Zero crossing point switching method and system of ANPC type three-level inverter

Abstract

The invention discloses a zero crossing point switching method and system for an ANPC type three-level inverter, and the method comprises the steps: determining a zero crossing point switching type when the ANPC type three-level inverter needs to carry out the zero crossing point switching, and enabling the zero crossing point switching type to be used for indicating a half-cycle switching mode of the ANPC type three-level inverter; according to the zero crossing point switching type, a first switch tube combination and a second switch tube combination are determined, and each of the first switch tube combination and the second switch tube combination comprises an outer tube and a clamping tube; and sequentially executing switching state exchange of the first switching tube combination, switching state exchange of an inner tube of the ANPC type three-level inverter and switching state exchange of the second switching tube combination so as to complete zero crossing point switching of the ANPC type three-level inverter. And more optimized zero crossing point switching logic is adopted, so that switching can be carried out in a zero-current or zero-voltage state.

Description

Technical Field

[0001] The present application relates to the technical field of ANPC type three-level inverters, and in particular to a zero-crossing switching method and system for an ANPC type three-level inverter. Background Art

[0002] In the prior art of the internal tube high frequency modulation technology, the internal tube high frequency chopping mode is a configuration scheme of 2 fast tubes and 4 slow tubes. The outer tube and the clamping tube work in the power frequency mode, and the inner tube works in the high frequency mode. The switching loss is concentrated on the inner tube. The outer tube and the clamping tube only bear part of the conduction loss, and only the inner tube uses a high-speed tube. When the internal tube high frequency modulation method is used, the zero-crossing switching needs to change the state of the outer tube and the clamping tube, and natural switching cannot be achieved. Switching needs to be done in a certain order, otherwise overvoltage damage may occur during zero-crossing switching.

[0003] In response to the problem of zero-crossing switching, this patent proposes an improved switching method, which aims to solve the problems existing in the prior art and achieve more efficient power conversion through optimized control strategies, while reducing costs and improving system reliability and efficiency. Summary of the invention

[0004] In view of this, an embodiment of the present application provides a zero-crossing switching method and system for an ANPC type three-level inverter, which overcomes the complexity and cost problems caused by hard switching conditions in the prior art.

[0005] According to one aspect of the present application, a zero-crossing switching method for an ANPC type three-level inverter is provided, the method comprising:

[0006] When the ANPC type three-level inverter needs to perform zero-crossing switching, determining the zero-crossing switching type, wherein the zero-crossing switching type is used to indicate a half-cycle switching mode of the ANPC type three-level inverter;

[0007] Determine a first switch tube combination and a second switch tube combination according to the zero-crossing switching type, wherein the first switch tube combination and the second switch tube combination each include an outer tube and a clamping tube;

[0008] The switch state exchange of the first switch tube combination, the switch state exchange of the inner tube of the ANPC type three-level inverter, and the switch state exchange of the second switch tube combination are performed in sequence to complete the zero-crossing switching of the ANPC type three-level inverter.

[0009] In an optional implementation manner, determining the zero-crossing switching type includes:

[0010] According to the current operation cycle of the ANPC type three-level inverter, the zero-crossing switching type is determined, wherein if the current operation cycle is a positive half cycle, the zero-crossing switching type is determined to be a positive-negative half cycle switching, and if the current operation cycle is a negative half cycle, the zero-crossing switching type is determined to be a negative-positive half cycle switching.

[0011] In an optional implementation manner, determining the first switch tube combination and the second switch tube combination according to the zero-crossing switching type includes:

[0012] If the zero-crossing switching type is positive and negative half-cycle switching, the outer tube T1 and the clamping tube T5 corresponding to the positive half-cycle are determined as the first switch tube combination, and the outer tube T4 and the clamping tube T6 corresponding to the negative half-cycle are determined as the second switch tube combination;

[0013] If the zero-crossing switching type is negative-positive half-cycle switching, the outer tube T4 and clamp tube T6 corresponding to the negative half-cycle are determined as the first switch tube combination, and the outer tube T1 and clamp tube T5 corresponding to the positive half-cycle are determined as the second switch tube combination.

[0014] In an optional implementation, before sequentially performing the switch state exchange of the first switch tube combination, the switch state exchange of the inner tube of the ANPC type three-level inverter, and the switch state exchange of the second switch tube combination, the method further includes:

[0015] According to the zero-crossing switching type, the first inner tube and the second inner tube are determined, wherein if the zero-crossing switching type is positive-negative half-cycle switching, the first inner tube is the inner tube T3 corresponding to the negative half-cycle, and the second inner tube is the inner tube T2 corresponding to the positive half-cycle; if the zero-crossing switching type is negative-positive half-cycle switching, the first inner tube is the inner tube T2 corresponding to the positive half-cycle, and the second inner tube is the inner tube T3 corresponding to the negative half-cycle.

[0016] In an optional implementation, sequentially performing the switch state exchange of the first switch tube combination, the switch state exchange of the inner tube of the ANPC type three-level inverter, and the switch state exchange of the second switch tube combination to complete the zero-crossing switching of the ANPC type three-level inverter includes:

[0017] The outer tube in the first switch tube combination is turned off and the clamping tube in the first switch tube combination is turned on in sequence to complete the switch state exchange of the first switch tube combination, the first inner tube is turned off and the second inner tube is turned on in sequence to complete the switch state exchange of the inner tube, the clamping tube in the second switch tube combination is turned off and the outer tube in the second switch tube combination is turned on in sequence to complete the switch state exchange of the second switch tube combination, and the zero-crossing switching of the ANPC type three-level inverter is completed.

