KR101686345B1 - Circuit for detecting back-emf and driver for sensorless brushless direct current motor - Google Patents

Circuit for detecting back-emf and driver for sensorless brushless direct current motor Download PDF

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Publication number
KR101686345B1
KR101686345B1 KR1020150128303A KR20150128303A KR101686345B1 KR 101686345 B1 KR101686345 B1 KR 101686345B1 KR 1020150128303 A KR1020150128303 A KR 1020150128303A KR 20150128303 A KR20150128303 A KR 20150128303A KR 101686345 B1 KR101686345 B1 KR 101686345B1
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KR
South Korea
Prior art keywords
counter electromotive
electromotive force
voltage difference
phase coil
motor
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KR1020150128303A
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Korean (ko)
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공경철
이명석
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서강대학교산학협력단
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
    • H02P6/14—Electronic commutators
    • H02P6/16—Circuit arrangements for detecting position
    • H02P6/18—Circuit arrangements for detecting position without separate position detecting elements
    • H02P6/182—Circuit arrangements for detecting position without separate position detecting elements using back-emf in windings
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/175—Indicating the instants of passage of current or voltage through a given value, e.g. passage through zero

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Control Of Motors That Do Not Use Commutators (AREA)

Abstract

The present invention relates to a counter electromotive force detection circuit, and an apparatus for controlling a drive of a sensorless brushless direct current motor, which mate a phase change time of a sensorless brushless direct current motor and a zero-crossing time of a counter electromotive force of a three-phase coil, and reduce a noise caused by a change of a switching device of an inverter.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a back electromotive force detection circuit and a sensorless brushless DC motor drive control device using the same,

One embodiment of the present invention relates to a back electromotive force detection circuit and a sensorless DC motor drive control device using the same.

Generally, a brushless direct current motor is a brushless direct current motor in which an electric rectifier is installed without a brush and a commutator, A current is applied to a stator made of a winding according to an electronic position to generate a magnetic flux, thereby rotating the rotor. As a result, the speed of the rotor in the motor can be controlled, and mechanical noise caused by the friction between the brush and the commutator of the conventional DC motor as well as electrical noise is not generated.

In order for the brushless DC motor to realize the above-described function, it is necessary to grasp the position of the rotor, that is, the permanent magnet. The position of the rotor can be detected using a magnetic flux sensor such as a Hall sensor. Each of the three hall sensors is disposed at an interval of 120 degrees electrically around the rotor to detect the position of the rotor. And determines an operation period required for continuous rotation of the rotor by using the position information of the rotor detected by the hall sensor, thereby selecting two phases to which current is to flow, The inverter is energized. During operation of such a brushless DC motor, only two phases of the three-phase windings are excited at all times, and the remaining phases of the three phases are not excited and are floating.

However, due to problems such as price, size, reliability, or usage environment of motor system, sensorless brushless direct current motor which drives brushless direct current motor without using sensor has been developed.

A method of driving a sensorless brushless DC motor is to detect a zero crossing point (ZCP) of the counter electromotive force opposite to the electromotive force generated by the current flowing in the stator winding of the motor, and use this as a phase current switching point It is widely used.

However, the method of detecting and driving the zero crossing point of the counter electromotive force is difficult to control the sensorless brushless DC motor due to the phase difference between the zero crossing point and the phase switching point, and it is impossible to drive the sensorless brushless DC motor, There is a problem in that it is deteriorated.

In order to solve this problem, there is employed a method in which the difference in the counter electromotive force between phases is the same as the phase change point of a general brushless DC motor using a Hall sensor, and a method in which the counter electromotive force is delayed by 30 ° from the point at which the counter electromotive force is detected.

However, the above-mentioned methods have problems in that the zero-crossing point does not exactly coincide with the phase change point of a general brushless DC motor due to the noise generated when the switching element connected to the stator winding of the sensorless brushless DC motor is activated or deactivated, There is a problem that the computation and signal detection in the intersection point detection process are complicated and the efficiency of the sensorless brushless DC motor for the purpose of low cost and structural simplicity is rather reduced.

The main object of the present invention is to improve the driving efficiency of the sensorless brushless direct current motor by matching the zero crossing point of the back electromotive force with the phase switching point and to reduce the output torque ripple and to reduce the noise generated upon detection of the back electromotive force of the sensorless brushless DC motor And a sensorless brushless DC motor drive control device using the same.

