Rotation angle detection device, electric power steering device, and control method for electric power steering device

Abstract

The power management section (50) supplies the first sensor (34) with the first power as continuous power when the power switch (11) is on, and supplies the first sensor with the second power as intermittent power having a smaller voltage than the first power when the power switch is off, and outputs the rotation number information indicating the rotation number of the motor rotation shaft based on the second sensor signal. The power management section (50) has a comparator (58a, 58b) that operates as a power source with the second power when the power switch is off and compares the second sensor signal and a reference voltage, and a counter (58c, 58d) that detects the rotation number of the motor rotation shaft by counting the output of the comparator.

Description

Technical Field

[0001] This invention relates to a rotation angle detection device, an electric power steering device, and a control method for the electric power steering device. Background Technology

[0002] Previously, sensors for detecting the rotation angle of a motor shaft have been proposed. Furthermore, techniques have been proposed for monitoring the number of rotations of the motor shaft during periods when the power switch is off.

[0003] For example, Patent Document 1 describes a steering system in which two MR (Magnetic Resistance) sensors for detecting the angular position of an electric motor and two counting units for processing their output signals are redundantly provided. During the period when the ignition switch is off, the number of rotations of the electric motor is counted by the two counting units based on the sine and cosine signals output by the two MR sensors respectively.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: European Patent No. 2050658 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] For example, in an electric power steering system, the steering shaft may sometimes rotate due to external force while the ignition switch (main power switch) is off and the auxiliary function is stopped. Therefore, it is preferable to monitor the number of rotations of the motor shaft connected to the steering shaft using a battery-backed circuit while the ignition switch is off.

[0009] On the other hand, it is preferable to consume as little power as possible during the period when the power switch is off. For example, in the case of an electric power steering system, the vehicle's battery is used as the main power source. Therefore, it is required that the dark current flowing during the period when the ignition switch is off be as small as possible. The steering system described in Patent Document 1 may result in increased power consumption due to the dark current flowing through the sensor during the period when the ignition switch is off.

[0010] The present invention was made in view of the following problem, and its object is to reduce the power consumption during the period when the power switch is off in a rotation angle detection device having a sensor that outputs a signal corresponding to the rotation of the motor shaft.

[0011] Methods for solving problems

[0012] To achieve the above objectives, one aspect of the rotation angle detection device of the present invention comprises: a first sensor, which is powered when a power switch is turned on, outputs a first sensor signal corresponding to the rotation of the motor's rotating shaft, and stops power supply when the power switch is turned off; an angle position calculation unit, which is powered when the power switch is turned on, calculates angle position information representing the angle position of the motor's rotating shaft based on the first sensor signal, and stops power supply when the power switch is turned off; and a second sensor, which outputs a sine signal and a cosine signal corresponding to the rotation of the motor's rotating shaft. The second sensor signal; a power management unit that provides the second sensor with a first power supply as continuous power when the power switch is on, and provides the second sensor with a second power supply as intermittent power supply having a voltage lower than the first power supply when the power switch is off, and outputs rotation number information indicating the number of rotations of the motor shaft based on the second sensor signal; and a rotation angle calculation unit that is powered when the power switch is on, calculates rotation angle information indicating the rotation angle of the motor shaft based on the angular position information and the rotation number information, and stops power supply when the power switch is off.

[0013] The power management unit includes: a power supply unit that generates a first power and a second power; a comparator that operates by using the first power supplied by the power supply unit as power when the power switch is on, and compares a first reference voltage based on the voltage of the first power with a second sensor signal, and operates by using the second power supplied by the power supply unit as power when the power switch is off, and compares a second reference voltage based on the voltage of the second power with a second sensor signal; and a counter that detects the number of rotations of the motor shaft by counting the output of the comparator.

[0014] Furthermore, other embodiments of the electric power steering device of the present invention include: a torque sensor that detects the steering torque applied to the steering shaft based on the torsion angle of the input shaft and the output shaft connected via a torsion bar provided on the steering shaft of the vehicle; a motor that provides steering assistance force to the steering mechanism of the vehicle; the aforementioned rotation angle detection device that calculates the rotation angle information of the motor rotation shaft; a motor control unit that performs drive control on the motor based on the steering torque; and a steering angle calculation unit that calculates the steering angle of the input shaft based on the torsion angle, the reduction ratio of the reduction gear, and the rotation angle information.

[0015] Furthermore, the control method of the electric power steering device in other aspects of the present invention controls the steering assist force given by the motor based on the steering angle calculated by the steering angle calculation unit.

[0016] Invention Effects

[0017] According to the present invention, in a rotation angle detection device having a sensor that outputs a signal corresponding to the rotation of the motor's rotating shaft, it is possible to reduce power consumption during periods when the power switch is off. Attached Figure Description

[0018] Figure 1 This is a structural diagram illustrating an example of an electric power steering device according to an embodiment.

[0019] Figure 2 This is a diagram illustrating an example of the first sine signal, the first cosine signal, the second sine signal, and the second cosine signal.

[0020] Figure 3 This is a schematic exploded view showing an example of a sensor unit.

[0021] Figure 4 This is a diagram showing an example of the controller's structure.

[0022] Figure 5 This is a block diagram illustrating an example of the functional structure of the power management unit in the first embodiment.

[0023] Figure 6 (a) to (d) are explanatory diagrams of an example of the operation of the rotation count detection unit, and (e) is an explanatory diagram of an example of rotation count information.

[0024] Figure 7 This is a block diagram illustrating an example of the functional architecture of a microprocessor.

[0025] Figure 8 (a) is a diagram showing the first sine signal SIN1 and the first cosine signal COS1, (b) is a diagram showing an example of angular position information θ1, (c) is a diagram showing the number of motor rotations Nr, and (d) is a diagram showing rotation angle information θm.

[0026] Figure 9 This is a block diagram illustrating an example of the functional structure of an auxiliary control unit.

[0027] Figure 10 (a) is a diagram showing the second sine signal SIN2 and the second cosine signal COS2, (b) is a diagram showing an example of the sine count value CNTs and the cosine count value CNTc when the threshold voltage Vr of the comparator has an error, and (c) is a diagram showing an example of the total count value CNT.

[0028] Figure 11 (a) is an explanatory diagram showing the possible error in the number of motor rotations Nr without a rotation number information correction unit, and (b) is an explanatory diagram showing the possible error in the rotation angle information θm.

[0029] Figure 12This is a block diagram illustrating an example of the functional structure of the rotation count information correction unit.

[0030] Figure 13 (a) is a diagram showing an example of the first quadrant signal Q1 and the second quadrant signal Q2; (b) is a diagram showing the difference between the first quadrant signal Q1 and the second quadrant signal Q2; (c) is a diagram showing an example of the calibrated total count CNTa; and (d) is a diagram showing the number of motor rotations Nr calculated from the calibrated total count CNTa.

[0031] Figure 14 This is a block diagram illustrating an example of the functional structure of the power management unit in the second embodiment.

[0032] Figure 15 This is an illustration of an example of controlling the drive interval of the second sensor when the rotation of the motor shaft is detected during the period when the ignition switch is off.

[0033] Figure 16 This is an illustration of an example of controlling the drive interval of the second sensor when no rotation of the motor shaft is detected during the period when the ignition switch is off.

[0034] Figure 17 This is a flowchart illustrating an example of a method for setting the drive interval indicated by a drive interval indication signal.

[0035] Figure 18 yes Figure 17 A flowchart of an example of rotation detection processing.

[0036] Figure 19 (a) is a graph showing an example of the waveform of the second sensor power supply Vs2, which is intermittently output during the period when the ignition switch is off, and (b) is a graph showing the waveform of the second sensor power supply Vs2 of (a) during one intermittent output.

[0037] Figure 20 This is a block diagram illustrating an example of the functional structure of the power management unit in the third embodiment.

[0038] Figure 21 This is a schematic block diagram illustrating an example of the circuit structure of the sensor unit according to the fourth embodiment.

[0039] Figure 22 This is a diagram showing an example of the structure of the controller according to the fourth embodiment.

[0040] Figure 23 This is a structural diagram illustrating a modified example of an electric power steering system.

[0041] Figure 24 This is a structural diagram illustrating a modified example of an electric power steering system.

