Ripple detection device and seat device

Abstract

Provided are a ripple-detecting device and a seat device with which a linear relational formula for deriving, on the basis of ripple current and voltage across motor terminals, the frequency of the ripple current is utilized to enable optimal control of variable-filter passband in accordance with a drive state of the motor, and to enable detection of ripple pulses with high accuracy.　A ripple-detecting device (100) is provided with: a ripple-current detecting unit (112, 24) that detects ripple current generated when a motor (23) is driven; a motor-voltage detecting unit (111) that detects voltage across the motor terminals; a variable filter (130) that passes components in a predetermined frequency band of the ripple current detected by the ripple-current detecting unit; and a frequency-adjusting unit (161) that, utilizing a linear relational formula for deriving a ripple current frequency on the basis of the ripple current detected by the ripple-current detecting unit and the voltage across the motor terminals detected by the motor-voltage detecting unit, adjusts the predetermined frequency band of the variable filter so as to include the derived ripple current frequency.

Description

[Technical Field]

[0001] The present disclosure relates to a ripple detection device and a seat device. [Background technology]

[0002] A conventional ripple detection device for detecting ripples superimposed on a motor waveform includes an AD converter that oversamples analog data of the waveform at a frequency equal to or higher than the ripple frequency and converts it into digital data, a digital filter with variable filter characteristics to which the digital data is input, and filter characteristic control means that changes the filter coefficient of the digital filter to optimize the filter characteristics for detecting the ripple. The low-pass filter of the digital filter has a linear phase characteristic or an approximately linear phase characteristic and suppresses phase distortion (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-207236 Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional ripple detection devices do not focus on the linearity between the ripple current and the voltage between the terminals of the motor, and the frequency of the ripple current.

[0005] Therefore, the object of the present invention is to provide a ripple detection device and a seat device that can optimally control the passband of a variable filter according to the driving state of the motor using a linear relationship equation that derives the frequency of the ripple current based on the ripple current and the voltage between the motor terminals, and that can detect ripple pulses with high accuracy. [Means for solving the problem]

[0006] A ripple detection device according to an embodiment of the present disclosure includes a ripple current detection unit that detects a ripple current generated when a motor is driven, a motor voltage detection unit that detects a terminal-to-terminal voltage of the motor, a variable filter that passes components of a predetermined frequency band of the ripple current detected by the ripple current detection unit, and a frequency adjustment unit that uses a linear relationship equation to derive the frequency of the ripple current based on the ripple current detected by the ripple current detection unit and the terminal-to-terminal voltage of the motor detected by the motor voltage detection unit, and adjusts the predetermined frequency band of the variable filter to include the frequency of the derived ripple current. [Effects of the Invention]

[0007] By using a linear relationship equation that derives the frequency of the ripple current based on the ripple current and the voltage between the motor terminals, and optimally controlling the passband of the variable filter according to the driving state of the motor, it is possible to provide a ripple detection device and a seat device that can detect ripple pulses with high accuracy. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating an example of a seat device mounted on a vehicle. [Figure 2] FIG. 1 is a diagram illustrating an example of a circuit configuration of a ripple detection device. [Figure 3] FIG. 10 is a diagram showing experimental results showing the relationship between ripple current and frequency of the ripple current. [Figure 4] FIG. 10 is a diagram showing experimental results showing the relationship between ripple current, the frequency of the ripple current, and the environmental temperature. [Figure 5A] FIG. 10 is a diagram illustrating an example of a detection result of a ripple pulse. [Figure 5B] FIG. 10 is a diagram illustrating an example of a detection result of a ripple pulse. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment to which the ripple detection device and the seat device of the present disclosure are applied will be described.

[0010] <Embodiment 1> FIG. 1 is a diagram showing an example of a seat device 10 mounted on a vehicle 1. The seat device 10 includes a seat 20, a ripple detection device 100, and a drive control unit 50. The seat 20 has a seat portion 21, a backrest portion 22, and motors 23A and 23B. The motor 23A is a DC (Direct Current) motor that moves the seat portion 21 back and forth or up and down, and the motor 23B is a DC motor that changes the angle of the backrest portion 22. The voltage and current between the terminals of the motors 23A and 23B are input to the ripple detection device 100.

