阅读说明：本技术 一种交流电机低纹波驱动方法 (Low-ripple driving method for alternating current motor ) 是由 郭慧 王晓琳 顾聪 刘雨婷 于 2019-11-08 设计创作，主要内容包括：本发明公开了一种交流电机低纹波驱动方法,采用的功率拓扑结构包含高频功率开关、高频二级管、高频直流滤波电感、六个低频功率开关串联六个低频二极管以及三个交流滤波电容组成,并对交流电机转子位置、速度、定子电流以及前级电感电流进行检测。控制时,通过高频功率开关高频斩波控制电流幅值,通过低频功率开关调节电流相位。本发明中,高频功率开关高频斩波,有助于降低电流纹波,减小电感体积；直流滤波电感使得无需通过大电容实现稳压；低频功率开关的采用有利于系统成本与开关损耗的降低；交流滤波电容提高了电流谐波性能,且减小了高dv/dt带来的不良影响；恒定调制比的后级控制方案便于各种调制策略的应用。(The invention discloses a low-ripple driving method of an alternating current motor, which adopts a power topological structure comprising a high-frequency power switch, a high-frequency diode, a high-frequency direct current filter inductor, six low-frequency power switches, six low-frequency diodes and three alternating current filter capacitors, and detects the position, the speed, the stator current and the preceding stage inductance current of a rotor of the alternating current motor. During control, the current amplitude is controlled through high-frequency chopping of the high-frequency power switch, and the current phase is adjusted through the low-frequency power switch. In the invention, the high-frequency power switch performs high-frequency chopping, which is beneficial to reducing current ripples and reducing the volume of an inductor; the direct current filter inductor ensures that voltage stabilization is realized without a large capacitor; the adoption of the low-frequency power switch is beneficial to reducing the system cost and the switching loss; the alternating current filter capacitor improves the current harmonic performance and reduces the adverse effect caused by high dv/dt; the latter control scheme of constant modulation ratio facilitates the application of various modulation strategies.)

1. A low ripple driving method of an alternating current motor is characterized in that a driving module is arranged to drive the alternating current motor, and the driving module comprises a high-frequency power switch, a high-frequency direct current filter inductor, a high-frequency diode, an inverter and first to third alternating current filter capacitors; the inverter comprises first to sixth low-frequency power switches and first to sixth low-frequency diodes;

one end of the high-frequency power switch is connected with the anode of an external direct-current voltage source, and the other end of the high-frequency power switch is respectively connected with the cathode of the high-frequency diode and one end of the high-frequency direct-current filter inductor; the other end of the high-frequency direct-current filter inductor is connected with one end of the first low-frequency power switch, one end of the third low-frequency power switch and one end of the fifth low-frequency power switch respectively; the other end of the first low-frequency power switch, the other end of the third low-frequency power switch and the other end of the fifth low-frequency power switch are respectively connected with the anode of the first low-frequency diode, the anode of the third low-frequency diode and the anode of the fifth low-frequency diode in a one-to-one correspondence manner;

the anode of the high-frequency diode is respectively connected with the cathode of an external direct-current voltage source, the cathode of the second low-frequency diode, the cathode of the fourth low-frequency diode and the cathode of the sixth low-frequency diode; the anode of the second low-frequency diode, the anode of the fourth low-frequency diode and the anode of the sixth low-frequency diode are respectively connected with one end of the second low-frequency power switch, one end of the fourth low-frequency power switch and one end of the sixth low-frequency power switch in a one-to-one correspondence manner;

the other end of the second low-frequency power switch is respectively connected with the cathode of the first low-frequency diode, one end of the first alternating-current filter capacitor and the A-phase input end of the alternating-current motor;

the other end of the fourth low-frequency power switch is respectively connected with the cathode of the third low-frequency diode, one end of the second alternating-current filter capacitor and the B-phase input end of the alternating-current motor;

the other end of the sixth low-frequency power switch is respectively connected with the cathode of the fifth low-frequency diode, one end of the third alternating-current filter capacitor and the C-phase input end of the alternating-current motor;

the other end of the second alternating current filter capacitor is respectively connected with the other end of the first alternating current filter capacitor and the other end of the third alternating current filter capacitor;

the driving method of the driving module comprises the following steps:

step 1), obtaining a position signal of an alternating current motor, carrying out differential processing on the position signal to obtain the real-time rotating speed of the motor, then carrying out difference between the real-time rotating speed of the motor and a preset rotating speed reference value, and then regulating an output torque current set value by a rotating speed regulatori _q ^* ；

Step 2), obtaining three-phase stator current of the alternating current motor, and resolving to obtain torque component of the currenti _q And field componenti _d ；

