KR0171088B1 - Sensorless bldc motor control apparatus - Google Patents

Abstract

The present invention relates to a brushless DC motor, that is, a BLDC motor controller, and the conventional BLDC motor controller is rotated because the position sensor 41 for detecting the position of the rotor is mounted in the air gap between the rotor and the stator. The position sensor 41 is likely to be damaged by the rotor, and a separate signal line and a connector are required to supply the rotor position detection signal of the position sensor 41 to the control means 4. Since a filter for removing noise of a signal line is required, there are many components of a control device, and thus there is a problem in that reliability of operation decreases.

In addition, as a prior art, a sensorless control method for solving the problems of the BLDC motor control apparatus has been provided, and the conventional sensorless control method includes a counter electromotive force (EMF) of each phase (A, B, and C). When detecting the cross point of the neutral voltage, the pulse width modulated voltage supplied from the inverter 2 crosses the neutral voltage, and it is difficult to remove the intersection between the free wheeling and the neutral voltage, and the pure counter electromotive force (EMF) Even if the intersection point with the neutral point voltage is detected, the detected rotation 32 position signal is 30 ° ahead of the actual rotor 32 position, so the phase compensation must be performed using a separate device. There was a problem of becoming complicated.

Therefore, in order to solve the above problems, the present invention senses the rotor position of the BLDC motor by using the line voltage of the BLDC motor without using a physical position sensor in controlling the BLDC motor, and according to the detection result of the BLDC motor Since there is no physical sensor, no wire is needed, and the structure of the product is simplified, and the position of the rotor even when the motor rotates at low speed because the rotor position sensing operation is detected by the integral value of the motor control voltage. The sensorless BLDC motor control device has the effect of improving the reliability of the motor control at low speed since the reliability of the sensing is improved.

Description

Sensorless BLDC Motor Control

1 is a block diagram showing a conventional motor control apparatus.

2 is a circuit diagram showing an equivalent circuit of an inverter and a motor applied to a conventional motor control apparatus.

3 is a view showing the internal structure of a general BLDC motor.

4 is a table showing an inverter driving signal according to the detection signal of the position sensor.

5A to 5E are diagrams for explaining a conventional motor control method of controlling a BLDC motor without a position sensor.

6 is a block diagram showing a sensorless BLDC motor control apparatus of the present invention.

7 is a circuit diagram showing in detail the position sensing unit applied to the present invention.

8 is a circuit diagram showing in detail the pulse width modulator applied to the present invention.

9 (a) to 9 (f) are output waveform diagrams of various parts of the present invention.

* Explanation of symbols for main parts of the drawings

10: position detection unit 20: control unit

30: driving reference signal generator 40: pulse width modulator

50: inverter drive unit

The present invention relates to a brushless DC motor, that is, a BLDC motor control device, and in particular, to control the BLDC motor by detecting the rotor position of the BLDC motor using the line voltage of the BLDC motor without using a physical position sensor. It relates to a sensorless BLDC motor controller for controlling the BLDC motor according to the detection result.

1 through 3 illustrate a conventional BLDC motor control apparatus, and includes a rectifier 1 for rectifying an input AC voltage and a smoothing capacitor C1 for smoothing and directing the voltage rectified by the rectifier 1. And an inverter 2 which converts the DC voltage input from the smoothing capacitor C1 into AC by supplying it to the BLDC motor 3 by operating according to a constant driving signal, and a constant voltage input from the inverter 2. And a constant drive signal for sensing the rotational speed of the BLDC motor 3 and the BLDC motor 3 to generate a constant power and controlling the rotational speed of the BLDC motor 3 according to the detection result. It consists of the motor control means 4 which outputs to the inverter 2.

In addition, the inverter 2 switches on / off according to a driving signal supplied from the motor control means 4 to form a BLDC motor 3 with a DC voltage smoothed by the smoothing capacitor C1 ( It is composed of a plurality of transistors Q1 to Q6 supplied to each of the phases A, B, and C of 32. The BLDC motor 3 generates a constant rotating magnetic field in accordance with a constant power supplied from the inverter 2. It consists of a stator 31 and a rotor 32 which rotates by the rotor field of the stator 31.

