Electric power steering device, control device used in an electric power steering device, and control method

Abstract

A control device (100) used in an electric power steering apparatus (1000) comprising a motor (543) and configured to control driving of the motor (543), the control device (100) having the following features: a processor (200); and a memory (116) storing a program for controlling operation of the processor (200), wherein, according to the program, the processor (200) executes: Obtaining a steering torque detected by a steering torque sensor (541) and a vehicle speed detected by a vehicle speed sensor (300); Changing a gain and a phase to be applied to the steering torque according to a steering frequency when a driver operates a steering wheel (521); Determining a magnitude of an assist torque based on the steering torque to which the gain and phase have been applied and the vehicle speed; and Generating a torque setpoint to be used to control driving of the motor (543) based on the determined assist torque, wherein a vehicle on which the electric power steering apparatus (1000) is mounted allows settings of a plurality of driving mode types, and the processor (200) performs control to vary each degree of change of the gain and the phase according to the steering frequency depending on a driving mode type selected by the driver.

Description

TECHNICAL FIELDThe present disclosure relates to an electric power steering apparatus, a control device used in the electric power steering apparatus, and a control method.BACKGROUND ARTAn automobile equipped with an electric power steering apparatus (EPS) including an electric motor (hereinafter, simply referred to as a "motor") is widely used. The electric power steering apparatus is an apparatus that assists steering wheel operation of a driver by driving the motor. A steering wheel is also referred to as a handle in some cases.In recent years, an assist force of the electric power steering apparatus with respect to the steering by the driver has been required to have different steering characteristics depending on the type of the vehicle. Moreover, even for the same type of vehicle, it has been required to provide different steering characteristics depending on sex, age, driving experience, driving situation, and the like. As one of the techniques for improving the steering feeling of a driver, JP 6 131 208 B2 discloses a technique for performing a greater deceleration phase compensation on a torque signal as a steering angle increases.From DE 199 19 374 B4 a power steering device for an automobile is known, in which the steering is assisted by a power source, such as an electric motor.DE 10 2019 214 894 A1, which represents prior art under §3(2) PatG, relates to a steering control device for controlling a rotation angle of a motor that drives a steering mechanism according to a rotation angle of a steering wheel.A torque control unit for controlling a torque of the motor with the rotation angle of the steering wheel as a command value and a phase advance processing unit for performing feedback control on the torque of the motor with at least one of the rotation angle and the angular speed of the motor as a command value and advancing a phase of a waveform to be fed back for a partial frequency range including a resonance frequency of the motor and the steering mechanism in an entire frequency range are provided.DE 101 56 369 A1 discloses a control unit for an electric power steering system which supplies a steering assistance force to a steering system of a motor vehicle with the aid of a motor. A steering return control recognizes turning and turning back of a steering wheel, wherein information on a steering speed is used to calculate a current with which turning back of the steering wheel is controlled.DE 101 42 154 B4 relates to a control unit for an electric power steering system which applies a steering assistance force to a steering system of a motor vehicle or of another vehicle with the aid of a motor. A safe and comfortable steering behavior is to be made possible in that the influence of the motor inertia is eliminated and a continuous steering feel is provided.SUMMARY OF THE INVENTIONTECHNICAL PROBLEMSThere is a need for improvement in terms of a steering feel that is suitable for different driving situations.Embodiments of the present disclosure provide a control device and a control method for an electric power steering apparatus capable of improving the steering feeling of a driver. In addition, the embodiments of the present disclosure also provide an electric power steering apparatus including the control device.SOLUTIONS TO THE PROBLEMSThe problems are solved by a control device having the features of one of claims 1, 3 or 6, by an electric power steering apparatus having the features of claim 8 and by a control method having the features of one of claims 9, 10 or 11.ADVANTAGEOUS EFFECTS OF THE INVENTIONAccording to the illustrative embodiments of the present disclosure, the driver's steering feeling can be improved.