JP2704424B2 - Speed control method of DC brushless motor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a speed control method for a DC brushless motor used for driving a rotary polygon mirror or the like.

(Prior art) Conventionally, as shown in FIG. 5, the speed control of this type of DC brushless motor is performed in the case of a three-phase four-pole DC brushless motor.
The detection outputs of the rotation position detectors H _U , H _V, and H _W of the rotor shaft are input to the coil energization logic circuit 1. The coil energizing logic circuit 1 is a known motor control integrated circuit (for example, TA7712P manufactured by Toshiba), and when the outputs of the rotational position detectors H _U , H _V , H _W are output with a phase difference of 120 degrees, A 120-degree pulse is output in synchronization with the rise of each of the outputs of the position detectors H _U , H _V , and H _W , and a 120-degree pulse is output as the output of the position detectors H _U , H _V , and H _W. It is output in synchronization with each fall. This state is as shown in FIG. In FIG. 6, the outputs of the rotational position detectors H _U , H _V , H _W are represented by H _U , H _V , H _W.
In show, shows the former pulse of 120 ° width U _L, V _L, with W _L, 1
The latter of the 20-degree pulse is denoted by U _U , V _U , and W _U.

A transistor Q ₁₀ for inverting an input signal at each of outputs U _U , V _U and W _U from the coil energization logic circuit 1;
Q _20, drives the Q _30, transistors Q _10, Q _20, Q ₃₀ through transistors Q _1, Q _2, Q ₃ and configured to drive each of the transistors Q _1, Q _2, respectively Q ₃ transistor Q
_11, Q _21, Q ₃₁ is Yes and complementary connection, the coil energization logic circuit 1 is the output U _L, V _L, respectively W _L drives the transistor _{Q 11, Q 21, Q 31} .

The emitters of transistors Q ₁₁ , Q ₂₁ and Q ₃₁ are grounded, and the star-connected stator windings L _U , L _V , L _W of a DC brushless motor between the commonly connected collectors of transistors Q ₁ , Q ₂ , Q ₃ Are connected at one end. Transistor Q ₁ ,
The emitter of Q _2, Q ₃ is commonly connected, emitter connected in common is connected via the transistor Q ₅₀ to a power source + V.

The determination output from the speed determiner 2 that determines whether the rotation angular speed of the rotor shaft is equal to or greater than the set angular speed is determined by the transistor Q _40.
To drive the, to drive the transistor Q _50. Therefore,
6 As is apparent from the figure, for example, the output period in transistor Q output V _U of the coil energization logic circuit 1 is a logic "1"
₂₀ and the transistor Q ₂ are turned on, and the transistor Q ₂ is turned on during the output period when the output _VL of the coil conduction logic circuit 1 is logic “1”.
₂₁ is controlled to the ON state, the output V _U and the output U _L is energized to the series circuit of the period in the stator windings L _V and L _U of logic "1" together. The same applies to other cases, and then the stator winding L _W
And L _U , and then the series circuit of stator windings L _W and L _V. Similarly, the energization period is 60 degrees in electrical angle.

However when the rotational angular velocity of the rotor shaft at a speed discriminator 2 is determined to less than the set angular velocity from the velocity discriminator 2 is outputted the output of the logic "1", the transistors Q ₄₀ and Q ₅₀ is controlled to be turned on The power supply voltage + V is the transistor Q ₁
It is applied to the emitter of the to Q _3, brushless motor 2 phase stator windings every 60 electrical degrees as described above is energized is driven. Also when the rotational angular velocity of the rotor shaft is determined to more than the set angular velocity, from the speed discriminator 2 is outputted the output of the logic "0", the transistors Q ₄₀ and Q ₅₀ is controlled to the OFF state, the power supply voltage + V transistor Q _1, Q _2, Q ₃ of
To the emitter is cut off. As a result, the drive of the brushless motor is stopped.

(Problems to be Solved by the Invention) However, as described above, when the brushless motor is driven simply according to the output of the speed determiner 2, the generated torque is accelerated much more strongly than the load torque. When the motor is stopped, the generated torque disappears, and the speed is rapidly reduced due to the emergency torque. As a result, the rotational angular velocity of the rotor shaft of the brushless motor as shown in one-dot chain line a in FIG. 4, the amplitude of hunting for setting the angular velocity omega ₀ is large, the variation width of the angular velocity of the rotor shaft was that problem is large .

