WO2018214082A1 - 用于载波同步的装置、逆变系统和方法 - Google Patents

用于载波同步的装置、逆变系统和方法 Download PDF

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Publication number
WO2018214082A1
WO2018214082A1 PCT/CN2017/085805 CN2017085805W WO2018214082A1 WO 2018214082 A1 WO2018214082 A1 WO 2018214082A1 CN 2017085805 W CN2017085805 W CN 2017085805W WO 2018214082 A1 WO2018214082 A1 WO 2018214082A1
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Prior art keywords
input
carrier
phase
inverter
change trend
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PCT/CN2017/085805
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English (en)
French (fr)
Inventor
刘方诚
王雄飞
辛凯
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华为技术有限公司
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Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Priority to CN201780091155.2A priority Critical patent/CN110679074B/zh
Priority to EP17910657.0A priority patent/EP3637607A4/en
Priority to PCT/CN2017/085805 priority patent/WO2018214082A1/zh
Publication of WO2018214082A1 publication Critical patent/WO2018214082A1/zh
Priority to US16/692,600 priority patent/US11133751B2/en

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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
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/493—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode the static converters being arranged for operation in parallel
    • 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
    • H02M1/12—Arrangements for reducing harmonics from ac input or output
    • 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
    • H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
    • H02M5/40—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc
    • H02M5/42—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters
    • H02M5/44—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac
    • H02M5/453—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M5/458—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • 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
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/21—Conversion of ac power input into dc power output without possibility of reversal 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
    • H02M7/217—Conversion of ac power input into dc power output without possibility of reversal 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
    • H02M7/23—Conversion of ac power input into dc power output without possibility of reversal 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 arranged for operation in parallel
    • 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
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/483—Converters with outputs that each can have more than two voltages levels
    • H02M7/49—Combination of the output voltage waveforms of a plurality of converters
    • 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
    • H02M1/12—Arrangements for reducing harmonics from ac input or output
    • H02M1/123—Suppression of common mode voltage or current

Definitions

  • the present application relates to the field of power supply technology and, more particularly, to a device, an inverter system and a method for carrier synchronization.
  • the current carrier synchronization method is mainly applied to a power supply system composed of a plurality of parallel inverters connected by a communication line (for example, a bus), that is, a plurality of parallel inverters are connected by a communication line, and the above Carrier synchronization signals are transmitted between the parallel inverters through the connected communication lines for carrier synchronization.
  • a communication line for example, a bus
  • Carrier synchronization signals are transmitted between the parallel inverters through the connected communication lines for carrier synchronization.
  • a communication line for example, a bus
  • the inverter parallel power supply system without the communication line has received more and more attention.
  • the carrier synchronization method currently applied to an inverter parallel power supply system without a communication line is for a centralized three-phase power supply system.
  • the DC input terminals of the parallel three-phase inverters are all connected to the same DC bus.
  • the parallel connection of the inverters makes the zero-sequence circulation between adjacent inverters have a great influence on the stability of the power supply system. Therefore, in the centralized three-phase power supply system, it is based on the inverters connected in parallel. The resulting zero-sequence loop adjusts the phase of the carrier output by each inverter to achieve carrier synchronization.
  • the distance between adjacent inverters in each inverter is usually set far, and the DC input terminals of the inverters are independent of each other.
  • the zero-sequence circulation has little influence on the stability of the distributed power supply system, and the factors affecting the stability of the distributed power supply system are mainly the system harmonic current. Therefore, if the carrier synchronization in the above-mentioned centralized three-phase power supply system is still adopted The method cannot effectively improve the stability of the distributed power supply system.
  • Embodiments of the present application provide a device, an inverter system, and a method for carrier synchronization to improve stability of a distributed power supply system.
  • an apparatus for carrier synchronization comprising: a modulating unit that generates a switching signal based on an input carrier and a modulated wave to control a switching device in the inverter; and a current processing unit configured to acquire the inverse a magnitude of a first harmonic current output by the transformer and a magnitude of a second harmonic current, the first harmonic current being the first carrier input to the modulation carrier and the modulation wave generation switch a signal, when the switching device in the inverter is controlled, the harmonic current output by the inverter, the second harmonic current is the input carrier is the second a carrier inputting the modulation unit and the modulated wave generating switch signal, when the inverter is controlled, a harmonic current output by the inverter, wherein a phase of the first carrier and the second carrier
  • the phase of the control unit is configured to increase or decrease the phase of the input carrier input to the modulation unit according to the first change trend and the second change trend, so that the third harmonic current output by the inverter The magnitude of the first harmonic current
  • the embodiment of the present application is based on a change trend between the amplitude of the first harmonic current and the amplitude of the second harmonic current, and a change trend between the phase of the first carrier and the phase of the second carrier, and the input modulation unit
  • the phase of the input carrier is adjusted to reduce the amplitude of the harmonic current output by the inverter and improve the stability of the distributed power supply system.
  • control unit is configured to reduce an input carrier input to the modulation unit when the first change trend and the second change trend are the same
  • the phase of the input carrier that is input to the modulation unit is increased when the first change trend and the second change trend are opposite.
  • the first change trend is represented by i 1 -i 2 , where i 1 represents a magnitude of the first harmonic current, i 2 represents a magnitude of the second current; and the second change trend It is represented by ⁇ 1 - ⁇ 2 , where ⁇ 1 represents the phase of the first carrier and ⁇ 2 represents the phase of the second carrier.
  • the first change trend and the second change trend may be the same as the first change trend and the second change trend, that is, The first change trend and the second change trend are opposite, and may refer to the first change trend and the second change trend, that is,
  • control unit is further configured to: determine an adjustment step size, where the adjustment step size is an adjustment step step of increasing or decreasing a phase of the input carrier And increasing or decreasing the phase of the input carrier input to the modulation unit in the first adjustment step according to the first change trend and the second change trend.
  • the first resonant current is a resonant current output by the current inverter
  • the control unit is further configured to: according to a formula And ⁇ ref >0, determining the adjustment step size, wherein ⁇ represents the adjustment step size, i f represents the amplitude of the first resonance current, and i N represents the rated current value of the inverter, ⁇ Ref denotes a reference value that determines the adjustment step size.
  • the first resonant current is a resonant current output by the current inverter
  • the control unit is further configured to: according to a formula And ⁇ ref >0, determining the adjustment step size, wherein ⁇ represents the adjustment step size, i f represents a magnitude of the first resonance current, and i N represents a rated current value of the inverter, ⁇ Ref represents an initial value determining the adjustment step size.
  • the adjustment step size By setting the adjustment step size to be able to adjust the phase of the input carrier according to the amplitude variation of the first resonant current, it is advantageous to improve the efficiency of adjusting the phase of the input carrier.
  • increasing the phase of the input carrier input to the modulation unit may refer to delaying the input carrier by a time period corresponding to a time adjustment value, where the phase of the input carrier input to the modulation unit is reduced. It may refer to a time period corresponding to the input carrier being adjusted in time by a time adjustment value.
  • the time adjustment value ⁇ t may be according to a formula. Where ⁇ represents the adjustment step size and f C represents the frequency of the input carrier.
  • the time adjustment value ⁇ t may be according to a formula. Where ⁇ represents the adjustment step size and f C represents the frequency of the input carrier.
  • control unit is further configured to: change trends and inputs according to the first change trend, the second change trend, and a magnitude of a harmonic current The tendency of the phase of the carrier to increase or decrease the phase of the input carrier input to the modulation unit.
  • control unit is further configured to: according to the change trend of the first change trend, the second change trend, and the amplitude of the harmonic current and the change trend of the phase of the input carrier,
  • the adjustment step size is set to increase or decrease the phase of the input carrier input to the modulation unit.
  • control unit includes: a logic determining unit, configured to determine an input to the modulation unit according to the first change trend and the second change trend The phase of the input carrier; a phase shifting unit for increasing or decreasing a phase of an input carrier input to the modulation unit according to the determined phase of the input carrier input to the modulation unit.
  • the inverter is a single phase inverter or a three phase inverter.
  • the current magnitude threshold can be 1% of the inverter rated current.
  • the current processing unit is further configured to: perform current sampling on the alternating current output by the inverter to obtain a magnitude of the inverter output harmonic current.
  • an inverter system comprising a plurality of inverters, the inverter system comprising the apparatus described in any one of the foregoing first aspects, the apparatus for controlling the plurality of inverters Carrier synchronization.
  • the embodiment of the present application is based on a change trend between the amplitude of the first harmonic current and the amplitude of the second harmonic current, and a change trend between the phase of the first carrier and the phase of the second carrier, and the input modulation unit
  • the phase of the input carrier is adjusted to reduce the amplitude of the harmonic current output by the inverter and improve the stability of the distributed power supply system.
  • a method for carrier synchronization comprising a modulation unit and a inverse a modulator that controls a switching device in the inverter based on an input carrier and a modulated wave generating switching signal, the method comprising: acquiring a first harmonic current output by the inverter An amplitude and a magnitude of the second harmonic current, the first harmonic current being the input carrier for the first carrier input to the modulation unit and the modulated wave generating switch signal, in the inverter
  • the switching device performs control, the harmonic current output by the inverter, the second harmonic current is an input carrier, and the second carrier is input to the modulation unit and the modulated wave generating switch signal, and the inverter is
  • the switching device in the device performs control, the harmonic current output by the inverter, wherein the phases of the first carrier and the second carrier are different; according to the first change trend and the second change trend, increase or Reducing a phase of an input carrier input to the modulation unit such that a
  • the embodiment of the present application is based on a change trend between the amplitude of the first harmonic current and the amplitude of the second harmonic current, and a change trend between the phase of the first carrier and the phase of the second carrier, and the input modulation unit
  • the phase of the input carrier is adjusted to reduce the amplitude of the harmonic current output by the inverter and improve the stability of the distributed power supply system.
  • the increasing or decreasing the phase of the input carrier input to the modulation unit according to the first change trend and the second change trend includes: When the first change trend and the second change trend are the same, the phase of the input carrier input to the modulation unit is decreased, and when the first change trend and the second change trend are opposite, the input is increased to the The phase of the input carrier of the modulation unit.
  • the first change trend is represented by i 1 -i 2 , where i 1 represents a magnitude of the first harmonic current, i 2 represents a magnitude of the second current; and the second change trend It is represented by ⁇ 1 - ⁇ 2 , where ⁇ 1 represents the phase of the first carrier and ⁇ 2 represents the phase of the second carrier.
  • the first change trend and the second change trend may be the same as the first change trend and the second change trend, that is, The first change trend and the second change trend are opposite, and may refer to the first change trend and the second change trend, that is,
  • the method further includes: determining an adjustment step size, where the adjustment step is an adjustment step for increasing or decreasing a phase of the input carrier; Increasing or decreasing the phase of the input carrier input to the modulation unit according to the first change trend and the second change trend, further comprising: according to the first change trend and the second change trend, The step size is adjusted to increase or decrease the phase of the input carrier input to the modulation unit.
  • the first resonant current is a resonant current output by the current inverter
  • the determining an adjustment step comprises: according to a formula And ⁇ ref >0, determining the adjustment step size, wherein ⁇ represents the adjustment step size, i f represents the amplitude of the first resonance current, and i N represents the rated current value of the inverter, ⁇ Ref denotes a reference value that determines the adjustment step size.
  • the adjustment step size By setting the adjustment step size to be able to adjust the phase of the input carrier according to the amplitude variation of the first resonant current, it is advantageous to improve the efficiency of adjusting the phase of the input carrier.
  • the first resonant current is a resonant current output by the current inverter
  • the determining an adjustment step comprises: according to a formula And ⁇ ref >0, determining the adjustment step size, wherein ⁇ represents the adjustment step size, i f represents the amplitude of the first resonance current, and i N represents the rated current value of the inverter, ⁇ Ref denotes a reference value that determines the adjustment step size.
  • the adjustment step size By setting the adjustment step size to be able to adjust the phase of the input carrier according to the amplitude variation of the first resonant current, it is advantageous to improve the efficiency of adjusting the phase of the input carrier.
  • increasing the phase of the input carrier input to the modulation unit may refer to delaying the input carrier by a time period corresponding to a time adjustment value, where the phase of the input carrier input to the modulation unit is reduced. It may refer to a time period corresponding to the input carrier being adjusted in time by a time adjustment value.
  • the time adjustment value ⁇ t may be according to a formula. Where ⁇ represents the adjustment step size and f C represents the frequency of the input carrier.
  • the time adjustment value ⁇ t may be according to a formula. Where ⁇ represents the adjustment step size and f C represents the frequency of the input carrier.
  • the increasing or decreasing the phase of the input carrier input to the modulation unit according to the first variation trend and the second variation trend further includes: a mapping relationship between the first change trend, the second change trend, and a change trend of the amplitude of the harmonic current and a change trend of a phase of the input carrier, increasing or decreasing input to the modulation unit The phase of the input carrier.
  • the third harmonic current output by the inverter is adjusted by adjusting the phase of the input carrier input to the modulation unit at a time.
