Background technology
The screen door in past adopts single-chip microcomputer to drive the brush direct current motor formation by decelerator more.This control mode loss is bigger, and control precision is not high and the life-span is not long.Brshless DC motor is a kind of communtatorless element, can overcome effectively has the brush direct current machine because problems such as caused torque ripple of commutation spark and electromagnetic interference, and be easy to control, particularly after having cooperated the PWM Driving technique, make brshless DC motor in control, can reach degree of precision.Direct driving with brshless DC motor realization shield door machine not only makes door apparatus mechanical structure simplify, and manufacturing cost is descended, and Installation and Debugging are convenient, and failure rate is low.Therefore, brshless DC motor is used in the shielding control system widely.
But also there are some problems in brshless DC motor, and there is torque pulsation exactly in wherein topmost problem, makes the application of brshless DC motor in AC servo be restricted.Because existing especially, torque directly driving the occasion of using, owing to there is not deceleration device, torque pulsation can be delivered in the load by rotor under current intelligence, cause unforeseeable velocity fluctuation, thereby produce problems such as vibration, resonance, noise by motor base.Work long hours down and can produce harmful effect the life-span of shield door.Can only be to have proposed on original structure that some weaken, methods of compensation at present, the problem of failing fundamentally to eliminate torque pulsation and being produced.
Direct torque control technology (being called for short DTC) is an another high performance ac variable speed technology after vector control.It has abandoned the control thought of decoupling zero in the vector control, has removed pulse width modulator PWM and current feedback link, has directly controlled the magnetic linkage of motor and torque to obtain torque response and fine control performance fast.
The basic principle of direct Torque Control is that the M.Depenbrock professor of Germany and the I.Takahashi professor of Japan put forward respectively at 1986, is the another great discovery after vector control.
The direct torque control technology adopts the analytical method of space vector, directly calculate and the torque of controlling alternating current motor at the stator coordinate system, adopt stator flux orientation, regulate (control) by means of discrete two point form and produce pulse-width modulation (PWM) signal, directly switching states is carried out Optimal Control, to obtain the high dynamic performance of torque.It has saved the simplification processing of complicated transform vector and motor Mathematical Modeling.Its control thought novelty, control device is direct, and the physical concept of signal processing is clear and definite, and the torque response of this control system is rapid, is a kind of ac speed control method with high static and dynamic performance.
Chinese patent application 200410065332.4 discloses a kind of brshless DC motor first-harmonic method direct Torque Control that relates to the position-sensor-free technology, comprise brshless DC motor, power inverter, the convertor controls signal, based on the control system of digital controlled signal processor, modulus converter A/D and electric current, voltage sensor.This device is according to detected electric current, voltage signal, calculate the magnetic linkage and the torque of motor by digital signal processor wherein, it is compared with given first-harmonic magnetic linkage, given torque, locus by comparative result and magnetic linkage place, directly select for use optimum space voltage vector to act on brshless DC motor, reach the purpose of speed governing by power inverter.
The induction motor that Chinese patent application 02148650.6 discloses a kind of space vector modulation becomes the direct control method of structure torque, its according to stator magnetic linkage amplitude and torque separately the size of error by becoming the stator voltage vector that structure magnetic linkage and torque controller remove to calculate these error convergences of control, again with the switch controlling signal of space vector modulation mode formation voltage inverter method with the control of induction torque.
Above-mentioned the deficiencies in the prior art part is: according to direct torque control theory, Fig. 6 (a) is that torque of the prior art stagnates chain rate than control waveform figure, T
* eBe the stagnant chain rate ideal value of the torque of system input, adopting the torque chain rate that stagnates is that Δ Te regulates torque than threshold value.Fig. 6 (b) is the output waveform figure of the stagnant ring of torque of the prior art control unit, and wherein, the stagnant chain rate of magnetic flux is the forward adjusting time t1 and the negative regulation time t2 of control variables than the output waveform of controller, is to be determined by the torque value Te that system imports.Incoming frequency is higher in system, and during frequent changes, t1, t2 are uncontrollable, are uneven, and promptly switching frequency is unfixing, unfavorable to filtering.This also is the immediate cause that influences the torque control effect of prior art.
