CN116470783A - Time-sharing power supply type single-stage low-frequency chain new energy multi-port integrated power supply system - Google Patents
Time-sharing power supply type single-stage low-frequency chain new energy multi-port integrated power supply system Download PDFInfo
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Classifications
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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
- H02M7/66—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal
- H02M7/68—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters
- H02M7/72—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/79—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with 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
- H02M7/797—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with 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
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0067—Converter structures employing plural converter units, other than for parallel operation of the units on a single load
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0083—Converters characterised by their input or output configuration
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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
- H02M7/66—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal
- H02M7/68—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters
Abstract
The invention relates to a time-sharing power supply type single-stage low-frequency chain new energy multiport integrated power supply system, the topological structure of which is formed by connecting a new energy multiport single-input single-output bidirectional high-frequency inverter circuit with an output filter inductor, an energy storage element single-input single-output bidirectional high-frequency inverter circuit with an output filter inductor and an output filter capacitor by a three-winding low-frequency transformer, wherein the new energy multiport single-input single-output bidirectional high-frequency inverter circuit comprises a prepositive parallel time-sharing selection switch, and the system adopts an input current instantaneous value feedback maximum power output power limiting energy management SPWM control strategy with an energy storage element direct-current port high-frequency inverter circuit output voltage independent control loop. The power supply system has the characteristics of time-sharing power supply to the load in one switching period of the multiple input sources, low-frequency isolation, small duty ratio adjustment range of the multiple input sources, small power switch voltage stress, single-stage power conversion among three types of ports, small volume and weight, high conversion efficiency, high reliability, low cost and the like, and is only suitable for scenes with similar voltage of the multiple input sources.
Description
Technical Field
The invention relates to a time-sharing power supply type single-stage low-frequency chain new energy multiport integrated power supply system, which belongs to the power electronic conversion technology.
Background
New energy sources (also called green energy sources) such as solar energy, wind energy, tidal energy, hydrogen energy and the like have the advantages of cleanness, no pollution, low cost, reliability, richness and the like, and have wide application prospects. The development and utilization of new energy are increasingly receiving attention from governments around the world due to the increasing tension of traditional fossil energy sources such as petroleum, coal and natural gas, serious environmental pollution, global warming and nuclear energy production, and the generation of nuclear waste and environmental pollution. The new energy power generation mainly comprises photovoltaic, wind power, fuel cells, hydraulic power and other types, and has the defects of unstable and discontinuous power supply, change along with the climate conditions and the like, so that a distributed power supply system combining multiple new energy sources is needed.
A conventional two-stage new energy multi-port power supply system is shown in fig. 1 and 2. The system generally adopts a plurality of single-input direct current converters to convert the electric energy of new energy power generation equipment such as photovoltaic cells, fuel cells, wind driven generators and the like which do not need energy storage through one unidirectional direct current converter, and then the power generation equipment is connected to a common inverter direct current bus after being connected in series or in parallel at an output end, and the energy storage equipment is also connected to the common inverter direct current bus after being converted through one bidirectional direct current converter, so that the aim of ensuring the combined power supply of various new energy sources and the coordinated operation is achieved. The power supply system realizes the simultaneous supply of power to loads by multiple input sources and the full utilization of energy sources, improves the stability and flexibility of the system, but has the defects of complex topological structure, large number of converters, two-stage power conversion among three types of ports of the multiple input sources, the energy storage element and the output load, large volume and weight, low conversion efficiency, low reliability, high cost and the like, and has limited practicality to a great extent.
In order to improve the system performance and reduce the cost, the topology structure of the two-stage new energy multiport power supply system shown in fig. 1 and 2 needs to be simplified, namely, the topology structure is simplified into a novel single-stage new energy multiport integrated power supply system shown in fig. 3. The single-stage new energy multiport integrated power supply system allows multiple new energy sources to be input, the properties, the amplitude and the characteristics of input sources can be the same, the difference can be large, and the single-stage power conversion device has the advantages of simple circuit structure, small volume and weight, high conversion efficiency, high reliability, low cost and the like among three types of ports of the multi-input source, the energy storage element and the output load.
Therefore, it is urgent to actively seek a new single-stage low-frequency chain new energy multiport integrated power supply system with high cost performance. The method has very important significance for meeting the greatly increased demands of human society on energy, improving environmental pollution, improving the stability and flexibility of a power supply system, prioritizing or fully utilizing new energy and promoting the development of a power electronic technology multiport conversion theory method system and new energy storage industry.
Disclosure of Invention
The invention aims to provide a high-cost performance time-sharing power supply type single-stage low-frequency chain new energy multiport integrated power supply system which has the characteristics of low-frequency isolation between output and input, common ground of a plurality of input power supplies, time-sharing power supply in one switching period, single-stage power conversion among three types of ports, small volume and weight, high conversion efficiency, high reliability, low cost, suitability for scenes with multiple input source voltages close to each other and the like.
