Control device for variable damping force damper

Abstract

Provided is a control device for a variable damping force damper with which the responsiveness of the damper can be improved. This control device for a variable damping force damper controls the current of a coil (6) of the variable damping force damper so as to match the actual current to a target current and comprises an H-bridge circuit (24) that supplies power to the coil (6) of the variable damping force damper according to the duty ratio. When the duty ratio reaches zero or a prescribed value or less, the connection state of the coil (6) is switched by the H-bridge circuit (24) from the connection state in fig. 4(a) to the connection state in fig. 4(b), and a reverse voltage is applied to the coil (6) for a prescribed period of time.

Description

Control device for variable damping damper

[0001] The present invention relates to a control device for a variable damping damper that controls the damping force of a damper provided in the suspension system of a vehicle such as an automobile.

[0002] As a variable damping force damper, there is a known type that uses a functional fluid such as magneto-rheological fluid (MRF), whose viscosity changes under the influence of a magnetic field, and changes the damping force of the damper by altering the viscosity of the functional fluid with a magnetic field generated by energizing a coil. There are two types of variable damping force dampers: rotary dampers and linear dampers. In rotary dampers, a rotating body is provided rotatably within a case, and the functional fluid is interposed between the case and the rotating body. In linear dampers, a piston is provided slidably within a cylinder, and the cylinder is filled with the functional fluid.

[0003] In such a variable damping damper, a larger current flowing through the coil results in a larger damping force, while a smaller current results in a smaller damping force. Therefore, the damping force of the damper can be controlled by controlling the current flowing through the coil.

[0004] To control the current flowing through a coil, a PWM (Pulse Width Modulation) method is used, which supplies the required power to the coil by switching pulses on and off (see Patent Document 1). That is, a DC voltage is applied to the coil, and a PWM signal of the voltage (in other words, the duty cycle) is calculated so that the actual current matches the target current, and the current flowing through the coil is controlled according to this duty cycle.

[0005] Japanese Patent Publication No. 2020-100319

[0006] However, conventional PWM-based control systems for variable damping dampers have a problem: poor damper responsiveness. For example, even when the duty cycle becomes zero during the falling edge of the target current, the current flowing through the coil does not immediately become zero, and some current remains in the coil. This results in residual damping force in the damper, and when the wheels drive over bumps in the road, for example, the force that pushes the wheels up is transmitted from the wheels to the vehicle body, reducing ride comfort.

[0007] This invention has been made in view of the above problems, and aims to provide a control device for a damping force variable damper that can improve the responsiveness of the damper.

[0008] To solve the above problems, a first aspect of the present invention is a control device for a variable damping damper that controls the current of the coil of the variable damping damper so that the actual current matches the target current, and comprises an H-bridge circuit that supplies power to the coil of the variable damping damper according to the duty cycle, and when the duty cycle becomes zero or less than a predetermined value, the H-bridge circuit switches the connection state of the coil and applies a reverse voltage to the coil for a predetermined time.

[0009] A second aspect of the present invention is a control device for a variable damping damper that controls the current of the coil of the variable damping damper so that the actual current matches the target current, and comprises an H-bridge circuit that supplies power to the coil of the variable damping damper according to the duty cycle, and when the derivative value at the rise of the target current becomes greater than or equal to a predetermined value, a rise duty cycle larger than the duty cycle determined according to the deviation between the target current and the actual current is input to the H-bridge circuit for a predetermined time.

[0010] According to a first aspect of the present invention, when the duty cycle becomes zero or less than a predetermined value, the H-bridge circuit switches the connection state of the coil and applies a reverse voltage to the coil for a predetermined time, thereby rapidly reducing the current remaining in the coil. This improves the responsiveness of the damper when the target current falls.

[0011] According to a second aspect of the present invention, when the derivative value at the rise of the target current exceeds a predetermined value, a predetermined duty cycle larger than the duty cycle determined according to the deviation between the target current and the actual current is input to the H-bridge circuit for a predetermined time, thereby improving the responsiveness of the damper at the rise of the target current.

