CN101425776A - Fault tolerant control method for double salient pole permanent magnet motor - Google Patents

Abstract

The invention relates to a fault-tolerance controlling method used for a double-convex-pole permanent magnetic motor. A double-convex-pole permanent magnetic motor of a straight flute rotor has trapezoid wave back-emf, and a three-phase square wave is used for control in the normal running of a system. The advantages of simple method, high outputted power, and the like are obtained. When the system has a phase-defect fault, an equivalent sine wave driving controlling method is used for calculating the equivalent three-phase sine wave current of a torque generated in normal running, and then amplitude values and phase positions of two non-fault phase-fault-tolerance sine wave currents in a fault-tolerance state are calculated, thus, the output torque of a driving system of the double-convex-pole permanent magnetic motor in phase-defect running is equivalent to that of the normal running state, and the running with a fault of the double-convex-pole permanent magnetic motor is realized.

Description

A kind of fault tolerant control method of doubly salient permanent magnet motor

Technical field

The present invention is a kind of fault tolerant control method that is used for three-phase 12/8 utmost point doubly salient permanent magnet motor, is applicable to that Aero-Space, steel rolling, mine etc. have the motor driven systems application scenario of high request to continuous operation.

Background technology

The application of motor driven systems in military affairs, industrial and agricultural production more and more widely, the field that particularly system reliability is had high request at some, as Aero-Space, military equipment etc., reliability serviceability to motor driven systems has very high requirement, and the fault tolerant control method under its malfunction is its key technology.

At present, domestic and international research to fault tolerant type motor and control method thereof focuses mostly in two class motors: switched reluctance machines and traditional rotor permanent magnet-type motor.Though the former is simple in structure, the reliability height has certain inferior position aspect power density; And the latter's permanent magnet places rotor, and the heat radiation of its mechanical structure reliability and permanent magnet all is a stubborn problem comparatively.

Doubly salient permanent magnet motor is a kind of novel stator permanent-magnet motor, and its permanent magnet places stator, have simple in structure, be easy to advantages such as heat radiation, satisfy the application requirements in high reliability field.Its stator and rotor are the biconvex electrode structure, do not have winding, no permanent magnet on the rotor, and stator adopts centralized winding, and the coil on the relative tooth in space links to each other in twos, and two groups of coil polyphones form a phase armature winding.Therefore, such motor has that structure is comparatively simple, power density is than advantages such as height.Existing achievement in research concentrates on design, analysis and the control of this kind motor, does not all relate to intelligent fault-tolerance Driving technique proposed by the invention.The present invention is directed to self electromagnetic property of doubly salient permanent magnet motor, a kind of fault-tolerant drive controlling method is proposed: when three-phase doubly salient permanent magnet motor drive system generation open-phase fault, to the electric current of the two-phase (non-fault phase) of remainder at aspects such as phase place and amplitudes to adjusting, reach the electromagnetism output torque and the akin purpose of normal operating condition that keep doubly salient permanent magnet motor, thereby improve the ability that operates with failure of doubly salient permanent magnet motor drive system, develop the fault-tolerant drive system of stator permanent-magnet motor, to satisfy the requirement of high reliability application.

Summary of the invention

Technical problem: the fault tolerant control method that the objective of the invention is to propose a kind of novel stator permanent-magnet motor based on doubly salient permanent magnet motor.Making provides current drives mutually by the non-fault of remaining two-phase when three-phase doubly salient permanent magnet motor generation open-phase fault, the electromagnetic torque that motor produced remains unchanged substantially, the torque characteristics when reaching normal operation the, the raising system ability that operates with failure.

Technical scheme: doubly salient permanent magnet motor has the trapezoidal wave back electromotive force, should adopt three-phase square wave control under the normal operating condition; When motor generation open-phase fault, for improving the performance under its malfunction, the present invention uses the control of two-phase fault tolerant type sine-wave current, reaches to keep the constant purpose of motor output electromagnetic torque.The main thought of this control method is: for three phase electric machine, its rotation main field is formed by the magnetic field addition that three-phase current produces, if wherein a certain breaking down mutually can't be worked, then doubly salient permanent magnet motor still can continue operation under the synthetic rotating magnetic field of equivalence that two-phase produces in addition.Specific as follows:

Increased the fault detect link in control system, when not detecting open-phase fault, control system promptly adopts 120 ° of square wave current control of three-phase doubly salient permanent magnet motor according to the normal operation pattern.When system detected open-phase fault, electric machine control system was enabled fault-tolerant control model, was divided into following three steps:

