CN104158462A - Method for detecting initial position of sensorless permanent magnet synchronous motor - Google Patents

Abstract

The invention relates to a method for detecting the initial position of a sensorless permanent magnet synchronous motor. On the basis of ensuring the static state of the motor, open-loop control is carried out on current, the initial position of a rotor is initialized, estimated high-frequency alternating axial current is extracted by injecting high-frequency cosine voltage signals into an estimation direct axis of an estimated synchronous rotating coordinate system, and signal processing and adjusting are carried on the high-frequency alternating axial current to obtain the estimated initial value of the initial position of the rotor; then a plurality of high-frequency cosine voltage signals of the determined period are continuously injected into the estimation direct axis, and the magnetic polarity is judged and the accurate initial position of the rotor is obtained by judging whether an integral value of the direct axis current is positive or negative. Motor parameters do not need to be obtained, the problem that as an existing rotor initial position detecting method possibly causes motor rotation, identification signals are difficult to detect is effectively avoided, hardware does not need to be additionally arranged, implementation is convenient, and the initial position of any rotor magnetic pole can be accurately obtained when the motor is in the static state.

Description

A kind of permagnetic synchronous motor initial position detection method of position-sensor-free

Technical field

The determination methods that the present invention relates to rotor initial polarity, belongs to Motor Control Field, relates in particular to a kind of permagnetic synchronous motor initial position detection method of position-sensor-free.

Background technology

Permagnetic synchronous motor, due to its good runnability, is widely used in AC Drive field.Yet, the control of permagnetic synchronous motor need to be known rotor-position and speed accurately, the mechanical sensor of for this reason installing is as photoelectric code disk, resolver etc., volume and the cost of system have not only been increased, and the reliability of system, the application scenario of having limited permagnetic synchronous motor have been reduced.Therefore, a lot of experts and scholars are devoted to the research of position-sensor-free in recent years.Wherein, it is important and problem demanding prompt solution that the initial position of rotor detects always, and can its accuracy have directly determined that can motor start smoothly, and with maximum torque starting.

At present, Chinese scholars has proposed the permagnetic synchronous motor initial position detection method of multiple position-sensor-free.If when starting allows that rotor rotates, simple effective method is to pass into direct current to stator, produces a stationary magnetic field so that rotor is positioned in the zero position of setting, completes the initialization of rotor-position.But in a lot of application scenarios, require motor at any resting position normal starting, to have scholar to propose High Frequency Injection for this reason.These class methods are applicable to salient pole type and non-salient pole permanent magnet synchronous motor.Its basic principle obtains rotor-position by detecting curtage signal.These class methods generally realize in two steps, first rotor-position are carried out to preresearch estimates, then detect pole polarity and compensate, and obtain final initial position of rotor.Wherein, pole polarity being detected and conventionally has two kinds of modes, is all to estimate that d-axis injects the wide positive negative sense potential pulse of constant amplitude and realizes.A kind of is that the current peak more now producing is determined, another kind of be to determine time when relatively rising or dropping to a certain current value.Yet above-mentioned two kinds of methods are amplitude and the duration of necessary choose reasonable Injection Signal all.If signal amplitude is excessive or the duration longly may cause electric machine rotation, too small or too short peak difference or time difference that cannot detect electric current of duration of amplitude.

Summary of the invention

The present invention is intended to propose a kind of permagnetic synchronous motor initial position detection method of position-sensor-free, and pole polarity detection method especially, to solve the defect that may cause electric machine rotation that existing method exists and the problem of identification signal detection difficult.

