Power and signal dual-modulation communication system and method based on time division multiple access

Abstract

The invention discloses a power and signal dual-modulation communication system and method based on time division multiple access, and belongs to the technical field of converter control. The system comprises a plurality of converter processing modules which are connected in parallel; a first information acquisition module and a second information acquisition module in each converter processing module respectively sample an input source signal and an output signal of the converter, and send the input source signal and the output signal to a data modulation module and a data demodulation module to perform synchronous modulation and time division multiple access synchronous demodulation according to time slots according to synchronization information; the interconnection-line-free control module generates a reference signal of the PWM module according to the output of the data demodulation module and the second information acquisition module; the PWM module is used for generating gate signals of the converters, and the output of each converter is connected in parallel to a load or a power grid. The time division multiple access modulation and demodulation method is applied to the multi-converter parallel system, the problems of complex communication and difficult data modulation and demodulation are solved, and stable and economical operation of an alternating current and direct current system is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of converter control, and in particular to a power and signal dual modulation communication method based on time division multiple access. Background Art

[0002] In the traditional control of multi-input source modules, communication is often required to achieve real-time control of each device in the system. In AC / DC systems, the communication method between multiple converters has become a key factor in its large-scale application, among which the communication method based on power and signal dual modulation has received widespread attention.

[0003] The traditional power and signal dual modulation communication method uses the converter itself for communication. Although it simplifies the system cost and volume, it does not divide the time slots for each converter to transmit data. For multiple converters communicating at the same time, there is still the problem that the bus voltage is affected by multiple aliased transmission data. Therefore, a new power and signal dual modulation communication method for multiple converters in parallel is urgently needed. Summary of the invention

[0004] In view of the defects of the prior art, the present invention provides a communication system and method based on time division multiple access (TDMA) dual modulation of power and signal, aiming to solve the problems of complex communication in AC and DC systems and difficult data modulation and demodulation when multiple converters are connected in parallel, so as to achieve stable and economical operation of AC and DC systems.

[0005] In order to achieve the above object, the present invention provides a communication system based on time division multiple access power and signal dual modulation, comprising:

[0006] A plurality of converter processing modules connected in parallel; the converter processing module includes a first information acquisition module, a second information acquisition module, a synchronous detection module, a converter, a non-interconnection line control module, a PWM module, a data modulation module, and a data demodulation module;

[0007] The first information acquisition module and the second information acquisition module respectively sample the input source signal and the output signal of the converter, and send them to the data modulation module and the data demodulation module;

[0008] The synchronization detection module filters the output of the second information acquisition module and extracts the zero-crossing point of the AC filter signal, and then determines whether the data demodulation is synchronized according to the zero-crossing point of the AC filter signal and the output of the data demodulation module, and sends a synchronization signal to the data modulation module and the data demodulation module;

[0009] The data modulation module synchronously modulates the output data of the first information acquisition module according to the synchronization signal output by the synchronization detection module in accordance with the allocated time slot;

[0010] The data demodulation module performs time division multiple access based synchronous demodulation on the output data of the second information acquisition module according to the synchronous signal output by the synchronous detection module according to the allocated time slot and restores it into an actual signal;

[0011] The non-interconnection line control module performs voltage / current control according to the output of the data demodulation module and the second information acquisition module and generates a reference signal for the PWM module;

[0012] The PWM module generates a gate signal of a switch device in the converter according to the output of the data modulation module and the non-interconnection line control module;

[0013] The converter completes the conversion output of the input source signal according to the gate signal, and the output of each converter is connected in parallel to a load or a power grid.

[0014] Furthermore, the converter is a non-isolated converter.

[0015] Furthermore, when the input source comes from photovoltaics, the signal collected by the first acquisition module is the output voltage and current signal of photovoltaics; when the input source comes from a battery or a supercapacitor, the signal collected by the first acquisition module is the SOC signal of the battery or the supercapacitor.

[0016] Furthermore, the data modulation mode of the data modulation module is amplitude shift keying, frequency shift keying or phase shift keying based on time division multiple access;

[0017] If the input source signal comes from photovoltaics, the data modulation module needs to calculate the output power according to the voltage and current signals collected by the first information collection module before modulation and then perform modulation.

[0018] Furthermore, the data demodulation mode of the data demodulation module is envelope detection or coherent demodulation based on time division multiple access, and the coherent demodulation compensates for the demodulation carrier phase through an automatic adjustment algorithm.

