CN107612030B - Photovoltaic converter with current quasi-critical continuous and device soft switch - Google Patents

Photovoltaic converter with current quasi-critical continuous and device soft switch Download PDF

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CN107612030B
CN107612030B CN201710897049.5A CN201710897049A CN107612030B CN 107612030 B CN107612030 B CN 107612030B CN 201710897049 A CN201710897049 A CN 201710897049A CN 107612030 B CN107612030 B CN 107612030B
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photovoltaic
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CN107612030A (en
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阚加荣
吴云亚
梁艳
吴冬春
薛迎成
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Yancheng Institute of Technology
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers

Abstract

The invention discloses a photovoltaic converter control device with power prediction-based current quasi-critical continuous and device soft switching, which comprises a main circuit, a signal detection circuit and a DSP digital controller. The main circuit comprises two stages of power conversion of an inverter and a rectifier, and the variable inductor is connected with the primary side of the high-frequency transformer in series; the signal detection circuit comprises two voltage sensors and two current sensors; the DSP digital controller comprises a maximum power point tracking module, a photovoltaic cell voltage regulator, a power prediction regulator, a signal modulator, an absolute value module and a variable inductance current regulator. The power regulator rapidly obtains the circuit modulation ratio according to the detection parameters, and the dynamic characteristics of the converter are increased; the variable inductance current regulator ensures that the variable inductance current operates in a quasi-critical mode and can enable the device to realize lossless switching in total. The implementation of the invention can lead the photovoltaic converter to realize rapid dynamic characteristics and higher conversion efficiency.

Description

Photovoltaic converter with current quasi-critical continuous and device soft switch
Technical Field
The invention relates to a photovoltaic converter based on a power prediction method, which is used for realizing soft switching of current quasi-critical continuous devices, and belongs to the technical field of control of power electronic converters.
Background
Photovoltaic power generation is an important form of renewable energy power generation, and has positive and far-reaching significance for relieving the current severe pollution situation. The power generated by the photovoltaic cell cannot be directly used by electric equipment, and a stable power supply form is obtained after the power is processed by the power converter and is transmitted to the electric equipment or the power grid. For low-power photovoltaic converters, designers prefer to operate inductor current design in the converter in a discontinuous mode (DCM) or a critical continuous mode (BCM), but the current stress of the device is larger in DCM, and the BCM needs variable frequency control to realize, which becomes an important reason for restricting the popularization of the low-power photovoltaic converter in a large range. In addition, although the inductor current works in BCM or DCM state, it can realize Zero Current Switching (ZCS) of the switching devices, half of the switching devices in the bridge circuit still have input voltage before the switching devices are turned on, so the energy stored in the parasitic capacitance is consumed when the devices are turned on, and therefore the efficiency of the converter working in DCM or BCM still has difficulty in reaching higher values.
When the traditional photovoltaic converter works, the maximum output power of the photovoltaic battery is ensured, the output voltage of the photovoltaic battery is usually controlled to serve as an outer ring, and the inductance current is usually controlled to serve as an inner ring. The output signal of the voltage ring is regulated by the current inner ring and then is output to the signal to modulate the driving signal, and a certain time is needed, so that the dynamic performance of the converter is slower.
Therefore, it is necessary to find a topology suitable for a photovoltaic converter and a corresponding control device thereof to ensure that the photovoltaic power generation system has efficient, reliable and fast dynamic response characteristics, and the scheme is generated thereby.
Disclosure of Invention
The invention aims to: aiming at the defects of the power conversion technology and the control technology of the existing low-power photovoltaic power generation system, the invention adopts variable inductance to replace the common inductance with fixed inductance in the photovoltaic converter, so that the device can realize a quasi-critical working mode (BCM) in a constant-frequency working state; in BCM state, the device realizing Zero Current Switching (ZCS) still has certain loss when being switched on, the invention detects variable inductance current in each half switching period and performs closed-loop control, so that all devices in the converter realize lossless switching; aiming at the characteristic of slower dynamic characteristics of the existing photovoltaic converter, the dynamic characteristics of the converter can be greatly improved by adopting a power prediction control method.
