DC-AC inverter modules and micro inverters

Abstract

The embodiment of the present application provides a DC-AC inverter module and a micro-inverter, wherein the DC-AC inverter module includes: a bridge rectifier circuit, including a first rectifier path and a second rectifier path connected between an AC interface and a DC interface, the first rectifier path and the second rectifier path having opposite conduction directions; a first switch tube, used to control the on and off of the first rectifier path; a second switch tube, used to control the on and off of the second rectifier path; wherein the switch states of the first switch tube and the second switch tube are different, and the drive signals of the first switch tube and the second switch tube are determined according to the phase of the mains grid voltage. Thus, it supports switching different rectifier bridge paths from the AC interface to the DC interface through the switch tube, realizes modulation of the mains grid voltage from the AC side to the DC side, and can adjust the power factor of the micro-inverter to meet the requirements of the new grid connection standard.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to a DC-AC inverter module and a micro inverter. Background Art

[0002] Micro inverters are inverter devices that are directly connected to photovoltaic modules and can perform independent MPPT control (Maximum Power Point Tracking) on ​​each photovoltaic module. Compared with string photovoltaic inverters, micro inverters have the advantages of small size, high efficiency, and avoidance of DC high voltage.

[0003] As some countries and regions have successively put forward new grid-connected requirements for photovoltaic inverters, the photovoltaic inverters connected to them are required to have the ability to adjust their power factor according to the grid conditions. This requires micro-inverters to be able to achieve bidirectional energy flow. However, the DC-AC inverter circuit in the current micro-inverter cannot support voltage modulation from the AC side to the DC side.

[0004] In response to the above problems, the industry has not yet proposed a better technical solution. Summary of the invention

[0005] The present application provides a DC-AC inverter module and a micro inverter to at least solve the problem in the prior art that the DC-AC inverter circuit in the micro inverter cannot support voltage modulation from the AC side to the DC side.

[0006] In a first aspect, an embodiment of the present application provides a DC-AC inverter module, comprising an AC interface and a DC interface, wherein the DC interface is used to connect to the output end of the DC-DC conversion module, and the AC interface is used to connect to a mains power grid; wherein the DC-AC inverter module also includes: a bridge rectifier circuit, comprising a first rectifier path and a second rectifier path connected between the AC interface and the DC interface, the first rectifier path and the second rectifier path having opposite conduction directions; a first switch tube, used to control the on and off of the first rectifier path; a second switch tube, used to control the on and off of the second rectifier path; wherein the switching states of the first switch tube and the second switch tube are different, and the drive signals of the first switch tube and the second switch tube are determined according to the phase of the mains power grid voltage.

[0007] In a second aspect, an embodiment of the present application provides a micro inverter, comprising: at least one DC-DC conversion module; a DC-AC inverter module as described in any of the above items; wherein the output end of each of the DC-DC conversion modules is connected to the DC interface in the DC-AC inverter module.

[0008] In a third aspect, an embodiment of the present application provides a micro-inverter control method, including: detecting whether a voltage deviation value between a mains grid voltage and a rated mains grid voltage exceeds a preset voltage deviation threshold; when the voltage deviation threshold is not exceeded, outputting a first switch tube drive signal set to the DC-AC inverter module to enable power to be supplied from the DC interface to the AC interface; when the voltage deviation threshold is exceeded, outputting a second switch tube drive signal set to the DC-AC inverter module to enable power to be supplied from the AC interface to the DC interface.

[0009] In a fourth aspect, an electronic device is provided, comprising: at least one processor, and a memory communicatively connected to the at least one processor, wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can perform the steps of the micro-inverter control method of any embodiment of the present application.

[0010] In a fifth aspect, an embodiment of the present application provides a storage medium having a computer program stored thereon, characterized in that when the program is executed by a processor, the steps of the micro-inverter control method of any embodiment of the present application are implemented.

[0011] The beneficial effects of the embodiments of the present application are:

[0012] By setting a bridge rectifier circuit and two switch tubes in the DC-AC inverter module, the bridge rectifier circuit has two rectifier paths with opposite conduction directions between the AC interface and the DC interface, which are respectively controlled by the corresponding switch tubes according to the phase of the mains grid voltage. Therefore, it supports driving the switch tube according to the phase of the mains grid, switching different rectifier bridge paths from the AC interface to the DC interface, and realizing the modulation of the mains grid voltage from the AC side to the DC side, which is conducive to the micro-inverter to realize the two-way flow of energy between the inverter and the grid, realize the adjustable power factor function of the micro-inverter, and meet the requirements of the new grid-connected standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0014] Figure 1 A schematic diagram showing a structure of an example of a DC-AC inverter module according to an embodiment of the present application is shown.

