A dual-input interface energy storage grid inverter and control method thereof

Abstract

The present invention discloses a dual-input interface energy storage grid-type inverter and a control method thereof: the inverter mainly includes two DC inputs, seven switch tubes, two diodes, and a load. Aiming at the problems of numerous switch devices, single application scenarios, and low energy supply stability of traditional multi-level inverters, a dual-input interface energy storage grid-type inverter and a control method thereof realize the inversion function of the energy storage grid-type converter through topological design and control methods according to the characteristics of dual DC input sources and inversion requirements, realizes multi-level with seven switch tubes, and simplifies the circuit structure; compared with traditional multi-level inverters, the present invention reduces the number of switch tubes, reduces system complexity and cost, and the dual-input interface design enhances the stability and flexibility of the system, can automatically adjust the working mode according to different energy supply conditions, optimizes energy utilization efficiency, and broadens the application scenarios of the inverter.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics, and in particular to an energy storage grid-forming inverter with dual input interfaces and a control method thereof. Background Art

[0002] As the global energy crisis and environmental pollution become increasingly prominent, the use of renewable energy has received widespread attention. Among the many renewable energy technologies, energy storage inverters are particularly important because they can convert unstable renewable energy into stable and usable electricity. Traditional inverters are mostly single-input interfaces, which are difficult to meet the needs of efficient energy conversion and management, resulting in low power conversion efficiency and increased system complexity.

[0003] Although existing energy storage inverters have solved the problem of stable output of electric energy to a certain extent, they usually face challenges such as insufficient system reliability and poor adaptability to the power grid.

[0004] In order to solve the above problems and improve the adaptability and flexibility of the energy storage grid-forming inverter, the present invention proposes an energy storage grid-forming inverter with dual input interfaces and a control method thereof. Summary of the invention

[0005] The present invention discloses an energy storage grid-forming inverter with a dual-input interface, and proposes a corresponding control method. By adopting a dual-input interface design, simultaneous access to multiple energy sources such as a DC power supply, an energy storage battery, a supercapacitor and a solar panel is achieved. In terms of control, the output voltage is flexibly adjusted by controlling the duty cycle of the switch tube, thereby achieving efficient energy conversion and enhancing the flexibility and reliability of the system.

[0006] A dual-input interface energy storage grid inverter includes a main circuit unit and a main control unit:

[0007] The main circuit unit includes a first DC power supply V dc1 , the second DC power supply V dc2 , a first switch tube S1, a second switch tube S2, a third switch tube S3, a fourth switch tube S4, a fifth switch tube S5, a sixth switch tube S6, a seventh switch tube S7, a first diode D1, a second diode D2, and a load Z;

[0008] The main control unit includes: a voltage sensor, a current sensor, a first adder SUM1, a second adder SUM2, a voltage loop PR regulator G v , Current loop regulator G i , SPWM modulation unit, driving circuit;

[0009] Preferably, the voltage sensor is a Hall voltage sensor;

[0010] Preferably, the current sensor is a Hall current sensor;

[0011] The dual input interfaces in the energy storage grid inverter with dual input interfaces are one or two of a DC power supply, an energy storage battery, a super capacitor, a solar panel, and an uninterruptible power supply.

[0012] The energy storage grid-forming inverter with dual input interfaces generates five different output levels in each working cycle, namely: a first forward voltage, a second forward voltage, zero voltage, a first reverse voltage, and a second reverse voltage.

[0013] When the output voltage is the first forward voltage, the third switch tube S3 and the sixth switch tube S6 are turned on, and the other switch tubes and other diodes are turned off. The output voltage is V0. dc1 +V dc2 ;

[0014] When the output voltage is the forward second voltage, the fifth switch tube S5, the sixth switch tube S6 and the second diode D2 are turned on, and the other switch tubes and the first diode D1 are turned off, and the output voltage V0 is V dc2 ;

[0015] When the output voltage is zero voltage, the sixth switch tube S6 and the seventh switch tube S7 are turned on, the other switch tubes and other diodes are turned off, and the output voltage V0 is 0;

[0016] When the output voltage is the reverse first voltage, the first switch tube S1, the fourth switch tube S4, the seventh switch tube S7 and the first diode D1 are turned on, and the other switch tubes and the second diode D2 are turned off, and the output voltage V0 is -V dc2 ;

[0017] When the output voltage is the reverse second voltage, the first switch tube S1, the second switch tube S2 and the seventh switch tube S7 are turned on, and the other switch tubes and other diodes are turned off, and the output voltage V0 is -V dc1 -V dc2 .

