A split-phase inverter circuit and a split-phase inverter

Abstract

The present invention provides a split-phase inverter circuit and a split-phase inverter, comprising: a first unidirectional inverter unit and a second unidirectional inverter unit, wherein the first unidirectional inverter unit has a switch tube S1, an inductor L1 and a diode D1, the positive electrode of a power input unit is connected to a first output unit through the switch tube S1 and the inductor L1, the first output unit is connected to a negative electrode through a capacitor C2, and the negative electrode of the power input unit is also connected to the first output unit through an anode and a cathode of a diode D1 and the inductor L1; and a switch tube S2, an inductor L2 and a diode D2, the positive electrode of the power input unit is connected to the first output unit through a capacitor C1, the first output unit is connected to a negative electrode of the power input unit through the inductor L2 and the switch tube S2, and the first output unit is also connected to a second end of the first output unit through the inductor L2, the anode and the cathode of the diode D2, and the capacitor C1. The present invention solves the problem of low working efficiency of the split-phase circuit system existing in the prior art.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and in particular to a split-phase inverter circuit and a split-phase inverter. Background Art

[0002] Clean energy represented by photovoltaic power generation has become a trend in the development of new energy. Feeding the electricity generated by the photovoltaic power generation system into the grid is one of its basic functions, which requires the inverter system to be compatible with the local power grid standard.

[0003] The most common power grid systems are the single-phase 220V / 230V and three-phase 380V / 400V, 50HZ systems used in China, Europe and other countries. However, in Japan and the United States, there are dual-phase systems with a phase difference of 180°, also called split-phase systems, which are 120V / 240V, 60HZ (USA) and 101 / 202V, 60HZ (Japan). Therefore, in Japan, the United States and other countries, low-power electrical equipment generally uses a single live wire, that is, 120V power supply, and high-power electrical equipment generally uses a dual live wire, that is, 240V power supply. There are also situations where both 120V and 240V power supplies exist at the same time.

[0004] In recent years, with the development of new energy technology, split-phase system countries such as the United States have also achieved vigorous development, and the demand for photovoltaic inverters and energy storage inverters has also increased. In the past, in order to generate 180° two-phase electricity, the inverters in America used the single-phase 230V inverter output voltage and matched it with the industrial frequency split-phase transformer. A midpoint was generated through the center tap of the split-phase transformer, and then a 120 / 240V split-phase power supply system was generated. However, due to the existence of the industrial frequency transformer, the entire system was relatively bulky, inefficient, and costly, and many other disadvantages.

[0005] In recent years, split-phase inverter circuits have gradually developed. However, existing split-phase inverter circuits have the problem that when the high-frequency switch tube is turned off, the freewheeling current of the two phases will flow through at least four switch tubes, resulting in the problem that the overall efficiency of the above circuit system is low. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a split-phase inverter circuit and a split-phase inverter, which solve the problem of low working efficiency of the split-phase circuit system in the prior art.

[0007] At least one embodiment of the present invention provides a split-phase inverter circuit, comprising:

[0008] A power input unit, a first output unit, a second output unit, and a first unidirectional inverter unit and a second unidirectional inverter unit that differ in output phase by 180°, wherein the power input unit is connected to the first output unit via the first unidirectional inverter unit, and the power input unit is connected to the second output unit via the second unidirectional inverter unit, wherein:

[0009] The first unidirectional inverter unit includes a first bridge arm and a second bridge arm;

[0010] The first bridge arm has a switch tube S1, an inductor L1 and a diode D1, the positive electrode of the power input unit is connected to the first end of the first output unit through the switch tube S1 and the inductor L1 in sequence, the second end of the first output unit is connected to the negative electrode of the power input unit through the capacitor C2, and the negative electrode of the power input unit is also connected to the first end of the first output unit through the anode and cathode of the diode D1 and the inductor L1 in sequence;

[0011] The second bridge arm has a switch tube S2, an inductor L2 and a diode D2. The positive electrode of the power input unit is connected to the second end of the first output unit through the capacitor C1. The first end of the first output unit is connected to the negative electrode of the power input unit through the inductor L2 and the switch tube S2 in turn. The first end of the first output unit is also connected to the second end of the first output unit through the inductor L2, the anode and cathode of the diode D2, and the capacitor C1 in turn.

