JPH04222487A - System for controlling constant-velocity rotation of motor - Google Patents

Abstract

PURPOSE:To maintain the constant-velocity rotation well and maintain the motor efficiency well even in the case that the torque of the motor changes. CONSTITUTION:In the constant-velocity rotation control system for a motor, it is provided with a position detecting means 13, which detects the rotational position of the motor and generates a position detection signal, a rotation time information measuring means 14, which measures the motor rotation time information from the position detection signal, a current quantity determining means 15, which the quantity of a motor driving current to be supplied to a driving coil 12 based on the rotation time information and the target rotation information of the motor, an electric angle determining means 16, which determines the electric angle of the motor driving current based on the quantity of current, and a motor driving current supply means 17, which supplies, having the electric angle to the position that the position detecting means 13 having detected, the motor driving current of the quantity of current to the corresponding driving coil 12.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling constant speed rotation of a motor when the motor is rotated at a constant speed by a motor drive current supplied to a drive coil of the motor, such as in a DC brushless motor.

0002

2. Description of the Related Art In a motor that is controlled to rotate at a constant speed, such as a DC brushless motor, a motor drive current is supplied to its drive coil to drive the motor to rotate. Next, a conventional constant speed rotation control method for a motor will be described with reference to FIGS. 7 and 8. In the constant speed rotation control method of the motor shown in FIG.
3, position detectors 2131 to 2133 are the main components.

[0003] The rotor magnet 211 has a rotor portion made of a magnet. Drive coil 2121 ~
A motor drive current for driving the rotor magnet 211 is periodically supplied to 2123 . Position detector 213
1 to 2133 are constituted by Hall elements, for example, and detect the opposing position of the magnetic pole of the rotor magnet 211 and the drive coil to generate a position detection signal.

Reference numeral 22 denotes a switching circuit, which switches direct current using a switching element (not shown) to periodically supply a predetermined motor drive current to drive coils 2121 to 2123. A logic circuit 23 generates a drive pattern for driving each switching element of the switching circuit 22 in response to position detection signals generated by the position detectors 2131 to 2133. A level conversion circuit 24 converts the level of the drive pattern generated by the logic circuit 23 to a level that can drive the switching circuit 22.

Next, a constant speed rotation control method for the motor in the motor control device shown in FIG. 7 will be explained with reference to an operation timing chart shown in FIG. FIG. 8 is an operation timing chart showing the relationship among the induced voltage of each drive coil, motor drive current, position detection signal, etc. during constant speed rotation, that is, in a steady state.

[0006] In FIG. 8, H1 to H6 indicate the operating states during one rotation of the motor, divided into six sections, each section having a rotation angle of 60 degrees. V1,
V2 and V3 are drive coils 2121 and 2122
and 2123, which is equal to the induced voltage of each drive coil. For the contents of other codes,
This will be explained as appropriate in the following operation description.

■State H1 In state H1, the rotor magnet 211 is in the position shown. At this time, the position detector 2132 generates a position detection signal c, and the position detector 2133 generates a position detection signal a and sends it to the logic circuit 23. The logic circuit 23 receives this position detection signal c
and a, it generates a drive pattern P1 (AH=CL=1, others 0) shown in FIG. 8 in synchronization with the position detection signal, and supplies it to the level conversion circuit 24.

The level conversion circuit 24 is a logic circuit 23
The level of the driving pattern P1 inputted from the converter converts the level of the driving pattern P1 inputted from the converter into a level at which the switching circuit 22 can be driven. When the switching circuit 22 receives the drive pattern P1 converted to a high level, the switching circuit 22 switches the DC power supply voltage Vcc using a switching element (not shown) to supply the motor drive current AH to the corresponding drive coil 2121 to drive the motor. The motor drive current CL is made to flow through the coil 2123.

Here, the code “CL
”, the first code “C” is the drive coil 2133
This indicates that the motor drive current is supplied to
" indicates that the motor drive current returns from the drive coil 2133 to the switching circuit 24 side. The motor drive current flowing from the switching circuit 24 to the drive coil 2133 is indicated by "CH". Therefore, in the operating state, the motor drive current CL becomes a return current of the motor drive current AH. This also applies to each motor drive current supplied to other drive coils described below.

