CN113193799B - Motor drive circuit, vibration device, and electronic apparatus - Google Patents

Abstract

A motor drive circuit, drive method, vibration device and electronic equipment for suppressing reverse rotation of a rotor caused by reverse braking. A control unit (110) generates a drive signal (S3) for controlling energization of a coil of a motor (2) based on a rectangular signal (S2) indicating a position of a rotor of a motor (2) to be driven. The drive unit (130) drives the coil based on the drive signal (S3). The control unit (110) monitors the cycle of the rectangular signal (S2) during reverse braking, and ends the reverse braking when the cycle is shortened.

Description

Motor drive circuit, vibration device and electronic equipment

This application is a divisional application of the following patent application: the application date is May 18, 2016, the application number is 201610329921.1, and the invention name is "motor drive circuit, vibration device and electronic equipment".

technical field

The invention relates to the driving technology of electric motors.

Background technique

In general, a driver for a brushless motor may be equipped with a brake function in order to stop the rotating rotor. There are regenerative braking and reverse braking for braking. In regenerative braking, the output stage of the driver and the motor coil form a loop, and current flows through the loop to dissipate the energy of the motor coil.

Reverse braking is used when it is desired to stop the rotor with a braking force stronger than regenerative braking. In reverse braking, the motor coil is driven so that the rotor generates torque in the opposite phase to the normal driving state (forward rotation state), in other words, in the opposite direction to the forward rotation direction.

[Prior art literature]

[Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. 2006-234208

[Patent Document 2] Japanese Unexamined Patent Publication No. 2009-018654

[Patent Document 3] Japanese Patent Application Laid-Open No. 8-191591

Contents of the invention

[Problem to be solved by the invention]

Problem 1. The inventors of the present invention have studied the following reverse braking control (referred to as research technology).

In the research technique, the period of the Hall signal is monitored during the reverse braking period. Then, if the period exceeds a predetermined threshold value, it is considered that the rotor has been sufficiently decelerated, and the reverse braking is terminated.

In the case of controlling the brushless motor synchronously with the Hall signal from the Hall element, the minimum time of reverse braking is restricted by the period of the Hall signal. Therefore, when the rotor torque in the forward rotation direction immediately before the reverse braking is small, the torque applied to the rotor by the reverse braking for a certain minimum time or longer may become larger, and the rotor may reversely rotate as a result.

Moreover, if the period of the Hall signal exceeds the threshold value immediately after the reverse rotation starts, there is a fear that the end condition of the reverse braking will not be met, and the reverse braking will not be released, causing the rotor to further accelerate in the reverse direction.

Problem 2. Furthermore, the inventors of the present invention recognized the following problems as a result of studies on counter-rotation braking. In the case of controlling the brushless motor synchronously with the Hall signal from the Hall element, the minimum time of reverse braking is restricted by the period of the Hall signal. Therefore, when the rotor torque in the forward rotation direction immediately before the reverse braking is small, the torque applied to the rotor by the reverse braking for a certain minimum time or longer may become larger, and as a result, the rotor may rotate in the reverse direction. In addition, this subject has not been understood as general knowledge of those skilled in the art.

An aspect of the present invention has been made in view of one of the above problems, and one of the exemplified purposes thereof is to provide a motor drive circuit capable of preventing or suppressing reverse rotation of a rotor caused by reverse braking.

〔Means used to solve the problem〕

1. A certain aspect of the present invention relates to a motor drive circuit. The motor drive circuit includes: a control unit that controls energization of a coil of the motor based on a rectangular signal indicating a position of a rotor of a motor to be driven; and a drive unit that drives the coil based on the drive signal. The control unit monitors the cycle of the rectangular signal during the reverse braking period, and ends the reverse braking when the cycle is shortened.

According to this aspect, it is possible to immediately detect the reverse rotation of the rotor based on the periodic relative change indicating the rotation speed of the rotor, thereby suppressing the reverse rotation of the rotor due to reverse braking.

The control unit may end reverse braking based on the magnitude relationship between the current cycle and the past cycle.

When the control unit denote the current cycle as T _CUR , the past cycle as T _PRE , and the correction value above 0 as TCORR, it may satisfy

T _CUR +T _CORR ≦T _PRE

, end reverse braking.

When the control unit denote the current cycle as T _CUR and the past cycle as T _PRE , it may satisfy T _CUR < T _PRE

end reverse braking.

The past cycle may also be the cycle of the previous measurement. The past cycles may also be based on a plurality of cycles measured in the last predetermined number of times.

During the reverse braking period, the control unit may end the reverse braking when the period of the rectangular signal becomes longer than a predetermined threshold value. The control unit may include an edge counter that counts the number of edges of the rectangular signal during the reverse braking period, and terminate the reverse braking when the count value of the edge counter exceeds a predetermined threshold. The control unit may include a timer circuit for measuring the length of the reverse braking period, and end the reverse braking when the reverse braking period reaches a predetermined time. A plurality of end conditions of reverse braking can be combined.

