A short circuit detection system without current sensor

Abstract

The application relates to a short-circuit detection system without a current sensor and belongs to the field of power electronic control. The system is characterized in that: the sampled voltage is transformed into a rotating coordinate system voltage through a Clark transformation module and a Park transformation module; the voltage in the rotating coordinate system is input into a phase-locked loop to obtain the frequency and voltage angular velocity of the system; the Park-transformed voltage and the voltage angular velocity obtained by the phase-locked loop are input into a notch filter to obtain a positive sequence voltage; the positive sequence voltage is transformed through a Park inverse transformation module and a Clark inverse transformation module and is subtracted from a three-phase voltage to obtain a voltage component caused by the short circuit; the three-phase voltage is input into a fault judgment module through a differential detection module, and the negative sequence voltage is used to judge the short-circuit condition. The application simplifies the hardware system and reduces the system cost.

Description

Technical Field

[0001] This invention belongs to the field of power electronic control and relates to a short-circuit detection system without a current sensor. Background Technology

[0002] Power electronic converters are widely used in various applications. To prevent short-circuit faults in the converter, current sensors and other current-detecting components are usually added to the input or output terminals of the converter to effectively handle short-circuit faults.

[0003] This conventional method requires adding hardware circuitry for current detection, which increases the cost and installation difficulty of the detection system. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a short circuit detection system without current sensors, which determines whether a short circuit fault has occurred by using a voltage detection device in the system without adding hardware such as a current detection device.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A short-circuit detection system without a current sensor includes a Clark converter module, a Park converter module, a phase-locked loop module, a notch filter module, an inverse Park converter module, an inverse Clark converter module, a voltage differential module, and a fault diagnosis module.

[0007] The Clark conversion module is used to convert the detected actual value U of the three-phase voltage. a U b and U c Voltage U transformed into α-β coordinate system α and U β ;

[0008] The phase-locked loop module is used to input the voltage U in the two-phase stationary axis coordinate system. d and U q The transformation is converted into coordinate transformation angle θ and voltage rotational angular velocity ω;

[0009] The Park transformation module is used to transform the input voltage U in the α-β coordinate system. α and U β And the coordinate transformation angle θ, transforming it into voltage U in a two-phase stationary axis coordinate system. d and U q ;

[0010] The notch filter module is used to convert the input voltage U in the two-phase stationary axis coordinate system. d and U qThe voltage rotational angular velocity ω is transformed into the positive sequence voltage U in a two-phase stationary axis coordinate system. pd and U pq ;

[0011] The Park inverse transform module is used to transform the input voltage U in the two-phase stationary axis coordinate system. pd and U pq And the coordinate transformation angle, transforming it into voltage U in a two-phase rotating axis coordinate system. pα and U pβ ;

[0012] The Clark inverse transform module converts the input voltage U in a two-phase rotating axis coordinate system. pα and U pβ Transformed into the positive sequence voltage U in the standard coordinate system pa U pb and U pc ;

[0013] The voltage differentiating module is used to convert the input three-phase voltage value U a U b and U c and the voltage U in the two-phase stationary axis coordinate system d and U q By performing differentiation, we obtain the differentiated value U of the three-phase voltage. a '、U b '、U c The value U after differentiating the two-phase voltages d 'and U q ';

[0014] The fault determination module is used to determine the fault based on the input positive sequence voltage U. pa U pb and U pc With three-phase voltage U a U b and U c The difference U na U nb and U nc The value U after the voltage derivative a '、U b '、U c '、U d 'and U q Determine if a short circuit has occurred.

[0015] Furthermore, the specific operation method of the phase-locked loop module is as follows: The input U... qThe difference obtained by subtracting from 0 is controlled by proportional-integral control, and the output result is the rotational angular velocity ω. The remainder of the rotational angular velocity ω and 2π is the rotational coordinate transformation angle θ. This rotational coordinate transformation angle θ is used as input to the Park transformation module, and the rotational angular velocity ω is used as input to the notch filter module.