Step 3), mixingi _q And a predetermined torque current reference valuei _q ^* After difference making, the output of the inverter is obtained by the regulation of a current regulatorqShaft reference currenti _wq ^* ；

Step (ii) of4) Will bei _d And a predetermined excitation current reference valuei _d ^* After difference making, the output of the inverter is obtained by the regulation of a current regulatordShaft reference currenti _wd ^* ；

Step 5) according to the formulai _dc ^* =sqrt(i ^* _wq ² +i ^* _wd ² ) /mCalculating a DC reference valuei _dc ^* In the formula (I), wherein,mis a preset modulation ratio;

step 6), according to the formulaα=atan(i ^* _wq /i ^* _wd ) Calculating the phase of the output current of the inverterα；

Step 7) obtaining the current of the high-frequency direct current filter inductori _dc Will bei _dc ^* Andi _dc obtaining the duty ratio of the high-frequency power switch through the current regulator after the difference is made, comparing the duty ratio with a carrier wave with a preset frequency threshold value to obtain a high-frequency switching signal, and controlling the high-frequency power switch to work according to the high-frequency switching signal;

step 8), according to the preset modulation ratio,αAnd the alternating current motor position signal is combined with a constant modulation ratio modulation strategy to obtain switching signals of the first to sixth low-frequency power switches, and the first to sixth low-frequency power switches are controlled to work according to the switching signals of the first to sixth low-frequency power switches.

2. The ac motor low-ripple driving method according to claim 1, wherein the first to third ac filter capacitors are each replaced with a capacitive filter network.

3. The ac motor low-ripple driving method according to claim 1, wherein the step 1) is implemented by providing a position sensor in the ac motor to obtain the ac motor position signal.

4. The high-efficiency low-ripple motor driving method according to claim 1, wherein the ac motor position signal is calculated in step 1) by using a position-free algorithm according to an input current and an input voltage of the ac motor.

Technical Field

The invention relates to a low-ripple driving method for an alternating current motor, and belongs to the technical field of electric transmission.

Background

The conventional ac power transmission system generally directly drives the ac motor by a general or special inverter, but the conventional inverter has limited performance and is difficult to satisfy the motor drive of higher performance occasions, and the following problems mainly exist: on one hand, the traditional frequency converter has large output current harmonic wave, further causes the loss increase of a stator and a rotor, forms serious heating, and can cause the aggravation of torque pulsation and increase the control difficulty of a motor; on the other hand, the output end dv/dt of the traditional frequency converter is very high, serious electromagnetic interference exists, the motor insulation and the bearing are further damaged, and the system reliability is reduced.

Existing solutions all have certain drawbacks or limitations, and are briefly set forth as follows:

(1) the modulation strategy is optimized, and the defects that the optimal switching angle is difficult to solve or the algorithm is complex exist generally;

(2) the RLC filter is adopted to avoid the influence of low electromagnetic constant, and besides resistance loss, high inductance high-frequency alternating current iron loss exists;

(3) high cost and electromagnetic interference problems cannot be ignored by adopting a high-frequency switch device;

(4) the improved topological structure comprises multi-level inversion, two-stage voltage type inversion topology and current type inversion topology, and the improved topological structure has the problem of limited application occasions.

Disclosure of Invention

The technical problem to be solved by the present invention is to provide a low ripple driving method for an ac motor, aiming at the defects explained in the background art.

The invention adopts the following technical scheme for solving the technical problems:

a low ripple driving method of an alternating current motor is characterized in that a driving module is arranged to drive the alternating current motor, and the driving module comprises a high-frequency power switch, a high-frequency direct current filter inductor, a high-frequency diode, an inverter and first to third alternating current filter capacitors; the inverter comprises first to sixth low-frequency power switches and first to sixth low-frequency diodes;

one end of the high-frequency power switch is connected with the anode of an external direct-current voltage source, and the other end of the high-frequency power switch is respectively connected with the cathode of the high-frequency diode and one end of the high-frequency direct-current filter inductor; the other end of the high-frequency direct-current filter inductor is connected with one end of the first low-frequency power switch, one end of the third low-frequency power switch and one end of the fifth low-frequency power switch respectively; the other end of the first low-frequency power switch, the other end of the third low-frequency power switch and the other end of the fifth low-frequency power switch are respectively connected with the anode of the first low-frequency diode, the anode of the third low-frequency diode and the anode of the fifth low-frequency diode in a one-to-one correspondence manner;

the anode of the high-frequency diode is respectively connected with the cathode of an external direct-current voltage source, the cathode of the second low-frequency diode, the cathode of the fourth low-frequency diode and the cathode of the sixth low-frequency diode; the anode of the second low-frequency diode, the anode of the fourth low-frequency diode and the anode of the sixth low-frequency diode are respectively connected with one end of the second low-frequency power switch, one end of the fourth low-frequency power switch and one end of the sixth low-frequency power switch in a one-to-one correspondence manner;

