阅读说明：本技术 三相逆变器带异步电机端子无残压的带速重投系统及方法 (Belt speed re-throwing system and method for three-phase inverter with asynchronous motor terminal without residual voltage ) 是由 金浩 潘冬华 李武杰 王自然 姚川 于 2021-04-21 设计创作，主要内容包括：本发明提供了一种三相逆变器带异步电机端子无残压的带速重投系统及方法,三相逆变器在逆变桥输出端增加了LC滤波电路。当三相逆变器故障停机时,为了快速重投,需要估算重投时刻的电机转速,此时通过电流闭环,给电流注入一定频率和幅值的电流,通过检测LC滤波电感L上的电流和电容C上的电压,结合异步电机的数学模型,估算出电机的转子磁链,根据电机转子磁链和定子电流,计算出电机的转差角频率,根据注入的定子频率和计算的转差角频率作差可以求出电机转子角频率,也即可以得到电机转速。本发明不仅提供了逆变器故障停机电机带速且端电压为零时的逆变器重投,也适用于逆变器启动时电机带速且无端电压等状态下的快速投入。(The invention provides a system and a method for a three-phase inverter with asynchronous motor terminals and without residual voltage for tape speed re-switching. When the three-phase inverter is in fault shutdown, in order to realize rapid reclosing, the motor rotating speed at the reclosing moment needs to be estimated, current with certain frequency and amplitude is injected into the current through a current closed loop at the moment, the rotor flux linkage of the motor is estimated by detecting the current on an LC filter inductor L and the voltage on a capacitor C and combining a mathematical model of the asynchronous motor, the rotor angular frequency of the motor is calculated according to the rotor flux linkage and the stator current of the motor, and the rotor angular frequency of the motor can be calculated according to the difference between the injected stator frequency and the calculated rotor angular frequency, namely the motor rotating speed can be obtained. The invention not only provides the inverter re-input when the inverter fault stops the motor and the terminal voltage is zero, but also is suitable for the rapid input of the motor in the states of motor speed, no terminal voltage and the like when the inverter starts.)

1. The utility model provides a three-phase inverter takes quick heavy-duty system of taking of asynchronous machine terminal no residual voltage, includes DC power supply, three-phase IGBT invertion bridge, three-phase asynchronous machine and motor load, its characterized in that: further comprising:

an LC filter circuit; the LC filter circuit comprises a filter inductor L and a filter capacitor C;

the direct-current power supply is electrically connected with the input end of the three-phase IGBT inverter bridge; the output end of the three-phase IGBT inverter bridge is electrically connected with the input end of the LC filter circuit; the output end of the LC filter circuit is electrically connected with the three-phase asynchronous motor; the three-phase asynchronous motor is connected with a load through a coupler;

and the three-phase IGBT inverter bridge is controlled by a chip DSP.

2. The belt speed re-throwing method of the three-phase inverter with the asynchronous motor terminal without residual voltage is applied to the belt speed re-throwing system of the three-phase inverter with the asynchronous motor terminal without residual voltage, which is characterized in that: the method specifically comprises the following steps:

s101: injecting current with preset frequency into the three-phase asynchronous motor, controlling the current to be output according to a set amplitude value through a current closed loop, and generating induced voltage at a motor terminal under the action of the current;

s102: taking the induction voltage as the input voltage of the end of the three-phase asynchronous motor, taking the current with preset frequency as the input current of the three-phase asynchronous motor, and inputting the input voltage and the input current to the chip DSP;

s103: the chip DSP calculates to obtain a rotor flux linkage of the three-phase asynchronous motor according to the input voltage, the input current and a mathematical model of the three-phase asynchronous motor;

s104: calculating the slip angular frequency of the three-phase asynchronous motor according to the rotor flux linkage and the input current;

s105: calculating to obtain the rotor angular frequency of the three-phase asynchronous motor according to the given stator frequency of the three-phase asynchronous motor and the rotation difference angular frequency;

s106: and calculating the motor rotating speed under the condition that the asynchronous motor terminal has no residual voltage according to the rotor angular frequency of the three-phase asynchronous motor.

