Inverter circuit and inverter

Abstract

The invention discloses an inverter circuit and an inverter, which are applied to the field of inverter circuits, the inverter circuit comprises a first capacitor, a second capacitor, a plurality of PIM units and an inverter inductance module, the first capacitor and the second capacitor are used for balancing the voltage of a neutral point of a direct current power supply, the plurality of PIM units are respectively composed of a first main switch, a first auxiliary switch, a first clamping switch, a second main switch, a second auxiliary switch and a second clamping switch, the plurality of PIM units are used for converting direct current into alternating current, and the inversion inductance module is used for inhibiting switching ring current at the output ends of the PIM units. Therefore, the direct current is converted into the alternating current by utilizing a plurality of PIM units consisting of the first main switch, the first auxiliary switch, the first clamping switch, the second main switch, the second auxiliary switch and the second clamping switch, the commutation path of a switch single tube is short, and the stray inductance is small, so that the stress and the turn-off loss of peak voltage are reduced; and the reliability and the efficiency of the inverter circuit are improved.

Description

Technical Field

[0001] The present invention relates to the field of inverter circuits, and in particular to an inverter circuit and an inverter. Background Art

[0002] Cost reduction is the eternal theme of photovoltaic / energy storage inverters, and high power is one of the important ways to achieve cost reduction. From the perspective of photovoltaic inverters, high power can significantly reduce unit costs. For example, high-power inverters have lower prices than low-power inverters, and can reduce the costs of other systems in photovoltaic power stations (such as cables, transportation and installation systems, etc.). High-power photovoltaic / energy storage inverters usually use IGBT (Insulate-Gate Bipolar Transistor) integrated modules. IGBT integrated modules are usually ANPC (Active Neutral Point Clamped) topology or NPC (Neutral Point Clamped) topology, and only one IGBT integrated module is required for each phase. The advantage of this implementation method is that the PCB layout is simple, and the disadvantages are also obvious: first, the cost is very high. The cost of IGBT integrated modules is about 3 times that of TO-247 single tubes; second, the commutation path is long (IGBT module is very large), the stray inductance is large, and the peak voltage stress of IGBT integrated modules is high. Summary of the invention

[0003] The object of the present invention is to provide an inverter circuit and an inverter, which can convert direct current into alternating current by using a plurality of PIM units consisting of a first main switch, a first auxiliary switch, a first clamping switch, a second main switch, a second auxiliary switch and a second clamping switch, wherein the cost of a single switch tube is low, and the commutation path of the single switch tube in the PIM unit is short and the stray inductance is small, thereby reducing the stress of the peak voltage and the turn-off loss, and improving the reliability and efficiency of the inverter circuit.

[0004] In order to solve the above technical problems, the present invention provides an inverter circuit, comprising a first capacitor, a second capacitor, a plurality of PIM units and an inverter inductor module;

[0005] The first capacitor and the second capacitor are connected in series, and one end of the series connection is connected to the positive electrode of the DC power supply, and the other end of the series connection is connected to the negative electrode of the DC power supply. The common end of the series connection is the neutral point of the DC power supply, and the first capacitor and the second capacitor are used to balance the voltage of the neutral point of the DC power supply;

[0006] The plurality of PIM units are each composed of a first main switch, a first auxiliary switch, a first clamp switch, a second main switch, a second auxiliary switch, and a second clamp switch. The first end of the first main switch is connected to the positive electrode of the DC power supply. The second end of the first main switch is connected to a common end of the first end of the first auxiliary switch and the first end of the first clamp switch. The second end of the first auxiliary switch is connected to the second end of the second auxiliary switch, and the connected common end is connected to the first end of the inverter inductor module. The second end of the first clamp switch is connected to the second end of the second clamp switch, and the connected common end is the neutral point of the PIM unit. The neutral point of the PIM unit is connected to the neutral point of the DC power supply. The first end of the second clamp switch is connected to the first end of the second auxiliary switch and the second end of the second main switch. The first end of the second main switch is connected to the negative electrode of the DC power supply. The plurality of PIM units are used to convert DC power into AC power.

[0007] The inverter inductor module includes multiple inverter inductors, the first ends of the multiple inverter inductors are respectively connected to the output ends of the multiple PIM units, and the second ends of the multiple inverter inductors are all connected to the power grid, so as to suppress the switching circulation current at the output end of the PIM unit, wherein the number of the inverter inductors is consistent with the number of the PIM units.

