JPH08256496A - Inverter controller for sensorless and brushless dc motor - Google Patents

Abstract

PURPOSE: To provide smooth operation even without using a sensor by controlling the driving of an inverter circuit based on the information of the rotator position and angular speed estimated from the operation of estimated information, and current information sent from a current detection means. CONSTITUTION: To a power source 1, a converter circuit 2 for sending DC output by rectifying and smoothing AC input AC input through a diode and a capacitor is connected. To an inverter circuit 3 connected to an output end, each two of six (6) transistors Q1-Q6 are connected in series, and a bridge connection is made to make a mutual junction between respective transistors serve as an output end. The position information, angular information and current information of a stator computed by the operation through the respective estimated operation means 17, 19, 20 of an operation device 16 are outputted to a PWM drive controller 18, converted into 3-phase voltage type sine wave approximation PWM signal and outputted to a power transistor circuit 22 to output a drive signal to the inverter circuit 3 and control driving of the respective transistors Q1-Q5. It is thus possible to provide smooth operation with high efficiency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a permanent magnet for a rotor and controls the phase of voltage and current applied to a stator winding wound around a stator core to obtain a rotating magnetic field. A brushless DC motor that can drive a brushless DC motor without using a position detecting sensor including a Hall element for detecting the rotational position of the rotor is used.
The present invention relates to an inverter control device for a C motor.

[0002]

2. Description of the Related Art Today, brushless DC motors are used in a wide range of fields including room air conditioners and office automation equipment. This brushless DC motor (hereinafter, simply referred to as a DC motor) theoretically has a small secondary copper loss and has good controllability, and therefore its range of use is steadily expanding. However, in the DC motor, a conventional DC motor mechanically performs commutation, whereas an electric switch is used to perform commutation to drive a synchronous motor. The commutation action needs to be performed so that it can be operated most efficiently, but in the permanent magnet type synchronous motor, the commutation timing is uniquely determined by the position of the magnetic poles of the permanent magnets constituting the rotor. It is determined.

Therefore, a sensor for detecting the magnetic pole position is indispensable for driving the DC motor. As the sensor, a hall element, an optical element, or a position detector such as an encoder or a resolver is generally used. However, when the sensor is used, not only becomes a major factor that hinders downsizing of the DC motor, but also from the sensor. Since it also requires a signal line for transmitting the signal of
The DC motor has problems in terms of manufacturing cost, reduction in size and weight, reliability, and the like.

Therefore, recently, various sensorless brushless DC motors have been proposed without specially providing a sensor for detecting the magnetic pole position, that is, a sensor is not required. This detects the position of the rotor based on the induced voltage (terminal voltage) generated in the stator winding of the DC motor,
By controlling the drive of the inverter circuit based on the position detection result, the phase of the voltage / current applied to the DC motor is controlled. A sensorless brushless DC motor that detects a magnetic pole position by directly utilizing an induced voltage generated in a stator winding of a DC motor without using a sensor such as the Hall element is disclosed in Japanese Patent Publication No.
It is disclosed in Japanese Patent No. 30157.

Next, an example in which the rotor position detecting device for the sensorless brushless DC motor is applied to, for example, a three-phase brushless DC motor will be described with reference to FIGS. In FIG. 11, a converter circuit 10 is configured to rectify and smooth an AC input to a commercial AC power supply 101 via a power factor improving reactor 103 with a diode and a capacitor to, for example, a voltage doubler to output a DC output V _DC.
2 is connected to the output terminal of the converter circuit 102, and 6
Transistors Qu, Qx, Qv, Qy, Qw, Qz
2 arms for each (Qu, Qx, Qv, Qy, Q
w, Qz) connected in series, and further connected in a bridge form to connect an inverter circuit 104 having a connection point between transistors of each arm (for example, a connection point between Qu and Qx) as an output end. , The DC input V _DC is converted into a three-phase AC output by energizing the transistors Qu to Qz at 120 ° for a suitable time, and the stator winding Su is star-connected.
A three-phase brushless motor (hereinafter simply referred to as a DC motor) 105 including Sv, Sw and a permanent magnet type rotor R is sent to each phase of the stator windings Su, Sv, Sw to drive the DC motor 105. .

The stator windings Su, Sv, Sw
To each phase of the capacitor C, Cv, Cw, which has one end star-connected and is grounded with this as a neutral point, is connected to the other ends via resistors Ru, Rv, Rw, respectively.
Outputs obtained by shifting the input phase as a phase voltage into a substantially triangular wave with a phase delay of 90 ° from the connection points of u, Cv, Cw and the resistances Ru, Rv, Rw (for example, the connection points of Cu and Ru). By comparing the output of each of the phase circuits 106 and the neutral point voltage, the comparators CPu and CPu
From the output terminals of v and CPw, rectangular wave signals U ₀ , V ₀ and W ₀ having a phase difference of 120 ° are obtained with a duty ratio of 50%,
A position detection circuit 108 is formed by the comparison circuit 107 that sends this as a position detection signal, and the comparison circuit 10
7 position detection signals U ₀ , V ₀ and W ₀ are combined by a logic circuit to form a transistor Qu of the inverter circuit 104.
~ Qz is sequentially conducted by 120 ° (for example, Qu → Qz → Qv →
The output signal of the distribution circuit 109 adapted to output the output signal (in the order of Qx → Qw → Qy) is sent to the base drivers BDu to BDz connected to the bases of the transistors Qu to Qz via the buffer circuit 110. Then
The transistors Qu to Qz are sequentially turned on to 120 °
It is configured to be energized.

In the above rotor position detecting device, when a DC motor equipped with a permanent magnet type rotor is rotated, a change in the magnetic flux of the rotor interlinking with the stator winding is caused in the stator winding. Induced voltage (that is, in response to rotation) is generated, and when three-phase AC power is applied to the stator winding by a 120 ° conduction type inverter circuit, the waveform of the phase voltage becomes
As shown in (1) of FIG. 12, during the half cycle, 120 °
Minute energization area part by the transistor of the inverter circuit, this energization area part, and 30 before and after this energization area part
An induced voltage of 60 ° is obtained.

