A power information dual modulation method based on high-frequency harmonic amplitude modulation

Abstract

This invention discloses a dual modulation method for power information in an isolated DC-DC converter based on high-frequency harmonic amplitude modulation, belonging to the technical field of power generation, substation, or distribution. This method is based on the design concept of complete separation of the high-frequency carrier and fundamental frequency bands. First, the waveform of the AC output voltage on the transmitting side is modulated, and the high-frequency harmonics carrying information are subjected to ASK (Automatic Signal-Sensing) to achieve wideband information transmission and improve channel capacity. Next, the signal is amplified through a resonant network of the magnetic cavity, which has the advantages of high signal-to-noise ratio, easy detection, and no impact on output voltage quality. Finally, the high-frequency AC voltage oscillation amplitude information on the receiving side is demodulated. This method requires only one switching cycle per communication, improving the communication rate compared to traditional methods; it also supports flexible high-frequency signal amplitude modulation, easily implements multi-level modulation, can transmit multiple bits per communication, and has almost no impact on DC voltage output quality or isolation transformer design, ensuring the integrity of power design.

Description

Technical Field

[0001] This invention relates to power electronics technology, specifically disclosing a dual modulation method for power information of an isolated DC-DC converter based on high-frequency harmonic amplitude modulation, belonging to the technical field of power generation, transformation, or distribution. Background Technology

[0002] To achieve efficient energy conversion and system optimization, power electronics technology has been widely used globally. This technology achieves power conversion by controlling switching devices, enabling flexible application of DC links in systems with different AC / DC sources and loads, thereby improving system efficiency and reliability. Due to the electrical isolation characteristics of DC-DC converters, fiber optic or wireless communication is often required, which increases cost and failure risk. Talkative Power Converter (TPC) technology provides a cost-effective communication solution by multiplexing power channels as channels, significantly reducing additional communication costs. However, the Frequency Shift Keying (FSK) and Phase Shift Keying (PSK) used in existing TPCs are difficult to achieve high-speed, delay-free communication. Their information carrier frequency is close to the power fundamental frequency and has weak strength, resulting in a low signal-to-noise ratio, thus limiting channel capacity. Furthermore, signal extraction often relies on sliding Fourier decomposition, sampling and analyzing harmonics over multiple cycles, requiring multiple switching cycles for a single communication, making it difficult to further increase communication speed due to efficiency limitations.

[0003] Amplitude Shift Keying (ASK) is a modulation method that controls the carrier amplitude using baseband digital signals. It's a multi-level ASK energy and signal simultaneous transmission scheme that retains the fundamental frequency for energy transmission. The effective value of the inverter voltage at the transmitting end is adjusted by regulating the phase shift angle of the full-bridge inverter. Electrical energy and information are transmitted through the transmitting and receiving coils, and the voltage amplitude in the overall electrical signal stream received at the receiving end corresponds to the demodulated information. This multi-level ASK energy and signal simultaneous transmission scheme has two main problems. First, the adjustment of the effective value of the inverter voltage corresponds to the adjustment of the fundamental frequency period timescale, which significantly affects the transmitting coil current and the total input power, causing power fluctuations and impacting the load. Second, the signal follows the energy transmitted through the fundamental frequency to the receiving end without decoupling the energy and information. Demodulating information by collecting the transmitting coil current means that information cannot be transmitted when maintaining current and power to meet load requirements is necessary. Furthermore, the jumps in information caused by power fluctuations affect the reliability of system communication.

[0004] Therefore, current TPC technology cannot meet the requirements of high-speed communication and strong anti-interference in power electronic converters. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of the aforementioned background technology by providing a power information dual modulation method based on high-frequency harmonic amplitude modulation. Based on the ASK modulation concept, the amplitude of the high-frequency harmonics carrying the information is adjusted by regulating the AC voltage waveform on the information transmitting side. The resonant characteristics of the AC link in the isolated DC-DC converter are used to amplify the high-frequency harmonics and transmit power simultaneously. By acquiring and demodulating the high-frequency AC voltage oscillation signal on the receiving side, the invention solves the technical problems of signal susceptibility to interference and low transmission rate in current TPC technology, thereby achieving the invention objective of high anti-interference and high-speed TPC communication.