[0008] Optionally, it also includes multiple current-sharing inductors, which are respectively arranged between the first main switch and the positive pole of the DC power supply or between the second main switch and the negative pole of the DC power supply, wherein the number of the current-sharing inductors is twice the number of the PIM units.

[0009] Optionally, the current-sharing inductor includes a single-turn coil and a magnetic ring, and the single-turn coil passes through the magnetic ring.

[0010] Optionally, it further includes multiple capacitor modules, which are respectively connected in parallel with the multiple PIM units in a one-to-one correspondence, and the neutral points of the multiple capacitor modules are all connected to the neutral point of the DC power supply. The number of the capacitor modules is consistent with the number of the PIM units.

[0011] Optionally, the capacitor module includes a first absorption capacitor and a second absorption capacitor, the first absorption capacitor and the second absorption capacitor are connected in series, and the series connection is connected in parallel with the PIM unit, the common end after the series connection is the neutral point of the capacitor module, and the neutral point of the capacitor module is connected to the neutral point of the DC power supply.

[0012] Optionally, the inverter inductor module includes multiple inverter inductors, the first ends of the multiple inverter inductors are respectively connected to the multiple PIM units, and the second ends of the multiple inverter inductors are all connected to the power grid, wherein the number of the inverter inductors is consistent with the number of the PIM units.

[0013] Optionally, the inverter inductor includes a coil and a magnetic core, and the coil is arranged on the periphery of the magnetic core.

[0014] Optionally, the first main switch, the first auxiliary switch, the first clamping switch, the second main switch, the second auxiliary switch and the second clamping switch are all single IGBT tubes.

[0015] Optionally, multiple resistors are included, and the gate and source of the IGBT are each connected in series with one resistor, wherein the number of the resistors is twice the number of the IGBT.

[0016] The present invention also provides an inverter, comprising three inverter circuits as described above, wherein the DC ends of the three inverter circuits are all connected to a DC power supply, and the AC ends of the three inverter circuits are respectively connected to the A phase, B phase and C phase of the power grid in a one-to-one correspondence.

[0017] The present application provides an inverter circuit and an inverter, the inverter circuit includes a first capacitor, a second capacitor, a plurality of PIM units and an inverter inductor module, wherein the first capacitor and the second capacitor are used to balance the voltage of the neutral point of the DC power supply, the plurality of PIM units are composed of a first main switch, a first auxiliary switch, a first clamp switch, a second main switch, a second auxiliary switch and a second clamp switch, the plurality of PIM units are used to convert DC power into AC power, and the inverter inductor module is used to suppress the switch circulation at the output end of the PIM unit. It can be seen that the present application uses a plurality of PIM units composed of a first main switch, a first auxiliary switch, a first clamp switch, a second main switch, a second auxiliary switch and a second clamp switch to convert DC power into AC power, the cost of a single switch is low, and the commutation path of the single switch in the PIM unit is short, and the stray inductance is small, thereby reducing the stress of the peak voltage and the turn-off loss, and improving the reliability and efficiency of the inverter circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the prior art and the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 A schematic diagram of an inverter circuit provided by the present invention;

[0020] Figure 2 A schematic diagram of a specific inverter circuit provided by the present invention;

[0021] Figure 3 A partial schematic diagram of a method for adjusting the speed at which an IGBT single tube is turned on or off provided by the present invention. DETAILED DESCRIPTION

[0022] The core of the present invention is to provide an inverter circuit and an inverter, which can convert direct current into alternating current by using a plurality of PIM (Power Integrated Module) units consisting of a first main switch, a first auxiliary switch, a first clamping switch, a second main switch, a second auxiliary switch and a second clamping switch. The cost of a single switch tube is low, and the commutation path of the single switch tube in the PIM unit is short and the stray inductance is small, thereby reducing the stress of the peak voltage and the turn-off loss, and improving the reliability and efficiency of the inverter circuit.

[0023] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] High-power photovoltaic / energy storage inverters usually use IGBT integrated modules, which are usually ANPC topology or NPC topology, and only one IGBT integrated module is needed for each phase. The advantage of this implementation method is that the PCB layout is simple, but the disadvantages are also obvious: first, the cost is very high, and the cost of IGBT integrated modules is about three times that of TO-247 single tube; second, the commutation path is long (IGBT module is very large), the stray inductance is large, and the peak voltage stress of IGBT integrated modules is high.

[0025] In order to solve the above technical problems, the present invention provides an inverter circuit.