The induced voltage of 60 ° appears as a part of the sinusoidal induced voltage having a frequency and voltage according to the rotation speed when the DC motor serves as a generator when the transistor is not energized. Focusing on the fact that the position of the rotor can be detected by detecting the zero-cross point of the induced voltage, the phase voltage can be calculated as shown in (2) of FIG.
As shown by, by converting to a triangular wave-shaped output having a 90 ° phase delay and comparing this output with a zero potential, a rectangular wave position detection signal having a 90 ° phase delay with respect to the phase voltage is obtained ( (3) in FIG. 12, the central portion 12 of the induced voltage phase from the distribution circuit 109 by the combination of these signals.
An output signal ((4) in FIG. 12) is provided to secure the energization area of each transistor at 0 ° and sequentially energize each of the transistors Qu to Qz at 120 °.

[0009]

However, in the rotor position detecting device having the above structure, for example, a 4-pole sensorless brushless having a permanent magnet type rotor having two N poles and two S poles, respectively. In the DC motor, the voltage vector applied to the stator winding of the DC motor has an electrical angle of 6
Since the machine angle changes only by 30 ° in increments of 0 °, that is, because the transistor of the inverter circuit is energized by 120 °, the rotor has only 12 rotation vectors during one revolution. Therefore, in this type of DC motor, pulsation occurs during operation and torque ripple is increased, which causes a large vibration and noise with the operation of the DC motor.

In the above 120 ° energizing method,
Since there is a commutation action in which the current flowing phase switches every 60 ° in terms of electrical angle, torque ripple is likely to occur, and at the time of commutation, the current of the phase that has been flowing until then becomes zero. Since there is a three-phase flow mode in which the return current and the rising current in the switched phase flow, the drive torque of the DC motor in this three-phase flow mode is determined by the sum of both currents, and therefore the inverter circuit When the commutation action delays the rise of the current due to the inductance of the stator winding, the sum of the two currents drops, which causes a problem that the torque ripple becomes large.

In order to solve the above noise problem, for example, an anti-vibration rubber member may be interposed between the rotor and the rotor shaft, or the rotor shaft and the rotor shaft may be connected to the rotor shaft. With the increase in the number of parts, measures have been taken such as connecting the members with a vibration-isolating viscous coupling and further enclosing the DC motor itself with a mat member having excellent sound absorption. Not only the productivity of the DC motor is lowered, but also the manufacturing cost of the DC motor is remarkably increased, which makes it difficult to manufacture the DC motor economically.

In addition, in the above-mentioned 120 ° energization type sensorless brushless DC motor, as described above, since the voltage vector that changes by 60 ° in electrical angle is applied to the stator winding, the highest efficiency point is obtained. That is, it is difficult to operate the DC motor at any maximum torque point. Therefore, as a means for compensating for the shortage of the output torque, for example, by increasing the diameter of the rotor or increasing the number of windings of the stator winding, the size of the DC motor can be increased. Although it is possible to obtain it, the DC motor itself becomes large in size, and the material cost becomes unnecessarily high, so that the range of use is limited and the manufacturing cost is increased. Moreover, as the size of the DC motor itself becomes larger, the current capacity to carry the current will inevitably increase.
It is also necessary to take measures against heat generation of the motor, and there is a problem that it takes more time and cost when manufacturing this type of DC motor.

The present invention has been made in view of the above various problems.
Induction voltage information estimated from output values of voltage and current detection means at the same time as rotating a rotor made of a permanent magnet by performing approximate sine wave PWM energization between three phases of a stator winding of a three-phase brushless DC motor Based on the above, the rotational position of the rotor and the rotational speed (angular velocity) of the rotor are respectively calculated by estimation calculation processing, and the estimated rotational position and angular velocity information indicating the rotational position and angular velocity of the rotor are calculated. 3 each
P with built-in phase voltage type sine wave approximate PWM signal generation circuit
The sine wave approximation PWM signal is output to the inverter circuit from the PWM drive control device.
A sensorless brushless that enables smooth drive control of the inverter circuit to operate the sensorless brushless DC motor at a rotation speed based on the target speed command signal and without a sensor (sensorless) even when the motor is running at low speed. It is to provide an inverter control device for a DC motor.

[0014]

In order to solve the above-mentioned problems, the present invention provides a three-phase brushless D comprising a stator winding and a rotor having a permanent magnet.
A C motor, and voltage and current detection means for detecting voltage and current from two phases of the stator winding, respectively.
Induction voltage estimation calculation means for calculating the induced voltage information estimated from the output values of the voltage and current detection means, and rotor position information and rotor angular velocity estimated using the output values from the induction voltage estimation calculation means. An estimated information arithmetic processing device including a rotor position estimation arithmetic means for arithmetically processing information and a rotor angular velocity estimation arithmetic means, and an estimated rotor position and angular velocity information and current detection from the estimated information arithmetic processing device. It is characterized in that the inverter circuit is drive-controlled by the current information sent from the means.

According to a second aspect of the invention, a three-phase brushless DC motor comprising a stator winding and a rotor provided with a permanent magnet, and a voltage and a current are respectively detected from two phases of the stator winding. The voltage and current detection means, the induced voltage estimation calculation means for calculating the induced voltage information estimated from the output values of the voltage and current detection means, and the output value from the induced voltage estimation calculation means are estimated. An estimated information arithmetic processing device including a rotor position estimation arithmetic means for arithmetically processing rotor position information and rotor angular velocity information and a rotor angular velocity estimation arithmetic means, and an estimated rotation from the estimated information arithmetic processing device. The child position and angular velocity information and the current information sent from the current detecting means are output to a PWM drive control device having a built-in three-phase voltage-type sine wave approximate PWM signal generating circuit, Outputs sine wave approximation PWM signal by the child position information and angular velocity information in the inverter circuit from the PWM drive control device, characterized by being adapted to drive control by the sine wave approximation PWM signal the inverter circuit.

According to the third aspect of the present invention, the induced voltage estimation calculation means provided in the estimation information calculation processing device reduces the feedback gain when the rotor angular velocity is low, and conversely, when the rotor angular velocity is high, feedback is performed. It is characterized in that means for increasing the gain is provided.

[0017]

According to the present invention, the induced voltage generated during the operation of the sensorless brushless DC motor is estimated and calculated with reference to the three-phase AC power that is actually applied to the sensorless brushless DC motor, and is calculated by the estimation calculation. Based on the estimated information of the induced voltage, the rotor position and the rotor angular velocity are estimated and calculated, and a three-phase voltage sine wave approximate PWM signal is calculated based on the estimated position information and angular velocity of the rotor. Since the sensorless brushless DC motor is configured to generate and control the drive of the inverter circuit, the sensorless brushless DC motor has a high efficiency in operating the sensorless brushless DC motor based on voltage and current information during actual operation. The operating information that can be driven by is estimated and calculated in advance, and the inverter circuit is driven and controlled based on the estimated and calculated operating information. Because it is, the operation of the sensorless brushless DC motor to follow the speed command becomes possible to operate with high efficiency.