[0018] In an optional implementation, the sequentially shutting down the outer tube in the first switch tube combination and turning on the clamping tube in the first switch tube combination includes:

[0019] Turning off the outer tube in the first switch tube combination, and turning on the clamping tube in the first switch tube combination after a delay of time t0;

[0020] The sequentially shutting off the first inner tube and opening the second inner tube comprises:

[0021] After a delay of time t1, the first inner tube is turned off, and after a delay of time t2, the second inner tube is turned on;

[0022] The method of sequentially shutting off the clamping tube in the second switch tube combination and turning on the outer tube in the second switch tube combination includes:

[0023] After a delay of time t3, the clamping tube in the second switch tube combination is turned off, and after a delay of time t4, the outer tube in the second switch tube combination is turned on, and the delay time t5 is waited.

[0024] In an optional implementation manner, the ANPC type three-level inverter includes an outer tube T1, an inner tube T2, an inner tube T3, an outer tube T4, a clamping tube T5, and a clamping tube T6; sequentially performing the switch state exchange of the first switch tube combination, the switch state exchange of the inner tube of the ANPC type three-level inverter, and the switch state exchange of the second switch tube combination to complete the zero-crossing switching of the ANPC type three-level inverter includes:

[0025] When the zero-crossing switching type is positive and negative half-cycle switching, the outer tube T1 is turned off, the clamping tube T5 is turned on after a delay of t0, the inner tube T3 is turned off after a delay of t1, the inner tube T2 is turned on after a delay of t2, the clamping tube T6 is turned off after a delay of t3, and the outer tube T4 is turned on after a delay of t4, and the delay time t5 is waited to complete the zero-crossing switching of the ANPC type three-level inverter;

[0026] When the zero-crossing switching type is negative-positive half-cycle switching, the outer tube T4 is turned off, the clamping tube T6 is turned on after a delay of t0, the inner tube T2 is turned off after a delay of t1, the inner tube T3 is turned on after a delay of t2, the clamping tube T5 is turned off after a delay of t3, and the outer tube T1 is turned on after a delay of t4, and the delay time t5 is waited to complete the zero-crossing switching of the ANPC type three-level inverter.

[0027] According to another aspect of the present application, a zero-crossing switching system of an ANPC type three-level inverter is provided, the system comprising:

[0028] ANPC type three-level inverter and controller; the controller is used for:

[0029] When the ANPC type three-level inverter needs to perform zero-crossing switching, determining the zero-crossing switching type, wherein the zero-crossing switching type is used to indicate a half-cycle switching mode of the ANPC type three-level inverter;

[0030] Determine a first switch tube combination and a second switch tube combination according to the zero-crossing switching type, wherein the first switch tube combination and the second switch tube combination each include an outer tube and a clamping tube;

[0031] The switch state exchange of the first switch tube combination, the switch state exchange of the inner tube of the ANPC type three-level inverter, and the switch state exchange of the second switch tube combination are performed in sequence to complete the zero-crossing switching of the ANPC type three-level inverter.

[0032] In an optional embodiment, the controller is also used to: determine the zero-crossing switching type according to the current operating cycle of the ANPC three-level inverter, wherein if the current operating cycle is a positive half-cycle, the zero-crossing switching type is determined to be a positive-negative half-cycle switching; if the current operating cycle is a negative half-cycle, the zero-crossing switching type is determined to be a negative-positive half-cycle switching.

[0033] In an optional embodiment, the controller is also used to: if the zero-crossing switching type is positive and negative half-cycle switching, determine the outer tube T1 and clamp tube T5 corresponding to the positive half-cycle as the first switch tube combination, and determine the outer tube T4 and clamp tube T6 corresponding to the negative half-cycle as the second switch tube combination.

[0034] In an optional embodiment, the controller is also used to: determine the first inner tube and the second inner tube according to the zero-crossing switching type, wherein if the zero-crossing switching type is positive-negative half-cycle switching, the first inner tube is the inner tube T3 corresponding to the negative half-cycle, and the second inner tube is the inner tube T2 corresponding to the positive half-cycle; if the zero-crossing switching type is negative-positive half-cycle switching, the first inner tube is the inner tube T2 corresponding to the positive half-cycle, and the second inner tube is the inner tube T3 corresponding to the negative half-cycle.

[0035] In an optional embodiment, the controller is also used to: sequentially turn off the outer tube in the first switch tube combination and turn on the clamping tube in the first switch tube combination to complete the switch state exchange of the first switch tube combination, sequentially turn off the first inner tube and turn on the second inner tube to complete the switch state exchange of the inner tube, sequentially turn off the clamping tube in the second switch tube combination and turn on the outer tube in the second switch tube combination to complete the switch state exchange of the second switch tube combination, and complete the zero-crossing switching of the ANPC type three-level inverter.

[0036] In an optional implementation manner, the controller is further used to: turn off the outer tube in the first switch tube combination, and turn on the clamping tube in the first switch tube combination after a delay of time t0;

[0037] After a delay of time t1, the first inner tube is turned off, and after a delay of time t2, the second inner tube is turned on;

[0038] After a delay of time t3, the clamping tube in the second switch tube combination is turned off, and after a delay of time t4, the outer tube in the second switch tube combination is turned on, and the delay time t5 is waited.