The stator 31 is divided into three phases A, B, and C, and coils for generating an electric field are wound around each of the phases A, B, and C.

The control means 4 detects the position of each phase (A, B, C) of the stator 31 when the BLDC motor 3 is driven, and outputs a predetermined signal to the position sensor 41 and the position sensor. The rotation speed of the BLDC motor 3 is sensed from the constant signal output from the 41 and the detection speed is compared with a predetermined speed, and the rotation speed of the BLDC motor 3 is controlled to the desired speed according to the comparison result. The control unit 42 for outputting a predetermined control signal to be able to be made, the information on the position of the rotor 32 output from the position sensor 41 and the control about the motor rotation direction output from the control unit 42 A drive signal generator 43 for generating and outputting a drive signal for controlling on / off control of each transistor Q1 to Q6 of the inverter 2 according to the signal, and outputting from the drive signal generator 43. The pulse width modulated according to the control signal output from the controller 42 A pulse width modulator 44 for outputting and a drive signal output by pulse width modulating the pulse width modulator 44 to the transistors Q1 to Q6 of the inverter 2. It is composed.

Incidentally, reference numerals D1 to D6 described above are diodes.

The operation of the conventional BLDC motor control apparatus configured as described above will be described with reference to FIGS. 1 to 4.

First, when the AC power for driving the BLDC motor 3 is input to the rectifier 1, the rectifier 1 rectifies and outputs the AC power input, the smoothing capacitor (C1) in the rectifier (1) The rectified signal is smoothed and converted into a DC voltage, and the inverter 2 converts the DC voltage smoothed by the smoothing capacitor C1 in accordance with a constant drive signal supplied from the inverter driver 45 of the control means 4. The phases of the stator 31 constituting the BLDC motor 3, i.e., A phase, B phase, and C phase, are supplied to the phase.

As shown in FIG. 2, the inverter 2 includes transistors Q1, Q3 and Q5 connected to the high potential portion of the smoothing capacitor C1 and transistors Q2, Q4 and Q6 connected to the low potential portion. Each pair is supplied one by one to supply a constant AC voltage to each phase (A, B, C) of the stator (310).

On the other hand, as described above, the current flows through the coils wound on the respective phases A, B, and C of the stator 31 constituting the BLDC motor 3, and the magnetic field formed by the above-described current is generated by the motor and the rotor 32. The rotor 32 rotates in synchronism with the rotor field by generating a rotating magnetic field in the air gap between the air gap.

When the rotor 32 is rotated as described above, the position sensor 41 detects the position of the rotor and outputs it to the controller 42 and the drive signal generator 43, and the controller 42 is positioned. The rotational speed of the motor is determined using the information on the position of the rotor input from the sensor 41.

Then, the determined rotational speed is compared with a predetermined target target speed, and a constant control signal for the BLDC motor 3 to rotate at the target speed when an error occurs as a result of the comparison, that is, the motor 3 Information on the rotation direction of the motor and information on the applied voltage of the motor (3) is output.

At this time, the driving signal generator 43 uses the information on the rotation direction of the motor 3 and the position of the rotor 32 to input each transistor Q1 to Q6 of the inverter 2. Generates and outputs a predetermined driving signal to enable the on / off switching operation to the pulse width modulator 44, the pulse width modulator 44 to the voltage applied to the motor (3) input from the controller 42 The pulse width of the driving signal is modulated according to the information and output to the inverter driver 45.

In addition, the inverter driver 45 supplies a pulse width modulated drive signal to each of the transistors Q1 to Q6 of the inverter 2, so that each of the transistors Q1 to Q6 is switched on and off so that the motor 3 AC voltage is supplied to each of the phases A, B, and C of the stator 31 constituting the C), so that the rotor 32 of the motor 3 rotates.

