CN101257271A - Motor control circuit and method as well as brushless motor system - Google Patents

Abstract

The invention relates to a motor control circuit and a brushless motor system, and provides a motor control method, circuit and brushless motor. The motor includes a three-phase coil, the first terminal of each coil is coupled at a node jointly. The method includes: when no current go through a first specific coil in the three-phase coil, and when the current flows from the second terminal of the second specific coil to the second terminal of the third specific coil, detecting the voltage at the second terminal of the first specific coil as a first appointment voltage; detecting the potential drop of the DC sensing resistor as a second appointment voltage; estimating the zero-cross point by the first appointment voltage, the second appointment voltage and the DC voltage supplied to the motor so as to control the motor. The invention is capable of detecting the zero-cross point of the motor in the PWM-off state, which further controls the phase change of motor, in addition, the invention can detect the zero-cross point by conjunction with PWM-off, thereby decreasing the phase change error, which is very practical.

Description

Motor control circuit and method and brushless motor system

Technical field

The present invention relates to a kind of motor control technique, particularly relate to a kind of motor control method, motor control circuit and brushless motor system.

Background technology

The adjustable rotational speed motor is applied in factory automation system, ventilating system, air-conditioning system or the like widely.Existing known adjustable rotating speed motor is the motor that adopts the brush form, disposes brush (Brush)-commutator (Commutator) on this kind motor.Since oneth century of past, the commutation of brush motor is by electrographite brush always and touches the annular commutator that is installed on the runner and realize.Yet above-mentioned brush motor is comparatively heavy, can produce very big noise during running, and efficient is low.Along with being showing improvement or progress day by day of science and technology, there is the people just to develop brushless motor (Brushless-Motor), and is indebted to the progress of design and material technology, its price sharply reduces.Nowadays, the cost variance that reaches between the technology of this two breeds of horses has only 10%.Therefore brush motor being replaced gradually in recent years by brushless motor.

Seeing also shown in Figure 1ly, is the structural representation that illustrates to typical brushless motor.This motor comprises that one has rotor (rotor) 14, Hall element 15～17 and the motor drive circuit 18 of 3 stators (stator) coil 11～13, employing permanent magnet, wherein, these three stator coils 11～13rd have an end to be coupled in together individually, and the other end (A, B, C node) is to be couple to motor drive circuit 18 (A, B, C node) respectively.This motor is called 3 phase motors again.After this motor control circuit 18 mainly is the position that is forwarded to by Hall element 15～17 detecting motor rotors 18, drive 3 stators (stator) coil 11～13 with the velocities of rotation of control rotor, turned position or the like by A, B, C node.

Yet, at some environment or structure is not allow to dispose on motor Hall element, the motor of the compressor of cold air or refrigerator for example, this motor seals, and this motor must operate at higher temperature, therefore many people's researchs had before been arranged how under the environment that does not dispose Hall element, done the rotor-position detecting.Because the rotor of brushless motor is to adopt permanent magnet as rotating shaft, so rotor can produce back electromotive force (back-EMF) when rotated.See also shown in Figure 2ly, illustrating is known Fig. 1 motor drive circuit 18 and the equivalent circuit diagram of brushless motor.As shown in Figure 2, wherein motor control circuit 18 comprises switch electric crystal S201～S206, and the stator coil 11～13 of brushless motor comprises equivalent inductance L respectively _s, equivalent series resistance R _sWith back electromotive force (Back Electro-Motive Force, back-EMF) voltage source E _A～E _C Motor control circuit 18 utilizes the conduction and cut-off of the mode control switch electric crystal S201～S206 of pulse wave width modulation (abbreviating PWM as) respectively, to reach the current i that control is supplied to stator coil 11～13 _a～i _cPurpose.Each switch element S201～S206 has PWM-on state and PWM-off state respectively.

Seeing also shown in Figure 3ly, is the oscillogram of the back electromotive force that produced when rotating with motor of the ideal current waveform that illustrates existing known Fig. 1 three-phase motor.Please shown in Figure 2 in conjunction with consulting, i _a, i _bWith i _cBe respectively the ideal current waveform that is fed to node A, B, C among Fig. 1, e _a, e _bWith e _cBe respectively the back electromotive force on the stator coil 11～13, T _eIt then is the commentaries on classics distance of motor.By among Fig. 2 as can be seen, if under optimal situation, should be at back electromotive force e _a, e _bWith e _cCross over 0 voltage (, being referred to as zero crossing point), 30 degree phase places afterwards, supply stator coil 11～13 current i with technical term _a, i _bWith i _c, make commentaries on classics apart from T _eKeep fixing.In other words, so long as can detect back electromotive force e _a, e _bWith e _cZero crossover point, the opportunity that is fit to supply of current just can be known, also the switching time of control switch S201～S206 that just can be suitable in the relative position of just knowing motor rotor.Yet, back electromotive force e _a, e _bWith e _cCan't directly measure and obtain.

Previously, the someone utilizes the node that no current flows through among bleeder circuit and filter measurement node A, B, the C, and to the PWM voltage filter of above-mentioned node with acquisition back electromotive force e _a, e _bWith e _cInformation, thereby detected zero crossover point.Yet, utilize the mode of bleeder circuit will make the signal attenuation that is captured; In addition,, make the detecting of zero crossover point be inaccurate, further cause the motor commutation inaccurate owing to filter circuit has different phase delay soon and in slow at motor rotary speed.

Below patent [1]～[10] be respectively under the situation of forefathers to no Hall element, by detecting zero crossover point with the sensing motor rotor and control some patents of revolution:

[1]J.M.Bourgeois，J.M.Charreton，P.Guillemin，and?B.Maurice，“Control?of?a?brushless?motor，”US?Patent，US?5859520，STM，Jan.12?1999.

[2]J.Shao，D.C.Nolan，K.A.Haughton，and?T.L.Hopkins，“Circuitfor?improved?back?EMF?detection，”US?Patent，US?6633145，STM，Oct.14?2003.

[3]E.C.Lee，“BEMF?crossing?detection?in?PWM?mode?operation?forsensorless?motor?control?application，”US?Patent，US?5789895，STM，Aug.4?1998.

[4]R.Sakti?and?K.K.Chow，“BEMF?zero-crossing?detection?systemof?a?multiple-phase?motor，”US?Patent，US?5909095，STM，Jun.11999.

[5]P.Menegoli，“Circuit?for?improving?back-EMF?detection?inpulse-width?modulation?mode，”US?Patent，US?5866998，STM，Feb.21999.

[6]G.Maiocchi?and?M.Viti，“Reconstruction?of?BEMF?signals?forsynchronizing?the?driving?of?brushless?sensorless?motors?by?meansof?predefined?driving?signals，”US?Patent，US5838128，STM，Nov.171998.

[7]S.W.Cameron，“Method?and?apparatus?for?resynchronizing?amoving?rotor?of?a?polyphase?DC?motor，”US?Patent，US?5172036，STM，Dec.15?1992.

[8]W.S.Gontowski，“Sensorless?motor?driver?with?BEMF?maskextender，”US?Patent，US?6504328，STM，Jan.7?2003.

[9]Q.Jiang?and?C.Bi，“Method?to?detect?the?true?zero-crossingpoints?of?the?phase?back?EMF?for?sensorless?control?of?brushless?DCmotors，”US?Patent，US?6879124，Apr.12?2005.

[10]B.Maurice?and?J.M.Charreton，“Control?of?a?brushlessmotor，”US?Patent，US?6577085，STM，Jun.10?2003.

The defective that the below technical problem that the above-mentioned patent of simple declaration [1]～[10] are solved respectively, and explanation patent [1]～[10] exist.Seeing also shown in Figure 4ly, is the circuit diagram that illustrates known patent [1].As shown in Figure 4, patent [1] is to utilize clamp circuit (clamping circuit) 40 to be couple to A, B, the C node of the stator coil of motor, and electric current by A to C stream and on during bridge switch S401 closed condition, the voltage of estimation Node B, however this kind method certainly will need the restriction of minimum switch shut-in time.In the patent [2], the voltage drop that provides the matrix diode of an offset compensation circuit with compensating switch (diode is a diode, below all be called diode) to be caused.By this kind compensating circuit, the asymmetry of zero-crossing signal has obtained improvement.Yet the pressure drop of matrix diode is the forward current that flows through along with it and changing.Disclosed fixed voltage Vcon compensation may cause translate phase error (commutation phase error) as patent [2] in utilization.In addition, its disclosed circuit only can be used in detecting back electromotive force under the PWM-off state, just can't detect under the state of PWM-on.

Hand over the accuracy of detecting more in order to promote zero more, in the patent of patent [3]～[6], disclosed SOME METHODS and circuit.In patent [3], disclosed a kind of in order to the comparison circuit that replaces pwm signal and drive high side electric crystal to conducting state up to detecting zero crossover point.Yet the commentaries on classics of Current Regulation power and generation just can be affected owing to pwm signal is substituted apart from ripple.Patent [4] is to disclose a sample-and-hold circuit, in order to the back electromotive force of taking a sample under the state of PWM-on, and at the state of PWM-off, keeps the voltage of being taken a sample by an electric capacity.During PWM-off, this electric capacity is that therefore the voltage on electric capacity comes down to the back electromotive force rising/decline along with motor by current source discharge.Yet this electric capacity and current source must adjust according to the parameter of motor.Patent [5] has been revised the topology of converter, has increased by a power electric crystal between low side switch electric crystal and ground connection more.Yet this kind topology also is not suitable for general application.

The disclosed mode of patent [6] is to utilize the measures of dispersion of a plurality of different back electromotive force of estimation to reach the single back electromotive force of generation estimation, improves signal noise ratio to reach.Yet this patent [6] certainly will be appointed the electric current of two-phase at sensing under the current-mode, or sensing is appointed the voltage difference of two-phase under voltage mode.The disclosed method of patent [7] is to utilize time difference of the preceding zero crossover point of being estimated for twice to estimate the zero crossover point of next time.Yet this kind method can not be applied on bigger motor of velocity variations or the asymmetric motor.

Patent [8] discloses a kind of in order to measure the polarity detector of back electromotive force; Patent [9] discloses in order to detect the edge detection device of zero crossover point.This two patent [8] is in order to solve during the matrix diode current flow of diverter switch, can't detect the problem of back electromotive force with [9].Yet at certain some operational circumstances, particularly under the situation of heavy duty, the detecting point of above-mentioned two back electromotive force that patent is detected is handed over when giving birth to all the more zero, and its signal polarity may not can change.See also the experimental waveform of Fig. 5, waveform 501 is the voltage of A node, and waveform 502 is electric currents of A node, and 503 of waveforms are the detecting waveforms of patent [8], [9] patent, 504,505,506 be respectively take place zero hand over more the time detecting waveform 503 change in voltage.In the waveform 503 of Fig. 5, can see, corresponding 504 and 506 time point, waveform 503 detect zero crossover point and make voltage is electronegative potential, but corresponding 505 time point, but cause detecting less than zero crossover point, make waveform 503 keep high potential because load is excessive.Above-mentionedly can't detect zero crossover point if utilize the technology of above-mentioned patent [8], [9] to cause, cause the motor can't commutation and stop possibly, thereby cause the electric current that backwashes, front stage circuits is burnt.So use the technology of patent [8], [9] if under above-mentioned condition, be breakneck!

