A kind of brshless DC motor does not have pickup wire back-emf method for detecting position
Technical field
The present invention relates to a kind of brshless DC motor does not have pickup wire back-emf method for detecting position, is particularly useful for the position probing of space flight with control-moment gyro product high speed three-phase brushless dc motor.
Background technology
Control-moment gyro is one of important execution unit of spacecraft, is mainly used in the attitude control of Large Spacecraft and the fast reserve of middle-size and small-size spacecraft, has vast potential for future development.As the crucial execution unit of posture control system, it is significant further to improve the control-moment gyro reliability of products.The high speed rotor of control-moment gyro uses brshless DC motor to drive, and brshless DC motor need be implemented commutation control to the motor windings electric current according to rotor-position.Obtain the positional information of rotor at present in the product by position transducer.Brshless DC motor does not have the sensing station detection method, is meant in electric machine control system, position and the speed of utilizing correlated variables in the winding such as stator current, stator voltage etc. to estimate rotor, and the position of substitution transducer is realized the control of brshless DC motor.Use the position-sensor-free location detecting technology will bring following advantage: to reduce body conducting ring number of rings, improve whole aircraft reliability; Reduce the complexity of motor body, reduce lead-in wire, simplify the manufacturing process of motor, improve reliability; Be not subjected to abominable external environment influence, make motor be applicable to abominable external environment condition; Solved because the commutation error problem that the position transducer installation accuracy is brought; Reduce the motor manufacturing cost.
Abroad, Muscovite control-moment gyro high-speed electric expreess locomotive has adopted the position Sensorless Control technology, and the accumulated energy flywheel of U.S. NASA has also adopted the position Sensorless Control technology, has all obtained and has controlled effect preferably.In the at present domestic control-moment gyro product, the position Sensorless Control technology does not also have application.The position Sensorless Control technology is applied to the control-moment gyro product, not only can guarantee the control precision of high-speed electric expreess locomotive driver circuit, control-moment gyro will be greatly improved at aspects such as body complexity, manufacturing process, costs, and product reliability is significant for improving.
Brshless DC motor does not have the research history that the sensing station detection technique has year surplus in the of 60, multiple method for detecting position has appearred during this time, yet, in the document of having delivered, mostly detection algorithm research is at the brshless DC motor of three-phase six-beat full-bridge driving the method for detecting position at the half-bridge driven brshless DC motor is not arranged also.The power device that the relative full bridge driving circuit of half-bridge drive circuit needs is few, volume is little, low in energy consumption, reliability is high, obtained using widely at space industry.During brshless DC motor work, commutation process can make three-phase winding terminal voltage produce big due to voltage spikes and disturb, causing line back-emf detection signal to produce due to voltage spikes disturbs, and then cause detected position signalling to produce errors present information, for this problem, adopt filter to filter commutation in the traditional location detection method mostly and disturb, but the time-delay meeting impact position accuracy of detection that filter is brought into.
Summary of the invention
Technology of the present invention is dealt with problems and is: overcome the deficiencies in the prior art, provide a kind of brshless DC motor not have pickup wire back-emf method for detecting position, solved the position probing problem of the brshless DC motor that uses the half-bridge circuit driving, avoided by the position detection error problem of using filter to cause.