Further, according to the present invention, based on the voltage and current information supplied to the sensorless brushless DC motor as described above, information on the rotor position and angular velocity for operating the sensorless brushless DC motor with high efficiency is provided. Since the sensorless brushless DC motor can be operated based on the estimated and calculated information, the detection member such as a Hall element for detecting the rotational position of the rotor is not required, and the sensorless brushless DC motor is not required. High-efficiency operation can be softly followed while the motor is running.
This is convenient because the adverse effect on the operation of the C motor can be significantly reduced. Moreover, since the above estimated information can be dealt with by software using a microcomputer,
There is also an advantage that this type of DC motor can be manufactured compactly and lightly and economically.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.
This will be described below. FIG. 1 is a block diagram showing the overall configuration of an inverter control device for a sensorless brushless DC motor according to the present invention. In FIG. 1, reference numeral 1 denotes a commercial AC power source, to which a converter circuit 2 configured to rectify and smooth an AC input by a diode and a capacitor and send a DC output is connected. Reference numeral 3 denotes an inverter circuit connected to the output terminal of the converter circuit 2, and the inverter circuit 3 includes six transistors Q ₁
Each of two to Q ₆ is connected in series, and further connected in a bridge shape so that the connection point of each transistor (for example, the connection point of Q ₁ and Q ₂ ) is formed as an output terminal. the transistors Q ₁ to Q ₆ as appropriate on - is driven controlled by the oFF signal, converts the DC power into three-phase AC power, which, for example, stator windings 4u was star-connected, 4v, 4w and the permanent magnet It consists of a rotor 5 in the shape of
For example, a 3-phase sensorless brushless DC motor (hereinafter referred to as 3
(Referred to as a phase DC motor) 6 of the stator windings 4u, 4v,
3 phase DC motor 6 by sending to each phase of 4w (U, V, W)
Drive.

Reference numerals 7 and 8 denote three power lines for connecting the output end of the inverter circuit 3 and the stator windings 4u, 4v, 4w of the three-phase DC motor 6 to energize the three-phase DC motor 6. Among them, a voltage detection circuit and a current detection circuit installed on two power lines (U phase and V phase) are shown. The voltage detection circuit 7 is a power line for U phase and V phase and a transistor Q _{6 of the} inverter circuit 3. Resistors R ₁ and R ₂ inserted and connected in series with the emitter side of
And the partial pressure ratio of the resistors R ₃ and R ₄ can be obtained. That is, the voltage of the power lines of the U and V phases can be detected, and the detected voltage outputs each connection point of the resistors R ₁ and R ₂ and the resistors R ₃ and R _4. It is sent to the next circuit as an end.

Further, the current detection circuit 8 is a current transformer CT ₁ , for detecting the load current value flowing in the two power lines of U phase and V phase.
It is configured by fitting and installing CT ₂ in the power lines of the U and V phases. At the output end of the current detection circuit 8, that is, at the output end of the current transformers CT ₁ and CT ₂ , the U-phase and V-phase power lines flow, for example, harmonic noise components and inverter circuits. PWM from the output end of 3
A noise filter 9 for removing a noise component caused by a disturbance due to an inverter mixed in the current controlled and applied to the three-phase DC motor 6 is connected. This noise filter 9 is composed of, for example, resistors CT and CT ₂ connected in series between the current transformers CT ₁ and CT ₂ and a grounding capacitor, and the stator windings 4 u to 4 w of the three-phase DC motor 6. It is provided in order to eliminate the presence of a noise component harmful to the accurate grasp of the current value in the current when the current flowing in the current is detected by the current detection circuit 8.

Further, at the output end of the voltage detection circuit 7,
A buffer circuit 10 is connected to the buffer circuit 10. The buffer circuit 10 is installed so that the high impedance input from the voltage detection circuit 7 can be appropriately lowered to the next circuit and sent out. It is possible to avoid a circuit malfunction that is induced when the detected voltage is directly sent to the next circuit. Reference numeral 11 denotes a noise filter connected to the output end of the buffer circuit 10, which is configured to include, for example, a resistor and a ground capacitor that are inserted and connected in series between the output end of the buffer circuit 10 and the ground.
When the voltage output from the buffer circuit 10 contains a noise component such as harmonic noise that hinders the accurate grasp of the voltage value, it is provided to remove the noise component.

Next, in FIG. 1, reference numeral 12 is a three-phase current calculation device, and this calculation processing device 12 has the stator windings 4u, 4v, 4 of the three-phase DC motor 6 detected by the current detection circuit 8.
Of the three power lines energized in w, the U-phase and V-phase current vectors are combined to obtain the W-phase current vector. Input current i
u and iv are added (combined) to obtain a combined current vector,
Further, the W-phase current iw can be obtained by inverting the polarity of the combined current vector and performing the calculation process. The currents iu, iv,
The iw is set as a current vector in a Y-shape (star) by the three-phase current calculation device 12, and is sent as a three-phase AC signal (current) to the three-phase to two-phase current conversion device 13 described below.

The above three-phase / two-phase current converter 13 has three
A three-phase alternating current signal sent from the phase current calculating device 12 is converted into a two-phase alternating current signal displayed by the outputs iα and iβ, that is, the three-phase current calculating device 12 outputs in a Y shape. Current vector iu, i of each phase U, V, W
v, iw

[Equation 1] (2) is converted into a two-phase AC signal having an L-shaped stator coordinate (α-β axis).

[0025]

[Equation 1]

As described above, the 3-phase to 2-phase current converter 1
3 is sent from the three-phase current calculation device 12 by dividing it into three phases of U phase, V phase, and W phase, and the current vectors iu, iv, iw of each phase for displaying these in Y shape are displayed. , The current vectors of the respective phases are included and converted to the α-β axis, the α axis indicates the position (vertical) in the same direction as the component of the U phase current vector iu, and the β axis indicates the α Axis (U
Phase) shows a position (horizontal) rotated by 90 ° in the clockwise direction. Then, the two-phase AC signals iα, iβ sent from the three-phase / two-phase current converter 13 are estimated information for estimating and outputting a command signal for operating the three-phase DC motor 6 described later with optimum high efficiency. An induced voltage estimation calculation means 17 of an arithmetic processing unit 16 (hereinafter, simply referred to as an arithmetic processing unit);
It is output to the M drive control device 18 as current information to be supplied to each of the three-phase DC motors 6.