Patent [10] provides a kind of storage unit that uses to go to write down the time relationship that zero friendship is given birth to all the more.The major technique feature of this patent [10] is that the longest, the middle and the shortest delay commutation time after giving birth to all the more handed in record zero, and judges when commutation according to this.The rule of this kind commutation is not to utilize zero to hand over back more 30 degree commutation positions, but utilizes the delay of time to come the commutation position.Therefore, the longest, the middle and the shortest delay commutation time that is stored must be done adaptive adjustment according to the rotating speed of motor.Yet, this adjustment not rule go definition the longest with to the short time, so if need utilize this patent, the simplest method is exactly to measure the delay commutation time of motor under different service speeds, and it is stored in the above-mentioned storage unit, will wastes many costs so plant way.

This shows, in above-mentioned existing motor control method, motor control circuit and brushless motor system and the use, obviously still have inconvenience and defective, and demand urgently further being improved.In order to solve the problem of above-mentioned existence, relevant manufacturer there's no one who doesn't or isn't seeks solution painstakingly, but do not see always that for a long time suitable design finished by development, and common product and method do not have appropriate structure and method to address the above problem, and this obviously is the problem that the anxious desire of relevant dealer solves.Therefore how to found a kind of new motor control circuit and method and brushless motor system, real one of the current important research and development problem that belongs to, also becoming the current industry utmost point needs improved target.

This shows that above-mentioned existing motor control method, motor control circuit and brushless motor system obviously still have inconvenience and defective, and demand urgently further being improved in product structure, control method and use.In order to solve the problem of above-mentioned existence, relevant manufacturer there's no one who doesn't or isn't seeks solution painstakingly, but do not see always that for a long time suitable design finished by development, and common product and method do not have appropriate structure and method to address the above problem, and this obviously is the problem that the anxious desire of relevant dealer solves.How therefore a kind of new motor control circuit and method and brushless motor system are provided, real one of the current important topic that belongs to, also becoming the current industry utmost point needs improved target.

Because the defective that above-mentioned existing motor control method, motor control circuit and brushless motor system exist, the inventor is based on being engaged in this type of product design manufacturing abundant for many years practical experience and professional knowledge, and the utilization of cooperation scientific principle, actively studied innovation, in the hope of founding a kind of new motor control circuit and method and brushless motor system, can improve general existing motor control method, motor control circuit and brushless motor system, make it have more practicality.Through constantly research, design, and after studying sample and improvement repeatedly, create the present invention who has practical value finally.

Summary of the invention

The objective of the invention is to, overcome the defective that existing motor control method, motor control circuit and brushless motor system exist, and provide a kind of new motor control circuit and method and brushless motor system, technical problem to be solved is to make it can accomplish the zero crossover point of detecting motor under the PWM-on state, the further commutation of control motor, in embodiment further, zero crossover point of detecting motor is very suitable for practicality with minimizing commutation error in the time of can also cooperating PWM-off.

The object of the invention to solve the technical problems realizes by the following technical solutions.In order to reach the foregoing invention purpose, the present invention proposes a kind of motor control method, and the method comprises following step: a motor is provided, and this motor comprises at least 3 phase stator coils, each stator coil comprises one first end and one second end, and first end of above-mentioned stator coil couples common node; One first supply voltage is provided; Provide at least 3 to go up bridge switch, couple respectively between second end and first supply voltage of above-mentioned 3 phase stator coils; At least 3 following bridge switch are provided, couple respectively between second end and impedor first end of above-mentioned 3 phase stator coils, wherein impedor second termination, one second source voltage, and this second source voltage is less than this first supply voltage; In the said stator coil, no current is by first stator coil, and during the following bridge switch conducting that the last bridge switch conducting that second end of second stator coil is coupled, second end of the 3rd stator coil are coupled: the voltage of second end of detecting first stator coil is as first given voltage; The voltage drop (Voltage Drop) at detecting impedance component two ends is as second given voltage; And utilize first supply voltage, first given voltage and second given voltage estimation, zero crossover point, with the control motor.

According to the described motor control method of preferred embodiment of the present invention, if definition first voltage source is V _Dd, first given voltage is V _Open, second given voltage is V _Idc, then above-mentioned steps " utilize this first supply voltage, this first given voltage and this second given voltage with judge whether take place this first zero hand over get over " comprise the following steps: V _Open, V _Dd, V _IdcConvergent-divergent one special ratios obtains v respectively _Open, v _Dd, v _IdcWith v _Open, v _Dd, v _IdcAccording to 2: 1: 1 mixed was a back electromotive force signal; And when the back electromotive force signal greater than a predetermined voltage, judge that then the first zero friendships are living all the more.

At the described motor control method of preferred embodiment of the present invention, except that above-mentioned steps, also comprise the following steps: in the said stator coil, no current is by first stator coil, and the last bridge switch that second end of working as second stator coil is coupled ends, during following bridge switch conducting that second end of the 3rd stator coil is coupled, first given voltage is made a scale operation to judge that whether taking place one the second zero hands over and get over.Wherein step " with this first given voltage do a scale operation with judge whether take place this second zero hand over get over " comprise the following steps: in a specific embodiment the first given voltage convergent-divergent, one special ratios is obtained a back electromotive force signal; And when the back electromotive force signal greater than a predetermined voltage, judge that then the second zero friendships are living all the more.In another specific embodiment, comprise the following steps: also except above-mentioned step to judge the first zero hand over more more how the person is taken place earlier with the second zero friendships; And hand over more and to hand over more with the second zero when the first zero, take place one specific zero earlier and hand over when getting over, then control the motor commutation more with this specific zero friendship.

The object of the invention to solve the technical problems also realizes by the following technical solutions.In order to reach the foregoing invention purpose, the present invention proposes in order to control a kind of motor control circuit of a motor, said motor comprises at least 3 phase stator coils, each stator coil comprises one first end and one second end, first end of said stator coil couples a common node, second end of said stator coil couples at least one bridge switch and at least one bridge switch down gone up, bridge switch is respectively in order to determine whether a supply voltage is supplied to the said stator coil on each, bridge switch couples by an impedance component and connects voltage altogether under each, and this motor control circuit comprises: select circuit, zero hands over detecting unit and control circuit more.Select circuit to couple second end of said stator coil, when first phase coil and second phase coil second end coupled go up or down bridge switch switch according to the pulse wave width modulation signal, with the voltage response of second end of third phase coil to the output of selecting circuit as one first voltage; Zero hands over more, and detecting unit couples the output of selecting circuit, the last bridge switch conducting that is coupled when second end of first phase coil, when following bridge switch ends, supply voltage composition and the impedor cross-pressure composition removed in first voltage obtain one first anti-electric voltage, relatively first anti-electric voltage and one first reference voltage are exported one the first zero friendship and are got over decision signal; Control circuit hands over decision signal judgement zero more to hand over the time of giving birth to all the more with the control motor according to zero.

According to the described motor control circuit of preferred embodiment of the present invention, above-mentioned zero hands over more detecting unit to comprise that the first zero hand over more circuit for detecting and the second zero to hand over circuit for detecting more.The first zero last bridge switch conductings of handing over circuit for detecting more to be coupled in order to second end when first phase coil, when following bridge switch ends, supply voltage composition and the impedor cross-pressure removed in first voltage obtain first anti-electric voltage, relatively first anti-electric voltage and first reference voltage, decision signal is got in output the first zero friendships; The second zero hand over last bridge switch that circuit for detecting more coupled in order to second end when first phase coil by the time, as second anti-electric voltage, relatively second anti-electric voltage and second reference voltage are exported one the second zero friendship and are got over decision signal with first voltage.

According to the described motor control circuit of preferred embodiment of the present invention, above-mentioned selection circuit comprises that one first ratio dwindles circuit, dwindles a predetermined ratio in order to the voltage with second end of the 3rd stator coil and obtains first voltage.And the first zero hand over more circuit for detecting to comprise that second ratio dwindles circuit and analogy subtraction circuit.Second ratio is dwindled circuit supply voltage is dwindled predetermined ratio as one second voltage, and impedor cross-pressure is dwindled predetermined ratio as a tertiary voltage.The analogy subtraction circuit is in order to according to 2: 1: 1 proportionate relationship, first voltage is deducted second voltage and tertiary voltage after, export first anti-electric voltage.

According to the described motor control circuit of preferred embodiment of the present invention, above-mentioned the first zero hand over more, and circuit for detecting also comprises: generating circuit from reference voltage, comparison circuit and sample circuit.Generating circuit from reference voltage is in order to produce first reference voltage, the wherein last bridge switch conducting that is coupled when second end of first phase coil, following bridge switch ends, the following bridge switch conducting of second phase coil, and the third phase coil still has electric current when first end flows to second end, setting first reference voltage is the accurate position of a high voltage, when the voltage quasi position of first anti-electric voltage is lower than the accurate position of high voltage, setting first reference voltage is the accurate position of an intermediate voltage, when the voltage quasi position of first anti-electric voltage was higher than the accurate position of intermediate voltage, setting first reference voltage was the accurate position of a low voltage.Comparison circuit comprises positive input terminal, negative input end and output, and its positive input terminal receives first anti-electric voltage, and its negative input end receives first reference voltage, and its output is exported a comparative voltage.Sample circuit couples the output of comparison circuit, receives comparative voltage, and during in order to bridge switch conducting on first stator coil, the sampling comparative voltage is handed over and got over decision signal to obtain the first zero.

