A power prediction control system and method for a micro-inverter

Abstract

The application discloses a power prediction control system and method of a micro inverter, and the power prediction control system comprises a master control unit and a consumption load unit; the master control unit comprises a sampling module and a control DSP, and the consumption load unit comprises a load loop arranged at an output end of a transformer, wherein a load R2 and a switch Q are arranged on the load loop, and the switch Q is connected with the control DSP through an isolation driving module. In an initial state, a relay KA is disconnected, and the switch Q is turned on; when sampling and detecting, a change ratio threshold value is set first, the change ratio of the voltage and the current of a primary side circuit module in a rated time is detected, when the change ratio is greater than the change ratio threshold value, the switch Q is turned off, and the relay KA is closed; when the change ratio is less than the change ratio threshold value, the switch Q is turned on, and the relay KA is disconnected. The application can consume the output energy of the transformer in the disconnected state of the load consumption relay, improve the frequent switching condition of the traditional relay, and guarantee and prolong the effective service life of the system.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of micro inverter power prediction control system and method, belong to the technical field of micro inverter power prediction and relay control. BACKGROUND

[0002] Micro single-stage inverter topology, input voltage is safe voltage, system voltage is low, wide operating voltage range weak light whole system is prone to frequent restart, reconnection influence whole system life, especially the frequent switching of mechanical relay in system directly influence electrical and mechanical life.

[0003] Micro inverter generally includes with grid end connection auxiliary side inverter bridge, auxiliary side inverter bridge is connected with primary circuit module by a plurality of parallel transformers, primary circuit module is connected with PV end, and auxiliary side inverter bridge and EMC module of grid end are connected through relay KA, PV end is influenced by light and can exist certain instability, at this time, grid end supply can cause system instability, and relay KA can produce frequent switching. SUMMARY

[0004] The purpose of the present application is to solve the above-mentioned deficiencies of the prior art, and to solve the problem of frequent restart of the system and frequent switching of the relay caused by unstable light in the traditional micro inverter, a power prediction control system and method for micro inverter are proposed.

[0005] In order to achieve the above purpose, the technical scheme adopted by the present application is:

[0006] A power prediction control system for micro inverter, comprising a grid end with an EMC module, the EMC module is connected with auxiliary side inverter bridge through relay KA, the auxiliary side inverter bridge is connected with a plurality of transformers in parallel, any transformer is connected with PV end through primary circuit module, comprising main control unit for collecting primary circuit module data to judge working state and control relay KA, and consumption load unit for output end power consumption of a plurality of transformers;

[0007] The main control unit comprises a sampling module connected with any primary circuit module, a control DSP connected with the sampling module, and the control DSP is drivingly connected with the relay KA;

[0008] The consumption load unit comprises a first ground branch and a second ground branch, the first ground branch is connected with the first end of any transformer, and the second ground branch is connected with the second end of any transformer, the first ground branch or the second ground branch is provided with a load R2 and a switch Q in series, and the switch Q is connected with the control DSP through an isolation driving module.

[0009] Preferably, the main control unit comprises an auxiliary power supply, and the auxiliary power supply is connected with the sampling module, the control DSP and the isolation driving module for power supply, respectively.

[0010] Preferably, the auxiliary power supply is connected with a power supply PV terminal.

[0011] Preferably, the switch Q is a MOS switch tube.

[0012] The application further provides a control method of the power prediction control system of the micro inverter.

[0013] S1 initial state, relay KA is off, switch Q is on, and load R2 consumes the output energy of the transformer;

[0014] S2 sampling detection, a change ratio threshold is set, the sampling module detects the change ratio of the voltage and the current of the primary side circuit module in a rated time, and a pass signal is triggered when it is detected that the change ratio is greater than the change ratio threshold;

[0015] S3 relay pass driving, the control DSP receives the pass signal, closes the switch Q through the isolation driving module, and closes the relay KA;

[0016] S4 supply detection, the sampling module detects the change ratio of the voltage and the current of the primary side circuit module in a rated time, a trip signal is triggered when it is detected that the change ratio is less than the change ratio threshold, the control DSP receives the trip signal, opens the switch Q through the isolation driving module, and opens the relay KA.