  • the magnitude of the signal is less than a smaller of the magnitude of the first harmonic current and the magnitude of the second harmonic current, simplifying the adjustment of the phase of the input carrier.
  • the increasing or decreasing the phase of the input carrier input to the modulation unit according to the first variation trend and the second variation trend further includes: The first change trend, the second change trend, and a change trend of the amplitude of the harmonic current and a change trend of the phase of the input carrier, increase or decrease the input to the modulation by a preset adjustment step The phase of the input carrier of the unit.
  • the phase of the input carrier input to the modulation unit is gradually adjusted by a preset adjustment step, and the input is refined.
  • the phase adjustment process of the carrier makes the phase adjustment process of the input carrier more accurate.
  • the determining, according to the first change trend and the second change trend, the phase of the input carrier input to the modulation unit including: according to the a change trend and the second change trend, determining the phase of the input carrier input to the modulation unit; for increasing or decreasing according to the determined phase of the input carrier input to the modulation unit The phase of the input carrier input to the modulation unit.
  • the current magnitude threshold can be 1% of the inverter rated current.
  • the method further includes: performing current sampling on the alternating current output by the inverter to obtain a magnitude of the inverter output harmonic current.
  • the inverter is a single phase inverter or a three phase inverter.
  • a computer readable medium storing program code for execution by a computing device, the program code comprising instructions for performing the method of the second aspect.
  • a computer program product comprising instructions for causing a computer to perform the method of the second aspect when executed on a computer is provided.
  • the technical solution provided by the present application is beneficial to improve the stability of the distributed power supply system.
  • FIG. 1 is a schematic block diagram of a centralized three-phase power supply system 100.
  • FIG. 2 is a schematic block diagram of a distributed power supply system according to an embodiment of the present application.
  • FIG. 3 is a schematic block diagram of a single phase inverter of an embodiment of the present application.
  • FIG. 4 is a schematic diagram of output current curves of a first inverter and a second inverter in a power supply system according to an embodiment of the present application.
  • FIG. 5 is a schematic diagram of output current curves of a first inverter and a second inverter in a power supply system according to an embodiment of the present application.
  • FIG. 6 is a schematic diagram showing the relationship between the phase difference ⁇ of the input carrier and the amplitude i f of the harmonic current in the embodiment of the present application.
  • FIG. 7 is a schematic block diagram of an apparatus for carrier synchronization according to an embodiment of the present application.
  • FIG. 8 is a schematic flowchart of a method for carrier synchronization according to an embodiment of the present application.
  • FIG. 9 is a schematic flowchart of a method for carrier synchronization according to an embodiment of the present application.
  • the distributed power supply system 200 shown in FIG. 2 includes a first inverter 210, a second inverter 220, and an AC bus.
  • the outputs of the first inverter 210 and the second inverter 220 are respectively connected to the same AC bus, and the first inverter and the second inverter can jointly provide AC power to the grid and provide the first inverter.
  • the direct current source of the direct current and the direct current source that supplies the direct current to the second inverter are independent of each other.
  • the distributed three-phase power supply system shown in FIG. 2 is only described by the parallel connection of two inverters.
  • the embodiment of the present application does not specifically describe the number of inverters connected in parallel in the distributed three-phase power supply system. limited.
  • the inverter may be a single-phase inverter or a three-phase inverter.
  • the structure of the single-phase inverter will be briefly described below with reference to FIG.
  • the single-phase inverter 300 shown in FIG. 3 includes a direct current system, an alternating current system, a hardware device, a first control unit, a sampling unit, and a modulation unit.
  • the first input end of the DC system is connected to the first input end of the hardware device for supplying DC power to the hardware device; the output end of the hardware device can be connected to the AC bus of the power grid, and the hardware device includes a capacitor, an inductor, a resistor, and a semiconductor switch.
  • the device and the relay device are used for inverting the DC power obtained in the DC bus to AC power and output to the AC bus;
  • the first input end of the first control unit is connected to the DC system through the first sampling unit, the first control unit
  • the second input end is connected to the output end of the hardware device through the second sampling unit, and is used according to the first
  • the DC voltage or DC current collected by the sample unit from the DC system, and the AC voltage or AC current collected by the second sampling unit from the AC system determine the modulation wave;
  • the input end of the modulation unit is connected to the output end of the first control unit, based on The input carrier of the modulation unit and the modulated wave output by the first control unit are input to generate a switching signal for driving an on/off state of the switching device in the hardware device.
  • the modulated wave may be the first control unit or the upper computer input to the modulation unit.
  • the specific source of the modulated wave is not limited in the embodiment of the present application.
  • AC system may be a device or system capable of providing or dissipating AC power, for example, may be an AC bus in the power grid.
  • the DC system described above may be a device or system capable of providing or sinking DC power, for example, may be a DC power source or a DC load.
  • the phase of the input carrier of the input modulation unit affects the waveform of the switching signal actually output by the modulation unit, and each inverter receives a different switching signal output by the modulation unit.
  • the actual output voltage waveforms of different inverters are different.
  • the voltage difference between different voltage waveforms will affect the equivalent high-frequency voltage source of the system, and the signal frequency and inverter of the equivalent high-frequency voltage source of the system.
  • harmonic current will exist in the AC output of the inverter.
  • the harmonic current will affect the quality of the output power of the power supply system and even the stability of the power supply system.
  • the embodiment of the present application reduces the amplitude of the harmonic current output by the inverter by using a carrier synchronization method, that is, based on the harmonic
  • a carrier synchronization method that is, based on the harmonic
  • the first modulation unit is input to control the input carrier of the switching signal input to the first inverter (hereinafter referred to as a phase of the "input carrier corresponding to the first inverter"), and an input carrier that inputs the second modulation unit to control the switching signal of the second inverter (hereinafter referred to as "the input carrier corresponding to the second inverter")
  • the phase is the same, that is, when the phase difference is 0, the phase of the waveform of the high frequency voltage waveform outputted by the first inverter and the waveform of the high frequency voltage output by the second inverter are equal, and the alternating current of the second inverter outputs the harmonic
  • the amplitude of the wave current is approximately 0.
  • the specific current curve is shown in Fig. 4. It can be seen from the current curve of the alternating current i g1 outputted by the first inverter shown in Fig. 4 and the alternating current i g2 outputted by the second inverter.
  • the high frequency components in i g1 and i g2 (which can be used to represent the magnitude of the harmonic current) are small.
  • phase of the input carrier corresponding to the first inverter is opposite to the phase of the input carrier corresponding to the second inverter, that is, when the phase difference is ⁇ , the phase of the first inverter outputting the high-frequency voltage waveform and the second inverter
  • the phase difference of the phase of the waveform of the high-frequency voltage output by the device is ⁇ , and the amplitude of the harmonic current in the alternating current output by the second inverter is large.
  • the specific current curve is shown in FIG. 5, as shown in FIG.
  • the current curve of the alternating current i g1 of the first inverter and the alternating current i g2 of the second inverter can be seen as high frequency components in i g1 and i g2 (can be used to represent the magnitude of the harmonic current) Larger.
  • phase difference ⁇ of the input carrier and the amplitude i f of the harmonic current are as shown in FIG. 6 , and the following is an example of the input carrier corresponding to the first inverter and the input carrier corresponding to the second inverter.
  • the relationship between the phase difference of the input carrier and the magnitude of the harmonic current shown in FIG. 6 will be described.
  • the phase difference ⁇ between the phase of the input carrier corresponding to the first inverter and the phase of the input carrier corresponding to the second inverter is between [0, 2 ⁇ ] as an example, when the first inverter When the phase difference ⁇ between the phase of the corresponding input carrier and the phase of the input carrier corresponding to the second inverter is between [0, ⁇ ], the amplitude i f of the harmonic current output by the second inverter will As the phase difference ⁇ increases, the phase difference ⁇ between the phase of the input carrier corresponding to the first inverter and the phase of the input carrier corresponding to the second inverter is between [ ⁇ , 2 ⁇ ] At the time, the magnitude of the harmonic current output by the second inverter decreases as the phase difference ⁇ increases.
  • the method for carrier synchronization in the embodiment of the present application may be based on the phase difference ⁇ of the input carrier and the amplitude i f relationship of the harmonic current shown in FIG. 6 by adjusting the phase and the first of the input carrier corresponding to the first inverter.
  • the phase difference ⁇ between the phases of the input carriers corresponding to the two inverters is used to adjust the amplitude of the harmonic current.
  • the first inverter is an inverter that completes a carrier synchronization process with the power grid
  • the phase of the input carrier corresponding to the first inverter may be a fixed value ⁇ *
  • the above adjustment is performed by adjusting the first inverter.
  • the phase difference ⁇ between the phase of the input carrier and the phase of the input carrier corresponding to the second inverter is used to adjust the amplitude of the harmonic current output by the second inverter, which can be understood as adjusting the corresponding of the second inverter.
  • the phase of the carrier is input to adjust the magnitude of the harmonic current output by the second inverter.
  • the carrier synchronization apparatus shown in FIG. 7 can be understood as a device for performing carrier synchronization on the second inverter shown in FIG. 2, that is, a carrier in the power supply system for the inverter to be subjected to carrier synchronization. Synchronized device.
  • FIG. 7 is a schematic block diagram of an apparatus for carrier synchronization according to an embodiment of the present application.
  • the apparatus 700 shown in FIG. 7 includes a modulation unit 710, a current processing unit 720, and a control unit 730.
  • a modulation unit that generates a switching signal based on the input carrier and the modulated wave to control the switching device in the inverter
  • a current processing unit configured to acquire a magnitude of a first harmonic current output by the inverter and a magnitude of a second harmonic current, where the first harmonic current is the first carrier input of the input carrier
  • the modulation unit and the modulated wave generating switch signal when the switching device in the inverter is controlled, the harmonic current output by the inverter, the second harmonic current is the input carrier a second carrier is input to the modulation unit and the modulated wave generating switch signal, and when the switching device in the inverter is controlled, the harmonic current output by the inverter, wherein the phase of the first carrier Different from the phase of the second carrier;
  • a control unit configured to increase or decrease a phase of an input carrier input to the modulation unit according to a first change trend and a second change trend, such that a magnitude of a third harmonic current output by the inverter is less than a smaller of a magnitude of the first harmonic current and a magnitude of the second harmonic current, the first variation trend being a magnitude of the first harmonic current and the second harmonic a trend between the amplitudes of the wave currents, the second change trend being a trend between the phase of the first carrier and the phase of the second carrier, the third harmonic current being the input
  • the carrier of the modulation unit is an input carrier after the phase adjustment
  • the input carrier after the phase adjustment and the modulated wave generate a switching signal
  • the switching device in the inverter is controlled, the inverter outputs Harmonic current.
  • control unit may increase or decrease the phase of the input carrier input to the modulation unit according to the first change trend and the second change trend, as a phase of preparing the third carrier output from the controller, so that the input carrier is
  • the third carrier input modulation unit and the modulated wave generating switch signal when the switching device in the inverter is controlled, the amplitude of the third resonant current output by the inverter is smaller than the amplitude of the first resonant current and the second resonance The smaller value of the magnitude of the current.
  • the input carrier of the input modulation unit includes three variables: amplitude, frequency and phase.
  • the power supply system can cure the frequency of the input carrier via the clock in the control system, and the amplitude of the input carrier is normalized. Synchronize. At this point, the only uncertainty among the three variables of the input carrier is the initial phase of the carrier.
  • the startup of multiple parallel inverters in the power supply system is not synchronized, which will cause the initial phase of the carrier to be different, which will eventually lead to
  • the phases of the input carriers are not synchronized, that is, the carriers are not synchronized.
  • carrier synchronization in the embodiment of the present application can be understood as synchronizing the phase of the input carrier of the input modulation unit.
  • control unit may be a control unit for performing carrier synchronization.
  • the device 700 When the device 700 is disposed in the single-phase inverter 300, it may be independent of the first controller in the single-phase inverter, and may also be The embodiment of the present application is not specifically limited.
  • the embodiment of the present application is based on a change trend between the amplitude of the first harmonic current and the amplitude of the second harmonic current, and a change trend between the phase of the first carrier and the phase of the second carrier, and the input modulation unit
  • the phase of the input carrier is adjusted as the phase of the input carrier to be output from the controller to reduce the amplitude of the harmonic current output by the inverter, thereby improving the stability of the distributed power supply system.
  • the comparison between the carrier wave and the modulated wave may be based on a Pulse Width Modulation (PWM) technique.
  • PWM Pulse Width Modulation
  • the switching signal is at a high level.
  • the switching signal is low; or when the amplitude of the modulated wave is higher than the amplitude of the carrier, the switching signal is low, when the amplitude of the modulated wave is lower than the carrier The amplitude of the switch signal is high.
  • device 700 can be part of an inverter.
  • device 700 can be integrated with an inverter on a chip dedicated to carrier synchronization for the inverter
  • FIG. 3 shows a schematic block diagram of a single phase inverter integrated with device 700 on a single chip.
  • the device 700 can also be a carrier synchronization device located outside of the inverter.