A counter electromotive force detecting unit for detecting a counter electromotive force generated in a three-phase coil of a sensorless brushless DC motor and outputting a voltage difference of the counter electromotive force according to an embodiment of the present invention; And a controller for controlling driving of the sensorless brushless DC motor using the zero crossing point, wherein the counter electromotive force detecting unit detects each of the counter electromotive forces generated in any two coils of the three-phase coils And outputs the voltage difference of the detected two counter electromotive forces. The control unit outputs the drive signal of the sensorless brushless direct current motor to the phase change point of the rotor of the sensorless brushless DC motor can do.

In the present invention, the counter electromotive force detecting unit may include a filtering unit that receives the respective counter electromotive forces generated in any two coils of the three-phase coils and removes noise of the counter electromotive forces, and a controller that subtracts the counter electromotive forces And a compensator for outputting the voltage difference, wherein the voltage difference may be the phase change point of the rotor.

In the present invention, the filtering unit may be two low-pass filters for removing the impulse-like noise generated when the sensorless brushless DC motor is driven.

In the present invention, the compensator may be a differential generator that subtracts each of the counter electromotive forces generated in the two coils to generate the voltage difference.

In the present invention, one low-pass filter of the two low-pass filters has its input connected to one of the three phases, its output connected to the input of the compensating unit, and the other low- An input terminal thereof may be connected to one of the phases of the remaining two phases of the three phases, and an output terminal thereof may be connected to an input terminal of the compensation unit.

In the present invention, the compensation unit may further include a potentiometer for adjusting an offset value of the voltage difference generated by the differential synchronization.

In the present invention, the potentiometer may comprise a variable resistor, and an operational amplifier electrically connected to the variable resistor and adjusting an offset of the differential signal according to a resistance value of the variable resistor.

In the present invention, when the three-phase coil is a u, v, w phase coil, the counter electromotive force detecting unit detects the counter electromotive forces generated in the u-phase coil and the v-phase coil, Phase coil and the w-phase coil; a first counter-electromotive force detecting unit for subtracting a counter electromotive force of the v-phase coil from the v-phase coil to output a first voltage difference; A second counter electromotive force detecting section for subtracting the counter electromotive force of the coil and outputting a second voltage difference; and a second counter electromotive force detecting section for detecting the counter electromotive forces generated in the w-phase coil and the u-phase coil and for detecting a counter electromotive force of the w- And a third counter electromotive force detecting unit for outputting a third voltage difference.

In the present invention, the zero-crossing point detecting unit may detect the zero-crossing points in which the values of the first voltage difference, the second voltage difference, and the third voltage difference are zero.

In the counter electromotive force detection circuit for detecting a counter electromotive force generated in a three-phase coil of a sensorless brushless DC motor according to an embodiment of the present invention, the counter electromotive force generated in any two coils of the three- And a compensator for outputting a voltage difference by subtracting the noises from the back electromotive force, wherein a time when the voltage difference becomes zero is referred to as a time point of the sensorless brushless DC motor It can be provided as the phase change point of the former.

In the present invention, the filtering unit may be two low-pass filters for removing the impulse-like noise generated when the sensorless brushless DC motor is driven.

In the present invention, the compensator may be a differential generator that subtracts each of the counter electromotive forces generated in the two coils to generate the voltage difference.

In the present invention, one low-pass filter of the two low-pass filters has its input connected to one of the three phases, its output connected to the input of the compensating unit, and the other low- An input terminal thereof may be connected to one of the phases of the remaining two phases of the three phases, and an output terminal thereof may be connected to an input terminal of the compensation unit.

In the present invention, the compensation unit may further include a potentiometer for adjusting an offset value of the voltage difference generated by the differential synchronization.

In the present invention, the potentiometer may comprise a variable resistor, and an operational amplifier electrically connected to the variable resistor and adjusting an offset of the differential signal according to a resistance value of the variable resistor.

According to an embodiment of the present invention, the driving efficiency of the sensorless brushless DC motor can be improved, the output torque ripple can be reduced, and the back electromotive force noise can be eliminated.

1 is a block diagram schematically showing a sensorless brushless DC motor drive control apparatus according to an embodiment of the present invention.
2 is a block diagram schematically showing the counter electromotive force detection unit shown in FIG.
3 is a configuration diagram showing an embodiment of a counter electromotive force detecting unit shown in FIG.
4 is a circuit diagram showing an embodiment of the counter electromotive force detecting unit shown in FIG.
5 (a) is a graph showing a phase transition point of a brushless DC motor using a hall sensor and a zero crossing point of a counter electromotive force in a conventional sensorless brushless DC motor.
5 (b) is a graph showing the relationship between the phase change point of the brushless DC motor using the hall sensor and the back electromotive force of the sensorless brushless direct current motor provided with the sensorless brushless DC motor drive control device according to the embodiment of the present invention And a zero crossing point.
6 is a graph showing the counter electromotive force generated in one phase of the sensorless brushless DC motor.