Next, reference numeral 14 shown in FIG. 1 is a three-phase voltage calculating device. This calculating device 14 is a U-phase or V-phase among the voltages applied to the three-phase DC motor 6 detected by the voltage detecting circuit 7. The voltage vector of W phase is obtained by synthesizing the voltage vector of W phase.
The input voltages Vu and Vv of the V phase are added (combined) to obtain a combined voltage vector, and then the combined voltage vector is
The voltage Vw of the W phase can be obtained by inverting the polarity and performing the calculation process. The voltages Vu, Vv, Vw of the respective phases are voltage vectors by the three-phase voltage calculation device 14. Is divided and set in a Y-shape and is sent as a three-phase AC signal (voltage) to a three-phase to two-phase voltage converter 15 described below.

Subsequently, the three-phase / two-phase voltage converter 15 converts the three-phase AC signal sent from the three-phase voltage calculator 14 into a two-phase AC signal represented by outputs Vα and Vβ. It is a thing. That is, from the three-phase voltage calculation device 14 to Y
The voltage vectors Vu, Vv, Vw of each phase U, V, W output in the shape of a letter are

[Equation 2] The calculation processing is performed by the (formula) shown in (4) and is converted into a two-phase AC signal having an L-shaped stator coordinate (α-β axis).

[0029]

(Equation 2)

As described above, the three-phase / two-phase voltage converter 15
Is sent from the three-phase voltage calculation device 14 by dividing it into three phases of U-phase, V-phase and W-phase, and the voltage vectors Vu and Vv of the respective phases are displayed in Y-shape. , Vw are converted into an α-β axis in a state of including the voltage vector of each phase, the α axis indicates the position (vertical) in the same direction as the component of the U phase voltage vector Vu, and the β axis indicates The direction (horizontal) rotated 90 ° clockwise from the α axis (U phase) is shown. The two-phase AC signals Vα and Vβ sent from the three-phase to two-phase voltage conversion device 15 are used as voltage information applied to the three-phase DC motor 6 by the induced voltage estimation calculation means 17 of the calculation processing device 16 described later. Is output.

Next, the configuration of the arithmetic processing unit 16 described above will be described. The arithmetic processing unit 16 is composed of an induced voltage estimation arithmetic means 17, a rotor position estimation arithmetic means 19, and a rotor angular velocity (rotation speed) estimation arithmetic means 20, and each of these estimation arithmetic means 17, 19 is provided. , 20
Is composed of a 16-32-bit 1-chip microcomputer or a digital signal processor (commonly called DSP). That is, it is configured so that it can be processed by software using the microcomputer (note that each of the estimation calculation means 17, 19 and 20 described above can also be handled as a hardware configuration without dealing with software. Needless to say).

Subsequently, each of the above-mentioned estimation calculation means 17, 1
The contents of 9 and 20 will be described in detail. First, the induced voltage estimation calculation means 17 causes the voltage value actually applied to the stator windings 4u, 4v, 4w of the three-phase DC motor 6 and the stator windings 4u, 4v, 4w at that time. A current equal to the flowing current is applied to the stator winding 4 of the three-phase DC motor 6 that is stopped.
Stator winding 4u, 4v, 4 when flowing into u, 4v, 4w
A means for calculating and calculating the induced voltage, which is the difference between the voltage appearing in each phase of w and the calculated value, is provided.

Further, the rotor position detection / estimation means 19 is provided with means for calculating the position of the rotor 5 by arithmetically processing the components of the induced voltage (described later). Furthermore,
The rotor angular velocity estimating means 20 is provided with means for calculating the angular velocity of the rotor from the induced voltage to calculate the angular velocity of the rotor 5.

Next, the induced voltage estimation calculation means 17 will be described. Generally, a voltage is applied to the stator windings 4u, 4v, 4w of the three-phase DC motor 6,
It is well known that an induced voltage e is generated in the stator windings 4u, 4v, 4w by causing a current to flow in u, 4v, 4w and the rotor 5 rotating accordingly. And the induced voltage e is generally

(Equation 3) It can be obtained by the equation (1) shown in.

[0035]

[Equation 3]

Here, i ¹ : current vector R: resistance value of stator winding L: inductance of stator winding V ¹ : applied voltage vector e _M ¹ : true value of induced voltage vector d / dt: current Represents an operator that differentiates at a given time. In the above equation (1), since the values other than the true value e _M ¹ of the induced voltage vector are already known, based on the equation (1), the estimated induced voltage vector e ¹ is

[Equation 4] It can be obtained by the equation (2) shown in.

[0037]

[Equation 4]

Further, in the present invention, as shown in FIG.
Since the currents iα, iβ and the voltages Vα, Vβ are sent by the voltage conversion devices 13, 15, the estimated induced voltage e ¹ is decomposed based on the stator coordinates (α-β axis) into eα and eβ. It can be divided. The induced voltages eα, e
β (estimated induced voltage information output from the induced voltage estimation calculation means 17) is

(Equation 5) It is calculated by the equations (3) and (4).

[0039]

(Equation 5)

The estimated back electromotive force information eα and eβ can be easily obtained by calculating the equations (3) and (4). However, since the equations (3) and (4) include the differential value obtained by differentiating the current per predetermined time, when the microcomputer performs arithmetic processing, an excessive load is applied to the microcomputer too much. This was a major obstacle to speeding up arithmetic processing. Therefore, in view of the above, the present invention obtains the estimated induced voltage information eα and eβ based on the equations (3) and (4) without using the differential operator d / dt. Here, the preparation for obtaining the estimated induced voltage information eα is performed as follows.

(Equation 6) Shown by. The above

[Mathematical formula-see original document] is the true value e _M ¹ of the induced voltage vector, if decomposed based on the stator coordinates (α-β axis), then e α _M and e β _M
Since it can be divided into

It can be obtained by modifying the equation (1) of the equation (3).

[0041]

[Equation 6]

The above

Equation (5) of Equation 6 includes the estimated induced voltage information eα, and

Equation (6) of the equation (6) is the true value e of the induced voltage information eα.
α _M is included. By using the difference between these two equations,
Estimated induced voltage information e without differentiating the current iα
The calculation formula for α is

(Equation 7) Shown by.

