JP2001339970A - Energizing control method for motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an energizing control method which enables to suppress inrush current immediately after energizing a motor and securely operate the motor. SOLUTION: An actual current Ia which flows in the motor 31 and a designated current I3 which is preliminary set are compared. If the actual current Ia is larger than the designated current I3, the duty ratio of energizing duration and non-energizing one is made smaller by a designated ratio. If the actual current Ia is smaller than the designated current I3 and the duty ratio does not exceed 100% even when the duty ratio is made larger by the designated ratio, the duty ratio of energizing duration and non-energizing one to the motor 31 is made larger by the designated ratio. If the actual current Ia is smaller than the designated current I3 and the duty ratio exceed 100% when the duty ratio is made larger by the designated ratio, the motor 31 is always energized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an energization control method for controlling a current flowing through a motor, and more particularly to an energization control method for controlling an inrush current flowing immediately after the start of energization.

[0002]

2. Description of the Related Art A conventional energization control method is disclosed in
There is a technique disclosed in JP-A-223983. This technology includes a motor that generates an output torque according to the load current, a rod that reciprocates in the axial direction, and a motor that converts the output torque into an axial thrust and transmits it to the rod. A power transmission mechanism that rotates the motor in the reverse direction by a load applied to the rod when stopped, and energization of the motor for a predetermined time (1 second). When a current of a predetermined value or more flows through the motor, the current is PWM-controlled to a predetermined value. There is disclosed a drive switching mechanism for switching a drive state of a vehicle including a motor drive circuit for limiting a load current so as not to generate an output torque greater than a torque.

According to the energization control method disclosed in this technology, the load current flowing through the motor is limited by the PWM control, and the output torque of the motor is suppressed, so that a large load is not applied to the rod or the power transmission mechanism. The power transmission mechanism and components can be reduced in size.

[0004]

However, in the technique disclosed in the above publication, the current value is limited by the PWM control when the motor is energized and the actuator is not operated. However, there is no mention of limiting the inrush current flowing through the motor immediately after the start of energization of the motor.If a large inrush current flows through the motor, the motor will overheat and the motor drive circuit will deteriorate. And the durability is reduced.

In view of the above circumstances, an object of the present invention is to provide an energization control method capable of suppressing an inrush current flowing immediately after energization of an electric motor and reliably operating the electric motor.

[0006]

According to a first aspect of the present invention, there is provided an energization control method performed immediately after energization of an electric motor driven in accordance with an energization current is started.
The actual current value flowing through the motor is compared with a preset predetermined current value. If the actual current value is larger than the predetermined current value, the duty ratio of energizing / de-energizing the motor is reduced by a predetermined ratio, and the actual current value is reduced. Even if the value is smaller than the predetermined current value and the duty ratio is increased by the predetermined ratio, the duty ratio is 1
When the duty ratio does not exceed 00%, the duty ratio of energizing / de-energizing the motor is increased by a predetermined ratio, and the duty ratio when the actual current value is smaller than the predetermined current value and the duty ratio is increased by the predetermined ratio exceeds 100%. At times, the duty ratio is set to 100%.

According to the first aspect, when the inrush current flowing into the motor immediately after the start of energization becomes larger than a predetermined current value, the energization duty ratio to the motor is reduced by the predetermined ratio. Is smaller than before. When the actual current value is smaller than the predetermined current value and the duty ratio does not exceed 100% even if the duty ratio is increased by the predetermined ratio, the duty ratio is increased by the predetermined ratio to secure the current flowing through the motor near the predetermined current value. I do. As a result, the durability of the electric motor is not significantly reduced. When the actual current value is smaller than the predetermined current value and the duty ratio exceeds 100% when the duty ratio is increased by the predetermined ratio, the current flowing through the motor is considered to be stable and steady. , The duty ratio to the motor is 100
Set to%. According to such an energization control, claim 1
According to the invention, the current value is stabilized around the predetermined current value. Therefore, a large current such as an inrush current flowing immediately after the start of energization does not flow through the motor, so that the motor does not generate excessive heat, and a current value near a predetermined current value flows through the motor, so that the motor operates reliably. Responsiveness of the electric motor is also ensured.

[0008]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a two-wheel drive of an automobile which is an apparatus including an electric motor in which the energization control method of the present embodiment is performed.
1 shows a cross-sectional view of a four-wheel drive switching device 10. In FIG. 1, hatching is omitted except for some components so that each component is not difficult to see.

