CN102355184B - Back-EMF (back electromotive force) zero-crossing detection circuit and method for three-phase DC (direct current) brushless motors - Google Patents
Back-EMF (back electromotive force) zero-crossing detection circuit and method for three-phase DC (direct current) brushless motors Download PDFInfo
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- CN102355184B CN102355184B CN2011103322056A CN201110332205A CN102355184B CN 102355184 B CN102355184 B CN 102355184B CN 2011103322056 A CN2011103322056 A CN 2011103322056A CN 201110332205 A CN201110332205 A CN 201110332205A CN 102355184 B CN102355184 B CN 102355184B
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Abstract
The invention discloses a back-EMF (back electromotive force) zero-crossing detection circuit and method for three-phase DC (direct current) brushless motors. The circuit comprises constant-current diodes and a voltage comparator, wherein the constant-current diodes comprise a first constant-current diode, a second constant-current diode, a third constant-current diode, a fourth constant-current diode, a fifth constant-current diode, a sixth constant-current diode, a first protection diode and a second protection diode; the first end of a phase winding of a motor is connected with the positive pole of the first constant-current diode and the negative pole of the second constant-current diode; the second end of the phase winding of the three-phase DC brushless motor is connected with the positive pole of the third constant-current diode and the negative pole of the fourth constant-current diode; and the third end of the phase winding of the three-phase DC brushless motor is connected with the positive pole of fifth constant-current diode and the negative pole of the sixth constant-current diode. The circuit disclosed by the invention has the characteristics of low noise, high sensitivity, and good anti-interference performance; and by using the circuit disclosed by the invention, an effect of zero-phase-shifting accurate detection on back-EMF zero-crossing signals within a wide speed range can be achieved without an RC (resistance-capacitance) low-pass filter circuit.
Description
Technical field
The present invention relates to the back electromotive force detection technique of DC brushless motor, specifically refer to back electromotive force zero-crossing detection circuit and the detection method of three-phase direct-current brushless motor.
Background technology
The traditional method for detecting position of brushless electric machine is that Hall element direct-detection rotor-position signal is installed in motor, but exist install difficulty, signal link many, to shortcomings such as temperature are more responsive, these shortcomings have limited popularization and the use of brshless DC motor to a certain extent.For this point, people have proposed the control mode of position-sensor-free.At present, without the most ripe also the most frequently used method of transducer Brush-Less DC motor control, be the back electromotive force zero-crossing detection method.By detecting the back electromotive force zero-crossing of unsettled phase, get the position of rotor.In existing implementation method, because motor adopts the PWM chopping regulating speed, so phase voltage is all switching waveform, comprises a large amount of high order harmonic components, therefore after generally adopting and adding resistance and electric capacity and form low pass filter phase voltage is carried out to filtering, then detect the zero crossing of back electromotive force.But the factors such as low-pass filtering phase shift, the time delay error of calculation, armature reaction cause position signalling to produce phase error, affect the runnability of motor, particularly, under motor low cruise state, the position signalling error easily causes commutation failure, cause motor stalling or stall, start unsuccessfully.
Summary of the invention
In order to solve, the sensitivity existed in existing back electromotive force zero cross detection circuit is low, additional phase shift and the shortcoming that easily is disturbed, the present invention proposes back electromotive force zero-crossing detection circuit and the detection method of three-phase direct-current brushless motor, it not only can accurately detect the zero crossing of back electromotive force under the motor lower-speed state, and good in anti-interference performance, can not bring additional phase shift.
The present invention is achieved through the following technical solutions:
The back electromotive force zero-crossing detection circuit of three-phase direct-current brushless motor, characteristics are: comprise current regulator diode, voltage comparator, described current regulator diode comprises the first current regulator diode, the second current regulator diode, the 3rd current regulator diode, the 4th current regulator diode, the 5th current regulator diode, the 6th current regulator diode, the first protection diode, the second protection diode;
Three-phase direct-current brushless motor phase windings first end is connected with the positive pole of the first current regulator diode, the negative pole of the second current regulator diode;
Three-phase direct-current brushless motor phase windings the second end is connected with the positive pole of the 3rd current regulator diode, the negative pole of the 4th current regulator diode;
Three-phase direct-current brushless motor phase windings the 3rd end is connected with the positive pole of the 5th current regulator diode, the negative pole of the 6th current regulator diode;
The positive pole of the negative pole of the positive pole of the negative pole of the positive pole of the negative pole of the first current regulator diode, the second current regulator diode, the 3rd current regulator diode, the 4th current regulator diode, the 5th current regulator diode, the 6th current regulator diode is connected with the in-phase input end of voltage comparator;
The reverse inter-input-ing ending grounding level GND of voltage comparator;
The positive pole of the first protection diode connects the in-phase input end of voltage comparator, and the negative pole of protection diode connects the inverting input of voltage comparator;
The positive pole of the second protection diode connects the inverting input of voltage comparator, and the negative pole of protection diode connects the in-phase input end of voltage comparator.