The technical scheme of the invention is as follows: a time-sharing power supply type single-stage low-frequency chain new energy multiport integrated power supply system has a topological structure that a three-winding low-frequency transformer is used for providing an output filter inductance L f1 New energy n-input single-output bidirectional high-frequency inverter circuit of prepositive time-sharing selection switch circuit, and output filter inductance L f2 Energy storage element single-input single-output bidirectional high-frequency inverter circuit and output filter capacitor C f The connection structure is formed, n is the number of paths of multiple input sources and is a natural number greater than 1; each input end of the new energy n-input single-output bidirectional high-frequency inverter circuit of the front time-sharing selection switch circuit is correspondingly connected with each output end of the n common-ground input filters one by one, and the output end of the new energy n-input single-output bidirectional high-frequency inverter circuit of the front time-sharing selection switch circuit is correspondingly connected with the output filter inductor L f1 N input source port winding N of three-winding low-frequency transformer 11 Phase cascade, L f1 From external inductor and winding N 11 Is connected in series or is formed by winding N 11 Is realized by leakage inductance; the input end of the energy storage element single-input single-output bidirectional high-frequency inverter circuit is connected with the output end of the input filter, and the output end of the energy storage element single-input single-output bidirectional high-frequency inverter circuit is connected with the output filter inductance L f2 And energy storage element port winding N of three-winding low-frequency transformer 12 Phase cascade, L f2 From external inductor and winding N 12 Leakage inductance phase of (2)In series or by windings N only 12 Is realized by leakage inductance; the output filter capacitor C f Output load port winding N of three-winding low-frequency transformer 2 Is connected with each other; the new energy n-input single-output bidirectional high-frequency inverter circuit of the front time-sharing selection switch circuit is formed by sequentially cascading n-path time-sharing selection bidirectional switch circuits with only one bidirectional switch on each path connected in parallel at the output end and a single-input single-output bidirectional high-frequency inverter circuit; the topology structure of the power supply system is push-pull type, push-pull forward type, half-bridge type and full-bridge type circuits, and n paths of time-sharing selection bidirectional switches S s1 、S s2 、…、S sn The voltage stress during bipolar SPWM and unipolar SPWM modulation is max-U, respectively iN -U i1 ∣、max∣U iN -U i2 ∣、…、max∣U iN -U in | and U i1 -(U i1 +U i2 +…+U in )/(n+2)、U i2 -(U i1 +U i2 +…+U in )/(n+2)、…、U in -(U i1 +U i2 +…+U in ) V (n+2), wherein the voltage stress of the four power switches of the single-input single-output bidirectional full-bridge high-frequency inverter circuit is U imax ＝max(U i1 、U i2 、…、U in ) Or the energy storage element voltage U b The method comprises the steps of carrying out a first treatment on the surface of the The n paths of input sources U of the power supply system i1 、U i2 、…、U in Is small in duty cycle adjustment range and is controlled by U in one switching period i1 、U i2 、…、U in The power is supplied to the load in a time-sharing way in sequence, and is only suitable for multiple input source voltages U imax -U imin Scene less than or equal to 200V, U imin ＝min(U i1 、U i2 、…、U in )。
The invention constructs a topological structure of a DC converter and an inverter of a traditional new energy power supply system into a novel topological structure of a single-stage new energy multi-port integrated power supply system, and provides a topological structure of a time-sharing power supply type single-stage low-frequency chain new energy multi-port integrated power supply system and a limited power energy management control strategy thereof, namely the topological structure is formed by a three-winding low-frequency transformerWill be a filter with an input filter and an output filter inductance L f1 New energy n-input single-output bidirectional high-frequency inverter circuit with prepositive time-sharing selection bidirectional switch, input filter and output filter inductance L f2 The energy storage element single-input single-output bidirectional high-frequency inverter circuit and an output filter capacitor are connected, and the output ends of the new energy n-input single-output bidirectional high-frequency inverter circuit and the energy storage element single-input single-output bidirectional high-frequency inverter circuit are respectively connected with the n-input source port winding and the energy storage element port winding through a filter inductor (an external inductor is connected with leakage inductance of a transformer winding in series or is only realized by leakage inductance of the transformer winding).
The time-sharing power supply type single-stage low-frequency chain new energy multi-port integrated power supply system can invert a plurality of common-ground and unstable input source voltages into stable and high-quality output alternating current required by a load, has the characteristics of output and input low-frequency isolation, common-ground multi-input power supply, time-sharing power supply in one switching period, single-stage power conversion among three types of ports, small volume and weight, high conversion efficiency, high reliability, low cost, suitability for scenes with the magnitude of the multi-input source voltages being close, and the like, and has the comprehensive performance superior to that of the traditional two-stage new energy multi-port power supply system.
Drawings
FIG. 1 shows a conventional two-stage new energy multi-port power supply system with a plurality of unidirectional DC converters connected in series at the output ends.
FIG. 2 shows a conventional two-stage new energy multi-port power supply system with a plurality of unidirectional DC converter output ends connected in parallel.