2. Another aspect of the present invention relates to a motor drive circuit. The motor drive circuit includes: a control unit that generates a drive signal for controlling energization to a coil of the motor based on a rectangular signal indicating a position of a rotor of a motor to be driven; a Hall comparator that generates a rectangular signal; and a control unit that The energization to the coil of the motor is controlled based on the rectangular signal, and the drive unit drives the coil based on the drive signal from the control unit. When the control unit receives an instruction to stop the motor in the normal driving state of the motor, it applies reverse rotation braking with an output corresponding to the normal driving state up to now.

In one aspect, the control unit can estimate how much torque the rotor of the electric motor has in the forward rotation direction by monitoring the normal driving state before the reverse braking is applied. Therefore, when it is estimated that the rotor has a sufficiently large torque in the forward rotation direction, reverse rotation braking is applied with a large output, and when the torque in the forward rotation direction is estimated to be small, the output of reverse rotation braking is reduced, or Setting the output to 0 means that reverse rotation braking is not applied, thereby preventing reverse rotation of the rotor.

In a certain aspect, the control unit may change the output of the reverse braking in accordance with the number of switching times of the rectangular signal that occurs in the normal driving state.

If the number of level transitions of the rectangular signal is small, it is estimated that the torque in the forward rotation direction of the rotor is small, and the output of reverse braking can be reduced.

In a certain aspect, the control unit may include an edge counter that counts the number of edges of the rectangular signal in a normal driving state, and may change the output of the reverse braking in accordance with the count value of the edge counter.

In a certain mode, when the control unit receives the instruction to stop the motor, when the number of edges of the rectangular signal measured so far is smaller than a predetermined threshold value, the output of the reverse braking reduce.

In a certain aspect, the control unit may not apply reverse rotation braking when the number of edges of the rectangular signal counted so far is smaller than a predetermined threshold value when receiving an instruction to stop the motor.

In a certain aspect, the control unit may change the output of the counter-rotation brake according to the length of the normal driving state.

If the normal driving state is short, it is presumed that the torque in the forward rotation direction of the rotor is small, and the output of reverse braking is reduced.

In a certain aspect, the control unit may include a timer circuit for measuring the length of the normal driving state, and may change the output of the reverse braking in accordance with the measured time of the timer circuit.

In a certain aspect, when the control unit receives an instruction to stop the electric motor, the output of the counter-rotation brake may be lowered when the measured time is shorter than a predetermined threshold value than when it is longer.

In a certain aspect, when the control unit receives an instruction to stop the electric motor, the reverse rotation braking may not be applied when the measured time is shorter than a predetermined threshold value.

The control unit may end the reverse braking when the period of the rectangular signal becomes longer than a predetermined threshold during the reverse braking. The control unit may include an edge counter that counts the number of edges of the rectangular signal during the reverse braking period, and when the count value of the edge counter exceeds a predetermined threshold value, the reverse braking may be terminated. The control unit may include a timer circuit for measuring the length of the reverse braking period, and end the reverse braking when the reverse braking period reaches a predetermined time. A plurality of end conditions of reverse braking can be combined.

In a certain aspect, the motor drive circuit may be integrally integrated on one semiconductor substrate.

The so-called "integration" includes the case where all the constituent elements of the circuit are formed on the semiconductor substrate, and the case where the main constituent elements of the circuit are integrally integrated, and a part of the resistors and resistors may be provided outside the semiconductor substrate for the purpose of adjusting the circuit constant. capacitance etc.

By integrating the circuits on one chip, the circuit area can be reduced and the characteristics of the circuit elements can be kept uniform.

Another aspect of the present invention relates to a vibration device. The vibrating device may also include a vibrating motor having an eccentric weight attached to a rotor, and a motor drive circuit for rotating the vibrating motor.

Another aspect of the present invention relates to electronic equipment. Electronic equipment may also include the above vibration device.

In addition, any combination of the above constituent elements and the constituent elements or expressions of the present invention, such as methods, apparatuses, systems, etc., are replaced with each other, which is also effective as an embodiment of the present invention.

[Effect of the invention]

According to an aspect of the present invention, it is possible to suppress and prevent reverse rotation of the rotor caused by reverse rotation braking.

Description of drawings

FIG. 1 is a block diagram of a motor drive circuit according to a first embodiment.

FIG. 2 is a block diagram showing a specific configuration example of a motor drive circuit.

3(a) and 3(b) are operation waveform diagrams of the motor drive circuit of FIG. 1 .

Fig. 4 is a block diagram showing a configuration example of a reverse braking control unit.

Fig. 5 is a block diagram of a reverse braking control unit according to a second modification.

Fig. 6 is a block diagram of a motor drive circuit according to the first example of the second embodiment.

7(a) and 7(b) are operation waveform diagrams of the motor drive circuit of FIG. 6 .

Fig. 8 is a block diagram of a motor drive circuit of the second embodiment.

9( a ) and FIG. 9( b ) are operation waveform diagrams of the motor drive circuit of FIG. 8 .

FIG. 10( a ) is a perspective view of an electronic device including a motor drive circuit, and FIG. 10( b ) is a cross-sectional view of a vibration motor unit.

11 is a perspective view of an electronic device including a motor drive circuit.

