ENGINE CONTROL DEVICE, CONTROL METHOD, ENGINE MODULE AND ELECTRIC SERVOIR DEVICE

Abstract

A control device (100) used in an electric power steering device (1000) including a motor with n-phase windings (n is an integer of three or more), for controlling the motor, in which an n-phase power supply control for supplying power to the n-phase windings or an n-1-phase power supply control for supplying power to n-1-phase windings can be implemented, wherein the control device (100) comprises the following: a processor (200); and a memory (116) which stores a program for controlling an operation of the processor (200), wherein The processor (200) performs the following according to the program: Switching from n-phase power supply control to n-1-phase power supply control in response to a switching signal, Capturing a torque command value (T) ref ), an electric angle (θm ) of the motor and an actual current value (I m ) of the engine, Generating a pre-current command value (I Pref ) based on the torque command value (T ref ), of the electric angle (θ m ) of the motor and the actual current value of the motor (I m ), which have been recorded, Generating a current command value (I ref ) by applying a jitter control to the pre-current command value (I Pref ) in a dead-point region of an electric angle range from 0 to 2π, and Performing n-1-phase power supply control based on the current command value (I ref ).

Description

[0001] The present invention relates to a motor control device, a control method, a motor module and an electric power steering device.

[0002] A typical passenger car is equipped with an electric power steering system (EPS), which includes an electric motor (hereinafter referred to simply as the "motor") and a motor control unit. The electric power steering system is a device that assists the driver's steering input by driving or controlling the motor.

[0003] A technique has already been developed to assist the driver's steering by continuing motor operation or control even in the event of a fault in a part of the motor or an inverter integrated into the electric power steering system. Examples of such faults include a broken motor winding or a failure of a switching element within the inverter. If such a fault only affects the power supply to a specific winding, it is possible to continue motor operation by continuously supplying power to the remaining normal windings.

[0004] Japanese patent JP 5 029 312 B2 discloses an electric power steering device capable of continuing assistance by performing a normal power supply control to conduct windings of three phases and a power supply control to energize the remaining normal windings of two phases in the event of a power supply failure in one phase of a motor's windings. In this electric power steering device, the motor's angular velocity increases by performing acceleration control within a deceleration range, thereby reducing the steering speed when the generated motor torque falls below a target assistance force value. Accordingly, it is possible to reduce steering instability perceived by the driver within this deceleration range.

[0005] If a fault occurs in a motor or inverter, it is desirable to improve the steering feel perceived by a driver when the assistance of the driver's steering wheel operation continues.

[0006] The object of the present invention is to create a control device, a motor module, an electric power steering device and a control method with improved characteristics.

[0007] This problem is solved by a control device according to claim 1, a motor module according to claim 10, an electric power steering device according to claim 11, and a control method according to claim 12. Advantageous embodiments are described in the dependent claims.

[0008] Exemplary embodiments of the present disclosure provide a motor control device that can improve a steering feel perceived by a driver when switching from a power supply control for supplying energy to n-phase windings to a power supply control for supplying energy to n-1-phase windings, a motor module comprising the control device, an electric power steering device comprising the motor module, and a motor control method.

[0009] In a non-limiting and exemplary embodiment, a control device of the present disclosure is a control device used in an electric power steering system including a motor with n-phase windings (n being an integer of three or more) for controlling the motor. An n-phase power supply controller for supplying energy to the n-phase windings or an n-1-phase power supply controller for supplying energy to n-1-phase windings can be implemented. The device comprises: a processor; and a memory that stores a program for controlling the operation of the processor.The processor performs the following actions according to the program: switching from n-phase power supply control to n-1-phase power supply control in response to a switching signal, acquiring a torque command value, an electrical angle of the motor, and an actual current value of the motor, generating a pre-current command value based on the acquired torque command value, electrical angle of the motor, and actual current value of the motor, generating a current command value by applying jitter control to the pre-current command value in a dead-point region of an electrical angle range from 0 to 2π, and performing the n-1-phase power supply control based on the current command value.

[0010] In a non-limiting and exemplary embodiment, a motor module of the present disclosure comprises a motor and the control device described above.

[0011] In a non-limiting and exemplary embodiment, an electric power steering device of the present disclosure comprises the motor module described above.

[0012] In a non-limiting and exemplary embodiment, a control method of the present disclosure is a control method used in an electric power steering device including a motor with n-phase windings (n is an integer of three or more) for controlling the motor. An n-phase power supply control for supplying energy to the n-phase windings or an n-1-phase power supply control for supplying energy to n-1-phase windings can be implemented.The procedure comprises: switching from n-phase power supply control to n-1-phase power supply control in response to a switching signal; acquiring a torque command value, an electrical angle of the motor, and an actual current value of the motor; generating a pre-current command value based on the acquired torque command value, electrical angle of the motor, and actual current value of the motor; generating a current command value by applying jitter control to the pre-current command value in a dead-point region of an electrical angle range from 0 to 2π; and performing n-1-phase power supply control based on the current command value.

[0013] According to an exemplary embodiment of the present disclosure, a motor control device that can improve a steering feel perceived by a driver when switching from a power supply control for supplying energy to n-phase windings to a power supply control for supplying energy to n-1-phase windings is provided, a motor module comprising the control device, an electric power steering device comprising the motor module, and a motor control method.