[0026] For details, see Figure 1 As shown, Figure 1 A schematic diagram of an inverter circuit provided by the present invention, wherein the present application takes three PIM units as an example, and the three PIM units are PIM1, PIM2 and PIM3 respectively.

[0027] The inverter circuit includes a first capacitor C1, a second capacitor C2, a plurality of PIM units and an inverter inductor module LA.

[0028] The first capacitor C1 and the second capacitor C2 are connected in series, and one end of the series connection is connected to the positive electrode of the DC power supply DC, and the other end of the series connection is connected to the negative electrode of the DC power supply DC. The common end of the series connection is the neutral point N of the DC power supply DC. The first capacitor C1 and the second capacitor C2 are used to balance the voltage of the neutral point N of the DC power supply DC.

[0029] Each PIM unit is composed of a first main switch, a first auxiliary switch, a first clamping switch, a second main switch, a second auxiliary switch and a second clamping switch. Figure 1 As shown, the first main switch in PIM1 is Q11, the first auxiliary switch in PIM1 is Q12, the first clamping switch in PIM1 is Q13, the second main switch in PIM1 is Q14, the second auxiliary switch in PIM1 is Q15, and the second clamping switch in PIM1 is Q16; the first main switch in PIM2 is Q21, the first auxiliary switch in PIM2 is Q22, the first clamping switch in PIM2 is Q23, the second main switch in PIM2 is Q24, the second auxiliary switch in PIM2 is Q25, and the second clamping switch in PIM2 is Q26; the first main switch in PIM3 is Q31, the first auxiliary switch in PIM3 is Q32, the first clamping switch in PIM3 is Q33, the second main switch in PIM3 is Q34, the second auxiliary switch in PIM3 is Q35, and the second clamping switch in PIM3 is Q36.

[0030] The first end of the first main switch Q11 in PIM1 is connected to the positive electrode of the DC power supply DC, the second end of the first main switch Q11 in PIM1 is connected to the common end of the first end of the first sub-switch Q12 in PIM1 and the first end of the first clamp switch Q13 in PIM1, the second end of the first sub-switch Q12 in PIM1 is connected to the second end of the second sub-switch Q15 in PIM1, and the connected common end is connected to the first end of the inverter inductor module LA, the second end of the first clamp switch Q13 in PIM1 is connected to the second end of the second clamp switch Q16 in PIM1, and the connected common end is the neutral point of the PIM unit, the neutral point of the PIM unit is connected to the neutral point N of the DC power supply DC, the first end of the second clamp switch Q16 in PIM1 is connected to the first end of the second sub-switch Q15 in PIM1 and the second end of the second main switch Q14 in PIM1, the first end of the second main switch Q14 in PIM1 is connected to the negative electrode of the DC power supply DC, and the multiple PIM units are used to convert DC power into AC power.

[0031] The inverter inductor module LA includes multiple inverter inductors, the first ends of the multiple inverter inductors are respectively connected to the output ends of the multiple PIM units, and the second ends of the multiple inverter inductors are all connected to the power grid AC, which is used to suppress the switching circulation current at the output end of the PIM unit, wherein the number of inverter inductors is consistent with the number of PIM units.

[0032] The inverter circuit includes a first capacitor C1, a second capacitor C2, a plurality of PIM units and an inverter inductor module LA. The present application takes three PIM units as an example, and the three PIM units are PIM1, PIM2 and PIM3, wherein each PIM unit is composed of a first main switch, a first auxiliary switch, a first clamping switch, a second main switch, a second auxiliary switch and a second clamping switch. Figure 1 As shown, the first main switch in PIM1 is Q11, the first auxiliary switch in PIM1 is Q12, the first clamping switch in PIM1 is Q13, the second main switch in PIM1 is Q14, the second auxiliary switch in PIM1 is Q15, and the second clamping switch in PIM1 is Q16; the first main switch in PIM2 is Q21, the first auxiliary switch in PIM2 is Q22, the first clamping switch in PIM2 is Q23, the second main switch in PIM2 is Q24, the second auxiliary switch in PIM2 is Q25, and the second clamping switch in PIM2 is Q26; the first main switch in PIM3 is Q31, the first auxiliary switch in PIM3 is Q32, the first clamping switch in PIM3 is Q33, the second main switch in PIM3 is Q34, the second auxiliary switch in PIM3 is Q35, and the second clamping switch in PIM3 is Q36. The inverter circuit is applied to high-power photovoltaic / energy storage inverters. Multiple PIM units are hard-connected in parallel without staggered parallel control, which can reduce the complexity of the inverter circuit and reduce the manufacturing cost.

