JP2001078481A - Dc brushless motor driver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the efficiency of a DC brushless motor driver by reducing switching losses, when a DC brushless motor is driven in a 180 deg. conducted state. SOLUTION: One turned-on switching transistor, two switching transistors which are turned on/off by PWM, and three turned-off switching transistors are selected from among the six switching transistors of a drive circuit 1, based on the position of the rotor of a DC brushless motor 2 and two switching transistors are turned on/off, while one switching transistor is turned on in each PWM period. Consequently, the DC brushless motor 2 is driven in a 180 deg. conducted state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device for driving a DC brushless motor 180 degrees through PWM control.

[0002]

FIG. 19 shows a conventional brushless motor.
FIGS. 19A and 19B are explanatory diagrams for explaining 0-degree energization driving, where FIG. 19A shows a driving circuit, and FIG.
3A shows an example of a switching pattern of the switching transistors Tu to Tz. The driving circuit 1
Switching transistors Tu, Tv, Tw, T
x, Ty, Tz, and PWM control of the DC voltage E by turning on / off the switching transistors Tu to Tz, so that the three-phase Y-connected drive windings of the brushless motor 2 become U-phase, V-phase, and W-phase. By applying a current of 180 degrees, the permanent magnet rotor 2a is rotationally driven. The switching transistors Tu to Tz are turned on / off at a PWM frequency of 3 KHz, for example, and in each PWM cycle, all the switching transistors Tu to Tz are on / off controlled as shown in FIG. As a result, a sine wave voltage is applied to each phase U, V, W,
By applying a three-phase sine wave current having a phase difference of 0 degree, a rotating magnetic field is generated.

[0003]

SUMMARY OF THE INVENTION
According to the 0-degree energization drive, all of the six switching transistors Tu to Tz are turned on / off in each PWM cycle, so that a total of 12 turn-on and turn-off operations are performed. Therefore, there is a problem that switching loss due to turn-on and turn-off increases and driver efficiency decreases.

[0004] The present invention has been made based on the above-mentioned viewpoints, and an object of the present invention is to provide a DC brushless motor driving apparatus capable of reducing switching loss and improving driver efficiency.

[0005]

According to the present invention, a DC is provided.
The brushless motor has six switching elements for controlling the energization of the three-phase drive windings.
In a drive device for energizing and driving the DC brushless motor through 180 degrees through WM control, one switching element that is turned on based on a rotor position of the DC brushless motor and two switching elements that are turned on / off by PWM are provided. , Three switching elements to be turned off, and by turning on / off two switching elements with one switching element turned on in each PWM cycle, the DC brushless motor is turned on and off by 180. The above object is attained by a DC brushless motor drive device which is driven by a current.

According to such a configuration, since only two switching elements are turned on / off in each PWM cycle, the number of turn-on and turn-off of the switching elements can be extremely reduced. Therefore, switching loss is reduced and driver efficiency is improved.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an example of the embodiment of the present invention.

The six switching transistors Tu, Tv, Tw, Tx, Ty and Tz of the driving circuit 1 are PWM-controlled by the control unit 3, and the DC voltage E is controlled by the brushless motor 2 via the PWM control of the switching transistors Tu to Tz. Is applied to each phase U, V, and W of the Y-connected three-phase drive winding, so that the brushless motor 2 is driven by 180 degrees. The switching transistors Tu and Tx are U-phase switching elements. Tu is provided on the power supply side, and Tx is provided on the ground side. Switching transistors Tv and T
y is a V-phase switching element, Tv is on the power supply side, and Ty is
Are provided on the ground side. The switching transistors Tw and Tz are W-phase switching elements.
Are provided on the power supply side, and Tz is provided on the ground side. The diodes Du, Dv, Dw, Dx, Dy, and Dz inserted in parallel with the switching transistors Tu to Tz are for back electromotive force prevention. The control unit 3, along with the target rotational speed ωref of the brushless motor 2 is given, the rotor position theta _M is adapted to be supplied from the position detecting means 4 for detecting the rotational angular position of the permanent magnet rotor 2a. In addition, as the permanent magnet rotor 2a, the SPM (Sumu) whose inductance hardly changes depending on the rotor position is used.
rface Permanent Magnet) type or IPM (Interior) whose inductance changes with rotor position
Permanent Magnet) type.
The SPM type has a permanent magnet provided on the surface of the rotor core, and generates only magnet torque. I
The PM type has a permanent magnet embedded in a rotor core, and generates reluctance torque in addition to magnet torque.

