JP7192643B2 - Control device and program for brushless motor - Google Patents

Description

The present invention relates to a control device and program for a brushless motor.

The following devices are known as control devices for brushless motors (see, for example, Patent Documents 1 and 2). That is, a known brushless motor control device has a control circuit that outputs a duty signal having a duty ratio corresponding to a speed command, and a plurality of switching elements connected to a plurality of phases of stator coils. an energizing circuit for turning on and off the plurality of switching elements by using a complementary energizing method to energize the stator coils of the plurality of phases.

JP 2011-30385 A JP-A-7-307435

In the brushless motor controller, when a stop command is received, the rotor is decelerated by gradually lowering the duty ratio of the duty signal in order to ramp-control the rotation speed of the rotor. However, in the complementary energization method, when the duty ratio of the duty signal becomes 0%, the stator coils of all phases are energized with a duty ratio of 50%, and a so-called short brake occurs, causing a stop sound (brake noise) is generated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a control device and program for a brushless motor that can suppress stop noise of the brushless motor.

A brushless motor control device according to claim 1 has a control circuit that outputs a duty signal having a duty ratio corresponding to a speed command, and a plurality of switching elements connected to a plurality of phases of stator coils. an energization circuit that turns on and off the plurality of switching elements based on a signal to energize the stator coils of the plurality of phases in a complementary energization method, wherein the control circuit controls the rotation speed of the rotor when a stop command is received. is less than a specified number of revolutions or the duty ratio is less than the specified duty ratio; a deceleration control unit for reducing the duty ratio when the determining unit determines that the number of revolutions of the rotor is less than the specified number of revolutions or the duty ratio is less than the specified duty ratio. and an energization stop control unit that turns off the plurality of switching elements when a short brake occurs, and the specified rotation speed is set to a rotation speed immediately before the timing at which the short brake occurs, or The specified duty ratio is set to a duty ratio immediately before the timing at which the short brake occurs .

According to this brushless motor control device, when a stop command is received, the determining section determines whether the rotation speed of the rotor is less than the specified rotation speed or the duty ratio is less than the specified duty ratio. Here, when the determination unit determines that the rotation speed of the rotor is equal to or higher than the specified rotation speed or the duty ratio is equal to or higher than the specified duty ratio, the deceleration control unit reduces the duty ratio. When the above operation is repeated, the rotation speed of the rotor gradually decreases.

When the determination unit determines that the rotation speed of the rotor is less than the specified rotation speed or the duty ratio is less than the specified duty ratio, the energization stop control unit turns off the plurality of switching elements. Therefore, the energization of the stator coils of all phases is stopped before the short brake occurs. As a result, the rotor rotates by inertia, gradually decelerates, and then stops, so that it is possible to suppress the occurrence of a stop sound.

A program according to claim 2 has a control circuit that outputs a duty signal having a duty ratio corresponding to a speed command, and a plurality of switching elements connected to a plurality of phases of stator coils. and an energizing circuit that turns on and off the plurality of switching elements to energize the stator coils of the plurality of phases in a complementary energizing method, wherein when a stop command is received, a determination step of determining whether the number of rotations of the rotor is less than the specified number of rotations or the duty ratio is less than the specified duty ratio; a deceleration control step of reducing the duty ratio if the determining step determines that the duty ratio is less than the specified duty ratio ; and a de-energization control step of turning off the plurality of switching elements when the determination step determines , wherein the specified rotation speed is immediately before the timing at which the short brake occurs. Alternatively, the specified duty ratio is set to the duty ratio immediately before the timing at which the short brake occurs .

According to this program, when a stop command is received, it is determined in the determination step whether the rotation speed of the rotor is less than the specified rotation speed or the duty ratio is less than the specified duty ratio. Here, if it is determined in the determination step that the rotation speed of the rotor is equal to or higher than the specified rotation speed or the duty ratio is equal to or higher than the specified duty ratio, the duty ratio is decreased by the deceleration control step. When the above operation is repeated, the rotation speed of the rotor gradually decreases.

Then, when it is determined in the determination step that the rotation speed of the rotor is less than the specified rotation speed or the duty ratio is less than the specified duty ratio, the plurality of switching elements are turned off by the energization stop control step. Therefore, the energization of the stator coils of all phases is stopped before the short brake occurs. As a result, the rotor rotates by inertia, gradually decelerates, and then stops, so that it is possible to suppress the occurrence of a stop sound.

