Motor control device, motor control device for steering actuator, steering actuator system

Abstract

A motor control device, a motor control device for a steering actuator, and a steering actuator system are provided. A motor control device according to one embodiment of the present invention drives a three-phase motor having two systems of angle sensors, wherein the two systems of angle sensors are composed of a first angle sensor and a second angle sensor. The motor control device has a control unit, which outputs excitation signals to the two systems of angle sensors respectively, and the two systems of angle sensors input detection signals sensed by each of them to the control unit, and the frequency of the first excitation signal of the first angle sensor is different from the frequency of the second excitation signal of the second angle sensor.

Description

Technical Field

[0001] The present invention relates to a motor control device, a motor control device for a steering actuator, and a steering actuator system. Background Art

[0002] In the past, as a steering system for large vehicles, there was an electric hydraulic power steering device that used a motor to control the hydraulic pressure of the hydraulic power steering device. In recent years, automatic driving and automatic steering of large vehicles have been desired. Therefore, the steering actuator system uses a steering actuator (motor) to activate the electric hydraulic power steering device, thereby performing automatic steering. Since it is necessary to improve safety against failures of the steering actuator system, the motor control device for controlling the steering actuator (motor) needs to be redundant. In addition, the motor control device detects the angle of the motor rotating shaft and controls it. As a redundant angle sensor, an angle sensor in which two systems of rotary transformers are closely arranged is known. (Patent Document 1)

[0003] Patent Document 1: Japanese Patent Application Publication No. 2009-210281

[0004] The motor control device of the steering actuator system receives an angle signal from the angle sensor of the motor rotating shaft and performs motor control. Therefore, if the angle sensor fails, the angle signal cannot be obtained, which may cause obstacles to the motor control, so it is necessary to make the angle sensor redundant. In the angle sensor of Patent Document 1, two rotary transformers are arranged close to each other, and even if the two excitation signals excited asynchronously with each other cause magnetic interference, high angle detection accuracy can be maintained. However, since it is necessary to find the timing for sampling the output of the rotary transformer, there is a problem that the structure becomes complicated in order to maintain high angle detection accuracy. Summary of the invention

[0005] A motor control device according to one embodiment of the present invention drives a three-phase motor having two systems of angle sensors, wherein the two systems of angle sensors are composed of a first angle sensor and a second angle sensor. The motor control device has a control unit that outputs excitation signals to the two systems of angle sensors, respectively, and the two systems of angle sensors input detection signals sensed by each of them to the control unit, wherein the frequency of the first excitation signal of the first angle sensor is different from the frequency of the second excitation signal of the second angle sensor.

[0006] A steering actuator motor control device according to one embodiment of the present invention employs the above-mentioned motor control device as a steering actuator motor control device for automating a steering operation of a vehicle.

[0007] Furthermore, a steering actuator system according to one aspect of the present invention includes the above-mentioned steering actuator motor control device.

[0008] According to the exemplary embodiment of the present invention, in the motor control device, the frequencies of the excitation signals of the two systems of angle sensors are different. Therefore, even if the excitation signals interfere as noise, the angle can be easily detected based on the detection signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a diagram showing the overall configuration of a steering actuator system including a steering actuator motor control device according to an embodiment of the present invention.

[0010] Figure 2 It is shown Figure 1 A diagram showing a detailed configuration of a motor control device for a steering actuator is shown.

[0011] Figure 3 1 is a diagram showing a schematic configuration of two systems of angle sensors.

[0012] Figure 4A It is a diagram showing an excitation signal and a detection signal of the angle sensor of the first system.

[0013] Figure 4B It is a diagram showing the excitation signal and the detection signal of the angle sensor of the second system.

[0014] Figure 5 This is a diagram showing a schematic flowchart of angle calculation by the motor control device.

[0015] Fig. 6A This is a diagram showing the results of simulating the angle calculation error in a motor control device when no filtering process is performed.

[0016] Figure 6B This is a diagram showing the results of simulating an angle calculation error when the motor control device performs bandpass filtering.

[0017] Figure 6C : is a diagram showing the result of simulating the angle calculation error when the motor control device performs band-stop filtering after band-pass filtering.

