阅读说明：本技术 一种基于定子磁链的最小电流谐波脉宽调制系统 (Minimum current harmonic pulse width modulation system based on stator flux linkage ) 是由 康成伟 张硕 丛培成 于 2019-10-29 设计创作，主要内容包括：一种基于定子磁链的最小电流谐波脉宽调制系统,包括逆变模块、控制单元,其中控制单元的处理器模块包括信号滤波模块、调制度计算模块、频率及角度计算模块、模式选择与切换模块、开关角计算模块、选择和更新模块以及脉冲生成模块,通过模式选择与切换模块、开关角计算模块与选择和更新模块的连接可以降低逆变模块内IGBT的开关损耗,降低开关管的电流应力,从而有助于提高电机控制性能；通过选择和更新模块与脉冲生产模块的连接,以使电机电流谐波分量总体最小,减小电流谐波和转矩脉动。(A minimum current harmonic pulse width modulation system based on stator flux linkage comprises an inversion module and a control unit, wherein a processor module of the control unit comprises a signal filtering module, a modulation degree calculation module, a frequency and angle calculation module, a mode selection and switching module, a switch angle calculation module, a selection and updating module and a pulse generation module; the current harmonics and torque ripple are reduced by selecting and updating the connections of the module to the pulse generation module to minimize the overall motor current harmonic component.)

1. The utility model provides a minimum current harmonic pulse width modulation system based on stator flux linkage, includes contravariant module, the control unit, wherein the control unit includes power module, signal processing module and processor module, power module and signal processing module and processor module are connected respectively, provide the power for signal processing module and processor module, signal processing module and processor module are connected, provide external signal for processor module, the final pulse width modulation control that realizes under the external signal condition of receiving of processor module, its characterized in that:

the processor module is used for realizing minimum current harmonic pulse width modulation, and comprises the following components:

the signal filtering module is used for filtering external rotating speed, voltage and current signals and then transmitting the signals to the modulation degree calculating module and the frequency and angle calculating module;

the modulation degree calculation module is used for calculating the modulation degree and outputting the calculated modulation degree to the mode selection and switching module and the switching angle calculation module;

the frequency and angle calculation module is used for calculating frequency and angle and outputting the calculated frequency and angle to the mode selection and switching module and the selection and updating module;

the mode selection and switching module receives the modulation degree and the frequency as judgment conditions and outputs the modulation mode to the switching angle calculation module and the selection and update module;

the switching angle calculation module is used for calculating the switching angle of the minimum current harmonic pulse width modulation and outputting the switching angle to the selection and updating module; optimizing the weighted harmonic total-distortion rate by using computer software to solve a switching angle by using the stator flux linkage as a reference system and the fundamental amplitude as a constraint condition;

the selection and update module is used for receiving the frequency calculation period value output by the frequency and angle calculation module and transmitting the frequency calculation period value to the pulse generation module, receiving the angle output by the frequency and angle calculation module and judging the sector value, receiving the modulation mode output by the mode selection and switching module, calculating the duty ratio in the current modulation mode and transmitting the duty ratio to the pulse generation module;

and the pulse generation module is used for generating an IGBT pulse signal according to the period value and the duty ratio and driving the IGBT of the inversion module.

2. The stator flux linkage based minimum current harmonic pulse width modulation system of claim 1, wherein: the signal filtering module mainly comprises a clock unit, a serial-parallel conversion unit, a pre-addition unit, a multiply-accumulate unit and a register output unit, wherein the clock unit is connected with the serial-parallel conversion unit, the pre-addition unit, the multiply-accumulate unit and the register output unit and is used for providing clocks for the units; the serial-parallel conversion module is connected with the pre-addition unit and the multiplication and accumulation unit, performs parallel and serial conversion on the signals output by the signal sampling unit, and then transmits the signals to the pre-addition unit and the multiplication and accumulation unit; the pre-adding unit is connected with the register output unit, shifts and adds the data output by the serial-parallel conversion module, and transmits the processed data to the register output unit; the multiply-accumulate unit is connected with the register output unit, compares, adds and shifts the data output by the serial-parallel conversion module, and transmits the processed data to the register output unit.

