Household optical storage all-in-one machine

Abstract

The household optical storage all-in-one machine comprises a photovoltaic input Vdc, the two ends of the photovoltaic input Vdc are connected with split capacitors in parallel, and the split capacitors comprise the first split capacitor C1 and the second split capacitor C2 which are connected in series; the second split capacitor C2 is connected with the source electrode of the first switch tube S1, and a first diode D1 is connected in series between the drain electrode of the first switch tube S1 and the midpoint of the first split capacitor C1 and the second split capacitor C2; the active power decoupling circuit is connected in parallel between the drain electrode of the first switching tube S1 and the positive electrode of the first split capacitor C1, the active power decoupling circuit is connected to the non-isolated full-bridge inverter circuit, and the output of the non-isolated full-bridge inverter circuit is connected to the AC side output through the filter circuit. According to the invention, the suppression effect on common-mode current and direct-current side power fluctuation can be realized at the same time.

Description

Technical Field

[0001] This invention belongs to the field of energy consumption in the power industry, and specifically relates to a residential photovoltaic-storage integrated machine. Background Technology

[0002] Residential integrated photovoltaic (PV) and energy storage systems are devices installed in homes that can simultaneously connect to PV, energy storage, and charging ports. They provide flexible energy storage and respond to grid adjustments based on active and reactive power. Especially in rural areas, residential PV systems can effectively utilize solar energy resources and flexibly store energy through storage devices. However, existing integrated PV and energy storage systems are bulky, have low operating efficiency, and are not suitable for residential use. Several technical issues remain to be addressed in system operation.

[0003] Firstly, to miniaturize the integrated photovoltaic and energy storage system, a non-isolated inverter structure was chosen for residential photovoltaic inverters. Non-isolated inverters offer advantages such as small size, compact structure, and high efficiency. However, the parasitic capacitance between the photovoltaic panel and ground forms a coupling circuit, generating common-mode current. This not only affects the normal operation of the system but may also adversely impact grid stability. Existing technologies primarily address the common-mode current problem by modifying the inverter topology to suppress common-mode voltage variations.

[0004] Another technical challenge is the presence of secondary pulsating power at the DC port of residential photovoltaic inverters. This means that instantaneous power fluctuations included in the AC output power are coupled to the DC port, causing DC bus voltage fluctuations. Traditionally, large-capacity electrolytic capacitors are used in residential photovoltaic inverters to absorb these fluctuations. However, electrolytic capacitors are large and have short lifespans, limiting the reliability and compactness of the system.

[0005] In summary, existing residential photovoltaic integrated machines still have shortcomings in suppressing common-mode current and solving secondary pulsating power problems. Designing a high-efficiency and compact photovoltaic energy storage integrated topology has important application value, which can improve the stability and reliability of system operation and help to achieve miniaturization and cost reduction of equipment. Summary of the Invention

[0006] Purpose of the invention: The purpose of this invention is to provide a residential photovoltaic integrated machine that can simultaneously suppress common-mode current and DC-side power fluctuations.

[0007] Technical solution: The basic residential photovoltaic integrated machine of the present invention includes a photovoltaic input V dc The photovoltaic input V dc A split capacitor is connected in parallel at both ends. The split capacitor includes a first split capacitor C1 and a second split capacitor C2 connected in series.

[0008] The second split capacitor C2 is connected to the source of the first switching transistor S1, and the drain of the first switching transistor S1 is connected in series with the midpoint between the first split capacitor C1 and the second split capacitor C2.

[0009] An active power decoupling circuit is connected in parallel between the drain of the first switching transistor S1 and the positive terminal of the first split capacitor C1. The active power decoupling circuit is then connected to a non-isolated full-bridge inverter circuit. The output of the non-isolated full-bridge inverter circuit is connected to the AC side output through a filter circuit.

[0010] Furthermore, the active power decoupling circuit includes a second switch S2, a third switch S3, and a decoupling inductor L1, wherein the drain of the second switch S2 is connected to the positive terminal of the photovoltaic power supply, the source of the second switch S2 is connected to the drain of the third switch S3, and the source of the third switch S3 is connected to the drain of the first switch S1.