3. The belt speed re-throwing method of the three-phase inverter with the asynchronous motor terminal without residual voltage as claimed in claim 2, characterized in that: in step S101, the current amplitude of the current with the preset frequency is the no-load current of the motor.

4. The belt speed re-throwing method of the three-phase inverter with the asynchronous motor terminal without residual voltage as claimed in claim 2, characterized in that: in step S103, the formula of the calculated rotor flux linkage of the three-phase asynchronous motor is shown as formula (1):

in the formula (1), phi_rα、ψ_rβIs a rotor flux linkage under an alpha beta system of a two-phase static coordinate system; psi_sα、ψ_sβIs a stator flux linkage under a two-phase stationary coordinate system; i.e. i_sα、i_sβIs the stator current in the two-phase stationary coordinate system, i.e. the input current; l is_mIs equivalent mutual inductance of coaxial windings of stator and rotor, L_sFor equivalent self-inductance of the stator winding, L_rIs the equivalent self-inductance of the rotor winding.

5. The belt speed re-throwing method of the three-phase inverter with the asynchronous motor terminal without residual voltage as claimed in claim 4, characterized in that: the calculation formula of the stator flux linkage in the two-phase stationary coordinate system is shown as formula (2):

in the formula (2), R_sIs stator resistance, u_sα、u_sβIs the stator voltage in a two-phase stationary frame, i.e. the input voltage.

6. The belt speed re-throwing method of the three-phase inverter with the asynchronous motor terminal without residual voltage as claimed in claim 4, characterized in that: in step S104, the calculated slip angular frequency is specifically as shown in formula (3):

in formula (3), the rotation difference angular frequency of the asynchronous motor is w_sl。

7. The belt speed re-throwing method of the three-phase inverter with the asynchronous motor terminal without residual voltage as claimed in claim 6, characterized in that: in step S105, the rotor angular frequency of the three-phase asynchronous motor is calculated as shown in formula (4):

in the formula (4), the angular frequency of the asynchronous motor rotor is w_r；For a given stator frequency of the asynchronous machine.

8. The belt speed re-throwing method of the three-phase inverter with the asynchronous motor terminal without residual voltage as claimed in claim 7, characterized in that: in step S106, the calculation formula of the motor rotation speed is as follows:

in the formula (5), n_pThe number of pole pairs of the three-phase asynchronous motor is shown.

9. The belt speed re-throwing method of the three-phase inverter with the asynchronous motor terminal without residual voltage as claimed in claim 4, characterized in that: in step S101, the current closed-loop control current output according to the set amplitude specifically includes: detecting the injected current through an LC filter circuit for feedback revision; the calculation formula for detecting the injected current is as follows (6):

and (3) obtaining the motor current under the two-phase static coordinate system through CLARK transformation in the formula (6), wherein the formula is (7):

in the formula (6), i_a、i_b、i_cThe three-phase current of the motor; i.e. i_La、i_Lb、i_LcIs the detected current of the filter inductor L; u. of_a、u_b、u_cIs the detected voltage of the filter capacitor C.

Technical Field

The invention relates to the field of motor control, in particular to a belt speed re-throwing system and a belt speed re-throwing method for a three-phase inverter with an asynchronous motor terminal without residual voltage.

Background

The three-phase inverter operates with an asynchronous motor, when the asynchronous motor operates at a certain rotating speed immediately before the inverter is started, or the inverter reports a fault and stops operating during the operation of the asynchronous motor, a three-phase IGBT inverter bridge (inverter) needs to be put into operation again under the motor speed state, if the voltage residual voltage at the end of the motor is not zero, the rotating speed of the motor can be estimated by detecting the voltage, if the voltage residual voltage at the end of the motor is zero, namely no residual voltage exists, and the inverter is reset under the motor speed, a method capable of identifying the rotating speed of the motor needs to be provided, so that the asynchronous motor can carry out quick speed resetting.