[0042] Figure 25 This is a structural diagram illustrating a modified example of an electric power steering system. Detailed Implementation

[0043] The embodiments of the present invention will be described in detail with reference to the accompanying drawings. Furthermore, the embodiments of the present invention shown below illustrate apparatus and methods for embodying the technical concept of the present invention; the technical concept of the present invention is not limited to the structure and arrangement of the constituent components as described below. Various modifications can be made to the technical concept of the present invention within the scope of the claims as defined in the claims.

[0044] (First Embodiment)

[0045] (structure)

[0046] The following describes a structural example of applying the rotation angle detection device of the embodiment to an electric power steering (EPS) system that applies steering assistance force to the vehicle's steering mechanism using the rotational force of a motor. However, the present invention is not limited to rotation angle detection devices applied to electric power steering systems, and can be widely applied to rotation angle detection devices having at least two sensors that output signals corresponding to the rotation of the motor's rotation shaft.

[0047] Reference Figure 1 The column shafts (steering shafts) 2i and 2o of the steering wheel 1 are connected to the tie rods 6 of the steering wheels via reduction gears 3, universal joints 4A and 4B, and rack and pinion mechanism 5. The input shaft 2i and output shaft 2o of the column shaft are connected by a torsion bar (not shown) that twists due to the deviation of the rotation angle between the input shaft 2i and the output shaft 2o.

[0048] Torque sensor 10 electromagnetically measures the torsion angle of the torsion bar as the steering torque Th of steering wheel 1.

[0049] Furthermore, a motor 20 that assists in the steering force of the steering wheel 1 is connected to the output shaft 2o of the column shaft via a reduction gear 3.

[0050] The controller 40 is an electronic control unit (ECU) that drives the motor 20. Battery power Vbat is supplied to the controller 40 from the battery 14, which serves as a power source, and an ignition switch signal IG is input to the controller 40 from the ignition switch 11, which serves as a power switch.

[0051] The controller 40 calculates the steering assist command value of the assist command using the assist mapping, etc., based on the steering torque Th detected by the torque sensor 10 and the vehicle speed Vh detected by the vehicle speed sensor 12, and provides the drive current I to the motor 20 based on the calculated steering assist command value.

[0052] The sensor unit 30 has two sensors that output sensor signals corresponding to the rotation of the motor rotation shaft of the motor 20.

[0053] The two sensors in sensor unit 30 independently detect the angular position θ (θ = 0~360 degrees) of the motor's rotating shaft. One sensor outputs a first sine signal sin1 = A × sinθ + Voff1 and a first cosine signal cos1 = A × cosθ + Voff1 with amplitude A to controller 40. The other sensor outputs a second sine signal sin2 = A × sinθ + Voff2 and a second cosine signal cos2 = A × cosθ + Voff2 with amplitude A to controller 40. Voltages Voff1 and Voff2 are offset voltages (i.e., the DC components of the first sine signal sin1, the first cosine signal cos1, the second sine signal sin2, and the second cosine signal cos2). Figure 2 An example is shown of the first sine signal sin1, the first cosine signal cos1, the second sine signal sin2, and the second cosine signal cos2.

[0054] The controller 40 calculates the rotation angle θm of the motor rotation shaft of the motor 20 based on the first sine signal sin1, the first cosine signal cos1, the second sine signal sin2, and the second cosine signal cos2.

[0055] The controller 40 calculates the rotation angle θo of the output shaft 2o of the column shaft based on the rotation angle θm of the motor shaft of the motor 20 and the gear ratio Rg of the reduction gear 3. The controller 40 calculates the rotation angle θi of the input shaft 2i of the column shaft, i.e., the steering angle θs of the steering wheel 1, based on the rotation angle θo and the steering torque Th.

[0056] In this type of electric power steering system, a torque sensor 10 detects the steering torque Th caused by the driver's steering wheel operation transmitted from the steering wheel 1. The steering assist command value calculated based on the steering torque th and the vehicle speed Vh drives the control motor 20 to provide the steering system with an assist force (steering assist force) for the driver's steering wheel operation.

[0057] Figure 3 This is a schematic exploded view showing an example of a sensor unit 30. The sensor unit 30 has a magnet 31 and a circuit board 32.

[0058] The magnet 31 is fixed to the end 24 of the motor rotation shaft 21 of the motor 20 on the side opposite to the output end 22, and has different magnetic poles (S pole and N pole) arranged circumferentially along the motor rotation shaft 21.

[0059] The circuit board 32 has a first sensor 33 and a second sensor 34. The first sensor 33 and the second sensor 34 detect the magnetic flux generated from the magnet 31 and output a first sensor signal and a second sensor signal respectively corresponding to the rotation of the motor rotation shaft 21 of the motor 20.

[0060] The first sensor signal output from the first sensor 33 includes a first sine signal sin1 and a first cosine signal cos1. The second sensor signal output from the second sensor 34 includes a second sine signal sin2 and a second cosine signal cos2.

[0061] The first sensor 33 and the second sensor 34 can be, for example, MR sensors for detecting magnetic flux (e.g., TMR (Tunnel Magneto Resistance) sensors).

[0062] The first sensor 33 and the second sensor 34 are configured close to the magnet 31 that rotates together with the motor shaft 21. By detecting the magnetic flux generated from the magnet 31, they generate a first sine signal sin1 and a first cosine signal cos1, as well as a second sine signal sin2 and a second cosine signal cos2, respectively, corresponding to the rotation of the motor shaft 21.

[0063] The sensor unit 30 is configured as a separate unit from the controller 40 and is connected to the controller 40 via a wiring harness 35. The controller 40 supplies power supplies Vs1 (for the first sensor 33) and Vs2 (for the second sensor 34) to the sensor unit 30 via the wiring harness 35. The sensor unit 30 outputs the first sensor signal and the second sensor signal to the controller 40 via the wiring harness 35. The length of the wiring harness 35 may be, for example, approximately 10 cm.

[0064] Alternatively, the sensor unit 30 and the controller 40 can be integrated into a single unit. In this case, the first sensor 33 and the second sensor 34 can be directly integrated into the controller 40, and the controller 40 can be mounted on the side of the motor 20 opposite to the output terminal 22.

[0065] Furthermore, the structure of the sensor unit 30 is not limited to Figure 3The structure shown. The first sensor 33 and the second sensor 34 of the sensor unit 30 can also be sensors other than MR sensors. The first sensor 33 can simply be a sensor that outputs a signal corresponding to the rotation of the motor shaft 21. The second sensor 34 can simply be a sensor that outputs a sine wave and a cosine wave corresponding to the rotation of the motor shaft 21.

[0066] Reference Figure 4 The structure of controller 40 will be described as an example. Controller 40 has a power management unit 50 and a microprocessor (MPU) 60.

[0067] The power management unit 50 receives power from the battery 14 via a battery power source Vbat to manage the power supply to the sensor unit 30 and the controller 40. The power management unit 50 can be installed as a single integrated circuit (IC) chip. For example, the power management unit 50 can be a power management integrated circuit (Power Management Integrated Circuit).

[0068] The power management unit 50 generates, based on the ignition switch signal IG, a first sensor power supply Vs1 for driving the first sensor 33, a second sensor power supply Vs2 for driving the second sensor 34, and a power supply Vm for driving other components such as the MPU 60 and controller 40 (hereinafter sometimes referred to as "MPU 60, etc.").

[0069] The voltages of the first sensor power supply Vs1, the second sensor power supply Vs2, and the power supply Vm can, for example, be the same power supply voltage Vcc1 (not shown). The power supply voltage Vcc1 can, for example, be 5V.

[0070] During the period when the ignition switch 11 is turned on, the power management unit 50 supplies the power supply Vs1 of the first sensor, the power supply Vs2 of the second sensor, and the power supply Vm to the first sensor 33, the second sensor 34, and the MPU 60, respectively.

[0071] On the other hand, the power management unit 50 stops supplying the first sensor power supply Vs1 and power supply Vm to the first sensor 33 and MPU 60, etc., during the period when the ignition switch 11 is off. The second sensor power supply Vs2 is intermittently supplied to the second sensor 34 according to a predetermined period T. The voltage of the second sensor power supply Vs2 supplied during the period when the ignition switch 11 is off may also be lower than the voltage Vcc1 during the period when the ignition switch 11 is on.