[0011] Ripple detection device 100 detects ripple currents of motors 23A and 23B and outputs the detected ripple currents to drive control unit 50. Drive control unit 50 is connected to a switch (not shown) that adjusts seat 21 or backrest 22, and when the switch is operated, it detects the rotation angle of motor 23A or 23B based on the ripple current detected by ripple detection device 100, and controls the movement of seat 21 forward and backward or up and down, or the angle of backrest 22.

[0012] In the following description, motor 23A and motor 23B will be referred to as motor 23 without distinction. Motor 23 is driven to adjust the position, angle, etc. of seat 20. Adjustment of the position, angle, etc. of seat 20 is not limited to adjustment of seat portion 21 forward / backward or up / down, and adjustment of the angle of backrest portion 22, but may also include adjustment of other directions, angles, etc.

[0013] <Circuit configuration of ripple detection device 100> Fig. 2 is a diagram showing an example of the circuit configuration of the ripple detection device 100. In addition to the ripple detection device 100, Fig. 2 shows a motor 23, a resistor 24, and a drive control unit 50. The resistor 24 is connected to one of the two terminals of the motor 23 and is a sensing resistor used to detect the current of the motor 23.

[0014] The ripple detection device 100 includes a voltage detection unit 111, a current detection unit 112, a filter 121, a filter 122, a variable filter 130, a filter 140, a ripple pulse generation unit 150, an MCU (Micro Controller) 160, and a temperature sensor 170. The MCU 160 has a frequency adjustment unit 161 and a memory 162. The filter 122, the variable filter 130, and the filter 140 configure a high-order filter.

[0015] The voltage detection unit 111 is an example of a motor voltage detection unit. The current detection unit 112 and the resistor 24 are an example of a ripple current detection unit. The filter 121 is an example of a first filter. The filter 122 is an example of a second filter.

[0016] The voltage detection unit 111 is connected to two terminals of the motor 23, detects the voltage between the terminals of the motor 23, and outputs it to the filter 121. As the voltage detection unit 111, for example, a voltage detection circuit configured with an amplifier can be used.

[0017] The current detection unit 112 receives the voltage across the resistor 24 as a voltage representing the current (ripple current) of the motor 23, and outputs the voltage representing the ripple current to the MCU 160 and the filter 122.

[0018] The filter 121 is a low pass filter (LPF). The filter 121 is connected to the output side of the voltage detection unit 111, and removes high frequency noise and the like contained in the terminal voltage of the motor 23 input from the voltage detection unit 111 before outputting the voltage. The terminal voltage output by the filter 121 is converted into a digital value of the terminal voltage by an A / D (Analog to Digital) converter (not shown), and is input to the MCU 160.

[0019] The filter 122 is an LPF that removes high-frequency noise and the like contained in the voltage input from the current detection unit 112 and outputs the voltage to the variable filter 130 .

[0020] The variable filter 130 is a band pass filter (BPF) whose pass band is adjusted by a frequency adjustment unit 161 of the MCU 160. The pass band of the variable filter 130 is an example of a predetermined frequency band. The variable filter 130 outputs the pass band components of the voltage that has passed through the filter 122 to the filter 140.

[0021] The filter 140 is a high pass filter (HPF). The filter 140 removes low frequency noise and the like contained in the voltage that has passed through the variable filter 130, and outputs the result to the ripple pulse generating section 150.

[0022] The ripple pulse generating unit 150 performs a ripple generating process to generate (detect) ripples contained in the voltage representing the current input from the filter 140, converts the ripples into pulses (ripple pulses), and outputs them to the MCU 160. The ripple pulses are pulses that represent the current value of the ripple current.

[0023] The MCU 160 is realized by a computer including a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), an input / output interface, an internal bus, etc. The MCU 160 has a frequency adjustment unit 161 and a memory 162, and performs processing for detecting a ripple current. As an example of the processing for detecting a ripple current, a voltage representing a ripple current input from the current detection unit 112 is calculated as a current value of the ripple current using a predetermined voltage / current conversion table stored in the memory 162. The frequency adjustment unit 161 represents the functions of a program executed by the MCU 160 as functional blocks. The memory 162 represents the memory of the MCU 160 as a functional block.