[0012] This is a longitudinal cross-sectional view of an example of a variable damping force damper according to this embodiment. This is the experimental result of the damper's responsiveness (Figure 2(a) is a graph comparing the duty cycle and the current flowing through the coil, and Figure 2(b) is a graph comparing the target torque and the actual torque of the damper). This is a block diagram of the control device for the variable damping force damper according to the first embodiment of the present invention. This is a diagram of the H-bridge circuit (Figure 4(a) is under normal conditions, and Figure 4(b) is when a reverse voltage is applied). This is a flowchart of the current control calculation unit. This is a block diagram of the control device for the variable damping force damper according to the second embodiment of the present invention. This is a flowchart of the current control calculation unit. This is a diagram of the pulse of Example 1. This is a graph showing the damper's responsiveness (Figure 9(a) shows the current responsiveness, and Figure 9(b) shows the torque responsiveness). This is a diagram of the pulse of Example 2. This is a graph showing the damper's responsiveness (Figure 11(a) shows the current responsiveness, and Figure 11(b) shows the torque responsiveness).

[0013] Hereinafter, with reference to the attached drawings, a control device for a variable damping force damper according to an embodiment of the present invention will be described in detail. However, the control device for a variable damping force damper according to the present invention can be embodied in various forms and is not limited to the embodiments described in this specification. This embodiment is provided with the intention that those skilled in the art will be able to fully understand the invention by making full disclosures in this specification. (Variable Damping Force Damper)

[0014] Figure 1 shows a longitudinal cross-sectional view of an example of a variable damping force damper 1 (hereinafter simply referred to as damper 1) according to this embodiment. The damper 1 according to this embodiment is a rotary damper, but it may also be a linear damper, as long as the functional fluid changes viscosity due to the magnetic field generated by the coil.

[0015] The damper 1 shown in Figure 1 comprises a case 2, a functional fluid 4 filled in a reservoir 3 of the case 2, a rotating body 5 rotatably mounted in the reservoir 3 of the case 2, a coil 6 positioned at the bottom of the reservoir 3 of the case 2, and a ball screw 7 that rotates the rotating body 5. This damper 1 is incorporated into a suspension system. The screw shaft 7a of the ball screw 7 is connected, for example, to the vehicle body (sprung mass), and the case 2 is connected, for example, to the suspension arm (unsprung mass). When the screw shaft 7a moves relative to the case 2 in the axial direction, the nut 7b of the ball screw 7 rotates, and the rotating body 5 rotates together with the nut 7b. The damper 1 changes the damping force of the damper 1 by changing the viscosity of the functional fluid 4 using a magnetic field generated by energizing the coil 6.

[0016] The storage tank 3 of case 2 is formed in a substantially cylindrical shape. Case 2 comprises a case body 2a that forms the outer circumference of the storage tank 3, and a substantially cylindrical block 2b that forms the inner circumference of the storage tank 3 and is attached to the case body 2a.

[0017] After filling the storage tank 3 of case 2 with the functional fluid 4, the top of case 2 is closed by a lid member 9. The lid member 9 is provided with an opening 9a through which the screw shaft 7a of the ball screw 7 passes. The lid member 9 is also provided with a bearing 10 that rotatably supports the nut 7b of the ball screw 7.

[0018] The rotating body 5 is connected to the nut 7b of the ball screw 7. The rotating body 5 is substantially cylindrical and comprises a shoulder portion 5a attached to the nut 7b and a cylindrical body 5b. The cylindrical body 5b is positioned between the case body 2a and the block 2b.

[0019] Functional fluid 4 includes magnetic fluids containing dispersed iron powder, and magnetorheological fluids, also known as MR fluids.