Detailed ways

Hereinafter, based on embodiment, this invention is demonstrated with reference to drawings. The same or equivalent components, members, and processes shown in the drawings are assigned the same symbols, and overlapping descriptions are appropriately omitted. In addition, the embodiment is not to limit the invention but to illustrate, and all the features described in the embodiment or a combination thereof are not necessarily essential features of the invention.

In this specification, the so-called "the state in which component A is connected to component B" includes, in addition to the case where component A and component B are physically directly connected, it also includes components A and component B via electrical connections that do not substantially affect their electrical connection state. , or other components that do not impair the functions and effects of their coupling and are indirectly connected.

Similarly, the so-called "a state in which a component C is placed between a component A and a component B" includes, in addition to the case where the component A and the component C, or the component B and the component C are directly connected, also includes a The influence of other components, or the situation that they are indirectly connected without impairing the functions and effects of their coupling.

(first embodiment)

FIG. 1 is a block diagram of a motor drive circuit 100 according to the first embodiment. The motor drive circuit 100 drives a single-phase brushless motor (hereinafter, simply referred to as a motor) 2 . The Hall element 4 generates a pair of Hall signals H+, H− corresponding to the position of the rotor of the motor 2 . The Hall signals H+, H- are opposite to each other.

A control command S1 for instructing rotation/stop of the motor 2 is input to the motor drive circuit 100 from a main processor not shown. When the Hall signals H+, H− are input to the motor drive circuit 100 and the control command S1 instructs rotation, the coils of the motor 2 are energized in synchronization with the Hall signals H+, H−.

The motor drive circuit 100 includes a Hall comparator 102 , a control unit 110 , and a drive unit 130 , and is a functional IC (integrated circuit) integrated on one semiconductor substrate. The Hall comparator 102 compares the Hall signals H+ and H− from the Hall element 4 to generate a rectangular signal (also referred to as an FG signal) S2. The control unit 110 generates a drive signal S3 for controlling energization of the coils of the motor 2 based on the rectangular signal S2. The drive unit 130 drives the coil based on the drive signal S3 from the control unit 110 . The configuration of the driving unit 130 is not particularly limited, and a known circuit may be used.

Control unit 110 receives a control command S1 for instructing rotation/stop of motor 2 . The control unit 110 applies reverse rotation braking when receiving an instruction to stop the motor 2 in a normal driving state in which the motor 2 is rotated in a certain direction (presumably forward rotation direction). During the reverse braking period, the control unit 110 monitors the period of the Hall signals H+, H-, that is, the period T _P of the rectangular signal S2 (in this embodiment, it is set as a half period), and if the period T _P is shortened, it ends reverse braking.

The control unit 110 includes an energization control unit 112 and a reverse braking control unit 114 . The energization control unit 112 performs commutation control in synchronization with the rectangular signal S2. The reverse braking control unit 114 controls the termination of the reverse braking.

Specifically, the reverse braking control unit 114 measures the period T _P of the rectangular signal S2 during the period of reverse braking, and compares the current period T _CUR with the past period T _PRE , and if the current period T _CUR If the period T _PRE is shortened from the past, the reverse braking is ended. This is the first condition. The past period T _PRE may also be the immediately preceding period T _P . Alternatively, the past period T _PRE may be a value calculated from a plurality of periods T _P measured in a plurality of past cycles. For example, the past period T _PRE may be an arithmetic average or a moving average of a plurality of past periods T _P .

In addition, the reverse braking control unit 114 ends the reverse braking when a predetermined time T _END elapses after starting the reverse braking. This is the second condition. If one of the first condition and the second condition is satisfied, the reverse braking control unit 114 ends the reverse braking.

The invention related to the first embodiment is grasped as a block diagram and a circuit diagram in FIG. 1 , or applies to various devices and circuits derived from the above description, and is not limited to a specific configuration. Hereinafter, more specific configuration examples will be described not to narrow the scope of the present invention, but to assist in understanding and clarifying the essence of the invention and circuit operation.

FIG. 2 is a block diagram showing a specific configuration example of the motor drive circuit 100 . The reverse braking control unit 114 includes a cycle measurement unit 118 and a determination unit 120 . Period measurement unit 118 measures the period of rectangular signal S2 (the respective lengths of the high-level interval and the low-level interval, that is, a half period), and outputs data (period data) S5 indicating the measured period to determination unit 120 .

The judging unit 120 compares the current cycle T _CUR shown by the cycle data S5 with the past cycle T _PRE held in the memory, and if the magnitude relationship between them satisfies a predetermined condition (first condition), the end signal S7 is set to is valid (for example, high level). In addition, the determination unit 120 asserts the end signal S7 when the predetermined time T _END has elapsed after the start of reverse braking. When the end signal S7 becomes active, the energization control unit 112 ends the reverse braking.

Next, the operation of the motor drive circuit 100 will be described. 3( a ) and ( b ) are operation waveform diagrams of the motor drive circuit 100 of FIG. 1 . First, the case where reverse braking is terminated based on the second condition will be described with reference to FIG. 3( a ). At time t0, the control command S1 becomes a high level for instructing rotation. Thereby, the control unit 110 starts energizing the motor 2 . As the rotation speed of the motor 2 increases, the period of the rectangular signal S2 gradually shortens.

