JPS62272896A - Driving method for dc brushless motor - Google Patents

Abstract

PURPOSE:To reduce the rotating irregularity in low speed region and to take out high output in high speed region, by changing over the conductive angle of each half wave for the armature current in each phase in accordance with the potating speed of a rotor to the preset value. CONSTITUTION:In case the rotating speed of a motor is lower than the set value, a change-over circuit 7 controlled by the output of a rotary encoder RE gives the position signal for 180 deg. type drive obtained by the first distribution circuit 4A to an adder 6. Transistors Qu-Qw and Qx-Qz are ON/OFF controlled by the 180 deg. type driving method. In case the rotating speed exceeds the set value, the change-over circuit 7 gives the position signal for 120 deg. type drive obtained by the second distribution circuit 4B to the adder 6 and the transistors Qu-Qw and Qx-Qz are ON/OFF controlled by the 120 deg. type driving method.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for driving a DC brushless motor.

[Prior Art] A DC brushless motor includes a rotor with a permanent magnet as a field, a stator with multiphase armature windings, a rotor position detection unit that detects the magnetic pole position of the rotor, It is equipped with a switch circuit provided between a DC power supply and an armature winding, and a drive circuit that controls opening and closing of the switch circuit based on a detection signal given from a rotor position detection section.
By opening and closing the switch circuit according to the position of it1, an alternating current corresponding to the position of the rotor magnetic poles is caused to flow through the armature windings of each phase to drive the rotor.

FIG. 6 shows a three-phase full-wave drive circuit as an example of the configuration of a drive circuit for a DC brushless motor 1 equipped with three-phase armature windings 1-u, LV, and LW. In this example, it is assumed that the armature windings 1u to W are concentratedly wound around three salient poles spaced apart by 120 degrees, and the rotor has two poles and the arc angle of each magnetic pole is 180 degrees. Suppose that it is degree.

In FIG. 6, S is PNPI-transistor Qu or Q
w and diodes [)U to [)W connected in antiparallel between the collectors and emitters of these transistors, and N whose collector-emitter circuits are connected in series to the collector-emitter circuits of the transistors QLJ to Qw, respectively.
A switch circuit consisting of a PN transistor Qx to QZ and a diode Dx to DZ connected in antiparallel to the collector-emitter circuit of these transistors, a series circuit of transistors Qu and Qx, a series circuit of transistors Q and Qy, A series circuit of transistors Qw and Qz is connected in parallel between the output terminals of the DC power supply 2. The three-phase armature windings LLJ to 1w are connected in a star pattern, and the terminals opposite to the neutral point of the windings 1u to LW are the connection points of transistors Qu and Qx, respectively, and the transistor Q
It is connected to the connection point between v and Qy and the connection point between transistors Qw and Qz.

PSu, PSv, and PSw are position sensors that are placed at positions corresponding to the stator magnetic poles around which the U, V, and W phase armature windings are wound, respectively, to detect the position of the rotor magnetic poles, and are located opposite to the rotor magnetic poles. It outputs a detection signal that lasts over an angular range (180 degrees in this example). A Hall element, a magnetoresistive element, etc. are used as these position sensors. The outputs of the position sensors PSu to PSw are input to a position signal output circuit 3 consisting of a waveform shaping circuit, etc., and position signals Hu to HW obtained from the signal output circuit 3 are input to a distribution circuit 4. Further, a rotary encoder RE that detects the rotational speed of the rotor is directly connected to the rotor,
A speed detection signal Vs of 1q from this rotary encoder is given to the speed control circuit 5. The controlling 0 signal 17 from the distribution circuit 4 and the control signal obtained from the speed control circuit 5 are added by the adder 6 (or an AND condition is taken by the AND circuit), and the transistor Qu~
are given to the bases of Qw and Qx-QZ, respectively.

The driving method for such a DC brushless motor is as follows:
Conducting angle α of each half-wave of armature current flowing through the lightning winding of each phase
Transistor Qu-Q so that the electrical angle is 120 degrees
A 120-degree drive method that turns on and off W and Qx to Qz, and turns each transistor on and off so that the conduction angle of each half wave of the electric brush current flowing through the armature winding of each phase is 180 degrees in electrical angle. There are 180-degree drive methods for controlling the motor, and examples of timing charts for these drive methods are shown in FIGS. 3 and 4, respectively.

FIG. 3 is a timing chart when a 120-degree drive method is adopted. In this case, the position signals Hu to HW are the rotational angles (electrical angles) of the rotor as shown in FIGS. ) between 30 degrees and 210 degrees, 15
It outputs a rectangular wave signal that lasts for an interval of 0 degrees to 330 degrees and an interval of 270 degrees to 90 degrees.

