can be any converter, and comprises a power control loop and a data transmission loop in control: the power control loop calculates the output PWM value d according to the given voltage or current value of the converterPWM(ii) a The data transmitting loop calculates and obtains a corresponding OFDM modulation signal d according to the transmitted dataOFDMThe actual output duty cycle of the converter is the value dPWM+dOFDM(ii) a Modulation communication can be carried out between the converters by adopting a composite modulation method of Pulse Width Modulation (PWM) and orthogonal frequency division multiplexing modulation (OFDM). The OFDM modulation method adopts multi-channel subcarrier signal superposition, the frequency of each signal subcarrier is an integer fraction of PWM frequency, and the signals are orthogonal in pairs in a code element period, namely the subcarrier frequency fckExpressed as:
wherein K is a positive integer, TbIs the symbol period. The modulation techniques used for the subcarriers include Multilevel Phase Shift Keying (MPSK), Multilevel Differential Phase Shift Keying (MDPSK), and Quadrature Amplitude Modulation (QAM).
Further inhibiting the peak-to-average power ratio of the system, specifically: and pre-distorting the OFDM modulation signal at a sending end by adopting a cyclic self-adaptive mu-law compression-expansion transformation method, so that the peak-to-average power ratio (PAPR) of the system is reduced, and the signal power before and after transformation is kept unchanged.
For amplitude of skIs subjected to mu-law companding transform to obtain an amplitude s'kComprises the following steps:
wherein A is an inflection point value of a cycle adaptive mu-law companding transform method, and mu is a constant; and | | represents solving an absolute value.
The specific process of the cycle self-adaptive mu-law compression expansion transformation method comprises the following steps:
(1) the amplitude of the modulation signal of each path of subcarrier in the PWM/OFDM composite modulation method is dkInitially, modulating the peak value of the signal
(2) D 'is judged'maxWhether the following conditions are satisfied:
d'max＜d'u_max
wherein, d'u_maxIs the peak upper limit of the modulated signal. And (5) if the condition is met, executing the step (4), and if the condition is not met, executing the step (3).
(3) Will dkReduced to 0.8 times of the original, dk＝0.8dkThe peak value d 'of the modulated signal after the one-cycle adaptive mu-law companding transform is calculated'maxComprises the following steps:
wherein A is an inflection point value of a cycle adaptive mu-law companding transform method, and mu is a constant; and (3) jumping to the step (2) and judging whether the peak value of the transformed modulation signal meets the condition or not to continuously approach to a proper modulation signal meeting the condition.
(4) And outputting the modulation signal.
The selection principle of each parameter in the circulation self-adaptive mu-law companding transformation method is as follows: the selection of the inflection point value A is adaptive to the number of subcarrier paths for sending signals, when the number of the subcarrier paths is less than 4 paths, a cyclic adaptive mu-law compression expansion transformation method is not needed, and when the number of the subcarrier paths is more than or equal to 4 paths, the average power of the signals is selected as the inflection point value; the value of mu needs to comprehensively consider the requirements of the actual system performance and the reduction of the PAPR, the best mu value is selected to obtain the maximum compression of the PAPR under the condition of the allowable bit error rate of the system, and the mu is generally not more than 25; modulation signal peak value upper limit d'u_maxThe value is adapted to the system performance and transmission requirements.
The PWM/OFDM composite modulation method specifically comprises the following steps:
firstly, according to a voltage-current double closed-loop control algorithm, calculating to obtain an output PWM value dPWM；
Then, data to be transmitted is serial-to-parallel converted, converted into N baseband data streams and allocated to N subcarriers. Subcarrier xk(t) uses MPSK modulation, expressed as:
wherein d iskFor the amplitude of each of the sub-carriers,
the phase of each path of subcarrier after MPSK modulation is obtained.
