A Calculation Method for Armature Magnetomotive Force of a Five-Phase Motor Adopting Star-Pentagon Connection

Abstract

The present invention discloses a method for calculating the armature magnetomotive force of a five-phase motor using a star-pentagram connection, which relates to the field of calculating the armature magnetomotive force of single-layer winding and double-layer winding five-phase motors. It includes: dividing a single-phase armature winding into a star-shaped partial winding and a pentagram partial winding, and the calculation steps include: calculating the magnetomotive force of the star-shaped partial winding, calculating the magnetomotive force of the pentagram partial winding, and calculating the resultant magnetomotive force. This method can accurately calculate the armature magnetomotive force of a five-phase induction motor using a star-pentagram connection. Further analyze which high-order harmonic magnetomotive forces are eliminated by the star-pentagram winding compared with a single star-shaped winding and a pentagram winding in terms of armature magnetomotive force. Further analyze the characteristics of the motor such as losses and vibrations.

Description

Technical Field

[0001] The present invention relates to the field of single-layer windings and double-layer winding five-phase motors, and particularly to a method for calculating the armature magnetomotive force of a five-phase motor using a star-star connection method. Background Art

[0002] With the rapid development of motor technology, the requirements for motor stability are getting higher and higher, especially for the drive devices of military equipment. Multi-phase motors have developed rapidly. Multi-phase motors have the advantages of high reliability, simple structure, and easy maintenance, and have now become the first choice for large-capacity motors. Compared with traditional three-phase asynchronous motors, five-phase motors have more advantages, especially in terms of fault tolerance. Five-phase motors have more motor phases, more phase number redundancy, and further improved control performance. When a certain phase fails, the five-phase motor can be adjusted through the control circuit, and the motor can still operate under load. The five-phase motor has more phases than the three-phase motor. The increase in the number of winding phases can reduce the phase transition between windings. Therefore, the harmonics of the five-phase motor are reduced and the amplitude is decreased. The iron loss of the motor is reduced, the electromagnetic torque of the motor is improved, the noise and vibration of the motor are reduced, and it has good environmental protection value. The star-star winding connection method eliminates the 9th and 11th harmonics compared with the single-star winding connection method and the star-star winding connection method. This can be verified through the calculation of the armature magnetomotive force of the star-star winding connection method. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for calculating the armature magnetomotive force of a five-phase motor using a star-star connection method. By changing the connection method of the armature winding, for a five-phase motor with a stator winding having a given turn ratio and a mechanical angle difference, the low-order harmonics in the armature magnetomotive force can be eliminated, thereby reducing the core loss and improving the motor efficiency.

[0004] The present invention adopts the following technical solutions to solve the above technical problems:

[0005] A method for calculating the armature magnetomotive force of a five-phase motor using a star-star connection method, characterized by comprising the following steps:

[0006] Step 1: For a five-phase motor using a star-star connection method, divide each phase winding into a star-shaped part winding and a star-star part winding;

[0007] Step 2: Take the total number of turns of a single-phase armature winding as N S = N star + N pentacle , where N star , N pentacle are the number of turns of the star-shaped part winding and the number of turns of the star-star part winding respectively;

[0008] Step 3: To ensure that the magnetomotive forces generated by the star-shaped part winding and the pentagram-shaped part winding are of the same magnitude, according to the equal ampere-turn law, the relationships among the voltages, currents, and turns of the two windings are as follows:

[0009]

[0010] In the formula, M is the modulation ratio; w s is the angular velocity; V DC is the line voltage per phase.

[0011] Step 4: Since the current waveform is non-sinusoidal, the Fourier decomposition is performed on the current of each phase winding respectively. The current of each phase of the star-shaped winding is:

[0012]

[0013] Step 5: Combining the phase and amplitude relationships of the armature winding currents in the star-pentagram connection, the magnetomotive force of the star-shaped part winding of the five-phase motor is obtained as:

[0014]

[0015] The magnetomotive force of the pentagram-shaped part winding is:

[0016]

[0017] In the formula, ν is the space harmonic order, μ is the time harmonic order, θ α is the mechanical angle difference in the spatial arrangement between the pentagram winding and the star-shaped winding, F μν is the magnetomotive force amplitude, w is the current frequency, and t is the time.