Technical solution of the present invention is: a kind of brshless DC motor does not have pickup wire back-emf method for detecting position, comprises line back-emf detection signal zero passage comparison step and line back-emf position detection signal demodulation step;
Described line back-emf detection signal zero passage comparison step is: with the three-phase winding terminal voltage of half-bridge driven brshless DC motor difference in twos, obtain three line back-emf e
Ab, e
Bc, e
Ca, three line back-emf e
Ab, e
Bc, e
CaCarried out zero balancing by three zero-crossing comparators respectively, when certain line back-emf more than or equal to zero the time, then the output of zero-crossing comparator is exported the line back-emf position detection signal of high level, otherwise the line back-emf position detection signal of output low level, three line back-emf position detection signals of three zero-crossing comparators output are remembered respectively and are made HALL_A, HALL_B, HALL_C;
E wherein
AbBe A, B phase line back-emf, e
BcBe B, C phase line back-emf, e
CaBe C, A phase line back-emf, HALL_A is an A phase line back-emf position detection signal, and HALL_B is a B phase line back-emf position detection signal, and HALL_C is a C phase line back-emf position detection signal;
Described line back-emf position detection signal demodulation step is:
(1) utilizing A phase rising edge pulse generation circuit, B phase rising edge pulse generation circuit, C phase rising edge pulse generation circuit to carry out rising edge respectively to three line back-emf position detection signal HALL_A, HALL_B, HALL_C judges, generate three rising edge monitor signal pulse_a, pulse_b and pulse_c, when the line back-emf position detection signal of certain phase has rising edge to take place, then the rising edge pulse generation circuit generation width by this phase is the low level pulse of us level, otherwise the rising edge pulse generation circuit of this phase produces the rising edge monitor signal of high level;
Wherein pulse_a is an A phase rising edge monitor signal, and pulse_b is a B phase rising edge monitor signal, and pulse_c is a C phase rising edge monitor signal;
(2) three line back-emf position detection signal HALL_A, HALL_B, HALL_C are sent into A phase sampler/retainer, B phase sampler/retainer, C phase sampler/retainer respectively; The sampling of the sampling/retainer of wherein any phase or hold mode are controlled by the rising edge monitor signal of other two-phase, when any one the low level pulse of us level occurs in the rising edge monitor signal of other two-phase, then this phase sampler/retainer is operated in hold mode, otherwise this phase sampler/retainer is operated in sample states;
(3) three phase samplers/retainer is exported three-phase position signal according to separately sample states or hold mode.
The present invention's advantage compared with prior art is: the present invention is by carrying out zero passage earlier relatively to position detection signal, export three monitor signals, utilize three monitor signals to control the operating state of three phase samplers/retainer, utilize this method to remove and be all the other interference that cause mutually in the two-phase commutation process arbitrarily, thereby avoided the use of filter, simultaneously can not bring time-delay into, improved accuracy of detection, compare other back-emf detection methods and realize that simply the present invention need not to carry out electrical degree phase shift computing.
Description of drawings
Fig. 1 forms schematic diagram for half-bridge drive circuit of the present invention;
Fig. 2 is a line back-emf position probing flow chart of the present invention;
Fig. 3 realizes schematic diagram for line back-emf position probing of the present invention;
Fig. 4 is an A phase position signal demodulating process schematic diagram of the present invention.
Embodiment
The present invention will be further described below in conjunction with the drawings and specific embodiments.
Fig. 1 is the half-bridge drive circuit that has the voltage chopping device, wherein, and V
pBe power power-supply, u
pBe the control voltage of voltage chopping device output, a, b, c are respectively brshless DC motor A, B, C three phase windings, u
Ag, u
Bg, u
CgBe respectively the terminal voltage of A, B, the output of C three-phase, r is a winding resistance.Half-bridge drive circuit among the present invention has added the voltage chopping device at the power power-supply end, the voltage of supplying with three phase windings by control carries out Current Control, the inner PWM of employing of voltage chopping device modulates, through output control voltage after the Filtering Processing, the PWM switch disturbs and filters out by chopper inside, can position probing not cause interference.The line back-emf position probing method of the brshless DC motor of relative full bridge driving circuit, the present invention need not to consider the influence of PWM modulation to position probing, realizes simple.
This drive circuit any one have only one to be conducted constantly, and when a certain being conducted, the line voltage between two other non-conduction phase is two line back-emfs between the non-conduction phase.