The technical scheme is as follows: a photovoltaic converter with current quasi-critical continuous and device soft switch comprises a photovoltaic converter main circuit, a signal detection circuit and a DSP digital controller; the main circuit of the photovoltaic converter comprises a photovoltaic cell and an input side filter capacitor C PV High-frequency inverter, variable inductor, high-frequency transformer, rectifier and DC bus filter capacitor C DC And a load; wherein the filter capacitor C at the positive end and the input side of the photovoltaic cell PV The positive terminal of the photovoltaic cell is connected with the first terminal of the high-frequency inverter, and the negative terminal of the photovoltaic cell is connected with the input side filter capacitor C PV Negative terminal of (d) and high frequency inverseA second terminal of the transformer is connected; the third terminal of the high-frequency inverter is connected with the homonymous end of the primary winding W1 of the high-frequency transformer; the two ends of the main winding of the variable inductor are respectively provided with a first terminal and a second terminal, the first terminal of the main winding of the variable inductor is connected with the fourth terminal of the high-frequency inverter, and the second terminal of the main winding of the variable inductor is connected with the different name end of the primary winding W1 of the high-frequency transformer; the homonymous end of the secondary winding W2 of the high-frequency transformer is connected to a first terminal of the rectifier, and the heteronymous end of the secondary winding W2 of the high-frequency transformer is connected to a second terminal of the rectifier; the third terminal of the rectifier is connected to the DC bus filter capacitor C DC A fourth terminal of the rectifier is connected to the DC bus filter capacitor C DC A negative terminal of (a) and a second terminal of the load; the two ends of the auxiliary winding of the variable inductor are respectively a third terminal and a fourth terminal, and the third terminal and the fourth terminal are connected to the output end of the voltage control current source; the signal detection circuit comprises a first voltage sensor, a second voltage sensor, a first current sensor and a second current sensor; wherein a first input end and a second input end of the first voltage sensor are respectively connected to the positive terminal and the negative terminal of the photovoltaic cell, and a first input end and a second input end of the second voltage sensor are respectively connected to the DC bus filter capacitor C DC Positive and negative terminals of (a); the input end of the first current sensor is connected in series with the negative end of the photovoltaic cell and the direct current bus filter capacitor C DC The connecting line of the negative terminal; the input end of the second current sensor is connected in series on a connecting line between the fourth terminal of the high-frequency inverter and the first terminal of the variable inductance main winding; the DSP digital controller comprises a maximum power point tracking module, a first subtracter, a variable inductance current regulator, an absolute value module, a second subtracter, a photovoltaic cell voltage regulator, a power prediction regulator and a signal modulator; wherein the first input end of the maximum power point tracking module is connected to the output end of the first current sensor; the output end of the first voltage sensor is connected to the second input end of the maximum power point tracking module, the negative input end of the second subtracter and the third input end of the power prediction regulator; the positive input end of the second subtracter is connected with the output end of the maximum power point tracking module, and the output end of the second subtracterAn input connected to the photovoltaic cell voltage regulator; the first input terminal and the second input terminal of the power prediction regulator are respectively connected with the output end of the second voltage sensor and the output end of the photovoltaic cell voltage regulator; the input end of the signal regulator is connected to the output end of the power prediction regulator, and the output end signal of the signal regulator is used as a driving signal of a switching device in the high-frequency inverter; the input end of the absolute value module is connected with the output end of the second current sensor, and the positive input end and the negative input end of the first subtracter are respectively connected with a constant signal generated by the DSP digital controller
Figure GDA0004121116070000031
And the output end of the absolute value module; the input end of the variable inductance current regulator is connected to the output end of the first subtracter, and the output end of the variable inductance current regulator is connected to the input end of the voltage control current source.
In the power predictive regulator, signals of a first input terminal, a second input terminal and a third input terminal of the power predictive regulator are U respectively DCf 、P * 、U PVf Respectively represent the DC bus filter capacitor C DC The feedback quantity of the voltage and the output end of the photovoltaic cell voltage regulator output signals, and the feedback quantity of the photovoltaic cell output voltage, the duty ratio D output by the power prediction regulator is:
Figure GDA0004121116070000032
wherein L is r The inductance value of the variable inductor is n, the transformation ratio of the high-frequency transformer is T S Is the switching period of the photovoltaic converter.