In order to solve the existing problem of background technology, the technical solution that the present invention adopts is:

A permagnetic synchronous motor initial position detection method for position-sensor-free, the method comprises the steps:

Step 1: definition actual angle is that θ, estimated angle are and lag behind θ, estimate that angular error is that Δ θ, actual d-axis are that d axle, actual quadrature axis are that q axle, estimation d-axis are axle, estimation quadrature axis are axle, actual synchronization rotational coordinates are that the synchronous rotating frame of d-q, estimation is then guaranteeing, under motor inactive state, electric current to be carried out to open loop control, initialization initial position of rotor, first supposes arbitrarily an initial position of rotor;

Step 2: axle injects lasting high frequency cosine voltage signal, given shaft voltage is the A that detection is sampled, B two-phase winding current signal i _a, i _bcarry out coordinate transform, obtain shaft current in high frequency response

Step 3: due to what obtain shaft current in high frequency response comprise the signal relevant to rotor-position, right carry out signal processing and regulate the initial value obtaining for the initial position of rotor estimation of coordinate transform

Step 4: continue axle injects several high frequency cosine voltage signal U that determines the cycle _hcos ω _ht, the A that detection is sampled, B two-phase winding current signal i _a, i _bwith the estimated position obtaining carry out coordinate transform, obtain shaft current

Step 5: to what obtain shaft current carry out integration, obtain integrated value

Step 6: by judgement positive and negatively determine pole polarity and initial position of rotor: if for just, magnetic pole positive direction is consistent with injecting voltage forward, its initial position of rotor if for negative, magnetic pole positive direction is contrary with injecting voltage forward, its initial position of rotor so far complete the detection and identification of initial position of rotor.

Beneficial effect of the present invention is: the permagnetic synchronous motor initial position detection method of this position-sensor-free, without knowing the parameter of electric machine, that has effectively avoided existing method for detecting initial position of rotor existence may cause electric machine rotation, the problem of identification signal detection difficult, without increasing hardware, be convenient to realize, realized the under static state Obtaining Accurate of any rotor magnetic pole initial position of motor.

Accompanying drawing explanation

Fig. 1 is the physical model figure of permagnetic synchronous motor under synchronous rotating frame.

Fig. 2 is that pole polarity of the present invention detects schematic diagram.

Fig. 3 is the flow chart of the inventive method.

Embodiment

Below in conjunction with Fig. 1 to Fig. 3, the specific embodiment of the invention is described, present embodiment comprises the following steps:

Step 1: if Fig. 1 permagnetic synchronous motor is as shown in the physical model figure of synchronous rotating frame, definition actual angle is that θ, estimated angle are and lag behind θ, estimate that angular error is that Δ θ, actual d-axis are that d axle, actual quadrature axis are that q axle, estimation d-axis are axle, estimation quadrature axis are axle, actual synchronization rotational coordinates are that the synchronous rotating frame of d-q, estimation is then guaranteeing, under motor inactive state, electric current to be carried out to open loop control, initialization initial position of rotor, first supposes arbitrarily an initial position of rotor.

Step 2: as shown in the flow chart of Fig. 3 the inventive method, axle injects lasting high frequency cosine voltage signal wherein subscript h represents high fdrequency component, U _hfor injecting the amplitude of high-frequency signal, ω _hfor injecting the angular frequency of high-frequency signal, t is the time.The A that detection is sampled, B two-phase winding current signal i _a, i _bcarry out coordinate transform, extract estimation high frequency quadrature axis electric current, obtain shaft current in high frequency response

In formula, Δ L=(L _d-L _q)/2, L _d, L _qfor d, q axle inductance, | Z _d|, | Z _q| be the mould of d, the impedance of q axle, for its corresponding phase angle.By formula (1), can be found out, axle high-frequency current sinusoidal variations in one-period by the average moment of its generation, be zero, and this current cycle is much smaller than electromechanics time constant, therefore can not cause electric machine rotation.

Step 3: due to what obtain shaft current in high frequency response comprise the signal relevant to rotor-position, right carry out signal processing and adjusting, will with sin ω _ht multiplies each other, and can obtain following error signal f through low pass filter (LPF) _{Δ θ}:

In formula, Δ θ is site error value.When institute, Injection Signal frequency meets ω _h> R _s/ L _dtime, R _sfor stator resistance, can make k>0.

