Three-level inverter circuit, converter and power supply equipment

Abstract

The utility model provides a three-level inverter circuit, a converter and a power supply device, belonging to the inverter field, the three-level inverter circuit is provided with a voltage-sharing circuit module, and a voltage-sharing circuit in the voltage-sharing circuit module is connected in parallel with a first outer tube module, a first inner tube module, a second outer tube module or a second inner tube module. Through the voltage-sharing effect of the voltage-sharing circuit, the voltage stress between each inner tube module and each outer tube module can be effectively adjusted, so that the condition of non-uniform voltage division between the inner tube modules and the outer tube modules is improved, thereby solving the problem that the service life of a switching tube is influenced by non-uniform voltage division, and then the normal operation of the inverter is influenced, guaranteeing the stable operation of the inverter, and improving the reliability of the inverter. Therefore, the reliability and the stability of the whole inverter system are improved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to inverter field, especially, relate to a three -level inverter circuit, converter and power supply equipment. BACKGROUND

[0002] In the high -power inverter, because the inner tube module, outer tube module exist difference in the current carrying demand in the circuit, so need to carry out the difference design to the inner tube module, outer tube module.

[0003] However, the difference design can cause the uneven problem of voltage distribution between the inner tube module and the outer tube module, if the voltage exceeds the voltage bearing capacity of the switch tube in the inner tube module and the outer tube module, the switch tube can be damaged, and the normal operation of the inverter is affected. SUMMARY

[0004] Therefore, the utility model discloses a three -level inverter circuit, converter and power supply equipment to solve the uneven voltage distribution between the inner tube module and the outer tube module in the high -power inverter, the problem of affecting the normal operation of the inverter.

[0005] The utility model embodiment first aspect provides a three -level inverter circuit, including DC input module, first outer tube module, first inner tube module, second outer tube module, second inner tube module, voltage sharing circuit module and AC output module;

[0006] The DC input module includes the positive pole of DC bus and the negative pole of DC bus;

[0007] The positive pole of DC bus is connected with the first outer tube module, and the first outer tube module, the first inner tube module, the second outer tube module and the second inner tube module are connected in series, and the connecting point between the first outer tube module and the first inner tube module and the connecting point between the second outer tube module and the second inner tube module are connected with the midpoint of DC bus respectively, and the negative pole of DC bus is connected with the second outer tube module;

[0008] The connecting point between the first inner tube module and the second inner tube module is connected with the AC output module;

[0009] The voltage sharing circuit module includes at least one voltage sharing circuit, and the voltage sharing circuit is connected with the first outer tube module, the first inner tube module, the second outer tube module or the second inner tube module in parallel.

[0010] In some possible implementation manners, the first outer tube module includes a first number of switch tubes connected in parallel, the first inner tube module includes a second number of switch tubes connected in parallel, the first number is different from the second number, and the voltage equalization circuit is connected in parallel with the switch tube in the first outer tube module or the switch tube in the first inner tube module.

[0011] In some possible implementation manners, the first number is greater than the second number, and the voltage equalization circuit is connected in parallel with the switch tube in the first inner tube module.

[0012] In some possible implementation manners, the voltage equalization circuit includes a first voltage equalization branch and a second voltage equalization branch, the first voltage equalization branch is connected in parallel with the second voltage equalization branch, and the first voltage equalization branch and the second voltage equalization branch are both connected in parallel with the switch tube in the first inner tube module.

[0013] The first voltage equalization branch includes a first capacitor, and the second voltage equalization branch includes a first resistor and a second capacitor connected in series.

[0014] In some possible implementation manners, the three-level inverter circuit further includes a first clamping diode and a second clamping diode.

[0015] The negative electrode of the first clamping diode is connected to a connection point between the first outer tube module and the first inner tube module, and the positive electrode of the first clamping diode is connected to the negative electrode of the second clamping diode.

[0016] The positive electrode of the second clamping diode is connected to a connection point between the second inner tube module and the second outer tube module.

[0017] A connection point between the first clamping diode and the second clamping diode is connected to a midpoint of the DC bus.

[0018] In some possible implementation manners, the DC input module further includes a third capacitor and a fourth capacitor.

[0019] The third capacitor is connected between the positive electrode of the DC bus and the midpoint of the DC bus.

[0020] The fourth capacitor is connected between the negative electrode of the DC bus and the midpoint of the DC bus.

[0021] In some possible implementation manners, the three-level inverter circuit further includes a filter module.

[0022] A connection point between the first inner tube module and the second inner tube module is connected to the AC output module through the filter module.