[0072] Furthermore, the power management unit 50 detects the number of rotations of the motor shaft 21 based on the second sine signal sin2 and the second cosine signal cos2, and generates rotation count information representing the number of rotations. The rotation count information includes a sine count value CNTs obtained by counting the changes in the sign of the second sine signal sin2 and a cosine count value CNTc obtained by counting the changes in the sign of the second cosine signal cos2. The sine count value CNTs and the cosine count value CNTc change according to the combination of the signs of the second sine signal sin2 and the second cosine signal cos2. Details of the power management unit 50 will be described later.

[0073] Based on the steering torque Th detected by the torque sensor 10 and the vehicle speed Vh detected by the vehicle speed sensor 12, the MPU 60 calculates the steering assist command value of the assist command using assist mapping, thereby controlling the drive current I of the motor 20.

[0074] Furthermore, the MPU 60 calculates the angular position information θ1, representing the angular position of the motor rotating shaft 21, based on the first sine signal sin1 and the first cosine signal cos1. The angular position information θ1 represents the angular position within the angular range of one revolution of the motor rotating shaft 21 (θ1 = 0 to 360 [deg]).

[0075] Based on the rotation count information (sine count value CNTs and cosine count value CNTc) and angular position information θ1 generated by the power management unit 50, the MPU 60 calculates the rotation angle information θm, which represents the rotation angle of the motor rotating shaft 21. The rotation angle information θm represents the rotation angle within the angle range of more than one rotation of the motor rotating shaft 21.

[0076] Specifically, the MPU 60 stops operating because the power supply Vm to the MPU 60 is stopped during the period when the ignition switch 11 is off.

[0077] At the moment when the ignition switch 11 changes from off to on, the MPU 60 reads the number of rotations from the power management unit 50 and calculates the rotation angle information θm based on the number of rotations and the angle position information θ1.

[0078] During the period when the ignition switch 11 is on, the MPU 60 accumulates the angle change of the angular position information θ1 after the moment when the ignition switch 11 changes from off to on into the rotation angle information θm calculated at the moment when the ignition switch 11 changes from off to on, thereby calculating the rotation angle information θm after the moment when the ignition switch 11 changes from off to on.

[0079] The MPU 60 multiplies the rotation angle information θm by the gear ratio Rg of the reduction gear 3 to calculate the rotation angle θo of the output shaft 2o of the column shaft. Furthermore, based on the steering torque Th detected by the torque sensor 10, the torsion angle θt of the torsion bar installed on the column shaft is calculated, and the rotation angle θo of the output shaft 2o is added to the torsion angle θt to calculate the rotation angle θi of the input shaft 2i of the column shaft (the steering angle θs of the steering wheel 1).

[0080] The controller 40 can also control the steering assist force applied to the output shaft 2o by the motor 20 based on the rotation angle θo of the output shaft 2o and the rotation angle θi of the input shaft 2i. For example, the controller 40 can determine whether the column shaft is in end contact state based on the rotation angle information. When the column shaft is in end contact state, the controller 40 can also limit the drive current I of the motor 20 to correct the steering assist force. Furthermore, the controller 40 can also use the rotation angle θi of the input shaft 2i to determine whether the input shaft 2i is in a neutral position.

[0081] Furthermore, for example, controller 40 can also determine whether the steering wheel 1 is in an increasing or decreasing yaw state based on the rotation angle information. For example, controller 40 can also determine whether it is in an increasing or decreasing yaw state based on the rotation angle of the column shaft and its direction of change. Furthermore, controller 40 can also determine whether it is in an increasing or decreasing yaw state based on the rotation angle of the column shaft and the steering torque Th.

[0082] The controller 40 increases the drive current I to increase the steering assist force when the yaw increases, and decreases the drive current I to decrease the steering assist force when the yaw decreases. Details of the MPU 60 will be further described later.

[0083] Next, refer to Figure 5 An example of the functional structure of the power management unit 50 will be described. The power management unit 50 includes a regulator 51, a first power supply unit 52, a second power supply unit 53, a third power supply unit 54, a power control unit 56, and a rotation count detection unit 58.

[0084] The regulator 51, the first power supply unit 52, the second power supply unit 53, the third power supply unit 54, and the power control unit 56 are examples of the "power supply unit" described in the technical solution.

[0085] Regulator 51 generates a regulator power supply VR with a specified voltage from the battery power supply Vbat. The voltage of the regulator power supply VR is, for example, 6V. The first power supply unit 52, the second power supply unit 53, and the third power supply unit 54 generate power supply Vm, the first sensor power supply Vs1, and the second sensor power supply Vs2 from the regulator power supply VR, respectively.

[0086] Alternatively, the power supply Vm and the power supply Vs1 of the first sensor can be shared, and the first power supply unit 52 and the second power supply unit 53 can be used as a single power supply unit. That is, the first sensor 33 and the MPU 60, etc., can also be powered from one or more power supply units.

[0087] Based on the ignition switch signal IG, the power control unit 56 outputs control signals Sc1, Sc2 and Sc3 to the first power supply unit 52, the second power supply unit 53 and the third power supply unit 54 respectively, and controls the first power supply unit 52, the second power supply unit 53 and the third power supply unit 54.

[0088] While the ignition switch 11 is on, the power control unit 56 causes the first power supply unit 52, the second power supply unit 53, and the third power supply unit 54 to generate power Vm, power Vs1 for the first sensor, and power Vs2 for the second sensor, respectively. The first power supply unit 52 continuously supplies power Vm to the MPU 60 and the like. The second power supply unit 53 continuously supplies power Vs1 to the first sensor 33. The third power supply unit 54 continuously supplies power Vs2 to the second sensor 34 and the rotation count detection unit 58. Therefore, the MPU 60 and the like, the first sensor 33, the second sensor 34, and the rotation count detection unit 58 operate continuously.

[0089] During the period when the ignition switch 11 is off, the power control unit 56 stops the first power supply unit 52 and the second power supply unit 53. That is, the generation of power supply Vm and first sensor power supply Vs1 is stopped. As a result, the supply of first sensor power supply Vs1 to the first sensor 33 and the supply of power supply Vm to the MPU 60, etc., are stopped, and the operation of the first sensor 33 and the MPU 60, etc., is stopped.

[0090] On the other hand, the power control unit 56 causes the third power supply unit 54 to intermittently generate the second sensor power supply Vs2 according to a predetermined period T. Thus, the second sensor power supply Vs2 is intermittently supplied to the second sensor 34 and the rotation count detection unit 58. The second sensor 34 and the rotation count detection unit 58 operate intermittently according to the predetermined period T. The power control unit 56 may also set the voltage of the second sensor power supply Vs2 during the period when the ignition switch 11 is off to be lower than during the period when the ignition switch 11 is on.

[0091] The rotation count detection unit 58 detects the number of rotations of the motor rotating shaft 21 based on the second sine signal sin2 and the second cosine signal cos2, and generates rotation count information (i.e., sine count value CNTs and cosine count value CNTc) representing the number of rotations.

[0092] The rotation count detection unit 58 includes a first comparator 58a, a second comparator 58b, a sine counter 58c, and a cosine counter 58d.

[0093] The first comparator 58a compares the second sine signal sin2 with the threshold voltage Vr and generates a sign signal Cs representing the sign of the second sine signal sin2. The sign signal Cs has a value of "1" when the second sine signal sin2 is above the threshold voltage Vr, and a value of "0" when the second sine signal sin2 is less than the threshold voltage Vr.

[0094] The second comparator 58b compares the second cosine signal cos2 with the threshold voltage Vr, generating a sign signal Cc representing the sign of the second cosine signal cos2. The sign signal Cc has a value of "1" when the second cosine signal cos2 is above the threshold voltage Vr, and a value of "0" when the second cosine signal cos2 is less than the threshold voltage Vr.

[0095] Since the second sine signal sin2 and the second cosine signal cos2 have a DC offset component Voff2, the threshold voltage Vr can be set to the offset voltage Voff2, for example.

[0096] The symbol signals Cs and Cc are input to the sine counter 58c and the cosine counter 58d.

[0097] Reference Figure 6 (a) and Figure 6 (b) Figure 6 The dashed waveform in (a) represents an example of the second sine signal sin2, and the solid waveform represents an example of the second cosine signal cos2.