[0016] Furthermore, the specific operation method of the notch filter module is as follows: d-axis voltage U d The voltage U is obtained by rotating the coordinate system twice, ω0 = 2 × ω. 2d q-axis voltage U q The voltage U is obtained by rotating the coordinate system twice, ω0 = 2 × ω. 2q U 2d with U 2q respectively and U d and U q The difference is used to obtain the positive sequence voltage U in the two-phase stationary axis coordinate system. pd and U pq .

[0017] Furthermore, the fault judgment module uses the following judgment method: U d 'and U q The counting begins when the value of ' is not zero, and the determination formula is:

[0018]

[0019] If any of the above three situations occur, a short circuit will occur in the system.

[0020] Furthermore, when U na ≠0 and |U' a When | > 1, the fault diagnosis module will determine that a short circuit has occurred in phase A; similarly, when U nb ≠0 and |U' b When |>1, the fault diagnosis module will determine that a short circuit has occurred in phase B. When U nc ≠0 and |U' c When |>1, the fault diagnosis module will determine that a short circuit has occurred in phase C.

[0021] The beneficial effects of this invention are as follows: Without current sensors or other current detection components, and without adding other hardware circuits (simplifying the hardware system and reducing system costs), this invention can effectively detect short circuits in the system. Based on the original voltage detection, it uses voltage differentiation processing and negative sequence voltage detection to determine whether a short circuit has occurred.

[0022] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0024] Figure 1 This is a structural diagram of the current sensorless short-circuit detection system of the present invention. Detailed Implementation

[0025] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0026] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0027] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0028] Please see Figure 1This invention provides a preferred sensorless short-circuit detection system, comprising: a Clark transform module, a Park transform module, a phase-locked loop module, a notch filter module, a voltage differentiator module, an inverse Park transform module, an inverse Clark transform module, and a fault diagnosis module. In this system, since current information cannot be acquired, voltage information is used to determine whether a short circuit has occurred. When a short circuit occurs, the voltage slope increases, and a negative sequence voltage is generated; therefore, this component needs to be separated as the basis for short-circuit detection.

[0029] The workflow of the short-circuit detection method without current sensors in the above system is as follows:

[0030] 1) Actual value of three-phase voltage U a U b and U c The voltage U is transformed into the α-β coordinate system by the Clark transformation module. α and U β The calculation formula is:

[0031]

[0032] 2) Voltage U in the α-β coordinate system α and U β After being transformed by the Park transformation module, it is converted into voltage U in a two-phase stationary axis coordinate system. d and U q The calculation formula is:

[0033]

[0034] The angle θ required for the Park transformation is output from the phase-locked loop module to the Park transformation module.

[0035] 3) The phase-locked loop module will input U d and U q The frequency of the voltage and the rotational coordinate transformation angle θ are obtained through transformation. The specific operation method is as follows: input U q The difference obtained by subtracting from 0 is controlled by proportional-integral control, and the output result is the rotational angular velocity ω. The remainder of the rotational angular velocity ω and 2π is the rotational coordinate transformation angle θ. This rotational coordinate transformation angle θ is used as input to the Park transformation module, and the rotational angular velocity ω is used as input to the notch filter module.

[0036] 4) The rotational angular velocity ω is input to the notch filter module. The specific operation method of the notch filter module is as follows: the d-axis voltage is obtained by rotating the coordinate system twice, ω0 = 2 × ω. 2d The q-axis voltage is obtained by rotating the coordinate system twice, ω0 = 2 × ω, to obtain the voltage U. 2q U 2d with U2q respectively and U d and U q The difference is used to obtain the positive sequence voltage U in the two-phase stationary axis coordinate system. pd and U pq ;

[0037] 5)U pd and U pq As input to the Park inverse transform module, the positive-sequence voltage U in the α-β coordinate system is obtained. pα and U pβ The calculation formula is:

[0038]