The object of the invention to solve the technical problems realizes by the following technical solutions again.In order to reach the foregoing invention purpose, the present invention proposes a kind of brushless motor system, and it comprises: motor, a plurality of bridge switch, a plurality of bridge switch down, impedance component, selection circuit, zero friendship detecting unit and control circuit more gone up.This motor comprises at least 3 phase stator coils, and each stator coil comprises first end and second end, and first end of said stator coil couples common node.At least couple one between second end of each stator coil and the supply voltage and go up bridge switch, bridge switch is respectively in order to determine whether a supply voltage is supplied to the said stator coil on each.Impedor first end couples and connects voltage altogether.At least couple a following bridge switch between second end of each stator coil and impedor second end.Select circuit to couple second end of said stator coil, when first phase coil second end coupled go up or down bridge switch switch according to the pulse wave width modulation signal, and during the following bridge switch conducting of second phase coil, with the voltage response of second end of third phase coil to the output of selecting circuit as first voltage.Zero hands over more, and detecting unit couples the output of selecting circuit.The last bridge switch conducting that is coupled when second end of first phase coil, when following bridge switch ends, zero supply voltage composition and the impedor cross-pressure of handing over detecting unit more to remove in first voltage obtains one first anti-electric voltage, and relatively this first anti-electric voltage and one first reference voltage, export one the first zero according to this and hand over decision signal more.Control circuit hands over decision signal judgement zero more to hand over the time of giving birth to all the more with the control motor according to zero.

According to the described brushless motor system of preferred embodiment of the present invention, above-mentioned zero hands over more detecting unit to comprise that the first zero hand over more circuit for detecting and the second zero to hand over circuit for detecting more.The first zero last bridge switch conductings of handing over circuit for detecting more to be coupled in order to second end when first phase coil, when following bridge switch ends, supply voltage composition and the impedor cross-pressure removed in first voltage obtain first anti-electric voltage, relatively first anti-electric voltage and first reference voltage, decision signal is got in output the first zero friendships.The second zero hand over last bridge switch that circuit for detecting more coupled in order to second end when first phase coil by the time, as second anti-electric voltage, relatively second anti-electric voltage and second reference voltage are exported one the second zero friendship and are got over decision signal with first voltage.

According to the described brushless motor system of preferred embodiment of the present invention, above-mentioned selection circuit comprises that one first ratio dwindles circuit, dwindles a predetermined ratio in order to the voltage with second end of the 3rd stator coil and obtains first voltage.And the first zero hand over more circuit for detecting to comprise that second ratio dwindles circuit and analogy subtraction circuit.Second ratio is dwindled circuit supply voltage is dwindled predetermined ratio as one second voltage, and impedor cross-pressure is dwindled predetermined ratio as a tertiary voltage.The analogy subtraction circuit is in order to according to 2: 1: 1 proportionate relationship, first voltage is deducted second voltage and tertiary voltage after, export first anti-electric voltage.

According to the described brushless motor system of preferred embodiment of the present invention, above-mentioned the first zero hand over more, and circuit for detecting also comprises: generating circuit from reference voltage, comparison circuit and sample circuit.Generating circuit from reference voltage is in order to produce first reference voltage, the wherein last bridge switch conducting that is coupled when second end of first phase coil, following bridge switch ends, the following bridge switch conducting of second phase coil, and the third phase coil still has electric current when first end flows to second end, setting first reference voltage is the accurate position of a high voltage, when the voltage quasi position of first anti-electric voltage is lower than the accurate position of high voltage, setting first reference voltage is the accurate position of an intermediate voltage, when the voltage quasi position of first anti-electric voltage was higher than the accurate position of intermediate voltage, setting first reference voltage was the accurate position of a low voltage.Comparison circuit comprises positive input terminal, negative input end and output, and its positive input terminal receives first anti-electric voltage, and its negative input end receives first reference voltage, and its output is exported a comparative voltage.Sample circuit couples the output of comparison circuit, receives comparative voltage, and during in order to bridge switch conducting on first stator coil, the sampling comparative voltage is handed over and got over decision signal to obtain the first zero.

The present invention compared with prior art has tangible advantage and beneficial effect.By technique scheme, motor control circuit of the present invention and method and brushless motor system have following advantage at least: the present invention is because adopt in above-mentioned three-phase coil, when electric current flows to second end of the 3rd certain coil by second end of second certain coil, and no current is by first certain coil, just the voltage of second end of detecting first coil is as first given voltage, and the voltage drop of detecting direct current sensing resistor is as one second given voltage.Next the direct voltage that utilizes first given voltage, second given voltage and be supplied to motor is to estimate zero crossover point with the control motor.Therefore do not need as the use filter circuit as the existing known techniques problem that yet can not cause detecting zero to hand over looks position all the more to postpone.And the circuit of the embodiment of the invention can detect zero crossover point by the stator coil of the non-active state of detecting (non-excited), no matter is PWM-on state or PWM-off state.

In sum, the present invention is about a kind of motor control circuit and method and brushless motor system, be a kind of motor control method, circuit and brushless motor, this motor comprises three-phase coil, first end of each coil couples common node, the method comprises: in above-mentioned three-phase coil, no current is by first certain coil, and when electric current flowed to second end of the 3rd certain coil by second end of second certain coil: the voltage of second end of detecting first coil was as first given voltage; The voltage drop of detecting direct current sensing resistor is as second given voltage; Direct voltage estimation zero crossover point that utilizes first given voltage, second given voltage and be supplied to motor is with the control motor.The present invention can accomplish the zero crossover point of detecting motor under the PWM-on state, further controls the commutation of motor, and in embodiment further, the zero crossover point of detecting motor in the time of can also cooperating PWM-off and can reduce the commutation error is very suitable for practicality.The present invention has above-mentioned plurality of advantages and practical value, no matter it all has bigger improvement on product structure, control method or function, obvious improvement is arranged technically, and produced handy and practical effect, and more existing motor control method, motor control circuit and brushless motor system have the outstanding effect of enhancement, thereby being suitable for practicality more, and having the extensive value of industry, really is a new and innovative, progressive, practical new design.

Above-mentioned explanation only is the general introduction of technical solution of the present invention, for can clearer understanding technological means of the present invention, and can be implemented according to the content of specification, and for above-mentioned and other purposes, feature and advantage of the present invention can be become apparent, below especially exemplified by preferred embodiment, and conjunction with figs., be described in detail as follows.

Description of drawings

Fig. 1 is the structural representation that illustrates typical brushless motor.

Fig. 2 is the equivalent circuit diagram that illustrates known Fig. 1 motor drive circuit 18 and brushless motor.

Fig. 3 is the oscillogram of the back electromotive force that produced when illustrating the ideal current waveform of known Fig. 1 three-phase motor and motor rotation.

Fig. 4 is the circuit diagram that illustrates known patent [1].

Fig. 5 is the experimental waveform figure that illustrates known patent [8], [9].

Fig. 6 illustrates the embodiment of the invention, and under the situation that high side is switched, conduction phase is transformed into the three-phase conduction period of B+C-and the circuit analysis figure of PWM-on by A+C-.

Fig. 7 illustrates the embodiment of the invention, and under the situation that high side is switched, conduction phase is transformed into the three-phase conduction period of B+C-and the circuit analysis figure of PWM-off by A+C-.

Fig. 8 and Fig. 9 illustrate the voltage of high side handover scheme of the embodiment of the invention and the analog result figure of current response.

Figure 10 is the conduction phase B+C-that illustrates the embodiment of the invention in three-phase conduction period, the circuit analysis figure of the complementary PWM-on that switches.

Figure 11 is the conduction phase B+C-that illustrates the embodiment of the invention in three-phase conduction period, the circuit analysis figure of the complementary PWM-off that switches.

Figure 12 and Figure 13 illustrate the voltage of complementary handover scheme of the embodiment of the invention and the analog result figure of current response.

Figure 14 is the conduction phase B+C-that illustrates the embodiment of the invention in two-phase conduction period, and high side is switched the circuit analysis figure with the complementary PWM-on that switches.

Figure 15 is the conduction phase B+C-that illustrates the embodiment of the invention in two-phase conduction period, the circuit analysis figure of the PWM-off that high side is switched.

Figure 16 is the conduction phase B+C-that illustrates the embodiment of the invention in two-phase conduction period, the circuit analysis figure of the complementary PWM-off that switches.

Figure 17 is the circuit block diagram that illustrates the brushless motor system of the embodiment of the invention.

Figure 18 is that the motor control circuit M170 that illustrates the embodiment of the invention implements circuit diagram more in detail.

Figure 19 is the experimental waveform that illustrates embodiment of the invention Figure 18 circuit utilization examination ripple device.

Figure 20 is the waveform schematic diagram that illustrates embodiment of the invention motor control circuit.

Figure 21 is the flow chart that illustrates the motor control method of the embodiment of the invention.

Figure 22 is that the commutation index signal Ck and zero that illustrates the control circuit of the embodiment of the invention hands over index signal Z more _kOscillogram.

11～13: stator coil 14: rotor

15～17: Hall element 18: motor drive circuit

A171, B171, C171: stator coil A, B, C: node

S201～S206: switch electric crystal L _s: equivalent inductance, with

R _s: equivalent series resistance E _A～E _C: the back-emf voltage source

i _a～i _c: the electric current of stator coil 11～13

T _e: the commentaries on classics of motor is apart from 40: clamp circuit

S401: the voltage waveform of going up bridge switch 501:A node

The current waveform 503:[8 of 502:A node], the detecting waveform of [9] patent

504,505,506: take place zero hand over more the time detecting waveform 503 change in voltage

M170: motor control circuit S171～S173: go up bridge switch

S174～S176: following bridge switch R _DC: impedance component

M171: brushless motor 1701: select circuit

Hand over more detecting unit 1703 at 1702: zero: control circuit

TS: the output V that selects circuit 1701 _s: the output end voltage of selecting circuit 1701

V _Emf-on: the first anti-electric voltage V _Idc: impedance component R _DCCross-pressure

Z _On: the first zero hand over more decision signal to hand in 181: the first zero gets over circuit for detecting

Friendship in 182: the second zero is circuit for detecting V more _Ref1: first reference voltage

V _Emf-off: the second anti-electric voltage V _Ref2: second reference voltage

Z _Off: the second zero hand over decision signal 1801 more: ratio is dwindled circuit

v _a, v _b, v _c: voltage R1, the R2 of stator coil: resistance

B181～B184: buffer circuit S181: subtraction circuit

V181: generating circuit from reference voltage CP181, CP182: comparison circuit

V _Se10, V _Se11: select circuit control voltage T191～T195: Figure 19 waveform label time point

V _Pwm: pwm signal f _Ss: sampled signal

Z _k: zero hands over index signal T201～T204 more: Figure 20 waveform label time point

S2101～S2117: the step of the embodiment of the invention

Embodiment

Reach technological means and the effect that predetermined goal of the invention is taked for further setting forth the present invention, below in conjunction with accompanying drawing and preferred embodiment, to motor control circuit and method and its embodiment of brushless motor system, structure, method, step, feature and the effect thereof that foundation the present invention proposes, describe in detail as after.

In order to solve the problem of existing known techniques, the present invention proposes rotor-position method for detecting, motor controller and brushless motor.Before explanation the method and device, earlier to performing an analysis with the closely bound up back electromotive force of motor position.Do mathematics and circuit analysis below just as an example, and to it with the three-phase motor of Fig. 2.

