This application claims priority to Chinese Patent Application No. 202410984276.1 with a filing date of Jul. 22, 2024. The content of the aforementioned application, including any intervening amendments thereto, is incorporated herein by reference.
The present disclosure relates to the technical field of fault diagnosis of electronic converters, and in particular, to an open-circuit fault diagnosis method for a silicon (Si)/silicon carbide (SiC) hybrid H-bridge inverter power device.
High-power inverters are widely used in the fields such as renewable energy generation, flexible alternating current transmission, and motor driving. A Si/SiC hybrid parallel switch structure has become one of the most competitive power devices among the high-power inverters by virtue of advantages such as high performance, high efficiency, and cost-effectiveness. A power device is a core part of the inverter, and an open-circuit fault of the power device may significantly impair the continuity and reliability of power supplied to equipment.
Currently, main diagnosis methods for the open-circuit fault of the power device of the inverter are classed into a current-based diagnosis method and a voltage-based diagnosis method. The current-based diagnosis method typically uses a phase current, neutral point current, or a current residual to detect the open-circuit fault. However, a Si/SiC hybrid device is typically driven by a new driving method, and involves more complicated current changes. The conventional current-based diagnosis method is not directly applicable to the Si/SiC hybrid device. The voltage-based diagnosis method is based on direct voltage measurement or pulse counting, thereby improving the response speed. However, most voltage-based diagnosis methods rely on an additional hardware circuit, thereby increasing cost. To achieve both speed and economic viability, a diagnosis method that constructs a voltage circuit model by considering a plurality of calculation errors has been put forward. However, the electrical quantities of a faulty hybrid device exhibit new forms and characteristics, and the fault symptoms are in a multi-coupled mapping relationship with the faulty devices. Consequently, the existing voltage model-based diagnosis method is not applicable to the Si/SiC hybrid inverter, and is unable to meet the requirements of reliable operation of the high-power inverter.
Therefore, a new technical solution is urgently needed to solve the technical problem that the existing open-circuit fault diagnosis method for the power device is hardly applicable to the Si/SiC hybrid inverter.
The present disclosure provides an open-circuit fault diagnosis method for a Si/SiC hybrid H-bridge inverter power device to solve the technical problem that the existing open-circuit fault diagnosis method for the power device is hardly applicable to the Si/SiC hybrid inverter.
To achieve the above objective, the present disclosure provides an open-circuit fault diagnosis method for a Si/SiC hybrid H-bridge inverter power device, including the following steps:
Preferably, the step S1 includes:
Preferably, the step S2 includes:
The collecting inverter data includes: collecting a reference modulation voltage uref, a load voltage uL, a load current iL, an inductor current i1, a DC-side voltage Udc, a switching cycle Ts, dead time TDD, delay time TDL, and inductor parameter Lf of the inverter.
Preferably, the step S2 further includes:
wherein, u1 represents an output voltage of an inverter port, and is expressed by the following relation:
Preferably, the step S2 further includes: using the following relation to represent a simplified discrete form of u1:
wherein, i1[n] represents an inductor current at the nth sampling moment, i1[n−1] represents an inductor current at the (n−1)th sampling moment, uL[n] represents a load voltage at the nth sampling moment, and uL[n−1] represents a load voltage at the (n−1)th sampling moment.
Preferably, the step S2 further includes:
wherein, y represents a function value, xi represents a variable that causes a function change, σxi represents an error of each variable xi, and εy represents a calculation error.
Preferably, the step S2 further includes: obtaining the calculation error ε1 caused parameters and sampling in consideration of a sampling error value of a current and an inductor measurement error value in a model, and using the following relation to represent the calculation error:
wherein, σLf represents a maximum error at time of selecting an inductance; σi1, σuL, and σiL represent maximum sampling errors of an inductor current i1, a load voltage uL, and a load current iL, respectively; i1[n] represents an inductor current at the nth sampling moment; and i1[n−1] represents an inductor current at the (n−1)th sampling moment.
Preferably, the step S2 further includes: using the following relation to represent a calculation error ε2 caused by a dead zone and a delay:
wherein, Udc represents a direct-current-side voltage, TS represents a switching frequency, TDD represents a dead time, and TDL represents a delay time.
Preferably, the method further includes:
wherein, uref1 represents an upper half wave of a reference voltage; uref2 represents a lower half wave of the reference voltage; Δudetect1 represents a first threshold detection region, and Δudetect1 represents a second threshold detection region.
Preferably, the method further includes:
The determining whether the first output voltage residual enters a voltage threshold diagnosis region in the step S2 includes:
The determining whether the second output voltage residual enters a voltage threshold diagnosis region in the step S3 includes:
A corresponding fault flag is empty when no corresponding determining process is performed.