Per sub-band data stream sub-carrier xk(t) modulation to a communications carrier (typically positive)Sine wave), forming an orthogonal frequency division multiplexing communication carrier s (t) composed of N paths of subcarrier signals, and expressing as:
obtaining d according to the average value of the amplitude of s (t) in a PWM carrier periodOFDM。
Finally, the output duty ratio d of the converter is obtained as d ═ dPWM+dOFDM. In subcarrier design, by selecting dkGuarantee dPWM+dOFDM<1。
To describe the present invention more specifically, the following detailed description will explain the technical solutions of the present invention from the detailed embodiments with reference to the accompanying drawings.
The invention relates to a controller which aims at a power electronic converter and adopts a composite modulation method of Pulse Width Modulation (PWM) and orthogonal frequency division multiplexing modulation (OFDM), and is applied to the power electronic converter, the hardware architecture of the controller is shown in figure 1, wherein TMS320F28377D is selected as a main control chip, an AD8608 amplifier is selected to form a signal conditioning circuit to acquire voltage, current and temperature information of a power circuit, a control algorithm is executed, a driving signal is generated, and a switching tube of the power circuit is driven to work. A schematic diagram of a functional module of a controller adopting a complex modulation method is shown in fig. 2, and circuit parameters obtained by sampling are respectively output to each functional module of the controller to transmit power and information. In this embodiment, the power topology of the power electronic converter may be any conversion circuit, and the specific topology may be a Buck circuit, a Boost circuit, a DC-AC converter, an AC-DC converter, or the like. The present embodiment takes a dual DC-DC cascade circuit as an example, and details an operation mechanism of a complex modulation method of a power electronic converter using Pulse Width Modulation (PWM) and Orthogonal Frequency Division Multiplexing (OFDM) according to the present invention.
In this embodiment, a framework of an application scenario of the controller adopting the composite modulation method is shown in fig. 3, where an external dc power supply is connected to an input terminal of a module a, a module B is used as a load of the module a, an output terminal of the module a is connected to an input terminal of the module B, and an output terminal of the module B is connected to a pure resistor as a load thereof. The module a serves as an information sending terminal, the module B serves as an information receiving terminal, and the modules a and B respectively select a Boost circuit and a Buck circuit in the present embodiment. The modules A and B are respectively realized by the own controller through functions of power transmission, information modulation, demodulation and the like.
The power transmission process of this example is shown in fig. 4: the output voltage and the inductive current are obtained by sampling in the circuit, firstly, the voltage outer ring is used, the sampled voltage is compared with the voltage reference value and then is output to the current inner ring through the PI adjusting module, and the output value of the current inner ring is compared with the current reference value and then is output to the power control quantity through the PI adjusting module. And the output is output to a driving plate for controlling a switching tube.
The communication process of this example is shown in fig. 5: the digital controller of the information sending end digitally encodes and modulates the data to be sent to obtain the corresponding disturbance dOFDMSuperimposed on the original power modulation dPWMMake the control quantity output by the power control loop be dOFDM+dPWMAnd further, the power output of the converter is compounded with communication components; the information receiving end samples the voltage, the sampling value is demodulated through a band-pass filter and an amplifier and a discrete Fourier algorithm to obtain an original code, and the code is decoded to obtain original data.
At a data transmitting end, 6 baseband data streams are adopted, wherein each data stream is 8 bits of data, one data is called a code element, and the code element period is selected to be 1.2 ms. The digital modulation method adopts quaternary differential phase shift keying (4DPSK) modulation, that is, the transmitted data can be any number of 0 to 3, the phase 0 to 360 degrees is divided into 4 equal sectors, each transmitted data corresponds to one sector, and the corresponding relationship is shown in fig. 6. For a sub-carrier, within 1.2ms of a code element period, one data is converted into a sine wave by a corresponding carrier modulation technology, and due to the particularity of differential phase shift keying modulation and the zero phase needing reference, N bit data needs N +2 sine waves to complete. The specific method of data modulation in this example is shown in fig. 7, and 8-bit data needs to be converted into 10 continuous sine waves, 10 sine wavesThe phase difference of the first and second bits can obtain 9 bits of data, wherein the 1 st bit is a reference zero bit, the 1 st bit is subtracted from the rest 8 bits to obtain 8 bits of transmitted data, and the phase subcarrier x of the 8 bits of transmitted datak(t) is expressed as:
the specific flow chart of the mu-law companding method for performing the cyclic self-adaptation on the duty ratio at the data sending end is shown in fig. 8, and the peak value of the initial modulation signal is set as
Judging the peak value d 'of the converted signal'maxWhether the following conditions are satisfied:
d'max＜d'u_max
wherein d'u_maxIs the peak upper limit of the modulated signal.