3. The stator flux linkage based minimum current harmonic pulse width modulation system of claim 1, wherein: the mode selection and switching module compares the stator frequency with a frequency threshold value, and compares the modulation degree with a modulation degree threshold value according to the stator frequency and the modulation degree, firstly judges whether the frequency is greater than a first frequency threshold value, and then judges whether the modulation degree is greater than the first modulation degree threshold value, if so, the square wave modulation is carried out, otherwise, the frequency division is carried out by 6; then, judging whether the frequency is greater than a second frequency threshold, if so, judging whether the modulation degree is greater than a second modulation degree threshold, if so, dividing by 6, otherwise, dividing by 12; and finally, judging that the frequency is greater than a third frequency threshold, if not, judging the frequency is normal synchronous modulation, if so, judging whether the modulation degree is greater than a third modulation degree threshold, if so, dividing the frequency by 12, otherwise, dividing the frequency by 18.

4. The stator flux linkage based minimum current harmonic pulse width modulation system of claim 1, wherein: the selection and update module comprises a clock unit, a period value calculation unit, a duty ratio calculation unit and a sector judgment unit, wherein the clock unit is connected with the period calculation unit and is used for calculating a period value together with the frequency; the period calculating unit is connected with the duty ratio calculating unit and used for providing a period value; the sector judging unit is connected with the duty ratio calculating unit and used for providing a sector number; the duty ratio calculation unit calculates the duty ratio according to the modulation mode, the switching angle, the period value and the sector number.

5. The stator flux linkage based minimum current harmonic pulse width modulation system of claim 1, wherein: the pulse generation module comprises a clock unit, a period conversion unit, a counter unit, a duty ratio conversion unit and a comparison unit, wherein the clock unit is connected with the period conversion unit, the counter unit, the duty ratio conversion unit and the comparison unit and used for providing clocks for the units; the period conversion unit is connected with the counter unit and the duty ratio conversion unit and used for converting the period value provided by the selection and update module into a period value corresponding to the pulse generation module and transmitting the converted period value to the counter unit and the duty ratio conversion unit; the counter unit is connected with the comparison unit, is used for generating a triangular carrier according to the period value and transmits the generated triangular carrier to the comparison unit; the duty ratio conversion unit is connected with the comparison unit and used for converting the duty ratio provided by the selection and update module into the duty ratio corresponding to the pulse generation module and transmitting the converted duty ratio to the comparison unit; the comparison unit is used for generating IGBT pulse signals according to the triangular carrier waves and the duty ratio and driving six IGBTs of the inversion module.

Technical Field

The invention relates to a pulse width modulation control technology, in particular to a minimum current harmonic pulse width modulation control system.

Background

The subway is of great importance in urban rail transit, and a subway vehicle traction system is a key core component of a subway vehicle. The metro vehicle traction system has the advantages of larger power, low switching frequency and wider speed operation range, so that the IGBT switching loss in the system is large, the current harmonic content is high, the torque ripple is large, and the operation stability is poor. In order to make the metro vehicle traction system have low switching loss, low current harmonic content, small torque ripple, and stable operation in the whole speed range, the traction system usually adopts a multi-mode pulse width modulation control technology (shown in fig. 2) for reducing switching loss, reducing current harmonic content, reducing torque ripple, and improving control performance.

The multi-mode pulse width modulation control technology generally adopts low-frequency time asynchronous modulation, intermediate-frequency time common regular sampling synchronous modulation and special synchronous modulation, and high-frequency time single pulse square wave modulation.

The existing special synchronous modulation technology such as overmodulation and middle 60-degree synchronous modulation can effectively reduce voltage harmonics, but has a small effect on reducing current harmonics, so that the optimization effect on switching loss and torque ripple is limited.

Disclosure of Invention

The invention aims to provide a minimum current harmonic pulse width modulation system based on stator flux linkage, which can effectively reduce switching loss, improve current harmonic under low carrier ratio and reduce torque ripple, thereby being beneficial to improving the control performance of a motor.

In order to achieve the above object, the present invention provides a minimum current harmonic pulse width modulation system based on stator flux linkage, including an inverter module and a control unit, wherein the control unit includes a power module, a signal processing module and a processor module, the power module is respectively connected with the signal processing module and the processor module, and provides power for the signal processing module and the processor module, the signal processing module is connected with the processor module, and provides external signals for the processor module, and the processor module finally realizes pulse width modulation control under the condition of receiving the external signals, and is characterized in that:

the processor module is used for realizing minimum current harmonic pulse width modulation, and comprises the following components:

the signal filtering module is used for filtering external rotating speed, voltage and current signals and then transmitting the signals to the modulation degree calculating module and the frequency and angle calculating module;

the modulation degree calculation module is used for calculating the modulation degree and outputting the calculated modulation degree to the mode selection and switching module and the switching angle calculation module;

the frequency and angle calculation module is used for calculating frequency and angle and outputting the calculated frequency and angle to the mode selection and switching module and the selection and updating module;

the mode selection and switching module receives the modulation degree and the frequency as judgment conditions and outputs the modulation mode to the switching angle calculation module and the selection and update module;

the switching angle calculation module is used for calculating the switching angle of the minimum current harmonic pulse width modulation and outputting the switching angle to the selection and updating module; and optimizing the weighted harmonic total-distortion ratio by using the stator flux linkage as a reference system and the fundamental wave amplitude as a constraint condition and using computer software to solve the switching angle.