[0019] Furthermore, the synchronization detection module filters the output of the second information acquisition module and extracts the zero-crossing point of the AC filter signal, and then determines whether there is demodulated data in each time slot within the AC filter signal cycle according to the zero-crossing point of the AC filter signal and the output of the data demodulation module. If there is, it indicates synchronization, and sends the synchronization signal to the data modulation module and the data demodulation module;

[0020] When the converter is a single-stage DC-DC converter, after the synchronization detection module in any of the converter processing modules determines that synchronization has been achieved, the synchronization signal is sent to the corresponding PWM module;

[0021] After synchronization, the synchronization detection module no longer performs synchronization detection.

[0022] Furthermore, the PWM module is specifically:

[0023] When the converter outputs a DC voltage signal, the output signal of the interconnection-free control module is used as a reference wave of the PWM module, and compared with the output of the data modulation module to generate a gate signal of the converter switch device;

[0024] When the converter outputs an AC voltage signal, the output signal of the interconnection-free control module is superimposed with the output signal of the data modulation module as a reference wave of the PWM module, and compared with the switching frequency triangle wave to generate a gate signal of the converter switch device;

[0025] When the converter is a single-stage DC-DC converter, a PWM module is connected to the synchronous detection module, and a low-frequency AC reference sine wave signal is superimposed on the reference wave of the PWM module as the reference wave of the new PWM module until the synchronization signal sent by the synchronous detection module is received, and the low-frequency AC reference sine wave signal is no longer superimposed on the reference wave of the PWM module.

[0026] Furthermore, the synchronous detection module filters the output signal of the second information acquisition module to obtain an AC filtering signal:

[0027] When the converter is a single-stage DC-DC converter, the AC filter signal is an AC signal generated by the influence of the low-frequency AC signal superimposed on the PWM reference wave in the DC-DC converter output signal sampled by the second information acquisition module;

[0028] When the converter is double-stage and the latter stage is an inverter, the AC filter signal is a double frequency pulsating signal in the output signal of the former stage direct-to-direct converter sampled by the second information acquisition module;

[0029] When the converter is a single-stage inverter, the AC filter signal is an output signal of the inverter sampled by the second information acquisition module.

[0030] The present invention also provides a power and signal dual modulation communication method based on time division multiple access, based on the system as described above, comprising the following steps:

[0031] (1) The first information acquisition module samples input source data and transmits it to the data modulation module;

[0032] (2) the data modulation module performs binary conversion on the data output by the first information acquisition module according to the synchronization signal output by the synchronization detection module and performs synchronous modulation according to the allocated time slot;

[0033] (3) The signal output by the converter of the input source data is sampled by the second information acquisition module and then sent to the data demodulation module;

[0034] (4) The synchronization detection module determines whether the data demodulation module is synchronized according to the zero crossing point of the AC filter signal in the output signal of the second information acquisition module and the output signal of the data demodulation module, and sends a synchronization signal to the data modulation module and the data demodulation module;

[0035] (5) The data demodulation module performs time division multiple access-based synchronous demodulation on the output data of the second information acquisition module according to the synchronous signal output by the synchronous detection module according to the allocated time slot and restores it into an actual signal;

[0036] (6) the non-interconnection line control module performs voltage / current control according to the output of the data demodulation module and the second information acquisition module and generates a reference signal in the PWM module;

[0037] (7) The PWM module generates gate signals of the switching devices in the converter according to the outputs of the data modulation module and the non-interconnection line control module;

[0038] (8) The output of the converter in each data processing module is connected in parallel to the load or the power grid.

[0039] Beneficial effects of the present invention:

[0040] The present invention applies a power and signal dual modulation communication method based on time division multiple access to a multi-converter parallel system, realizes modulation and transmission of data signals using only the converters themselves, proposes a self-synchronization method for converter communication and an automatic compensation algorithm for the carrier phase during data demodulation, optimizes the system structure and cost, solves the problems of complex communication in AC and DC systems and difficulty in data modulation and demodulation when multiple converters are connected in parallel, and realizes stable and economical operation of the AC and DC systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 The structure diagram of the communication system of power and signal dual modulation in time division multiple access according to an embodiment of the present invention.

[0042] Figure 2 It is a schematic diagram of the structure of the interconnection-free control module and the PWM module according to an embodiment of the present invention.