[0098] In this embodiment, the amplitude A of the second sine signal sin2 and the second cosine signal cos2 is half the voltage of the second sensor power supply Vs2 (i.e., Vs2 / 2), and the DC component is offset by half the voltage of the second sensor power supply Vs2, varying within the range of 0 [V] to the voltage of the second sensor power supply Vs2 (i.e., Vs2). Therefore, the threshold voltage Vr is set to half the voltage of the second sensor power supply Vs2 (i.e., Vs2 / 2).

[0099] The sign signal Cs of the second sine signal sin2 output from the first comparator 58a has a value of "1" in the range of angular position of the motor rotation shaft 21 from 0 [deg] to 180 [deg], and a value of "0" in the range of 180 [deg] to 360 [deg].

[0100] The sign signal Cc of the second cosine signal cos2 output from the second comparator 58b has a value of "1" in the range of angular position of the motor rotation shaft 21 from 0 [deg] to 90 [deg] and from 270 [deg] to 360 [deg], and a value of "0" in the range from 90 [deg] to 270 [deg].

[0101] Reference Figure 5 The sine counter 58c and cosine counter 58d count the changes in the combination of the signs of the second sine signal sin2 and the second cosine signal cos2 based on the sign signal Cs and Cc of the second sine signal sin2 and the second cosine signal cos2, respectively, and calculate the sine count value CNTs and the cosine count value CNTc.

[0102] Reference Figure 6 (c) and Figure 6 (d). The sine counter 58c calculates the sine count value CNTs by counting the number of sign changes of the second sine signal sin2, and the cosine counter 58d calculates the cosine count value CNTc by counting the number of sign changes of the second cosine signal cos2. The sine counter 58c and the cosine counter 58d store the calculated sine count value CNTs and cosine count value CNTc in, for example, non-volatile memory (not shown).

[0103] Specifically, during the period when the sign signal Cc of the second cosine signal cos2 has a value of "1", when the value of the sign signal Cs of the second sine signal sin2 changes from "0" to "1", the sine counter 58c increases the sine count value CNTs by 1; when the value of the sign signal Cs of the second sine signal sin2 changes from "1" to "0", the sine counter 58c decreases the sine count value CNTs by 1.

[0104] Furthermore, during the period when the sign signal Cc of the second cosine signal cos2 has a value of "0", when the value of the sign signal Cs of the second sine signal sin2 changes from "1" to "0", the sine counter 58c increases the sine count value CNTs by 1, and when the value of the sign signal Cs of the second sine signal sin2 changes from "0" to "1", the sine counter 58c decreases the sine count value CNTs by 1.

[0105] During the period when the sign signal Cs of the second sine signal sin2 has a value of "0", when the value of the sign signal Cc of the second cosine signal cos2 changes from "0" to "1", the cosine counter 58d increases the cosine count value CNTc by 1. When the value of the sign signal Cc of the second cosine signal cos2 changes from "1" to "0", the cosine counter 58d decreases the cosine count value CNTc by 1.

[0106] Furthermore, during the period when the sign signal Cs of the second sine signal sin2 has a value of "1", when the value of the sign signal Cc of the second cosine signal cos2 changes from "1" to "0", the cosine counter 58d increases the cosine count value CNTc by 1, and when the value of the sign signal Cc of the second cosine signal cos2 changes from "0" to "1", the cosine counter 58d decreases the cosine count value CNTc by 1.

[0107] Therefore, when the motor shaft 21 rotates one revolution, the sine count value CNTs and the cosine count value CNTc each increase or decrease by 2 according to the direction of rotation. Thus, the sum of the sine count value CNTs and the cosine count value CNTc (sometimes referred to below as the "total count value CNT") is as follows: Figure 6 As shown in (e), the number of rotations increases or decreases by 4 corresponding to the direction of rotation for each revolution of the motor shaft 21. Therefore, the combination or total count of the sine count CNTs and cosine count CNTc represents the number of revolutions in one-quarter rotational unit. Thus, the combination or total count of the sine count CNTs and cosine count CNTc indicates which quadrant of the four quadrants, which divides the rotational range of the motor shaft 21 into four parts, the angular position of the motor shaft 21 belongs to.

[0108] Furthermore, the sine count value CNTs and cosine count value CNTc in this embodiment are illustrative, and the rotation count information of the present invention is not limited to the sine count value CNTs and cosine count value CNTc. The rotation count information is any rotation count information in which n is set to a natural number of 2 or more and represents the number of rotations of 1 / n rotation unit.

[0109] Next, refer to Figure 7 An example of the functional structure of the MPU 60 will be described. The MPU 60 includes an angle position calculation unit 61, a counting and totaling unit 62, a rotation count information correction unit 63, a rotation count calculation unit 64, a torsion angle calculation unit 65, a rotation angle information calculation unit 66, a diagnostic unit 67, and an auxiliary control unit 68.

[0110] The functions of the angle position calculation unit 61, the counting and totaling unit 62, the rotation circle information correction unit 63, the rotation circle calculation unit 64, the torsion angle calculation unit 65, the rotation angle information calculation unit 66, the diagnostic unit 67, and the auxiliary control unit 68 are realized by the MPU 60 executing the program stored in the storage device (e.g., non-volatile memory) of the MPU 60 or the controller 40.

[0111] The rotation angle information calculation unit 66 is an example of the "rotation angle calculation unit" and "steering angle calculation unit" described in the technical solution. The auxiliary control unit 68 is an example of the "motor control unit" described in the technical solution.

[0112] The angle position calculation unit 61 inputs the first sine signal sin1 and the first cosine signal cos1, and compensates for the errors (offset, amplitude difference, phase difference, etc.) contained in these signals. Figure 8 (a) represents an example of the first sine signal sin1 and the first cosine signal cos1. The angle position calculation unit 61 calculates angle position information θ1 (θ1 = 0~360 [deg]) representing the angle position within the angle range of one revolution of the motor rotating shaft 21, based on the first sine signal sin1 and the first cosine signal cos1 after error compensation. Figure 8 (b) shows an example of angular position information θ1.

[0113] For example, the angle position calculation unit 61 can calculate the angle position information θ1 based on the sum (cos1+sin1) and difference (cos1-sin1) of the first sine signal sin1 and the first cosine signal cos1.

[0114] Similarly, the angle position calculation unit 61 inputs the second sine signal sin2 and the second cosine signal cos2, and calculates the angle position information θ2 (θ2=0~360[deg]) representing the angle position within the angle range of one revolution of the motor rotating shaft 21 to compensate for the error.

[0115] Reference Figure 7 At the moment when power supply Vm to the MPU 60 begins (i.e., the moment the ignition switch 11 changes from off to on), the counting and totalizing unit 62 reads the sine counter 58c and the cosine counter 58d from the power management unit 50, respectively, the sine counter value CNTs and the cosine counter value CNTc. The counting and totalizing unit 62 adds the sine counter value CNTs and the cosine counter value CNTc to calculate... Figure 6 The total count value CNT is shown in (e).

[0116] Here, due to errors contained in the second sine signal sin2 and the second cosine signal cos2, and the error in the comparator's threshold voltage Vr, errors sometimes occur in the sine count value CNTs and the cosine count value CNTc. As a result, errors sometimes also occur in the total count value CNT.

[0117] Reference Figure 7The rotation count information correction unit 63 corrects the total count value CNT based on the angular position information θ1, compensating for any errors in the total count value CNT. The rotation count information correction unit 63 outputs the corrected total count value CNTa after error compensation. Details of the rotation count information correction unit 63 will be described later.

[0118] The rotation count calculation unit 64 calculates the quotient obtained by dividing the calibrated total count value CNTa by the natural number n, and takes this quotient as the number of rotations Nr of the motor shaft 21. The natural number n is the increment or decrement of the total count value CNT for each rotation of the motor shaft 21; in this embodiment, the natural number n is "4". Figure 8 (c) shows an example of the number of rotations Nr.

[0119] The torsion angle calculation unit 65 calculates the torsion angle θt of the torsion bar installed on the column shaft based on the steering torque Th detected by the torque sensor 10.

[0120] Reference Figure 7 At the moment when the power supply Vm to the MPU 60 begins (i.e., the moment when the ignition switch 11 changes from off to on), the rotation angle information calculation unit 66 calculates the rotation angle information θm within the angle range of more than one rotation of the motor rotating shaft 21 based on the rotation number Nr calculated by the rotation number calculation unit 64 and the angle position information θ1 calculated by the angle position calculation unit 61.