[0012] The technical solution disclosed in the present invention has at least the following beneficial effects:

[0013] Through the above arrangement, when the power input unit is turned on, the first unidirectional inverter circuit can output a first alternating current to the first output unit, and the second unidirectional inverter circuit can output a second alternating current that is 180° out of phase with the first alternating current to the second output unit;

[0014] In the above working process, the switch tube S1 is controlled to be turned on, and the positive current output by the power input unit can enter the first end of the first output unit through the switch tube S1 and the inductor L1. At this time, the inductor L1 stores the positive current, so that the positive current output by the power input unit gradually increases in the first output unit, and then the switch tube S2 is turned off. At this time, the electric energy stored in the inductor L1 is released to form a freewheeling current, which passes through the capacitor Co, the capacitor C2 and the diode D1 in sequence to return to the inductor L1, and gradually decreases to 0, thereby realizing the positive half-cycle output of the AC current;

[0015] When the current flowing through the inductor L1 is reduced to 0, the switch tube S2 is controlled to be turned on, and the positive current output by the power input unit can flow through the second end of the first output unit through the capacitor C1, and return to the power input unit through the first end of the first output unit, the inductor L2 and the switch tube S2. The inductor L2 is used to store the above positive current to achieve a gradual increase in the current flowing through the first output unit. At the same time, after the switch tube S2 is turned off, the electric energy stored in the inductor L2 is released to form a freewheeling current. The freewheeling current passes through the diode D2, the capacitor C1 and the first output unit in sequence to return to the inductor L2, and gradually decreases to 0, thereby achieving the negative half-cycle output of the AC current;

[0016] That is, by controlling the staggered on and off of the switch tube S1 and the switch tube S2, the output of AC current can be achieved;

[0017] At the same time, in the present invention, the two-phase freewheeling current can flow in the preset loop without the need to additionally set up other switching tubes and controllers, thereby optimizing the entire split-phase inverter circuit and improving the output efficiency of the split-phase inverter circuit.

[0018] In an embodiment of a split-phase inverter circuit provided by the present invention, the second unidirectional inverter unit includes a third bridge arm and a fourth bridge arm;

[0019] The third bridge arm has a switch tube S3, an inductor L3 and a diode D3. The positive electrode of the power input unit is connected to the first end of the second output unit through the switch tube S3 and the inductor L3 in sequence. The second end of the second output unit is connected to the negative electrode of the power input unit through the capacitor C8. The negative electrode of the power input unit is also connected to the first end of the second output unit through the anode and cathode of the diode D3 and the inductor L3 in sequence.

[0020] The fourth bridge arm has a switch tube S4, an inductor L4 and a diode D4, the positive electrode of the power input unit is connected to the second end of the second output unit through the capacitor C7, the first end of the second output unit is connected to the negative electrode of the power input unit through the inductor L4 and the switch tube S4 in sequence, and the first end of the second output unit is also connected to the second end of the second output unit through the inductor L4, the anode and cathode of the diode D4 and the capacitor C7 in sequence;

[0021] The switch tubes S1 and S4 are configured to be turned on synchronously in a first time period, and the switch tubes S2 and S3 are configured to be turned on synchronously in a second time period, so as to invert the voltage output by the power input unit.

[0022] The beneficial effect of adopting the above scheme is: by controlling the switch tube S1 and the switch tube S4 to be turned on at the same time, the first output unit and the second output unit can obtain the positive half-cycle output of the alternating current with opposite phases, and by controlling the switch tube S2 and the switch tube S3 to be turned on at the same time, the negative half-cycle output of the alternating current with opposite phases can be obtained.

[0023] In an embodiment of a split-phase inverter circuit provided by the present invention, an equivalent parasitic capacitor C3 is connected in parallel to the diode D1, and an equivalent parasitic capacitor C5 is connected in parallel to the diode D3.

[0024] The beneficial effect of adopting the above scheme is: utilizing the natural oscillation generated by the equivalent parasitic capacitance C3 and the inductance L1, and the natural oscillation generated by the equivalent parasitic capacitance C5 and the inductance L3, respectively, to put the switch tube S1 and the switch tube S3 in a critical open state, and then when the switch tube S1 and the switch tube S3 need to be turned on, the switch tube S1 and the switch tube S3 can be turned on with zero voltage, thereby improving the operating efficiency of the circuit.

