Electric motor control device

Abstract

This document discloses an example of an electric motor control device that can stop the electric motor at a desired timing even if the motor current fluctuates due to torque ripple or the like. [Solution] The electric motor control device 1 stops applying voltage to the electric motor 12 when the extracted current Id extracted by the bandpass filter unit 3 exceeds a threshold value. As a result, the electric motor control device 1 determines whether or not to stop applying voltage to the electric motor 12 based on the current from which disturbance elements have been removed from the motor current. Consequently, it is possible to suppress the electric motor 12 stopping at a timing different from the originally intended timing, and the electric motor 12 not stopping at the originally intended timing.

Description

Technical Field

[0001] The present disclosure relates to an electric motor control device that controls the operation of an electric motor that drives a movable part provided in a vehicle seat.

Background Art

[0002] For example, in the electric motor control device described in Patent Document 1, a load acting on an opening / closing body is detected using a current value flowing through the electric motor (hereinafter also referred to as motor current), and when the detected load becomes equal to or greater than a predetermined threshold value, the electric motor is stopped.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The load acting on the movable part of the vehicle seat changes along with changes such as when the seated person changes their seating posture by themselves or when the movable part of the vehicle seat is displaced. Therefore, if the invention described in Patent Document 1 is applied to a vehicle seat, there is a high possibility that the electric motor will stop at a timing different from the originally intended timing.

[0005] The movable part of the vehicle seat refers to a member that has a larger mass than the opening / closing body such as a seat cushion, a seat back, or an ottoman, and on which a load caused by the mass of the seated person acts.

[0006] Furthermore, because the motor current fluctuates due to torque ripple (torque fluctuation) generated as the rotor of the electric motor rotates, if the invention described in Patent Document 1 were applied to a vehicle seat, there is a high risk that the electric motor would stop at a timing different from the originally intended timing.

[0007] This disclosure provides an example of an electric motor control device in view of the above points. [Means for solving the problem]

[0008] An electric motor control device that controls the operation of an electric motor (12) that drives a movable part provided in a vehicle seat preferably comprises at least one of the following constituent elements.

[0009] In other words, the constituent elements are a drive unit (2) that applies a voltage to the electric motor (12) to drive the electric motor (12), a bandpass filter unit (3) that extracts a current in a predetermined frequency band from the current flowing through the electric motor (12), and a stop control unit (4) that stops applying voltage to the electric motor (12) when the value of the current extracted by the bandpass filter unit (3) exceeds a predetermined value.

[0010] As a result, the electric motor control device determines whether or not to stop applying voltage to the electric motor (12) based on the current from which disturbance elements have been removed from the current flowing through the electric motor (12).

[0011] Consequently, it is possible to prevent the electric motor (12) from stopping at a timing different from the originally intended timing, and from failing to stop at the originally intended timing.

[0012] The electric motor control device may have, for example, the following configuration. In other words, in a vehicle seat in which an ottoman (11) that supports the lower limbs of a seated person is driven by the electric motor (12), it is desirable that the upper limit cutoff frequency of the frequency band is approximately 2 Hz, and the lower limit cutoff frequency of the said frequency band is approximately 0.1 Hz.

[0013] Furthermore, it is desirable that the bandpass filter section (3) be implemented by the execution of software by the electronic control unit (6), which is an electronic control unit (6) capable of running software. This makes it possible to address the bandpass filter issue solely by changing the software, without requiring any additional hardware.

[0014] Consequently, by utilizing existing hardware, it is possible to suppress the electric motor (12) stopping at a timing different from the originally intended timing, and the electric motor 12 not stopping at the originally intended timing.

[0015] Incidentally, the symbols in each of the parentheses above are just examples showing the correspondence with the specific configurations etc. described in the embodiments described later, and this disclosure is not limited to the specific configurations etc. indicated by the symbols in the parentheses above. [Brief explanation of the drawing]

[0016] [Figure 1] This figure shows an electric motor control device according to the first embodiment. [Figure 2] This is a graph showing the extracted current, etc. [Figure 3] This is a flowchart showing the operation of the electric motor control device according to the first embodiment. [Modes for carrying out the invention]

[0017] The following "Embodiments of the Invention" are examples of embodiments that fall within the technical scope of this disclosure. In other words, the features defining the invention as described in the claims are not limited to the specific configurations and structures shown in the embodiments below.

[0018] This embodiment is an example in which the electric motor control device according to the present disclosure is applied to a seat (hereinafter referred to as a vehicle seat) mounted on a vehicle or the like. At least one member or part described with a reference sign is provided, unless otherwise specified such as "one".

