CN107733300B - A kind of safe and reliable brushless DC motor without sensor starting control method - Google Patents

A kind of safe and reliable brushless DC motor without sensor starting control method Download PDF

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Publication number
CN107733300B
CN107733300B CN201711042266.2A CN201711042266A CN107733300B CN 107733300 B CN107733300 B CN 107733300B CN 201711042266 A CN201711042266 A CN 201711042266A CN 107733300 B CN107733300 B CN 107733300B
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China
Prior art keywords
motor
determined bit
electric current
rotor
commutation
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CN201711042266.2A
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Chinese (zh)
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CN107733300A (en
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周新秀
陈曦
周咏平
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北京航空航天大学
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    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02PCONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P6/00Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
    • H02P6/20Arrangements for starting
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02PCONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P6/00Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
    • H02P6/14Electronic commutators
    • H02P6/16Circuit arrangements for detecting position
    • H02P6/18Circuit arrangements for detecting position without separate position detecting elements
    • H02P6/182Circuit arrangements for detecting position without separate position detecting elements using back-emf in windings

Abstract

The present invention relates to a kind of safe and reliable brushless DC motor without sensor to start control method, by preset current, the relationship of instantaneous position of analyzing the pre-determined bit stage, obtain the minimum current value injected required for two steps pre-determined bit method, after pre-determined bit, zero crossing is detected using line voltage difference, motor back-emf zero crossing in first commutation section is surveyed can by injecting suitable acceleration electric current, and then guarantee smooth commutation, motor can be made to transit directly to the motor synchronizing stage from the pre-determined bit stage by this method.

Description

A kind of safe and reliable brushless DC motor without sensor starting control method

Technical field

The present invention relates to the technical fields of brshless DC motor starting control, and in particular to a kind of safe and reliable without sensing Device brshless DC motor starts control method, is suitable for industry, Aerospace Control field, realizes brushless DC motor without sensor Starting.

Background technique

Brshless DC motor because its high power density, high efficiency, high torque (HT) ratio of inertias, it is compact-sized the advantages that be widely applied In industrial production, aerospace and military field.Traditional brshless DC motor needs position sensor to provide rotor-position letter Breath is to realize accurate commutation control, however, the installation of position sensor not only increases equipment cost, also to the daily of motor More stringent requirements are proposed for maintenance, while also reducing the stability and reliability of system entirety.In order to avoid above-mentioned unfavorable shadow It rings, motor without position sensor actuation techniques are widely used in brshless DC motor.It is driven in numerous position-sensor-frees In method, back-emf zero crossing detection is applied at most because of the advantages that its simple easily realization and high reliability.However, due to motor There is no counter electromotive force when static, the brushless DC motor without sensor driving method based on counter electromotive force zero passage detection is faced with Start difficult problem.Any position sensor is not utilized, smoothly drives a brshless DC motor from stationary state to specified Revolving speed is difficult.Three steps starting method is generallyd use in conventional method, it includes three forced alignment, outer synchronization, motor synchronizing ranks Section.Although principle is very simple, process of realizing lacks theoretical direction and is easy to be influenced and failure by Parameter Perturbation, because This brshless DC motor without sensor receives the limitation of these disadvantages in the application of low-speed range.

Summary of the invention

The technical problem to be solved by the present invention is existing brushless DC motor without sensor is overcome to ask from static starting is difficult Topic, on the basis of the relationships such as detailed analysis startup stage electric current and torque, detectable commutation point, propose a kind of no sensor without The control method that brushless motor reliably starts from stationary state has the following characteristics that (1) is possible to for the pre-determined bit stage Occur rotor be located in " dead zone ", need biggish pre-determined bit electric current, so as to cause it is static when power device damage risk, divide Two step positioning modes are used after analysis, derive that the pre-determined bit stage guarantees the minimum pre-determined bit current value of reliable location.(2) pass through detection Line voltage difference extracts back-emf zero crossing, and back-emf signal size detected is exaggerated 2 times, makes the detection of zero crossing more It is easy to add, and finally makes it possible motor accurate commutation when revolving speed is lower.(3) certain by applying after being pre-positioned The acceleration electric current of size survey the back-emf zero crossing in first commutation section can, and then guarantee that commutation is gone on smoothly, should Accelerating the lower limit of current value can be obtained by analysis.This method transits directly to the motor synchronizing stage, and eliminating reduces motor performance Outer synchronous phase.

