A split-phase inverter and a control method and control device thereof and an energy storage system

Abstract

The application discloses a split-phase inverter, a control method and a control device thereof, and an energy storage system. The split-phase inverter comprises a voltage dividing circuit, two inverter circuits and a control switch. The inverter circuits are electrically connected to the voltage dividing circuit. The first input end of a load is connected to the inverter output end of the first inverter circuit among the two inverter circuits. The second input end of the load is connected to the inverter output end of the second inverter circuit among the two inverter circuits. The middle end of the load is connected to the voltage dividing circuit. The control switch is connected between the first input end and the second input end of the load. The control method comprises the following steps: detecting the output signal of the split-phase inverter; and if the output signal of the split-phase inverter is a half-wave signal, controlling the control switch to be closed and entering a half-wave load working mode. In the half-wave load working mode, the control switch is closed, and the two inverter circuits of the split-phase inverter simultaneously provide the output signal for the load, so that the output stability of the split-phase inverter can be improved, and the stability of the energy storage system is further improved.

Description

Technical Field

[0001] This invention relates to the field of inverter technology, and in particular to a split-phase inverter, its control method and control device, and an energy storage system. Background Technology

[0002] With the rapid development of power electronics technologies such as new energy, inverters have also experienced rapid development and growth. Inverters can be applied to energy storage systems such as backup power systems, photovoltaic energy storage systems, outdoor power systems, microgrid systems, and industrial drives.

[0003] Inverters include split-phase inverters. Split-phase inverters can be adapted to 120V / 240V energy storage systems and are suitable for both low-voltage and high-voltage AC loads.

[0004] Currently, when a split-phase inverter drives a half-wave load, the dynamic conduction characteristics of the half-wave load can cause abnormal output of the split-phase inverter, affecting the stability of the energy storage system. Summary of the Invention

[0005] This invention provides a split-phase inverter, its control method and device, and an energy storage system to solve the problem of abnormal output when the existing split-phase inverter drives a half-wave load.

[0006] According to one aspect of the present invention, a control method for a split-phase inverter is provided, the split-phase inverter comprising: a voltage divider circuit, two inverter circuits, and a control switch; the inverter circuits are electrically connected to the voltage divider circuit, a first input terminal of the load is connected to the inverter output terminal of the first inverter circuit, a second input terminal of the load is connected to the inverter output terminal of the second inverter circuit, an intermediate terminal of the load is connected to the voltage divider circuit, and the control switch is connected between the first input terminal and the second input terminal of the load; The control method includes: Detect the output signal of the split-phase inverter; If the output signal of the split-phase inverter is a half-wave signal, then the control switch is controlled to close and merge into the half-wave load working mode.

[0007] Furthermore, detecting the output signal of the split-phase inverter includes: Acquire the current signal at the inverter output terminal of the inverter circuit; If the output current of the inverter circuit exists only in the positive or negative half-cycle of the power frequency cycle in N consecutive power frequency cycles, the output signal of the split-phase inverter is determined to be a half-wave signal, and N≥1.

[0008] Furthermore, detecting the output signal of the split-phase inverter includes: Acquire the current signal at the inverter output terminal of the inverter circuit; If the output current of the inverter circuit exists only in the positive or negative half-cycle of the power frequency cycle in N consecutive power frequency cycles, and the effective value error of the output current in different power frequency cycles is within a preset difference range, the output signal of the split-phase inverter is determined to be a half-wave signal, N≥1.

[0009] Furthermore, the inverter circuit includes a first bridge arm unit, a second bridge arm unit, and a filter unit. The first end of the first bridge arm unit is connected to the first end of the voltage divider circuit, the second end of the first bridge arm unit is connected to the second end of the voltage divider circuit, the middle end of the first bridge arm unit is connected to the middle end of the voltage divider circuit through the second bridge arm unit, and the middle end of the first bridge arm unit is connected to the inverter output terminal through the filter unit. The first bridge arm unit includes a first switch and a second switch connected in series, and the second bridge arm unit includes a third switch and a fourth switch connected in series. Entering half-wave load operating mode includes: During the first half of the power frequency cycle, the second switch of the first inverter circuit is turned off, and the second switch of the second inverter circuit is also turned off. The first inverter circuit is controlled to output a first output signal, and the second inverter circuit is controlled to output a second output signal, wherein the phase difference between the first output signal and the second output signal is 180°.

[0010] Furthermore, it enters a half-wave load operating mode, including: During the second half-cycle of the power frequency cycle, the first to fourth switches of the first inverter circuit are turned off, and the first to fourth switches of the second inverter circuit are also turned off.

[0011] Furthermore, the first half-cycle of the power frequency cycle is a positive half-cycle and the second half-cycle is a negative half-cycle.

[0012] Furthermore, the voltage divider circuit includes a voltage divider unit and a voltage regulator bridge arm unit connected in parallel. The voltage divider unit includes a first capacitor and a second capacitor connected in series, and the voltage regulator bridge arm unit includes a fifth switch and a sixth switch connected in series. Entering half-wave load operating mode includes: During the power frequency cycle, if the voltage difference between the first capacitor and the second capacitor exceeds a preset voltage difference range, the fifth and sixth switches in the voltage regulator bridge unit are controlled to open in a time-sharing manner.

[0013] According to another aspect of the present invention, a control device for a split-phase inverter is provided, the split-phase inverter comprising: a voltage divider circuit, two inverter circuits, and a control switch; the inverter circuits are electrically connected to the voltage divider circuit, a first input terminal of the load is connected to the inverter output terminal of the first inverter circuit, a second input terminal of the load is connected to the inverter output terminal of the second inverter circuit, an intermediate terminal of the load is connected to the voltage divider circuit, and the control switch is connected between the first input terminal and the second input terminal of the load; The control device is connected to the voltage divider circuit, the inverter circuit, and the control switch, respectively. The control device is used to control the control switch to close and merge into a half-wave load operating mode if the output signal of the split-phase inverter is a half-wave signal.

[0014] According to another aspect of the present invention, a split-phase inverter is provided that performs the control method as described above, the split-phase inverter comprising: a voltage divider circuit, two inverter circuits and a control switch; The inverter circuit includes a first bridge arm unit, a second bridge arm unit, and a filter unit. The first end of the first bridge arm unit is connected to the first end of the voltage divider circuit, the second end of the first bridge arm unit is connected to the second end of the voltage divider circuit, the middle end of the first bridge arm unit is connected to the middle end of the voltage divider circuit through the second bridge arm unit, and the middle end of the first bridge arm unit is connected to the inverter output terminal through the filter unit. The first input terminal of the load is connected to the inverter output terminal of the first inverter circuit in the two inverter circuits, the second input terminal of the load is connected to the inverter output terminal of the second inverter circuit in the two inverter circuits, and the middle terminal of the load is connected to the middle terminal of the voltage divider circuit. The control switch is connected between the first input terminal and the second input terminal of the load.