[0025] In an embodiment of a split-phase inverter circuit provided by the present invention, an equivalent parasitic capacitor C4 is connected in parallel to the switch tube S2, and an equivalent parasitic capacitor C6 is connected in parallel to the switch tube S4.

[0026] The beneficial effect of adopting the above scheme is: utilizing the natural oscillation generated by the equivalent parasitic capacitance C4 and the inductance L2, and the natural oscillation generated by the equivalent parasitic capacitance C6 and the inductance L4, respectively, the switch tube S2 and the switch tube S4 are in a critical open state, and then when the switch tube S2 and the switch tube S4 need to be turned on, the switch tube S1 and the switch tube S3 can be turned on with zero voltage, thereby improving the operating efficiency of the circuit.

[0027] In an embodiment of a split-phase inverter circuit provided by the present invention, the switch tube S1, the switch tube S2, the switch tube S3 and the switch tube S4 are all MOS tubes, and the gate end of each MOS tube is connected to a controller for controlling its disconnection.

[0028] The beneficial effect of adopting the above solution is that the on-off of each MOS tube can be accurately modulated by using the control signal output by the controller.

[0029] In an embodiment of a split-phase inverter circuit provided by the present invention, the inductor L1 and the inductor L2 form a group of coupled inductors.

[0030] The beneficial effect of adopting the above solution is that the number of corresponding power devices can be reduced through the above arrangement, thereby reducing the manufacturing cost of the circuit.

[0031] In an embodiment of a split-phase inverter circuit provided by the present invention, the inductor L3 and the inductor L4 form a group of coupled inductors.

[0032] The beneficial effect of adopting the above solution is that the number of corresponding power devices can be reduced through the above arrangement, thereby reducing the manufacturing cost of the circuit.

[0033] In an embodiment of a split-phase inverter circuit provided by the present invention, the first output unit includes a first output capacitor Co and a filtering unit, wherein:

[0034] Two ends of the first output capacitor Co are respectively the first end and the second end of the first output unit, and the two ends of the first output capacitor Co are also connected to the filter unit.

[0035] The beneficial effect of adopting the above solution is: the alternating voltage output by the first output capacitor Co is filtered by the filtering unit, so that the obtained waveform is smoother.

[0036] In a split-phase inverter circuit embodiment provided by the present invention, the filter unit includes an inductor Lf and a capacitor Cf, wherein one end of the first output capacitor Co is connected to the other end of the first output capacitor Co via the inductor Lf and the capacitor Cf in sequence.

[0037] The beneficial effect of adopting the above solution is: the output voltage is filtered by using the capacitor Cf and the inductor Lf, so that the obtained waveform is smoother.

[0038] At least one embodiment of the present invention further provides a split-phase inverter, comprising a split-phase inverter circuit as described above.

[0039] The beneficial effect of adopting the above scheme is that after adopting the above split-phase inverter circuit, it can ensure that the split-phase inverter is more efficient when in use. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a structural schematic diagram of a split-phase inverter circuit of the present invention;

[0041] Figure 2 A schematic diagram of a specific connection relationship of a split-phase inverter circuit according to the present invention;

[0042] Figure 3 A schematic diagram of current flow direction of a split-phase inverter circuit during a preset time period T1 of the present invention;

[0043] Figure 4 A schematic diagram of current flow direction of a split-phase inverter circuit during a preset time period T2 according to the present invention;

[0044] Figure 5 The present invention relates to an output voltage waveform diagram of a split-phase inverter circuit during a preset time period T1, a preset time period T2, a preset time period T3 and a preset time period T4 respectively. DETAILED DESCRIPTION

[0045] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0046] Furthermore, those skilled in the art may combine and associate different embodiments or examples and features of different embodiments or examples described in this specification without mutual contradiction.