[0018] A specific control method of a dual-input interface energy storage grid inverter is as follows:

[0019] S1: First DC power supply V dc1 and the second DC power supply V dc2 Power is supplied to the load Z, the voltage sensor detects the output voltage V0, and the current sensor detects the output current I0;

[0020] S2: Output voltage V0 and reference voltage V ref After comparison by the first adder SUM1, the first error signal e is output V1 , the first error signal e V1 After the voltage loop PR regulator Gv Output the first adjustment signal I1, the first adjustment signal I1 and the output current I0 are compared by the second adder SUM2 to output the second error signal e I1 , the second error signal e I1 Through the current loop regulator G i The second regulating signal U1 is output, and the second regulating signal U1 is output through the SPWM modulation unit to output the first modulation signal P1, the second modulation signal P2, the third modulation signal P3, the fourth modulation signal P4, the fifth modulation signal P5, the sixth modulation signal P6, and the seventh modulation signal P7 to the driving circuit, and the driving circuit outputs control signals to control the duty cycles of the first switch tube S1, the second switch tube S2, the third switch tube S3, the fourth switch tube S4, the fifth switch tube S5, the sixth switch tube S6, and the seventh switch tube S7 respectively.

[0021] The energy storage grid-forming inverter with dual input interfaces provided by the present invention has the following advantages:

[0022] First, seven switching tubes and two diodes are used to realize the corresponding inverter function. The inverter uses a limited number of switching devices, has a simple design and low cost, and effectively overcomes the problems caused by the existing single-phase five-level inverter due to the large number of switching devices and complex structure.

[0023] Second, the input interface is one or two of the following: DC power supply, energy storage battery, super capacitor, solar panel, and uninterruptible power supply, which gives the system a high degree of flexibility. When one energy source is insufficient or fails, the system can automatically switch to other available energy sources, enhancing the redundancy and fault tolerance of the system, while helping to balance the energy consumption cost of the system in different time periods and under different load conditions.

[0024] The control method of the single-phase five-level inverter provided by the present invention has the following advantages:

[0025] By adopting dual closed-loop regulation of voltage PR voltage loop regulator and current regulator, five-level output can be achieved by controlling the opening and closing of seven switching tubes, realizing static error-free tracking of output voltage and current signals, and improving the stability, accuracy and output waveform quality of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings in the embodiments will be briefly introduced below. The technical solutions in the embodiments of the present invention will be clearly and completely described in combination with the drawings of the present invention. Obviously, the described embodiments are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1A schematic diagram of the structure of an energy storage grid-forming inverter with dual input interfaces according to an embodiment of the present invention;

[0028] Figure 2 A schematic diagram of the working principle of an energy storage grid-forming inverter with dual input interfaces in an embodiment of the present invention;

[0029] Figure 3 It is a flow chart of a main control unit of an energy storage grid-forming inverter with dual input interfaces in an embodiment of the present invention;

[0030] Figure 4 It is a flow chart of a control method of a dual-input interface energy storage grid-type inverter in an embodiment of the present invention;

[0031] Figure 5 Schematic diagram of five-level output waveforms of a dual-input energy storage grid inverter in an embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to clearly illustrate the purpose, technical solutions and features of the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be further described below in combination with the prior art and the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0033] Please refer to Figure 1 , Figure 1 A schematic diagram of a topological structure of an energy storage grid-forming inverter with dual input interfaces of the present invention, comprising: a main circuit unit and a main control unit;

[0034] The main circuit unit includes a first DC power supply V dc1 , the second DC power supply V dc2 , a first switch tube S1, a second switch tube S2, a third switch tube S3, a fourth switch tube S4, a fifth switch tube S5, a sixth switch tube S6, a seventh switch tube S7, a first diode D1, a second diode D2, and a load Z;