[0019] That is, when there is no specification such as "one", two or more of the members may be provided. The electric motor control device shown in the present disclosure includes at least one of the components such as the members or parts described with reference signs, and at least one of the illustrated structural parts.

[0020] (First Embodiment) <1. Outline of Electric Motor Control Device> As shown in FIG. 1, the electric motor control device (hereinafter referred to as the control device) 1 according to the present embodiment is applied to the vehicle seat 10. That is, the control device 1 controls the operation of the electric motor 12 that drives the movable part provided on the vehicle seat 10.

[0021] The movable part provided on the vehicle seat 10 refers to a mechanism or member that obtains a driving force from the electric motor 12 and operates. The movable part according to the present embodiment is the ottoman 11. The ottoman 11 is disposed on the front end side of the seat cushion 13 and supports the lower limbs (particularly, the calves) of the seated person.

[0022] The ottoman 11 is a movable part that can be displaced between a support position and a storage position. The support position is a position where the lower limbs of the seated person can be supported. The storage position is a position where it is stored below the seat cushion 13.

[0023] The electric motor 12 generates a driving force for displacing the ottoman 11. The control device 1 is an electronic control type controller that can control the operation of the electric motor 12, that is, the rotation and stop of the electric motor 12.

[0024] <2. Details of Control Device> As shown in Figure 1, the control device 1 includes at least a drive unit 2, a bandpass filter unit 3, a stop control unit 4, and a current detection unit 5. The drive unit 2 is a drive circuit that applies a voltage to the electric motor 12 to drive the electric motor 12.

[0025] In this embodiment, the drive unit 2 applies a DC voltage to the electric motor 12. Specifically, the drive unit 2 applies a predetermined constant voltage to the electric motor 12, either continuously or with a predetermined duty cycle (in this embodiment, PWM control).

[0026] Incidentally, in this embodiment, the drive unit 2 gradually increases the duty cycle until a predetermined time has elapsed from the start of voltage application, and after that time has elapsed, drives the electric motor 12 with a duty cycle corresponding to the constant voltage.

[0027] The bandpass filter unit 3 extracts current within a predetermined frequency band from the current flowing through the electric motor 12. The stop control unit 4 stops applying voltage to the electric motor 12 when the value of the current extracted by the bandpass filter unit 3 exceeds a predetermined threshold.

[0028] The "current flowing through the electric motor 12" is detected by the current detection unit 5. The current detection unit 5 transmits the detected current value as a digital signal to the electronic control unit 6. Hereinafter, the current detected by the current detection unit 5 will be referred to as the "motor current".

[0029] In this embodiment, the bandpass filter unit 3 and the stop control unit 4 are composed of an electronic control unit 6. That is, the electronic control unit 6 is composed of a computer having a CPU, ROM, RAM, etc.

[0030] Then, the functions of the bandpass filter unit 3 and the stop control unit 4 are realized when the software (program) pre-stored in a non-volatile memory unit such as ROM is executed by the electronic control unit 6 (CPU).

[0031] The bandpass filter unit 3 according to this embodiment extracts the current in the above frequency band (hereinafter referred to as extracted current Id) using the following method. In other words, the bandpass filter unit 3 extracts current I1 from the motor current using a first low-pass filter, and then extracts current I2 from the same motor current using a second low-pass filter, after which it subtracts current I2 from current I1 (see Figure 2).

[0032] In other words, Id = (I1 - I2). The cutoff frequency of the first low-pass filter is the upper limit cutoff frequency of the above frequency band. The cutoff frequency of the second low-pass filter is the lower limit cutoff frequency of the above frequency band.

[0033] In other words, the electronic control unit 6 executes software to extract currents I1 and I2 from the motor current, and then calculates and extracts the extracted current Id. In this embodiment, the upper limit cutoff frequency is approximately 2 Hz, and the lower limit cutoff frequency is approximately 0.1 Hz.

[0034] Figure 3 is a flowchart showing the operation of the electronic control unit 6, that is, the operations performed by the bandpass filter unit 3 and the stop control unit 4. When power is supplied to the electric motor 12, the electronic control unit 6 calculates and extracts the extracted current Id according to the method described above (S1).

[0035] Next, the electronic control unit 6 determines whether the extracted current Id is above a threshold (S3). If it is determined that the extracted current Id is not above a threshold (S3:NO), the electronic control unit 6 executes S1 again.

[0036] On the other hand, if it is determined that the extracted current Id is above a threshold (S3:YES), the electronic control unit 6 stops supplying power to the electric motor 12 (S5). This interrupts the drive control of the electric motor 12.