[0014] Preferred embodiments of the present invention are explained in more detail below with reference to the accompanying drawings. These show: Fig. 1 a diagram for the schematic illustration of a configuration example of an electric power steering device according to an embodiment of the present disclosure; Fig. 2 a block diagram illustrating a typical example of a configuration of a control device according to the embodiment of the present disclosure; Fig. 3 a functional block diagram illustrating exemplary functional blocks of a processing operation performed by a processor of the control device according to the embodiment of the present disclosure; Fig. 4 a function block diagram illustrating a configuration example of a torque unit; Fig. 5 a function block diagram illustrating a configuration example of a power control unit; Fig. 6 a function block diagram illustrating a configuration example of a current command value calculation unit; Fig. 7A a diagram illustrating, by way of example, a phase current waveform through a two-phase power supply control at the time of a U-phase failure; Fig. 7B a diagram illustrating an example of an engine torque waveform through the two-phase power supply control at the time of a U-phase failure; Fig. 8 a diagram illustrating an example of a tremor current waveform according to the embodiment of the present disclosure; Fig. 9 a diagram illustrating a tremor current waveform in a comparative example; Fig. 10 a diagram illustrating, by way of example, the tremor current waveform used for tremor control; Fig. 11 a diagram illustrating, by way of example, a phase current waveform after the application of jitter control to a phase current in which flutter occurs; Fig. 12 a diagram illustrating measurement results of a steering angle and a steering torque in a case where the jitter control is not applied; and Fig. 13 a diagram illustrating measurement results of the steering angle and steering torque in a case where the jitter control is applied.

[0015] As a result of a review by the inventors of the present invention, it was found that in a case where a steering wheel angle must be maintained in the deceleration range, as disclosed in Japanese patent JP 5 029 312 B2, fluttering (or chattering) occurs in the motor current, causing the motor torque to vibrate and consequently resulting in vibration at the steering wheel. This undesirable vibration impairs the steering feel perceived by the driver. Even when the acceleration control disclosed in Japanese patent JP 5 029 312 B2 is implemented, it is difficult to prevent this deterioration.

[0016] The inventors of the present invention have discovered that the deterioration of steering feel can be reduced by applying a jitter control (or dither control) to a calculation of a current command value, and have completed the present invention.

[0017] In the following, exemplary embodiments of a motor control device mounted on an electric power steering system, a control method, a motor module comprising the control device, and the electric power steering system comprising the motor module are described in detail below with reference to the accompanying drawings, as disclosed herein. However, unnecessarily detailed descriptions may be omitted. For example, detailed descriptions of known items and duplicate descriptions of essentially the same configuration may be omitted. This is to avoid unnecessary redundancy in the present description and to facilitate understanding by those skilled in the art.

[0018] The following embodiments are for illustrative purposes only, and the motor control device attached to the electric power steering system and the control method according to the present invention are not limited to the following embodiments. For example, the numerical values, steps, sequence of steps, and the like illustrated in the following embodiments are merely illustrative, and various modifications may be made unless a technical inconsistency arises. The embodiments described below are for illustrative purposes, and various combinations are possible unless a technical inconsistency arises. 1. Configuration of an electric power steering system 1000

[0019] Fig. Figure 1 is a diagram that schematically illustrates a configuration example of an electric power steering device 1000 according to the present embodiment.

[0020] The electric power steering system 1000 (hereinafter referred to as "EPS") comprises a steering system 520 and an assist torque mechanism 540, which generates an assist torque. The EPS 1000 generates the assist torque to support the torque of the steering system, which is generated when a driver operates a steering wheel. The assist torque reduces the driver's operating load.

[0021] The steering system 520 includes, for example, a steering wheel 521, a steering shaft 522, universal connectors 523A and 523B, a pivot shaft 524, a rack and pinion mechanism 525, a toothed shaft 526, a right and a left ball joint 552A and 552B, tie rods 527A and 527B, joints 528A and 528B, and a right and a left steered wheel 529A and 529B.

[0022] The support torque mechanism 540 comprises, for example, a steering torque sensor 541, a steering angle sensor 542, an electronic control unit (ECU) / control device 100 for passenger cars, a motor 543, a delay gear 544, an inverter 545, and a torsion bar 546. The steering torque sensor 541 detects steering torque in the steering system 520 by detecting a torsional force of the torsion bar 546. The steering angle sensor 542 detects the steering angle of the steering wheel. Furthermore, the steering torque can be an estimated value derived from a calculation and need not be a value from the steering torque sensor. The steering angle can also be calculated based on the output value of the angle sensor.

[0023] The ECU / control device 100 generates a motor drive signal based on detection signals received from the steering torque sensor 541, the steering angle sensor 542, a vehicle speed sensor (not illustrated), or the like, and outputs the motor drive signal to the inverter 545. For example, the inverter 545 converts DC power into three-phase AC power with U-phase, V-phase, and W-phase pseudosine waves according to the motor drive signal 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 the three-phase AC power is supplied to it to generate an assist torque corresponding to the steering torque.The motor 543 transmits the generated support torque to the steering system 520 via the delay gear 544. Hereinafter, the ECU 100 is referred to as the control device 100 for the EPS.

[0024] The control device 100 and the motor are modular and are manufactured and sold as a motor module. The motor module comprises the motor and the control device 100 and is used accordingly for the EPS. Alternatively, the control device 100 can be manufactured and sold as a control unit for controlling the EPS independently of the motor. 2. Configuration example of a control device 100

[0025] Fig. Figure 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 comprises, for example, a power supply circuit 111, an angle sensor 112, an input circuit 113, a communication interface 114, a driver circuit 115, a ROM (read-only memory) / memory 116, and a processor 200. The control device 100 can be implemented as a printed circuit board (PCB) on which these electronic components are implemented.