[0121] The rotation angle information calculation unit 66 calculates the rotation angle information θm = (360 [deg] × number of rotations Nr) + angular position information θ1 using multiplier 66a and adder 66b. Figure 8 Example of rotation angle information θm is shown in (d).

[0122] Subsequently, during the period when the ignition switch 11 is turned on, the rotation angle information calculation unit 66 accumulates the angle change of the angle position information θ1 after the moment when the ignition switch 11 changes from off to on onto the rotation angle information θm calculated at the moment when the ignition switch 11 changes from off to on, and calculates the rotation angle information θm after the moment when the ignition switch 11 changes from off to on.

[0123] Reference Figure 7 Multiplier 66c multiplies the rotation angle information θm by the gear ratio Rg of reduction gear 3 to calculate the rotation angle θo of the output shaft 2o of the column shaft. Adder 66d adds the torsion angle θt of the torsion bar to the rotation angle θo to calculate the rotation angle θi of the input shaft 2i of the column shaft (steering angle θs of steering wheel 1). The rotation angle information calculation unit 66 outputs the rotation angle information θo and rotation angle θi.

[0124] The rotation angle θo of the output shaft 2o or the rotation angle θi of the input shaft 2i can be used in the controller 40 to determine whether the column shaft is in end contact state and whether the steering wheel 1 is in a state of increased deflection or deflection return. The controller 40 can also control the steering assist force applied to the output shaft 2o by the motor 20 based on these determinations. Furthermore, the rotation angle θi of the input shaft 2i can also be used to determine whether the input shaft 2i is in a neutral position.

[0125] The diagnostic unit 67 compares the angle position information θ1 calculated based on the first sine signal sin1 and the first cosine signal cos1 with the angle position information θ2 calculated based on the second sine signal sin2 and the second cosine signal cos2, and determines an anomaly generated in the first sensor 33 or the second sensor 34. For example, if the difference between the angle position information θ1 and the angle position information θ2 is greater than or equal to a threshold, it is determined that an anomaly has occurred in the first sensor 33 or the second sensor 34.

[0126] Furthermore, the diagnostic unit 67 determines an abnormality occurring in the second sensor 34 or the rotation count detection unit 58 based on the difference between the sine count value CNTs and the cosine count value CNTc. For example, if the difference between the sine count value CNTs and the cosine count value CNTc is 2 or more, it is determined that an abnormality has occurred in the second sensor 34 or the rotation count detection unit 58.

[0127] The diagnostic unit 67 outputs a diagnostic signal Sd, representing the determination result, to the auxiliary control unit 68.

[0128] The auxiliary control unit 68 controls the drive current I of the motor 20 based on the steering torque Th detected by the torque sensor 10 and the vehicle speed Vh detected by the vehicle speed sensor 12.

[0129] exist Figure 9 The diagram shows an example of the functional structure of the auxiliary control unit 68. The steering torque Th detected by the torque sensor 10 and the vehicle speed Vh detected by the vehicle speed sensor 12 are input to the current command value calculation unit 71, which calculates the current command value Iref1. Based on the input steering torque Th and vehicle speed Vh, the current command value calculation unit 71 calculates the current command value Iref1, which is the control target value of the current supplied to the motor 20, using auxiliary mapping and the like.

[0130] The current command value Iref1 is input to the current limiting unit 73 via the adder 72A. The current command value Irefm, after being limited to the maximum current, is input to the subtraction unit 72B. The deviation ΔI (=Irefm-Im) between Iref1 and the feedback motor current value Im is calculated. This deviation ΔI is input to the PI (proportional-integral) control unit 75 for improving the characteristics of steering action. The voltage control command value Vref obtained by the PI control unit 75 after characteristic improvement is input to the PWM control unit 76, and then the motor 20 is driven by the inverter 77, which serves as the drive unit, using PWM. The current value Im of the motor 20 is detected by the motor current detector 78 and fed back to the subtraction unit 72B.

[0131] The compensation signal CM from the compensation signal generation unit 74 is added to the addition unit 72A. By adding the compensation signal CM, the characteristics of the steering system are compensated, improving convergence, inertial characteristics, etc. The compensation signal generation unit 74 uses the addition unit 74-4 to add the automatic alignment torque (SAT) 74-3 and the inertia 74-2, and further uses the addition unit 74-5 to add the convergence 74-1 to the addition result. The addition result of the addition unit 74-5 is used as the compensation signal CM.

[0132] Reference Figure 7 When the auxiliary control unit 68 detects an abnormality based on the diagnostic signal Sd output from the diagnostic unit 67, it performs prescribed abnormality response procedures such as stopping the motor 20 drive and outputting an alarm.

[0133] Next, the rotation count information correction unit 63 will be explained. As described above, due to the errors contained in the second sine signal sin2 and the second cosine signal cos2, and the error of the comparator threshold voltage Vr, the total count value CNT output from the rotation count calculation unit 64 may sometimes have an error.

[0134] The following example illustrates the case where the comparator's threshold voltage Vr has an error, and explains the error caused by the total count value CNT.

[0135] exist Figure 10 Example (a) shows the threshold voltage Vr of the second sine signal sin2 and the second cosine signal cos2, as well as the first comparator 58a and the second comparator 58b. The dashed line represents the second sine signal sin2, the solid line represents the second cosine signal cos2, the double-dotted line represents the threshold voltage Vr compared with the second sine signal sin2 in the first comparator 58a, and the single-dotted line represents the threshold voltage Vr compared with the second cosine signal cos2 in the second comparator 58b.

[0136] In this example, the threshold voltage Vr (double-dotted line) compared with the second sine signal sin2 is lower than the design value (ideal value).

[0137] The result is that the sine count value CNTs and the cosine count value CNTc are as follows: Figure 10 As shown in (b), the dashed line represents the sine count value CNTs, and the solid line represents the cosine count value CNTc.

[0138] As shown in the figure, the timing of the rise (fall) of the sine count value CNTs that should be generated when the motor rotates at angles of 180, 360, 540, 720, 900, 1080, ... [deg] has deviated.

[0139] The result is, as Figure 10 As shown in (c), there is also a deviation in the timing of the rise (fall) of the total count value CNT. As shown by the enclosing line of the single-dotted line, there is a deviation in the timing of the rise (fall) of the total count value CNT that should occur when the motor rotation angle is 180, 360, 540, 720, 900, 1080, ... [deg].

[0140] Thus, the errors contained in the second sine signal sin2 and the second cosine signal cos2, and the error of the comparator's threshold voltage Vr, cause errors in the total count value CNT in the form of a deviation in the timing of the rise (fall) of the total count value CNT.

[0141] When the timing of the rise (fall) of the total count value CNT deviates, such as Figure 11 As shown in (a), the rising (falling) timing of the motor rotation number Nr calculated by the rotation number calculation unit 64 deviates from the original timing.

[0142] When using the number of rotations Nr of the motor to calculate the rotation angle information θm, such as Figure 11 As shown in (b), the number of rotations is incorrectly generated in the area surrounded by the single-dot dashed line, resulting in an error in the rotation angle information θm.

[0143] Therefore, the rotation count information correction unit 63 pairs Figure 10 The deviation in the timing of the rise (fall) of the total count value CNT shown in (c) is corrected.

[0144] Reference Figure 12 The rotation count information correction unit 63 includes a first quadrant information calculation unit 63a, a second quadrant information calculation unit 63b, a quadrant comparison unit 63c, and a correction unit 63d.

[0145] The first quadrant information calculation unit 63a calculates the first quadrant information Q1 based on the angular position information θ1. The first quadrant information Q1 indicates which quadrant the angular position of the motor rotating shaft 21 belongs to, which is obtained by dividing the rotation range of the motor rotating shaft 21 according to the natural number n mentioned above.

[0146] The second quadrant information calculation unit 63b calculates the second quadrant information Q2 based on the total count value CNT, which is the rotation number information. The second quadrant information Q2 indicates which quadrant the angular position of the motor rotation shaft 21 belongs to, which is divided into quadrants by the natural number n mentioned above.