SUMMARY OF THE INVENTION An object of the present invention is to provide a speed control method of a DC brushless motor that can reduce the hunting amplitude.

(Means for Solving the Problems) A speed control method according to the present invention includes a discriminator for discriminating a slow speed between a set angular speed and a rotor shaft rotation angular speed, and driving of a stator winding in accordance with a rotor shaft rotation position detection signal. And a coil energizing logic circuit for outputting a signal. The speed control method of the DC brushless motor in a case where one or more drive signal periods are output from the discriminating cycle coil energizing logic circuit of the discriminator. A first timer that is triggered and timed to produce an average generated torque less than the load torque due to driving during the set period, and a second timer that is timed to generate an average generated torque that is greater than the load torque. A timer is provided, and the first or second timer is selected according to the discrimination output of the discriminator, and the drive signal is used only during the set time of the selected timer. It is characterized in that a brushless motor is driven.

(Operation) In the speed control method as described above, the first timer or the second timer is selected by the discrimination output of the discriminator, and the drive output from the coil energizing logic circuit only during the set time of the selected timer. The stator winding is energized by the signal. Therefore, when the discriminator determines that the set angular velocity is lower than the rotor shaft rotation angular velocity, the second timer is set to:
By selecting the first timer when it is determined to be early, the acceleration is accelerated by the average generated torque larger than the load torque in the former case, and the acceleration is decelerated by the average generated torque smaller than the load torque in the latter case. Will be controlled.

(Examples) Hereinafter, the present invention will be described with reference to examples.

FIG. 1 is a block diagram showing the configuration of the first embodiment of the present invention.

In FIG. 1, the same components as those of the conventional example shown in FIG. 5 are denoted by the same reference numerals, and description thereof will be omitted.

The power supply voltage + V is directly applied to the commonly connected emitters of the transistors Q ₁ , Q ₂ and Q ₃ .

The outputs U _U , V _U , W _U , _UL , _VL , and W _L of the coil energization logic circuit 1 are sent to the rising timing detector 3 and the outputs U _U ,
V _U, W _U, detects the rise of the U _L, V _L, and W _L. The timers 4 and 5 are triggered by the rise detection output of the rise timing detector 3. Timer 4 The set time T _1, the timer 5 is set respectively to the set time _{T 2 (T 2> T 1} ). As set time T ₁ and T ₂ which is between the mean value B and C of the load torque is the torque generated from the relationship between the average value and the timer set time T _1, T ₂ of the torque as shown in Figure 2 Set time
T ₁ and T ₂ are set.

The outputs of the timers 4 and 5 are sent out as one inputs of the AND gate circuits 6 and 7, respectively.

The output from the speed discriminator 2 is sent out as the other input of the AND gate 7, and the output from the speed discriminator 2 is sent out via the inverter 8 as the other input of the AND gate 6.

The start signal from the start timer 9 for outputting a start signal for driving the DC brushless motor for a predetermined period at the start, the output from the AND gate 6, and the output from the AND gate 7 are input to the OR gate 10. The output from the OR gate 10 is sent to the AND gates 11 to 16 as one input, and the output of the OR gate 10 controls the gates of the AND gates 11 to 16 to be open.

Output U _U is sent to the AND gate 11, to drive the transistors Q ₁₀ at the output of the AND gate 11. The output V _U is sent to the AND gate 12, the transistors in the output of the AND gate 12
Drives the Q _20, the output V _U is sent to the AND gate 13 drives the transistor Q ₃₀ at the output of the AND gate 13.

The output U _L is sent to the AND gate 14 drives the transistor Q ₁₁ at the output of the AND gate 14, the output V _L is sent to the AND gate 15, the transistor Q at the output of the AND gate 15
Drives _21, the output W _L is sent to the AND gate 16 drives the transistor Q ₃₁ at the output of the AND gate 16.