FIG. 3 is a schematic block diagram of a novel single-stage new energy multiport integrated power supply system.
FIG. 4 is a schematic block diagram of a time-sharing power supply type single-stage low frequency chain new energy multiport integrated power supply system.
Fig. 5 is a circuit structure diagram of a time-sharing power supply type single-stage low-frequency chain new energy multiport integrated power supply system.
FIG. 6 shows a unipolar SPWM modulated steady state principle waveform diagram of a time-sharing powered single stage low frequency chain new energy multiport integrated power supply system.
Fig. 7 is a schematic diagram of a full-bridge circuit topology example of a time-sharing power supply type single-stage low-frequency chain new energy multiport integrated power supply system.
FIG. 8 illustrates a power-limited energy management control strategy for a time-division powered single-stage low frequency chain new energy multi-port integrated power supply system.
Fig. 9, a multi-input source time-division powered input current instantaneous feedback maximum power output energy management unipolar SPWM control block diagram with energy storage element dc-port inverter circuit output voltage independent control loop.
Fig. 10 is a waveform diagram of the principle of multi-input source time-division power supply input current instantaneous value feedback maximum power output energy management unipolar SPWM control with energy storage element dc port inverter circuit output voltage independent control loop.
FIG. 11 shows the output voltage u of the time-division power supply type single-stage low-frequency chain new energy multi-port integrated power supply system o And output filter inductor current i Lf1 、i Lf2 Waveform.
Fig. 12 shows a working mode i of the time-sharing power supply type single-stage low-frequency chain new energy multiport integrated power supply system, namely, the multiple input sources supply power to the output load and the energy storage element.
Fig. 13 shows a working mode ii of the time-sharing power supply type single-stage low-frequency chain new energy multi-port integrated power supply system, namely, the multi-input source and the energy storage element supply power to the output load.
Fig. 14 shows a working mode iii of the time-sharing power supply type single-stage low-frequency chain new energy multiport integrated power supply system, in which multiple input sources supply power to an output load and an energy storage element is neither charged nor discharged.
Detailed Description
The technical scheme of the invention is further described below with reference to the attached drawings and embodiments.
The topological structure of the time-sharing power supply type single-stage low-frequency chain new energy multiport integrated power supply system is that a three-winding low-frequency transformer is used for providing an output filter inductance L f1 New energy n-input single-output bidirectional high-frequency inverter circuit of prepositive time-sharing selection switch circuit, and output filter inductance L f2 Single input single of energy storage element of (a)Output bidirectional high-frequency inverter circuit and output filter capacitor C f The connection structure is formed, n is the number of paths of multiple input sources and is a natural number greater than 1; each input end of the new energy n-input single-output bidirectional high-frequency inverter circuit of the front time-sharing selection switch circuit is correspondingly connected with each output end of the n common-ground input filters one by one, and the output end of the new energy n-input single-output bidirectional high-frequency inverter circuit of the front time-sharing selection switch circuit is correspondingly connected with the output filter inductor L f1 N input source port winding N of three-winding low-frequency transformer 11 Phase cascade, L f1 From external inductor and winding N 11 Is connected in series or is formed by winding N 11 Is realized by leakage inductance; the input end of the energy storage element single-input single-output bidirectional high-frequency inverter circuit is connected with the output end of the input filter, and the output end of the energy storage element single-input single-output bidirectional high-frequency inverter circuit is connected with the output filter inductance L f2 And energy storage element port winding N of three-winding low-frequency transformer 12 Phase cascade, L f2 From external inductor and winding N 12 Is connected in series or is formed by winding N 12 Is realized by leakage inductance; the output filter capacitor C f Output load port winding N of three-winding low-frequency transformer 2 Is connected with each other; the new energy n-input single-output bidirectional high-frequency inverter circuit of the front time-sharing selection switch circuit is formed by sequentially cascading n-path time-sharing selection bidirectional switch circuits with only one bidirectional switch on each path connected in parallel at the output end and a single-input single-output bidirectional high-frequency inverter circuit; the topology structure of the power supply system is push-pull type, push-pull forward type, half-bridge type and full-bridge type circuits, and n paths of time-sharing selection bidirectional switches S s1 、S s2 、…、S sn The voltage stress during bipolar SPWM and unipolar SPWM modulation is max-U, respectively iN -U i1 ∣、max∣U iN -U i2 ∣、…、max∣U iN -U in | and U i1 -(U i1 +U i2 +…+U in )/(n+2)、U i2 -(U i1 +U i2 +…+U in )/(n+2)、…、U in -(U i1 +U i2 +…+U in ) V (n+2), n=1, 2, …, N, four power switches of single-input single-output bidirectional full-bridge high-frequency inverter circuitThe off voltage stress is U imax ＝max(U i1 、U i2 、…、U in ) Or the energy storage element voltage U b The method comprises the steps of carrying out a first treatment on the surface of the The n paths of input sources U of the power supply system i1 、U i2 、…、U in Is small in duty cycle adjustment range and is controlled by U in one switching period i1 、U i2 、…、U in The power is supplied to the load in a time-sharing way in sequence, and is only suitable for multiple input source voltages U imax -U imin Scene less than or equal to 200V, U imin ＝min(U i1 、U i2 、…、U in )。
