阅读说明：本技术 一种开绕组永磁发电机匝间短路电流间接测量方法 (Indirect measurement method for turn-to-turn short circuit current of open winding permanent magnet generator ) 是由 王伟 陆超 曾昕卢 程明 于 2020-04-14 设计创作，主要内容包括：本发明公开了一种开绕组永磁发电机匝间短路电流间接测量方法,该方法首先通过主动控制故障绕组两端的变换器桥臂,将故障绕组的短路比主动扩展至100％；其次,通过故障绕组原有的电流传感器实现对匝间短路电流的高精度瞬时间接测量；第三,根据所测量的瞬时匝间短路电流,构造匝间短路电流的数学模型；最后,封锁故障绕组两端的变换器桥臂,将匝间短路比恢复至原有状态。本发明无需新增传感器,通过将电机故障绕组主动短路的方法,规避了匝间短路电流不可直接测量的问题,提升了电机驱动系统的可靠性与安全性。(The invention discloses an indirect measuring method for turn-to-turn short circuit current of an open winding permanent magnet generator, which comprises the steps of firstly actively controlling converter bridge arms at two ends of a fault winding to actively expand the short circuit ratio of the fault winding to 100%; secondly, high-precision instantaneous indirect measurement of turn-to-turn short circuit current is realized through an original current sensor of a fault winding; thirdly, constructing a mathematical model of the turn-to-turn short circuit current according to the measured instantaneous turn-to-turn short circuit current; and finally, blocking converter bridge arms at two ends of the fault winding, and restoring the turn-to-turn short circuit ratio to the original state. According to the invention, a sensor is not required to be additionally arranged, the problem that the turn-to-turn short circuit current cannot be directly measured is avoided by a method of actively short-circuiting a fault winding of the motor, and the reliability and the safety of a motor driving system are improved.)

1. An indirect measurement method for turn-to-turn short circuit current of an open winding permanent magnet generator is characterized by comprising the following steps:

(1) when the turn-to-turn short circuit fault occurs in the open winding permanent magnet generator, the following variables are set: indirect measurement mark F, turn-to-turn short circuit current amplitude I_mThe measured value I of the turn-to-turn short circuit current in the current sampling period_kAnd the previous two sampling periods are turn-to-turn short circuit current measurement values I_k-2And I_k-1Rotor position angle of theta_kThe maximum value of the turn-to-turn short circuit current is obtained and the measured value theta of the rotor position angle is corresponding to the maximum value_mSetting the initial values of the variables to be 0;

(2) the rotor position angle of the current sampling period is measured by a position sensor and is assigned to theta_k；

(3) If F is 1, jumping to step (9);

(4) converter bridge arms at two ends of the fault winding are actively controlled to enable the fault winding to be actively short-circuited, so that the short-circuit ratio mu of the fault winding is actively expanded to 100%;

(5) measuring turn-to-turn short circuit current of the current sampling period through the original current sensor of the fault phase winding and assigning the current to I_k；

(6) If I_k-1>I_kAnd I_k-1>I_k-2Then I_m＝I_k-1，F＝1；

(7)I_k-2＝I_k-1，I_k-1＝I_k，θ_m＝θ_k；

(8) Jumping to the step (2) when the next sampling period comes;

(9) the turn-to-turn short circuit current amplitude I is obtained according to indirect measurement_mAnd its corresponding rotor position angle theta_mEstablishing a mathematical equation i of the turn-to-turn short circuit current_f(θ_e)；

(10) And (4) blocking converter bridge arms at two ends of the fault winding, and restoring the turn-to-turn short circuit ratio mu to the original state.

2. The indirect measurement method for the turn-to-turn short circuit current of the open-winding permanent magnet generator according to claim 1, is characterized in that: in the step (4), a high-level signal is applied to the switching tubes of the bridge arms of the power converter at two ends of the fault phase, so that the fault phase winding is actively short-circuited, and the short-circuit ratio mu is expanded to 100%.

3. The open-winding permanent magnet generator turn-to-turn short circuit current indirect measurement method according to claim 2, characterized in that: the turn-to-turn short circuit current mathematical model constructed in the step (9) is as follows:

wherein, theta_eFor the rotor position angle of the machine, I_mAmplitude of the short-circuit current between turns, theta_mAnd obtaining a rotor position angle measured value corresponding to the maximum value of the turn-to-turn short circuit current.