Summary of the invention
Technical problem to be solved by this invention provide a kind of torque pulsation that is used for eliminating the brshless DC motor use and torque control effect better, respond Direct Torque brushless DC servo control system and method for work thereof faster.
For solving the problems of the technologies described above, Direct Torque brushless DC servo control system of the present invention comprises:
Coordinate transformation unit: be used for detect motor current signal, voltage signal respectively from the abc coordinate system transformation to the α β stator system of axis, with output stator current signal and stator voltage signal;
Magnetic linkage computing unit: be used for according to the stator magnetic linkage Ψ that calculates motor from the stator current signal of coordinate transformation unit
sGo out stator magnetic linkage Ψ according to stator current signal and stator voltage calculated signals simultaneously from coordinate transformation unit
sAmplitude | Ψ
s| and stator magnetic linkage Ψ
sComponent Ψ
αAnd Ψ
βThen, according to from the stator current signal of coordinate transformation unit, described Ψ
αAnd Ψ
βCalculate stator magnetic linkage Ψ
sAnd the angle theta between a axle of abc coordinate system;
Torque calculation unit: be used for according to described stator current signal with from the described Ψ of magnetic linkage computing unit
αAnd Ψ
βCalculate the stator torque T of motor
e
Magnetic linkage and torque stagnate and encircle control unit: be used for the stator magnetic linkage Ψ from magnetic linkage computing unit
sWith stator torque T from the torque calculation unit
eRespectively with reference value
And T
* eCompare, and be magnetic linkage conditioning signal τ and the torque adjustment signal Phi of 4-8kHz according to comparative result output correspondent frequency;
Switch list: be used for according to the ring control unit that stagnates from magnetic linkage and torque magnetic linkage conditioning signal τ, torque adjustment signal Phi and from the stator magnetic linkage Ψ of magnetic linkage computing unit
sAnd angle theta, determine the space vector of voltage output of a correspondence;
Inverter unit: be used for according to described space vector of voltage control inverter, so that the torque of inverter control motor keeps stable from switch list.
The stagnant ring of magnetic linkage and torque control unit 4 comprises: torque stagnates and encircles control unit 4-1 and the stagnant control unit 4-2 that encircles of magnetic linkage.
In torque stagnates ring control unit 4-1, as described stator torque T
eWith respect to torque reference value T
* eReach the ring upper limit that stagnates
The time, the stagnant ring of torque control unit 4-1 exports corresponding torque adjustment signal Phi to switch
list 5, and
switch list 5 draws the correspondent voltage space vector and exports corresponding high-frequency switching signal, through inverter 6
control motors 7, so that
motor 7 stator torques diminish; Otherwise, as described stator torque T
eWith respect to torque reference value T
* eReach the ring lower limit that stagnates
The time, the stagnant ring of torque control unit 4-1 exports another corresponding torque adjustment signal Phi to switch
list 5,
switch list 5 draws another correspondent voltage space vector and exports another corresponding high-frequency switching signal, through inverter 6
control motors 7, so that
motor 7 stator torques become big.
In magnetic linkage stagnates ring control unit 4-2, as described stator magnetic linkage ψ
sWith respect to magnetic linkage reference value ψ
* sReach the ring upper limit that stagnates
The time, the stagnant ring of magnetic linkage control unit 4-2 exports corresponding magnetic linkage conditioning signal τ to switch
list 5, and
switch list 5 draws the correspondent voltage space vector and exports corresponding high-frequency switching signal, through inverter 6
control motors 7, so that
motor 7 magnetic linkages diminish; Otherwise, as described stator magnetic linkage ψ
sWith respect to magnetic linkage reference value ψ
* sReach the ring lower limit that stagnates
The time, the stagnant ring of magnetic linkage control unit 4-2 exports another corresponding magnetic linkage conditioning signal τ to switch
list 5,
switch list 5 draws another correspondent voltage space vector and exports another corresponding high-frequency switching signal, through inverter 6
control motors 7, so that
motor 7 stator magnetic linkages become big.