At time t1, when the control command S1 becomes a low level for instructing to stop, the energization control unit 112 starts reverse braking. The rotor is decelerated by reverse braking, and the period of the rectangular signal S2 becomes longer gradually. Then, at time t2 after a predetermined time T _END has elapsed from time t1 , the end signal S7 is asserted, and the reverse braking ends.

Next, a case where reverse braking is terminated based on the first condition will be described with reference to FIG. 3( b ). At time t0, the control command S1 becomes a high level for instructing rotation. Thereby, the control unit 110 starts to energize the motor 2 . At time t3 immediately thereafter, before the rotation speed of the motor 2 increases, the control command S1 becomes low level to instruct the motor 2 to stop, and the energization control unit 112 starts reverse rotation braking.

The period measuring unit 118 measures periods T _P0 , T _P1 , T _P2 , T _P3 . . . of the rectangular signal S2 every cycle. In the i-th cycle, the current cycle T _CUR (=T _Pi ) is compared with the past cycle T _PRE (=T _Pi-1 ). Here, it is assumed that the past period T _PRE is the period T _P of the immediately preceding cycle.

During the period Ta immediately after the start of reverse braking, T _Pi > T _Pi-1 holds true. That is, the period of the rectangular signal S2 gradually becomes longer, and the rotor decelerates. If it is detected at time t4 that T _P3 >T _P2 and the first condition is satisfied, the end signal S7 is asserted, and the reverse braking ends.

The above is the operation of the motor drive circuit 100 . After a short period of normal driving, if the reverse rotation brake is continuously applied, the rotor will be accelerated in the reverse direction. In contrast, according to the motor drive circuit 100 of the first embodiment, the period T _P of the rectangular signal S2 is measured, and if it is detected that T _CUR < T _PRE , it is considered that the rotor reverses in the reverse direction, and the reverse braking can be stopped immediately. .

FIG. 4 is a block diagram showing a configuration example of the reverse braking control unit 114 . The determination unit 120 includes a first determination unit 120a and a second determination unit 120b that determine the first condition and the second condition, respectively. The second determination unit 120b includes a timer circuit 160, measures an elapsed time immediately after reverse braking is started, and asserts an end signal S7b after a predetermined time T _END has elapsed. The predetermined time TEND is set based on the value of the register 162 at a predetermined address. It is preferable that the predetermined time T _END can be set from an external host processor via an interface such as an I2C (Inter IC) bus.

The first determination unit 120 a includes a memory 150 , a comparator 152 , an adder 154 , and a register 156 . The memory 150 holds past periods T _PRE . As mentioned above, the past period T _PRE may be the immediately preceding period T _P , or may be an average value of a plurality of past periods T _P .

Depending on the installation position of the Hall element and the deviation of the magnetic field, even when the rotor rotates at a constant speed, the period T _P of the rectangular signal S2 may vary and may not be fixed. This means that reverse rotation of the rotor may be erroneously detected when the current period T _Pi is simply compared with the previous period T _Pi-1 . In order to prevent this erroneous detection, the first determination unit 120a corrects the period TCUR.

The adder 154 adds the correction value T _CORR to the current cycle T _CUR to generate a corrected cycle T _CUR ′. The correction value T _CORR is 0 or more (≧0), and is set according to the value of the register 156 at a predetermined address. It is preferable that the predetermined value T _CORR can be set from an external host processor via an interface such as an I2C (Inter IC) bus. The optimum value of the correction value T _CORR may be determined according to the type and number of poles of the motor 2 , the load connected to the rotor, the moment of inertia, and the like.

The comparator 152 compares the corrected current period T _CUR ' with the past period T _PRE , and when

T _CUR '≦T _PRE

, in other words, when the

T _CUR +T _CORR ≦T _PRE

, the end signal S7a is set to be valid.

When at least one of the end signals S7a, S7b is asserted, the end signal S7 is asserted. For example, the logic gate 164 may also be constituted by an "OR gate".

According to this reverse rotation braking control unit 114, the sensitivity of detecting the reverse rotation of the rotor can be adjusted according to the correction value T _CORR . By enabling the correction value T _CORR to be set externally using the register 156 , optimal control can be achieved on a platform using the motor drive circuit 100 .

A certain aspect of the present invention has been described above based on the first embodiment. The first embodiment is an example, and it will be understood by those skilled in the art that various modifications can be made to the combination of these respective components and processes, and these modifications are also within the scope of the present invention. Hereinafter, such a modified example will be described.

(1st modified example)

In FIG. 4 , the current period T _CUR is corrected, but it is also possible to correct the past period T _PRE in reverse. In this case, the correction value T _CORR may be subtracted from the value read from the memory 150 to generate a corrected period T _PRE ′, and T _PRE may be compared with T _CUR .

(Second modified example)

In the first embodiment, the reverse braking is ended when the predetermined time T _END elapses after the start of the reverse braking, but the present invention is not limited thereto. FIG. 5 is a block diagram of a reverse braking control unit 114a according to a second modification. In the second modified example, the second condition may be that the number of switching times (the number of edges) of the rectangular signal S2 that occurs during the reverse braking period exceeds a threshold value.

