CN102594249A - Velocity sensorless vector control method for single bus current detection of three-phase alternating-current motor - Google Patents

Abstract

The invention discloses a unique velocity sensorless vector control method for single bus current detection of a three-phase alternating-current motor. The velocity sensorless vector control method comprises the steps of detecting the bus current by a shunt resistor mounted on the bus low voltage side of a frequency changer, determining the trigger time adopted by the bus current according to the pulse width modulation PWM duty ratio of a control switch, and correspondingly reconstructing three-phase current of the motor. According to the motor current reconstruction method, a motor current direct detection hardware circuit is detected, so that the hardware cost is saved, and the same performance as the vector control of the motor three-phase current direct detection can be achieved. The velocity sensorless vector control method is suitable for a space vector PWM mode and is favorable for solving the problems of sector boundary and low modulation region in a vector method based on space switching. Analysis of experimental results shows that the motor current reconstruction method is also suitable for other any switch modulation mode and is higher in commonality and practicality. Particularly in small current and low modulation regions, the three-phase current of the motor also can be precisely reconstructed.

Description

Three phase alternating current motor single busbar connection electric current inspection Speedless sensor vector control method

Technical field:

The present invention relates to Speedless sensor vector control (SVC) three-phase permanent-magnetic synchronous motors (PMSM), particularly a kind ofly realize single busbar connection current detecting Speedless sensor vector control method through reconstruct three phase alternating current motor electric current.

Background technology:

Vector control is current most popular a kind of high-performance motor control method.Through the coordinate vector conversion, the three-phase current of motor resolves into two mutually perpendicular dq shaft currents: flux component and torque component, directly control the magnetic flux and the torque of motor then as direct current machine, to realize Fast Dynamic response and accurate control.

The Speedless sensor vector control has been eliminated the velocity transducer (normally encoder) of motor, and the electric current through motor observes rotating speed of motor and position.So not only reduce the cost of Electric Machine Control hardware, also improved the reliability of system.

Generally, the biphase current that the Speedless sensor vector control need detect motor at least is used for observing the magnetic linkage of motor, and then calculates the position and the speed of motor.Current detecting hardware has increased cost.Therefore; Prior art personnel focus on exploitation single busbar connection current detecting vector control more; Purpose is that the deletion current of electric directly detects, and detects bus current through a shunt resistance that is installed in frequency converter bus low-pressure side, and then reconstructs the three-phase current of motor.

On the other hand, existing known solutions all is according to six switch space vectors of voltage source inverter pattern, confirms that directly the dc bus current of taking is which phase current in the motor three-phase current.Because three brachium pontis of voltage source inverter always have six non-zero status, each on off state correspondingly corresponding the phase current that flows through of motor.Therefore, can obtain each phase current of motor according to six space vectors of space vector pulse width modulation (SVPWM).For example, Delpha, the single busbar connection current of electric reconstructing method principle of STmicroelectronics and Freescale all is like this.Yet this current of electric reconstructing method existing problems, space vector pulse width modulation (SVPWM) if the time that effective vector continues is less than the current sample time, can be made mistakes in the sector borders and low modulation region of space vector.Some disclosed schemes are then taked compensatory approach for this reason, be in adjacent boundary, to insert effective vector, but inserting effective vector can bring distortion to current waveform.Simultaneously, this method only is confined to the space vector pulse width modulation pattern, and for other pulse width modulation mode, the phase current of this motor directly equals the bus current method just can not be used.

Summary of the invention:

In view of the defective of above-mentioned prior art and the demand of practical application, the present invention proposes a kind of three phase alternating current motor single busbar connection current detecting Speedless sensor vector control method of uniqueness.Detect bus current through a shunt resistance that is installed in frequency converter bus low-pressure side,, confirm the triggered time that bus current is taked, correspondingly the three-phase current of reconstruct motor according to the pulse-width modulation PWM duty ratio size of control switch.The current of electric reconstructing method of invention has been deleted the direct detection hardware circuit of current of electric, saves hardware cost, can reach again with the motor three-phase current and directly detect the same performance of vector control.