The drive switching device 10 is disposed between an input shaft 24, which is an output of a transmission (not shown), and a front wheel drive shaft 12 and a rear wheel drive shaft 11 of the vehicle. 30 is a device that switches the driving state of the vehicle to three states of two-wheel drive, four-wheel drive (center differential lock) and four-wheel drive (center differential free) by the operation of 30. Rotational driving force is transmitted to the rear wheel drive shaft 11 via the input shaft 24, and the rotational drive force of the rear wheel drive shaft 11 can be transmitted from the center differential unit 13 to the front wheel drive shaft 12 via the silent chain 19. Have been. The center differential unit 13 is a device for absorbing a difference in rotation speed between the front wheel drive shaft 12 and the rear wheel drive shaft 11, and is constituted by a planetary gear mechanism.

The switching of the driving state by the drive switching device 10 will be described. The drive switching device used in the present embodiment switches the drive state of the vehicle to three states of two-wheel drive, four-wheel drive (center differential lock) and four-wheel drive (center differential free) according to the position of rod 33. And the second motor-drive 4 disposed on each of the shafts 14 and 15 by moving the first shaft 14 in the axial direction according to the position of the rod 33.
The drive switching shift fork 16 and the center differential lock shift fork 17 move in the axial direction, and sleeves 16A, 17A provided at the ends of the shift forks 16, 17 are provided.
Is moved in the axial direction. As a result, the driving state of the vehicle is switched. In the four-wheel drive (center differential free) state, the members on the front wheel drive shaft 12 side and the center differential unit 1
And the rotational drive force of the rear wheel drive shaft 11 is absorbed by the front wheel drive shaft 12 via the silent chain 19 while absorbing the difference between the rotational speeds of the two drive shafts 11 and 12 by the planetary gear action of the planetary gear mechanism. Is transmitted to In the four-wheel drive (center differential lock) state, the sleeve 17A is in the upper position in the drawing, the planetary gear mechanism of the center differential unit 13 is locked, and the front wheel drive shaft 12 and the rear wheel drive shaft 11 are directly connected to each other. 11 and 12 are driven to rotate at the same rotation speed. In the two-wheel drive state, the member on the front wheel drive shaft 12 side and the center differential unit 13 are not connected, and the rotational driving force of the input shaft 24 is transmitted only to the rear wheel drive shaft 11.

Next, the drive switching device actuator 30
Will be described. FIG. 2 is a sectional view of the drive switching device actuator 30 according to the present embodiment, and FIG.
FIG. The drive switching device actuator 30 is a motor 31 that is an electric motor that is rotationally driven according to the load current.
An output mechanism 32 that converts the rotational torque of the output shaft 31A of the motor 31 into an axial thrust and outputs the thrust;
A thrust corresponding to the rotational torque of the motor 31 is transmitted through the rod 33, and the position of the rod 33 is displaced according to the transmitted thrust.
A cycloid gear 34 disposed between the output shaft 31A of the motor 31 and the output mechanism 32 to prevent the output shaft 31A from rotating by the power transmitted from the rod 33 to the output shaft 31A; 34 and output mechanism 3
2 when the motor 31 rotates and the rod 3
3, a rotation absorbing mechanism 35 for absorbing the rotation of the motor 31 when the reciprocation is not possible, a rotation absorbing mechanism 35 and an output shaft 31A.
And a limit switch 36 for detecting the rotation angle of the output shaft 31A. Further, the drive switching device requiring actuator 30 includes a control mechanism 40 provided outside the housing 37 for inputting an external signal to select a driving state of the vehicle and outputting an electric current to the motor 31 so as to attain the selected driving state. ing. FIG. 4 shows a circuit configuration of the control mechanism 40.

The rotation absorbing mechanism 35 includes the cycloid gear 3
And a motor-side rotating member 35A capable of transmitting the rotation of the output shaft 31A of the motor 31 via the motor 4 and a motor-side rotating member 35A.
Spiral Spring 35B Elasticized in the Direction of Rotation
An output-side rotating member 35C capable of transmitting a rotational force to the output mechanism 32; a motor-side rotating member 35A;
5C.

The control mechanism 40 will be described. The control mechanism 40 is a battery (not shown) which is an external signal.
Power supply, vehicle speed, manual switch 50
OFF, contact / non-contact of a plurality of terminals of the limit switch 36, and input of a current flowing through the motor 31, so that the motor 31 is driven in accordance with these input signals.
It is configured by a CPU 41 that calculates a current flowing through the relays and outputs ON / OFF of the relays 42 and 43 and the FETs 44 and 45 to output the calculated current value. Motor 31
The current flowing through the motor 31 is compared with a plurality of predetermined current values set in advance by the comparator 46 to detect whether the current flowing through the motor 31 has reached the predetermined current value. ing.