[0018] Step 6: The sum of the magnetomotive forces of the star-shaped part winding and the pentagram-shaped part winding is:

[0019]

[0020] Advantages of the present invention: By changing the winding connection method, the low-order harmonics in the armature magnetomotive force can be suppressed, the motor loss can be reduced, the motor efficiency can be improved, and the safety of motor use can be increased. Description of the Drawings

[0021] Figure 1 It is the star-pentagram winding connection diagram of the present invention. Detailed Description of the Invention

[0022] The technical solution of the present invention will be further described in detail below in conjunction with the drawings:

[0023] The embodiments described in the present invention are only for the five-phase motor with a single-layer winding using the star-pentagram connection, and the present invention can also be applied to the five-phase motor using the star-pentagon winding connection.

[0024] Example 1

[0025] For a polyphase motor with a star - pentagram connection, each phase armature winding is divided into a star - shaped partial winding and a pentagram - shaped partial winding.

[0026] Take the total number of turns of a single - phase armature winding as N S = N star + N pentacle , where N star and N pentacle are the number of turns of the star - shaped partial winding and the pentagram - shaped partial winding respectively.

[0027] To ensure that the magnetomotive forces generated by the star - shaped partial winding and the pentagram - shaped partial winding are of the same magnitude, according to the equal - ampere - turn law, the relationships between the voltages, currents, and number of turns of the two windings are:

[0028]

[0029] In the formula, M is the modulation ratio; w s is the angular velocity; V DC is the line - to - line voltage of each phase.

[0030] Since the current waveform is non - sinusoidal, the Fourier decomposition is performed on the current of each phase winding respectively. The current of each phase of the star - shaped winding is:

[0031]

[0032] Combining the phase and amplitude relationships of the armature winding currents in the star - pentagram connection, the magnetomotive force of the star - shaped partial winding of the five - phase motor is:

[0033]

[0034] The magnetomotive force of the pentagram - shaped partial winding is:

[0035]

[0036] In the formula, ν is the space harmonic order, μ is the time harmonic order, θ α is the mechanical angle difference in the spatial arrangement between the pentagram winding and the star - shaped winding, F μν is the magnetomotive force amplitude, w is the current frequency, and t is the time.

[0037] Step 6. The sum of the magnetomotive forces of the star - shaped partial winding and the pentagram - shaped partial winding is:

[0038]

[0039] Centered around the embodiments of the present invention, the specific calculation process of this method is introduced in detail. The described calculation process or the specific embodiment of certain features should be understood that this specification only describes the present invention for the motors of the given embodiments. In fact, there will be some changes in certain details during the analysis of the armature magnetomotive force of the five-phase motor, and these changes should fall within the scope of the present invention.

Claims

1. A calculation method for the armature magnetomotive force of a five-phase motor using a star-pentagram connection, characterized in that: Including the following steps: Step 1: For a five-phase motor with a star-pentagram connection, each phase winding is divided into a star part winding and a pentagram part winding; Step 2: Take the total number of turns of the single-phase armature winding as N S = N star + N pentacle , where N star and N pentacle are the number of turns of the star-shaped part winding and the pentagram-shaped part winding respectively; Step 3: To ensure that the magnetomotive forces generated by the star part winding and the pentagram part winding are of the same magnitude, according to the equal ampere-turn law, the relationships between the voltages, currents, and turns of the two windings are as follows: where M is the modulation ratio; w s is the angular velocity; V DC is the line voltage per phase; Step 4: Since the current waveform is non-sinusoidal, the Fourier decomposition is performed on the current of each phase winding respectively. The current of each phase of the star winding is: Step 5: Combining the phase and amplitude relationships of the armature winding currents in the star-pentagram connection, the magnetomotive force of the star part winding of the five-phase motor is obtained as: The magnetomotive force of the pentagram part winding is: where ν is the space harmonic order, μ is the time harmonic order, and θ α is the mechanical angle difference in the spatial arrangement between the pentagram winding and the star winding, F μν is the magnetomotive force amplitude, w is the current frequency, and t is the time; Step 6: The sum of the magnetomotive forces of the star part winding and the pentagram part winding is:

2. The method for calculating the armature magnetomotive force of a five-phase motor using a star-pentagram connection according to claim 1, wherein: The star-pentagram winding connection method eliminates the 9th and 11th harmonics compared with the single star winding and pentagram winding.

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