[0020] The coil 6 constitutes an electromagnet using the case body 2a and block 2b as a yoke. The coil 6 is held in a bobbin 12 and is positioned below the storage tank 3 together with the bobbin 12. When a DC voltage is applied to the coil 6, a magnetic field is generated, forming a magnetic loop M that spans the case body 2a and block 2b. The functional fluid 4 is placed on the magnetic path, which is the path of the magnetic loop M.

[0021] As described above, when the vehicle body (sprung mass) moves relative to the suspension arm (unsprung mass), the screw shaft 7a of the ball screw 7 moves relative to the case 2 in the axial direction, causing the rotating body 5 to rotate together with the nut 7b. When a DC voltage is applied to the coil 6, a magnetic loop M is generated, and chain-like clusters of iron powder, etc., are formed in the functional fluid 4 between the case 2 and the rotating body 5. When the rotating body 5 rotates, a damping force is generated by the shear resistance of these clusters.

[0022] Therefore, by controlling the DC voltage applied to coil 6, the strength of the magnetic loop M can be controlled, thereby controlling the damping force of damper 1. A PWM (pulse-wavelength) method, which switches the DC voltage pulse on and off, is used to control the DC voltage. (Experimental results of damper responsiveness)

[0023] Figures 2(a) and 2(b) show the experimental results of the damper's responsiveness. Figure 2(a) is a graph comparing the PWM signal (duty cycle) and the current flowing through coil 6, and Figure 2(b) is a graph comparing the damper's target damping force (target torque) and actual damping force (actual torque). The actual torque was calculated by simulation from the current flowing through coil 6.

[0024] As shown in Figure 2(b), when controlled using the PWM method, the actual torque can generally follow the target torque, but the actual torque's tracking was delayed, especially during the falling edge of the target torque (during the time period T demarcated by the dashed line in the figure). To verify the reason for this, the responsiveness of the actual current to the target current shown in Figure 2(a) was examined. As shown in Figure 2(a), during time period T, when the actual torque's tracking is delayed, current remains in the coil 6 even after the duty cycle has fallen to zero. This is presumed to be due to the residual magnetism of the coil 6 and the maintenance of clusters in the functional fluid 4. During time period T, the current flowing through the coil 6 should ideally become zero in accordance with the duty cycle, but because current remains in the coil 6, the actual torque remains, and the actual torque cannot follow the target torque.

[0025] The control device according to this embodiment enables the rapid reduction of the current remaining in the coil 6 and the rapid removal of residual torque. (First Embodiment)

[0026] As shown in Figure 3, the control device 21 according to the first embodiment of the present invention comprises a target current calculation unit 22, a current control calculation unit 23, and an H-bridge circuit 24. The target current calculation unit 22 calculates the target current from the target damping force. The current control calculation unit 23 calculates the target current I ｃ Actual current I ｍ Deviation I ｄ Duty cycle D ｔａ The current control calculation unit 23 calculates the duty cycle D. ｔ Direction command D for switching the connection state of coil 6. ｉｒ The output is sent to the H-bridge circuit 24. The H-bridge circuit 24 receives the input duty cycle D ｔ In accordance with the input direction command D, power is supplied to coil 6 and the input direction command D ｉｒ The connection state of coil 6 is switched accordingly. The target current calculation unit 22 and the current control calculation unit 23 are realized by a microcomputer executing a program stored in ROM.

[0027] The target damping force 20 is calculated by an ECU (Electronic Control Unit) not shown in the figures. The ECU calculates the damping forces of the total four dampers 1 for each wheel based on the detection values of various sensors provided in the vehicle, such as a wheel speed sensor for detecting vehicle speed, a sprung acceleration sensor, a damper displacement sensor for detecting the displacement of the damper, a steering angle sensor for detecting the steering angle of the front wheel, and the like. Further, the ECU selectively executes skyhook control for suppressing the rocking of the vehicle when overcoming the unevenness of the road surface to improve the riding comfort, and maneuverability control for suppressing rolling during vehicle turning and pitching during sudden acceleration or deceleration of the vehicle according to the driving state of the vehicle. Incidentally, instead of the ECU, the above-mentioned microcomputer may calculate the target damping force 20, or the ECU may include the above-mentioned target current calculation unit 22.