[0037] Incidentally, in this embodiment, the case in which the extracted current Id is determined to be above a threshold is when a large load is generated on the electric motor 12, for example, when "a part of the lower limb supported by the ottoman 11 is caught between the lower part of the front seat and the ottoman 11."

[0038] <3. Features of the control device according to this embodiment> In the control device 1 according to this embodiment, the application of voltage to the electric motor 12 is stopped when the extracted current Id extracted by the bandpass filter unit 3 exceeds a threshold value. Thus, the control device 1 determines whether or not to stop the application of voltage to the electric motor 12 based on the motor current from which disturbance elements have been removed, i.e., the extracted current Id.

[0039] Consequently, it is possible to suppress the electric motor 12 from stopping at a timing different from the originally intended timing, and from failing to stop at the originally intended timing.

[0040] Furthermore, in the control device 1, the bandpass filter section 3 is realized by the execution of software in the electronic control unit 6. This makes it possible to implement the bandpass filter by changing only the software, without having to install hardware components.

[0041] Furthermore, by utilizing existing hardware, it is possible to suppress the electric motor 12 stopping at a timing different from the originally intended timing, and the electric motor 12 not stopping at the originally intended timing.

[0042] (Other embodiments) In the above-described embodiment, the bandpass filter unit 3 and the stop control unit 4 were implemented by software execution in the electronic control unit 6. However, this disclosure is not limited thereto. That is, the disclosure may, for example, describe a configuration in which the bandpass filter unit is made up of hardware.

[0043] In the bandpass filter unit 3 of the above embodiment, the extracted current Id was obtained by subtracting current I2 from current I1. However, the disclosure is not limited thereto. That is, the disclosure may, for example, extract current I1 from the motor current using a low-pass filter, and then extract a current from the extracted current I1 using a high-pass filter to obtain the extracted current Id.

[0044] In the above-described embodiment, an ottoman 11 was used as the movable part, and the upper cutoff frequency was approximately 2 Hz, while the lower cutoff frequency was approximately 0.1 Hz. However, the present disclosure is not limited thereto.

[0045] The above-described embodiment was a description of a control device using an ottoman 11 as an example of a movable part. However, this disclosure is not limited thereto. That is, the disclosure may also describe a control device in which a sliding device, seat back or tilt part is used as a movable part, for example.

[0046] In the above-described embodiment, the electric motor 12 was driven by PWM control. However, this disclosure is not limited to this. That is, the disclosure may, for example, simply involve applying voltage to the electric motor 12.

[0047] In the embodiments described above, the vehicle seat according to this disclosure was applied to a vehicle. However, the application of the invention disclosed herein is not limited to this. That is, the disclosure can be applied, for example, to seats used in vehicles such as railway cars, ships and aircraft, as well as to stationary seats used in theaters, homes, etc.

[0048] Furthermore, this disclosure is not limited to the embodiments described above, but is sufficient to be consistent with the intent of the disclosures described in the embodiments described above. Therefore, it may be a configuration in which at least two of the embodiments described above are combined, or a configuration in which any of the illustrated components or components described with reference numerals in the embodiments described above are omitted. [Explanation of Symbols]

[0049] 1… Electric motor control device 2… Drive unit 3… Bandpass filter section 4… Stop control unit 5… Current detection unit 6… Electronic control unit 10… Vehicle seats 11… Ottoman 12… Electric motor

Claims

1. In an electric motor control device that controls the operation of an electric motor that drives a movable part provided in a vehicle seat, A drive unit that applies a voltage to the electric motor to drive the electric motor, A bandpass filter unit that extracts current in a predetermined frequency band from the current flowing through the electric motor, A stop control unit that stops applying voltage to the electric motor when the value of the current extracted by the bandpass filter unit exceeds a predetermined value, and An electric motor control device equipped with the following features.

2. An electric motor control device, which controls the operation of the electric motor, is applied to a vehicle seat equipped with an ottoman that supports the lower limbs of a seated person and an electric motor that generates the driving force to displace the ottoman. A drive unit that applies a voltage to the electric motor to drive the electric motor, A bandpass filter unit that extracts current in a predetermined frequency band from the current flowing through the electric motor, The system includes a stop control unit that stops applying voltage to the electric motor when the value of the current extracted by the bandpass filter unit exceeds a predetermined value, An electric motor control device wherein the upper limit cutoff frequency of the frequency band is approximately 2 Hz, and the lower limit cutoff frequency of the frequency band is approximately 0.1 Hz.

3. Equipped with an electronically controlled unit capable of running software, The electric motor control device according to claim 1 or 2, wherein the bandpass filter section is realized by software being executed in the electronic control unit.

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