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 schematically illustrates a configuration example of an electric power steering apparatus according to an embodiment. FIG. 2 is a block diagram illustrating a configuration example of a control device according to the embodiment. FIG. 3 is a functional block diagram illustrating functions mounted on a processor based on a functional block according to the present embodiment. FIG. 4 is a graph illustrating control for changing gain according to a steering frequency according to the present embodiment. FIG. 5 is a graph illustrating control for changing a phase according to the steering frequency according to the present embodiment. FIG. 6 is a view for describing the steering frequency according to the present embodiment. FIG. 7 is a graph illustrating a waveform of a steering characteristic as a simulation result according to the present embodiment. FIG. 8 is a graph illustrating a waveform of a steering characteristic as a simulation result according to the present embodiment. FIG. 9 is a graph illustrating a waveform of a steering characteristic as a simulation result according to the present embodiment.DESCRIPTION OF THE EMBODIMENTSAs described above, as one of the techniques for improving the steering feeling of a driver, a technique for performing a greater deceleration phase compensation on a torque signal as a steering angle increases is known. However, such a technique is advantageous in a situation where smooth driving feeling is required, for example, in a case where a comfort mode is selected as a driving mode, but not in a situation where an agile driving feeling is required, for example, in a sports mode.In recent years, not only a steering load felt by the driver such as "heavy" or "light" has been demanded, but also agility, for example, a vehicle that responds "soft" or "fast" to steering. In particular, steering characteristics such as "quick response at heavy steering load" and "smooth response at light steering load" are required. Embodiments of the present disclosure provide such steering characteristics.With reference to the accompanying drawings, a specific description will be given below of a control device and a control method for an electric power steering apparatus according to an embodiment of the present disclosure, and an electric power steering apparatus including the control device. However, in some cases, a specific description beyond the required level is omitted. For example, detailed descriptions of well-known facts and duplicate descriptions of substantially the same configurations may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding of those skilled in the art.The following embodiments are illustrative, and the control device and the control method for an electric power steering apparatus according to the present disclosure are not limited to the present embodiments. For example, the numerical values, the steps, the order of the steps, and the like illustrated in the following embodiments are illustrative only, and various modifications may be made as long as no technical inconsistencies occur. The embodiments described below are illustrative and various combinations are possible unless technical inconsistencies occur.1. Configuration of an electric power steering apparatusFIG. 1 is a diagram schematically illustrating a configuration example of an electric power steering apparatus 1000 according to the present embodiment.The electric power steering apparatus 1000 (hereinafter referred to as "EPS") includes a steering system 520 and an assist torque mechanism 540 that generates an assist torque. The EPS 1000 generates the assist torque for assisting a steering torque of the steering system generated when a driver operates a steering wheel. The assist torque reduces an operation load for the driver.The steering system 520 includes, for example, a steering wheel 521, a steering shaft 522, universal joints 523A and 523B, a rotation shaft 524, a rack and pinion mechanism 525, a rack shaft 526, left and right ball joints 552A and 552B, tie rods 527A and 527B, knuckle joints 528A and 528B, and left and right steered wheels 529A and 529B.The assist torque mechanism 540 includes, for example, a steering torque sensor 541, a steering angle sensor 542, an electronic control unit (ECU) 100 for automobiles, a motor 543, a deceleration gear 544, an inverter 545, and a torsion bar 546. The steering torque sensor 541 detects a steering torque in the steering system 520 by detecting the amount of torsion of the torsion bar 546. The steering angle sensor 542 detects a steering angle of the steering wheel.The ECU 100 generates a motor drive signal based on the detection signals detected by the steering torque sensor 541, the steering angle sensor 542, a vehicle speed sensor (not illustrated) mounted on the vehicle, or the like, and outputs the motor drive signal to the inverter 545. The inverter 545 converts direct current into three-phase alternating current having pseudo sine waves of the A phase, the B phase, and the C phase according to the motor drive signal, for example, and supplies the power to the motor 543. The motor 543 is, for example, a surface permanent-magnet synchronous motor (SPMSM) or a switched reluctance motor (SRM), and is supplied with the three-phase alternating current to generate an assist torque corresponding to the steering torque. The motor 543 transmits the generated assist torque to the steering system 520 via the deceleration gear 544. Hereinafter, the ECU 100 will be referred to as a control device 100 for the EPS.2. Configuration Example of Control Device 100FIG. 2 is a block diagram illustrating a typical example of a configuration of the control