[0028] The target current calculation unit 22 calculates a target torque corresponding to the characteristics of the damper 1 from the target damping force 20, calculates the damper rotation speed from the damper displacement sensor, and calculates the target current from the target torque and the damper rotation speed using a target current map that specifies the relationship among the target torque, the damper rotation speed, and the target current.

[0029] The current control calculation unit 23 includes a PI control calculation unit 31 and a determination processing unit 32. The PI control calculation unit 31 performs proportional-integral control on the deviation I ｃ of the actual current I ｍ with respect to the target current I ｄ = I ｃ - I ｍ and calculates the duty ratio D ｔａ which is the feedback command value. The actual current is the detected value of the current actually flowing through the coil 6 and is detected by the current detector 33.

[0030] The determination processing unit 32 performs a determination process as to whether or not the duty ratio D ｔａ becomes zero and the above-mentioned deviation I ｄ becomes less than or equal to a predetermined value. The predetermined value is set to a value such that the responsiveness of the damper 1 is, for example, the actual torque does not fall below the target torque based on the experimental results.

[0031] When the duty ratio D ｔａ is zero and the deviation I ｄWhen the condition is not met, the determination processing unit 32 issues the direction command D ｉｒ =1 is output to the H-bridge circuit 24, and the duty cycle D calculated by the PI control calculation unit 31 is ｔａ This is output to the H-bridge circuit 24.

[0032] Conversely, duty cycle D ｔａ If zero and deviation I ｄ When the value falls below a predetermined value, the determination processing unit 32 issues the direction command D ｉｒ = -1 and reverse voltage duty cycle D ｔｂ The reverse voltage duty cycle D is output to the H-bridge circuit 24 for a predetermined time. ｔｂ This is stored in memory 34 in advance and is set to, for example, 100%. The predetermined time is set to, for example, 15 ms to 40 ms. After the predetermined time has elapsed, the determination processing unit 32 again issues the direction command D ｉｒ = 1 and the duty cycle D calculated by the PI control calculation unit 31 ｔａ This is output to the H-bridge circuit 24.

[0033] The determination processing unit 32 has a duty cycle D ｔａ You can also perform a check to determine whether or not it has become zero, or you can use a duty cycle D ｔａ The determination process may only be performed to check whether the value falls below a predetermined value. The predetermined value is set to, for example, 10% or less based on experimental results of the responsiveness of damper 1.

[0034] This concludes the explanation of the configuration of the target current calculation unit 22 and the current control calculation unit 23. Next, the configuration of the H-bridge circuit 24 will be explained with reference to Figures 3 and 4.

[0035] As shown in Figure 3, the H-bridge circuit 24 comprises four transistors (power MOSFETs) Q1 to Q4, which are controlled by the gate drive circuit 24a to drive the coil 6. The gate drive circuit 24a controls the direction command D ｉｒ and duty cycle D ｔ This is a digital circuit that drives transistors Q1 to Q4 of the H-bridge circuit 24 based on the signal D. The gate drive circuit 24a is a digital circuit that drives transistors Q1 to Q4 of the H-bridge circuit 24 based on the signal D. ｉｒWhen is 1, as shown in Figure 4(a), transistors Q1 and Q4 of the H-bridge circuit 24 are turned on, the (+) terminal of the battery 35 is connected to one terminal of coil 6, and the (-) terminal of coil 6 is connected to the other terminal. Conversely, direction command D ｉｒ When the value is -1, as shown in Figure 4(b), the gate drive circuit 24a turns on transistors Q2 and Q3, connects the negative terminal of the battery 35 to one terminal of coil 6, and connects the positive terminal of the other terminal of coil 6. Since the connection state of coil 6 in Figure 4(b) is the opposite of that in Figure 4(a), a reverse voltage is applied to coil 6 in the connection state of coil 6 in Figure 4(b).

