JP3373291B2 - Motor overload detection method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting an overload of a motor, and more particularly, to a method of detecting a motor overload based on a predetermined number of pulses generated as the motor rotates. And a motor overload detection method that determines motor overload based on a change in cycle. 2. Description of the Related Art For example, there is an automobile equipped with a device for opening and closing an opening and closing body such as a power window and a sunroof by a motor. When such an opening / closing member is opened / closed, if the motor is overloaded due to some external factors such as icing, it is necessary to detect the overload and stop the motor. Conventionally, in detecting a motor overload in the above-described apparatus, the cycle of the motor is constantly monitored, and an overload can be detected based on an abnormal change in the cycle. The period can be calculated by measuring a predetermined number of generation times of the pulses generated with the rotation of the motor and converting the period into a period for each pulse generation. For example, the cycle at the time of this detection is t _n ,
The period at the time of the next detection is t _{n + 1,} and their ratio t _n / t
By comparing _{n + 1} with a preset discrimination value k, it is possible to detect that the fluctuation of the cycle is too large (t _n / t _{n + 1} > = k) and determine the overload state. However, in the above-mentioned conventional method, when the motor is locked due to an abnormal overload, the motor cannot rotate, so that the next pulse is not generated and the overload is not generated. There was a problem that could not be detected. SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, a main object of the present invention is to reliably detect an overload even when the motor locks and stops. It is an object of the present invention to provide a motor overload detection method which can be performed. According to the present invention, there is provided a map in which a coefficient which increases as a cycle of a motor becomes longer is set by linear approximation at every cycle interval. Having data, a step of calculating the cycle of the motor based on pulses continuously generated with the rotation of the motor,
Calculating a timer interrupt time by multiplying the previous cycle by the coefficient read from the map data corresponding to the previous cycle of the motor at the time of the previous generation of the pulse, and This is attained by providing a motor overload detecting method, wherein if the next generation of the pulse does not occur before the timer interrupt time elapses, it is determined that the motor is overloaded. In the DC motor, the relationship between the rotation speed N and the output shaft torque T has a constant slope regardless of the magnitude of the motor applied voltage on a graph with the horizontal axis and the vertical axis. (See FIG. 5). As shown in FIG. 5, when the load increases by ΔT due to the overload, the rotation speed decreases by the constant rotation speed ΔN regardless of the voltage, so that the load increase can be determined using the rotation speed difference ΔN. . That is, as the ΔN or more rotational speed N _{n + 1} of the current than the rotational speed N _n of preceding drops, because that would increase in torque corresponding to the rotational speed difference ΔN has occurred, it will reach an overload level A rotation speed difference ΔN corresponding to the torque increase is set, and the current rotation speed N _{n + 1} is equal to or greater than a value obtained by subtracting the rotation speed difference ΔN from the previous rotation speed N _n (N _{n + 1} > = N _n − If ΔN), it is normal, and if it is outside the normal range, it can be determined that an overload has occurred. [0008] The equation using the rotational speed difference is expressed by a period t (mse
Expressed using c), t _{n + 1} > = 60000t _n / (60000−ΔN × t _n ) (1) The above equation, the linear approximation for each certain cycle range, the [0009] _{t n + 1> = k m} × t n. The coefficient k _m of the above equation, is stored in advance as map data for each arbitrary period range, by reading the map data in accordance with the measured period, it may perform determination of overload by periodically. Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows a main part of a control circuit of a power window for an automobile to which the present invention is applied. In FIG. 1, a controller 1 of a power window control circuit includes a forward / reverse drive circuit 3 for a motor 2 for opening / closing a window glass as an opening / closing body (not shown), a manual open switch 4 and an automatic open switch 5. And a CPU 8 as a control means for appropriately operating the drive circuit 3 in accordance with the operation of each of the manual close switch 6 and the automatic close switch 7. Further, in the controller 1, a positive voltage supplied from a vehicle-mounted battery (not shown) is supplied to the CPU 8 and the drive circuit 3 via each power supply terminal V. Each of the switches 4 to 7 is a normally open contact,