[0015] Figure 2A schematic diagram of a circuit connection structure of an example of a DC-AC inverter module according to an embodiment of the present application is shown;

[0016] Figure 3 A structural block diagram of an example of a micro inverter according to an embodiment of the present application is shown;

[0017] Figure 4 A circuit connection diagram of an example of a micro inverter according to an embodiment of the present application is shown;

[0018] Figure 5 A flowchart showing an example of a micro-inverter control method applied to a controller according to an embodiment of the present application is shown;

[0019] Figure 6 A structural block diagram of an example of a micro-inverter control device according to an embodiment of the present application is shown;

[0020] Figure 7 It is a structural schematic diagram of the electronic device provided by this application. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0022] Figure 1 A schematic structural diagram of an example of a DC-AC inverter module according to an embodiment of the present application is shown.

[0023] like Figure 1 As shown, the DC-AC inverter module 100 includes an AC interface and a DC interface, the DC interface is used to connect to the output end of the DC-DC conversion module (not shown), the AC interface is used to connect to the mains power grid, and the AC interface is used to connect to the mains power grid. It should be understood that the micro inverter includes a cascaded DC-DC conversion module and a DC-AC inverter module, and the MPPT control and DC boost processing for the photovoltaic module are realized through the DC-DC conversion module, and the DC voltage is converted into an AC voltage that meets the mains grid requirements through the DC-AC inverter module.

[0024] Specifically, the DC-AC inverter module 100 also includes a switch tube Q1, a switch tube Q2 and a rectifier bridge circuit 110. The rectifier bridge circuit includes a first rectifier path 111 and a second rectifier path 113 connected between the AC interface and the DC interface, and the conduction directions of the first rectifier path 111 and the second rectifier path 113 are opposite. Q1 is used to control the on and off of the first rectifier path 111, and Q2 is used to control the on and off of the second rectifier path. The switching states of Q1 and Q2 are different. Exemplarily, Q1 is turned on and Q2 is turned off, at which time the first rectifier path 111 is turned on and the second rectifier path 113 is turned off; Q1 is turned off and Q2 is turned on, at which time the first rectifier path 111 is turned off and the second rectifier path 113 is turned on.

[0025] More specifically, the driving signals of Q1 and Q2 are determined according to the phase of the mains grid voltage. For example, the driving cycle for Q1 and Q2 is determined according to the phase cycle of the mains grid voltage, the on-off timing for Q1 and Q2 is determined according to the positive and negative conditions of the phase, and the emergency response control for Q1 and Q2 is determined according to the sudden fluctuation of the mains grid, etc. Therefore, the switch tube is driven according to the phase of the mains grid, and different rectifier bridge paths from the AC interface to the DC interface are switched, realizing the rectification modulation process matching the mains grid voltage, modulating the mains grid voltage from the AC side to the DC side, which is conducive to the micro inverter to realize the two-way flow of energy between the inverter and the grid.

[0026] Figure 2 A schematic diagram of a circuit connection structure of an example of a DC-AC inverter module according to an embodiment of the present application is shown.

[0027] Specifically, the bridge rectifier circuit includes a first diode D1, a second diode D2, a third diode D3 and a fourth diode D4. The positive electrodes of D1 and D2 form a series branch with the output ends of Q1 and Q2 respectively, and the two series branches are connected in parallel with the DC interface. Diodes D3 and D4 are connected in parallel with the switch tubes Q1 and Q2 respectively, and the positive and negative electrodes of D3 and D4 are connected to the DC interface and the AC interface respectively. In addition, the two ends of the AC interface are also connected to the output ends of the two switch tubes respectively.

[0028] In some embodiments, the more specific structural connections of the diodes and diodes in the DC-AC module are as follows: the positive electrode of D1 is connected to the output end of Q1, the negative electrode of D1 is connected to the first end of the DC interface, and the input end of Q1 is connected to the second end of the DC interface. The positive electrode of D2 is connected to the output end of Q2, the negative electrode of D2 is connected to the first end of the DC interface, and the input end of Q2 is connected to the second end of the DC interface. D3 is connected in parallel with Q1, the positive electrode of D3 is connected to the input end of D1, the negative electrode of D3 is connected to the first end of the AC interface, and the output end of Q1 is also connected to the first end of the AC interface. D4 is connected in parallel with Q2, the positive electrode of D4 is connected to the input end of Q2, the negative electrode of D4 is connected to the second end of the AC interface, and the output end of Q2 is also connected to the second end of the AC interface.