[0036] The gate drive circuit 24a receives the duty cycle D from the determination processing unit 32. ｔ The H-bridge circuit 24 is designed to drive Q1 and Q2 with a PWM signal. These cases are summarized in a table.

[0037]

[0038] As shown in Figure 3, the current detector 33 detects the actual current in the coil 6 by detecting the potential difference across the resistor 37 placed between the H-bridge circuit 24 and ground. The battery 35 is a DC power source. (Effects)

[0039] The damper control device 21 of this embodiment provides the following effects. In explaining the effects, we will focus on the effects of the current control calculation unit 23, which is a characteristic feature of the present invention.

[0040] As shown in Figure 5, in step S1, the PI control calculation unit 31 calculates the duty cycle D ｔａ The duty cycle D calculated by the PI control calculation unit 31 is calculated in step S2. ｔａ When the deviation becomes zero, ｄ The determination processing unit 32 determines whether or not the value exceeds a predetermined value. If the above is not met in step S2, the process proceeds to steps S3 and S5, and the determination processing unit 32 issues a direction command D. ｉｒ = 1 and duty cycle D ｔａ This is output to the H-bridge circuit 24.

[0041] If the above is true in step S2, the process proceeds to steps S4 and S5, and the determination processing unit 32 issues a direction command D ｉｒ = -1 and duty cycle D ｔｂ The H-bridge circuit 24 outputs the following for a predetermined time. As a result, the H-bridge circuit 24 switches the connection state of the coil 6 and applies a reverse voltage to the coil 6 for a predetermined time. After the predetermined time has elapsed, the determination processing unit 32 issues a direction command D ｉｒ = 1 and the duty cycle D calculated by the PI control calculation unit 31 ｔａ This is output to the H-bridge circuit 24. As a result, the H-bridge circuit 24 has a duty cycle D ｔａ The appropriate power is supplied to coil 6. In other words, the control returns to normal.

[0042] In this way, when the duty cycle becomes zero, the H-bridge circuit 24 switches the connection state of the coil 6 and applies a reverse voltage to the coil 6 for a predetermined time, so that the current remaining in the coil 6 can be quickly reduced. The damping force of the damper 1 can also be quickly reduced, so for example, when the wheel goes over a bump in the road, the force that pushes the wheel up is transmitted from the wheel to the vehicle body, which prevents a decrease in ride comfort performance.

[0043] Also, deviation I ｄ When the value exceeds a predetermined value, the H-bridge circuit 24 switches the connection state of the coil 6 and applies a reverse voltage to the coil 6 for a predetermined time. This prevents further reduction of the actual torque, for example, even if the actual torque is already lower than the target torque.

[0044] By setting the predetermined time to 15 ms to 40 ms, the torque of damper 1 can be rapidly reduced. If the predetermined time is less than 15 ms, the torque of damper 1 decreases gradually. If the predetermined time exceeds 40 ms, although the torque of damper 1 can be rapidly reduced, the steady-state torque becomes greater than the torque when the duty cycle is zero. This is thought to be due to reverse current flowing through coil 6. This point will be explained in Example 1 below. (Second Embodiment)

[0045] As shown in Figure 6, the control device 41 according to the second embodiment of the present invention also includes a target current calculation unit 22, a current control calculation unit 44, and an H-bridge circuit 24. The configuration of the target current calculation unit 22 and the H-bridge circuit 24 is the same as that of the control device 21 according to the first embodiment, so the same reference numerals are used and their descriptions are omitted. The current control calculation unit 44 is the current control calculation unit 23 of the control device 21 according to the first embodiment with the addition of a target current differential calculation unit 42 and a memory 43. The other configurations are the same as those of the control device 21 according to the first embodiment.