[0043]

(Equation 7)

Here, G: feedback gain (observer gain) iα: current value detected and calculated by the current detection circuit 8 ξα: intermediate variable for avoiding calculation of current component

It is possible to obtain the estimated induced voltage information eα by calculating the equation (14) of the equation (7), and the estimated induced voltage information eα is calculated as described above.

As shown in the equation (3) of the equation (5), the current iα can be obtained without performing a differential operation, so that the load on the microcomputer can be reduced and the speed of the operation processing can be increased.

When obtaining the other estimated induced voltage information eβ, the same as the case of obtaining the estimated induced voltage information eα,

Based on the equation (4) of

In equations (7) to (13) shown in Equation 7, eα is
Substitute β for arithmetic processing, and then

(Equation 8) Since the estimated electromotive force information eβ can be obtained by performing the arithmetic processing of the equation (15), the arithmetic expression of the estimated electromotive voltage information eβ is omitted.

[0046]

(Equation 8)

In this way, the induced voltage vector e ¹ , that is, the estimated induced voltage information eα, eβ output from the induced voltage estimation calculation means 17 is

[Equation 7],

It can be easily calculated and obtained by the equations (14) and (15) shown by Eq. Then, the induced voltage information eα and eβ are the rotor position estimation calculation means 1 described below.
9 and the rotor angular velocity estimation calculation means 20 respectively.

Next, the rotor position estimation calculation means 19 will be described. Estimated induced voltage vector e ¹ (estimated induced voltage information eα and e) output from the induced voltage estimation calculation means 17
For example, in the case of a two-pole brushless DC motor, β) always has a phase advanced by 90 ° in electrical angle with respect to the direction of the magnetic poles of the rotor, as shown in FIG. Based on this, for example, the position θ of the magnetic pole N of the rotor is taken as an example in FIG.
To describe the case of obtaining, the rotor position estimation calculation means 1
Since the estimated back electromotive force information eα and eβ are constantly input from the back electromotive force estimation calculation means 17 to 9, the information eα,
By using eβ, the θ shown in FIG.

[Equation 9] Calculate by

[0049]

[Equation 9]

[0050]

From the equation (9), the position θ of the magnetic pole N of the rotor in FIG. 3 is present at a position rotated by 30 ° clockwise from the start (0 °) point.

The above

Based on the following equation, and the estimated induced voltage information eα,
The general formula for calculating the position of the magnetic pole (rotor) by using eβ is

[Equation 10] Can be sought by. In addition,

The general formula shown by the equation (10) is for a two-pole brushless DC motor.

[0052]

[Equation 10]

The above

[Equation 10] has been described as an example in which it is used for a two-pole DC motor, but in the case of the four-pole three-phase DC motor 6 used in this embodiment, the mechanical angle is 360 ° per one rotation of the rotor 5. . Therefore, the electrical angle is 360 ° per rotation × number of poles /
It becomes 2. As a result, the electrical angle of the 4-pole 3-phase DC motor 6 is 360 ° × 4/2 = 720 °. For this reason,
In the 4-pole 3-phase DC motor 6, the induced voltage vector e ¹ is 90 in electrical angle with respect to the direction of the magnetic poles of the rotor 5.
The phase is advanced by ° and its mechanical angle exists at the position of 45 °. That is, in the case of the 4-pole three-phase DC motor 6, the mechanical angle θre ₁ = electrical angle θ / 2, and when θ = 90 °, θre ₁ = 90 ° / 2 = 45 °. Thereafter θr
e = electrical angle. Then, the information indicating the position of the rotor 5, that is, the estimated rotor position information (a signal indicating the electrical angle of the rotatable element 5) θre output from the rotor position estimation calculation means 19 is PWM drive control. It is sent (input) to the device 18.

Subsequently, the rotor angular velocity estimation calculation means 20
Will be described. During operation of the three-phase DC motor 6, the induced voltage e generated in the stator windings 4u, 4v, 4w is generated in proportion to the angular velocity ωre of the rotor 5. When the angular velocity ωre of the rotor 5 is fast (the rotation speed of the rotor is high), the induced voltage e becomes high. On the other hand, the angular velocity ω of the rotor 5
When re is slow (the rotation speed of the rotor is low), the induced voltage e also becomes low. Thus, the induced voltage e and the rotor 5
Since the angular velocity ωre of is proportional,

[Equation 11] It can be expressed by the following equation.

[0055]

[Equation 11]

K is the torque constant of the motor

As shown by the following equation, the angular velocity ωre of the rotor 5 is
It can be easily obtained by performing calculation processing using the induced voltage e and the torque constant K of the motor. However, 3
When the usage environment of the three-phase DC motor 6 and the temperature of the three-phase DC motor 6 differ, the torque constant K of the three-phase DC motor 6 fluctuates, and the angular velocity ωre of the rotor 5 also fluctuates accordingly. Rotor 5 of 3-phase DC motor 6
The electric velocity of the rotor 5 is updated (corrected) every 360 ° of mechanical angle and 180 ° of mechanical angle, so that the angular velocity ωre of the rotor 5 is calculated and calculated.

Therefore, the estimated induced voltage information eα and eβ output from the induced voltage estimation calculation means 17 and the three-phase D
The relationship of the induced voltage e generated by the operation of the C motor 6 is as follows.

(Equation 12) It can be set by the arithmetic expression shown in.

[0058]

[Equation 12]

Here,

Eα = ωre × Ko (-
When sin (θre)) is integrated, eIα = ∫eαdt
= Ko × cos (θre) + C. Where eI
α: voltage obtained by integrating eα Ko: true motor torque constant C: integration constant As a result, eIα = Ko × cos (θre) +
It becomes C. It should be noted that Ko × cos (θre) represents an AC voltage component, and C represents a DC voltage component. The relationship between the voltage eIα obtained by integrating the estimated induced voltage information eα and the AC and DC voltage components will be described with reference to FIG. 4, where the integration constant C matches the DC voltage component D and becomes the DC voltage component D. That is, the DC voltage component D is in a state in which the offset voltage is applied. Therefore, the AC voltage component Ko × cos (θ
re) is to output the arc-shaped waveform (trajectory) centered on the DC voltage component D and at a predetermined downward interval.

Then, the voltage eIα is the maximum value eIαm.
When it becomes ax, it is when cos (θre) = 1. That is,

(Equation 13) This is shown by the equation (21).

[0061]

[Equation 13]

When the voltage eIα becomes the minimum value eIαmin, it is when cos (θre) =-1. That is,

[Equation 14] This is shown by the equation (22).