[0024] The frequency adjusting unit 161 uses a linear relational expression to derive the frequency of the ripple current based on the current value of the ripple current detected by the ripple current detecting unit (current detecting unit 112 and resistor 24) and the voltage value indicating the inter-terminal voltage detected by the voltage detecting unit 111 and passed through the filter 121, and adjusts the pass band of the variable filter 130 so as to include the derived frequency of the ripple current. The linear relational expression to derive the frequency of the ripple current based on the current value of the ripple current and the voltage value of the inter-terminal voltage will be described later with reference to FIGS. 3 and 4.

[0025] The memory 162 stores programs and data used by the MCU 160 in processing to detect a ripple current, data generated by the processing, etc. The memory 162 stores linear relational expressions and other data used by the frequency adjustment unit 161 to adjust the pass band of the tunable filter 130.

[0026] The temperature sensor 170 is a temperature sensor that detects the environmental temperature of the motor 23. The temperature sensor 170 outputs data indicating the detected temperature to the MCU 160.

[0027] <Relationship between ripple current and ripple current frequency> Figure 3 shows the experimental results showing the relationship between ripple current and its frequency. In Figure 3, the horizontal axis represents ripple current Ir, and the vertical axis represents ripple current frequency fr. The ripple current frequency fr is the frequency of the ripple pulse contained in the ripple current.

[0028] When a person is seated in seat 20, the load on motor 23 used to adjust seat 20 is greater than when no one is seated, resulting in a greater amount of fluctuation in ripple current Ir. Fluctuations in ripple current Ir cause fluctuations in the torque output by motor 23, which in turn causes fluctuations in the frequency fr of the ripple current. For this reason, the ripple current Ir and the frequency fr of the ripple current fluctuate between when a person is seated in seat 20 and when no one is seated.

[0029] The experimental results shown in Fig. 3 were obtained by creating a pseudo state where a person is sitting on the seat 20 by placing a weight on the seat 20 and measuring the ripple current Ir and the frequency fr of the ripple current while changing the weight of the weight. Note that the state where no person is sitting on the seat 20 is the state where no weight is placed on the seat 20.

[0030] Fig. 3 shows the ripple current Ir and the frequency fr of the ripple current (black squares (■)) when there is a seated person with the inter-terminal voltage applied to the motor 23 being V1, and the ripple current Ir and the frequency fr of the ripple current (white squares (□)) when there is no seated person with the inter-terminal voltage applied to the motor 23 being V1. Also, Fig. 3 shows the ripple current Ir and the frequency fr of the ripple current (black triangles (▲)) when there is a seated person with the inter-terminal voltage applied to the motor 23 being V2, and the ripple current Ir and the frequency fr of the ripple current (white triangles (△)) when there is no seated person with the inter-terminal voltage applied to the motor 23 being V2. Further, Fig. 3 shows the ripple current Ir and the frequency fr of the ripple current (black circles (●)) when there is a seated person with the inter-terminal voltage applied to the motor 23 being V3, and the ripple current Ir and the frequency fr of the ripple current (white circles (○)) when there is no seated person with the inter-terminal voltage applied to the motor 23 being V3. Note that the inter-terminal voltage of the motor 23 is V1 < V2 < V3, and as an example, V1 = 9V, V2 = 13.5V, and V3 = 16V.

[0031] In Fig. 3, it can be seen that the characteristics when there is a seated person with the inter-terminal voltage being V1 are distributed along the straight line (1), and the characteristics when there is no seated person with the inter-terminal voltage being V1 are also distributed along the straight line (1). The straight line (1) is a straight line obtained by fitting using the least squares method as an example. When the inter-terminal voltage is V1, in the case of having a seated person, compared to the case of having no seated person, the ripple current Ir is larger, the variation amount of the ripple current Ir is also larger, and the frequency fr of the ripple current is lower.

[0032] It can also be seen that the characteristics when the terminal voltage is V2 and there is a person seated are distributed along line (2), and the characteristics when the terminal voltage is V2 and there is no person seated are also distributed along line (2). Line (2) is an example of a line obtained by fitting using the least squares method. When the terminal voltage is V2 and there is a person seated, the ripple current Ir is larger, the amount of fluctuation in the ripple current Ir is also larger, and the ripple current frequency fr is lower compared to when there is no person seated. This is the same trend as when the terminal voltage is V1.