The schematic block diagram, the topological structure and the steady-state schematic waveform of the unipolar SPWM control of the time-sharing power supply type single-stage low-frequency chain new energy multiport integrated power supply system are shown in figures 4, 5 and 6. In FIGS. 4, 5 and 6, U i1 、U i2 、…、U in For n paths of input direct-current voltage sources (n is a natural number greater than 1), Z L For single-phase output ac loads or ac network, u o 、i o The alternating voltage and the alternating current are output in a single phase respectively. The n-input single-output bidirectional high-frequency inverter circuit is formed by sequentially cascading a front n-way time-sharing selection bidirectional switch circuit and a single-input single-output bidirectional high-frequency inverter circuit, wherein the front n-way time-sharing selection bidirectional switch circuit is formed by n bidirectional high-frequency power switches capable of bearing bidirectional voltage stress and bidirectional current stress, the single-input single-output bidirectional high-frequency inverter circuit is formed by a plurality of high-frequency power switches capable of bearing unidirectional voltage stress and bidirectional current stress (power devices such as MOSFET (metal oxide semiconductor field effect transistor) and IGBT (insulated gate bipolar transistor)) and the n-way input filter is a capacitor filter or an LC (liquid crystal display) filter; the energy storage element single-input single-output bidirectional high-frequency inverter circuit is also composed of a plurality of high-frequency power switches (power devices such as MOSFET (metal oxide semiconductor field effect transistor) and IGBT (insulated gate bipolar transistor)) capable of bearing unidirectional voltage stress and bidirectional current stress, and the n-way input filter is a capacitive filter or an LC (inductance capacitance) filter. Fig. 5 shows a case of using an input capacitor filter, where the input dc current is smoother when using an LC input filter. The system can employ bipolar SPWM and unipolar SPWM modulation strategies, and FIG. 6 shows steady state principle waveforms when the unipolar SPWM modulation strategy is employed. n-input single-output bidirectional high-frequency inverter circuitN-way input DC source U i1 、U i2 、…、U in Multi-level SPWM voltage wave u modulated into bipolar two-state (bipolar SPWM modulation) or unipolar three-state (unipolar SPWM modulation) with amplitude varying with input DC voltage AB (the +1 state amplitude is U during bipolar SPWM modulation) i1 、U i2 、…、U in When designed to pass through the nth input source U only in The-1 state amplitude value when feeding back the energy of the alternating current side is-U in The method comprises the steps of carrying out a first treatment on the surface of the The +1 state amplitude value is U during unipolar SPWM modulation i1 、U i2 、…、U in The-1 state amplitude is-U i1 、-U i2 、…、-U in ) Through output filter inductance L f1 Low frequency transformer T, output filter capacitor C f Obtaining high-quality sine alternating voltage u on single-phase output alternating load (alternating current power grid) o (AC current i) o ). n input pulse currents flowing through the input filter and then being supplied to n input sources U i1 、U i2 、…、U in Is obtained to smooth the input DC current I i1 、I i2 、…、I in The method comprises the steps of carrying out a first treatment on the surface of the The energy storage element voltage U is supplied to the energy storage element single-input single-output bidirectional high-frequency inverter circuit b Modulating into bipolar two-state (bipolar SPWM modulation) or unipolar three-state (unipolar SPWM modulation) two-level SPWM voltage wave u with amplitude varying with input DC voltage CD (+1 state amplitude is U b The-1 state amplitude is-U b ) Through output filter inductance L f2 Low frequency transformer T, output filter capacitor C f After that, the supplement of the insufficient energy of the multiple input sources and the storage of the excessive energy of the multiple input sources are realized, and the input pulse current is input into the direct current source U after passing through the input filter b Is obtained to smooth the input DC current I b 。
The circuit topology embodiment of the time-sharing power supply type single-stage low-frequency chain new energy multiport integrated power supply system comprises push-pull type, push-pull forward type, half-bridge type and full-bridge type circuits, wherein the push-pull type, push-pull forward type and half-bridge type circuits can only adopt a bipolar SPWM (sinusoidal pulse width modulation) strategy, and the full-bridge type circuits can adopt a bipolar SPWM strategy and a unipolar SPWM strategy. Single-input single-output bidirectional high-frequency inverter circuit and single-input energy storage elementThe input/single output bidirectional high-frequency inverter circuit is composed of two or four high-frequency power switches capable of bearing unidirectional voltage stress and bidirectional current stress, and a full-bridge circuit topology is shown in fig. 7. The power switch voltage stress of the full-bridge circuit topology embodiment of the time-sharing power supply type single-stage low-frequency chain new energy multiport integrated power supply system is shown in table 1. In Table 1, U imax ＝max(U i1 ，U i2 ，…，U in ) N=1, 2, …, N. As can be seen from table 1, the inverter circuit of the system has small power switch voltage stress and is only suitable for multiple input source voltage U imax -U imin A scenario of less than or equal to 200V to fully utilize the voltage rating of the power switch, U imin ＝min(U i1 、U i2 、…、U in ). The circuit topology can convert a plurality of common-ground unstable input direct current voltages into output alternating current with required voltage magnitude, stability and high quality, and can be used for realizing a novel single-stage new energy multi-port integrated power supply system with high cost performance and wide application prospect, such as a photovoltaic cell 40-60VDC/220V50HzAC or 115V400HzAC, a 10kw proton exchange membrane fuel cell 85-120V/220V50HzAC or 115V400HzAC, a middle-and small-sized household wind power generation 24-36-48VDC/220V50HzAC or 115V400HzAC, a large-sized wind power generation 510VDC/220V50HzAC or 115V400HzAC and other multi-input sources for supplying power to an alternating current load or an alternating current power grid and being provided with energy storage elements with voltage magnitude of 48VDC, 96VDC and the like.