While the present invention has been described in connection with certain exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and similarities. It should be understood, however, that the invention is not to be limited to the specific embodiments, but includes all changes, equivalents, and alternatives falling within the spirit and scope of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description of the present invention, detailed description of related arts will be omitted when it is determined that the gist of the present invention may be unnecessarily blurred. In addition, numbers used in the description process of the present invention (e.g., first second, etc.) may be identifier signals for distinguishing one component from another.

Also, in this specification, when an element is referred to as being "connected" or "connected" with another element, the element may be directly connected or directly connected to the other element, As long as the opposite substrate does not exist, it may be connected or connected via another component in the middle.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram schematically showing an apparatus 100 for driving a sensorless brushless DC motor according to an embodiment of the present invention.

1, a sensorless brushless DC motor drive control apparatus 100 according to an embodiment of the present invention includes an inverter 110, a logic controller 120, a counter electromotive force detection unit 130, and a main controller 140, ≪ / RTI >

The inverter 110 receives a DC voltage through a power supply (not shown) and applies the DC voltage to each phase of the sensorless brushless DC motor 10 through a switching operation. When the inverter 110 is connected to the three-phase sensorless brushless direct-current motor 10, the inverter 110 can be composed of six switching elements, and two pairs of switching elements form a pair of sensorless brushless direct- (U-phase, V-phase, W-phase) of the sensorless brushless DC motor 10 by the switching operation of the switching element, and the DC voltage is applied to each phase of the sensorless brushless DC motor 10, The DC motor 10 is rotated.

The inverter 110 may be an electronic switching device such as a MOSFET, an IGBT, or the like as an embodiment.

The logic controller 120 can control the switching operation (on / off) of the inverter 110. [ More specifically, the logic controller 120 receives from the main controller 140 a motor control signal capable of controlling the rotation of the rotor of the sensorless brushless DC motor 10, (ON / OFF) of the inverter 110 so that the rotor can be rotated according to the motor control signal, which is applied to the less brushless DC motor 10.

When the inverter 110 is an electronic switching device such as a MOSFET, an IGBT or the like, the logic controller 120 for applying the voltage to the gate electrode of the electronic switching device such as a MOSFET, an IGBT, The inverter 110 can be controlled.

The logic controller 120 may be implemented as a control chip such as a micro controller unit (MCU) or a digital signal processor (DSP) together with the main controller 140 as an embodiment, Which may be implemented separately from the main controller 140 and comprise a plurality of logic gates. A logic controller having a plurality of logic gates receives a motor control signal from the main controller 140 and generates an inverter control signal for driving the sensorless brushless direct current motor 10 through the operation of the logic gates, It is possible to control the drive of the sensorless brushless DC motor 10 by applying a control signal to the inverter 110. [

The counter electromotive force detecting unit 130 detects a counter electromotive force generated in the three-phase coil (U phase, V phase, W phase) of the sensorless brushless DC motor 10 and subtracts the counter electromotive force to generate a voltage difference. Specifically, the counter electromotive force detecting unit 130 detects the counter electromotive force generated in any two of the three-phase coils, that is, the U-phase coil and the V-phase coil, or the V- and W- And outputs the voltage difference by subtracting the detected two counter electromotive forces. The voltage difference generated by the counter electromotive force detecting unit 130 is input to the zero crossing point detecting unit 141. The zero crossing point detecting unit 141 detects the zero crossing point of the voltage difference and outputs the zero crossing point to the sensorless brushless DC motor 10 ) Can be determined as the phase change point of the rotor of the rotor. This will be described later.

2 is a block diagram schematically showing an embodiment of a counter electromotive force detecting unit shown in FIG.

Referring to FIG. 2, the counter electromotive force detecting unit 130 may include a first counter electromotive force detecting unit 130a, a second counter electromotive force detecting unit 130b, and a third counter electromotive force detecting unit 130c. When the three-phase coil of the sensorless brushless DC motor 10 is a U-phase coil, a V-phase coil and a W-phase coil, the counter electromotive force detecting unit 130 detects the first counter electromotive force detecting unit 130a, the second counter electromotive force detecting unit 130b, And a third counter electromotive force detecting unit 130c.