[0043] Figure 3 Schematic diagram of time slot allocation for multi-converter data transmission according to an embodiment of the present invention.

[0044] Figure 4 The figure is a flow chart of a communication method for dual modulation of power and signal in time division multiple access according to an embodiment of the present invention. DETAILED DESCRIPTION

[0045] The present invention is further described in detail below with reference to the accompanying drawings by describing in detail a preferred specific embodiment:

[0046] like Figure 1 As shown, the present invention provides a communication system based on time division multiple access power and signal dual modulation, including: a plurality of converter processing modules connected in parallel; the converter processing module includes a first information acquisition module, a second information acquisition module, a synchronous detection module, a converter, a PWM module, a data modulation module and a data demodulation module.

[0047] In each converter processing module, the input source signal is connected to the converter as an input, and the output of each converter is connected in parallel to a load or a power grid.

[0048] The first information acquisition module and the second information acquisition module respectively sample the input source signal and the output signal of the converter, and send them to the data modulation module and the data demodulation module.

[0049] The input source signal comes from the output signal of, but is not limited to, a photovoltaic module, a battery module, a supercapacitor module, etc. When the input source comes from photovoltaics, the signal collected by the first acquisition module is the output voltage and current signal of photovoltaics; when the input source comes from batteries or supercapacitors, the signal collected by the first acquisition module is the SOC signal of the batteries or supercapacitors.

[0050] The synchronization detection module filters the output of the second information acquisition module and extracts the zero-crossing point of the AC filter signal, and then determines whether the data demodulation is synchronized based on the zero-crossing point of the AC filter signal and the output of the data demodulation module. Specifically, based on filtering the output signal of the second information acquisition module and extracting the zero-crossing point of the AC filter signal, whether the data demodulation module has output in each time slot within the AC filter signal cycle, until it is detected that there is output in each time slot, it indicates synchronization, and sends the synchronization signal to the data modulation module and the data demodulation module. When the converter is a single-stage DC converter, select any converter processing module, connect the synchronization detection module therein to the PWM module at the same time, and after the synchronization detection module detects synchronization, send its synchronization information to the PWM module. After synchronization, the synchronization detection module will no longer perform synchronization detection.

[0051] If the input source signal comes from photovoltaic, the data modulation module needs to calculate the output power according to the voltage and current signals collected by the first information acquisition module before modulation. The data modulation module synchronously modulates the output data of the first information acquisition module according to the synchronization signal output by the synchronization detection module according to the allocated time slot, such as Figure 3 As shown, and output to the PWM module. The data modulation method is amplitude shift keying, frequency shift keying or phase shift keying based on time division multiple access. The data modulation signal of the data modulation module is composed of a data start bit (fixed data), a data bit and a data end bit (fixed data).

[0052] The data demodulation module performs time division multiple access synchronous demodulation on the output data of the second information acquisition module according to the allocated time slot according to the synchronization signal output by the synchronization detection module and restores it to the actual signal. The data demodulation mode of the data demodulation module is envelope detection or coherent demodulation based on time division multiple access. Coherent demodulation is to compensate the demodulation carrier phase through an automatic adjustment algorithm, that is, according to the coherent demodulation of the start bit and the end bit, the demodulation carrier phase is compensated by a certain angle until the coherence peak is maximum.

[0053] The non-interconnection line control module performs voltage or current control according to the output of the data demodulation module and the second information acquisition module and generates a reference signal for the PWM module. Wherein: voltage / current control includes but is not limited to non-interconnection line parallel control methods such as improved droop control.

[0054] The PWM module generates the gate signal of the switching device in the converter according to the output of the modulation module and the non-interconnection line control module. Figure 2 As shown, when the converter outputs a DC voltage signal, the output signal of the non-interconnection control module is used as the reference wave of the PWM module, and is compared with the output of the data modulation module to generate the gate signal of the converter switch device; when the converter outputs an AC voltage signal, the output signal of the non-interconnection control module is superimposed with the output signal of the data modulation module as the reference wave of the PWM module, and is compared with the switching frequency triangle wave to generate the gate signal of the converter switch device. When the converter is a single-stage DC converter, the PWM module connected to the synchronous detection module, the reference wave of the above PWM module is also superimposed with a low-frequency AC reference sine wave signal as the reference wave of the new PWM module, until the synchronized signal sent by the synchronous detection module is received, the low-frequency AC reference sine wave signal is no longer superimposed.