Technical Field

The invention relates to an indirect measurement method for turn-to-turn short circuit current of an open winding permanent magnet generator, and belongs to the technical field of motor control.

Background

At present, fault-tolerant control of the existing multi-phase motor is mostly focused on open-circuit faults, and relatively few researches on fault-tolerant control of turn-to-turn short circuits of windings are carried out. After the turn-to-turn short circuit fault occurs, the rotating permanent magnet flux linkage can continuously induce back electromotive force in the armature winding in the short circuit, and therefore short circuit current is generated. The turn-to-turn short circuit current can damage the original circular rotating magnetic field, obvious torque fluctuation is generated, and the operation reliability of the system is influenced. If fault-tolerant control is carried out on turn-to-turn short circuit faults of the motor, turn-to-turn short circuit current needs to be measured, however, the number of turns of a short circuit winding is difficult to accurately determine, and turn-to-turn short circuit current cannot be measured on line on the premise of not adding an additional sensor, and the report of research results in the aspect is rarely seen at present. The difficulty in measuring the turn-to-turn short circuit current makes fault-tolerant control of the motor system under the turn-to-turn short circuit fault become a technical difficulty.

Disclosure of Invention

The purpose of the invention is as follows: aiming at the problems, the invention provides an indirect measurement method for turn-to-turn short circuit current of an open winding permanent magnet generator. The method is based on the structural characteristics of open windings, and innovatively provides an indirect turn-to-turn short circuit current measuring method based on active short circuit of a phase winding, so that high-precision measurement of the turn-to-turn short circuit current is realized, the problem that the turn-to-turn short circuit current cannot be directly measured is avoided, a technical basis is provided for fault-tolerant control of the turn-to-turn short circuit of the generator winding, and the reliability of the system is improved.

The technical scheme is as follows: in order to achieve the purpose of the invention, the technical scheme adopted by the invention is as follows: an indirect measurement method for turn-to-turn short circuit current of an open winding permanent magnet generator, comprising the following steps:

(1) when the turn-to-turn short circuit fault occurs in the open winding permanent magnet generator, the following variables are set: indirect measurement mark F, turn-to-turn short circuit current amplitude I_mThe measured value I of the turn-to-turn short circuit current in the current sampling period_kAnd the previous two sampling periods are turn-to-turn short circuit current measurement values I_k-2And I_k-1Rotor position angle of theta_kThe maximum value of the turn-to-turn short circuit current is obtained and the measured value theta of the rotor position angle is corresponding to the maximum value_mAnd setting the initial values of the variablesIs 0;

(2) the rotor position angle of the current sampling period is measured by a position sensor and is assigned to theta_k；

(3) If F is 1, jumping to step (9);

(4) converter bridge arms at two ends of the fault winding are actively controlled to enable the fault winding to be actively short-circuited, so that the short-circuit ratio mu of the fault winding is actively expanded to 100%;

(5) measuring turn-to-turn short circuit current of the current sampling period through the original current sensor of the fault phase winding and assigning the current to I_k；

(6) If I_k-1>I_kAnd I_k-1>I_k-2Then I_m＝I_k-1，F＝1；

(7)I_k-2＝I_k-1，I_k-1＝I_k，θ_m＝θ_k；

(8) Jumping to the step (2) when the next sampling period comes;

(9) the turn-to-turn short circuit current amplitude I is obtained according to indirect measurement_mAnd its corresponding rotor position angle theta_mEstablishing a mathematical equation i of the turn-to-turn short circuit current_f(θ_e) The following were used:

wherein, theta_eFor the rotor position angle of the machine, I_mAmplitude of the short-circuit current between turns, theta_mAnd obtaining a rotor position angle measured value corresponding to the maximum value of the turn-to-turn short circuit current.

(10) And (4) blocking converter bridge arms at two ends of the fault winding, and restoring the turn-to-turn short circuit ratio mu to the original state.

Has the advantages that: compared with the prior art, the technical scheme of the invention has the following beneficial technical effects:

(1) the measuring method innovatively provides an indirect turn-to-turn short circuit current measuring method based on the active short circuit of the phase winding, solves the technical problem that the turn-to-turn short circuit current cannot be measured, and completes high-precision instantaneous indirect measurement of the turn-to-turn short circuit current;

(2) the measuring method constructs a mathematical model of the inter-short circuit current according to the measured instantaneous inter-turn short circuit current, and provides a foundation for subsequent motor control.