[0046] In the control device 41 of the second embodiment, the target current differentiation calculation unit 42 calculates the target current I ｃ The derivative value I at the rising edge ｅ The (slope) is calculated. The differential value I calculated by the target current differential calculation unit 42 is... ｅ This is supplied to the determination processing unit 32.

[0047] The determination processing unit 32 determines the target current I ｃ The derivative of I ｅ A determination process is performed to determine whether the value exceeds a predetermined value. The predetermined value is set by experiments on the responsiveness of damper 1 when the target current rises.

[0048] Target current I ｃ The derivative of I ｅ Under normal circumstances, when the value does not exceed a predetermined value, the determination processing unit 32 issues the direction command D ｉｒ = 1 and the duty cycle D calculated by the PI control calculation unit 31 ｔａ This is output to the H-bridge circuit 24.

[0049] Target current I ｃ The derivative of I ｅ When the value exceeds a predetermined value, the determination processing unit 32 issues the direction command D ｉｒ = 1 and rising duty cycle D ｔｃ The signal is output to the H-bridge circuit 24 for a predetermined time. Rise-off duty cycle D ｔｃ The target current I is stored in memory 43 beforehand. ｃ and actual current I ｍ Deviation I ｄThe duty cycle is set to a value greater than the duty cycle determined accordingly, for example, 100%. The predetermined time is set to, for example, 25 ms to 45 ms. After the predetermined time has elapsed, the determination processing unit 32 again issues the direction command D ｉｒ = 1 and the duty cycle D calculated by the PI control calculation unit 31 ｔａ This is output to the H-bridge circuit 24. (Effect)

[0050] The control device 41 of the second embodiment has the following effects. As shown in Figure 7, in step S01, the determination processing unit 32 determines the target current I ｃ The derivative of I ｅ The system performs a determination process to check whether the value exceeds a predetermined value.

[0051] Target current I ｃ The derivative of I ｅ Under normal circumstances, when the duty cycle does not exceed a predetermined value, the process proceeds to S1, and the PI control calculation unit 31 calculates the duty cycle D ｔａ The following is calculated. Since S1 to S5 are the same as the control device 21 of the first embodiment, the same reference numerals are used and their descriptions are omitted.

[0052] If the above is true in step S01, the process proceeds to steps S02 and S5, and the determination processing unit 32 determines the direction command D ｉｒ = 1 and rising duty cycle D ｔｃ The H-bridge circuit 24 outputs the signal for a predetermined time. As a result, the H-bridge circuit 24 applies a rise voltage to the coil 6 for a predetermined time. After the predetermined time has elapsed, the determination processing unit 32 issues the direction command D. ｉｒ = 1 and the duty cycle D calculated by the PI control calculation unit 31 ｔａ This is output to the H-bridge circuit 24. As a result, the H-bridge circuit 24 has a duty cycle D ｔａ The appropriate power is supplied to coil 6. In other words, the control returns to normal.

[0053] Thus, the target current I ｃ The derivative value I at the rising edge ｅ When it exceeds a predetermined value, the target current I ｃ and actual current I ｍ Deviation I ｄ Duty cycle D is determined accordingly. ｔａ Larger rise duty cycle Dｔｃ Since it is input to the H-bridge circuit 24 for a predetermined time H, the responsiveness of the damper 1 can be improved. (Example 1)

[0054] Using the damper 1 shown in FIG. 1, as shown in FIG. 8, a duty ratio of 29% (D ｉｒ = 1, D ｔ = 29%) was input to the H-bridge circuit 24, and then, for a predetermined time T ｐ１ duty ratio -100% (D ｉｒ = -1, D ｔ = 100%) was input. That is, a reverse voltage was applied to the coil 6 for a predetermined time T ｐ１