The inventive method comprises the steps:

(1) is provided with by AC/DC rectifier, a voltage source inverter and the ware circuit of forming based on the electric machine controller of microprocessor that the band dc bus current detects; Voltage source inverter is the power supply that motor provides three-phase voltage and frequency adjustable; Electric machine controller is used for realizing current of electric restructing algorithm and single busbar connection current detecting Speedless sensor vector control method; Said system is the basis of exploitation current of electric reconstruct and control hardware platform.

(2) the input dc bus current, is confirmed two ADC input channel hardware trigger times according to the pulse-width modulation PWM duty ratio, and is correspondingly read the three-phase current of motor to numeral (ADC) passage AN0 and AN6 to two logics of microprocessor;

(3) read the bus current sampled value, and what confirm reconstruct according to pulse-width modulation PWM duty ratio size is that phase current; Current sampling data deducts the zero current deviant, calculates the actual value of bus current;

(4) under six kinds of on off states of voltage source inverter, repeat to read two ADC channel current values, the three-phase current of reconstruct motor;

(5) through the coordinate vector conversion, decomposed and reconstituted three-phase current becomes two mutually perpendicular dq axle direct currents, i.e. flux component and torque component, thus realize single busbar connection current detecting Speedless sensor vector control.

Can know by the contrast of the invention described above method; Usually the three phase alternating current motor vector control need detect the three-phase current of motor; Transform to dq axle two phase direct currents then; So just can directly control the magnetic flux and the torque of motor, reach the quick and accurate performance that compares favourably with DC MOTOR CONTROL.The three-phase current that directly detects motor has increased hardware cost.The inventive method is utilized the three-phase alternating current of dc bus current reconstruct motor, has deleted the direct detection hardware circuit of current of electric and has provided cost savings, and can reach again with three-phase current directly to detect the same performance of control.

In addition; Single busbar connection current of electric reconstructing method of the present invention is the pulse-width modulation PWM duty ratio size according to six switch controls; Confirm the timer triggered time of microprocessor; Correspondingly trigger the electric current that two ADC passages remove to take dc bus through hardware, and then the three-phase current of reconstruct motor correspondingly.This method is not only applicable to the space vector pulse width modulation pattern, and has eliminated based on sector borders that exists in the space switching vector method and low modulation region problem.In addition, interpretation shows that current of electric reconstructing method of the present invention also is applicable to other any switch modulation pattern, has more versatility and practicality.Particularly in little electric current and low modulation region, it also can reconstruct the three-phase current of motor accurately.

Description of drawings:

Further specify the present invention below in conjunction with accompanying drawing and embodiment.

Fig. 1 is single busbar connection current detecting Speedless sensor vector control hardware development platform structure figure.

Fig. 2 triggers current of electric reconstruct sketch map for timer.

Fig. 3 is a motor three-phase current reconstruct Speedless sensor vector control control implementation strategy block diagram.

The electric machine phase current oscillogram that Fig. 4 comes out for reconstruct under the no-load condition.

The electric machine phase current oscillogram that Fig. 5 comes out for reconstruct under the full load conditions.

The electric machine phase current oscillogram of Fig. 6 for directly detecting under the no-load condition.

The electric machine phase current oscillogram of Fig. 7 for directly detecting under the full load conditions.

The Speedless sensor vector control speed load response curve that Fig. 8 comes out for current of electric reconstruct.

The Speedless sensor vector control speed load response curve that Fig. 9 directly detects for current of electric.

Embodiment:

For technological means, creation characteristic that the present invention is realized, reach purpose and effect and be easy to understand and understand, below in conjunction with concrete diagram, further set forth the present invention.

In order to realize three phase alternating current motor single busbar connection electric current inspection Speedless sensor vector control method of the present invention, the practical implementation process comprises:

(1) hardware circuit setting;

At first, specifically introduce hardware circuit related among the present invention program.