In this embodiment, the control unit 3 is a DSP (Digital Signal Processor) which is a microcomputer for digital signal high-speed processing as an arithmetic processing unit.
Five. The DSP 5 selects one switching transistor to be turned on, two switching transistors to be turned on / off by PWM, and three switching transistors to be turned off among the switching transistors Tu to Tz for each PWM cycle,
By setting the duty ratio of two switching transistors that are turned on / off by PWM, the DC power source E is PWM-controlled by turning on / off two switching transistors in each PWM cycle while one switching transistor is on. I do.

[0010] Selection of the switching transistor Tu~Tz, in this example, is performed based on the phase theta _V of the voltage vector V to be applied to three-phase drive winding of the brushless motor 2 to be described later. FIG. 2 shows switching transistors Tu to Tz.
It is a figure which shows the selection pattern of. As is clear from FIG. 2, when the phase θ _V of the voltage vector V is 0 to 60 degrees, Ty as one switching transistor to be turned on, and Tw and Tu as two switching transistors to be turned on / off by PWM. However, Tv, Tx, and Tz are selected as three switching transistors to be turned off. When the phase theta _V is 60 to 120 degrees, Tu is a single switching transistors to turn on, PW
Ty and Tz are selected as two switching transistors to be turned on / off by M, and Tv, Tw and Tx are selected as three switching transistors to be turned off. Phase θ
_{When V} is 120 to 180 degrees, Tz as one switching transistor to be turned on is turned on / off by PWM.
Tu, as two switching transistors to be turned off,
Tw, Tx, and Ty are selected as three switching transistors that turn off Tv. Phase θ _V is 180
In the case of up to 240 degrees, Tv as one switching transistor to be turned on is turned on / off by PWM.
Tz and Tx as one switching transistor, and Tu and Ts as three switching transistors to turn off.
Tw and Ty are selected. When the phase theta _V is 240 to 300 degrees, Tx as one switching transistor to turn it, Tv as two switching transistors to be turned on / off by PWM, Tw is turned off 3
Tu, Ty, Tz as two switching transistors
Is selected. When the phase theta _V is 300 to 360 degrees, Tw as one switching transistor to turn it, Tx as two switching transistors to be turned on / off by PWM, Ty is, Tu as three switching transistors to turn off, Tv and Tz are selected.

FIG. 3 is a vector diagram showing a method of obtaining a voltage vector V applied to the three-phase driving winding of the brushless motor 2. 3, V1, V2, V3, V4, V5 and V6 are basic vectors, I is a current vector given to the brushless motor 2, and Φ is a main magnetic flux vector given by the permanent magnet rotor 2a of the brushless motor 2. The basic vectors V1 to V6 are vectors having a phase difference of 60 degrees with V1 being 0 degrees, that is, the origin, and are given by the switching pattern shown in FIG. Note that V
0 is a zero vector and does not affect the voltage vector V. The phase θ _V of the voltage vector V with respect to the origin, that is, the basic vector V1, is the phase of the main magnetic flux vector Φ, that is, the rotor position θ _M , the phase difference θ _{Φ I} between the main magnetic flux vector Φ and the current vector I, the current vector I and the voltage And the phase difference θ _{IV from the} vector V. The phase difference θ _ΦI between the main magnetic flux vector Φ and the current vector I is
It is set so that the maximum torque is generated, and is approximately 90 degrees if the influence of the motor current is ignored. The phase difference θ _IV between the current vector I and the voltage vector V is a phase difference caused by the inductance of each phase U, V, W, and is a function of the motor rotating speed and the inductance that changes depending on the rotor position. If the permanent magnet rotor 2a is of the SPM type, the inductance hardly changes depending on the rotor position. Therefore, the phase difference θ _IV is a function of only the rotation speed, and is set according to the actual rotation speed ωact of the brushless motor 2. On the other hand, if the permanent magnet rotor 2a is of the IPM type, it is set according to the actual rotational speed ωact and the inductance that changes according to the rotor position. Phase theta of the thus voltage vector V based on the rotor position theta _M
V , the switching transistors Tu to Tz
And identify two basic vectors associated with the voltage vector V. That is, in the state of FIG.
Since the phase theta _V of the voltage vector V is between 0 and 60 degrees, Ty as a switching transistor to turn
Are selected as switching transistors to be turned on / off by PWM, Tv, Tx, and Tz are selected as switching transistors to be turned off, and V1 and V2 are specified as two basic vectors. Permanent magnet rotor 2a
That is, the main magnetic flux vector Φ rotates in the direction indicated by the arrow b,
When the voltage vector V enters the region of the basic vectors V2 and V3, the switching transistor to be turned on is Tu.
Are selected as Ty and Tz as switching transistors to be turned on / off by PWM, and Tv, Tw and Tx as switching transistors to be turned off, and V2 and V3 are specified as two basic vectors.

