Analysed on the upright voltage when constant of modulation of bridge arm PWM, arm playing the bridge opens modulation way is undee, discuss to turn over electromotive force accordingly to detected at 0 o’clock too method. In PWM modulation signal liberal position ends hour to undertake sampling to carrying voltage, turn over electromotive force to pass certainly by software algorithm at 0 o’clock. The circumstance of lead commutation or lag commutation exists when moving in the light of electric machinery, will realize optimal commutation through setting reasonable defer time. In the light of actual electric machinery existence turns over electromotive force to pass the case with inhomogenous 0:0 cloth, according to passing time interval was existing at 0 o’clock seasonal pattern, put forward a kind of new defer time to set a means, make commutation dot is located in photograph adjacent to cross the intermediate position 0 o’clock, realized the accurate commutation of electric machinery. Experimental test and verify the feasibility that offers a means and effectiveness.

 

Without brush dc machine (BLDCM) has a structure simple, moving efficiency is mixed high timing performance is good wait for an advantage, get applied extensively in industry and commercial domain. In recent years, having those who brush dc machine to be controlled without positional sensor is domestic and international research heat all the time, relatively common rotor position signal detects the method has turn over diode of electromotive force law, stator inductance law, follow on current estimation technique of law, linkage and condition observation implement the law, oppose electromotive force law among them most effective and practical.

 

Fast when, close to detect with liberal phase in PWM respectively oppose electromotive force, the referenced tension that uses 2 to differ is obtained turn over electromotive force to pass at 0 o’clock, and do not need positional sensor and voltaic sensor, but the complexity that increased hardware circuit. Document carries the significance of voltage and voltage of midpoint of inverter dc annulus through comparing impending photograph winding, obtain turn over electromotive force to pass at 0 o’clock. This method need not reframe electric machinery is bit neuterer, do not use filter wave circuit, but need to use hardware circuit to had gotten quite at 0 o’clock.

 

Put forward when means of On _pwm modulation turn over electromotive force to detected at 0 o’clock too method, use inside the small controller of buy AD detects when PWM is enlightened impending photograph carries voltage, simple algebraic operation is used in software algorithm, obtain pass well and truly at 0 o’clock signal. Current, turn over electromotive force to pass about turning over the research of electromotive force law to be in centrally more 0 o’clock detect the elimination of circuit method and the phasic error that cause by filtrate circuit or compensation method, but the research in accurate commutation respect is still insufficient and thorough.

 

 

Without brush dc machine to use “ two-phase to guide commonly a three-phase run mode of 6 condition ” , every job status has two-phase winding to guide only, three-phase winding is in impending condition, be used to detect turn over electromotive force to pass at 0 o’clock. Detecting turn over electromotive force to pass after 0 o’clock, according to commutation dot lag passes at 0 o’clock 30° report angle, set corresponding defer time. After defer time arrives, electric machinery commutation enters next job state.

 

This literary grace turns over electromotive force to detect directly with what be based on upright voltage circuit, through detecting the upright voltage signal of impending photograph winding is obtained turn over electromotive force to pass at 0 o’clock. Use cent to press resistor to undertake be dividinged with scale pressing to carrying voltage and dc side voltage, make the signal be measuringed after cent pressing falls inside the input range that sampling unit permits. Graph 1 (A) is mixed for main circuit turn over cent of electromotive force law to press circuit directly, carry voltage UA, UB, after cent is pressed, UC and UDC course are Ua respectively, ub, uc and Udc.

 

 

Turn over electromotive force weaveform ideally to make the echelon wave that change to be being lost, and it is reference point with electric machinery center, in graph 1 (B) , EA, EB, EC states three-phase opposes electromotive force respectively. Electric machinery shares 6 jobs position inside a cycle, status of job of angle of report of every other 60° is changed, every power switch guides a 120° report angle. Working status is OK by guide the two-phase winding that connect and 2 power switch express, if what graph 1 (B) shows, BA states electric current is flowed into from B photograph winding, the 2 power switch that pours out of;Q3Q4 to state arm of the bridge on B photograph and A photograph lay bridge arm from A photograph winding guides. Detected at 0 o’clock too weaveform expresses to turn over electromotive force to was nodded with commutation at 0 o’clock too, among them, z passes to oppose electromotive force at 0 o’clock, c is commutation dot. Turn over electromotive force to pass to distributinged equably with commutation dot at 0 o’clock, those separates 30° report point of view here.

 

 

Without brush dc engine control to be able to use a variety of PWM modulation means. Adoption modulation kind is different, the upright voltage weaveform that appear is different also. This literary grace uses modulation of bridge arm PWM, constant of arm playing the bridge is connected (the modulation means of H _pwm 2L _on) . It is with A photograph exemple, hypothesis PWM occupies sky comparing to be 50% , the pulse burr that noise of high frequency switch and commutation follow on current produce neglect, what the undee 2 (A) that be like a graph shows ideal upright tension. Inside a periodic limits, a photograph upright voltage weaveform differentiates for BA, BC, AC, AB, CB and CA6 area, every area correspondence works condition. The ascendant share that carries voltage weaveform and drop to be BC area and CB area partly, right now A photograph is in impending condition.