The second determination unit 120 b includes an edge counter 170 , a comparator 172 , and a register 174 . The edge counter 170 counts the number of edges of the rectangular signal S2 after reverse braking starts. The comparator 172 compares the count value S4 of the edge counter 170 with a predetermined threshold D, and if S4>D, asserts the end signal S7b. The threshold D is set based on the value of the register 174 at a predetermined address. It is preferable that the threshold D can be set from an external host processor via an interface such as an I2C (Inter IC) bus.

(3rd modified example)

In the first embodiment, reverse braking is terminated when either the first condition or the second condition is satisfied, but the second condition may be omitted. In this case, the timer circuit 160 and the logic gate 164 of FIG. 4 may also be omitted.

(4th modified example)

In the first embodiment, reverse braking is completed based on the magnitude relationship between the current cycle _TCUR and the past cycle T _PRE , but the present invention is not limited thereto. For example, it is also possible to focus on a plurality of consecutive (for example, three or more) cycles, and end reverse braking when the cycles tend to be shortened.

(fifth modified example)

The Hall comparator 102 may also be incorporated in a Hall IC including the Hall element 4 . Alternatively, the Hall element 4 may be built in the motor drive circuit 100 .

(Sixth modified example)

In the first embodiment, the motor drive circuit 100 that performs commutation control and anti-reverse control using the Hall signal from the Hall element is described, but it may be used instead of the Hall signal from the Hall element. Other signals that contain rotational speed information.

(second embodiment)

A second embodiment will be described with reference to FIG. 1 . Since the basic configuration is the same as that of the first embodiment, the description of the same points will be omitted, and the differences will be described.

A control command S1 for instructing rotation/stop of the motor 2 is input to the control unit 110 . When the control unit 110 receives an instruction to stop the motor 2 in a normal drive state in which the motor 2 is rotated in a certain direction (assumed to be a forward rotation direction), it applies reverse rotation braking with an output corresponding to the normal drive state so far.

The control unit 110 includes an energization control unit 112 and a reverse braking control unit 114 . The energization control unit 112 performs commutation control in synchronization with the rectangular signal S2. The reverse braking control unit 114 controls the output of the reverse braking. Specifically, the reverse braking control unit 114 changes the output of the reverse braking based on the normal driving state before the reverse braking is applied. When the motor drive circuit 100 performs PWM control, the reverse brake control unit 114 changes the duty ratio of the drive voltage Vo+/Vo- applied to the motor 2 to change the output of the reverse brake.

The above is the configuration of the motor drive circuit 100 in the second embodiment. Next, its operation will be described.

While the control command S1 instructs the rotor to rotate, the energization control unit 112 performs commutation control based on the rectangular signal S2, and supplies the motor 2 with a drive voltage Vo+/Vo- having a duty ratio corresponding to the target rotation speed. The duty cycle in a normal driving state may be a fixed value, or may be 100%.

The reverse braking control unit 114 monitors the normal driving state. The reverse braking control unit 114 can estimate how much torque the rotor of the electric motor 2 has in the forward rotation direction based on the monitoring result. Therefore, when it is estimated that the rotor has a sufficiently large torque in the forward rotation direction, reverse rotation braking is applied with a large output (rated output), and when the torque in the forward rotation direction is estimated to be small, reverse rotation braking is applied. Lower than the rated output, or set the output to zero, that is, no reverse braking is applied.

Accordingly, the reverse torque applied to the rotor by the reverse braking can be prevented from exceeding the forward torque applied in the normal driving state, and the rotor can be prevented from rotating reversely.

The invention related to the second embodiment is grasped as the block diagram and circuit diagram of FIG. 1 , or relates to various devices and circuits derived from the above description, and is not limited to a specific configuration. Hereinafter, more specific configuration examples will be described in order not to narrow the scope of the present invention, but to help understand the essence of the invention and circuit operations, and to clarify them.

FIG. 6 is a block diagram of a motor drive circuit 100a according to the first example of the second embodiment.

The counter-rotation braking control unit 114a of the motor drive circuit 100a changes the output of the counter-rotation braking in accordance with the switching frequency of the rectangular signal S2 generated in the normal driving state. The reverse braking control unit 114 a includes an edge counter 116 , a cycle measurement unit 118 , and a drive unit 130 . The edge counter 116 counts the number of edges of the rectangular signal S2 in the normal driving state. The determination unit 120 changes the output of the reverse braking in accordance with the count value S4 of the edge counter 116 .

For example, when the control unit 110 (determining unit 120) (i) the stop of the motor is instructed by the control command S1, if the count value S4 indicating the number of edges of the rectangular signal S2 counted so far is greater than the predetermined threshold value A, Apply reverse rotation braking with rated output. For example, the rated output may be a duty ratio in the range of 70 to 100%.

For example, the threshold value A may be determined such that the rotor becomes one revolution (360° mechanical angle) or less. For example, in a three-pole brushless motor, the edge of the rectangular signal S2 occurs six times in one rotor revolution, and three times in a half revolution. Therefore, it is good also as A=3-6 about. In a 2-pole brushless motor, the edge of the rectangular signal S2 occurs twice in one rotation of the rotor, and once in a half rotation, so A=1-2 may be used.

The threshold value A may be determined according to the type of the motor 2 , the number of poles, the load connected to the rotor, the moment of inertia, and the like, and may be about 1 to 20.