[0039] In the embodiment of the present application, optionally, the ANPC type three-level inverter includes an outer tube T1, an inner tube T2, an inner tube T3, an outer tube T4, a clamping tube T5, and a clamping tube T6; the controller is further used for:

[0040] When the zero-crossing switching type is positive and negative half-cycle switching, the outer tube T1 is turned off, the clamping tube T5 is turned on after a delay of t0, the inner tube T3 is turned off after a delay of t1, the inner tube T2 is turned on after a delay of t2, the clamping tube T6 is turned off after a delay of t3, and the outer tube T4 is turned on after a delay of t4, and the delay time t5 is waited to complete the zero-crossing switching of the ANPC type three-level inverter;

[0041] When the zero-crossing switching type is negative-positive half-cycle switching, the outer tube T4 is turned off, the clamping tube T6 is turned on after a delay of t0, the inner tube T2 is turned off after a delay of t1, the inner tube T3 is turned on after a delay of t2, the clamping tube T5 is turned off after a delay of t3, and the outer tube T1 is turned on after a delay of t4, and the delay time t5 is waited to complete the zero-crossing switching of the ANPC type three-level inverter.

[0042] According to another aspect of the present application, a storage medium is provided, on which a computer program is stored, and when the program is executed by a processor, the zero-crossing switching method of the ANPC type three-level inverter is implemented.

[0043] According to another aspect of the present application, a computer device is provided, including a storage medium, a processor, and a computer program stored on the storage medium and executable on the processor, wherein when the processor executes the program, the zero-crossing switching method of the ANPC type three-level inverter is implemented.

[0044] By means of the above technical scheme, a zero-crossing switching method and system of an ANPC type three-level inverter provided in an embodiment of the present application adopts a more optimized zero-crossing switching logic, so that the switch can be performed under a zero current or zero voltage state. In particular, the two high-frequency switching tubes as the inner tubes are subjected to significantly reduced stress under the new switching strategy. And compared with traditional PWM modulation, this method does not require complex switching logic to manage the switching tubes, but focuses on orderly conversion at specific moments, simplifies the design of the control system, and improves the reliability of the system. At the same time, because not all switches need to be configured as high-frequency switching tubes, lower-specification IGBT wafers can be selected for switch positions for non-high-frequency operations, thereby directly reducing hardware costs.

[0045] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0047] Figure 1 A schematic flow chart of a zero-crossing switching method for an ANPC type three-level inverter provided in an embodiment of the present application is shown;

[0048] Figure 2 A schematic flow chart of a zero-crossing switching method for an ANPC type three-level inverter provided in an embodiment of the present application is shown;

[0049] Figure 3 A schematic diagram of the structure of an ANPC type three-level inverter provided in an embodiment of the present application is shown;

[0050] Figure 4 A zero-crossing switching logic diagram of an ANPC type three-level inverter provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0051] The present application will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other without conflict.

[0052] In this embodiment, a zero-crossing switching method of an ANPC type three-level inverter is provided. Figure 1 As shown, the method includes:

[0053] Step 101: When the ANPC type three-level inverter needs to perform zero-crossing switching, determine the zero-crossing switching type, wherein the zero-crossing switching type is used to indicate a half-cycle switching mode of the ANPC type three-level inverter;

[0054] Step 102: Determine a first switch tube combination and a second switch tube combination according to the zero-crossing switching type, wherein the first switch tube combination and the second switch tube combination each include an outer tube and a clamping tube;

[0055] Step 103: sequentially execute the switch state exchange of the first switch tube combination, the switch state exchange of the inner tube of the ANPC type three-level inverter, and the switch state exchange of the second switch tube combination to complete the zero-crossing switching of the ANPC type three-level inverter.

[0056] The embodiment of the present application provides a zero-crossing switching method for an ANPC type three-level inverter, which is intended to overcome the complexity and cost problems caused by the hard switching conditions in the prior art. First, identify the type of zero-crossing switching that needs to be performed, that is, determine the half-cycle switching method that the ANPC type three-level inverter should adopt when the current or voltage waveform passes through the zero point. This step ensures that the subsequent operation can accurately adjust the switch state according to the actual situation. According to the determined zero-crossing switching type, select an appropriate first switch tube combination (including an outer switch tube, i.e., an outer tube, and a clamp switch tube, i.e., a clamp tube) and a second switch tube combination (also including an outer tube and a clamp tube). This selection process takes into account avoiding unnecessary stress on the IGBT. Afterwards, the following three stages of operation are performed in sequence in a predetermined order: the switch state exchange of the first switch tube combination, the switch state exchange of the inner tube (i.e., the internal switch tube) of the ANPC type three-level inverter, and the switch state exchange of the second switch tube combination. Such a sequence ensures that the switching action can transition more smoothly near the zero-crossing point, thereby realizing the so-called "soft switching" condition and reducing the negative impact of hard switching.

[0057] It should be noted that the switching tubes in the ANPC type three-level inverter of the embodiment of the present application include but are not limited to IGBT, SIC MOSFET, MOSFET, etc.