Output signal of photovoltaic voltage regulator as output power reference value P of photovoltaic converter * The power prediction regulator directly obtains the required duty ratio of the photovoltaic converter from the detection parameters, so that the regulation time of the regulator in the traditional method is saved, and the dynamic response of the photovoltaic converter is quickened; the variable inductance current regulator ensures that the variable inductance current operates in a quasi-critical continuous state, so that all devices in the photovoltaic converter operate in a nondestructive soft switching state, and the variable inductance current regulator is greatly improvedThe efficiency of the photovoltaic converter is high.
The beneficial effects are that: in the invention, the scheme of controlling the inductance current value in the variable inductance and half period is adopted to realize that the device works in a quasi-critical continuous state, so that on one hand, the current stress of the device is ensured to be smaller, and on the other hand, the lossless switching of all the devices is realized; in addition, the power prediction control technology adopted by the invention ensures that the photovoltaic converter has faster dynamic characteristics. In conclusion, the implementation of the invention can lead the low-power photovoltaic power generation system to have high efficiency and higher performance index.
Drawings
FIG. 1 is a block diagram of an embodiment of the present invention;
FIG. 2 is a schematic diagram of a bridge topology according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a main waveform of a switching cycle according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of the operation of embodiment mode 1 of the present invention;
FIG. 5 is a schematic diagram of the operation of embodiment mode 2 of the present invention;
FIG. 6 is a schematic diagram of the operation of embodiment mode 3 of the present invention;
FIG. 7 is a schematic diagram of the operation of embodiment mode 4 of the present invention;
FIG. 8 is a schematic diagram of the operation of embodiment mode 5 of the present invention;
FIG. 9 is a schematic diagram of the operation of embodiment mode 6 of the present invention;
FIG. 10 is a schematic diagram of a variable inductor and voltage controlled current source according to an embodiment of the present invention;
FIG. 11 is a graph showing the inductance of the variable inductor according to the embodiment of the present invention;
FIG. 12 is a schematic diagram of a variable inductance current detection point according to an embodiment of the present invention;
symbol names in the drawings: u (U) PV -photovoltaic cell output voltage; i PV -photovoltaic cell output current; c (C) PV -a photovoltaic cell filter capacitance; l (L) r -variable inductance; i.e L -a variable inductance current; t-high frequency transformer; n-high frequency transformer transformation ratio; w1-high frequency transformerA primary winding of the presser; w2-secondary winding of high-frequency transformer; c (C) DC -a dc bus equivalent filter capacitor; u (U) DC -dc bus voltage;
Figure GDA0004121116070000041
-a reference value of the variable inductor current at the sampling instant; i Lf -a feedback value of the variable inductance current at the sampling instant; i Le -a variable inductor current negative feedback error value; u (U) con -a variable inductance control voltage value; u (U) PVf -photovoltaic cell output voltage feedback value; i PVf -photovoltaic cell output current feedback value; />
Figure GDA0004121116070000042
-a photovoltaic cell output voltage reference value; u (U) PVe -a photovoltaic cell output voltage negative feedback error value; p (P) * -the converter output power reference value; u (U) DCf -a dc bus voltage feedback value; d-the duty cycle of the converter; u (u) S -a drive signal for the switching tube; S1-S4, namely a first switching tube to a fourth switching tube; d1-D2—first diode to second diode; i.e in -an input side current of the converter; u (u) AB -high frequency inverter ac side voltage; u (u) CD -voltage doubler rectifier ac side voltage; c (C) 1 -C 2 -the voltage doubler rectifier filters the voltage; i.e rec1 -i rec2 -a first diode current to a second diode current; i.e DC -a dc bus outputting current; w (W) r1 -W r2 -a first auxiliary winding and a second auxiliary winding of variable inductance; w (W) r -a main winding of variable inductance; u (U) con -a variable inductance control voltage; i con -variable inductance control current; u (U) 1 -U 2 -a variable inductance first control chip and a second control chip; r is R 1 -R 3 -variable inductance first control resistance to third control resistance; v1-a variable inductance control triode; i con -variable inductance control current.