The selection and update module is used for receiving the frequency calculation period value output by the frequency and angle calculation module and transmitting the frequency calculation period value to the pulse generation module, receiving the angle output by the frequency and angle calculation module and judging the sector value, receiving the modulation mode output by the mode selection and switching module, calculating the duty ratio in the current modulation mode and transmitting the duty ratio to the pulse generation module;

and the pulse generation module is used for generating an IGBT pulse signal according to the period value and the duty ratio and driving the IGBT of the inversion module.

The signal filtering module mainly comprises a clock unit, a serial-parallel conversion unit, a pre-addition unit, a multiply-accumulate unit and a register output unit, wherein the clock unit is connected with the serial-parallel conversion unit, the pre-addition unit, the multiply-accumulate unit and the register output unit and is used for providing clocks for the units; the serial-parallel conversion module is connected with the pre-addition unit and the multiplication and accumulation unit, performs parallel and serial conversion on the signals output by the signal sampling unit, and then transmits the signals to the pre-addition unit and the multiplication and accumulation unit; the pre-adding unit is connected with the register output unit, shifts and adds the data output by the serial-parallel conversion module, and transmits the processed data to the register output unit; the multiply-accumulate unit is connected with the register output unit, compares, adds and shifts the data output by the serial-parallel conversion module, and transmits the processed data to the register output unit.

The mode selection and switching module compares the stator frequency with a frequency threshold value, and compares the modulation degree with a modulation degree threshold value according to the stator frequency and the modulation degree, firstly judges whether the frequency is greater than a first frequency threshold value, and then judges whether the modulation degree is greater than the first modulation degree threshold value, if so, the square wave modulation is carried out, otherwise, the frequency division is carried out by 6; then, judging whether the frequency is greater than a second frequency threshold, if so, judging whether the modulation degree is greater than a second modulation degree threshold, if so, dividing by 6, otherwise, dividing by 12; and finally, judging that the frequency is greater than a third frequency threshold, if not, judging the frequency is normal synchronous modulation, if so, judging whether the modulation degree is greater than a third modulation degree threshold, if so, dividing the frequency by 12, otherwise, dividing the frequency by 18.

The selection and update module comprises a clock unit, a period value calculation unit, a duty ratio calculation unit and a sector judgment unit, wherein the clock unit is connected with the period calculation unit and is used for calculating a period value together with the frequency; the period calculating unit is connected with the duty ratio calculating unit and used for providing a period value; the sector judging unit is connected with the duty ratio calculating unit and used for providing a sector number; the duty ratio calculation unit calculates the duty ratio according to the modulation mode, the switching angle, the period value and the sector number.

The pulse generation module comprises a clock unit, a period conversion unit, a counter unit, a duty ratio conversion unit and a comparison unit, wherein the clock unit is connected with the period conversion unit, the counter unit, the duty ratio conversion unit and the comparison unit and used for providing clocks for the units; the period conversion unit is connected with the counter unit and the duty ratio conversion unit and used for converting the period value provided by the selection and update module into a period value corresponding to the pulse generation module and transmitting the converted period value to the counter unit and the duty ratio conversion unit; the counter unit is connected with the comparison unit, is used for generating a triangular carrier according to the period value and transmits the generated triangular carrier to the comparison unit; the duty ratio conversion unit is connected with the comparison unit and used for converting the duty ratio provided by the selection and update module into the duty ratio corresponding to the pulse generation module and transmitting the converted duty ratio to the comparison unit; the comparison unit is used for generating IGBT pulse signals according to the triangular carrier waves and the duty ratio and driving six IGBTs of the inversion module.

The positive effects produced by the scheme adopted by the invention are as follows:

the minimum current harmonic pulse width modulation control system comprises an inverter module and a control unit, wherein the switching loss of an IGBT (insulated gate bipolar transistor) in the inverter module can be reduced and the current stress of a switching tube is reduced by connecting a processor module mode selection and switching module and a switching angle calculation module with a selection and updating module, so that the control performance of a motor is improved; the current harmonics and torque ripple are reduced by selecting and updating the connections of the module to the pulse generation module to minimize the overall motor current harmonic component.