[0058] By applying the technical solution of this embodiment, due to the use of a more optimized zero-crossing switching logic, the switch can be operated in a state close to zero current or zero voltage. In particular, the two high-frequency switching tubes as the inner tubes are significantly less stressed under the new switching strategy. And compared with traditional PWM modulation, this method does not require complex switching logic to manage the switching tubes, but focuses on orderly conversion at specific moments, simplifies the design of the control system, and improves the reliability of the system. At the same time, because not all switches need to be configured as high-frequency switching tubes, lower-specification IGBT wafers can be selected for switch positions that are not operated at high frequencies, thereby directly reducing hardware costs.

[0059] In an embodiment of the present application, optionally, determining the zero-crossing switching type includes: determining the zero-crossing switching type according to the current operating cycle of the ANPC three-level inverter, wherein if the current operating cycle is a positive half-cycle, then determining the zero-crossing switching type is positive-negative half-cycle switching; if the current operating cycle is a negative half-cycle, then determining the zero-crossing switching type is negative-positive half-cycle switching.

[0060] In this embodiment, if the inverter is currently outputting the positive half of the sine wave (i.e., the voltage is positive), then when it approaches the zero point and is ready to switch to the negative half cycle, this switching type is defined as "positive-negative half cycle switching", and it is necessary to switch from the state of generating positive voltage to the state of preparing to generate negative voltage. On the contrary, if the inverter is currently in the negative half of the output sine wave (i.e., the voltage is negative), then when it approaches the zero point and is ready to switch back to the positive half cycle, this switching type is called "negative-positive half cycle switching", and it is necessary to switch from the state of generating negative voltage to the state of preparing to generate positive voltage. By clearly distinguishing the switching types of the positive and negative half cycles, a more accurate and reliable switching control strategy can be implemented to ensure that appropriate switching actions are performed at the right time to minimize unnecessary losses and interference, so as to optimize the switching sequence for each situation, thereby improving the efficiency and response speed of the system, and reducing possible electromagnetic interference.

[0061] In an embodiment of the present application, optionally, determining the first switch tube combination and the second switch tube combination according to the zero-crossing switching type includes: if the zero-crossing switching type is positive-negative half-cycle switching, determining the outer tube T1 and the clamp tube T5 corresponding to the positive half-cycle as the first switch tube combination, and determining the outer tube T4 and the clamp tube T6 corresponding to the negative half-cycle as the second switch tube combination; if the zero-crossing switching type is negative-positive half-cycle switching, determining the outer tube T4 and the clamp tube T6 corresponding to the negative half-cycle as the first switch tube combination, and determining the outer tube T1 and the clamp tube T5 corresponding to the positive half-cycle as the second switch tube combination.

[0062] In this embodiment, when the zero-crossing switching type is a positive-negative half-cycle switching (i.e., switching from the positive half-cycle to the negative half-cycle), it is necessary to prepare to switch from the output positive voltage state to the output negative voltage state. The switch tube combination determination rule at this time is: select the outer switch tube T1 and the clamp switch tube T5 corresponding to the positive half-cycle as the first switch tube combination. Select the outer switch tube T4 and the clamp switch tube T6 corresponding to the negative half-cycle as the second switch tube combination. On the contrary, when the zero-crossing switching type is a negative-positive half-cycle switching (i.e., switching from the negative half-cycle to the positive half-cycle), it is necessary to prepare to switch from the output negative voltage state to the output positive voltage state. The switch tube combination determination rule at this time is: select the outer switch tube T4 and the clamp switch tube T6 corresponding to the negative half-cycle as the first switch tube combination, and select the outer switch tube T1 and the clamp switch tube T5 corresponding to the positive half-cycle as the second switch tube combination. T1 and T5 are a pair of complementary combinations. When T1 is turned on, it is generally P level, because T1 is connected to the P level side DC+. When T5 is turned on, it is generally 0 level, and T5 is connected to the midpoint 0 level side. Similarly, T4 and T6, when T4 is turned on, it is generally N level, and when T6 is turned on, it is 0 level. And T2 T3 is also a complementary combination, controlling the level of the output end; that is to say, T1 T5, T2 T3, T6 T4 itself is a pair of switch combinations by default, because their switch states are complementary. Reasonable selection of switch tube combinations avoids rapid switching from one extreme state to another, thereby protecting the switch tube and other circuit components from high stress.

[0063] In an embodiment of the present application, optionally, before sequentially executing the switch state exchange of the first switch tube combination, the switch state exchange of the inner tube of the ANPC type three-level inverter, and the switch state exchange of the second switch tube combination, the method also includes: determining the first inner tube and the second inner tube according to the zero-crossing switching type, wherein if the zero-crossing switching type is positive and negative half-cycle switching, the first inner tube is the inner tube T3 corresponding to the negative half-cycle, and the second inner tube is the inner tube T2 corresponding to the positive half-cycle, and if the zero-crossing switching type is negative and positive half-cycle switching, the first inner tube is the inner tube T2 corresponding to the positive half-cycle, and the second inner tube is the inner tube T3 corresponding to the negative half-cycle.