[0010]Moreover, the motor drive current is supplied to the drive coil 213.
3 (indicated by diagonal lines in the figure; the same applies to the motor drive currents at the time of startup in other drive coils). When receiving the motor drive currents AH and CL, the rotor magnet 211 rotates in the direction of the arrow and enters state H2.

■State H2 In state H2, the position detector 2133 detects that the rotor magnet 211 is connected to the drive coil 2.
123 and generates a position detection signal a, which is sent to the logic circuit 23. logic circuit 2
3, upon receiving this position detection signal a, outputs the position detection signal a.
Drive pattern P2 (AH=BL
= 1, others 0) and supplies it to the level conversion circuit 24.

When the switching circuit 22 receives this drive pattern P2 via the level conversion circuit 24, it supplies the motor drive current AH to the corresponding drive coil 2121 by switching the power supply voltage Vcc using a switching element (not shown). , so that the return motor drive current BL flows through the drive coil 2122. When receiving the motor drive currents AH and BL, the rotor magnet 211 rotates to state H3.

■State H3 In state H3, the position detector 2133 generates the position detection signal a, and the position detector 21
31 generates a position detection signal b and sends it to the logic circuit 23. The logic circuit 23 receives these position detection signals a and b.
When received, a drive pattern P3 (BL=CH=1, others are 0) shown in FIG. 8 is generated in synchronization with the position detection signal and supplied to the level conversion circuit 24.

When the switching circuit 22 receives this drive pattern P3 via the level conversion circuit 24, it supplies the motor drive current CH to the corresponding drive coil 2123, and returns the motor drive current BL to the drive coil 2122.
Let it flow. These motor drive currents CH and BL
When received, the rotor magnet 211 rotates to state H.
It becomes 4.

■State H4 In state H4, the position detector 2131 generates a position detection signal b and sends it to the logic circuit 23. The logic circuit 23 receives this position detection signal b
When the drive pattern P4 (AL=CH
=1, otherwise 0) and supplies it to the level conversion circuit 24.

When the switching circuit 22 receives this drive pattern P4 via the level conversion circuit 24, it supplies the motor drive current CH to the corresponding drive coil 2123 and returns the motor drive current AL to the drive coil 2121.
Let it flow. These motor drive currents CH and AL
When received, the rotor magnet 211 rotates to state H.
It becomes 5.

■State H5 In state H5, the position detector 2131 generates the position detection signal b, and the position detector 21
32 generates a position detection signal c and sends it to the logic circuit 23. The logic circuit 23 synchronizes with this position detection signal to create a drive pattern P5 (AL=BH=1,
Others generate 0) and supply it to the level conversion circuit 24.

When the switching circuit 22 receives this drive pattern P5 via the level conversion circuit 24, it supplies the motor drive current BH to the corresponding drive coil 2122 and returns the motor drive current AL to the drive coil 2121.
Let it flow. These motor drive currents BH and AL
When received, the rotor magnet 211 rotates to state H.
It becomes 6.

■State H6 In state H6, the position detector 2132 generates the position detection signal c and the logic circuit 2
Send to 3. The logic circuit 23 synchronizes with this position detection signal c to create a drive pattern P6 (BH=CL=
1, others are 0) and supplied to the level conversion circuit 24.

When the switching circuit 22 receives this drive pattern P6 via the level conversion circuit 24, it supplies the motor drive current BH to the corresponding drive coil 2122. Upon receiving this motor drive current BH, the rotor magnet 211 rotates and returns to the initial operating state H1. Thereafter, the operations ① to ① described above are repeated, and the rotor magnet 211 rotates at a constant speed as shown in FIG. This is the steady rotation state of the motor.

[0021] In constant speed rotation, that is, in a steady rotation state, the rotation speed of the motor (rotor magnet 211) is sufficiently high, so that each of the drive coils 2121 to 21123
The amplitude of the electromotive voltages V1 to V3 induced in the motor becomes large as shown in the figure, and each motor drive current (the shaded portion in FIG. 9) becomes a small level. Therefore, power consumption in a steady rotation state is reduced, and efficient rotation can be achieved.

[0022] In this way, in the motor control device, the timing for switching the motor drive current in synchronization with the position detection signal of the position detector (Hall element) is selected to be the timing at which the motor efficiency is maximized during steady rotation. Ta.