[0033] It can also be seen that the characteristics when the terminal voltage is V3 and there is a person seated are distributed along line (3), and the characteristics when the terminal voltage is V3 and there is no person seated are also distributed along line (3). Line (3) is an example of a line obtained by fitting using the least squares method. When the terminal voltage is V3 and there is a person seated, the ripple current Ir is larger, the amount of fluctuation in the ripple current Ir is also larger, and the ripple current frequency fr is lower than when there is no person seated. This is the same trend as when the terminal voltage is V1 and V2. Note that the method of obtaining lines (1), (2), and (3) is not limited to the least squares method, and other methods may be used.

[0034] As described above, it was found that there is a linear relationship between the ripple current Ir and the ripple current frequency fr when the inter-terminal voltage is constant in Figure 3. It was also found that the slopes of lines (1), (2), and (3) (the change in the ripple current frequency fr Δfr (Δfr / ΔIr) relative to the change in the ripple current Ir ΔIr) are substantially the same, although the intercept values ​​of the ripple current frequency fr are different.

[0035] The linear relationship between the ripple current Ir and the frequency fr of the ripple current can be expressed by the following equation (1).

[0036] fr=α×Ir+β×Vm (1) where α is the ratio of the change Δfr in the ripple current frequency fr to the change ΔIr in the ripple current Ir, i.e., α=Δfr / ΔIr, and β is the ratio of the change Δfr in the ripple current frequency fr to the change ΔVm in the terminal voltage Vm of the motor 23, i.e., β=Δfr / ΔVm.

[0037] As shown in equation (1), the frequency fr of the ripple current can be derived based on the ripple current Ir and the terminal voltage Vm. That is, equation (1) is an example of a linear relational equation that derives the frequency fr of the ripple current based on the ripple current Ir and the terminal voltage Vm. In equation (1), β×Vm, which is the frequency fr of the ripple current, can be expressed as a value that includes the terminal voltage Vm as a parameter, so equation (1) can derive the frequency fr of the ripple current corresponding to various terminal voltages Vm.

[0038] As an example, α is -200<α<-100, and more preferably -160<α<-120. As an example, the optimal value of α is -140, which is the ratio of the change in ripple current frequency to the change in ripple current, as seen from line (2) in Figure 3. Furthermore, β is 50<β<250, and more preferably 100<β<150. As an example, the optimal value of β is 130, which is the ratio of the change in ripple current frequency to the change in terminal voltage, as seen from lines (1) and (3) in Figure 3. However, because α and β vary depending on the specific motor resistance value and motor power generation coefficient of motor 23, the optimal values ​​differ for each motor used.

[0039] Furthermore, as described above, it was found that there is a linear relationship between the ripple current Ir and the frequency fr of the ripple current, and that the ripple current Ir and the frequency fr of the ripple current vary depending on the weight of the weight.

[0040] Here, we will consider a comparative ripple detection device that does not include variable filter 130, and in which the ripple current that has passed through filter 122 is directly input to filter 140. When the frequency fr of the ripple current fluctuates as shown in Fig. 3, in the comparative ripple detection device that does not include variable filter 130, a high-order bandpass filter realized by filter 122, which is an LPF, and filter 140, which is an HPF, is unable to completely remove noise when the frequency fr of the ripple current fluctuates, which can result in missing ripple pulses (missed ripple detection) or false detection of ripple pulses, and the ripple pulses may not be detected accurately.

[0041] Therefore, in the ripple detection device 100 of the embodiment, the passband of the variable filter 130 is adjusted according to the frequency fr of the ripple current calculated based on the formula (1), thereby tracking the frequency fr of the ripple current and removing noise, suppressing missing ripple pulses (missed ripple detection) and false detection of ripple pulses, and detecting ripple pulses with high accuracy.

[0042] For this reason, the frequency adjustment unit 161 may substitute the value of the ripple current calculated based on the ripple pulse and the inter-terminal voltage Vm into equation (1) to calculate the frequency fr of the ripple current, and adjust the pass band of the variable filter 130 so that the frequency fr of the ripple current is included in the pass band of the variable filter 130. The frequency adjustment unit 161 outputs a variable clock corresponding to the calculated frequency fr of the ripple current to the variable filter 130 to adjust the pass band. The frequency fr of the ripple current is adjusted to be included in the pass band of the variable filter 130 so that it is suited to the driving state of the motor 23. Data representing equation (1) may be stored in memory 162, and the frequency adjustment unit 161 may read the data representing equation (1) from the memory 162 and use it in calculations.