4 is a diagram showing an example of the output signal according to the position detection of the rotor 32 in the position sensor 41 and the drive signal according to the inverter 2, the drive signal according to the detection information of the position sensor 41 Is 1, the corresponding transistors Q to Q6 of the inverter 2 are turned on, and when the drive signal is '0', the corresponding transistors Q1 to Q6 of the inverter 2 are turned off, and as a result, The rotor field is generated by the electric current flowing through the coil of the stator 31 constituting the motor 3, and the rotor 32 rotates.

As described above, the conventional motor control apparatus determines the rotation speed of the motor 3 by using the position information of the rotor 32 detected by the position sensor 41, and determines the determined rotation speed and the pre-programmed target. By comparing the speed and supplying an alternating voltage to each phase (A, B, C) of the stator 31 so that the rotational speed of the motor 3 reaches a predetermined target speed according to the comparison result, The BLDC motor 3 is controlled at the target speed.

However, in the BLDC motor control apparatus as described above, since the position sensor 41 for detecting the position of the rotor is mounted in the air gap between the rotor and the stator, the position sensor 41 may be damaged by the rotating rotor. This high, requires a separate signal line and a connector for the rotor position detection signal of the position sensor 41 to be supplied to the control means 4, and a filter for removing the noise of the signal line There is a problem in that the reliability of the operation is lowered as the components of the control device increases.

In addition, as a conventional technology, a sensorless control method for solving the problem of the BLDC motor control apparatus has been provided, and FIG. 5 is a waveform diagram for explaining a conventional sensorless control method.

(A) (b) (c) of FIG. 5 shows the position of the rotor 32 with respect to each phase A, B and C of the stator 31 detected by the position sensor 41 of the BLDC motor. The position of the rotor 32 with respect to each of the phases A, B, and C has a phase difference of 120 degrees, respectively.

In addition, (d) of FIG. 5 shows a voltage waveform supplied to the stator 31 A, which is divided into a high potential section and a low potential section, each section having a conduction section of 120 ° and pulse width modulation controlled. It consists of a 60 ° rest period, which is a full span, forming a period of 360 °.

FIG. 5E shows the intersection of the counter electromotive force EMF on the stator 31 A phase and the neutral point voltage of each phase A, B, and C. Each phase A, B of the stator 31 is shown in FIG. In (C), back EMF having a phase difference of 120 ° is generated.

FIG. 5 (f) shows the result of detecting the crossing point of the counter electromotive force and the neutral point voltage on the stator 31 A shown in FIG. 5 (e) by the zero cross method. It can be seen that the position signal of the rotor 32 sensed by the phase is 30 ° ahead of the position signal of the rotor 32 shown in FIG.

The reason for detecting the position of the rotor 32 by using the intersection of the counter electromotive force and the neutral point voltage of each phase (A, B, C) is that the voltage supplied to each phase (A, B, C) is not energized. When the phase (A, B, C) voltage is not affected by the voltage supplied from the inverter 2, the phase (A, B, C) voltage of the stator 31 is a motor, that is, the rotor 32 This is because only pure back EMF with position information remains.

(G) of FIG. 5 shows the position signal of the rotor 32 detected by the zero cross method in which the phase signal is 30 ° ahead of the actual rotor 32, so that a phase compensation of 30 ° using a separate timer is performed. It is shown.

As described above, the conventional sensorless control method detects the position of the rotor 32 by detecting a point where the counter electromotive force (EMF) of each phase (A, B, C) and the neutral point voltage cross each other in a zero crossing manner. Then, the motor speed is controlled according to the detected position of the rotor 32.

However, in the conventional sensorless control method as described above, the pulse width modulated voltage supplied from the inverter 2 when the cross point of the counter electromotive force (EMF) of each phase (A, B, C) and the neutral point voltage is detected. It is difficult to remove the intersection between the neutral point voltage and the free wheeling and the neutral point voltage, and the detected rotor 32 position even if the intersection point of the pure back EMF (s) and the neutral point voltage is detected. Since the signal is 30 ° ahead of the actual rotor 32 position, the compensating system has to be complicated by using a separate device.