[0011] The drain of the third switch S3 and the source of the third switch S3 are connected in series with a decoupling inductor L1 and an energy storage battery VB. The energy storage battery VB is used to absorb power fluctuations on the DC bus and to provide power supply when photovoltaic input is insufficient.

[0012] Furthermore, the non-isolated full-bridge inverter circuit includes a fourth switch S4, a fifth switch S5, a sixth switch S6, and a seventh switch S7. The drains of the fourth switch S4 and the sixth switch S6 are both connected to the photovoltaic input V. dc The positive terminal is connected to the source of the fourth switch S4 and the drain of the fifth switch S5. The source of the sixth switch S6 is connected to the drain of the seventh switch S7. The sources of the fifth switch S5 and the seventh switch S7 are both connected to the drain of the first switch S1.

[0013] Furthermore, the filtering circuit includes a first filtering inductor L2 and a second filtering inductor L3. One end of the first filtering inductor L2 is connected to the source of the fourth switching transistor S4, and the other end is connected to the AC output V. g The positive electrode;

[0014] One end of the second filter inductor L3 is connected to the drain of the seventh switch S7, and the other end is connected to the AC output V. g The negative electrode.

[0015] Furthermore, the active power decoupling circuit and the non-isolated H5-D inverter circuit each employ a different control method.

[0016] Furthermore, the control method of the non-isolated H5-D inverter circuit is as follows:

[0017] The grid voltage vg is sampled by a phase-locked loop to obtain the grid phase wt. The grid phase wt is combined with the given grid current amplitude Ig to obtain the reference value Igsinwt of the grid current. The reference value Igsinwt of the grid current is compared with the actual value ig of the grid current, and the difference Δi between the reference value Igsinwt and the actual value ig of the grid current is input to the PR controller to obtain the reference value vg_ref of the grid voltage. The reference value vg_ref of the grid voltage is compared with the carrier wave by PWM to obtain the drive signals of the first switch S1, the fourth switch S4, the fifth switch S5, the sixth switch S6 and the seventh switch S7 in the non-isolated H5-D inverter circuit.

[0018] Furthermore, the transfer function G of the PR controller PR (s) is

[0019]

[0020] Among them, K p K r w and w represent proportional gain, resonant gain coefficient, and resonant frequency, respectively; s represents a complex variable.

[0021] Furthermore, the control method of the active power decoupling circuit is as follows:

[0022] The energy storage voltage of the battery in the active power decoupling circuit is controlled. The actual energy storage voltage value vB is sampled and processed by a low-pass filter LPF to obtain the average energy storage voltage VB.

[0023] The difference between the average voltage VB and the energy storage voltage reference value VB* is used to obtain one of the reference values ​​of the decoupling current IB_1* through the PI controller.

[0024] The DC bus voltage is controlled. The actual value of the DC bus voltage, vdc, is processed by a bandpass filter (BPF) to obtain the actual component Δvdc of the second harmonic frequency. The difference between the actual component of the second harmonic frequency and the reference value Δvdc* of the second harmonic frequency component is calculated. The difference between the actual component of the second harmonic frequency and the reference value Δvdc* of the second harmonic frequency component is used by the PI controller to obtain another reference value IB_2* for the decoupling current.

[0025] The reference values ​​IB_1* and IB_2* of the decoupling current are compared with the actual value iB of the decoupling current. The comparison results are processed by the PR controller to obtain the modulation wave of the active power decoupling circuit.

[0026] By comparing the modulation wave and carrier wave of the active power decoupling circuit with PWM, drive signals for the second switch S2 and the third switch S3 in the active power decoupling circuit are generated.

[0027] Furthermore, the transfer function G of the PI controller PI (s) is

[0028]

[0029] Among them, K p K i These represent the proportional gain and integral gain coefficients, respectively; s represents a complex variable.

[0030] Beneficial effects: Compared with the prior art, the significant technical effects of the present invention are as follows:

[0031] This invention enables the use of a non-isolated full-bridge inverter circuit in residential photovoltaic-storage integrated machines, thereby automatically maintaining a constant common-mode voltage and suppressing common-mode current caused by parasitic capacitance in the photovoltaic panels.