[0039] 6)U pα and U pβ The positive-sequence voltage U in the standard coordinate system is obtained by inputting it to the Clark inverse transform module. pa U pb and U pc The calculation formula is:

[0040]

[0041] 7) The voltage differentiating module will input the three-phase voltage value U a U b and U c By performing differentiation, we obtain the differentiated value U of the three-phase voltage. a '、U b 'and U c The calculation formula is:

[0042]

[0043] 8) Positive sequence voltage U pa U pb and U pc With three-phase voltage U a U b and U c The difference U na U nb and U nc The value U after differentiation from the three-phase voltage a '、U b 'and U c This information is input to the fault diagnosis module to determine whether a short circuit has occurred in the system. The specific diagnosis method is as follows:

[0044]

[0045] When U na ≠0 and |U' aWhen | > 1, the fault diagnosis module will determine that a short circuit has occurred in phase A; similarly, when U nb ≠0 and |U' b When |>1, the fault diagnosis module will determine that a short circuit has occurred in phase B. When U nc ≠0 and |U' c When |>1, the fault diagnosis module will determine that a short circuit has occurred in phase C.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A short-circuit detection system without a current sensor, characterized in that, The system includes a Clark transform module, a Park transform module, a phase-locked loop module, a notch filter module, a Park inverse transform module, a Clark inverse transform module, a voltage differentiation module, and a fault diagnosis module; The Clark conversion module is used to convert the detected actual values ​​of the three-phase voltages. , and Voltage transformed into α-β coordinate system and ; The phase-locked loop module is used to process the input voltage in the two-phase stationary axis coordinate system. and Transformation into coordinate transformation angle and voltage rotational angular velocity ; The Park transformation module is used to transform the voltage in the input α-β coordinate system. and and coordinate transformation angle Transformed into voltage in a two-phase stationary axis coordinate system and ; The notch filter module is used to convert the input voltage in the two-phase stationary axis coordinate system. and and voltage rotational angular velocity Transformed into positive sequence voltage in a two-phase stationary axis coordinate system and ; The Park inverse transform module is used to transform the input voltage in the two-phase stationary axis coordinate system. and And the coordinate transformation angle, transforming it into voltage in a two-phase rotating axis coordinate system. and ; The Clark inverse transform module converts the input voltage in a two-phase rotating axis coordinate system. and Transformed into positive sequence voltage in standard coordinate system , and ; The voltage differentiating module is used to convert the input three-phase voltage values , and Voltage in a two-phase stationary axis coordinate system and By performing differentiation, we obtain the differentiated values ​​of the three-phase voltages. , , The value after differentiating the two-phase voltages and ; The fault determination module is used to determine the fault based on the input positive sequence voltage. , and With three-phase voltage , and The difference , and The value after the voltage derivative , , , and To determine if a short circuit has occurred, the specific method is as follows: and Counting begins when the value is not zero, and the determination formula is: If any of the above three situations occur, a short circuit will occur in the system.

2. The short-circuit detection system according to claim 1, characterized in that, The specific operation method of the phase-locked loop module is as follows: input... The difference obtained by subtracting from 0 is used for proportional-integral control, and the output result is the rotational angular velocity. , rotational angular velocity and The remainder is the rotational coordinate transformation angle. Transform this coordinate system by angle The rotational angular velocity is input to the Park transform module. It is used as input to the notch filter module.

3. The short-circuit detection system according to claim 1, characterized in that, The specific operation method of the notch filter module is as follows: d-axis voltage After two coordinate system rotations Obtain voltage q-axis voltage After two coordinate system rotations Obtain voltage , and Separately and and The difference is used to obtain the positive sequence voltage in the two-phase stationary axis coordinate system. and .

4. The short-circuit detection system according to claim 1, characterized in that, when When this happens, the fault diagnosis module will determine that a short circuit has occurred in phase A; Similarly, when When the fault diagnosis module determines that a short circuit has occurred in phase B, When this happens, the fault diagnosis module will determine that a short circuit has occurred in phase C.

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