[0047] The present invention provides a split-phase inverter circuit, please refer to Figure 1 As shown, including:

[0048] A power input unit, a first output unit, a second output unit, and a first unidirectional inverter unit and a second unidirectional inverter unit that differ in output phase by 180°, wherein the power input unit is connected to the first output unit via the first unidirectional inverter unit, and the power input unit is connected to the second output unit via the second unidirectional inverter unit, wherein:

[0049] The first unidirectional inverter unit includes a first bridge arm and a second bridge arm;

[0050] The first bridge arm has a switch tube S1, an inductor L1 and a diode D1. The positive electrode of the power input unit is connected to the first end of the first output unit through the switch tube S1 and the inductor L1 in sequence. The second end of the first output unit is connected to the negative electrode of the power input unit through the capacitor C2. The negative electrode of the power input unit is also connected to the first end of the first output unit through the anode and cathode of the diode D1 and the inductor L1 in sequence. The above-mentioned power input unit is Figure 2 The power supply Cin in.

[0051] The second bridge arm has a switch tube S2, an inductor L2 and a diode D2. The positive electrode of the power input unit is connected to the second end of the first output unit through the capacitor C1. The first end of the first output unit is connected to the negative electrode of the power input unit through the inductor L2 and the switch tube S2 in turn. The first end of the first output unit is also connected to the second end of the first output unit through the inductor L2, the anode and cathode of the diode D2, and the capacitor C1 in turn.

[0052] Through the above arrangement, when the power input unit is turned on, the first unidirectional inverter circuit can output a first alternating current to the first output unit, and the second unidirectional inverter circuit can output a second alternating current that is 180° out of phase with the first alternating current to the second output unit;

[0053] In the above working process, the control switch tube S1 is turned on. Please refer to Figure 3 In the current loop located at the top, the positive current output by the power input unit can enter the first end of the first output unit through the switch tube S1 and the inductor L1. At this time, the inductor L1 stores the positive current, so that the positive current output by the power input unit gradually increases in the first output unit, and then the switch tube S2 is turned off. Please refer to Figure 4In the current loop located at the top, the electric energy stored in the inductor L1 is released to form a freewheeling current, which returns to the inductor L1 through the capacitor Co, the capacitor C2 and the diode D1 in sequence, and gradually decreases to 0, thereby realizing the positive half-cycle output of the AC current;

[0054] When the current flowing through the inductor L1 decreases to 0, the control switch S2 is turned on, and the positive current output by the power input unit can flow through the second end of the first output unit through the capacitor C1, and return to the power input unit through the first end of the first output unit, the inductor L2 and the switch S2. Figure 3 The current loop at the bottom of the circuit is similar to that of FIG. 1 , inductor L2 is used to store the positive current to realize the gradual increase of the current flowing through the first output unit. At the same time, after the switch tube S2 is turned off, the electric energy stored in the inductor L2 is released to form a freewheeling current. The freewheeling current passes through the diode D2, the capacitor C1 and the second end and the first end of the first output unit in sequence to return to the inductor L2 and gradually decrease to 0, thereby realizing the negative half-cycle output of the AC current. This current loop is similar to Figure 4 The current loop at the bottom is similar;

[0055] That is, by controlling the staggered on and off of the switch tube S1 and the switch tube S2, the output of AC current can be achieved;

[0056] At the same time, in the present invention, the two-phase freewheeling current can flow in the preset loop without the need to additionally set up other switching tubes and controllers, thereby optimizing the entire split-phase inverter circuit and improving the output efficiency of the split-phase inverter circuit.

[0057] Further, the second unidirectional inverter unit includes a third bridge arm and a fourth bridge arm;

[0058] The third bridge arm has a switch tube S3, an inductor L3 and a diode D3. The positive electrode of the power input unit is connected to the first end of the second output unit through the switch tube S3 and the inductor L3 in sequence. The second end of the second output unit is connected to the negative electrode of the power input unit through the capacitor C8. The negative electrode of the power input unit is also connected to the first end of the second output unit through the anode and cathode of the diode D3 and the inductor L3 in sequence.

[0059] The fourth bridge arm has a switch tube S4, an inductor L4 and a diode D4, the positive electrode of the power input unit is connected to the second end of the second output unit through the capacitor C7, the first end of the second output unit is connected to the negative electrode of the power input unit through the inductor L4 and the switch tube S4 in sequence, and the first end of the second output unit is also connected to the second end of the second output unit through the inductor L4, the anode and cathode of the diode D4 and the capacitor C7 in sequence;

[0060] The switch tubes S1 and S4 are configured to be modulated by SPWM and turned on synchronously in the first time period, and the switch tubes S2 and S3 are configured to be modulated by SPWM and turned on synchronously in the second time period to invert the voltage output by the power input unit.