Described voltage ratio homophase and anti-phase input terminal voltage is between negative 0.7V～positive 0.7V.
When the current regulator diode both end voltage surpasses the starting voltage of current regulator diode, current regulator diode enters the constant current district, and interior resistive is large, makes current regulator diode be operated in constant current state; When the current regulator diode both end voltage is less than starting voltage, current regulator diode is operated in the linear resistance district, its motional impedance value is little and remain unchanged, at this moment the current regulator diode AC impedance is little, three-phase direct-current brushless motor phase windings end three phase winding phase voltages compare with ground level after being superimposed by current regulator diode, and zero crossing is exactly the back electromotive force zero-crossing of unsettled phase.
Compared with prior art, the invention has the beneficial effects as follows: adopt this method to detect the zero crossing of back electromotive force, do not need phase voltage is carried out to low-pass filtering, the problem that can not bring phase place to lag behind, highly sensitive, expanded the detection range of back electromotive force method; The present invention is safe and reliable, and cost is low, and technological means is simple and easy to do, adopts six current regulator diodes and a voltage comparator just can realize.
The accompanying drawing explanation
Fig. 1 is the back electromotive force zero-crossing detection circuit of three-phase direct-current brushless motor of the present invention, is the back electromotive force zero cross detection circuit schematic diagram under lower-speed state.
Embodiment
Below the specific embodiment of the present invention is described in further detail, but embodiments of the present invention are not limited to this.
As shown in Figure 1, the back electromotive force zero-crossing detection circuit of three-phase direct-current brushless motor of the present invention, comprise current regulator diode, voltage comparator, described current regulator diode comprises the first current regulator diode 1, the second current regulator diode 10, the 3rd current regulator diode 2, the 4th current regulator diode 11, the 5th current regulator diode 3, the 6th current regulator diode 12, the first protection diode 4, the second protection diode 5;
Three-phase direct-current brushless motor phase windings first end 7 is connected with the positive pole of the first current regulator diode 1, the negative pole of the second current regulator diode 10; Three-phase direct-current brushless motor phase windings the second end 8 is connected with the positive pole of the 3rd current regulator diode 2, the negative pole of the 4th current regulator diode 11;
Three-phase direct-current brushless motor phase windings the 3rd end 9 is connected with the positive pole of the 5th current regulator diode 3, the negative pole of the 6th current regulator diode 12;
The positive pole of the negative pole of the positive pole of the negative pole of the positive pole of the negative pole of the first current regulator diode 1, the second current regulator diode 10, the 3rd current regulator diode 2, the 4th current regulator diode 11, the 5th current regulator diode 3, the 6th current regulator diode 12 is connected with the in-phase input end of voltage comparator 6;
The reverse inter-input-ing ending grounding level GND of voltage comparator 6;
The positive pole of the first protection diode 4 connects the in-phase input end of voltage comparator 6, and the negative pole of protection diode 4 connects the inverting input of voltage comparator 6;
The positive pole of the second protection diode 5 connects the inverting input of voltage comparator 6, and the negative pole of protection diode 5 connects the in-phase input end of voltage comparator 6.
For existing DC brushless motor PWM chopping regulating speed mode, under motor low cruise state, under most of the time in this time, be that the conducting two-phase is all by the field effect transistor earth level, now smaller, the interference signal of common-mode noise is difficult to coupling and comes in, and detect this time to the back electromotive force zero-crossing of unsettled phase is best.Simultaneously, we take full advantage of the operating characteristic of current regulator diode, current regulator diode (CRD) belongs to two ends junction field constant current device, when the current regulator diode both end voltage surpasses the starting voltage of current regulator diode, current regulator diode enters the constant current district, interior resistive is large, makes current regulator diode be operated in constant current state; When the current regulator diode both end voltage is less than starting voltage, current regulator diode is operated in the linear resistance district, its motional impedance value is little and remain unchanged, therefore at unsettled phase back electromotive force near zero-crossing point, the phase voltage of three phase windings is all very little, the constant current diode works in the linear resistance district, this time, the current regulator diode AC impedance was little, therefore three-phase direct-current brushless motor phase windings first, second, third end 7,8,9 three phase winding phase voltages compare with ground level after being superimposed by current regulator diode, and zero crossing is exactly the back electromotive force zero-crossing of unsettled phase.Because current regulator diode has one-way conduction, therefore need to adopt two reverse parallel connections, guarantee can be realized bidirectional current limiting.Adopt current regulator diode to replace power resistor, have the advantages such as noise is little, volume is little, current limiting characteristic are good, therefore to back electromotive force zero-crossing, detection has brought a lot of benefits, comprises that low noise, sensitivity are high.Because voltage comparator 6 is to be operated in open loop situations; easily because differential mode voltage is excessive, cause voltage comparator 6 to block and can't work; therefore excessive in order to prevent differential mode voltage; added the first protection diode 4 and the second protection diode 5 in voltage ratio than 6 homophase and inverting input, guaranteed that the differential mode voltage size is at negative 0.7V～just between 0.7V.It is strong that this patent circuit has an antijamming capability, the advantage that detection sensitivity is high.