Conversely, when (ii) the number of edges of the rectangular signal S2 counted so far is smaller than a predetermined threshold A, the control unit 110 (determining unit 120 ) reduces the output of the reverse braking from the rated output. In the present embodiment, the control unit 110 does not apply reverse braking when the number of measured edges of the rectangular signal is smaller than a predetermined threshold value A. FIG. That is, the output of reverse braking is set to duty=0%.

The period measurement unit 118 measures the period of the rectangular signal S2 (the respective lengths of the high-level interval and the low-level interval, that is, a half period) during the period of applying reverse braking, and sends data (period data) representing the measured period to S5 is output to the determination unit 120 . If the cycle indicated by the cycle data S5 is longer than the predetermined threshold B, the determination unit 120 ends the reverse braking.

It is preferable that the threshold value A can be set based on setting data stored in a register at a certain address. Similarly, it is also preferable that the threshold value B can be set based on setting data stored in a register at a certain address. These thresholds A and B have different optimal values depending on the type, specification, and application of the motor 2, so the designer of the device equipped with the motor drive circuit 100 can select the thresholds A and B to realize the optimum value for various platforms. good control.

The above is the configuration of the motor drive circuit 100a. Next, its operation will be described.

7( a ), ( b ) are operation waveform diagrams of the motor drive circuit 100 a of FIG. 6 . The vertical and horizontal axes of the waveform diagrams and timing diagrams in this specification are appropriately enlarged or reduced for easy understanding, and each shown waveform is simplified, exaggerated, or emphasized for easy understanding.

Refer to Figure 7(a). At time t0, the control command S1 becomes a high level for instructing rotation. Thereby, the control unit 110 starts energizing the motor 2 . As the rotation speed of the motor 2 increases, the period of the rectangular signal S2 gradually shortens. The count value S4 increases as the motor 2 rotates, and reaches the upper limit value N of the edge counter 116 at time t1.

At time t2, the control command S1 becomes a low level for instructing to stop. At time t2, since N>A, reverse rotation braking is applied at the rated output. Through reverse braking, the rotor decelerates, and the period of the rectangular signal S2 gradually becomes longer. At time t3, when the period T _P of the rectangular signal S2 exceeds the threshold value B, the reverse braking period ends.

Refer to Figure 7(b). At time t0, the control command S1 becomes a high level for instructing rotation. Thereby, the control unit 110 starts energizing the motor 2 . At time t1 immediately after, before the rotation speed of the electric motor 2 increases, the control command S1 becomes low level, and instructs the stop of the electric motor 2 .

At time t1, the edge count value S4 is 2, which is smaller than the threshold value A (for example, 3). Therefore, without reverse rotation braking, the rotor is stopped by regenerative braking, or the rotor is stopped naturally.

The above is the operation of the motor drive circuit 100a. In FIG. 7( b ), the torque in the forward rotation direction of the motor at time t1 is very small. Therefore, when the control command S1 is at a low level, if reverse braking is applied, the rotor starts to rotate in the reverse direction. Also, if the period T _P of the rectangular signal S2 is shorter than the threshold value B immediately after the start of the reverse rotation, there is a possibility that the rotor will not be released from reverse braking, and the rotor may be further accelerated in the reverse direction.

In contrast, according to the motor drive circuit 100a of FIG. 6 , when the number of edges of the rectangular signal S2 measured in the normal driving state is smaller than the threshold value A, it is estimated that the torque in the forward rotation direction is sufficiently small, and reverse braking is not applied. It can prevent the reverse rotation of the rotor.

In addition, the first embodiment has the following advantages over the second embodiment described below. In the second embodiment, based on the length of the normal driving state, the rotation state of the motor in the forward rotation direction is estimated, and whether the reverse rotation braking should be applied is switched. The length of the rotor is long enough, the torque in the direction of forward rotation is small, and the rotor may also be reversed by reverse braking. On the other hand, the fact that the number of edges of the rectangular signal S2 is greater than the threshold value A is grounds for the motor to reliably rotate in the forward rotation direction, so that the rotor can be prevented from rotating backward even in an abnormal state.

FIG. 8 is a block diagram of a motor drive circuit 100b of the second embodiment.

The reverse braking control unit 114b of the motor drive circuit 100b changes the output of the reverse braking according to the length of the normal driving state. The reverse braking control unit 114b includes a timer circuit 122 instead of the edge counter 116 of FIG. 6 . The timer circuit 122 measures the length of the normal driving state, and generates section length data S6 indicating the measured length. The timer circuit 122 may also be a digital timer that counts up (or counts down) a clock signal in a normal driving state. In other implementations, the timer circuit 122 can also be an analog timer. The determination unit 120 changes the output of the reverse braking in accordance with the measurement time of the timer circuit 122 .

For example, if the measurement time of the timer circuit 122 exceeds a predetermined threshold value C, the determination unit 120 applies reverse rotation braking at a rated output, and does not apply reverse rotation when the measurement time is shorter than the threshold value C and a stop is instructed. Brake or reduce the output of reverse braking.

The above is the configuration of the motor drive circuit 100b in FIG. 8 . Next, its operation will be described.