Table 1 Power switch Voltage stress for time-shared Power supply Single-stage Low frequency chain New energy Multi-port Integrated Power supply System full bridge Circuit embodiment
A time-sharing power supply type single-stage low-frequency chain new energy multiport integrated power supply system belongs to a step-down type inversion system, n input sources are connected in parallel to supply power to an output load and an energy storage element in a time-sharing mode, or the n input sources and the energy storage element supply power to the load together. Let n input source error amplifier output signals i 1e 、i 1e +i 2e 、…、i 1e +i 2e +…+i ne And the output of the output voltage error amplifierSignal u e The amplitude of (a) is I respectively 1em 、I 1em +I 2em 、…、I 1em +I 2em +…+I nem 、U em Saw-tooth carrier signal u c Is of amplitude U cm The corresponding modulation degree is m 1 ＝I 1em /U cm 、m 1 +m 2 ＝(I 1em +I 2em )/U cm 、…、m 1 +m 2 +…+m n ＝(I 1em +I 2em +…+I nem )/U cm 、m＝U em /U cm And has 0.ltoreq.m 1 、m 2 、…、m n M is less than or equal to 1 and m 1 ＜m 1 +m 2 ＜…＜m 1 +m 2 +…+m n . The principle of the inversion system is equivalent to the superposition of the voltages of a plurality of voltage type single-input inverters at the output end or equivalent to the output voltage of an energy storage element voltage type single-input inverter, namely the output voltage u o And multiple input source voltage (U) i1 、U i2 、…、U in ) Turn ratio N of low frequency transformer 11 /N 2 Modulation degree (m) 1 、m 2 、…、m n ) The relation between is u o ＝[(m 1 U i1 +m 2 U i2 +…+m n U in )]N 2 /N 11 (unipolar SPWM modulation) or u o ＝[(2m 1 -1)U i1 +(2m 2 -1)U i2 +…+(2m n -1)U in )]N 2 /N 11 (bipolar SPWM modulation), or output voltage u o And energy storage element voltage U b Turn ratio N of low frequency transformer 12 /N 2 The relation between the modulation degree m is u o ＝mU b N 2 /N 12 (unipolar SPWM modulation) or u o ＝(2m-1)U b N 2 /N 12 (bipolar SPWM modulation). Due to the presence of 0 < m 1 +m 2 +…+m n < 1 (unipolar SPWM modulation) and 0.5 < m 1 +m 2 +…+m n < 1 (bipolar SPWM modulation), so u o ＜(U i1 +U i2 +…+U in )N 2 /N 11 U is namely o Always lower than the multiple input source voltage (U) i1 、U i2 、…、U in ) Turn ratio N to low frequency transformer 2 /N 11 Sum of products (U) i1 +U i2 +…+U in )N 2 /N 11 The method comprises the steps of carrying out a first treatment on the surface of the The inverter system belongs to a single-stage circuit structure, the working frequency of a transformer is equal to the frequency of output voltage, and the multichannel time-sharing selection bidirectional switch is arranged in front of the high-frequency inverter circuit, so that the power supply system is also called a time-sharing power supply type single-stage low-frequency chain new energy multiport integrated power supply system with the front-mounted bidirectional selection switch. N input sources U of the power supply system i1 、U i2 、…、U in Is small in duty cycle adjustment range and is controlled by U in one switching period i1 、U i2 、…、U in The load is supplied with power in time-sharing order, the modulation degree can be the same (m 1 ＝m 2 ＝…＝m n ) May also be different (m 1 ≠m 2 ≠…≠m n )。
According to the time-sharing power supply type single-stage low-frequency chain new energy multiport integrated power supply system, as the multiple input sources and the energy storage element share one output low-frequency transformer and one filter circuit, the multiple input sources share one single-input single-output bidirectional high-frequency inverter circuit, and the topology structure of the traditional two-stage new energy multiport power supply system formed by cascading the direct current converter and the inverter is essentially different. Therefore, the power supply system has novelty and creativity, and has the advantages of low-frequency isolation of output and input, common ground of multiple input power sources, time-sharing power supply in one switching period, single-stage power conversion among three types of ports of multiple input sources, energy storage batteries and output loads, small volume and weight, high conversion efficiency (low energy loss), high reliability, low cost, flexible input voltage preparation, small output voltage ripple, large output capacity and suitability for multiple input source voltage U only imax -U imin The power switch is an ideal energy-saving consumption-reducing single-stage new energy multi-port integrated power supply system, and has important value at present for advocating construction of energy-saving and saving society.