The first counter electromotive force detecting unit 130a detects the counter electromotive forces generated in the U phase coil and the V phase coil and subtracts the counter electromotive force of the U phase coil and the counter electromotive force of the V phase coil to output the first voltage difference The second counter electromotive force detecting unit 130b detects the counter electromotive forces generated in the V-phase coil and the W-phase coil, subtracts the counter electromotive force of the V-phase coil and the counter electromotive force of the W- The third counter electromotive force detecting unit 130c detects the counter electromotive forces generated in the W phase coil and the U phase coil and subtracts the counter electromotive force of the W phase coil and the counter electromotive force of the U phase coil, Can be output.

3 is a configuration diagram showing an embodiment of a counter electromotive force detecting unit shown in FIG. Each of the first, second, and third counter electromotive force detecting units 130a, 130b, and 130c may be a counter electromotive force detecting unit shown in FIG.

3, the counter electromotive force detecting unit 130 according to an exemplary embodiment of the present invention may include a filtering unit 131 and a compensating unit 134. The counter electromotive force detecting unit 130 may include a three-phase coil The back electromotive force can be detected.

The filtering unit 131 may receive the counter electromotive force generated by any two of the three-phase coils and may remove the noise of the counter electromotive forces.

More specifically, the filtering unit 131 is connected to any two of the three-phase coils of the sensorless brushless DC motor. When the switching elements provided in the inverter are switched during operation of the sensorless brushless DC motor, Phase coil of the sensorless DC motor 10 connected to the switching element when the switching element is switched from ON to OFF (deactivated) or from OFF to ON (when activated) Noise in the back electromotive force can be removed.

A counter electromotive force generated in the three-phase coil has the switching device is disabled, as shown in FIG. 6, the counter electromotive force appears as (or activated) (e tr) and a counter electromotive force due to the change in magnetic flux caused by rotation of the permanent magnet of the rotor (e p ). The back electromotive force (e p ) generated due to the flux change of the rotor contributes to the generation of the trapezoidal waveform, and the position of the permanent magnet can be indirectly measured by detecting the zero crossing point by the generated back electromotive force. However, the counter electromotive force (e tr ) that appears when the switching element is inactivated can be regarded as a noise component as a component that distorts a trapezoidal waveform in the form of an impulse. The filtering unit 131 of the present invention can remove the counter electromotive force (e tr ) that appears when the switching device is inactivated.

The filtering unit 131 may include a first low-pass filter 132 and a second low-pass filter 133 as an example. The first low-pass filter 132 and the second low-pass filter 133 may be low-pass filters. The first low-pass filter 132 and the second low-pass filter 133 may be connected to different ones of the three-phase coils of the sensorless brushless DC motor.

For example, the input terminal of the first low-pass filter 132 may be connected to the U-phase coil, and the output terminal may be connected to the input terminal of the compensation unit 134. At this time, the first low-pass filter 132 can remove the impulse noise generated in the counter electromotive force of the U-phase coil when the switching element provided in the inverter is switched when the sensorless brushless DC motor is driven.

The second low-pass filter 133 has an input terminal connected to the V-phase coil and an output terminal connected to the input terminal of the compensation unit 134. At this time, the second low-pass filter 133 can remove the impulse-shaped noise generated in the counter electromotive force of the V-phase coil when the switching element provided in the inverter is switched when the sensorless brushless DC motor is driven.

Similarly, when the first low-pass filter 132 is connected to the V-phase coil, the second low-pass filter 133 is connected to the W-phase coil. When the first low-pass filter 132 is connected to the W- 2 low-pass filter 133 is connected to the V-phase coil to remove the noise generated by the operation of the switch element upon detection of the counter electromotive force.

The compensation unit 134 can output the voltage difference by subtracting the counter electromotive forces from which the filtering unit 131 removes the noise.

More specifically, the compensation unit 134 removes the impulse-shaped noise of the counter electromotive force generated in the two coils connected to the filtering unit 131 when the filtering unit 131 drives the sensorless brushless DC motor, The voltage difference between the back electromotive force generated in the two coils can be outputted.

The compensation unit 134 may output the voltage difference of the counter electromotive forces by subtracting the noise elimination counter electromotive forces by the filtering unit 131. [ The compensating unit 134 may include a differential amplifier 135 and a potentiometer 136 as one embodiment.

The difference generator 135 may generate the voltage difference by subtracting each of the counter electromotive forces generated in the two coils.