device 100 according to the present embodiment. The control device 100 includes, for example, a power supply circuit 111, an angle sensor 112, an input circuit 113, a processor 200, a communication interface 114, a driver circuit 115, a ROM 116. The control device 100 may be implemented as a printed circuit board (PCB) on which these electrical components are implemented.An on-vehicle vehicle speed sensor 300, the steering torque sensor 541, and the steering angle sensor 542 are electrically connected to the processor 200. The vehicle speed sensor 300, the steering torque sensor 541, and the steering angle sensor 542 transmit a vehicle speed v, a steering torque T tor and a steering angle θ, respectively, to the processor 200.The control device 100 is electrically connected to the inverter 545. The control device 100 controls switching operations of a plurality of switching elements (for example, MOS-FETs) included in the inverter 545. Specifically, the control device 100 generates control signals (hereinafter, referred to as "gate control signals") for controlling the switching operations of the respective switching elements, and outputs the gate control signals to the inverter 545.The control device 100 generates a torque command value based on the vehicle speed v, the steering torque T tor and a steering angle θ, and the like, and controls a torque and a rotation speed of the motor 543 by vector control, for example. The control device 100 can perform not only the vector control but also other control. The rotational speed is expressed by the number of revolutions (U / min) at which a motor rotates per unit time (for example, one minute or the number of revolutions U / sec) at which the rotor rotates per unit time (for example, one second). The vector control is a method in which a current flowing through the motor is divided into a current component contributing to generation of a torque and a current component contributing to generation of a magnetic flux, and the current components orthogonal to each other are independently controlled.The power supply circuit 111 is connected to an external power supply (not illustrated) and generates a DC voltage (for example, 3 V or 5 V) required for each block in the circuit.The angle sensor 112 is, for example, a resolver or a Hall shear IC. Alternatively, the angle sensor 112 is also realized by a combination of an MR sensor with a magnetoresistive (MR) element and a sensor magnet. The angle sensor 112 detects the rotation angle of the rotor and outputs the rotation angle of the rotor to the processor 200. The control device 100 may include a speed sensor and an acceleration sensor for detecting the rotational speed and the acceleration of the motor, instead of the angle sensor 112.The input circuit 113 receives a motor current value (hereinafter referred to as "current actual value") detected by a current sensor (not illustrated), converts a level of the current actual value into an input level for the processor 200 as needed, and outputs the current actual value to the processor 200. A typical example of the input circuit 113 is an analog-to-digital conversion circuit.The processor 200 is a semiconductor integrated circuit and is also referred to as a central processing unit (CPU) or a microprocessor. The processor 200 sequentially executes a computer program stored in the ROM 116, which is an example of a memory, and describes an instruction set for controlling motor drive, and performs desired processing. The processor 200 is widely interpreted as a term including a field programmable gate array (FPGA), a programmable specific integrated circuit (ASIC), or an application specific standard product (ASSP) with a CPU. The processor 200 sets a target current value according to, for example, the current actual value and the rotation angle of the rotor to generate a PWM signal, and outputs the PWM signal to the driving circuit 115.The communication interface 114 is an input / output interface configured to transmit and receive data in accordance with, for example, an in-vehicle control array network (CAN).The driver circuit 115 is typically a gate driver (or a pre-driver). The driver circuit 115 generates a gate control signal corresponding to the PWM signal, and outputs the gate control signal to gates of the plurality of switching elements included in the inverter 545. There is a case where a gate driver is not necessarily required when a drive target is a motor that can be driven at low voltage. In this case, the processor 200 may have the function of the gate driver.The ROM 116 is electrically connected to the processor 200. The ROM 116 is, for example, a writable memory (for example, a PROM), a rewritable memory (for example, a flash memory or an EEPROM), or a read-only memory.The ROM 116 stores a control program containing an instruction set that causes the processor 200 to control the motor drive. The control program is temporarily expanded in a RAM (not illustrated), for example, when booting.FIG. 3 is a functional block diagram illustrating functions implemented in the processor 200 in function block units. In the present application, the processor 200 includes a responsiveness phase compensation unit 210, a phase compensation variable processing unit 220, a base assist calculation unit 230, a stability phase compensation unit 240, a current control calculation unit 250, and a motor