WO2007007794A1

WO2007007794A1 - Motor control method and motor control system

Info

Publication number: WO2007007794A1
Application number: PCT/JP2006/313873
Authority: WO
Inventors: Toshiyuki Amagasa
Original assignee: Mitsuba Corporation
Priority date: 2005-07-13
Filing date: 2006-07-12
Publication date: 2007-01-18
Also published as: JP4878598B2; DE112006001839T5; JPWO2007007794A1

Abstract

In a motor undergoing PWM control, rotational frequency f of the motor is detected (S1), and then a PID control Duty value is calculated (S2) and a Max.Duty value is set (S3). Acceleration/deceleration state of the motor is judged from variation in rotation speed (S4), and if the motor is under acceleration state, the Max.Duty value is multiplied by an acceleration correction coefficient Kp to obtain a corrected Max.Duty value (S6). Otherwise, the Max.Duty value is used as it is (S5). When the control Duty value exceeds the Max.Duty value, the output Duty is limited to the Max.Duty value (S9). When the control Duty value is equal to or smaller than the Max.Duty value, the control Duty value is used, as it is, as the output Duty value (S8). During acceleration of the motor, the Max.Duty value is corrected to a larger value thus securing a torque required during acceleration.

Description

Specification

Motor control method and motor control system

Technical field

TECHNICAL FIELD [0001] The present invention relates to a method for controlling a motor used in a wiper system of an automobile, and more particularly

The present invention relates to a motor control method and a motor control system capable of improving the acceleration characteristics of a motor while suppressing the amount of current during overload and motor lock.

Background art

Conventionally, in an automobile wiper system or the like, an electromagnetic motor provided with a field magnet (permanent magnet) is frequently used as a drive source. Such motors must be able to withstand use in a low temperature range of about −40 ° C. according to the usage conditions of automobiles, etc., and operate without problems even in such low temperature environments. In other words, it is required to start without any problems even at low-temperature forces such as when the motor is cold, and to operate the wiper etc. in the same way as at normal temperature.

[0003] However, when the motor is placed in a low temperature environment, the resistance of the copper wire used as the armature winding becomes small, and current easily flows through the winding. For this reason, when the motor is overloaded at low temperatures and the motor is locked, the winding current (lock current) becomes extremely large, which causes the field magnet to become demagnetized. For example, when the motor is locked in the low temperature zone immediately after the motor is operated and the swinging wiper arm comes into contact with an obstacle such as snow in the reverse position, the lock current increases and the field magnet increases. May be demagnetized. In particular, in a ferrite-based magnet, the coercive force of the magnet itself tends to decrease at low temperatures, so demagnetization in a low temperature environment becomes more prominent. When the magnet is demagnetized, not only the motor output decreases, but there is a possibility that desired motor characteristics cannot be obtained even when the ambient temperature returns to room temperature.

[0004] For this reason, in a motor that may be used in a low-temperature environment, it is necessary to use a magnet with a high coercive force that prevents demagnetization of the magnet, or to increase the thickness of the magnet. is there. However, high coercivity magnets have the problem of increasing the cost of the product as the price increases. In addition, increase the thickness of the magnet! ], There is a problem that the motor becomes larger and the weight increases accordingly. Also, when the winding current increases, the mode Even in a motor drive circuit, it is necessary to use an expensive switching element with a large current capacity according to the lock current of the motor. In particular, when driving a high-torque, high-rotation motor, a switching element with a larger current capacity is required, which increases the cost of the element and increases the product cost.

Patent Document 1: Japanese Patent Laid-Open No. 7-39062

Patent Document 2: Japanese Patent Laid-Open No. 11-122703

Patent Document 3: Japanese Patent Application No. 2004-327299

Disclosure of the invention

Problems to be solved by the invention

[0005] Therefore, as a countermeasure against magnet demagnetization at low temperatures, a control form in which the current value flowing to the motor from the motor rotation speed and PWM duty is predicted and the current during overload is appropriately limited can be considered. . However, the control method that simply sets the upper limit value of the current based on the motor speed and PWM duty and suppresses the motor current is limited even when the load is slightly high and acceleration is required. In some cases, the PWM duty may be kept below the specified value. In such a case, there was a problem that the desired acceleration performance could not be obtained even though the load was medium enough not to reach the locked state, and the motor rotation speed did not increase easily.