[0029] In addition, the DC-AC inverter module further includes a first inductor L1 and a second inductor L2. Specifically, L1 is connected between the output end (i.e., source) of Q1 and the negative electrode of D3, and L2 is connected between the output end (i.e., source) of Q2 and the negative electrode of D4, thereby supporting rectification and inversion conversion between direct current signals and alternating current signals by arranging the inertial device inductors L1 and L2 in the DC-AC inverter module.

[0030] It should be understood that the two ends of the DC interface are respectively a positive pole and a negative pole, and accordingly the first end of the DC interface can represent a positive pole or a negative pole, which should not be limited here. In some embodiments, the DC interface can exist in the form of a bus capacitor, for example, the DC-DC conversion module and the DC-AC module are bridged by the bus capacitor. In addition, the two ends of the AC interface are respectively a first AC power supply end and a second AC power supply end for connecting to the mains power grid.

[0031] Through the embodiments of the present application, based on the switch tubes Q1 and Q2, the switching of the rectifier bridge path from the AC interface to the DC interface composed of D1, D2, D3 and D4 is realized, so that the DC-AC inverter module supports voltage modulation from the AC side to the DC side, which is beneficial for the micro inverter to realize the bidirectional flow function of energy between the inverter and the power grid, and realize the power factor adjustable function of the micro inverter.

[0032] In some examples of the embodiments of the present application, Q1 and Q2 are driven according to the phase of the mains grid voltage connected to the AC interface. For example, when the phase is the positive half-cycle phase of the voltage, Q1 is controlled to be turned on and Q2 is controlled to be turned off, and when the phase is the negative half-cycle phase of the voltage, Q2 is controlled to be turned on and Q1 is controlled to be turned off.

[0033] Specifically, when Q1 is turned on and Q2 is turned off, the first direct-alternating conduction loop is formed by the AC interface, D1, the DC interface, Q1, L1, and D4, so that a positive half-cycle AC voltage can be output from the AC interface to the DC interface. When Q1 is turned off and Q2 is turned on, the second direct-alternating conduction loop is formed by the DC interface, Q2, L2, D2, D3, and the AC interface, so that a negative half-cycle AC voltage can be output from the AC interface to the DC interface. Thus, by controlling the on-off operation of Q1 and Q2, switching in different rectification loops is achieved, the rectification requirements of the AC power corresponding to the positive half-cycle phase and the negative half-cycle phase of the AC power grid are met, and sinusoidal rectification modulation of the AC power grid voltage signal is supported.

[0034] It should be noted that the types of switch tubes can be various, such as N-channel MOS transistors, P-channel MOS transistors, IGBTs, MOSFET switch tubes, etc. In addition, those skilled in the art can also modify the switch tubes according to their needs. Figure 1 Optimize the examples in the example, such as adding new components to achieve richer functions, and all of these fall within the scope of implementation of the embodiments of the present application. Figure 1 The example in the figure can realize the goal of rectifying and supplying power from the AC side to the DC side in the DC-AC inverter module. In addition, the DC-AC inverter module can also be provided with any suitable inverter circuit not described herein to support the bidirectional flow of energy between the AC side and the DC side of the DC-AC inverter module.

[0035] like Figure 2 As shown, the DC-AC inverter module also includes a third switch tube Q3 and a fourth switch tube Q4, wherein the switch tube is selected as an N-channel MOS tube. In some examples of the embodiments of the present application, the input end (i.e., the drain) of Q3 is connected to the negative electrode of D3, the output end of Q3 is connected to the first end of the DC interface, the input end (i.e., the drain) of Q4 is connected to the negative electrode of D4, and the output end of Q4 is connected to the first end of the DC interface. By performing switch tube on-off operations on the switch tube groups Q1, Q2, Q3 and Q4, power can be supplied from the DC interface to the AC interface.

[0036] Specifically, the switch tube group is driven according to the phase of the mains grid voltage. When the mains grid voltage is in the positive half-cycle phase, Q2 and Q3 are turned on, and Q1 and Q4 are turned off. At this time, Q2, L2, AC interface, D2, Q3 and DC interface form a first AC-DC conduction loop, so that the AC interface can receive the positive half-cycle AC voltage after inversion from the DC interface. When the mains grid voltage is in the negative half-cycle phase, Q1 and Q4 are turned on, and Q2 and Q3 are turned off. At this time, Q4, L1, AC interface, Q1, D2 and DC interface form a second AC-DC conduction loop, so that the AC interface can receive the negative half-cycle AC voltage after inversion from the DC interface. Thus, by controlling the on-off operation of the switch group Q1, Q2, Q3 and Q4, switching in different inversion loops is realized, and the inversion corresponding to the positive half-cycle phase and the negative half-cycle phase of the mains voltage is realized through inductance modulation, so as to realize the AC output of the inversion corresponding to the positive half-cycle phase and the negative half-cycle phase, and support the sinusoidal inversion modulation of the current.