[0035] The emitter of the first switch tube S1 is connected to the negative electrode of the load Z and the collector of the sixth switch tube S6, and the collector of the first switch tube S1 is connected to the emitter of the second switch tube S2 and the cathode of the first diode D1;

[0036] The collector of the second switch tube S2 and the collector of the third switch tube S3, the first DC power supply V dc1 The positive connection of

[0037] The emitter of the third switch tube S3 is connected to the positive electrode of the load Z, the cathode of the second diode D2, and the collector of the seventh switch tube S7;

[0038] The emitter of the fourth switch tube S4 is connected to the anode of the first diode D1, and the collector of the fourth switch tube S4 is connected to the first DC power supply V dc1 The negative pole of the second DC power supply V dc2 The positive electrode and the collector of the fifth switch tube S5 are connected;

[0039] The emitter of the fifth switch tube S5 is connected to the anode of the second diode D2;

[0040] The emitter of the sixth switch tube S6 and the emitter of the seventh switch tube S7, the second DC power supply V dc2 The negative connection of

[0041] The main control unit includes: a current sensor, a voltage sensor, a first adder SUM1, a second adder SUM2, a voltage loop PR regulator G v , Current loop regulator G i , SPWM modulation unit, driving circuit;

[0042] The input end of the voltage sensor is connected between the positive electrode of the load Z and the negative electrode of the load Z, and the output end of the voltage sensor is connected to the negative input end of the first adder SUM1; the input end of the current sensor is connected to the positive electrode of the load Z, and the output end of the current sensor is connected to the negative input end of the second adder SUM2; the output end of the first adder SUM1 is connected to the voltage loop PR regulator G v Input terminal of voltage loop PR regulator G v The output end of the second adder SUM2 is connected to the positive input end of the current loop regulator G i Input terminal of current loop regulator G i an output end of the SPWM modulation unit is connected to an input end of the SPWM modulation unit; a first output end of the SPWM modulation unit is connected to a first input end of the driving circuit, a second output end of the SPWM modulation unit is connected to a second input end of the driving circuit, a third output end of the SPWM modulation unit is connected to a third input end of the driving circuit, a fourth output end of the SPWM modulation unit is connected to a fourth input end of the driving circuit, a fifth output end of the SPWM modulation unit is connected to a fifth input end of the driving circuit, a sixth output end of the SPWM modulation unit is connected to a sixth input end of the driving circuit, and a seventh output end of the SPWM modulation unit is connected to a seventh input end of the driving circuit.

[0043] Preferably, the voltage sensor is a Hall voltage sensor;

[0044] Preferably, the current sensor is a Hall current sensor;

[0045] The dual input interfaces in the energy storage grid inverter with dual input interfaces are one or two of a DC power supply, an energy storage battery, a super capacitor, a solar panel, and an uninterruptible power supply.

[0046] Please refer to Figure 2 , Figure 2 The figure is a schematic diagram of the working principle of a dual-input interface energy storage grid inverter of the present invention.

[0047] When the output voltage is the first forward voltage, the third switch tube S3 and the sixth switch tube S6 are turned on, and the other switch tubes and other diodes are turned off. The output voltage is V0. dc1 +V dc2 ;

[0048] When the output voltage is the forward second voltage, the fifth switch tube S5, the sixth switch tube S6 and the second diode D2 are turned on, and the other switch tubes and the first diode D1 are turned off, and the output voltage V0 is V dc2 ;

[0049] When the output voltage is zero voltage, the sixth switch tube S6 and the seventh switch tube S7 are turned on, the other switch tubes and other diodes are turned off, and the output voltage V0 is 0;

[0050] When the output voltage is the reverse first voltage, the first switch tube S1, the fourth switch tube S4, the seventh switch tube S7 and the first diode D1 are turned on, and the other switch tubes and the second diode D2 are turned off, and the output voltage V0 is -V dc2 ;

[0051] When the output voltage is the reverse second voltage, the first switch tube S1, the second switch tube S2 and the seventh switch tube S7 are turned on, and the other switch tubes and other diodes are turned off, and the output voltage V0 is -V dc1 -V dc2 .