[0006] To achieve the above-mentioned objectives, the present invention employs the following technical solution:

[0007] A power information dual modulation method based on high-frequency harmonic amplitude modulation is applicable to isolated DC-DC converters.

[0008] Based on amplitude shift keying modulation technology, the information sequence is modulated into high-frequency harmonics to obtain high-frequency harmonics whose amplitude varies with the AC voltage waveform on the information transmission side;

[0009] While transmitting the AC voltage on the information transmitting side, the high-frequency harmonics whose amplitude varies with the AC voltage waveform on the information transmitting side are amplified to obtain the high-frequency AC voltage oscillation signal on the information receiving side.

[0010] The high-frequency AC voltage oscillation signal at the data receiving side is demodulated.

[0011] As a further optimization of the power information dual modulation method based on high-frequency harmonic amplitude modulation, in the process of modulating the information sequence into high-frequency harmonics based on amplitude shift keying modulation technology, a signal frequency greater than the switching frequency is selected as the carrier frequency.

[0012] As a further optimization of the power information dual modulation method based on high-frequency harmonic amplitude modulation, the high-frequency harmonics whose amplitude varies with the AC voltage waveform on the information transmission side are obtained. Specifically, each bit information symbol is associated with the inner phase shift angle on the information transmission side, and the inner phase shift angle on the information transmission side is adjusted according to the information sequence.

[0013] As a further optimization of the power information dual modulation method based on high-frequency harmonic amplitude modulation, this method amplifies the high-frequency harmonics whose amplitude varies with the waveform of the AC voltage on the information transmission side while transmitting the AC voltage on the information transmission side. This is achieved through a component with frequency selection function.

[0014] As a further optimization of the power information dual modulation method based on high-frequency harmonic amplitude modulation, the component with frequency selection function is a magnetic cavity composed of an isolation transformer and an external phase-shifting inductor. The external phase-shifting inductor is connected to the secondary coil of the isolation transformer, and the equivalent circuit of the isolation transformer and the parasitic network of the magnetic cavity composed of the external phase-shifting inductor resonate at the signal frequency.

[0015] As a further optimization of the power information dual modulation method based on high-frequency harmonic amplitude modulation, the equivalent circuit of the isolation transformer includes, but is not limited to, a three-capacitor network. The three-capacitor network includes: the equivalent capacitance of the information transmitting side winding, the equivalent capacitance of the information receiving side winding, the inter-winding capacitance, and the leakage inductance. The equivalent capacitance of the information transmitting side winding is connected in parallel with the primary winding of the isolation transformer, the equivalent capacitance of the information receiving side winding is connected in parallel with the secondary winding of the isolation transformer, the inter-winding capacitance is connected across the primary and secondary windings of the isolation transformer, and the leakage inductance is connected in series with the secondary winding of the isolation transformer.

[0016] As a further optimization of the power information dual modulation method based on high-frequency harmonic amplitude modulation, the external phase-shifting inductor includes inductors and parasitic capacitances connected in parallel.

[0017] As a further optimized scheme of the power information dual modulation method based on high-frequency harmonic amplitude modulation, the demodulation information of the high-frequency AC voltage oscillation signal acquired on the information receiving side is as follows:

[0018] The high-frequency AC voltage oscillation signal on the information receiving side is processed to obtain the high-frequency AC component contained in the high-frequency AC voltage oscillation signal on the information receiving side.

[0019] Signal conditioning is performed on the high-frequency AC component contained in the high-frequency AC voltage oscillation signal on the information receiving side to obtain a DC voltage pulse that is linearly correlated with the amplitude of the high-frequency AC component contained in the high-frequency AC voltage oscillation signal on the information receiving side, and the amplitude information of the DC voltage pulse is collected.

[0020] As a further optimization of the power information dual modulation method based on high-frequency harmonic amplitude modulation, the signal input processing of the high-frequency AC voltage oscillation signal on the information receiving side includes, but is not limited to, high-pass filtering and signal isolation.