An object of the present invention is to provide a motor control method and a motor control system capable of improving the acceleration characteristics of a motor while suppressing the amount of current at the time of overload or motor lock. Means for solving the problem

[0007] The motor control method of the present invention applies a voltage having a pulse waveform having an ON period and an OFF period, and effectively changes the applied voltage by changing the ON / OFF ratio of the voltage. A control method for a motor to be changed, wherein an allowable duty value indicating a ratio of an ON period of the voltage that can be applied to the motor when the motor is locked is set based on an allowable current amount of the motor. When the rotation speed of the motor becomes equal to or less than a predetermined value, the ratio of the applied voltage during the ON period is suppressed to the allowable duty value or less, while when the motor is accelerating, the allowable duty is The value is corrected to a duty value for acceleration set to a higher value than the allowable duty value.

[0008] In the present invention, in a motor in which so-called PWM control is executed, the rotational speed is increased. In view of the motor characteristics that force and current values decrease, the allowable duty value is corrected to a higher value during motor acceleration. Therefore, the torque required for acceleration is ensured by correcting the duty value while suppressing the current value during overload to lock using the allowable duty value.

In another motor control method of the present invention, a voltage having a pulse-like waveform having an ON period and an OFF period is applied, and the applied voltage is effectively reduced by changing the ON / OFF ratio of the voltage. A control method for a motor to be changed, which is based on an allowable current amount of the motor, and an allowable duty value indicating a 0 N period ratio of the voltage that can be applied to the motor when the motor is locked. Is set to a different value between when the motor is accelerating and when the motor is decelerating. A duty value is selected as appropriate, and a ratio of the ON period of the applied voltage is suppressed to be equal to or less than the selected allowable duty value. In this case, the allowable duty value when the motor is accelerating may be set higher than the allowable duty value when the motor is decelerating.

[0010] In the present invention, in a motor in which so-called PWM control is executed, the allowable duty value is set differently during acceleration and deceleration, and the allowable duty value is appropriately set based on the acceleration / deceleration state of the motor. Since it is selected, the allowable duty value that matches the state at the time of motor deceleration or acceleration can be selected. For this reason, the torque required during acceleration is ensured while suppressing the current value during overload to lock.

[0011] The motor control system of the present invention applies a voltage having a pulse waveform having an ON period and an OFF period, and effectively changes the applied voltage by changing the ON / OFF ratio of the voltage. A motor control system that controls the drive of the motor by changing the rotation detection means that outputs a signal as the motor rotates, and the motor is locked based on the allowable current amount of the motor. Storage means for storing an allowable duty value indicating the ON-period ratio of the voltage that can be applied to the motor, and the allowable duty value based on a signal output from the rotation detecting means. Allowable duty value calculating means for calculating; motor driving state detecting means for detecting the acceleration / deceleration status of the motor based on a signal output from the rotation detecting means; and the motor being accelerated by the motor driving state detecting means If detected, Yes and allowable Duty value correcting means for correcting the allowable Duty value It is characterized by doing.

In the present invention, in the motor control system in which so-called PWM control is executed, when the motor is accelerating, the allowable duty value is corrected by the allowable duty value correction means. The torque required for acceleration is ensured by correcting the duty value while suppressing the current value during overload to lock.

[0013] In the motor control system, when the motor is accelerating by the allowable duty value correction means, the allowable duty value is multiplied by a predetermined correction coefficient to increase the allowable duty value to a higher value. You may make it correct | amend. In the motor control system, the storage means stores an acceleration duty value used when the motor is accelerating and a deceleration duty value used when the motor is decelerating, When the motor is accelerating by an allowable duty value correction means, the allowable duty value may be corrected using the acceleration duty value.