If the condition is satisfied, the modulation signal is outputted, and if the condition is not satisfied, the d is outputtedkThe correction is performed to reduce the amplitude to 0.8 times of the original amplitude, and the above determination is performed to continuously approach to an appropriate modulation signal satisfying the condition.
By means of the communication mode, under the condition of a complex power electronic converter combination, active balance of electric energy among different converters can be achieved, and the efficiency of energy transfer is improved to the maximum extent; and the real-time monitoring of the power electronic conversion circuit is realized, so that the power electronic conversion circuit is protected.
Through the implementation method, the composite modulation method of Pulse Width Modulation (PWM) and orthogonal frequency division multiplexing modulation (OFDM) aiming at the power electronic converter can enable the power electronic converter to realize multiple functions of information acquisition, data communication, active electric energy equalization, converter protection and the like, and has the characteristics of low communication cost, simplicity in maintenance, wiring harness saving and compact structure.
The embodiments described above are presented to enable a person having ordinary skill in the art to make and use the invention. It will be readily apparent to those skilled in the art that various modifications to the above-described embodiments may be made, and the generic principles defined herein may be applied to other embodiments without the use of inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications to the present invention based on the disclosure of the present invention within the protection scope of the present invention.
Claims (10)
1. A composite modulation method of pulse width modulation and orthogonal frequency division multiplexing modulation is characterized in that: the power electronic converter adopts PWM modulation to realize output voltage or current control, and simultaneously superposes OFDM signals in voltage or current ripples to realize data communication. The power electronic converter comprises a power control loop and a data transmission loop in control: the power control loop calculates the output PWM value d according to the given voltage or current value of the converterPWM(ii) a The data transmitting loop calculates and obtains a corresponding OFDM modulation signal d according to the transmitted dataOFDMThe actual output duty cycle of the converter is dPWM+dOFDM。
The orthogonal frequency division multiplexing modulation adopts multi-channel subcarrier signal superposition, the frequency of each signal subcarrier is an integer fraction of PWM frequency, and every two signals are orthogonal in a code element period, and the subcarrier frequency fckExpressed as:
wherein K is a positive integer, TbIs the symbol period.
2. The complex modulation method of pulse width modulation and orthogonal frequency division multiplexing modulation according to claim 1, wherein a cyclic adaptive μ -law companding transform method is adopted to pre-distort the orthogonal frequency division multiplexing modulation signal at the transmitting end, and reduce PAPR while keeping the signal power before and after transform unchanged, specifically:
(1) the amplitude of the modulation signal of each path of subcarrier is dkInitially, modulating the peak value of the signal
(2) D 'is judged'maxWhether the following conditions are satisfied:
d'max＜d'u_max
wherein, d'u_maxIs the peak upper limit of the modulated signal. And (5) if the condition is met, executing the step (4), and if the condition is not met, executing the step (3).
(3) Will dkReduced to 0.8 times of the original, dk＝0.8dkThe peak value d 'of the modulated signal after the one-cycle adaptive mu-law companding transform is calculated'maxComprises the following steps:
wherein A is an inflection point value of a cycle adaptive mu-law companding transform method, and mu is a constant; and (3) jumping to the step (2) and judging whether the peak value of the modulated signal after conversion meets the condition.
(4) And outputting the modulation signal.
3. The composite modulation method of pulse width modulation and orthogonal frequency division multiplexing modulation according to claim 2, wherein the selection of the inflection point value a is adapted to the number of sub-carrier channels for transmitting signals, and when the number of sub-carrier channels is less than 4, a cyclic adaptive μ -law companding transform method is not required; when the number of subcarrier paths is greater than or equal to 4, the average power of the signal is selected as the inflection point value.