[0017] The application has the following beneficial effects:

[0018] 1. The transformer output energy in the relay off state is consumed by the load, so that the sampling module can generate a reliable interval for the switching signal, the traditional relay switching is eliminated, and the effective service life of the system is guaranteed and prolonged.

[0019] 2. The system circuit is ingenious, easy to construct and implement.

[0020] 3. The power prediction and load energy consumption can be realized, and the system is particularly suitable for solving the frequent restart problem of the whole system under weak light, and the system operation reliability and stability are maintained. BRIEF DESCRIPTION OF DRAWINGS

[0021] Other characteristics, objects and advantages of the application will become more apparent after reading the following detailed description of non-restrictive embodiments made with reference to the accompanying drawings:

[0022] Figure 1 is a structural schematic diagram of the power prediction control system of the micro inverter.

[0023] Figure 2 This is a flowchart illustrating the control method of a power prediction control system for a micro-inverter according to the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described in the present application can be combined with each other.

[0026] This invention provides a power prediction control system for a micro inverter, such as... Figure 1 As shown, the system includes a grid terminal equipped with an EMC module. The EMC module is connected to a secondary inverter bridge via a relay KA. Several transformers are connected in parallel to the secondary inverter bridge, and any transformer is connected to a PV terminal via a primary circuit module. This system configuration is existing technology for microinverters and will not be elaborated upon here.

[0027] In this invention, such as Figure 1 As shown, it includes a main control unit for collecting data from the primary circuit module to determine its working status and for relay KA control, and a load unit for consuming electrical energy at the output of several transformers.

[0028] The main control unit includes a sampling module connected to any primary-side circuit module, a control DSP connected to the sampling module, and the control DSP is connected to the relay KA phase drive control.

[0029] The load consumption unit includes a first grounding branch and a second grounding branch. The first grounding branch is connected to the first end of any transformer, and the second grounding branch is connected to the second end of any transformer. The first grounding branch or the second grounding branch is equipped with a load R2 and a switch Q connected in series. The switch Q is connected to the control DSP through an isolation drive module.

[0030] Detailed implementation process and principle explanation:

[0031] First, let's explain the first and second terminals of the transformer. The first and second terminals are distinguished according to their positive and negative poles. That is, the first grounding branch is connected to the positive or negative pole of each transformer, and the second grounding branch is the same. The parallel connection method of the transformer output terminals is existing technology and will not be elaborated here.

[0032] In traditional systems, a sampling module is also used. The sampling module samples the primary circuit module and then controls the DSP to control the on / off state of the relay KA. However, the secondary side of the inverter bridge of the transformer is insufficient to maintain a stable output of the whole system. Therefore, after the relay KA is controlled to switch on and off, the sampling of the primary circuit module will fluctuate, resulting in frequent switching of the relay KA, which will affect the electrical and mechanical life.

[0033] In this case, the first grounding branch and the second grounding branch form an electrical loop. The load R2 on the electrical loop can realize the output energy consumption of the transformer, making the on-off control of the relay KA by the DSP after sampling by the sampling module more stable, eliminating the situation of frequent switching, and thus improving the effective service life.

[0034] To explain in more detail, before the relay KA is connected, the transformer's output energy is consumed. At this time, after the connection is controlled, it can maintain a relatively stable output. However, after the sampling module samples and the relay KA is disconnected, the transformer's output will be insufficient to maintain the stable output of the entire system. This affects the sampling data at the primary side, and it is easy to reach the control requirement of the connection again. However, due to the presence of the load R2, the energy consumption that is insufficient to maintain the stable output of the entire system can be achieved, so the condition of reconnection will not be frequently reached, thus reducing the frequency of the relay KA being connected and disconnected.

[0035] In addition, the isolation drive module can realize the isolation between the load circuit and the control DSP, meet the isolation control requirements, and realize the isolation drive of the control DSP to switch Q.

[0036] In one specific embodiment, the main control unit includes an auxiliary power supply, which is connected to the sampling module, the control DSP, and the isolation drive module for power supply. The auxiliary power supply is connected to a power supply PV terminal.

[0037] Specifically, this means that the auxiliary power supply powers all the electrical components. Simultaneously, the auxiliary power supply stores energy through the PV terminal.

[0038] In one specific embodiment, the switch Q is a MOS switch, which meets the requirements for isolation drive cooperation, and the MOS switch control of circuit opening and closing is safe, reliable and stable.