Specifically, the difference generator 135 receives the counter electromotive force from which the noise of the impulse type is removed by the first low-pass filter 132 and the second low-pass filter 133 of the filtering unit 131, It is possible to generate a voltage difference.

For example, the difference signal generator 135 may be configured such that the first low-pass filter 132 and the second low-pass filter 133 filter the counter electromotive force of the U-phase coil and the V-phase coil to remove the impulse- Phase coil and the counter electromotive force of the V-phase coil to generate a voltage difference between the counter electromotive force of the U-phase coil and the counter electromotive force of the V-phase coil, and transmit the voltage difference to the potentiometer 136.

The potentiometer 136 may adjust the offset value of the voltage difference generated by the differential amplifier 135, and may include a variable resistor and an operational amplifier.

More specifically, the potentiometer 136 receives a voltage difference between the counter electromotive force of the U-phase coil and the counter electromotive force of the V-phase coil from the differential lock 135. Specifically, for example, The voltage difference between the counter electromotive force of the U-phase coil and the counter electromotive force of the V-phase coil is received and the potentiometer 136 adjusts the offset value of the differential locker 135 in accordance with the resistance value of the variable resistor 122a .

4 is a circuit diagram showing an embodiment of the counter electromotive force detecting unit shown in FIG.

Referring to FIG. 4, the counter electromotive force detection circuit 130 according to an embodiment of the present invention may include a filtering unit 131 and a compensation unit 134.

The filtering unit 131 may receive the counter electromotive force generated by any two of the three-phase coils and may remove the noise of the counter electromotive forces.

Specifically, when the sensorless brushless DC motor is driven, the filtering unit 131 removes the impulse-like noise generated in the counter electromotive force of one of the two coils when the switching device provided in the inverter is switched. 1 low-pass filter 132 and a second low-pass filter 133 for removing the impulse-like noise generated in the counter electromotive force of the other one of the two coils.

For example, the first low-pass filter 132 may be connected to the U-phase coil of the input stage 111a, and the output stage 111b may be connected to the input stage 121a of the differential amplifier 135. At this time, the first low-pass filter 132 can remove the impulse noise generated in the counter electromotive force of the U-phase coil when the switching element provided in the inverter is switched when the sensorless brushless DC motor is driven.

The input terminal 112a of the second low-pass filter 133 is connected to the V-phase coil and the output terminal 112b of the second low-pass filter 133 is connected to the input terminal 121b of the differential amplifier 135. At this time, the second low-pass filter 133 can remove the impulse-shaped noise generated in the counter electromotive force of the V-phase coil when the switching element provided in the inverter is switched when the sensorless brushless DC motor is driven.

The compensation unit 134 can output the voltage difference by subtracting the counter electromotive forces from which the filtering unit 131 removes the noise.

More specifically, the compensation unit 134 removes the impulse-shaped noise of the counter electromotive force generated in the two coils connected to the filtering unit 131 when the filtering unit 131 drives the sensorless brushless DC motor, The voltage difference between the back electromotive force generated in the two coils can be outputted.

The compensation unit 134 may comprise a differential amplifier 135 and a potentiometer 136.

The difference generator 135 may generate the voltage difference by subtracting each of the counter electromotive forces generated in the two coils.

More specifically, the differential amplifier 135 is connected between the output terminal 111b of the first low-pass filter 132 and the input terminal 121a of the differential amplifier 135 of the filtering unit 131, and the second low- And the input terminal 121b of the differential amplifier 135 may be connected to the output terminal 112b. The difference generator 135 may receive the counter electromotive force obtained by removing the noise of the impulse type at the input terminals 121a and 121b, respectively, and subtract the noise eliminating counter electromotive force to generate the voltage difference between the two counter electromotive forces.

For example, the difference signal generator 135 may be configured such that the first low-pass filter 132 and the second low-pass filter 133 filter the counter electromotive force of the U-phase coil and the V-phase coil to remove the impulse- The voltage difference between the counter electromotive force of the U-phase coil and the counter electromotive force of the V-phase coil is generated and subtracted from the counter electromotive force of the U-phase coil and the counter electromotive force of the V-phase coil to be input to the potentiometer 136 .

The potentiometer 136 may adjust the offset value of the voltage difference generated by the differential amplifier 135 and may include a variable resistor 122a and an operational amplifier 122b.

More specifically, for example, the potentiometer 136 receives the voltage difference between the counter electromotive force of the U-phase coil and the counter electromotive force of the V-phase coil from the differential lock 135, and the potentiometer 136 detects the resistance value of the variable resistor 122a The offset (value) of the differential sync 135 can be adjusted according to the offset value.