[0015] Furthermore, the control switch includes a relay or a switching transistor.

[0016] According to another aspect of the present invention, an energy storage system is provided, comprising: The battery module and the phase-split inverter as described above, wherein the phase-split inverter is electrically connected to the battery module. The split-phase inverter is used to convert the DC power of the battery module into AC power to supply the load, or to convert the mains power into DC power to charge the battery module.

[0017] In this invention, the split-phase inverter includes two inverter circuits; the control device detects the output signal of the split-phase inverter to determine whether the load electrically connected to the split-phase inverter is a half-wave load; if the output signal of the split-phase inverter is detected to be a half-wave signal, it is determined that the load electrically connected to the split-phase inverter is a half-wave load, and the corresponding control device drives the control switch to close, so that the split-phase inverter enters the half-wave load working mode. In this invention, when the control switch is closed in half-wave load operating mode, both inverter circuits of the split-phase inverter simultaneously provide output signals to the load. This avoids the problem of independent waveform control of a single bridge arm in the inverter, allowing the bridge arm current pulses of the first inverter circuit and the bridge arm current ripples of the second inverter circuit to cancel each other out. This reduces current ripple and current imbalance in the two inverter circuits of the split-phase inverter, which is beneficial for adapting to the dynamic conduction characteristics of half-wave loads. It also avoids voltage imbalance and output waveform distortion in the two inverter circuits caused by the asymmetrical conduction characteristics of half-wave loads, improving the output stability of the split-phase inverter when driving half-wave loads, and thus improving the stability of the energy storage system.

[0018] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of a split-phase inverter provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of a control method for a split-phase inverter provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the switch control signal provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the current ripple provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of a control device for a split-phase inverter provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of an energy storage system provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of another energy storage system provided in an embodiment of the present invention. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0022] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0023] Figure 1 This is a schematic diagram of a split-phase inverter provided in an embodiment of the present invention, for reference. Figure 1 The split-phase inverter provided in this embodiment of the invention includes a voltage divider circuit 101, two inverter circuits 102, and a control switch K1. The inverter circuit 102 includes a first bridge arm unit 1021, a second bridge arm unit 1022, and a filter unit 1023. The first end of the first bridge arm unit 1021 is connected to the first end of the voltage divider circuit 101, the second end of the first bridge arm unit 1021 is connected to the second end of the voltage divider circuit 101, and the middle end of the first bridge arm unit 1021 is connected to the middle end of the voltage divider circuit 101 through the second bridge arm unit 1022. The middle terminal of element 1021 is connected to the inverter output terminal through filter unit 1023; the first input terminal LL1 of load 103 is connected to the inverter output terminal OA of the first inverter circuit 102A in the two inverter circuits 102, the second input terminal LL2 of load 103 is connected to the inverter output terminal OB of the second inverter circuit 102B in the two inverter circuits 102, the middle terminal NL of load 103 is connected to the middle terminal of voltage divider circuit 101; the control switch K1 is connected between the first input terminal LL1 and the second input terminal LL2 of load 103.

[0024] In this embodiment, the split-phase inverter includes two inverter circuits 102, namely a first inverter circuit 102A and a second inverter circuit 102B. The first inverter circuit 102A has an inverter output terminal OA, and the second inverter circuit 102B has an inverter output terminal OB. The inverter circuits 102 are electrically connected between the voltage divider circuit 101 and the load 103. The first input terminal LL1 of the load 103 is connected to the inverter output terminal OA of the first inverter circuit 102A, the second input terminal LL2 of the load 103 is connected to the inverter output terminal OB of the second inverter circuit 102B, and the intermediate terminal NL of the load 103 is connected to the voltage divider circuit 101. Here, the first input terminal LL1 of the load 103 is connected to the live wire, the second input terminal LL2 of the load 103 is connected to the live wire, and the intermediate terminal NL of the load 103 is connected to the neutral wire.

[0025] For the first inverter circuit 102A, the first inverter circuit 102A includes a first bridge arm unit 1021A, a second bridge arm unit 1022A and a filter unit 1023A. The first end of the first bridge arm unit 1021A is connected to the first end of the voltage divider circuit 101, the second end of the first bridge arm unit 1021A is connected to the second end of the voltage divider circuit 101, the middle end of the first bridge arm unit 1021A is connected to the middle end of the voltage divider circuit 101 through the second bridge arm unit 1022A, and the middle end of the first bridge arm unit 1021A is connected to the inverter output terminal OA of the first inverter circuit 102A through the filter unit 1023A.

[0026] The second inverter circuit 102B includes a first bridge arm unit 1021B, a second bridge arm unit 1022B, and a filter unit 1023B. The first end of the first bridge arm unit 1021B is connected to the first end of the voltage divider circuit 101, the second end of the first bridge arm unit 1021B is connected to the second end of the voltage divider circuit 101, the middle end of the first bridge arm unit 1021B is connected to the middle end of the voltage divider circuit 101 through the second bridge arm unit 1022B, and the middle end of the first bridge arm unit 1021B is connected to the inverter output terminal OB of the second inverter circuit 102B through the filter unit 1023B.

[0027] In some embodiments, the first bridge arm unit 1021 includes a first switch and a second switch connected in series, and the second bridge arm unit 1022 includes a third switch and a fourth switch connected in series. The filter unit 1023 includes an inductor and a capacitor.

[0028] For the first inverter circuit 102A, the first bridge arm unit 1021A includes a first switch Q1 and a second switch Q4 connected in series, and the second bridge arm unit 1022A includes a third switch Q2 and a fourth switch Q3 connected in series. The filter unit 1023A includes an inductor L1 and a capacitor C1. The first switch Q1 and the second switch Q4 are connected in series. The main controller is electrically connected to the control terminal of the first switch Q1 and the control terminal of the second switch Q4. The connection point of the first switch Q1 and the second switch Q4 is the middle terminal of the first bridge arm unit 1021A. Correspondingly, the third terminal of the first switch Q1 is the first terminal of the first bridge arm unit 1021A, and the third terminal of the second switch Q4 is the second terminal of the first bridge arm unit 1021A. The third switch Q2 and the fourth switch Q3 are connected in series. The main controller is electrically connected to the control terminal of the third switch Q2 and the control terminal of the fourth switch Q3. The third terminal of the third switch Q2 is electrically connected to the middle terminal of the first bridge arm unit 1021A, and the third terminal of the fourth switch Q3 is electrically connected to the middle terminal of the voltage divider circuit 101. In the filter unit 1023A, the inductor L1 is electrically connected between the middle terminal of the first bridge arm unit 1021A and the corresponding inverter output terminal OA. The first plate of the capacitor C1 is electrically connected to the corresponding inverter output terminal OA, and the second plate of the capacitor C1 is electrically connected to the middle terminal NL of the load 103.