[0033] Specifically, the first capacitor C1 and the second capacitor C2 are connected in series, and one end of the series connection is connected to the positive electrode of the DC power supply DC, and the other end of the series connection is connected to the negative electrode of the DC power supply DC, and the common end of the series connection is the neutral point N of the DC power supply DC. A first end of the first main switch Q11 in PIM1 is connected to the positive electrode of the direct current power source DC, a second end of the first main switch Q11 in PIM1 is connected to a common end of a first end of a first sub-switch Q12 in PIM1 and a first end of a first clamp switch Q13 in PIM1, a second end of the first sub-switch Q12 in PIM1 is connected to a second end of a second sub-switch Q15 in PIM1, and the connected common end is connected to a first end of the inverter inductor module LA as an output end of PIM1, a second end of the first clamp switch Q13 in PIM1 is connected to a second end of a second clamp switch Q16 in PIM1, and the connected common end is a neutral point of PIM1, the neutral point of PIM1 is connected to a neutral point N of the direct current power source DC, a first end of the second clamp switch Q16 in PIM1 is connected to a first end of a second sub-switch Q15 in PIM1 and a second end of a second main switch Q14 in PIM1, and a first end of the second main switch Q14 in PIM1 is connected to a negative electrode of the direct current power source DC; A first end of the first main switch Q21 in PIM2 is connected to the positive electrode of the DC power supply DC, a second end of the first main switch Q21 in PIM2 is connected to a common end of a first end of a first sub-switch Q22 in PIM2 and a first end of a first clamp switch Q23 in PIM2, a second end of the first sub-switch Q22 in PIM2 is connected to a second end of a second sub-switch Q25 in PIM2, and the connected common end is connected to a first end of the inverter inductor module LA as an output end of PIM2, a second end of the first clamp switch Q23 in PIM2 is connected to a second end of a second clamp switch Q26 in PIM2, and the connected common end is a neutral point of PIM2, the neutral point of PIM2 is connected to a neutral point N of the DC power supply DC, a first end of the second clamp switch Q26 in PIM2 is connected to a first end of a second sub-switch Q25 in PIM2 and a second end of a second main switch Q24 in PIM2, and a first end of the second main switch Q24 in PIM2 is connected to a negative electrode of the DC power supply DC;The first end of the first main switch Q31 in PIM3 is connected to the positive electrode of the DC power supply DC, the second end of the first main switch Q31 in PIM3 is connected to the common end of the first end of the first sub-switch Q32 in PIM3 and the first end of the first clamp switch Q33 in PIM3, the second end of the first sub-switch Q32 in PIM3 is connected to the second end of the second sub-switch Q35 in PIM3, and the connected common end is connected to the first end of the inverter inductor module LA as the output end of PIM3, the second end of the first clamp switch Q33 in PIM3 is connected to the second end of the second clamp switch Q36 in PIM3, and the connected common end is the neutral point of PIM3, the neutral point of PIM3 is connected to the neutral point N of the DC power supply DC, the first end of the second clamp switch Q36 in PIM3 is connected to the first end of the second sub-switch Q35 in PIM3 and the second end of the second main switch Q34 in PIM3, and the first end of the second main switch Q34 in PIM3 is connected to the negative electrode of the DC power supply DC. The second end of the inverter inductor module LA is connected to the power grid AC, and is used to suppress the switch circulation current on the power grid AC side. ;

[0034] In addition, the inverter inductor module LA includes a plurality of inverter inductors, the number of which is consistent with the number of PIM units, the number of PIM units is 3, the number of inverter inductors is 3, and the three inverter inductors are respectively a first inverter inductor LA1, a second inverter inductor LA2, and a third inverter inductor LA3. Among them, the first inverter inductor LA1, the second inverter inductor LA2, and the third inverter inductor LA3 can share a magnetic core, or can be packaged separately. Specifically, the first end of the first inverter inductor LA1 is connected to the output end of PIM1, the first end of the second inverter inductor LA2 is connected to the output end of PIM2, the first end of the third inverter inductor LA3 is connected to the output end of PIM3, and the second ends of the first inverter inductor LA1, the second inverter inductor LA2, and the third inverter inductor LA3 are all connected to the power grid AC, which can effectively suppress the high-frequency switch circulation current generated on the AC side when the switch single tubes in PIM1, PIM2, and PIM3 are turned on and off.