At first, suppose the equivalent series resistance R of stator coil 11～13 _sBe a fixed value, and the inductance sensibility reciprocal L of hypothesis stator coil 11～13 _sEquate.Therefore, the voltage v of node A, the B of this three-phase motor, C _An, v _Bn, v _CnCan be expressed as follows:

$\left[\begin{array}{c}{v}_{\mathrm{an}}\\ v_{\mathrm{bn}}\\ v_{\mathrm{cn}}\end{array}\right]=\left[\begin{array}{ccc}{R}_s& 0& 0\\ 0& {\mathrm{<figure-callout\; id="0"\; label="R\; s"\; filenames="A20071000048500331.png"\; state="\{\{state\}\}">R</figure-callout>}}_s& 0\\ 0& 0& R_s\end{array}\right]\left[\begin{array}{c}{i}_a\\ i_b\\ i_c\end{array}\right]+\left[\begin{array}{ccc}{L}_s& 0& 0\\ 0& L_s& 0\\ 0& 0& L_s\end{array}\right]\left[\begin{array}{c}\frac{{\mathrm{di}}_a}{\mathrm{dt}}\\ \frac{{\mathrm{di}}_b}{\mathrm{dt}}\\ \frac{{\mathrm{di}}_c}{\mathrm{dt}}\end{array}\right]+\left[\begin{array}{c}{e}_a\\ e_b\\ e_c\end{array}\right]$

Next, (supplemental instruction: A+C-refers to electric current and flows to the C node by the A node to suppose to be transformed into B+C-by A+C-by conduction phase, B+C-refers to electric current and flows to the C node by the B node) time, the A node just is in non-active state (non-excited) this moment, just can be used for the estimation of back electromotive force.But, because stator coil 11 has inductance L _sCharacteristic, its electric current must be continuously, finishes so discharge as yet at the inductance of stator coil 11, just current i _aBefore disappearing as yet, the terminal voltage of node A will be by the matrix diode of S202 (body diode) strangulation near the accurate position of ground connection.In other words, in the inductance L of stator coil 11 _sDischarge is not finished as yet, and node A also cannot be used for the estimation of back electromotive force.Therefore, if need to use node A to do the estimation of back electromotive force, at first must be divided into two time sections.First time section is three-phase conduction period, and second time section is two-phase conduction period.So-called three-phase conduction period refers to during this period, and three-phase coil 11～13 all has electric current.So-called two-phase conduction period refers to during this period, and three-phase coil 11～13 has only two-phase that electric current is arranged.

Before the explanation that performs an analysis, at first define switch S 201, S203, S205 are high-side switch (high-side switch), switch S 202, S204, S206 are low side switch (low-sideswitch).And when conduction phase A+C-: the switching high-side switch S201 of repetition controls the electric current of A node to the C node, just is referred to as high side to switch (high-side switching); The switching low side switch S202 that repeats controls the electric current of A node to the C node, just is referred to as downside and switches (low-sideswitching); The switching high and low side switch S 201 and the S202 that repeat control the electric current of A node to the C node, just are referred to as complementary switch (complementary switching).In addition, when high side switching or complementary the switching, the high-side switch conducting is called PWM-on, and high-side switch is by being referred to as PWM-off.Below just begin to do the analysis of three-phase conduction period and two-phase conduction period with above-mentioned hypothesis.

Analyze three-phase conduction period, the situation that high side is switched at first earlier.Seeing also shown in Figure 6ly, is the conduction phase B+C-that illustrates the embodiment of the invention in three-phase conduction period, and high side switches in the circuit analysis figure of PWM-on state.Please refer to Fig. 6, when PWM-on, current i _bFlow to Node B by last bridge switch S203, flow to node C again; Current i _aMatrix diode by following bridge switch S202 flows to node A, flows to node C again.The node voltage v of node A, B, C _a, v _b, v _cCan be expressed as follows respectively:

v _a＝i _dcR _dc-V _d

v _b＝V _dc-i _bR _pon

v _c＝i _dcR _dc-i _cR _non

i _dc＝i _b

Wherein, V _dBe the cut-in voltage (cut-in voltage) of matrix diode, R _PonBe the conducting resistance of last bridge switch S201, S203, S205, R _NonConducting resistance for following bridge switch S202, S204, S206.

Seeing also shown in Figure 7ly, is the conduction phase B+C-that illustrates the embodiment of the invention in three-phase conduction period, and high side switches in the circuit analysis figure of PWM-off state.Please refer to shown in Figure 7, when PWM-off, current i _bFlow to Node B by following bridge switch S204, flow to node C again; Current i _aMatrix diode by following bridge switch S202 flows to node A, flows to node C again.The node voltage v of this node A, B, C _a, v _b, v _cCan be expressed as follows respectively:

v _a＝-V _d

v _b＝-V _d

v _c＝-i _cR _non

i _dc＝0

Seeing also Fig. 8 and shown in Figure 9, is to illustrate the voltage of high side handover scheme of the embodiment of the invention and the analog result figure of current response.Please refer to Fig. 8 and Fig. 9, wherein, the cut-in voltage of the matrix diode of switch S 201～S206 is set at 1V, resistance R _DcBe set at 0.05 Ω, the conducting resistance Rpon of switch S 201～S206 and Rnon all are set at 0.1 Ω.So voltage and electric current on Fig. 8 and Fig. 9 just can utilize above-mentioned formula to estimate out.

Next, analyze three-phase conduction period, complementary situation about switching.Seeing also shown in Figure 10ly, is the conduction phase B+C-that illustrates the embodiment of the invention in three-phase conduction period, the circuit analysis figure of the complementary PWM-on that switches.Please refer to Figure 10, according to Figure 10, the terminal voltage v of node A, B, C _a, v _b, v _cCan be expressed as follows:

v _a＝i _dcR _dc-V _d

v _b＝V _dc-i _bR _pon

v _c＝i _dcR _dc-i _cR _non

i _dc＝i _b

See also shown in Figure 11, be illustrate into the conduction phase B+C-of the embodiment of the invention in three-phase conduction period, the circuit analysis figure of the complementary PWM-off that switches.Please refer to Figure 11, according to Figure 11, the terminal voltage v of node A, B, C _a, v _b, v _cCan be expressed as follows:

v _a＝-V _d

v _b＝-i _bR _non

v _c＝-i _cR _non

i _dc＝0

Seeing also Figure 12 and shown in Figure 13, is to illustrate the voltage of complementary handover scheme of the embodiment of the invention and the analog result figure of current response.Just can reflect the above-mentioned analysis of card by Figure 12 and Figure 13.

Next, begin to analyze two-phase conduction period, high side is switched and complementary situation about switching.Seeing also shown in Figure 14ly, is the conduction phase B+C-that illustrates the embodiment of the invention in two-phase conduction period, and high side is switched the circuit analysis figure with the complementary PWM-on that switches.Please refer to Figure 14, according to Figure 14, the terminal voltage v of this node A, B, C _a, v _b, v _cCan be expressed as follows:

v _a＝e _a+v _n

v _b＝V _dc-i _bR _pon

v _c＝i _dcR _dc-i _cR _non

i _dc＝i _b

Seeing also shown in Figure 15ly, is the conduction phase B+C-that illustrates the embodiment of the invention in two-phase conduction period, the circuit analysis figure of the PWM-off that high side is switched.Please refer to shown in Figure 15, according to Figure 15, the terminal voltage v of node A, B, C _a, v _b, v _cCan be expressed as follows:

v _a＝e _a+v _n

v _b＝-V _d

v _c＝-i _cR _non

i _dc＝0

Seeing also shown in Figure 16ly, is the conduction phase B+C-that illustrates the embodiment of the invention in two-phase conduction period, the circuit analysis figure of the complementary PWM-off that switches.Please refer to Figure 16, according to Figure 16, the terminal voltage v of this node A, B, C _a, v _b, v _cCan be expressed as follows:

v _a＝e _a+v _n

v _b＝-i _bR _non

v _c＝-i _cR _non

i _dc＝0

$v_n=\frac{1}{3}(v_a+v_b+v_c)+\frac{1}{3}{e}_{\mathrm{sum}}$

Wherein, v _nThe voltage of the node that couples jointly for three-phase coil, e _SumSum total for back electromotive force.Next, comprehensive foregoing circuit mathematical analysis can obtain following result.

B+C-two is conducted and the PWM-on state, and high side is switched with complementary and switched:

$v_a=\frac{3}{2}{e}_a+\frac{1}{2}{V}_{\mathrm{dc}}-\frac{1}{2}(i_b{R}_{\mathrm{pon}}+i_c{R}_{\mathrm{non}}-i_b{R}_{\mathrm{dc}})+\frac{1}{2}{e}_{\mathrm{sum}}$

$e_a=\frac{2}{3}{v}_a-\frac{1}{3}{V}_{\mathrm{dc}}+\frac{1}{3}(i_b{R}_{\mathrm{pon}}+i_c{R}_{\mathrm{non}}-i_b{R}_{\mathrm{dc}})-\frac{1}{3}{e}_{\mathrm{sum}}$

B+C-two is conducted and the PWM-off state, and high side is switched:

$v_a=\frac{3}{2}{e}_a-\frac{1}{2}(V_d+i_c{R}_{\mathrm{non}})+\frac{1}{2}{e}_{\mathrm{sum}}$

$e_a=\frac{2}{3}{v}_a+\frac{1}{3}(V_d+i_c{R}_{\mathrm{non}})-\frac{1}{3}{e}_{\mathrm{sum}}$

B+C-two is conducted and the PWM-off state, the complementary switching:

$v_a=\frac{3}{2}{e}_a+\frac{1}{2}{e}_{\mathrm{sum}}$

$e_a=\frac{2}{3}{v}_a-\frac{1}{3}{e}_{\mathrm{sum}}$

So as can be seen by above-mentioned analysis, in BC two-phase conduction period, no matter be under the situation of PWM-on or PWM-off, can be by the voltage v of this node A _aObtain the back electromotive force e of A phase _aFurther, so long as appoint the stator coil conducting of two-phase, and the stator coil no current of another phase, the node that just can utilize above-mentioned no current stator coil to couple switch detects back electromotive force.Therefore above-mentioned two-phase conduction period, the mathematical expression of the back electromotive force that the no current stator coil is sensed can be rewritten as follows:

PWM-on state, high side switch with complementary and switch:

$e_{\mathrm{open}}=\frac{2}{3}{v}_{\mathrm{open}}-\frac{1}{3}{V}_{\mathrm{dc}}+\frac{1}{3}(i_{\mathrm{on}}{R}_{\mathrm{pon}}+i_{\mathrm{off}}{R}_{\mathrm{non}}-i_{\mathrm{on}}{R}_{\mathrm{dc}})-\frac{1}{3}{e}_{\mathrm{sum}}........\left(\mathrm{EQ}01\right)$

The PWM-off state, high side is switched:

$e_{\mathrm{open}}=\frac{2}{3}{v}_{\mathrm{open}}+\frac{1}{3}(V_d+i_{\mathrm{off}}{R}_{\mathrm{non}})-\frac{1}{3}{e}_{\mathrm{sum}}..................\left(\mathrm{EQ}02\right)$

The PWM-off state, the complementary switching:

$e_{\mathrm{open}}=\frac{2}{3}{v}_{\mathrm{open}}-\frac{1}{3}{e}_{\mathrm{sum}}....................................\left(\mathrm{EQ}03\right)$

Wherein, e _OpenBe the back electromotive force that the no current stator coil is sensed, v _OpenBe the terminal voltage of no current stator coil, V _DcBe input direct voltage, V _dBe the cut-in voltage of diode, e _SumSum total for back electromotive force.Though the above-mentioned high side of only deriving is switched with complementary and switched, the technical staff that this area has common knowledge should just can derive the mathematical analysis that downside switches (low-side switching) with aforesaid way by above-mentioned derivation.