The distribution circuit 4 inputs the position signal Hu or 1-1w and outputs the transistors Q IJ h to Qw and Qx to Q.
The supply of base current to Z is i+II 1G to control on/off of these transistors. transistor Qu,
The sections in which Qv, Qw, Qx, Qy, and QZ produce ON rJ+ are shown in the form of rectangular waves in FIGS. 3(d) to 1), respectively. By turning on and off these transistors, armature currents 1u to I alternate in armature windings 1-u to 1w as shown in FIG. 3 (j>or λ), respectively.
W flows. In this case, the conduction angle α of each half-wave of each type current is
is 120 degrees in electrical angle. These armature currents generate a rotating magnetic field, causing the rotor (not shown) to move from U→■→W.
Rotate in the direction of.

In addition, when the 180-degree drive method is adopted, the position signal ports U to l-1w are, for example, shown in FIGS. 4(a) to C).
In this case, the i12 position signal Hu to l-1
w is the interval from 0 degrees to 180 degrees in electrical angle, 12
An interval of 0 degrees to 300 degrees and an interval of 240 degrees to 60 degrees occur. The distribution circuit 4 inputs these position signals to the transistors Qu to Qw and Qx.
By controlling the supply of base current to QZ or QZ,
These transistors are controlled to be turned on and off as shown in d) or i). By turning on and off these transistors, the armature windings lu to LW are changed to the values shown in Fig. 4 (j
) As shown in the diagram, an alternating armature current 1u to [W flows. In this case, each half-wave energization α of each armature N current is 180 degrees in electrical angle.

The speed control circuit 5 generates a control signal for performing chopper control to maintain the rotational speed at a set value, and the control signal supplied from the speed control circuit 5 is supplied to the transistors Qu to Qw and QX to QZ, respectively. The base current generated is intermittent. As a result, the transistors Qu to Qw and Qx to QZ are turned on and off at predetermined intervals within their respective conduction periods To (times corresponding to the conduction angle α of half waves of each armature current) as shown in FIG. The duty of each transistor during the ON period is controlled according to the detected value of the rotation speed, and thereby the average value of each [1 child current] is controlled and the rotation speed is maintained at the set value.

[Problems to be solved by the invention] As mentioned above, in the DC brushless motor, 120
Although it is possible to control the speed by chopper control when using either the degree drive method or the 180 degree drive method, the following problem occurs when trying to change the speed from a low speed range to a high speed range.

That is, when a 120-degree drive method is adopted, stable operation with less rotational unevenness can be achieved in the high-speed range, but it is unavoidable that rotational unevenness increases in the low-speed range. Furthermore, if a 180-degree drive method is used, rotational unevenness in the low speed region can be reduced;
It is less efficient than the 20-degree drive method, and
If the windings are constructed with the same amount of copper as in the case of using the 20 degree drive method, high speed and large output cannot be obtained.

In order to use a 180-degree drive method and increase the output at high speeds, it is necessary to increase the cross-sectional area of the windings, which increases the size of the windings and rotor, making the motor larger. cannot be avoided.

The reason why these problems occur is when a 120-degree driving method is used and when a 180-degree driving method is used.
This is said to be due to the difference in the number of phases through which armature current flows simultaneously. In other words, in the case of a 120 degree shape, 2
This is because the armature current flows through the windings of each phase, but in the case of a 180 degree type, the armature current flows simultaneously through the windings of three phases.

As mentioned above, when a 120-degree drive method is used, it is not possible to achieve rotational unevenness in the low-speed range, and when a 180-degree drive method is used, high-speed operation is not possible in the high-speed range. Since it is not possible to operate efficiently, it has not been possible to obtain a small DC brushless motor that has little rotational unevenness in the low speed range and can obtain high output in the high speed range.

The purpose of the present invention is to propose a method for driving a DC brushless motor that solves the above-mentioned problems, reduces rotational unevenness in the low speed range, and makes it possible to obtain high output in the high speed range without increasing the size of the motor. It's about doing.

[Means for Solving the Problems] The present invention detects the position of the rotor magnetic poles and uses a switch circuit provided between the DC power supply and the armature windings of each phase to detect the position of the rotor magnetic poles. This is a DC brushless morph drive method that drives the rotor by passing alternating current through the armature windings of each phase by opening and closing depending on the position.It reduces rotational unevenness in the low speed region and also reduces the size of the motor. 1? This makes it possible to extract high output in the high-speed range without the need for l <.

Therefore, in the present invention, when the rotational speed of the rotor is below the set value, the conduction angle of each half wave of the armature Ti flow of each phase is reduced to 1.
80 degrees, and when the rotation speed exceeds a set value, the conduction angle of the armature current is switched according to the rotation speed so that the conduction angle of each half wave of the armature current of each phase is 120 degrees.