[0147] As described above, the natural number n is the increment or decrement of the total count CNT for each rotation of the motor shaft 21. In this embodiment, the natural number n is "4". The first quadrant information Q1 and the second quadrant information Q2 indicate which quadrant of the first, second, third, and fourth quadrants the angular position of the motor shaft 21 belongs to.

[0148] The first quadrant information calculation unit 63a can perform a threshold determination on which of the angle ranges from the first quadrant to the nth quadrant the angular position information θ1 belongs to, thereby calculating the first quadrant information Q1.

[0149] The second quadrant information calculation unit 63b can calculate the remainder when the total count value CNT is divided by the natural number n (modulo: CNT mod n) as the second quadrant information Q2.

[0150] exist Figure 13 Example (a) shows an example of first quadrant information Q1 and second quadrant information Q2. The solid line represents first quadrant information Q1, and the dashed line represents second quadrant information Q2. Since... Figure 10 The deviation in the timing of the rise (fall) of the total count value CNT shown in (c) indicates that the information Q1 in the first quadrant and the information Q2 in the second quadrant are different in the area enclosed by the single-dot dash.

[0151] Reference Figure 12 The quadrant comparison unit 63c outputs the quadrant difference, which is the comparison result obtained by comparing the information Q1 in the first quadrant and the information Q2 in the second quadrant.

[0152] For example, the quadrant comparison unit 63c can calculate the difference obtained by subtracting the number of the first quadrant information Q1 from the number of the second quadrant information Q2 representing the quadrant as shown in equation (1) as the quadrant difference.

[0153] Quadrant difference = Q2 - Q1…(1)

[0154] However, when the information Q2 in the second quadrant represents the first quadrant and the information Q1 in the first quadrant represents the fourth quadrant, the sum obtained by adding 4 (i.e., the natural number n) to the subtraction result is calculated as the quadrant difference, as shown in equation (2).

[0155] Quadrant difference = Q2 - Q1 + 4, where Q1 = quadrant 4, Q2 = quadrant 1…(2)

[0156] Furthermore, when the information Q2 in the second quadrant represents the fourth quadrant and the information Q1 in the first quadrant represents the first quadrant, the difference obtained by subtracting 4 (i.e., the natural number n) from the subtraction result is calculated as the quadrant difference in the following formula (3).

[0157] Quadrant difference = Q2 - Q1 - 4, where Q1 = quadrant 1, Q2 = quadrant 4...(3)

[0158] exist Figure 13 Example of quadrant difference is shown in (b). Figure 13 The first quadrant information Q1 and the second quadrant information Q2 of (a) have quadrant differences with any value among “1”, “0”, and “-1”.

[0159] Reference Figure 12 The correction unit 63d corrects the total count value CNT based on the quadrant difference output by the quadrant comparison unit 63c, and calculates the corrected total count value CNTa.

[0160] For example, the correction unit 63d calculates the difference obtained by subtracting the quadrant difference from the total count value CNT as the corrected total count value CNTa.

[0161] Figure 13 (c) shows from Figure 10 The total count of (c) is CNT minus Figure 13 The corrected total count value CNTa is calculated based on the quadrant difference of (b).

[0162] right Figure 10 (c) and Figure 13 By comparing (c), it can be seen that the deviation in the rising (falling) timing when the motor rotation angle is 180, 360, 540, 720, 900, 1080, ... [deg] has been corrected.

[0163] When calculating the number of motor revolutions Nr based on the total corrected count value CNTa, as follows: Figure 13 As shown in (d). Figure 13 The number of motor revolutions Nr of (d) is the same as Figure 8 The same result was obtained for the number of motor rotations Nr in (c), indicating that the error was corrected.

[0164] (action)

[0165] Next, the operation of the motor control device according to the embodiment will be explained.

[0166] (1) During the period when the ignition switch is off

[0167] The power control unit 56 of the power management unit 50 stops the first power supply unit 52 and the second power supply unit 53, and only operates the third power supply unit 54. At this time, the power control unit 56 causes the third power supply unit 54 to intermittently generate the second sensor power supply Vs2 according to a predetermined period T.

[0168] The power supply Vs2 for the second sensor is intermittently supplied to the second sensor 34 and the rotation count detection unit 58. The second sensor 34 and the rotation count detection unit 58 operate intermittently according to a predetermined period T.

[0169] During the operation of the rotation count detection unit 58, the sine counter 58c increments or decrements the sine count value CNTs based on the output of the first comparator 58a. The cosine counter 58d increments or decrements the cosine count value CNTc based on the output of the second comparator 58b.

[0170] Thus, during the period when the ignition switch 11 is off, only the power management unit 50 and the second sensor 34 continue to operate, while other units such as the MPU 60 and the first sensor 33 stop operating.

[0171] (2) The moment when the ignition switch changes from off to on

[0172] The power control unit 56 initiates the operation of the first power supply unit 52 and the second power supply unit 53. Furthermore, the power control unit 56 causes the first power supply unit 52, the second power supply unit 53, and the third power supply unit 54 to continuously generate power Vm, the first sensor power supply Vs1, and the second sensor power supply Vs2. Power Vm, the first sensor power supply Vs1, and the second sensor power supply Vs2 are then continuously supplied to the MPU 60, the first sensor 33, the second sensor 34, and the rotation count detection unit 58. Therefore, during the period when the ignition switch 11 is on, the MPU 60, the first sensor 33, the second sensor 34, and the rotation count detection unit 58 operate continuously.

[0173] When the ignition switch 11 changes from off to on, the counting unit 62 of the MPU 60 reads the sine count value CNTs and the cosine count value CNTc from the sine counter 58c and the cosine counter 58d respectively, and calculates the total count value CNT.

[0174] The rotation count information correction unit 63 corrects the total count value CNT and outputs a corrected total count value CNTa. The rotation count calculation unit 64 calculates the number of rotations Nr of the motor rotating shaft 21 based on the corrected total count value CNTa.

[0175] The angle position calculation unit 61 calculates the angle position information θ1, and the rotation angle information calculation unit 66 calculates the rotation angle information θm of the motor rotation shaft 21 based on the number of rotations Nr and the angle position information θ1.

[0176] (3) During the period when the ignition switch is turned on

[0177] The power control unit 56 causes the first power supply unit 52, the second power supply unit 53, and the third power supply unit 54 to operate, continuously generating power supply Vm, first sensor power supply Vs1, and second sensor power supply Vs2. The MPU60, first sensor 33, second sensor 34, and rotation count detection unit 58 operate continuously.

[0178] The rotation count detection unit 58 periodically measures the outputs of the first comparator 58a and the second comparator 58b, and continuously maintains the sine count CNTs and cosine count CNTc (i.e. the current value of the motor rotation count) by increasing or decreasing the sine count CNTs and cosine count CNTc.

[0179] The angle position calculation unit 61 calculates the angle position information θ1. The rotation angle information calculation unit 66 accumulates the angle change of the angle position information θ1 after the ignition switch 11 changes from off to on into the rotation angle information θm calculated at the moment the ignition switch 11 changes from off to on, and calculates the rotation angle information θm after the moment the ignition switch 11 changes from off to on.

[0180] The rotation angle information calculation unit 66 calculates the rotation angle θo of the output shaft 2o and the rotation angle θi of the input shaft 2i based on the rotation angle information θm, the gear ratio Rg of the reduction gear 3 and the torsion angle θt of the torsion bar.

[0181] The auxiliary control unit 68 controls the drive current I of the motor 20 based on the steering torque Th detected by the torque sensor 10 and the vehicle speed Vh detected by the vehicle speed sensor 12.

[0182] The diagnostic unit 67 compares the angle position information θ1 and the angle position information θ2 to determine the abnormality generated by the first sensor 33 or the second sensor 34.

[0183] Furthermore, the diagnostic unit 67 determines the abnormality generated in the second sensor 34 or the rotation count detection unit 58 based on the difference between the sine count value CNTs and the cosine count value CNTc.

[0184] When the auxiliary control unit 68 detects an abnormality based on the diagnostic signal Sd output from the diagnostic unit 67, it performs prescribed abnormality response procedures such as stopping the drive of the motor 20 and outputting an alarm.