[0035] It should be noted that three PIM units are used to convert the DC power of the DC power supply DC into AC power. Each PIM unit includes six switch tubes. The commutation of the six switch tubes only needs to be performed in their respective PIM units. Since the size of the PIM unit is small, the length of the leads welded between the six switch tubes will be greatly reduced, and the stray inductance will be reduced. This can not only reduce the stress of the peak voltage of the switch tube, but also reduce the turn-off loss of the switch tube, thereby improving the conversion efficiency of the photovoltaic / energy storage inverter.

[0036] In addition, the inverter circuit can be applied to a single-phase system or a three-phase system. If the inverter circuit is applied to a three-phase system, three inverter circuits are required. The DC ends of the three inverter circuits are all connected to a DC power supply DC, and the AC ends of the three inverter circuits are respectively connected to phase A, phase B, and phase C of the three-phase system.

[0037] It can be seen that the present embodiment utilizes three PIM units consisting of a first main switch, a first auxiliary switch, a first clamping switch, a second main switch, a second auxiliary switch, and a second clamping switch to convert direct current into alternating current. The cost of a single switch is low, and the commutation path of the switch in the PIM unit is short and the stray inductance is small, thereby reducing the stress of the peak voltage and the turn-off loss, and improving the reliability and efficiency of the inverter circuit.

[0038] Based on the above embodiments:

[0039] For details, see Figure 2 As shown, Figure 2 A schematic diagram of a specific inverter circuit provided by the present invention.

[0040] As an optional embodiment, it also includes multiple current-sharing inductors, which are respectively arranged between the first main switch and the positive pole of the DC power supply DC or between the second main switch and the negative pole of the DC power supply DC, wherein the number of the current-sharing inductors is twice the number of the PIM units.

[0041] Theoretically, the PWM drive pulses of the PIM unit are completely synchronized, and there is no instantaneous potential difference on the DC side, so there is no circulation problem. However, due to the differences in the switch tubes themselves, the actual PWM drive pulses cannot be completely synchronized. When the switch tubes are turned on and off, high-frequency switch circulation will be generated on the DC side, thereby damaging the equipment. In order to suppress the high-frequency switch circulation of the PIM unit on the DC side, this embodiment sets a current-sharing inductor between the first main switch and the positive electrode of the DC power supply DC and between the second main switch and the negative electrode of the DC power supply DC. The number of current-sharing inductors is twice the number of PIM units. The number of PIM units is 3, and the number of current-sharing inductors is 6. The 6 current-sharing inductors are the first current-sharing inductor L1, the second current-sharing inductor L2, the third current-sharing inductor L3, the fourth current-sharing inductor L4, the fifth current-sharing inductor L5, and the sixth current-sharing inductor L6.

[0042] Among them, the first end of the first current sharing inductor L1 is connected to the positive electrode of the direct current power supply DC, the second end of the first current sharing inductor L1 is connected to the first end of the first main switch Q11 in PIM1, the first end of the second current sharing inductor L2 is connected to the negative electrode of the direct current power supply DC, the second end of the second current sharing inductor L2 is connected to the first end of the second main switch Q14 in PIM1, and the first current sharing inductor L1 and the second current sharing inductor L2 can suppress the high-frequency switching circulation of PIM1 on the DC side; the first end of the third current sharing inductor L3 is connected to the positive electrode of the direct current power supply DC, the second end of the third current sharing inductor L3 is connected to the first end of the first main switch Q21 in PIM2, and the first end of the fourth current sharing inductor L4 is connected to the direct current power supply DC. The first end of the fifth current balancing inductor L5 is connected to the positive electrode of the DC power supply DC, the second end of the fifth current balancing inductor L5 is connected to the first end of the first main switch Q31 in PIM3, the first end of the sixth current balancing inductor L6 is connected to the negative electrode of the DC power supply DC, the second end of the sixth current balancing inductor L6 is connected to the first end of the second main switch Q34 in PIM3, and the fifth current balancing inductor L5 and the sixth current balancing inductor L6 can suppress the high-frequency switching circulation of PIM3 on the DC side.

[0043] It can be seen that in this embodiment, current-sharing inductors are arranged between the PIM unit and the positive electrode of the DC power supply DC and between the PIM unit and the negative electrode of the DC power supply DC, which can suppress the high-frequency switching circulation current of the PIM unit on the DC side and improve the reliability and efficiency of the inverter circuit.

[0044] As an optional embodiment, the current sharing inductor includes a single-turn coil and a magnetic ring, and the single-turn coil passes through the magnetic ring.