[0029] For the second inverter circuit 102B, the first bridge arm unit 1021B includes a first switch Q5 and a second switch Q6 connected in series, and the second bridge arm unit 1022B includes a third switch Q7 and a fourth switch Q8 connected in series. The filter unit 1023B includes an inductor L2 and a capacitor C2. The first switch Q5 and the second switch Q6 are connected in series. The main controller is electrically connected to the control terminal of the first switch Q5 and the control terminal of the second switch Q6. The connection point of the first switch Q5 and the second switch Q6 is the middle terminal of the first bridge arm unit 1021B. Correspondingly, the third terminal of the first switch Q5 is the first terminal of the first bridge arm unit 1021B, and the third terminal of the second switch Q6 is the second terminal of the first bridge arm unit 1021B. The third switch Q7 and the fourth switch Q8 are connected in series. The main controller is electrically connected to the control terminal of the third switch Q7 and the control terminal of the fourth switch Q8. The third terminal of the third switch Q7 is electrically connected to the middle terminal of the first bridge arm unit 1021B, and the third terminal of the fourth switch Q8 is electrically connected to the middle terminal of the voltage divider circuit 101. In the filter unit 1023B, the inductor L2 is electrically connected between the middle terminal of the first bridge arm unit 1021B and the corresponding inverter output terminal OB. The first plate of the capacitor C2 is electrically connected to the corresponding inverter output terminal OB, and the second plate of the capacitor C2 is electrically connected to the middle terminal NL of the load 103.

[0030] The voltage divider circuit 101 includes a voltage divider unit 1011 and a voltage regulator bridge arm unit 1012 connected in parallel.

[0031] The voltage divider unit 1011 includes a first capacitor C3 and a second capacitor C4 connected in series. The connection point of the first capacitor C3 and the second capacitor C4 is the middle terminal of the voltage divider circuit 101. Specifically, the first plate of the first capacitor C3 and the first plate of the second capacitor C4 are electrically connected, and the connection point is the middle terminal of the voltage divider circuit 101. Correspondingly, the second plate of the first capacitor C3 is the first terminal of the voltage divider circuit 101, and the second plate of the second capacitor C4 is the second terminal of the voltage divider circuit 101.

[0032] The voltage regulator bridge arm unit 1012 includes a fifth switch Q9 and a sixth switch Q10 connected in series. The main controller is electrically connected to the control terminal of the fifth switch Q9 and the control terminal of the sixth switch Q10. Correspondingly, the third terminal of the fifth switch Q9 is electrically connected to the second plate of the first capacitor C3, and the third terminal of the sixth switch Q10 is electrically connected to the second plate of the second capacitor C4. In some embodiments, the voltage regulator bridge arm unit 1012 further includes an inductor L3, which is electrically connected between the middle end of the voltage divider unit 1011 and the middle end of the voltage regulator bridge arm unit 1012. The middle end of the voltage divider unit 1011 is the connection point of the first capacitor C3 and the second capacitor C4, and the middle end of the voltage regulator bridge arm unit 1012 is the connection point of the fifth switch Q9 and the sixth switch Q10.

[0033] Control switch K1 is connected between the first input terminal LL1 and the second input terminal LL2 of load 103. Alternatively, control switch K1 is connected between the inverter output terminal OA of the first inverter circuit 102A and the inverter output terminal OB of the second inverter circuit 102B. It can be understood that a main controller is integrated within the split-phase inverter, or the energy storage system to which the split-phase inverter belongs is integrated with a main controller. The main controller (not shown in the figure) is electrically connected to the control terminal of control switch K1. The main controller provides a conduction level to the control terminal of control switch K1, which turns on control switch K1, thus electrically connecting the first input terminal LL1 and the second input terminal LL2 of load 103. In other words, the inverter output terminal OA of the first inverter circuit 102A and the inverter output terminal OB of the second inverter circuit 102B are electrically connected. The main controller provides a shutdown level to the control terminal of the control switch K1, which can turn off the control switch K1. Then the first input terminal LL1 and the second input terminal LL2 of the load 103 are independent and not electrically connected. In other words, the inverter output terminal OA of the first inverter circuit 102A is not electrically connected to the inverter output terminal OB of the second inverter circuit 102B.

[0034] In some embodiments, the control switch K1 includes a relay or a switching transistor. The control switch K1 can be a relay. Alternatively, the control switch K1 can be a switching transistor, such as an NMOS or a PMOS, but is not limited thereto.

[0035] As described above in the split-phase inverter, when the main controller provides a conduction level to the control terminal of the control switch K1, the control switch K1 is turned on. Then, the inverter output terminal OA of the first inverter circuit 102A and the inverter output terminal OB of the second inverter circuit 102B are electrically connected. Correspondingly, the first inverter circuit 102A and the second inverter circuit 102B simultaneously output standby signals to the load 103.

[0036] In this embodiment of the invention, each switch in the split-phase inverter can be a MOS switch, which has the advantages of fast switching speed and low conduction loss, but is not limited thereto. In some embodiments, the switches in the split-phase inverter can be IGBTs or other types of switching devices.

[0037] It should be noted that, Figure 1 The split-phase inverter shown is only one embodiment of the split-phase inverter in this invention. The structure of the split-phase inverter in this invention includes, but is not limited to, those shown in the embodiments of the present invention. Figure 1 As shown, for Figure 1 Various split-phase inverters obtained by adding or deleting components are also embodiments of the present invention, and will not be described in detail here.

[0038] Figure 2 This is a schematic diagram of a control method for a split-phase inverter provided in an embodiment of the present invention. This control method can be executed by a control device, which can be implemented in hardware and / or software. The control device can be configured within the split-phase inverter, or it can be configured within the energy storage system to which the split-phase inverter belongs. The control device includes the main controller as described above. This is only in conjunction with... Figure 1 The circuit structure of the split-phase inverter shown illustrates the control method of the split-phase inverter provided in this embodiment of the invention. The actual structure of the split-phase inverter is not limited to... Figure 1 As shown.

[0039] refer to Figure 1 and Figure 2 The phase-divergent inverter provided in this embodiment of the invention includes: a voltage divider circuit 101, two inverter circuits 102, and a control switch K1. The inverter circuits 102 are electrically connected to the voltage divider circuit 101. The first input terminal LL1 of the load 103 is connected to the inverter output terminal OA of the first inverter circuit 102A. The second input terminal LL2 of the load 103 is connected to the inverter output terminal OB of the second inverter circuit 102B. The middle terminal NL of the load 103 is connected to the voltage divider circuit 101. The control switch K1 is connected between the first input terminal LL1 and the second input terminal LL2 of the load 103. Based on this phase-divergent inverter, the control method of the phase-divergent inverter provided in this embodiment of the invention includes the following steps: Step 210: Detect the output signal of the split-phase inverter; Step 220: If the output signal of the split-phase inverter is a half-wave signal, then control the switch to close and merge to enter the half-wave load working mode.