Preferably, the step S4 includes:
Preferably, the determining whether the first inductor current pulsation value pulsates within an inductor current pulsation region in the step S4 includes:
A corresponding fault flag is empty when no corresponding determining process is performed.
Preferably, the step S5 includes:
The present disclosure achieves at least the following beneficial effects:
The open-circuit fault diagnosis method for the Si/SiC hybrid H-bridge inverter power device according to the present disclosure uses the inverter output voltage residual and the inductor current pulsation value as diagnosis variables, without a need to add additional sensors, thereby reducing cost. The fault characteristics are amplified by calculating the voltage residual and the inductor current pulsation value. At the moment of the fault occurrence, the diagnosis variable changes significantly in a working range of the faulty switch transiently. In this way, the method provides a reliable dynamic indicator to ensure the diagnosis speed of the algorithm. By quantitatively analyzing the relationship between the voltage residual and the detection threshold in a case of an open-circuit fault of the device, the present disclosure implements accurate positioning of the faulty power device. The method of the present disclosure is applicable to Si/SiC hybrid inverters, and provides a reliable fault diagnosis method for the Si/SiC hybrid inverters.
The present disclosure also achieves other objectives, features, and advantages in addition to the objectives, features, and advantages described above. The following describes the present disclosure in further detail with reference to accompanying drawings.
The drawings that constitute a part of the present disclosure are intended to enable a further understanding of the present disclosure. The exemplary embodiments of the present disclosure and the description thereof are intended to explain the present disclosure but without constituting any undue limitation on the present disclosure. In the drawings:
The embodiments of the present disclosure are described in detail below with reference to accompanying drawings, but the present disclosure may be implemented in many different ways as defined and covered by the claims.
Referring to
In step S1, a first switching sequence is injected into a second driving mode of the power device at intervals of a preset period. The second driving mode includes a SiC MOSFET first-on and then-off mode. Step S1 specifically includes the following substeps.
Referring to
The first switching sequence is injected into the second driving mode of the power device at a frequency that the first switching sequence is injected in two switching cycles every N switching cycles, where 8≤N≤12, and N is a positive integer.
In a preferred embodiment of the present disclosure, on the premise of ensuring normal operation of the inverter, the periodic injection of the first switching sequence is conducive to distinguishing similar characteristics of the open-circuit fault of the power device, thereby improving the reliability of the diagnosis strategy.
In step S2, inverter data is collected, and an output voltage residual is calculated to obtain a first output voltage residual. It is determined whether the first output voltage residual enters a voltage threshold diagnosis region, and a first fault flag is obtained. The process goes to step S3 when the first output voltage residual enters the voltage threshold diagnosis region, or, the process goes to step S4 when the first output voltage residual is outside the voltage threshold diagnosis region. The step S2 specifically includes the following substeps.
The step of collecting inverter data includes: collecting a reference modulation voltage uref, a load voltage uL, a load current iL, an inductor current i1, a DC-side voltage Udc, a switching cycle Ts, dead time TDD, delay time TDL, and inductor parameter Lf of the inverter.
In a preferred embodiment of the present disclosure, the Si/SiC hybrid H-bridge inverter structure and the inverter data are shown in
The output voltage residual Δu may be represented by the following relation:
wherein, u1 represents an output voltage of an inverter port, and is expressed by the following relation:
The following relation is used for representing a simplified discrete form of u1:
wherein, i1[n] represents an inductor current at the nth sampling moment, i1[n−1] represents an inductor current at the (n−1)th sampling moment, uL[n] represents a load voltage at the nth sampling moment, and uL[n−1] represents a load voltage at the (n−1)th sampling moment.
The following relation is used for representing the output voltage residual Δu in consideration of a calculation error caused by parameters and sampling in a process of calculating the output voltage residual:
wherein, y represents a function value, xi represents a variable that causes a function change, σxi represents an error of each variable xi, and εy represents a calculation error.
The calculation error ε1 caused parameters and sampling is obtained in consideration of a sampling error value of a current and an inductor measurement error value in a model, and the following relation is used for representing the calculation error:
wherein, σLf represents a maximum error at time of selecting an inductance; σi1, σuL, and σiL represent maximum sampling errors of an inductor current i1, a load voltage uL, and a load current iL, respectively; i1[n] represents an inductor current at the nth sampling moment; and i1[n−1] represents an inductor current at the (n−1)th sampling moment.
The following relation is used for representing a calculation error ε2 caused by a dead zone and a delay:
wherein, Udc represents a direct-current-side voltage, TS represents a switching frequency, TDD represents a dead time, and TDL represents a delay time.
In a preferred embodiment of the present disclosure, the calculation errors caused by sampling, parameters, dead zones, and delays are considered, and an adaptive threshold diagnosis region is designed, thereby eliminating the modeling errors caused by the establishment of a voltage residual model and further improving the accuracy of the diagnosis strategy.