[0023]

[Problems to be Solved by the Invention] In the conventional constant speed rotation control system for a motor, as mentioned above, the motor drive is supplied to the drive coil in synchronization with a motor position detection signal from a position detector such as a Hall element. The current is switched, and the timing of this switching is set so that the motor power consumption during constant speed rotation (steady rotation) is minimized, that is, the motor efficiency is maximized (the area of the shaded part in Figure 8 is minimized). ) was selected.

However, while this conventional motor constant speed rotation control method has the advantage of maximizing motor efficiency, it also minimizes the motor drive current, that is, the area of the shaded area in FIG. As a result, the following problems arose.

In other words, if there is insufficient torque margin during steady rotation and the power supply voltage drops for some reason, if the induced voltage in the drive coil becomes higher than the specified value, or if the drive coil is used in environments ranging from room temperature to low temperature, If a situation occurs where the motor torque decreases or conversely requires a large torque, such as when the friction during motor rotation increases due to changes in the environment and a large torque is required, constant speed rotation, In other words, there was a risk that steady rotation could not be maintained.

[0026] The present invention makes it possible to maintain constant speed rotation, that is, steady rotation, and maintain good motor efficiency even when the motor torque decreases or, conversely, a large torque is required. The purpose of the present invention is to provide an improved constant speed rotation control method for a motor.

[0027]

[Means for Solving the Problems] The torque of the motor is proportional to the amount of current supplied to the drive coil when the power supply voltage is constant. As shown in FIG. 1B, this current amount is proportional to the area surrounded by the power supply voltage Vcc, the induced voltage V of the drive coil, and the current conduction time TC. Then, if this area can be expanded, it is possible to increase the torque of the motor.

This increase in area can be achieved by, for example, as shown in FIG. 1C, by speeding up the switching timing TH of the position detection means and the switching timing of the motor drive current supplied to the drive coil. . Hereinafter, the interval between these two timings will be referred to as an electrical angle. however,
If this electrical angle is always maintained at an advanced angle state as shown in FIG. 1(C), the motor drive current, that is, the power consumption will increase, and the motor efficiency will decrease.

Therefore, by constantly determining whether it is difficult to maintain steady rotation or when it is easy, the electrical angle is determined as shown in FIG.
By appropriately switching between the state shown in (B) and the state shown in (C) in the figure, constant speed rotation can be maintained even when the motor torque decreases or a situation that requires a large torque occurs. It is possible to maintain good motor efficiency.

The present invention was made based on this idea, and the means adopted by the present invention to solve the above-mentioned problems will be explained below with reference to FIG. Figure 1(A)
FIG. 1 is an explanatory diagram of the basic configuration of the present invention. In FIG. 1(A), 10 is a motor, which includes a rotor magnet 11, drive coils 121 to 123, and position detection means 131.
~133. The rotor magnet 11 has a rotor portion composed of a magnet, and drive coils 121 to 1.
23 is rotated by a motor drive current periodically supplied to the motor.

The position detection means 131 to 133 are composed of, for example, Hall elements, and detect the rotational position of the motor, that is, the opposing position of the drive coil corresponding to the magnetic pole of the rotor magnet 11, and generate a position detection signal. . 1
4 is a rotation time information measuring means, and a position detecting means 131
A process of measuring information related to the rotation time of the motor (rotation time information) is performed based on the position detection signal generated in 133 to 133.

Reference numeral 15 denotes a current amount determining means, which determines the drive coils 131 to 133 based on the rotation time information of the motor measured by the rotation time measuring means 14 and information related to the target rotation speed of the motor (target rotation speed information). Determine the amount of current supplied to the This amount of current can be determined, for example, by the current application time of the motor drive current.

Reference numeral 16 denotes an electrical angle determining means, which performs a process of determining the electrical angle of the motor drive current based on the amount of current determined by the amount of current determining means 15. Note that, as described above, the electrical angle is an amount indicating the interval between the switching timing of the position detecting means and the switching timing of the motor drive current supplied to the drive coil, and is expressed by a rotation angle, time, phase, etc.

Reference numeral 17 denotes a motor drive current supply means, which supplies the current determined by the current amount determining means 15 at the electrical angle determined by the electrical angle determining means 16 with respect to the rotational position of the motor detected by the position detecting means 131 to 133. The process of supplying the same amount of motor drive current to the next drive coil is performed. In addition,
Although FIG. 1 shows a three-phase case as an example, the present invention
It is not limited to the case of a phase, but is applied to the case of a multiphase other than three layers.