In addition, by detecting the position of the rotor 32 by using the counter electromotive force (EMF) of each phase (A, B, C), if the rotational speed of the rotor 32 is small, each phase (A, B, C) Since the back EMF (EMF) becomes small, there is a problem in that the position of the rotor 32 cannot be accurately detected when the motor rotates at a low speed.

Accordingly, the present invention has been made to solve the above problems, in the control of the BLDC motor, the position of the rotor of the BLDC motor is sensed using the line voltage of the BLDC motor without using a physical position sensor, and the detection result It is an object of the present invention to provide a BLDC motor control device for controlling a BLDC motor.

Figure 6 shows the sensorless BLDC motor control apparatus of the present invention for achieving the above object, and the control voltage output from the inverter 2 and supplied to each phase (A, B, C) of the stator (31) From the position detecting unit 10 for detecting the position of the rotor 32 of the motor 3 using the neutral point voltage of the motor 3, and from the position signal of the rotor 32 detected by the position detecting unit 10 It detects the rotational speed of the BLDC motor 3 and compares the detection speed with a predetermined predetermined speed so that the rotational speed of the BLDC motor 3 can be controlled to the desired speed according to the comparison result. The inverter 20 can be controlled according to the control unit 20 for outputting, the position signal of the rotor 32 output from the position detecting unit 10 and the control signal for the motor rotation direction output from the control unit 20. Generates driving reference signal to generate and output driving reference signal And a pulse width modulated by the driving reference signal output from the driving reference signal generator 30 in accordance with a control signal (voltage control signal, enable signal) output from the controller 20. A pulse width modulator 40 and an inverter driver 50 for outputting a drive signal pulse-width modulated by the pulse width modulator 40 to the inverter 2.

The operation of the sensorless BLDC motor control apparatus of the present invention configured as described above is as follows.

First, the position sensing unit 10 uses the control voltages VA, VB, and VC supplied from the inverter 2 to the motor 3 and the neutral point voltage VN of the motor 3. Detecting the position of the rotor 32 with respect to the phase (A, B, C), and outputs the detected position signal of the rotor 32 to the control unit 20 and the drive signal generator 30, respectively, The control unit 20 determines the current rotation speed of the motor 3 by the position signal of the rotor 32, and the motor direction control signal, the pulse width modulation enable signal, and the voltage control required for the motor speed control according to the determined rotation speed. Output the signal.

In addition, the driving reference signal generator 30 receives the rotor 32 position signal sensed and output from the position sensing unit 10 and a direction control signal output from the controller 20 to drive the inverter 2. A driving reference signal is generated and output to the pulse width modulator 40, and the pulse width modulator 40 controls the driving reference signal of the inverter 2 output from the driving reference signal generator 30 to the controller 20. The pulse width modulated according to the voltage control signal and the enable signal of the output to the inverter driver 50.

Then, the inverter driver 50 drives the inverter 2 by outputting a drive signal that is pulse width modulated by the pulse width modulator 40 to the inverter 2 to drive the inverter 2, thereby forming a stator constituting the motor 3 ( The control voltages VA, VB, and VC supplied to each of the phases A, B, and C of FIG. 31 are controlled.

7 is a detailed view illustrating the position sensing unit 10 applied to the present invention, wherein the control voltage VA supplied to the A phase of the stator 31 constituting the motor 3 and the neutral point voltage of the motor 3 are illustrated in FIG. A control voltage supplied to the first position detector 11 for detecting the rotor position with respect to the B phase of the stator 31 and the B phase of the stator 31 constituting the motor 3 using VN. A second position detector 12 which detects the rotor position with respect to the C phase of the stator 31 by using the neutral point voltage VN of the motor 3 and the stator 31 constituting the motor 3. The third position detector 13 detects the rotor position of the stator 31 with respect to the A phase by using the control voltage VC supplied to the C phase of the motor and the neutral point voltage VN of the motor 3. do.