1 is a diagram schematically showing the configuration of a brushless motor device using a brushless motor control device according to an embodiment of the present invention; FIG. FIG. 2 is a flow chart showing a first operation example of the CPU in FIG. 1; FIG. 4 is a flowchart showing a second operation example of the CPU of FIG. 1; FIG. 9 is a diagram showing an example (comparative example) of measurement results when a short brake is generated with a duty ratio of 0% in an actual machine; It is a figure which shows an example (comparative example) of the result of having measured the rotation speed which a short brake begins to generate|occur|produce by changing conditions in an actual machine. FIG. 7 is a diagram showing an example (comparative example) of measurement results of waveforms when a short brake is generated by performing RAMP control; FIG. 10 is a diagram showing an example (comparative example) of waveforms and sound pressure measurement results when a short brake is generated by performing RAMP control; FIG. 5 is a diagram showing an example (this example) of measurement results of waveforms and sound pressures when energization of stator coils of all phases is stopped just before a duty ratio becomes 0% by performing RAMP control;

First, the configuration of a brushless motor device using a brushless motor control device according to an embodiment of the present invention will be described.

FIG. 1 schematically shows the configuration of a brushless motor device 1 using a brushless motor control device 10 according to the present embodiment. The brushless motor device 1 is used, for example, as an in-vehicle blower motor. The brushless motor device 1 includes a brushless motor 2 and a brushless motor control device 10 (hereinafter abbreviated as the control device 10).

The brushless motor 2 includes a rotor 3 , a stator 4 and Hall elements 5 . The rotor 3 includes a rotor magnet 6 having a plurality of (six, for example) magnetic poles, and the stator 4 includes a multi-phase stator coil 7 composed of U-phase, V-phase, and W-phase. When the multi-phase stator coils 7 are energized, a rotating magnetic field is formed in the stator 4 , and the rotating magnetic field acts on the rotor magnet 6 with attractive and repulsive forces, causing the rotor 3 to rotate.

The Hall element 5 detects the rotation speed of the rotor 3 and is arranged to face the rotor magnet 6 . The Hall element 5 outputs an H level detection signal when facing the N pole of the rotor magnet 6 and outputs an L level detection signal when facing the S pole of the rotor magnet 6 .

The control device 10 is, for example, an ECU (Electrical Control Unit) for motor control, and includes a control circuit 12 and an energizing circuit 14 . The energizing circuit 14 has a pre-driver 16 and a three-phase inverter 18 . The control circuit 12 is connected with the external ECU 8 and the Hall element 5 , and the pre-driver 16 is connected with the control circuit 12 and the three-phase inverter 18 .

When receiving a speed command from the external ECU 8, the control circuit 12 calculates a duty ratio according to the speed command from the external ECU 8 and the detection signal from the Hall element 5, and performs PWM (Pulse Width Modulation) having this duty ratio. It has a function of outputting a duty signal, which is a signal, to the predriver 16 .

The pre-driver 16 has a function of generating a drive signal, which is a PWM signal, based on the duty signal output from the control circuit 12 and outputting this drive signal to the three-phase inverter 18 .

The three-phase inverter 18 has a plurality of switching elements 20 connected to the stator coils 7 of multiple phases. The plurality of switching elements 20 form a bridge circuit. That is, the switching elements 20 arranged as upper arms of the U, V, and W phases are connected to the positive pole of the power supply 9, and the switching elements 20 arranged as lower arms of the U, V, and W phases are , is connected to the negative pole of the power supply 9 . The U-phase switching elements 20, the V-phase switching elements 20, and the W-phase switching elements 20 are connected to the stator coils 7 of the respective phases.

When a drive signal is output from the pre-driver 16, the plurality of switching elements 20 are turned on and off, power is supplied from the power source 9 to the multi-phase stator coils 7, and the multi-phase stator coils 7 are energized. In this embodiment, the multi-phase stator coils 7 are energized by a complementary energization method.

The control circuit 12 is, for example, a microcomputer. Specifically, the control circuit 12 has a CPU 30 (Central Processing Unit), a ROM 32 (Read Only Memory), and a RAM 34 (Random Access Memory). A program 36 is stored in the ROM 32 . The CPU 30 is a central processing unit (computer), reads a program 36 stored in a ROM 32, develops the program 36 in a RAM 34, and executes it.