[0023] In some possible implementation manners, the second outer tube module includes a third number of switch tubes connected in parallel, the second inner tube includes a fourth number of switch tubes connected in parallel, the third number is different from the fourth number, and the voltage-sharing circuit is connected in parallel with the switch tube in the second outer tube module or the switch tube in the second inner tube module.

[0024] The utility model embodiment second aspect provides a kind of transformer, including any one three-level inverter circuit described in the first aspect.

[0025] The utility model embodiment third aspect provides a kind of power supply equipment, including the transformer described in the second aspect.

[0026] The three-level inverter circuit, the transformer and the power supply equipment provided in the embodiment are provided with the voltage-sharing circuit module, and the voltage-sharing circuit in the voltage-sharing circuit module is connected in parallel with the first outer tube module, the first inner tube module, the second outer tube module or the second inner tube module. By the voltage-sharing effect of the voltage-sharing circuit, the voltage stress between each inner tube module and outer tube module can be effectively adjusted, so that the uneven voltage distribution between the inner tube module and the outer tube module is improved, thereby solving the problem that the uneven voltage distribution affects the service life of the switch tube and further affects the normal operation of the inverter, ensuring the stable operation of the inverter, thereby improving the reliability and stability of the entire inverter system. In the embodiment, the voltage-sharing circuit module includes at least one voltage-sharing circuit, and this flexible setting mode can select the appropriate number of voltage-sharing circuits according to the actual circuit requirements and power size to meet the voltage-sharing requirements under different working conditions, enhance the adaptability of the circuit to different application scenarios, and improve the versatility of the three-level inverter circuit. BRIEF DESCRIPTION OF DRAWINGS

[0027] To more clearly illustrate the technical solutions in the embodiments of the utility model, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the utility model, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0028] Figure 1 It is a three-level inverter circuit schematic diagram provided by the utility model embodiment;

[0029] Figure 2 It is another three-level inverter circuit schematic diagram provided by the utility model embodiment. DETAILED DESCRIPTION

[0030] In the following description, specific details are set forth such as particular system configurations, techniques, etc., in order to provide a thorough understanding of the embodiments of the present application. However, persons skilled in the art will understand that the present application can be practiced without these specific details. In other instances, well-known methods, procedures, components, circuits, and networks have not been described in detail so as not to unnecessarily obscure aspects of the present application.

[0031] In order to illustrate the technical scheme of the present application, the following will be described by specific embodiments.

[0032] Referring to Figure 1 , Figure 1 is a schematic diagram of a three-level inverter circuit provided by the embodiments of the present application, as shown in Figure 1 , the three-level inverter circuit comprises a DC input module 11, a first outer tube module 12, a first inner tube module 13, a second outer tube module 14, a second inner tube module 15, a voltage equalization circuit module 16 and an AC output module 17.

[0033] Among them, the DC input module 11 comprises a positive pole of a DC bus and a negative pole of the DC bus.

[0034] The positive pole of the DC bus is connected to the first outer tube module 12, the first outer tube module 12, the first inner tube module 13, the second outer tube module 14 and the second inner tube module 15 are connected in series, the connection points between the first outer tube module 12 and the first inner tube module 13 and the connection points between the second outer tube module 14 and the second inner tube module 15 are respectively connected to the midpoint O of the DC bus, and the negative pole of the DC bus is connected to the second outer tube module 14.

[0035] The three-level inverter circuit can comprise an A-phase bridge arm, a B-phase bridge arm and a C-phase bridge arm, Figure 1 only the A-phase bridge arm is shown by way of example. The first outer tube module 12, the first inner tube module 13, the second outer tube module 14 and the second inner tube module 15 connected in series constitute the A-phase bridge arm, and the connection point between the first inner tube module 13 and the second inner tube module 15 represents the output end of the A-phase bridge arm, and the AC output module 17 is connected.

[0036] Due to the difference in parameters and settings, voltage imbalance may occur between the first outer tube module 12, the first inner tube module 13, the second outer tube module 14 and the second inner tube module. Therefore, the voltage equalization circuit module 16 is provided in the present embodiment, the voltage equalization circuit module 16 comprises at least one voltage equalization circuit, the voltage equalization circuit is connected in parallel with the first outer tube module 12, the first inner tube module 13, the second outer tube module 14 or the second inner tube module 15, and the voltage stress between the inner and outer tube modules is balanced.

[0037] Figure 1The voltage equalization circuit module 16 includes two voltage equalization circuits, and the voltage equalization circuits are connected in parallel with the first inner tube module 13 and the second inner tube module 15, respectively.