[0035]

[Operation] A motor drive current is periodically supplied from the motor drive current supply means 17 to the drive coils 121 to 123. As a result, the motor (rotor magnet 11) is driven to rotate, increases its rotational speed, and reaches a steady rotation state. The position detection means 131 to 133 detect the rotational position of the motor, that is, the opposing position of the drive coil corresponding to the magnetic pole of the rotor magnet 11, and send it to the rotation time information measurement means 14.

The rotation time information measuring means 14 measures rotation time information related to the rotation time of the motor based on the position detection signals detected by the position detection means 131 to 133 and sends it to the current amount determining means 15. The current amount determining means 15 determines the amount of current to be supplied to the drive coils 131 to 133 based on the rotation time information of the motor measured by the rotation time measuring means 14 and the target rotation speed information related to the target rotation speed of the motor. . This amount of current can be determined, for example, by the duty ratio of the motor drive current, the current energization time, and the like.

On the other hand, the electrical angle determining means 16 performs a process of determining the electrical angle of the motor drive current based on the amount of current determined by the amount of current determining means 15 (details of the specific method for determining the electrical angle). will be explained in the Examples section). The motor drive current supply means 17 supplies the motor drive current of the amount of current determined by the current amount determination means with the electrical angle determined by the electrical angle determination means 16 to the rotational position of the motor detected by the position detection means. Performs processing to supply the drive coil.

In this case, the electric current is By controlling the angle, stable constant speed rotation control can be performed (details of a specific method for switching the electrical angle will be explained in the Examples section).

As described above, the present invention corresponds to the rotational position of the motor detected by the position detecting means by applying the motor drive current of the current amount determined by the current amount determining means using the electrical angle determined by the electrical angle determining means. Since the motor is supplied to the drive coil, it is possible to maintain constant speed rotation even in situations where the motor torque decreases or conversely requires a large torque, and the motor efficiency is also maintained. can do.

Furthermore, the electrical angle is determined based on the lower limit number of times the duty ratio of the motor drive current is continuously less than or equal to the specified lower limit value and the upper limit number of times that the duty ratio is continuously less than or equal to the specified upper limit value. By controlling , stable constant speed rotation control can be performed.

[0041]

Embodiment An embodiment of the present invention will be described with reference to FIGS. 2 to 6. FIG. 2 is an explanatory diagram of a motor constant speed rotation control method according to an embodiment of the present invention, FIG. 3 is an operation flowchart during electrical angle control according to an embodiment of the present invention, and FIG. 4 is an operation diagram of an embodiment of the present invention. FIG. 5 is an operation timing chart when electrical angle control is not performed in the same embodiment, and FIG. 6 is an operation timing chart when electrical angle control is performed in the same embodiment.

(Configuration of Example) In FIG. 2, a synchronous motor 10, a rotor magnet 11, a drive coil 121 to
123, position detection means 131 to 133, rotation time information measurement means 14, current amount determination means 15, electrical angle determination means 16, and motor drive current supply means 17, as shown in FIG.
As explained in . The rotation time information measuring means 14 includes an input register 141 therein, and each position detection signal generated by the position detecting means 131 to 133 is input to and held in the input register 141.

In the motor drive current supply means 17, 1
70 is a level conversion circuit, and 171 to 176 switch the DC power supply voltage Vcc to each drive coil 12.
This is a switching element that periodically supplies a predetermined motor drive current to motors 1 to 123. The level conversion circuit 170 performs a process of converting the level of a drive pattern generated by the logic circuit 19, which will be described next, to a level that can drive the switching circuit 12.

The switching element 171 is connected to the drive coil 12
The switching element 172 supplies the motor drive current AL to the drive coil 121. The switching element 173 is the drive coil 122
The motor drive current BH is supplied to the switching element 17.
4 supplies the motor drive current BL to the drive coil 122. The switching element 175 supplies the motor drive current CH to the drive coil 123, and the switching element 176 supplies the motor drive current CL to the drive coil 123.

Reference numeral 19 denotes a logic circuit, which includes rotation time information measuring means 14, current amount determining means 15, and electrical angle determining means 1.
6 and a control processor 18, and generates a drive pattern for driving the motor drive current supply means 17 in response to position detection signals generated by the position detection means 131 to 133.

The control processor 18 has an output register 18
1, the motor drive current of the current amount determined by the current amount determining means 15 is determined by the electric angle determined by the electrical angle determining means 16 with respect to the rotational position of the motor detected by the position detecting means 131 to 133. It performs processing to generate a drive pattern to be supplied to the drive coil of and writes it into the output register 181, and also controls the entire device.