The operation of the drive switching device actuator 30 will be described with reference to time charts shown in FIGS. In this embodiment, four-wheel drive (center differential free)
The operation of each component at the time of switching from to the four-wheel drive (center differential lock) will be described. FIG. 5 shows the actual current value Ia flowing through the motor 31, FIG. 6 shows the thrust acting on the rod 33 by the spiral spring 35B of the rotation absorbing mechanism 35,
FIG. 7 shows the stroke of the rod 33.
First, each state at times t0 to t1 will be described. 4
When the center differential lock switch of the manual switch 50 is turned on from the wheel drive (center differential free) state,
The CPU 41 outputs on / off signals of the relays 42 and 43 and the FETs 44 and 45, and the energization of the motor 31 is started (time t0). Here, immediately after the start of energization, the motor 3
Although the inrush current is about to flow through the motor 1, the inrush current flowing through the motor 31 is suppressed by the first duty control described later, so that only a current of about the first predetermined current value I1 flows through the motor 31. The first duty control corresponds to the energization control described in the claims of the present invention, and the first predetermined current value I1 is the predetermined current value described in the claims of the present invention. It corresponds to. After the time t0 'has elapsed from the start of energization and the inrush current stops flowing, the steady current I2 flows to the motor 31. Thus, at time t0 to t1, a current flows through the motor 31 and the output shaft 31A
Is driven to rotate, and the rod 33 is displaced in the axial direction via the output mechanism 32. At this time, the axial displacement of the rod 33 is not restricted, and the rod 33 strokes in proportion to time, and only the sliding resistance of each member acts on the spiral spring 35B.

Next, when the center differential lock shift fork 17 is displaced in the axial direction with the stroke of the rod 33, the splines formed on the inner and outer circumferences of the sleeve 17A and the splines formed on the center differential unit 13 are engaged. Although the sleeve 17A integrally rotates the planetary gear mechanism so as to prevent the planetary gear mechanism of the differential unit 13 from acting, the center differential lock state is established. However, even if the sleeve 17A is displaced in the axial direction, the planetary gear mechanism remains in the center differential free state. The splines formed on the inner and outer circumferences of the sleeve 17A and the splines formed on the center differential unit 13 do not immediately mesh with each other until the splines on the sleeve 17A and the splines on the center differential unit 13 mesh. , Time t1
The spiral spring 35B indicated by t3 is held in an elasticized state (hereinafter, referred to as a waiting state). In this waiting state, the rod 33 cannot be displaced in the axial direction, and accordingly, the actual current value Ia gradually increases. Actual current value Ia
Is the second predetermined current value I3 detected by the comparator 46.
(Time t2), the current flowing through the motor 31 is maintained at the second predetermined current value I3 by the PWM control, and O
The second duty control for energizing / de-energizing the motor 31 is performed by the N-OFF control (time t2 to t3), and heat generation of the motor 31 due to an overcurrent is suppressed. The period of the PWM control of the second duty control performed at time t2 to t3 is several hundreds μ.
sec, ON / OFF control cycle is several hundred msec to several s
ec. Since the output shaft 31A is connected to the rotation absorbing mechanism 35 via the cycloid gear 34, the output shaft 31A does not rotate in the reverse direction even when the motor 31 is de-energized, and the current is turned ON / OFF. Control becomes possible. The elastic compression of the spiral spring 35B at times t1 to t3 will be described. From time t1 to time t2, the motor 3
As the 1 rotates, the load acting on the spiral spring 35B gradually increases, and the rotation of the motor 31 stops at time t2. Time t during which the second duty control is performed
From 2 to t3, a substantially constant load acts on the spiral spring 35B without rotating the motor 31 and the rod 33
Approximately constant thrust is stored.

The second duty control is performed until the spline of the sleeve 17A meshes with the spline of the center differential unit 13. When the sleeve 17A meshes with the spline of the center differential unit 13 (time t3), the sleeve 17A moves along the spline. Displaces in the axial direction.

From time t3 to time t4, the spiral spring 35B shifts from the elastic state to the non-elastic state, and the load on the spiral spring 35B becomes zero (time t4). At this time, the rod 33 is quickly displaced in the axial direction by the elastic force of the spiral spring 35B.

During a period from time t4 to t5, the power supply to the motor 31 is continuously performed. Since the sleeve 17A is displaced in the axial direction along the spline of the center differential unit 13,
The rod 33 strokes in proportion to time, and the motor 31
Has a steady current I2 substantially equal to the current required to reach the waiting state.
Flows.