  • the device 700 can also be a digital signal processor (DSP) built into the inverter.
  • DSP digital signal processor
  • control unit is further configured to: when the first change trend and the second change trend are the same, reduce a phase of an input carrier input to the modulation unit, the first change trend and a When the second change trend is reversed, the phase of the input carrier input to the modulation unit is increased.
  • first change trend and the second change trend are the same, and may mean that the second change trend increases as the first change trend increases, or decreases as the first change trend decreases;
  • the first change trend and the second change trend are opposite, and may mean that the second change trend decreases as the first change trend increases, or the second change trend increases as the first change trend decreases.
  • first change trend and the second change trend are the same, and the first change trend and the second change trend may fall within the monotonous increment interval shown in FIG. 6, and the first change trend and the second change trend are opposite.
  • the first change trend and the second change trend may fall within the monotonous decreasing interval shown in FIG. 6.
  • the first change trend is represented by i 1 -i 2 , where i 1 represents a magnitude of the first harmonic current, i 2 represents a magnitude of the second current; and the second change trend It is represented by ⁇ 1 - ⁇ 2 , where ⁇ 1 represents the phase of the first carrier and ⁇ 2 represents the phase of the second carrier.
  • the first change trend and the second change trend may be the same as the first change trend and the second change trend, that is, The first change trend and the second change trend are opposite, and may refer to the first change trend and the second change trend, that is,
  • control unit is further configured to: determine an adjustment step size, where the adjustment step is an adjustment step for increasing or decreasing a phase of the input carrier; according to the first change trend and The second variation trend is to increase or decrease the phase of the input carrier input to the modulation unit by the first adjustment step.
  • the adjustment step may be a fixed value.
  • the adjustment step may be a preset adjustment step.
  • the adjustment step may also be a change value.
  • the adjustment step may be the current output of the inverter.
  • the adjustment step size of the amplitude change of the harmonic current is not limited in the specific implementation form of the adjustment step size in the embodiment of the present application.
  • the first resonant current is a resonant current output by the current inverter
  • the control unit is further configured to: according to a formula And ⁇ ref >0, determining the adjustment step size, wherein ⁇ represents the adjustment step size, i f represents the amplitude of the first resonance current, and i N represents the rated current value of the inverter, ⁇ Ref denotes a reference value that determines the adjustment step size.
  • ⁇ ref represents a reference value for determining the adjustment step size, and may mean that ⁇ ref represents a reference phase for determining the adjustment step size.
  • ⁇ ref may be preset for determining the adjustment step reference value.
  • the first resonant current is a resonant current output by the current inverter
  • the control unit is further configured to: according to a formula And ⁇ ref >0, determining the adjustment step size, wherein ⁇ represents the adjustment step size, i f represents the amplitude of the first resonance current, and i N represents the rated current value of the inverter, ⁇ Ref represents an initial value determining the adjustment step size.
  • ⁇ ref represents a reference value for determining the adjustment step size, and may mean that ⁇ ref represents a reference phase for determining the adjustment step size.
  • ⁇ ref may be preset for determining the adjustment step reference value.
  • increasing the phase of the input carrier input to the modulation unit may refer to delaying the input carrier by a time period corresponding to a time adjustment value, where the phase of the input carrier input to the modulation unit is reduced. It may refer to a time period corresponding to the input carrier being adjusted in time by a time adjustment value.
  • the time adjustment value ⁇ t may be according to a formula. Where ⁇ represents the adjustment step size and f C represents the frequency of the input carrier.
  • the time adjustment value ⁇ t may be according to a formula. Where ⁇ represents the adjustment step size and f C represents the frequency of the input carrier.
  • control unit is further configured to: increase according to the change trend of the first change trend, the second change trend, and the amplitude of the harmonic current and the phase change of the input carrier. Or reducing the phase of the input carrier input to the modulation unit.
  • control unit may first input the phase of the input carrier input to the modulation unit according to the change trend of the first change trend, the second change trend, and the amplitude of the harmonic current and the change trend of the phase of the input carrier.
  • the phase is synchronized to an inverter (eg, the first inverter) that is synchronized with other carriers in the power supply system.
  • control unit is further configured to: according to the change trend of the first change trend, the second change trend, and the amplitude of the harmonic current and the change trend of the phase of the input carrier,
  • the adjustment step size is set to increase or decrease the phase of the input carrier input to the modulation unit.
  • the phase of the input carrier of the input modulation unit is iterated by a preset adjustment step, and the phase of the input carrier of the input modulation unit is gradually reduced until the inverse Change
  • the amplitude of the third harmonic current output by the device is smaller than a smaller value of the amplitude of the first harmonic current and the amplitude of the second harmonic current; when the first change trend and the second change trend are opposite,
  • the preset adjustment step length iterates the phase of the input carrier of the input modulation unit, and gradually increases the phase of the input carrier of the input modulation unit until the amplitude of the third harmonic current output by the inverter is smaller than the first The smaller of the magnitude of one harmonic current and the magnitude of the second harmonic current.
  • control unit includes: a logic determining unit, configured to determine the phase of an input carrier input to the modulation unit according to the first change trend and the second change trend; And means for increasing or decreasing the phase of the input carrier input to the modulation unit according to the determined phase of the input carrier input to the modulation unit.
  • control unit is further configured to: determine that a magnitude of the third harmonic current output by the inverter is lower than a current amplitude threshold, and then stop increasing or decreasing an input to the The phase of the input carrier of the modulation unit.
  • the phase of the input carrier input to the modulation unit may be stopped, and at this time, the input to the modulation unit may be determined.
  • the phase of the input carrier is synchronized with the phase of the carrier corresponding to the inverter (eg, the first inverter) that has achieved carrier synchronization in addition to the inverter in the power supply system.
  • the current magnitude threshold can be 1% of the inverter rated current.
  • the inverter is a single phase inverter or a three phase inverter.
  • the zero-sequence current is the phasor of the three-phase current in the three-phase inverter and the current generated when it is not zero, it belongs to the unique current in the three-phase inverter, and therefore, the carrier synchronization method is implemented according to the zero-sequence current. It is not applicable to a single-phase inverter, and the harmonic current in the embodiment of the present application is due to the presence of a resonance point (ie, a point having a small impedance) in a hardware circuit in the inverter, or a specific frequency in the power supply system.
  • the system excitation for example, the sideband signal
  • the method for adjusting the harmonic current of the embodiment of the present application is also applicable to A single-phase inverter is connected in parallel to form a power supply system.
  • the current processing unit is further configured to: perform current sampling on the alternating current output by the inverter to obtain a magnitude of the inverter output harmonic current.
  • the alternating current outputted by the inverter is sampled, and the alternating current is filtered to obtain a magnitude of a harmonic current having a frequency of a first frequency, the first frequency being a resonant frequency of the inverter.
  • the inverter includes inductors and capacitors in addition to the filter, the remaining components include the capacitance and inductance of the printed circuit board.
  • the inductance or capacitance is very small (also known as parasitic inductance or capacitance), which is usually negligible.
  • the resonant frequency of the inverter can mainly consider the resonant frequency of the capacitance and inductance in the filter in the inverter. That is to say, the above first frequency can be determined according to the resonant frequency of the capacitance and the inductance in the filter in the inverter.
  • the first frequency can be represented by f, then Determined, where L eq represents the equivalent inductance value of the filter and C eq represents the equivalent capacitance value of the filter.
  • the above filter for filtering the alternating current to obtain the harmonic current of the first frequency may be a digital filtering or an analog filter, wherein the digital filter may be filtered by a fast Fourier transform method, and the analog filter Specifically, it may be a band pass filter.
  • an embodiment of the present application provides an inverter system including a plurality of inverters, where the inverter system includes the apparatus 700 shown in FIG. 7 for controlling the plurality of inverters. Carrier synchronization.
  • the above-mentioned inverter system may include a plurality of inverters for controlling a target inverter and an inverter system connected to the device 700 among a plurality of inverters except the target inverter. Between other inverters Carrier synchronization process.
  • FIG. 7 only shows one inverter in the inverter system of the embodiment of the present application.
  • the embodiment of the present application does not specifically limit the number of inverters in the inverter system.
  • each inverter in the inverter system has a separate device 700, the specific device 700 and the inverter. See Figure 7 for the connection method.
  • the apparatus for carrier synchronization according to the embodiment of the present application is described in detail above with reference to FIG. 1 to FIG. 7.
  • the method for carrier synchronization in the embodiment of the present application is described in detail below with reference to FIG. It should be understood that the apparatus shown in FIG. 7 can implement various steps in the method shown in FIG. 8. To avoid repetition, details are not described herein again.
  • FIG. 8 is a schematic flowchart of a method for carrier synchronization according to an embodiment of the present application, where an apparatus for applying the method includes a modulation unit and an inverter, and the modulation unit generates a switch signal based on an input carrier and a modulated wave,
  • the switching device in the inverter performs control, and the method includes:
  • the inverter is a single phase inverter or a three phase inverter.
  • FIG. 8 shows detailed steps or operations for carrier synchronization, but these steps or operations are merely examples, and other operations may be performed by the embodiments of the present application, or variations of the operations in FIG. Moreover, the various steps in FIG. 8 may be performed in a different order than that presented in FIG. 8, and it is possible that not all of the operations in FIG. 8 are to be performed. The method steps shown in Fig. 8 are specifically described below.
  • the embodiment of the present application is based on a change trend between the amplitude of the first harmonic current and the amplitude of the second harmonic current, and a change trend between the phase of the first carrier and the phase of the second carrier, and the input modulation unit
  • the phase of the input carrier is adjusted to reduce the amplitude of the harmonic current output by the inverter and improve the stability of the distributed power supply system.
  • step 820 further includes: reducing a phase of an input carrier input to the modulation unit when the first change trend and the second change trend are the same, the first change trend and the When the second change trend is reversed, the phase of the input carrier input to the modulation unit is increased.
  • the first change trend is represented by i 1 -i 2 , where i 1 represents a magnitude of the first harmonic current, i 2 represents a magnitude of the second current; and the second change trend It is represented by ⁇ 1 - ⁇ 2 , where ⁇ 1 represents the phase of the first carrier and ⁇ 2 represents the phase of the second carrier.
  • the first change trend and the second change trend may be the same as the first change trend and the second change trend, that is, The first change trend and the second change trend are opposite, and may refer to the first change trend and the second change trend, that is,
  • control unit is further configured to: determine an adjustment step size, where the adjustment step is an adjustment step for increasing or decreasing a phase of the input carrier; according to the first change trend and The second variation trend is to increase or decrease the phase of the input carrier input to the modulation unit by the first adjustment step.
  • the first resonant current is a resonant current output by the current inverter
  • the control unit is further configured to: according to a formula And ⁇ ref >0, determining the adjustment step size, wherein ⁇ represents the adjustment step size, i f represents the amplitude of the first resonance current, and i N represents the rated current value of the inverter, ⁇ Ref denotes a reference value that determines the adjustment step size.
  • the first resonant current is a resonant current output by the current inverter
  • the control unit is further configured to: according to a formula And ⁇ ref >0, determining the adjustment step size, wherein ⁇ represents the adjustment step size, i f represents the amplitude of the first resonance current, and i N represents the rated current value of the inverter, ⁇ Ref represents an initial value determining the adjustment step size.
  • increasing the phase of the input carrier input to the modulation unit may refer to delaying the input carrier by a time period corresponding to a time adjustment value, where the phase of the input carrier input to the modulation unit is reduced. It may refer to a time period corresponding to the input carrier being adjusted in time by a time adjustment value.
  • the time adjustment value ⁇ t may be according to a formula. Where ⁇ represents the adjustment step size and f C represents the frequency of the input carrier.
  • the time adjustment value ⁇ t may be according to a formula. Where ⁇ represents the adjustment step size and f C represents the frequency of the input carrier.
  • step 820 further includes: increasing or decreasing the input according to the first change trend, the second change trend, and a change trend of the amplitude of the harmonic current and a change trend of the phase of the input carrier.
  • phase of the input carrier input to the modulation unit is adjusted to other carriers already in the power supply system at a time.
  • Phase synchronization of a synchronized inverter eg, a first inverter
  • the step 820 further includes: according to the first change trend, the second change trend, and a change trend of the amplitude of the harmonic current and a change trend of the phase of the input carrier, with a preset adjustment step. Long, increasing or decreasing the phase of the input carrier input to the modulation unit.
  • step 820 further includes: determining the phase of the input carrier input to the modulation unit according to the first change trend and the second change trend; inputting to the modulation unit according to the determined input
  • the phase of the input carrier increases or decreases the phase of the input carrier input to the modulation unit.
  • the method further includes determining that a magnitude of the third harmonic current output by the inverter is lower than a current amplitude threshold, and then stopping increasing or decreasing input to the modulation unit The phase of the input carrier.
  • the "input carrier corresponding to the second inverter" described hereinafter may refer to a modulated wave in the modulation unit.
  • a switching signal is generated to control an input carrier of a switching device in the second inverter.