[0052] Please refer to Figure 3 and Figure 4 , Figure 3 This is the flow chart of the control unit. Figure 4 is a flow chart of the control method, according to Figure 3 and Figure 4 The energy storage grid-connected inverter with dual input interfaces in this paper is analyzed, and the specific control method is as follows:

[0053] S1: First DC power supply V dc1 and the second DC power supply V dc2 Power is supplied to the load Z, the voltage sensor detects the output voltage V0, and the current sensor detects the output current I0;

[0054] S2: Output voltage V0 and reference voltage V refAfter comparison by the first adder SUM1, the first error signal e is output V1 , the first error signal e V1 After the voltage loop PR regulator G v Output the first adjustment signal I1, the first adjustment signal I1 and the output current I0 are compared by the second adder SUM2 to output the second error signal e I1 , the second error signal e I1 Through the current loop regulator G i The second regulating signal U1 is output, and the second regulating signal U1 is output through the SPWM modulation unit to output the first modulation signal P1, the second modulation signal P2, the third modulation signal P3, the fourth modulation signal P4, the fifth modulation signal P5, the sixth modulation signal P6, and the seventh modulation signal P7 to the driving circuit, and the driving circuit outputs control signals to control the duty cycles of the first switch tube S1, the second switch tube S2, the third switch tube S3, the fourth switch tube S4, the fifth switch tube S5, the sixth switch tube S6, and the seventh switch tube S7 respectively.

[0055] Please refer to Figure 5 , assuming that the first DC power supply V dc1 and the first DC power supply V dc2 Equal to V dc In the case of Figure 5 This is a schematic diagram of output waveforms in an embodiment of an energy storage grid-type inverter with dual input interfaces proposed by the present invention.

[0056] By using sinusoidal pulse width modulation technology, the modulation pulse is changed so that the time duty cycle of the pulse width is arranged according to the sinusoidal law, thereby adjusting the conduction time of the switch tube and making the output waveform close to a sinusoidal waveform after proper filtering. Assuming that the load is inductive, the load current I0 will lag slightly behind the output voltage.

[0057] It should be noted that, in this specification, relational terms such as first and second, etc. are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

[0058] Although the above describes the specific implementation methods of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention; the description of the embodiments disclosed in the present invention enables professional and technical personnel in the field to use or implement the present invention, and they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these replacements or modifications do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of each embodiment of the present application.

Claims

1. A dual-input interface energy storage grid inverter, characterized in that: Including main circuit unit and main control unit: The main circuit unit includes a first DC power supply V dc1 , the second DC power supply V dc2 , a first switch tube S1, a second switch tube S2, a third switch tube S3, a fourth switch tube S4, a fifth switch tube S5, a sixth switch tube S6, a seventh switch tube S7, a first diode D1, a second diode D2, and a load Z; The emitter of the first switch tube S1 is connected to the negative electrode of the load Z and the collector of the sixth switch tube S6, and the collector of the first switch tube S1 is connected to the emitter of the second switch tube S2 and the cathode of the first diode D1; The collector of the second switch tube S2 and the collector of the third switch tube S3, the first DC power supply V dc1 The positive connection of The emitter of the third switch tube S3 is connected to the positive electrode of the load Z, the cathode of the second diode D2, and the collector of the seventh switch tube S7; The emitter of the fourth switch tube S4 is connected to the anode of the first diode D1, and the collector of the fourth switch tube S4 is connected to the first DC power supply V dc1 The negative pole of the second DC power supply V dc2 The positive electrode of the switch tube S5 is connected to the collector of the fifth switch tube S5; The emitter of the fifth switch tube S5 is connected to the anode of the second diode D2; The emitter of the sixth switch tube S6 and the emitter of the seventh switch tube S7, the second DC power supply V dc2 negative connection.