[0026] A vehicle speed sensor 300, a steering torque sensor 541, and a steering angle sensor 542, all mounted on the vehicle, are electrically connected to the processor 200. The vehicle speed sensor 300, the steering torque sensor 541, and the steering angle sensor 542 transmit vehicle speed, steering torque, and steering angle, respectively, to the processor 200.

[0027] The control device 100 is electrically connected to the inverter 545 (see Fig. 1) The control device 100 controls the switching operations of a plurality of switching elements (for example, MOSFETs) contained in the inverter 545. Specifically, the control device 100 generates control signals (hereinafter referred to as "gate control signals") to control the switching operations of the respective switching elements and outputs the gate control signals to the inverter 545.

[0028] The control device 100 generates a torque command value based on a torsional torque or the like and controls the torque and speed of the motor 543, for example, by vector control. The control device 100 can perform not only vector control but also other control methods. The speed is expressed as the number of revolutions (rpm) of a rotor per unit of time (for example, one minute) or, in other words, the number of revolutions (rpm) of the motor per unit of time (for example, one second). Vector control is a method in which a current flowing through the motor is divided into a current component that contributes to generating torque and a current component that contributes to generating magnetic flux, and the mutually orthogonal current components are controlled independently.

[0029] Power supply circuit 111 is connected to an external power supply (not illustrated) and generates a DC voltage required for each block in the circuit. The DC voltage to be generated is, for example, 3 V or 5 V.

[0030] The angle sensor 112 is, for example, a rotary encoder or a Hall-effect IC. Alternatively, the angle sensor 112 can also be implemented by a combination of an MR sensor with a magnetoresistive element (MR element) and a sensor magnet. The angle sensor 112 detects the rotation angle of the rotor and outputs the rotation angle to the processor 200. The control device 100 can include a speed sensor and an acceleration sensor for detecting the rotational speed and acceleration of the motor instead of the angle sensor 112.

[0031] The input circuit 113 receives a motor current value (hereinafter referred to as the "actual current value") detected by a current sensor (not illustrated), converts the level of the actual current value into the input level for the processor 200 as needed, and outputs the actual current value to the processor 200. A typical example of the input circuit 113 is an analog-to-digital conversion circuit.

[0032] The Processor 200 is an integrated semiconductor circuit, also known as a central processing unit (CPU) or microprocessor. The Processor 200 sequentially executes a computer program stored in ROM / memory 116, which describes an instruction set for controlling a motor drive and performs the desired processing. The term "Processor 200" is widely interpreted as encompassing a field-programmable gate array (FPGA), an application-specific integrated circuit (ASIC), or an application-specific standard product (ASSP) to which a CPU is attached. The Processor 200 sets a current instruction value according to the actual current value, the rotor's angle of rotation, and similar parameters, generates a pulse-width modulation (PWM) signal, and outputs the PWM signal to the driver circuit 115.

[0033] The communication interface 114, for example, is an input / output interface for sending / receiving data in accordance with a control area network (CAN, Control Area Network) in the vehicle.

[0034] The driver circuit 115 is typically a gate driver (or a pre-driver). Based on the PWM signal, the driver circuit 115 generates a gate control signal and outputs this signal to the gates of the multiple switching elements contained in the inverter 545. If the target drive is a motor that can be driven or controlled at a low voltage, the gate driver is not necessarily required. In this case, the gate driver functionality can be implemented in the processor 200.

[0035] The ROM / memory 116 is electrically connected to the processor 200. The ROM / memory 116 can be, for example, writable memory (such as a PROM), rewritable memory (such as flash memory or an EEPROM), or read-only memory. The ROM / memory 116 stores a control program, including an instruction set, to cause the processor 200 to control a motor drive. For example, the control program is temporarily extended to a RAM (not illustrated) at startup.

[0036] Fig. Figure 3 is a functional block diagram illustrating, by way of example, functional blocks of processes (or tasks) that are executed by the processor 200 of the control device 100 according to the exemplary embodiment of the present disclosure. The processor 200 in the exemplary embodiment of the present disclosure can be implemented by a plurality of functional blocks, including a torque control unit 210 and a current control unit 220.

[0037] A torsional torque T detected by the steering torque sensor 541 to is fed into the torque control unit 210. The torque control unit 210 generates a torque command value T. ref based on the torsional torque T tor .

[0038] The motor according to the present embodiment is a three-phase motor in which the windings are connected in a star configuration. Phase currents flowing through the U-phase, the V-phase, and the W-phase are measured by the current sensor as actual current values ​​I. m detected. The actual current value I m , an electric angle θ m of the motor and the torque command value T ref are entered into the power control unit 220. The power control unit 220 calculates load command values. u Last v and load v for the U, V or W phase based on the actual current value I m , of the electric angle θ m of the motor and the torque command value T ref and outputs the calculated values ​​to the driver circuit 115. The functions of the torque control unit 210 and the current control unit 220 will be described in detail later.

[0039] The processing of each functional block is usually described in a computer program in units of software modules and stored in ROM / memory 116. If an FPGA or similar device is used, all or parts of these functional blocks can be implemented as hardware accelerators.