[0043] <Relationship between ripple current, ripple current frequency, and environmental temperature> Figure 4 shows the experimental results showing the relationship between ripple current, ripple current frequency, and environmental temperature. Figure 4 shows the relationship between ripple current and ripple current frequency, similar to Figure 3, obtained while changing the environmental temperature. Figures 4(A) to 4(C) show lines (1) to (3), similar to Figure 3. Lines (1) to (3) are obtained by fitting when the inter-terminal voltages are V1, V2, and V3 and there is a seated person. As an example, V1 = 9V, V2 = 13.5V, and V3 = 16V.

[0044] 4A shows the relationship between the ripple current and the frequency of the ripple current obtained when the ambient temperature is low. The ambient temperature is the temperature in the environment where the ripple detection device 100 is installed, and may be considered as the room temperature of the vehicle 1.

[0045] A low temperature is a temperature lower than 25°C, which is an example of a reference temperature, and one example is -20°C. Figure 4(B) shows the relationship between the ripple current and the frequency of the ripple current obtained when the ambient temperature is the reference temperature. An example of the reference temperature is 25°C. 25°C is an example of a predetermined reference temperature. Figure 4(C) shows the relationship between the ripple current and the frequency of the ripple current obtained when the ambient temperature is high. A high temperature is a temperature higher than 25°C, which is an example of a reference temperature, and one example is 80°C.

[0046] As shown in Figures 4(A) to 4(C), for all ambient temperatures, the ripple current Ir and the ripple current frequency fr exhibited a linear relationship, as in Figure 3. Furthermore, when the relationship between the slope α in equation (1) and temperature T was determined, the result shown in Figure 4(D) was obtained. Temperature T is the ambient temperature t minus the reference temperature (25°C), i.e., T = t - 25°C.

[0047] As shown in Figure 4(D), the slope α of the low temperature (-20°C), the reference temperature (25°C), and the high temperature (80°C) is linear with respect to the temperature T, so the frequency fr of the ripple current can be expressed by the following equation (2) based on the ripple current Ir, the inter-terminal voltage Vm, and the temperature T.

[0048] fr=α×Ir×K+β×Vm (2) Here, K is a variable temperature coefficient expressed by the following equation (3).

[0049] K=1-γ×T (3) In equation (3), γ is a predetermined temperature coefficient, and is the absolute value of the ratio of the change Δα in the slope α to the change Δt in the environmental temperature t.

[0050] Therefore, the frequency adjuster 161 may calculate the temperature T based on the ambient temperature t detected by the temperature sensor 170, substitute the temperature T into equation (3) to calculate the variable temperature coefficient K, and then substitute the value of the ripple current calculated based on the ripple pulse, the inter-terminal voltage Vm, and the variable temperature coefficient K into equation (2) to calculate the frequency fr of the ripple current. The frequency adjuster 161 may then adjust the pass band of the variable filter 130 so that the frequency fr of the ripple current is included in the pass band of the variable filter 130. The frequency adjuster 161 outputs a variable clock corresponding to the calculated frequency fr of the ripple current to the variable filter 130 to adjust the pass band. Ensuring that the frequency fr of the ripple current is included in the pass band of the variable filter 130 is to make it suitable for the driving state of the motor 23. The frequency adjuster 161 may read data representing equations (2) and (3) from the memory 162 and use the data in the calculation.

[0051] As an example, it is more preferable that γ satisfies 0.2<γ<0.5. As an example, the optimum value of γ is 0.34, which is the absolute value of the ratio of the change in slope to the change in environmental temperature, as shown in FIG. 4(D).

[0052] <Ripple pulse detection results> 5A and 5B are diagrams showing an example of the detection results of ripple pulses. Fig. 5A shows an example of the detection results of ripple pulses by ripple detection device 100, and Fig. 5B shows an example of the detection results of ripple pulses by a comparative ripple detection device. The comparative ripple detection device does not include variable filter 130, and filter 140, which is an HPF, is directly connected to the output side of filter 122, which is an LPF.

[0053] 5A and 5B, the lower part shows the ripple current input to the ripple pulse generating unit 150, and the upper part shows the ripple pulse output from the ripple pulse generating unit 150.