[0040] In this embodiment, the split-phase inverter can be adapted to 120 / 240V energy storage systems. It can output 120V AC power with a 180° phase difference and can also output 240V AC power. Therefore, the split-phase inverter can drive both 120V low-voltage AC loads and 240V high-voltage AC loads, but is not limited to this. The loads electrically connected to the split-phase inverter can be of various types. The split-phase inverter provided in this embodiment can be used to drive half-wave loads, which often refer to half-wave rectifier devices. Half-wave rectifier devices include at least an electrically connected half-wave rectifier circuit and resistive / inductive components. Common half-wave rectifier devices include hair dryers, space heaters, and kettles. When a split-phase inverter drives a half-wave load, the output signal provided by the split-phase inverter to the half-wave load is a half-wave signal. Specifically, a half-wave load refers to a nonlinear load that is turned on and consumes energy only in one half of a complete cycle of AC power and is turned off in the other half. In other words, the split-phase inverter drives the load so that the load is in the on state in one half of the cycle and in the off state in the other half of the cycle, alternating between the two. Accordingly, the half-wave signal provided by the split-phase inverter to the half-wave load is a conducting level only in one half of a complete cycle of AC power and a cut-off level in the other half.

[0041] As described above, the half-wave signal provided by the split-phase inverter to the half-wave load is at a conducting level only for half of a complete AC cycle and at a cutoff level for the other half. Based on this, the control device can determine whether the load electrically connected to the split-phase inverter is a half-wave load by detecting whether the output signal of the split-phase inverter is a half-wave signal. If the control device detects that the output signal of the split-phase inverter is a half-wave signal, it can determine that the load electrically connected to the split-phase inverter is a half-wave load; conversely, if the control device detects that the output signal of the split-phase inverter is not a half-wave signal, it can determine that the load electrically connected to the split-phase inverter is not a half-wave load.

[0042] Specifically, the control device is electrically connected to the inverter output terminal OA of the first inverter circuit, the inverter output terminal OB of the second inverter circuit, and the intermediate terminal NL of the load. The signals from the inverter output terminal OA of the first inverter circuit, the inverter output terminal OB of the second inverter circuit, and the intermediate terminal NL of the load constitute the output signal of the split-phase inverter. The control device obtains the output signal of the split-phase inverter and determines whether the output signal of the split-phase inverter is a half-wave signal. Specifically, the output signal of the split-phase inverter obtained by the control device in real time is the current signal of the load port.

[0043] If the control device detects that the output signal of the phase-split inverter is at a conducting level for half of a complete AC cycle and at a cutoff level for the other half, the control device determines that the output signal of the phase-split inverter is a half-wave signal. Accordingly, the control device determines that the load electrically connected to the phase-split inverter is a half-wave load. Furthermore, the control device provides a conducting level to the control switch to close the control switch, and the phase-split inverter enters the half-wave load operating mode. Conversely, if the control device detects that the output signal of the phase-split inverter is not a half-wave signal, the control switch remains in the off state.

[0044] As described above, the split-phase inverter includes two inverter circuits. When the control device determines that the output signal of the split-phase inverter is a half-wave signal, it switches the control switch to the on state, and the split-phase inverter enters the half-wave load operating mode. That is, the two inverter circuits of the split-phase inverter provide output signals to the load. In the half-wave load operating mode, the control switch is closed, causing the first and second inverter circuits of the split-phase inverter to work simultaneously to provide output signals to the load. It can be understood that the two inverter circuits of the split-phase inverter output half-wave signals, enabling both inverter circuits to output simultaneously to drive a half-wave load, can reduce current ripple and current imbalance problems. In addition, with both inverter circuits outputting half-wave signals simultaneously, each inverter circuit only operates for half of the entire power frequency cycle, which can reduce the switching losses of the inverter circuit in the other half of the power frequency cycle and improve the working efficiency of the energy storage system. Furthermore, the simultaneous output of half-wave signals by the two inverter circuits can reduce the voltage imbalance problem between the two inverter circuits on the bus, and the capacitance value of the bus capacitor of the split-phase inverter also needs to be reduced accordingly.

[0045] In this invention, the split-phase inverter includes two inverter circuits; the control device detects the output signal of the split-phase inverter to determine whether the load electrically connected to the split-phase inverter is a half-wave load; if the output signal of the split-phase inverter is detected to be a half-wave signal, it is determined that the load electrically connected to the split-phase inverter is a half-wave load, and the corresponding control device drives the control switch to close, so that the split-phase inverter enters the half-wave load working mode. In this invention, when the control switch is closed in half-wave load operating mode, both inverter circuits of the split-phase inverter simultaneously provide output signals to the load. This avoids the problem of independent waveform control of a single bridge arm in the inverter, allowing the bridge arm current pulses of the first inverter circuit and the bridge arm current ripples of the second inverter circuit to cancel each other out. This reduces current ripple and current imbalance in the two inverter circuits of the split-phase inverter, which is beneficial for adapting to the dynamic conduction characteristics of half-wave loads. It also avoids voltage imbalance and output waveform distortion in the two inverter circuits caused by the asymmetrical conduction characteristics of half-wave loads, improving the output stability of the split-phase inverter when driving half-wave loads, and thus improving the stability of the energy storage system.

[0046] In some embodiments, the operation of detecting the output signal of the split-phase inverter in step 210 includes: acquiring the current signal at the inverter output terminal of the inverter circuit; if the output current of the inverter circuit exists only in the positive or negative half-cycle of the power frequency cycle in N consecutive power frequency cycles, the output signal of the split-phase inverter is determined to be a half-wave signal, where N≥1.

[0047] As mentioned above, the main characteristic of a half-wave load is that there is conduction loss (i.e., power demand) for only half of a power frequency cycle, while the other half is cut off. During one power frequency cycle, the control device detects whether the output signal of the split-phase inverter is a half-wave signal. To improve the accuracy of the detection results, the control device can continuously detect the output signal of the split-phase inverter over multiple consecutive power frequency cycles, thereby enhancing the accuracy of the detection results.

[0048] In this embodiment, the control device acquires the current signal at the inverter output terminal of the inverter circuit for N consecutive power frequency cycles to detect the output current of the inverter circuit. If the control device detects that the output current of the inverter circuit exists only in half of each power frequency cycle in N consecutive power frequency cycles, the control device can determine that the output signal of the split-phase inverter is a half-wave signal, and correspondingly, determine that the load electrically connected to the split-phase inverter is a half-wave load.