The absolute value of the voltage vector V, that is, the magnitude A
Is given based on the actual rotation speed ωact of the brushless motor 2 and the target rotation speed ωref.
act is set to the target rotation speed ωref. Actual rotational speed ωact is determined from the time per amount of change in rotor position theta _M. By obtaining the phase θ _V and the magnitude A of the voltage vector V, the composite ratio of the two related basic vectors, that is, on / off by PWM, such that the voltage vector V has the magnitude A at the phase θ _V The duty ratio of the two switching transistors is set. 5 to 10 are timing charts of the switching transistors Tu to Tz in one PWM cycle. FIG. 5 shows a case where the phase θ _V of the voltage vector _V is 0 to 60 degrees, and FIG.
7 shows the case of 120 to 180 degrees, FIG. 8 shows the case of 180 to 240 degrees, FIG. 9 shows the case of 240 to 300 degrees, and FIG. 10 shows the case of 300 to 360 degrees. . 5 to 10, T _PWM indicates one PWM cycle, and the duty ratio of two switching transistors that are turned on / off by PWM is set by the time widths T ₁ , T ₂ , and T ₃ . The sum of the time widths T ₁ , T ₂ , and T ₃ is 1
PWM period T _PWM . Time width T ₁ represents the ON time width of one of the switching transistors, the time width T ₂
Represents the ON time width of the other switching transistor, and the ON of one switching transistor and the ON of the other switching transistor are continuous without overlapping. Only one switching transistor duration T ₃ is open periods of all the other switching transistor is turned off ON. Such time widths T ₁ , T ₂ , T ₃ are set by the following equations.

(Equation 2) In the above equation, θ ₁ and θ ₂ are the respective phases of the two associated fundamental vectors. If the voltage vector V is in the state of FIG. 3, θ ₁ is the phase of the basic vector V _1, that is, 0.
And θ ₂ is the phase of the basic vector V2, ie, 60
Degrees. The main magnetic flux vector Φ is rotated in the arrow b direction, if the voltage vector V placed in the region of the base vector V2, V3, theta ₁ becomes phase i.e. 60 ° of the basic vector V2, theta ₂ phase of the basic vector V3 That is, 120
It becomes degree. As is apparent from the foregoing, A is the absolute value of the voltage vector V, the theta _V is the phase of the voltage vector V.

As described above, the DSP 5 determines the phase θ _V of the voltage vector V based on the rotor position θ _M from the position detecting means 4 for each PWM cycle, and also determines the actual rotational speed ω.
one switching transistor that determines its magnitude A from act and the target rotation speed ωref and turns on;
Two switching transistors to be turned on / off by PWM and three switching transistors to be turned off are selected, and the duty ratio of the two switching transistors to be turned on / off is set to control the switching transistors Tu to Tz. Permanent magnet rotor 2a
Is an SPM type, since the inductance hardly changes regardless of the rotor position, a sine wave current having a phase difference of 120 degrees flows through each phase U, V, W of the brushless motor 2 by the above control. On the other hand, if the permanent magnet rotor 2a
In the case of the PM type, since the phase current is distorted due to the change in inductance depending on the rotor position, current sensors 6 and 7 for detecting the phase current are provided as shown by broken lines in FIG. The time widths T ₁ , T
₂ and T ₃ are corrected.