Seeing also shown in Figure 17ly, is the circuit block diagram of the brushless motor system of the embodiment of the invention, this circuit comprise the embodiment of the invention motor control circuit M170, go up bridge switch S171～S173, bridge switch S174～S176, impedance component R down _DCAnd brushless motor M171, wherein this brushless motor M171 comprises 3 phase stator coils (stator coil) A171, B171, C171, motor control circuit M170 comprises that selecting circuit 1701, zero to hand over gets over detecting unit 1702 and control circuit 1703 in addition.

At first, selecting circuit 1701 mainly is to couple on A, B on stator coil A171, B171 and the C171, the C node.This select circuit 1701 be in order to the voltage of selecting A, B, three nodes of C one of them, and will above-mentioned selected voltage response to the output TS of selection circuit 1701.Its reaction regular as follows: when the A node coupled on, following bridge switch just is being subjected to PWM control, and during the following bridge switch conducting that the C node couples (high side is switched or complementary the switching), or when the C node coupled on, following bridge switch just is being subjected to PWM control, and during the following bridge switch conducting that the A node couples (high side is switched or complementary the switching), or the last bridge switch conducting that is coupled when the A node, and when the following bridge switch that the C node couples just is being subjected to PWM control (downside switching), or the last bridge switch conducting that is coupled when the C node, and when the following bridge switch that the A node couples just is being subjected to PWM control (downside switching), the voltage that then reacts the B node is to the output TS that selects circuit 1701; Same, the upper and lower bridge switch that is coupled when the B node just is being subjected to PWM control, and during the following bridge switch conducting that the C node couples, or the upper and lower bridge switch that is coupled when the C node just is being subjected to PWM control, and during the following bridge switch conducting that the B node couples, the voltage that then reacts the A node is to the output TS that selects circuit 1701; As a same reason, the upper and lower bridge switch that is coupled when the A node just is being subjected to PWM control, and during the following bridge switch conducting that the B node couples, or the upper and lower bridge switch that is coupled when the B node just is being subjected to PWM control, and during the following bridge switch conducting that the A node couples, the voltage that then reacts the C node is to the output TS that selects circuit 1701.In other words, the major function of selection circuit 1701 is reacted the voltage V of the node of non-active state (non-excited) exactly _s

Zero hands over more, and detecting unit 1702 couples the output of selecting circuit 1701, and receives the voltage V of the output of selecting circuit 1701 _sIts 1702 main function will be removed voltage V exactly _sInterior supply voltage V _DcComposition and impedor cross-pressure V _IdcObtain one first an anti-electric voltage V relevant with back electromotive force (back-EMF) _Emf-onCan be at this with reference to above-mentioned derivation result (EQ01), because in PWM-on, if will obtain back electromotive force e _Open, then must continue will be with V _OpenDeduct the V of half ratio _Dc, and deduct the impedance component R of half ratio again _DCCross-pressure V _Idc=i _OnR _DCObtain the first anti-electric voltage V _Emf-onAfterwards, next zero friendship is got over detecting unit 1702 with the first anti-electric voltage V _Emf-onWith the first reference voltage V _Ref1Make comparisons, output the first zero is handed over and is got over decision signal Z _On Next control circuit 1703 is just handed over decision signal Z more according to zero _OnJudge that zero hands over the time of giving birth to all the more to control the switching of above-mentioned upper and lower bridge switch S171～S176, further reach the purpose of control motor.

Above embodiment only narrated the motor system implemented according to spirit of the present invention and the kenel of motor control circuit M170.Just the state of PWM-on estimates that down zero hands over a kind of scheme of giving birth to the time all the more.Because the part of control circuit 1703 has had many different modes to implement according to this before this case application, and this case improved part be not the part of control circuit 1703, so in this embodiment, do not narrate part in detail relevant for control circuit 1703, yet the embodiment in the back will propose a kind of method that zero friendship postpones the control motor commutation of 30 degree phase angles more afterwards of detecting.Next, know usually that in order to allow this area have the knowledgeable more can understand and implement spirit of the present invention, and hand over the accuracy of time point estimation more, below lift several more detailed enforcement circuit and modes again in order to promote zero more.

Seeing also shown in Figure 180ly, is that the motor control circuit M170 that illustrates the embodiment of the invention implements circuit diagram more in detail.Please refer to Figure 18, can be divided into two parts at this motor control circuit M170, first part is that the first zero to hand over more 181, the second parts of circuit for detecting be the second zero to hand over and get over circuit for detecting 182.The first zero hand over more, and circuit for detecting 181 mainly is to use V as above-mentioned under the state of PWM-on _Emf-onWith the first reference voltage V _Ref1Make comparisons, and export the first zero and hand over decision signal Z more _OnThe second zero hand over more, and circuit for detecting 182 mainly is under the state of PWM-off, when just the last bridge switch that is coupled when second end of first phase coil ends, and the voltage V of output that will selection circuit 1701 _sAs the second anti-electric voltage V _Emf-off, compare the second anti-electric voltage V _Emf-offWith the second reference voltage V _Ref2, output the second zero is handed over and is got over decision signal Z _OffIn addition, comprise also that at this embodiment a sample circuit 183 is in order to sampling Z _OnWith Z _Off

Please refer to Figure 18, select circuit 1701 and the first zero hand over more circuit for detecting 181 before the ratio that all couples dwindle circuit 1801, it is to realize with electric resistance partial pressure that the ratio of this embodiment is dwindled circuit.Because the voltage v of stator coil _a, v _b, v _c, supply voltage V _DcAnd impedance component R _DCCross-pressure V _IdcOn the circuit of reality, voltage may surpass above-mentioned selection circuit 1701, first and second zero friendship voltage tolerance level (voltage endurance) of circuit for detecting 181,182 more, though top circuit mathematical analysis is directly to utilize above-mentioned v _a, v _b, v _c, V _DcAnd V _IdcObtain V _Emf-onWith V _Emf-offYet, when withstand voltage, may need a ratio to dwindle circuit 1801 to avoid circuit burnout as if the consideration circuit.So in this embodiment, above-mentioned v _a, v _b, v _c, V _DcAnd V _IdcThe reduced some predetermined ratios of difference.The v of reduced ratio in Figure 18 _a, v _b, v _c, V _DcAnd V _IdcBe expressed as v respectively _As, v _Bs, v _Cs, V _DcsAnd V _Idcs

The first zero hand over more, and circuit for detecting 181 comprises buffer circuit B181～B183, differential amplifier circuit S181, generating circuit from reference voltage V181 and comparison circuit CP181 in this embodiment.The second zero hand over more, and circuit for detecting 182 comprises amplifying circuit B184 and comparison circuit CP182.Above-mentioned all buffer circuit B181～B183 mainly are to voltage V _s, V _DcAnd V _IdcMake buffered, avoid load effect to influence the accuracy of voltage.In ideal conditions, above-mentioned buffer circuit B181～B183 is negligible.Resistance R 1 among the differential amplifier circuit S181 is used for adjusting circuit gain with R2.In theory, when R1 equates with R2, V _Emf-onWill equal V _sDeduct (V _Dcs+ V _Idcs)/2.So V _Emf-onMeeting and e _OpenVery close.That is to say the V among this embodiment _Emf-onCan be considered as a voltage along with the back electromotive force change.If increase the ratio of R2/R1, just can increase the rate of change that resistance electromotive force voltage estimate by institute, can improve comparator output since change in voltage slow cause in short-term affectionately towards disturbed condition (glitch), increase the accuracy that the signal judgement is got in zero friendship.

Next, the anode of comparator receives V _Emf-on, its negative terminal receives the first reference voltage V that generating circuit from reference voltage V181 is exported _Ref1, its output output the first zero is handed over and is got over decision signal Z _OnGenerating circuit from reference voltage V181 passes through V _Se10With V _Se11Voltage decide the first reference voltage V _Ref1Size.In this embodiment, V _Se10With V _Se11Voltage be V _CcWith the two one of earthing potential.By the circuit diagram of the generating circuit from reference voltage V181 of Figure 18 as can be seen, work as V _Se10With V _Se11Voltage all be high potential V _CcThe time, the first reference voltage V _Ref1Will be in higher current potential; Work as V _Se10With V _Se11Voltage when all being ground connection, the first reference voltage V _Ref1Will be in lower current potential; Work as V _Se10With V _Se11Voltage be respectively high potential V _CcAnd during ground connection, the first reference voltage V _Ref1Will be in middle current potential.Below just cooperate experimental waveform explanation V _Se10With V _Se11The decision mechanism of voltage.