As shown in Figure 1, this system mainly comprise one by AC to the DC rectifier, the voltage source inverter (VSI) that dc bus and DC form to the AC inverter and one are the controller of center processing unit with the microprocessor.Voltage source inverter is to be used for the three phase mains that provides frequency and voltage to regulate to motor.Controller is three-phase current restructing algorithm and the Speedless sensor vector control scheme that is used for realizing motor.Shown in system take busbar voltage, bus current, and the three-phase current of motor.Three-phase current detection mainly is to be used for doing contrast test, and directly to detect vector control approaching with the current of electric of routine to confirm the performance of current of electric reconstructing method and single busbar connection electric current Speedless sensor vector control of exploitation.In fact, the phase current of in the present invention program, having deleted motor detects, and what system only need take is busbar voltage and electric current.It is through being installed in a shunt resistance detection of frequency converter bus low-pressure side, being input to the three-phase current that microprocessor (MCU) calculates motor then that bus current is taked.

(2) electric current reconstructing method;

As stated, the three-phase current of motor is not direct with three current sensor senses, but comes out through the bus current reconstruction calculations.Based on pulse-width modulation PWM duty ratio size, the inventive method has been developed the electric current reconstructing method of a uniqueness.

Fig. 2 has shown the dc bus current that is detected by a shunt resistance, is input to two ADC passages of electric machine controller (microprocessor), confirms to trigger the time of ADC passage according to pulse-width modulation PWM duty ratio size, and correspondingly reads the three-phase current of motor.Shown in this figure went up: the PWM dutyfactor value of W phase was maximum, and V takes second place mutually, the minimum of U phase.

If detect bus current mutually and between the rising edge of V phase at W; This electric current confirms it is the W phase current; Because in this case, have only W to be only conducting mutually, it is conducting that three brachium pontis that is to say inverter have only the last brachium pontis switch I GBT of W phase; Therefore, the bus current that measures on the shunt resistance only is the W phase current.Next pwm pulse, if the electric current that detects is between the rising edge of V phase and U phase, this biphase current is measured mutually with V mutually for W so, this means that the U phase current is measured, because for a three-phase symmetrical system, all three-phase current summations should be zero.

Therefore, the three-phase current reconstruct of bus current measurement and motor must be read under a precise time.In break period,, need to use two timer passage MTU2S4.TADCOBRA and MTU2S4.TADCOBRB to come regularly to control the triggered time at a PWM in order accurately to trigger the three-phase electricity flow valuve that these two ADC passages read motor.According to known PWM output duty cycle, calculate the accurate triggered time of these two ADC passages.

Microprocessor has multi-functional timer pulse passage, comprises a plurality of 16 or 32 bit timing devices.In the concrete implementation procedure of the present invention; Two timer passage MTU2S4.ADCOBRA and MTU2S4.TADCOBRB are used as bus current and detect timer; PWM dutyfactor value according to each stage switch state calculates precise time, triggers ADC passage AN0 and AN6.

The major part of this algorithm is to compare the three-phase PWM dutyfactor value, to confirm MTU2S4.TADCOBRA, two timer triggered times of MTU2S4.TADCOBRB.Because three PWM dutyfactor values are continuous variations, the PWM duty ratio of W phase is always maximum, therefore, a suitable sign need be set at every turn indicate and currently carrying out which phase PWM value is maximum in the current phasor measurement.All PWM dutyfactor values compare, the setting of facies marker, and the calculating of ADC passage triggered time is a complex processing process accordingly, need take more CPU processing time and internal memory.The direct current detection scheme Speedless sensor of CPU bandwidth ratio vector control requires high.Therefore, for single busbar connection current detecting Speedless sensor vector control, ADC passage AN0 and AN6 trigger and realized by hardware, thereby save ADC change-over time.In addition, the microprocessor of algorithm execution need have higher operational capability, and it is simple and accurate to make bus current detection and the reconstruct of motor three-phase current realize.

As stated, take bus current through two ADC passage AN0 and AN6, sampled value leaves iw0ad and iw6ad respectively in.Duty ratio according to three-phase PWM: du, dv and dw calculate ADC and trigger timer time and corresponding current of electric conversion is set.Practical implementation is described below:

1) if du＞dv＞dw is provided with MTU2S4.TADCOBRA, two timer triggered times of MTU2S4.TADCOBRB are respectively:

MTU2S4.TADCOBRA＝dv+SS

MTU2S4.TADCOBRB＝dw+SS

The SS value is decided by ADC sampling time and hardware circuit setting-up time.