  • FIG. 9 is a schematic flowchart of a method for carrier synchronization according to an embodiment of the present application. It should be understood that the method shown in FIG. 9 is based on the distributed power supply system shown in FIG. 2, wherein the first inverter may be an inverter that has completed carrier synchronization, and the second inverter may be required to perform carrier synchronization. Inverter.
  • the method shown in Figure 9 includes:
  • the frequency of the above harmonic current may be Determined, where L eq represents the equivalent inductance value of the filter and C eq represents the equivalent capacitance value of the filter.
  • determining whether the current control period is the initial control period in which the second inverter performs carrier synchronization may be classified into the following two cases:
  • the current control period is an initial control period in which the second inverter performs self-carrier synchronization
  • the phase of the corresponding input carrier of the second inverter in the current control period may be marked as ⁇ 0 and is the second inverse.
  • the transformer configures a preset initial phase ⁇ 1 on the input carrier corresponding to the next control cycle, and then performs step 950.
  • the phase ⁇ 0 of the input carrier corresponding to the inverter may be randomly selected, or may be a preset fixed value, and the specific selection manner of the initial phase is not used in the embodiment of the present application. limited.
  • the phase ⁇ 1 of the input carrier corresponding to the inverter may also be randomly selected, or may be a preset fixed value.
  • step 930 is performed.
  • control period may include at least one switching period.
  • the amplitude of the harmonic current is less than or equal to the current amplitude threshold, it may be determined that the phase of the corresponding carrier of the second inverter is approximately synchronous with the phase of the carrier in the power supply system, and the corresponding carrier of the second inverter may be stopped. For the phase, go to step 950.
  • step 940 the magnitude of the harmonic current is greater than the current amplitude threshold, and step 940 is performed.
  • step 940 Since the amplitude of the harmonic current is greater than the current amplitude threshold, it can be determined that the current harmonic current is still likely to affect the stability of the system, and the amplitude of the harmonic current needs to be adjusted, and step 940 is performed.
  • the current control period is the nth control period, then one control period before the current control period is represented by n-1, and so on.
  • One control period before the n-1th control period is represented by n-2, the current control A control period after the period can be represented by n+1.
  • the amplitude of the harmonic current output by the inverter in the nth control period is i n
  • the amplitude of the harmonic current output by the inverter in the n-1th control period is i n-1
  • the control period The phase of the input carrier corresponding to the second inverter is ⁇ n-1
  • the amplitude of the harmonic current output by the inverter in the n-2th control period is i n-2
  • the phase of the input carrier corresponding to the inverter is ⁇ n-2 .
  • the trend of the magnitude of the harmonic current can be expressed as i n -i n-1
  • the trend of the phase of the carrier can be expressed as ⁇ n - ⁇ n-1 .
  • the n + 1 cycle control input of a second inverter corresponding to the carrier phase [theta] n + 1 input carrier phase [theta] n n-th control period corresponding to the second inverter The trend of change can be determined from i n -i n-1 and ⁇ n - ⁇ n-1 .
  • the above determining the phase of the carrier in the n+1th control period can be specifically divided into two cases:
  • i n -i n-1 When the change trend of i n -i n-1 is opposite to the change trend of ⁇ n - ⁇ n-1 , It can be determined that i n -i n-1 and ⁇ n - ⁇ n-1 are within the monotonically decreasing interval in the curve shown in FIG. 5, at this time, the phase of the carrier and the nth control period in the n+1th control period.
  • the trend between the phases of the medium carriers may be an increasing trend, that is, ⁇ n+1 > ⁇ n .
  • control cycle ends and enters the next control cycle.
  • the adjustment of the phase of the input carrier in the nth control period is ended, and the n+1th control period is entered.
  • B corresponding to A means that B is associated with A, and B can be determined according to A.
  • determining B from A does not mean that B is only determined based on A, and that B can also be determined based on A and/or other information.
  • the size of the sequence numbers of the foregoing processes does not mean the order of execution sequence, and the order of execution of each process should be determined by its function and internal logic, and should not be applied to the embodiment of the present application.
  • the implementation process constitutes any limitation.
  • the disclosed systems, devices, and methods may be implemented in other manners.
  • the device embodiments described above are merely illustrative.
  • the division of the unit is only a logical function division.
  • there may be another division manner for example, multiple units or components may be combined or Can be integrated into another system, or some features can be ignored or not executed.
  • the mutual coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection through some interface, device or unit, and may be in an electrical, mechanical or other form.
  • the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of the embodiment.
  • each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.
  • the computer program product includes one or more computer instructions.
  • the computer can be a general purpose computer, a special purpose computer, a computer network, or other programmable device.
