CN101902190A - Method for estimating rotor position of switched reluctance motor without position sensor - Google Patents

Abstract

The invention discloses a method for estimating the rotor position of a switched reluctance motor without a position sensor, and belongs to the technical field of the control of the switched reluctance motors. In the method, based on the fundamental feature that an inductor of the switched reluctance motor is changed periodically with the rotor position, phase inductance reaches maximum at a position where a stator is aligned with a rotor, so the slope of the phase inductance is changed into negative from positive at the maximum position of the inductance, and slope zero-crossing points exist. In the method, by sampling each phase current and phase voltage in real time, each phase inductance value can be detected in real time, and simultaneously, the inductance slope can be calculated; the calculated inductance slope is subjected to zero balancing to obtain pulse signals of the slope zero-crossing points, so that a zero-crossing position, namely the position where a stator tooth pole is aligned with a rotor tooth pole can be detected; and the phase difference of the two adjacent maximum inductance positions is 45 degrees, so the difference of positions of the two slope zero-crossing points is 1/8 cycle, and the real-time rotate speed and rotor position information of the motor can be calculated according to the zero-crossing pulse signals. The method has the advantages of independent of parameters of a motor body, no need of measurement of motor characteristics such as static flux linkage and the like, simple algorithm and easy realization, so the method has strong generality compared with a non-position strategy.

Description

A kind of method for estimating rotor position of switched reluctance motor without position sensor

Technical field

Invention relates to a kind of method for estimating rotor position of switched reluctance motor without position sensor, belongs to the switched Reluctance Motor Control technical field.

Background technology

(Switched Reluctance Motor SRM) as a kind of novel governing system, not only has the principal advantages of AC and DC speed governing concurrently to switched reluctance machines, and possesses unique high speed performance and fault-tolerant ability.This makes it obtain paying close attention to widely in Aero-Space and various civilian manufacturing AC and DC transmission field, has good application prospects and market value undoubtedly.For switched reluctance motor system, rotor position information is the prerequisite of its reliability service and high performance control in real time and accurately.In practical application at present, general shaft position sensor or other detection type position detectors of adopting obtains positional information, this has not only increased system cost and complexity, reduced the whole system reliability of operation simultaneously, especially at some high temperature, application under the harsh service conditionss such as high speed and oil pollution environment, as aviation high-speed starting/generator, the fuel pump motor, compressor etc., the work of conventional position sensor is restricted, thereby limited the scope of this type motor application greatly, made it high temperature resistant, be fit at a high speed, proper properties such as strong fault tolerance can not find full expression.Therefore, how the position of substitution transducer overcomes the deficiency that adopts position transducer to bring, and explores practical position-sensor-free technology and has crucial researching value.

Traditional position-sensor-free method that is applied to high speed is mainly based on the magnetic linkage or the inductance characteristic curve of motor, non-linear relation according to magnetic linkage or inductance and rotor position angle, by tabling look-up or the method for non-linear observation model is obtained rotor position information, perhaps directly utilize the method for magnetic linkage or inductance threshold values directly to obtain commutation signal, thus the position of substitution transducer.Though these methods all are very classics and effective method, but they all have a common shortcoming, be the associated electrical parameter of magnetic characteristic that they all depend on motor body very much, and very high to the electric symmetry requirement of motor, and the error source that angle is estimated is many.Before these methods of employing, at first must carry out inductance to motor, the measurement of electromagnetic propertys such as magnetic linkage, and the measurement of these parameters itself is exactly very complicated and loaded down with trivial details, and precision is limited; In addition, even to the motor of same model, software parameter all needs to do corresponding modification when control.These problems must cause the portability of algorithm poor, directly have influence on the versatility of no position technique.

Summary of the invention

The problem to be solved in the present invention is:

Overcome traditional relevant no position algorithm preparation complexity based on magnetic linkage or inductance, the Algorithm Error source is many, and problems such as portable difference obtain a kind of simple and be easy to realize the position-sensor-free location estimation strategy of highly versatile.

The present invention adopts following technical scheme for achieving the above object:

The present invention is a kind of method for estimating rotor position of switched reluctance motor without position sensor, based on the inductance of switched reluctance machines with the periodically variable basic characteristics of rotor-position, phase inductance reaches maximum at the rotor aligned position, therefore by just becoming negative, thereby there is the slope zero crossing in the phase inductance slope at the inductance maximum position.Therefore can realize that by following steps rotating speed is estimated and the estimation of rotor-position.