[0061] In the above arrangement, two opposite-phase alternating currents outputted by a split-phase inverter circuit are taken as an example for one cycle;

[0062] Please refer to here Figure 5 As shown, the above cycle is divided into a preset time period T1, a preset time period T2, a preset value time period T3 and a preset time period T4, wherein the above first time period is the preset time period T1, and the above second time period is the preset time period T3. Figure 2 as well as Figure 3 As shown, at the beginning of the preset time period T1, the switch tube S1 and the switch tube S4 are turned on synchronously, the switch tube S2 and the switch tube S3 are in the cut-off state, and the positive current output by the positive electrode of the power input unit returns to the negative electrode of the power input unit through the switch tube S1, the inductor L1, the first end and the second end of the first output unit and the capacitor C2 in sequence. At this time, since the current passing through the inductor L1 cannot change suddenly, when the above-mentioned positive current flows from one end of the inductor L1 to the other end, the current at the other end of the inductor L1 gradually increases from 0, thereby gradually increasing the voltage at the first output unit. Please refer to Figure 5 In the figure, the waveform at the top shows the voltage change in the T1 stage. During this process, the inductor L1 gradually stores electrical energy.

[0063] Correspondingly, at the beginning of the preset time period T1, the positive current outputted from the positive electrode of the power input unit sequentially passes through the capacitor C7, the second end and the first end of the second output unit, the inductor L4 and the switch tube S4 and returns to the negative electrode of the power input unit. At this time, since the current passing through the inductor L4 cannot change suddenly, when the positive current flows from one end of the inductor L4 to the other end, the current at the other end of the inductor L4 gradually increases from 0, thereby gradually increasing the voltage at the second output unit. Please refer to Figure 5 In the waveform in the middle, the voltage changes in the T1 stage. During this process, the inductor L4 gradually stores electric energy. Since the positive current output by the power input unit flows through the first bridge arm into the first output unit, the current flows in the opposite direction to the current flows through the fourth bridge arm into the second output unit. At this time, the voltages of the two phases detected are in an anti-phase relationship.

[0064] During the preset time period T2, the switch tube S1 and the switch tube S4 are turned off. At this time, the inductor L1 releases the electric energy stored therein to maintain the original loop current size, that is, the current of the inductor L1 returns to the inductor L1 through the first and second ends of the first output unit, the capacitor C2 and the diode D1, and the current output by the inductor L1 gradually decreases, so that the voltage on the first output unit gradually decreases. Please refer to Figure 5 In the figure, the voltage change of the top waveform in the T2 stage;

[0065] Correspondingly, the inductor L4 releases the electric energy stored therein to maintain the original loop current size, that is, the current in the inductor L4 returns to the inductor L4 through the diode D4, the capacitor C7, the second end and the first end of the second output unit, and the current output by the inductor L4 gradually decreases, so that the voltage on the second output unit gradually decreases. Please refer to Figure 5 In the figure, the voltage change of the waveform in the middle during the T2 stage;

[0066] In the preset time period T3, the switch tube S2 and the switch tube S3 are turned on. The working principles thereof can refer to the working of the switch tube S4 and the switch tube S1 in the first preset time period respectively. The voltage changes of the first output unit and the second output unit caused by the above waveform and the middle waveform in the T3 stage can refer to FIG5 respectively.

[0067] In the preset time period T4, the switch tube S2 and the switch tube S3 are turned off, and the inductor L2 and the inductor L3 are used to maintain the current output. The working principle thereof can refer to the working of the switch tube S4 and the switch tube S1 in the preset time period T2, respectively. The voltage changes of the first output unit and the second output unit caused by the switching tube S2 and the switch tube S3 can refer to Figure 5 In the figure, the voltage changes of the waveform at the top and the waveform at the middle during the T4 stage;

[0068] Through the above arrangement, the DC power output by the power input unit can be subjected to split-phase inversion, so that it outputs two AC power supplies in anti-phase arrangement.

[0069] The present invention also provides another embodiment, please refer to Figure 2 As shown, the difference from the above embodiment is that in this embodiment, an equivalent parasitic capacitor C3 is connected in parallel to the diode D1, and an equivalent parasitic capacitor C5 is connected in parallel to the diode D3.