[0037] It should be noted that, on the other hand, when it is required to supply power from the AC interface to the DC interface, the switch tubes Q3 and Q4 are turned off, and then the on-off control of Q1 and Q2 is used to enable power supply from the AC interface to the DC interface. For the details of the on-off control of Q1 and Q2, please refer to the relevant descriptions of other parts above, which will not be repeated here. Therefore, by controlling the on-off of each switch tube in the switch tube group, the bidirectional flow of energy in the DC-AC module is realized, and the voltage signal can be bidirectionally sinusoidally modulated.

[0038] In some examples of the embodiments of the present application, the control end of the switch tube in the switch tube group can be connected to a PWM (Pulse Width Modulation) signal source, and the on and off of each switch tube is modulated by PWM pulses to achieve an accurate sinusoidal modulation process. Thus, based on the digital encoding of the phase analog signal of the mains power grid, the voltage inversion and rectification encoding matching the mains power grid is achieved.

[0039] It should be understood that the above PWM signal source is only used for example and cannot be regarded as limiting the present application. In addition, the types of driving signal sources connected to the control terminals of each switch tube in the switch tube group can be diverse, such as SPWM (sinusoidal PWM, sinusoidal pulse width modulation) signal source, SVPWM (Space Vector PWM) signal source, pulse frequency modulation (pulse frequency modulation, PFM) signal source, SPFM (sinusoidal PFM, sinusoidal pulse frequency modulation) signal source, etc.

[0040] Figure 3 A structural block diagram of an example of a micro inverter according to an embodiment of the present application is shown.

[0041] like Figure 3 As shown, the micro inverter 400 includes at least one DC-DC conversion module (411, 413...41n) and a DC-AC inverter module 420. The output end of each DC-DC conversion module is connected to the DC interface 421 in the DC-AC inverter module 420. Each DC / DC conversion module tracks the MPPT and boosts the output DC voltage to the DC interface 421. The DC / AC inverter module 420 obtains energy from the DC interface 421 and is connected to the mains power grid through the AC interface 423 to achieve maximum energy-based grid-connected output.

[0042] Figure 4 A circuit connection diagram of an example of a micro inverter according to an embodiment of the present application is shown.

[0043] like Figure 4 As shown, the micro inverter 500 also includes a controller, which is connected to the control end of each switch tube in the DC-AC inverter module. Then, the controller detects the AC voltage signal feedback of the mains grid, and outputs a switch tube drive signal to control the conduction or cutoff of each switch tube. Through the modulation of the switch tube drive signal, energy flows from the AC interface to the DC interface in the DC-AC module, and energy flows in both directions between the AC side and the DC side of the DC-AC module, and different switch tube on-off operations can be performed according to the positive half-cycle phase or the negative half-cycle phase of the mains grid voltage signal, so as to achieve bidirectional sinusoidal modulation matching the mains grid voltage signal. For the details on the regulation of the switch tube, please refer to the above text in part. Figure 1-3 The description of the embodiments in the above will not be repeated here.

[0044] like Figure 4 As shown, the micro inverter includes multiple DC-DC conversion modules and DC-AC inverter modules, and the energy is input into the bus (bus voltage Vbus) through multiple DC-DC conversion modules to increase the power capacity of the micro inverter, and then the DC-AC inverter is used to achieve grid connection. In addition, the DC-DC conversion module is connected to the photovoltaic module, and each photovoltaic panel in the photovoltaic module can be connected in parallel or in series.

[0045] The DC-DC conversion module includes a transformer T1. A capacitor C1 and a switch tube Q5 are arranged on one side of the primary coil of the transformer T1. C1 is connected in parallel with the photovoltaic module, and Q5 is connected in series between C1 and the primary coil. A diode D5, a diode D6, a capacitor C2, a capacitor C3 and a capacitor C4 are arranged on one side of the secondary coil of the transformer T1. C2 is connected in series to the negative electrode of D5 to form a first branch, and C3 is connected in series to the positive electrode of D6 to form a second branch. The positive electrode of D5 in the first branch and the negative electrode of D6 in the second branch are connected to the first end of the secondary coil, and C2 in the first branch and C3 in the second branch are connected to the second end of the secondary coil. C2 and C3 form a series branch, and this series branch is connected in parallel with the energy storage capacitor C4.