the other end of the second low-frequency power switch is respectively connected with the cathode of the first low-frequency diode, one end of the first alternating-current filter capacitor and the A-phase input end of the alternating-current motor;

the other end of the fourth low-frequency power switch is respectively connected with the cathode of the third low-frequency diode, one end of the second alternating-current filter capacitor and the B-phase input end of the alternating-current motor;

the other end of the sixth low-frequency power switch is respectively connected with the cathode of the fifth low-frequency diode, one end of the third alternating-current filter capacitor and the C-phase input end of the alternating-current motor;

the other end of the second alternating current filter capacitor is respectively connected with the other end of the first alternating current filter capacitor and the other end of the third alternating current filter capacitor;

the driving method of the driving module comprises the following steps:

step 1), obtaining a position signal of an alternating current motor, carrying out differential processing on the position signal to obtain the real-time rotating speed of the motor, and then carrying out real-time processing on the motorThe given value of the output torque current is regulated by a rotating speed regulator after the rotating speed is different from the preset rotating speed reference valuei _q ^* ；

Step 2), obtaining three-phase stator current of the alternating current motor, and resolving to obtain torque component of the currenti _q And field componenti _d ；

Step 3), mixingi _q And a predetermined torque current reference valuei _q ^* After difference making, the output of the inverter is obtained by the regulation of a current regulatorqShaft reference currenti _wq ^* ；

Step 4), mixingi _d And a predetermined excitation current reference valuei _d ^* After difference making, the output of the inverter is obtained by the regulation of a current regulatordShaft reference currenti _wd ^* ；

Step 5) according to the formulai _dc ^* =sqrt(i ^* _wq ² +i ^* _wd ² ) /mCalculating a DC reference valuei _dc ^* In the formula (I), wherein,mis a preset modulation ratio;

step 6), according to the formulaα=atan(i ^* _wq /i ^* _wd ) Calculating the phase of the output current of the inverterα；

Step 7) obtaining the current of the high-frequency direct current filter inductori _dc Will bei _dc ^* Andi _dc obtaining the duty ratio of the high-frequency power switch through the current regulator after the difference is made, comparing the duty ratio with a carrier wave with a preset frequency threshold value to obtain a high-frequency switching signal, and controlling the high-frequency power switch to work according to the high-frequency switching signal;

step 8), according to the preset modulation ratio,αAnd the alternating current motor position signal is combined with a constant modulation ratio modulation strategy to obtain switching signals of the first to sixth low-frequency power switches, and the first to sixth low-frequency power switches are controlled to work according to the switching signals of the first to sixth low-frequency power switches.

As a further optimization scheme of the low-ripple driving method of the alternating current motor, the first to third alternating current filter capacitors are replaced by capacitive filter networks.

As a further optimized solution of the ac motor low-ripple driving method according to the present invention, in step 1), a position sensor is disposed in the ac motor to obtain a position signal of the ac motor.

As a further optimization scheme of the low-ripple driving method for the alternating current motor, in step 1), a position-free algorithm is used to calculate a position signal of the alternating current motor according to the input current and the input voltage of the alternating current motor.

Compared with the prior art, the invention adopting the technical scheme has the following beneficial effects:

1. the adoption of the high-frequency switching device can reduce current ripples through high-frequency chopping, thereby reducing the volume of the inductor and improving the dynamic performance of the system; only a single high-frequency power switch is adopted, and the increase of the cost is negligible;

2. the front stage adopts a direct current filter inductor, so that voltage stabilization is realized without a large capacitor;

3. the adoption of the low-frequency power switch is beneficial to reducing the system cost and the switching loss;

4. the alternating current filter capacitor improves the current harmonic performance and reduces the adverse effect caused by high dv/dt; the problem of high-frequency iron loss caused by alternating current filter inductance does not exist;

5. the control strategy of the front-stage speed regulation and the rear-stage commutation can regulate and control the direct-current side current along with the load, reduce the loss and simultaneously facilitate the starting of the motor; on the other hand, the post-stage modulation ratio control facilitates the application of various modulation strategies.

Drawings

FIG. 1 is a block diagram of a control system implementation of the present invention.

Detailed Description

The technical scheme of the invention is further explained in detail by combining the attached drawings:

the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, components are exaggerated for clarity.