When A is conducted, B, when C is mutually unsettled:
B opposite potential signal e
b=u
p-u
Bg, C opposite potential signal e
c=u
p-u
CgCan obtain B, C phase line back-emf signal e
Bc=u
Cg-u
Bg
When B is conducted, C, when A is mutually unsettled:
C opposite potential signal e
c=u
p-u
Cg, A opposite potential signal e
a=u
p-u
AgCan obtain C, A phase line back-emf signal e
Ca=u
Ag-u
Cg
When C is conducted, A, when B is mutually unsettled:
A opposite potential signal e
a=u
p-u
Ag, B opposite potential signal e
b=u
p-u
BgCan obtain A, B phase line back-emf signal e
Ab=u
Bg-u
Ag
As shown in Figure 2, detection method of the present invention comprises that mainly the line back-emf crosses each and every one step of zero balancing and position detection signal demodulation two.Brshless DC motor is eight pairs of utmost points of three-phase in this example, and the nominal operation rotating speed is 7000rpm.
As shown in Figure 3, the method for three opposite potential zero passage comparisons is: three line back-emf signal e
Ca, e
Ab, e
BcSend into three zero-crossing comparators respectively, when line back-emf detection signal more than or equal to zero the time, the position detection signal of output+5V high level, on the contrary export the low level position detection signal of 0V.By three back-emf position detection signals that zero-crossing comparator obtains, note is made HALL_A, HALL_B, HALL_C respectively.
The process that the position signalling of crossing zero balancing output is detected demodulation is: position detection signal HALL_A, HALL_B, HALL_C to three line back-emfs utilize A phase rising edge pulse generation circuit, B phase rising edge pulse generation circuit, C phase rising edge pulse generation circuit to carry out the rising edge judgement respectively, generate three rising edge monitor signal pulse_a, pulse_b and pulse_c.When the position detection signal of certain phase had rising edge to take place, it was the 0V low level pulse monitor signal of 50us that this phase rising edge pulse generation circuit produces width, when no rising edge takes place, and rising edge pulse generation circuit output+5V high level monitor signal;
(2) position detection signal HALL_A, HALL_B, the HALL_C with three line back-emfs sends into three sampling/retainers respectively, A phase sampler/retainer, B phase sampler/retainer, C phase sampler/retainer.
(3) sampling of A phase sampler/retainer or hold mode are controlled by the rising edge monitor signal pulse_b and the pulse_c of B, C two-phase.When pulse_b and pulse_c had any one to be low level pulse, sampling/retainer was operated in hold mode, otherwise sampling/retainer is operated in sample states.In fact, when B mutually or C when having rising edge to take place mutually, just B mutually or the commutation of C phase constantly, in commutation process, A phase winding terminal voltage can produce big due to voltage spikes and disturb, and causes line back-emf detection signal e
CaThe generation due to voltage spikes disturbs, and then cause the mutually detected position detection signal HALL_A of A to have error message, as shown in Figure 4, utilize the action of pulse_b and pulse_c control sampling holder, can make respectively HALL_A B mutually and C mutually the commutation moment A error message conductively-closed of bringing into mutually fall, obtain the mutually correct position signalling hall_a of A.
In like manner, the sampling of B phase sampler/retainer or hold mode are controlled by the rising edge monitor signal pulse_a and the pulse_c of A, C two-phase.As pulse_a and pulse_c when any one is arranged is low low level pulse, sampling/retainer is operated in hold mode, otherwise sampling/retainer is operated in sample states.The mutually detected position signalling HALL_B of B falls in the error message conductively-closed that A, the commutation of C two-phase are brought into constantly, obtains the mutually correct position signalling hall_b of B.
The sampling of C phase sampler/retainer or hold mode are controlled by the rising edge monitor signal pulse_a and the pulse_b of A, B two-phase.As pulse_a and pulse_b when any one is arranged is low low level pulse, sampling/retainer is operated in hold mode, otherwise sampling/retainer is operated in sample states.The mutually detected position signalling HALL_C of C falls in the error message conductively-closed that A, the commutation of B two-phase are brought into constantly, obtains the mutually correct position signalling hall_c of C.
(4) output hall_a, the hall_b of sampling/retainer and hall_c are and detect A, B, the C three-phase position signal that obtains.
The present invention not detailed description is a technology as well known to those skilled in the art.