Drawings

FIG. 1 is a traction system control block diagram;

FIG. 2 is a diagram of a multi-mode pulse width modulation control technique;

FIG. 3 is a block diagram of the control unit;

FIG. 4 is a diagram of the processor module architecture in the control unit;

FIG. 5 is a diagram of the signal filtering module logic in the processor module;

FIG. 6 is a flow diagram of the mode selection and switching module logical relationship in a processor module;

FIG. 7 is a switch angle distribution diagram;

FIG. 8 is a diagram of a selection and update module logical relationship in a processor module;

FIG. 9 is a diagram of the pulse generation module logic in the processor module.

Detailed Description

Referring to fig. 1, the traction system includes a traction inverter, a motor, and the like, the traction inverter includes a dc module, an inverter module, and a control unit, and the control unit sends PWM pulse signals (chopper control and inverter control) through internal processing and calculation by analog quantity signals (voltage Vdc, torque Te, rotation speed Spd, and current Iu/Iv) input from outside, and further controls on and off of the IGBT, thereby realizing chopper control and inverter control. The modulation system is actually a part of a traction inverter control system (motor control system), mainly comprises an inverter module and a control unit, and can realize accurate control of the motor under the working conditions of vehicle traction and braking.

Referring to fig. 2, a diagram of a multi-mode pulse width modulation control technique commonly used in a traction system is shown, in which a horizontal axis represents a motor stator frequency (unit Hz), a vertical axis represents an IGBT switching frequency (unit Hz), asynchronous modulation (switching frequency is unchanged) is adopted at a low frequency, regular sampling common synchronous modulation (carrier ratio is unchanged) is adopted at a medium frequency, special synchronous modulation (carrier ratio is unchanged) is adopted at a high frequency, and finally square wave modulation (carrier ratio is 1) is performed. The special synchronous modulation is the core content of the invention, reduces the switching loss of the IGBT in the inverter module, and reduces the current harmonic wave and the torque ripple.

Referring to fig. 3, the control unit includes a power module, a signal processing module and a processor module, wherein the power module is connected with the signal processing module and the processor module to provide power for the signal processing module and the processor module; the signal processing module is connected with the processor module and provides an external signal for the processor module; the processor module finally realizes the minimum current harmonic pulse width modulation control method under the condition of receiving an external signal. The minimum current harmonic pulse width modulation control is implemented inside the processor module by schematic input or software language programming and in a modular approach.

Referring to fig. 4, the processor module includes a signal filtering module, a modulation degree calculation module, a frequency and angle calculation module, a mode selection and switching module, a switching angle calculation module, a selection and update module, and a pulse generation module. The signal filtering module is connected with the modulation degree calculation module and the frequency and angle calculation module, and is used for filtering the rotating speed, the voltage and the current of an external signal and then transmitting the filtered external signal to the modulation degree calculation module and the frequency and angle calculation module; the modulation degree calculation module is connected with the mode selection and switching module and the switch angle calculation module and transmits the modulation degree output by calculation to the mode selection and switching module and the switch angle calculation module; the frequency and angle calculation module is connected with the mode selection and switching module and the selection and updating module, transmits the calculated and output frequency to the mode selection and switching module, and transmits the calculated and output frequency and angle to the selection and updating module; the frequency output by the frequency and angle calculation module is used for judging conditions by the mode selection and switching module; the frequency output by the frequency and angle calculation module is used for calculating the period value in the selection and update module, and the output angle is used for judging the sector value in the selection and update module. The mode selection and switching module is connected with the switching angle calculation module and the selection and updating module, and transmits the modulation mode output by calculation to the switching angle calculation module and the selection and updating module; the switching angle calculation module is connected with the selection and update module and transmits the switching angle output by calculation to the selection and update module; the selection and update module is connected with the pulse production module, calculates an output period value and a duty ratio according to the frequency, the angle, the modulation mode and the switching angle, and then transmits the output period value and the duty ratio to the pulse production module; the pulse production module is used for generating IGBT pulse signals according to the period value and the duty ratio, and driving six IGBTs of the inversion module to realize minimum current harmonic pulse width modulation control.