When site error value Δ θ hour, f _{Δ θ}be similar to and be proportional to Δ θ, if can regulate f _{Δ θ}make it to level off to zero, the estimated value of rotor-position will converge on actual value θ.In the inventive method by f _{Δ θ}through integral controller, regulate to obtain the initial value of position estimation

But from formula (2), when Δ θ equals 0, when pi/2, π or 3 pi/2, f _{Δ θ}be zero, at this moment regulating system is all in stable state.And only have Δ θ=0 o'clock, thereby must get rid of its excess-three kind situation.First carry out for this reason convergence property analysis, first estimated angle initial value is all made as zero herein, with rotor physical location in (0, pi/2) for example, due to k>0, formula (2) is known, f _{Δ θ}>0, under the regulating action of adjuster increase gradually, finally can converge on physical location θ; In like manner, by above-mentioned derivation, can show that physical location is at other during interval and boundary value convergency value as shown in Figure 2, wherein dotted line is physical location θ, solid line is estimated position

As shown in Figure 2: convergency value and θ between relation there are two class situations:

(1) if convergency value is 0, θ=0, pi/2, π or 3 pi/2s;

(2) if convergency value is not 0, or

For first kind situation, need to carry out specific position judgement.Concrete grammar is as follows: take rotor physical location as 0 being example, set specific position judgement T constantly, if estimating algorithm runs to T constantly still be zero (or to be less than certain threshold value θ _t), show that rotor, in (or approaching) 0, pi/2, π or these four specific positions of 3 pi/2s, now changes value, might as well be made as π/4, take rotor reality in 0 being example, now f _{Δ θ}<0, passes through the effect of regulating system, reduce gradually, finally converge to 0; In like manner, can push away to such an extent that its excess-three kind convergence situation is as shown in table 1.So far all results can unify be or only need carry out again pole polarity judgement.

Table 1 specific position judgement convergence property

Due to the saturated salient pole nature of motor, the current response value that the current response value producing when the voltage direction injecting is consistent with pole polarity positive direction produces when contrary is large, can carry out the judgement of pole polarity thus.

Step 4: obtain the initial value for the initial position of rotor estimation of coordinate transform by step 3 after, continue axle injects the high frequency cosine voltage signal U that several (supposing 10) determine the cycle _hcos ω _ht, the A that detection is sampled, B two-phase winding current signal i _a, i _bwith the estimated position obtaining carry out coordinate transform, obtain shaft current

Step 5: to what obtain shaft current carry out integration, obtain integrated value

Step 6: by judgement positive and negatively determine pole polarity and initial position of rotor: if for just, magnetic pole positive direction is consistent with injecting voltage forward, its initial position of rotor if for negative, magnetic pole positive direction is contrary with injecting voltage forward, its initial position of rotor so far complete the detection and identification of initial position of rotor.

Protection range of the present invention relates to all changes form recited above.

Claims (1)

1. a permagnetic synchronous motor initial position detection method for position-sensor-free, is characterized in that, the method comprises the steps:

Step 1: definition actual angle is that θ, estimated angle are and lag behind θ, estimate that angular error is that Δ θ, actual d-axis are that d axle, actual quadrature axis are that q axle, estimation d-axis are axle, estimation quadrature axis are axle, actual synchronization rotational coordinates are that the synchronous rotating frame of d-q, estimation is then guaranteeing, under motor inactive state, electric current to be carried out to open loop control, initialization initial position of rotor, first supposes arbitrarily an initial position of rotor;

Step 2: axle injects lasting high frequency cosine voltage signal, given shaft voltage is the A that detection is sampled, B two-phase winding current signal i _a, i _bcarry out coordinate transform, obtain shaft current in high frequency response

Step 3: due to what obtain shaft current in high frequency response comprise the signal relevant to rotor-position, right carry out signal processing and regulate the initial value obtaining for the initial position of rotor estimation of coordinate transform

Step 4: continue axle injects several high frequency cosine voltage signal U that determines the cycle _hcos ω _ht, the A that detection is sampled, B two-phase winding current signal i _a, i _bwith the estimated position obtaining carry out coordinate transform, obtain shaft current

Step 5: to what obtain shaft current carry out integration, obtain integrated value

Step 6: by judgement positive and negatively determine pole polarity and initial position of rotor: if for just, magnetic pole positive direction is consistent with injecting voltage forward, its initial position of rotor if for negative, magnetic pole positive direction is contrary with injecting voltage forward, its initial position of rotor so far complete the detection and identification of initial position of rotor.