The conversion bus current is U phase and W electric current mutually:

ium＝iw0ad-iw0_off

iwm＝-iw6ad+iw6_off

Iw0_off and iw6_off are respectively the dc buss that two ADC passage AN0 and AN6 take

The deviant of zero current.

2) if du＞dw＞dv is provided with MTU2S4.TADCOBRA, two timer triggered times of MTU2S4.TADCOBRB are respectively:

MTU2S4.TADCOBRA＝dw+SS

MTU2S4.TADCOBRB＝dv+SS

The conversion bus current is U phase and V electric current mutually:

ium＝iw0ad-iw0_off

ivm＝-iw6ad+iw6_off

3) if dw＞du＞dv is provided with MTU2S4.TADCOBRA, two timings of MTU2S4.TADCOBRB

The device triggered time is respectively:

MTU2S4.TADCOBRA＝du+SS

MTU2S4.TADCOBRB＝dv+SS

The conversion bus current is W phase and V electric current mutually:

iwm＝iw0ad-iw0_off

ivm＝-iw6ad+iw6_off

4) if dv＞du＞dw is provided with MTU2S4.TADCOBRA, two timer triggered times of MTU2S4.TADCOBRB are respectively:

MTU2S4.TADCOBRA＝du+SS

MTU2S4.TADCOBRB＝dw+SS

The conversion bus current is U phase and W electric current mutually:

ium＝iw0ad-iw0_off

iwm＝-iw6ad+iw6_off

5) if dv＞dw＞du is provided with MTU2S4.TADCOBRA, two timer triggered times of MTU2S4.TADCOBRB are respectively:

MTU2S4.TADCOBRA＝dw+SS

MTU2S4.TADCOBRB＝du+SS

The conversion bus current is V phase and U electric current mutually:

ivm＝iw0ad-iw0_off

i?um＝-iw6ad+iw6_off

6) if dw＞dv＞du is provided with MTU2S4.TADCOBRA, two timer triggered times of MTU2S4.TADCOBRB are respectively:

MTU2S4.TADCOBRA＝dv+SS

MTU2S4.TADCOBRB＝du+SS

The conversion bus current is W phase and U electric current mutually:

iwm＝iw0ad-iw0_off

ium＝-iw6ad+iw6_off

Voltage source inverter provides motor three phase variable frequency variable-voltage power supply, and six switches of three brachium pontis always have six non-zero status.Therefore, six kinds of top situations have comprised this six states, thereby the conversion bus current is the three-phase current of motor.

(3) electric current reconstructing is used and Speedless sensor vector control implementation strategy;

The motor three-phase current that reconstructs becomes two phase dq axle direct currents through transform vector.Transform vector is divided into two steps and gathers.At first be the Clarke conversion, the three-phase alternating current of conversion motor is two mutually mutually perpendicular alternating current ia and i β.

$\left[\begin{array}{c}{i}_{\mathrm{\α}}\\ i_{\mathrm{\β}}\end{array}\right]=\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}& -\frac{\sqrt{3}}{2}\end{array}\right]\left[\begin{array}{c}{i}_u\\ i_v\\ i_w\end{array}\right]$

Second step was the Park conversion, and the two-phase alternating current ia that further changes motor and i β are two direct current id and iq mutually.

$\left[\begin{array}{c}{i}_d\\ i_q\end{array}\right]=\left[\begin{array}{cc}\cos \mathrm{\θ}& \sin \mathrm{\θ}\\ -\sin \mathrm{\θ}& \cos \mathrm{\θ}\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{\α}}\\ i_{\mathrm{\β}}\end{array}\right]$

θ is the angle between d shaft current and the U phase current.

Through transform vector, the three-phase alternating current of motor converts two mutually mutually perpendicular direct currents into.Therefore, the vector control three phase alternating current motor can directly be controlled the magnetic flux and the torque of motor just as the control direct current machine.

In conjunction with the current of electric reconstructing method of invention, single busbar connection current detecting Speedless sensor vector control has not only improved the control performance of motor, and saves the three-phase current sample circuit of motor, thereby has further saved hardware cost.