  • the computer instructions can be stored in a computer readable storage medium or transferred from one computer readable storage medium to another computer readable storage medium, for example, the computer instructions can be from a website site, computer, server or data center By wire (for example coaxial Cable, fiber, Digital Subscriber Line (DSL) or wireless (eg infrared, wireless, microwave, etc.) to another website, computer, server or data center.
  • the computer readable storage medium can be any available media that can be read by a computer or a data storage device such as a server, data center, or the like that includes one or more available media.
  • the usable medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a Digital Video Disc (DVD)), or a semiconductor medium (eg, a Solid State Disk (SSD)). )Wait.
  • a magnetic medium eg, a floppy disk, a hard disk, a magnetic tape
  • an optical medium eg, a Digital Video Disc (DVD)
  • DVD Digital Video Disc
  • SSD Solid State Disk

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Abstract

一种用于载波同步的装置（700）、逆变系统和方法，该装置（700）包括：调制单元（710），电流处理单元（720），和控制单元（730），其中控制单元（730）可以根据第一谐波电流的幅值和第二谐波电流的幅值之间的变化趋势，以及第一载波的相位和第二载波的相位之间的变化趋势，对输入调制单元（710）的输入载波的相位进行调整，以减小逆变器输出的谐波电流的幅值，提高分布式供电系统（200）的稳定性，避免了使用基于零序电流进行载波同步的过程中，无法通过载波同步减少谐波电流对供电系统的影响，提高分布式系统的稳定性。

Description

用于载波同步的装置、逆变系统和方法 技术领域
本申请涉及电源技术领域，并且更具体地，涉及用于载波同步的装置、逆变系统和方法。
背景技术
随着供电系统供电容量的不断扩大，供电系统所需要的逆变器容量及数量也越来越大，在大型供电系统中通常采用多逆变器并联的方式来提高供电系统的供电容量。若供电系统中并联的各逆变器之间载波不同步，则有可能会产生环流以及谐波电流，损害逆变器输出的电能质量甚至是危及供电系统的稳定性。因此，载波同步是供电系统稳定运行的基本条件之一。
目前的载波同步方法主要应用于通过通讯线(例如，总线)相连的多个并联逆变器构成的供电系统，也就是说，多个并联的逆变器之间通过通讯线相连，并且上述多个并联的逆变器之间通过相连的通讯线发送的载波同步信号进行载波同步。然而，这种多个并联的逆变器之间需要通过通讯线连接的连接方式，使得现场布线复杂且难以实现，尤其是当通讯线上存在故障或干扰时，无法实现逆变器之间的载波同步功能。
为了克服基于通讯线的逆变器并联供电系统在进行载波同步时的上述困难，无通讯线的逆变器并联供电系统受到越来越多的关注。然而，目前应用于无通讯线的逆变器并联供电系统中的载波同步方法是针对集中式三相供电系统而言的。从图1所示的集中式三相供电系统100的示意性框图可以看出，在集中式三相供电系统中，各并联的三相逆变器的直流输入端都连接在相同的直流母线上，这种逆变器的并联方式使得相邻逆变器之间的零序环流对供电系统的稳定性影响较大，因此，在集中式三相供电系统中是根据各并联的逆变器之间产生的零序环流调整各个逆变器输出的载波的相位，以实现载波同步的。
然而，在分布式供电系统中，各逆变器中相邻逆变器之间的距离通常设置较远，并且各逆变器的直流输入端之间相互独立，这种逆变器的并联方式使得零序环流对分布式供电系统的稳定性影响较小，而影响分布式供电系统的稳定性的因素主要是系统谐波电流，因此，如果仍然采用上述集中式三相供电系统中的载波同步方法，无法有效提高分布式供电系统的稳定性。
发明内容
本申请实施例提供一种用于载波同步的装置、逆变系统和方法，以提高分布式供电系统的稳定性。
第一方面，提供一种用于载波同步的装置，包括：调制单元，基于输入载波和调制波生成开关信号，对逆变器中的开关器件进行控制；电流处理单元，用于获取所述逆变器输出的第一谐波电流的幅值和第二谐波电流的幅值，所述第一谐波电流为所述输入载波为第一载波输入所述调制单元和所述调制波生成开关信号，对所述逆变器中的开关器件进行控制时，所述逆变器输出的谐波电流，所述第二谐波电流为所述输入载波为第二 载波输入所述调制单元和所述调制波生成开关信号，对所述逆变器进行控制时，所述逆变器输出的谐波电流，其中所述第一载波的相位和所述第二载波的相位不同；控制单元，用于根据第一变化趋势和第二变化趋势，增大或减小输入至所述调制单元的输入载波的相位，使得所述逆变器输出的第三谐波电流的幅值小于所述第一谐波电流的幅值和所述第二谐波电流的幅值中的较小值，所述第一变化趋势为所述第一谐波电流的幅值和所述第二谐波电流的幅值之间的变化趋势，所述第二变化趋势为所述第一载波的相位和所述第二载波的相位之间的变化趋势，所述第三谐波电流为输入所述调制单元的载波为调整相位后的输入载波时，所述调整相位后的输入载波与所述调制波生成开关信号，对所述逆变器中的开关器件进行控制时，所述逆变器输出的谐波电流。
本申请实施例根据第一谐波电流的幅值和第二谐波电流的幅值之间的变化趋势，以及第一载波的相位和第二载波的相位之间的变化趋势，对输入调制单元的输入载波的相位进行调整，以减小逆变器输出的谐波电流的幅值，提高分布式供电系统的稳定性。
进一步地，避免了使用现有技术中基于零序电流进行载波同步的过程中，无法通过载波同步减少谐波电流对供电系统的影响，以提高分布式系统的稳定性。
结合第一方面，在第一方面的某些实现方式中，所述控制单元用于：所述第一变化趋势和所述第二变化趋势相同时，减小输入至所述调制单元的输入载波的相位，所述第一变化趋势和所述第二变化趋势相反时，增大输入至所述调制单元的输入载波的相位。
根据第一变化趋势和第二变化趋势，增大或减小输入至所述调制单元的输入载波的相位，无需将第一变化趋势和第二变化趋势之间的映射关系预存在控制器中，降低对控制器在存储方面的要求。
在一些实现方式中，所述第一变化趋势通过i1-i2表示，其中，i1表示第一谐波电流的幅值，i2表示第二电流的幅值；所述第二变化趋势通过θ1-θ2表示，其中，θ1表示第一载波的相位，θ2表示第二载波的相位。
在一些实现方式中，上述第一变化趋势和第二变换趋势相同可以指第一变化趋势和第二变化趋势同号，即
Figure PCTCN2017085805-appb-000001
上述第一变化趋势和第二变化趋势相反，可以指第一变化趋势和第二变化趋势异号，即
Figure PCTCN2017085805-appb-000002
结合第一方面，在第一方面的某些实现方式中，所述控制单元还用于：确定调整步长，所述调整步长为增大或减小所述输入载波的相位的调整步长；根据所述第一变化趋势和所述第二变化趋势，以所述第一调整步长，增大或减小输入至所述调制单元的输入载波的相位。
结合第一方面，在第一方面的某些实现方式中，所述第一谐振电流为当前所述逆变器输出的谐振电流，所述控制单元还用于：根据公式
Figure PCTCN2017085805-appb-000003
且θref>0，确定所述调整步长，其中，Δθ表示所述调整步长，if表示所述第一谐振电流的幅值，iN表示所述逆变器的额定电流值，θref表示确定所述调整步长的参考值。
通过分段地设置调整步长，以对输入载波的相位进行调整，有利于提高调整输入载波的相位的效率。
结合第一方面，在第一方面的某些实现方式中，所述第一谐振电流为当前所述逆变器输出的谐振电流，所述控制单元还用于：根据公式
Figure PCTCN2017085805-appb-000004
且θref>0，确定所述 调整步长，其中，Δθ表示所述调整步长，if表示所述第一谐振电流的幅值，iN表示所述逆变器的额定电流值，θref表示确定所述调整步长的初始值。
通过将调整步长设置为可以根据第一谐振电流的幅值变化，以对输入载波的相位进行调整，有利于提高调整输入载波的相位的效率。
在一些实施例中，上述增大输入至调制单元的输入载波的相位，可以指将输入载波在时间上延迟一个时间调整值对应的时间段，上述减小输入至调制单元的输入载波的相位，可以指将输入载波在时间上提前一个时间调整值对应的时间段。
在一些实施例中，若调整步长Δθ的单位为度时，上述时间调整值Δt可以根据公式
Figure PCTCN2017085805-appb-000005
其中，Δθ表示调整步长，fC表示输入载波的频率。
在一些实施例中，若调整步长Δθ的单位为弧度(rad)时，上述时间调整值Δt可以根据公式
Figure PCTCN2017085805-appb-000006
其中，Δθ表示调整步长，fC表示输入载波的频率。
结合第一方面，在第一方面的某些实现方式中，所述控制单元还用于：根据所述第一变化趋势、所述第二变化趋势以及谐波电流的幅值的变化趋势和输入载波的相位的变化趋势，增大或减小输入至所述调制单元的输入载波的相位。
根据第一变化趋势和第二变化趋势之间的映射关系，通过一次调整输入至所述调制单元的输入载波的相位，使得逆变器输出的第三谐波电流的幅值小于所述第一谐波电流的幅值和所述第二谐波电流的幅值中的较小值，简化对输入载波的相位的调整过程。
在一些实现方式中，所述控制单元具体还用于：根据所述第一变化趋势、所述第二变化趋势以及谐波电流的幅值的变化趋势和输入载波的相位的变化趋势，以预设的调整步长，增大或减小输入至所述调制单元的输入载波的相位。
根据第一变化趋势和第二变化趋势之间的映射关系，以预设的调整步长，逐步调整输入至所述调制单元的输入载波的相位，细化对输入载波的相位的调整过程，使得输入载波的相位调整过程更加精确。
结合第一方面，在第一方面的某些实现方式中，所述控制单元包括：逻辑判断单元，用于根据所述第一变化趋势和所述第二变化趋势，确定输入至所述调制单元的输入载波的所述相位；移相单元，用于根据确定的输入至所述调制单元的输入载波的所述相位，增大或减小输入至所述调制单元的输入载波的相位。
结合第一方面，在第一方面的某些实现方式中，所述逆变器为单相逆变器或三相逆变器。
在一些实现方式中，上述电流幅值阈值可以为逆变器额定电流的1％。
在一些实施例中，所述电流处理单元还用于：对所述逆变器输出的交流电进行电流采样，获取所述逆变器输出谐波电流的幅值。
第二方面，提供一种逆变系统，包括若干逆变器，所述逆变系统包括上述第一方面中任一种实现方式描述的装置，所述装置用于控制所述若干逆变器的载波同步。
本申请实施例根据第一谐波电流的幅值和第二谐波电流的幅值之间的变化趋势，以及第一载波的相位和第二载波的相位之间的变化趋势，对输入调制单元的输入载波的相位进行调整，以减小逆变器输出的谐波电流的幅值，提高分布式供电系统的稳定性。
进一步地，避免了使用现有技术中基于零序电流进行载波同步的过程中，无法通过载波同步减少谐波电流对供电系统的影响，以提高分布式系统的稳定性。
第三方面，提供一种用于载波同步的方法，应用所述方法的装置包括调制单元和逆 变器，所述调制单元，基于输入载波和调制波生成开关信号，对所述逆变器中的开关器件进行控制，所述方法包括：获取所述逆变器输出的第一谐波电流的幅值和第二谐波电流的幅值，所述第一谐波电流为所述输入载波为第一载波输入所述调制单元和所述调制波生成开关信号，对所述逆变器中的开关器件进行控制时，所述逆变器输出的谐波电流，所述第二谐波电流为输入载波为第二载波输入所述调制单元和所述调制波生成开关信号，对所述逆变器中的开关器件进行控制时，所述逆变器输出的谐波电流，其中所述第一载波和所述第二载波的相位不同；根据第一变化趋势和第二变化趋势，增大或减小输入至所述调制单元的输入载波的相位，使得所述逆变器输出的第三谐波电流的幅值小于所述第一谐波电流的幅值和第二谐波电流的幅值中的较小值，所述第一变化趋势为所述第一谐波电流的幅值和所述第二谐波电流的幅值之间的变化趋势，所述第二变化趋势为所述第一载波的相位和所述第二载波的相位之间的变化趋势，所述第三谐波电流为输入所述调制单元的载波为增大或减小相位后的输入载波时，所述增大或减小相位后的输入载波与所述调制波生成开关信号，对所述逆变器中的开关器件进行控制时，所述逆变器输出的谐波电流。
本申请实施例根据第一谐波电流的幅值和第二谐波电流的幅值之间的变化趋势，以及第一载波的相位和第二载波的相位之间的变化趋势，对输入调制单元的输入载波的相位进行调整，以减小逆变器输出的谐波电流的幅值，提高分布式供电系统的稳定性。
进一步地，避免了使用现有技术中基于零序电流进行载波同步的过程中，无法通过载波同步减少谐波电流对供电系统的影响，以提高分布式系统的稳定性。
结合第三方面，在第三方面的某些实现方式中，所述根据第一变化趋势和第二变化趋势，增大或减小输入至所述调制单元的输入载波的相位，包括：所述第一变化趋势和所述第二变化趋势相同时，减小输入至所述调制单元的输入载波的相位，所述第一变化趋势和所述第二变化趋势相反时，增大输入至所述调制单元的输入载波的相位。
根据第一变化趋势和第二变化趋势，增大或减小输入至所述调制单元的输入载波的相位，无需将第一变化趋势和第二变化趋势之间的映射关系预存在控制器中，降低对控制器在存储方面的要求。
在一些实现方式中，所述第一变化趋势通过i1-i2表示，其中，i1表示第一谐波电流的幅值，i2表示第二电流的幅值；所述第二变化趋势通过θ1-θ2表示，其中，θ1表示第一载波的相位，θ2表示第二载波的相位。
在一些实现方式中，上述第一变化趋势和第二变换趋势相同可以指第一变化趋势和第二变化趋势同号，即
Figure PCTCN2017085805-appb-000007
上述第一变化趋势和第二变化趋势相反，可以指第一变化趋势和第二变化趋势异号，即
Figure PCTCN2017085805-appb-000008