A. according to the doubly salient permanent magnet motor torque equation of three-phase square wave control under the normal operating condition, calculate the current amplitude of the three-phase sine-wave control that produces equivalent torque, its value should be 1.1 times of square wave current amplitude;

B. according to and three-phase sine-wave produce the constant principle in magnetic field, calculate the amplitude and the phase place of the fault-tolerant sine-wave current of two-phase, when its amplitude should be normal operation 1.73 times of the three-phase sine-wave current amplitude, when promptly normally moving 1.9 of the three-phase square wave electric current times; The last phase of fault phase, phase place becomes leading 150 ° for 120 ° by original leading fault phase, a back phase of fault phase, phase place becomes 150 ° of hysteresis for 120 ° by original hysteresis fault phase;

C. according to the amplitude and the phase place of the mutually fault-tolerant sine-wave current of fault-tolerant when control work that calculates, becomes original three-phase square wave and be controlled to be that two-phase is sinusoidal wave to be controlled.

Beneficial effect: characteristics of the present invention are that fault-tolerant control technology is incorporated in three-phase 12/8 utmost point doubly salient permanent magnet motor, build stator permanent-magnet fault-tolerant motor drive system.Overcome many shortcomings of traditional fault-tolerant motor drive system: on the low side as the switched reluctance machines power density; Rotor magneto fault-tolerant motor permanent magnet places rotor, problem such as be not easy to cooling, the mechanical structure reliability is relatively poor, and the doubly salient permanent magnet motor that the present invention introduced has that power density is higher, rotor structure simple, the motor reliability is than advantages such as height.Back-emf based on doubly salient permanent magnet motor is this characteristic of approximate trapezoid ripple, and when motor normally moved, motor adopted square wave control, has simple, the advantage such as bigger of exerting oneself of control; When open-phase fault takes place when, use fault-tolerant Driving technique, adjusting Control current is sinusoidal wave control mode, based on the constant theoretical thought of rotating magnetic field, keep the output torque of motor constant substantially, thereby improve the ability that operates with failure of doubly salient permanent magnet motor, set up the drive system of high power density, high-reliability.

The invention has the advantages that:

1, adopt the doubly salient permanent magnet motor of three-phase straight trough rotor, motor is exerted oneself greatly, is applicable to that high power density requires the field; Rotor structure is simple, and no winding, no permanent magnet, so reliability height are applicable to the high reliability application;

When 2, normally moving, system adopts square wave control, and control method is simple.

3, when open-phase fault takes place, system adopts the two-phase sine wave to carry out fault-tolerant control, and system's characteristic that operates with failure is higher, and its torque output Approximate Equivalent is in normal operating condition.

Description of drawings

Fig. 1 is three-phase 12/8 utmost point doubly salient permanent magnet motor structural representation.

Fig. 2 is a doubly salient permanent magnet motor fault-tolerance approach flow chart.

Three-phase square wave Control current oscillogram when Fig. 3 normally moves for motor.

Equivalence three-phase sine-wave Control current oscillogram when Fig. 4 normally moves for motor.

The fault-tolerant sinusoidal wave Control current of two-phase when Fig. 5 is the motor open-phase fault.

Have among the above figure: the axle 1.5 of doubly salient permanent magnet motor 1, stator 1.1, permanent magnet 1.2, rotor 1.3, armature winding 1.4, motor.

Embodiment

The fault tolerant control method that the present invention proposes when doubly salient permanent magnet motor during at normal operating condition, adopts three-phase square wave control; When open-phase fault took place, controller adopted fault-tolerant control strategy, and motor adopts the sinusoidal wave control of two-phase, and system operates with failure.Its concrete implementation step is:

1. set up the doubly salient permanent magnet motor torque equation under the three-phase square wave control

12/8 utmost point doubly salient permanent magnet motor of straight trough rotor has the back-emf of trapezoidal wave, from traditional control method, should adopt square wave control.Under normal operating condition, adopt the three-phase doubly salient permanent magnet motor of 120 ° of square wave controls, its electromagnetism output torque can be expressed as:

$T_{N\_\mathrm{BLDC}}=\frac{6E_m{I}_m}{\mathrm{\ω}}---\left(1\right)$

Wherein, E _mBe doubly salient permanent magnet motor back-emf peak value, I _mBe the square wave current peak value that motor adopts, ω is the angular speed of motor.