Fig. 3 has described the reconstruct of motor three-phase current and its implementation strategy in Speedless sensor vector control control application.The Speedless sensor vector control of single busbar connection electric current detecting method has been eliminated the position transducer and the direct detecting sensor of phase current of motor.Detect the three-phase current that bus current reconstructs motor by a shunt resistance that is installed in frequency converter bus low-pressure side.Control system is mainly by the motor phase current reconstruction module; The transform vector module comprises the Clarke conversion, Park conversion and Park inverse transformation, rotor-position and flux observer; Speed observer; Speed regulator, flux current and torque current regulator, and space vector and sine pulse width modulation (PWM) pulse width modulator composition.System realizes electric current and speed double closed-loop control, speed outer shroud and current inner loop.What speed and current regulator used is traditional proportional integral PI controller.Electric current loop is directly controlled the flux current and the torque current of motor, just d axle and q shaft current, thereby directly control the magnetic flux and the torque of motor, reach the quick and accurate performance that compares favourably with DC MOTOR CONTROL.

(4) testing and verification;

The three-phase current method of the single busbar connection electric current reconstructing motor of invention is used actual the realization with it on the Speedless sensor vector control.That shown in Figure 1 is development experiments platform structure figure of the present invention.This system is that the controller of center processing unit is formed with the microprocessor by a voltage source inverter (VSI) and one mainly.Voltage source inverter is to be used for the three phase mains that provides frequency and voltage to regulate to motor, and controller is realized the three-phase current restructing algorithm and the vector control scheme of motor.The motor of test is a three-phase permanent magnet synchronous motor.Do not having under the loading condition, the current of electric of this permanent-magnet-field is very little.

In order to compare and verify the current of electric and the control performance of reconstruct, three-phase current directly detects and vector control also realizes.What Fig. 4 showed is the electric machine phase current that reconstruct is come out under the no-load condition, is a very sinusoidal and very little alternating current, and this is because the single busbar connection current detecting vector control that realizes can be accomplished accurate flux orientation.Fig. 5 is the electric machine phase current that reconstruct is come out under the full load conditions, general 1.5 amperes of current amplitude.Fig. 6 and Fig. 7 show respectively be unloaded with hide the electric machine phase current that directly detects under the situation of carrying from.Compare with Fig. 4 and Fig. 5, the electric machine phase current that reconstruct is come out is very approaching with the actual electric machine phase current that directly detects, and this electric machine phase current of having explained that reconstruct comes out is very accurate.

What Fig. 8 showed is the rate curve that current of electric reconstruct does not have velocity control.Suddenly loading and unloading under the situation, the velocity variations of motor is very little, and can get back to setting speed very soon, and this shows that electric current reconstructing does not have the fast and control precision height of velocity control dynamic response.Fig. 9 is the rate curve that current of electric directly detects no velocity control.Compare with Fig. 8, speed responsive is the same basically with control performance.

Experimental result has confirmed that further single busbar connection current detecting Speedless sensor vector control directly detects the Speedless sensor vector control with current of electric and has consistent performance, has shown that the current of electric reconstructing method of invention has practical application in industry to be worth.

More than show and described basic principle of the present invention and principal character and advantage of the present invention.The technical staff of the industry should understand; The present invention is not restricted to the described embodiments; That describes in the foregoing description and the specification just explains principle of the present invention; Under the prerequisite that does not break away from spirit and scope of the invention, the present invention also has various changes and modifications, and these variations and improvement all fall in the scope of the invention that requires protection.The present invention requires protection range to be defined by appending claims and equivalent thereof.