control unit 260. Typically, the processes (or tasks) of the function blocks corresponding to the respective units are described in the software module-based computer program and stored in the ROM 116. However, when an FPGA or the like is used, all or some of the function blocks may be implemented as hardware accelerators.In a case where each function block is implemented as software (or firmware) in the control device 100, a device that executes the software may be the processor 200. In one aspect, the control device according to the present disclosure includes the processor and a memory that stores a program that controls the operation of the processor. The processor executes the following processing in accordance with the program. (1) A steering torque detected by the steering torque sensor and a vehicle speed detected by the vehicle speed sensor are obtained. (2) A gain and a phase to be applied to the steering torque are changed according to a steering frequency when the driver operates the steering wheel. (3) The magnitude of an assist torque is determined based on the steering torque to which the gain and the phase have been applied and the vehicle speed. (4) A torque command value to be used to control driving of the motor is generated based on the determined assist torque.The processor 200 receives, as inputs, the steering torque T tor, which is detected by the steering torque sensor 541, the vehicle speed v, which is detected by the vehicle speed sensor, the steering angle θ, which is detected by the steering angle sensor, and a rotational speed ω of the motor. For example, in a case where the control device 100 includes a speed sensor that detects a rotation speed of the motor, the processor 200 may obtain the rotation speed ω of the motor by obtaining the detected rotation speed from the speed sensor. In a case where the control device 100 includes an angle sensor that detects a rotation angle (more specifically, a mechanical angle) of the motor, the processor 200 may obtain the rotation speed ω by obtaining the detected rotation angle of the rotor from the angle sensor and calculating an angular speed based on the rotation angle of the rotor.A control for changing the gain and the phase according to the steering frequency according to the present embodiment will be described with reference to FIGS. 4, 5, and 6.FIG. 4 is a graph illustrating control for changing the gain according to the steering frequency. FIG. 5 is a graph illustrating control for changing the phase according to the steering frequency. FIG. 6 is a view for describing the steering frequency. In the present embodiment, the gain and the phase to be applied to the steering torque are changed according to the steering frequency when the driver operates the steering wheel 521.The steering frequency will be described with reference to FIG. 6. FIG. 6 illustrates an automobile 1100 that changes lanes while traveling on a road and how the steering wheel 521 is operated at this time. The steering frequency is a frequency corresponding to a steering speed. For example, when the traveling lane is changed from the left to the right lane as illustrated in FIG. 6, the steering wheel 521 is turned to the right and then to the left to return to the neutral position. Such a process, in which the steering wheel 521 is rotated from the neutral position in one direction and then rotated back to the neutral position again, corresponds to a half cycle. In a case where the operation takes 2.5 seconds for the half cycle, one cycle takes 5 seconds and the steering frequency is 0.2 Hz.In the present embodiment, for example, when a condition that the steering frequency is 0.1 to 5.0 Hz, control is performed to change the gain and the phase according to the steering frequency. Note that the control for changing the gain and the phase according to the steering frequency can be similarly performed when the steering frequency is other than that described above.The automobile on which the electric power steering apparatus 1000 of the present embodiment is mounted may set a plurality of driving modes. For example, the plurality of driving mode types include a sport mode, a comfort mode, and a normal mode. The types and the number of driving modes are arbitrary, and the present embodiment is not limited thereto.The processor 200 performs control to change a steering feel of the steering wheel according to a driving mode type selected by the driver. For example, in a case where the sport mode is selected, the driver is given a steering feeling that responds quickly although the steering load is heavy. Moreover, for example, in a case where the comfort mode is selected, the driver is given a steering feeling that responds smoothly although the steering load is light.In FIG. 4, the vertical axis represents the gain and the horizontal axis represents the steering frequency. In FIG. 5, the vertical axis represents the phase and the horizontal axis represents the steering frequency. The processor 200 varies the degree of change for each of the gain and the phase according to the steering frequency depending on the driving mode type selected by the driver. For example, in the case where the sport mode is selected, the processor 200 executes control to increase the gain and advance the phase as the steering frequency increases. On the other hand, in the case where the comfort mode is