[0064] In this embodiment, under the high-frequency modulation of the inner tube, the switch of the inner tube directly controls the level of the output end, but after the outer tube is turned off, the inner tube switch will only be able to output a 0 level. In order to avoid the loss caused when the outer tube is turned on and off, it is necessary to turn off the inner tube of the half cycle to be switched to, such as positive and negative switching, and finally T4 is turned on, so all T3 cannot be turned on and can only be turned off. It is necessary to first exchange the switch state of the inner tube to turn off T3, and then turn on T4 to avoid the generation of outer tube loss. If the zero-crossing switching type is to switch from the positive half cycle to the negative half cycle, the first inner tube is determined to be the inner tube T3 corresponding to the negative half cycle, and the second inner tube is the inner tube T2 corresponding to the positive half cycle, that is, the inner switch tube that is working during the current positive half cycle. If the zero-crossing switching type is to switch from the negative half cycle to the positive half cycle, the first inner tube is determined to be the inner tube T2 corresponding to the positive half cycle, and the second inner tube is the inner tube T3 corresponding to the negative half cycle, that is, the inner switch tube that is working during the current negative half cycle.

[0065] In an embodiment of the present application, optionally, the sequentially executing the switch state exchange of the first switch tube combination, the switch state exchange of the inner tube of the ANPC type three-level inverter, and the switch state exchange of the second switch tube combination to complete the zero-crossing switching of the ANPC type three-level inverter includes: sequentially executing the switching state exchange of the outer tube in the first switch tube combination and opening the clamping tube in the first switch tube combination to complete the switch state exchange of the first switch tube combination, sequentially executing the switching state exchange of the first inner tube and opening the second inner tube to complete the switch state exchange of the inner tube, sequentially executing the switching state exchange of the clamping tube in the second switch tube combination and opening the outer tube in the second switch tube combination to complete the switch state exchange of the second switch tube combination, and completing the zero-crossing switching of the ANPC type three-level inverter.

[0066] In this embodiment, the outer switch tube in the first switch tube combination (i.e., the outer tube corresponding to the current half cycle) is first turned off to cut off the direct connection of the current voltage level, and then the clamp switch tube in the first switch tube combination is turned on. The function of the clamp switch is to prevent the voltage at the intermediate point from being too high and to provide a current path, and to ensure that the voltage smoothly transitions to the next stage, thereby completing the switch state exchange of the first switch tube combination. Next, the first inner tube corresponding to the other half cycle is turned off, and then the second inner tube corresponding to the current half cycle is turned on. Finally, the clamp switch tube in the second switch tube combination is turned off to release the voltage state maintained by the clamp tube, and then the outer switch tube in the second switch tube combination (i.e., the outer tube corresponding to the new half cycle) is turned on. This step establishes a new voltage level connection and completes the entire switching process. Through the above-mentioned orderly and precise switch state exchange method, the state of each switch can be gradually adjusted, especially the conversion between the clamp tube and the outer tube, which can effectively reduce the transient impact of voltage and current, improve the stability and reliability of the system, maintain good dynamic response performance, especially near the zero crossing point, and the smooth voltage and current transition reduces the generation of high-frequency noise, thereby reducing the risk of electromagnetic interference and improving the electromagnetic compatibility of the system. In addition, the optimized switching sequence can reduce unnecessary switching losses and thus improve the overall conversion efficiency of the inverter. The correct switching sequence avoids rapid switching directly from one extreme state to another, which helps protect the switch tube and other circuit components from high stress.

[0067] In an embodiment of the present application, optionally, the sequential execution of turning off the outer tube in the first switch tube combination and turning on the clamping tube in the first switch tube combination includes: turning off the outer tube in the first switch tube combination, and turning on the clamping tube in the first switch tube combination after a delay of t0; the sequential execution of turning off the first inner tube and turning on the second inner tube includes: turning off the first inner tube after a delay of t1, and turning on the second inner tube after a delay of t2; the sequential execution of turning off the clamping tube in the second switch tube combination and turning on the outer tube in the second switch tube combination includes: turning off the clamping tube in the second switch tube combination after a delay of t3, and turning on the outer tube in the second switch tube combination after a delay of t4, and waiting for a delay of t5.

[0068] In this embodiment, if Figure 2As shown, first turn off the outer switch tube in the first switch tube combination (i.e., the outer tube corresponding to the current half cycle), wait for a period of time t0 to ensure that the outer tube is completely turned off, and then turn on the clamp switch tube in the first switch tube combination to prevent the voltage at the middle point from being too high and ensure that the voltage smoothly transitions to the next stage. After turning off the outer tube and turning on the clamp tube, delay for a period of time t1 to ensure that the system is in a stable state, then turn off the first inner tube corresponding to the other half cycle, and then delay for a period of time t2 to ensure that the first inner tube is completely turned off and the current is stable, and then turn on the second inner tube corresponding to the current half cycle that is about to enter. After completing the switch state exchange of the inner tube, delay for a period of time t3 to ensure that the system is in a stable state, then turn off the clamp switch tube in the second switch tube combination to release the voltage state maintained by the clamp tube, and delay for a period of time t4 again to ensure that the clamp tube is completely turned off and the current is stable, and finally turn on the outer switch tube in the second switch tube combination (i.e., the outer tube corresponding to the new half cycle), thereby establishing a new voltage level connection and completing the entire switching process. Finally, the system waits for an additional delay time t5 to ensure that after all switch actions are completed, the system can be fully stabilized and ready to enter the next working cycle. By setting an appropriate delay time, transient shocks caused by the simultaneous action of multiple switches can be avoided, reducing the possibility of voltage or current spikes, helping to ensure that each switch operates at the appropriate time point, avoiding the impact of high stress on the switch tube and other components, thereby extending their service life. Even if there is a slight time deviation under certain conditions, it will not affect the overall switching performance, allowing the system to adapt to load changes more quickly and maintain good dynamic response performance, especially near the zero crossing point.