[0063]

[Equation 14]

The above equations (21) and (22) are

(Equation 15) When the following equation shown in

[0065]

(Equation 15)

It becomes As a result, the true motor torque constant Ko is

[Equation 16] It is possible to obtain the value by calculating the following equation.

[0067]

[Equation 16]

Here, the true motor torque constant Ko is substituted into the motor torque constant K, and the estimated induced voltage information e
The angular velocity ωre of the rotor 5 estimated using α and eβ is

[Equation 17] It can be obtained by calculating with the following equation.

[0069]

[Equation 17]

Here, the estimated angular velocity ωre of the rotor 5 is
For example, in the case of a 2-pole DC motor, the calculation processing is performed using ωre as it is, and in the case of a 4-pole DC motor, ωre
Converted to / 2 for calculation. The estimated angular velocity ωre of the rotor 5 calculated by the rotor angular velocity estimation calculation means 20 is P as the estimated angular velocity information ωre of the rotor 5.
It is output to the WM drive control device 18.

Subsequently, the rotor position information θre of the rotor 5 output from each of the estimation calculation means 19 and 20 of the calculation processing device 16, the angular velocity information ωre of the rotor 5, and the three-phase-two-phase The PWM drive control device 18 to which the current information (two-phase AC signals) iα, iβ output from the current conversion device 13 is input, respectively, according to the input signal from the speed command device 21, the θre, ωre, iα. , Iβ signals are converted and controlled into a three-phase voltage type sine wave approximate PWM signal that is optimal for the operation of the three-phase DC motor 6, and output, for example, a well-known PWM signal generation circuit is provided. .

In FIG. 1, reference numeral 22 is a power transistor drive for driving and controlling the inverter circuit 3 by supplying ON / OFF signals to the transistors Q _{1 to} Q ₆ of the inverter circuit 3 connected to the output terminal of the PWM drive control device 18. Circuit, and each of the transistors Q _{1 to} Q of the inverter circuit 3
₆ are the optimum conditions (three-phase voltage type sine wave approximation PW
3 phase D by controlling on-off with M signal)
The rotor 5 is attached to the stator windings 4u, 4v, 4w of the C motor 6.
It is possible to apply a three-phase AC signal capable of rotating the motor according to the speed command signal, and as a result, the three-phase DC motor 6 can be smoothly operated with an optimum motor torque constant.

Next, the estimation calculation processing of the calculation processing device 16 which is the main part of the inverter control device of the present invention will be described with reference to the flow charts shown in FIGS. Figure 5
Is a flow chart showing the execution means of the induced voltage estimation calculation means 17, and when the three-phase DC motor 6 is operating, three-phase-2
The estimated induced voltage information eα, using the phase currents, the currents iα, iβ and the voltages Vα, Vβ (currents and voltages of the power supplied to the three-phase DC motor 6) sent from the voltage converters 13, 15 eβ is output, and step S in FIG.
1 and S2, the time T ₃ after the start of the calculation of the estimated induced voltage information
And a predetermined time T ₂ are compared, and if the time T ₃ after the start of the calculation is a predetermined time T ₂ or more, steps S3, S
Then, the process proceeds to 4 to update the estimated induced voltage information eα and eβ. If the time T ₃ after the start of calculation is less than the predetermined time T ₂ in step S2, the estimated induced voltage information eα,
Since it is not necessary to update eβ, the previous data is output as it is as the estimated induced voltage information eα and eβ. Then, in step S3, when a certain time has elapsed from the start of calculation, the elapsed time T ₃ is once reset, and step S4
, The voltage / current Vα, Vβ, iα, i
The information of β and the estimated angular velocity information ωre of the rotor 5 are taken in. Then, in step S5, the feedback gain G is obtained based on the acquired information. However, g in step S5 is a constant that sets the estimation accuracy.

Then, when the feedback gain G is obtained in the step S5, the numerical value is utilized in the step S5.
6, the components of the current iα and the voltage Vα are

Equation (13) is used to perform integration to obtain ξα,
Further, in step S8,

The estimated induced voltage information eα is calculated by the equation (14) shown in Equation 7. Incidentally, when the other estimated induced voltage information eβ is obtained, the estimated induced voltage information eβ can be obtained in the same manner as described above, and thus the calculation formula of eβ is omitted. Therefore,

[Equation 7],

As can be seen from the equations (14) and (15) of Equation 8, when the feedback gain G is increased, the three-phase DC motor 6
However, if the feedback gain G is increased more than necessary, noise caused by the output from the inverter circuit 3 is superimposed on the estimated induced voltage information eα and eβ, and the estimated induced voltage information e eα, eβ
May reduce the function of. Therefore, in the present invention, when the feedback gain G is obtained, the estimated angular velocity information ωre of the rotor 5 is taken in and the arithmetic processing is performed, as shown in step S5 of FIG.

Next, the execution means of the rotor position estimation calculation means 19 of the rotor 5 is shown in the flow chart of FIG. 6, and the magnetic pole position θ of the rotor 5 is the estimated induced voltage information e.
Obtained using α and eβ. In FIG. 6, step S
When the estimated induced voltage information eα and eβ are input to the rotor position estimation calculation means 19 at 10,

In the case of eα = 0 and eβ> 0 shown in the equation (1), the process proceeds to steps S11 to 13, and θ is 0 °.
In case of no in step S12

Since eα = 0 and eβ <0 shown in the equation (5) of (10) are satisfied, the process proceeds to step S14, and θ becomes 180 °. If steps S15 and S16 are required, the process proceeds to step S17, where θ is

According to the equation (8) of the equation (10), 360 ° + tan ⁻¹ (−e
α / eβ). If NO in step S15, the process proceeds to step S18, and if step 18 is necessary,

It matches with eα <0 and eβ> 0 shown in the equation (2), and the process proceeds to step S19, where θ is tan ⁻¹ (−eα /
eβ). If step S16 is negative, the process proceeds to step S20, and if step S20 is necessary,

Since eα> 0 and eβ = 0 shown in the equation (7) of (10) are satisfied, the process proceeds to step S21 and θ becomes 270 °. If step S20 is negative, the process moves to step S22,

This coincides with eα> 0 and eβ <0 shown in the equation (6), and θ becomes 180 ° + tan ⁻¹ (−eα / eβ).
Further, in the case of no in step S18 and in the case of necessity in step S23,

This matches eα <0 and eβ = 0 shown in the equation (3), and the process proceeds to step S24, where θ becomes 90 °. If the result in step S23 is NO, the process moves to step S25,

Since it matches with eα <0 and eβ <0 shown in the equation (4), θ becomes 180 ° + tan ⁻¹ (−eα / eβ).