[0046] Specifically, when Q5 is turned on, capacitors C3, D6 and the secondary secondary coil form a conduction loop, which realizes charging of capacitors C3 and C4; when Q5 is turned off, capacitors D5, C2 and the secondary secondary coil form a conduction loop, which realizes charging of capacitors C2 and C4. Therefore, whether Q5 is turned on or off, energy can be transferred from the primary side of the transformer to the secondary side. Compared with the general flyback circuit that can only transmit energy when the switch tube is turned off, or the forward circuit that only transmits energy when the switch tube is turned on, the forward flyback circuit provided in the embodiment of the present application greatly improves the utilization rate of the transformer T1, and at the same time increases the capacity of the DC-DC conversion module and the satellite inverter.

[0047] In some examples of the embodiments of the present application, the control signal of the switch tube in each DC-DC conversion module is driven by a controller, for example, the switch tube driving signal is used to realize the conduction or shutdown of the switch tube (for example, Q5, Q6, etc.) in the DC-DC conversion module. Specifically, the controller can implement the on-off control of the switch tube in the DC-DC conversion module according to the bus voltage, for example, compare the difference voltage Skip between the bus voltage Vbus and the bus reference voltage Vbusref, and determine the voltage size that needs to be adjusted in the DC / DC conversion circuit of different channels based on Skip, thereby controlling the bus voltage so that the voltage of the bus capacitor reaches the balance between energy injection and output. Thus, the bus voltage fluctuation caused by changes in the external environment is reduced. For example, with the change of weather, the light intensity of some photovoltaic modules increases greatly, and some photovoltaic modules are affected by the environment and enter the shadow, and the light intensity amplitude is reduced.

[0048] Figure 5 A flowchart of an example of a micro-inverter control method applied to a controller according to an embodiment of the present application is shown.

[0049] like Figure 5 As shown, in step S610, it is detected whether the voltage deviation value between the mains grid voltage and the rated mains grid voltage exceeds a preset voltage deviation threshold.

[0050] In some implementations, a voltage detection circuit connected in parallel to the mains interface is provided in the micro inverter, and the grid voltage signal can be collected and monitored in an isolated or non-isolated manner.

[0051] Here, the voltage deviation value may indicate the degree or voltage difference of the mains voltage being greater than or less than the rated mains voltage, and the voltage deviation threshold may be pre-calibrated according to the demand, such as the local inverter access standard. In addition, the rated mains voltage may be different in different countries or regions, for example, the rated mains voltage of Chinese civil electricity is 220V.

[0052] In step S621, when the voltage deviation threshold is not exceeded, a first switch tube driving signal set is output to the DC-AC inverter module to enable power to be supplied from the DC interface of the DC-AC inverter module to the AC interface of the DC-AC inverter module.

[0053] Combination Figure 1 In the example, the first switch tube drive signal set includes a Q1 turn-on pulse and a Q2 turn-off pulse corresponding to the positive half cycle of the mains voltage, and a Q1 turn-off pulse and a Q2 turn-on pulse corresponding to the negative half cycle of the mains voltage, enabling power supply from the DC interface to the AC interface. Figure 2 In the example, the first switch tube drive signal set includes Q1 turn-on pulse, Q2 turn-off pulse, Q3 turn-off pulse and Q4 turn-off pulse corresponding to the positive half cycle of the mains grid voltage, and Q1 turn-off pulse, Q2 turn-on pulse, Q3 turn-off pulse and Q4 turn-off pulse corresponding to the negative half cycle of the mains grid voltage, thereby enabling power supply from the DC interface to the AC interface.

[0054] In some embodiments, when the voltage deviation threshold is not exceeded, it indicates that the mains voltage is relatively stable, the micro-inverter can implement a normal inverter function, and control the output current of the inverter to have the same phase as the output voltage or the mains voltage, so that all energy is output from the DC end to the AC end, thereby maximizing the inverter power factor.

[0055] In step S623, when the voltage deviation threshold is exceeded, a second switch tube driving signal set is output to the DC-AC inverter module to enable power to be supplied from the AC interface to the DC interface.

[0056] Specifically, once it is detected that the voltage deviation value exceeds the voltage deviation threshold, it is determined that the energy flow direction of the micro inverter needs to be adjusted, that is, the energy is controlled to flow from the AC side of the micro inverter to the DC side. In some embodiments, the voltage detection circuit in the micro inverter is also provided with a filtering module to reduce noise and interference in the measurement signal.