Detailed Description
The present invention is further illustrated below in conjunction with specific embodiments, it being understood that these embodiments are meant to be illustrative of the invention only and not limiting the scope of the invention, and that modifications of the invention, which are equivalent to those skilled in the art to which the invention pertains, will fall within the scope of the invention as defined in the claims appended hereto.
As shown in fig. 1, a photovoltaic converter with a current quasi-critical continuous and device soft switch comprises a photovoltaic converter main circuit, a signal detection circuit and a DSP digital controller; the main circuit of the photovoltaic converter comprises a photovoltaic cell and an input side filter capacitor C PV High-frequency inverter, variable inductor, high-frequency transformer, rectifier and DC bus filter capacitor C DC And a load; wherein the filter capacitor C at the positive end and the input side of the photovoltaic cell PV The positive terminal of the photovoltaic cell is connected with the first terminal of the high-frequency inverter, and the negative terminal of the photovoltaic cell is connected with the input side filter capacitor C PV Is connected to the negative terminal of the high frequency inverter; the third terminal of the high-frequency inverter is connected with the homonymous end of the primary winding W1 of the high-frequency transformer; the two ends of the main winding of the variable inductor are respectively provided with a first terminal and a second terminal, the first terminal of the main winding of the variable inductor is connected with the fourth terminal of the high-frequency inverter, and the second terminal of the main winding of the variable inductor is connected with the different name end of the primary winding W1 of the high-frequency transformer; the homonymous end of the secondary winding W2 of the high-frequency transformer is connected to a first terminal of the rectifier, and the heteronymous end of the secondary winding W2 of the high-frequency transformer is connected to a second terminal of the rectifier; the third terminal of the rectifier is connected to the DC bus filter capacitor C DC A fourth terminal of the rectifier is connected to the DC bus filter capacitor C DC A negative terminal of (a) and a second terminal of the load; the two ends of the auxiliary winding of the variable inductor are respectively a third terminal and a fourth terminal, and the third terminal and the fourth terminal are connected to the output end of the voltage control current source; the signal detection circuit comprises a first voltage sensor, a second voltage sensor, a first current sensor and a second current sensor; wherein the first input end and the second input end of the first voltage sensor are respectively connected to the positive terminal and the negative terminal of the photovoltaic cell, and the first input end and the second input end of the second voltage sensorThe input ends are respectively connected to the DC bus filter capacitor C DC Positive and negative terminals of (a); the input end of the first current sensor is connected in series with the negative end of the photovoltaic cell and the direct current bus filter capacitor C DC The connecting line of the negative terminal; the input end of the second current sensor is connected in series on a connecting line between the fourth terminal of the high-frequency inverter and the first terminal of the variable inductance main winding; the DSP digital controller comprises a maximum power point tracking module, a first subtracter, a variable inductance current regulator, an absolute value module, a second subtracter, a photovoltaic cell voltage regulator, a power prediction regulator and a signal modulator; wherein the first input end of the maximum power point tracking module is connected to the output end of the first current sensor; the output end of the first voltage sensor is connected to the second input end of the maximum power point tracking module, the negative input end of the second subtracter and the third input end of the power prediction regulator; the positive input end of the second subtracter is connected with the output end of the maximum power point tracking module, and the output end of the second subtracter is connected with the input end of the photovoltaic cell voltage regulator; the first input terminal and the second input terminal of the power prediction regulator are respectively connected with the output end of the second voltage sensor and the output end of the photovoltaic cell voltage regulator; the input end of the signal regulator is connected to the output end of the power prediction regulator, and the output end signal of the signal regulator is used as a driving signal of a switching device in the high-frequency inverter; the input end of the absolute value module is connected with the output end of the second current sensor, and the positive input end and the negative input end of the first subtracter are respectively connected with a constant signal generated by the DSP digital controller
Figure GDA0004121116070000051
And the output end of the absolute value module; the input end of the variable inductance current regulator is connected to the output end of the first subtracter, and the output end of the variable inductance current regulator is connected to the input end of the voltage control current source.