At times t5 to t6, the sleeve 17A is displaced along the spline to the position where the switching of the driving state is completed, and the displacement of the rod 33 in the axial direction is regulated until the power supply to the motor 31 is stopped. I have. After the time t5 has elapsed, the actual current value Ia gradually increases, and when the actual current value Ia reaches the third predetermined current value I4 detected by the comparator 46 (time t6), the motor 31 is de-energized, and The switching from the wheel drive (center differential free) to the four-wheel drive (center differential lock) is completed.

The time t0 to t in FIG.
The first duty control at 0 'will be described. FIG. 8 is a time chart showing the energized / deenergized duty ratio, the actual current value Ia, and the first predetermined current value I1 at times t0 to t0 ′ in FIG. FIG. 9 is a flowchart relating to energization of the motor 31.

In the present embodiment, the time t0 to t0 'during which the inrush current flows is several to several tens of msec, and the first duty control is PWM control in which the cycle T is set to several hundred μsec.

The energization of the motor 31 will be described with reference to the flowchart of FIG. In step 10, it is determined whether or not there is a request to switch the driving state of the vehicle. If there is a request to switch, the process proceeds to step 11 to start energizing the motor 31. Next, in step 12, the ratio D set in advance
0 (0 <D0 <100) and the cycle T are turned on to turn on the switch and energize the motor 31, and at step 13, the switch is turned off for the time obtained by multiplying the difference between 100 and D0 by the cycle T. Power supply to the motor 31 is stopped. Next, proceeding to step 14, the actual current value Ia flowing through the motor 31 is compared with the first predetermined current value I1, and when the actual current value Ia is equal to or less than the first predetermined current value I1, the energization ratio to the motor 31 is determined. It is determined that it is necessary to increase the value, and the routine proceeds to step 15, where the ratio Dn-1 (n is a positive integer) is set to a predetermined ratio h (0 <h).
It is determined whether the value obtained by adding <100) is 100% or more,
If it is smaller than 100%, at step 16 Dn-1
Is the value obtained by adding h to Dn. As a result, the duty ratio of energizing / de-energizing the motor 31 increases by a predetermined ratio. In step 14, the actual current value Ia is set to the first predetermined current value I1.
If it is larger, the process proceeds to step 17 where the ratio Dn-1
Dn is the value obtained by subtracting the predetermined ratio h from. As a result, the duty ratio of energizing / de-energizing the motor 31 is reduced by a predetermined ratio. If the value obtained by adding the predetermined ratio h to Dn-1 is equal to or more than 100% in step 15, the process proceeds to step 20, and it is determined that the current does not exceed the first predetermined current I1 even if the energization ratio for the period T is 100%. And motor 31
Is always energized. Steps 16 and 17 to Step 18
The switch 31 is turned on to energize the motor 31 only for the time obtained by multiplying the cycle T by the value Dn obtained in step 16 or step 17, and only the time obtained by multiplying the difference between 100% and Dn by the cycle T in step 19 The switch is turned off to stop energizing the motor 31. Here, the cycle T performed in steps 12 and 13 and steps 18 and 19 is a very short time (several hundred μsec).
During the period T, the current flowing through the motor 31 does not become completely zero. Therefore, the actual current flowing through the motor 31 does not become completely zero as shown in FIG. 8 and keeps around the first predetermined current value I1. Steps 14 to 19 described above are repeated until the value obtained by adding Dn-1 to the predetermined ratio h in step 15 becomes 100% or more, that is, until the actual current value Ia flowing through the motor 31 is stabilized.
Steps 11 to 20 in FIG. 9 correspond to the first duty control. The predetermined ratio h used in steps 16 and 17 may be set to different ratios in steps 16 and 17.

When the first duty control is completed, the process proceeds from step 20 to step 21 to determine whether or not the actual current value Ia is equal to or greater than a second predetermined current value I3. When the actual current value Ia is smaller than the second predetermined current value I3 in step 21, the process proceeds to step 23, and it is determined whether the switching of the driving state is completed. When the switching is not completed, the process returns to step 20 to always energize the motor 31, the rod 33 cannot be displaced in the axial direction, and the current flowing through the motor 31 gradually increases. If it is determined that the current has reached the second predetermined current value I3, the routine proceeds to step 22, where the above-described second duty control is performed. The second duty control is performed until the actual current value Ia becomes smaller than the second predetermined current value I3. When it is determined in step 23 that the switching of the driving state of the vehicle is completed, the power supply to the motor 31 is performed in step 24. To stop.