[0040] If each functional block is implemented as software (or firmware) in the control device 100, the processor 200 can be a device that executes the software. In one aspect, the motor control device according to the present disclosure comprises the processor 200 and a memory 116 that stores a program for controlling the operation of the processor 200.The Processor 200 performs the following actions according to the program: (1) switching from three-phase power supply control to two-phase power supply control in response to a switching signal, (2) acquiring a torque command value, an electrical angle of the motor, and an actual current value of the motor, (3) generating a pre-current command value based on the acquired torque command value, electrical angle of the motor, and actual current value of the motor, (4) generating a current command value by applying jitter control to the pre-current command value in a dead-point region of an electrical angle range (or phase angle range) from 0 to 2π, and (5) performing the two-phase power supply control based on the current command value.

[0041] If each functional block is implemented as software and / or hardware in the control device 100, then, according to another aspect of the present disclosure, the control device 100 switches from three-phase power supply control to two-phase power supply control in response to a switching signal output by a failure detection unit 224 and performs the two-phase power supply control based on a current command value calculated by a current command value calculation unit 221, which is contained in the current control unit 220.The current command value calculation unit 221 comprises a pre-current command value calculation unit 221a, which detects a torque command value, an electrical angle of the motor and an actual current value of the motor and generates a pre-current command value based on the detected torque command value, electrical angle of the motor and actual current value of the motor, and a jitter control unit 221b, which generates a current command value by applying jitter control to the pre-current command value in a dead-point region of an electrical angle range of 0 to 2π.

[0042] Fig. Figure 4 is a function block diagram illustrating a configuration example of the torque control unit 210.

[0043] In the illustrated example, the torque control unit 210 comprises a response sensitivity phase control unit 211, a basic support calculation unit 212, a stability phase compensation unit 213, a torque difference compensation unit 214, and an addition device 215.

[0044] The response sensitivity phase control unit 211 provides a support boost within a possible range of steering frequencies when the driver operates the steering wheel and compensates for the stiffness of the torsion bar. In the present embodiment, one example of the aforementioned range is 5 Hz or less. The response sensitivity phase control unit 211 detects the torsional torque T tor The response sensitivity phase control unit 211 generates a response sensitivity phase compensation torque T rc by applying first-order phase compensation to the torsional torque Ttor , if the steering frequency is 5 Hz or less. First-order phase compensation is represented by a transfer function of a mathematical equation according to Equation 1. C(s)=12πf1s+112πf2s+1

[0045] Here, s is a Laplace transform, f1 is a frequency (Hz) used to determine the zero point of the transfer function, and f2 is a frequency (Hz) used to determine the pole of the transfer function. A diagram in which the gain (or loop gain) is defined as the vertical axis and the logarithm of the frequency is defined as the horizontal axis is called a gain diagram. In the gain diagram, the zero point is the intersection of the gain curve and the horizontal axis, indicating 0 dB, and the pole is the maximum point of the gain curve. By setting the pole frequency higher than the zero point frequency, for example, phase anticipation compensation can be applied. The greater the interval between the frequencies, the greater the magnitude of the phase anticipation.

[0046] The basic support calculation unit 212 records the response sensitivity phase compensation torque T rc and a vehicle speed v as input data. The basic support calculation unit 212 generates a basic support torque T. ba based on the response sensitivity phase compensation torque T rc and the vehicle speed v. For example, the basic support calculation unit 212 may have a look-up table (LUT) that provides a correspondence between the response sensitivity phase compensation torque T rc , the vehicle speed v and the basic support torque T ba The basic support calculation unit 212 can define the basic support torque T. ba in the correspondence relationship based on the response sensitivity phase compensation torque T rcand the vehicle speed v with reference to the LUT. Furthermore, the basic support calculation unit 212 can determine a basic support gain k based on a rise that is determined by a ratio of a deviation amount of the basic support torque T. ba to a deviation amount of the response sensitivity phase compensation torque T rc is defined.

[0047] The stability phase compensation unit 213 detects the basic support torque T ba and the basic support gain k as input data. The stability phase compensation unit 213 generates a stability phase compensation torque T. Sc based on the basic support torque T ba and the basic support gain k. The stability phase compensation unit 213 can apply a stability phase compensation to the basic support torque T. baFor example, this can be achieved by using a stabilization compensator. The stabilization compensator can have a second-order or higher-order transfer function, with a frequency response variable according to the basic support gain k. The second-order or higher-order transfer function is expressed using a response sensitivity parameter ω and an attenuation parameter ζ. The second-order or higher-order transfer function can be expressed, for example, by a mathematical equation according to Equation 2. By setting the order of the transfer function to two, attenuation can be applied to the transfer function's characteristic. A phase characteristic can be set by changing the attenuation. Csc(s)=s2+2ζ1ω1s+ω12s2+2ζ2ω2s+ω22(ω22ω12)

[0048] Here, s is a Laplace transform, ω1 is the zero-point frequency, ω2 is the pole frequency, ζ1 is the zero-point attenuation, and ζ2 is the pole attenuation. In the gain diagram, the zero point denotes the intersection of the gain curve and the horizontal axis, representing 0 dB, and the pole denotes the maximum point of the gain curve. The pole frequency ω2 is lower than the zero-point frequency ω1.