The voltage threshold diagnosis region may be represented by the following relation:
wherein, uref1 represents an upper half wave of a reference voltage; uref2 represents a lower half wave of the reference voltage; Δudetect1 represents a first threshold detection region, and Δudetect1 represents a second threshold detection region.
The step of determining whether the first output voltage residual enters a voltage threshold diagnosis region in the step S2 includes the following substeps:
In step S3, the first switching sequence is injected into an all-driving mode of the power device. Inverter data is collected again, and an output voltage residual is calculated to obtain a second output voltage residual. It is determined whether the second output voltage residual enters the voltage threshold diagnosis region, and a second fault flag is obtained.
Referring to
First driving mode: When the current falls within the range of 0 to I1, the SiC MOSFET is turned on alone.
Second driving mode: When the current falls within the range of I1 to I2, the SiC MOSFET is turned on and then off.
Third driving mode: When the current is greater than I2, the Si IGBT is turned on and then off.
In a preferred embodiment of the present disclosure, some power devices generate similar voltage residual characteristics after occurrence of an open-circuit fault. It is difficult to precisely locate the faulty power device based on the first output voltage residual alone. To further locate the power device with an open-circuit fault, the first switching sequence is injected into the all-driving mode of the power device to improve the accuracy of the diagnosis strategy.
The step of determining whether the second output voltage residual enters a voltage threshold diagnosis region in the step S3 includes the following substeps:
A corresponding fault flag is empty when no corresponding determining process is performed.
In the step S4, inverter data is collected and an inductor current pulsation value is calculated to obtain a first inductor current pulsation value. It is determined whether the first inductor current pulsation value pulsates within an inductor current pulsation region, and a third fault flag is obtained. Step S4 specifically includes the following substeps:
The following relation is used for representing the inductor current pulsation value Δikm:
The inductor current pulsation region Δidetect is obtained in consideration of the calculation error ε1 caused by parameters and sampling as well as the calculation error ε2 caused by a dead zone and a delay, and using the following relation to represent the inductor current pulsation region:
In a preferred embodiment of the present disclosure, the pulsation value of the inductor current under normal working conditions may be estimated by the above formula, thereby constructing an inductor current pulsation region, indicating that the inductor current fluctuates within the region under normal conditions. After an open-circuit fault occurs, due to abnormal charging and discharging of the inductor, the inductor pulsation will depart from the pulsation region, thereby enabling fault diagnosis.
The step of determining whether the first inductor current pulsation value pulsates within an inductor current pulsation region in the step S4 includes the following substeps:
A corresponding fault flag is empty when no corresponding determining process is performed.
In S5, open-circuit fault diagnosis is performed on the power device based on the first fault flag, the second fault flag, and the third fault flag. Step S5 specifically includes the following substep:
Positioning of a specific faulty fully-controlled device is performed to obtain specific fault information based on different value combinations of the first fault flag, the second fault flag, and the third fault flag, as shown in Table 1.
To better demonstrate the effectiveness of the fully-controlled device fault diagnosis method disclosed herein, a Si/SiC hybrid H-bridge inverter model is built in MATLAB/Simulink. The injection of the power device switch signal is stopped at a specified moment to simulate the open-circuit fault of the power device, so as to simulate the diagnosis of the open-circuit fault of the relevant fully-controlled device. Table 2 shows the specific circuit simulation parameters.
Referring to
Referring to
The open-circuit fault diagnosis method for the Si/SiC hybrid H-bridge inverter power device according to a preferred embodiment of the present disclosure uses the inverter output voltage residual and the inductor current pulsation value as diagnosis variables, without a need to add additional sensors, thereby reducing cost. The fault characteristics are amplified by calculating the voltage residual and the inductor current pulsation value. At the moment of the fault occurrence, the diagnosis variable changes significantly in a working range of the faulty switch transiently. In this way, the method provides a reliable dynamic indicator to ensure the diagnosis speed of the algorithm. By quantitatively analyzing the relationship between the voltage residual and the detection threshold in a case of an open-circuit fault of the device, the present disclosure implements accurate positioning of the faulty power device. The method of the present disclosure is applicable to Si/SiC hybrid inverters, and provides a reliable fault diagnosis method for the Si/SiC hybrid inverters.
What is described above is merely exemplary embodiments of the present disclosure, but is not intended to limit the present disclosure. To a person skilled in the art, various modifications and variations may be made to the present disclosure. Any and all modifications, equivalent replacements, improvements, and the like made without departing from the essence and principles of the present disclosure still fall within the protection scope of the present disclosure.
Number | Date | Country | Kind |
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202410984276.1 | Jul 2024 | CN | national |