Seeing also shown in Figure 19ly, is to illustrate embodiment of the invention Figure 18 circuit to utilize oscillographic experimental waveform.Following several waveform is arranged in Figure 19, is respectively A node voltage v _a, the first anti-electric voltage V _Emf-on, the first reference voltage V _Ref1And the first zero hand over decision signal Z more _OnAbove-mentioned waveform is the waveform of measuring under the situation that BC is conducted.Please refer to Figure 18 and 19, during T191～T192, the S172 of bridge switch up and down, the S175 that couples Node B begins to be subjected to the control of PWM and moves, this moment, electric current was flowed to the node C of C phase coil C171 by the Node B of B phase coil B171, but the stored energy of A phase coil A171 does not also discharge and finishes, and just A phase coil A171 still has electric current to exist.This moment, T191～T192 can't measure back electromotive force from node A, the V of this moment _Se10With V _Se11Voltage all be to be in supply voltage V _Cc

In the T192 time, the energy of A phase coil A171 has been put, and enters the state that BC two is conducted this moment.Can see A node voltage v _aMoment descends, than the original first higher reference voltage V _Ref1For low.The V of this moment _Se10With V _Se11Voltage will change into one high and one low, V for example _Se10Equal supply voltage V _Cc, V _Se11Equal earthed voltage, or V for example _Se10Equal earthed voltage, V _Se11Equal supply voltage V _CcSo first reference voltage V _Ref1Current potential in the middle of will changing into by higher current potential.Note that this improvement first reference voltage V _Ref1Mode because heavy duty time, the voltage v on Figure 19 _aMay be very short during descending.If detecting will take place among Fig. 5 less than the situation of zero crossover point 505 with the way of patent [8], [9].If in the mode of present embodiment, because the time point T191 that begins to detect just is set at high potential with first reference voltage.So present embodiment can solve the problem of patent [8], [9].

In the T193 time, the first anti-electric voltage V _Emf-onSurpass the first reference voltage V again once again _Ref1, just represent that back electromotive force by passing through 0 current potential toward high potential than electronegative potential, the zero friendship is just taken place get over this moment.So V _Se10With V _Se11Voltage will be set to earthed voltage, make the reference voltage V that wins _Ref1Become lower current potential, to begin judging whether the back electromotive force of B or C phase coil zero friendship takes place more.Because oscillographic number of probes is restricted, therefore in this experimental waveform figure, do not demonstrate the node voltage of other phase coils.Next, roughly the same during the operation principles during T194～T195 and the T191～T193 because T194～T195 only is that back electromotive force is to be transferred to than electronegative potential by high potential, so during operation only to terminate in the voltage height opposite, therefore do not repeat them here.

Next, the second zero hand over more that the negative terminal of the comparison circuit CP182 of circuit for detecting 182 receives the second reference voltage V _Ref2, the anode of comparison circuit CP182 couples the output of amplifying circuit B184.Basically, the second reference voltage V _Ref2It can be earthed voltage.Please refer to above-mentioned equation EQ02 and the EQ03 that derives,, and, can see back electromotive force e via proof because the second zero hand over more that circuit for detecting 182 mainly is the variation of the back electromotive force when detecting the PWM-off state _OpenUnder the state of PWM-off, be and V _OpenDirectly related, little with other parameters relationship.So need will select the voltage V of the output of circuit 1701 at this _sMake comparisons with earthed voltage and can know that just zero hands over time of origin point more.

Because among the embodiment of present embodiment compared with top Figure 17, narrated more a PWM-off state down detecting zero hand over more the second zero hand over circuit for detecting 182 more, last sample circuit 183 is respectively at the situation of the PWM-on Z that takes a sample _On, the situation sampling Z of PWM-off _Off, how to decide diverter switch by control circuit 1703 at last.Reason wherein please refer to shown in Figure 20, and Figure 20 is the waveform schematic diagram that illustrates embodiment of the invention motor control circuit.In Figure 20, comprised the output voltage V of selecting circuit _s, pwm signal V _Pwm, the first zero hand over decision signal Z more _On, the second zero hand over decision signal Z more _Off, sampled signal f _SsAnd the zero index signal Z more that hands over _k

At the T201 time point, zero hands over more and just in time takes place, and when just in time occurring in PWM-on, sampled signal f _SsBe sampled to Z _On, hand over index signal Z more this moment zero _kJust can directly move high potential to, expression zero is handed over living all the more.And ensuing T202 time point, sampled signal f _SsBe sampled to Z _Off, because sampled Z _OffAlso be that the zero friendship of expression is living all the more, it is at T201 that origination point is got in still actual zero friendship, so as if only using Z _OnOr only use Z _OffAll might cause the time error of T201 and T202.But, just can revise this class error if use the embodiment of Figure 18.Next, at the T203 time point, sampled signal f _SsBe sampled to Z earlier _Off, expression zero is handed over more and is just in time taken place, and when just in time occurring in PWM-off, so the time zero hand over index signal Z more _kJust can directly move electronegative potential to.And ensuing T204 time point, sampled signal f _SsBe sampled to Z _On, zero hands over index signal Z more _kJust can not change.

Just can see by above-mentioned waveform schematic diagram,, hand over the living all the more time so can estimate zero more accurately because the embodiment of Figure 18 utilizes PWM-on and zero friendship of PWM-off state estimation to get over simultaneously.

In these supplementary notes, the employed circuit of the foregoing description must be supplied voltage V with two power supplys basically _CcWith V _SsIf will change supply voltage into V _CcDuring with earthed voltage, only need the first zero voltages of handing over the subtraction circuit S181 of circuit for detecting 181 more to be exported are added an offset voltage, and cooperate and revise first reference voltage and get final product.And this kind means equally also can be used in the second zero buffer circuits of handing on the circuit for detecting 182 more, and cooperate and revise second reference voltage.Though the circuit of the foregoing description is not exposed among the embodiment, spirit of the present invention should contain the foregoing description.In addition, though above-mentioned sample circuit 183 is to illustrate a square, but this area has the technical staff of common knowledge should be known, at a specific embodiment, the first zero hand over more circuit for detecting 181 and the second zero to hand over more circuit for detecting 182 still can distinguish a built-in sample circuit, respectively in order to the situation of sampling PWM-on and PWM-off.This kind specific embodiment should also be encompassed in the spirit of the present invention.In addition in this embodiment, sampled signal f _SsThere is a non-working time t centre _dSet this non-working time t _dMainly be reference voltage when changing, may cause interference,, avoid zero to hand over and get over misinterpretation so suspend sampling action in a period of time after reference voltage changes.But at other embodiment or in ideal conditions, still can cancel this non-working time t _dSo, do not repeat them here.

At last, providing a kind of in order to hand over index signal Z more zero _kPostpone 30 degree phase angles and afterwards motor is made the execution mode of the control circuit of commutation control.Following mode does not need the above-mentioned patent of picture [10] must use memory body to store the longest, middle and the shortest delay commutation time, only needs to use simple counting circuit just can implement.Seeing also shown in Figure 22ly, is the commutation index signal C that illustrates the control circuit of the embodiment of the invention _kGet over index signal Z with zero friendship _kOscillogram.Ideally, when load is fixed, also fixedly the time, zero hands over index signal Z more to rotating speed _kWill be very stable waveform, so it is postponed 30 degree phase angles as commutation index signal C _kCan be easy to reach.But in fact, motor might not be kept identical rotating speed, and the load of motor is can change, so motor system needs one to hand over zero and to get over index signal Z _kThe method that postpones 30 degree phase angles is done commutation control in order to motor.

See also shown in Figure 22ly, in this embodiment, remove above-mentioned commutation index signal C _kGet over index signal Z with zero friendship _kAlso comprised accumulated value P outward, ₁～P ₄Schematic diagram.Please refer to accumulated value P ₁～P ₄, accumulated value P ₁～P ₄Be in order to hand over index signal Z more zero _k1.5 cycles in, accumulated value decided at the higher level but not officially announced adds up.Please carefully with reference to accumulated value P ₁, at each section period section γ _I1～γ _I3, accumulated value P ₁Slope all different.γ _I1The time section, accumulated value P ₁Slope less, relative, be added to P ₁Value also less.γ _I3The time section, accumulated value P ₁Slope bigger, relative, be added to P ₁Value also bigger.γ _dThe time section then is with accumulated value P ₁The negative value that adds up is up to accumulated value P ₁Become 0, with commutation index signal C _kSwitching state.

Top each section period γ _I1～γ _dPhase difference 60 degree have all been represented.So ideally, commutation index signal C _kShould be at each section period γ _I1～γ _dMiddle switching state.Yet each section period γ in fact _I1～γ _dBe not all to be identical, different because of load or the outside rotating speed of giving sometimes.Yet commutation index signal C _kBefore the time point of switching state and this time point zero handed over index signal Z more _kBe closely bound up, wherein with γ _dThe commutation index signal C of section _k, maximally related is exactly γ _I3Time span, next is only γ _I2Time span, be only γ at last _I1Time span.Because the speed of motor rotary speed and zero is handed over index signal Z more _kResponsibility cycle relevant, the rotating speed of motor is not easy moment and changes in addition.For example motor is at γ _I1～γ _dTime quickens to rotate time span γ _I1Will be longer, time span γ _I3Will be shorter.In theory, time span γ _dWill be than time span γ _I3Be weak point.Therefore at γ _dCommutation index signal C during this time _kWill with γ _I3The most relevant, next γ _I2, be only γ at last _I1

On the way of this embodiment, can utilize the counting circuit of higher-frequency, utilize the work time pulse of this counting circuit, at γ _I1The time section, each clock pulse is with accumulated value P ₁The x (for example 1, weight is lighter) that adds up is at γ _I2The time section, each clock pulse is with accumulated value P ₁The y (for example 2, weight is common) that adds up is at γ _I3The time section, each clock pulse is with accumulated value P ₁The z (for example 3, weight is heavier) that adds up is at γ _dThe time section, each clock pulse is with accumulated value P ₁Add up-m, wherein m=(x+y+z) * 2 (therefore in above-mentioned example, can draw m is 12).As accumulated value P ₁Be reduced at 0 o'clock, then switch commutation index signal C _kState, so just can reach the purpose of 30 degree commutations.

The benefit of the method maximum is exactly the mode that does not need as patent [10], uses memory body, and the foregoing description only needs to remove to count accumulated value P with simple 4 counting circuits ₁～P ₄, just can reach and reach 30 degree are done the commutation processing to motor purpose accurately.Can be described as with few cost and go to reach and the identical purpose of patent [10].In addition, above-mentioned way only is an embodiment, and this area has knows that usually the knowledgeable should know by inference with reference to the foregoing description, if only using two sections to do adds up, can also reach above-mentioned effect, difference only is commutation index signal C _kAccuracy less than the foregoing description height.So the time of adding up is many more, commutation index signal C _kAccurate more.In addition, though the foregoing description is to utilize zero to hand over index signal Z more _kGive an example, but this area has the technical staff of common knowledge, should know after reference the foregoing description, can use Z _OnOr Z _OffAlso can reach identical effect, so the present invention is not as limit.