As the position detecting means 4, a rotary encoder, a Hall element, or the detection of an induced voltage by a search coil described later can be used. When the inductance changes depending on the rotor position, such as when the permanent magnet rotor 2a is of the IPM type, the change in the inductance, that is, the rotor position may be detected from the phase difference between the phase voltage and the phase current. In addition, IP whose inductance hardly changes depending on the rotor position
In the case of the M type, the induced voltage of the motor winding can be obtained based on the phase voltage, the phase current, and the rotation speed, and the rotor position can be detected accordingly. In addition, a known detecting unit can be applied as the position detecting unit 4.

FIG. 11 shows the DSP of the control unit 3.
5 is a control flowchart showing a control process performed every one PWM cycle.

It is assumed that the brushless motor 2 is started by well-known starting means, and the permanent magnet rotor 2a is rotating. At the start of the current PWM cycle, the DSP 5 first enters step 10, where the position detection means 4 sends the rotor position θ _M
Take in. Then, actual rotational speed of the brushless motor 2 from the time per amount of change in rotor position theta _M omega at step 11
ACT is calculated, and in the next step 12, the target rotation speed ωref of the brushless motor 2 is fetched. In step 13, the absolute value of the voltage vector V, that is, the magnitude A is calculated so that the actual rotation speed ωact becomes the target rotation speed ωref, and in the next step 14, the phase θ _V of the voltage vector _V is calculated. Phase theta _V of the voltage vector V, as described above, the rotor position theta _M, and the phase difference theta _.PHI.I the main flux vector Φ and the current vector I, and the phase difference theta _IV between the current vector I and the voltage vector V Given by adding As described above, the phase difference _θΦI is approximately 90 degrees if the influence of the motor current is ignored. However, when the influence of the motor current is considered, the motor current is detected and adjusted according to the magnitude. What should I do? The phase difference θ _IV is determined by the SPM of the permanent magnet rotor 2a.
If the type is set by using the table representing the relationship between the phase difference theta _IV and the actual rotational speed Omegaact, if the permanent magnet rotor 2a is IPM type, to a phase difference theta _IV actual rotational speed Omegaact the rotor position It is set using a table representing the relationship with the corresponding change in inductance.

Thereafter, the process proceeds to step 15, wherein one switching transistor to be turned on, two switching transistors to be turned on / off by PWM, and three switching transistors to be turned off are determined by using the phase θ _V of the voltage vector V. select. Selection pattern of the switching transistor Tu~Tz by phase theta _V is as described in FIG. Then, go to step 16, so that the voltage vector V becomes the absolute value A phase theta _V, and the phase theta _V and the absolute value A of the voltage vector V, the two basic vectors associated with the voltage vector V phase theta ₁ , Θ ₂ , the time widths T ₁ , T ₂ , and T ₃ are calculated by the above-described equation, and the duty ratio of the two switching transistors that are turned on / off by PWM is set. Next Step 17
Then, in step 15, the switching transistors Tu to
According to the selection of Tz and the setting of the duty ratio in step 16, the switching transistors Tu to Tz are changed as shown in FIGS.
The control is performed as shown in FIG. Only two switching transistors are turned on / off by PWM,
Therefore, as is clear from FIGS. 5 to 10, the switching transistors Tu to T in one PWM cycle T _PWM
The number of turn-on and turn-off of z is four.
Therefore, switching loss can be significantly reduced. One switching transistor is turned on every 60 degrees.
There are only 6 times per revolution, very few times and the effect on switching losses can be neglected. After step 17, step 18 is entered to determine whether or not the current PWM cycle has ended.
And the above-described control is repeated for the next PWM cycle. Since the DSP 5 can process digital signals in real time, it functions particularly effectively for such high-speed processing.

When the permanent magnet rotor 2a is of the IPM type, a distortion occurs in the phase current due to a change in the inductance depending on the rotor position.
, The time widths T ₁ , T ₂ , and T ₃ in step 16 are corrected so that the detected phase current becomes a sine wave.