The invention's effect

[0014] According to the motor control method of the present invention, in a motor for which so-called PWM control is executed, an allowable duty value indicating a PWM duty value that can be applied when the motor is locked is set based on the allowable current amount of the motor. When the motor speed falls below the specified value, the PWM duty value is suppressed to the allowable duty value or less.On the other hand, when the motor is accelerating, the allowable duty value is higher than the allowable duty value. The duty value for acceleration is set to, so the torque required for acceleration is secured by correcting the duty value during acceleration while suppressing the current value during overload to lock using the allowable duty value. It becomes possible to do. Accordingly, it is possible to improve the acceleration performance of the motor while reducing the cost of the magnet and the switching element and reducing the motor weight by suppressing the demagnetization.

[0015] According to another motor control method of the present invention, in a motor in which so-called PWM control is executed, an allowable duty value indicating a PWM duty value that can be applied when the motor is locked based on the allowable current amount of the motor is set to the motor. When the motor is accelerating and decelerating, the motor is set to a different value, and when the motor speed falls below the specified value, the allowable duty value is selected appropriately based on the motor acceleration / deceleration status, and the PWM Since the duty value is suppressed below the selected allowable duty value, the motor is driven with the allowable duty value that matches the state during motor deceleration or acceleration. It is possible to secure the necessary torque during acceleration using the allowable duty value for acceleration while suppressing the current value during overload to lock using the allowable duty value for deceleration. Accordingly, it is possible to improve the acceleration performance of the motor while reducing the cost of the magnet and the switching element and reducing the motor weight by suppressing the demagnetization.

[0016] According to the motor control system of the present invention, in the motor control system in which so-called PWM control is executed, the rotation detection means and the PWM that is set based on the allowable current amount of the motor and can be applied when the motor is locked. The storage means for storing the allowable duty value indicating the duty value, the allowable duty value calculating means for calculating the allowable duty value based on the output signal from the rotation detecting means, and the motor based on the output signal of the rotation detecting means force The motor drive state detection means that detects the acceleration / deceleration status of the motor and the allowable duty value correction means that corrects the allowable duty value when the motor is accelerating are provided, so that the allowable duty value correction is performed when the motor is accelerating. The allowable duty value can be corrected by means, and the torque required for acceleration can be secured while suppressing the current value during overload to lock using the allowable duty value. Therefore, by suppressing demagnetization, it is possible to improve the acceleration performance of the motor while reducing the cost of the magnet and the switching element and reducing the weight of the motor.

Brief Description of Drawings

FIG. 1 is a block diagram showing a configuration of a motor control system to which a motor control method according to an embodiment of the present invention is applied.

FIG. 2 is a flowchart showing a processing procedure of a motor control method according to an embodiment of the present invention.

FIG. 3 is a flowchart showing a Max. Duty calculation processing procedure in step S 3 of FIG.

FIG. 4 is a graph showing the relationship between E and DO when a = 124 and b = 4.7 in Equation 2.

[Fig. 5] Map showing Max. Duty value (duty value for deceleration) corresponding to deceleration.

[Fig. 6] Map showing the correction value (duty value for acceleration) by multiplying Max.Duty value corresponding to deceleration by Kp = 1.2.

[Fig.7] Process procedure of motor control method when obtaining current value and rotational force Max.Duty value It is a flowchart to show.

Explanation of symbols

[0018] 1 motor

2 Battery

3 CPU

4 Rotation detection means

5 Motor drive device

6 Voltage sensor

7 Temperature sensor

8 ROM

9 Control map

10 H bridge circuit

11 Control duty calculation means

12 Max.Duty calculation means (allowable duty value calculation means)

13 Motor status detection means

14 Max.Duty correction means (allowable duty value correction means)

15 Duty value output means

DO tolerance duty value

Kf Frequency adjustment factor

Kp acceleration correction factor

Ε Power supply voltage

a Fixed duty value

b Duty characteristic coefficient

c Limit start frequency

d Lock judgment frequency

f Motor rotation frequency

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Figure 1 shows an illustration of the present invention. It is a block diagram which shows the structure of the motor control system to which the motor control method which is an Example is applied. The motor 1 shown in FIG. 1 is used as a drive source for an automobile wiper system, supplied with power from the battery 2, and driven and controlled by the CPU 3. The motor 1 is driven forward and backward by an H-bridge circuit 10 using four FETs. The motor 1 is provided with a rotation detection means 4 using a Hall IC, and the speed (number of rotations) can be detected by the frequency of the pulse signal (motor rotation frequency) output from the rotation detection means 4. Talk to you.