[0049] The torque difference compensation unit 214 calculates a differential compensation torque T dc based on the rate of change of the torsional torque T tor The torque difference compensation unit 214 can compensate the differential torque T dc For example, it can be calculated based on a transfer function represented by a mathematical equation according to Equation 3. Here, T is a time constant. G(s)=s1+Ts

[0050] The addition device 215 generates the torque command value T ref based on the stability phase compensation torque T Sc and the differential compensation torque T dc In particular, the addition device 215 adds the differential compensation torque T dc to the stability phase compensation torque T Sc to add the torque command value T ref to produce.

[0051] According to the torque control unit 210 described above, the response sensitivity of the motor torque to the torsional torque can be extended by applying torque differential compensation and phase advance compensation. Consequently, a rapid deviation in the motor torque, which can occur after a dead center described later, can be reduced, and the steering feel can be improved.

[0052] Fig. Figure 5 is a function block diagram illustrating a configuration example of the power control unit 220. Fig. Figure 6 is a block diagram illustrating a configuration example of the current command value calculation unit 221.

[0053] In the illustrated example, the current control unit 220 comprises the current command value calculation unit 221, a voltage command value calculation unit 222, a PWM modulation unit 223, and the failure detection unit 224. The current control unit 220 calculates a voltage command value V. ref based on the torque command value T ref For example, according to a vector control. The current control unit 220 generates a load command value, which is a PWM signal, based on the voltage command value V. ref and outputs the load command value "Load" to the driver circuit 115.

[0054] Based on the current command value I refThe power control unit 220 performs three-phase power supply control to supply power to windings of three phases in a controller in a normal state, and performs two-phase power supply control to supply power to windings of two phases from the three phases in a controller in an abnormal state.

[0055] First, a failure detection procedure is described for the present embodiment.

[0056] In the present embodiment, the current control unit 220 can supply energy to the motor windings according to a control mode that includes control in the normal state and control in the abnormal state. For example, the normal state refers to a state in which a fault such as a winding break, an open circuit, or a short-circuit failure of a switching element contained in an inverter does not occur. The abnormal state refers to a state in which the fault described above occurs.

[0057] The power control unit 220 can perform three-phase power supply control to power the three-phase windings when the control is selected in the normal state as the control mode, and can perform two-phase power supply control to power the two-phase windings when the control is selected in the abnormal state as the control mode.

[0058] The failure detection unit 224 monitors whether or not there is a winding among the three-phase windings that cannot be energized and detects a failure of the winding or of a switching element contained in the inverter. As an example of failure detection, the failure detection unit 224 can detect a failure of the winding or switching element for each phase based on any difference between the three-phase phase currents I. u , I v and I w and three-phase current command values ​​Iref_u , I ref_v and I ref_w detect. Each of the three-phase phase currents can, for example, be detected by a shunt resistor contained in one leg of each phase of the inverter. As another example of failure detection, the failure detection unit 224 can estimate a current value and indicate a failure phase. Alternatively, the failure detection unit 224 can detect a failure of the switching element by monitoring a drain-source voltage V. ds of the switching element (usually MOSFET) and comparison of a predetermined threshold voltage with V ds However, failure detection is not limited to the above methods and any known method in connection with fault detection can be used.

[0059] The failure detection is not necessarily performed by the processor 200, which is attached to the ECU (control device 100) for controlling the engine, and can, for example, be performed by a processor attached to another ECU which is connected to the processor 200 via the CAN.

[0060] The failure detection unit 224 generates a failure detection signal FD in response to the detection of a failure in a phase that cannot be energized. When a failure of the winding or changeover element is detected, the failure detection unit 224 notifies the current command value calculation unit 221 via the failure detection signal FD. The current command value calculation unit 221 receives the failure detection signal FD as a switching signal. For example, when the failure detection signal FD is activated, the current command value calculation unit 221 switches the motor control of the control device 100 from the three-phase power supply control to the two-phase power supply control in response to the activation.

[0061] For example, if a failure of a high-side switching element contained in a U-phase leg of the inverter is detected, the failure detection unit 224 activates the failure detection signal FD. This failure is referred to as a U-phase failure.

[0062] In response to the activated failure detection signal FD, the current command value calculation unit 221 switches from three-phase power supply control to two-phase power supply control, with the windings of the V and W phases being energized from the three phases, except for the U phase. If a failure of a high-side changeover element contained in a V-phase leg of the inverter is detected, the failure detection unit 224 similarly activates the failure detection signal FD. This failure is referred to as a V-phase failure. In response to the activated failure detection signal FD, the current command value calculation unit 221 switches from three-phase power supply control to two-phase power supply control, with the U-phase and W-phase windings being energized from the three phases, except for the V phase.For example, if a failure of a high-side switching element contained in a W-phase leg of the inverter is detected, the failure detection unit 224 activates the failure detection signal FD. This failure is referred to as a W-phase failure. In response to the activated failure detection signal FD, the current command value calculation unit 221 switches from three-phase power supply control to two-phase power supply control, with the exception of the W-phase, the U-phase and V-phase windings being supplied with power from the three phases.

[0063] In the illustrated example, the current command value calculation unit 221 comprises the pre-current command value calculation unit 221a and the jitter control unit 221b.

[0064] The current command value calculation unit 221 records the actual current value I m of the motor including the torque command value T ref, of the electric angle θ m of the motor and the three-phase phase currents I u , I v and I w The current command value calculation unit 221 calculates three-phase current command values ​​I ref_u , I ref_v and I ref_w based on the torque command value T ref , of the electric angle θ m of the motor and the three-phase phase currents I u , I v and I w , which are recorded.