The control circuit 12 has a determination section 40, a deceleration control section 42, and an energization stop control section 44 as components that function when a stop command is received from the external ECU 8. FIG. The determination unit 40 , the deceleration control unit 42 , and the de-energization control unit 44 are implemented by the CPU 30 executing the program 36 .

That is, the determination unit 40 is implemented by the CPU 30 executing the program 36 (step S1 or step S11, which will be described later). This determination unit 40 has a function of determining whether the rotation speed of the rotor 3 is less than a specified rotation speed or the duty ratio is less than a specified duty ratio when a stop command is received from the external ECU 8 . Step S1 or step S11 executed by the determination unit 40 corresponds to the determination step.

The deceleration control unit 42 is implemented by the CPU 30 executing the program 36 (step S2 or step S12, which will be described later). The deceleration control unit 42 has a function of decreasing the duty ratio when the determination unit 40 determines that the rotation speed of the rotor 3 is equal to or higher than the specified rotation speed or the duty ratio is equal to or higher than the specified duty ratio. Step S2 or step S12 executed by the deceleration control unit 42 corresponds to the deceleration control step.

The de-energization control unit 44 is implemented by the CPU 30 executing the program 36 (step S3 or step S13, which will be described later). The de-energization control unit 44 has a function of turning off the plurality of switching elements 20 when the determination unit 40 determines that the rotation speed of the rotor 3 is less than the specified rotation speed or the duty ratio is less than the specified duty ratio. have. Step S3 or step S13 executed by the de-energization control unit 44 corresponds to the de-energization control step.

Next, operation of the CPU 30 will be described.

The CPU 30 operates as in the following first operation example or second operation example. FIG. 2 shows the flow of processing in the first operation example of the CPU 30, and FIG. 3 shows the flow of processing in the second operation example of the CPU 30. As shown in FIG. When receiving a stop command from the external ECU 8, the CPU 30 starts the processing shown in FIG. 2 or the processing shown in FIG. Hereinafter, the first operation example and the second operation example will be described in order.

(First operation example: see Fig. 2)
In step S<b>1 , CPU 30 (determination unit 40 ) determines whether or not the rotation speed of rotor 3 is less than a specified rotation speed based on the detection signal output from Hall element 5 . When the CPU 30 determines that the rotation speed of the rotor 3 is not less than the specified rotation speed, the CPU 30 proceeds to step S2.

In step S2, the CPU 30 (deceleration control unit 42) reduces the duty ratio of the duty signal. As the duty ratio of the duty signal decreases, the rotational speed of the rotor 3 decreases accordingly. The CPU 30 repeats the above operations until it determines that the rotation speed of the rotor 3 is less than the specified rotation speed. As a result, the duty ratio gradually decreases and the rotation speed of the rotor 3 gradually decreases. That is, when a stop command is received, the rotor 3 is decelerated by gradually decreasing the duty ratio of the duty signal in order to ramp-control the rotational speed of the rotor 3 .

Here, in the complementary energization method, when the duty ratio of the duty signal becomes 0%, the stator coils 7 of all phases are energized with a duty ratio of 50%, so that a so-called short brake occurs and a stop sound is generated. There's a problem.

Therefore, the above-mentioned specified number of revolutions is set to a number of revolutions before the timing at which the short brake occurs. The timing at which the short brake occurs can be confirmed on the actual machine. The above specified rotation speed is set to, for example, the rotation speed at which the short braking starts + 100 rpm. When the CPU 30 determines that the rotation speed of the rotor 3 is less than the specified rotation speed, the CPU 30 proceeds to step S3.

In step S<b>3 , the CPU 30 (power supply stop control unit 44 ) outputs a power supply stop signal to the pre-driver 16 . When the energization stop signal is output to the pre-driver 16 , the pre-driver 16 turns off the plurality of switching elements 20 . At this time, the energization of the stator coils 7 of all phases is stopped before short braking occurs. Therefore, the rotor 3 rotates by inertia, gradually decelerates, and then stops, thereby suppressing the occurrence of stop noise.

(Second operation example: see Fig. 3)
In step S11, CPU 30 (determining unit 40) determines whether the duty ratio of the duty signal is less than the specified duty ratio. When the CPU 30 determines that the duty ratio is not less than the prescribed duty ratio, the process proceeds to step S12.