The conventional sensorless brushless DC motor detects the phase change point of the rotor as the zero crossing point of the counter electromotive force generated in the stator made of the coil. However, since there is a phase difference of 30 ° between the phase transition point of the rotor and the zero crossing point of the back electromotive force, it is difficult to control the sensorless brushless DC motor, and the zero crossing point of the counter- There is a problem that the driving efficiency of the sensor less brushless DC motor is lowered when the less DC motor is driven.

In order to solve such a problem, a method of delaying the back electromotive force by 30 degrees from the point of time when the back electromotive force is detected has been applied.

However, in the above method, the zero-crossing point of the counter electromotive force due to the impulse noise generated when the switching element connected to the stator winding of the sensorless brushless direct current motor is activated or deactivated, And there is a problem that the efficiency of the sensorless brushless DC motor for the purpose of low cost and structural simplicity is rather reduced.

However, according to an embodiment of the present invention, the counter electromotive force detection unit 130 of the sensorless brushless DC motor includes a filtering unit 131 including a first low-pass filter 132 and a second low-pass filter 133 Bar and sensorless brushless DC motors connected to two coils of the three-phase coils, it is possible to eliminate impulse noise generated when the inverter of the sensorless brushless DC motor is switched. The differential amplifier 135 of the unit 134 subtracts the two counter electromotive forces from which the noise is removed, and outputs a voltage difference. Here, since the time point at which the voltage difference becomes zero coincides with the phase change point of the rotor of the sensorless brushless DC motor, there is no delay time which is a time difference between the zero crossing point and the phase switching point of the counter electromotive force So that the driving efficiency of the sensorless brushless DC motor can be increased.

The main controller 140 detects the zero crossing point of the counter electromotive force generated in the three-phase coil of the sensorless brushless DC motor 10 and detects the zero crossing point of the counter electromotive force as the phase change point of the rotor of the sensorless brushless DC motor 10, It is possible to output a signal for controlling the less brushless DC motor. That is, the main controller 140 receives the voltage difference from the counter electromotive force detector 130, detects the zero crossing point of the voltage difference, determines the zero crossing point of the detected voltage difference as the phase switching point of the rotor, And outputs a motor control signal for controlling the driving of the lef DC motor, and the motor control signal may be input to the logic controller 120.

The main controller 140 may include a zero intersection detecting unit 141, a controller 142, and a PWM (Pulse Width Modulation) generating unit 143 as an embodiment.

The zero-crossing point detecting unit 141 may detect a zero crossing point that is a zero point of the voltage difference by analyzing the voltage difference of the counter electromotive forces transmitted from the counter electromotive force detecting unit 130.

Specifically, the zero-crossing point detection unit 141 receives the voltage difference generated by subtracting the counter electromotive force of any two of the three-phase coils from the counter electromotive force detection unit 130, detects the zero crossing point where the voltage difference crosses the zero point, And can be applied to the controller 140.

For example, when the three-phase coil is the U-phase coil, the V-phase coil, and the W-phase coil, the zero-crossing point detection unit 141 detects the counter electromotive force of the U- And a zero crossing point where the first voltage difference crosses a zero point by receiving the subtracted first voltage difference.

The zero crossing point detecting unit 141 receives the second voltage difference obtained by subtracting the counter electromotive force of the V-phase coil from the counter electromotive force of the W-phase coil from the second counter electromotive force detecting unit 130b and outputs a zero crossing point at which the second voltage difference crosses the zero point Can be detected.

The zero crossing point detection unit 141 receives the third voltage difference obtained by subtracting the counter electromotive force of the W phase coil from the counter electromotive force of the U phase coil from the third counter electromotive force detection unit 130c and calculates a zero crossing point at which the third voltage difference crosses the zero point Can be detected.

The zero-crossing point detecting unit 141 may be formed of a single control chip together with the main controller 140, and may be formed as a separate chip from the main controller 140 as another embodiment.

The control unit 142 receives the zero crossing point at which the voltage difference of the counter electromotive force generated by each of the two coils among the three-phase coils crosses the zero point from the zero crossing point detecting unit 141 and outputs the zero crossing point as the phase switching point And generates a PWM signal through the PWM generator 143 using the phase change point to supply a motor control signal to the logic controller 120 so as to control the phase change of each phase (U, V, W phase) Can be output.