[0020] CPU 3 performs PID control of motor 1 based on the calculated rotation speed of the pulse signal force. For motor 1, PWM control (Pulse Width Modulation) that controls the drive by changing the ONZOFF ratio of the pulse width of the applied voltage is executed, and the applied voltage is set by turning the power supply voltage ON / OFF. Is effectively changed to control the amount of current supplied to motor 1. During PWM control, CPU 3 sets the duty ratio (Duty) of the ON period of the pulse voltage and sends a control signal to motor drive device 5. Upon receiving this control signal, the motor drive device 5 applies a set duty pulse voltage to the motor 1, whereby the rotational speed of the motor 1 is appropriately controlled.

A voltage sensor 6 is connected to the battery 2. The voltage sensor 6 detects the power supply voltage applied to the motor 1 and sends the value to the CPU 3. Further, inside the motor 1, a temperature sensor 7 for detecting the temperature in the motor, particularly the temperature of the armature winding is provided. The temperature sensor 7 is also connected to the CPU 3, and the temperature in the motor 1 detected by the temperature sensor 7 is sent to the CPU 3 as motor temperature information. CPU 3 constantly monitors the temperature in motor 1 using this temperature information. The CPU 3 controls the motor drive device 5 based on the power supply voltage, the motor rotation frequency, the motor temperature information, and the like so that the current value does not exceed a predetermined value when the motor is locked. At this time, the CPU 3 refers to the control map 9 and the like stored in the ROM (storage means) 8 to limit the maximum value of the PWM duty of the motor 1 and suppress the motor supply current.

[0022] In CPU 3, control duty calculation means 11, Max. Duty calculation means (allowable duty value calculation means) 12, motor state detection means 13, Max. Duty correction means (allowable duty value correction means) 14, Duty Value output means 15 is provided. Control duty calculation means 11 includes battery voltage and motor Based on the rotation frequency, motor temperature information, etc., the current state of the motor 1 is detected, and a control duty value suitable for the load state is calculated. The motor 1 is normally PID controlled by the duty value obtained by the control duty calculation means 11.

[0023] As described above, the motor 1 is normally driven and controlled by the control duty value by the PID control. However, in this system, to prevent demagnetization due to the lock current, the PWM duty that can be applied at the time of locking is allowed. Value (Max.Duty) is set. The Max. Duty calculation means 12 sets the allowable duty value based on the battery voltage, the motor rotation frequency, and the motor temperature information. The allowable duty value is stored in the ROM 8 as the control map 9, and the Max. Duty calculation means 12 calculates the allowable duty value with reference to the control map 9 based on each detected value.

Motor state detection means 13 detects the acceleration / deceleration state of motor 1. The motor state detection means 13 receives the motor rotation frequency from the rotation detection means 4 and compares the previous detection value with the current detection value to determine the acceleration / deceleration state of the motor. ing. For example, when the current rotational speed is faster (higher rotational frequency) than immediately before, the motor state detection means 13 determines that the motor 1 is in an acceleration state.

[0025] The Max. Duty correction unit 14 appropriately corrects the allowable duty value calculated by the Max. Duty calculation unit 12 according to the acceleration / deceleration state of the motor. As described above, simply setting the duty upper limit value to suppress the motor current amount! /, The desired acceleration performance cannot be obtained with the control method. Therefore, in this system, considering the characteristics of the motor that the current value decreases as the rotation speed increases, the allowable duty value mentioned above is corrected to be slightly higher during motor acceleration. When the motor state detection means 13 determines that the motor is in an acceleration state, the Max. Duty correction means 14 creates a correction duty value by multiplying the value of the control map 9 by a predetermined coefficient.