Referring to fig. 5, the signal filtering module mainly includes a clock unit, a serial-to-parallel conversion unit, a pre-addition unit, a multiply-accumulate unit, and a register output unit, where the clock unit is connected with the serial-to-parallel conversion unit, the pre-addition unit, the multiply-accumulate unit, and the register output unit to provide clocks for these units; the serial-parallel conversion module is connected with the pre-addition unit and the multiplication and accumulation unit, performs parallel and serial conversion on the signals output by the signal sampling unit, and then transmits the signals to the pre-addition unit and the multiplication and accumulation unit; the pre-adding unit is connected with the register output unit, shifts and adds the data output by the serial-parallel conversion module, and transmits the processed data to the register output unit; the multiply-accumulate unit is connected with the register output unit, compares, adds and shifts the data output by the serial-parallel conversion module, and transmits the processed data to the register output unit.

Referring to fig. 6, the mode selection and switching module determines the position of the stator flux linkage circle according to the stator frequency and the modulation degree, and then judges the minimum current harmonic modulation mode, and the minimum current harmonic pulse width modulation mode mainly outputs three modulation modes of 6 frequency division, 12 frequency division and 18 frequency division. Firstly, judging whether the frequency is greater than a first frequency threshold value, then judging whether the modulation degree is greater than a first modulation degree threshold value, if so, performing square wave modulation, and if not, performing frequency division of 6; then, judging whether the frequency is greater than a second frequency threshold, if so, judging whether the modulation degree is greater than a second modulation degree threshold, if so, dividing by 6, otherwise, dividing by 12; and finally, judging that the frequency is greater than a third frequency threshold, if not, performing ordinary synchronous modulation, if so, judging whether the modulation degree is greater than a third modulation degree threshold, if so, performing frequency division by 12, otherwise, performing frequency division by 18.

Referring to fig. 7, the switching angle distribution diagram shows the position of the switching angle in the stator flux linkage on the right side and the IGBT pulse signal corresponding to the switching angle on the left side. The method comprises the steps of firstly calculating stator flux linkage according to a motor control algorithm, then equally dividing the stator flux linkage under the current modulation mode according to a modulation mode provided by a mode selection and switching module, determining the number of switching angles, and finally calculating the switching angles under the current modulation mode according to a known fundamental wave amplitude value, a known minimum current constraint condition and a modulation degree output by a modulation degree calculation module.

Referring to fig. 8, the selecting and updating module includes a clock unit, a period value calculating unit, a duty ratio calculating unit, and a sector judging unit. The clock unit is connected with the period calculation unit and is used for calculating a period value together with the frequency; the period calculating unit is connected with the duty ratio calculating unit and used for providing a period value; the sector judging unit is connected with the duty ratio calculating unit and used for providing a sector number; the duty ratio calculation unit calculates the duty ratio according to the modulation mode, the switching angle, the period value and the sector number.

Referring to fig. 9, the pulse generation module includes a clock unit, a period conversion unit, a counter unit, a duty conversion unit, and a comparison unit. The clock unit is connected with the period conversion unit, the counter unit, the duty ratio conversion unit and the comparison unit and is used for providing clocks for the units, and the clock unit is set to be 10 us; the period conversion unit is connected with the counter unit and the duty ratio conversion unit and used for converting the period value provided by the selection and update module into a period value corresponding to the pulse generation module and transmitting the converted period value to the counter unit and the duty ratio conversion unit; the counter unit is connected with the comparison unit, and the counter unit is used for generating a triangular carrier wave according to the period value and transmitting the generated triangular carrier wave to the comparison unit. The duty ratio conversion unit is connected with the comparison unit and used for converting the duty ratio provided by the selection and update module into the duty ratio corresponding to the pulse generation module and transmitting the converted duty ratio to the comparison unit. The comparison unit is used for generating IGBT pulse signals according to the triangular carrier waves and the duty ratio and driving six IGBTs of the inversion module.

The modulation process of the invention:

1. the power module provides power for the signal processing module and the processor module.

2. The signal processing module samples, amplifies and sets the external signal and then sends the external signal to the processor module.

3. And a signal filtering module of the processor module carries out filtering processing on the rotating speed, the voltage and the current of an external signal.

4. A modulation degree calculation module of the processor module calculates a modulation degree according to the voltage and the current.

5. And the frequency and angle calculation module of the processor module calculates the stator frequency and the control angle according to the rotating speed.

6. And the mode selection and switching module and the switching angle calculation module of the processor module respectively output a modulation mode and a switching angle according to the modulation degree and the frequency and the division of the stator flux linkage circle.

7. The selection and update module of the processor module calculates a period value and a duty cycle according to the modulation mode, the switching angle, the frequency and the angle.

8. The pulse generation module of the processor module is used for generating IGBT pulse signals, driving six IGBTs of the inversion module and accurately controlling the motor.