[0038] The three-level inverter circuit, the converter and the power supply device provided by the embodiment can effectively adjust the voltage stress between the inner tube modules and the outer tube modules by the voltage equalization effect of the voltage equalization circuit, so that the voltage division imbalance between the inner tube modules and the outer tube modules is improved, thereby solving the problem that the switch tube life is affected due to the voltage division imbalance, and further affecting the normal operation of the inverter, and ensuring the stable operation of the inverter, thereby improving the reliability and stability of the entire inverter system.

[0039] In the high-power inverter, the inner tube modules and the outer tube modules need to be designed differently because of the difference in current carrying demand in the circuit.

[0040] Referring to Figure 2 , Figure 2 The first outer tube module 12 includes a first number of parallelly connected switch tubes, and each switch tube can further include a diode connected in anti-parallel with each switch tube.

[0041] The voltage equalization circuit module 16 includes two voltage equalization circuits, and the voltage equalization circuits are connected in parallel with the first inner tube module 13 and the second inner tube module 15, respectively.

[0042] The first number and the second number are different, so that the voltage stress borne by the switch tubes in the first inner tube module 13 and the switch tubes in the first outer tube module 12 can also be different, and therefore, the first voltage equalization circuit 21 is connected in parallel with the switch tubes in the first outer tube module 12 or the switch tubes in the first inner tube module 13 to balance the voltage stress between the first inner tube module 13 and the first outer tube module 12.

[0043] Because the current carrying demand of the first inner tube module 13 is smaller than that of the first outer tube module 12, the number of parallelly connected switch tubes in the first inner tube module 13 is usually smaller than that in the outer tube module.

[0044] In a feasible implementation, when the switch tubes in the second outer tube module 14 and the second inner tube module 15 are simultaneously turned on, the bus voltage is applied to the switch tubes in the first outer tube module 12 and the first inner tube module 13. At this time, due to the different number of switch tubes in parallel in the first outer tube module 12 and the first inner tube module 13, the impedances are also different, and the first outer tube module 12 and the first inner tube module 13 will appear uneven voltage distribution. If the first number is greater than the second number, the switch tubes in the first inner tube module 13 will bear a larger voltage, which may exceed the carrying capacity of the switch tubes, and then cause the switch tubes to be damaged, affecting the normal operation of the inverter. Therefore, in the embodiment, the first voltage equalization circuit 21 is arranged, the first voltage equalization circuit 21 is connected in parallel with the switch tubes in the first inner tube module 13, the impedance is balanced, the switch tubes in the first outer tube module 12 and the first inner tube module 13 bear the same voltage stress, and safe and reliable operation of the switch tubes in the first outer tube module 12 and the first inner tube module 13 is ensured.

[0045] In a feasible implementation, the first voltage equalization circuit 21 includes a first voltage equalization branch and a second voltage equalization branch, the first voltage equalization branch and the second voltage equalization branch are connected in parallel, and the first voltage equalization branch and the second voltage equalization branch are connected in parallel with the switch tubes in the first inner tube module 13. The first voltage equalization branch includes a first capacitor 211, and the second voltage equalization branch includes a first resistor 212 and a second capacitor 213 connected in series.

[0046] Through the parallel connection of the first voltage equalization branch and the second voltage equalization branch of the voltage equalization circuit, the voltage across the switch tubes in the first inner tube module 13 and the switch tubes in the first outer tube module 12 can be made as equal as possible, the switch tubes in the first inner tube module 13 are prevented from bearing excessively high voltage due to uneven voltage, and the reliability and stability of the entire circuit are improved.

[0047] And, in the embodiment, the first voltage equalization circuit 21 includes a first voltage equalization branch and a second voltage equalization branch, the first capacitor 211 in the first voltage equalization branch has the characteristics of fast charge and discharge. In the moment when the switch tube is turned on and turned off, the voltage in the first voltage equalization circuit 21 will change rapidly. The first capacitor 211 can quickly absorb or release the charge, and quickly adjust the voltage across the switch tube in the first inner tube module 13 to balance the voltage mutation caused by the switching action; the first resistor 212 and the second capacitor 213 in series in the second voltage equalization branch form an RC circuit. When the circuit is in a steady state, the resistor plays a role in limiting the current. By reasonably selecting the resistance value of the first resistor 212, a certain voltage drop can be generated on the first resistor 212, thereby adjusting the voltage across the second capacitor 213, and then realizing the fine adjustment of the voltage across the switch tube, ensuring that the voltage across the switch tube is more balanced in the steady state. The first resistor 212 in the second voltage equalization branch also has a damping effect, which can suppress the oscillation in the circuit. In addition, the addition of the first resistor 212 can consume the oscillation energy, so that the oscillation decays rapidly, reducing the influence of the oscillation on the switch tube and the entire circuit.