(Operation of Embodiment) Before explaining the detailed operation of an embodiment of the present invention, an overview of the operation of this embodiment will be explained. The position detection signal is input to the input register 141 of the rotation time information measuring means 14, and a drive pattern for generating a motor drive current is generated by the logic circuit 19 and written to the output register 181.

There are various methods for adjusting the amount of motor drive current supplied to the drive coils 131 to 133.
In this embodiment, this is performed by changing the current application time, that is, the duty ratio, and by changing the electrical angle. That is, position detection means 131 to 13 such as Hall elements
1 of the motor due to the period of the position detection signal generated in 3.
The rotation period is measured, control calculations are performed between it and the target rotation speed, and the duty ratio of the motor drive current supplied to the drive coil is determined. This calculation of the duty ratio is performed every rotation of the motor.

When the electrical angle is constant, if there is little torque margin for steady rotation, a large duty ratio is selected, and conversely, if there is little torque margin, a small duty ratio is selected. When there is little torque margin, the electrical angle is adjusted to be delayed, and conversely, when there is a large torque margin, the electrical angle is adjusted to be advanced (or returned to 0 degrees). One of the features of the present invention is that the electrical angle is determined based on the duty ratio, thereby achieving both efficient control and maintaining steady rotation of the motor designed to save energy. It is possible to achieve both.

The electrical angle control and current conduction time (duty ratio) control described above are performed by controlling the drive timing and current conduction time of the switching elements based on the position detection signals of the position detection means 131 to 133. A drive pattern for this purpose is supplied to each switching element of the motor drive current supply means 17.

By the way, since the motor torque T is a function of the supplied power, it is a function of the duty ratio (denoted by DUT) and the electrical angle (denoted by DEL), and T=T(DUT,D
EL). Note that the electrical angle DEL is expressed as an angle when one cycle of the induced voltage of the drive coil (one rotation time of the motor) is 360 degrees.

This indicates that there is a possibility that the torque T may become unstable if the electrical angle is controlled based on the duty ratio. Therefore, in this embodiment, the duty ratio DUT is determined for each revolution of the motor, whereas the electrical angle DEL is changed very slowly based on the value of the duty ratio DUT over several tens of revolutions. , electrical angle D
In order to make it easier for el to settle down, a certain duty ratio D
Control is performed by providing a dead zone in which electrical angle control is not performed in the UT range.

In the following embodiment, this electrical angle control is performed based on the lower limit number of times DTL and the upper limit number of times DTG.
The lower limit number of times DTL is the number of times that the duty ratio is continuously less than or equal to a certain value, and the upper limit number of times DTG is the number of times that the duty ratio is continuously less than or equal to a certain value.

The values of the lower limit number of times DTL and the upper limit number of times DTG and the values of each duty ratio in that case are selected in consideration of stability, motor efficiency, etc. In this embodiment, the value of the lower limit number of times DTL is 70. (one count per revolution of the motor), and the duty ratio in that case is selected to be 95%. On the other hand, the value of the condition number of times DTL is also 70 times, and the duty ratio in that case is selected to be 98%.

Therefore, in this embodiment, when the duty ratio DUT is between 95% and 98%, the electrical angle DEL does not change and becomes a dead zone. In addition, the electrical angle DEL is used to efficiently control the amount of current within a range where the motor does not function as a generator.
It is variably controlled in the range of 0 degrees to 20 degrees.

The operation of the embodiment will be described below with reference to the operation flowchart of FIG. 3, the operation waveform diagram of FIG. 4, and the operation timing charts of FIGS. 5 and 6, and according to each processing step of the operation flowchart of FIG. Each of the following processes is performed every rotation of the motor. Note that, prior to the start of the operation, the electrical angle DEL=20 degrees, the lower limit number of times DTL=0, and the upper limit number of times DTG=0 are initialized, respectively.

(1) Step S1 Position detection means 131
133 detects the position of the rotor magnet 11 and inputs the position detection signal to the input register 141 of the rotation time information measuring means 14. Rotation time information measuring means 1
4 measures rotation time information related to the rotation time of the motor based on the position detection signal input to the input register 141 and sends it to the current amount determining means 15 . As the rotation time information, in this embodiment, the time required for one rotation of the motor (one rotation time) is measured.