结合第三方面，在第三方面的某些实现方式中，所述方法还包括：确定调整步长，所述调整步长为增大或减小所述输入载波的相位的调整步长；所述根据第一变化趋势和第二变化趋势，增大或减小输入至所述调制单元的输入载波的相位，还包括：根据所述第一变化趋势和所述第二变化趋势，以所述调整步长，增大或减小输入至所述调制单元的输入载波的相位。
结合第三方面，在第三方面的某些实现方式中，所述第一谐振电流为当前所述逆变器输出的谐振电流，所述确定调整步长，包括：根据公式
Figure PCTCN2017085805-appb-000009
且θref>0，确定所述调整步长，其中，Δθ表示所述调整步长，if表示所述第一谐振电流的幅值，iN表示所述逆变器的额定电流值，θref表示确定所述调整步长的参考值。
通过将调整步长设置为可以根据第一谐振电流的幅值变化，以对输入载波的相位进行调整，有利于提高调整输入载波的相位的效率。
结合第三方面，在第三方面的某些实现方式中，所述第一谐振电流为当前所述逆变器输出的谐振电流，所述确定调整步长，包括：根据公式
Figure PCTCN2017085805-appb-000010
且θref>0，确定所述调整步长，其中，Δθ表示所述调整步长，if表示所述第一谐振电流的幅值，iN表示所述逆变器的额定电流值，θref表示确定所述调整步长的参考值。
通过将调整步长设置为可以根据第一谐振电流的幅值变化，以对输入载波的相位进行调整，有利于提高调整输入载波的相位的效率。
在一些实施例中，上述增大输入至调制单元的输入载波的相位，可以指将输入载波在时间上延迟一个时间调整值对应的时间段，上述减小输入至调制单元的输入载波的相位，可以指将输入载波在时间上提前一个时间调整值对应的时间段。
在一些实施例中，若调整步长Δθ的单位为度时，上述时间调整值Δt可以根据公式
Figure PCTCN2017085805-appb-000011
其中，Δθ表示调整步长，fC表示输入载波的频率。
在一些实施例中，若调整步长Δθ的单位为弧度(rad)时，上述时间调整值Δt可以根据公式
Figure PCTCN2017085805-appb-000012
其中，Δθ表示调整步长，fC表示输入载波的频率。
结合第三方面，在第三方面的某些实现方式中，所述根据第一变化趋势和第二变化趋势，增大或减小输入至所述调制单元的输入载波的相位，还包括：根据所述第一变化趋势、所述第二变化趋势以及所述谐波电流的幅值的变化趋势和输入载波的相位的变化趋势之间的映射关系，增大或减小输入至所述调制单元的输入载波的相位。
根据谐波电流的幅值的变化趋势和输入载波的相位的变化趋势之间的映射关系，通过一次调整输入至所述调制单元的输入载波的相位，使得逆变器输出的第三谐波电流的幅值小于所述第一谐波电流的幅值和所述第二谐波电流的幅值中的较小值，简化对输入载波的相位的调整过程。
结合第三方面，在第三方面的某些实现方式中，所述根据第一变化趋势和第二变化趋势，增大或减小输入至所述调制单元的输入载波的相位，还包括：根据所述第一变化趋势、所述第二变化趋势以及谐波电流的幅值的变化趋势和输入载波的相位的变化趋势，以预设的调整步长，增大或减小输入至所述调制单元的输入载波的相位。
根据谐波电流的幅值的变化趋势和输入载波的相位的变化趋势之间的映射关系，以预设的调整步长，逐步调整输入至所述调制单元的输入载波的相位，细化对输入载波的相位的调整过程，使得输入载波的相位调整过程更加精确。
结合第三方面，在第三方面的某些实现方式中，所述根据第一变化趋势和第二变化趋势，对输入至所述调制单元的输入载波的相位进行调整，包括：根据所述第一变化趋势和所述第二变化趋势，确定输入至所述调制单元的输入载波的所述相位；用于根据确定的输入至所述调制单元的输入载波的所述相位，增大或减小输入至所述调制单元的输入载波的相位。
在一些实现方式中，上述电流幅值阈值可以为逆变器额定电流的1％。
在一些实施例中，所述方法还包括：对所述逆变器输出的交流电进行电流采样，获取所述逆变器输出谐波电流的幅值。
结合第三方面，在第三方面的某些实现方式中，所述逆变器为单相逆变器或三相逆变器。
第四方面，提供一种计算机可读介质，所述计算机可读介质存储用于计算设备执行的程序代码，所述程序代码包括用于执行第二方面中的方法的指令。
第五方面，提供一种包含指令的计算机程序产品，当其在计算机上运行时，使得计算机执行第二方面所述的方法。
本申请提供的技术方案有利于提高分布式供电系统的稳定性。
附图说明
图1是集中式三相供电系统100的示意性框图。
图2是本申请实施例的分布式供电系统的示意性框图。
图3是本申请实施例的单相逆变器的示意性框图。
图4是本申请实施例的供电系统中第一逆变器和第二逆变器输出电流曲线的示意图。
图5是本申请实施例的供电系统中第一逆变器和第二逆变器输出电流曲线的示意图。
图6是本申请实施例中输入载波的相位差Δθ和谐波电流的幅值if关系的示意图。
图7是本申请实施例的用于载波同步的装置的示意性框图。
图8是本申请实施例的用于载波同步的方法的示意性流程图。
图9是本申请实施例的用于载波同步的方法的示意性流程图。
具体实施方式
下面将结合附图，对本申请中的技术方案进行描述。
为了便于理解，先简单介绍本申请实施例的应用场景。
图2是本申请实施例的分布式供电系统的示意性框图。图2所示的分布式供电系统200包括：第一逆变器210，第二逆变器220和交流母线。第一逆变器210和第二逆变器220的输出端分别与相同的交流母线相连，第一逆变器和第二逆变器可以共同为电网提供交流电，并且为第一逆变器提供直流电的直流源和为第二逆变器提供直流电的直流源之间相互独立。
需要说明的是，图2所示的分布式三相供电系统仅仅是以两台逆变器并联连接方式进行说明，本申请实施例对于分布式三相供电系统中并联的逆变器数量不作具体限定。
在图2所示的分布式三相供电系统中，逆变器可以是单相逆变器或者三相逆变器。下文结合图3简单介绍单相逆变器的结构。
图3是本申请实施例的单相逆变器的示意性框图。图3所示的单相逆变器300包括直流系统、交流系统、硬件装置、第一控制单元、采样单元和调制单元。
直流系统的第一输入端与硬件装置的第一输入端相连，用于向硬件装置提供直流电能；硬件装置的输出端可以与电网的交流母线相连，硬件装置包括电容、电感、电阻、半导体开关器件以及继电器等装置，用于将直流母线中获取的直流电能逆变为交流电，并向交流母线输出；第一控制单元的第一输入端通过第一采样单元与直流系统相连，第一控制单元的第二输入端通过第二采样单元与硬件装置的输出端相连，用于根据第一采 样单元从直流系统中采集的直流电压或直流电流，以及第二采样单元从交流系统中采集的交流电压或交流电流确定调制波；调制单元的输入端与第一控制单元的输出端相连，基于输入调制单元的输入载波与第一控制单元输出的调制波，生成用于驱动硬件装置中的开关器件的通断状态的开关信号。
需要说明的是，上述调制波可以是第一控制单元或者上位机输入至调制单元。本申请实施例对于调制波的具体来源不作限定。
应理解，上述交流系统可以是能够提供或消纳交流电的装置或系统，例如，可以是电网中的交流母线。
还应理解，上述直流系统可以是能够提供或消纳直流电能的装置或系统，例如，可以是直流电源或直流负载。
然而，当多台逆变器并联于交流母线时，输入调制单元的输入载波的相位会影响到调制单元实际输出的开关信号的波形，而各逆变器由于接收调制单元输出的不同的开关信号，导致不同各逆变器实际输出电压波形不同，不同的电压波形之间的电压差会影响到系统的等效高频电压源，而当系统的等效高频电压源的信号频率与逆变器中电感、电容等硬件装置的自然谐振频率接近时，则逆变器输出的交流电中会存在谐波电流，谐波电流会影响供电系统输出电能的质量，甚至危害供电系统的稳定性。
为了减小谐波电流对供电系统输出电能的质量以及供电系统稳定性的影响，本申请实施例通过载波同步的方法以减少逆变器输出的谐波电流的幅值，也就是说，基于谐波电流幅值与输入调制单元的输入载波的相位之间的变化趋势，调节谐波电流的幅值。
下文结合图2，简单介绍谐波电流幅值与输入调制单元的输入载波的相位之间的关系。
通过实验发现，当第一逆变器完成载波同步后，需要对第二逆变器进行载波同步时，若输入第一调制单元以控制输入第一逆变器的开关信号的输入载波(以下简称“第一逆变器对应的输入载波”)的相位，和输入第二调制单元以控制第二逆变器的开关信号的输入载波(以下简称“第二逆变器对应的输入载波”)的相位相同，即相位差为0时，第一逆变器输出高频电压波形的相位和第二逆变器输出的高频电压的波形的相位相等，则第二逆变器输出的交流电中谐波电流的幅值近似为0，具体的电流曲线参见图4，从图4所示的第一逆变器输出的交流电ig1和第二逆变器输出的交流电ig2的电流曲线可以看出，ig1和ig2中的高频分量(可以用于表示谐波电流的幅值)较小。
若第一逆变器对应的输入载波的相位和第二逆变器对应的输入载波的相位相反，即相位差为π时，第一逆变器输出高频电压波形的相位和第二逆变器输出的高频电压的波形的相位的相位差为π，则第二逆变器输出的交流电中的谐波电流的幅值较大，具体的电流曲线参见图5，从图5所示的第一逆变器输出的交流电ig1和第二逆变器输出的交流电ig2的电流曲线可以看出，ig1和ig2中的高频分量(可以用于表示谐波电流的幅值)较大。
从实验中发现，输入载波的相位差Δθ和谐波电流的幅值if关系如图6所示，下面以第一逆变器对应的输入载波和第二逆变器对应的输入载波为例，对图6所示的输入载波的相位差和谐波电流的幅值之间的关系进行说明。
从图6所示的输入载波的相位差Δθ和谐波电流的幅值if关系的示意图中，可以看出输入载波的相位差Δθ和谐波电流的幅值if之间呈现周期性的局部单调特性。下文以第一逆变器对应的输入载波的相位和第二逆变器对应的输入载波的相位之间的相位差Δθ在[0,2π]之间为例进行说明，当第一逆变器对应的输入载波的相位和第二逆变器对应的输入载波的相位之间的相位差Δθ在[0，π]之间时，第二逆变器输出的谐波电流的幅值if会随着 相位差Δθ的增大而增大；当第一逆变器对应的输入载波的相位和第二逆变器对应的输入载波的相位之间的相位差Δθ在[π，2π]之间时，第二逆变器输出的谐波电流的幅值会随着相位差Δθ的增大而减小。
因此，本申请实施例的载波同步的方法可以基于图6所示的输入载波的相位差Δθ和谐波电流的幅值if关系，通过调节第一逆变器对应的输入载波的相位和第二逆变器对应的输入载波的相位之间相位差Δθ，以调节谐波电流的幅值。
进一步地，由于第一逆变器是与电网完成载波同步过程的逆变器，第一逆变器对应的输入载波的相位可以是定值θ＊，则上述通过调节第一逆变器对应的输入载波的相位和第二逆变器对应的输入载波的相位之间相位差Δθ，以调节第二逆变器输出的谐波电流的幅值，可以理解为通过调节第二逆变器对应的输入载波的相位，以调节第二逆变器输出的谐波电流的幅值。
基于上述图6所示的输入载波的相位差Δθ和谐波电流的幅值if关系的示意图，结合图7，详细描述本申请实施例的用于载波同步的装置。为了便于理解，图7所示的用于载波同步装置可以理解为对图2中所示的第二逆变器进行载波同步的装置，即供电系统中为对待进行载波同步的逆变器进行载波同步的装置。
图7是本申请实施例的用于载波同步的装置的示意性框图。图7所示的装置700包括：调制单元710，电流处理单元720，和控制单元730。
调制单元，基于输入载波和调制波生成开关信号，对逆变器中的开关器件进行控制；
电流处理单元，用于获取所述逆变器输出的第一谐波电流的幅值和第二谐波电流的幅值，所述第一谐波电流为所述输入载波为第一载波输入所述调制单元和所述调制波生成开关信号，对所述逆变器中的开关器件进行控制时，所述逆变器输出的谐波电流，所述第二谐波电流为所述输入载波为第二载波输入所述调制单元和所述调制波生成开关信号，对所述逆变器中的开关器件进行控制时，所述逆变器输出的谐波电流，其中所述第一载波的相位和所述第二载波的相位不同；
控制单元，用于根据第一变化趋势和第二变化趋势，增大或减小输入至所述调制单元的输入载波的相位，使得所述逆变器输出的第三谐波电流的幅值小于所述第一谐波电流的幅值和所述第二谐波电流的幅值中的较小值，所述第一变化趋势为所述第一谐波电流的幅值和所述第二谐波电流的幅值之间的变化趋势，所述第二变化趋势为所述第一载波的相位和所述第二载波的相位之间的变化趋势，所述第三谐波电流为输入所述调制单元的载波为调整相位后的输入载波时，所述调整相位后的输入载波与所述调制波生成开关信号，对所述逆变器中的开关器件进行控制时，所述逆变器输出的谐波电流。
具体地，上述控制单元可以根据第一变化趋势和第二变化趋势，增大或减小输入至调制单元的输入载波的相位，作为准备从控制器输出的第三载波的相位，使得输入载波为第三载波输入调制单元和调制波生成开关信号，对逆变器中的开关器件进行控制时，上述逆变器输出的第三谐振电流的幅值小于第一谐振电流的幅值和第二谐振电流的幅值的较小值。
需要说明的是，输入调制单元的输入载波包括3种变量：幅值、频率和相位，供电系统可以在控制系统中经由时钟固化输入载波的频率，并且通过归一化处理对输入载波的幅值进行同步。此时，输入载波的三个变量中唯一不确定的就是载波的初始相位。供电系统中的多个并联的逆变器的启动不同步，都会使得载波的初始相位不同，最终导致 输入载波的相位不同步，即载波不同步。换言之，在本申请实施例中载波同步可以理解为对输入调制单元的输入载波的相位进行同步。
还应理解，上述控制单元可以是用于进行载波同步的控制单元，当上述装置700设置在单相逆变器300中时，可以独立于单相逆变器中的第一控制器，还可以与第一控制器集成在一起，本申请实施例对此不作具体限定。
本申请实施例根据第一谐波电流的幅值和第二谐波电流的幅值之间的变化趋势，以及第一载波的相位和第二载波的相位之间的变化趋势，对输入调制单元的输入载波的相位进行调整，作为准备从控制器输出的输入载波的相位，以减小逆变器输出的谐波电流的幅值，提高分布式供电系统的稳定性。
进一步地，避免了使用现有技术中基于零序电流进行载波同步的过程中，无法通过载波同步减少谐波电流对供电系统的影响，以提高分布式系统的稳定性。
在一些实施例中，上述载波和调制波进行比较可以基于脉冲宽度调制(Pulse Width Modulation，PWM)技术，当调制波的幅值高于载波的幅值时，开关信号为高电平，当调制波的幅值低于载波的幅值时，开关信号为低电平；或者当调制波的幅值高于载波的幅值时，开关信号为低电平，当调制波的幅值低于载波的幅值时，开关信号为高电平。
还应理解，上述PWM技术可以采用和现有技术相同的方式通过比较器实现，还可以通过数字信号处理(Digital Signal Processor，DSP)芯片实现，本申请实施例对PWM技术的具体实现方式不作限定。
在一些实施例中，装置700可以为逆变器的一部分。例如，装置700可以与逆变器集成在一块芯片上，专门用于为该逆变器进行载波同步，图3示出了单相逆变器与装置700集成在一块芯片上的示意性框图。装置700还可以是位于逆变器之外的载波同步装置。