Each of the position detectors 11 to 13 integrates an integrator 111 for integrating the control voltages VA, VB, and VC input according to a predetermined integration coefficient, and an integral of the integrator 111. The control voltages VA, VB and VC are compared by comparing the resistors R10 and capacitor C10 that determine coefficients with the control voltages VA, VB and VC integrated in the integrator 111 and the neutral point voltage VN. The comparator 112 outputs a section higher than the neutral point voltage VN as a rotor position signal, wherein R11 to R13, which are not described, are resistors, and D10 and D11 are diodes.

The operation of the position sensing unit 10 configured as described above is as follows.

Before describing the operation of the position sensing unit 10, the waveforms shown in FIG. 9 will be described. In FIG. 9 (a), (b) and (c), each image (A, B) of the stator 31 is illustrated. Is a waveform diagram showing the actual position of the rotor 32 with respect to (C), and (d) of FIG. 9 is a control supplied from the inverter 2 to the A phase of the stator 31 by the motor control apparatus of the present invention. FIG. 9E is a waveform diagram showing the result of integrating the control voltage VA as shown in FIG. 9D, and FIG. 9E is a waveform diagram showing the voltage VA. (f) is a waveform diagram showing a comparison result of the comparator 112 comparing the integration result of the control voltage VA with the neutral point voltage VN.

Referring to FIG. 9, the operation of the position sensor 10 applied to the present invention will be described as follows.

First, the first position detector 11 of the position sensing unit 10 receives a control voltage VA such as (d) of FIG. 9 which is output from the inverter 2 and supplied to the A phase of the stator 31. Detecting the position of the rotor 32 with respect to the B phase of the stator 31 through a predetermined operation and comparison process, the operation thereof will be described in more detail, the integrator 111 constituting the first position sensor 11 Integrates the input control voltage VA according to a predetermined integral value determined by the resistor R10 and the capacitor C10, and outputs a signal as shown in FIG. 9E, and the comparator 112 outputs a motor 3. Compare the signal integrated in the integrator 111 with the neutral point voltage (VN) of the circuit, and the interval of the level of the signal integrated in the integrator 111 is higher than the neutral point voltage (VN). The position signal of the former 32 is output.

The position signal of the rotor 32 with respect to the phase B of the stator 31 output from the comparator 112 of the first position sensor 11 is the same as in FIG. 9 (f), and in the comparator 112 The output position signal of the rotor 32 is substantially the same as the actual position of the rotor 32 with respect to the B phase of the stator 31 shown in FIG.

However, if you look closely, the position signal of the rotor 32 as shown in (f) of FIG. 9 sensed by the comparator 112 of the first position sensor 11 is similar to that of the actual rotor 32 as shown in FIG. The position (P) (DIR 3 °) ahead of the position, which helps to control the motor (3) because the position of the rotor 32 is detected a little earlier than the actual rotor 32 is located. .

In addition, the second position detector 12 of the position sensing unit 10 performs the control voltage VB supplied to the B phase of the stator 31 through a predetermined calculation and comparison process as described above to determine the stator 31. The position signal of the rotor 32 with respect to the C phase is detected, and the third position detector 13 calculates and compares the control voltage VC supplied to the C phase of the stator 31 as described above. Through this, the position signal of the rotor 32 with respect to the A phase of the stator 31 is detected.

As described above, the position signal of the rotor 32 for each of the phases A, B, and C of the stator 31 detected by the position sensors 11 to 13 of the position sensing unit 10 is a driving reference signal generator. The driving reference signal generator 30 may be supplied to 30 to generate a driving reference signal for driving the inverter 2.

For reference, the driving reference signal generated by the driving reference signal generator 30 has the control voltages VA, VB, and VC supplied to the phases A, B, and C of the stator 31 having a high potential (+). ) And a low potential (-), the driving reference signal for driving the inverter (2) for supplying the control voltage (VA, VB, VC) to each phase (A, B, C) of the stator (31) It is also classified into A +, A-, B +, B-, C +, and C- (see also figure 8).