[0055] The synchronization detection module filters the output signal of the second information acquisition module and extracts the zero-crossing point of the filtered signal, and then determines whether the data demodulation module is synchronized according to the zero-crossing point of the filtered signal and the output of the data demodulation module; when the converter is a single-stage DC-DC converter, the filtered signal is an AC signal generated by the output signal of the DC-DC converter sampled by the second information acquisition module under the influence of the low-frequency AC signal superimposed in the PWM reference wave; when the converter is a double-stage converter and the subsequent stage is an inverter, the filtered signal is a double-frequency pulsating signal in the output signal of the preceding DC-DC converter sampled by the second information acquisition module; when the converter is a single-stage inverter, the filtered signal is the output signal of the inverter sampled by the second information acquisition module.

[0056] The converter converts the input source signal into an output according to the gate signal, and the output of each converter is connected in parallel to the load or the power grid. The converter is a non-isolated converter of various types. The switching devices include but are not limited to IGBT or MOSFET.

[0057] like Figure 4 As shown, the embodiment of the present invention also provides a power and signal dual modulation communication method based on time division multiple access, based on the above system, including the following steps:

[0058] S101. A first information acquisition module samples input source data and transmits it to a data modulation module.

[0059] S102: The data modulation module converts the data output by the first information acquisition module into a binary signal according to the synchronization signal output by the synchronization detection module and performs synchronization modulation according to the allocated time slot number.

[0060] S103, the signal output by the converter of the input source data is sampled by the second information acquisition module and then sent to the data demodulation module.

[0061] S104, the synchronization detection module filters the output signal of the second information acquisition module and extracts the zero-crossing point of the AC filter signal, and then determines whether the data demodulation module is synchronized according to the zero-crossing point of the AC filter signal and the output of the data demodulation module.

[0062] S105, the data demodulation module performs time division multiple access-based synchronous demodulation on the output signal of the second data acquisition module according to the synchronous signal output by the synchronous detection module according to the allocated time slot and restores it to the actual signal;

[0063] S106 , the non-interconnection line control module performs voltage / current control according to the outputs of the data demodulation module and the second information acquisition module and generates a reference signal in the PWM module.

[0064] S107, the PWM module generates a gate signal of a switching device in the converter according to the output of the data modulation module and the non-interconnection line control module;

[0065] S108. The outputs of the converters in the various data processing modules are connected in parallel to a load or a power grid.

[0066] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention can be made. Therefore, the protection scope of the present invention should be limited by the attached claims.

Claims

1. A power and signal dual modulation communication system based on time division multiple access, characterized in that: include: A plurality of converter processing modules connected in parallel; the converter processing module includes a first information acquisition module, a second information acquisition module, a synchronous detection module, a converter, a non-interconnection line control module, a PWM module, a data modulation module, and a data demodulation module; The first information acquisition module and the second information acquisition module respectively sample the input source signal and the output signal of the converter, and send them to the data modulation module and the data demodulation module; The synchronization detection module filters the output of the second information acquisition module and extracts the zero-crossing point of the AC filter signal, and then determines whether the data demodulation is synchronized according to the zero-crossing point of the AC filter signal and the output of the data demodulation module, and sends a synchronization signal to the data modulation module and the data demodulation module; The data modulation module synchronously modulates the output data of the first information acquisition module according to the synchronization signal output by the synchronization detection module in accordance with the allocated time slot; the data demodulation module synchronously demodulates the output data of the second information acquisition module based on time division multiple access according to the synchronization signal output by the synchronization detection module in accordance with the allocated time slot and restores it to an actual signal; The non-interconnection line control module performs voltage / current control according to the output of the data demodulation module and the second information acquisition module and generates a reference signal for the PWM module; The PWM module generates a gate signal of a switch device in the converter according to the output of the data modulation module and the non-interconnection line control module; The converter completes the conversion output of the input source signal according to the gate signal, and the output of each converter is connected in parallel to a load or a power grid.

2. The power and signal dual modulation communication system based on time division multiple access according to claim 1, characterized in that: The converter is a non-isolated converter.

3. The power and signal dual modulation communication system based on time division multiple access according to claim 1, characterized in that: When the input source is from photovoltaics, the signals collected by the first acquisition module are the output voltage and current signals of photovoltaics; when the input source is from batteries or supercapacitors, the signals collected by the first acquisition module are the SOC signals of batteries or supercapacitors.