[0070] Through this setting, since at the beginning of the preset time period T3, the current passing through the inductor L1 has gradually decreased to 0, the current in the diode D1 is naturally turned off without reverse recovery loss. At this time, as the switch tube S2 is turned on, the above-mentioned equivalent parasitic capacitance C3 and the inductor L1 produce natural oscillations, and the voltage on the switch tube S1 is increased, so that the switch tube S1 works in the DCMB mode. At this time, the switch tube S1 is in a critically turned-on state. When it is in the preset time period T1 and the switch tube S1 needs to be turned on, since the switch tube S1 is in a critically turned-on state, it is not necessary to provide a turn-on voltage for the switch tube S1, thereby realizing zero-voltage turning-on of the switch tube S1, so as to improve the operation efficiency of the circuit;

[0071] Correspondingly, the equivalent parasitic capacitor C5 can generate natural oscillation with the inductor L3 when the switch tube S3 is turned off and the current flowing through the inductor L3 is zero, and after the switch tube S4 is turned on, to increase the voltage on the switch tube S3, so that the switch tube S3 is in a critical open state, thereby achieving zero voltage turn-on of the subsequent switch tube S3.

[0072] Furthermore, an equivalent parasitic capacitor C4 is connected in parallel to the switch tube S2, and an equivalent parasitic capacitor C6 is connected in parallel to the switch tube S4.

[0073] Similarly, through this setting, the above-mentioned equivalent parasitic capacitor C4 can generate natural oscillation with the inductor L2 during the period when the switch tube S2 is turned off, and when the current flowing through the inductor L2 is 0, and after the switch tube S1 is turned on, it can increase the voltage on the switch tube S2, so that the switch tube S2 is in a critical open state, and the subsequent zero voltage opening of the switch tube S2 is achieved.

[0074] Correspondingly, when the switch tube S4 is turned off and the current flowing through the inductor L4 is zero, and the switch tube S3 is turned on, the equivalent parasitic capacitor C6 can generate natural oscillation with the inductor L4 to increase the voltage on the switch tube S4, so that the switch tube S4 is in a critical open state, thereby achieving zero voltage turn-on of the subsequent switch tube S4.

[0075] Specifically, the switch tube S1, the switch tube S2, the switch tube S3 and the switch tube S4 are all MOS tubes, and the gate end of each MOS tube is connected to a controller that controls its opening and closing. The controller outputs a control signal to realize that the switch tube S1 and the switch tube S4 are turned on at the beginning of the preset time period T1 and turned off at the end of the preset time period T1, and the switch tube S2 and the switch tube S3 are turned on at the beginning of the preset time period T3 and turned off at the end of the preset time period T3.

[0076] Furthermore, the inductor L1 and the inductor L2 form a group of coupled inductors, and this arrangement can reduce the number of corresponding power devices and reduce the manufacturing cost of the circuit.

[0077] Correspondingly, the inductor L3 and the inductor L4 are also a group of coupled inductors, so as to reduce the number of corresponding power devices and reduce the manufacturing cost of the circuit.

[0078] Furthermore, the first output unit includes a first output capacitor Co and a filtering unit, wherein:

[0079] The two ends of the first output capacitor Co are the first end and the second end of the first output unit, respectively. Figure 2 As shown, the upper end of the first output capacitor Co is the first end of the first output unit, the lower end of the first output capacitor Co is the second end of the first output unit, and the two ends of the first output capacitor Co are also connected to the filtering unit. Using the filtering unit, the voltage output on the first output capacitor Co can be filtered to obtain an alternating current signal with a smoother waveform.

[0080] Specifically, the filtering unit includes an inductor Lf and a capacitor Cf, wherein one end of the first output capacitor Co is connected to the other end of the first output capacitor Co via the inductor Lf and the capacitor Cf in sequence.

[0081] Of course, the second output unit also includes a second output capacitor Co', and another filter unit composed of an inductor Lf' and a capacitor Cf'. The two ends of the second output capacitor Co' are respectively the first end and the second end of the second output unit. Figure 1 As shown, the upper end of the second output capacitor Co′ is the first end of the second output unit, the lower end of the second output capacitor Co′ is the second end of the second output unit, and the upper end of the second output capacitor Co′ is connected to the lower end of the second output capacitor Co′ through the inductor Lf′ and the capacitor Cf′ in sequence.