[0026] In this way, the control duty value calculated by the control duty calculation means 11, the allowable duty value calculated by the Max. Duty calculation means 12, and the correction duty corrected by the Max. Duty correction means 14 The y value is sent from the duty value output means 15 as a control signal. This control signal is sent to the motor drive device 5, and the motor 1 is driven according to the duty value set by the CPU 3.

FIG. 2 is a flowchart showing a processing procedure for motor drive control according to an embodiment of the present invention. The control shown in FIG. 2 is executed by the system shown in FIG. 1. When the ignition key of the automobile is turned on, the process shown in FIG. 2 is started. [0028] As shown in FIG. 2, first, in step S1, the motor rotation frequency f is detected. As the motor rotation frequency f, the frequency of the output signal of the rotation detection means 4 is used. The output cannula signal is output along with the rotation of the motor 1, so that the current rotation speed and rotation state of the motor 1 can be grasped. The rotation detection means 4 outputs 12 pulses per motor rotation. For example, when the output pulse is 200 Hz, the motor rotation speed is about lOOOrpm. Since the output frequency and the motor speed have a one-to-one relationship, in this embodiment, the frequency of the output pulse is regarded as the motor speed, and the motor rotation frequency f is directly used. Drive control is performed.

Next, based on the motor rotation speed detected in S 1, the control duty calculation means 11 calculates a control duty value (Duty (l)) based on the PID control method. After calculating Duty (l), the process proceeds to step S 3 and the Max.Duty calculation means 12 calculates the Max.Duty value. FIG. 3 is a flowchart showing the Max. Duty calculation processing procedure in step S3. First, the ROM 8 force also acquires the lock judgment frequency d (step S 11). The lock determination frequency d is a numerical value that determines how many Hz the motor rotation frequency is determined as “lock state”. For example, if the lock judgment frequency is set to d = 300, motor 1 is judged to be locked at 300Hz. The value of d is appropriately set within a range of about 0 to 400 depending on the motor characteristics and the load level.

Next, the power supply voltage E is detected in step S12. The power supply voltage E is detected by the voltage sensor 6, and the voltage currently applied to the motor 1 is detected by the notch 2. The higher the power supply voltage, the smaller the motor duty corresponding to a certain allowable current value. For this reason, even in this control method, the voltage value of battery 2 is detected and used as one of the control parameters. Note that the lock determination frequency d and the power supply voltage E are not limited to the order described above, which may be set first and detected.

[0031] After detecting d and E, d and f are compared. If f is greater than or equal to d, that is, if the motor rotation frequency is greater than or equal to the lock judgment frequency, calculate the maximum duty value (Max.Duty) of motor 1 based on the following formula! In step S15, set the Max.Duty value and exit the routine.

[0032] Max.Duty = DO * Kf (Formula 1) [0033] In the above equation, DO is an allowable duty value, and Kf is a frequency adjustment coefficient. DO is a duty value that can be applied to motor 1 from the viewpoint of the demagnetization of the magnet and the current capacity of the switching element when the motor 1 is in a locked state (f = 0). DO is a value that depends on power supply voltage E, and CPU3 uses the power supply voltage E acquired in step S12 as a parameter to obtain DO using the following equation.

[0034] DO = a-bE (Formula 2)

[0035] In Equation 2, a and b are fixed values set in advance for each motor (or for each motor model, etc.), a is a fixed duty value for which the allowable current capacity at the time of locking is also required, and b depends on the motor characteristics Duty characteristic coefficient determined by These values are stored in the ROM 8 in advance. FIG. 4 is a graph showing the relationship between E and DO when a = 124 and b = 4.7 in Equation 2.

[0036] The fixed duty value a is determined by how many amperes the lock current is to be fixed, and is an intercept value of DO expressed by a linear function with E as a variable. The value of a increases as the allowable current amount increases, and the value of a decreases as the allowable current amount decreases. The duty characteristic coefficient b is determined based on the characteristics of each motor according to the motor's shore resistance, etc., and is the DO slope expressed by a linear function with E as a variable. As described above, when the power supply voltage E is high, it is necessary to keep the allowable duty value DO low. Here, b is a positive value, and the graph showing DO goes to the right.