According to the present embodiment, as described above, the switching loss can be greatly reduced, and the circulating current can be effectively used. FIG.
FIG. 2 is a diagram for explaining a circulating current in the configuration of FIG. Assuming that the selection pattern of the switching transistors Tu to Tz is in the state of FIG. 5, while the switching transistor Tu that is turned on / off by PWM is on, the switching transistors Tu and U-phase as shown by the dashed line c. , V phase, and a phase current flows through the switching transistor Ty. When from this state into the open period of time width T ₃ off the switching transistor Tu, because it tries to continue a current flows through the inductance of the phase winding, decreases the potential of the point P between the switching transistors Tu and Tx 0V or less, and the diode Dx of the switching transistor Tx is turned on. Thereby, as shown by the broken line d, the diodes Dx, U
A circulating current flows through the phase, V phase, and switching transistor Ty. Since both the switching transistors Tw and Tz are off, the circulating current flows from the U phase to the V phase in the same manner as when the switching transistor Tu is turned on, without shunting to the W phase, and torque is generated for this as well. . Since the circulating current is not reduced by the shunt as described above, the circulating current can be used more effectively, and the supplied energy can be reduced for the same generated torque. Incidentally, the ground side of the switching transistors, such as in a state of FIG. 6 when it is turned on / off by the PWM, enters the open period of time width T ₃ off the switching transistor Tz, the switching transistor Tw and Tz The potential at the point Q rises to the power supply voltage or higher, and a circulating current flows when the diode Dw of the switching transistor Tw is turned on.

In the example described above, the target rotation speed ω of the brushless motor 2 is supplied to the control unit 3 as the target value.
ref, the actual rotation speed ωact and the target rotation speed ωr
Although the absolute value A of the voltage vector V is determined based on ef, the present invention is not limited to this, and the absolute value A of the voltage vector V may be directly given as the target value. In this example, the control unit 3 is a DSP
5 has been described as an example, but the present invention is not limited to this, and other processors can be used.

In the example described above, the on /
FIGS. 5 to 1 show two switching transistors to be turned off.
Although the on / off operation is performed at the timing indicated by 0, the on / off operation may be performed at the timing illustrated in FIG. In FIG. 13, the time width _{T 3} of the open period 2
And one of the two switching transistors, which is turned on / off by PWM, Tw is on and Tu is the other.
, And between the ON of Tu and one PWM cycle T
Between the _PWM end, open period of T _3/2 are provided respectively. According to this, it is possible to effectively use the circulating current by turning on / off the switching transistor Tw and effectively use the circulating current by turning on / off the switching transistor Tu. Further, FIG.
Also, as shown in FIG. 15, the switching transistors Tu to Tz can be turned on / off.
Also in these cases, similarly, the number of times that the switching transistors Tu to Tz are turned on and off in each PWM cycle is four.

FIG. 16 is a block diagram showing an example of detecting the rotor position of a DC brushless motor using a search coil. In this embodiment, a compressor 20 and a DC brushless motor 21 for driving the compressor are provided in a sealed shell 22. Fig. 4 shows an application to a stored hermetic compressor.

The brushless motor 21 has a three-phase Y-connected U-phase, V-phase, and W-phase drive winding 23 and a three-phase Y-connected u-phase, v-phase, and w-phase. It has a coil 24. The search coil 24 shown in FIG.
As shown in FIG.
By being wound around one status lot 25, it is housed in the status lot 25 together with the drive winding 23. The search coil 24 has a thin wire diameter so that it can be accommodated in the gap between the drive windings 23 and the gap between the drive winding 23 and the inner wall of the status slot 25. The size of the lot 25 is not affected. Therefore, the search coil 24 can be provided only by changing the drive winding 23 and the search coil 24 together, instead of winding the conventional drive winding 23 alone into the status slot 25. The neutral point of such a search coil 24 is connected to the neutral point of the drive winding 23 in this example.