[0021] As a further optimization of the power information dual modulation method based on high-frequency harmonic amplitude modulation, the signal conditioning of the high-frequency AC component contained in the high-frequency AC voltage oscillation signal on the information receiving side includes, but is not limited to, bandpass filtering and envelope detection.

[0022] The present invention, by adopting the above technical solution, has the following beneficial effects:

[0023] (1) This invention is the first to realize dual modulation of information energy using high frequency harmonic amplitude shift keying. By using a high frequency carrier that is much higher than the power frequency and switching frequency as the information carrier, the information bandwidth and channel capacity are improved. On the information transmission side, only the switching quantity needs to be adjusted to realize information injection, without the need for dedicated communication equipment and channels. The high frequency signal is amplified by the resonant network of the magnetic cavity to obtain a high signal-to-noise ratio and easy-to-detect high frequency AC voltage oscillation signal on the receiving side. This does not affect the quality of the output DC voltage, nor does it affect the design and optimization of the isolation transformer. The amplitude of the high frequency AC voltage oscillation signal on the receiving side is collected. The demodulation result of the collected information is independent of the load requirements, so as to realize high-speed communication without affecting the design of the power section.

[0024] (2) Based on the design concept of complete separation between high frequency carrier and fundamental frequency band, the present invention uses a carrier frequency much higher than the switching frequency, so that a lower switching frequency can be used when transmitting the same information, reducing the influence of low frequency power on the signal and improving equipment efficiency; in addition, since the carrier frequency is much higher than the switching frequency, the mutual interference between the two is minimal, which is also beneficial to the design of information filter.

[0025] (3) The present invention can easily adjust the amplitude of the high-frequency harmonics that transmit information, and can easily implement the multi-level modulation (M-ary) strategy, so that more information can be sent in a single communication, and appropriate information strength can be adopted to meet communication needs.

[0026] (4) The present invention achieves communication in one switching cycle for the first time. Compared with the traditional TPC technology which requires multiple switching cycles for communication, the invention improves the communication rate. Thanks to the high signal-to-noise ratio, the information-related harmonic amplitude is easy to detect without the need for sliding Fourier decomposition, thus achieving instant communication and improving the dynamic performance of AC power converters. Attached Figure Description

[0027] Figure 1 This is a waveform diagram of amplitude frequency keying (AFS) modulation signal.

[0028] Figure 2 This is a schematic diagram of the overall principle of the dual-information modulation method proposed in this invention.

[0029] Figure 3 This is the amplitude-frequency gain curve of the magnetic cavity in this embodiment of the invention.

[0030] Figure 4 This is the equivalent circuit of the magnetic cavity in the embodiment of the present invention.

[0031] Figure 5 This is a waveform diagram of the voltage to ground at the transformer port on the information receiving side in an embodiment of the present invention.

[0032] Figure 6This is a schematic diagram of the demodulation circuit and demodulated information in an embodiment of the present invention.

[0033] Figure 7 This is an example diagram of dual information modulation of a dual active bridge converter in an embodiment of the present invention.

[0034] Figure 8 This is a schematic diagram of the signal transmission path in the converter in an embodiment of the present invention.

[0035] Figure 9 This is a specific implementation of the demodulation circuit in the embodiments of the present invention.

[0036] Figure 10 These are experimental waveforms verified in the embodiments of the present invention.

[0037] Figure 11 yes Figure 10 The experimental waveform diagram shown is a magnified view of the first position on the horizontal axis.

[0038] Figure 12 yes Figure 10 The image shown is a magnified view of the second point on the horizontal axis of the experimental waveform.

[0039] Explanation of the labels in the diagram: C p Equivalent capacitance of the receiving-side winding C s The equivalent capacitance of the transmitting side winding, C ps Inter-winding capacitance L leak Leakage, L inc ,inductance, C inc Parasitic capacitance C b High-pass capacitor, T sig Signal isolation transformer, D ,diode, C q ,capacitance, Q r Switching transistor. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0042] like Figure 1 As shown, the power information dual modulation method based on high-frequency harmonic amplitude modulation proposed in this invention is implemented through amplitude shift keying modulation information technology, using a frequency higher than the switching frequency. f The frequency of 0 is f s If a high-frequency carrier wave transmits information, then the information sequence / modulation signal "Information #1" - "Information #2" will be modulated to a frequency of f s And the amplitude of high-frequency harmonics varies with the data.