As described above, the rotor position estimation calculation means 1
In 9, when the estimated induced voltage information eα and eβ are input,
The magnetic pole position θ of the rotor 5 is sequentially calculated based on the information eα and eβ, and the rotor position information θre estimated from the output end is output.

The flow chart shown in FIG. 7 shows the execution state of the rotor angular velocity estimation calculation means 20 for calculating the estimated angular velocity ωre of the rotor 5, and is output from the induced voltage estimation calculation means 17 as described above. Estimated induced voltage information e
The estimated angular velocity ωre of the rotor 5 is calculated by taking in α and eβ. In steps S31 and S32 shown in FIG. 7, the time T ₁ and the predetermined time T after the calculation of the estimated induced voltage information eα and eβ are started. If the time T ₁ after the start of the calculation is equal to or longer than the predetermined time T, the following steps S33 and S34 are performed.
Then, the estimated induced voltage information eα and eβ are updated.
On the other hand, when the time T ₁ after the start of calculation is less than the predetermined time T in step 32, the estimated rotor angular velocity information ωre
Does not need to be updated, the previous data is output as is as the estimated angular velocity information ωre.

In step S33, the elapsed time T ₁ is once reset after a certain time has elapsed from the start of the calculation. Then, in step S34, new induced voltage information e
Taking in α and eβ, the calculation process of the rotor angular velocity is started. Then, in step S35, eα is integrated to obtain eIα.
Ask for. The voltage eIα obtained by the integration is calculated in step S
As shown in FIG. 4, at 36 and S37, the maximum and minimum voltage values are compared centering on the DC voltage component D, the maximum voltage value eIαmax is updated at step 38, and the minimum voltage value eIαmin is determined at step S39. I am updating. Then, in step S40, the rotational position of the rotor 5 is confirmed, the process proceeds to step S45 until the rotor 5 rotates 360 ° in electrical angle, and when the rotor 5 rotates 360 ° in electrical angle, At that time, the process proceeds to step S41 to calculate the torque constant Ko of the true motor, and in step S42, the Ko obtained by the above calculation is calculated.
Is substituted into the motor torque constant K. Then, the process proceeds to step S45 through steps S43 and 44, and in step S45, the estimated angular velocity ωre of the rotor 5 is calculated by using the estimated induced voltage information eα and eβ to calculate the estimated angular velocity ωre of the rotor 5. Ask. The estimated angular velocity ωre obtained in step 45 is calculated by the induced voltage estimation calculation means 17 and the PWM.
It is output to the drive control device 18, respectively.

As described above, the estimated rotor position information θre and the estimated rotor angular velocity information ωr calculated by performing the calculation processing by the respective estimation calculation means 17, 19, 20 of the calculation processing device 16.
Since e is calculated on the basis of the estimated induced voltage information eα and eβ which are both calculated and calculated by the induced voltage estimation calculation means 17, the PWM drive control device 1 is used as estimated information.
8 is output. Therefore, the above estimation information θre, ωr
e is the current, voltage iu, supplied to the three-phase DC motor 6,
Since it was calculated based on iv, Vu, Vv, three-phase DC
The motor 6 can always be supplied with the three-phase AC power for driving the three-phase DC motor 6 with high efficiency based on the command from the speed command device 21.

This is because when calculating the induced voltage information eα and eβ, the estimated rotor angular velocity information ωre is calculated in advance.
It's just because it's capturing and processing. Therefore, during the calculation process of the estimated induced voltage information eα and eβ, the estimated value of the estimated induced voltage information eα and eβ can be calculated by arbitrarily calculating the feedback gain G based on the estimated rotor angular velocity information ωre. It is possible to approach the optimum operating condition of the three-phase DC motor 6.

Now, for example, a case where the feedback gain G is small will be described. In FIG. 8, since the rotor angular velocity is slow (the rotation speed of the rotor 5 is low), the feedback gain G is also small. However, since the difference Δd between the estimated rotor position information θre and the actual rotor position information θre ₂ is very small, the rotor 5 rotates smoothly according to a predetermined speed command even if the feedback gain G is small. Can be made.

Further, as shown in FIG. 9, the estimated rotor position information θre and the actual rotor position information θre ₂ when the feedback gain G is small and the rotor angular velocity is fast (the rotation speed of the rotor 5 is high). The difference .DELTA.d becomes large, the rotation efficiency of the rotor 5 decreases, and sufficient torque cannot be obtained. However, in this case, the rotation angle of the estimated rotor position information θre may be increased, that is, the interval of Δd may be decreased. This is solved by increasing the feedback gain G. Since the actual rotation angle of the rotor position information θre ₂ is large, the feedback gain G is increased.
It becomes easy to increase the rotation angle of the rotor 5. As a result, the rotation angle of the estimated rotor position information θre can be increased and the position detection of the rotor 5 can be favorably followed.
Can be efficiently rotated according to the speed command.

Further, in FIG. 10, when the feedback gain G is high, the difference Δd between the estimated rotor position information θre and the actual rotor position information θre ₂ is small, so that the rotor 5 can detect the position well. It can follow and rotate smoothly.

As described above, in the present invention, the feedback gain G is reduced when the angular velocity of the rotor is slow, and conversely, the feedback gain G is increased when the angular velocity of the rotor is fast. The followability of the position detection of the rotor 5 is remarkably good, whereby the rotation of the rotor 5 can be performed smoothly, and the operation efficiency of the three-phase DC motor 6 can be remarkably improved.

As described above, the estimated position detection information θre of the rotor 5, the estimated angular velocity information ωre of the rotor 5, and the current information iα, iβ which are arithmetically processed by the arithmetic processing unit 16 are supplied to the PWM drive control unit 18, respectively. Output, this PW
In the M drive control device 18, each of the above information is converted into a three-phase voltage type sine wave approximate PWM signal by the PWM signal generation circuit, and this is output to the power transistor drive circuit 22. From this power transistor drive circuit 22 to the inverter circuit 3. it outputs a drive signal, the transistors Q ₁ to Q ₆ of the inverter circuit 3 is driven and controlled by 3-phase voltage sine wave approximation PWM signals, respectively, the stator winding from the inverter circuit 3 a three-phase DC motor 6 4u, 4v, 4
w is supplied with 3-phase AC power capable of operating the 3-phase DC motor 6 with high efficiency, and the 3-phase DC motor 6 is supplied.
With the optimum motor torque constant, the torque ripple can be reduced to allow smooth and efficient operation.