[0018] Description of symbols

[0019] 1: Motor control device; 1a: Motor control device (first system); 1b: Motor control device (second system); 2: Steering wheel; 3: Rotating shaft; 7: Rack shaft; 8a: Rotary valve; 8b: Power cylinder; 9, 9a, 9b: Torque sensor; 10: Steering actuator system; 11a: Angle sensor (first system); 11b: Angle sensor (second system); 12a, 12b: Control unit (CPU); 13a, 13b: 3b: inverter control unit; 14a, 14b: inverter circuit; 15, 15a, 15b: steering actuator (motor); 16a, 16b: filter; 17a, 17b: power relay; 18a, 18b: input I / F; 19a, 19b: CANI / F; 27: CAN signal line; 27a: CAN-H line; 27b: CAN-L line; 31: ignition switch (IG-SW); BT: battery. DETAILED DESCRIPTION

[0020] Hereinafter, embodiments of the motor control device of the present disclosure, the motor control device for a steering actuator having the motor control device, and the steering actuator system having the motor control device for a steering actuator will be described in detail with reference to the accompanying drawings. However, in order to avoid the following description being unnecessarily long and to facilitate understanding by those skilled in the art, an overly detailed description may be omitted. For example, a detailed description of a well-known matter or a repeated description of a substantially identical structure may be omitted.

[0021] Figure 1 1 is a diagram showing an example of the overall structure of the steering actuator system 10. The steering actuator system 10 is a device that assists the driver's steering operation in transportation equipment such as large vehicles. The steering actuator system 10 includes a battery BT as a power supply source, a motor control device 1 as an electronic control unit (ECU), a steering wheel 2 as a steering member, a rotating shaft 3 connected to the steering wheel, a pinion 6, a rack shaft 7, a rotary valve 8a for adjusting the hydraulic pressure from a hydraulic source not shown, and a power cylinder 8b for driving the rack shaft using the hydraulic pressure.

[0022] The rotating shaft 3 meshes with a pinion 6 provided at the front end thereof. The rotating motion of the rotating shaft 3 is converted into the linear motion of the rack shaft 7 by the pinion 6. In addition, the hydraulic pressure sent from the rotary valve 8a is transmitted to the power cylinder 8b as an output for assisting the rotation of the rotating shaft 3, so that the piston of the power cylinder 8b is actuated, thereby converting it into the linear motion of the rack shaft 7. A pair of wheels 5a and 5b provided at both ends of the rack shaft 7 are steered at an angle corresponding to the displacement amount of the rack shaft 7.

[0023] A motor 15 having an angle sensor for a steering actuator is coaxially provided on the rotating shaft 3. The motor control device 1 obtains the steering angle of the rotating shaft 3 based on the angle of the rotating shaft of the motor obtained by the angle sensor, generates a motor drive signal so that the steering angle becomes the indicated steering angle received from an ADAS-ECU (Advanced Driver-Assistance Systems-Electronic Control Unit) not shown, and outputs the signal to the motor 15. Regardless of the steering operation of the driver, the steering actuator system can perform automatic steering by indicating the steering angle through the ADAS-ECU.

[0024] In addition, a torque sensor 9 is provided on the rotating shaft 3 to detect the steering torque when the steering wheel 2 is operated, and the detected steering torque is transmitted to the motor control device 1. The motor control device 1 detects the driver's intervention in steering the steering wheel based on the steering torque obtained by the torque sensor 9, generates an attenuation or stop signal of the motor drive signal, and outputs the signal to the electric motor 15. The driver's intervention in the steering operation can stop the automatic steering based on the steering actuator system and perform manual steering.

[0025] Next, the motor control device of this embodiment will be described. Figure 2 As shown, the motor control device of this embodiment has a redundant structure, and the redundant structure is composed of a plurality of motor control systems having the same structural elements except for a predetermined part. Here, a motor control device having a redundant structure composed of two systems is used as an example for explanation, but it can also be further expanded to a redundant structure composed of a plurality of systems such as three systems, four systems, etc.

[0026] The motor control device of this embodiment is composed of motor control devices 1a and 1b, which are composed of two independent systems having control units (CPUs) 12a and 12b, respectively. The motor control devices 1a and 1b adopt a dual inverter structure having the following parts: an electric motor 15 having two sets of three-phase windings (Ua, Va, Wa) 15a and three-phase windings (Ub, Vb, Wb) 15b; and two sets of inverter circuits 14a and 14b, which respectively provide drive current to the two sets of three-phase windings. The electric motor 15 is, for example, a three-phase brushless DC motor.