[0049] Specifically, the control device collects the current signals from the inverter output terminals of the two inverter circuits for N consecutive power frequency cycles, and detects the output current of the inverter circuits. For at least one of the inverter circuits, if the control device detects that the output current of the inverter circuit exists only in half a cycle of each power frequency cycle for N consecutive power frequency cycles, the control device can determine that the output signal of the split-phase inverter is a half-wave signal, and correspondingly, determine that the load electrically connected to the split-phase inverter is a half-wave load.

[0050] In some embodiments, the operation of detecting the output signal of the split-phase inverter in step 210 includes: acquiring the current signal at the inverter output terminal of the inverter circuit; if the output current of the inverter circuit exists only in the positive or negative half-cycle of the power frequency cycle in N consecutive power frequency cycles, and the effective value error of the output current in different power frequency cycles is within a preset difference range, the output signal of the split-phase inverter is determined to be a half-wave signal, N≥1.

[0051] In this embodiment, the output current of the inverter circuit may have a certain error in different power frequency cycles. Therefore, the control device collects the current signal at the inverter output terminal of the inverter circuit for N consecutive power frequency cycles to detect the output current of the inverter circuit. If, in N consecutive power frequency cycles, the control device detects that the output current of the inverter circuit exists only in half a cycle of each power frequency cycle, and the control device detects that the effective value error of the output current of the inverter circuit in different power frequency cycles is within a preset difference range, the output signal of the split-phase inverter is determined to be a half-wave signal.

[0052] Specifically, the control device collects the current signals from the inverter output terminals of the two inverter circuits for N consecutive power frequency cycles, and detects the output current of the inverter circuits. For at least one inverter circuit, if the control device detects that the output current of the inverter circuit exists only in half a cycle of each power frequency cycle for N consecutive power frequency cycles, and the control device detects that the effective value error of the output current of the inverter circuit in different power frequency cycles is within a preset difference range, then the control device can determine that the output signal of the split-phase inverter is a half-wave signal, and correspondingly, determine that the load electrically connected to the split-phase inverter is a half-wave load.

[0053] It is understood that the control device has a preset difference range as described above stored in advance. This preset difference range is obtained based on laboratory data, actual test data, etc., and will not be explained in detail here.

[0054] In some embodiments, step 220, entering the half-wave load operating mode, includes: during the first half-cycle of the power frequency cycle, turning off the second switch of the first inverter circuit and the second switch of the second inverter circuit; controlling the first inverter circuit to output a first output signal and controlling the second inverter circuit to output a second output signal, wherein the phase difference between the first output signal and the second output signal is 180°. In some embodiments, step 220, entering the half-wave load operating mode, includes: during the second half-cycle of the power frequency cycle, turning off the first to fourth switches of the first inverter circuit and the first to fourth switches of the second inverter circuit. In some embodiments, the first half-cycle of the power frequency cycle is a positive half-cycle and the second half-cycle is a negative half-cycle.

[0055] Figure 3 This is a schematic diagram of the switch control signal provided in an embodiment of the present invention. (Reference) Figures 1 to 3 When the connected load 103 is determined to be a half-wave load, control switch K1 closes, and the split-phase inverter enters the half-wave load operating mode. It should be noted that, for example, if control switch K1 is an NMOS, then when the connected load 103 is determined to be a half-wave load, a high level is provided to control switch K1 to close it. With control switch K1 closed, both inverter circuits 102 of the split-phase inverter output are loaded, thus doubling the load-carrying capacity of the split-phase inverter.

[0056] The control device provides the control signal PWM_Q1 to the control terminal of the first switch Q1 in the first inverter circuit 102A, the control signal PWM_Q4 to the control terminal of the second switch Q4 in the first inverter circuit 102A, the control signal PWM_Q2 to the control terminal of the third switch Q2 in the first inverter circuit 102A, and the control signal PWM_Q3 to the control terminal of the fourth switch Q3 in the first inverter circuit 102A.

[0057] The control device provides the control signal PWM_Q5 to the control terminal of the first switch Q5 in the second inverter circuit 102B, the control signal PWM_Q6 to the control terminal of the second switch Q6 in the second inverter circuit 102B, the control signal PWM_Q7 to the control terminal of the third switch Q7 in the second inverter circuit 102B, and the control signal PWM_Q8 to the control terminal of the fourth switch Q8 in the second inverter circuit 102B.

[0058] It should be noted that, for example, each switch in the inverter circuit 102 is an NMOS, and the control device provides control signals to the switches in the inverter circuit 102, wherein the on level is high and the off level is low.

[0059] In this embodiment, the first half-cycle F1 of the power frequency cycle F is taken as the positive half-cycle and the second half-cycle F2 is taken as the negative half-cycle. In some embodiments, the first half-cycle of the power frequency cycle can be the negative half-cycle and the second half-cycle can be the positive half-cycle.

[0060] After the split-phase inverter enters the half-wave load operating mode, during the first half-cycle (i.e., the positive half-cycle) F1 of the power frequency cycle F, control signals PWM_Q4 and PWM_Q6 are both at a low level, which can turn off the second switch Q4 of the first inverter circuit 102A and the second switch Q6 of the second inverter circuit 102B. Correspondingly, the first switch Q1, the third switch Q2, and the fourth switch Q3 of the first inverter circuit 102A operate normally, and the first switch Q5, the third switch Q7, and the fourth switch Q8 of the second inverter circuit 102B operate normally. Among them, the phase of PWM_Q1 leads the phase of PWM_Q5 by 180°, the phase of PWM_Q2 leads the phase of PWM_Q7 by 180°, and the phase of PWM_Q3 leads the phase of PWM_Q8 by 180°. Based on this, the current in inductor L1 in the first inverter circuit 102A and the current in inductor L2 in the second inverter circuit 102B are 180° out of phase. That is, the first inverter circuit 102A outputs a first output signal and the second inverter circuit 102B outputs a second output signal. The phase difference between the first output signal and the second output signal is 180°. After the output currents of the two inverter circuits 102 are added together in an alternating manner, the current ripple of the load 103 can be reduced, as can the current ripple flowing through capacitors C3 and C4.

[0061] After the split-phase inverter enters the half-wave load operating mode, during the second half-cycle (i.e., the negative half-cycle) F2 of the power frequency cycle F, the first switch Q1, the second switch Q4, the third switch Q2 and the fourth switch Q3 of the first inverter circuit 102A are turned off, and the first switch Q5, the second switch Q6, the third switch Q7 and the fourth switch Q8 of the second inverter circuit 102B are turned off, which can reduce the switching power consumption of the split-phase inverter.

[0062] In some embodiments, step 220, entering the half-wave load operating mode, includes: during the power frequency cycle, if the voltage difference between the first capacitor and the second capacitor exceeds a preset voltage difference range, then controlling the fifth and sixth switches in the voltage regulator bridge arm unit to open in a time-sharing manner. It is understood that the control device pre-stores the preset voltage difference range as described above. This preset voltage difference range is obtained based on laboratory data, actual test data, etc., and will not be specifically described here.