As described above, according to the present embodiment, the rush current flowing immediately after the start of energization to the motor 31 can be suppressed to near the first predetermined current value I1 by the first duty control. A large current does not flow, the motor 31 does not generate excessive heat, and the motor 31 can operate reliably and responsiveness is ensured.

In the above-described embodiment, the first duty control of the current is performed in accordance with the magnitude of the current flowing through the motor 31 immediately after the start of energization of the motor 31, and the first duty control is performed when the stability of the current is detected. After the termination, the current is always supplied until the first predetermined current value I1 is reached.
As another method, the time during which the inrush current flows may be experimentally obtained in advance, and the first duty control may be terminated when the time has reached.

Although the embodiments of the present invention have been described above, the present invention is not intended to be limited to the above-described embodiments, but may be any other forms according to the gist of the present invention. There may be.

[0027]

According to the present invention, since the current value is stabilized around a predetermined current value, a large current such as an inrush current flowing immediately after the start of energization does not flow through the motor, and the motor does not generate excessive heat. Since a current value near a predetermined current value flows through the motor, the motor can be reliably operated,
Responsiveness of the motor is also ensured.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a drive switching device according to an embodiment of the present invention.

FIG. 2 is a sectional view of a drive switching actuator according to the embodiment.

FIG. 3 is a view as viewed from A in FIG. 2;

FIG. 4 is a circuit diagram of a control mechanism according to the present embodiment.

FIG. 5 is a time chart according to the drive switching actuator in the present embodiment.

FIG. 6 is a time chart according to the drive switching actuator in the present embodiment.

FIG. 7 is a time chart according to the drive switching actuator in the present embodiment.

FIG. 8 is a time chart showing a duty ratio and an actual current Ia at times t0 to t0 ′.

FIG. 9 is a flowchart relating to energization of a motor 31;

[Explanation of symbols]

10 Drive switching device 11
Rear wheel drive shaft 12 ・ ・ ・ Front wheel drive shaft 13 ・ ・ ・
Center differential unit 14 First shaft 15
2nd shaft 16 ・ ・ ・ 2WD-4WD switching shift fork 17 ・ ・ ・ Center differential lock shift fork 19 ・ ・ ・ Silent chain 23 ・ ・ ・ Reducer 24 ・ ・ ・
Input shaft 30 Actuator for drive switching device 31
Motor (electric motor) 32 ... output mechanism 33 ...
Rod (output member) 34: cycloid gear (reverse rotation inhibiting mechanism) 35: rotation absorbing mechanism 36: limit switch (detection mechanism) 37:
Housing 40 ・ ・ ・ Control mechanism 50 ・ ・ ・
Manual switch

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Noriaki Nonaka 2-1-1 Asahi-cho, Kariya-shi, Aichi F-term (reference) in Aisin Seiki Co., Ltd. 5H001 AA03 AB10 AC04 AC06 AD05 5H570 AA21 BB09 DD01 FF01 GG01 HA01 HA04 HA05 HA08 HB16 JJ03 JJ18 LL02 MM02 MM05 PP02

Claims (5)

[Claims] 1. An energization control method performed immediately after energization of an electric motor driven in accordance with an energization current is performed, wherein an actual current value flowing through the electric motor is compared with a predetermined current value. When the actual current value is larger than the predetermined current value, the duty ratio of energization / de-energization to the motor is reduced by a predetermined ratio, and the actual current value is smaller than the predetermined current value and the duty ratio is increased by a predetermined ratio. If the duty ratio does not exceed 100%, the duty ratio of energizing / de-energizing the motor is increased by a predetermined ratio, and the actual current value is smaller than the predetermined current value and the duty ratio is increased by a predetermined ratio. When the duty ratio of the motor exceeds 100%, the energizing / non-energizing duty ratio of the motor is set to 100%. Method. 2. The energization control method according to claim 1, wherein a control cycle of the energization control is shorter than a time from immediately after the start of energization to the motor until the current is stabilized. Control method. 3. The method according to claim 1, wherein the predetermined current value is set to a value larger than a minimum current value required for driving the motor and smaller than a maximum value of an inrush current flowing immediately after the start of energization to the motor. The method for controlling the energization of a motor according to claim 1. 4. The energization control in the energization control method according to claim 1, wherein the duty ratio when the actual current value is smaller than the predetermined current value and the duty ratio is increased by a predetermined ratio immediately after the start of energization to the electric motor. An energization control method for an electric motor, which is performed until the amount exceeds 100%. 5. The energization control in the energization control method according to claim 1, wherein the energization control is performed immediately after the energization of the electric motor is started until a predetermined time period is assumed in which the current is assumed to be stable and in a steady state. To control the energization of the electric motor.