[0065] When the control device 100 performs motor control in the normal state, the power of the three-phase motor can be expressed, for example, by a mathematical equation according to Equation 4. The phase voltages of the U, V, and W phases are expressed by mathematical equations according to Equations 5, 6, and 7, respectively. Here, T is a motor torque [Nm], Pn is the number of pole pairs, and Ψ fis an inductive coupling [wb] and ω is an angular velocity [rad / s] of the electric angle θ m of the engine. ψ f is through the product (I m ·L) of the actual current value I m of the motor and a reactance L of the motor. ω is represented by a time differentiation of θ m receive. Tω=Pn(iueu+ivev+iwew) eu=Ψfωsinθ ev=Ψfωsin(θ+23π) ew=Ψfωsin(θ−23π)

[0066] In the present embodiment, an example of a motor control system in the abnormal state is described, in which a two-phase power supply control is implemented to supply power to the V- and W-phase windings, assuming that a fault occurs in the power supply of the U-phase from the U-, V-, and W-phases. In this two-phase power supply control, each phase current is given by a mathematical equation according to Equation 8.2phase is a phase current that flows through the U-phase and the V-phase, and corresponds to the actual current value I m of the engine. iu=0,iv=−iw=i2phase

[0067] Applying equations 5 to 8 to equation 4 and rearranging them results in a mathematical equation according to equation 9. If equation 9 is used for the i 2phase When ordered, a mathematical equation is obtained according to Equation 10. Here, φ is a phase shift [rad]. If a fault occurs in the power supply of the U-phase, φ = 0. If a fault occurs in the power supply of the V-phase, φ = π / 3. If a fault occurs in the power supply of the W-phase, φ = -π / 3. T=Pni2phaseΨf[sin(θ+23π)−sin(θ−23π)] i2phase=T√3PnΨf1sin(θ+∅+π2)

[0068] In two-phase power supply control, the maximum current limit is set as shown in Equation 11. The phase current is limited to the maximum current value, and the current i 2phase is considered as the pre-current command value in relation to the torque command value T ref set. More precisely, the U-phase pre-current command value I is set. pref_u set to zero. It is assumed that the V-phase pre-current command value I pref_v equal i 2phase is. The W-phase pre-current command value I pref_w will be on -i 2phase This specification defines a current command value prior to the application of a jitter control described later as a pre-current command value and differs from a current command value after the application of a jitter control.

[0069] The pre-current command value calculation unit 221a calculates and generates the pre-current command values ​​I pref_v and I pref_wbased on a mathematical equation according to Equation 11. The mathematical equation according to Equation 11 represents the current i 2phase This is represented by using a torque constant Kt [Nm / arms], which is represented by a mathematical equation according to Equation 12. iphase=32TKt1sin(θ+∅+π2) Kt=32PnΨf

[0070] The jitter control unit 221b generates a current command value by applying jitter control to the pre-current command value in a dead-point region of an electric angle range from 0 to 2π. The jitter control unit 221b determines the pre-current command value as the current command value without applying jitter control to the pre-current command value in a region other than the dead-point region in the electric angle range from 0 to 2π.

[0071] Fig. Figure 7A is a diagram that exemplifies a phase current waveform through a two-phase power supply control at the time of a U-phase failure. Fig. Figure 7B is a diagram that exemplifies an engine torque waveform through a two-phase power supply control at the time of the U-phase failure. Fig. 7A and Fig. Figure 7B illustrates exemplary waveforms of the phase current or motor torque to which the maximum current limit is applied.

[0072] In the three-phase and two-phase power supply control systems of the present embodiment, the phase currents are controlled such that the sum of the phase currents equals zero. In the two-phase power supply control system, the current flowing through the U-phase winding is always zero, thus generating an electrical angle at which the sum of the phase currents flowing through the V-phase and the W-phase is zero. This electrical angle is called the dead center. Fig. 7A or Fig. 7B is the dead center π / 2 or (3 / 2)π.

[0073] The dead-center region refers to a portion of the dead center and the electrical angles before and after the dead center. In the dead-center region, current cannot flow to the motor, even if it is commanded, so the motor torque falls below the torque command value (or a target motor torque). The dead-center region encompasses the range of electrical angles that satisfy a condition such that π / 4 ≤ θ + φ < (3 / 4)π or (5 / 4)π ≤ θ + φ < (7 / 4)π. In the present embodiment, if the U-phase is absent, the phase shift φ is zero. The dead-center region corresponds to the electrical angle range of π / 4 ≤ θ < (3 / 4)π or (5 / 4)π ≤ θ < (7 / 4)π.

[0074] As in Fig. As illustrated in Figure 7B, engine power decreases significantly near the dead center. The difference in engine torque between the dead center area and the area other than the dead center area increases, and the magnitude of the torsional torque deviation also increases. This can be a factor that further impairs the steering feel perceived by the driver if the steering wheel angle is to be maintained near the dead center.