[0063] refer to Figures 1 to 3 The voltage divider circuit 101 includes a first capacitor C3 and a second capacitor C4. The values ​​of the first capacitor C3 and the second capacitor C4 affect the signal magnitude at the middle terminal of the voltage divider circuit 101, and thus affect the current of the load 103. The larger the capacitance of the capacitor, the greater the power consumption of the split-phase inverter. Therefore, when designing capacitors in a split-phase inverter, the capacitance value can be reduced to lower the power consumption of the split-phase inverter. In addition, when the output terminal of the split-phase inverter is connected to a half-wave load, the split-phase inverter only has power output for half of a power frequency cycle. This may lead to a certain voltage difference between the first capacitor C3 and the second capacitor C4. The voltage difference between the first capacitor C3 and the second capacitor C4 may cause one capacitor to have the entire bus voltage or cause one capacitor to occupy most of the bus voltage. When the bus voltage of the capacitor exceeds the rated voltage stress of the capacitor itself, there is a risk of capacitor failure. On this basis, the voltage difference between the first capacitor C3 and the second capacitor C4 also affects the voltage amplitude of the output signal of the split-phase inverter. Based on this, during the power frequency cycle F, when the voltage difference between the first capacitor C3 and the second capacitor C4 exceeds the preset capacitor voltage difference range, the voltage regulator bridge arm unit 1012 is activated, which can avoid the risk of capacitor failure caused by the bus voltage of the capacitor exceeding the rated voltage stress of the capacitor itself.

[0064] In some embodiments, when the output of the split-phase inverter is connected to a half-wave load, the split-phase inverter only outputs power for half of a power frequency cycle. This may cause the voltage stress of at least one switch in the inverter circuit 102 to exceed half the bus voltage or even approach the entire bus voltage. When the voltage stress of the switch in the inverter circuit 102 exceeds the rated voltage stress of the switch itself, there is also a risk of switch failure. Based on this, starting the voltage regulator bridge arm unit 1012 in the power frequency cycle F can also avoid the risk of switch failure caused by the voltage stress of the switch in the inverter circuit 102 exceeding the rated voltage stress of the switch itself.

[0065] In this embodiment, during the power frequency cycle F, when the voltage difference between the first capacitor C3 and the second capacitor C4 exceeds a preset capacitor voltage difference range, the voltage regulator bridge arm unit 1012 is activated. Specifically, the fifth switch Q9 and the sixth switch Q10 in the voltage regulator bridge arm unit 1012 are turned on in a time-sharing manner. When the fifth switch Q9 and the sixth switch Q10 in the voltage regulator bridge arm unit 1012 are conducting complementary high-frequency signals, the inductor L3 will perform energy storage and energy release operations in each switching cycle. In this way, the inductor L3 can transfer the energy of the capacitor with a higher voltage in the first capacitor C3 and the second capacitor C4 to the capacitor with a lower voltage, thereby reducing the voltage difference between the first capacitor C3 and the second capacitor C4 and achieving dynamic voltage balance between the first capacitor C3 and the second capacitor C4, which helps to reduce the risk of capacitor failure.

[0066] As mentioned above, the split-phase inverter can reduce the volume and current of the balancing inductor L3 and reduce the loss of the balancing inductor L3 by adjusting the voltage difference between the first capacitor C3 and the second capacitor C4 according to the actual operating voltage range and the allowable voltage stress of each component. The working requirements of the energy storage system can be met by setting an appropriate voltage difference between the first capacitor C3 and the second capacitor C4.

[0067] Figure 4 This is a schematic diagram of current ripple provided in an embodiment of the present invention. (Reference) Figures 1 to 4 During normal operation of the split-phase inverter, the control signals of each switch in the first inverter circuit 102A and each switch in the second inverter circuit 102B are 180° out of phase. Therefore, the current phases of the inductors L1 in the first inverter circuit 102A and L2 in the second inverter circuit 102B are also 180° out of phase. Figure 4 Figure I1 shows the current in inductor L1 in the first inverter circuit 102A and the current in inductor L2 in the second inverter circuit 102B, with a phase difference of 180° between the two currents. The superposition of the currents in inductor L1 in the first inverter circuit 102A and inductor L2 in the second inverter circuit 102B, followed by capacitors C1 and C2, reduces the output current ripple of the first inverter circuit 102A and the second inverter circuit 102B by 80%. Figure 4 Figure I2 shows the output current of the first inverter circuit 102A and the output current of the second inverter circuit 102B, with the two currents being 180° out of phase.

[0068] In this embodiment, the split-phase inverter includes two inverter circuits and a control switch. The control device detects the current signals at the output terminals of the two inverter circuits and determines whether the electrically connected load is a half-wave load based on the power distribution of the current signals during the positive and negative half-cycles of multiple power frequency cycles. When the control device determines that the load is a half-wave load, it closes the control switch K1, allowing both inverter circuits to output loads simultaneously, thus doubling the split-phase inverter's ability to handle half-wave loads. Specifically, after entering the half-wave load operating mode, both inverter circuits operate during the positive half-cycle of the power frequency cycle and are off during the other half-cycle, or both inverter circuits operate during the negative half-cycle of the power frequency cycle and are off during the other half-cycle. This reduces the switching losses of the inverter circuits, making the output current of the two inverter circuits more balanced, and simultaneously reducing the ripple current of the bus capacitor. Furthermore, the addition of a voltage regulator bridge arm unit in the split-phase inverter, which operates intermittently to reduce losses, allows for flexible adjustment of the bus voltage difference between the first capacitor C3 and the second capacitor C4. This helps reduce the ripple current of both the inductor and capacitor, and also allows for a lower current rating for the switch selection, reducing the current stress on inductor L3. Moreover, the split-phase inverter can also operate in off-grid output mode. In this mode, the control strategy of the control device can actively identify whether the off-grid output is driven by a half-wave load, and then adjust and optimize the output to improve efficiency and reduce the power consumption of the half-wave load. This improves the output stability of the split-phase inverter when driving a half-wave load, thereby enhancing the stability of the energy storage system.

[0069] Based on the same inventive concept, embodiments of the present invention provide a control device for a split-phase inverter. Figure 5 This is a schematic diagram of a control device for a split-phase inverter provided in an embodiment of the present invention. The control device 110 provided in this embodiment can execute the control method provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the execution method. The control device 110 of the split-phase inverter 100 provided in this embodiment includes, but is not limited to, the control devices described in the foregoing embodiments.