4. The complex modulation method of pulse width modulation and orthogonal frequency division multiplexing modulation as claimed in claim 2, wherein the value of μ is obtained by comprehensively considering two requirements of actual system performance and PAPR value reduction, and the best μ value is selected to obtain maximum compression of PAPR under the condition of allowable error rate of the system, and generally μ is not more than 25.
5. As claimed in2 the complex modulation method of pulse width modulation and orthogonal frequency division multiplexing modulation is characterized in that the modulation signal peak value upper limit d'u_maxThe value is adapted to the system performance and transmission requirements.
6. The method for complex modulation of pwm and ofdm according to claim 1, comprising the steps of:
firstly, according to a voltage-current double closed-loop control algorithm, calculating to obtain an output PWM value dPWM；
Then, data to be transmitted is serial-to-parallel converted, converted into N baseband data streams and allocated to N subcarriers. Per sub-band data stream sub-carrier xk(t) modulating the signal to a communication carrier to form an orthogonal frequency division multiplexing communication carrier s (t) composed of N paths of subcarrier signals, wherein the s (t) is expressed as:
and finally, obtaining the output duty ratio of the converter as follows:
d＝dPWM+dOFDM
wherein d isOFDMIs the average value of s (t) over one PWM carrier period.
7. The modulation method according to claim 6, wherein in the step (2), the modulation technique adopted by the sub-carriers is selected from the group consisting of multiple-system phase shift keying, multiple-system differential phase shift keying and quadrature amplitude modulation.
8. The method of claim 7, wherein the subcarrier x is a subcarrierk(t) employs multi-ary phase shift keying modulation, represented as:
wherein d iskFor the amplitude of each of the sub-carriers,
the phase of each path of subcarrier after modulation; by selecting dkGuarantee dPWM+dOFDM<1。
9. The method of claim 6, wherein the communication carrier is a sine wave.
10. The modulation method of claim 1, wherein the internal power topology of the power electronic converter is a Buck circuit, a Boost circuit, a DC-DC, an AC-DC or a DC-AC.
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| CN114785117A (en) * | 2022-05-23 | 2022-07-22 | 浙江大学 | PWM (pulse-width modulation) regulation and control method for three-degree-of-freedom power information fusion |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103957033A (en) * | 2014-05-12 | 2014-07-30 | 东南大学 | Communication-line-free data transmission method between power electronic devices based on composite modulation |
| WO2018069424A1 (en) * | 2016-10-12 | 2018-04-19 | Technische Universität Dortmund | Communication system in a current supply grid |
| CN111404580A (en) * | 2020-03-24 | 2020-07-10 | 中国矿业大学 | OFDM-based DC/DC converter power line power signal composite transmission system and transmission method |
-
2021
- 2021-02-26 CN CN202110220011.0A patent/CN112994419B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103957033A (en) * | 2014-05-12 | 2014-07-30 | 东南大学 | Communication-line-free data transmission method between power electronic devices based on composite modulation |
| WO2018069424A1 (en) * | 2016-10-12 | 2018-04-19 | Technische Universität Dortmund | Communication system in a current supply grid |
| CN111404580A (en) * | 2020-03-24 | 2020-07-10 | 中国矿业大学 | OFDM-based DC/DC converter power line power signal composite transmission system and transmission method |
Non-Patent Citations (1)
| Title |
|---|
| 王志鹍: ""光伏功率优化***及电力线通信研究"", 《中国优秀硕士学位论文全文数据库 工程科技Ⅱ辑》 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114785117A (en) * | 2022-05-23 | 2022-07-22 | 浙江大学 | PWM (pulse-width modulation) regulation and control method for three-degree-of-freedom power information fusion |
| CN114785117B (en) * | 2022-05-23 | 2024-05-24 | 浙江大学 | PWM regulation and control method for three-degree-of-freedom power information fusion |
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