8 illustrates an embodiment of the pulse width modulator 40 constituting the present invention, and includes a waveform generator 401 for generating a reference wave for pulse width modulation, and the waveform generator 401. The comparator 402 for generating and outputting a pulse having a certain duty by comparing the reference wave generated from the voltage control signal input from the control unit 20 and the enable signal input from the control unit 20 ( E) an OR gate 403 for performing an OR operation on the output pulses of the comparator 402 and outputting the result, and a NOT gate 404 for inverting the output pulse of the OR gate 403; The pulse width modulated for driving the inverter 2 by performing an AND operation on the output pulse of the OR gate 403 and the high potential driving reference signals A +, B +, and C + output from the driving reference signal generator 30. Multiple anns that output high potential drive signals (A +, B +, C +), respectively The gates 405A, 405B, and 405C, the output pulses of the sickle gate 404 and the low potential driving reference signals A-, B-, and C- output from the driving reference signal generator 30 are respectively logically multiplied. And a plurality of end gates 406A, 406B, and 406C which calculate and output pulse width modulated low potential drive signals A-, B-, and C- for driving the inverter 2.

When the operation of the configured pulse width modulator 40 is briefly described, the comparator 402 compares a reference waveform generated by the waveform generator 401 with a voltage control signal input from the controller 20 to obtain a predetermined duty. Generates a pulse, and the OR gate 403 performs a logical OR operation on the pulse generated by the comparator 402 and the enable (E) signal output from the controller 20 to generate a predetermined pulse as a reference for pulse width modulation. A pulse having a width is generated, and the sickle gate 404 inverts the pulse output from the OR gate 403 and outputs it to one input terminal of the AND gates 406A, 406B, and 406C.

The enable signal E output from the controller 20 is a pulse in which the ratio between the high state and the low state is always half and half.

The AND gates 405A, 405B, and 405C perform an AND operation on the pulses output from the OR gate 403 and the high potential driving reference signals A +, B +, and C + output from the driving reference signal generator 40. And output pulse width modulated high potential drive signals A +, B +, and C + for driving the inverter 2, respectively, and the remaining AND gates 406A, 406B, and 406C are output from the OR gate 403. Pulse width modulated for driving the inverter 2 by performing an AND operation on the pulse inverted at 404 and the low potential driving reference signals A-, B-, and C- output from the driving reference signal generator 40. The low potential driving signals A-, B-, and C- are outputted, respectively.

Accordingly, the high potential and low potential driving signals A +, A-, B +, and B output from the AND gates 405A, 405B, 405C, 406A, 406B, and 406C constituting the pulse width modulator 40. -, C +, C- is supplied to the inverter 2 through the inverter driver 50, so that the motor supplied from the inverter 2 to each phase (A, B, C) of the stator 31 of the motor (3) The control voltages VA, VB and VC are output.

FIG. 9 (d) shows the motor control voltage VA of the inverter 2 controlled by the pulse width modulator 40, and is divided into a conduction section of 120 ° and a non-conduction section of 60 °, respectively. It is divided into a true high potential section and a low potential section, and each energization section is divided into a pulse width modulation-controlled pulse width modulation section (PWM) and a normal ON section.

In addition, the pulse width modulation section (PWM) and always on (ON) section also occupies ½ of each conduction section.

That is, the purpose of configuring the pulse width modulator 40 as described above is the control voltage (VA, VB) supplied from the inverter 2 to each phase (A, B, C) of the stator 31 of the motor (3) , VC) as shown in (d) of FIG. 9 so that the conduction section of the high potential section and the low potential section is composed of ½ pulse width modulation section (PWM) and always on (ON) section by the control voltage (VA, VB) In order to prevent off-set from occurring at the output of the integrator 111 of the position sensor 10 integrating, VC).

The reason why the enable signal E output from the controller 20 is always half of the high state and the low state is also in order to prevent an offset from occurring in the output of the integrator 111 of the position sensor 10. will be.

As described above, the present invention detects the rotor position of the BLDC motor by using the line voltage of the BLDC motor without controlling the physical position sensor in controlling the BLDC motor, and controls the BLDC motor according to the detection result. Since there is no physical sensor, no wires are needed, and the structure of the product is simplified, and the rotor position sensing operation is detected by the integral value of the motor control voltage. Since the reliability is improved, the sensorless BLDC motor controller has an effect of improving the reliability of the motor control at low speed rotation.