2. set up the doubly salient permanent magnet motor torque equation under the three-phase sine-wave control

In three-phase 12/8 utmost point doubly salient permanent magnet motor of the present invention, 12 salient poles are arranged on the stator, be distributed with 4 permanent magnets at four angles, the magnetic direction of permanent magnet is along the circumferencial direction of motor, 8 salient poles are arranged on the rotor, and the rotor with salient pole width is slightly larger than the width of stator salient poles.Described rotor adopts the straight trough design, to guarantee motor exerting oneself more greatly in running.Simultaneously,, equally also can adopt sine wave to control, reach same torque output as traditional trapezoidal wave back-emf motor.This moment, the three-phase electromagnetic torque output of motor can be expressed as:

$T_{N\_\mathrm{BLAC}}=\frac{9E_{m1}{I}_{\max }}{2\mathrm{\ω}}---\left(2\right)$

Wherein, E _MlBe the peak value of doubly salient permanent magnet motor back-emf first-harmonic, I _MaxSine-wave current peak value for the motor employing.Desirable trapezoidal wave back-emf is carried out harmonic analysis as can be known, E _Ml/ E _m=1.216, therefore try to achieve:

I _max＝1.096I _m (3)

So the sinusoidal current of equivalence can be expressed as:

$\left\{\begin{array}{c}{i}_a=1.096I_m\sin \left(\mathrm{\ωt}\right)\\ i_b=1.096I_m\sin (\mathrm{\ωt}+2\mathrm{\π}/3)\\ i_c=1.096I_m\sin (\mathrm{\ωt}-2\mathrm{\π}/3)\end{array}\right.---\left(4\right)$

3. set up the doubly salient permanent magnet motor torque equation under the sinusoidal wave fault-tolerant control of two-phase

By formula (4) as can be known, the rotation magnetomotive force in doubly salient permanent magnet motor this moment can be expressed as three-phase magnetomotive force sum

MMF＝MMF _a+MMF _b+MMF _c (5)

＝NI _a+αNI _b+α ²NI _c

Wherein N is the number of turn of every phase, 120 ° of α=1 ∠

$\mathrm{MMF}=\frac{3}{2}F(\cos \mathrm{\θ}+j\sin \mathrm{\θ})---\left(6\right)$

F=NI wherein _Max, θ=(ω t).

If b breaks down at a time mutually and can't work quarter, then this moment

$\mathrm{MMF}\′={\mathrm{NI}\′}_a+{\mathrm{\α}}^2{\mathrm{NI}\′}_c={\mathrm{NI}\′}_a+{\mathrm{NI}\′}_c(-\frac{1}{2}-j\frac{\sqrt{3}}{2})---\left(7\right)$

Make formula (5) equate, can obtain with formula (7)

$\left\{\begin{array}{c}{I\′}_a=1.9I_m\sin (\mathrm{\ωt}+\mathrm{\π}/6)\\ {I\′}_c=1.9I_m\sin (\mathrm{\ωt}+\mathrm{\π}/2)\end{array}\right.---\left(8\right)$

Can obtain as drawing a conclusion by formula (8): for the doubly salient permanent magnet motor of open-phase fault state takes place, by non-fault phase current is carried out the linear transformation of amplitude and phase place, become original square wave and be controlled to be the sinusoidal wave control of fault tolerant type, can make this motor driven systems under the open-phase fault state, obtain the approximate magnetomotive force that is equal to normal operation, that is to say that this system can operate with failure; And this moment, the output torque of motor will remain unchanged.

Claims (1)

1. the fault tolerant control method of a three-phase doubly salient permanent magnet motor, it is characterized in that, in control system, increased the fault detect link, when not detecting open-phase fault, control system promptly adopts 120 ° of square wave current control of three-phase doubly salient permanent magnet motor according to the normal operation pattern.When system detected open-phase fault, electric machine control system was enabled fault-tolerant control model, was divided into following three steps:

A. according to the doubly salient permanent magnet motor torque equation of three-phase square wave control under the normal operating condition, calculate the current amplitude of the three-phase sine-wave control that produces equivalent torque, its value should be 1.1 times of square wave current amplitude;

B. according to and three-phase sine-wave produce the constant principle in magnetic field, calculate the amplitude and the phase place of the fault-tolerant sine-wave current of two-phase, when its amplitude should be normal operation 1.73 times of the three-phase sine-wave current amplitude, when promptly normally moving 1.9 of the three-phase square wave electric current times; The last phase of fault phase, phase place becomes leading 150 ° for 120 ° by original leading fault phase, a back phase of fault phase, phase place becomes 150 ° of hysteresis for 120 ° by original hysteresis fault phase;

C. according to the amplitude and the phase place of the mutually fault-tolerant sine-wave current of fault-tolerant when control work that calculates, becomes original three-phase square wave and be controlled to be that two-phase is sinusoidal wave to be controlled.

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