The current amount determining means 15 determines whether the drive coil 1
The amount of motor drive current to be supplied to 31 to 133 is determined. In this embodiment, one rotation time of the motor in a normal steady rotation state (target one rotation time) is used as the target rotation speed information, and the current amount is determined by the duty ratio DUT indicating the current energization time of the motor drive current. It is determined.

[0059] The time for one rotation of the motor in steady state becomes longer when the torque is large, and becomes shorter when the torque is small. Therefore, if the optimal duty ratio DUT corresponding to each type of motor rotation time during steady state is determined in advance through experiments and made into a table, by referring to this table, one rotation time of the motor during steady state can be calculated. The corresponding optimum duty ratio DUT can be easily obtained from .

On the other hand, in order to determine the electrical angle of the motor drive current based on the duty ratio DUT determined by the current amount determining means 15, the electrical angle determining means 16 selects the lower limit number of times DTL.
is larger than the set value 70 (step S
1). If the lower limit number of times DTL is smaller than 70, the motor rotation speed is higher than the lower limit, so step S5, which will be described later, is performed.
Proceed to the following process.

(2) Step S2 If the lower limit number of times DTL is larger than the set value 70, that is, the duty ratio DU
If the state in which T is 95% or less continues for 71 rotations or more, the motor torque has sufficient margin to maintain steady rotation, so the electrical angle determining means 16 reduces the electrical angle DEL by one degree and Reset the counter of the lower limit number of times DTL to 0. Since the electrical angle DEL is initially set to 20 degrees, it is updated to 19 degrees. Thereby, it is possible to provide a margin for the torque of the motor and to improve motor efficiency.

(3) Step S3 If the electrical angle DEL becomes smaller than 0 degrees, the amount of current will increase, so the electrical angle determining means 16 determines whether the electrical angle DEL is less than 0 degrees. judge. If it is less than 0 degrees, the process moves to step S5 and subsequent steps, which will be described later.

(4) Step S4 If the electrical angle DEL is smaller than 0 degrees, reducing the electrical angle DEL will conversely increase the amount of current and reduce the motor efficiency. to 0 degrees. As a result, the electrical angle D has sufficient torque and has the highest motor efficiency.
Steady rotation is performed in a state where EL is 0 degrees.

(5) Step S5 In step S1, if the duty ratio DUT is 95% or less at 70 revolutions or less, or if the duty ratio DUT is 95% or more at 71 revolutions or more and the electrical angle DEL is reduced. Since it is conceivable that the motor torque may not have enough margin, the electrical angle determining means 16 determines whether the value of the upper limit number of times DTG is larger than the set value 70 or not. If the value of the upper limit number of times DTG is less than or equal to the set value 70, there is sufficient torque of the motor, so the process moves to step S8 and subsequent steps, which will be described later.

(6) Step S6 DTG is set to 70
If larger, i.e. the duty ratio DUT is 98
% or more continues for 71 rotations or more, it is considered that the motor torque does not have enough margin to maintain steady rotation, so the electrical angle determining means 16 increases the electrical angle DEL by one degree and increases the electrical angle DEL to an upper limit (not shown). Reset the number DTG counter to 0. As a result, the amount of motor drive current increases, and the torque of the motor can be increased.

(7) Step S7 If the electrical angle DEL becomes too large, the motor will function as a generator, so the electrical angle determining means 16 monitors the electrical angle DEL so that it does not become too large. In this embodiment, it is determined whether the electrical angle DEL has become 20 or more, with a margin in mind. If the temperature is 20 degrees or less, step S9 will be described later.
Proceed to the following process.

(8) Step S8 Electrical angle DEL is 20
In order to prevent the motor from functioning as a generator if the electrical angle is greater than
Set the electrical angle DEL to 20 degrees.

(9) Step S9 Even if the state in which the duty ratio DUT is 98% or more in step S5 is 70 revolutions or less, or the state in which the duty ratio DUT is 98% or more is 71 revolutions or more, the electrical angle DEL is 20 revolutions or less. If the duty ratio DUT is less than 95%, the motor torque may have a margin to maintain steady rotation, so the electrical angle determining means 16 determines whether the duty ratio DUT is 95% or less. If the duty ratio DUT is larger than the lower limit set value of 95%, in order to determine whether there is a margin of torque in the motor,
The process moves to step S11 and subsequent steps, which will be described later.