[0027] In the following description, a configuration including the motor control device 1 a and the three-phase winding 15 a is referred to as a first system, and a configuration including the motor control device 1 b and the three-phase winding 15 b is referred to as a second system.

[0028] The motor control device 1a constituting the first system includes: a control unit (CPU) 12a, which is responsible for the overall control of the motor control device 1a and is composed of, for example, a microprocessor; an inverter control unit 13a, which generates a motor drive signal based on a control signal from the CPU 12a and functions as a FET drive circuit; and an inverter circuit 14a, which is a motor drive unit that provides a drive current to the three-phase winding (Ua, Va, Wa) 15a of the electric motor 15.

[0029] The motor control device 1b constituting the second system has, like the motor control device 1a, a control unit (CPU) 12b, which is responsible for the overall control of the motor control device 1b; an inverter control unit 13b, which generates a motor drive signal based on the control signal from the CPU 12b and functions as a FET drive circuit; and an inverter circuit 14b, which provides a specified drive current to the three-phase winding (Ub, Vb, Wb) 15b of the electric motor 15.

[0030] The motor driving power is supplied to the inverter circuit 14a from the external battery BT via the filter 16a and the power supply relay 17a, and the motor driving power is supplied to the inverter circuit 14b from the external battery BT via the filter 16b and the power supply relay 17b. In addition, the filters 16a and 16b may be included in the inverter circuits 14a and 14b, respectively.

[0031] The filters 16a and 16b are composed of electrolytic capacitors and coils (not shown) and absorb noise contained in the power supply to smooth the power supply voltage. The power supply relays 17a and 17b are composed of mechanical relays or semiconductor relays, for example, and are configured to cut off power from the battery BT.

[0032] The inverter circuit 14a is a FET bridge circuit composed of semiconductor switch elements (FET) corresponding to the three-phase windings (Ua, Va, Wa) 15a of the electric motor 15. Similarly, the inverter circuit 14b is a FET bridge circuit composed of semiconductor switch elements (FET) corresponding to the three-phase windings (Ub, Vb, Wb) 15b of the electric motor 15.

[0033] These switching elements (FETs) are also called power elements, and, for example, semiconductor switching elements such as MOSFET (Metal-Oxide Semiconductor Field-Effect Transistor) and IGBT (Insulated Gate Bipolar Transistor) are used.

[0034] One end of the ignition switch (IG-SW) 31 is connected to the battery BT, and the other end is connected to the IG voltage detection unit 24a, 24b. The IG voltage detection unit 24a, 24b performs AD conversion on the ignition (IG) voltage value, and inputs the converted digital voltage value as the actual voltage value of the IG voltage to the CPU 12a, 12b. In addition, the IG voltage detection unit can also be built into the CPU.

[0035] The power supply units 20a and 20b convert the battery voltage +B supplied from the battery BT into a predetermined voltage (eg, a voltage of a logic level) and supply it as an operating power supply for the control units (CPU) 12a and 12b and the inverter control units 13a and 13b.

[0036] The path between the power supply unit 20a, 20b and the battery BT includes switches 21a, 21b that are linked to the operation of the ignition switch (IG-SW) 31. When the ignition switch (IG-SW) 31 is turned off, the switches 21a, 21b are also turned off, and when the ignition switch (IG-SW) 31 is turned on, the switches 21a, 21b are also turned on. By including the switches 21a, 21b, the dark current of the motor control devices 1a, 1b can be reduced when the ignition switch (IG-SW) 31 is turned off. By reducing the dark current, the battery can be prevented from being exhausted.

[0037] The CPUs 12a and 12b of the motor control devices 1a and 1b are configured to be able to communicate with each other in real time. In addition, the motor control devices 1a and 1b perform data communication based on the CAN protocol with other control units (ECUs) via CAN signal lines (CAN communication buses) 27H and 27L connected to an on-board network (CAN) for transmitting and receiving various information of the vehicle and CAN I / Fs 19a and 19b.

[0038] The CAN signal lines 27H and 27L are two-wire communication lines each composed of a CAN-H line 27Ha and a CAN-L line 27La constituting a first system, and a CAN-H line 27Hb and a CAN-L line 27Lb constituting a second system.