The photovoltaic converter shown in fig. 1 is only required to be connected in series with a high-frequency transformer by a variable inductance, and common half-bridge, full-bridge, forward and flyback converters can be used as the main circuit of the photovoltaic converter of the invention because of the high frequency of the flyback converterThe transformer itself is an inductance function, so that the high-frequency transformer can be designed as a variable self-inductance high-frequency transformer. For the sake of specific description, the bridge converter will be described herein as shown in fig. 2. FIG. 3 shows the waveform of the bridge converter during a switching cycle, FIG. 3 shows the operation of the bridge converter by controlling the variable inductance at t 0 Time and t 3 The values of the moments are respectively
Figure GDA0004121116070000061
And +.>
Figure GDA0004121116070000062
(/>
Figure GDA0004121116070000063
A value greater than zero and close to zero), all the switching tubes S1-S4 in the bridge converter can be ensured to work in a zero-voltage switching state, and no loss exists in the whole process; while the diodes D1-D2 of the secondary side of the high frequency transformer are all commutated in a zero current state.
In fig. 3, the duty cycle D of the converter is defined as
Figure GDA0004121116070000064
In the actual course of the work of the present invention,
Figure GDA0004121116070000065
is a value close to zero, so t 0 -t 1 Time period, t 3 -t 4 The time period is very small and can be ignored approximately, t can be calculated 1 -t 2 The length of the time period is considered as DT S Obtaining the maximum value of the variable inductance current as
Figure GDA0004121116070000066
The input side current i of the photovoltaic converter in Is equal to the average value of
Figure GDA0004121116070000067
/>
The power value processed by the photovoltaic converter is equal to
Figure GDA0004121116070000068
The duty cycle of the converter is thus obtained as
Figure GDA0004121116070000069
If the duty ratio D is found from a known quantity, it is necessary to change the expression (5) to the expression (6).
Figure GDA00041211160700000610
Equation (6) is the power predictive regulator of fig. 1. If all the signal detection has no error, the duty ratio D is theoretically obtained by the calculation of the formula (6), so that the output power of the converter can be ensured to track the reference power value P * This ensures a faster dynamic behavior of the converter.
Corresponding to the converter operation waveforms shown in fig. 3, the corresponding 6 switching mode operation processes in one switching period are briefly described as follows:
switching mode 1[ corresponds to fig. 4]:
t 0 before the moment, the variable inductance current is negative, the switching tubes S1 and S2 are conducted, the secondary rectifying diode D2 of the high-frequency transformer is conducted, and the voltage u is the same AB ＝0，u CD <0, the energy stored in the variable inductance is transferred to the dc bus side through the diode D2. t is t 0 At the moment, the switching tube S2 is turned off, the switching tube S4 is turned on, the variable inductance current is kept to be a negative value, and the voltage u is kept AB >0，u CD <0, so that the energy stored in the variable inductance is transferred to the direct current via the diode D2 on the one handOn the current bus side, on the other hand, to the input side voltage U PV Delivering energy, thus variable inductive current i L Rapidly drop to t 1 Time i L Down to 0.
Switching mode 2[ corresponds to fig. 5]:
t 1 time, i L Down to 0, thereafter, i L To become positive, diode D2 turns off and D1 starts to turn on. Voltage u AB >0，u CD >0, since the bridge circuit is still essentially a buck circuit, the inductor current increases linearly, and the energy stored in the photovoltaic filter capacitor simultaneously transfers energy to the dc bus and the variable inductance.
Switching mode 3[ corresponds to fig. 6]:
t 2 at the moment, the switching tube S1 is turned off, S3 is turned on, the diode D1 is kept on, and the voltage u AB ＝0，u CD >0, the energy stored in the inductor is transmitted to the DC bus side, the energy stored in the variable inductor is reduced, and the current i L Descending.
t 3 At moment, the switching tube S4 is turned off, S2 is turned on, and the corresponding working process and t are carried out 0 -t 3 The time periods are relatively symmetrical, and are not repeated here, and specific switching mode diagrams thereof are shown in fig. 7 to 9.
From the working waveforms shown in fig. 3 and the mode diagrams shown in fig. 4 to 9, it can be seen that the direction of the variable inductance current can always implement effective charge and discharge on the parasitic capacitance of the switching tube in the on and off processes of all the switching tubes, so that it is ensured that all the switching tubes always implement zero-voltage switching, which is significant for improving the efficiency of the converter.