Disclosure of Invention

In view of this, the invention provides a belt speed re-switching system and method for a three-phase inverter with an asynchronous motor terminal without residual voltage, aiming at the situation that the inverter stops due to faults and the motor terminal does not have residual voltage during the operation of the asynchronous motor. The invention injects current with certain frequency and constant amplitude, detects the response voltage under the current excitation, can estimate the rotor flux linkage of the motor by knowing the voltage and the current of the motor, can calculate the angular frequency of the rotation difference of the asynchronous motor by the rotor flux linkage and the current, the angular frequency of the stator is known, and the angular frequency of the rotor of the motor can be obtained by subtracting the angular frequency of the rotation difference obtained by calculation from the angular frequency of the stator, namely the rotating speed of the motor is obtained.

The invention provides a belt speed re-throwing system and a method of a three-phase inverter with asynchronous motor terminals without residual voltage, wherein the system comprises: the system comprises a direct-current power supply, a three-phase IGBT inverter bridge, a three-phase asynchronous motor, a motor load and an LC filter circuit; an LC filter circuit; the LC filter circuit comprises a filter inductor L and a filter capacitor C;

the direct-current power supply is electrically connected with the input end of the three-phase IGBT inverter bridge; the output end of the three-phase IGBT inverter bridge is electrically connected with the input end of the LC filter circuit; the output end of the LC filter circuit is electrically connected with the three-phase asynchronous motor; the three-phase asynchronous motor is connected with a load through a coupler;

and the three-phase IGBT inverter bridge is controlled by a chip DSP.

A belt speed re-throwing method of a three-phase inverter with an asynchronous motor terminal without residual voltage specifically comprises the following steps:

s101: injecting current with preset frequency into the three-phase asynchronous motor, controlling the current to be output according to a set amplitude value through a current closed loop, and generating induced voltage at a motor terminal under the action of the current;

s102: taking the induction voltage as the input voltage of the end of the three-phase asynchronous motor, taking the current with preset frequency as the input current of the three-phase asynchronous motor, and inputting the input voltage and the input current to the chip DSP;

s103: the chip DSP calculates to obtain a rotor flux linkage of the three-phase asynchronous motor according to the input voltage, the input current and a mathematical model of the three-phase asynchronous motor;

s104: calculating the slip angular frequency of the three-phase asynchronous motor according to the rotor flux linkage and the input current;

s105: calculating to obtain the rotor angular frequency of the three-phase asynchronous motor according to the given stator frequency of the three-phase asynchronous motor and the rotation difference angular frequency;

s106: and calculating the motor rotating speed under the condition that the asynchronous motor terminal has no residual voltage according to the rotor angular frequency of the three-phase asynchronous motor.

Further, in step S101, the current amplitude of the current with the preset frequency is the idle current of the motor.

Further, in step S103, the formula of the calculated rotor flux linkage of the three-phase asynchronous motor is shown in formula (1):

in the formula (1), phi_rα、ψ_rβIs a rotor flux linkage under an alpha beta system of a two-phase static coordinate system; psi_sα、ψ_sβIs a stator flux linkage under a two-phase static coordinate system; i.e. i_sα、i_sβIs the stator current in the two-phase stationary coordinate system, i.e. the input current; l is_mIs equivalent mutual inductance of coaxial windings of stator and rotor, L_sFor equivalent self-inductance of the stator winding, L_rIs the equivalent self-inductance of the rotor winding.

Further, the calculation formula of the stator flux linkage in the two-phase stationary coordinate system is shown in formula (2):

in the formula (2), R_sIs stator resistance, u_sα、u_sβIs the stator voltage in a two-phase stationary frame, i.e. the input voltage.