[0185] (Effects of the first embodiment)

[0186] (1) The first sensor 33 and the second sensor 34 output a first sensor signal and a second sensor signal respectively corresponding to the rotation of the motor rotation shaft 21 of the motor 20. The angle position calculation unit 61 calculates angle position information representing the angle position of the motor rotation shaft 21 based on the first sensor signal. The rotation count detection unit 58 detects the number of rotations of the motor rotation shaft 21 based on the second sensor signal and outputs rotation count information representing the number of rotations. The rotation angle information calculation unit 66 calculates rotation angle information representing the rotation angle of the motor rotation shaft 21 based on the angle position information and the rotation count information.

[0187] When the power switch is on, the regulator 51, the first power supply unit 52, the second power supply unit 53, the third power supply unit 54, and the power control unit 56 supply power to the first sensor 33, the second sensor 34, the angle position calculation unit 61, the rotation count detection unit 58, and the rotation angle information calculation unit 66. When the power switch is off, the power supply to the first sensor 33, the angle position calculation unit 61, and the rotation angle information calculation unit 66 is stopped, and power is supplied to the second sensor 34 and the rotation count detection unit 58.

[0188] Therefore, when the power switch is off, power consumption in the first sensor 33 and the angle position calculation unit 61 and rotation angle information calculation unit 66 that process its output signal can be stopped. Thus, power consumption during the period when the power switch is off can be reduced.

[0189] (2) The rotation count detection unit 58 can continue to detect the number of rotations of the motor shaft 21 during the period when the power switch is off. The rotation angle information calculation unit 66 can calculate the rotation angle information based on the rotation count information output by the rotation count detection unit 58 when the power switch changes from off to on and the angle position information calculated by the angle position calculation unit 61.

[0190] Therefore, even if the motor shaft 21 rotates due to external force while the power switch is off, the rotation angle of the motor shaft 21 within a range of multiple turns can be calculated when the power switch changes from off to on.

[0191] (3) The first quadrant information calculation unit 63a calculates the first quadrant information based on the angular position information. This first quadrant information indicates which quadrant (n is a natural number of 2 or more) the angular position of the motor rotating shaft 21 belongs to, obtained by dividing the rotation range of the motor rotating shaft 21 by n. The second quadrant information calculation unit 63b calculates the second quadrant information based on the rotation number information, which represents the number of rotations per nth of a rotation unit. This second quadrant information indicates which quadrant the angular position of the motor rotating shaft 21 belongs to, obtained by dividing the rotation range of the motor rotating shaft 21 by n. The correction unit 63d corrects the rotation number information based on the comparison result between the first quadrant information and the second quadrant information.

[0192] The correction unit 63d can correct the rotation number information by subtracting the difference obtained by subtracting the first quadrant information from the second quadrant information from the rotation number information.

[0193] Therefore, even if there is an error in the number of rotations calculated based on the signal from the second sensor, the error in the number of rotations can be corrected based on the angular position information calculated based on the signal from the first sensor. As a result, the accuracy of the rotation angle information can be improved.

[0194] (4) The natural number n is 4. The second sensor signal is the second sine signal sin2 and the second cosine signal cos2 corresponding to the rotation of the motor rotating shaft 21. The rotation number detection unit 58 can detect the rotation number based on the change in the combination of the signs of the second sine signal sin2 and the second cosine signal cos2.

[0195] Therefore, by using sensors that output sine and cosine signals corresponding to the rotation of the motor's rotating shaft 21, it is possible to detect the number of rotations representing a quarter-rotation unit.

[0196] (5) Furthermore, the electric power steering device of the embodiment includes: a torque sensor 10, which detects the steering torque applied to the steering shaft based on the torsion angle between the input shaft 2i and the output shaft 2o connected via a torsion bar provided on the steering shaft of the vehicle; a motor 20, which is connected to the output shaft 2o via a reduction gear 3 and applies steering assistance force to the steering shaft; a rotation angle information calculation unit 66, which calculates the rotation angle information of the motor rotation shaft 21 of the motor 20; and an auxiliary control unit 68, which performs drive control on the motor 20 based on the steering torque. The rotation angle information calculation unit 66 calculates the steering angle of the input shaft 2i based on the torsion angle, the reduction ratio of the reduction gear 3, and the rotation angle information.

[0197] Therefore, the steering angle of the steering shaft can be detected using the rotation angle information of the motor rotation shaft 21 of the motor 20, without the need to install an angle sensor to detect the steering angle of the steering shaft. For example, the steering assist force applied to the steering shaft by the motor 20 can also be controlled based on the steering angle calculated by the rotation angle information calculation unit 66.

[0198] (Second Implementation)

[0199] Next, the power management unit 50 of the second embodiment will be described. In addition to the first sensor power supply Vs1, the second sensor power supply Vs2, and the power supply Vm, the power management unit 50 of the second embodiment also generates an internal power supply Vp (see reference IG) based on the ignition switch signal IG, using the power supplied by the battery 14, to drive the digital logic circuits within the power management unit 50. Figure 14 ).

[0200] During the period when the ignition switch 11 is turned on, the power management unit 50 provides power Vm to the MPU 60 and the like in the same manner as in the first embodiment.

[0201] Furthermore, during the period when the ignition switch 11 is turned on, the power management unit 50 provides the first sensor power supply Vs1 and the second sensor power supply Vs2 to the first sensor 33 and the second sensor 34, respectively. The voltages of the first sensor power supply Vs1 and the second sensor power supply Vs2 during the period when the ignition switch 11 is turned on can, for example, be the same power supply voltage Vcc1 (e.g., Vcc1 = 5 [V]).

[0202] Furthermore, regardless of whether the ignition switch 11 is on or off, the power management unit 50 continuously supplies internal power Vp to the logic circuit inside the power management unit 50.

[0203] On the other hand, during the period when the ignition switch 11 is off, the power management unit 50 stops supplying the first sensor power supply Vs1 and power supply Vm to the first sensor 33 and MPU 60, etc., and intermittently supplies the second sensor power supply Vs2 to the second sensor 34.

[0204] For example, the voltage of the second sensor power supply Vs2, which is intermittently supplied during the period when the ignition switch 11 is off, can be a power supply voltage Vcc2 that is lower than the power supply voltage Vcc1. For example, the power supply voltage Vcc2 can be 3.3 [V].

[0205] Reference Figure 6 (a) and Figure 6(b) As described above, the threshold voltage Vr is set to half the voltage of the second sensor power supply Vs2 (i.e., Vs2 / 2). Therefore, for example, when the ignition switch 11 is on and the second sensor power supply Vs2 is 5 [V], the threshold voltage Vr can be set to 2.5 [V], and when the ignition switch 11 is off and the second sensor power supply Vs2 is 3.3 [V], the threshold voltage Vr can be set to 1.65 [V].

[0206] Figure 14 This is a block diagram illustrating an example of the functional structure of the power management unit 50 according to the second embodiment. Structural elements identical to those in the power management unit 50 of the first embodiment are labeled with the same reference numerals. The power management unit 50 of the second embodiment includes an internal power generation unit 55 and a sensor power determination unit 57.

[0207] The third power supply unit 54 is an example of a "sensor power supply unit". The first power supply unit 52, the second power supply unit 53, and the internal power generation unit 55 are examples of "power supply units" described in the technical solution.

[0208] The power control unit 56 generates an operation switching signal Sig based on the ignition switch signal IG, and outputs it to the regulator 51, the first power supply unit 52, the second power supply unit 53, and the third power supply unit 54.

[0209] The action switching signal Sig has different values ​​depending on whether the ignition switch 11 is on or off.

[0210] That is, the action switching signal Sig indicates whether the ignition switch 11 is on or off. For example, the value indicating that the ignition switch 11 is on can be "1", and the value indicating that the ignition switch 11 is off can be "0".

[0211] Furthermore, the power control unit 56 generates a drive interval indication signal Si and outputs it to the third power supply unit 54. The drive interval indication signal Si is a signal indicating the interval during which power is intermittently supplied to the second sensor (i.e., the drive interval for driving the second sensor 34) while the ignition switch 11 is off. Details of the power control unit 56 will be described later.

[0212] The regulator 51 generates a regulator power supply VR with a specified voltage from the battery power supply Vbat. The first power supply unit 52, the second power supply unit 53, the third power supply unit 54, and the internal power generation unit 55 generate power supply Vm, first sensor power supply Vs1, second sensor power supply Vs2, and internal power supply Vp from the regulator power supply VR, respectively.