The present invention solve above-mentioned technical problem the technical solution adopted is that: a kind of safe and reliable non sensor brushless direct current Electric motor starting control method realizes mainly include the following contents:

(1) analysis acquires the minimum current value injected needed for pre-determined bit stage reliable location

Motor stator is passed through electric current and generates electromagnetic force, to obtain electromagnetic torque Te, form can be expressed as:

Te=Kt×Ip×sin(θ0) (14)

Wherein KtIt is torque coefficient, IpIt is pre-determined bit electric current, θ0The magnetomotive force and rotor permanent magnet that be stator generated by electric current The angle between magnetomotive force that body generates, θ0∈(–π,π).For dragging motor, electromagnetic torque TeDamping torque T should be greater than0, It is as follows:

Kt×Ip×|sin(θ0)|>T0 (15)

Wherein, the K for particular motortUsually constant, therefore obtain pre-determined bit electric current IpWith phase angle theta0Meet formula (16) when, rotor can normally be dragged.

Other cannot be by being pre-positioned electric current IpThe region of dragging is referred to as " dead zone " (θdead)。

If initial position of rotor is located at " dead zone ", at this time θ0Very little is difficult to overcome resistance pre-determined bit electric current is very big Buddhist nun's torque dragging motor.In order to avoid this problem, it is pre-positioned method using two steps, after first time is pre-positioned, is dragged again Rotor fixed position is in the position for differing 60 ° with first time orientation angle.In order to guarantee effectively to drag rotor in two steps, two steps are pre- The sum of " dead zone " of positioning should guarantee at least can once be positioned to function in this way less than 60 °.

2×θdead≤60° (18)

In addition, being pre-positioned electric current I known to formula (17)pInfluence the size in " dead zone ": pre-determined bit electric current IpIt is bigger, it is " dead Area " is smaller.However, excessive pre-determined bit electric current may cause power device damage, especially in stationary rotor stall.In conjunction with Formula (15) (18), the available the smallest starting current for guaranteeing two steps pre-determined bit method reliable location rotor are as follows:

(2) detection line voltage difference is to extract back-emf zero crossing

Brshless DC motor phase voltage equation is:

Subscript x=a, b, c.uxIt is DC terminal phase-to-ground voltage, unIt is the voltage of neutral point relatively, ixIt is phase current, R It is phase resistance, L is phase inductance, exIt is phase back-emf.

It is analyzed so that CB is conducted as an example, the down tube of the upper tube of C phase and B phase is open-minded at this time, and A phase is non-conduction phase. According to equation (20), line voltage U can be obtainedcaAnd Uab, and the difference of the two line voltages can be represented as:

At this point, ic=-ib,iaThe counter electromotive force that=0, C phase are generated with B phase is equal in magnitude contrary, ec=-eb, therefore can It obtains:

ucaab=-2ea (22)

Similarly, when other are conducted, also there is conclusion like above, it can be seen that the line voltage difference signal of detection is 2 Back-emf value again can thus make back-emf can detect range and expand to the more slow-speed of revolution.

(3) it realizes from pre-determined bit and is directly switch to the motor synchronizing stage

After the completion of pre-determined bit, it is passed through acceleration electric current to motor stator, rotor starts to accelerate rotation, if can be in first commutation Correct commutation at point, so that it may directly transit directly to the motor synchronizing stage from the pre-determined bit stage, accelerate electric current bigger, detect Commutation point is closer to ideal commutation point, if electric current very little is possible to can't detect depositing for commutation point in first commutation section Causing to be switched to the failure of motor synchronizing stage, therefore, to guarantee that first time commutation point can be detected reliably, is needing to analyze injection The influence that accelerates size of current detect commutation point simultaneously obtains smoothly being switched to the smallest required for the motor synchronizing stage add Fast electric current.