[0069] In the embodiment of the present application, optionally, Figure 3 As shown, the ANPC type three-level inverter includes an outer tube T1, an inner tube T2, an inner tube T3, an outer tube T4, a clamping tube T5, and a clamping tube T6; the switching state exchange of the first switch tube combination, the switching state exchange of the inner tube of the ANPC type three-level inverter, and the switching state exchange of the second switch tube combination are sequentially performed to complete the zero-crossing switching of the ANPC type three-level inverter, including:

[0070] When the zero-crossing switching type is positive and negative half-cycle switching, the outer tube T1 is turned off, the clamping tube T5 is turned on after a delay of t0, the inner tube T3 is turned off after a delay of t1, the inner tube T2 is turned on after a delay of t2, the clamping tube T6 is turned off after a delay of t3, and the outer tube T4 is turned on after a delay of t4, and the delay time t5 is waited to complete the zero-crossing switching of the ANPC type three-level inverter;

[0071] When the zero-crossing switching type is negative-positive half-cycle switching, the outer tube T4 is turned off, the clamping tube T6 is turned on after a delay of t0, the inner tube T2 is turned off after a delay of t1, the inner tube T3 is turned on after a delay of t2, the clamping tube T5 is turned off after a delay of t3, and the outer tube T1 is turned on after a delay of t4, and the delay time t5 is waited to complete the zero-crossing switching of the ANPC type three-level inverter.

[0072] In the above embodiment, the ANPC type three-level inverter includes the switch tubes corresponding to the positive half cycle (outer tube T1, inner tube T2, clamp tube T6) and the switch tubes corresponding to the negative half cycle (inner tube T3, outer tube T4, clamp tube T5). When switching at the zero point, the state change of the switch tube is carried out in an orderly and safe manner to minimize transient impact and protect circuit components. Figure 4 As shown, the zero-crossing switching steps are as follows: First, turn off the outer tube in the outer tube clamp tube combination corresponding to the half cycle. Turn off the outer tube T1 when switching between the positive and negative half cycles, and turn off the outer tube T4 when switching between the negative and positive half cycles. Wait for a period of time t0 to ensure that the outer tube is completely turned off. Turn on the clamp tube in the outer tube clamp tube combination corresponding to the half cycle. Turn on the clamp tube T5 when switching between the positive and negative half cycles, and turn on the clamp tube T6 when switching between the negative and positive half cycles. Wait for a period of time t1 to ensure that the clamp tube is fully turned on and the system is stable. Turn off the inner tube of the other half cycle in the inner tube combination. Turn off the negative half cycle inner tube T3 when switching between the positive and negative half cycles, and turn off the positive half cycle inner tube T2 when switching between the negative and positive half cycles. Wait for a period of time t2 to ensure that the inner tube is completely turned off and the current is stable. Turn on the inner tube of the corresponding half cycle in the inner tube combination. Turn on the positive half cycle inner tube T2 when switching between the positive and negative half cycles, and turn on the negative half cycle inner tube T3 when switching between the negative and positive half cycles. Wait for a period of time t3 to ensure that the inner tube is fully turned on and the system is stable, and then turn off the clamp tube in the outer tube clamp tube combination corresponding to the other half cycle. Turn off the clamp tube T6 when switching between the positive and negative half cycles, and turn off the clamp tube T5 when switching between the negative and positive half cycles. Wait for a period of time t4 to ensure that the clamp tube is fully turned off and the current is stable. Turn on the outer tube in the outer tube clamp tube combination corresponding to the other half cycle. Turn on the outer tube T when switching between the positive and negative half cycles, and turn on the outer tube T1 when switching between the negative and positive half cycles. Wait for a period of time t5 to ensure that the outer tube is fully turned on and the system is stable.

[0073] By applying the technical solution of this embodiment, not only a clear and orderly zero-crossing switching process is provided, but also the safety and stability of the ANPC type three-level inverter during switching are ensured by accurately controlling the action sequence of each switch and introducing an appropriate delay time. Specifically, the outer tube of the current half cycle is turned off first, and then the corresponding clamping tube is turned on, then the inner tube of the other half cycle is turned off, and then the inner tube of the new half cycle is turned on, and finally the clamping tube and outer tube of the other half cycle are adjusted. This strategy helps to achieve a smoother voltage and current transition, reduces unnecessary electromagnetic interference and losses, and improves the overall performance and reliability of the system.

[0074] Further, as Figure 1 The specific implementation of the method, the embodiment of the present application provides a zero-crossing switching system of an ANPC type three-level inverter, comprising:

[0075] ANPC type three-level inverter and controller; the controller is used for:

[0076] When the ANPC type three-level inverter needs to perform zero-crossing switching, determining the zero-crossing switching type, wherein the zero-crossing switching type is used to indicate a half-cycle switching mode of the ANPC type three-level inverter;

[0077] Determine a first switch tube combination and a second switch tube combination according to the zero-crossing switching type, wherein the first switch tube combination and the second switch tube combination each include an outer tube and a clamping tube;

[0078] The switch state exchange of the first switch tube combination, the switch state exchange of the inner tube of the ANPC type three-level inverter, and the switch state exchange of the second switch tube combination are performed in sequence to complete the zero-crossing switching of the ANPC type three-level inverter.