The energy management control strategy is crucial to the new energy multi-port power supply system. Because of the multiple ports and corresponding power switching units, multiple power switching units need to be controlled, i.e. multiple degrees of control freedom exist, which provides the possibility for energy management and power distribution of the multiple ports.
The time-sharing power supply type single-stage low-frequency chain new energy multiport integrated power supply system needs to adopt an input current instantaneous value feedback maximum power output power limit energy management SPWM control strategy of an output voltage independent control loop of a direct-current port high-frequency inverter circuit with an energy storage element, as shown in fig. 8. In fig. 8, the system has three loops of independent control of output voltage, multi-input source MPPT and multi-input source power limit control, u o 、u r Respectively output feedback voltage and reference voltage, U 1 、I 1ref 、I 1 、P 1ref 、P 1 Output voltage, reference current, output power reference and output power of the 1 st path input source respectively, U 2 、I 2ref 、I 2 、P 2ref 、P 2 Output voltage, reference current, output power reference and output power of the 2 nd input source respectively …, U n 、I nref 、I n 、P nref 、P n The output voltage, reference current, output power reference and output power of the nth input source are respectively, and sin (ωt) is a synchronization signal of the output voltage (current). The power limiting control is realized by adding n power limiting loops on the basis of the 1 st, 2 nd and … th and n input source MPPT loops: under normal working conditions, P 1 <P 1ref 、P 2 <P 2ref 、…、P n <P nref Output u of n power-limited loops m1 、u m2 、…、u mn Respectively through diode D b1 And resistance R b1 Diode D b2 And resistance R b2 … and diode D bn And resistance R bn N clipping circuits composed, due to u m1 ＞0、u m2 ＞0、…、u mn ＞0，D b1 、D b2 、…、D bn Cut-off, I e1 ＝I e1 * 、I e2 ＝I e2 * 、…、I en ＝I en * ，u m1 、u m2 、…、u mn The MPPT loops of the 1 st, 2 nd, … th and n th input sources are not affected, namely the power limiting loop does not work; under extreme working conditions, the power is limited as long as the power of 1 input source fluctuates in a large range, and n input source powers P are set 1 >P 1ref 、P 2 >P 2ref 、…、P n >P nref Output u of n power-limited loops m1 ＜0、u m2 ＜0、…、u mn ＜0，D b1 、D b2 、…、D bn Conduction, I e1 ＝I e1 * +u m1 ＜I e1 * 、I e2 ＝I e2 * +u m2 ＜I e2 * 、…、I en ＝I en * +u mn ＜I en * ，u m1 、u m2 、…、u mn Output I of MPPT loop of 1 st, 2 nd, … th and n th input sources e1 、I e2 、…、I e2 And limiting amplitude, wherein the n paths of input sources exit from the MPPT state, so that the maximum power transmitted by the multi-port integrated power supply system is limited, and the safe and reliable operation of the system is ensured.
The SPWM control strategy for maximum power output energy feedback of the instantaneous value of the input current of the output voltage independent control loop of the high-frequency inverter circuit with the energy storage element DC port under the normal working condition of the system is further discussed below. Fig. 9 and 10 show control block diagrams and control principle waveforms when the unipolar SPWM modulation strategy is adopted. Current feedback signals I of 1 st, 2 nd, … th and n th input sources i1f 、I i2f 、…、I inf Reference current signal I obtained by calculating maximum power point with 1 st, 2 nd, … th and n th input sources respectively i1r 、I i2r 、…、I inr The output error amplified signal I is amplified by the comparison of a proportional integral error amplifier 1e 、I 2e 、…、I ne Respectively with sine synchronous signalMultiplying the numbers and outputting i by an adder 1e 、i 1e +i 2e 、…、i 1e +i 2e +…+i ne A signal; system output voltage feedback signal u of With reference sinusoidal voltage u r The output error amplified signal u is compared and amplified by a proportional integral error amplifier e ；i 1e 、i 1e +i 2e 、…、i 1e +i 2e +…+i ne And u e Zigzag carrier u with positive and negative polarities respectively corresponding to positive and negative half cycles of system output voltage c The control signal u of the power switch of the multi-input source n-input single-output bidirectional high-frequency inverter circuit is output after the interception and through the output voltage gating signal and the proper logic conversion circuit gss1 、u gss2 、…、u gssn 、u gs1 、u gs2 、u gs3 、u gs4 And control signal u of energy storage element single-input single-output bidirectional high-frequency inverter circuit power switch gsb1 、u gsb2 、u gsb3 、u gsb4 . The 1 st, 2 nd, … th and n th error amplifiers (currents) respectively and independently work and respectively work with the n+1th error amplifier (voltage), the former is used for realizing the maximum power output of the 1 st, 2 nd, … th and n th input sources, the latter is used for realizing the stability of the output voltage of a power supply system, and the n th input sources and the energy storage element are closely matched to supply power to a load. The control principle waveforms shown in FIG. 10 mark the switching period T S And on-time T of 1 st, 2 nd, … th and n th input sources on1 、T on2 、…、T onn Total on time T on ＝T on1 +T on2 +…+T onn Total on time T on Is varied in a sinusoidal manner during an output voltage period. It should be noted that, when the system is used for grid-connected power generation, the independent control loop of the output voltage needs to be adjusted to the independent control loop of the grid-connected current.