selected, the processor 200 performs control to reduce the gain and retard the phase as the steering frequency increases. As a result, a desired steering feeling corresponding to the driving mode is given to the driver.Referring to FIG. 3, the responsiveness phase compensation unit 210 receives, as inputs, the steering torque T tor, the steering angle θ, and an output signal of the phase compensation variable processing unit 220. The responsiveness phase compensation unit 210 adjusts the assist gain within a possible range of the steering frequency (for example, 0.1 to 5.0 Hz) to compensate for the strength of the torsion bar 546. For example, the responsiveness phase compensation unit 210 calculates a first-order phase compensation represented by the following (Formula 1), and applies the first-order phase compensation to the steering torque T tor. Expression 1Here, f 1 is a frequency of the zero point, and f 2 is a frequency of the pole. A Laplace operator is represented by s. The responsiveness phase compensation unit 210 changes the gain and the phase using the calculated first-order compensation C(s).The phase compensation variable processing unit 220 receives the vehicle speed v as an input. The phase compensation variable processing unit 220 changes values of the frequency f 1 of the zero point and the frequency f 2 of the pole according to the vehicle speed v. For example, the ROM 116 stores a look-up table defining a relationship among the vehicle speed v, the frequency f 1 of the zero point, and the frequency f 2 of the pole. The look-up table changes the values of the frequency f 1 of the zero point and the frequency f 2 of the pole according to the vehicle speed v. The value of the frequency f 1 of the zero point and the value of the frequency f 2 of the pole are set to lower values, for example, while the value of the vehicle speed v increases.The phase compensation variable processing unit 220 outputs the changed values of the frequency f 1 of the zero point and the frequency f 2 of the pole to the responsiveness phase compensation unit 210. The responsiveness phase compensation unit 210 performs the calculation of the above (Formula 1) using the obtained values of the frequency f 1 of the zero point and the frequency f 2 of the pole. As a result, the amount of first-order compensation C(s) changes according to the vehicle speed v.For example, the assist gain in a frequency band increases by leading the phase by performing phase lead compensation so that the torsion of the torsion bar 546 decreases, and the rigidity of the torsion bar 546 can be increased. In addition, the assist gain decreases in a frequency band in which the phase is delayed by performing phase lag compensation, so that the torsion of the torsion bar 546 increases, and the rigidity of the torsion bar 546 can be decreased.Moreover, the responsiveness phase compensation unit 210 calculates the steering frequency from a change in the magnitude of the obtained steering angle θ. The responsiveness phase compensation unit 210 varies the degree of change for each of gain and phase according to the steering frequency depending on the driving mode type selected by the driver, as described with reference to FIGS. 4 and 5. For example, in the case where the sport mode is selected, the responsiveness phase compensation unit 210 increases the gain and advances the phase as the steering frequency increases. On the other hand, in the case where the comfort mode is selected, the responsiveness phase compensation unit 210 decreases the gain and lags the phase as the steering frequency increases. In the normal mode, such gain and phase matching is not performed, and predetermined gain and phase compensation is adopted.For example, the ROM 116 stores a plurality of types of lookup tables each having different content per driving mode and defining a relationship among the steering frequency, gain, and phase. The responsiveness phase compensation unit 210 changes the gain and the phase by a look-up table depending on the selected driving mode.The responsiveness phase compensation unit 210 applies the adopted gain and phase compensation to the steering torque T tor to generate a steering torque T kom. The responsiveness phase compensation unit 210 outputs the steering torque T kom to the base assist calculation unit 230.The basic assist calculation unit 230 calculates an assist amount serving as a basis for reducing a steering drive load for the driver based on the phase compensated steering torque T kom and the vehicle speed v. The basic assist calculation unit 230 obtains the steering torque T kom and the vehicle speed v as inputs, and generates and outputs a basic assist torque T BASIS based on these signals.In addition, the ROM 116 also stores a look-up table defining a relationship between the steering torque T kom, the vehicle speed v, and the base assist torque T BASIS. The base assist calculation unit 230 determines the base assist torque T BASIS using such a lookup table.The stability phase compensation unit 240 receives the basic assist torque T BASIS as an input. The stability phase compensation unit 240 ensures a phase margin near a gain transition frequency by the phase lead compensation to ensure stability with respect to a base assist gain. The stability phase compensation unit 240 performs stability compensation on the base assist torque T BASIS to generate