[0032] This invention uses an active power decoupling circuit in a residential photovoltaic storage unit to suppress the coupling of AC power fluctuations to the DC side.

[0033] This invention enables the decoupling of active power topology to be reused as an energy storage structure, which can release or absorb energy when photovoltaic output is insufficient or overflowing, without the need to add an additional energy storage circuit.

[0034] This invention, through its non-isolated inverter design, helps to meet the design needs of compact and miniaturized integrated photovoltaic and energy storage systems. Attached Figure Description

[0035] Figure 1 This is a circuit diagram of a residential photovoltaic and energy storage integrated machine disclosed in an embodiment of the present invention;

[0036] Figure 2 This is a control principle diagram of a non-isolated full-bridge inverter circuit disclosed in an embodiment of the present invention;

[0037] Figure 3 This is a control principle diagram of an active power decoupling circuit disclosed in an embodiment of the present invention. Detailed Implementation

[0038] The technical solution of the present invention will now be described in detail with reference to specific embodiments and accompanying drawings.

[0039] Please see Figure 1 , Figure 1 This is a circuit diagram of a residential photovoltaic and energy storage integrated system disclosed in an embodiment of the present invention. The residential photovoltaic and energy storage integrated system of this embodiment includes a photovoltaic input V...dc Photovoltaic input V dc A split capacitor is connected in parallel across the two ends. The split capacitor includes a first split capacitor C1 and a second split capacitor C2 connected in series. The second split capacitor C2 is connected to the source of the first switching transistor S1. A first diode D1 is connected in series between the drain of the first switching transistor S1 and the midpoint of the first split capacitor C1 and the second split capacitor C2. An active power decoupling circuit is connected in parallel between the drain of the first switching transistor S1 and the positive terminal of the first split capacitor C1. After the active power decoupling circuit, a non-isolated full-bridge inverter circuit is connected. The output of the non-isolated full-bridge inverter circuit is connected to the AC output through a filter circuit.

[0040] In one embodiment of the present invention, the positive terminal of the first diode D1 is connected to the drain of the first switching transistor S1, and its negative terminal is connected to the midpoint of the first split capacitor C1 and the second split capacitor C2.

[0041] The active power decoupling circuit employs a half-bridge configuration, comprising a second switch S2, a third switch S3, and a decoupling inductor L1. The second and third switches S2 and S3 are connected in a half-bridge configuration. The drain of the second switch S2 is connected to the positive terminal of the photovoltaic power source, and its source is connected to the drain of the third switch S3. The source of the third switch S3 is connected to the drain of the first switch S1. The decoupling inductor L1 and the energy storage battery VB are connected in series between the drain and source of the third switch S3. The energy storage battery VB is used to absorb power fluctuations on the DC bus and as an energy storage element to provide power when photovoltaic input is insufficient. This active power decoupling circuit can suppress AC-side power fluctuations from coupling to the DC side.

[0042] The non-isolated full-bridge inverter circuit includes a first switch S1, a fourth switch S4, a fifth switch S5, a sixth switch S6, and a seventh switch S7. The drains of the fourth switch S4 and the sixth switch S6 are both connected to the photovoltaic input V. dc On the positive terminal, the source of the fourth switch S4 is connected to the drain of the fifth switch S5, and the source of the sixth switch S6 is connected to the drain of the seventh switch S7. The sources of both the fifth switch S5 and the seventh switch S7 are connected to the drain of the first switch S1. This non-isolated full-bridge inverter circuit can maintain a constant common-mode voltage, thereby suppressing common-mode current. The topology design of the non-isolated inverter facilitates efficient and compact device design.

[0043] The filter circuit includes a first filter inductor L2 and a second filter inductor L3. One end of the first filter inductor L2 is connected to the source of the fourth switch S4, and the other end is connected to the AC output V. g The positive electrode;

[0044] One end of the second filter inductor L3 is connected to the drain of the seventh switch S7, and the other end is connected to the AC output V. g The negative electrode.