[Operation of the invention] By switching the conduction angle of the armature current according to the rotational speed as described above, the advantages of the 120-degree drive method and the 180-degree drive method can be utilized to achieve low speed range and high speed range. It is possible to perform satisfactory operation in the low speed range, reduce uneven rotation in the low speed range, and perform highly efficient operation in the high speed range. Therefore, it is possible to widen the usable rotational speed range and obtain high speed and large output without increasing the size of the motor.

[Example] The present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 schematically shows an example of the configuration of a drive circuit that implements the drive method of the present invention. Although various configurations of the device for carrying out the driving method of the present invention can be considered, in the example shown in FIG.
Two sets of position sensors are provided: position sensors p3u2 to pSw2 used in the 120-degree drive method, and the outputs of the position sensors p3u1 to p3w1 are sent to the first position signal output circuit 3A, and the position sensors p3
The outputs of u2 to p3w2 are output from the second position signal output circuit 3.
Each is input in B. The first and second position signal output circuits 3A output position signals HU to l-(w when implementing the 180-degree drive method shown in FIG. Position signals Hu to HW are output when the 120-degree drive method shown in FIG. 3 is implemented.

The outputs of the first and second position signal output circuits 3A and 3B are input to the first and second distribution circuits 4A and 4B, respectively, and the outputs of these distribution circuits are input to the adder 6 via the switching circuit 7. has been done.

The first distribution circuit 4A includes position sensors p3u1 to p3w.
Using the output of 1 as an input, the transistors Qu to Qw and Qx to QZ are driven in a 180 degree manner as shown in FIG.
outputs a signal to the base of each transistor to control on/off. Further, the second distribution circuit 4B inputs the outputs of the position sensors p3u2 to p3w2, and receives the third distribution circuit 4B.
In order to control on/off of the transistors Qu through Qw and Qx through Qz using the 120 degree driving method shown in the figure, a signal is outputted to the base of each transistor.

The switching circuit 7 inputs the rotation speed detection signal given from the rotary encoder RE, and selects the first switch according to the rotation speed.
and the outputs of the second distribution circuits 4A and 4B are selected and applied to the adder (or AND circuit) 6.

In other words, when the rotation speed is below the set value, the switching circuit 7
The position signals Hu to HW for 180-degree drive obtained from the first distribution circuit 3A are applied to the adder 6 to drive the transistors Qu to Q in the 180-degree drive method shown in FIG.
On/off control of w and Qx to QZ is performed. Further, when the rotation speed exceeds the set value, the switching circuit 7 supplies the position signals Hu to Hw for 120-degree drive obtained from the second distribution circuit 4B to the adder (or AND circuit) 6. The on/off control of transistors QLl to Qw and Qx to Qz is performed using the 120-degree drive method shown in FIG. Other points are similar to the drive circuit implementing the conventional drive method shown in FIG.

When implementing the drive method of the present invention, the set value of the rotation speed at which the switching circuit 6 performs the switching operation is set to the lower limit of the rotation speed range that allows operation with small rotational irregularities when a 120-degree drive method is adopted, for example. do.

By setting in this way, it is possible to widen the speed range in which the vehicle can be operated with high efficiency. When setting the rotation speed as described above, the set rotation speed can be easily determined by conducting an experiment in which the motor is driven using a 120-degree drive method and measuring the characteristics of rotation fluctuations. can.

In the above embodiment, the first and second distribution circuits 4A and 4
B is a transistor Qu in response to position signals given from the first and second position signal output circuits 3A and 3B, respectively.
The base current is distributed to Qw and QxQ to Qz to control on/off of these transistors. To explain the operation of these distribution circuits in more detail, the first distribution circuit 4Δ receives the position signal l-I as shown in FIG.
A base current is passed through the transistors Qu, Qv, and Qw during the period when u, H■, and Hw are generated, respectively, to sequentially turn on these transistors. Also position signal)
A base current is caused to flow through the lock transistors Qu, Qv, and Qw, in which negative signals of 1u, Hv, and )1w are generated, respectively, to sequentially turn on these transistors. Windings 1-u to L are turned on and off by turning on and off these transistors.
Alternating armature currents 1u to IW flow through W as shown in FIGS. 4(j) to 4(f).

Further, as shown in FIG. 3, the second distribution circuit 4B operates during the period from the rise of the position signal 1u to the rise of the position signal Hv, and from the rise of the position signal H■ to the rise of the position signal)-
During the period from the rise of position signal Hw to the rise of position signal Hu, a base current is passed through each of transistors Qu and Qv to make these transistors conductive in sequence, and the base current is supplied to transistor Qw during the period from the rise of position signal Hw to the rise of position signal Hu. Make Qw conductive. Also, the position signal HU
A base current is supplied to each of the transistors Qx and Qy to make these transistors conductive during the period from the fall of the position signal Hv to the fall of the position signal Hv and from the fall of the position signal 1-1v to the fall of the position signal HW. , position signal)
A base current is supplied to the transistor QZ for a period from the falling edge of 1w to the falling edge of the position signal 1''U to make the transistor QZ conductive.