Fig. 10 shows a variable inductance core, winding structure, and circuit of a voltage controlled current source. The variable inductance iron core is composed of a pair of EE type ferrite cores, and the splicing parts of magnetic core columns in the middle of the two EE type iron cores are respectively cut off to form an air gap with a certain length; winding a main winding W of a variable inductance on an intermediate core leg r Auxiliary windings W are wound on the magnetic core columns at two sides respectively r_1 、W r_2 And willThe series connection is performed. The voltage control current source consists of two single power supply operational amplifiers U1-U2, voltage dividing resistors R1-R2, a feedback resistor R3 and a current adjusting tube V1, and the current source controls the voltage U con The voltage is obtained at the positive input end of the operational amplifier U2 through the voltage dividing resistors R1-R2 and a voltage follower
Figure GDA0004121116070000081
According to the principle of the operational amplifier of short and broken, the voltage on the feedback resistor R3 is equal to U 2+ Then
Figure GDA0004121116070000082
The invention discloses a variable inductor, the main winding inductance L r Along with I con The change curve of (2) is shown in FIG. 11. It can be seen that the variable inductance can be changed within the range of 2.8 muh to 8.5 muh by adopting smaller current source loss, i.e. the quasi-critical continuous working mode of the variable inductance current can be realized within a very wide power range.
One advantage of the present invention is that all switching tubes can be switched without loss, and to achieve this feature it must be ensured that when switching tubes S2 are off, S4 are on (t in FIG. 12 a Time instant) current i L Smaller than zero, it is also necessary to ensure that the switching tube S4 is off and S2 is on (t in fig. 12 b Time instant) current i L Greater than zero, must be specific to t a Time and t b The current value at the moment being controlled, i.e. discrete samples t a Time and t b Current i at time instant L The value of the variable inductor is regulated if the detection value is smaller, and vice versa, and finally the current i is caused L At t a Time and t b The absolute value of the moment is equal to
Figure GDA0004121116070000083
In summary, the variable inductor is used in the low-power photovoltaic converter, so that the converter can be ensured to work in a current quasi-critical continuous mode, and the switching device works at constant frequency, so that on one hand, the current stress of the switching device is lower, and on the other hand, the control implementation is convenient; the current value of the variable inductor is detected in each half switching period, so that the variable inductance value is finely adjusted, all switching devices are further enabled to work in a zero-voltage switching state, and the efficiency of the photovoltaic converter is improved; the dynamic response of the converter is obviously improved through power prediction control. Therefore, the invention has the advantages of low device current stress, high conversion efficiency, convenient control and realization and quick dynamic response.

Claims (3)

1. A photovoltaic converter with current quasi-critical continuity and device soft switching, characterized in that: the system comprises a photovoltaic converter main circuit, a signal detection circuit and a DSP digital controller;
the main circuit of the photovoltaic converter comprises a photovoltaic cell and an input side filter capacitor C PV High-frequency inverter, variable inductor, high-frequency transformer, rectifier and DC bus filter capacitor C DC And a load; wherein the filter capacitor C at the positive end and the input side of the photovoltaic cell PV The positive terminal of the photovoltaic cell is connected with the first terminal of the high-frequency inverter, and the negative terminal of the photovoltaic cell is connected with the input side filter capacitor C PV Is connected to the negative terminal of the high frequency inverter; the third terminal of the high-frequency inverter is connected with the homonymous end of the primary winding W1 of the high-frequency transformer; the two ends of the main winding of the variable inductor are respectively provided with a first terminal and a second terminal, the first terminal of the main winding of the variable inductor is connected with the fourth terminal of the high-frequency inverter, and the second terminal of the main winding of the variable inductor is connected with the different name end of the primary winding W1 of the high-frequency transformer; the homonymous end of the secondary winding W2 of the high-frequency transformer is connected to a first terminal of the rectifier, and the heteronymous end of the secondary winding W2 of the high-frequency transformer is connected to a second terminal of the rectifier; the third terminal of the rectifier is connected to the DC bus filter capacitor C DC A fourth terminal of the rectifier is connected to the DC bus filter capacitor C DC A negative terminal of (a) and a second terminal of the load; the two ends of the auxiliary winding of the variable inductor are respectively a third terminal and a fourth terminal, and the third terminal and the fourth terminal are connected to the output end of the voltage control current source;