2. The energy storage grid inverter with dual input interfaces according to claim 1, characterized in that: The main control unit includes: a voltage sensor, a current sensor, a first adder SUM1, a second adder SUM2, a voltage loop PR regulator G v , Current loop regulator G i , SPWM modulation unit, driving circuit; The input end of the voltage sensor is connected between the positive electrode of the load Z and the negative electrode of the load Z, and the output end of the voltage sensor is connected to the negative input end of the first adder SUM1; the input end of the current sensor is connected to the positive electrode of the load Z, and the output end of the current sensor is connected to the negative input end of the second adder SUM2; the output end of the first adder SUM1 is connected to the voltage loop PR regulator G v The input end of the voltage loop PR regulator G v The output end of the second adder SUM2 is connected to the positive input end of the current loop regulator G i The input end of the current loop regulator G i an output end of the SPWM modulation unit is connected to an input end of the SPWM modulation unit; a first output end of the SPWM modulation unit is connected to a first input end of the drive circuit, a second output end of the SPWM modulation unit is connected to a second input end of the drive circuit, a third output end of the SPWM modulation unit is connected to a third input end of the drive circuit, a fourth output end of the SPWM modulation unit is connected to a fourth input end of the drive circuit, a fifth output end of the SPWM modulation unit is connected to a fifth input end of the drive circuit, a sixth output end of the SPWM modulation unit is connected to a sixth input end of the drive circuit, and a seventh output end of the SPWM modulation unit is connected to a seventh input end of the drive circuit.

3. The energy storage grid inverter with dual input interfaces according to claim 1, characterized in that: The dual input interfaces in the energy storage grid inverter with dual input interfaces are one or two of a DC power supply, an energy storage battery, a super capacitor, a solar panel, and an uninterruptible power supply.

4. The energy storage grid inverter with dual input interfaces according to claim 1, characterized in that: The energy storage grid inverter with dual input interfaces generates five different output levels in each working cycle, namely: a first forward voltage, a second forward voltage, zero voltage, a first reverse voltage, and a second reverse voltage.

5. The energy storage grid inverter with dual input interfaces according to claim 4, characterized in that: When the output voltage is the first forward voltage, the third switch tube S3 and the sixth switch tube S6 are turned on, the other switch tubes and the other diodes are turned off, and the output voltage is V0. dc1 +V dc2 ; When the output voltage is the forward second voltage, the fifth switch tube S5, the sixth switch tube S6 and the second diode D2 are turned on, and the other switch tubes and the first diode D1 are turned off, and the output voltage V0 is V dc2 ; When the output voltage is zero voltage, the sixth switch tube S6 and the seventh switch tube S7 are turned on, the other switch tubes and the other diodes are turned off, and the output voltage V0 is 0; When the output voltage is the reverse first voltage, the first switch tube S1, the fourth switch tube S4, the seventh switch tube S7 and the first diode D1 are turned on, and the other switch tubes and the second diode D2 are turned off, and the output voltage V0 is -V dc2 ; When the output voltage is the reverse second voltage, the first switch tube S1, the second switch tube S2 and the seventh switch tube S7 are turned on, the other switch tubes and the other diodes are turned off, and the output voltage V0 is -V dc1 -V dc2 .

6. A dual-input interface energy storage grid inverter according to any one of claims 1 to 5, characterized in that: Each switch tube in the inverter is an IGBT with a reverse parallel freewheeling diode.

7. A control method for a dual-input interface energy storage grid inverter, characterized in that: The energy storage grid inverter with dual input interfaces used in any one of claims 1 to 6, wherein the specific control method is: S1: The first DC power supply V dc1 and the second DC power supply V dc2 Power is supplied to the load Z, a voltage sensor detects an output voltage V0, and a current sensor detects an output current I0; S2: Output voltage V0 and reference voltage V ref After comparison by the first adder SUM1, the first error signal e is output V1 , the first error signal e V1 After the voltage loop PR regulator G v Output the first adjustment signal I1, the first adjustment signal I1 and the output current I0 are compared by the second adder SUM2 to output the second error signal e I1 , the second error signal e I1 Through the current loop regulator G i The second regulating signal U1 is output, and the second regulating signal U1 is output through the SPWM modulation unit to output the first modulation signal P1, the second modulation signal P2, the third modulation signal P3, the fourth modulation signal P4, the fifth modulation signal P5, the sixth modulation signal P6, and the seventh modulation signal P7 to the driving circuit, and the driving circuit outputs control signals to respectively control the duty ratios of the first switch tube S1, the second switch tube S2, the third switch tube S3, the fourth switch tube S4, the fifth switch tube S5, the sixth switch tube S6, and the seventh switch tube S7.

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