One end of the manual open switch 4 is grounded, the other end is connected to the input terminal I2 of the CPU 8, and
Input terminal I of CPU 8 via automatic open switch 5
1 connected. The power supply terminal V is connected between the automatic open switch 5 and the terminal I1 and between the manual open switch 4 and the terminal I2 via the resistors R1 and R2, respectively. The manual close switch 6 and the automatic close switch 7 and the resistors R4 and R3 connected to the power supply terminal V are connected to the input terminals I4 and I3 of the CPU 8 in the same configuration as described above. The manual open switch 4 is also activated when the automatic open switch 5 is operated. When the manual open switch 4 is operated, a low level signal is applied only to the input terminal I2. Entered,
When the automatic open switch 5 is operated, a low level signal is input to both input terminals I1 and I2. In this way, the operation states of the switches 4 and 5 can be determined. Note that the same applies to the signal input states to both input terminals I3 and I4 in the case of each of the close switches 6 and 7. The forward drive output terminal O1 of the CPU 8 is connected to one end of a solenoid of the relay RL1 via an amplifier AP1, and the other end of the solenoid is connected to a power supply terminal V. The normally open terminal of the contact of the relay RL1 is connected to the power supply terminal V, the normally closed terminal is grounded, and the common terminal is connected to one end of the motor 2. The reverse rotation drive terminal O2 of the CPU 8 is connected to the amplifier AP2 and the relay RL2 having the same configuration as described above, and the common terminal of the relay RL2 is connected to the other end of the motor 2. The motor 2 has, for example, a pair of Hall elements 9a and 9b for generating a pulse wave in synchronization with its rotation.
Is provided. These Hall elements 9a and 9b generate pulse waves having a predetermined rotation angle difference and a predetermined width with the rotation of the motor 2 as shown in FIG. I have. From the frequency dividing circuit 10, a pulse wave is generated at the rise and fall of each pulse wave from both Hall elements 9a and 9b, and is inputted to the input terminal I5 of the CPU 8. The period of the motor 2 can be measured by measuring, for example, a predetermined number of generation times of the pulse wave from the frequency dividing circuit 10. Also, by counting the number of waves of this pulse, it is possible to know where the position of the window glass is. Next, an operation routine in the CPU 8 will be described below with reference to a flowchart of FIG. 3 showing a closing operation. First, in step ST1, it reads the rising signal of the rotation pulses generated with the rotation of the motor 2, to measure the period t _n as the preceding period of the motor 2 in the next step ST2. At step ST3, the order to obtain the determination value for overload judgment reads those corresponding to the period t _n which is the measurement from the coefficient k _m, which is stored as a map data in advance in the memory of the CPU 8. The illustrated with reference to FIG. 4 a method of setting the coefficient k _m as described above. In FIG. 4, the horizontal axis is the previous cycle (t _n ), and the vertical axis is the current predicted cycle (t _{n + 1} ). The above equation (1) is converted to t _{n + 1} = k × t _{n in} consideration of a reduction in processing time.
When represented by / (k−t _n ), the curve becomes as shown by the imaginary line in the figure. Actually, it is used within a gentle range of the curve. Coefficient k _m of the linear approximation _{t n + 1 = k m ×} t n
Is [0018] _{k m = k / (k-} t n) ... , and therefore equation (2), linear approximation is [0019] _{t n + 1 = [k /} (k-t m)] × t _n ... can be converted into equation (3). Here, t _m is a boundary of the period range, which can be appropriately determined by design.