[0075] The tremor control unit 221b calculates a tremor current i Zitter based on a mathematical equation according to equation 13 and generates the current command value I ref based on the pre-current command value I Pref and the trembling current i Zitter Here is A Zitter a tremor amplitude, and f Zitter is a tremor frequency. The tremor current i Zitter is represented by a periodic current waveform. The jitter control unit 221b sets the jitter current i. Zitterin a region other than the dead-point region, the current drops to zero, as shown in a mathematical equation according to Equation 14. Adjusting the tremor current i Zitter Setting it to zero means that essentially no jitter control is applied. iZitter=12|AZittersin{2(θ+∅)+π2}{sin(2πfZittert)−1}| iZitter=0

[0076] Fig. Figure 8 is a diagram illustrating an example of a tremor current waveform in the present embodiment. Fig. Figure 9 is a diagram illustrating a tremor current waveform in a comparative example. The tremor current according to the comparative example is expressed by a mathematical equation according to Equation 15. In contrast to the tremor current according to the comparative example, in the present embodiment, two points are specified in the mathematical equation according to Equation 13 for specifying the tremor current: (1) the absolute value of the tremor current is used (see Fig. 8) and (2) “-1” is added as a bias to the output of the sine function of the last term on the right-hand side. This setting makes it possible to retain the jitter control effect in the dead-point region. iZitter=AZittersin{2(θ+∅)+π2}sin(2πfZittert)

[0077] The jitter control unit 221b generates a current command value by subtracting the jitter current from the pre-current command value if the pre-current command value is equal to or greater than zero, and generates a current command value by adding the jitter current to the pre-current command value if the pre-current command value is less than zero. In other words, the jitter control unit 221b generates the current command value based on a mathematical equation according to Equation 17 if the condition shown in Equation 16 is satisfied, and generates the current command value based on the mathematical equation according to Equation 18 if the condition shown in Equation 16 is not satisfied. i2phase≥0 i2phase_Zitter=i2phase−iZitter i2phase_Zitter=i2phase+iZitter

[0078] The jitter control unit 221b outputs three-phase current command values ​​I after the jitter control has been applied. ref_u , I ref_v and I ref_wfrom which are given by a mathematical equation according to Equation 19. Furthermore, the U-phase current command value I ref_u at the time of the U-phase failure, it is zero. Iref_u=0,Iref_v=i2phase_Zitter,Iref_w=−i2phase_Zitter

[0079] Fig. Figure 10 is a diagram that exemplifies a tremor current waveform used for tremor control. Fig. Figure 11 is a diagram that exemplifies a phase current waveform after the application of jitter control to a phase current in which flutter occurs.

[0080] As described above, current limiting is applied in the two-phase power supply control. Even when the current quirk is applied to the pre-current command value according to the comparative example, the reduction of current quirk is insufficient, and consequently, the effect of the quirk control cannot be maintained. On the other hand, when the current quirk is applied to the pre-current command value according to the present embodiment, the current quirk is adequately reduced, and consequently, the effect of the quirk control can be sufficiently maintained.

[0081] It will be revisited Fig. 5. Referenced.

[0082] The voltage command value calculation unit 222 records the current command values ​​I ref_u , I ref_v and I ref_w The voltage command value calculation unit 222 calculates the voltage command values ​​V ref_u , Vref_v and V ref_w based on the current command values ​​I ref_u , I ref_v and I ref_w In the case of two-phase power supply control, at the time of the U-phase failure, V ref_u equal to zero.

[0083] The PWM modulation unit 223 detects the voltage command values ​​V ref_u , V ref_v and V ref_w The PWM modulation unit 223 calculates the load command values. u Last v and load w based on the voltage command values ​​V ref_u , V ref_v and V ref_w and gives the load command values ​​load u Last v and load w to the driver circuit 115.

[0084] The inventors of the present invention have confirmed the effect obtained by applying the jitter control to the pre-current command value by conducting an actual vehicle measurement. During the actual vehicle measurement, the effect of the jitter control was measured when the two-phase power supply control was implemented, and the application of the jitter control was activated when fluttering occurred in the current in the dead center region.

[0085] The conditions of the actual vehicle measurement are as follows: (1) Torque constant Kt: 0.0452 [Nm / arm], (2) Number of pole pairs Pn: 4, (3) Jitter amplitude A Zitter : 2 [Nm], (4) Shaking frequency f Zitter : 30 [Hz], and (5) type of motor: brushless motor. The jitter amplitude A Zitter and the tremor frequency f Zitterare set as variables and can be appropriately determined depending on the type of vehicle or engine to which the EPS is attached.

[0086] Fig. Figure 12 is a diagram illustrating measurement results of a steering angle and steering torque in a case where the jitter control is not applied. Fig. Figure 13 is a diagram illustrating measurement results of the steering angle and steering torque in a case where the yaw control is applied. In the diagram, a dashed line indicates the steering angle [degrees] and a solid line indicates the steering torque [Nm].

[0087] Compared to a case where the vibration control was not applied, current flutter was reduced in a case where the vibration control was applied. Consequently, it was found that the steering wheel vibration was also reduced, and in particular, the deviation in steering torque decreased by approximately 5 Nm.

[0088] According to the control device 100 of the present embodiment, it is possible to improve the steering feel perceived by the driver when the power supply control is executed to supply energy to the remaining windings of the normal phase in a case where the power supply fails in one phase of the motor windings. For example, it is possible to reduce current oscillation near the dead center, which can occur when the two-phase power supply control is executed, and to reduce the steering torque deviation. These effects can contribute to improving the safety of steering wheel operation.

[0089] The motor control device or control method according to the present embodiment can also be used as a control device for a double-winding motor capable of performing a so-called double-inverter drive, wherein the motor is driven or controlled using two inverters. For example, in a case where a U-phase fails in one of the two inverters, it is possible to implement a two-phase power supply control for continuously supplying power to a V-phase and a W-phase winding by using the two inverters.