在一些实施例中，装置700还可以是逆变器中内置的数字信号处理器(Digital Signal Processor，DSP)。
可选地，所述控制单元还用于：所述第一变化趋势和所述第二变化趋势相同时，减小输入至所述调制单元的输入载波的相位，所述第一变化趋势和所述第二变化趋势相反时，增大输入至所述调制单元的输入载波的相位。
具体地，上述第一变化趋势和第二变化趋势相同，可以指随着第一变化趋势增大，第二变化趋势增大，或随着第一变化趋势减小，第二变化趋势减小；上述第一变化趋势和第二变化趋势相反，可以指随着第一变化趋势的增大，第二变换趋势减小，或随着第一变化趋势的减小，第二变化趋势增大。
也就是说，上述第一变化趋势和第二变化趋势相同，可以是第一变化趋势和第二变化趋势落在图6所示的单调递增区间内，上述第一变化趋势和第二变化趋势相反，可以是第一变化趋势和第二变化趋势落在图6所示的单调递减区间内。
在一些实现方式中，所述第一变化趋势通过i1-i2表示，其中，i1表示第一谐波电流的幅值，i2表示第二电流的幅值；所述第二变化趋势通过θ1-θ2表示，其中，θ1表示第一载波的相位，θ2表示第二载波的相位。
在一些实现方式中，上述第一变化趋势和第二变换趋势相同可以指第一变化趋势和第二变化趋势同号，即
Figure PCTCN2017085805-appb-000013
上述第一变化趋势和第二变化趋势相反，可以指第一变化趋势和第二变化趋势异号，即
Figure PCTCN2017085805-appb-000014
在一些实现方式中，所述控制单元还用于：确定调整步长，所述调整步长为增大或减小所述输入载波的相位的调整步长；根据所述第一变化趋势和所述第二变化趋势，以所述第一调整步长，增大或减小输入至所述调制单元的输入载波的相位。
应理解，上述调整步长可以是固定值，例如，调整步长可以是预设的调整步长；上述调整步长还可以是变化值，例如，调整步长可以是随着逆变器当前输出的谐波电流的幅值变化的调整步长，本申请实施例对于调整步长的具体实现形式不作限定。
在一些实现方式中，所述第一谐振电流为当前所述逆变器输出的谐振电流，所述控制单元还用于：根据公式
Figure PCTCN2017085805-appb-000015
且θref>0，确定所述调整步长，其中，Δθ表示所述调整步长，if表示所述第一谐振电流的幅值，iN表示所述逆变器的额定电流值，θref表示确定所述调整步长的参考值。
具体地，上述θref表示确定所述调整步长的参考值，可以指θref表示确定所述调整步长的参考相位。
需要说明的是，上述θref可以是预设的用于确定调整步长参考值。
在一些实现方式中，所述第一谐振电流为当前所述逆变器输出的谐振电流，所述控制单元还用于：根据公式
Figure PCTCN2017085805-appb-000016
且θref>0，确定所述调整步长，其中，Δθ表示所述调整步长，if表示所述第一谐振电流的幅值，iN表示所述逆变器的额定电流值，θref表示确定所述调整步长的初始值。
具体地，上述θref表示确定所述调整步长的参考值，可以指θref表示确定所述调整步长的参考相位。
需要说明的是，上述θref可以是预设的用于确定调整步长参考值。
在一些实施例中，上述增大输入至调制单元的输入载波的相位，可以指将输入载波在时间上延迟一个时间调整值对应的时间段，上述减小输入至调制单元的输入载波的相位，可以指将输入载波在时间上提前一个时间调整值对应的时间段。
在一些实施例中，若调整步长Δθ的单位为度时，上述时间调整值Δt可以根据公式
Figure PCTCN2017085805-appb-000017
其中，Δθ表示调整步长，fC表示输入载波的频率。
在一些实施例中，若调整步长Δθ的单位为弧度(rad)时，上述时间调整值Δt可以根据公式
Figure PCTCN2017085805-appb-000018
其中，Δθ表示调整步长，fC表示输入载波的频率。
在一些实现方式中，所述控制单元具体还用于：根据所述第一变化趋势、所述第二变化趋势以及谐波电流的幅值的变化趋势和输入载波的相位的变化趋势，增大或减小输入至所述调制单元的输入载波的相位。
具体地，控制单元可以根据所述第一变化趋势、所述第二变化趋势以及谐波电流的幅值的变化趋势和输入载波的相位的变化趋势，一次将输入至调制单元的输入载波的相位调整至与该供电系统中其他已经载波同步的逆变器(例如，第一逆变器)的相位同步。
在一些实现方式中，所述控制单元具体还用于：根据所述第一变化趋势、所述第二变化趋势以及谐波电流的幅值的变化趋势和输入载波的相位的变化趋势，以预设的调整步长，增大或减小输入至所述调制单元的输入载波的相位。
具体地，第一变化趋势和第二变化趋势相同时，以预设的调整步长对输入调制单元的输入载波的相位进行迭代，逐步减小输入调制单元的输入载波的相位，直到所述逆变 器输出的第三谐波电流的幅值小于所述第一谐波电流的幅值和第二谐波电流的幅值中的较小值；第一变化趋势和第二变化趋势相反时，以预设的调整步长对输入调制单元的输入载波的相位进行迭代，逐步增大输入调制单元的输入载波的相位，直到所述逆变器输出的第三谐波电流的幅值小于所述第一谐波电流的幅值和第二谐波电流的幅值中的较小值。
在一些实现方式中，所述控制单元包括：逻辑判断单元，用于根据所述第一变化趋势和所述第二变化趋势，确定输入至所述调制单元的输入载波的所述相位；移相单元，用于根据确定的输入至所述调制单元的输入载波的所述相位，增大或减小输入至所述调制单元的输入载波的相位。
在一些实现方式中，所述控制单元还用于：确定所述逆变器输出的所述第三谐波电流的幅值低于电流幅值阈值，则停止增大或减小输入至所述调制单元的输入载波的相位。
具体地，当逆变器输出的第三谐波电流的幅值低于电流幅值阈值时，可以停止对输入至调制单元的输入载波的相位进行调整，此时，可以确定输入至调制单元的输入载波的相位与供电系统中除所述逆变器之外的其他已经实现载波同步的逆变器(例如，第一逆变器)对应的载波的相位同步。
在一些实现方式中，上述电流幅值阈值可以为逆变器额定电流的1％。
在一些实现方式中，所述逆变器为单相逆变器或三相逆变器。
由于零序电流是三相逆变器中的三相电流的相量和不为0时产生的电流，属于三相逆变器中特有的电流，因此，根据零序电流实现载波同步的方法并不适用在单相逆变器中，而本申请实施例中的谐波电流是由于逆变器中的硬件电路中存在谐振点(即阻抗较小的点)，或是供电系统中存在特定频率的系统激励(例如，边频带信号)产生的，是影响多个单相逆变器并联的供电系统的稳定性的因素之一，因此本申请实施例的谐波电流的调节方法也适用由多个单相逆变器并联组成的供电系统。
在一些实施例中，所述电流处理单元还用于：对所述逆变器输出的交流电进行电流采样，获取所述逆变器输出谐波电流的幅值。
具体地，对逆变器输出的交流电进行采样，并对该交流电进行滤波处理，获取频率为第一频率的谐波电流的幅值，所述第一频率为逆变器的谐振频率。由于逆变器中除了滤波器包括电感和电容以外，其余的部件包括印制电路板上面存在的电容和电感的电感或电容值非常小(又称为寄生电感或电容)，通常可以忽略，因此逆变器的谐振频率可以主要考虑逆变器中的滤波器中的电容和电感的谐振频率。也就是说，上述第一频率可以根据逆变器中的滤波器中的电容和电感的谐振频率确定。
若上述第一频率可以用f表示，则
Figure PCTCN2017085805-appb-000019
确定，其中，Leq表示滤波器的等效电感值，Ceq表示滤波器的等效电容值。
应理解，上述对交流电进行滤波处理以获取第一频率的谐波电流的滤波器可以是数字滤波或模拟滤波器，其中，数字滤波器可以采用快速傅里叶变换的方法进行滤波，模拟滤波器具体可以是带通滤波器。
在一些实施例中，本申请实施例提供一种逆变系统，包括若干逆变器，所述逆变系统包括图7所示的装置700，该装置700用于控制所述若干逆变器的载波同步。
具体地，上述逆变系统可以包括多个逆变器，该装置700用于控制多个逆变器中与所述装置700相连的目标逆变器和逆变系统中除所述目标逆变器之外的其他逆变器之间 的载波同步过程。
需要说明的是，图7仅仅示出了本申请实施例的逆变系统中的一个逆变器，本申请实施例对于逆变系统中的逆变器数量不作具体限定。
还应理解，上述装置700可以与逆变器封装在一个电路板上，也就是说，逆变系统中的每个逆变器中都有一个独立的装置700，具体装置700和逆变器之间的连接方式可以参见图7。
上文结合图1至图7详细的说明了描述了本申请实施例的用于载波同步的装置，下面结合图8，详细描述本申请实施例的用于载波同步的方法。应理解，图7所示的装置能够实现图8所示的方法中的各个步骤，为避免重复，在此不再详细赘述。
图8是本申请实施例的用于载波同步的方法的示意性流程图，应用所述方法的装置包括调制单元和逆变器，所述调制单元，基于输入载波和调制波生成开关信号，对所述逆变器中的开关器件进行控制，所述方法包括：
810，获取所述逆变器输出的第一谐波电流的幅值和第二谐波电流的幅值，所述第一谐波电流为所述输入载波为第一载波输入所述调制单元和所述调制波生成开关信号，对所述逆变器中的开关器件进行控制时，所述逆变器输出的谐波电流，所述第二谐波电流为输入载波为第二载波输入所述调制单元和所述调制波生成开关信号，对所述逆变器中的开关器件进行控制时，所述逆变器输出的谐波电流，其中所述第一载波和所述第二载波的相位不同。
在一些实现方式中，所述逆变器为单相逆变器或三相逆变器。
820，根据第一变化趋势和第二变化趋势，增大或减小输入至所述调制单元的输入载波的相位，使得所述逆变器输出的第三谐波电流的幅值小于所述第一谐波电流的幅值和第二谐波电流的幅值中的较小值，所述第一变化趋势为所述第一谐波电流的幅值和所述第二谐波电流的幅值之间的变化趋势，所述第二变化趋势为所述第一载波的相位和所述第二载波的相位之间的变化趋势，所述第三谐波电流为输入所述调制单元的载波为增大或减小相位后的输入载波时，所述增大或减小相位后的输入载波与所述调制波生成开关信号，对所述逆变器中的开关器件进行控制时，所述逆变器输出的谐波电流。
应理解，图8示出的用于载波同步的详细的步骤或操作，但这些步骤或操作仅是示例，本申请实施例还可以执行其他操作，或者图8中各操作的变形。此外，图8中的各个步骤可以按照与图8呈现的不同顺序来执行，并且有可能并非要执行图8中的全部操作。下面具体描述图8所示的方法步骤。
本申请实施例根据第一谐波电流的幅值和第二谐波电流的幅值之间的变化趋势，以及第一载波的相位和第二载波的相位之间的变化趋势，对输入调制单元的输入载波的相位进行调整，以减小逆变器输出的谐波电流的幅值，提高分布式供电系统的稳定性。
进一步地，避免了使用现有技术中基于零序电流进行载波同步的过程中，无法通过载波同步减少谐波电流对供电系统的影响，以提高分布式系统的稳定性。
在一些实现方式中，步骤820还包括：所述第一变化趋势和所述第二变化趋势相同时，减小输入至所述调制单元的输入载波的相位，所述第一变化趋势和所述第二变化趋势相反时，增大输入至所述调制单元的输入载波的相位。
在一些实现方式中，所述第一变化趋势通过i1-i2表示，其中，i1表示第一谐波电流的幅值，i2表示第二电流的幅值；所述第二变化趋势通过θ1-θ2表示，其中，θ1表示第一载 波的相位，θ2表示第二载波的相位。
在一些实现方式中，上述第一变化趋势和第二变换趋势相同可以指第一变化趋势和第二变化趋势同号，即
Figure PCTCN2017085805-appb-000020
上述第一变化趋势和第二变化趋势相反，可以指第一变化趋势和第二变化趋势异号，即
Figure PCTCN2017085805-appb-000021
在一些实现方式中，所述控制单元还用于：确定调整步长，所述调整步长为增大或减小所述输入载波的相位的调整步长；根据所述第一变化趋势和所述第二变化趋势，以所述第一调整步长，增大或减小输入至所述调制单元的输入载波的相位。
在一些实现方式中，所述第一谐振电流为当前所述逆变器输出的谐振电流，所述控制单元还用于：根据公式
Figure PCTCN2017085805-appb-000022
且θref>0，确定所述调整步长，其中，Δθ表示所述调整步长，if表示所述第一谐振电流的幅值，iN表示所述逆变器的额定电流值，θref表示确定所述调整步长的参考值。
在一些实现方式中，所述第一谐振电流为当前所述逆变器输出的谐振电流，所述控制单元还用于：根据公式
Figure PCTCN2017085805-appb-000023
且θref>0，确定所述调整步长，其中，Δθ表示所述调整步长，if表示所述第一谐振电流的幅值，iN表示所述逆变器的额定电流值，θref表示确定所述调整步长的初始值。
在一些实施例中，上述增大输入至调制单元的输入载波的相位，可以指将输入载波在时间上延迟一个时间调整值对应的时间段，上述减小输入至调制单元的输入载波的相位，可以指将输入载波在时间上提前一个时间调整值对应的时间段。
在一些实施例中，若调整步长Δθ的单位为度时，上述时间调整值Δt可以根据公式
Figure PCTCN2017085805-appb-000024
其中，Δθ表示调整步长，fC表示输入载波的频率。
在一些实施例中，若调整步长Δθ的单位为弧度(rad)时，上述时间调整值Δt可以根据公式
Figure PCTCN2017085805-appb-000025
其中，Δθ表示调整步长，fC表示输入载波的频率。
在一些实现方式中，步骤820还包括：根据所述第一变化趋势、所述第二变化趋势以及谐波电流的幅值的变化趋势和输入载波的相位的变化趋势，增大或减小输入至所述调制单元的输入载波的相位。
具体地，根据第一变化趋势、第二变化趋势以及第一变化趋势和第二变化趋势之间的映射关系，一次将输入至调制单元的输入载波的相位调整至与该供电系统中其他已经载波同步的逆变器(例如，第一逆变器)的相位同步。
在一些实现方式中，步骤820还包括：根据所述第一变化趋势、所述第二变化趋势以及谐波电流的幅值的变化趋势和输入载波的相位的变化趋势，以预设的调整步长，增大或减小输入至所述调制单元的输入载波的相位。
在一些实现方式中，步骤820还包括：根据所述第一变化趋势和所述第二变化趋势，确定输入至所述调制单元的输入载波的所述相位；根据确定的输入至所述调制单元的输入载波的所述相位，增大或减小输入至所述调制单元的输入载波的相位。
在一些实现方式中，所述方法还包括：确定所述逆变器输出的所述第三谐波电流的幅值低于电流幅值阈值，则停止增大或减小输入至所述调制单元的输入载波的相位。
下面将结合载波同步的控制周期详细介绍本申请实施例的用于载波同步的方法。为了便于描述，下文中描述的“第二逆变器对应的输入载波”可以指与调制单元中调制波 生成开关信号，以控制第二逆变器中的开关器件的输入载波。