[0070] refer to Figure 5The split-phase inverter 100 includes: a voltage divider circuit 101, two inverter circuits 102, and a control switch K1; the inverter circuits 102 are electrically connected to the voltage divider circuit 101; the first input terminal LL1 of the load 103 is connected to the inverter output terminal OA of the first inverter circuit 102A of the two inverter circuits 102; the second input terminal LL2 of the load 103 is connected to the inverter output terminal OB of the second inverter circuit 102B of the two inverter circuits 102; the middle terminal NL of the load 103 is connected to the voltage divider circuit 101; and the control switch K1 is connected between the first input terminal LL1 and the second input terminal LL2 of the load 103; a control device 110 is connected to the voltage divider circuit 101, the inverter circuits 102, and the control switch K1; the control device 110 is used to control the control switch K1 to close and enter the half-wave load working mode if the output signal of the split-phase inverter 100 is a half-wave signal.

[0071] In some embodiments, the control device 110 is used to collect the current signal at the inverter output terminal of the inverter circuit 102. If the output current of the inverter circuit 102 exists only in the positive half-cycle or negative half-cycle of the power frequency cycle in N consecutive power frequency cycles, the output signal of the split-phase inverter 100 is determined to be a half-wave signal, where N≥1.

[0072] In some embodiments, the control device 110 is used to collect the current signal at the inverter output terminal of the inverter circuit 102. If the output current of the inverter circuit 102 exists only in the positive or negative half-cycle of the power frequency cycle in N consecutive power frequency cycles, and the effective value error of the output current in different power frequency cycles is within a preset difference range, the output signal of the split-phase inverter 100 is determined to be a half-wave signal, N≥1.

[0073] In some embodiments, the control device 110 is used to turn off the second switch Q4 of the first inverter circuit 102A and the second switch Q6 of the second inverter circuit 102B during the first half-cycle of the power frequency cycle, control the first inverter circuit 102A to output a first output signal, and control the second inverter circuit 102B to output a second output signal, wherein the phase difference between the first output signal and the second output signal is 180°.

[0074] In some embodiments, the control device 110 is used to turn off the first to fourth switches of the first inverter circuit 102A and the first to fourth switches of the second inverter circuit 102B during the second half-cycle of the power frequency cycle.

[0075] In some embodiments, the first half-cycle of the power frequency cycle is a positive half-cycle and the second half-cycle is a negative half-cycle.

[0076] In some embodiments, the control device 110 is used to control the fifth switch Q9 and the sixth switch Q10 in the voltage regulator bridge arm unit 1012 to turn on in a time-sharing manner if the voltage difference between the first capacitor C3 and the second capacitor C4 exceeds a preset capacitor voltage difference range during the power frequency cycle.

[0077] In this embodiment, the split-phase inverter includes two inverter circuits and a control switch. The control device detects the current signals at the output terminals of the two inverter circuits and determines whether the electrically connected load is a half-wave load based on the power distribution of the current signals during the positive and negative half-cycles of multiple power frequency cycles. When the control device determines that the load is a half-wave load, it closes the control switch K1, allowing both inverter circuits to output loads simultaneously, thus doubling the split-phase inverter's ability to handle half-wave loads. Specifically, after entering the half-wave load operating mode, both inverter circuits operate during the positive half-cycle of the power frequency cycle and are off during the other half-cycle, or both inverter circuits operate during the negative half-cycle of the power frequency cycle and are off during the other half-cycle. This reduces the switching losses of the inverter circuits, making the output current of the two inverter circuits more balanced, and simultaneously reducing the ripple current of the bus capacitor. Furthermore, the addition of a voltage regulator bridge arm unit in the split-phase inverter, which operates intermittently to reduce losses, allows for flexible adjustment of the bus voltage difference between the first capacitor C3 and the second capacitor C4. This helps reduce the ripple current of both the inductor and capacitor, and also allows for a lower current rating for the switch selection, reducing the current stress on inductor L3. Moreover, the split-phase inverter can also operate in off-grid output mode. In this mode, the control strategy of the control device can actively identify whether the off-grid output is driven by a half-wave load, and then adjust and optimize the output to improve efficiency and reduce the power consumption of the half-wave load. This improves the output stability of the split-phase inverter when driving a half-wave load, thereby enhancing the stability of the energy storage system.

[0078] Based on the same inventive concept, embodiments of the present invention provide an energy storage system. Figure 6 This is a schematic diagram of an energy storage system provided in an embodiment of the present invention. Figure 7 This is a schematic diagram of another energy storage system provided in an embodiment of the present invention. (Reference) Figure 6 and Figure 7 The energy storage system 1 provided in this embodiment of the invention includes: a battery module 11 and a phase-splitting inverter 100 as described in any embodiment of the invention. The phase-splitting inverter 100 is electrically connected to the battery module 11. The phase-splitting inverter 100 is used to convert the DC power of the battery module 11 into AC power to supply the load 12, or to convert the AC mains power into DC power to charge the battery module 11.

[0079] refer to Figure 6The split-phase inverter 100 is electrically connected to the battery module 11 and also electrically connected to the load 12. The load 12 can be the half-wave load 103 described in any embodiment of the present invention, but is not limited thereto. In some embodiments, the split-phase inverter 100 is electrically connected between the battery module 11 and the load 12. The load 12 can be a non-half-wave load, without specific limitations. The split-phase inverter 100 is used to convert the DC power from the battery module 11 into AC power and supply it to the load 12. That is, the split-phase inverter 100 provides an output signal to the load 12, enabling the battery module 11 to supply power to the load 12.

[0080] refer to Figure 7 Here, AC represents the mains power. The split-phase inverter 100 is electrically connected to the battery module 11, and also electrically connected to the AC mains power. The split-phase inverter 100 is used to convert the AC mains power into DC power and supply it to the battery module 11; that is, it is connected to the mains power AC. Figure 6 The difference is that here, the split-phase inverter 100 provides an output signal to the battery module 11, enabling the AC mains power to charge the battery module 11.

[0081] It is understood that the energy storage system 1 can be a consumer-grade energy storage system or an industrial / commercial energy storage system.

[0082] Consumer-grade energy storage systems include at least balcony photovoltaic (PV) energy storage systems, home energy storage systems, or portable energy storage systems. Balcony PV energy storage systems are suitable for apartment balconies; they are plug-and-play, storing energy generated during the day and providing power at night or on cloudy days. Combined with mobile app monitoring and automatic optimization of charging and discharging, they can significantly reduce household electricity bills. Home energy storage systems are suitable for detached houses, working with rooftop PV systems to store energy during the day and use it at night, taking advantage of peak-valley electricity price differences to save costs. They also serve as backup power, ensuring the normal operation of critical equipment during power outages. Portable energy storage systems are suitable for outdoor camping and road trips, charging devices such as mobile phones, cameras, and drones. They can also be used for fieldwork, emergency lighting, and core backup power; they are lightweight and portable, supporting multiple output interfaces to meet diverse needs.