[0079] In an embodiment of the present application, optionally, the controller is also used to: determine the zero-crossing switching type according to the current operating cycle of the ANPC three-level inverter, wherein if the current operating cycle is a positive half-cycle, the zero-crossing switching type is determined to be a positive-negative half-cycle switching; if the current operating cycle is a negative half-cycle, the zero-crossing switching type is determined to be a negative-positive half-cycle switching.

[0080] In an embodiment of the present application, optionally, the controller is also used to: if the zero-crossing switching type is positive and negative half-cycle switching, determine that the outer tube T1 and the clamping tube T5 corresponding to the positive half-cycle are the first switch tube combination, and determine that the outer tube T4 and the clamping tube T6 corresponding to the negative half-cycle are the second switch tube combination.

[0081] In an embodiment of the present application, optionally, the controller is also used to: determine the first inner tube and the second inner tube according to the zero-crossing switching type, wherein if the zero-crossing switching type is positive-negative half-cycle switching, the first inner tube is the inner tube T3 corresponding to the negative half-cycle, and the second inner tube is the inner tube T2 corresponding to the positive half-cycle; if the zero-crossing switching type is negative-positive half-cycle switching, the first inner tube is the inner tube T2 corresponding to the positive half-cycle, and the second inner tube is the inner tube T3 corresponding to the negative half-cycle.

[0082] In an embodiment of the present application, optionally, the controller is also used to: sequentially turn off the outer tube in the first switch tube combination and turn on the clamping tube in the first switch tube combination to complete the switch state exchange of the first switch tube combination, sequentially turn off the first inner tube and turn on the second inner tube to complete the switch state exchange of the inner tube, sequentially turn off the clamping tube in the second switch tube combination and turn on the outer tube in the second switch tube combination to complete the switch state exchange of the second switch tube combination, and complete the zero-crossing switching of the ANPC type three-level inverter.

[0083] In the embodiment of the present application, optionally, the controller is further used to: turn off the outer tube in the first switch tube combination, and turn on the clamping tube in the first switch tube combination after a delay of t0;

[0084] After a delay of time t1, the first inner tube is turned off, and after a delay of time t2, the second inner tube is turned on;

[0085] After a delay of time t3, the clamping tube in the second switch tube combination is turned off, and after a delay of time t4, the outer tube in the second switch tube combination is turned on, and the delay time t5 is waited.

[0086] In the embodiment of the present application, optionally, the ANPC type three-level inverter includes an outer tube T1, an inner tube T2, an inner tube T3, an outer tube T4, a clamping tube T5, and a clamping tube T6; the controller is further used for:

[0087] When the zero-crossing switching type is positive and negative half-cycle switching, the outer tube T1 is turned off, the clamping tube T5 is turned on after a delay of t0, the inner tube T3 is turned off after a delay of t1, the inner tube T2 is turned on after a delay of t2, the clamping tube T6 is turned off after a delay of t3, and the outer tube T4 is turned on after a delay of t4, and the delay time t5 is waited to complete the zero-crossing switching of the ANPC type three-level inverter;

[0088] When the zero-crossing switching type is negative-positive half-cycle switching, the outer tube T4 is turned off, the clamping tube T6 is turned on after a delay of t0, the inner tube T2 is turned off after a delay of t1, the inner tube T3 is turned on after a delay of t2, the clamping tube T5 is turned off after a delay of t3, and the outer tube T1 is turned on after a delay of t4, and the delay time t5 is waited to complete the zero-crossing switching of the ANPC type three-level inverter.

[0089] It should be noted that the corresponding description of the zero-crossing switching system of an ANPC type three-level inverter provided in the embodiment of the present application can be referred to Figure 1 to Figure 2 The corresponding description in the method will not be repeated here.

[0090] The processor involved in each embodiment provided in this application may be a general-purpose processor, a digital signal processor, a programmable logic device, etc., but is not limited thereto.

[0091] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0092] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A zero-crossing switching method for an ANPC type three-level inverter, characterized in that: The method comprises: When the ANPC type three-level inverter needs to perform zero-crossing switching, determining the zero-crossing switching type, wherein the zero-crossing switching type is used to indicate a half-cycle switching mode of the ANPC type three-level inverter; Determine a first switch tube combination and a second switch tube combination according to the zero-crossing switching type, wherein the first switch tube combination and the second switch tube combination each include an outer tube and a clamping tube; The switch state exchange of the first switch tube combination, the switch state exchange of the inner tube of the ANPC type three-level inverter, and the switch state exchange of the second switch tube combination are performed in sequence to complete the zero-crossing switching of the ANPC type three-level inverter.

2. The method according to claim 1, characterized in that Determining the zero-crossing switching type includes: According to the current operation cycle of the ANPC type three-level inverter, the zero-crossing switching type is determined, wherein if the current operation cycle is a positive half cycle, the zero-crossing switching type is determined to be a positive-negative half cycle switching, and if the current operation cycle is a negative half cycle, the zero-crossing switching type is determined to be a negative-positive half cycle switching.

3. The method according to claim 2, characterized in that The determining of the first switch tube combination and the second switch tube combination according to the zero-crossing switching type includes: If the zero-crossing switching type is positive and negative half-cycle switching, the outer tube T1 and the clamping tube T5 corresponding to the positive half-cycle are determined as the first switch tube combination, and the outer tube T4 and the clamping tube T6 corresponding to the negative half-cycle are determined as the second switch tube combination; If the zero-crossing switching type is negative-positive half-cycle switching, the outer tube T4 and clamp tube T6 corresponding to the negative half-cycle are determined as the first switch tube combination, and the outer tube T1 and clamp tube T5 corresponding to the positive half-cycle are determined as the second switch tube combination.