The drive winding 23 is driven by the drive circuit 1 for 180
Is energized. The search coil 24 is a brushless motor
Induction of sine wave with phase difference of 120 degrees by rotating 21
Generates voltage. In this example, the search coil 24 and the driving coil
Since the wire 23 is connected to the neutral point,
Prevents voltage from being applied to the control unit 27
For this purpose, the search coil 24 is
Is applied to the control unit 27.
Swelling. Therefore, the control unit 27
Is the zero cross point of the induced voltage. Control
The rule unit 27 has a zero cross point and
And the actual rotation speed ωact of the brushless motor 21
And a permanent magnet rotor (not shown) of the brushless motor 21
Position θ _MAsk for. The control unit 27
Other configurations and operations are as described in FIG.

FIG. 18 is a block diagram showing another example of detecting the rotor position of a DC brushless motor using a search coil. The feature of this example is that the neutral point of the search coil 24 and the neutral point of the drive winding 23 are disconnected, and the induced voltage generated in the search coil 24 is transmitted to the control unit 31 via the A / D converter 30. giving, in that so as to obtain the position theta _M of the permanent magnet rotor control unit 31 is not shown from the induced voltage itself of the brushless motor 21. The control unit 31 stores, for example, the previous maximum value of the induced voltage, and based on the ratio between this maximum value and the current voltage value of the induced voltage, the position θ _{M of the} permanent magnet rotor is set.
Is calculated. Other configurations are as described above.

In a hermetic compressor, a brushless motor is used in a high-temperature and high-pressure environment, so that it is difficult to use a rotary encoder or a Hall element.
In addition, when they are used, a space for installing them is required, which leads to an increase in size. On the other hand, according to the search coil as described above, it is only necessary to wind the search coil together with the drive winding, and it is not necessary to change the design of the entire configuration and also to secure a space for installation. Nor.

[0027]

As described above, according to the present invention, D
One switching element to be turned on, two switching elements to be turned on / off by PWM, and three switching elements to be turned off are selected based on the rotor position of the C brushless motor, and one switching element is set for each PWM cycle. By turning on / off the two switching elements with the elements on, the DC brushless motor can
Since the drive operation is performed at 0 degree, only two switching elements are turned on / off in each PWM cycle, so that the number of turn-on and turn-off of the switching elements can be extremely reduced, and switching loss can be reduced. Driver efficiency can be improved.

In each PWM cycle, an open period in which one switching element is turned on and all the other switching elements are turned off is formed, so that the circulating current can be more effectively used and the same period can be obtained. Energy can be reduced with respect to the generated torque.

Furthermore, since the search coil for detecting the rotor position is wound together with the three-phase drive winding in the status lot of the DC brushless motor, it is only necessary to wind the drive winding and the search coil together. There is no need to form an installation space in the DC brushless motor, and it can be applied very easily to existing DC brushless motors.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an example of an embodiment of the present invention.

FIG. 2 is a diagram showing a selection pattern of a switching transistor in FIG. 1;

FIG. 3 is a vector diagram showing how to obtain a voltage vector V applied to a three-phase drive winding of the brushless motor in the configuration of FIG.

FIG. 4 is a diagram showing a switching pattern for providing a basic vector in FIG. 3;

FIG. 5 is a timing chart of the switching transistor of FIG. 1 in one PWM cycle, showing a case where the phase of a voltage vector is 0 to 60 degrees.

FIG. 6 is a timing chart of the switching transistor of FIG. 1 in one PWM cycle, showing a case where the phase of a voltage vector is 60 to 120 degrees.

FIG. 7 is a timing chart of the switching transistor of FIG. 1 in one PWM cycle, showing a case where the phase of a voltage vector is 120 to 180 degrees.

FIG. 8 is a timing chart of the switching transistor of FIG. 1 in one PWM cycle, showing a case where the phase of the voltage vector is 180 to 240 degrees.

FIG. 9 is a timing chart of the switching transistor of FIG. 1 in one PWM cycle, showing a case where the phase of the voltage vector is 240 to 300 degrees.

FIG. 10 is a timing chart of the switching transistor of FIG. 1 in one PWM cycle, showing a case where the phase of a voltage vector is 300 to 360 degrees.

FIG. 11 is a control flowchart of the DSP of the control unit in FIG. 1, showing a control process performed for each PWM cycle.