9( a ) and ( b ) are operation waveform diagrams of the motor drive circuit 100 b of FIG. 8 . Refer to Figure 9(a). At time t0, the control command S1 becomes a high level for instructing rotation. Thereby, the control unit 110 starts to energize the motor 2 . As the rotation speed of the motor 2 increases, the period of the rectangular signal S2 gradually shortens. The section length data S6 indicating the length of the normal driving state gradually increases with time. Since the bit width of the timer circuit 122 is limited, if the segment length data S6 reaches a certain upper limit, the counting up stops.

At time t2, the control command S1 becomes a low level for instructing to stop. At time t2, since S6>C, reverse rotation braking is applied at the rated output. Through reverse braking, the rotor decelerates, and the period of the rectangular signal S2 gradually becomes longer. At time t3, when the period TP of the rectangular signal S2 exceeds the threshold value B, the reverse braking period ends.

Refer to Figure 9(b). At time t0, the control command S1 becomes a high level for instructing rotation. Thereby, the control unit 110 starts energizing the motor 2 . At time t1 immediately after, before the rotation speed of the electric motor 2 increases, the control command S1 becomes low level, and instructs the stop of the electric motor 2 .

At time t1, the section length data S6 is smaller than the threshold C. Therefore, without reverse rotation braking, the rotor is stopped by regenerative braking, or the rotor is stopped naturally.

The above is the operation of the motor drive circuit 100b. Also according to the motor drive circuit 100b, the same effect as that of the motor drive circuit 100a of FIG. 6 is obtained.

A certain aspect of the present invention has been described above based on the second embodiment. The second embodiment is an example, and those skilled in the art will understand that various modifications can be made to the combination of these individual components and processes, and these modifications are also within the scope of the present invention. Hereinafter, such a modified example will be described.

(Seventh modified example)

In the second embodiment, when there is a concern about reverse rotation, the output of the reverse rotation brake is set to zero, but the present invention is not limited thereto. For example, when there is concern about reverse rotation, the output of the reverse brake may be set to a value greater than zero and smaller than the rated output, for example, about 5 to 30%.

(8th modified example)

Alternatively, the output of the reverse braking when reverse rotation is concerned may be adaptively changed from the previous normal driving state. For example, the smaller the number of edges of the rectangular signal S2 measured in the normal driving state, the lower the output of reverse braking, or the shorter the length of the normal driving state, the lower the output of reverse braking. .

(9th modified example)

In the second embodiment, when the period T _P of the rectangular signal S2 exceeds the threshold value B, the reverse braking period ends, but the present invention is not limited thereto. In the ninth modification, the reverse braking is terminated when the number of switching times (the number of edges) of the square signal S2 that occurs during the reverse braking period exceeds a threshold value. When the ninth modification is applied to the first embodiment in FIG. 6 , the edge counter 116 can be used to count the number of edges of the rectangular signal S2 during the reverse braking period. If the number S4 of edges generated during the reverse braking exceeds the threshold value D, the determination unit 120 ends the reverse braking.

When the ninth modification is applied to the second embodiment of FIG. 8 , an edge counter 116 may be added to the reverse braking control unit 114 b.

(10th modified example)

In the tenth modification, when the length of the reverse braking period reaches the predetermined time T _END , the reverse braking is ended. When the tenth modification is applied to the second embodiment in FIG. 8 , the length of the reverse braking period may be measured using the timer circuit 122 . The determination unit 120 compares the reverse braking period measured by the timer circuit 122 with a predetermined time T _END .

When the tenth modified example is applied to the first embodiment shown in FIG. 6 , a timer circuit 122 may be added to the reverse braking control unit 114 a.

(11th modified example)

The Hall comparator 102 can be built in a Hall IC including the Hall element 4 . Alternatively, the Hall element 4 may be built in the motor drive circuit 100 .

(12th modified example)

In the second embodiment, the motor drive circuit 100 that performs commutation control and anti-reverse control using the Hall signal from the Hall element is described, but it may be used instead of the Hall signal from the Hall element. Other signals that contain rotational speed information.

Arbitrary features of the first embodiment and arbitrary features of the second embodiment may be combined, and these combinations are also effective as one aspect of the present invention.

(use)

Next, applications of the motor drive circuit 100 described in the first or second embodiment will be described. Fig. 10(a) is a perspective view of an electronic device 300a including the motor drive circuit 100, and Fig. 10(b) is a cross-sectional view of a vibration motor unit.

The electronic device 300 is a device having a vibration function, for example, a mobile phone terminal, a smartphone, a tablet PC, a portable game device, a controller of a game console, and the like are exemplified. A smartphone is shown as a representative in FIG. 10( a ).

The electronic device 300 includes a vibration device 302 and a main processor 304 . The vibration device 302 is a vibration motor unit in which the motor 2 and the motor drive circuit 100 are integrally formed and covered with a case. As shown in FIG. 10( b ), the motor drive circuit 100 and the coil 312 are mounted on the substrate 310 . Further, a washer 314 is attached to the main shaft 316, and is rotatably supported. At the front end of the main shaft 316, an eccentric weight 318a and a rotor 318 having a permanent magnet 318b embedded in its inner peripheral portion are attached. The vibration device 302 is entirely covered by a case 320 .