Above-mentioned Direct Torque brushless DC servo control system also comprises the rotational speed omega that is used to detect motor 7
fSpeed measuring coder 9; Described torque reference value T
* eBy default speed reference ω
*With described rotational speed omega
fDifference behind pi regulator, obtain.
Described coordinate transformation unit 1, magnetic linkage computing unit 2, torque calculation unit 3, magnetic linkage and torque stagnant ring control unit 4 and switch list 5 are arranged in the digital signal processor 8; Digital signal processor 8 has the PWM control output end, and the high-frequency switching signal that is used for switch list 5 outputs is pwm signal is delivered to inverter unit through power driving circuit 10 a signal input end; Digital signal processor 8 has ADC analog-to-digital conversion input, is used for detecting through signal processing circuit 11 current signal, the voltage signal of motor 7; Digital signal processor 8 has the CAP rotating speed and catches input, is used for detecting through speed measuring coder 9 rotational speed omega of motor 7
f
The method of work of above-mentioned Direct Torque brushless DC servo control system comprises the steps:
A, coordinate transformation unit detect current signal, the voltage signal of motor, after with this current signal and voltage signal from the abc coordinate system transformation to the α β stator system of axis, with output stator current signal i
αAnd i
β, stator voltage signal u
αAnd u
βTo magnetic linkage computing unit;
B, magnetic linkage computing unit are according to described stator current signal i
αAnd i
βCalculate the stator magnetic linkage Ψ of motor
sSimultaneously according to described current signal i
αAnd i
βWith stator voltage signal u
αAnd u
βCalculate stator magnetic linkage Ψ
sAmplitude | Ψ
s| and stator magnetic linkage Ψ
sComponent Ψ
αAnd Ψ
βThen, according to described i
αAnd i
β, described Ψ
αAnd Ψ
βCalculate stator magnetic linkage Ψ
sAnd the angle theta between a axle of abc coordinate system;
C, torque calculation unit are according to described stator current signal i
αAnd i
βWith described Ψ from magnetic linkage computing unit
αAnd Ψ
βCalculate the stator torque T of motor
e
D, magnetic linkage and torque stagnate the ring control unit will be from the stator magnetic linkage Ψ of magnetic linkage computing unit
sWith stator torque T from the torque calculation unit
eRespectively with reference value
And T
* eCompare, and export corresponding magnetic linkage conditioning signal τ and torque adjustment signal Phi according to comparative result; Magnetic linkage conditioning signal τ and torque adjustment signal Phi are high-frequency square-wave signal;
E, switch list are according to the magnetic linkage conditioning signal τ of the ring control unit that stagnates from magnetic linkage and torque, torque adjustment signal Phi with from the stator magnetic linkage Ψ of magnetic linkage computing unit
sAnd angle theta, draw a correspondent voltage space vector S
Abc, and export a corresponding high-frequency switching signal;
F, inverter unit are according to the described high-frequency switching signal control inverter from switch list, so that the torque of inverter control motor keeps stable.
The execution frequency of described steps A-E is 4-8kHz.
The stagnant ring of described magnetic linkage and torque control unit 4 comprises: torque stagnates and encircles control unit 4-1 and the stagnant control unit 4-2 that encircles of magnetic linkage.
In torque stagnates ring control unit 4-1, as described stator torque T
eWith respect to torque reference value T
* eReach the ring upper limit that stagnates
The time, the stagnant ring of torque control unit 4-1 exports corresponding torque adjustment signal Phi to switch
list 5, and
switch list 5 draws the correspondent voltage space vector and exports corresponding high-frequency switching signal, through inverter 6
control motors 7, so that
motor 7 stator torques diminish; Otherwise, as described stator torque T
eWith respect to torque reference value T
* eReach the ring lower limit that stagnates
The time, the stagnant ring of torque control unit 4-1 exports another corresponding torque adjustment signal Phi to switch
list 5,
switch list 5 draws another correspondent voltage space vector and exports another corresponding high-frequency switching signal, through inverter 6
control motors 7, so that
motor 7 stator torques become big.