[0039] Angle sensors (resolvers) 11a and 11b for detecting the rotational position of the motor rotor are mounted on the electric motor 15. The output signal from the angle sensor (resolver) 11a is sent to the CPU 12a via the input I / F 18a as rotation information, and the output signal from the angle sensor (resolver) 11b is sent to the CPU 12b via the input I / F 18b.

[0040] By making the first system 1a and the second system 1b including the power supply units 20a and 20b, the CPUs 12a and 12b, the inverter circuits 14a and 14b, etc. redundant, a motor control device with high reliability and high safety against failure can be provided.

[0041] Figure 3 This is a diagram showing the schematic structure of two systems of angle sensors (resolvers) 11a and 11b. Two systems of excitation coils and detection coils are assembled for one resolver rotor, forming a redundant structure. In order to distinguish the excitation signals from each other, different excitation signals are input to each system. For example, an excitation signal of 10kHz is input to the angle sensor of the first system, and an excitation signal of 5kHz is input to the angle sensor of the second system.

[0042] Since the redundantly designed angle sensors (resolvers) 11a and 11b are arranged close to each other, the excitation signal of the first system sometimes becomes noise inducing induction in the detection coil of the second system, and vice versa.

[0043] Figure 4A This is a diagram showing the relationship between the excitation signal and the detection signal of the angle sensor (resolver) of the first system. In the first system, there are a sine wave S2_A and a cosine wave S1_A as the first detection signal for the first excitation signal R1_A. The sine wave S2_A in the first detection signal is mixed with a signal induced by the second excitation signal R1_B of the second system as noise, and the sine wave is destroyed.

[0044] Figure 4B This is a diagram showing the relationship between the excitation signal and the detection signal of the angle sensor (resolver) of the second system. In the second system, there are a sine wave S2_B and a cosine wave S1_B as the second detection signal for the second excitation signal R1_B. The sine wave S2_B in the second detection signal is mixed with a signal induced by the first excitation signal R1_A of the first system as noise, and the sine wave is destroyed.

[0045] Since the detection signal of the resolver is derived from the sine and cosine wave values ​​of the rotor angle, the amplitude ratio of the signal is consistent with the tangent value of the rotor angle. Therefore, the rotor angle θ can be obtained by dividing the amplitude Vs of the sine signal by the inverse tangent trigonometric function of the amplitude Vc of the cosine signal.

[0046] <Formula 1>

[0047] θ=tan -1 (sinθ / cosθ)=tan -1 (Vs / Vc)

[0048] Figure 5 A schematic flowchart of angle calculation of the motor control device is shown. In this embodiment, as noise removal filtering, a band-stop filter (BSF) is implemented after a band-pass filter (BPF).

[0049] Assume that 10kHz is input as the first excitation signal. First, in step ST1, a 10kHz bandpass filter is applied as the first detection signal. Then, in step ST2, a 5kHz bandstop filter is applied to the first detection signal after the bandpass filter. This is to remove the noise component induced by the 5kHz of the second excitation signal. Then, in step ST3, the rotation angle of the first angle sensor is calculated by equation 1 based on the first detection signal after the bandstop filter.

[0050] Similarly, assume that 5kHz is input as the second excitation signal. First, in step ST1, a 5kHz bandpass filter is implemented as the second detection signal. Then, in step ST2, a 10kHz bandstop filter is implemented on the second detection signal after the bandpass filter. This is to remove the noise signal induced by the 10kHz of the first excitation signal. Then, in step ST3, the rotation angle of the second angle sensor is calculated by equation 1 based on the second detection signal after the bandstop filter.

[0051] It is well known that the band pass filter BPF can be implemented by the following formula.

[0052] <Formula 2>

[0053]

[0054] In equation 2, ω0 is the peak gain angular frequency and Q is the sharpness.

[0055] For example, if you want to pass a 10 kHz band as a detection signal, assuming that the peak gain frequency fp is 10 kHz, by using ω0=(2πfp)=62831.853, Q=10, ω0 2 =3947841751.4136These values ​​can implement bandpass filtering BPF.

[0056] For example, if you want to pass the 5 kHz band as the detection signal, assuming that the peak gain frequency fp is 5 kHz, by using ω0=(2πfp)=31415.9265, Q=10, ω0 2 =986960437.8534These values ​​can implement bandpass filtering BPF.