Further, in step S104, the calculated slip angular frequency is specifically represented by formula (3):

in formula (3), the rotation difference angular frequency of the asynchronous motor is w_sl。

Further, in step S105, the rotor angular frequency of the three-phase asynchronous motor is calculated and obtained as specifically shown in formula (4):

in the formula (4), the angular frequency of the asynchronous motor rotor is w_r；For a given stator frequency of the asynchronous machine.

In step S106, the calculation formula of the motor rotation speed is as follows:

in the formula (5), n_pThe number of pole pairs of the three-phase asynchronous motor is shown.

In step S101, the current closed-loop control current output according to the set amplitude specifically includes: detecting the injected current through an LC filter circuit for feedback revision; the calculation formula for detecting the injected current is as follows (6):

and (3) obtaining the motor current under the two-phase static coordinate system through CLARK transformation in the formula (6), wherein the formula is (7):

in the formula (6), i_a、i_b、i_cThe three-phase current of the motor; i.e. i_La、i_Lb、i_LcIs the detected current of the filter inductor L; u. of_a、u_b、u_cIs the detected voltage of the filter capacitor C.

The invention has the beneficial effects that: the method not only provides the inverter restarting when the inverter is in fault shutdown and the voltage at the motor end is zero, but also is suitable for the condition that when the inverter is started, the motor is in the speed, for example, the motor is always rotating due to external factors, or when the inverter is stopped, the motor needs time for stopping rotation, if the inverter is restarted in a short time after being stopped, the motor is in the speed, and the motor in the states has the speed but no voltage on the terminal. The method ensures that the motor is stably and quickly restarted, and well improves the fault-tolerant rate of the driving system.

Drawings

FIG. 1 is a block diagram of the tape casting system of the present invention;

FIG. 2 is a flow chart of the tape speed re-launch method of the present invention;

FIG. 3 is a block diagram of the control scheme of the tape speed re-launch method of the present invention;

FIG. 4 is a graph of a motor current waveform in response after current injection;

FIG. 5 is a graph of three phase voltage output by the inverter after motor injection;

FIG. 6 shows the motor speed identified by the open-loop vector slip estimation method of the present invention and the actual motor speed.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be further described with reference to the accompanying drawings.

Referring to fig. 1, a belt speed re-throwing system for a three-phase inverter with an asynchronous motor terminal without residual voltage includes the following:

the system comprises a direct-current power supply, a three-phase IGBT inverter bridge, a three-phase asynchronous motor, a motor load and an LC filter circuit; the LC filter circuit comprises a filter inductor and a filter capacitor C;

in fig. 1, a direct-current power supply, a three-phase IGBT inverter bridge, an LC filter circuit, a three-phase asynchronous motor, and a motor load are sequentially arranged from left to right; wherein the chip DSP is not seen;

an LC filter circuit; the LC filter circuit comprises a filter inductor L and a filter capacitor C;

the direct-current power supply is electrically connected with the input end of the three-phase IGBT inverter bridge; the output end of the three-phase IGBT inverter bridge is electrically connected with the input end of the LC filter circuit; the output end of the LC filter circuit is electrically connected with the three-phase asynchronous motor; the three-phase asynchronous motor is connected with a load through a coupler;

and the three-phase IGBT inverter bridge is controlled by a chip DSP.

Referring to fig. 2, fig. 2 is a flow chart of the tape speed re-casting method according to the present invention; a belt speed re-throwing method of a three-phase inverter with an asynchronous motor terminal without residual voltage specifically comprises the following steps:

s101: injecting current with preset frequency into the three-phase asynchronous motor, controlling the current to be output according to a set amplitude value through a current closed loop, and generating induced voltage at a motor terminal under the action of the current;

in step S101, the current closed-loop control current output according to the set amplitude specifically includes: detecting the injected current through an LC filter circuit for feedback revision; the calculation formula for detecting the injected current is as follows:

the motor current under the two-phase static coordinate system is obtained by CLARK transformation of the above formula, which is as follows:

i_a、i_b、i_cthe three-phase current of the motor; i.e. i_La、i_Lb、i_LcIs the detected current of the filter inductor L; u. of_a、 u_b、u_cIs the detected voltage of the filter capacitor C.