In step S12, the CPU 30 (deceleration control unit 42) reduces the duty ratio of the duty signal. As the duty ratio of the duty signal decreases, the rotational speed of the rotor 3 decreases accordingly. The CPU 30 repeats the above operations until it determines that the duty ratio is less than the specified duty ratio. As a result, the duty ratio gradually decreases and the rotation speed of the rotor 3 gradually decreases. That is, when a stop command is received, the rotor 3 is decelerated by gradually decreasing the duty ratio of the duty signal in order to ramp-control the rotational speed of the rotor 3 .

Here, in the complementary energization method, when the duty ratio of the duty signal becomes 0%, the stator coils 7 of all phases are energized with a duty ratio of 50%, so that a so-called short brake occurs and a stop sound is generated. There's a problem. Therefore, the above specified duty ratio is set to a duty ratio just before 0%. The specified duty ratio mentioned above is set to, for example, 5%. When the CPU 30 determines that the duty ratio is less than the specified duty ratio, the CPU 30 proceeds to step S13.

In step S<b>13 , the CPU 30 (power supply stop control unit 44 ) outputs a power supply stop signal to the pre-driver 16 . When the energization stop signal is output to the pre-driver 16 , the pre-driver 16 turns off the plurality of switching elements 20 . At this time, the energization of the stator coils 7 of all phases is stopped before short braking occurs. Therefore, the rotor 3 rotates by inertia, gradually decelerates, and then stops, thereby suppressing the occurrence of stop noise.

Next, the operation and effects of this embodiment will be described.

As described in detail above, according to the control device 10 according to the present embodiment, when a stop command is received, it is determined whether the rotation speed of the rotor 3 is less than the specified rotation speed or the duty ratio is less than the specified duty ratio. is determined by the determination unit 40 . Here, when the determining unit 40 determines that the rotation speed of the rotor 3 is equal to or higher than the specified rotation speed or the duty ratio is equal to or higher than the specified duty ratio, the deceleration control unit 42 reduces the duty ratio. When the above operation is repeated, the rotation speed of the rotor 3 gradually decreases.

When the determining unit 40 determines that the rotation speed of the rotor 3 is less than the specified rotation speed or the duty ratio is less than the specified duty ratio, the energization stop control unit 44 turns off the plurality of switching elements 20. . Therefore, the energization of the stator coils 7 of all phases is stopped before short braking occurs. As a result, the rotor 3 rotates by inertia, gradually decelerates, and then stops, so that it is possible to suppress the occurrence of a stop sound.

Moreover, even if the setting of the RAMP control is changed, the timing at which all the switching elements 20 are turned off is the same, so the stop time of the rotor 3 can be uniformed.

Moreover, since the timing at which all the switching elements 20 are turned off can be changed by setting the RAMP control, the RAMP control can be performed until the timing immediately before the stop sound is generated.

Furthermore, since the stop sound can be suppressed simply by changing the setting of the program 36, it can be easily used for other products.

Next, an example of this embodiment will be described.

First, a comparative example in which a short brake is generated with a duty ratio of 0% will be described. FIG. 4 is a diagram showing an example of measurement results when a short brake is generated with a duty ratio of 0% in an actual machine. As shown in FIG. 4, in the complementary energization method, when the duty ratio of the duty signal becomes 0%, the stator coils of all phases are energized with a duty ratio of 50%, causing a so-called short brake to stop the motor. A stop sound is generated. In the example shown in FIG. 4, as an example, the rotational speed at which the short brake starts to occur is 800 rpm. FIG. 5 shows an example of the result of measuring the rotational speed at which the short brake starts to occur under different conditions in an actual machine.

FIG. 6A shows an example of measurement results of each waveform when RAMP control is performed at 900 rpm/s to generate a short brake, and FIG. An example of the measurement result of each waveform when RAMP control is performed to generate a short brake is shown. As shown in FIG. 6(A), when the RAMP control is performed at 900 rpm/s, short braking begins to occur at 1000 rpm. On the other hand, as shown in FIG. 6(B), when the RAMP control is performed at 1500 rpm/s, short braking begins to occur at 1400 rpm.