[0054] 5A, there are no missing (missed detection) or false detections, and the ripple pulses can be detected at regular intervals with high accuracy. Therefore, by using the ripple detection device 100 of the embodiment, the rotation position of the motor 23 can be detected with high accuracy regardless of the magnitude of the load on the motor 23, and the seat 20 can be adjusted accurately.

[0055] 5B, the area enclosed by the dashed square has gaps (detection omissions) or false detections, and the ripple pulses are not detected at regular intervals. For this reason, when the comparative ripple detection device is used, the rotational position of the motor 23 cannot be detected with high accuracy, and the seat 20 cannot be adjusted accurately.

[0056] <Effects> The ripple detection device 100 includes a current detection unit 112 and a resistor 24 that detect a ripple current generated when the motor 23 is driven, a voltage detection unit 111 that detects a terminal voltage Vm of the motor 23, a variable filter 130 that passes components of a predetermined frequency band of the ripple current detected by the current detection unit 112 and the resistor 24, and a frequency adjustment unit 161 that uses a linear relational expression to derive the frequency of the ripple current based on the ripple current detected by the current detection unit 112 and the resistor 24 and the terminal voltage Vm detected by the voltage detection unit 111, and adjusts the predetermined frequency band of the variable filter 130 to include the derived frequency of the ripple current. Therefore, the frequency of the ripple current can be derived from the linear relational expression based on the ripple current and the terminal voltage Vm, and the predetermined frequency band of the variable filter 130 can be adjusted according to the frequency of the ripple current, thereby suppressing missing ripple pulses (missed ripple detection) and erroneous detection of ripple pulses.

[0057] Therefore, by using a linear relational expression that derives the ripple current frequency fr based on the ripple current Ir and the motor terminal voltage Vm, it is possible to provide a ripple detection device 100 that can optimally control the pass band of the variable filter 130 in accordance with the driving state of the motor 23 and detect ripple pulses with high accuracy.

[0058] The linear relational expression is expressed by the following equation (1): The equation (1) shown here is the same as the equation (1) described above.

[0059] fr=α×Ir+β×Vm (1) where Ir is the ripple current, fr is the frequency of the ripple current, α is the ratio (Δfr / ΔIr) of the change in ripple current Ir to the change in ripple current frequency fr (Δfr), and β is the ratio (Δfr / ΔVm) of the change in terminal voltage Vm to the change in ripple current frequency fr (Δfr).

[0060] Therefore, by utilizing the linearity between the ripple current Ir and the ripple current frequency fr to adjust the passband of the variable filter 130, it is possible to speed up processing and provide a ripple detection device 100 that can detect ripple pulses with high accuracy.

[0061] The ripple detection device 100 further includes a temperature sensor 170 that detects the ambient temperature of the motor 23. The frequency adjustment unit 161 adjusts the predetermined frequency band of the variable filter 130 to include the frequency of the derived ripple current using a linear relational expression between the ripple current detected by the current detection unit 112 and the resistor 24, the inter-terminal voltage Vm detected by the voltage detection unit 111, and the ambient temperature detected by the temperature sensor 170, and the linear relational expression is expressed by the following equation (2). The equation (2) shown here is the same as the above-mentioned equation (2).

[0062] fr=α×Ir×K+β×Vm (2) where Ir is the ripple current, fr is the frequency of the ripple current, α is the ratio (Δfr / ΔIr) of the change in the ripple current frequency fr to the change in the ripple current Ir, K is the variable temperature coefficient expressed by the following equation (3), and β is the ratio (Δfr / ΔVm) of the change in the ripple current frequency fr to the change in the terminal voltage Vm. Equation (3) shown here is the same as equation (3) above.

[0063] K=1-γ×T (3) In equation (3), γ is a predetermined temperature coefficient, and T is a temperature obtained by subtracting a predetermined reference temperature from the environmental temperature t of the motor 23 detected by the temperature sensor 170.

[0064] Therefore, by utilizing the linearity between the ripple current Ir and the variable temperature coefficient K and the frequency fr of the ripple current, and adjusting the passband of the variable filter 130 taking into account the environmental temperature t of the motor 23 detected by the temperature sensor 170, it is possible to speed up processing while taking into account the environmental temperature t, and to provide a ripple detection device 100 that can detect ripple pulses with high accuracy.