the signal detection circuit comprises a first voltage sensor, a second voltage sensor, a first current sensor and a second current sensor; wherein a first input end and a second input end of the first voltage sensor are respectively connected to the positive terminal and the negative terminal of the photovoltaic cell, and a first input end and a second input end of the second voltage sensor are respectively connected to the DC bus filter capacitor C DC Positive and negative terminals of (a); the input end of the first current sensor is connected in series with the negative end of the photovoltaic cell and the direct current bus filter capacitor C DC The connecting line of the negative terminal; the input end of the second current sensor is connected in series on a connecting line between the fourth terminal of the high-frequency inverter and the first terminal of the variable inductance main winding;
the DSP digital controller comprises a maximum power point tracking module, a first subtracter, a variable inductance current regulator, an absolute value module, a second subtracter, a photovoltaic cell voltage regulator, a power prediction regulator and a signal modulator; wherein the first input end of the maximum power point tracking module is connected to the output end of the first current sensor; the output end of the first voltage sensor is connected to the second input end of the maximum power point tracking module, the negative input end of the second subtracter and the third input end of the power prediction regulator; the positive input end of the second subtracter is connected with the output end of the maximum power point tracking module, and the output end of the second subtracter is connected with the input end of the photovoltaic cell voltage regulator; the first input terminal and the second input terminal of the power prediction regulator are respectively connected with the output end of the second voltage sensor and the output end of the photovoltaic cell voltage regulator; the input end of the signal regulator is connected to the output end of the power prediction regulator, and the output end signal of the signal regulator is used as a driving signal of a switching device in the high-frequency inverter; the input end of the absolute value module is connected with the output end of the second current sensor, and the positive input end and the negative input end of the first subtracter are respectively connected with a constant signal I generated by the DSP digital controller L * And the output end of the absolute value module; variable inductance currentAn input of the regulator is connected to an output of the first subtractor and an output of the variable inductor current regulator is connected to an input of the voltage controlled current source.
2. The photovoltaic converter of claim 1 wherein: the signals of the first input terminal, the second input terminal and the third input terminal of the power prediction regulator are U respectively DCf 、P * 、U PVf Respectively represent the DC bus filter capacitor C DC The feedback quantity of the voltage and the output end of the photovoltaic cell voltage regulator output signals, and the feedback quantity of the photovoltaic cell output voltage, the duty ratio D output by the power prediction regulator is:
Figure FDA0004121116060000021
wherein L is r The inductance value of the variable inductor is n, the transformation ratio of the high-frequency transformer is T S Is the switching period of the photovoltaic converter.
3. The photovoltaic converter of claim 1 wherein: output signal of photovoltaic voltage regulator as output power reference value P of photovoltaic converter * The power prediction regulator directly obtains the required duty ratio of the photovoltaic converter from the detection parameters, so that the regulation time of the regulator in the traditional method is saved, and the dynamic response of the photovoltaic converter is quickened; the variable inductance current regulator ensures that the variable inductance current operates in a quasi-critical continuous state, so that all devices in the photovoltaic converter operate in a lossless soft switching state, and the efficiency of the photovoltaic converter is greatly improved.
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* Cited by examiner, † Cited by third party
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CN105048490A (en) * 2015-06-24 2015-11-11 盐城工学院 Low current stress photovoltaic micro inverter and digital control device associated with the same
CN105978389A (en) * 2016-07-11 2016-09-28 盐城工学院 Low-frequency current ripple inhibition digital control apparatus of bridge type micro inverter
CN106411115A (en) * 2016-11-21 2017-02-15 盐城工学院 Method of continuously extending work range of variable inductors

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105048490A (en) * 2015-06-24 2015-11-11 盐城工学院 Low current stress photovoltaic micro inverter and digital control device associated with the same
CN105978389A (en) * 2016-07-11 2016-09-28 盐城工学院 Low-frequency current ripple inhibition digital control apparatus of bridge type micro inverter
CN106411115A (en) * 2016-11-21 2017-02-15 盐城工学院 Method of continuously extending work range of variable inductors

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