图9是本申请实施例的用于载波同步的方法的示意性流程图。应理解，图9所示的方法以图2所示的分布式供电系统为基础，其中第一逆变器可以是已经完成载波同步的逆变器，第二逆变器可以是需要进行载波同步的逆变器。图9所示的方法包括：
910，对第二逆变器输出的交流电中的谐波电流进行采样。
具体地，上述谐波电流的频率可以是
Figure PCTCN2017085805-appb-000026
确定，其中，Leq表示滤波器的等效电感值，Ceq表示滤波器的等效电容值。
920，判断当前控制周期是否是第二逆变器进行载波同步的初始控制周期。
具体地，判断当前控制周期是否是第二逆变器进行载波同步的初始控制周期可以分为下面两种情况：
921，若当前控制周期是第二逆变器进行自载波同步的初始控制周期，则可以将第二逆变器在当前控制周期内对应的输入载波的相位标记为θ0，并为第二逆变器在下一控制周期对应的输入载波配置预设的初始相位θ1，随后执行步骤950。
需要说明的是，上述初始控制周期内，逆变器对应的输入载波的相位θ0可以是随机选择的，也可以是预先配置的固定值，本申请实施例对于上述初始相位的具体选择方式不作限定。
上述初始控制周期之后的下一控制周期内，逆变器对应的输入载波的相位θ1也可以是随机选择的，也可以是预先配置的固定值，本申请实施例对于上述初始相位的具体选择方式不作限定。
922，若当前控制周期不是第二逆变器进行载波同步的初始控制周期，则执行步骤930。
需要说明的是，上述控制周期可以包括至少一个开关周期。
930，判断谐波电流的幅值是否大于电流幅值阈值。
具体地，判断谐波电流的幅值是否大于电流幅值阈值，分为下面两种情况：
931，谐波电流的幅值小于或等于电流幅值阈值，则可以确定当前第二逆变器对应载波的相位与供电系统中的载波的相位近似同步，可以停止调节第二逆变器对应载波的相位，执行步骤950。
932，谐波电流的幅值大于电流幅值阈值，执行步骤940。
由于谐波电流的幅值大于电流幅值阈值，则可以确定当前谐波电流还是有可能影响系统的稳定性，则需要对谐波电流的幅值进行调整，执行步骤940。
940，根据谐波电流的幅值的变化趋势和第二逆变器对应的输入载波的相位的变化趋势，确定下一控制周期中第二逆变器对应的输入载波相位的变化趋势。
具体地，为了便于描述借助符号进行说明。当前的控制周期为第n个控制周期，则当前控制周期之前的一个控制周期用n-1表示，以此类推，第n-1控制周期之前的一个控制周期用n-2表示，当前的控制周期之后的一个控制周期可以用n+1表示。第n个控制周期中逆变器输出的谐波电流的幅值为in，第n-1个控制周期中逆变器输出的谐波电流的幅值为in-1，且该控制周期内第二逆变器对应的输入载波的相位为θn-1，第n-2个控制周期中逆变器输出的谐波电流的幅值为in-2，且该控制周期内第二逆变器对应的输入载波的相位为θn-2。则上述谐波电流的幅值的变化趋势可以表示为in-in-1，上述载波的相位的变化趋势可以表示为θn-θn-1。也就是说，第n+1个控制周期中第二逆变器对应的输入 载波的相位θn+1与第n个控制周期中第二逆变器对应的输入载波的相位θn之间的变化趋势可以根据in-in-1和θn-θn-1确定。
上述确定第n+1个控制周期中载波的相位具体可以细分为两种情况：
1、当in-in-1的变化趋势和θn-θn-1的变化趋势相同时，即
Figure PCTCN2017085805-appb-000027
可以确定in-in-1和θn-θn-1为图5所示的曲线中的单调递增区间内，此时第n+1个控制周期中载波的相位与第n个控制周期中载波的相位之间的变化趋势可以为减小趋势，即θn+1<θn。
2、当in-in-1的变化趋势和θn-θn-1的变化趋势相反时，即
Figure PCTCN2017085805-appb-000028
可以确定in-in-1和θn-θn-1为图5所示的曲线中的单调递减区间内，此时第n+1个控制周期中载波的相位与第n个控制周期中载波的相位之间的变化趋势可以为增大趋势，即θn+1>θn。
950，本控制周期结束，进入下一控制周期。
具体地，结束第n个控制周期中对于输入载波的相位的调节，并进入第n+1个控制周期。
应理解，在本申请实施例中，“与A相应的B”表示B与A相关联，根据A可以确定B。但还应理解，根据A确定B并不意味着仅仅根据A确定B，还可以根据A和/或其它信息确定B。
应理解，本文中术语“和/或”，仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。另外，本文中字符“/”，一般表示前后关联对象是一种“或”的关系。
应理解，在本申请的各种实施例中，上述各过程的序号的大小并不意味着执行顺序的先后，各过程的执行顺序应以其功能和内在逻辑确定，而不应对本申请实施例的实施过程构成任何限定。
在本申请所提供的几个实施例中，应该理解到，所揭露的系统、装置和方法，可以通过其它的方式实现。例如，以上所描述的装置实施例仅仅是示意性的，例如，所述单元的划分，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，例如多个单元或组件可以结合或者可以集成到另一个系统，或一些特征可以忽略，或不执行。另一点，所显示或讨论的相互之间的耦合或直接耦合或通信连接可以是通过一些接口，装置或单元的间接耦合或通信连接，可以是电性，机械或其它的形式。
所述作为分离部件说明的单元可以是或者也可以不是物理上分开的，作为单元显示的部件可以是或者也可以不是物理单元，即可以位于一个地方，或者也可以分布到多个网络单元上。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案的目的。
另外，在本申请各个实施例中的各功能单元可以集成在一个处理单元中，也可以是各个单元单独物理存在，也可以两个或两个以上单元集成在一个单元中。
在上述实施例中，可以全部或部分地通过软件、硬件、固件或者其任意组合来实现。当使用软件实现时，可以全部或部分地以计算机程序产品的形式实现。所述计算机程序产品包括一个或多个计算机指令。在计算机上加载和执行所述计算机程序指令时，全部或部分地产生按照本申请实施例所述的流程或功能。所述计算机可以是通用计算机、专用计算机、计算机网络、或者其他可编程装置。所述计算机指令可以存储在计算机可读存储介质中，或者从一个计算机可读存储介质向另一个计算机可读存储介质传输，例如，所述计算机指令可以从一个网站站点、计算机、服务器或数据中心通过有线(例如同轴 电缆、光纤、数字用户线(Digital Subscriber Line，DSL))或无线(例如红外、无线、微波等)方式向另一个网站站点、计算机、服务器或数据中心进行传输。所述计算机可读存储介质可以是计算机能够读取的任何可用介质或者是包含一个或多个可用介质集成的服务器、数据中心等数据存储设备。所述可用介质可以是磁性介质，(例如，软盘、硬盘、磁带)、光介质(例如，数字通用光盘(Digital Video Disc，DVD))或者半导体介质(例如，固态硬盘(Solid State Disk，SSD))等。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以所述权利要求的保护范围为准。

Claims (15)

  1. 一种用于载波同步的装置，其特征在于，包括：
    调制单元，基于输入载波和调制波生成开关信号，对逆变器中的开关器件进行控制；
    电流处理单元，用于获取所述逆变器输出的第一谐波电流的幅值和第二谐波电流的幅值，所述第一谐波电流为所述输入载波为第一载波输入所述调制单元和所述调制波生成开关信号，对所述逆变器中的开关器件进行控制时，所述逆变器输出的谐波电流，所述第二谐波电流为所述输入载波为第二载波输入所述调制单元和所述调制波生成开关信号，对所述逆变器进行控制时，所述逆变器输出的谐波电流，其中所述第一载波的相位和所述第二载波的相位不同；
    控制单元，用于根据第一变化趋势和第二变化趋势，增大或减小输入至所述调制单元的输入载波的相位，使得所述逆变器输出的第三谐波电流的幅值小于所述第一谐波电流的幅值和所述第二谐波电流的幅值中的较小值，所述第一变化趋势为所述第一谐波电流的幅值和所述第二谐波电流的幅值之间的变化趋势，所述第二变化趋势为所述第一载波的相位和所述第二载波的相位之间的变化趋势，所述第三谐波电流为输入所述调制单元的载波为调整相位后的输入载波时，所述调整相位后的输入载波与所述调制波生成开关信号，对所述逆变器中的开关器件进行控制时，所述逆变器输出的谐波电流。
  2. 如权利要求1所述的装置，其特征在于，所述控制单元用于：
    所述第一变化趋势和所述第二变化趋势相同时，减小输入至所述调制单元的输入载波的相位，所述第一变化趋势和所述第二变化趋势相反时，增大输入至所述调制单元的输入载波的相位。
  3. 如权利要求1或2所述的装置，其特征在于，所述控制单元还用于：
    确定调整步长，所述调整步长为增大或减小所述输入载波的相位的调整步长；
    根据所述第一变化趋势和所述第二变化趋势，以所述调整步长，增大或减小输入至所述调制单元的输入载波的相位。
  4. 如权利要求3所述的装置，其特征在于，所述第一谐振电流为当前所述逆变器输出的谐振电流，
    所述控制单元还用于：
    根据公式
    Figure PCTCN2017085805-appb-100001
    且θref>0，确定所述调整步长，其中，Δθ表示所述调整步长，if表示所述第一谐振电流的幅值，iN表示所述逆变器的额定电流值，θref表示确定所述调整步长的参考值。
  5. 如权利要求3所述的装置，其特征在于，所述第一谐振电流为当前所述逆变器输出的谐振电流，
    所述控制单元还用于：
    根据公式
    Figure PCTCN2017085805-appb-100002
    且θref>0，确定所述调整步长，其中，Δθ表示所述调整步长，if表示所述第一谐振电流的幅值，iN表示所述逆变器的额定电流值，θref表示确定所述调整步长的参考值。
  6. 如权利要求1所述的装置，其特征在于，所述控制单元还用于：
    根据所述第一变化趋势、所述第二变化趋势以及谐波电流的幅值的变化趋势和输入 载波的相位的变化趋势之间的映射关系，增大或减小输入至所述调制单元的输入载波的相位。
  7. 如权利要求1所述的装置，其特征在于，所述控制单元包括：
    逻辑判断单元，用于根据所述第一变化趋势和所述第二变化趋势，确定输入至所述调制单元的输入载波的所述相位；
    移相单元，用于根据确定的输入至所述调制单元的输入载波的所述相位，增大或减小输入至所述调制单元的输入载波的相位。
  8. 一种逆变系统，包括若干逆变器，其特征在于，所述逆变系统包括权利要求1至7中任一项所述的装置，用于控制所述若干逆变器的载波同步。
  9. 一种用于载波同步的方法，其特征在于，应用所述方法的装置包括调制单元和逆变器，所述调制单元，基于输入载波和调制波生成开关信号，对所述逆变器中的开关器件进行控制，所述方法包括：
    获取所述逆变器输出的第一谐波电流的幅值和第二谐波电流的幅值，所述第一谐波电流为所述输入载波为第一载波输入所述调制单元和所述调制波生成开关信号，对所述逆变器中的开关器件进行控制时，所述逆变器输出的谐波电流，所述第二谐波电流为输入载波为第二载波输入所述调制单元和所述调制波生成开关信号，对所述逆变器进行控制时，所述逆变器输出的谐波电流，其中所述第一载波和所述第二载波的相位不同；
    根据第一变化趋势和第二变化趋势，增大或减小输入至所述调制单元的输入载波的相位，使得所述逆变器输出的第三谐波电流的幅值小于所述第一谐波电流的幅值和第二谐波电流的幅值中的较小值，所述第一变化趋势为所述第一谐波电流的幅值和所述第二谐波电流的幅值之间的变化趋势，所述第二变化趋势为所述第一载波的相位和所述第二载波的相位之间的变化趋势，所述第三谐波电流为输入所述调制单元的载波为增大或减小相位后的输入载波时，所述增大或减小相位后的输入载波与所述调制波生成开关信号，对所述逆变器中的开关器件进行控制时，所述逆变器输出的谐波电流。
  10. 如权利要求9所述的方法，其特征在于，所述根据第一变化趋势和第二变化趋势，增大或减小输入至所述调制单元的输入载波的相位，包括：
    所述第一变化趋势和所述第二变化趋势相同时，减小输入至所述调制单元的输入载波的相位，所述第一变化趋势和所述第二变化趋势相反时，增大输入至所述调制单元的输入载波的相位。
  11. 如权利要求9或10所述的方法，其特征在于，所述方法还包括：
    确定调整步长，所述调整步长为增大或减小所述输入载波的相位的调整步长；
    所述根据第一变化趋势和第二变化趋势，增大或减小输入至所述调制单元的输入载波的相位，还包括：
    根据所述第一变化趋势和所述第二变化趋势，以所述调整步长，增大或减小输入至所述调制单元的输入载波的相位。
  12. 如权利要求11所述的方法，其特征在于，所述第一谐振电流为当前所述逆变器输出的谐振电流，
    所述确定调整步长，包括：
    根据公式
    Figure PCTCN2017085805-appb-100003
    且θref>0，确定所述调整步长，其中，Δθ表示所述调整步长，if表示所述第一谐振电流的幅值，iN表示所述逆变器的额定电流值，θref表示确定所述调整步长的参考值。
  13. 如权利要求11所述的方法，其特征在于，所述第一谐振电流为当前所述逆变器输出的谐振电流，
    所述确定调整步长，包括：
    根据公式
    Figure PCTCN2017085805-appb-100004
    且θref>0，确定所述调整步长，其中，Δθ表示所述调整步长，if表示所述第一谐振电流的幅值，iN表示所述逆变器的额定电流值，θref表示确定所述调整步长的参考值。
  14. 如权利要求9所述的方法，其特征在于，所述根据第一变化趋势和第二变化趋势，增大或减小输入至所述调制单元的输入载波的相位，还包括：
    根据所述第一变化趋势、所述第二变化趋势以及谐波电流的幅值的变化趋势和输入载波的相位的变化趋势之间的映射关系，增大或减小输入至所述调制单元的输入载波的相位。
  15. 如权利要求9所述的方法，其特征在于，所述根据第一变化趋势和第二变化趋势，增大或减小输入至所述调制单元的输入载波的相位，包括：
    根据所述第一变化趋势和所述第二变化趋势，确定输入至所述调制单元的输入载波的所述相位；
    用于根据确定的输入至所述调制单元的输入载波的所述相位，增大或减小输入至所述调制单元的输入载波的相位。
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