S102: taking the induction voltage as the input voltage of the end of the three-phase asynchronous motor, taking the current with preset frequency as the input current of the three-phase asynchronous motor, and inputting the input voltage and the input current to the chip DSP;

s103: the chip DSP calculates to obtain a rotor flux linkage of the three-phase asynchronous motor according to the input voltage, the input current and a mathematical model of the three-phase asynchronous motor;

s104: calculating the slip angular frequency of the three-phase asynchronous motor according to the rotor flux linkage and the input current;

s105: calculating to obtain the rotor angular frequency of the three-phase asynchronous motor according to the given stator frequency of the three-phase asynchronous motor and the rotation difference angular frequency;

s106: and calculating the motor rotating speed under the condition that the asynchronous motor terminal has no residual voltage according to the rotor angular frequency of the three-phase asynchronous motor.

In step S101, the current amplitude of the current with the preset frequency is the no-load current of the motor.

Referring to fig. 3, fig. 3 is a control schematic block diagram of the motor speed identification method of the present invention;

in the context of figure 3, it is shown,the three-phase asynchronous motor has rotating speed and no residual voltage on a terminal, current with a certain amplitude is injected into the motor, voltage can be responded to the motor terminal through the control of a current closed-loop PI regulator, a motor rotor flux linkage can be estimated according to a motor model according to a current signal fed back by detection and a voltage signal responded, the motor slip frequency can be calculated according to the rotor flux linkage and the motor current, the current stator frequency (current value of injection frequency) is known, the slip frequency can be estimated according to an open-loop vector, the motor rotor frequency can be obtained by subtracting the slip frequency from the stator frequency, and the rotating speed of the motor can be estimated. In the formula (I), the compound is shown in the specification,a given value for the d-axis of current injection in the dq coordinate system, typically set to 30% of the rated current,a given value, generally zero, i, for the q-axis of the current injection in the dq coordinate system_d，i_qIs a feedback current in dq coordinate system, u_d，u_qIs the output voltage dq axis component of the current loop PI regulator;for angular frequency of current injection, theta_rStator voltage phase, i, integrated for injected angular frequency_a，b，cFor detected three-phase currents of the motor u_a，b，cFor detecting three-phase voltage of motor i_alfa，betaIs the stator current u under an alpha beta coordinate system obtained by CLARK transformation_alfa，betaIs the stator voltage w in an alpha-beta coordinate system obtained by CLARK transformation_slThe angular frequency of the motor slip is obtained by open-loop vector estimation according to a motor model.

In step S103, the formula of the calculated rotor flux linkage of the three-phase asynchronous motor is shown as formula (1):

in the formula (1), phi_rα、ψ_rβIs a rotor flux linkage under an alpha beta system of a two-phase static coordinate system; psi_sα、ψ_sβIs a stator flux linkage under a two-phase static coordinate system; i.e. i_sα、i_sβIs the stator current in the two-phase stationary coordinate system, i.e. the input current; l is_mIs equivalent mutual inductance of coaxial windings of stator and rotor, L_sFor equivalent self-inductance of the stator winding, L_rIs the equivalent self-inductance of the rotor winding.

The calculation formula of the stator flux linkage in the two-phase stationary coordinate system is shown as formula (2):

in the formula (2), R_sIs stator resistance, u_sα、u_sβIs the stator voltage in a two-phase stationary frame, i.e. the input voltage.