In magnetic linkage stagnates ring control unit 4-2, as described stator magnetic linkage ψ
sWith respect to magnetic linkage reference value ψ
* sReach the ring upper limit that stagnates
The time, the stagnant ring of magnetic linkage control unit 4-2 exports corresponding magnetic linkage conditioning signal τ to switch
list 5, and
switch list 5 draws the correspondent voltage space vector and exports corresponding high-frequency switching signal, through inverter 6
control motors 7, so that
motor 7 magnetic linkages diminish; Otherwise, as described stator magnetic linkage ψ
sWith respect to magnetic linkage reference value ψ
* sReach the ring lower limit that stagnates
The time, the stagnant ring of magnetic linkage control unit 4-2 exports another corresponding magnetic linkage conditioning signal τ to switch
list 5,
switch list 5 draws another correspondent voltage space vector and exports another corresponding high-frequency switching signal, through inverter 6
control motors 7, so that
motor 7 stator magnetic linkages become big.
The Direct Torque brushless DC servo control system also comprises speed measuring coder 9; Speed measuring coder 9 detects the rotational speed omega of motor 7
fDescribed torque reference value T
* eBy default speed reference ω
*With described rotational speed omega
fDifference behind pi regulator, obtain.
Deliver to the signal input end of inverter unit through the PWM control output end from the high-frequency switching signal of switch list 5 output, so that the torque of inverter 6 control motors 7 keeps stable.
The present invention has positive effect: among (1) the present invention program, magnetic linkage and torque stagnate the ring control unit will be from the stator magnetic linkage Ψ of magnetic linkage computing unit
sWith stator torque T from the torque calculation unit
eRespectively with reference value
And T
* eCompare, and be magnetic linkage conditioning signal τ and the torque adjustment signal Phi of 4-8kHz according to comparative result output correspondent frequency; With respect to prior art, improved the frequency of the control signal of input switch table greatly, thereby improved the ability of the torque of inverter control motor.The direct torque control that adopts does not contain current regulator, do not consider the waveform of stator current, but compare according to torque that records and torque reference, and directly control the output torque of motor according to this comparative result, thereby it is effective to the control of torque, response is fast, thereby has solved the problem of the torque pulsation of brshless DC motor.(2) the present invention cuts down torque pulsation by improving inverter switching frequency.In digitized direct Torque Control, on control mode, the control of using the fixing sampling period to replace torque stagnates and encircles, it was only once adjusted the output voltage of inverter according to result of calculation in each sampling period, this voltage will impose on motor always then, up to the end of next one sampling, computing cycle.So, for the regulating frequency of raising system, must shorten the sampling period, to come conversion to be applied to voltage on the motor according to the torque adjustment needs as quickly as possible to torque.So just can reach with the corresponding to control effect of control method that reduces stagnant ring range of tolerable variance in the ring control that stagnates.(3) prior art the torque pulsation amplitude of motor commutation period can only be controlled at nominal torque 50% within, and this also depends on the distortion situation of winding back emf and the parameter of motor, such as inductance, resistance etc.And the present invention is when adopting the method for direct torque control to control, and the torque ripple of motor can be controlled at below 5%, and can utilize the machinery inertial of motor that it is filtered easily.
Embodiment
(embodiment 1)
See Fig. 1 and Fig. 5, the Direct Torque brushless DC servo control system of present embodiment comprises: inverter 6, data signal processor DSP 8, speed measuring coder 9, power driving circuit 10, signal processing circuit 11 and current rectifying and wave filtering circuit 12.
The 220V alternating current links to each other with the power end of inverter 6 through the output of current rectifying and wave filtering circuit 12; The control output end of inverter 6 connects the power end of motor 7.Digital signal processor 8 has the PWM control output end, and series connection power driving circuit 10 backs link to each other with the signal input end of inverter unit; Digital signal processor 8 has ADC analog-to-digital conversion input; Signal processing circuit 11 comprises current sensor 13, and the ADC analog-to-digital conversion input of digital signal processor 8 detects current signal, the voltage signal of motor 7 through signal processing circuit 11; Digital signal processor 8 has the CAP rotating speed and catches input, is used for detecting through speed measuring coder 9 rotational speed omega of motor 7
f
Still see Fig. 1, data signal processor DSP 8 comprises: coordinate transformation unit 1, magnetic linkage computing unit 2, torque calculation unit 3, magnetic linkage and torque stagnate and encircle control unit 4 and switch list 5.
Coordinate transformation unit 1 be used for detect motor 7 current signal, voltage signal respectively from the abc coordinate system transformation to α β stator system of axis (see figure 2), with output stator current signal and stator voltage signal.
Magnetic linkage computing unit 2 is used for according to the stator magnetic linkage Ψ that calculates motor 7 from the stator current signal of coordinate transformation unit 1
sGo out stator magnetic linkage Ψ according to stator current signal and stator voltage calculated signals simultaneously from coordinate transformation unit 1
sAmplitude | Ψ
s| and stator magnetic linkage Ψ
sComponent Ψ
αAnd Ψ
βThen, according to from the stator current signal of coordinate transformation unit 1, described Ψ
αAnd Ψ
βCalculate stator magnetic linkage Ψ
sAnd the angle theta between a axle of abc coordinate system.
Torque calculation unit 3 is used for according to the described Ψ from magnetic linkage computing unit 2
αAnd Ψ
βCalculate the stator torque T of motor 7
e
See Fig. 3-4, the stagnant ring of magnetic linkage and torque control unit 4 is used for the stator magnetic linkage Ψ from magnetic linkage computing unit 2
sWith stator torque T from torque calculation unit 3
eRespectively with reference value
And T
* eCompare, and export the torque adjustment signal Phi of magnetic linkage conditioning signal τ and the 6kHz of corresponding 6kHz according to comparative result.
Switch list 5 is used for according to the magnetic linkage conditioning signal τ of the ring control unit 4 that stagnates from magnetic linkage and torque, torque adjustment signal Phi with from the stator magnetic linkage Ψ of magnetic linkage computing unit 2
sAnd angle theta, draw a correspondent voltage space vector S
Abc, and by the PWM control output end of digital signal processor 8 output one corresponding high-frequency switching signal.
Inverter unit is used for according to the described high-frequency switching signal control inverter 6 from switch list 5, so that the torque of inverter 6 control motors 7 keeps stable.
See Fig. 7, the method for work of above-mentioned Direct Torque brushless DC servo control system comprises:
A, coordinate transformation unit 1 detect the current signal i of motor 7
α, i
bAnd i
c, voltage signal u
α, u
bAnd u
c, after with this current signal i
a, i
bAnd i
cWith voltage signal u
α, u
bAnd u
cFrom the abc coordinate system transformation to the α β stator system of axis, with output stator current signal i
αAnd i
β, stator voltage signal u
αAnd u
βTo magnetic linkage computing unit 2;
Wherein, u
α, u
bAnd u
cBe according to the U that records
DcIn conjunction with switch list 5, draw by following form:
Switch a |
Switch b |
Switch c |
u
α |
u
b |
u
c |
0 |
0 |
0 |
0 |
0 |
0 |
1 |
0 |
0 |
2U
dc/3
|
-U
dc/3
|
-U
dc/3
|
1 |
1 |
0 |
U
dc/3
|
U
dc/3
|
-2U
dc/3
|
0 |
1 |
0 |
-U
dc/3
|
2U
dc/3
|
-U
dc/3
|
0 |
1 |
1 |
-2U
dc/3
|
U
dc/3
|
Udc/3 |
0 |
0 |
1 |
-U
dc/3
|
-U
dc/3
|
2U
dc/3
|
1 |
0 |
1 |
U
dc/3
|
-2U
dc/3
|
U
dc/3
|
1 |
1 |
1 |
0 |
0 |
0 |
B, magnetic linkage computing unit 2 are according to described current signal i
αAnd i
βCalculate the stator magnetic linkage Ψ of motor 7
sSimultaneously according to described current signal i
αAnd i
βWith stator voltage signal u
αAnd u
βCalculate stator magnetic linkage Ψ
sAmplitude | Ψ
s| and stator magnetic linkage Ψ
sComponent Ψ
αAnd Ψ
βThen, according to described i
αAnd i
β, described Ψ
αAnd Ψ
βCalculate stator magnetic linkage Ψ
sAnd the angle theta between a axle of abc coordinate system;
C, torque calculation unit 3 are according to described stator current signal i
αAnd i
βWith described Ψ from magnetic linkage computing unit 2
αAnd Ψ
βCalculate the stator torque T of motor 7
e
D, magnetic linkage and torque stagnate
ring control unit 4 will be from the stator magnetic linkage Ψ of magnetic
linkage computing unit 2
sWith stator torque T from
torque calculation unit 3
eRespectively with reference value
And T
* eCompare, and export corresponding magnetic linkage conditioning signal τ and torque adjustment signal Phi according to comparative result; The torque adjustment signal Phi is that (among other embodiment, can be 4,5,8 or 10kHz, this frequency be high more, and the torque pulsation amplitude is just more little for the high-frequency square-wave signal that is 6kHz.)。
E, switch list 5 is according to the magnetic linkage conditioning signal τ of the ring control unit 4 that stagnates from magnetic linkage and torque, torque adjustment signal Phi with from the stator magnetic linkage Ψ of magnetic linkage computing unit 2
sAnd angle theta, draw a correspondent voltage space vector S
Abc, and by the PWM control output end of digital signal processor 8 output one corresponding high-frequency switching signal.
F, inverter unit are according to the described high-frequency switching signal control inverter 6 from switch list 5, so that the torque of inverter 6 control motors 7 keeps stable.
See Fig. 4, Fig. 6 and Fig. 8, in torque stagnates ring control unit 4-1, when described stator torque Te with respect to torque reference value T
* eReach the ring upper limit that stagnates
The time, the stagnant ring of torque control unit 4-1 exports corresponding magnetic linkage conditioning signal to switch
list 5, and
switch list 5 draws the correspondent voltage space vector and exports corresponding high-frequency switching signal, through
inverter 6
control motors 7, so that
motor 7 stator torques diminish; Otherwise, as described stator torque T
eWith respect to torque reference value T
* eReach the ring lower limit that stagnates
The time, the stagnant ring of torque control unit 4-1 exports another corresponding magnetic linkage conditioning signal to switch
list 5,
switch list 5 draws another correspondent voltage space vector and exports another corresponding high-frequency switching signal, through
inverter 6
control motors 7, so that
motor 7 stator torques become big.
Speed measuring coder 9 detects the rotational speed omega of motor 7
fDescribed torque reference value T
* eBy default speed reference ω
*With described rotational speed omega
fDifference behind pi regulator (being proportional and integral controller), obtain.
Deliver to the signal input end of inverter unit from the high-frequency switching signal (frequency is fixed, and is generally 16khz) of switch list 5 output by the PWM control output end of DSP8, so that the corresponding space vector of voltage S of inverter 6 outputs
ab
c(S
AbcHas initial value, u
a, u
bAnd u
cEffect be exactly space voltage space vector S
Abc), and the torque of control motor 7 keeps stable.
See Fig. 6 (c) Fig. 8 (c), adopt the direct torque control after the high frequencyization, abandoned hysteresis comparator, reduced the system phase hysteresis, for system deviation high frequency output controlled quentity controlled variable, refinement the adjusting time, and forward negative regulation time t3, t4 are uniform.The size of control tolerance depends on frequency controller, therefore, as long as by the control switch frequency, the size of tolerance that just can controlling torque, thereby size that can the controlling torque pulsation.