[0043] like Figure 2 As shown, the information sequence is generated at a frequency of ASK. f s The modulated information is a high-frequency harmonic whose amplitude changes with the information, and it is contained in the inverter output voltage on the information transmitting side. u 1. Changing the amplitude of this high-frequency harmonic requires changing the inverter output voltage on the information transmitting side. u One way to achieve the waveform of 1 is by adjusting... u 1 inward phase angle D 3, u The frequency contained in 1 is f s The amplitude of the high-frequency harmonics changes simultaneously. Therefore, each transmitted bit of information corresponds to a specific inner phase shift angle. For example, when transmitting bit "0", the inner phase shift angle of the transmitting-side full-bridge inverter circuit is... D 30 Similarly, when sending bit "k" (k is an integer greater than or equal to 0), the inner phase shift angle of the full-bridge inverter circuit on the transmitting side is... D 3k .

[0044] Information transmission side inverter AC voltage u 1 represents a square wave with a wide bandwidth. The switching frequency AC voltage is used for power transmission, while the high-frequency harmonic AC voltage is used for information transmission. To amplify the signal without affecting the power, a component is needed that, when the signal and power pass through it, adjusts the frequency band within the signal band. f s Information transmission side inverter AC voltage u1. Features high amplitude gain and switching frequency band f 0 Information transmission side inverter AC voltage u The amplitude gain of 1 is close to 1, such as Figure 3 As shown. One way to amplify the signal without affecting power transmission is to use a magnetic cavity composed of the existing isolation transformer and an external phase-shifting inductor, such as... Figure 4 As shown. A high-frequency transformer can be equivalently represented as a three-capacitor network, consisting of the equivalent capacitance of the receiving-side winding. C p Equivalent capacitance of transmitting side winding C s Inter-winding capacitance C ps and leakage L leak Composition. An external phase-shifting inductor is composed of an inductor... L inc and parasitic capacitance C inc Composition. The parasitic network of the magnetic cavity can exist in the signal frequency band. f s A series resonance is formed at this point, which amplifies the high-frequency harmonic AC voltage. Furthermore, the gain of the magnetic cavity is close to 1 in the low-frequency band of the switching frequency, taking a 1:1 turns ratio transformer as an example. When power and signal pass through this magnetic cavity simultaneously, the amplified high-frequency harmonic AC voltage signal is superimposed on the receiving-side transformer port in the form of high-frequency voltage oscillations, such as... Figure 5 As shown, the modulated signal is thus amplified into a directly detectable high-frequency AC voltage oscillation. The amplitude of this high-frequency AC voltage oscillation is much higher than the switching frequency, and the amplitude changes with the information.

[0045] Finally, as Figure 6 As shown, through the high-pass capacitor C b and signal isolation transformer T sig The signal input circuit and conditioning circuit together extract the high-frequency AC voltage oscillation signal from the receiving side transformer port. u 2, and identify u 2. Amplitude for demodulation information. The conditioning circuit can be composed of a bandpass filter and an envelope detector circuit. The signal demodulation process is specifically as follows: the high-frequency AC voltage oscillation signal at the transformer port on the receiving side... u 2 via high-pass capacitor C b Filtering, then passing through signal isolation transformer T sig The signal reaches the receiving side and is then filtered by a bandpass filter to extract the signal frequency. f s The harmonics are obtained u c . u cThe amplitude and the high-frequency AC voltage oscillation at the receiving side transformer port u The amplitudes are linearly related and the frequencies are consistent, that is... u c This refers to the high-frequency AC component contained in the high-frequency AC voltage oscillation signal at the information receiving side; then, through an envelope detection circuit, it is... u c Transformed into amplitude and u c Amplitude-dependent direct current u d And collected by analog-to-digital converter chip u d This is then demodulated into information.