4. The method according to claim 3, characterized in that Before sequentially performing the switching state exchange of the first switch tube combination, the switching state exchange of the inner tube of the ANPC type three-level inverter, and the switching state exchange of the second switch tube combination, the method further includes: According to the zero-crossing switching type, the first inner tube and the second inner tube are determined, wherein if the zero-crossing switching type is positive-negative half-cycle switching, the first inner tube is the inner tube T3 corresponding to the negative half-cycle, and the second inner tube is the inner tube T2 corresponding to the positive half-cycle; if the zero-crossing switching type is negative-positive half-cycle switching, the first inner tube is the inner tube T2 corresponding to the positive half-cycle, and the second inner tube is the inner tube T3 corresponding to the negative half-cycle.

5. The method according to claim 4, characterized in that The step of sequentially performing the switch state exchange of the first switch tube combination, the switch state exchange of the inner tube of the ANPC type three-level inverter, and the switch state exchange of the second switch tube combination to complete the zero-crossing switching of the ANPC type three-level inverter includes: The outer tube in the first switch tube combination is turned off and the clamping tube in the first switch tube combination is turned on in sequence to complete the switch state exchange of the first switch tube combination, the first inner tube is turned off and the second inner tube is turned on in sequence to complete the switch state exchange of the inner tube, the clamping tube in the second switch tube combination is turned off and the outer tube in the second switch tube combination is turned on in sequence to complete the switch state exchange of the second switch tube combination, and the zero-crossing switching of the ANPC type three-level inverter is completed.

6. The method according to claim 5, characterized in that The method of sequentially shutting down the outer tube in the first switch tube combination and turning on the clamping tube in the first switch tube combination includes: Turning off the outer tube in the first switch tube combination, and turning on the clamping tube in the first switch tube combination after a delay of time t0; The sequentially shutting off the first inner tube and opening the second inner tube comprises: After a delay of time t1, the first inner tube is turned off, and after a delay of time t2, the second inner tube is turned on; The method of sequentially shutting off the clamping tube in the second switch tube combination and turning on the outer tube in the second switch tube combination includes: After a delay of time t3, the clamping tube in the second switch tube combination is turned off, and after a delay of time t4, the outer tube in the second switch tube combination is turned on, and the delay time t5 is waited.

7. The method according to any one of claims 1 to 6, characterized in that The ANPC type three-level inverter includes an outer tube T1, an inner tube T2, an inner tube T3, an outer tube T4, a clamping tube T5, and a clamping tube T6; the switching state exchange of the first switch tube combination, the switching state exchange of the inner tube of the ANPC type three-level inverter, and the switching state exchange of the second switch tube combination are sequentially performed to complete the zero-crossing switching of the ANPC type three-level inverter, including: When the zero-crossing switching type is positive and negative half-cycle switching, the outer tube T1 is turned off, the clamping tube T5 is turned on after a delay of t0, the inner tube T3 is turned off after a delay of t1, the inner tube T2 is turned on after a delay of t2, the clamping tube T6 is turned off after a delay of t3, and the outer tube T4 is turned on after a delay of t4, and the delay time t5 is waited to complete the zero-crossing switching of the ANPC type three-level inverter; When the zero-crossing switching type is negative-positive half-cycle switching, the outer tube T4 is turned off, the clamping tube T6 is turned on after a delay of t0, the inner tube T2 is turned off after a delay of t1, the inner tube T3 is turned on after a delay of t2, the clamping tube T5 is turned off after a delay of t3, and the outer tube T1 is turned on after a delay of t4, and the delay time t5 is waited to complete the zero-crossing switching of the ANPC type three-level inverter.

8. A zero-crossing switching system for an ANPC type three-level inverter, characterized in that: The system comprises: ANPC type three-level inverter and controller; the controller is used for: When the ANPC type three-level inverter needs to perform zero-crossing switching, determining the zero-crossing switching type, wherein the zero-crossing switching type is used to indicate a half-cycle switching mode of the ANPC type three-level inverter; Determine a first switch tube combination and a second switch tube combination according to the zero-crossing switching type, wherein the first switch tube combination and the second switch tube combination each include an outer tube and a clamping tube; The switch state exchange of the first switch tube combination, the switch state exchange of the inner tube of the ANPC type three-level inverter, and the switch state exchange of the second switch tube combination are performed in sequence to complete the zero-crossing switching of the ANPC type three-level inverter.

9. The system according to claim 8, characterized in that The controller is further used for: According to the current operation cycle of the ANPC type three-level inverter, the zero-crossing switching type is determined, wherein if the current operation cycle is a positive half cycle, the zero-crossing switching type is determined to be a positive-negative half cycle switching, and if the current operation cycle is a negative half cycle, the zero-crossing switching type is determined to be a negative-positive half cycle switching.

10. The system according to claim 9, characterized in that The controller is further used for: If the zero-crossing switching type is positive and negative half-cycle switching, the outer tube T1 and the clamp tube T5 corresponding to the positive half-cycle are determined as the first switch tube combination, and the outer tube T4 and the clamp tube T6 corresponding to the negative half-cycle are determined as the second switch tube combination.

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