[0045] In this invention, the active power decoupling circuit and the non-isolated full-bridge inverter circuit are controlled separately, using independent control methods. Specifically:

[0046] like Figure 2 As shown, the control method of the non-isolated H5-D inverter circuit is as follows:

[0047] The grid voltage vg is sampled by a phase-locked loop to obtain the grid phase wt. Then, the grid phase wt is combined with the given grid current amplitude Ig to obtain the reference value Igsinwt of the grid current. The reference value Igsinwt of the grid current is compared with the actual value ig of the grid current, and the difference Δi between the reference value Igsinwt and the actual value ig of the grid current is input to the PR controller to obtain the reference value vg_ref of the grid voltage. Finally, the reference value vg_ref of the grid voltage is compared with the carrier wave by PWM to obtain the drive signals of the first switch S1, the fourth switch S4, the fifth switch S5, the sixth switch S6 and the seventh switch S7 in the non-isolated H5-D inverter circuit.

[0048] In this embodiment, the transfer function G of the PR controller PR (s) is

[0049]

[0050] Among them, K p K r w and w represent proportional gain, resonant gain coefficient, and resonant frequency, respectively; s represents a complex variable.

[0051] like Figure 3 As shown, the control method of the active power decoupling circuit is as follows:

[0052] The energy storage voltage of the battery in the active power decoupling circuit is controlled by sampling the actual energy storage voltage value vB. The actual energy storage voltage vB is processed by a low-pass filter LPF to obtain the average energy storage voltage VB. The difference between the average voltage VB and the energy storage voltage reference value VB* is used to obtain one of the reference values ​​IB_1* for the decoupling current via a PI controller. Next, the DC bus voltage is controlled. The actual value vdc of the DC bus voltage is processed by a band-pass filter BPF to obtain the actual component Δvdc of the second harmonic frequency. The difference between the actual component of the second harmonic frequency and the reference value Δvdc* of the second harmonic frequency component is used by the PI controller to obtain another reference value IB_2* for the decoupling current. One of the reference values ​​IB_1* and the other reference value IB_2* of the decoupling current are compared with the actual value iB of the decoupling current. Then, the comparison result is processed by the PR controller to obtain the modulation wave of the active power decoupling circuit. Finally, the modulation wave of the active power decoupling circuit and the carrier are compared by PWM to generate the drive signals of the second switch S2 and the third switch S3 in the active power decoupling circuit.

[0053] In this embodiment, the transfer function G of the PI controller PI (s) is

[0054]

[0055] Among them, K p K i These represent the proportional gain and integral gain coefficients, respectively.

Claims

1. A household photovoltaic and storage integrated device, characterized in that: Including photovoltaic input V dc , the photovoltaic input V dc A split capacitor is connected in parallel at both ends, and the split capacitor includes a first split capacitor C1 and a second split capacitor C2 connected in series with each other; The second split capacitor C2 is connected to the source of the first switch tube S1, and a first diode D1 is connected in series between the drain of the first switch tube S1 and the midpoint of the first split capacitor C1 and the second split capacitor C2; An active power decoupling circuit is connected in parallel between the drain of the first switch tube S1 and the positive electrode of the first split capacitor C1, and a non-isolated full-bridge inverter circuit is connected after the active power decoupling circuit. The output of the non-isolated full-bridge inverter circuit is connected to the AC side output through a filter circuit.

2. The household photovoltaic and storage integrated device according to claim 1, characterized in that: The active power decoupling circuit includes a second switch tube S2, a third switch tube S3, and a decoupling inductor L1, wherein the drain of the second switch tube S2 is connected to the positive electrode of the photovoltaic power source, the source of the second switch tube S2 is connected to the drain of the third switch tube S3, and the source of the third switch tube S3 is connected to the drain of the first switch tube S1; A decoupling inductor L1 and an energy storage battery VB are connected in series between the drain of the third switch tube S3 and the source of the third switch tube S3 , wherein the energy storage battery VB is used to absorb power fluctuations on the DC bus and to provide power supply as an energy storage element when photovoltaic input is insufficient.