5 is a graph showing a zero crossing point of a counter electromotive force in a sensorless brushless DC motor including a conventional sensorless brushless DC motor and a sensorless brushless DC motor drive control device according to an embodiment of the present invention . 5 (a) is a graph showing a phase transition point of a brushless DC motor using a hall sensor and a zero crossing point of a counter electromotive force in a conventional sensorless brushless DC motor. FIG. 5 (b) And a sensorless brushless direct current (DC) motor drive control device according to an embodiment of the present invention, and a zero crossing point of a counter electromotive force in a sensorless brushless DC motor.

5 (a) and 5 (b), the horizontal axis represents the phase change point and the vertical axis represents the magnitude of the voltage.

5 (a) and 5 (b), the counter electromotive force generated in the three-phase coil of the conventional sensorless brushless direct current motor is expressed by the following equation 5 (a), and the graph of the counter electromotive force of the sensorless brushless DC motor drive control apparatus 100 according to the embodiment of the present invention is shown in the following three graphs of FIG. 5 (b) .

5 (b), the voltage difference output by the first counter electromotive force detecting unit 130a is e u -e v obtained by subtracting the counter electromotive force e u of the U phase coil and the counter electromotive force e v of the V phase coil, (130b) has a voltage difference output is e v -e w less the counter-electromotive force e v and e w W counter electromotive force of the coil of the V phase coil, and the third counter electromotive force detecting voltage differences (130c), the output is the W-phase coil E w -e u obtained by subtracting the counter electromotive force e w of the U-phase coil and the counter electromotive force e u of the U phase coil.

5A, the counter electromotive force of the conventional sensorless brushless direct-current motor is changed from the phase change point (time point when H is changed to L or L is changed to H) of Hall sensor A, Hall sensor B, Hall sensor C, .

However, the sensorless brushless direct current motor using the sensorless brushless direct current motor drive control device 100 according to the embodiment of the present invention has a structure in which, as shown in FIG. 5 (b) The zero crossings of the voltage differences match.

It is difficult to control the sensorless brushless DC motor because of the phase difference between the zero crossing point of the counter electromotive force and the phase switching point and the sensorless brushless DC motor is not capable of driving the sensorless brushless DC motor, A problem has occurred.

In order to solve this problem, there is employed a method in which the difference in the counter electromotive force between phases is the same as the phase change point of a general brushless DC motor using a Hall sensor, and a method in which the counter electromotive force is delayed by 30 ° from the point at which the counter electromotive force is detected.

However, in the above methods, the zero-crossing point of the counter electromotive force due to the impulse noise generated when the switching element connected to the stator winding of the sensorless brushless direct current motor is activated or deactivated, And there is a problem that the efficiency of the sensorless brushless DC motor for the purpose of low cost and structural simplicity is rather reduced.

However, in the sensorless brushless DC motor drive control apparatus 100 according to the embodiment of the present invention, the counter electromotive force detecting unit 130 is connected to two coils of the three-phase coil of the sensorless brushless DC motor 10 When the sensorless brushless DC motor 10 is driven, noise of an impulse type generated when a switching element provided in the inverter 110 is converted is subtracted to subtract the two counter electromotive forces from the noise, Can be output.

The zero crossing point detecting unit 141 detects a zero crossing point at which the voltage difference crosses the zero point and applies the zero crossing point to the main controller 140. The main controller 140 uses the zero crossing point to detect the zero crossing point of the sensorless brushless DC motor 10 can be driven to generate a drive signal for driving the sensorless brushless direct-current motor 10.

Since the time point at which the voltage difference becomes zero coincides with the phase change point of the rotor of the sensorless brushless DC motor and there is no delay time which is a time difference between the zero crossing point and the phase switching point of the counter electromotive force, The efficiency of driving a less brushless DC motor can be increased.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention.

Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments.

The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

100: Sensorless brushless DC motor drive control device
110: Inverter
120: Logic controller
130: a back electromotive force detecting section
140: Main controller
141: Zero crossing point detector

Claims (15)