[0057] It is known that the band stop filter BSF can be implemented by the following formula.

[0058] <Formula 3>

[0059]

[0060] In equation 3, ω0 is the cutoff angular frequency and Q is the sharpness.

[0061] For example, if we want to cut off the 10 kHz band as the detection signal, assuming that the cutoff frequency fc is 10 kHz, we can use ω0=(2πfc)=62831.853, Q=10, ω0 2 =3947841751.4136These values ​​can realize band-stop filtering BSP.

[0062] For example, if you want to cut off the 5kHz band as a detection signal, assuming that the cutoff frequency fc is 5kHz, by using ω0=(2πfc)=31415.9265, Q=10, ω0 2 =986960437.8534These values ​​can implement band-stop filtering BSP.

[0063] The bandpass filter and the bandstop filter may be configured by hardware circuits, but since the filter characteristics vary depending on the temperature characteristics of circuit components such as capacitors or component variations, they are more effectively configured by software.

[0064] Fig. 6A This is a diagram showing the results of simulating the angle calculation error in a motor control device when no filtering process is performed. Figure 6B This is a diagram showing the results of simulating an angle calculation error in a case where a band-pass filter process is performed in a motor control device. Figure 6C This is a diagram showing the result of simulating the angle calculation error of the motor control device when a band-pass filter is applied after a band-stop filter. Here, the error when the angle is calculated without filtering the first detection signal is in the range of approximately +2degE to -4degE relative to the ideal angle, while the error when the angle is calculated using the first detection signal after the band-pass filter BPF is approximately ±0.2degE. Furthermore, the error when the angle is calculated using the first detection signal obtained by applying a band-stop filter BSF to the first detection signal after the band-pass filter BPF is ±0.01degE, which confirms the effect of improving the accuracy of the angle calculation by applying the band-pass filter BPF and the band-stop filter BSF. The accuracy of the angle calculation can be improved by appropriately filtering the detection signal.

[0065] As a motor control device for a steering actuator system, the higher the steering angle accuracy is, the better it is for automatic steering, and therefore it is effective that the angle error is less than ±1 degree E. Thus, the control accuracy of the motor control device for a steering actuator can be improved.

[0066] Furthermore, by using a steering actuator system including the steering actuator motor control device, a steering actuator system capable of achieving high-precision control can be provided, and an automatic steering system capable of achieving high-precision control can be provided.

[0067] In addition, the steering actuator system 10 has a configuration including the motor control device 1, but is not limited thereto. The motor control device 1 may also be a control device that controls other components in the vehicle or the like.

[0068] In addition, in the present embodiment, the first system 1a and the second system 1b may be configured in one circuit board or in different circuit boards.

Claims

1. A motor control device that drives a three-phase motor having two systems of angle sensors, wherein: The angle sensors of the two systems are composed of a first angle sensor and a second angle sensor. The motor control device includes a control unit that outputs excitation signals to the two systems of angle sensors, respectively, and the two systems of angle sensors input detection signals sensed by each system to the control unit. The frequency of the first excitation signal of the first angle sensor is different from the frequency of the second excitation signal of the second angle sensor. A first detection signal is induced by the first excitation signal, A second detection signal is induced by the second excitation signal, The control unit performs band-pass filtering on the frequency of the first excitation signal and then performs band-stop filtering on the frequency of the second excitation signal on the first detection signal, and performs band-pass filtering on the frequency of the second excitation signal and then performs band-stop filtering on the frequency of the first excitation signal on the second detection signal.

2. The motor control device according to claim 1, wherein: The three-phase motor is composed of two systems of winding groups. The motor control device comprises: an inverter circuit for two systems that drives the winding groups of the two systems on a per-system basis; and a control circuit for two systems, which controls the inverter circuits of the two systems for each system, The control circuits of the two systems are composed of a first control circuit and a second control circuit, and each system has a power supply unit that generates an internal power supply from an external constant power supply. The first control unit of the first control circuit outputs the first excitation signal. The second control unit of the second control circuit outputs the second excitation signal.

3. A motor control device for a steering actuator, which uses the motor control device according to claim 1 or 2 as a motor control device for a steering actuator for automating a steering operation of a vehicle.

4. A steering actuator system comprising the steering actuator motor control device according to claim 3.

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