In this way, the allowable duty value DO is set according to the characteristics of each motor based on the maximum allowable lock current value, and varies depending on the magnitude of the power supply voltage E. In this case, the allowable maximum block current value is set so that the demagnetization of the magnet is kept within the allowable range.When lock is detected, the duty value is forcibly set in accordance with the power supply voltage E. If suppressed to the following, excessive current at the time of low temperature lock can be prevented, and demagnetization of the magnet is suppressed.

On the other hand, in such a control mode, even when the motor rotational speed is gradually reduced due to overload and the winding current value is increased, the duty value is not forcibly set unless the motor stops. Therefore, in the process of step S3, the allowable duty value is corrected according to the motor rotation frequency f, and the duty value allowed for the motor rotation speed at that time is individually set to prevent overcurrent according to the motor status. Measures are being implemented. The DO adjustment coefficient for this is Kf in Equation 1. [0039] That is, the frequency adjustment coefficient Kf is a coefficient that depends on the motor rotation frequency f. The current motor rotation frequency f is an adjustment value for determining how many Max.Duty values should be based on DO. is there. Therefore, the Max. Duty value obtained from Equation 1 is also a kind of allowable duty value. Here, the value obtained by correcting the allowable duty value DO according to the motor rotation frequency is used. CPU3 uses the motor rotation frequency f and the lock determination frequency d acquired previously to determine Kf by the following equation.

[0040] Kf = l + (f-d) / c (Formula 3)

[0041] c in Equation 3 is a limit start frequency, which is a fixed value that determines how many Hz the motor rotational frequency reaches when the duty value starts to be limited, and is stored in the ROM 8 in advance. As the value of c, for example, when the lock determination frequency is d = 300, c = 420 (Hz) is set correspondingly. F−d becomes 0 when the motor rotation frequency f reaches the lock judgment frequency d, and Kf = l at this time. At this time, the allowable duty value DO is X 1, that is, DO itself, and when f reaches d, the Max.Duty value becomes DO even if f = 0 is not satisfied.

[0042] Fig. 5 is an example of a control map 9 showing the Max. Duty value (duty value for deceleration) when a = 124, b = 4.7, c = 420, and d = 300. Stored. Here, d is 300 (determined to be locked when f = 300 Hz). When the motor decelerates and the frequency reaches 300 Hz, DO set as shown in Fig. 4 is applied. In other words, Equation 1 is expressed as Max.Duty = DO * (l + (f-300) Z420): (Equation 4) in the map of Fig. 5, and Max.Duty = DO at f = 300Hz. For example, if d = 400 is set, the table in FIG. 5 is read so that DO is applied when f = 400.

[0043] DO takes the value shown in FIG. 4 according to the power supply voltage E. For example, when the power supply voltage E exceeds 13.5V and is 14.0V or less, DO = 58%. In other words, in Fig. 5, the value for E = 14.0 (V) or less and the frequency of 300 (Hz) or less is 58%. This means that if motor 1 locks when E is greater than 13.5V and less than 14.0V, the maximum duty is reduced to 58%.

Further, as shown in FIG. 5, when the power supply voltage is 13.5V to 14.0V as described above, Max.Duty = 72% at f = 400Hz and Max.Duty = 86% at f = 500Hz. Value is limited. At f = 600Hz, the calculated value of Max.Dutv exceeds 100%. In this case, a duty value of 100% is possible. Therefore, there is no duty restriction. Further, when the calculated value of Max.Duty is 100% or more as shown by the shaded portion in FIG. 5, Max.Duty = 100 (%) regardless of the calculated value.

[0045] As described above, when the Max. Duty value is limited based on Equation 1, the maximum Duty value is gradually limited as the rotational speed of the motor 1 decreases. When the motor is locked, the maximum Duty value is suppressed to DO, which is a value that takes into account the current capacity of the switching element of the magnet. On the other hand, if the motor rotation frequency f is less than the lock determination frequency d in step S13, the process proceeds to step S16. In this case, since it is determined that the motor 1 is already in the locked state, the Max.Duty value is set to the above-mentioned DO, and the process proceeds to step S15 to exit the routine. As a result, even if the motor 1 is locked immediately after starting, the Max. Duty value is kept at D 0.