The way of the embodiment of above-mentioned Figure 22 can reduce following step to represent spirit of the present invention: at first, calculate commutation index signal C _kI before the switching state zero hands over the time more, and wherein this zero hands over more that timing definition comprises following (1) or (2): index signal Z is more handed in (1) zero _kState transfer second state to by first state and hand over index signal Z more to zero _kState transfer time between first state to by second state; (2) zero hand over index signal Z more _kState transfer first state to by second state and hand over index signal Z more to zero _kState transfer time between second state to by first state, wherein k zero hands over more that time representation is T _k, wherein i, k are natural number and 0＜k=＜i.Next, give each zero friendship time one weighted value more, k the zero weighted value of the time of getting over of handing over is expressed as G _kNext, definition is time of delay:

T _d＝(G ₁*T ₁+...+G _k*T _k+...+G _i*T _i)/2*(G ₁+...+G _i)。

At last, the time of delay after the 1st zero is handed over the time of getting over, conversion commutation index signal C _kState.

Though the above embodiments provide a motor control circuit and a motor system, spirit of the present invention should not be only limited in above-mentioned several circuit kenel.So the present invention has also proposed the embodiment of motor control method.Seeing also shown in Figure 21ly, is the flow chart that illustrates the motor control method of the embodiment of the invention.Please refer to Figure 21, motor control method of the present invention may further comprise the steps: at first, one motor is provided, this motor comprises at least 3 phase stator coils, and each stator coil comprises first end and second end, and first end of said stator coil couples a common node (step S2101).First supply voltage (step S2102) is provided, and for example is the V of the foregoing description _DcProvide at least 3 to go up bridge switch, couple respectively between second end of above-mentioned 3 phase stator coils and first supply voltage (step S2103).

At least 3 following bridge switch are provided, couple second end and an impedance component R of above-mentioned 3 phase stator coils respectively _DCFirst end between, impedance component R wherein _DCSecond termination, one second source voltage, for example ground connection, and second source voltage is less than the first supply voltage V _Dc(step S2104).Next, in those stator coils, no current is by first stator coil, and the last bridge switch conducting that second end of working as second stator coil is coupled, during following bridge switch conducting that second end of the 3rd stator coil is coupled (step S2105), two-phase conduction period just, and another is when PWM-on, comprises following substep to I haven't seen you for ages this moment: the voltage of second end of detecting the 3rd stator coil is as the first given voltage V _Open(step S2106).Detecting impedance component R _DCThe voltage drop at two ends (Voltage Drop) is as the second given voltage V _Idc(step S2107).Utilize the first supply voltage V _Dc, the first given voltage V _OpenWith the second given voltage V _IdcJudge that whether taking place zero hands over (step S2108) more.

Above-mentioned step S2107, the inference according to the circuit and the mathematics of above-mentioned preferred embodiment also can comprise following substep: with V _Open, V _Dd, V _IdcDwindle a special ratios respectively and obtain v _Open, v _Dd, v _Idc(step S2109).With v _Open, v _Dd, v _IdcAccording to 2: 1: 1 mixed was a back electromotive force signal e _Open(step S2110).And work as the back electromotive force signal greater than a predetermined voltage V _Ref1, judge then that PWM-on zero hands over to give birth to (step S2111) all the more.

In addition, in preferred implementation of the present invention, in a little stator coils, no current is by this first stator coil, and the last bridge switch that is coupled when second end of second stator coil ends, during following bridge switch conducting that this second end of the 3rd stator coil is coupled (step S2112), and two-phase conduction period just, and another is when PWM-off, and comprise following substep to I haven't seen you for ages this moment: with the first given voltage V _OpenDwindle a special ratios and obtain a back electromotive force signal e _Open(step S2113).When the back electromotive force signal is greater than a predetermined voltage, judge then that PWM-off zero hands over to give birth to (step S2114) all the more.Judge at last PWM-on zero hands over more to hand over PWM-off zero more how (step S2115) takes place earlier the person.When PWM-on zero hands over first more generation, be standard control motor commutation (step S2116) more then with PWM-on zero friendship.When PWM-off zero hands over first more generation, be standard control motor commutation (step S2117) more then with PWM-off zero friendship.

In sum, the present invention is because of adopting in above-mentioned three-phase coil, when electric current flows to second end of the 3rd certain coil by second end of second certain coil, and no current is by first certain coil, just the voltage of second end of detecting first coil is as first given voltage, and the voltage drop of detecting direct current sensing resistor is as one second given voltage.Next the direct voltage that utilizes first given voltage, second given voltage and be supplied to motor is to estimate zero crossover point with the control motor.Therefore do not need as existing known techniques, to use filter circuit, can not cause detecting zero to hand over the problem of looks position delay all the more yet.And the circuit of the embodiment of the invention can detect zero crossover point by the stator coil of the non-active state of detecting (non-excited), no matter is PWM-on state or PWM-off state.

The above, it only is preferred embodiment of the present invention, be not that the present invention is done any pro forma restriction, though the present invention discloses as above with preferred embodiment, yet be not in order to limit the present invention, any those skilled in the art, in not breaking away from the technical solution of the present invention scope, when the method that can utilize above-mentioned announcement and technology contents are made a little change or be modified to the equivalent embodiment of equivalent variations, but every content that does not break away from technical solution of the present invention, according to technical spirit of the present invention to any simple modification that above embodiment did, equivalent variations and modification all still belong in the scope of technical solution of the present invention.

Claims (20)

1. a motor control method is characterized in that it comprises the following steps:

One motor is provided, comprises at least 3 phase stator coils, each stator coil comprises one first end and one second end, and this of those stator coils first end couples a common node;

One first supply voltage is provided;

Provide at least 3 to go up bridge switch, couple respectively between this second end and this first supply voltage of above-mentioned 3 phase stator coils;

At least 3 following bridge switch are provided, couple respectively between this second end and impedor first end of above-mentioned 3 phase stator coils, this impedor second termination, one second source voltage wherein, and this second source voltage is less than this first supply voltage;

In those stator coils, no current is by one first stator coil, and the last bridge switch conducting that is coupled when this second end of one second stator coil, during following bridge switch conducting that this second end of one the 3rd stator coil is coupled:

The voltage of this second end of detecting this first stator coil is as one first given voltage;

The voltage drop (Voltage Drop) of detecting these impedance component two ends is as one second given voltage;

And

Utilize this first supply voltage, this first given voltage and this second given voltage to judge whether to take place one the first zero to hand over and get over.

2. motor control method according to claim 1, it is characterized in that wherein defining this first voltage source is V _Dd, this first given voltage is V _Open, this second given voltage is V _Idc, then step " utilize this first supply voltage, this first given voltage and this second given voltage with judge whether take place this first zero hand over get over " comprising:

With V _Open, V _Dd, V _IdcDwindle a special ratios respectively and obtain v _Open, v _Dd, v _Idc

With v _Open, v _Dd, v _IdcAccording to 2: 1: 1 mixed was a back electromotive force signal; And

When this back electromotive force signal greater than a predetermined voltage, then judge this first zero hand over living all the more.

3. motor control method according to claim 1 is characterized in that it more comprises the following steps:

In those stator coils, no current is by this first stator coil, and the last bridge switch that is coupled when this second end of this second stator coil ends, during following bridge switch conducting that this second end of the 3rd stator coil is coupled:

This first given voltage is made a scale operation to judge that whether take place one the second zero hands over and get over.

4. motor control method according to claim 3, it is characterized in that wherein said " with this first given voltage do a scale operation with judge whether take place this second zero hand over get over " step comprises:

This first given voltage is dwindled a special ratios obtain a back electromotive force signal; And

When this back electromotive force signal is greater than a predetermined voltage, then judge this second zero hand over living all the more.

5. motor control method according to claim 3 is characterized in that it more comprises the following steps:

Judge this first zero hands over more more how the person is taken place earlier with this second zero friendship; And

The first zero hand over more and the second zero to hand over more when this, take place one specific zero earlier when handing over more, then control this motor commutation more with this specific zero friendship with this.

6. motor control circuit, it is characterized in that it controls a motor, this motor comprises at least 3 phase stator coils, each stator coil comprises one first end and one second end, this of those stator coils first end couples a common node, this of those stator coils second end couples at least one bridge switch and at least one bridge switch down gone up, bridge switch is respectively in order to determine whether a supply voltage is supplied to those stator coils on each, bridge switch couples by an impedance component and connects voltage altogether under each, and this motor control circuit comprises:

One selects circuit, couple second end of those stator coils, when this first phase coil and this second phase coil second end coupled goes up or when bridge switch switches according to the pulse wave width modulation signal down, with the voltage response of second end of third phase coil to the output of selecting circuit as one first voltage;

One zero hand over detecting unit more, couple the output of this selection circuit, the last bridge switch conducting that is coupled when second end of first phase coil, when following bridge switch ends, this supply voltage composition and this impedor cross-pressure removed in this first voltage obtain one first anti-electric voltage, relatively this first anti-electric voltage and one first reference voltage are exported one the first zero and are handed over decision signal more; And

One control circuit the first zero hands over more decision signal to judge that zero hands over the time of giving birth to all the more to control this motor according to this.

7. motor control circuit according to claim 6 is characterized in that wherein said zero hands over more that detecting unit comprises:

One the first zero hands over circuit for detecting more, in order to the last bridge switch conducting that is coupled when second end of first phase coil, when following bridge switch ends, this supply voltage composition and this impedor cross-pressure removed in this first voltage obtain this first anti-electric voltage, relatively this first anti-electric voltage and this first reference voltage are exported this and the first zero are handed over decision signal more; And

One the second zero hands over circuit for detecting more, the last bridge switch that is coupled in order to second end when first phase coil by the time, as one second anti-electric voltage, relatively this second anti-electric voltage and one second reference voltage are exported one the second zero and are handed over decision signal more with this first voltage.

8. motor control circuit according to claim 7, it is characterized in that wherein said selection circuit comprises that one first ratio dwindles circuit, dwindles a predetermined ratio in order to voltage and obtain this first voltage, and this first zero hands over more that circuit for detecting comprises second end of the 3rd stator coil:

One second ratio is dwindled circuit, and this supply voltage is dwindled this predetermined ratio as one second voltage, should dwindle this predetermined ratio as a tertiary voltage by impedor cross-pressure; And

One analogy differential amplifier circuit in order to according to 2: 1: 1 proportionate relationship, amplifies after this first voltage deducted this second voltage and this tertiary voltage, exports this first anti-electric voltage.

9. motor control circuit according to claim 8 is characterized in that wherein said the first zero hand over more that circuit for detecting also comprises:

One generating circuit from reference voltage, in order to produce this first reference voltage, the wherein last bridge switch conducting that is coupled when second end of this first phase coil, following bridge switch ends, the following bridge switch conducting of this second phase coil, and when this third phase coil still has electric current to flow to second end by first end, setting this first reference voltage is the accurate position of a high voltage, when the voltage quasi position of this first anti-electric voltage is lower than the accurate position of this high voltage, setting this first reference voltage is the accurate position of an intermediate voltage, when the voltage quasi position of this first anti-electric voltage was higher than the accurate position of this intermediate voltage, setting this first reference voltage was the accurate position of a low voltage;

One comparison circuit comprises positive input terminal, negative input end and output, and its positive input terminal receives this first anti-electric voltage, and its negative input end receives this first reference voltage, and its output is exported a comparative voltage; And

One sample circuit couples the output of this comparison circuit, receives this comparative voltage, and during in order to bridge switch conducting on first stator coil, this comparative voltage of taking a sample the first zero is handed over decision signal more to obtain this.