Taking a band-stop load of a time-sharing power supply type single-stage low-frequency chain new energy multi-port integrated independent power supply system as an example, the control of the power flow direction and the system output voltage of the energy storage element direct-current port high-frequency inverter circuit is discussed, and the control is shown in fig. 11, 12, 13 and 14. For output filteringWave capacitor C f And output load Z L ＝R L To say, the multi-input source direct current port high-frequency inverter circuit and the energy storage battery direct current port high-frequency inverter circuit respectively pass through L f1 、L f2 Two direct current port windings N of three-winding low-frequency transformer T 11 、N 12 And connected in parallel, corresponding to two current sources at output load port winding N 2 And (5) overlapping in parallel. From the output voltage u of the system shown in FIG. 11 o And output filter inductor current i Lf1 、i Lf2 Waveform shows that i of multi-input source direct current port high-frequency inverter circuit Lf1 And u is equal to o The same frequency and the same phase output active power; the high-frequency inverter circuit of the direct current port of the energy storage battery is connected with the power supply through u o And reference voltage u r Is controlled by SPWM signal generated by intersecting error amplification signal with high frequency sawtooth carrier, i Lf2 And u is equal to o There is a phase difference θ between them, and different phase differences θ mean that active power of different magnitudes and directions is output. When P o ＜P 1max +P 2max +…+P nmax When u o Increasing, wherein θ > 90 °, the energy storage element dc port high frequency inverter circuit outputs negative active power, the output load feeds back power to the energy storage battery, i.e. the residual power output by the multiple input source charges the energy storage element—power supply mode i, when θ=180°, the power fed back by the output load to the energy storage battery is maximum, and the system is equivalent to the multiple input and dual output multiport integrated conversion system shown in fig. 12; when P o >P 1max +P 2max +…+P nmax When u o The power supply mode II is equivalent to a multi-input single-output multi-port integrated inverter system in which multiple input sources and multiple windings are connected in parallel and simultaneously supply power, wherein the power supply mode II is shown in FIG. 13; when P o ＝P 1max +P 2max +…+P nmax When θ=90°, the active power output by the high-frequency inverter circuit at the dc port of the energy storage element is zero (no-load state), the energy storage element is neither charged nor discharged-power supply mode iii, which is equivalent to the multiple-input single-output mode shown in fig. 14And outputting the multi-port integrated inverter system. Thus, the energy management control strategy can be based on P o And P 1max +P 2max +…+P nmax The power flow and direction of the high-frequency inverter circuit of the direct current port of the energy storage element are controlled in real time, and the functions of maximum power output of multiple input sources such as photovoltaic, wind power and the like, power distribution of two types of direct current ports, stability of output voltage of a system and smooth and seamless switching of the system under three different power supply modes are realized. Based on the above, the maximum power output limit power energy management SPWM control strategy with the energy storage element direct current port and high frequency inverter circuit output voltage independent control loop shown in figure 8 can be realized by limiting the maximum power output by the multiple input sources under the extreme working condition.
Compared with the technical scheme of a single-stage power frequency link new energy multi-port integrated power supply system and a power frequency isolation type single-stage new energy multi-port hybrid power device integrated inverter which are simultaneously powered, the invention has different topological structures, circuit connection relations and power-limiting energy management control strategies, although n paths of input sources U i1 、U i2 、…、U in The duty ratio adjusting range of the power supply is small, but the voltage stress of four power switches of the bidirectional full-bridge high-frequency inverter circuit is small, namely U is obtained imax ＝max(U i1 、U i2 、…、U in ) Or the energy storage element voltage U b Pressing U in one switching period i1 、U i2 、…、U in The power is supplied to the load in a time-sharing way in sequence, and is only suitable for multiple input source voltages U imax -U imin Scene less than or equal to 200V, and the like.