Claims (6)

In the motor driving device for driving the motor 3 by using the control voltage output from the inverter 2, the control voltage output from the inverter 2 and supplied to the motor 3 and the neutral point voltage of the motor 3 Position sensing unit 10 for detecting the position of the rotor of the motor (3) by using, and the rotational speed of the motor (3) from the rotor position signal detected by the position sensing unit 10 to detect the speed In the control unit 20 and the position detecting unit 10 for outputting a predetermined control signal for controlling the rotational speed of the motor 3 to the desired speed according to the comparison result compared to the predetermined predetermined speed A drive reference signal generator 30 for generating and outputting a drive reference signal for controlling the inverter 2 according to the output rotor position signal and a control signal for the motor rotation direction output from the controller 20; The driving reference signal generator 30 And a pulse width modulator 40 for outputting a pulse width modulated according to the control signal (voltage control signal, enable signal E) output from the controller 20, and the pulse width modulator. A sensorless BCD motor control device, comprising: an inverter driver 50 for driving an inverter 2 with a drive signal output by pulse width modulation at 40; The stator (31) according to claim 1, wherein the position sensor (10) uses the control voltage (VA) supplied to the A phase of the stator constituting the motor (3) and the neutral point voltage (VN) of the motor (3). The first position detector 11 for detecting the position of the rotor with respect to the B phase of the control panel, the control voltage VB supplied to the B phase of the stator constituting the motor 3 and the neutral point voltage VN of the motor 3. Of the second position detector 12 for detecting the rotor position with respect to the C phase of the stator, and the control voltage VC supplied to the C phase of the stator constituting the motor 3 and the motor 3. A sensorless BLC motor control device, comprising a third position detector (13) for sensing the rotor position with respect to A phase of the stator using a neutral point voltage (VN). The integrator 111 according to claim 2, wherein each of the position detectors 11 to 13 integrates the motor 3 control voltages VA, VB, and VC input according to a predetermined integration coefficient. A resistor R10 and a capacitor C10 for determining an integral coefficient of the 111 and a control voltage VA, VB, VC and the neutral point voltage VN integrated in the integrator 111 are compared to control voltage VA, A sensorless BLC motor control device, characterized in that the comparator 112 for outputting a section of the VB, VC higher than the neutral point voltage (VN) as a rotor position signal. The waveform generator of claim 1, wherein the pulse width modulator 40 is input from a waveform generator 401 for generating a reference wave for pulse width modulation, and a reference wave generated from the waveform generator 401 and a controller 20. Comparing the voltage control signal to be generated to generate a pulse having the appropriate duty and outputs, and the enable signal (E) input from the control unit 20 and the output pulse of the comparator 402 An ora gate 403 for outputting the result, a not gate 404 for inverting an output pulse of the ora gate 403, an output pulse of the ora gate 403 and a driving reference signal generator Computing the high potential driving reference signals A +, B +, and C + output from (30), respectively, and outputting pulse width modulated high potential driving signals A +, B +, and C + for driving the inverter 2, respectively. A plurality of AND gates 405A, 405B, and 405C and output pulses of the sickle gate 404 And a plurality of end gates 406A, 406B, and 406C outputting the low potential driving reference signals A-, B-, and C- output from the driving reference signal generator 30. DC motor control device. The pulse width modulation section of claim 1 or 4, wherein the pulse width modulation section 40 converts the energization section between the high potential section and the low potential section of the control voltages VA, VB, and VC supplied from the inverter to the motor. Sensorless BLC motor controller, characterized in that the (PWM) and always on (ON) section is configured by ½. 5. The pulse width modulator 40 of claim 1, wherein the pulse width modulator 40 integrates the control voltages VA, VB, and VC supplied from the inverter 2 to the motor 3. A sensorless BLDC motor controller, which includes all devices to prevent off-sets from occurring at the integrator 111 output.