The motor drive circuit 100 rotates the motor 2 in response to a control command S1 from the main processor 304 . Main processor 304 may be a baseband processor or an application processor.

FIG. 11 is a perspective view of an electronic device 300b with another structure. An eccentric weight 306 is attached to the rotor of the motor 2 . The motor 2 has a configuration that does not require a Hall element.

The above is the configuration of the electronic devices 300a and 300b. By employing the motor drive circuit 100 of the embodiment for the vibrating device 302 , it is possible to prevent the vibration from continuing due to the reverse rotation of the rotor due to reverse braking, and to stop the vibration immediately.

According to the embodiment, the present invention is described using a specific user. The embodiment only shows the principle and application of the present invention. In the embodiment, various Modifications and configuration changes.

〔Explanation of labels〕

2...Motor, 4...Hall element, 100...Motor driving circuit, 102...Hall comparator, 110...Control part, 130...Drive part, S1...Control command, S2...Rectangular signal, S3...Drive signal, S4... Count value, S5...period data, S6...section length data, S7...end signal, 112...energization control unit, 114...reverse braking control unit, 116...edge counter, 118...period measurement unit, 120...judgment unit, 120a...1st judging section, 120b...2nd judging section, 122...timer circuit, 150...memory, 152...comparator, 154...adder, 156...register, 160...timer circuit, 162...register, 164... Logic gates, 170...edge counter, 172...comparator, 174...register, 300...electronic equipment, 302...vibration device, 304...main processor.

Claims (14)

1. A motor drive circuit, characterized by comprising:

a control unit that generates a drive signal for controlling energization to a coil of a motor to be driven based on a rectangular signal indicating a position of a rotor of the motor, and

a driving unit that drives the coil based on the driving signal;

the control unit measures the cumulative switching times of the rectangular signal from the start of the normal driving state, and when a stop instruction of the motor is received in the normal driving state of the motor, the control unit changes the output of the reverse brake based on the measured switching times of the rectangular signal,

the control unit includes an edge counter for counting the number of edges of the rectangular signal in the normal driving state, and changes the output of the reverse brake according to the count value of the edge counter.

2. The motor drive circuit according to claim 1, wherein the control unit, upon receiving a stop instruction of the motor, decreases the output of the reverse brake when the number of edges of the rectangular signal measured up to this point is smaller than a predetermined threshold value.

3. The motor drive circuit according to claim 1, wherein the control unit does not apply the reverse brake when the number of edges of the rectangular signal measured so far is smaller than a predetermined threshold value upon receiving the stop instruction of the motor.

4. A motor drive circuit, characterized by comprising:

a control unit that generates a drive signal for controlling energization to a coil of a motor to be driven based on a rectangular signal indicating a position of a rotor of the motor, and

a driving unit that drives the coil based on the driving signal;

the control unit measures an elapsed time from the start of a normal driving state, and changes an output of reverse braking based on the measured elapsed time when a stop instruction of the motor is received,

the control unit includes a timer circuit for measuring an elapsed time from the start of the normal driving state, and changes the output of the reverse brake according to the measured time of the timer circuit.

5. The motor drive circuit according to claim 4, wherein the control unit, upon receiving the instruction to stop the motor, reduces the output of the reverse brake compared with the case where the measurement time is shorter than a predetermined threshold value.

6. The motor drive circuit according to claim 4, wherein the control unit does not apply the reverse brake when the measurement time is shorter than a predetermined threshold value upon receiving a stop instruction of the motor.

7. The motor drive circuit according to any one of claims 1 to 6, further comprising a hall comparator for comparing a pair of hall signals from the hall elements in mutually opposite phases and generating the rectangular signal.

8. The motor drive circuit according to any one of claims 1 to 6, wherein the period of the rectangular signal is monitored during the period of the reverse braking, and the control unit ends the reverse braking if the measured period becomes longer than a predetermined 1 st threshold value.

9. The motor drive circuit according to any one of claims 1 to 6, wherein the control unit measures the number of edges of the rectangular signal during the reverse braking, and ends the reverse braking if the measured number of edges exceeds a predetermined 2 nd threshold value.

10. The motor drive circuit according to any one of claims 1 to 6, wherein the control section includes an edge counter for counting the number of edges of the rectangular signal in each of the periods of the normal drive state and the reverse brake,

when a stop instruction of the motor is received, the output of the reverse brake is changed according to the count value of the edge counter obtained in the normal driving state,

during the reverse braking period, if the count value of the edge counter exceeds a predetermined 2 nd threshold value, the reverse braking is terminated.

11. The motor drive circuit according to any one of claims 1 to 6, wherein the control unit measures a length of the period of the reverse braking, and ends the reverse braking if the length of the period of the reverse braking exceeds a predetermined 3 rd threshold value.

12. A motor drive circuit according to any one of claims 1 to 6, wherein the motor drive circuit is integrally formed on a semiconductor substrate.

13. A vibration device, comprising:

a vibration motor having an eccentric weight mounted on a rotor;

the motor drive circuit according to any one of claims 1 to 6, for rotating the vibration motor.

14. An electronic device comprising the vibration apparatus according to claim 13.