[0048] In addition, the structure of the parallel connection of the first voltage equalization branch and the second voltage equalization branch forms a redundant design. If one of the branches fails, the other branch can still achieve the voltage equalization function to a certain extent, improving the fault tolerance and reliability of the circuit; and, in the embodiment, the parameters of the first capacitor 211, the first resistor 212 and the second capacitor 213 can be adjusted based on the parasitic parameters of the switch tube to adapt to different circuit working conditions and requirements.

[0049] Similarly, in the embodiment, the second outer tube module 14 includes a third number of parallelly connected switch tubes, and the second inner tube includes a fourth number of parallelly connected switch tubes, and the third number is different from the fourth number. When the third number is different from the fourth number, the voltage stress borne by the switch tubes in the second inner tube module 15 and the switch tubes in the second outer tube module 14 can also be different, therefore, the second voltage equalization circuit 22 is connected in parallel with the switch tubes in the second outer tube module 14 or the switch tubes in the second inner tube module 15 to balance the voltage stress between the inner tube module and the outer tube module.

[0050] If the third quantity is greater than the fourth quantity, in one example, when the switch tubes in the first outer tube module 12 and the first inner tube module 13 are simultaneously turned on, the bus voltage is applied to the switch tubes in the second outer tube module 14 and the second inner tube module 15. At this time, due to the different number of switch tubes in parallel in the second outer tube module 14 and the second inner tube module 15, the impedances are different, and the second outer tube module 14 and the second inner tube module 15 will appear uneven voltage distribution. The voltage borne by the switch tubes in the second inner tube module 15 is larger, which may exceed the carrying capacity of the switch tubes, thereby causing damage to the switch tubes and affecting the normal operation of the inverter. Therefore, in the embodiment, the second voltage equalization circuit 22 is arranged in parallel with the switch tubes in the second inner tube module 15 to balance the impedance, so that the switch tubes in the second outer tube module 14 and the second inner tube module 15 bear the same voltage stress, and the safe and reliable operation of the switch tubes in the second outer tube module 14 and the second inner tube module 15 is ensured.

[0051] In a feasible implementation, the second voltage equalization circuit 22 is composed of two voltage equalization branches, including a third voltage equalization branch and a fourth voltage equalization branch, the third voltage equalization branch and the fourth voltage equalization branch are connected in parallel, and the third voltage equalization branch and the fourth voltage equalization branch are both connected in parallel with the switch tubes in the second inner tube module 15. The third voltage equalization branch includes a fifth capacitor 221, and the fourth voltage equalization branch includes a second resistor 222 and a sixth capacitor 223 connected in series.

[0052] In a feasible implementation, the three-level inverter circuit further includes a first clamping diode 23 and a second clamping diode 24. The negative electrode of the first clamping diode 23 is connected to the connection point between the first outer tube module 12 and the first inner tube module 13. The positive electrode of the first clamping diode 23 is connected to the negative electrode of the second clamping diode. The positive electrode of the second clamping diode 24 is connected to the connection point between the second inner tube module 15 and the second outer tube module 14. The connection point between the first clamping diode 23 and the second clamping diode 24 is connected to the midpoint O of the DC bus.

[0053] The first clamping diode 23 and the second clamping diode 24 in the embodiment cooperate with other elements in the three-level inverter circuit to clamp the output voltage at a specific level, so that the three-level inverter circuit can output three different levels. At the same time, it plays a role in protecting the switch tubes and improving the output waveform of the three-level inverter circuit.

[0054] The DC input module 11 further includes a third capacitor 25 and a fourth capacitor 26. The third capacitor 25 is connected between the positive electrode of the DC bus and the midpoint O of the DC bus. The fourth capacitor 26 is connected between the negative electrode of the DC bus and the midpoint O of the DC bus.

[0055] The third capacitor 25 and the fourth capacitor 26 are arranged to stabilize the DC bus midpoint potential, improve the dynamic response capability of the circuit, and share the voltage stress of the switch tube.

[0056] In an embodiment, the three-level inverter circuit further comprises a filter module 27, and the connection point between the first inner tube module 13 and the second inner tube module 15 is connected to the AC output module 17 through the filter module 27.