1) detects each phase current and terminal voltage in real time;

2) sample each phase current and terminal voltage of DSP calculated each phase magnetic linkage by digital integration;

3) the phase magnetic linkage is obtained real-time phase inductance divided by electric current;

4) in DSP, calculate the inductance difference of an interrupt cycle;

5) compare each phase inductance size, select the inductance maximal phase as estimating phase;

6) at the selected estimation alpha region of step 5) with above-mentioned steps 4) in inductance difference and the zero balancing of calculating, if greater than 0 be high level, as if being low level smaller or equal to 0; Thereby obtain the pulse signal of zero crossing, the zero crossing position is the rotor aligned position;

7) differ 45 degree in the step 6) between adjacent two zero-crossing pulse trailing edges, i.e. 1/8 cycle, thus can estimate rotating speed and rotor position information.

This algorithm does not rely on the motor body parameter, need not measure motor characteristics such as static magnetic linkage yet, and algorithm is simple and be easy to realize that therefore not having the position strategy with respect to tradition has stronger versatility.

Description of drawings

Fig. 1 is a switched reluctance machines governing system block diagram;

Fig. 2 is the relation of the three pole reactor and the rotor-position of 12/8 structure model machine;

Fig. 3 is model machine one a phase inductance characteristic curve;

Fig. 4 is inductance characteristic three-dimensional relationship figure;

Fig. 5 is principle of the invention schematic diagram (A is example mutually);

Fig. 6 is zero passage detection pulse signal and position angle graph of a relation;

Fig. 7 is for after electric current enters region of saturation current, and inductance curve and slope curve concern schematic diagram;

Inductance real-time computing technique FB(flow block) when Fig. 8 moves for motor;

Fig. 9 is the method for estimating rotor position of switched reluctance motor without position sensor schematic diagram of 0 degree for a kind of turn-on angle of the present invention;

Figure 10 the present invention is a kind of to be fit to open/close the adjustable position-sensor-free rotor-position method of estimation of the angle of rupture.

Embodiment

The present invention utilizes the relation of inductance and rotor-position, estimates rotating speed and rotor position information by the method that detects each cycle maximum induction location point.

Be elaborated below in conjunction with the technical scheme of accompanying drawing to invention:

Fig. 1 is a switched reluctance machines governing system block diagram.The switched reluctance machines governing system mainly is made up of switched reluctance machines (SRM), power inverter, control system (DSP+CPLD), position transducer and electric current and voltage detection and protective circuit etc.Its middle controller is the core of system, and detection signal is gathered, calculated and handles, and finishes relevant control algolithm, thus the output control signal corresponding.Inductance among the present invention calculates and the algorithm of position-sensor-free technology is finished by controller, need not to add additional hardware.Phase current and phase winding voltage are detected by voltage, current sensor (LEM).

Fig. 2 is the relation of the three pole reactor and the rotor-position of 12/8 structure model machine.Shown in figure, the inductance curve is the cycle with 45 degree, and wherein each phase inductance differs 15 degree.If 0 degree angle is A phase stator tooth center line and rotor center line aligned position, 22.5 degree are rotor tooth utmost point center line aligned position.

Fig. 3 (A) is with model machine one phase inductance characteristic curve.The inductance characteristic curve has characterized the non-linear relation between phase inductance and rotor position angle and the phase current three, the figure shows under the same current phase inductance family of curves of different rotor position.As seen from the figure, phase inductance reduces with the increase of electric current, and when electric current reaches certain value, inductance will occur saturated, and this moment, flat-top appearred in inductance curve top.Its three-dimensional relationship can be by formula (1) expression, and three-dimensional relationship figure as shown in Figure 4.Fig. 3 (B) is the phase inductance slope curve under the same current.

L＝L(θ，i)(1)

Fig. 5 is to be example explanation principle of the invention schematic diagram mutually with A.As shown in the figure, phase inductance curve, phase inductance slope curve, and slope zero crossing pulse signal.Pulse signal trailing edge position is the inductance maximum position.Between two adjacent trailing edges 45 degree, i.e. 1/8 Machine cycle.Zero passage detection pulse signal and position angle graph of a relation are as shown in Figure 6.