4. The power and signal dual modulation communication system based on time division multiple access according to claim 3 is characterized in that: The data modulation mode of the data modulation module is amplitude shift keying, frequency shift keying or phase shift keying based on time division multiple access; If the input source signal comes from photovoltaics, the data modulation module needs to calculate the output power according to the voltage and current signals collected by the first information collection module before modulation and then perform modulation.

5. The power and signal dual modulation communication system based on time division multiple access according to claim 1, characterized in that: The data demodulation mode of the data demodulation module is envelope detection or coherent demodulation based on time division multiple access, and the coherent demodulation compensates the demodulation carrier phase through an automatic adjustment algorithm.

6. The power and signal dual modulation communication system based on time division multiple access according to claim 1, characterized in that: The synchronization detection module filters the output of the second information acquisition module and extracts the zero-crossing point of the AC filter signal, and then determines whether there is demodulated data in each time slot within the AC filter signal cycle according to the zero-crossing point of the AC filter signal and the output of the data demodulation module. If there is, it indicates synchronization, and sends the synchronization signal to the data modulation module and the data demodulation module; When the converter is a single-stage DC-DC converter, after the synchronization detection module in any of the converter processing modules determines that synchronization has been achieved, the synchronization signal is sent to the corresponding PWM module; After synchronization, the synchronization detection module no longer performs synchronization detection.

7. The power and signal dual modulation communication system based on time division multiple access according to claim 6, characterized in that: The PWM module is specifically: When the converter outputs a DC voltage signal, the output signal of the interconnection-free control module is used as a reference wave of the PWM module, and compared with the output of the data modulation module to generate a gate signal of the converter switch device; When the converter outputs an AC voltage signal, the output signal of the interconnection-free control module is superimposed with the output signal of the data modulation module as a reference wave of the PWM module, and compared with the switching frequency triangle wave to generate a gate signal of the converter switch device; When the converter is a single-stage DC-DC converter, a PWM module is connected to the synchronous detection module, and a low-frequency AC reference sine wave signal is superimposed on the reference wave of the PWM module as the reference wave of the new PWM module until the synchronization signal sent by the synchronous detection module is received, and the low-frequency AC reference sine wave signal is no longer superimposed on the reference wave of the PWM module.

8. The power and signal dual modulation communication system based on time division multiple access according to claim 7 is characterized in that: The AC filtering signal obtained by filtering the output signal of the second information acquisition module by the synchronization detection module is: When the converter is a single-stage DC-DC converter, the AC filter signal is an AC signal generated by the influence of the low-frequency AC signal superimposed on the PWM reference wave in the DC-DC converter output signal sampled by the second information acquisition module; When the converter is double-stage and the latter stage is an inverter, the AC filter signal is a double frequency pulsating signal in the output signal of the former stage direct-to-direct converter sampled by the second information acquisition module; When the converter is a single-stage inverter, the AC filter signal is an output signal of the inverter sampled by the second information acquisition module.

9. A power and signal dual modulation communication method based on time division multiple access, based on the system according to any one of claims 1 to 8, characterized in that: The steps include: (1) The first information acquisition module samples input source data and transmits it to the data modulation module; (2) the data modulation module performs binary conversion on the data output by the first information acquisition module according to the synchronization signal output by the synchronization detection module and performs synchronous modulation according to the allocated time slot; (3) The signal output by the converter of the input source data is sampled by the second information acquisition module and then sent to the data demodulation module; (4) The synchronization detection module determines whether the data demodulation module is synchronized according to the zero crossing point of the AC filter signal in the output signal of the second information acquisition module and the output signal of the data demodulation module, and sends a synchronization signal to the data modulation module and the data demodulation module; (5) The data demodulation module performs time division multiple access-based synchronous demodulation on the output data of the second information acquisition module according to the synchronous signal output by the synchronous detection module according to the allocated time slot and restores it into an actual signal; (6) the non-interconnection line control module performs voltage / current control according to the output of the data demodulation module and the second information acquisition module and generates a reference signal in the PWM module; (7) The PWM module generates gate signals of the switching devices in the converter according to the outputs of the data modulation module and the non-interconnection line control module; (8) The output of the converter in each data processing module is connected in parallel to the load or the power grid.

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