(10) Step S10 If the duty ratio DUT is 95% or less in step S9, the electrical angle determining means 16 uses a counter (not shown) that counts the number of times the duty ratio DUT is 95% or less. ) is counted up by 1.

(11) Step S11 Electrical angle determining means 1
6 is to determine whether there is a margin of torque in the motor.
Furthermore, it is determined whether the duty ratio DUT is 98% or more. If the duty ratio DUT is smaller than the upper limit setting value of 98%, the process for the current rotation is ended.

(12) Step S12 If the duty ratio DUT is 98% or more in step S11, the electrical angle determining means 16 uses a counter (not shown) that counts the number of times the duty ratio DUT is 98% or more. ) is counted up by 1. As above,
The process of determining the electrical angle DEL in the electrical angle determining means 16 ends.

The control processor 18 uses the electrical angle determined by the electrical angle determining means 16 with respect to the rotational position of the motor detected by the position detecting means, and based on the motor drive current of the duty ratio DUT determined by the current amount determining means. , generates a drive pattern to be supplied to the next drive coil and sets it in the output register 181.

FIG. 4 is an explanatory diagram of the motor drive current and the induced voltage of each drive coil at each electrical angle in a steady rotation state. Figure (B) shows the case where the electrical angle DEL is 15 degrees.

In FIG. 4, H1 to H6 indicate the operating states during one rotation of the motor divided into six sections, each section having a rotation angle of 60 degrees. V1,
V2 and V3 indicate the terminal voltages of the drive coils 121, 122 and 123, which are equal to the induced voltage of each drive coil. Comparing FIGS. 4A and 4B, it can be seen that by delaying the electrical angle DEL, the amount of current (the shaded area) increases and the motor torque increases even with the same duty ratio DUT.

FIG. 5 is a timing chart of the position detection signal and motor drive current at an electrical angle of 0 degrees, and FIG. 6 is a timing chart of the position detection signal and motor drive current at an electrical angle of 30 degrees. is 20 degrees or less, but for the sake of clarity, a case of 30 degrees is shown, but the electrical angle control and motor current energization control operations are the same).

In FIGS. 5 and 6, states H1 to H6
has the same meaning as in FIG. AH, BH and CH are
The motor drive currents that are the currents supplied to the corresponding drive coils 121, 122, and 123 are shown, and AL, BL, and CL indicate the motor drive currents that are the return currents from the corresponding drive coils 121, 122, and 123.

P1 to P6 are each state H1 to H6
The driving pattern shown in FIG. For example, the drive pattern P1 when the electrical angle DEL=0 degree shown in FIG. 5 is AH=
BL=1 (predetermined duty section), BL=1 (all sections), and other motor drive current levels are 0.

In order to simplify the explanation, the operating state of H1 will be explained below. Furthermore, since the motor drive control operation is the same whether the electrical angle DEL is 0 degrees or not, the control operation when the electrical angle DEL is 0 degrees will be described below.

Drive pattern P1 is input to output register 181.
When P1 is written, the level conversion circuit 170 of the motor drive current supply means 17 converts the level of this drive pattern P1 and applies it to the corresponding switching element.

When the motor drive current supply means 17 receives this drive pattern P1, it switches the power supply voltage Vcc with the switching element 171 and supplies the motor drive current AH to the corresponding drive coil 121.
The switching element 176 switches the power supply voltage Vcc so that the motor drive current CL returned from the corresponding drive coil 123 flows. As a result, the motor rotates in the direction of the arrow and enters state H2.

The motor rotation control operation using this drive pattern is the same as the motor rotation control operation using the drive pattern in the conventional motor constant speed rotation control method described with reference to FIGS. 7 and 8. Therefore, the motor rotation control operation based on the drive pattern will be briefly explained. State H2
, the position detector means 131 to 133 generate respective position detection signals, and the input register 141 in the motor rotation time information measuring means 14 of the logic circuit 19
Set to .

Control processor 18 controls input register 14
1 and detects that the position detection signal has been newly set, the drive pattern of the output register 181 is changed to the drive pattern P2 (BL=CH
= 1, others 0. To simplify the explanation, the duty ratio of each motor drive current is not mentioned. The same applies below)
Update to.