[0046] The following example, using a dual active bridge circuit to transmit 2 bits of information "0-3", illustrates the implementation of the dual modulation method proposed in this invention. Figure 7 As shown, the converter includes: a transmitting-side full-bridge inverter circuit, a magnetic cavity, and a receiving-side full-bridge inverter circuit. The dual modulation method includes: information modulation, information amplification, and information demodulation.

[0047] The first step is to adjust the internal phase shift modulation information of the transmitting-side full-bridge inverter. For example... Figure 7 As shown, the information is injected by the switching signal of the full-bridge inverter circuit on the transmitting side. The information "0-3" is first transmitted using amplitude shift keying (APS) at a frequency of [frequency value missing]. f s High-frequency carrier modulation generates a modulated signal whose amplitude varies with the information. Obtaining this modulated signal requires adjusting the inverter AC voltage on the transmitting side. u The zero-level time of 1. u 1. The waveform will change its spectral characteristics, with a frequency of f s The amplitude of the high-frequency harmonics is thus changed, thereby obtaining the modulated signal whose amplitude changes with the information in each cycle.

[0048] The second step is to amplify the modulated signal through a magnetic cavity. For example... Figure 7 As shown, the magnetic cavity consists of a high-frequency transformer and an external phase-shifting inductor, which can be considered as a multi-order RLC network, operating in the signal frequency band. f s This creates a series resonance. The voltage amplitude gain of the magnetic cavity represents the high-frequency AC voltage oscillation signal measured from the transformer port on the receiving side. u 2. Voltage at the injection transmitting side transformer port u The ratio of 1 to 1 produces a high gain at the series resonant frequency, thus exhibiting frequency selectivity. When the series resonant frequency is equal to the frequency of the modulated signal... f sWhen the signals are synchronized, the modulated signal will be amplified at the transformer port on the receiving side, forming a high-frequency AC voltage oscillation signal at the transformer port on the receiving side. u 2.

[0049] The third step involves demodulating the high-frequency AC voltage oscillation signal at the receiving side transformer port. u 2. Through the high-pass capacitor of the signal C b and isolation transformers T sig It reaches the conditioning circuit. The conditioning circuit will... u The high-frequency signal contained in step 2 is converted into a DC voltage pulse that is linearly related to the amplitude of the high-frequency signal. Finally, the DC voltage pulse is sampled and restored to information. Specifically, the voltage to ground at the transformer port on the information receiving side... u 2. This is presented as a high-frequency signal being amplified and superimposed on a square wave, forming a high-frequency oscillation. u 2. u 2. In the spectrum, the signal frequency band f s voltage relative to u 1. Signal frequency bands in the spectrum f s The voltage is significantly amplified, while the voltage of the low-frequency harmonic components used for power transmission remains almost unchanged, so their impact on power transmission is negligible.

[0050] like Figure 8 As shown, u 2. The high-frequency AC component obtained after passing through the high-pass filter capacitor and signal isolation transformer is then... Figure 9 The conditioning circuit shown demodulates the signal into information. One type of conditioning circuit has the following structure: Figure 9 As shown, it consists of a second-order active bandpass filter and an envelope detector circuit. First, u 2. The high-frequency AC component obtained after passing through the high-pass filter capacitor and signal isolation transformer, after passing through the active bandpass filter, retains only the frequency of . f s signal components u c Next, in the envelope detection circuit, the diode... D Will u c After the negative half-cycle is truncated, it is converted into a half-wave voltage and then into a capacitor. C q Charging, due to capacitor C q With low internal resistance, its discharge time constant is relatively large, resulting in a relatively stable plateau in each cycle. u c DC oscillation amplitude related ud Before the next cycle arrives, via the switching transistor. Q r capacitor C q Discharge. Finally. u d The sampled data is converted into received information based on its voltage magnitude.