Claims (4)

1. three phase alternating current motor single busbar connection electric current inspection Speedless sensor vector control method is characterized in that, comprises the steps:

(1) is provided with by AC/DC rectifier, a voltage source inverter and the ware circuit of forming based on the electric machine controller of microprocessor that the band dc bus current detects;

(2) the input dc bus current, is confirmed two ADC input channel hardware trigger times according to the pulse-width modulation PWM duty ratio, and is correspondingly read the three-phase current of motor to numeral (ADC) passage AN0 and AN6 to two logics of microprocessor;

(3) read the bus current sampled value, and what confirm reconstruct according to pulse-width modulation PWM duty ratio size is that phase current; Current sampling data deducts the zero current deviant, calculates the actual value of bus current;

(4) under six kinds of on off states of voltage source inverter, repeat to read two ADC channel current values, the three-phase current of reconstruct motor;

(5) through the coordinate vector conversion, decomposed and reconstituted three-phase current becomes two mutually perpendicular dq axle direct currents, i.e. flux component and torque component, thus realize single busbar connection current detecting Speedless sensor vector control.

2. examine the Speedless sensor vector control method according to the three phase alternating current motor single busbar connection electric current of claim 1; It is characterized in that; In the said step (2); Through using two timer passage MTU2S4.TADCOBRA and MTU2S4.TADCOBRB to come to detect timer as bus current, accurate timing triggers these two ADC passages then.

3. examine the Speedless sensor vector control method according to the three phase alternating current motor single busbar connection electric current of claim 2; It is characterized in that; In the said step (2), establish iw0_off and iw6_off and be respectively the deviant of the dc bus zero current that two ADC passage AN0 and AN6 take, according to the duty ratio of three-phase PWM: du; Dv and dw calculate ADC and trigger timer time and corresponding current of electric conversion is set; Specifically comprise following six kinds of situation:

As du＞dv＞dw, MTU2S4.TADCOBRA=dv+SS, MTU2S4.TADCOBRB=dw+SS; The conversion bus current is U phase and W electric current mutually: ium=iw0ad-iw0_off, iwm=-iw6ad+iw6_off;

As du＞dw＞dv, MTU2S4.TADCOBRA=dw+SS, MTU2S4.TADCOBRB=dv+SS; The conversion bus current is U phase and V electric current mutually: ium=iw0ad-iw0_off, ivm=-iw6ad+iw6_off;

As dw＞du＞dv, MTU2S4.TADCOBRA=du+SS, MTU2S4.TADCOBRB=dv+SS; The conversion bus current is W phase and V electric current mutually: iwm=iw0ad-iw0_off, ivm=-iw6ad+iw6_off;

As dv＞du＞dw, MTU2S4.TADCOBRA=du+SS, MTU2S4.TADCOBRB=dw+SS; The conversion bus current is U phase and W electric current mutually: ium=iw0ad-iw0_off, iwm=-iw6ad+iw6_off;

As dv＞dw＞du, MTU2S4.TADCOBRA=dw+SS, MTU2S4.TADCOBRB=du+SS; The conversion bus current is V phase and U electric current mutually: ivm=iw0ad-iw0_off, ium=-iw6ad+iw6_off;

As dw＞dv＞du, MTU2S4.TADCOBRA=dv+SS, MTU2S4.TADCOBRB=du+SS; The conversion bus current is W phase and U electric current mutually: iwm=iw0ad-iw0_off, ium=-iw6ad+iw6_off.

4. according to the three phase alternating current motor single busbar connection electric current inspection Speedless sensor vector control method of claim 1, it is characterized in that in the said step (5), transform vector comprises:

Step a:Clarke conversion, the three-phase alternating current of conversion motor is two mutually mutually perpendicular alternating current ia and i β, that is: $\left[\begin{array}{c}{i}_{\mathrm{\α}}\\ i_{\mathrm{\β}}\end{array}\right]=\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}& -\frac{\sqrt{3}}{2}\end{array}\right]\left[\begin{array}{c}{i}_u\\ i_v\\ i_w\end{array}\right]$

Step b:Park conversion, the two-phase alternating current ia that further changes motor and i β are two direct current id and iq mutually, that is: $\left[\begin{array}{c}{i}_d\\ i_q\end{array}\right]=\left[\begin{array}{cc}\mathrm{Cos}\mathrm{\θ}& \mathrm{Sin}\mathrm{\θ}\\ -\mathrm{Sin}\mathrm{\θ}& \mathrm{Cos}\mathrm{\θ}\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{\α}}\\ i_{\mathrm{\β}}\end{array}\right].$

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