FIG. 7 shows an example of waveforms and sound pressure measurement results when a short brake is generated by performing RAMP control at 1500 rpm/s. In the example shown in FIG. 7, the amplitude of the phase current begins to increase at 1400 rpm, and the amplitude of the phase current reaches its maximum at 850 rpm. Further, the amplitude of the sound pressure becomes large at 1400 rpm, and the amplitude of the sound pressure becomes maximum at 803 rpm.

Next, examples of the present embodiment will be described. FIG. 8 shows an example of measurement results of waveforms and sound pressure when the energization of the stator coils of all phases is stopped just before the duty ratio becomes 0% under RAMP control at 1500 rpm/s. ing. In the example shown in FIG. 8, as an example, energization to the stator coils of all phases is stopped at 1500 rpm. This suppresses the amplitude of the sound pressure at 803 rpm and suppresses the occurrence of the stop sound.

Next, a modified example of this embodiment will be described.

In the above embodiment, the control device 10 has a control circuit 12, which is a microcomputer, as a hardware configuration. Each functional unit such as the determination unit 40 in the control circuit 12 is implemented by the CPU 30 executing the program 36 .

However, each functional unit such as the determination unit 40 in the control circuit 12 may be realized by a PLD (Programmable Logic Device) whose circuit configuration can be changed after manufacturing, such as an FPGA (Field-Programmable Gate Array). good.

Further, each functional unit such as the determination unit 40 in the control circuit 12 is realized by a dedicated electric circuit designed exclusively for executing a specific process, such as an ASIC (Application Specific Integrated Circuit). good too.

An embodiment of the present invention has been described above, but the present invention is not limited to the above, and can of course be implemented in various modifications without departing from the gist of the present invention. is.

DESCRIPTION OF SYMBOLS 1... Brushless motor apparatus 2... Brushless motor 3... Rotor 4... Stator 5... Hall element 6... Rotor magnet 7... Stator coil 8... External ECU 9... Power supply 10... Control device 12... Control circuit 14 Energizing circuit 16 Pre-driver 18 Three-phase inverter 20 Switching element 30 CPU (computer) 32 ROM 34 RAM 36 Program 40 Determination section 42 deceleration control unit, 44... de-energization control unit

Claims (2)

a control circuit that outputs a duty signal having a duty ratio corresponding to the speed command;
an energization circuit having a plurality of switching elements connected to a multi-phase stator coil, for turning on and off the plurality of switching elements based on the duty signal to energize the multi-phase stator coil in a complementary energization method;
with
The control circuit is
a determination unit that determines whether the rotation speed of the rotor is less than a specified rotation speed or the duty ratio is less than a specified duty ratio when a stop command is received;
a deceleration control unit that reduces the duty ratio when the determination unit determines that the number of revolutions of the rotor is equal to or greater than the specified number of revolutions or that the duty ratio is equal to or greater than the specified duty ratio;
an energization stop control unit that turns off the plurality of switching elements when the determination unit determines that the number of revolutions of the rotor is less than the specified number of revolutions or that the duty ratio is less than the specified duty ratio;
has
The specified rotation speed is set to a rotation speed immediately before the timing at which the short brake is generated, or the specified duty ratio is set to the duty ratio immediately before the timing at which the short brake is generated.
Controller for brushless motor. a control circuit having a computer that outputs a duty signal having a duty ratio corresponding to the speed command;
an energization circuit having a plurality of switching elements connected to a multi-phase stator coil, for turning on and off the plurality of switching elements based on the duty signal to energize the multi-phase stator coil in a complementary energization method;
A program applied to a control device for a brushless motor comprising
a determination step of determining whether the rotation speed of the rotor is less than a specified rotation speed or the duty ratio is less than a specified duty ratio when a stop command is received;
a deceleration control step of reducing the duty ratio when the determination step determines that the number of rotations of the rotor is equal to or greater than the specified number of revolutions or that the duty ratio is equal to or greater than the specified duty ratio;
an energization stop control step of turning off the plurality of switching elements when it is determined in the determination step that the rotation speed of the rotor is less than the specified rotation speed or the duty ratio is less than the specified duty ratio;
is a program for causing the computer to execute
The specified rotation speed is set to a rotation speed immediately before the timing at which the short brake is generated, or the specified duty ratio is set to the duty ratio immediately before the timing at which the short brake is generated.
program.

Images