[0086]

Since the present invention is constructed as described above, it has the following effects. (1) According to the present invention, the three-phase brushless DC motor is based on the AC power supplied to the three-phase brushless DC motor.
Since the information for operating the motor with high efficiency is estimated and arithmetically processed, and the inverter circuit is drive-controlled based on the information obtained by the estimation and arithmetic processing, the three-phase brushless DC motor is always in the optimum operating condition. Since it can be operated based on the information, this type of three-phase brushless DC motor can be operated with high efficiency by following the speed command.

(2) The present invention is a three-phase brushless DC
Based on the voltage and current information supplied to the motor, it is configured to estimate the information on the optimum operating condition and drive and control the inverter circuit. Therefore, expensive position detectors such as Hall elements, encoders, resolvers, etc. are completely eliminated. I don't need it, so
A three-phase brushless DC motor can be manufactured with a simple structure, small size, light weight, and economically.

(3) The present invention is a three-phase brushless DC
The information on the optimum operating condition for driving the motor is calculated by estimating the induced voltage generated during the operation of the three-phase brushless DC motor based on the current and voltage information supplied to the three-phase brushless DC motor. Then, the estimated induced voltage thus calculated is used to further estimate the rotor position and the rotor angular velocity, and the calculation process is performed. Based on the estimated rotor position and rotor angular velocity information, the three-phase voltage type sine Since the wave approximate PWM signal is generated to drive and control the inverter circuit, pulsation occurs during the operation of the three-phase brushless DC motor to increase the torque ripple, and vibration and noise are generated in the three-phase brushless DC motor itself. It is possible to surely solve the problem of causing it.

(4) According to the present invention, the induced voltage estimation calculation means for calculating the estimated induced voltage information is provided with the means for adjusting the feedback gain in correspondence with the slow / fast rotor angular speed. The three-phase brushless DC motor is convenient because it can be operated by always following the operating condition of a highly efficient motor torque constant.
Since it is possible to suppress the generation of vibrations and noises by reducing the pulsation, mechanical sound absorption and vibration isolation members are not required, and moreover, it is possible to deal with them by software using a microcomputer. Seed three-phase brushless DC
It is possible to significantly improve the productivity of the motor and reduce the cost.

[Brief description of drawings]

FIG. 1 is a block diagram showing an inverter control device for a three-phase brushless DC motor of the present invention.

FIG. 2 is an explanatory diagram showing a relationship between an induced voltage vector and magnetic poles.

FIG. 3 is an explanatory diagram showing an example of obtaining a position of a magnetic pole by using an induced voltage.

FIG. 4 is an explanatory diagram of a motor torque constant.

FIG. 5 is a flow chart showing a calculation processing state of estimated induced voltage information.

FIG. 6 is a flowchart showing a state of calculation processing of estimated position information of a rotor.

FIG. 7 is a flowchart showing a calculation processing state of estimated angular velocity information of a rotor.

FIG. 8 is an explanatory diagram showing a relationship when a feedback gain is low and a rotor angular velocity is low.

FIG. 9 is an explanatory diagram showing a relationship when a feedback gain is low and a rotor angular velocity is fast.

FIG. 10 shows a case where the feedback gain is high, and
It is explanatory drawing which shows the relationship when a rotor angular velocity is fast.

FIG. 11 is a block diagram showing an example of a conventional rotor position detecting device for a sensorless brushless DC motor.

12 is a time chart diagram for explaining the principle position detection operation of FIG.

[Explanation of symbols]

3 Inverter circuit 4u, 4v, 4w Stator winding 5 Rotor 6 3-phase sensorless brushless DC motor 7 Voltage detection circuit 8 Current detection circuit 12 3-phase current operation device 13 3-phase-2 phase current conversion device 14 3-phase voltage operation Device 15 Three-phase to two-phase voltage conversion device 16 Estimated information calculation processing device 17 Induction voltage estimation calculation means 18 PWM drive control device 19 Rotor position estimation calculation means 20 Rotor angular velocity estimation calculation means 21 Speed command device 22 Power transistor drive circuit e ¹ Estimated induced voltage vector eα, eβ Estimated induced voltage information θre Estimated rotor position information ωre Estimated rotor angular velocity information iα, iβ Current information

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuhiko Sato 1 Aichi-cho, Kasugai-shi, Aichi Aichi Electric Co., Ltd.

Claims (3)

[Claims] 1. A three-phase brushless DC motor comprising a stator winding and a rotor having a permanent magnet, and voltage and current detection for detecting voltage and current respectively from two phases of the stator winding. Means, an induced voltage estimation calculation means for calculating the induced voltage information estimated from the output values of the voltage and current detection means, and rotor position information estimated by using the output values from the induced voltage estimation calculation means. An estimated information calculation processing device including a rotor position estimation calculation unit and a rotor angular velocity estimation calculation unit that respectively calculate the rotor angular velocity information, and the estimated rotor position and angular velocity information from the estimated information calculation processing unit. Inverter control of a sensorless brushless DC motor, characterized in that the inverter circuit is driven and controlled by the current information sent from the current detection means. Control device. 2. A three-phase brushless DC motor comprising a stator winding and a rotor provided with a permanent magnet, and voltage and current detection for respectively detecting voltage and current from two phases of the stator winding. Means, an induced voltage estimation calculation means for calculating the induced voltage information estimated from the output values of the voltage and current detection means, and rotor position information estimated by using the output values from the induced voltage estimation calculation means. An estimated information calculation processing device including a rotor position estimation calculation unit and a rotor angular velocity estimation calculation unit that respectively calculate the rotor angular velocity information, and the estimated rotor position and angular velocity information from the estimated information calculation processing unit. And the current information sent from the current detecting means to a PWM drive control device having a built-in PWM signal generation circuit, and the rotor position information and the rotor angular velocity information are used to support the information. In the approximate wave PWM signal
A sensorless brushless D characterized in that the drive control device outputs the signal to an inverter circuit, and the inverter circuit is drive-controlled by a sine wave approximation PWM signal.
Inverter control device for C motor. 3. The means for estimating an induced voltage included in the estimated information arithmetic processing unit, which lowers the feedback gain when the rotor angular velocity is low, and increases the feedback gain when the rotor angular velocity is high. An inverter control device for a sensorless brushless DC motor according to claim 1 or 2, further comprising: