CN2749178Y - A brushless DC motor speed regulator based on direct torque control (DTC) of fundamental wave method - Google Patents

Abstract

The utility model relates to a fundamental wave method direct torque control system of a brushless direct current motor relating to the technology of non-position sensors. The fundamental wave method direct torque control system comprises a brushless direct current motor (1), a power converter (2), a converter control signal (3), a control system (4) based on a digital control signal processor, a module converter A / D (5), and a current and voltage sensor (6). A common position sensor and a common current closed loop circuit are cancelled. The device bases on a current and voltage signal detected, and the magnetic linkage and the torque of the brushless direct current motor are calculated by a digital signal processor in the device. The magnetic linkage and the torque of the brushless direct current motor are compared with the given fundamental wave magnetic linkage and the given torque, the optimal space voltage vector is directly selected from a comparative result and the space position of the magnetic linkage to be used for the brushless direct current motor by the power converter to obtain the purpose of speed regulation. Due to the fact that the position sensor is cancelled, the fundamental wave method direct torque control system has simple structure, firmness, reliability, and low manufacture cost. The speed regulation ratio of the fundamental wave method direct torque control system can obtain 1: 150, and can be widely applicable to a military industry requirement and a civil requirement.

Description

A kind of brshless DC motor speed regulating device based on first-harmonic method direct torque control

Technical field

What the utility model was related is a kind of brshless DC motor speed regulating device that adopt the position-sensor-free direct torque control,

Background technology:

Reaching energy-conservation effect with ac speed control technology is news from nowhere, and magneto has been owing to used rare earth permanent-magnetic material, and energy-saving effect is more remarkable.China is rare earth metal big country, for many years in the application of promoting rare-earth permanent-magnet electric machine; In addition, ac speed control technology can also improve various dynamic, static propertiess, and crudy or system operation integrated quality is improved.Therefore, the speed adjusting technique of magneto is that an application is very extensive, to the influential technology of national economy large tracts of land.

Magneto comprises two types, and a class is a brshless DC motor, and a class is the AC sine magneto.In fact this two class all is an alternating current machine, and the characteristic that is the first kind is just like direct current machine, but it is brushless, so make it be brshless DC motor, it promptly is the permanent magnetism square-wave motor.1996, one of the applicant proposed the direct torque control scheme of AC sine magneto first University of New South Wales's duration of work and Australia side scholar, and disclosed its achievement in 1997 on the American I EEE PE magazine, did not apply for a patent.After this, this Study on Technology is risen simultaneously with domestic abroad, has delivered many papers, and remarkable progress is arranged.But also do not have the people that direct torque control is applied directly on the brshless DC motor, and that brshless DC motor uses is very extensive on household electrical appliances, general industry articles for use, as refrigerator, washing machine, air-conditioning all at a large amount of brshless DC motors that use.The weak magnetic of brshless DC motor is difficulty, and speed adjustable range is restricted, and the new control method of expectation invention can overcome these weakness.

Summary of the invention

The purpose of this utility model is two kinds of advanced technologies are applied on the brshless DC motor, in the hope of speed adjustable range and the raising dynamic property that enlarges it.A kind of advanced technology is the position-sensor-free technology, and it is not a position-sensor-free technology of utilizing counter electromotive force of motor, but detects transient current, goes out transient speed through the rotating speed calculated with mathematical model of setting up, and this technology can enlarge the range of operation of low speed.Another kind of advanced technology is the direct torque control technology, and it can improve the dynamic property of system, and can improve the situation of weak magnetic.Enlarge the high-speed cruising scope of motor.These two technology combine, and can make the brshless DC motor speed adjustable range of position-sensor-free reach 1: 150.

For realizing above-mentioned technical indicator, technical solution of the present utility model is that hardware system detects the loop by major loop, control loop three parts composition.Major loop is received power supply grid by brshless DC motor, power inverter series connection by power inverter; Detecting the loop is made up of current sensor and voltage sensor; Control loop is connected in control unit based on digital signal processor (DSP) by analog to digital converter, produces the power inverter control signal, is connected in the convertor controls signal processing unit again and forms.In detecting the loop, deleted position transducer (perhaps motor three-phase alternating current back-emf zero passage position detector) commonly used; In control loop, deleted the current closed-loop circuit.

The control method of the brshless DC motor first-harmonic method direct Torque Control of the utility model position-sensor-free is: in each control cycle, according to detected electric current, voltage, calculate instantaneous magnetic linkage and instantaneous torque, and the rotating speed Mathematical Modeling according to setting up calculates transient speed (this is the position-sensor-free technology); By given rotating speed and the transient speed that calculates,, obtain given torque via speed regulator.Instantaneous magnetic linkage and given first-harmonic magnetic linkage are compared, instantaneous torque and given torque ratio are, by the result relatively and the locus at magnetic linkage place, directly select for use optimum converters space voltage vector to act on brshless DC motor, make it reach the purpose of speed governing.And the given magnetic linkage of first-harmonic is to be provided by design of electrical motor.

This control method is calculated simply, and it is little influenced by the parameter of electric machine, and the dynamic response of system is good, speed-regulating range width.Owing to removed position transducer and current closed-loop, whole system is simple in structure, has improved reliability simultaneously.

Description of drawings:

Fig. 1 is the composition frame chart of the first-harmonic method direct moment controlling system without position sensor of brshless DC motor

Fig. 2 is the magnetic linkage track schematic diagram

Fig. 3 is the first-harmonic method direct moment controlling system without position sensor block diagram of brshless DC motor

Numbering title among Fig. 1 in each block diagram is respectively; 1, brshless DC motor, 2, power inverter, 3, the convertor controls signal, 4, based on the control system of digital controlled signal processor, 5, modulus converter A/D, 6, current sensor and voltage sensor.

Designation among Fig. 2: U ₁～U ₆-space voltage vector, θ ₁～θ ₆Six zones that space ,-stator magnetic linkage place is divided equally.

Designation among Fig. 3: Ψ ^*The amplitude set-point of-stator first-harmonic magnetic linkage, T ^*-voltage regulator output torque set-point, Ψ-stator magnetic linkage, T-torque instantaneous value, Φ-magnetic linkage ring hysteresis comparator output valve, τ-torque ring hysteresis comparator output valve, six regional output valves that θ-space, stator field place is divided equally, S ₁, S ₂, S ₃-three on off states, U _α, I _α-permanent-magnet brushless DC electric machine line voltage and line current be the projection on the α axle in the alpha-beta coordinate system, U _β, I _β-permanent-magnet brushless DC electric machine line voltage and line current be the projection on the β axle in the alpha-beta coordinate system, Ψ _α, Ψ _β-permanent-magnet brushless DC electric machine stator magnetic linkage Ψ is α axle and the axial projection of β in the alpha-beta coordinate system, U _Dc, I _DcThe direct voltage and the electric current of-output.Title in each block diagram among the figure, the basis signal direction is successively: voltage, current detecting, coordinate transform, magnetic linkage is estimated, flux linkage set, magnetic linkage ring hysteresis comparator, torque is estimated, velocity estimation, velocity setting, rotational speed regulation, torque ring hysteresis comparator, the magnetic linkage sector is determined, switch list also has permanent-magnet brushless DC electric machine (BLDC MOTOR) and IGBT three-phase bridge in the main circuit.

Specific implementation method:

Narrate specific implementation method of the present utility model and operation principle and the course of work with reference to the accompanying drawings.As shown in Figure 1, brushless DC motor without position sensor direct Torque Control of the present utility model comprises by brshless DC motor 1, power inverter 2 the two major loop that are formed by connecting; The detection loop of being made up of current sensor, voltage sensor 6 is connected in the control loop that convertor controls signal 3 is formed after being connected in control system 4 based on digital signal processor (DSP) by modulus converter A/D 5 again.Power tube in the power inverter can adopt IGBT power tube or power field effect pipe; The current/voltage transducer can be Hall element, also can be sampling resistor.Transducer changes electric current on the major loop and voltage the analog voltage signal of light current into, enters modulus converter A/D, is digital signal by it with analog signal conversion, and it is used to give the DSP control system again.According to signal of obtaining and Strategy of Direct Torque Control of the present utility model, calculate transient speed, determine sector, the residing space of magnetic linkage, and calculate the control signal of sending, via convertor controls signal 3, send 6 digit pulse signals and remove to control power inverter in the major loop.

The utility model has been deleted position transducer commonly used in detecting the loop; In control loop, deleted current closed-loop circuit (alternating current herein Signal is not made current closed-loop usefulness, only as calculating transient speed, determines the magnetic linkage position and calculates the needed signal of transient electromagnetic torque).

The utility model is based on the brushless DC motor without position sensor direct Torque Control, adopt the method for directly selecting for use optimum space voltage vector to act on brshless DC motor directly to control electromagnetic torque by converters, make motor change rotating speed fast, reach the purpose of quick speed governing.

The basic principle of this control method is described below:

Brshless DC motor governing system in the past all is to measure rotor-position by position transducer, thereby determines the triggering signal of master power switch, realizes and the direct current machine similar electronic commutation that commutates.In case additional position transducer lost efficacy, brshless DC motor can not be worked.The numerous and confused requirement of user is in recent years got rid of the high position transducer of failure rate, system is simplified and compactness more, and the position-sensor-free technology is developed rapidly.General brshless DC motor governing system all adopts the crossover point signal of the back-emf that detects motor no power phase to determine rotor-position and calculates rotating speed, but the big or small summation motor speed of counter electromotive force of motor is directly proportional, and when rotating speed hanged down, back-emf was very weak, poor signal to noise can't detect.Therefore this position-sensor-free technology can not be used for the low occasion of speed, and limitation is very big.The utility model then adopts the method for setting up the rotating speed Mathematical Modeling, calculate rotating speed with the transient current, the space voltage vector of selecting for use that detect and the magnetic linkage that calculates, it doesn't matter because electric current, space voltage vector, magnetic linkage are all with the height of rotating speed, therefore, as long as the Mathematical Modeling structure is correct, it can calculate the rotating speed under the very slow-speed of revolution in theory, because the applied occasion of brshless DC motor mostly is general occasion, calculate simply the following Mathematical Modeling that this place selects for use for making:

In the stator rest frame, have: ${\mathrm{\ω}}_s=\frac{{\mathrm{d\θ}}_s}{\mathrm{dt}}=\frac{{\stackrel{\·}{\mathrm{\ψ}}}_{\mathrm{\β}}{\mathrm{\ψ}}_{\mathrm{\α}}-{\stackrel{\·}{\mathrm{\ψ}}}_{\mathrm{\α}}{\mathrm{\ψ}}_{\mathrm{\β}}}{{\mathrm{\ψ}}_{\mathrm{\α}}^2+{\mathrm{\ψ}}_{\mathrm{\β}}^2}$

Because relational expression is arranged in the motor: $\begin{array}{c}{\stackrel{\·}{\mathrm{\ψ}}}_{\mathrm{\α}}=U_{\mathrm{\α}}-i_{\mathrm{\α}}{R}_s\\ {\stackrel{\·}{\mathrm{\ψ}}}_{\mathrm{\β}}=U_{\mathrm{\β}}-i_{\mathrm{\β}}{R}_s\end{array}$

So: ${\mathrm{\ω}}_s=\frac{(U_{\mathrm{\β}}-i_{\mathrm{\β}}{R}_s){\mathrm{\ψ}}_{\mathrm{\α}}-(U_{\mathrm{\α}}-i_{\mathrm{\α}}{R}_s){\mathrm{\ψ}}_{\mathrm{\β}}}{{\mathrm{\ψ}}_{\mathrm{\β}}^2+{\mathrm{\ψ}}_{\mathrm{\β}}^2}$

In the formula: ω _sBe the synchronous speed in the motor, U _α, U _βBe the projection of space voltage vector on α, β axle of selecting for use; i _α, i _βBe the projection of current phasor on α, β axle, ψ _α, ψ _βBe the projection of stator magnetic linkage on α, β axle, R _sResistance for motor stator.

Because brshless DC motor belongs to permagnetic synchronous motor in essence, the feature of synchronous machine is rotor speed ω when stable state _rEqual synchronous speed ω _s, so ω _r=ω _s

The transient speed ω that calculates _rWith given rotating speed ω _r ^*Send into speed regulator, provide given torque according to its difference.Actual torque can be calculated by magnetic linkage and electric current.If actual torque just increases the angle of stator magnetic linkage and rotor flux less than given torque.If actual torque greater than given torque, just reduces this angle.If actual torque is substantially equal to given torque, then should keep this angle constant.And the direction of control cycle internal rotor magnetic linkage changes not quite, and this angle is by the direction decision of stator magnetic linkage.Therefore, in fact as long as just can realize the change of this angle by the direction of control stator magnetic linkage.And stator magnetic linkage is subjected to the influence of space voltage vector, and promptly the arrow tongue mark of stator magnetic linkage vector will move along the direction of selected spatial movement voltage vector, selects different spatial movement voltage vectors that the amplitude of stator magnetic linkage and direction will be changed.If select zero vector, then the stator magnetic linkage vector is constant, promptly keeps the angle of stator magnetic linkage vector.Therefore, select appropriate space voltage vector to move by required movement locus according to certain rule with regard to may command stator magnetic linkage vector.For the AC sine magneto, required stator magnetic linkage movement locus is a circle, and still, for square-wave motor (being brshless DC motor), then this magnetic linkage is not a circle, and its first-harmonic is only circle.Characteristics of the present utility model are controlled this first-harmonic with regard to being as required movement locus.At this moment, controlling schemes also must satisfy the condition of first-harmonic magnetic linkage circle constant amplitude.So the arrow point of stator magnetic linkage vector should be controlled so as to by circuit orbit and move.Shown in Figure 2 is exactly stator magnetic linkage track schematic diagram.Be divided into 6 different sectors among the figure, exist in six different sectors of circumference and to make the optimal spatial voltage vector of magnetic linkage movement locus separately accordingly along circular motion, because have only six motion vectors optional, cause the movement locus of stator magnetic linkage vector to be actually as shown in Figure 2 broken line.But because actual control cycle is extremely short, it is circular that movement locus is approximately, and guaranteed the constant condition of stator magnetic linkage amplitude.The angle that will change electromagnetic torque rapidly and be by quick change stator magnetic linkage reaches.The rotary speed that changes stator magnetic linkage is by selecting appropriate motion vector and inserting zero vector and realize.In view of the above, by in each extremely short control cycle, from eight space voltage vectors, selecting the optimal spatial voltage vector, the deviation that one side is corrected stator magnetic linkage movement locus and given trace; Change the angle of stator magnetic linkage and rotor flux on the other hand as soon as possible.According to the condition that different sectors and magnetic linkage, torque change, can sum up the switch list that provides an optimal spatial voltage vector as shown in the table.

φ	1	θ 1	θ 2	θ 3	θ 4	θ 5	θ 6
								1	1	U 2(110)	U 3(010)	U 4(011)	U 5(001)	U 6(101)	U 1(100)
0	U 7(111)	U 0(000)	U 7(111)	U 0(000)	U 7(111)	U 0(000)
							-1		U 6(101)	U 1(100)	U 3(110)	U 3(010)	U 4(011)	U 5(001)
-1	1	U 3(010)	U 4(011)	U 5(001)	U 6(101)	U 1(100)									U 2(110)
							0	U 0(000)	U 7(111)	U 0(000)	U 7(111)	U 0(000)	U 7(111)
	-1	U 1(100)	U 2(110)	U 3(010)	U 4(011)	U 5(001)								U 6(101)

The block diagram of the first-harmonic method direct torque control of realization brushless direct current motor sensorless as shown in Figure 3.The controlling unit of native system is divided into torque control ring and magnetic linkage control ring, all adopts table tennis (Band-Band) control.Adopt the loop circle flux track, the amplitude set-point of stator magnetic linkage is provided by the first-harmonic magnetic linkage of motor, a parameter of electric machine when it is design of electrical motor.Speed regulator provides the set-point T of brshless DC motor torque control according to rotating speed that detects and given rotating speed ^*The instantaneous value T of stator magnetic linkage ψ and torque, the observation of useable electric moter model calculates, and chooses optimal spatial voltage vector by the relatively back position that combines the magnetic linkage place of hysteresis comparator by last table with its set-point respectively again.θ and τ are respectively the output of hysteresis comparator in magnetic linkage ring and the torque ring.φ=1 requires to adopt to make | ψ _s| the vector that increases or keep, φ=-1, then adopt to make | ψ _s| the vector that reduces or keep.τ=1 requires torque to increase, and adopts motion vector that the angle of the relative rotor flux of stator magnetic linkage is increased; Zero vector is then adopted in τ=0, and torque is kept, and τ=-1 requires torque to reduce, and adopts motion vector that the angle of the relative rotor flux of stator magnetic linkage is reduced.At θ ₁-θ ₆Each zone in adopt the voltage vector of respective direction can control magnetic linkage and electromagnetic torque simultaneously, reach the purpose of speed governing.

Claims (1)

1. A kind of brshless DC motor speed regulating device based on first-harmonic method direct torque control is characterized in that, comprise brshless DC motor (1), power inverter (2), and brshless DC motor connects power inverter.The detection loop of forming by AC current sensor and voltage sensor (6), the signal that detects is sent into control system (4) based on digital controlled signal processor (DSP) through modulus converter A/D (5), carry out the calculating of rotating speed, magnetic linkage, torque by DSP, and make control decision, give power inverter (2) control decision via convertor controls signal (3), finally press control law control brshless DC motor (1) by power inverter (2).This device is characterised in that the first-harmonic magnetic linkage of asking for sinusoidal shape from controlled brshless DC motor magnetic linkage is as given magnetic linkage, magneto direct torque control method by sinusoidal magnetic linkage, without position detector, also without the back-emf of brshless DC motor, and, go out transient speed by the rotating speed calculated with mathematical model with the transient current that detects.Then, in each control cycle, directly select the space voltage vector of optimum converters for use, act on brshless DC motor, realize the purpose of speed governing by power inverter according to rotating speed, magnetic linkage, torque.

Images