[0045] Considering the economical efficiency, this embodiment uses a single-turn coil passing through a magnetic ring as a current-sharing inductor, and the current-sharing inductor is connected to the first main switch, the positive pole of the DC power supply DC or the second main switch, the negative pole of the DC power supply DC at both ends of the single-turn coil, which can absorb and suppress high-frequency current fluctuations and effectively suppress the high-frequency switching circulating current of the PIM unit on the DC side. The single-turn coil has a simple structure and does not require a complex winding process, which reduces the manufacturing cost to a certain extent. The single-turn coil is small in size and is suitable for applications with limited space.

[0046] It can be seen that this embodiment uses a single-turn coil passing through a magnetic ring as a current-sharing inductor, which can effectively suppress the high-frequency switching circulating current of the PIM unit on the DC side, and while improving the reliability and efficiency of the inverter circuit, it also improves the economy of the inverter circuit to a certain extent.

[0047] As an optional embodiment, it also includes multiple capacitor modules, which are connected in parallel with multiple PIM units one by one, and the neutral points of the multiple capacitor modules are connected to the neutral point N of the DC power supply DC. The number of capacitor modules is consistent with the number of PIM units.

[0048] Theoretically, the PWM drive pulses of the PIM unit are completely synchronized, and there is no instantaneous potential difference on the DC side, so there is no circulation problem. However, due to the differences in the switch tubes themselves, the actual PWM drive pulses cannot be completely synchronized. When the switch tubes are turned on and off, spike voltages will be generated, which will cause semiconductor devices to be overloaded, overheated, or even breakdown. These problems will seriously affect the service life and reliability of the device, and may even cause permanent damage to the device. In order to suppress the spike voltage generated when the switch tube is turned on and off, the present embodiment connects a capacitor module in parallel on the DC side of each PIM unit. The capacitor module can effectively absorb the spike voltage and improve the reliability and stability of the inverter circuit.

[0049] It should be noted that the number of capacitor modules is consistent with the number of PIM units, the number of PIM units is 3, the number of capacitor modules is 3, and the 3 capacitor modules are respectively a first absorption capacitor module, a third capacitor module and a third capacitor module.

[0050] It can be seen that in this embodiment, a capacitor module is connected in parallel on the DC side of each PIM unit. The capacitor module can effectively absorb the peak voltage and improve the reliability of the inverter circuit.

[0051] As an optional embodiment, the capacitor module includes a first absorption capacitor and a second absorption capacitor. The first absorption capacitor and the second absorption capacitor are connected in series and connected in parallel with the PIM unit after the series connection. The common end after the series connection is the neutral point of the capacitor module, and the neutral point of the capacitor module is connected to the neutral point N of the DC power supply DC.

[0052] Specifically, this embodiment uses the first absorption capacitor and the second absorption capacitor as the capacitor module. The first absorption capacitor and the second absorption capacitor have the characteristic of storing charge. When a peak voltage occurs, the first absorption capacitor and the second absorption capacitor will absorb excess charge, thereby reducing the amplitude of the peak voltage.

[0053] Each capacitor module is composed of a first absorption capacitor and a second absorption capacitor. Figure 2 As shown, the three capacitor modules include a first absorption capacitor Cs11 and a second absorption capacitor Cs12 in the first capacitor module, a first absorption capacitor Cs21 and a second absorption capacitor Cs22 in the second capacitor module, and a first absorption capacitor Cs31 and a second absorption capacitor Cs32 in the third capacitor module.

[0054] It can be seen that this embodiment uses the first absorption capacitor and the second absorption capacitor as the capacitor module. When a peak voltage occurs, the first absorption capacitor and the second absorption capacitor will absorb excess charge, thereby reducing the amplitude of the peak voltage, achieving the effect of absorbing the peak voltage and improving the reliability of the inverter circuit.

[0055] As an optional embodiment, the inverter inductor includes a coil and a magnetic core, and the coil is arranged on the periphery of the magnetic core.

[0056] In this embodiment, the coil is arranged on the periphery of the magnetic core as an inverter inductor. The saturation characteristics of the magnetic core can saturate the magnetic core when the current flows normally, thereby reducing the inductance value; when the current flows in the reverse direction, the magnetic core will quickly generate a large reverse electromotive force, and the coil can quickly generate a reverse voltage to prevent sudden changes in the current, thereby effectively suppressing the high-frequency switching circulation generated on the AC side when the single switch is turned on and off.

