A self-maintenance modulation method for current source inverter power consumption suppression switch aging

Abstract

This invention relates to the field of current source inverter technology, and in particular to a power consumption suppression-type switch aging self-maintenance modulation method for current source inverters. The method includes: acquiring the junction temperature of each power switch in an H7 current source inverter; determining prematurely aging power switches based on the junction temperature of each power switch; and performing zero-current switching operation on the prematurely aging power switches through the front-end power switch S7 of the H7 current source inverter to achieve self-maintenance of the H7 current source inverter. This invention is based on the H7-CSI topology circuit, optimizes the circuit commutation process through the front-end power switch, and performs zero-current switching operation on aging power switches to dynamically adjust the switching state and significantly reduce power consumption, thereby achieving self-maintenance, effectively extending the service life of the current source inverter and improving its operating efficiency.

Description

Technical Field

[0001] This invention relates to the field of current source inverter technology, and in particular to a power consumption suppression switching aging self-maintenance modulation method for current source inverters. Background Art

[0002] Inverters, as the core energy conversion devices in renewable energy systems such as wind, solar, and ocean energy, directly determine the operating efficiency and lifespan of the power generation system. In new energy power generation applications, inverters operate under complex and variable environmental conditions for extended periods. Research shows that the aging of power switching devices (such as IGBTs and MOSFETs) mainly manifests as thermal stress accumulation caused by junction temperature fluctuations, gate oxide layer damage, and fatigue of packaging materials. Their failure process is closely coupled with the environment, electrical stress, and operating conditions. For example, in ocean energy generation and offshore wind power scenarios, harsh conditions such as high humidity, salt spray corrosion, temperature fluctuations, and frequent load changes significantly accelerate the aging process of the power switching devices inside the inverter. The performance degradation of power switching devices not only leads to a decrease in energy conversion efficiency but may also cause system failures or even shutdowns, seriously affecting the economic viability and power supply stability of new energy power generation systems.

[0003] A current source inverter (CSI) is an inverter with boost capability and DC fault tolerance, and it has been applied in fields such as renewable energy generation and active power filtering. The most widely used circuit topology is the traditional three-phase bridge circuit structure consisting of six power switches, also known as H6-CSI. The most commonly used seven-segment space vector modulation sequence model of H6-CSI is as follows: Figure 3 As shown, A and B represent two different non-zero vector states, N represents the zero vector state, and T... s It refers to the modulation period. During the modulation process, all power switches inside the H6-CSI have the same modulation process and there is no essential difference in commutation operation. That is, the switching sequence of S1-S6 is exactly the same within one power frequency cycle. The H6-CSI lacks a differentiated commutation mechanism, so it is difficult to design a dynamic control method when facing a power switch that is prematurely aged.

[0004] In response to the risk of inverter component aging, traditional methods of inverter health management often rely on regular manual inspections or offline testing. When premature aging of power switching components is detected, there are usually only two options: Option 1, replace the entire module; Option 2, reduce the switching frequency to reduce switching losses.

[0005] However, its limitations are also obvious: Scheme 1 has high maintenance costs and struggles to respond promptly to the harsh development environments of new energy sources such as oceans or deserts; Scheme 2 increases harmonics due to the overall reduction in switching frequency, sacrificing power quality, and does not improve the uneven aging of power switching devices caused by long-term use, thus failing to achieve ideal maintenance results. Overall, traditional technologies have failed to effectively address the aging problem of power switches caused by long-term use, thereby limiting the lifespan and performance of current source inverters. Summarizing the technical solutions of H6-CSI, it is clear that this traditional topology limits the improvement of the commutation mechanism, especially regarding the premature aging of power switches, lacking the feasibility of designing strategies to mitigate power consumption modulation.

[0006] In recent years, among the many improvements and explorations of three-phase current source inverters, the H7 current source inverter (H7-CSI) represents a meaningful attempt. H7-CSI defines a type of current source inverter that integrates seven power semiconductor switches in the circuit, with a topology as follows: Figure 1 As shown. Compared to H6-CSI, the most obvious feature of H7-CSI is the addition of a power switch S7 to the original bridge circuit, thereby achieving more flexible DC current control capabilities. This topology provides CSI with more commutation degrees of freedom, and has great potential for improving modulation strategies. However, currently, there is still a lack of exploration regarding the aging and maintenance of the power switch for H7-CSI. Summary of the Invention

[0007] The purpose of this invention is to provide a power consumption suppression switching aging self-maintenance modulation method for current source inverters, which effectively extends the service life of current source inverters and improves their working efficiency.

[0008] To achieve the above objectives, the present invention provides the following solution:

[0009] A power consumption suppression switching aging self-maintenance modulation method for current source inverters includes:

[0010] Obtain the junction temperature of each power switch in the H7 current source inverter, and determine the power switches that are aging prematurely based on the junction temperature of each power switch.

[0011] By using the front-end power switch S7 of the H7 current source inverter, zero-current switching operation is performed on the prematurely aged power switch to achieve self-maintenance of the H7 current source inverter.

[0012] Optionally, based on the junction temperature of each power switch, the power switches that are prematurely aged include:

[0013] The junction temperature of each power switch S1-S6 of the H7 current source inverter is collected when it is working normally, and the average junction temperature is obtained.

[0014] The junction temperature of each power switch in S1-S6 is collected when the current source inverter is working. The junction temperature of the power switch is compared with the average junction temperature of a preset multiple to determine the power switch that is prematurely aged.

[0015] Optionally, performing zero-current switching operation on the prematurely aged power switch via the front-end power switch S7 of the H7 current source inverter includes:

[0016] The zero vector is obtained by turning on the front-end power switch S7;

[0017] The number of times the zero-current switching operation is performed is obtained based on the average junction temperature, the limiting junction temperature of the power switch, and the junction temperature of the prematurely aged power switch.

[0018] The zero vector is positioned between two non-zero vectors, and based on the number of zero-current switching operations, the two adjacent non-zero vector switches are combined within the zero vector interval to complete the zero-current switching.

[0019] Optionally, obtaining the number of zero-current switch operations includes:

[0020] The limiting aging factor is calculated based on the limiting junction temperature and the average junction temperature of the power switch.

[0021] The premature aging factor is calculated based on the prematurely aged power switch junction temperature and the average junction temperature.

[0022] The number of zero-current switching operations is calculated based on the limiting aging factor and the premature aging factor.

[0023] Optionally, calculating the number of zero-current switching operations includes:

[0024] ;

[0025] Where, N z β represents the number of zero-current switching operations. i α is the premature aging factor, M is the limiting aging factor, and i is the number of times the power switch performs turn-on and turn-off operations in a single sector.

[0026] Optionally, the calculation of the limiting aging factor includes:

[0027] α = T lim / T av ;

[0028] Among them, T lim It is the limiting junction temperature of the power switch, T av It is the average junction temperature of the inverter's power switches.

[0029] Optionally, the calculation of the premature aging factor includes:

[0030] β i = T i / T av ;

[0031] Among them, T i It is the junction temperature of the aging power switch.

[0032] Optionally, calculating the number of times the power switch performs an on-off operation within the single sector includes:

[0033] ;

[0034] Among them, T 工频 For the power frequency period, T s The modulation period.

[0035] The beneficial effects of this invention are as follows: In this invention, all switching losses of the current source inverter are borne by S7. By configuring high-performance semiconductor devices (such as SiC power switches) on S7, the power consumption distribution of the CSI can be reconfigured and optimized. Therefore, the strong engineering practicality of this invention is mainly reflected in two aspects: First, the technical route of this invention is low-cost and cost-effective; second, it can be directly and quickly modified based on the existing traditional H6-CSI structure. By adding a high-performance / reliable S7, performance can be efficiently improved, thus greatly facilitating practical applications and expansion. Simultaneously, this invention integrates junction temperature measurement, aging judgment, and power consumption suppression aging self-maintenance switching strategy, which is conducive to realizing intelligent management and control of the current source inverter and improving operation and maintenance efficiency. This is of great significance for improving the guarantee capability of new energy power generation equipment in remote areas. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the H7-CSI topology according to an embodiment of the present invention;

[0038] Figure 2 This is a schematic diagram of the H7-CSI space vector according to an embodiment of the present invention;

[0039] Figure 3 This is a schematic diagram of a single-cycle vector sequence model of the seven-segment spatial vector debugging strategy according to an embodiment of the present invention;

[0040] Figure 4 This is a schematic diagram of the single-modulation period vector state action model of the ZCS operation method according to an embodiment of the present invention;

[0041] Figure 5 This is a schematic diagram of the single-modulation cycle switching action sequence and its spatial vector state of the ZCS operation method according to an embodiment of the present invention;

[0042] Figure 6 This is a schematic diagram of the switching operation process of a half-modulation cycle in ZCS mode according to an embodiment of the present invention;

[0043] Figure 7 This is a schematic diagram of a power consumption suppression switching aging self-maintenance modulation method for a current source inverter according to an embodiment of the present invention. Detailed Implementation

[0044] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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 making creative efforts are within the scope of protection of the present invention.

[0045] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0046] This embodiment provides a power consumption suppression-type switch aging self-maintenance modulation method for current source inverters, including:

[0047] Obtain the junction temperature of each power switch in the H7 current source inverter, and determine the power switches that are aging prematurely based on the junction temperature of each power switch.

[0048] By using the front-end power switch S7 of the H7 current source inverter, zero-current switching operation is performed on the prematurely aging power switch, thereby realizing the self-maintenance of the H7 current source inverter.

[0049] Specifically, this embodiment is based on the H7-CSI topology circuit. By optimizing the circuit commutation process through the front-end power switch, zero-current switching operation is performed on the aging power switch to dynamically adjust the switching state and significantly reduce power consumption, thereby achieving self-maintenance and effectively extending the service life of the current source inverter and improving its working efficiency.

[0050] Furthermore, based on the junction temperature of each power switch, the power switches that are prematurely aged are identified as follows:

[0051] The junction temperature of each power switch S1-S6 of the H7 current source inverter is collected when it is working normally, and the average junction temperature is obtained.

[0052] The junction temperature of each power switch S1-S6 is collected when the current source inverter is working. The junction temperature of the power switch is compared with the average junction temperature of a preset multiple to identify the power switches that are aging prematurely.

[0053] Specifically, in this embodiment, the junction temperature of the power switch is measured using physical contact measurement, optical non-contact measurement, thermal impedance model prediction, and thermally sensitive electrical parameter method.

[0054] Furthermore, zero-current switching operation is performed on the prematurely aging power switch via the front-end power switch S7 of the H7 current source inverter, including:

[0055] The zero vector is obtained by turning on the front-end power switch S7;

[0056] The number of zero-current switching operations is obtained based on the average junction temperature, the limiting junction temperature of the power switch, and the junction temperature of the prematurely aged power switch.

[0057] The zero vector is positioned between two non-zero vectors, and based on the number of zero-current switching operations, the two adjacent non-zero vector switches are combined within the zero vector interval to complete the zero-current switching.

[0058] Specifically, under the zero-current switching (ZCS) method, the switching losses of the subsequent power switches S1-S6 are approximately zero. The switching losses caused by circuit modulation are entirely borne by power switch S7, thus achieving zero-current switching capability for power switches S1-S6. Because of the relatively high number of switching operations, S7 should be a high-performance wide-bandgap semiconductor device, such as a SiC-MOSFET, to maintain its low power consumption and reliability.

[0059] Furthermore, obtaining the number of zero-current switching operations includes:

[0060] Calculate the limiting aging factor based on the limiting junction temperature and average junction temperature of the power switch;

[0061] Calculate the premature aging factor based on the junction temperature and average junction temperature of the prematurely aged power switch.

[0062] The number of zero-current switching operations is calculated based on the limiting aging factor and the premature aging factor.

[0063] Specifically, the extreme aging condition is defined as the state where a power switch is about to completely fail due to aging. Under this extreme condition, all on-off operations of the power switch should be performed using the ZCS (Zero-Cost Switching) method. At this point, there is a limit aging factor. Premature aging coefficient β i .

[0064] Furthermore, the calculation of the number of zero-current switching operations includes:

[0065] ;

[0066] Where, N z β represents the number of zero-current switching operations. i Premature aging factor, M represents the limiting aging factor, M represents the number of times the power switch in a single sector performs an on-off operation, and i represents the inverter power switch number.

[0067] Furthermore, the calculation of the ultimate aging factor includes:

[0068] α = T lim / T av ;

[0069] Among them, T lim It is the limiting junction temperature of the power switch, T av It is the average junction temperature of the inverter's power switches.

[0070] Furthermore, calculating the premature aging factor includes:

[0071] β i = T i / T av ;

[0072] Among them, T i It is the junction temperature of the aging power switch.

[0073] Furthermore, calculating the number of times the power switch performs an on-off operation within a single sector includes:

[0074] ;

[0075] Among them, T 工频 For the power frequency period, T s The modulation period.

[0076] The method of this embodiment will be further described below with reference to the accompanying drawings:

[0077] This embodiment proposes a self-maintenance modulation method for aging power switches in a current source inverter, such as... Figure 7 As shown, the overall execution consists of two steps:

[0078] Step 1: Junction temperature measurement and aging assessment, namely: based on the H7-CSI circuit topology, obtain the junction temperature of each power switch, and evaluate the aging degree of the power switches based on the junction temperature information.

[0079] There is a very close and significant relationship between the aging degree of power switching devices and their junction temperature. As the junction temperature rises, the microstructure and material properties within the device change significantly, accelerating the aging process. For example, due to the different coefficients of thermal expansion of the materials in different layers within the module, the increased junction temperature generates varying shear stress, causing irreversible plastic deformation within the power switch. With the accumulation of deformation, cracks and voids appear at the bonding wire roots and solder layer locations. Furthermore, device aging further leads to decreased heat dissipation and increased power consumption, causing the junction temperature to rise even further, creating a vicious cycle. Therefore, the aging degree of power switching devices and their junction temperature are interdependent and mutually causal; their close relationship is crucial for ensuring the long-term stable operation of the devices. Domestic and international academic research has conducted some work on measuring the junction temperature of power switches, with commonly used methods including: physical contact measurement methods, optical non-contact measurement methods, thermal impedance model prediction methods, and thermally sensitive electrical parameter methods.

[0080] When the H7 current source inverter is operating normally and stably, the junction temperature of each power switch can be measured one by one using the method described above, and the average value of these junction temperatures can be calculated. If this average value approaches a certain constant value, then this value is recorded as the average junction temperature T. av Furthermore, by continuously monitoring the junction temperature of the power switches during the operation of the current source inverter, once a junction temperature spike is detected in a power switch... ( (where i is the power switch number) reaches or exceeds k times the average junction temperature T av ,Right now (k is the preset aging judgment coefficient), which can determine that the power switch is aging prematurely.

[0081] Step 2: Implement a power consumption suppression-type switch aging self-maintenance switching strategy. That is, implement a power consumption suppression-type switch aging self-maintenance switching strategy for power switches that have been determined to be prematurely aged, reduce the power consumption of the power switch, so as to slow down its aging process, extend its service life, and realize the self-maintenance of the current source inverter.

[0082] The power consumption suppression-type switch aging self-maintenance modulation method proposed in this embodiment is based on the H7-CSI topology circuit. It utilizes the added front-end power switch S7 to optimize the circuit commutation process and performs zero-current switching (ZCS) operation on the aging power switch to reduce its power consumption, thereby realizing self-maintenance of the current source inverter and extending its life.

[0083] The implementation conditions and specific principles of the power consumption suppression-type switch aging self-maintenance switching strategy are as follows:

[0084] 1. Hardware configuration of H7-CSI:

[0085] This embodiment is based on the H7-CSI topology, such as Figure 1 As shown in the diagram, in this circuit, the six power switches S1-S6 use components with the same rated parameters and are responsible for performing the commutation task; the power switch S7 is responsible for performing the "zero current switching" task on the aging components. Since it performs a relatively large number of switching operations, S7 should be a high-performance wide-bandgap semiconductor component, such as a SiC-MOSFET, to maintain its low power consumption level and reliability.

[0086] 2. Basic converter mode of H7-CSI (for normal operating conditions):

[0087] ① Modulation method:

[0088] H7-CSI spatial vector diagram, as shown Figure 2 As shown. Its spatial vector states include 6 non-zero vector states (I1-I6) and 4 zero vector states (I0, I7, I8, I9).

[0089] Under normal operating conditions, the H7-CSI employs a seven-segment space vector modulation strategy. Its reference vector synthesis method is identical to that of the traditional H6-CSI seven-segment space vector modulation strategy; the zero vector is not implemented via I0. The vector state action model within a standard modulation cycle is as follows: Figure 3 As shown. Where, T s This is the modulation period; A and B represent two different non-zero vector states, and N represents the zero vector state. In this state, the zero vector state does not need to be implemented by I0. As the reference vector rotates between sectors, the correspondence of their composite vectors is shown in Table 1.

[0090] Table 1: Space Vector Selection Method under Basic Converter Mode

[0091]

[0092] ② Number of times to activate / deactivate:

[0093] Within a complete power frequency cycle, a given power switch will perform switching operations in three sectors (e.g., the switching operation of S1 occurs in sectors II, IV, and VI). Within a single modulation cycle, the power switch needs to perform two on-off operations. Therefore, the number of on-off operations, M, performed by a given power switch within a single sector can be calculated using the following formula.

[0094] ;

[0095] in, T 工频 That is, the power frequency period, multiplied by one-sixth, gives the time it takes for the reference vector to rotate through one sector; T sThe modulation period.

[0096] 3. Implementation of zero-current switching operation of H7-CSI:

[0097] In the space vector of H7-CSI, the zero vector can be achieved by turning on S7, i.e., executing I0. When the AC side power factor angle is less than ±30°, S7 can short-circuit the subsequent circuit. At this time, only S7 flows through H7-CSI, and the current flowing through the other power switches is zero.

[0098] The zero-current switching operation method involves placing the zero vector (I0) between two non-zero vectors, ensuring that the zero vector covers the switching edges of the two preceding and following non-zero vectors. This allows the switching combination of two adjacent non-zero vectors to complete zero-current switching within the zero vector interval. The vector state action model within a single modulation cycle is as follows: Figure 4 As shown. Where, T s The modulation period is represented by A and B, which represent two different non-zero vector states, and N represents the zero vector state. The correspondence between the reference vector and its synthesized vector in different sectors during ZCS operation is shown in Table 2.

[0099] Table 2: Method for Selecting Space Vectors for ZCS Operations in H7-CSI

[0100]

[0101] Taking the premature aging of S6 as an example, focusing on its switching operation in sector I, the single-modulation cycle switching action sequence of the ZCS operation method to be executed and the corresponding space vector state are as follows: Figure 5 As shown, when switch S7 is turned on, it can short-circuit the subsequent circuit, forcing H7-CSI to execute zero vector I0 (corresponding to...). Figure 4 The zero vector N in the equation); when switch S7 is in the non-conducting state, the switch combinations {S1, S6} and {S1, S2} execute the non-zero vectors I6 and I1 respectively (corresponding to the zero vector N in the equation). Figure 4 (Non-zero vector A and non-zero vector B in the equation). I0 lies between I6 and I1, and the switch combinations corresponding to I6 and I1 can complete zero-current switching within the I0 interval. Taking half a modulation cycle as an example, Figure 6 The diagram illustrates the operation of the relevant switches. The conducting segment of S7 overlaps before and after the point where S6 needs to be turned on or off, thus enabling S6 to perform zero-current switching. The switching situation for the remaining half-cycle is symmetrical and follows the same principle. The corresponding switching time points t are shown. a t n1 and t n2 It can be calculated as follows.

[0102] ;

[0103] In the formula, T s T0 is the modulation period, which is the duration of the zero vector within a single modulation period. T1 and T2 are the durations of two different non-zero vectors, respectively.

[0104] Therefore, under the ZCS operation method, the switching losses of the subsequent power switches S1-S6 are approximately zero, and the switching losses caused by circuit modulation are entirely borne by power switch S7. Power switches S1-S6 achieve zero-current switching capability. Since power switch S7 uses a high-performance SiC-MOSFET, its power consumption can be maintained at a low level.

[0105] 4. Number of times the ZCS operation of the aging switch is executed within a single sector:

[0106] The extreme aging condition is defined as the state where a power switch is about to completely fail due to aging. Under this extreme condition, all on-off operations of the power switch should be performed using the ZCS (Zero-Cost Switching) method. At this point, there is a limit aging factor. This can be expressed as: α = T lim / T av T lim It is the limiting junction temperature of the power switch, T av It is the average junction temperature of the inverter's power switches.

[0107] Define the premature aging factor β i , can be expressed as: β i = T i / T av T i This is the junction temperature of the aging power switch, and i is the number of the inverter power switch (i = 1, 2, 3……6). Clearly, β... i ≥k.

[0108] For power switches (S1~S6) identified as prematurely aged, a power consumption suppression aging self-maintenance switching strategy can be implemented. This involves redistributing the switching modulation sequence according to the degree of premature aging, causing some modulation cycles to operate in ZCS mode, thereby extending the lifespan of the power switch. The number of ZCS operations for this aged power switch is based on... The proportional relationship is determined; specifically, within one-sixth of the power frequency cycle (corresponding to one sector of the spatial vector diagram), the number of ZCS operations N that the power switch needs to perform is determined. z It can be determined by the following formula.

[0109] ;

[0110] The number of ZCS on-off operations can be calculated similarly for the other two sectors where the power switch needs to operate. It's important to note that the ZCS operation is only performed on the power switch determined to be prematurely aging; the other power switches maintain their original modulation modes.

[0111] Taking switch S6 as an example, it performs switching actions in three sectors: I, III, and V. In sectors I and V, it's a non-zero vector action, while in sector III, it's a zero vector action. In sector I, the number M of times the power switch S6 performs a ZCS operation can be determined by… Received. If S6 has been determined to be prematurely aged, its junction temperature... and average junction temperature The relationship between them can be represented as: Therefore, within sector I, the number of times the ZCS operation needs to be performed on S6 is N. z can be Similarly, the number of ZCS operations performed in sectors III and V can be derived.

[0112] Overall, the schematic diagram of the power switch aging self-maintenance modulation method for current source inverters is as follows: Figure 7 As shown, the aging self-maintenance of the power switch of the current source inverter can be completed by performing two steps: junction temperature measurement and judgment, and power consumption suppression aging self-maintenance switching strategy.

[0113] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A power consumption suppression-type switch aging self-maintenance modulation method for current source inverters, characterized in that, include: Obtain the junction temperature of each power switch in the H7 current source inverter, and determine the power switches that are aging prematurely based on the junction temperature of each power switch. By using the front-end power switch S7 of the H7 current source inverter, zero-current switching operation is performed on the prematurely aging power switch to achieve self-maintenance of the H7 current source inverter, including: The zero vector is obtained by turning on the front-end power switch S7; The number of zero-current switching operations is obtained based on the average junction temperature, the limiting junction temperature of the power switch, and the junction temperature of the prematurely aged power switch. The zero vector is positioned between two non-zero vectors, and based on the number of zero-current switching operations, the two adjacent non-zero vector switches are combined within the zero vector interval to complete the zero-current switching.

2. The power consumption suppression switching aging self-maintenance modulation method for current source inverters according to claim 1, characterized in that, Based on the junction temperature of each power switch, the power switches that are prematurely aged are identified as follows: The junction temperature of each power switch S1-S6 of the H7 current source inverter is collected when it is working normally, and the average junction temperature is obtained. The junction temperature of each power switch in S1-S6 is collected when the current source inverter is working. The junction temperature of the power switch is compared with the average junction temperature of a preset multiple to determine the power switch that is prematurely aged.

3. The power consumption suppression switching aging self-maintenance modulation method for current source inverters according to claim 1, characterized in that, The number of zero-current switch operations is obtained by: The limiting aging factor is calculated based on the limiting junction temperature and the average junction temperature of the power switch. The premature aging factor is calculated based on the prematurely aged power switch junction temperature and the average junction temperature. The number of zero-current switching operations is calculated based on the limiting aging factor and the premature aging factor.

4. The power consumption suppression switching aging self-maintenance modulation method for current source inverters according to claim 3, characterized in that, The calculation of the number of zero-current switch operations includes: ； Where, N z β represents the number of zero-current switching operations. i α is the premature aging factor, M is the limiting aging factor, and i is the number of times the power switch performs turn-on and turn-off operations in a single sector.

5. The power consumption suppression switching aging self-maintenance modulation method for current source inverters according to claim 4, characterized in that, The calculation of the limiting aging factor includes: α = T lim / T av ; Among them, T lim It is the limiting junction temperature of the power switch, T av It is the average junction temperature of the inverter's power switches.

6. The power consumption suppression switching aging self-maintenance modulation method for current source inverters according to claim 5, characterized in that, Calculating the premature aging factor includes: β i = T i / T av ; Among them, T i It is the junction temperature of the aging power switch.

7. The power consumption suppression switching aging self-maintenance modulation method for current source inverters according to claim 4, characterized in that, The calculation of the number of times the power switch in the single sector performs an on-off operation includes: ； Among them, T 工频 For the power frequency period, T s The modulation period.

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