[0090] The embodiments described in the present disclosure can be used for an engine control device for controlling an EPS attached to a vehicle. Reference symbol list 200 processor 210 Torque control unit 211 Response sensitivity phase compensation unit 212 Basic Support Calculation Unit 213 Stability phase compensation unit 214 Torque difference compensation unit 215 Add-on device 220 power control unit 221 Current command value calculation unit 221a Pre-current command value calculation unit 221b Jitter control unit 222 Voltage command value calculation unit 223 PWM modulation unit 224 Failure Detection Unit

Claims

[1] A control device (100) used in an electric power steering device (1000) including a motor with n-phase windings (n is an integer of three or more), for controlling the motor, in which an n-phase power supply control for supplying power to the n-phase windings or an n-1-phase power supply control for supplying power to n-1-phase windings can be implemented, wherein the control device (100) comprises the following: a processor (200); and a memory (116) which stores a program for controlling an operation of the processor (200), wherein The processor (200) performs the following according to the program: Switching from n-phase power supply control to n-1-phase power supply control in response to a switching signal, Capturing a torque command value (T) ref ), an electric angle (θ m) of the motor and an actual current value (I m ) of the engine, Generating a pre-current command value (I Pref ) based on the torque command value (T ref ), of the electric angle (θ m ) of the motor and the actual current value of the motor (I m ), which have been recorded, Generating a current command value (I ref ) by applying a jitter control to the pre-current command value (I Pref ) in a dead-point region of an electric angle range from 0 to 2π, and Performing n-1-phase power supply control based on the current command value (I ref ). [2] The control device (100) according to claim 1, characterized by , that the processor (200) the pre-current instruction value (I pref ) as the current command value (I ref ) determined without applying a jitter control to the pre-current command value (I Pref) in a different region than the dead center region in the electric angle range from 0 to 2π. [3] The control device (100) according to claim 1 or 2, characterized by , that the dead-point region includes a range of electric angles that satisfies a condition according to π / 4 ≤ θ + φ < (3 / 4)π or (5 / 4)π ≤ θ + φ < (7 / 4)π, where θ is the electric angle and φ is a phase shift. [4] The control device (100) according to claim 3, characterized by , that the processor (200) calculates a jitter current based on a mathematical equation according to equation 1 and the current instruction value (I ref ) based on the pre-current command value (I Pref ) and the trembling current is generated, iZitter=12|AZittersin{2(θ+∅)+π2}{sin(2πfZittert)−1}| where i Zitter the trembling current is, A Zitter a tremor amplitude is and f Zitter a tremor frequency. [5] The control device (100) according to claim 4, characterized by , that the processor (200): the current command value (I ref ) by subtracting the trembling current (i Zitter ) from the pre-current command value (I Pref ) is generated when the pre-current command value (I Pref ) is equal to or greater than zero, and the current command value (I ref ) by adding the trembling current (i Zitter ) to the pre-current command value (I Pref ) is generated when the pre-current command value (I Pref ) less than zero. [6] The control device (100) according to any one of claims 1 to 5, characterized by , that the processor (200) further executes the following: Detecting a torsional torque (T tor ), Generating a phase compensation torque (T rc ) by applying first-order phase compensation to the torsional torque (T tor), if a steering frequency is within a predetermined range, and Generating the torque command value (T) ref ) based on the phase compensation torque (T rc ). [7] The control device (100) according to claim 6, characterized by , that the first-order phase compensation is represented by a transfer function of a mathematical equation according to equation 2, C(s)=12πf1s+112πf2s+1 where s is a Laplace transform, f1 is a frequency of a zero point of the transfer function, and f2 is a frequency of a pole of the transfer function. [8] The control device (100) according to claim 6 or 7, characterized by , that the processor (200) has a differential compensation torque (T dc ) based on a time-dependent change in the torsional torque (T tor ) calculated, and the torque command value (T ref ) based on the phase compensation torque (Trc ) and the differential compensation torque (T dc ) generated. [9] The control device (100) according to any one of claims 1 to 8, characterized by , that the processor (200): monitors whether there is a winding among the n-phase windings that cannot be supplied with energy, the switching signal responds to the detection of the winding that cannot be supplied with energy, and The n-1 phase power supply control is carried out by supplying energy to the other n-1 phase windings besides the winding that cannot be supplied with energy from the n phase windings. [10] A motor module which has the following features: an engine; and the control device (100) according to any one of claims 1 to 9. [11] An electric power steering device (1000) comprising the motor module according to claim 10. [12] A control method used in an electric power steering device (1000) including a motor with n-phase windings (n is an integer of three or more) for controlling the motor, wherein an n-phase power supply control for supplying energy to the n-phase windings or an n-1-phase power supply control for supplying energy to n-1-phase windings can be implemented, wherein the control method comprises the following steps: Switching from n-phase power supply control to n-1-phase power supply control in response to a switching signal, Capturing a torque command value (T) ref ), an electric angle (θ m ) of the motor and an actual current value (I m ) of the engine, Generating a pre-current command value (I Pref ) based on the torque command value (T ref ), of the electric angle (θm ) of the motor and the actual current value of the motor (I m ), which have been recorded, Generating a current command value (I ref ) by applying a jitter control to the pre-current command value (I Pref ) in a dead-point region of an electric angle range from 0 to 2π, and Performing n-1-phase power supply control based on the current command value (I ref ).

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