[0057] It can be seen that in this embodiment, the coil is arranged on the periphery of the magnetic core as an inverter inductor, which can prevent the sudden change of current when the current flows in the reverse direction, thereby effectively suppressing the high-frequency switching circulation generated on the AC side when the single switch is turned on and off.

[0058] As an optional embodiment, the first main switch, the first auxiliary switch, the first clamping switch, the second main switch, the second auxiliary switch and the second clamping switch are all single IGBT tubes.

[0059] In order to improve the reliability and efficiency of the inverter circuit, this embodiment uses an IGBT single tube as the first main switch, the first auxiliary switch, the first clamp switch, the second main switch, the second auxiliary switch and the second clamp switch. The IGBT single tube combines the high input impedance of MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) and the low conduction loss characteristics of BJT (Bipolar Junction Transistor), and can transmit current with lower energy loss in the on state, thereby improving energy utilization efficiency. The IGBT single tube can specifically be a TO-247 IGBT single tube.

[0060] Among them, the first main switch Q11 in PIM1, the first auxiliary switch Q12 in PIM1, the first clamping switch Q13 in PIM1, the second main switch Q14 in PIM1, the second auxiliary switch Q15 in PIM1 and the second clamping switch Q16 in PIM1 all adopt a single IGBT tube; the first main switch Q21 in PIM2, the first auxiliary switch Q22 in PIM2, the first clamping switch Q23 in PIM2, the second main switch Q24 in PIM2, the second auxiliary switch Q25 in PIM2 and the second clamping switch Q26 in PIM2 all adopt a single IGBT tube; the first main switch Q31 in PIM3, the first auxiliary switch Q32 in PIM3, the first clamping switch Q33 in PIM3, the second main switch Q34 in PIM3, the second auxiliary switch Q35 in PIM3 and the second clamping switch Q36 in PIM3 all adopt a single IGBT tube.

[0061] It can be seen that this embodiment uses an IGBT single tube as the first main switch, the first auxiliary switch, the first clamping switch, the second main switch, the second auxiliary switch and the second clamping switch. The IGBT single tube can transmit current with lower energy loss in the on state, thereby improving energy utilization efficiency.

[0062] As an optional embodiment, a plurality of resistors are further included, and a resistor is connected in series to the gate and source of each IGBT tube, wherein the number of the resistors is twice the number of the IGBT tubes.

[0063] In order to adjust the speed of turning on or off the IGBT, a resistor is connected in series to the gate and source of the IGBT in this embodiment. However, the resistance value of the resistor cannot be too large or too small, because although a smaller resistance value can speed up the turning on or off of the IGBT, it may also increase the current change rate during the turning on or off of the IGBT, which may cause electromagnetic interference problems; on the contrary, although a larger resistance value can slow down the turning on or off of the IGBT and reduce the current change rate during the turning on or off of the IGBT, it may increase the loss of the IGBT when it is turned on or off. For details, please refer to Figure 3 As shown, Figure 3A partial schematic diagram of a method for adjusting the speed of turning on or off an IGBT provided by the present invention. Among them, G1-S1, G2-S2 and G3-S3 can be either synchronous pulses or staggered phase-shifted pulses; the three PIM units are divided into upper and lower bridge arms, which are symmetrical. In this embodiment, the upper bridge arm is taken as an example, and the number of resistors in the upper bridge arm is 18, and the 18 resistors are respectively the first resistor R1, the second resistor R2, the third resistor R3, the fourth resistor R4, the fifth resistor R5, the sixth resistor R6, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9, the tenth resistor R10, the eleventh resistor R11, the twelfth resistor R12, the thirteenth resistor R13, the fourteenth resistor R14, the fifteenth resistor R15, the sixteenth resistor R16, the seventeenth resistor R17 and the eighteenth resistor R18.

[0064] It can be seen that in this embodiment, a resistor is connected in series with the gate and source of the IGBT to adjust the speed at which the IGBT is turned on or off, but the resistance value of the resistor cannot be too large or too small to avoid electromagnetic interference and increase the loss of the IGBT when it is turned on or off.

[0065] The present invention also provides an inverter, comprising three inverter circuits as described above, wherein the DC ends of the three inverter circuits are all connected to a DC power supply DC, and the AC ends of the three inverter circuits are respectively connected to the A phase, B phase and C phase of the power grid AC in a one-to-one correspondence.

[0066] Specifically, if the AC power grid is a three-phase system, three inverter circuits are required, the DC ends of the three inverter circuits are connected to a DC power supply DC, and the AC ends of the three inverter circuits are respectively connected to phase A, phase B, and phase C of the three-phase system.