FIG. 12 is a diagram for explaining a circulating current in the configuration of FIG. 1;

FIG. 13 is a timing chart showing another example of the on / off timing of the switching transistor in FIG. 1;

FIG. 14 is a timing chart showing still another example of the on / off timing of the switching transistor in FIG. 1;

FIG. 15 is a timing chart showing still another example of the on / off timing of the switching transistor in FIG. 1;

FIG. 16 is a configuration diagram illustrating an example of detecting a rotor position of a DC brushless motor using a search coil.

FIG. 17 is a sectional view of a status lot showing a stored state of a search coil.

FIG. 18 is a configuration diagram showing another example in the case of detecting the rotor position of a DC brushless motor using a search coil.

19A and 19B are explanatory diagrams for explaining a conventional 180-degree energizing drive of a brushless motor. FIG. 19A shows a drive circuit, and FIG. 19B shows a drive circuit of the switching transistor of FIG. 19A in one PWM cycle. 4 shows an example of a switching pattern.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Drive circuit Tu-Tz Switching transistor 2, 21 DC brushless motor 2a Permanent magnet rotor 3, 27, 31 Control unit 4 Position detecting means 5 DSP (Digital Signal Processor) 23 Drive winding 24 Search coil 25 Status lot

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Junyuki Takekawa 3-13-26, Yayumicho, Higashimatsuyama-shi, Saitama F-term in Zexel Higashimatsuyama Plant (reference) 5H560 AA02 BB04 BB12 DA02 DA05 DA07 DA14 DB20 DC02 DC13 EB01 GG03 SS01 TT15 UA02 XA12 XA13 XB09

Claims (7)

[Claims] 1. A driving device having six switching elements for controlling energization of a three-phase drive winding of a DC brushless motor, and energizing and driving the DC brushless motor by 180 degrees through PWM control of the switching elements. Selecting means for selecting one switching element to be turned on, two switching elements to be turned on / off by PWM, and three switching elements to be turned off based on the rotor position of the DC brushless motor; A DC brushless motor driving device in which two switching elements are turned on / off with one switching element turned on in each PWM cycle, so that the DC brushless motor is driven by 180 degrees. 2. A phase calculating means for calculating a phase of a voltage vector applied to a three-phase driving winding of the DC brushless motor based on a rotor position of the DC brushless motor, wherein the selecting means determines a phase of the voltage vector. The driving device for a DC brushless motor according to claim 1, wherein the switching element is selected according to the following. 3. An absolute value calculating means for calculating an absolute value of the voltage vector, and an absolute value calculated by the absolute value calculating means at the phase calculated by the phase calculating means. 3. The drive device for a DC brushless motor according to claim 2, further comprising setting means for setting a duty ratio of the two switching elements that are turned on / off by PWM. 4. The control device according to claim 3, further comprising control means for controlling the switching elements in accordance with the selection means and the setting means so that the ON states of the two switching elements which are turned on / off by PWM do not overlap. Drive device for DC brushless motor. Wherein said selecting means, a time width T ₁ to turn on one of the two switching elements to be turned on / off by PWM, a time width T ₂ to turn on the other, one switching element is turned on in the a time width T ₃ to turn off all the other switching elements, PWM on / off to DC brushless motor driving device according to claim 4 which is adapted to set the duty ratio of the two switching elements . 6. A method according to claim 1, further comprising: six basic vectors each having a phase difference of 60 degrees, wherein said phase calculating means specifies two basic vectors related to said voltage vector based on a phase of said voltage vector. The setting means sets the time widths T ₁ , T ₂ , T
The driving device for a DC brushless motor according to claim 5, wherein ₃ is calculated. (Equation 1) Here, A is the absolute value of the voltage vector, θ _V is the phase of the voltage vector, θ ₁ and θ ₂ are the phases of two basic vectors related to the voltage vector, and T _{P WM} is 1
PWM cycle. 7. A search brush wound around a status lot of the DC brushless motor together with the three-phase drive winding, and a rotor position of the DC brushless motor is given based on an induced voltage generated in the search coil. The driving device for a DC brushless motor according to claim 1, wherein