As shown in fig. 1, the present invention discloses a low ripple driving method for an ac motor, wherein a driving module is provided to drive the ac motor, and the driving module includes a high frequency power switch, a high frequency dc filter inductor, a high frequency diode, an inverter, and first to third ac filter capacitors; the inverter comprises first to sixth low-frequency power switches and first to sixth low-frequency diodes;

one end of the high-frequency power switch is connected with the anode of an external direct-current voltage source, and the other end of the high-frequency power switch is respectively connected with the cathode of the high-frequency diode and one end of the high-frequency direct-current filter inductor; the other end of the high-frequency direct-current filter inductor is connected with one end of the first low-frequency power switch, one end of the third low-frequency power switch and one end of the fifth low-frequency power switch respectively; the other end of the first low-frequency power switch, the other end of the third low-frequency power switch and the other end of the fifth low-frequency power switch are respectively connected with the anode of the first low-frequency diode, the anode of the third low-frequency diode and the anode of the fifth low-frequency diode in a one-to-one correspondence manner;

the anode of the high-frequency diode is respectively connected with the cathode of an external direct-current voltage source, the cathode of the second low-frequency diode, the cathode of the fourth low-frequency diode and the cathode of the sixth low-frequency diode; the anode of the second low-frequency diode, the anode of the fourth low-frequency diode and the anode of the sixth low-frequency diode are respectively connected with one end of the second low-frequency power switch, one end of the fourth low-frequency power switch and one end of the sixth low-frequency power switch in a one-to-one correspondence manner;

the other end of the second low-frequency power switch is respectively connected with the cathode of the first low-frequency diode, one end of the first alternating-current filter capacitor and the A-phase input end of the alternating-current motor;

the other end of the fourth low-frequency power switch is respectively connected with the cathode of the third low-frequency diode, one end of the second alternating-current filter capacitor and the B-phase input end of the alternating-current motor;

the other end of the sixth low-frequency power switch is respectively connected with the cathode of the fifth low-frequency diode, one end of the third alternating-current filter capacitor and the C-phase input end of the alternating-current motor;

the other end of the second alternating current filter capacitor is respectively connected with the other end of the first alternating current filter capacitor and the other end of the third alternating current filter capacitor;

the driving method of the driving module comprises the following steps:

step 1), obtaining a position signal of an alternating current motor, carrying out differential processing on the position signal to obtain the real-time rotating speed of the motor, then carrying out difference between the real-time rotating speed of the motor and a preset rotating speed reference value, and then regulating an output torque current set value by a rotating speed regulatori _q ^* ；

Step 2), obtaining three-phase stator current of the alternating current motor, and resolving to obtain torque component of the currenti _q And field componenti _d ；

Step 3), mixingi _q And a predetermined torque current reference valuei _q ^* After difference making, the output of the inverter is obtained by the regulation of a current regulatorqShaft reference currenti _wq ^* ；

Step 4), mixingi _d And a predetermined excitation current reference valuei _d ^* After difference making, the output of the inverter is obtained by the regulation of a current regulatordShaft reference currenti _wd ^* ；

Step 5) according to the formulai _dc ^* =sqrt(i ^* _wq ² +i ^* _wd ² ) /mCalculating a DC reference valuei _dc ^* In the formula (I), wherein,mis a preset modulation ratio;

step 6), according to the formulaα=atan(i ^* _wq /i ^* _wd ) Calculating the phase of the output current of the inverterα；

Step 7) obtaining the current of the high-frequency direct current filter inductori _dc Will bei _dc ^* Andi _dc obtaining the duty ratio of the high-frequency power switch through the current regulator after the difference is made, comparing the duty ratio with a carrier wave with a preset frequency threshold value to obtain a high-frequency switching signal, and controlling the high-frequency power switch to work according to the high-frequency switching signal;

step 8), according to the preset modulation ratio,αAnd the alternating current motor position signal is combined with a constant modulation ratio modulation strategy to obtain switching signals of the first to sixth low-frequency power switches, and the first to sixth low-frequency power switches are controlled to work according to the switching signals of the first to sixth low-frequency power switches.

The first to third alternating current filter capacitors can be replaced by capacitive filter networks.

In the step 1), a position sensor may be disposed in the ac motor to obtain a position signal of the ac motor, or a position-free algorithm may be used to calculate the position signal of the ac motor according to an input current and an input voltage of the ac motor.

The invention controls the current amplitude by high-frequency chopping of the high-frequency power switch, thereby achieving the purpose of reducing current ripple and reducing the volume of an inductor; the low-frequency power switch is used for adjusting the current phase, so that the pursuit of low loss and low cost is realized. In the control process, the tracking reference value with good motor rotating speed, current amplitude and phase can be realized by continuous steps. The power topological structure that whole scheme adopted is comparatively simple, and control technique easily realizes to can effectively reduce the electric current ripple, reduce system's loss, help improving alternating current motor drive system's efficiency and stability.

It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

The above-mentioned embodiments, objects, technical solutions and advantages of the present invention are further described in detail, it should be understood that the above-mentioned embodiments are only illustrative of the present invention and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.