CN102355184A - 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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- CN102355184A CN102355184A CN2011103322056A CN201110332205A CN102355184A CN 102355184 A CN102355184 A CN 102355184A CN 2011103322056 A CN2011103322056 A CN 2011103322056A CN 201110332205 A CN201110332205 A CN 201110332205A CN 102355184 A CN102355184 A CN 102355184A
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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 be meant the 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 the direct detection rotor position signalling of Hall element is installed in motor; But exist difficult installation, signal link many, to temperature shortcoming such as sensitivity relatively, these shortcomings have limited the popularization and the use of brshless DC motor to a certain extent.To this point, people have proposed the control mode of position-sensor-free.At present, the most ripe also the most frequently used method of no transducer dc brushless motor control is the back electromotive force zero-crossing detection method.Through detecting the back electromotive force zero-crossing of unsettled phase, get access to the position of rotor.In existing implementation method; Because motor adopts the PWM chopping regulating speed, so phase voltage all is switching waveform, comprises a large amount of high order harmonic components; Therefore generally adopt add resistance and phase voltage carried out filtering with electric capacity formation low pass filter after, detect the zero crossing of back electromotive force again.But factors such as LPF phase shift, the time-delay error of calculation, armature reaction cause position signalling to produce phase error; Influence the runnability of motor, particularly under motor low cruise state, the position signalling error causes commutation failure easily; Cause motor stall or stall, start failure.
Summary of the invention
The sensitivity that exists in the existing back electromotive force zero cross detection circuit is low in order to solve, additional phase shift and the shortcoming that is subject to disturb; The present invention proposes the 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 realizes through following technical proposals:
The back electromotive force zero-crossing detection circuit of three-phase direct-current brushless motor; Characteristics are: comprise current regulator diode, voltage comparator, said current regulator diode comprises first current regulator diode, 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 links to each other with the positive pole of first current regulator diode, the negative pole of second current regulator diode;
Three-phase direct-current brushless motor phase windings second end links to each other 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 links to each other 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 first current regulator diode, 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.
Said voltage ratio homophase and inverting input voltage is between negative 0.7V～positive 0.7V.
When the current regulator diode voltage surpassed the starting voltage of current regulator diode, current regulator diode got into the constant current district, and it is big that internal resistance becomes, and makes current regulator diode be operated in constant current state; When current regulator diode voltage during 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, and three-phase direct-current brushless motor phase windings end three phase winding phase voltages are done comparison with ground level after being superimposed through 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, need not carry out LPF, can not bring the problem of phase lag phase voltage, 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.
Description of drawings
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 the lower-speed state.
Embodiment
Following specific embodiments of the invention is done further detailed explanation, but execution mode of the present invention is not limited thereto.
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, said current regulator diode comprises first current regulator diode 1, 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 links to each other with the positive pole of first current regulator diode 1, the negative pole of second current regulator diode 10; Three-phase direct-current brushless motor phase windings second end 8 links to each other 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 links to each other 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 first current regulator diode 1, 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.
To existing dc brushless motor PWM chopping regulating speed mode; Under motor low cruise state; Be that conducting two all is through the FET earth level mutually under most of the time in this time; Smaller, the interference signal of common-mode noise this moment is difficult to coupling comes in, and detect the back electromotive force zero-crossing of unsettled phase this time is best.Simultaneously; We make full use of the operating characteristic of current regulator diode; Current regulator diode (CRD) belongs to two ends junction field constant current device, and when the current regulator diode voltage surpassed the starting voltage of current regulator diode, current regulator diode got into the constant current district; It is big that internal resistance becomes, and makes current regulator diode be operated in constant current state; When current regulator diode voltage during less than starting voltage; Current regulator diode is operated in the linear resistance district; Its motional impedance value is little and remain unchanged, and 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, so three-phase direct-current brushless motor phase windings first, second, third end 7,8,9 three phase winding phase voltages do comparison with ground level through current regulator diode after being superimposed, and zero crossing is exactly the back electromotive force zero-crossing of unsettled phase.Because current regulator diode has unidirectional conducting, therefore need to adopt two reverse parallel connections, could guarantee to realize bidirectional current limiting.Adopt current regulator diode to replace power resistor, have advantages such as noise is little, volume is little, current limiting characteristic are good, therefore detection has brought a lot of benefits to back electromotive force zero-crossing, comprises that low noise, sensitivity are high.Because voltage comparator 6 is to be operated in open loop situations; Being prone to cause because of differential mode voltage is excessive voltage comparator 6 to block can't operate as normal; 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 the 0.7V.It is strong that this patent circuit has an antijamming capability, the advantage that detection sensitivity is high.
As stated, can realize preferably that just the present invention, the foregoing description are merely preferred embodiment of the present invention, be not to be used for limiting practical range of the present invention; Be that all equalizations of doing according to content of the present invention change and modification, all contained by claim of 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, said current regulator diode comprises first current regulator diode, 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 links to each other with the positive pole of first current regulator diode, the negative pole of second current regulator diode;
Three-phase direct-current brushless motor phase windings second end links to each other 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 links to each other 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 first current regulator diode, 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.
2. the detection method of the back electromotive force zero-crossing detection circuit of the said three-phase direct-current brushless motor of claim 1; It is characterized in that following steps: when the current regulator diode voltage surpasses the starting voltage of current regulator diode; Current regulator diode gets into the constant current district; It is big that internal resistance becomes, and makes current regulator diode be operated in constant current state; When current regulator diode voltage during 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, and three-phase direct-current brushless motor phase windings end three phase winding phase voltages are done comparison with ground level after being superimposed through current regulator diode, and zero crossing is exactly the back electromotive force zero-crossing of unsettled phase.
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: said voltage ratio homophase and inverting input voltage is between negative 0.7V～positive 0.7V.
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| 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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| 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 true CN102355184A (en) | 2012-02-15 |
| CN102355184B CN102355184B (en) | 2013-12-11 |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106803728A (en) * | 2017-04-13 | 2017-06-06 | 福建星海通信科技有限公司 | A kind of zero cross detection circuit of DC brushless motor |
| CN107592036A (en) * | 2017-10-23 | 2018-01-16 | 深圳市优必选科技有限公司 | Motor brake circuit and steering engine |
| WO2018196177A1 (en) * | 2017-04-25 | 2018-11-01 | 北京太尔时代科技有限公司 | Limit sensing method |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0634620B2 (en) * | 1986-08-28 | 1994-05-02 | 三洋電機株式会社 | Brushless motor |
| CN1684355A (en) * | 2004-04-12 | 2005-10-19 | 台达电子工业股份有限公司 | 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 |
-
2011
- 2011-10-27 CN CN2011103322056A patent/CN102355184B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0634620B2 (en) * | 1986-08-28 | 1994-05-02 | 三洋電機株式会社 | Brushless motor |
| CN1684355A (en) * | 2004-04-12 | 2005-10-19 | 台达电子工业股份有限公司 | 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 |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106803728A (en) * | 2017-04-13 | 2017-06-06 | 福建星海通信科技有限公司 | A kind of zero cross detection circuit of DC brushless motor |
| 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 |
| WO2018196177A1 (en) * | 2017-04-25 | 2018-11-01 | 北京太尔时代科技有限公司 | Limit sensing method |
| CN107592036A (en) * | 2017-10-23 | 2018-01-16 | 深圳市优必选科技有限公司 | Motor brake circuit and steering engine |
| 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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