[0039] The control method of the power prediction control system for a microinverter according to the present invention is described, which includes the following steps:

[0040] In the initial state, relay KA is open, switch Q is open, and load R2 consumes the output energy of the transformer; that is, the load circuit where load R2 is located is in the open state, and the output energy of the transformer is continuously consumed.

[0041] Sampling and detection are performed, and a change ratio threshold is set. The sampling module detects the change ratio of the voltage and current of the primary circuit module in real time within a rated time. When the change ratio is detected to be greater than the change ratio threshold, a path signal is triggered. This change ratio is used as a condition to determine whether the system can operate stably. When the condition is met, the path signal is triggered.

[0042] The relay path driver controls the DSP to close switch Q and close relay KA after receiving the path signal through the isolation driver module. At this time, relay KA opens and provides stable output to the EMC module.

[0043] The supply detection and sampling module monitors the voltage and current changes of the primary circuit module in real time within a rated time. When the detected change ratio is less than the change ratio threshold, a circuit breaker signal is triggered. Upon receiving the circuit breaker signal, the DSP controls the isolation drive module to open switch Q, disconnecting relay KA. At this time, the transformer output is insufficient to maintain a stable output for the entire system, while the primary side continues to generate electrical energy. This affects the primary side's sampling data, causing the change ratio to fluctuate. However, due to the energy consumption of the load R2, the influence on the primary side's sampling data is eliminated, making the change ratio detection more reliable and stable, and preventing frequent on / off control of relay KA.

[0044] As described above, by utilizing the load to dissipate the transformer's output energy during the relay's open-circuit state, the sampling module can reliably determine the switching signal based on the sampled data, eliminating the frequent switching issues of traditional relays and ensuring and extending the system's effective lifespan. The system circuit is ingenious and easy to construct and implement. It enables power prediction and load energy consumption, and is particularly suitable for improving and resolving the problem of frequent system restarts in low-light conditions, maintaining system reliability and stability.

[0045] The term "comprising" or any other similar term is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus / device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent in such process, method, article, or apparatus / device.

[0046] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A power prediction and control system for a micro-inverter, comprising a grid terminal with an EMC module, the EMC module being connected to a secondary inverter bridge via a relay KA, the secondary inverter bridge being connected in parallel with several transformers, and any transformer being connected to a PV terminal via a primary circuit module, characterized in that: It includes a main control unit for collecting data from the primary circuit module to determine its working status and for relay KA control, and a load unit for consuming the output power of several transformers. The main control unit includes a sampling module connected to any of the primary-side circuit modules and a control DSP connected to the sampling module. The control DSP is connected to the relay KA for phase drive control. The load consumption unit includes a first grounding branch and a second grounding branch. The first grounding branch is connected to the first end of any of the transformers, and the second grounding branch is connected to the second end of any of the transformers. The first grounding branch or the second grounding branch is provided with a load R2 and a switch Q connected in series. The switch Q is connected to the control DSP through an isolation drive module.

2. The power prediction control system for a microinverter according to claim 1, characterized in that: The main control unit includes an auxiliary power supply, which is connected to the sampling module, the control DSP, and the isolation drive module for power supply.

3. The power prediction control system for a microinverter according to claim 2, characterized in that: The auxiliary power supply is connected to a power supply PV terminal.

4. The power prediction control system for a microinverter according to claim 1, characterized in that: The switch Q is a MOS switch.

5. A control method for a power prediction control system for a microinverter based on any one of claims 1 to 4, characterized in that... Includes the following steps: In the initial state of S1, relay KA is open, switch Q is open, and load R2 consumes the output energy of the transformer. S2 sampling detection: Set the change ratio threshold. The sampling module detects the change ratio of the voltage and current of the primary circuit module in real time within the rated time. When the detected change ratio is greater than the change ratio threshold, the path signal is triggered. S3 relay path driver: After the DSP receives the path signal, it closes the switch Q and closes the relay KA through the isolation drive module. S4 supply detection: The sampling module detects the ratio of voltage and current change of the primary circuit module in real time within a rated time. When the detected ratio is less than the ratio threshold, a circuit breaker signal is triggered. After receiving the circuit breaker signal, the DSP controls the switch Q to open the isolation drive module and disconnect the relay KA.

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