10. motor control circuit according to claim 8 is characterized in that wherein said the first zero hand over more that circuit for detecting also comprises:

One generating circuit from reference voltage, in order to produce this first reference voltage, the wherein last bridge switch conducting that is coupled when second end of this first phase coil, following bridge switch ends, the following bridge switch conducting of this second phase coil, and when this third phase coil still has electric current to flow to first end by second end, setting this first reference voltage is the accurate position of a low voltage, when the voltage quasi position of this first anti-electric voltage is higher than the accurate position of this high voltage, setting this first reference voltage is the accurate position of an intermediate voltage, when the voltage quasi position of this first anti-electric voltage was lower than the accurate position of this intermediate voltage, setting this first reference voltage was the accurate position of a high voltage;

One comparison circuit comprises positive input terminal, negative input end and output, and its positive input terminal receives this first anti-electric voltage, and its negative input end receives this first reference voltage, and its output is exported a comparative voltage; And

One sample circuit couples the output of this comparison circuit, receives this comparative voltage, and during in order to bridge switch conducting on first stator coil, this comparative voltage of taking a sample the first zero is handed over decision signal more to obtain this.

11. motor control circuit according to claim 7 is characterized in that wherein said the second zero hand over more that circuit for detecting comprises:

One comparison circuit comprises positive input terminal, negative input end and output, and its positive input terminal receives this second anti-electric voltage, and its negative input end receives this second reference voltage, and its output is exported a comparative voltage; And

One sample circuit couples the output of this comparison circuit, receives this comparative voltage, and during in order to bridge switch conducting on first stator coil, this comparative voltage of taking a sample the second zero is handed over decision signal more to obtain this.

12. motor control circuit according to claim 7, it is characterized in that wherein said control circuit receive this first, this second zero hands over more decision signal to hand over index signal more to obtain 1, and according to this zero index signal more of handing over, export a commutation index signal, wherein switch state regular as follows of this commutation index signal:

Calculate this commutation index signal switching state i before zero friendship and get over the time, wherein those zero hand over more that timing definition comprises following (1) or (2): (1) this zero state of handing over index signal more transfers second state to by first state and transfers time first state to this zero state of handing over index signal more to by second state, (2) this zero state of handing over index signal more transfers first state to by second state and transfers time second state to this zero state of handing over index signal more to by first state, and wherein to hand over and get over time representation be T to k zero _k, wherein i, k are natural number and 0＜k=＜i;

Give each zero friendship time one weighted value more, k the zero weighted value of the time of getting over of handing over is expressed as G _k

Define one time of delay T _dFor:

T _d=(G ₁* T ₁+ ... + G _k* T _k+ ... + G _i* T _i)/2* (G ₁+ ... + G _i); And

This time of delay after the 1st zero is handed over time more, change the state of this commutation index signal.

13. a brushless motor system is characterized in that it comprises:

One motor comprises at least 3 phase stator coils, and each stator coil comprises first end and second end, and this of those stator coils first end couples a common node;

A plurality of bridge switch of going up couple bridge switch on one of them of bridge switch on those at least between second end of each stator coil and the supply voltage, bridge switch is respectively in order to determine whether a supply voltage is supplied to those stator coils on each;

One impedance component, its first end couples and connects voltage altogether;

A plurality of following bridge switch couple those one of them following bridge switch of bridge switch down at least between second end of each stator coil and this impedor second end;

One selects circuit, couple second end of those stator coils, when this first phase coil and this second phase coil second end coupled goes up or when bridge switch switches according to the pulse wave width modulation signal down, with the voltage response of second end of third phase coil to the output of selecting circuit as one first voltage;

One zero hand over detecting unit more, couple the output of this selection circuit, the last bridge switch conducting that is coupled when second end of first phase coil, when following bridge switch ends, this supply voltage composition and this impedor cross-pressure removed in this first voltage obtain one first anti-electric voltage, relatively this first anti-electric voltage and one first reference voltage are exported one the first zero and are handed over decision signal more; And

One control circuit is got over decision signal according to this zero friendship and is judged that zero hands over the living all the more time to control this motor.

14. brushless motor system according to claim 13 is characterized in that wherein said zero hands over more that detecting unit comprises:

One the first zero hands over circuit for detecting more, in order to the last bridge switch conducting that is coupled when second end of first phase coil, when following bridge switch ends, this supply voltage composition and this impedor cross-pressure removed in this first voltage obtain this first anti-electric voltage, relatively this first anti-electric voltage and this first reference voltage are exported this and the first zero are handed over decision signal more; And

One the second zero hands over circuit for detecting more, the last bridge switch that is coupled in order to second end when first phase coil by the time, as one second anti-electric voltage, relatively this second anti-electric voltage and one second reference voltage are exported one the second zero and are handed over decision signal more with this first voltage.

15. brushless motor system according to claim 14, it is characterized in that wherein said selection circuit comprises that one first ratio dwindles circuit, dwindles a predetermined ratio in order to voltage and obtain this first voltage, and this first zero hands over more that circuit for detecting comprises second end of the 3rd stator coil:

One second ratio is dwindled circuit, and this supply voltage is dwindled this predetermined ratio as one second voltage, should dwindle this predetermined ratio as a tertiary voltage by impedor cross-pressure; And

One analogy differential amplifier circuit in order to according to 2: 1: 1 proportionate relationship, amplifies after this first voltage deducted this second voltage and this tertiary voltage, exports this first anti-electric voltage.

16. brushless motor system according to claim 15 is characterized in that wherein said the first zero hand over more that circuit for detecting also comprises:

One generating circuit from reference voltage, in order to produce this first reference voltage, the wherein last bridge switch conducting that is coupled when second end of this first phase coil, following bridge switch ends, the following bridge switch conducting of this second phase coil, and when this third phase coil still has electric current to flow to second end by first end, setting this first reference voltage is the accurate position of a high voltage, when the voltage quasi position of this first anti-electric voltage is lower than the accurate position of this high voltage, setting this first reference voltage is the accurate position of an intermediate voltage, when the voltage quasi position of this first anti-electric voltage was higher than the accurate position of this intermediate voltage, setting this first reference voltage was the accurate position of a low voltage;

One comparison circuit comprises positive input terminal, negative input end and output, and its positive input terminal receives this first anti-electric voltage, and its negative input end receives this first reference voltage, and its output is exported a comparative voltage; And

One sample circuit couples the output of this comparison circuit, receives this comparative voltage, and during in order to bridge switch conducting on first stator coil, this comparative voltage of taking a sample the first zero is handed over decision signal more to obtain this.

17. brushless motor system according to claim 15 is characterized in that wherein said the first zero hand over more that circuit for detecting also comprises:

One generating circuit from reference voltage, in order to produce this first reference voltage, the wherein last bridge switch conducting that is coupled when second end of this first phase coil, following bridge switch ends, the following bridge switch conducting of this second phase coil, and when this third phase coil still has electric current to flow to first end by second end, setting this first reference voltage is the accurate position of a low voltage, when the voltage quasi position of this first anti-electric voltage is higher than the accurate position of this high voltage, setting this first reference voltage is the accurate position of an intermediate voltage, when the voltage quasi position of this first anti-electric voltage was lower than the accurate position of this intermediate voltage, setting this first reference voltage was the accurate position of a high voltage;

One comparison circuit comprises positive input terminal, negative input end and output, and its positive input terminal receives this first anti-electric voltage, and its negative input end receives this first reference voltage, and its output is exported a comparative voltage; And

One sample circuit couples the output of this comparison circuit, receives this comparative voltage, and during in order to bridge switch conducting on first stator coil, this comparative voltage of taking a sample the first zero is handed over decision signal more to obtain this.

18. brushless motor system according to claim 14 is characterized in that wherein said the second zero hand over more that circuit for detecting comprises:

One comparison circuit comprises positive input terminal, negative input end and output, and its positive input terminal receives this second anti-electric voltage, and its negative input end receives this second reference voltage, and its output is exported a comparative voltage; And

One sample circuit couples the output of this comparison circuit, receives this comparative voltage, and during in order to bridge switch conducting on first stator coil, this comparative voltage of taking a sample the second zero is handed over decision signal more to obtain this.

19. brushless motor system according to claim 14, it is characterized in that wherein said control circuit receive this first, this second zero hands over more decision signal to hand over index signal more to obtain 1, and according to this zero index signal more of handing over, export a commutation index signal, wherein switch state regular as follows of this commutation index signal:

Calculate this commutation index signal switching state i before zero friendship and get over the time, wherein those zero hand over more that timing definition comprises following (1) or (2): (1) this zero state of handing over index signal more transfers second state to by first state and transfers time first state to this zero state of handing over index signal more to by second state, (2) this zero state of handing over index signal more transfers first state to by second state and transfers time second state to this zero state of handing over index signal more to by first state, and wherein to hand over and get over time representation be T to k zero _k, wherein i, k are natural number and 0＜k=＜i;

Give each zero friendship time one weighted value more, k the zero weighted value of the time of getting over of handing over is expressed as G _k

Define one time of delay T _dFor:

T _d=(G ₁* T ₁+ ... + G _k* T _k+ ... + G _i* T _i)/2* (G ₁+ ... + G _i); And

This time of delay after the 1st zero is handed over time more, change the state of this commutation index signal.

20. a motor control method is characterized in that it comprises the following steps:

Provide one zero to hand over an index signal and a commutation index signal more;

Calculate this commutation index signal switching state i before zero friendship and get over the time, wherein those zero hand over more that timing definition comprises following (1) or (2): (1) this zero state of handing over index signal more transfers second state to by first state and transfers time first state to this zero state of handing over index signal more to by second state, (2) this zero state of handing over index signal more transfers first state to by second state and transfers time second state to this zero state of handing over index signal more to by first state, and wherein to hand over and get over time representation be T to k zero _k, wherein i, k are natural number and 0＜k=＜i;

Give each zero friendship time one weighted value more, k the zero weighted value of the time of getting over of handing over is expressed as G _k

Define one time of delay T _dFor:

T _d=(G ₁* T ₁+ ... + G _k* T _k+ ... + G _i* T _i)/2* (G ₁+ ... + G _i); And

This time of delay after the 1st zero is handed over time more, change the state of this commutation index signal.

Images