Fig. 7 (A) is for after electric current enters region of saturation current, and inductance curve and slope curve concern schematic diagram.Fig. 7 (B) is near the inductance slope zero crossing schematic diagram inductance maximum position, as known in the figure, after electric current reaches capacity, because inductance is saturated, flat-top occurs at the inductance top, and a plurality of zero points may appear in the inductance slope, causes the location estimation error.But because in the motor actual moving process, owing to will make the afterflow district electric current that enters inductance decline district as far as possible little, with the negative torque that reduces to produce, so must before inductance 22.5 degree, turn-off, thereby make near the position of 22.5 degree electric current much smaller than saturation current, when real electrical machinery moved, inductance slope negative sense zero crossing had only one, promptly corresponding 22.5 degree positions, so the inventive method is fit to the position probing and the velocity estimation of switched reluctance machines operation fully.

Inductance real-time computing technique FB(flow block) when Fig. 8 moves for motor.Phase current and phase winding voltage are detected and are obtained by voltage, current sensor (LEM), after conditioning, start the A/D sampling routine in DSP, sampling winding terminal voltage and phase current.Calculate the magnetic linkage size according to the integration formula.Wherein the magnetic linkage expression formula of a phase winding is:

${\mathrm{\ψ}}_k\left(t\right)={\∫}_0^t(v_k\left(t\right)-R_k{i}_k\left(t\right))\mathrm{dt}+{\mathrm{\ψ}}_k\left(0\right)---\left(2\right)$

ψ wherein _kBe k phase winding magnetic linkage, v _kBe k phase winding terminal voltage, R is a k phase winding equivalent resistance, i _kK phase winding electric current.Use numerical integrating, following formula can be dispersed turns to:

${\mathrm{\ψ}}_k\left(n\right)=\underset{n=1}{\overset{N}{\mathrm{\Σ}}}[v_k\left(n\right)-R_k{i}_k\left(n\right)]T+{\mathrm{\ψ}}_k\left(0\right)---\left(3\right)$

Wherein T is the sampling period, the some number of N for measuring, and n is the n measurement point.

Can obtain inductance value according to the relational expression between inductance and the magnetic linkage.

ψ(θ，i)＝L(θ，i)i (4)

$L(\mathrm{\θ},i)=\frac{\mathrm{\ψ}(\mathrm{\θ},i)}{i}---\left(5\right)$

This method is owing to introduced integral operation, and phase voltage, phase current detect error, and the variation of winding equivalent resistance, all can influence the precision of calculating, and the magnetic linkage when the relatively more suitable motor speed of this method is higher is estimated.

Fig. 9 is a kind of method for estimating rotor position of switched reluctance motor without position sensor schematic diagram of the present invention, and the motor turn-on angle is 0 degree.If 0 degree angle is A phase stator tooth center line and rotor center line aligned position, 22.5 degree are rotor tooth utmost point center line aligned position, each phase phase difference 15 degree.

Wherein Fig. 9 (A) is processing method one schematic diagram:

It is the waveform that 0 each phase inductance when spending calculates in real time that Fig. 9 (A) is depicted as turn-on angle, with A is example mutually, according to the relation between inductance and the position angle, as seen from the figure, the inductance slope of inductance rising area will be more than or equal to 0 when 0-22.5 spends, and when the electric current afterflow descended the district to inductance, it is negative that the inductance slope becomes, therefore 22.5 degree positions are that inductance slope negative sense is crossed zero position, so the inductance slope k is through obtaining pulse signal P as shown in the figure after the zero balancing _aSignal output waveform is provided with relevant with the program of digital zero-crossing comparator.(1) as if k＞0, P _a＞0; K≤0, P _a=0.Then can obtain the waveform of Fig. 9 (A1).(2) as if k 〉=0, P _a＞0; K＜0, P _a=0.Then passable waveform to Fig. 9 (A2).The trailing edge of adjacent two pulses by detecting the gained pulse signal writes down the time T between two trailing edges _DownGet final product through type (6) and obtain rotary speed information, just can estimate the real-time position of rotor according to the real-time rotating speed that estimates.

n _srm＝7.5T _down (6)