In step S104, the calculated slip angular frequency is specifically as shown in formula (3):

in formula (3), the rotation difference angular frequency of the asynchronous motor is w_sl。

In step S105, the rotor angular frequency of the three-phase asynchronous motor is calculated as shown in formula (4):

in the formula (4), the angular frequency of the asynchronous motor rotor is w_r；For a given stator frequency of the asynchronous machine.

In step S106, the calculation formula of the motor rotation speed is as follows:

in the formula (5), n_pThe number of pole pairs of the three-phase asynchronous motor is shown.

After the rotating speed of the motor is identified, a pre-designed VF curve is controlled according to the asynchronous motor, the given frequency is the frequency corresponding to the current rotating speed of the motor, the voltage is the voltage inquired by the current frequency according to the VF curve, the voltage is increased to a set value, and then the frequency and voltage increasing control is carried out according to the VF control curve until the motor reaches a set target rotating speed value.

An example is provided below.

MATLAB simulation analysis shows that the method has high identification precision, good rapidity, high feasibility and strong engineering implementation. The motor parameters of the three-phase asynchronous motor in simulation are as follows: rated power of 15kW, rated voltage of 380V, rated current of 22.7A, pole pair number of 2, rated frequency of 50Hz, rated rotation speed of 1500rpm, and stator resistance of R_s2.261 Ω, rotor resistance R_r1.157 Ω, stator inductance L_s0.0787H, and the rotor inductance L_r0.0779H, equivalent mutual inductance L_s0.0765H. In simulation, the initial rotation speed of the three-phase asynchronous motor is 1200rpm to simulate the working condition of the motor terminal without residual voltage, at the moment, the rotation speed of the motor needs to be identified, the frequency corresponding to 90% of the rated rotation speed (or the rotation speed before shutdown) and the current with a certain amplitude are injected, the output voltage is adjusted through a current loop PI, and the amplitude of the injected current is generally 30% -50% of the rated current. In the simulation, 95% of rated frequency and 45% of rated current are injected, and the frequency of the motor stator is decreased from 95% according to a certain slope. FIG. 4 is a waveform diagram of motor current in response to current injection, FIG. 5 is three-phase voltage output by an inverter after motor injection, FIG. 6 is motor speed and actual motor speed identified by the open-loop vector slip estimation method of the present invention, and FIG. 4 is a waveform diagram of the first quarter of a cycle after time axisDuring the period, the curves from top to bottom show in sequence: A. b, C three-phase current; in fig. 5, the curves from top to bottom in the first quarter cycle after the time axis show: phase line voltages of an AB phase, a BC phase and a CA phase of the motor; in fig. 6, from 0s to 0.02s after the time axis, the upper curve is the identified motor speed, and the lower curve is the real motor speed; as can be seen from the graphs of FIGS. 4, 5 and 6, the method of the present invention has the advantages of stable motor current and voltage, high identification speed and high identification precision, and the difference between the real rotation speed and the identification rotation speed is 50rpm at time 0.1s, the difference between the real rotation speed and the identification rotation speed is 4rpm at time 0.2s, the estimation error is less than 0.36%, the time is less than 0.2s, and the identification error of the rotation speed is about 1rpm at time 0.5s, so that the accuracy and the practicability of the method can be seen. In addition, the method for identifying the rotating speed is also verified in a laboratory.

The invention has the beneficial effects that: the method not only provides the inverter restarting when the inverter is in fault shutdown and the voltage at the motor end is zero, but also is suitable for the condition that when the inverter is started, the motor is in the speed, for example, the motor is always rotating due to external factors, or when the inverter is stopped, the motor needs time for stopping rotation, if the inverter is restarted in a short time after being stopped, the motor is in the speed, and the motor in the states has the speed but no voltage on the terminal. The method ensures that the motor is stably and quickly restarted, and well improves the fault-tolerant rate of the driving system.

The above description is only exemplary of the present invention and should not be taken as limiting, since any modifications, equivalents, improvements and the like which are within the spirit and principle of the present invention are intended to be included within the scope of the present invention.