When the motor drive current supply means 17 receives this drive pattern P2 via the level conversion circuit 170, it switches the power supply voltage Vcc with the switching element 171 and supplies the motor drive current CH to the corresponding drive coil 123. At the same time, the switching element 174
The power supply voltage Vcc is switched so that the return motor drive current BL from the corresponding drive coil 122 flows. As a result, the motor rotates in the direction of the arrow and enters the operating state of state H3.

Thereafter, motor drive control in states H3 to H6 is performed in the same manner, and constant speed rotation control for one rotation of the motor is completed. When the constant speed rotation control for this one rotation is completed, the constant speed rotation control of the motor for the second rotation is repeated in the same manner as for the first rotation described above.

Above, the lower limit number of times DT for duty ratio 95%
An embodiment of the present invention has been described by taking as an example a case where the upper limit number of times DTG with L and duty ratio of 98% or more are both selected to be 70. However, the present invention is not limited to this embodiment, and the invention is not limited to this embodiment. Various modifications are possible according to the main idea.

For example, the motor can be driven with multiple phases other than three phases. In addition, in the embodiment, the duty ratio DUT
In the range of 95 to 98%, electrical angle control is not performed and a dead zone is provided, but such a dead zone is not an essential requirement in the present invention, so it may be omitted.

[0087]

Effects of the Invention As explained above, the present invention allows the motor driving current of the amount of current determined by the current amount determining means to be applied to the rotational position of the motor detected by the position detecting means. Since the power is supplied to the corresponding drive coil at each corner, it is possible to maintain constant speed rotation even in situations where the motor torque decreases or conversely requires a large torque, and the motor efficiency is also improved. Can be maintained in good condition.

[0088] Also, the electrical angle is determined based on the lower limit number of times that the duty ratio of the motor drive current is continuously less than or equal to the specified lower limit value and the upper limit number of times that the duty ratio is consecutively less than or equal to the specified upper limit value. By controlling , stable constant speed rotation control can be performed.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the principle of the present invention, (A) is an explanatory diagram of the principle configuration of the present invention, (B) is an operation waveform diagram when electrical angle control is not performed, and (C) is an illustration of the operating waveform when electrical angle control is performed. FIG. 3 is an operation waveform diagram when

FIG. 2 is an explanatory diagram of a motor constant speed rotation control system according to an embodiment of the present invention.

FIG. 3 is an operation flowchart during electrical angle control according to an embodiment of the present invention.

FIG. 4 is an operational waveform diagram of an embodiment of the present invention, (A)
(B) is an operating waveform diagram when electrical angle control is not performed, and (B) is an operating waveform diagram when electrical angle control is performed.

FIG. 5 is an operation timing chart when electrical angle control is not performed in one embodiment of the present invention.

FIG. 6 is an operation timing chart when electrical angle control is performed in an embodiment of the present invention.

FIG. 7 is an explanatory diagram of a conventional constant speed rotation control method for a motor.

FIG. 8 is an operation waveform diagram of a conventional motor constant speed rotation control method.

[Explanation of symbols]

10 Motor 11 Rotor magnet 121
~123 Drive coil 131 ~133 Position detection means

Claims (3)

[Claims] 1. In a constant speed rotation control method for a motor rotationally driven by a motor drive current supplied to drive coils (121 to 123), a position detection means ( 131 ~
133), rotation time information measuring means (14) for measuring motor rotation time information related to the rotation time of the motor based on the position detection signals generated by the position detection means (131 to 133), and rotation time information measuring means Based on the measured rotation time information of the motor in (14) and the information related to the target rotation time of the motor, the drive coils (121 to 123
); and an electrical angle determination unit that determines the electrical angle of the motor drive current based on the current amount determined by the current amount determination unit (15). means (16); and position detection means (131).
- 133 ) with the electrical angle determined by the electrical angle determining means (16), the current amount determining means (
15) A constant speed rotation control system for a motor, comprising: motor drive current supply means (17) for supplying the motor drive current of the determined current amount to the corresponding drive coils (121 to 123). 2. The constant speed rotation control method for a motor according to claim 1, wherein the current amount determining means (15) determines the current amount by an amount related to the current energization time. 3. The electrical angle determining means (16) determines the lower limit number of times the duty ratio of the motor drive current is continuously equal to or less than a prescribed lower limit value and the number of times the duty ratio is consecutively equal to or less than a prescribed upper limit value. 3. The constant speed rotation control method for a motor according to claim 1, wherein the electrical angle is controlled based on an upper limit number of times.