[0082] The present invention also provides a split-phase inverter, comprising one of the split-phase inverter circuits mentioned above.

[0083] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A split-phase inverter circuit, characterized in that: include: A power input unit, a first output unit, a second output unit, and a first unidirectional inverter unit and a second unidirectional inverter unit that differ in output phase by 180°, wherein the power input unit is connected to the first output unit via the first unidirectional inverter unit, and the power input unit is connected to the second output unit via the second unidirectional inverter unit, wherein: The first unidirectional inverter unit includes a first bridge arm and a second bridge arm; The first bridge arm comprises a switch tube S1, an inductor L1 and a diode D1, the positive electrode of the power input unit is sequentially connected to the first end of the first output unit through the switch tube S1 and the inductor L1, the second end of the first output unit is connected to the negative electrode of the power input unit through the capacitor C2, and the negative electrode of the power input unit is also sequentially connected to the first end of the first output unit through the anode and cathode of the diode D1 and the inductor L1; The second bridge arm has a switch tube S2, an inductor L2 and a diode D2, the positive electrode of the power input unit is connected to the second end of the first output unit through the capacitor C1, the first end of the first output unit is connected to the negative electrode of the power input unit through the inductor L2 and the switch tube S2 in sequence, and the first end of the first output unit is also connected to the second end of the first output unit through the inductor L2, the anode and cathode of the diode D2, and the capacitor C1 in sequence; The second unidirectional inverter unit includes a third bridge arm and a fourth bridge arm; The third bridge arm comprises a switch tube S3, an inductor L3 and a diode D3, the positive electrode of the power input unit is sequentially connected to the first end of the second output unit through the switch tube S3 and the inductor L3, the second end of the second output unit is connected to the negative electrode of the power input unit through the capacitor C8, and the negative electrode of the power input unit is also sequentially connected to the first end of the second output unit through the anode and cathode of the diode D3 and the inductor L3; The fourth bridge arm has a switch tube S4, an inductor L4 and a diode D4, the positive electrode of the power input unit is connected to the second end of the second output unit through the capacitor C7, the first end of the second output unit is connected to the negative electrode of the power input unit through the inductor L4 and the switch tube S4 in sequence, and the first end of the second output unit is also connected to the second end of the second output unit through the inductor L4, the anode and cathode of the diode D4 and the capacitor C7 in sequence; The switch tube S1 and the switch tube S4 are configured to be turned on synchronously in a first time period, and the switch tube S2 and the switch tube S3 are configured to be turned on synchronously in a second time period, so as to invert the voltage output by the power input unit.

2. A split-phase inverter circuit according to claim 1, characterized in that: An equivalent parasitic capacitor C3 is connected in parallel to the diode D1, and an equivalent parasitic capacitor C5 is connected in parallel to the diode D3.

3. A split-phase inverter circuit according to claim 2, characterized in that: An equivalent parasitic capacitor C4 is connected in parallel to the switch tube S2, and an equivalent parasitic capacitor C6 is connected in parallel to the switch tube S4.

4. A split-phase inverter circuit according to claim 1, characterized in that: The switch tube S1 , the switch tube S2 , the switch tube S3 and the switch tube S4 are all MOS tubes, and the gate end of each MOS tube is connected to a controller for controlling the switching thereof.

5. The split-phase inverter circuit according to claim 1, characterized in that: The inductor L1 and the inductor L2 form a set of coupled inductors.

6. The split-phase inverter circuit according to claim 1, characterized in that: The inductor L3 and the inductor L4 form a set of coupled inductors.

7. The split-phase inverter circuit according to claim 1, characterized in that: The first output unit includes a first output capacitor Co and a filtering unit, wherein: Two ends of the first output capacitor Co are respectively the first end and the second end of the first output unit, and the two ends of the first output capacitor Co are also connected to the filtering unit.

8. A split-phase inverter circuit according to claim 7, characterized in that: The filtering unit includes an inductor Lf and a capacitor Cf, wherein one end of the first output capacitor Co is connected to the other end of the first output capacitor Co via the inductor Lf and the capacitor Cf in sequence.

9. A split-phase inverter, characterized in that: It comprises a split-phase inverter circuit as described in any one of claims 1 to 8.

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