[0051] Based on the principle shown, a typical experimental waveform is as follows: Figure 10 As shown. Figure 11 and Figure 12 They are respectively Figure 10 The first and second horizontal magnified views are shown. CH1 represents the inverter AC voltage waveform on the information transmission side. u 1. CH2 is the AC voltage waveform on the information receiving side, CH3 is... Figure 9 In u 2, CH4 is Figure 9 In u c CH5 is Figure 9 In u d CH6 is the demodulated voltage output from the DAC. First, the method was verified by repeatedly sending the signal sequence "0, 1, 2, 3, 4, 5, 6, 7", where each signal represents a three-bit binary code; for example, "7" represents "111". The inner phase shift angle on the low-voltage side is... D 30 arrive D 37 The system cycles between these parameters. Due to the group delay of the active filter, the filtered output voltage... u c Compared to input voltage u There is a delay of approximately 200 ns, which is much smaller than a single switching cycle and therefore negligible. The delay between the information injected from the transmitter by adjusting the inner phase shift angle and its sampling by the analog-to-digital converter (ADC) is minimal, thus ensuring reliable real-time communication. Although a certain delay is introduced when the digital-to-analog converter (DAC) outputs the demodulated signal due to the 1 MHz Serial Peripheral Interface (SPI) communication rate and program processing time, this delay does not affect the overall performance of the proposed method.

[0052] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the specific embodiments described above. The specific embodiments and descriptions in the specification are merely for further illustrating the principles and preparation effects of the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of protection claimed by the present invention. The scope of protection of the present invention is defined by the claims and their equivalents.

Claims

1. A power information dual modulation method based on high-frequency harmonic amplitude modulation, applicable to isolated DC-DC converters, characterized in that, Select a signal frequency greater than the switching frequency. As a carrier frequency, the information sequence is modulated into high-frequency harmonics based on amplitude shift keying modulation technology. Each bit information symbol is associated with the internal phase shift angle of the information transmission side. The internal phase shift angle of the information transmission side is adjusted according to the information sequence to obtain high-frequency harmonics whose amplitude changes with the AC voltage waveform of the information transmission side. A frequency-selective component amplifies the high-frequency harmonics whose amplitude varies with the waveform of the AC voltage on the information transmitting side while transmitting the AC voltage, thereby obtaining the high-frequency AC voltage oscillation signal on the information receiving side. The frequency-selective component is a magnetic cavity composed of an isolation transformer and an external phase-shifting inductor. The magnetic cavity operates within the signal frequency band. A series resonance is formed. The external phase-shifting inductor is connected to the secondary winding of the isolation transformer. The equivalent circuit of the isolation transformer and the parasitic network of the magnetic cavity formed by the external phase-shifting inductor resonate at the signal frequency. The equivalent circuit of the isolation transformer includes a three-capacitor network, which includes: the equivalent capacitance of the information transmitting winding, the equivalent capacitance of the information receiving winding, the inter-winding capacitance, and the leakage inductance. The equivalent capacitance of the information transmitting winding is connected in parallel with the primary winding of the isolation transformer. The equivalent capacitance of the information receiving winding is connected in parallel with the secondary winding of the isolation transformer. The inter-winding capacitance is connected across the primary and secondary windings of the isolation transformer. The leakage inductance is connected in series with the secondary winding of the isolation transformer. The external phase-shifting inductor includes an inductor and a parasitic capacitance connected in parallel. Demodulation information of high-frequency AC voltage oscillation signal acquired from the information receiving side: The high-frequency AC voltage oscillation signal from the information receiving side is processed by signal input to obtain the high-frequency AC component contained in the high-frequency AC voltage oscillation signal from the information receiving side. The high-frequency AC component contained in the high-frequency AC voltage oscillation signal from the information receiving side is conditioned by signal to obtain a DC voltage pulse that is linearly related to the amplitude of the high-frequency AC component contained in the high-frequency AC voltage oscillation signal from the information receiving side. The amplitude information of the DC voltage pulse is acquired.

2. The power information dual modulation method based on high-frequency harmonic amplitude modulation according to claim 1, characterized in that, The signal input processing of the high-frequency AC voltage oscillation signal on the information receiving side includes high-pass filtering and signal isolation.

3. The power information dual modulation method based on high-frequency harmonic amplitude modulation according to claim 1, characterized in that, The signal conditioning of the high-frequency AC component contained in the high-frequency AC voltage oscillation signal on the information receiving side includes bandpass filtering and envelope detection.

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