[0067] In addition, for an introduction to an inverter provided by the present invention, please refer to the above-mentioned embodiment of the inverter circuit, and the present invention will not be described in detail here.

[0068] It can be seen that if the power grid AC is a three-phase system, the present application can adopt three inverter circuits, and the three inverter circuits all use multiple PIM units consisting of a first main switch, a first auxiliary switch, a first clamping switch, a second main switch, a second auxiliary switch and a second clamping switch to convert direct current into alternating current. The cost of a single switch is low, and the commutation path of the switch in the PIM unit is short and the stray inductance is small, thereby reducing the stress of the peak voltage and the turn-off loss, and improving the reliability and efficiency of the inverter.

[0069] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0070] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0071] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An inverter circuit, characterized in that: It includes a first capacitor, a second capacitor, a plurality of PIM units and an inverter inductor module; The first capacitor and the second capacitor are connected in series, and one end of the series connection is connected to the positive electrode of the DC power supply, and the other end of the series connection is connected to the negative electrode of the DC power supply. The common end of the series connection is the neutral point of the DC power supply, and the first capacitor and the second capacitor are used to balance the voltage of the neutral point of the DC power supply; The plurality of PIM units are each composed of a first main switch, a first auxiliary switch, a first clamp switch, a second main switch, a second auxiliary switch, and a second clamp switch. The first end of the first main switch is connected to the positive electrode of the DC power supply. The second end of the first main switch is connected to a common end of the first end of the first auxiliary switch and the first end of the first clamp switch. The second end of the first auxiliary switch is connected to the second end of the second auxiliary switch, and the connected common end is connected to the first end of the inverter inductor module. The second end of the first clamp switch is connected to the second end of the second clamp switch, and the connected common end is the neutral point of the PIM unit. The neutral point of the PIM unit is connected to the neutral point of the DC power supply. The first end of the second clamp switch is connected to the first end of the second auxiliary switch and the second end of the second main switch. The first end of the second main switch is connected to the negative electrode of the DC power supply. The plurality of PIM units are used to convert DC power into AC power. The inverter inductor module includes multiple inverter inductors, the first ends of the multiple inverter inductors are respectively connected to the output ends of the multiple PIM units, and the second ends of the multiple inverter inductors are all connected to the power grid, so as to suppress the switching circulation current at the output end of the PIM unit, wherein the number of the inverter inductors is consistent with the number of the PIM units.

2. The inverter circuit according to claim 1, characterized in that: It also includes multiple current-sharing inductors, which are respectively arranged between the first main switch and the positive electrode of the DC power supply or between the second main switch and the negative electrode of the DC power supply, wherein the number of the current-sharing inductors is twice the number of the PIM units.

3. The inverter circuit according to claim 2, characterized in that: The current-sharing inductor comprises a single-turn coil and a magnetic ring, and the single-turn coil passes through the magnetic ring.

4. The inverter circuit according to claim 1, characterized in that: It also includes multiple capacitor modules, which are respectively connected in parallel with the multiple PIM units in a one-to-one correspondence. The neutral points of the multiple capacitor modules are all connected to the neutral point of the DC power supply. The number of the capacitor modules is consistent with the number of the PIM units.

5. The inverter circuit according to claim 4, characterized in that: The capacitor module includes a first absorption capacitor and a second absorption capacitor, the first absorption capacitor and the second absorption capacitor are connected in series, and the series connection is connected in parallel with the PIM unit, the common end after the series connection is the neutral point of the capacitor module, and the neutral point of the capacitor module is connected to the neutral point of the DC power supply.

6. The inverter circuit according to claim 1, characterized in that: The inverter inductor comprises a coil and a magnetic core, and the coil is arranged on the periphery of the magnetic core.

7. The inverter circuit according to any one of claims 1 to 6, characterized in that: The first main switch, the first auxiliary switch, the first clamping switch, the second main switch, the second auxiliary switch and the second clamping switch are all single IGBT tubes.

8. The inverter circuit according to claim 7, characterized in that: It also includes a plurality of resistors, wherein the gate and the source of the IGBT are each connected in series with one of the resistors, wherein the number of the resistors is twice the number of the IGBT.

9. An inverter, characterized in that: It comprises three inverter circuits as claimed in any one of claims 1 to 8, wherein the DC ends of the three inverter circuits are all connected to a DC power supply, and the AC ends of the three inverter circuits are respectively connected to the A phase, B phase and C phase of the power grid in a one-to-one correspondence.

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