[0057] Combination Figure 2In the example, the second switch tube drive signal set includes Q1 turn-off pulse, Q4 turn-off pulse, Q2 turn-on pulse and Q3 turn-on pulse corresponding to the positive half cycle of the mains grid voltage, and Q1 turn-on pulse, Q4 turn-on pulse, Q2 turn-off pulse and Q3 turn-off pulse corresponding to the negative half cycle of the mains grid voltage, thereby enabling power supply from the AC interface to the DC interface.

[0058] It should be understood that the pulse type and number of the switch tube drive signal set can be more diverse and can be adjusted as the circuit structure in the DC-AC inverter module changes. Figure 1 When other suitable DC-AC circuits are added on this basis, the pulse modulation mode of PWM can be adjusted accordingly according to the inversion requirements.

[0059] In some examples of the embodiments of the present application, when the voltage deviation threshold is exceeded, the second switch tube drive signal set is determined according to the phase of the mains grid voltage, and the second switch tube drive signal set is output to the DC-AC inverter module. Here, the second switch tube drive signal set is used to modulate the phase of the output current of the AC interface to lead or lag behind the phase of the mains grid voltage. In this way, for a period of time in each AC cycle, the phase direction of the output current of the micro-inverter is opposite to that of the mains grid voltage. At this time, energy will flow from the AC interface to the DC interface, so that the energy of the micro-inverter can flow in both directions, so that the inverter can adjust its output power factor in time according to the grid conditions, and meet the new grid connection standards of some countries and regions.

[0060] Furthermore, when the voltage deviation threshold is exceeded, the controller can also send a stop power generation instruction to each DC-DC conversion module, so that each DC-DC conversion module stops supplying power to the bus based on the stop power generation instruction. Thus, when the grid energy return of the inverter is controlled in a weak grid, the DC-DC conversion module stops transmitting energy to the bus, which can effectively avoid the DC-DC conversion module and the DC-AC module charging the bus together, resulting in an excessively high bus voltage (i.e., Vbus).

[0061] More preferably, the bus voltage is monitored to see if it exceeds a preset bus voltage safety threshold, and when it does, the controller issues a whole machine shutdown command to shut down the DC-DC conversion module and the DC-AC module, thereby protecting the equipment safety of the micro inverter.

[0062] In some embodiments, when the mains grid voltage is lower than the rated mains grid voltage, the second switch tube drive signal set is used to modulate the phase of the output current of the AC interface to a phase that is ahead of the mains grid voltage. And, when the mains grid voltage is higher than the rated mains grid voltage, the second switch tube drive signal set is used to modulate the phase of the output current of the AC interface to a phase that lags behind the mains grid voltage. Thus, under weak grid conditions, the overvoltage state or undervoltage state of the mains grid voltage is considered, and pulse modulation is performed in combination with the voltage phase of the mains grid to achieve forward or reverse voltage compensation, thereby ensuring the stability of the reverse power supply voltage to the DC interface.

[0063] More specifically, a second switch tube drive signal set matching the voltage deviation threshold is determined according to a preset voltage phase reference relationship, and the voltage phase reference relationship defines the association between the voltage deviation threshold and the modulation phase. Further, the controller monitors the voltage deviation value in real time, and queries the corresponding voltage phase reference relationship according to the voltage deviation value, calculates the second switch tube drive signal set for leading or lagging the phase of the output current of the AC interface, and realizes fast phase modulation.

[0064] Figure 6 A structural block diagram of an example of a micro-inverter control device according to an embodiment of the present application is shown. The device can execute the micro-inverter control method described in any of the above embodiments and is configured in a terminal.

[0065] A micro-inverter control device 700 provided in this embodiment includes:

[0066] The voltage detection unit 710 is used to detect whether a voltage deviation value between the mains grid voltage and the rated mains grid voltage exceeds a preset voltage deviation threshold.

[0067] The drive signal output unit 720 is used to output a first switch tube drive signal set to the DC-AC inverter module when the voltage deviation threshold is not exceeded, so as to enable power to be supplied from the DC interface of the DC-AC inverter module to the AC interface of the DC-AC inverter module; and when the voltage deviation threshold is exceeded, output a second switch tube drive signal set to the DC-AC inverter module, so as to enable power to be supplied from the AC interface to the DC interface.

[0068] Furthermore, the switch tube drive signal output unit 720 is used to determine the second switch tube drive signal set according to the phase of the mains grid voltage when the voltage deviation threshold is exceeded, and output the second switch tube drive signal set to the DC-AC inverter module; wherein the second switch tube drive signal set is used to modulate the phase of the output current of the AC interface to lead or lag behind the phase of the mains grid voltage, so that energy flows from the AC interface to the DC interface.