[0055] For the predetermined time T ｐ１ When it was changed to 0 ms, 15 ms, 30 ms, 40 ms, and 45 ms, the current value flowing through the coil 6 is shown in FIG. 9(a), and the torque converted from the current value is shown in FIG. 9(b). As shown in FIG. 9(b), when the predetermined time T ｐ１ was 0 ms, that is, when no reverse voltage was applied to the coil 6, the torque decreased gradually. When the predetermined time T ｐ１ was 15 ms to 40 ms, the torque decreased rapidly. When the predetermined time T ｐ１ was 45 ms, although the torque decreased rapidly, it became larger than the torque when no reverse voltage was applied. This is considered to be due to the current flowing in the reverse direction through the coil 6. (Example 2)

[0056] Using the damper 1 shown in FIG. 1, as shown in FIG. 10, a duty ratio of 0% (D ｉｒ = 1, D ｔ = 0%) was input to the H-bridge circuit 24, and then, for a predetermined time T ｐ２ duty ratio 100% (D ｉｒ = 1, D ｔ = 100%) was input, and then, a duty ratio of 29% (D ｉｒ = 1, D ｔ = 29%) was input. That is, a rising duty ratio D ｔ = 100% was input to the H-bridge circuit 24.

[0057] For the predetermined time T ｐ２ ​Figure 11(a) shows the current values ​​flowing through coil 6 when the time is changed to 0 ms, 25 ms, 35 ms, 45 ms, and 55 ms, and Figure 11(b) shows the torque calculated from the current values. As shown in Figure 11(b), the predetermined time T ｐ２ When this is 0 ms, that is, the rise time of the H-bridge circuit 24 is D ｔ When 100% was not input, the torque increased gradually. (Date T) ｐ２ When the time interval was between 25 ms and 45 ms, the torque increased rapidly. ｐ２ When the time is 55 ms, the torque rises rapidly, but the steady-state torque rises and the duty cycle D ｔ = The torque was greater than when not inputting 100%. (Duty cycle D) ｔ It is thought that entering 100% had an effect.

[0058] This specification is based on Japanese Patent Application No. 2024-232665, filed on 27 December 2024. All of its contents are included herein.

[0059] 1...Damper 6...Coil 24...H-bridge circuit 21, 41...Damper control device I ｃ ...Target current I ｍ ...Actual current I ｄ ...deviation I ｅ ...the derivative of the target current D ｉｒ ...Direction command D ｔ ...duty cycle

Claims

1. A control device for a variable damping damper that controls the current of the coil of the variable damping damper so that the actual current matches the target current, comprising an H-bridge circuit that supplies power to the coil of the variable damping damper according to the duty cycle, and when the duty cycle becomes zero or less than a predetermined value, the H-bridge circuit switches the connection state of the coil and applies a reverse voltage to the coil for a predetermined time.

2. The control device for a variable damping force damper according to claim 1, characterized in that when the duty cycle becomes zero or less than or equal to a predetermined value, and the deviation between the target current and the actual current becomes greater than or equal to a predetermined value, a reverse voltage is applied to the coil for a predetermined time.

3. The control device for a variable damping force damper according to claim 1 or 2, characterized in that the predetermined time is set to 15 ms to 40 ms.

4. A control device for a variable damping force damper that controls the current of the coil of the variable damping force damper so that the actual current matches the target current, comprising an H-bridge circuit that supplies power to the coil of the variable damping force damper according to the duty cycle, and when the derivative value of the rising edge of the target current exceeds a predetermined value, the control device for a variable damping force damper inputs a rising duty cycle larger than the duty cycle determined according to the deviation between the target current and the actual current for a predetermined time.

5. The control device for a variable damping force damper according to claim 4, characterized in that the rise duty cycle is 100%.

6. The control device for a variable damping force damper according to any one of claims 1 to 5, characterized in that the variable damping force damper comprises a rotating body and a functional fluid that resists the rotation of the rotating body and whose viscosity changes due to a magnetic field generated by energizing a coil.

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