[0057] The filter module 27 can effectively filter the high-frequency harmonics of the output through the characteristics of its inductance, capacitance and other elements, so that the current and voltage output to the AC load are closer to the sine wave, and the power quality is improved. The output waveform can also be smoothed, electromagnetic interference can be suppressed, and the stable AC power after filtering can reduce the electrical stress on the load device and prolong the service life of the device.

[0058] Corresponding to the three-level inverter circuit described above, the utility model embodiment still provides a kind of converter, including any one of the three-level inverter circuit as above, and with the beneficial effects of any one of the three-level inverter circuit as above.

[0059] The utility model embodiment further provides a kind of power supply equipment, including the converter of any one as above, and with the beneficial effects of any one of the converter as above.

[0060] The above embodiments are only used to illustrate the technical solutions of the utility model, but not to limit them; although the utility model is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part of technical features; and these modifications or replacements do not make the essence of corresponding technical solutions deviate from the spirit and scope of the technical solutions of the utility model embodiments, and all should be included in the protection scope of the utility model.

Claims

1. A three-level inverter circuit, characterized by comprising: The three-level inverter circuit comprises a direct current input module, a first outer tube module, a first inner tube module, a second outer tube module, a second inner tube module, a voltage equalization circuit module and an alternating current output module. The direct current input module comprises a positive pole of a direct current bus and a negative pole of the direct current bus. The positive pole of the direct current bus is connected to the first outer tube module, the first outer tube module, the first inner tube module, the second outer tube module and the second inner tube module are connected in series, the connection points between the first outer tube module and the first inner tube module and between the second outer tube module and the second inner tube module are respectively connected to a midpoint of the direct current bus, and the negative pole of the direct current bus is connected to the second outer tube module. The connection point between the first inner tube module and the second inner tube module is connected to the alternating current output module. The voltage equalization circuit module comprises at least one voltage equalization circuit, and the voltage equalization circuit is connected in parallel with the first outer tube module, the first inner tube module, the second outer tube module or the second inner tube module.

2. The three-level inverter circuit according to claim 1, characterized in that, The first outer tube module comprises a first number of parallelly connected switch tubes, the first inner tube module comprises a second number of parallelly connected switch tubes, the first number is different from the second number, and the voltage equalization circuit is connected in parallel with the switch tubes in the first outer tube module or the switch tubes in the first inner tube module.

3. The three-level inverter circuit according to claim 2, characterized in that, The first number is greater than the second number, and the voltage equalization circuit is connected in parallel with the switch tubes in the first inner tube module.

4. The three-level inverter circuit according to claim 3, characterized in that, The voltage equalization circuit comprises a first voltage equalization branch and a second voltage equalization branch, the first voltage equalization branch and the second voltage equalization branch are connected in parallel, and the first voltage equalization branch and the second voltage equalization branch are both connected in parallel with the switch tubes in the first inner tube module. The first voltage equalization branch comprises a first capacitor, and the second voltage equalization branch comprises a first resistor and a second capacitor connected in series.

5. The three-level inverter circuit according to any one of claims 1 to 4, characterized in that, The three-level inverter circuit further comprises a first clamping diode and a second clamping diode. The negative pole of the first clamping diode is connected to the connection point between the first outer tube module and the first inner tube module, and the positive pole of the first clamping diode is connected to the negative pole of the second clamping diode. The positive pole of the second clamping diode is connected to the connection point between the second inner tube module and the second outer tube module. The connection point between the first clamping diode and the second clamping diode is connected to the midpoint of the direct current bus.

6. The three-level inverter circuit according to any one of claims 1 to 4, characterized in that, The direct current input module further comprises a third capacitor and a fourth capacitor. The third capacitor is connected between the positive pole of the direct current bus and the midpoint of the direct current bus. The fourth capacitor is connected between the negative pole of the direct current bus and the midpoint of the direct current bus.

7. A three-level inverter circuit according to any one of claims 1-4, characterized in that, The three-level inverter circuit further comprises a filter module. The connection point between the first inner tube module and the second inner tube module is connected to the alternating current output module through the filter module.

8. The three-level inverter circuit according to claim 1, characterized by The second outer tube module comprises a third number of parallelly connected switch tubes, the second inner tube comprises a fourth number of parallelly connected switch tubes, the third number is different from the fourth number, and the voltage equalization circuit is connected in parallel with the switch tubes in the second outer tube module or the switch tubes in the second inner tube module.

9. A converter, characterized by A three-level inverter circuit as claimed in any one of claims 1-8.

10. A power supply device characterized by comprising: A converter as claimed in claim 9.

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