Claims (2)
1. A time-sharing power supply type single-stage low-frequency chain new energy multiport integrated power supply system is characterized in that: the topology of the power supply system is that a three-winding low-frequency transformer is used for providing an output filter inductance L f1 New energy n-input single-output bidirectional high-frequency inverter circuit of prepositive time-sharing selection switch circuit, and output filter inductance L f2 Single-input single-output bidirectional high-frequency inversion of energy storage element of (2)Circuit and output filter capacitor C f The connection structure is formed, n is the number of paths of multiple input sources and is a natural number greater than 1; each input end of the new energy n-input single-output bidirectional high-frequency inverter circuit of the front time-sharing selection switch circuit is correspondingly connected with each output end of the n common-ground input filters one by one, and the output end of the new energy n-input single-output bidirectional high-frequency inverter circuit of the front time-sharing selection switch circuit is correspondingly connected with the output filter inductor L f1 N input source port winding N of three-winding low-frequency transformer 11 Phase cascade, L f1 From external inductor and winding N 11 Is connected in series or is formed by winding N 11 Is realized by leakage inductance; the input end of the energy storage element single-input single-output bidirectional high-frequency inverter circuit is connected with the output end of the input filter, and the output end of the energy storage element single-input single-output bidirectional high-frequency inverter circuit is connected with the output filter inductance L f2 And energy storage element port winding N of three-winding low-frequency transformer 12 Phase cascade, L f2 From external inductor and winding N 12 Is connected in series or is formed by winding N 12 Is realized by leakage inductance; the output filter capacitor C f Output load port winding N of three-winding low-frequency transformer 2 Is connected with each other; the new energy n-input single-output bidirectional high-frequency inverter circuit of the front time-sharing selection switch circuit is formed by sequentially cascading n-path time-sharing selection bidirectional switch circuits with only one bidirectional switch on each path connected in parallel at the output end and a single-input single-output bidirectional high-frequency inverter circuit; the topology structure of the power supply system is push-pull type, push-pull forward type, half-bridge type and full-bridge type circuits, and n paths of time-sharing selection bidirectional switches S s1 、S s2 、…、S sn The voltage stress during bipolar SPWM and unipolar SPWM modulation is max-U, respectively iN -U i1 ∣、max∣U iN -U i2 ∣、…、max∣U iN -U in | and U i1 -(U i1 +U i2 +…+U in )/(n+2)、U i2 -(U i1 +U i2 +…+U in )/(n+2)、…、U in -(U i1 +U i2 +…+U in ) V (n+2), wherein the voltage stress of the four power switches of the single-input single-output bidirectional full-bridge high-frequency inverter circuit is equal to that of the four power switches of the single-input single-output bidirectional full-bridge high-frequency inverter circuitU imax ＝max(U i1 、U i2 、…、U in ) Or the energy storage element voltage U b The method comprises the steps of carrying out a first treatment on the surface of the The n paths of input sources U of the power supply system i1 、U i2 、…、U in Is small in duty cycle adjustment range and is controlled by U in one switching period i1 、U i2 、…、U in The power is supplied to the load in a time-sharing way in sequence, and is only suitable for multiple input source voltages U imax -U imin Scene less than or equal to 200V, U imin ＝min(U i1 、U i2 、…、U in )。
2. The time-sharing power supply type single-stage low frequency chain new energy multiport integrated power supply system according to claim 1, wherein: the power supply system adopts an input current instantaneous value feedback maximum power output power limit energy management (SPWM) control strategy of an output voltage independent control loop of a full-bridge high-frequency inverter circuit with an energy storage element, and has three loops of output voltage independent control, multi-input source maximum power point tracking and multi-input source maximum output power limit; the SPWM control strategy is to control the power flow size and direction of the full-bridge high-frequency inverter circuit of the direct current port of the energy storage element in real time according to the relative size of the sum of the system output power and the multi-input source power, so as to realize the maximum power output of the multi-input source and the limitation of the maximum output power under the extreme working condition, the power distribution of the two types of direct current ports, the stability of the system output voltage and the smooth and seamless switching under three different power supply modes, wherein the three power supply modes are a mode I in which the multi-input source supplies power to an output load and the energy storage element, a mode II in which the multi-input source supplies power to the output load and the energy storage element is neither charged nor discharged; the power limiting control is realized by adding n power limiting loops on the basis of the maximum power point tracking loops of n input sources, the output of the n power limiting loops under normal working conditions does not influence the maximum power point tracking loops of the n input sources through n amplitude limiting circuits consisting of diodes and resistors, and the output of the n power limiting loops under extreme working conditions enables the n input sources to exit the maximum power point tracking state through n amplitude limiting circuits consisting of diodes and resistors, so that the output amplitude of the maximum power point loops of the n input sources, the modulation degree of a full-bridge high-frequency inverter circuit of a multi-input source direct current port and the maximum power transmitted by a multi-port power supply system are limited, and the safe and reliable operation of the power supply system is ensured.
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