By turning on and off these transistors, the armature winding 1
Alternating armature currents 1u to 1w flow in u to 1w, respectively, as shown in FIG. 3(j) to 1w.

The first and second distribution circuits can be configured using logic circuits.

FIG. 2 shows an example of the mechanical configuration of the DC brushless motor 1 used when carrying out the method of the present invention. The armature core protrudes radially at 120 degree intervals, with salient pole parts 102u to 102w.
Pole piece portions 103u to 103W are provided at the tips of the respective pole pieces 103u to 103W. The salient pole portions 102u to 102w are provided with opening and W-phase ff1lfi child windings, respectively.
are wound, and these windings are connected in a star shape as shown in FIG. Armature core 100 and winding L or 1
w constitutes a stator 105, and this stator is fixed to a frame or case (not shown).

The rotor 106 includes a cup-shaped rotating body 107 and two arc-shaped permanent magnets 108 and 109 having a polar arc angle of 180 degrees.
A rotating shaft (not shown) fixed to the bottom wall of the rotating body 107 is provided through a hole inside the yoke 101 of the armature core 100, and a bearing is attached to the end wall of the frame or case (not shown). Supported by

The permanent magnets 108 and 109 are magnetized in the radial direction so that their inner circumferential sides are N and S poles, and these magnets constitute two rotor magnetic poles each having a polar arc angle of 180 degrees. ing.

As shown in FIGS. 3 and 4, the generation section of the position signal is different depending on the 120-degree drive method and the 180-degree drive method, and usually the difference between these drive methods is Due to the difference, the positions of the position sensors are different by 30 degrees. In this example, the center of the stator magnetic pole of the beam phase is set to 0.
The position sensors PSu1 to p3wl used in the 180-degree driving method are mounted with their centers aligned with the center positions of the pole pieces 103u to 103W. In addition, the position sensors p3u2 to PSw2 used in the 120-degree drive method are installed so that their respective centers coincide with positions deviated by 30 degrees from the center positions of the pole pieces 103u to 103W on the opposite side (toward the lag side) of the rotation direction. It is being A Hall element is used as each position sensor.

It should be noted that the installation of each of the above position sensors is optional. [It may be fixed to the child core, and if a printed circuit board on which electronic components constituting the drive circuit are attached is fixed to the armature core, motor frame, or case, each position sensor may be fixed to the printed circuit board.] It may be fixed.

In the above description, a magnetic detection element is used as a position sensor, but the present invention can also be applied to the case where the position of the rotor magnetic poles is photoelectrically detected.

In the above embodiment, the rotor has two poles, but the present invention can also be applied to a case where a multi-pole rotor is used.

In the above embodiment, the three-phase armature windings are connected in a star shape, but the present invention can also be applied to a case where the three-phase armature windings are connected in a triangular manner.

[Operation of the invention 1] As described above, by switching the conduction angle of the armature current according to the rotation speed, it is possible to take advantage of the advantages of the 120-degree drive method and the 180-degree drive method, and It is possible to operate with less irregular rotation in the range, and to operate with high efficiency in the high speed range. Therefore, there is an advantage that the usable rotational speed range can be expanded and high speed and large output can be obtained without increasing the size of the motor.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram schematically showing the configuration of a drive circuit used to implement the method of the present invention, and FIG. 2 is a configuration showing the mechanical configuration of a motor used when implementing the method of the present invention. Figures 3 and 4 are 120 degrees and 1, respectively.
The timing diagram does not show the 80-degree drive method. Figure 5 is a diagram showing the on/off operation of the transistor when speed control is performed by chopper control. Figure 6 is the configuration of the drive circuit when using the conventional drive method. FIG. 1... DC brushless motor, 2... DC power supply, 3
△, 3B...Position signal output circuit, 4A, 4B...Distribution circuit, 5...Speed control circuit, 6...Adder, RE
...Rotary encoder, PSu1~PSW1...
Position sensor for 180 degree drive, p3u2~p3w2・
・Position sensor for 120 degree drive, Qu-Qw, Qx-
Qz...transistor. Figure 3 Figure 4

Claims (1)

[Claims] By detecting the position of the rotor magnetic poles and opening and closing a switch circuit provided between the DC power supply and the armature windings of each phase according to the detected position of the rotor magnetic poles. In a DC brushless motor drive method in which alternating current is passed through the armature windings of each phase to drive the rotor, each half-wave of the armature current of each phase is energized when the rotational speed of the rotor is below a set value. The conduction angle of the armature current is set to 180 degrees, and the conduction angle of the armature current is adjusted according to the rotation speed so that when the rotation speed exceeds a set value, the conduction angle of each half wave of the armature current of each phase is 120 degrees. A method for driving a DC brushless motor characterized by switching.