A counter electromotive force detecting unit detecting a counter electromotive force generated in a three-phase coil of a sensorless brushless DC motor and outputting a voltage difference of the counter electromotive force;
A zero crossing point detecting unit for detecting a zero crossing point at which the voltage difference crosses a zero point; And
A controller for controlling driving of the sensorless brushless direct current motor using the zero crossing point; And,
Wherein the counter electromotive force detecting unit detects each of the counter electromotive forces generated in any two coils among the three-phase coils and outputs the voltage difference of the detected two counter electromotive forces, and the controller sets the zero crossing point to the sensorless brushless And outputs a drive signal of the sensorless brushless direct current motor at a phase change point of the rotor of the direct current motor,
Wherein the counter electromotive force detecting unit comprises: a filtering unit for receiving each of the counter electromotive forces generated in any two coils of the three-phase coils and for eliminating noise of the counter electromotive forces; and a subtracter for subtracting the noises from the counter electromotive forces, And a compensation unit,
A time when the voltage difference becomes zero is set as a phase change point of the rotor,
Wherein the compensation unit comprises a difference generator for subtracting each of the counter electromotive forces generated in the two coils to generate the voltage difference and a potentiometer for adjusting an offset value of the voltage difference generated by the differential coils DC motor drive control device. delete The method according to claim 1,
Wherein the filtering unit is two low-pass filters for removing the impulsive noise generated when the sensorless brushless DC motor is driven. delete The method of claim 3,
The low pass filter of one of the two low pass filters has its input connected to one of the three phases and its output connected to the input of the compensator. And the output terminal is connected to the input terminal of the compensation unit. The apparatus according to claim 1, delete The method according to claim 1,
The potentiometer may include:
Variable resistor; And
An operational amplifier electrically connected to the variable resistor and adjusting an output gain of the voltage difference according to a resistance value of the variable resistor; Wherein the sensorless brushless direct current motor drive control device comprises: The method according to claim 1,
When the three-phase coil is a u, v, w phase coil, the counter electromotive force detecting unit
A first counter electromotive force detecting unit detecting the counter electromotive forces generated in each of the u-phase coil and the v-phase coil and subtracting a counter electromotive force of the u-phase coil and a counter electromotive force of the v-phase coil to output a first voltage difference;
A second counter electromotive force detecting unit detecting the counter electromotive forces generated in each of the v-phase coil and the w-phase coil and subtracting a counter electromotive force of the v-phase coil and a counter electromotive force of the w-phase coil to output a second voltage difference; And
A third counter electromotive force detecting unit detecting the counter electromotive forces generated in each of the w-phase coil and the u-phase coil and subtracting a counter electromotive force of the w-phase coil and a counter electromotive force of the u-phase coil to output a third voltage difference; Wherein the sensorless brushless direct current motor drive control device comprises: 9. The method of claim 8,
Wherein the zero crossing point detecting unit detects the zero crossing point at which the values of the first voltage difference, the second voltage difference, and the third voltage difference become zero. A counter electromotive force detecting circuit for detecting a counter electromotive force generated in a three-phase coil of a sensorless brushless DC motor,
A filtering unit for receiving each of the counter electromotive forces generated in any two of the three-phase coils and removing noise of the counter electromotive forces; And
And a compensator for subtracting the counter electromotive forces from which the noise is removed to output a voltage difference,
The time point at which the voltage difference becomes zero is provided as a phase change point of the rotor of the sensorless brushless DC motor,
Wherein the compensation unit comprises a difference generator for subtracting each of the counter electromotive forces generated in the two coils to generate the voltage difference and a potentiometer for adjusting an offset value of the voltage difference generated by the differential coils Back electromotive force detection circuit. 11. The method of claim 10,
Wherein the filtering unit is two low-pass filters for removing the impulse-like noise generated when the sensorless brushless DC motor is driven. delete 12. The method of claim 11,
The low pass filter of one of the two low pass filters has its input connected to one of the three phases and its output connected to the input of the compensator. And the output terminal is connected to the input terminal of the compensation unit. delete 11. The method of claim 10,
The potentiometer may include:
Variable resistor; And
An operational amplifier electrically connected to the variable resistor and adjusting an output gain of the voltage difference according to a resistance value of the variable resistor; And a back electromotive force detection circuit for detecting a back electromotive force.
KR1020150128303A 2015-09-10 2015-09-10 Circuit for detecting back-emf and driver for sensorless brushless direct current motor KR101686345B1 (en)

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KR20140073141A (en) * 2012-12-06 2014-06-16 삼성전기주식회사 Apparatus and method for motor drive control, and motor using the same
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KR101199634B1 (en) * 2011-07-15 2012-11-08 충남대학교산학협력단 Method and apparatus for controling 3-phase brushless dc motor
KR20140073141A (en) * 2012-12-06 2014-06-16 삼성전기주식회사 Apparatus and method for motor drive control, and motor using the same
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021253562A1 (en) * 2020-06-17 2021-12-23 北京航空航天大学宁波创新研究院 Commutation error compensation system and method without position sensor for brushless motor
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