Transistor output directly from coil energization logic circuit 1
When driving Q _{10 to} Q ₃₀ and Q _{11 to} Q ₃₁ , the stator windings L _U , L _V ,
The driving voltage waveforms applied to the terminals of L _W Figure 3 (a) ~
As shown in (c), rectangular wave driving is performed. The rise detected by the rise timing detector 3 is a period T ₀ (120 electrical degrees) divided into “3” by two poles in FIG.
Output every time. Since the timers 4 and 5 are triggered by this output, the set periods of the timers 4 and 5 are as shown in FIGS. 3 (d) and 3 (e).

Here, the speed discriminator 2 generates an output of logic "1" when the rotor rotation angular speed is lower than the set angular speed, and generates an output of logic "0" when the rotor rotation angular speed is higher than the set angular speed. Therefore, in the former case, the output of the timer 5 is output via the AND gate 7, and in the latter case, the output of the timer 4 is output via the AND gate 6. As a result, if the output from the speed discriminator 2 is as shown in FIG. 4 (a), the output from the OR gate 10 will be as shown in FIG. 4 (b). Therefore, the AND gate 11 to 16 when the rotor rotational angular velocity is slower than the set angular velocity during the setting period T ₂ of the timer 5 in the period T _0, the gate is opened, the transistor _{Q 10, Q 20, Q 30} , Q ₁₁ , Q ₂₁ , Q ₃₁ output U _U ,
Driven by V _U , W _U , U _L , V _L , W _L. When the rotor rotational speed is faster than the set angular speed, AND gates 11 to 16
During the setting period T ₁ of the timer 4 during the period T _0, the gate is opened, the transistor _{Q 10, Q 20, Q 30} , Q 11, Q 21, Q 31
_Are driven by the outputs U _U , V _U , W _U , U _L , V _L , W _L. For this reason, the roller rotation angular velocity is controlled as shown by a solid line b in FIG. 4 (c). For this reason, when the rotor rotation angular velocity is lower than the set angular velocity, the motor is energized and accelerated for a set time of the timer 5 that generates a generated torque that exceeds the load torque on average. The motor 4 is energized and decelerated for the set time of the timer 4 that generates the generated torque that is lower than the average, and the hunting amplitude of the rotor rotational angular velocity becomes smaller than in the conventional case.

(Effect of the Invention) As described above, according to the present invention, the first and second timers are provided, the first or second timer is selected according to the discrimination output of the discriminator, and the setting of the selected timer is performed. Since the brushless motor is driven by the drive signal only during the time, the hunting amplitude can be reduced in controlling the roller shaft rotation angular velocity to the set angular velocity.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of the present invention. FIG. 2 is a diagram showing a relationship between a set time of a timer and an average value of generated torque. 3 and 4 are diagrams for explaining the operation of the embodiment of the present invention. FIG. 5 is a block diagram showing a configuration of a conventional example. FIG. 6 is a timing chart of the output signal of the coil energization logic circuit. 1 ... Coil energizing logic circuit, 2 ... Speed discriminator, 3 ...
Rise timing detectors, 4 and 5, timers, 6, 7,
11-16 …… and gate, 10… or gate, Q ₁ , Q ₂ ,
Q ₃ , Q ₁₀ , Q ₂₀ , Q ₃₀ , Q ₁₁ , Q ₂₁ and Q ₃₁ ... transistors.

Claims (1)

(57) [Claims] A discriminator for discriminating between a set angular velocity and a rotor shaft rotational angular velocity; and a coil energizing logic circuit for outputting a stator winding drive signal in accordance with a rotor shaft rotational position detection signal. A speed control method for a DC brushless motor in a case where a discrimination cycle of a discriminator is equal to or longer than one drive signal period output from a coil energizing logic circuit, wherein the speed is triggered by a rise of the drive signal and the drive is performed by a drive during a set period. A first timer whose time is set during a period in which an average generated torque smaller than the torque is generated, and a second timer set in a period in which an average generated torque larger than the load torque is generated; Accordingly, the first or second timer is selected, and the brushless motor is driven by the drive signal only during the set time of the selected timer. Rate control method of a DC brushless motor, wherein the door.