a stability compensation torque. The stability phase compensation unit 240 outputs the stability compensation torque as a torque target value T ref.The current control calculation unit 250 generates a current command value I ref based on the torque command value T ref. The motor control unit 260 sets a target current value based on the current command value I ref by vector control, for example, to generate a PWM signal, and outputs the PWM signal to the driving circuit 115.By the above-described control, for example, severe and rapid steering characteristics of the sport mode can be realized. In addition, for example, light and smooth steering characteristics of the comfort mode can be realized.The inventor of the present invention has checked the validity of the control device 100 according to the present embodiment by simulation. FIGS. 7, 8, and 9 illustrate graphs of steering characteristics as simulation results. FIG. 7 illustrates the simulation result in the sport mode. FIG. 8 illustrates the simulation result in the comfort mode. FIG. 9 illustrates the simulation result in the normal mode.As simulation conditions, the steering angle θ was set to ±80 [degrees] and the steering frequency was set to 0.25 [Hz]. Moreover, the frequency f 1 of the zero point and the frequency f 2 of the pole were set to 0.7 [Hz] and 0.5 [Hz], respectively, in the comfort mode. The frequency f 1 of the zero point and the frequency f 2 of the pole in the sport mode were set to 0.5 [Hz] and 0.7 [Hz], respectively. In the normal mode, the first-order compensation described above has not been applied.In each of FIGS. 7, 8, and 9, the vertical axis represents the steering torque [N·m], and the horizontal axis represents the steering angle [deg].Referring to the Lissajous waveforms of the angular force illustrated in FIGS. 7, 8, and 9, it can be seen that the steering torque is larger in the sport mode than in the normal mode and that an inclination of the steering torque sin relation to the steering angle is steep. It will be appreciated that the heavy and fast steering characteristics can be realized in the sport mode of the present embodiment. It is recognized that the steering torque in the comfort mode is smaller than in the normal mode, and that an inclination of the steering torque with respect to the steering angle is smooth. It will be appreciated that the light and smooth steering characteristics can be realized in the comfort mode of the present embodiment.INDUSTRIAL APPLICABILITYEmbodiments of the present disclosure can be applied to a control device for controlling an electric power steering apparatus mounted in a vehicle.LIST OF REFERENCE CHARACTERS100 Control device (ECU) 116 ROM 200 Processor 210 Responsiveness phase compensation unit 220 Phase compensation variable processing unit 230 Basic assist calculation unit 240 Stability phase compensation unit 250 Current control calculation unit 260 Motor control unit 1000 Electric power steering apparatus

Claims

A control device (100) used in an electric power steering apparatus (1000) including a motor (543), and configured to control driving of the motor (543), the control device (100) comprising: a processor (200); and a memory (116) storing a program for controlling an operation of the processor (200), wherein, according to the program, the processor (200) executes: obtaining a steering torque detected by a steering torque sensor (541) and a vehicle speed detected by a vehicle speed sensor (300); changing a gain and a phase to be applied to the steering torque according to a steering frequency when a driver operates a steering wheel (521); determining a magnitude of an assist torque based on the steering torque to which the gain and the phase have been applied and the vehicle speed; and generating a torque command value to be used to control driving of the motor (543) based on the determined assist torque, wherein a vehicle to which the electric power steering apparatus (1000) is mounted allows settings of a plurality of driving mode types, and the processor (200) performs control to vary each change degree of the gain and the phase according to the steering frequency depending on a driving mode type selected by the driver.The control device (100) according to claim 1, wherein the plurality of driving mode types include a first driving mode and a second driving mode, and the processor (200) performs control to increase the gain and advance the phase while the steering frequency increases when the first driving mode is selected, and performs control to decrease the gain and retard the phase while the steering frequency increases when the second driving mode is selected.A control device (100) used in an electric power steering apparatus (1000) including a motor (543), and configured to control driving of the motor (543), the control device (100) comprising: a processor (200); and a memory (116) storing a program for controlling an operation of the processor (200), wherein, according to the program, the processor (200) executes: obtaining a steering torque detected by a steering torque sensor (541) and a vehicle speed detected by a vehicle speed sensor (300); changing a gain and a phase to be applied to the steering torque according to a steering frequency when a driver operates a steering wheel (521); determining a magnitude of an assist torque based on the steering torque to which the