[0069] Furthermore, the switch tube drive signal output unit 720 is used to send a power generation suspension instruction to each of the DC-DC conversion modules when the voltage deviation threshold is exceeded, so that each of the DC-DC conversion modules stops supplying power to the bus based on the power generation suspension instruction.

[0070] In some embodiments, when the mains grid voltage is lower than the rated mains grid voltage, the second switch tube drive signal set is used to modulate the phase of the output current of the AC interface to be ahead of the phase of the mains grid voltage; and, when the mains grid voltage is higher than the rated mains grid voltage, the second switch tube drive signal set is used to modulate the phase of the output current of the AC interface to be behind the phase of the mains grid voltage.

[0071] Figure 7 is a schematic diagram of the hardware structure of an electronic device provided in an embodiment of the present application, such as Figure 7 As shown, the device includes:

[0072] One or more processors 810 and memory 820, Figure 7 A processor 810 is taken as an example. The device of the micro inverter control method may further include: an input device 830 and an output device 840.

[0073] The processor 810, the memory 820, the input device 830 and the output device 840 may be connected via a bus or other means. Figure 7 The example of connecting through bus is taken in the following.

[0074] The memory 820, as a non-volatile computer-readable storage medium, can be used to store non-volatile software programs, non-volatile computer executable programs and modules, such as program instructions / modules corresponding to the micro-inverter control method in the embodiment of the present application. The processor 810 executes various functional applications and data processing of the server by running the non-volatile software programs, instructions and modules stored in the memory 820, that is, the micro-inverter control method of the above method embodiment is implemented.

[0075] The memory 820 may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function; the data storage area may store data, etc. In addition, the memory 820 may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other non-volatile solid-state storage device. In some embodiments, the memory 820 may optionally include a memory remotely arranged relative to the processor 810, and these remote memories may be connected to the mobile device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0076] The input device 830 can receive input digital or character information. The output device 840 can include a display device such as a display screen.

[0077] The one or more modules are stored in the memory 820, and when executed by the one or more processors 810, the micro-inverter control method in any of the above method embodiments is executed.

[0078] The above-mentioned product can execute the method provided in the embodiment of the present application, and has the functional modules and beneficial effects corresponding to the execution method. For technical details not fully described in this embodiment, please refer to the method provided in the embodiment of the present application.

[0079] The non-volatile computer-readable storage medium may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function; the data storage area may store data created according to the use of the device, etc. In addition, the non-volatile computer-readable storage medium may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other non-volatile solid-state storage device. In some embodiments, the non-volatile computer-readable storage medium may optionally include a memory remotely arranged relative to the processor, and these remote memories may be connected to the device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0080] An embodiment of the present application also provides an electronic device, comprising: at least one processor, and a memory communicatively connected to the at least one processor, wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can perform the steps of the micro-inverter control method of any embodiment of the present application.

[0081] The electronic device of the embodiment of the present application exists in various forms, including but not limited to:

[0082] (1) Mobile communication equipment: This type of equipment is characterized by having mobile communication functions and its main purpose is to provide voice and data communications. This type of terminal includes: smart phones, multimedia phones, functional phones, and low-end phones.

[0083] (2) Ultra-mobile personal computer devices: These devices fall into the category of personal computers, have computing and processing capabilities, and generally also have mobile Internet access features. These terminals include: PDAs, MIDs, and UMPC devices, such as tablet computers.

[0084] (3) Portable entertainment devices: These devices can display and play multimedia content. They include audio and video players, handheld game consoles, e-books, smart toys, and portable car navigation devices.

[0085] (4) Other electronic devices with data processing functions.

[0086] In this article, relational terms such as first and second, etc. are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include" and "comprise" include not only those elements, but also other elements not explicitly listed, or also include elements inherent to such processes, methods, articles or equipment. In the absence of further restrictions, the elements defined by the statement "include..." do not exclude the existence of other identical elements in the process, method, article or equipment that includes the elements.