3. The household photovoltaic and storage integrated device according to claim 1, characterized in that: The non-isolated full-bridge inverter circuit comprises a fourth switch tube S4, a fifth switch tube S5, a sixth switch tube S6, and a seventh switch tube S7. The drains of the fourth switch tube S4 and the sixth switch tube S6 are both connected to the photovoltaic input V dc The positive electrode, the source of the fourth switch tube S4 is connected to the drain of the fifth switch tube S5, the source of the sixth switch tube S6 is connected to the drain of the seventh switch tube S7, and the sources of the fifth switch tube S5 and the seventh switch tube S7 are both connected to the drain of the first switch tube S1.

4. The household photovoltaic and storage integrated device according to claim 3, characterized in that: The filter circuit includes a first filter inductor L2 and a second filter inductor L3. One end of the first filter inductor L2 is connected to the source of the fourth switch tube S4, and the other end is connected to the AC side output V g The positive electrode; One end of the second filter inductor L3 is connected to the drain of the seventh switch tube S7, and the other end is connected to the AC side output V g of the negative electrode.

5. The household photovoltaic and storage integrated device according to claim 1, characterized in that: The active power decoupling circuit and the non-isolated H5-D inverter circuit respectively adopt separate control methods.

6. The household photovoltaic and storage integrated device according to claim 5, characterized in that: The control method of the non-isolated H5-D inverter circuit is as follows: The grid voltage vg is sampled through a phase-locked loop to obtain a grid phase wt, and the grid phase wt is combined with a given grid current amplitude Ig to obtain a reference value Igsinwt of the grid current; the reference value Igsinwt of the grid current is compared with an actual value ig of the grid current, and the difference Δi between the reference value Igsinwt of the grid current and the actual value ig of the grid current is input into a PR controller to obtain a reference value vg_ref of the grid voltage; the reference value vg_ref of the grid voltage is compared with a carrier through PWM to obtain drive signals of the first switch tube S1, the fourth switch tube S4, the fifth switch tube S5, the sixth switch tube S6 and the seventh switch tube S7 in the non-isolated H5-D inverter circuit.

7. The household photovoltaic and storage integrated device according to claim 6, characterized in that: The transfer function G of the PR controller PR (s) Among them, K p , K r , w represent proportional gain, resonant gain coefficient and resonant frequency respectively; s represents a complex variable.

8. The household photovoltaic and storage integrated device according to claim 5, characterized in that: The control method of the active power decoupling circuit is as follows: The energy storage voltage of the battery in the active power decoupling circuit is controlled, the actual voltage value vB of the energy storage is sampled, and the actual voltage value vB of the energy storage is processed by a low-pass filter LPF to obtain the average voltage VB of the energy storage; The average voltage VB is subtracted from the energy storage voltage reference value VB*, and the difference between the average voltage VB and the energy storage voltage reference value VB* is passed through a PI controller to obtain one of the reference values ​​of the decoupling current IB_1*; Control the DC bus voltage, the actual value vdc of the DC bus voltage is processed by the bandpass filter BPF to obtain the actual component Δvdc of twice the fundamental frequency, the actual component of twice the fundamental frequency is subtracted from the reference value Δvdc* of the twice the fundamental frequency component, and the difference between the actual component of twice the fundamental frequency and the reference value Δvdc* of the twice the fundamental frequency component is obtained by the PI controller to obtain another reference value IB_2* of the decoupling current; One of the reference values ​​IB_1* and another reference value IB_2* of the decoupling current is compared with the actual value iB of the decoupling current, and the comparison result is processed by the PR controller to obtain the modulation wave of the active power decoupling circuit; The modulation wave and the carrier wave of the active power decoupling circuit are compared by PWM to generate driving signals for the second switch tube S2 and the third switch tube S3 in the active power decoupling circuit.

9. The household photovoltaic and storage integrated device according to claim 8, characterized in that: The transfer function of the PI controller G PI (s) Among them, K p , K o They represent proportional gain and integral gain coefficients respectively; s represents a complex variable.

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