gain and the phase have been applied and the vehicle speed; and generating a torque command value to be used to control driving of the motor (543) based on the determined assist torque, wherein when f 1 is a frequency of a zero point and f 2 is a frequency of a pole, the processor (200) calculates a first-order compensation C(s) represented by (Formula 1): C (s)=1 ω 1 s+1 ω 2 s+1 ω 1=1 2 π f 1 ω 2=1 2 π f 2 changes the gain and the phase using the first-order compensation C(s).The control device (100) according to claim 3, wherein the processor (200) changes values of the frequency f 1 of the zero point and the frequency f 2 of the pole according to the vehicle speed.The control device (100) according to claim 3 or 4, wherein the processor (200) changes values of the frequency f 1 of the null point and the frequency f 2 of the pole according to the vehicle speed using a table defining a relationship among the vehicle speed, the frequency f 1 of the null point, and the frequency f 2 of the pole.A control device (100) used in an electric power steering apparatus (1000) including a motor (543), and configured to control driving of the motor (543), the control device (100) comprising: a processor (200); and a memory (116) storing a program for controlling an operation of the processor (200), wherein, according to the program, the processor (200) executes: obtaining a steering torque detected by a steering torque sensor (541) and a vehicle speed detected by a vehicle speed sensor (300); changing a gain and a phase to be applied to the steering torque according to a steering frequency when a driver operates a steering wheel (521); determining a magnitude of an assist torque based on the steering torque to which the gain and the phase have been applied and the vehicle speed; and generating a torque command value to be used to control driving of the motor (543) based on the determined assist torque, wherein the processor (200) performs control to change the gain and the phase according to the steering frequency when the steering frequency is 0.1 to 5.0 Hz.The control device (100) according to any one of claims 1 to 6, wherein the processor (200) further performs stability compensation on the determined assist torque to generate stability compensation torque.An electric power steering apparatus (1000) comprising: a motor (543); a steering torque sensor (541); and the control device (100) according to any one of claims 1 to 7.A control method used in an electric power steering apparatus (1000) including a motor (543) and configured to control driving of the motor (543), the control method comprising the steps of: obtaining a steering torque detected by a steering torque sensor (541) and a vehicle speed detected by a vehicle speed sensor (300); changing a gain and a phase to be applied to the steering torque according to a steering frequency when a driver operates a steering wheel (521); determining a magnitude of an assist torque based on the steering torque to which the gain and the phase have been applied and the vehicle speed; and generating a torque command value to be used to control driving of the motor (543) based on the determined assist torque, wherein a vehicle on which the electric power steering apparatus (1000) is mounted allows settings of a plurality of driving mode types, and wherein each change degree of the gain and the phase is varied according to the steering frequency depending on a driving mode type selected by the driver.A control method used in an electric power steering apparatus (1000) including a motor (543) and configured to control driving of the motor (543), the control method comprising the steps of: obtaining a steering torque detected by a steering torque sensor (541) and a vehicle speed detected by a vehicle speed sensor (300); changing a gain and a phase to be applied to the steering torque according to a steering frequency when a driver operates a steering wheel (521); determining a magnitude of an assist torque based on the steering torque to which the gain and the phase have been applied and the vehicle speed; generating a torque command value to be used to control driving of the motor (543) based on the determined assist torque, wherein when f 1 is a frequency of a zero point and f 2 is a frequency of a pole, first-order compensation C(s) represented by (Formula 1) is calculated: C (s)=1 ω 1 s+1 ω 2 s+1 ω 1=1 π f 1 ω 2=1 2 π f 2 the gain and the phase are changed using the first-order compensation C(s).A control method used in an electric power steering apparatus (1000) including a motor (543) and configured to control driving of the motor (543), the control method comprising the steps of: obtaining a steering torque detected by a steering torque sensor (541) and a vehicle speed detected by a vehicle speed sensor (300); changing a gain and a phase to be applied to the steering torque according to a steering frequency when a driver operates a steering wheel (521); determining a magnitude of an assist torque based on the steering torque to which the gain and the phase have been applied and the vehicle speed; generating a torque command value to be used to control driving of the motor (543) based on the determined assist torque, wherein the gain and the phase are changed according to the steering frequency when the steering frequency is 0.1 to 5.0 Hz.

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