[0083] Specifically, the energy storage system 1 includes a battery module 11, a battery management system (BMS, not shown in the figure), an energy management system (EMS, not shown in the figure), and an inverter 100. The inverter 100 is electrically connected to the battery module 11 and converts the direct current (DC) generated by the battery module 11 into alternating current (AC) for use by the electrical equipment, i.e., the load 12. The inverter 100 can also convert AC mains power into DC to charge the battery module 11. The inverter 100 includes a split-phase inverter. The battery management system monitors the status information of each cell in the battery module 11, such as current, temperature, or voltage, to prevent overcharging, over-discharging, or short circuits, thus protecting the cells in the battery module 11 from damage. The control board of the energy management system is electrically connected to the battery module 11 and the inverter 100, and receives user commands through a user input port to control the charging or discharging process between the battery module 11 and the inverter 100.

[0084] Note that the above embodiments of this application are merely illustrative examples for the purpose of clearly illustrating the present application, and are not intended to limit the implementation of the present application, nor do they constitute a limitation on the scope of protection of the present application. For those skilled in the art, various obvious changes, readjustments, and substitutions can be made according to design requirements and other factors without departing from the scope of protection of the present application. Therefore, although the present application has been described in detail through the above embodiments, the present application is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present application. It is neither necessary nor possible to exhaustively describe all implementation methods here. The scope of the present application is determined by the scope of the appended claims. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present application should be included within the scope of protection of the claims of the present application.

Claims

1. A control method for a split-phase inverter, characterized in that, The split-phase inverter includes: a voltage divider circuit, two inverter circuits, and a control switch; the inverter circuits are electrically connected to the voltage divider circuit, the first input terminal of the load is connected to the inverter output terminal of the first inverter circuit, the second input terminal of the load is connected to the inverter output terminal of the second inverter circuit, the middle terminal of the load is connected to the voltage divider circuit, and the control switch is connected between the first input terminal and the second input terminal of the load. The control method includes: Detect the output signal of the split-phase inverter; If the output signal of the split-phase inverter is a half-wave signal, then the control switch is controlled to close and merge into the half-wave load working mode.

2. The control method according to claim 1, characterized in that, Detecting the output signal of the split-phase inverter includes: Acquire the current signal at the inverter output terminal of the inverter circuit; If the output current of the inverter circuit exists only in the positive or negative half-cycle of the power frequency cycle in N consecutive power frequency cycles, the output signal of the split-phase inverter is determined to be a half-wave signal, and N≥1.

3. The control method according to claim 1, characterized in that, Detecting the output signal of the split-phase inverter includes: Acquire the current signal at the inverter output terminal of the inverter circuit; If the output current of the inverter circuit exists only in the positive or negative half-cycle of the power frequency cycle in N consecutive power frequency cycles, and the effective value error of the output current in different power frequency cycles is within a preset difference range, the output signal of the split-phase inverter is determined to be a half-wave signal, N≥1.

4. The control method according to claim 1, characterized in that, The inverter circuit includes a first bridge arm unit, a second bridge arm unit, and a filter unit. The first end of the first bridge arm unit is connected to the first end of the voltage divider circuit, the second end of the first bridge arm unit is connected to the second end of the voltage divider circuit, the middle end of the first bridge arm unit is connected to the middle end of the voltage divider circuit through the second bridge arm unit, and the middle end of the first bridge arm unit is connected to the inverter output terminal through the filter unit. The first bridge arm unit includes a first switch and a second switch connected in series, and the second bridge arm unit includes a third switch and a fourth switch connected in series. Entering half-wave load operating mode includes: During the first half of the power frequency cycle, the second switch of the first inverter circuit is turned off, and the second switch of the second inverter circuit is also turned off. The first inverter circuit is controlled to output a first output signal, and the second inverter circuit is controlled to output a second output signal, wherein the phase difference between the first output signal and the second output signal is 180°.

5. The control method according to claim 4, characterized in that, Entering half-wave load operating mode includes: During the second half-cycle of the power frequency cycle, the first to fourth switches of the first inverter circuit are turned off, and the first to fourth switches of the second inverter circuit are also turned off.

6. The control method according to claim 5, characterized in that, The first half-cycle of the power frequency cycle is the positive half-cycle and the second half-cycle is the negative half-cycle.

7. The control method according to claim 1, characterized in that, The voltage divider circuit includes a voltage divider unit and a voltage regulator bridge arm unit connected in parallel. The voltage divider unit includes a first capacitor and a second capacitor connected in series. The voltage regulator bridge arm unit includes a fifth switch and a sixth switch connected in series. Entering half-wave load operating mode includes: During the power frequency cycle, if the voltage difference between the first capacitor and the second capacitor exceeds a preset voltage difference range, the fifth and sixth switches in the voltage regulator bridge unit are controlled to open in a time-sharing manner.

8. A control device for a split-phase inverter, characterized in that, The split-phase inverter includes: a voltage divider circuit, two inverter circuits, and a control switch; the inverter circuits are electrically connected to the voltage divider circuit, the first input terminal of the load is connected to the inverter output terminal of the first inverter circuit, the second input terminal of the load is connected to the inverter output terminal of the second inverter circuit, the middle terminal of the load is connected to the voltage divider circuit, and the control switch is connected between the first input terminal and the second input terminal of the load. The control device is connected to the voltage divider circuit, the inverter circuit, and the control switch, respectively. The control device is used to control the control switch to close and merge into a half-wave load operating mode if the output signal of the split-phase inverter is a half-wave signal.

9. A split-phase inverter, characterized in that, The phase-divider inverter, which performs the control method as described in any one of claims 1-7, comprises: a voltage divider circuit, two inverter circuits, and a control switch; The inverter circuit includes a first bridge arm unit, a second bridge arm unit, and a filter unit. The first end of the first bridge arm unit is connected to the first end of the voltage divider circuit, the second end of the first bridge arm unit is connected to the second end of the voltage divider circuit, the middle end of the first bridge arm unit is connected to the middle end of the voltage divider circuit through the second bridge arm unit, and the middle end of the first bridge arm unit is connected to the inverter output terminal through the filter unit. The first input terminal of the load is connected to the inverter output terminal of the first inverter circuit in the two inverter circuits, the second input terminal of the load is connected to the inverter output terminal of the second inverter circuit in the two inverter circuits, and the middle terminal of the load is connected to the middle terminal of the voltage divider circuit. The control switch is connected between the first input terminal and the second input terminal of the load.

10. The split-phase inverter according to claim 9, characterized in that, The control switch includes: a relay or a switching transistor.

11. An energy storage system, characterized in that, include: The battery module and the phase-split inverter as described in any one of claims 9-10, wherein the phase-split inverter is electrically connected to the battery module; The split-phase inverter is used to convert the DC power of the battery module into AC power to supply the load, or to convert the mains power into DC power to charge the battery module.

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