Figure 10 is fit to open/close the adjustable position-sensor-free rotor-position method of estimation of the angle of rupture for the present invention is a kind of.When turn-on angle shifts to an earlier date, can judge according to Fig. 9 method in theory to obtain the corresponding zero passage pulse signal.As inductance slope k＞0, P _a＞0; K≤0, P _a=0, therefore can obtain zero-crossing pulse signal shown in Figure 10 (A).But in the DSP numerical control system, inductance slope calculation mode is to calculate inductance sampled point difference and the ratio of interrupt cycle in the adjacent interruption, owing to only just can calculate opening phase inductance, and the calculated value of inductance is 0 when turn-offing, therefore in moment that estimated phase is just opened, there is a sudden change in the missionary society of twice inductance sampled value before and after opening, make this cycle slope calculated value greater than 0, and the inductance slope meter is added into the stable region in each sampling period afterwards, therefore descend district's inductance slope less than 0 at inductance, and in the inductance rising area, the inductance slope is greater than 0, if adopt above-mentioned numeral to cross the method for zero balancing, then can obtain the zero-crossing pulse waveform shown in Figure 10 (B).As seen from the figure, in one-period, two pulses be can occur, estimation rotating speed and rotor-position that above-mentioned detection trailing edge estimation approach can't be correct therefore adopted.

For solving the problem that said method occurs at experimentation, the present invention proposes a kind of with said method with based on the estimation of the inductance size subregion location estimation strategy that combines of system of selection mutually, this method has been avoided the problem that occurs misvaluing the meter pulse under the situation opening in advance cleverly, and concrete grammar describes in conjunction with Figure 10 (C).

Shown in Figure 10 (C), this method is by three-phase actual measurement inductance size relatively, select inductance calculated value maximum as current estimation phase, this selects logic by shown in the table one mutually, promptly works as L _a＞L _c＞L _dThe time, select A mutually as estimating phase; Work as L _c＞L _b＞L _a, select C mutually as estimating phase; Work as L _b＞L _a＞L _c, select B mutually as estimating phase.In case selected estimation phase, then calculate current estimation phase inductance slope, and utilize the digital method of crossing zero balancing to obtain zero-crossing pulse signal PA, PB, the PC of single estimation phase, also can obtain one group of integrated pulse signal Puse that comprehensively respectively estimates phase zero-crossing pulse signal simultaneously.

Table one inductance zoned logic table

The inductance logic	The zone	The location estimation phase
			L a＞L c＞L b	I	A
L c＞L b＞L a	II	C
			L b＞L a＞L c	III	B

Because the trailing edge position of zero-crossing pulse signal PA, PB or PC is this phase inductance maximum position, and phase difference 45 is spent between adjacent two trailing edges, therefore catches the trailing edge of any one group of zero-crossing pulse signal, writes down the time T between two trailing edges _Down, can utilize formula (6) to calculate rotary speed information equally, estimate the rotor real time position simultaneously.And because above-mentioned Puse signal, each trailing edge correspondence each phase inductance maximum position, and 15 degree of therefore being separated by between the adjacent trailing edge in like manner can be estimated rotary speed information and rotor real time position by the method for catching trailing edge.

The inventive method is only determined rotor real time position and rotary speed information by the method for estimating ad-hoc location, possesses following advantage:

1) principle is simple, implements very convenient flexible;

2) program is simple, no complex calculations and form stores, and it is few to take software resource, and need not additionally to increase hardware;

3) do not need independent measurement static electromagnetic characteristic curve, saved the set-up procedure of traditional no position algorithm complexity;

4) be fit to motor in middling speed, the rotating speed of high speed whole service scope is estimated and position probing, opens/close all capable of regulatings of the angle of rupture, satisfies the motor runnability;

5) has very strong robustness, motor speed fluctuation, the detection that external disturbance can impact position;

6) not high to parameter of electric machine requirement, even in the not high situation of the inductance symmetry that causes owing to the motor processing problems, still can accurately estimate the maximum induction position;

7) algorithm is portable strong, highly versatile, and the rotating speed or the rotor-position that are fit to the regular tap reluctance motor of any structure and power grade are estimated.

Claims (1)

1. a method for estimating rotor position of switched reluctance motor without position sensor is characterized in that comprising the steps:

1) detects each phase current and terminal voltage in real time;

2) sample each phase current and terminal voltage of DSP calculated each phase magnetic linkage by digital integration;

3) the phase magnetic linkage is obtained real-time phase inductance divided by electric current;

4) in DSP, calculate the inductance difference of an interrupt cycle;

5) compare each phase inductance size, select the inductance maximal phase as estimating phase;

6) at the selected estimation alpha region of step 5) with above-mentioned steps 4) in inductance difference and the zero balancing of calculating, if greater than 0 be high level, as if being low level smaller or equal to 0; Thereby obtain the pulse signal of zero crossing, the zero crossing position is the rotor aligned position;

7) differ 45 degree in the step 6) between adjacent two zero-crossing pulse trailing edges, i.e. 1/8 cycle, thus can estimate rotating speed and rotor position information.

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