 

 

BA and CA area issue bridge arm switch to guide for A photograph a phase, q4 is in constant to open position, a photograph winding and the negative pole of straight voltage drifting side are linked together, upright voltage is arrived to shed the negative pole potential of side voltage continuously by clamp down on. Because shed the negative pole of side voltage to be the reference point that carries voltage continuously, right now upright voltage is 0.

 

AC and AB area are phase of modulation of PWM of switch of arm of the bridge on A photograph. It is with AC area exemple, during PWM is enlightened, q1 and Q2 guide, a photograph winding and the anode of straight voltage drifting side are linked together, during carrying voltage to be shut in PWM for UDC; , q1 is shut, q2 guides, because winding impedance shows sensibility, of arm of the bridge below A photograph turn over shunt-wound diode D4 guides a follow on current, right now A photograph winding and the negative pole of straight voltage drifting side are linked together, upright voltage is 0.

 

BC and CB area are A photograph impending phase, 2 area respective cent is Ⅰ and Ⅱ two period of time, if pursue,place of 2 (B) is shown. It is with BC area exemple, right now electric current from inpour of B photograph winding, c photograph winding is poured out of, if pursue,3 are shown. In the graph, RS and LS express the equivalent resistor of stator winding and inductance respectively, UN is voltage of electric machinery center, I is phase current. Of oversight power switch and diode guide is connected pressure fall, according to Kirchhoff voltage law can be gotten

 

 

 

 

The article opens condition to end hour to undertake sampling to the upright voltage of impending photograph in PWM modulation. Because hardware circuit is put in delay time effect, switch of the power when sampling has not close, during be equivalent to debutting in PWM modulation sampling, be sufferred by the voltage signal of sampling right now switch noise influence is minor. According to type (5) , should detect when A photograph carries voltage to be worth the half that is worth for volts d.c. , a contrary electromotive force passes 0, the comparison of UA and UDC /2 is equivalent to EA and the comparison of 0.

 

Turn over electromotive force to detected at 0 o’clock too the method is simple and accurate, judgement of use software algorithm turns over electromotive force to pass at 0 o’clock. Hardware circuit should choose the resistor with block value and appropriate power to be used at cent pressing only, do not need to reframe electric machinery center, also do not need low connect filter, signal does not have phasic delay time, also do not use comparator to had detected at 0 o’clock. Hardware circuit structure is simple, suit low cost application.

 

 

Optimal commutation logic is to show winding turns over the flat-roofed part of electromotive force to guide in echelon wave connect, to it corresponding optimal commutation position is to point to after commutation is finished, situation of magnetism of rotor of lead of stator magnetism situation 120° report angle, if pursue,5 are shown. Among them, fa and Fr show stator magnetism situation and rotor magnetism sign respectively. In situation of magnetism of the stator inside status of a job angle of report of 90° of situation of magnetism of average lead rotor, average electromagnetism torsion is the biggest.

 

If had turned in commutation hour rotor,cross optimal commutation position, behave for lag commutation, commutation dot is relatively optimal on time axis commutation place is right move, carry voltage weaveform asymmetry, the part on the right side of is undee by annihilation, the defer time TZC that nodded to commutation at 0 o’clock too slants big, if pursue,6 are shown. When lag commutation, rotor exceeds the angle of optimal commutation position to should be less than 30° report angle, if commutation is serious lag, pass to will not detect by annihilation at 0 o’clock next time, cause electric machinery to lose a condition. Conversely, if rotor has not reached optimal commutation place with respect to commutation, it is lead commutation, commutation dot is relatively optimal on time axis commutation position is different move, the share that carries voltage is left and undee by annihilation, the defer time TZC that nodded to commutation at 0 o’clock too slants small. Lag commutation and lead commutation can cause torsion of electric machinery electromagnetism fluctuate, rotor movement is not smooth. The upright voltage of actual measurement is undee (passageway 1) is shown 7 times like the graph, passageway 2 detected at 0 o’clock to pass undee, ascendant edge and drop the edge parts correspondence was nodded with commutation at 0 o’clock too.

 

 

 

According to passing lead commutation nodded the principle of 30° report angle at 0 o’clock, having detectinging after 0 o’clock, TZC of setting defer time decides commutation is nodded. Below good moving position, distributinged with the interval such as commutation dot at 0 o’clock too, each other differ 30° report angle. Accordingly, can set defer time according to crossing the time interval 0 o’clock, method of traditional defer time setting is set defer time arrived at 0 o’clock to pass last this second over- at 0 o’clock the half of time, if pursue,8 are shown. In the graph, z (K) , c (K) expresses K respectively second mixed at 0 o’clock too dot of K second commutation, should detect K second over- when 0 o’clock, if defer time sets buy:

 

 

In type, TZZ (K – 1) is K – 1 second arrived at 0 o’clock too K second cross the time; TZC (K) 0 o’clock to be K second arrived at 0 o’clock too the defer time that K second commutation chooses.