t _m = t ₁ , t ₂ , t ₃ ,... The coefficient km is _calculated based on the above equation (2) for each of the predetermined period ranges defined by t _m = t ₁ , t ₂ , t ₃ ,..., And linear approximation can be performed for each of the period ranges. you create a map data that defines the coefficient k _m. In the map data created on the basis of FIG. 4, for example, in the during period until t ₁ and the coefficient k _m and k _1, t ₁ ~t is located between the _second coefficient k _m a k ₂
And then, as k ₃ coefficient k _m In the between t ₂ ~t _3, fitted to a linear approximation, used to overload discriminant. [0020] After reading the coefficient k _m at step ST3, the step ST4, sets the timer interrupt signal having a timer interrupt time ti multiplied by the period t _n to the coefficient k _m. Then, in step ST5, the interrupt signal generation timing after the elapse of the timer interrupt time ti from the previous pulse generation and the time before and after the next pulse generation timing are compared. That is, if the pulse generation is earlier than the interrupt signal generation, the load fluctuation is small and within the allowable range. In that case, the cycle t _n based on the current pulse generation is determined in step ST6. ₊₁ is measured, and in step ST7, the cycle t _{n + 1} is set as the previous cycle t _{n in the} next cycle, and the process returns to step ST3. If the current pulse has not been generated when the interrupt signal is generated, it means that the load fluctuation has reached the overload level, and in that case, the process proceeds to step ST8.
In step ST7, the motor 2 is preferably stopped. However, for example, it is conceivable that something has been caught in the event of an overload when the opening / closing body is closed. You may do it. In this way, the measured cycle is compared with the previous cycle measured immediately before (for example, one pulse before) and the discrimination value obtained by multiplying the coefficient read out from the previously created map data based on the previous cycle. To determine the overload. As described above, even when the motor applied voltage (battery voltage in this embodiment) fluctuates, the rate of change between the number of revolutions and the shaft torque is constant. map as represented, represents represents expression in the period by the multiplier k _m × t _n of the cycle change amount Δt coefficients and the previous period by linear approximation for every arbitrary cycle range, the coefficient k _m for each cycle range The overload is determined by setting as data, and the overload can be determined without being affected by the voltage fluctuation.
Even in the case where the motor 2 is stopped due to the overload and the next pulse does not occur, the overload can be determined after the timer interrupt time expires, so that the overload can always be determined. The above process counts the pulse wave and determines whether or not something has been caught by the closing operation of the window glass when the window glass is not near the fully open position, but when the window glass is near the fully open position. Step S
By increasing the constant B of T3 by a predetermined amount with respect to the previous processing, it is possible to ensure that the window glass is fully opened. As described above, according to the present invention, the non-linearity is obtained when the discriminant of the torque change is converted into a formula using the period, but the formula is linearly approximated for each certain period range. Is set as map data, the coefficient is read out according to the measurement cycle, and the discrimination is performed by a linear approximation formula. Therefore, the overload discrimination can be performed by the cycle measurement. Since it is not necessary, the calculation process can be simplified, and overload detection that is not affected by fluctuations in the motor applied voltage can be performed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a main part control circuit diagram of an automotive power window to which the present invention is applied. FIG. 2 is an explanatory diagram showing a procedure for measuring a pulse wave accompanying rotation of a motor. FIG. 3 is a flowchart of a motor overload detection to which the present invention is applied. FIG. 4 is a diagram for explaining a linear approximation formula when performing overload determination based on a cycle. FIG. 5 is a diagram showing the relationship between the number of rotations of a motor and torque. [Description of Signs] 1 Controller 2 Motor 3 Drive circuit 4 Manual open switch 5 Automatic open switch 6 Manual close switch 7 Automatic close switch 8 CPU 9a / 9b Hall element 10 Divider circuit

──────────────────────────────────────────────────続 き Continuing on the front page (72) Katsuya Shigematsu 1-2681-2 Hirosawacho, Kiryu-shi, Gunma Inside Mitsuba Electric Works, Ltd. (72) Inventor Masashi Shimada 1-2681 Hirosawacho, Kiryu-shi, Gunma (56) References JP-A-7-143792 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02P 3/08

Claims (1)

(57) [Claim 1] Map data in which a coefficient that increases as the cycle of a motor becomes longer is set by linear approximation at an arbitrary cycle interval, and map data is set for the rotation of the motor. A step of calculating the cycle of the motor based on the continuously generated pulses, and multiplying the previous cycle by the coefficient read from the map data corresponding to the previous cycle of the motor when the pulse last occurred. Calculating a timer interrupt time, and determining that an overload has occurred if the next occurrence of the pulse has not occurred before the timer interrupt time has elapsed since the previous occurrence of the pulse. Motor overload detection method.