[0087] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0088] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A micro inverter, comprising: At least one DC-DC conversion module; DC-AC inverter module; wherein the output end of each of the DC-DC conversion modules is connected to the DC interface in the DC-AC inverter module; The DC-AC inverter module includes an AC interface and a DC interface, wherein the DC interface is used to connect to the output end of the DC-DC conversion module, and the AC interface is used to connect to the mains power grid; the DC-AC inverter module also includes: A bridge rectifier circuit, comprising a first rectifier path and a second rectifier path connected between the AC interface and the DC interface, wherein the first rectifier path and the second rectifier path have opposite conduction directions; A first switch tube, used for controlling the on and off of the first rectifier path; A second switch tube, used for controlling the on and off of the second rectifier path; A third switch tube, an input end of which is connected to the cathode of the third diode, and an output end of which is connected to the first end of the DC interface; a fourth switch tube, whose input end is connected to the cathode of the fourth diode, and whose output end is connected to the first end of the DC interface; The switch tube group is used to switch on and off the switch tubes to enable power to be supplied from the DC interface to the AC interface; the switch tube group includes the first switch tube, the second switch tube, the third switch tube and the fourth switch tube; The switch states of the first switch tube and the second switch tube are different from each other, and the driving signals of the first switch tube and the second switch tube are determined according to the phase of the mains power grid voltage; A controller connected to the control end of each switch tube in the DC-AC inverter module and used to output a switch tube drive signal to control each switch tube to be turned on or off; The controller is also used to perform the following operations: Detecting whether the voltage deviation value between the mains grid voltage and the rated mains grid voltage exceeds a preset voltage deviation threshold; When the voltage deviation threshold is not exceeded, a first switch tube driving signal set is output to the DC-AC inverter module to enable power to be supplied from the DC interface to the AC interface; When the voltage deviation threshold is exceeded, a second switch tube driving signal set is output to the DC-AC inverter module to enable power to be supplied from the AC interface to the DC interface; Among them, when the mains grid voltage is lower than the rated mains grid voltage, the second switch tube drive signal set is used to modulate the phase of the output current of the AC interface to be ahead of the phase of the mains grid voltage; and when the mains grid voltage is higher than the rated mains grid voltage, the second switch tube drive signal set is used to modulate the phase of the output current of the AC interface to be behind the phase of the mains grid voltage.

2. The micro inverter according to claim 1, wherein: When the voltage deviation threshold is exceeded, outputting a second switch tube drive signal set to the DC-AC inverter module includes: When the voltage deviation threshold is exceeded, the second switch tube drive signal set is determined according to the phase of the mains grid voltage, and the second switch tube drive signal set is output to the DC-AC inverter module; wherein the second switch tube drive signal set is used to modulate the phase of the output current of the AC interface to lead or lag behind the phase of the mains grid voltage, so that energy flows from the AC interface to the DC interface.

3. The micro inverter according to claim 1, wherein: The controller is also used to perform the following operations: When the voltage deviation threshold is exceeded, a power generation stop instruction is sent to each of the DC-DC conversion modules, so that each of the DC-DC conversion modules stops supplying power to the bus based on the power generation stop instruction.

4. The micro inverter according to claim 1, wherein: The controller includes a PWM signal source.

5. The micro inverter according to claim 1, wherein: The bridge rectifier circuit includes a first diode, a second diode, a third diode and a fourth diode; the DC-AC inverter module also includes a first inductor and a second inductor; A first branch consisting of the anode of the first diode connected in series to the output end of the first switch tube, and a second branch consisting of the anode of the second diode connected in series to the output end of the second switch tube, wherein the first branch and the second branch are connected in parallel to two ends of the DC interface; The third diode is connected in parallel with the first switch tube; the anode of the third diode is connected to the input end of the first switch tube, the cathode of the third diode is connected to the first end of the AC interface, and the output end of the first switch tube is also connected to the first end of the AC interface; The fourth diode is connected in parallel with the second switch tube; the anode of the fourth diode is connected to the input end of the second switch tube, the cathode of the fourth diode is connected to the second end of the AC interface, and the output end of the second switch tube is also connected to the second end of the AC interface; The first inductor is connected between the output end of the first switch tube and the cathode of the third diode, and the second inductor is connected between the output end of the second switch tube and the cathode of the fourth diode.

6. The micro inverter according to claim 5, wherein: When the mains voltage is in a positive half-cycle phase, the first switch is turned on and the second switch is turned off; and when the mains voltage is in a negative half-cycle phase, the first switch is turned off and the second switch is turned on.

7. The micro inverter according to claim 5, wherein: The switch tube group is driven according to the phase of the mains power grid voltage; When the mains grid voltage is in a positive half-cycle phase, the second switch tube and the third switch tube are turned on, and the first switch tube and the fourth switch tube are turned off; when the mains grid voltage is in a negative half-cycle phase, the first switch tube and the fourth switch tube are turned on, and the second switch tube and the third switch tube are turned off.

8. The micro inverter according to claim 5, wherein: The first switch tube, the second switch tube, the third switch tube and the fourth switch tube are N-channel MOS transistors.

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