 

Good the setting defer time is record in register, tally begins to time. After arriving at the defer time that sets beforehand, electric machinery commutation enters next job state, situation of stator magnetism situation is entered. Commutation dot is located in photograph adjacent to cross the intermediate position 0 o’clock, electric machinery is changed in optimal commutation position, average electromagnetism torsion is the biggest, upright voltage weaveform assumes symmetrical position. Should turn over electromotive force to pass when cloth is even 0:0, can better land realizes method of traditional defer time setting not to have positional sensor to control without what brush dc machine.

 

 

Instead electromotive force law is detecting again electromotive force weaveform rises and drop instead 2 of the part pass at 0 o’clock, opposite of undee and flat-roofed part detected at 0 o’clock methodological impact is not big. Because electric mechanism creates the effect of the respect such as craft, do not have actually brush the circumstance with not complete and symmetrical winding of three-phase of dc plane existence, bring about three-phase difference exists between electromotive force instead, photograph adjacent crosses the time interval 0 o’clock completely not equal, over- cloth is inhomogenous 0:0. ,

 

Hypothesis A contrary electromotive force is put in phasic deflection, weaveform rises to pass with what drop to go up partly lag appeared at 0 o’clock, had brought about distributinged on time axis at 0 o’clock inhomogenous. If the graph is shown 9 times, dotted line states ideal opposes electromotive force, what solid line expresses to be put in phasic deflection is actual oppose electromotive force, cross the time interval TZZ (1) 0 o’clock, TZZ (2) and TZZ (3) are unequal. Weaveform of every contrary electromotive force rises and drop 2 of the part differred at 0 o’clock too 180° report angle, over- time interval was existing at 0 o’clock seasonal pattern, be like TZZ (1) =TZZ (4) , TZZ (2) = TZZ (5) and TZZ (3) = TZZ (6) .

 

 

The defer time that uses a convention sets a means, drop of commutation of ideal of deviate of certain commutation dot is bigger. When some commutation when serious lag, it is easy at 0 o’clock to pass next time by annihilation, bring about electric machinery to lose a condition, if pursue,10 are shown.

 

 

To make commutation dot is located in photograph adjacent 2 cross the intermediate position 0 o’clock, the article puts forward a kind of new defer time to set a means. If the graph is shown 11 times, cross the time interval TZZ (K – 3) 0 o’clock and TZZ (K) equal, should detect K second over- when 0 o’clock, from K second cross the defer time TZC (K) that to K second commutation nodded at 0 o’clock to install as follows:

 

 

In type, TZZ (K – 3) is K – 3 second arrived at 0 o’clock too K – 2 second spend the time 0 o’clock.

 

The time interval length that turns over electromotive force weaveform when three-phase is not manage graph the 120° report point of view that 11 new defer time set a method to want, over- when time interval is unequal at 0 o’clock, use new defer time to install a method to be able to make commutation more accurate, commutation point drops in around 2 cross the intermediate position 0 o’clock, it is not easy at 0 o’clock to pass by annihilation, electric accident loses a condition not easily all right, if pursue,10 are shown. Move in electric machinery high speed especially when, new method raised the reliability that electric machinery runs, experiment well test and verify the feasibility of new method and effectiveness.

 

The actual measurement of correspondence of method of setting of time of 2 kinds of defer carries voltage weaveform (if passageway 1) pursues 12 are shown, passageway 2 with the passageway 3 detected at 0 o’clock to pass undee, the ascendant edge of 2 mixes the passageway drop the edge is corresponding at passing at 0 o’clock, and the ascendant edge of 3 mixes the passageway drop the edge parts correspondence was nodded with commutation at 0 o’clock too.

 

 

 

Graph the 13 three-phase that are actual measurement carry voltage weaveform (passageway 3) of 1 ～ passageway, the ascendant edge of 4 mixes the passageway drop the edge parts correspondence was nodded with commutation at 0 o’clock too.

 

 

 

1) turns over electromotive force law to carry voltage to obtain through detecting turn over electromotive force to pass at 0 o’clock, setting defer time gets commutation is nodded. This literary grace has been obtained with software algorithm nodded with commutation at 0 o’clock, simplified hardware circuit, apply to low cost application.

 

2) lead commutation or lag commutation can bring about electric machinery move not smooth, upright voltage asymmetry of two side weaveform, through setting reasonable defer time, can make electric machinery is in commutation of optimal commutation position.

 

3) should turn over electromotive force to pass when cloth is even 0:0, the defer time that can use a convention sets a means, be about to defer time setting arrived at 0 o’clock to pass last this second over- at 0 o’clock the half of time.

 

4) is become of actual electric machinery turn over electromotive force to pass cloth is inhomogenous 0:0, can make K second cross the defer time that to K second commutation chose at 0 o’clock to be equal to K – 3 second arrived at 0 o’clock too K – 2 second over- at 0 o’clock the half of time, this one new defer time sets a means, make commutation dot is located in photograph adjacent 2 cross the intermediate position 0 o’clock, realized the accurate commutation of electric machinery. Experiment well test and verify this feasibility of new method and effectiveness.