Assuming that rotor is located at I after pre-determined bit, first commutation point at II, at two between be divided into 60 °, rotor is from I Locating the rotation equation at II can indicate are as follows:

ω1=a1×t1 (23)

θ1=a1×t1 2/2 (24)

Wherein α1It is the average rotary acceleration of rotor, ω1It is spinner velocity, t1It is acceleration time, θ1=π/3 (from I to II), wushu (24) brings formula (23) into and obtains rotor in the instantaneous velocity of the position II, to obtain the counter electromotive force in the position II Value:

keIt is back EMF coefficient, EaIt is the back-emf value at II, p indicates motor number of pole-pairs.According to the torque of rotor Equilibrium equation, rotor acceleration values are available:

TLIt is loading moment.Wushu (26) is brought formula (25) into and is obtained:

It can be seen that the counter electromotive force size and acceleration electric current I at one timing of loading moment, IIaIt is related, it is contemplated that There is a signal amplification conditioning link, in zero-crossing detection circuit in order to guarantee that detection circuit can measure opposite electricity this moment Kinetic potential has following formula:

Ea×G≥Umin (28)

G is the gain amplifier of signal amplification conditioning, UminIt is the minimum voltage-measurable of voltage detecting circuit.

The method that zero crossing is extracted using the detection line voltage difference introduced in (2), and convolution (22) (27) (28) To accelerate electric current:

The electric current is the minimum current for guaranteeing to terminate directly to carry out motor synchronizing acceleration from pre-determined bit, based on the commutation detected Point, ideal commutation moment can be obtained by 30 ° of electrical angles of delayed zero crossing point.

The principle of the present invention is: a kind of safe and reliable brushless DC motor without sensor starting control method: logical first Injection pre-determined bit electric current is crossed, pressure alignment is carried out to rotor, to avoid rotor from being located at the case where " dead zone " can not drag, using two Footwork reliably positions rotor.Back-emf zero crossing, this method detection are extracted by the way of detection line voltage difference Back-emf signal amplitude be 2 times of true value so that may also detect that when motor speed is relatively low Zero point.After pre-determined bit, make motor back-emf zero crossing in first commutation section by injecting suitable acceleration electric current It can survey, and then guarantee smooth commutation, motor can be made to transit directly to the motor synchronizing stage from the pre-determined bit stage by this method.

Compared with existing scheme, major advantage is the solution of the present invention:

(1) existing scheme can not provide pre-determined bit stage electrical current size, and debugging process only relies on experience, and blindly It is passed through the risk that super-high-current has damage device.The present invention analyzes the pass of the preset current in pre-determined bit stage, instantaneous position System has obtained the minimum current value injected required for the pre-determined bit stage, provides theoretical reference for the debugging of pre-determined bit stage.

(2) existing scheme extracts zero crossing by detection phase voltage or line voltage and obtains commutation position, and low speed difficulty is surveyed.This Invention obtains back electromotive force zero-crossing using detection line voltage difference, and line voltage difference signal is 2 times of true back-emf amplitude, this So that the detection of zero crossing is more easier, created condition for motor in lower Rotating speed measring commutation point.

(3) existing scheme enters the outer sync plus white stage after pre-determined bit, and outer sync plus white can not detect commutation point, It is controlled completely by external signal, there are the risks of step-out.The present invention accelerates the relationship of electric current and back-emf size by analysis, tastes Examination detects commutation point in first commutation section, the size of the acceleration current value by analyzing its available minimum value so that Transitting directly to the motor synchronizing stage is possibly realized, and eliminates the outer synchronous phase for reducing motor performance.

Detailed description of the invention

Fig. 1 is start-up course flow chart of the invention;

Fig. 2 is that two steps are pre-positioned schematic diagram, wherein Fig. 2 (a) is that pre-determined bit stage electromagnetism and the magnetomotive direction of permanent magnetism are closed Be schematic diagram, Fig. 2 (b) be pre-determined bit stage rotor can not trailing " dead zone " schematic diagram, Fig. 2 (c) is the pre-determined bit stage two Step pre-determined bit process schematic;

Fig. 3 is that motor accelerates first commutation interval diagram, wherein Fig. 3 (a) is first acceleration area rotor of motor Schematic diagram is moved, Fig. 3 (b) is first acceleration area opposite potential waveform diagram of motor.

Specific embodiment

With reference to the accompanying drawing and specific embodiment further illustrates the present invention.

As shown in Figure 1, in the specific implementation process, a kind of safe and reliable brushless DC motor without sensor of the present invention opens The specific implementation step of flowing control method is as follows:

(1) it calculates the minimum current value injected needed for pre-determined bit stage reliable location and completes to be pre-positioned.Guarantee that two steps are pre- The smallest starting current of positioning mode reliable location rotor can be calculated by following formula

After the current value is calculated according to real electrical machinery parameter, predetermined bit positions are set, and be pre-positioned method through two steps Complete positioning operation.

(2) injection accelerates electric current

After the completion of pre-determined bit, starting line voltage difference detects zero crossing program, while being passed through acceleration electric current to motor stator, turns Son starts to accelerate rotation, and size of current is accelerated to be calculated by following formula:

The electric current is the minimum current for guaranteeing to terminate directly to carry out motor synchronizing acceleration from pre-determined bit, based on the commutation detected Point, ideal commutation moment can be obtained by 30 ° of electrical angles of delayed zero crossing point.

(3) it realizes from pre-determined bit and is directly switch to the motor synchronizing stage

If smoothly detecting zero crossing in first acceleration area of motor and completing commutation, with the acceleration of motor, Zero crossing later is easier to measure, and motor smoothly cuts motor synchronizing operating status, and start-up course terminates;Otherwise, step is repeated (1)-(2), until start completion.

The content being not described in detail in present specification belongs to the prior art well known to professional and technical personnel in the field.

Claims (2)

1. a kind of safe and reliable brushless DC motor without sensor starts control method, it is characterised in that: predetermined by analyzing Preset current, the relationship of instantaneous position in position stage obtain the minimum current value injected required for two steps pre-determined bit method;Pre-determined bit After, zero crossing is detected using line voltage difference, and make motor in first commutation area by injecting suitable acceleration electric current Interior back-emf zero crossing can be surveyed, and guarantee smooth commutation, and motor is made to transit directly to the completion of motor synchronizing stage from the pre-determined bit stage Starting;
It is described from pre-determined bit be directly switch to the motor synchronizing stage needed for acceleration size of current obtained by following methods:
After the completion of pre-determined bit, it is passed through acceleration electric current to motor stator, rotor starts to accelerate rotation, if can be at first commutation point Correct commutation, so that it may directly transit directly to the motor synchronizing stage from the pre-determined bit stage, accelerate electric current bigger, the commutation detected Point is closer to ideal commutation point, if electric current very little is possible to can't detect the presence of commutation point in first commutation section, Cause to be switched to the failure of motor synchronizing stage, therefore, to guarantee that first time commutation point can be detected reliably, needs to analyze injection and accelerate Influence that size of current detects commutation point simultaneously obtains smoothly being switched to the smallest acceleration electricity required for the motor synchronizing stage Stream;
Assuming that rotor is located at I after pre-determined bit, first commutation point at II, at two between be divided into 60 °, rotor from I to Rotation equation at II can indicate are as follows:
ω1=a1×t1 (7)
θ1=a1×t1 2/2 (8)
Wherein α1It is the average rotary acceleration of rotor, ω1It is spinner velocity, t1It is acceleration time, θ1=π/3, wushu (8) are brought into Formula (7) obtains rotor in the instantaneous velocity of the position II, to obtain the back-emf value in the position II:
keIt is back EMF coefficient, EaIt is the back-emf value at II, p indicates motor number of pole-pairs, according to the torque balance of rotor Equation, rotor acceleration values are available:
TLIt is loading moment, wushu (10) is brought formula (9) into and obtained:
It can be seen that the counter electromotive force size and acceleration electric current I at one timing of loading moment, IIaIt is related, it is contemplated that in mistake There is signal amplification conditioning link in zero-detection circuit, in order to guarantee that detection circuit can measure this moment opposite electronic Gesture has following formula:
Ea×G≥Umin (12)
G is the gain amplifier of signal amplification conditioning link, UminIt is the minimum voltage-measurable of voltage detecting circuit;
The method that zero crossing is extracted using detection line voltage difference, and convolution (11), (12) obtain accelerating electric current:
The electric current is the minimum current for guaranteeing to terminate directly to carry out motor synchronizing acceleration from pre-determined bit, based on the commutation point detected, Ideal commutation moment can be obtained by 30 ° of electrical angles of delayed zero crossing point.
2. safe and reliable brushless DC motor without sensor according to claim 1 starts control method, feature exists In: the minimum current value in the pre-determined bit stage is obtained by following analysis:
Motor stator is passed through electric current and generates electromagnetic force, to obtain electromagnetic torque Te, form can be expressed as:
Te=Kt×Ip×sin(θ0) (1)
Wherein KtIt is torque coefficient, IpIt is pre-determined bit electric current, θ0It is the magnetomotive force and rotor permanent magnet production that stator is generated by electric current Angle between raw magnetomotive force, θ0∈ (- π, π), for dragging motor, electromagnetic torque TeDamping torque T should be greater than0, such as Under:
Kt×Ip×|sin(θ0) | > T0 (2)
Wherein, the K for particular motortIt is constant, therefore obtains pre-determined bit electric current IpWith phase angle theta0It, can when meeting formula (3) Normally to drag rotor;
Other cannot be by being pre-positioned electric current IpThe region of dragging is referred to as " dead zone " θdead,
If initial position of rotor is located at " dead zone ", at this time θ0Very little is difficult to overcome damping torque pre-determined bit electric current is very big Dragging motor is pre-positioned method using two steps in order to avoid this problem, and after first time is pre-positioned, it is fixed to drag rotor again Positioned at the position for differing 60 ° with first time orientation angle, in order to guarantee effectively to drag rotor in two steps, two steps pre-determined bit The sum of " dead zone " should guarantee at least can once be positioned to function in this way less than 60 °;
2×θdead≤60° (5)
In addition, being pre-positioned electric current I known to formula (4)pInfluence the size in " dead zone ": pre-determined bit electric current IpBigger, " dead zone " is got over It is small;However, excessive pre-determined bit electric current may cause power device damage, and especially in stationary rotor stall, in conjunction with formula, The available the smallest starting current for guaranteeing two steps pre-determined bit method reliable location rotor are as follows:
CN201711042266.2A 2017-10-30 2017-10-30 A kind of safe and reliable brushless DC motor without sensor starting control method CN107733300B (en)

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CN108768225A (en) * 2018-05-29 2018-11-06 广东威灵电机制造有限公司 Pre-determined bit dragging method, system and the synchronous motor control system of rotor

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101459407A (en) * 2009-01-08 2009-06-17 东元总合科技(杭州)有限公司 Initial position detection method for permanent magnet synchronous electric motor rotor
CN105680742A (en) * 2016-03-23 2016-06-15 北京航空航天大学 Sensorless rotor position identification system and method for brushless direct current motor

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* Cited by examiner, † Cited by third party
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JP5970227B2 (en) * 2012-04-17 2016-08-17 日立オートモティブシステムズ株式会社 Synchronous motor drive system

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101459407A (en) * 2009-01-08 2009-06-17 东元总合科技(杭州)有限公司 Initial position detection method for permanent magnet synchronous electric motor rotor
CN105680742A (en) * 2016-03-23 2016-06-15 北京航空航天大学 Sensorless rotor position identification system and method for brushless direct current motor

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