[0065] The ripple detection device 100 also includes a memory 162 that stores data representing the linear relational expression expressed by equation (1). Therefore, by reading and using equation (1) from the memory 162, the linearity between the ripple current Ir and the ripple current frequency fr can be utilized to instantly calculate the ripple current frequency fr, and the passband of the variable filter 130 can be adjusted. This makes it possible to provide a ripple detection device 100 that can speed up processing and detect ripple pulses with high accuracy.

[0066] The ripple detection device 100 also includes a memory 162 that stores data representing the linear relational expression expressed by equation (2) and data representing equation (3). Therefore, by reading and using equations (2) and (3) from the memory 162, the ripple current frequency fr can be instantly calculated by taking into account the ambient temperature t and utilizing the linearity between the ripple current Ir and the ripple current frequency fr, and the passband of the variable filter 130 can be adjusted. This makes it possible to provide a ripple detection device 100 that can speed up processing and detect ripple pulses with high accuracy.

[0067] Moreover, the ripple detection device 100 further includes a ripple pulse generation unit 150 that generates a ripple pulse from the output signal of the variable filter 130. Therefore, the variable filter 130 can be optimized according to the characteristics of the motor 23.

[0068] The ripple detection device 100 also includes a filter 122 provided on the input side of the variable filter 130 and a filter 140 provided on the output side of the variable filter 130, and the ripple pulse generation unit 150 receives the ripple current that is detected by the current detection unit 112 and the resistor 24 and passes through the filter 122, the variable filter 130, and the filter 140 in that order. Therefore, even if the characteristics of the ripple current of the motor 23 are disturbed, the ripple current can be detected with high accuracy by accurately removing noise.

[0069] The seat device 10 is mounted on the vehicle 1 and includes a seat 20 whose position or angle can be adjusted by a motor 23, a drive control unit 50 that controls the drive of the motor 23, and a ripple detection device 100 that detects a ripple current of the motor 23 and outputs the detected ripple current to the drive control unit 50. The ripple detection device 100 includes a current detection unit 112 and a resistor 24 that detect a ripple current generated when the motor 23 is driven, a voltage detection unit 111 that detects a terminal voltage Vm of the motor 23, a variable filter 130 that passes components of a predetermined frequency band of the ripple current detected by the current detection unit 112 and the resistor 24, and a frequency adjustment unit 161 that uses a linear relational expression to derive the frequency of the ripple current based on the ripple current detected by the current detection unit 112 and the resistor 24 and the terminal voltage Vm detected by the voltage detection unit 111, and adjusts the predetermined frequency band of the variable filter 130 to include the frequency of the derived ripple current.

[0070] Therefore, the frequency of the ripple current can be derived from a linear relational expression based on the ripple current and the inter-terminal voltage Vm, and the predetermined frequency band of the variable filter 130 can be adjusted according to the frequency of the ripple current, thereby suppressing missing ripple pulses (missed ripple detection) and false detection of ripple pulses. As a result, the rotational position of the motor 23 can be detected with high accuracy regardless of the magnitude of the load on the motor 23, and the seat 20 can be adjusted accurately.

[0071] Therefore, by using a linear relational expression that derives the ripple current frequency fr based on the ripple current Ir and the motor terminal voltage Vm, and optimally controlling the passband of the variable filter 130 according to the driving state of the motor 23, it is possible to provide a seat device 10 that can detect ripple pulses with high accuracy and accurately adjust the seat 20.

[0072] The above describes exemplary embodiments of the ripple detection device and seat device of the present disclosure, but the present disclosure is not limited to the specifically disclosed embodiments, and various modifications and changes are possible without departing from the scope of the claims.

[0073] This international application claims priority based on Japanese Patent Application No. 2022-106006, filed on June 30, 2022, the entire contents of which are incorporated herein by reference. [Explanation of symbols]

[0074] 1 vehicle 10 Seat device 20 sheets 23, 23A, 23B motors 24 Resistor (an example of a ripple current detector) 50 Drive control unit 100 Ripple detection device 111 Voltage detection unit (an example of a motor voltage detection unit) 112 Current detection section (an example of a ripple current detection section) 121 filters 122 filter (example of the first filter) 130 Variable Filter 140 filter (example of second filter) 150 Ripple pulse generator 160 MCU 161 Frequency adjustment unit 162 memory 170 Temperature Sensor