[0046] After the Max. Duty value is calculated in step S3 as described above, the process proceeds to step S4, and the motor state detection means 13 detects the motor drive state. Here, the acceleration / deceleration state of the motor is determined from the change in the rotation speed, and the motor rotation speed (f) in the previous processing (previous processing) and the latest (current processing) motor rotation speed are determined. To be compared. If the rotation speed at the time of the previous process is greater than or equal to this time, it is determined that the motor 1 is at the same rotation speed or is in a decelerating state, and the process proceeds to step S5 and uses the Max. Proceed to S7. On the other hand, if the rotational speed at the time of the previous processing is smaller than this time, it is determined that the motor 1 is in an acceleration state, the process proceeds to step S6, and Max.Duty correction means 14 calculates the Max calculated in step S3. .Duty value is multiplied by acceleration correction factor Kp.

[0047] In step S6, for example, Max.Duty value is multiplied by Κρ = 1.2, and the value is increased to 1.2 times that in normal control. Fig. 6 is a map that shows the correction value (duty value for acceleration) by multiplying the Max. Duty value for deceleration (Fig. 5) by 1.2. In ROM8, such a correction map for acceleration is stored in advance, and in step S6, the Max.Duty value is corrected with reference to it. In the map of FIG. 6, for example, in the case of 13.5V to 14.0V, Duty value is limited to Max.Duty = 70% at f = 300Hz or less and Max.Duty = 86% at f = 400Hz. Above f = 500Hz, Max.Duty value is 100%. In this case, if the rotational speed increases due to acceleration, the current value decreases relatively, so even if the allowable duty value is set higher by that amount, inconveniences such as magnet demagnetization do not occur. [0048] As described above, in this control method, the Max. Duty value is set higher during motor acceleration than during deceleration. As described above, with the deceleration response map as shown in Fig. 5, the load is slightly higher and the rotational speed is reduced! In some cases, the duty value was suppressed more than necessary, and the desired acceleration characteristics were not obtained. On the other hand, in the control method according to the present invention, the acceleration / deceleration state of the motor is detected and the Max.Duty value is corrected to be higher during acceleration. Therefore, it is necessary for acceleration while suppressing the current value during overload to lock. Torque can be secured. For this reason, it is possible to improve acceleration performance while reducing magnet and switching element costs and reducing motor weight by suppressing demagnetization.

[0049] Set the Max.Duty value in Steps S5, 6 'After correction, proceed to Step S7 and compare the control duty value (Duty (l)) obtained in Step S2 with the Max.Duty value . If Duty (l) is less than Max.Duty value, it is not necessary to suppress the Duty value.Proceed to Step S8, set Duty (1) as the output Duty value, and output the Duty value in Step S10. Means 15 force is also output to the motor drive 5 and the routine is exited. On the other hand, if Duty (l) exceeds the Max.Duty value, if this Duty (l) is output as it is, the current value may become excessive and demagnetization may occur. Therefore, proceed to step S9, set the Max. Duty value as the output duty value, and suppress the duty value. Then, go to step S10, output the Max. Duty value, and exit the routine. During deceleration, the PWM duty is held constant (Max. Duty value), and the motor output is stopped when the specified time has elapsed. As a result, excessive current at the time of motor lock is suppressed, and demagnetization of the magnet is prevented. On the other hand, during acceleration, the Max. Duty value is corrected to a higher value, and acceleration performance is improved.

[0050] It goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.

For example, in the above-described embodiment, the control form in which the Max.Duty value is calculated using Equation 1 is shown, but the method for calculating the Max.Duty value is not limited to this. The Max.Duty value may be obtained. FIG. 7 is a flowchart showing the processing procedure in that case. Here, instead of the process of step S3 of FIG. 2, the Max.Duty value is calculated in step S34 using the rotation speed and current value detected in steps S31 and 33. Other processing is the same as in Fig. 2. The current value can be detected by using a current sensor, shunt resistor, rotation It can be detected by various methods such as the relationship between number and duty.