(3) According to the measuring method, additional sensor equipment is not needed to be installed, only the bridge arms of the power converters at two ends of the fault phase winding are needed to be controlled, and the algorithm is simple and easy to implement.

Drawings

FIG. 1 is a flow chart of a measurement method of the present invention;

FIG. 2 is a schematic diagram of an A-phase winding turn-to-turn short circuit;

FIG. 3 is a topological structure diagram of an H-bridge type power converter of an open-winding permanent magnet motor;

FIG. 4 is an equivalent circuit diagram of the A-phase winding after active short circuit of the fault phase;

FIG. 5 illustrates phase A current during normal operation;

fig. 6 shows the a-phase current after the occurrence of an inter-turn short circuit with a short circuit ratio μ equal to 0.5;

fig. 7 shows the a-phase current after the occurrence of an inter-turn short fault with a short circuit ratio μ equal to 0.5 and active short circuit;

fig. 8 is a comparison of the a-phase turn-to-turn short circuit current and the constructed mathematical equation for the turn-to-turn short circuit current.

Detailed Description

The technical scheme of the invention is explained in detail in the following by combining the drawings and the embodiment:

as shown in fig. 1, the invention provides an indirect measurement method for inter-turn short circuit current of an open-winding permanent magnet generator, taking an example of inter-turn short circuit of a phase a, an equivalent circuit diagram of the inter-turn short circuit is shown in fig. 2, a topological structure of an H-bridge type power converter of the open-winding permanent magnet generator is shown in fig. 3, and the indirect measurement method for the inter-turn short circuit current of the open-winding permanent magnet generator comprises the following steps:

(1) when the turn-to-turn short circuit fault occurs in the open winding permanent magnet generator, the following variables are set: indirect measurement mark F, turn-to-turn short circuit current amplitude I_mThe measured value I of the turn-to-turn short circuit current in the current sampling period_kAnd turn-to-turn short circuit current measurement of the previous two sampling periodsMagnitude I_k-2And I_k-1Rotor position angle of theta_kThe maximum value of the turn-to-turn short circuit current is obtained and the measured value theta of the rotor position angle is corresponding to the maximum value_mSetting the initial values of the variables to be 0;

(2) the rotor position angle of the current sampling period is measured by a position sensor and is assigned to theta_k；

(3) If F is 1, jumping to step (9);

(4) simultaneously sending conducting instructions to the switching tubes A11 and A21 of the bridge arms of the power converter at the two ends of the phase A, namely simultaneously applying high-level signals to actively short-circuit the phase A winding, so that the short-circuit ratio mu is expanded to 100%, and the equivalent circuit diagram of the phase A winding after active short-circuit of a fault phase is shown in figure 4;

(5) measuring turn-to-turn short circuit current of the current sampling period through the original current sensor of the fault phase winding and assigning the current to I_k；

(6) If I_k-1>I_kAnd I_k-1>I_k-2Then I_m＝I_k-1，F＝1；

(7)I_k-2＝I_k-1，I_k-1＝I_k，θ_m＝θ_k；

(8) Jumping to the step (2) when the next sampling period comes;

(9) the turn-to-turn short circuit current amplitude I is obtained according to indirect measurement_mAnd its corresponding rotor position angle theta_mEstablishing a mathematical equation i of the turn-to-turn short circuit current_f(θ_e) The following were used:

wherein, theta_eFor the rotor position angle of the machine, I_mAmplitude of the short-circuit current between turns, theta_mAnd obtaining a rotor position angle measured value corresponding to the maximum value of the turn-to-turn short circuit current.

(10) And (4) blocking converter bridge arms at two ends of the fault winding, and restoring the turn-to-turn short circuit ratio mu to the original state.

Fig. 5 and fig. 6 are current waveforms before and after a winding turn-to-turn short circuit fault occurs in a phase a of the generator, respectively, it can be seen that the turn-to-turn short circuit fault significantly increases phase current, and fig. 8 is a comparison of a turn-to-turn short circuit current waveform indirectly measured after an active short circuit of the phase a winding and a turn-to-turn short circuit current mathematical equation waveform established by the measurement method of the present invention, it can be seen that the method can effectively measure the turn-to-turn short circuit current.

The embodiments of the present invention are merely preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. That is, all equivalent changes and modifications made according to the content of the claims of the present invention should be regarded as the technical scope of the present invention.