Claims

1. a ripple current detection unit that detects a ripple current generated when the motor is driven; a motor voltage detection unit that detects a voltage between the terminals of the motor; a variable filter that passes components of a predetermined frequency band of the ripple current detected by the ripple current detection unit; a frequency adjusting unit that adjusts the predetermined frequency band of the variable filter so as to include a frequency of the ripple current derived using a linear relational expression that derives a frequency of the ripple current based on the ripple current detected by the ripple current detecting unit and the terminal voltage detected by the motor voltage detecting unit; a temperature sensor for detecting the ambient temperature of the motor; Equipped with the frequency adjusting unit adjusts the predetermined frequency band of the variable filter so as to include a frequency of the ripple current derived using a linear relational expression among the ripple current detected by the ripple current detecting unit, the terminal voltage detected by the motor voltage detecting unit, and the environmental temperature detected by the temperature sensor; The ripple detection device, wherein the linear relational expression is expressed by the following expression (2). fr=α×Ir×K+β×Vm (2) where Ir is the ripple current, fr is the frequency of the ripple current, α is the ratio of the change in the frequency of the ripple current to the change in the ripple current, K is a variable temperature coefficient expressed by the following equation (3), and β is the ratio of the change in the frequency of the ripple current to the change in the terminal voltage. K = 1 - γ × T (3) In equation (3), γ is a predetermined temperature coefficient, and T is a temperature obtained by subtracting a predetermined reference temperature from the environmental temperature of the motor detected by the temperature sensor.

2. 2. The ripple detection device according to claim 1, wherein the linear relational expression is expressed by the following equation (1). fr=α×Ir+β×Vm (1) where Ir is the ripple current, fr is the frequency of the ripple current, α is the ratio of the change in the frequency of the ripple current to the change in the ripple current, and β is the ratio of the change in the frequency of the ripple current to the change in the terminal voltage.

3. The ripple detection device according to claim 2 , further comprising a memory for storing data representing the linear relational expression expressed by the equation (1).

4. The ripple detection device according to claim 1 , further comprising a memory for storing data representing the linear relational expression expressed by the equation (2) and data representing the equation (3).

5. The ripple detection device according to claim 2 , further comprising a ripple pulse generation unit that generates a ripple pulse from the output signal of the variable filter.

6. a first filter provided on the input side of the variable filter; a second filter provided on the output side of the variable filter; Furthermore, 6. The ripple detection device according to claim 5, wherein the ripple pulse generation unit receives a ripple current that is detected by the ripple current detection unit and passes through the first filter, the variable filter, and the second filter in this order.

7. a seat mounted in a vehicle and capable of adjusting a position or angle by a motor; a drive control unit that controls the drive of the motor; a ripple detection device that detects a ripple current of the motor and outputs the detected ripple current to the drive control unit; A seat device comprising: The ripple detection device is a ripple current detection unit that detects a ripple current generated when the motor is driven; a motor voltage detection unit that detects a voltage between the terminals of the motor; a variable filter that passes components of a predetermined frequency band of the ripple current detected by the ripple current detection unit; a frequency adjusting unit that adjusts the predetermined frequency band of the variable filter so as to include a frequency of the ripple current derived using a linear relational expression that derives a frequency of the ripple current based on the ripple current detected by the ripple current detecting unit and the terminal voltage detected by the motor voltage detecting unit; a temperature sensor for detecting the ambient temperature of the motor; Equipped with the frequency adjusting unit adjusts the predetermined frequency band of the variable filter so as to include a frequency of the ripple current derived using a linear relational expression among the ripple current detected by the ripple current detecting unit, the terminal voltage detected by the motor voltage detecting unit, and the environmental temperature detected by the temperature sensor; The linear relational expression is expressed by the following equation (2): fr=α×Ir×K+β×Vm (2) where Ir is the ripple current, fr is the frequency of the ripple current, α is the ratio of the change in the frequency of the ripple current to the change in the ripple current, K is a variable temperature coefficient expressed by the following equation (3), and β is the ratio of the change in the frequency of the ripple current to the change in the terminal voltage. K = 1 - γ × T (3) In equation (3), γ is a predetermined temperature coefficient, and T is a temperature obtained by subtracting a predetermined reference temperature from the environmental temperature of the motor detected by the temperature sensor.

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