In the above-described embodiment, the control form in which both maps of the duty value for deceleration and the duty value for acceleration are stored in the ROM 8 and appropriately referred to according to the acceleration / deceleration situation is shown. ROM 8 may store only a map of the duty value for deceleration and multiply that value by Kp during acceleration. Of course, the duty value for deceleration may also be calculated on the spot using Equation 1, which is not a map. Furthermore, considering the motor temperature, the Max.Duty value may be corrected based on the motor temperature information obtained from the temperature sensor 7. For example, D1 = 100— (100—Max.D uty) * T (T :) The Max.Duty value may be corrected in a form such as (temperature) and multiplied by Kp to obtain the Max.Duty value during acceleration.

[0052] Power! In the above embodiment, the present invention is applied to a motor for a wiper system of an automobile. However, the application target of the present invention is not limited to this, and a motor for driving a window or a door, or It can be applied to various on-board motors and motors used in pumps used in cold regions. Further, the present invention can also be applied to control of a motor that rotates only in one direction of force, which is shown as a motor 1 that is driven forward and backward by a drive circuit 10. It should be noted that the numerical values given in the above embodiment and the maps of FIGS. 4 and 6 are merely examples, and it goes without saying that the present invention is not limited to these numerical values.

Claims

The scope of the claims

[1] A motor control method in which a voltage having a pulse-like waveform having an ON period and an OFF period is applied, and the applied voltage is effectively changed by changing the ON / OFF ratio of the voltage. ,

Based on the allowable current amount of the motor, an allowable duty value indicating a ratio of the ON period of the voltage that can be applied to the motor when the motor is locked is set, and the rotational speed of the motor is a predetermined value When the ratio is less than or equal to the ON duty ratio of the applied voltage to the allowable duty value or less,

When the motor is accelerating, the allowable duty value is corrected to an acceleration duty value that is set to a value that is higher than the allowable duty value.

[2] Apply a voltage having a pulse waveform with an ON period and an OFF period, and

A motor control method that effectively changes the applied voltage by changing the N / OFF ratio.

Based on the allowable current amount of the motor, an allowable duty value indicating a ratio of the ON period of the voltage that can be applied to the motor when the motor is in a locked state, when the motor is accelerating and decelerating. Set to a different value in the case of

When the number of rotations of the motor becomes a predetermined value or less, the allowable duty value is appropriately selected based on the acceleration / deceleration state of the motor, and the ratio of the applied voltage during the ON period is selected or less. The motor control method characterized by restraining to.

[3] The motor control method according to claim 2, wherein the allowable duty value when the motor is accelerating is set higher than the allowable duty value when the motor is decelerating. A motor control method.

[4] A voltage having a pulse-like waveform having an ON period and an OFF period is applied, and 0% of the voltage is applied.

A motor control system that performs motor drive control by effectively changing the applied voltage by changing the N / OFF ratio,

Rotation detection means for outputting a signal along with the rotation of the motor;

Stores an allowable duty value that is set based on the allowable current amount of the motor and indicates the ratio of the ON period of the voltage that can be applied to the motor when the motor is locked. Storage means

The rotation detection means force An allowable duty value calculation means for calculating the allowable duty value based on an output signal;

Motor drive state detection means for detecting the acceleration / deceleration status of the motor based on a signal output from the rotation detection means;

A motor control system comprising: an allowable duty value correcting means for correcting the allowable duty value when the motor driving state detecting means detects that the motor is accelerating.

[5] The motor control system according to claim 5, wherein when the motor is accelerating, the allowable duty value correction means multiplies the allowable duty value by a predetermined correction coefficient to calculate the allowable duty value. A motor control system characterized by correcting the value to a higher value.

[6] In the motor control system according to claim 5, the storage means is an acceleration duty value used when the motor is accelerating and a deceleration time value used when the motor is decelerating. A motor control system comprising: a duty value; and the allowable duty value correction means corrects the allowable duty value using the acceleration duty value when the motor is accelerating.