As mentioned above, just can realize preferably the present invention, above-described embodiment is only preferred embodiment of the present invention, not is used for limiting practical range of the present invention; Be that all equalizations of doing according to content of the present invention change and modify, all contained by the claims in the present invention scope required for protection.
Claims (3)
1. the back electromotive force zero-crossing detection circuit of three-phase direct-current brushless motor, it is characterized in that: comprise current regulator diode, voltage comparator, the first protection diode, the second protection diode, described current regulator diode comprises the first current regulator diode, the second current regulator diode, the 3rd current regulator diode, the 4th current regulator diode, the 5th current regulator diode, the 6th current regulator diode;
Three-phase direct-current brushless motor phase windings first end is connected with the positive pole of the first current regulator diode, the negative pole of the second current regulator diode;
Three-phase direct-current brushless motor phase windings the second end is connected with the positive pole of the 3rd current regulator diode, the negative pole of the 4th current regulator diode;
Three-phase direct-current brushless motor phase windings the 3rd end is connected with the positive pole of the 5th current regulator diode, the negative pole of the 6th current regulator diode;
The positive pole of the negative pole of the positive pole of the negative pole of the positive pole of the negative pole of the first current regulator diode, the second current regulator diode, the 3rd current regulator diode, the 4th current regulator diode, the 5th current regulator diode, the 6th current regulator diode is connected with the in-phase input end of voltage comparator;
The reverse inter-input-ing ending grounding level GND of voltage comparator;
The positive pole of the first protection diode connects the in-phase input end of voltage comparator, and the negative pole of the first protection diode connects the inverting input of voltage comparator;
The positive pole of the second protection diode connects the inverting input of voltage comparator, and the negative pole of protection diode connects the in-phase input end of voltage comparator.
2. the detection method of the back electromotive force zero-crossing detection circuit of the described three-phase direct-current brushless motor of claim 1, it is characterized in that following steps: when the current regulator diode both end voltage surpasses the starting voltage of current regulator diode, current regulator diode enters the constant current district, interior resistive is large, makes current regulator diode be operated in constant current state; When the current regulator diode both end voltage is less than starting voltage, current regulator diode is operated in the linear resistance district, its motional impedance value is little and remain unchanged, at this moment the current regulator diode AC impedance is little, three-phase direct-current brushless motor phase windings end three phase winding phase voltages compare with ground level after being superimposed by current regulator diode, and zero crossing is exactly the back electromotive force zero-crossing of unsettled phase.
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3. the detection method of the back electromotive force zero-crossing detection circuit of three-phase direct-current brushless motor according to claim 2 is characterized in that: the homophase of voltage comparator and anti-phase input terminal voltage are between negative 0.7V～positive 0.7V.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011103322056A CN102355184B (en) | 2011-10-27 | 2011-10-27 | Back-EMF (back electromotive force) zero-crossing detection circuit and method for three-phase DC (direct current) brushless motors |
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| Application Number | Priority Date | Filing Date | Title |
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| CN2011103322056A CN102355184B (en) | 2011-10-27 | 2011-10-27 | Back-EMF (back electromotive force) zero-crossing detection circuit and method for three-phase DC (direct current) brushless motors |
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| CN102355184A CN102355184A (en) | 2012-02-15 |
| CN102355184B true CN102355184B (en) | 2013-12-11 |
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| CN106803728B (en) * | 2017-04-13 | 2023-05-05 | 福建星海通信科技有限公司 | Zero-crossing detection circuit of direct-current brushless motor |
| CN106970324A (en) * | 2017-04-25 | 2017-07-21 | 北京太尔时代科技有限公司 | A kind of spacing method for sensing |
| CN107592036B (en) * | 2017-10-23 | 2023-07-18 | 深圳市优必选科技有限公司 | Motor brake circuit and steering engine |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPH0634620B2 (en) * | 1986-08-28 | 1994-05-02 | 三洋電機株式会社 | Brushless motor |
| US7202617B2 (en) * | 2004-04-12 | 2007-04-10 | Delta Electronics, Inc. | Circuit and method for controlling brushless DC motor |
| CN201213247Y (en) * | 2008-05-28 | 2009-03-25 | 常州信息技术学院 | Wide speed precise phase converter for motor without sensor and brush |
| CN202282757U (en) * | 2011-10-27 | 2012-06-20 | 华南理工大学 | Counter electromotive force zero-crossing detection circuit for three-phase direct current brushless motor |
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