[0213] The regulator 51 switches the voltage of the regulator power supply VR according to the action switching signal Sig. For example, the voltage of the regulator power supply VR can be 6 [V] during the period when the value of the action switching signal Sig is "1" (i.e., the period when the ignition switch 11 is on), and the voltage of the regulator power supply VR can be 4 [V] during the period when the value of the action switching signal Sig is "0" (i.e., the period when the ignition switch 11 is off).

[0214] The first power supply unit 52 continuously supplies power Vm to the MPU 60 and the like during the period when the value of the operation switching signal Sig is "1".

[0215] Furthermore, during the period when the value of the action switching signal Sig is "1", the second power supply unit 53 continuously supplies the first sensor power supply Vs1 to the first sensor 33, and the third power supply unit 54 continuously supplies the second sensor power supply Vs2 to the second sensor 34.

[0216] As a result, during the period when the ignition switch 11 is turned on, the MPU 60, the first sensor 33, and the second sensor 34 operate continuously. Furthermore, the voltages of the first sensor power supply Vs1 and the second sensor power supply Vs2 at this time are the power supply voltage Vcc1.

[0217] On the other hand, during the period when the value of the operation switching signal Sig is "0" (i.e., during the period when the ignition switch 11 is off), the first power supply unit 52 and the second power supply unit 53 stop generating power supply Vm and the first sensor power supply Vs1. As a result, the supply of the first sensor power supply Vs1 to the first sensor 33 and the supply of power supply Vm to the MPU 60, etc., stop, and the operation of the first sensor 33 and the MPU 60, etc., stops.

[0218] During the period when the operation switching signal Sig is "0", the third power supply unit 54 generates a second sensor power supply Vs2, which is lower than the power supply voltage Vcc2. Furthermore, during the period when the operation switching signal Sig is "0", the third power supply unit 54 intermittently generates the second sensor power supply Vs2 according to the drive interval indicated by the drive interval indication signal Si.

[0219] As a result, the power supply Vs2 of the second sensor, which is lower than the power supply voltage Vcc2 of Vcc1, is intermittently supplied to the second sensor 34, and the second sensor 34 operates intermittently.

[0220] Regardless of whether the value of the action switching signal Sig is "1" or "0" (regardless of whether the ignition switch 11 is on or off), the internal power generation unit 55 provides internal power Vp to the rotation count detection unit 58.

[0221] During the period when the ignition switch 11 is off (i.e., during the period when the second sensor power supply Vs2 is intermittently generated), the sensor power supply determination unit 57 determines whether the second sensor power supply Vs2 is supplied to the second sensor 34. The sensor power supply determination unit 57 generates a start signal Sr for timing the operation of the rotation count detection unit 58 when the second sensor power supply Vs2 is supplied to the second sensor 34. The value of the start signal Sr is, for example, intermittently "1" during the period when the second sensor power supply Vs2 is supplied, and "0" during the period when the second sensor power supply Vs2 is not supplied.

[0222] The rotation count detection unit 58 operates continuously while the ignition switch 11 is on, and operates intermittently when the ignition switch 11 is off, provided that the value of the start signal Sr from the sensor power determination unit 57 is "1" (i.e., when the second sensor power supply Vs2 is supplied to the second sensor 34).

[0223] The first comparator 58a and the second comparator 58b of the rotation count detection unit 58 operate intermittently during the period when the ignition switch 11 is off, changing the sign signals Cs and Cc based on the comparison results of the second sine signal sin2 and the second cosine signal cos2 with the threshold voltage Vr. During the period when the second sensor power supply Vs2 is not supplied to the second sensor 34, the output of the sign signals Cs and Cc is maintained by the internal power supply Vp. The sine counter 58c and the cosine counter 58d operate powered by the internal power supply Vp and calculate the sine count value CNTs and the cosine count value CNTc, respectively.

[0224] Next, the power control unit 56 will be further described. As described above, the power control unit 56 controls the regulator 51, the first power supply unit 52, the second power supply unit 53, and the third power supply unit 54 by generating an operation switching signal Sig and a drive interval indication signal Si. The power control unit 56 includes an operation switching unit 56a and a drive interval changing unit 56b.

[0225] The action switching unit 56a generates the action switching signal Sig based on the ignition switch signal IG.

[0226] The drive interval change unit 56b generates a drive interval indication signal Si based on whether rotation of the motor rotating shaft 21 is detected. As described above, the drive interval indication signal Si indicates the drive interval at which the second sensor 34 is intermittently driven.

[0227] The drive interval change unit 56b adjusts the drive interval indicated by the drive interval indicator signal Si according to whether the rotation of the motor rotating shaft 21 is detected.

[0228] Specifically, when rotation of the motor shaft 21 is detected, the drive interval changing unit 56b shortens the drive interval indicated by the drive interval indication signal Si from the predetermined maximum interval x, and then extends the drive interval to the maximum interval x when rotation of the motor shaft 21 is no longer detected. The maximum interval x is an example of the "first time interval".

[0229] In this way, by shortening the drive interval of the second sensor 34 when the rotation of the motor shaft 21 is detected, it is possible to prevent the omission of the sine count value CNTs and the cosine count value CNTc.

[0230] For example, the drive interval changing unit 56b can generate a drive interval indication signal Si based on whether changes in the second sine signal sin2 and the second cosine signal cos2 are detected.

[0231] Specifically, the drive interval changing unit 56b generates a drive interval indication signal Si based on the changes in the sign signal Cs of the second sine signal sin2, which is the output of the first comparator 58a, and the sign signal Cc of the second cosine signal cos2, which is the output of the second comparator 58b.

[0232] That is, when the symbol signals Cs and Cc change, the drive interval changing unit 56b shortens the drive interval indicated by the drive interval indication signal Si from the maximum interval x.

[0233] Subsequently, when the symbol signals Cs and Cc no longer change, the drive interval changing unit 56b extends the drive interval indicated by the drive interval indication signal Si to the maximum interval x.

[0234] For example, even if power is intermittently supplied to the second sensor 34 at a predetermined number of times and no change in either of the symbol signals Cs and Cc is detected, the drive interval change unit 56b may begin to extend the drive interval.

[0235] The drive interval change unit 56b can also detect changes in the signal of one of the symbol signals Cs and Cc, and then, when a change in the signal of the other of the symbol signals Cs and Cc is detected, it will periodically shorten the drive interval indicated by the drive interval indication signal Si.

[0236] For example, when a change in one of the symbol signals Cs and Cc is detected, the drive interval changing unit 56b shortens the drive interval by a predetermined length T1, and then further shortens the drive time by a predetermined length T1 when a change in the other signal is detected. That is, the shortening amount changes in stages such as T1, (2×T1).

[0237] By periodically shortening the drive interval in this way, the increase in power consumption caused by the shortening of the drive interval can be suppressed, and the omission of the sine count value CNTs and the cosine count value CNTc can be prevented.

[0238] Reference Figure 15 (a)~ Figure 15 (c) describes an example of the control of the drive interval of the second sensor 34, which detects the rotation of the motor shaft 21 during the period when the ignition switch 11 is off. Figure 15 (a) shows an example where the specified length T1 is 2.2 [milliseconds].

[0239] The initial driving interval is the maximum interval x, which is shortened to (x-2.2) [milliseconds] when the symbol signal Cs changes from "0" to "1" as shown in reference symbol 100.

[0240] Subsequently, when the symbol signal Cc changes from “0” to “1” as shown by reference symbol 101, it shortens from (x-2.2) [milliseconds] to (x-4.4) [milliseconds].

[0241] For example, when the maximum interval x is set to 6.6 [milliseconds], the drive interval indicated by the drive interval indicator signal Si is shortened in stages from 6.6 [milliseconds] to 4.4 [milliseconds] and 2.2 [milliseconds].

[0242] When the drive interval indicated by the drive interval indication signal Si is shortened to the specified minimum interval, even if changes in the symbol signals Cs and Cc are detected, the drive interval changing unit 56b prohibits shortening the drive interval to a value shorter than the minimum interval. For example, in Figure 15 In example (a), the minimum interval can be (x-4.4) [milliseconds]. Figure 15 In example (a), if the maximum interval x is 6.6 [milliseconds], then the minimum interval is 2.2 [milliseconds].

[0243] Furthermore, the time width w during which the second sensor 34 is supplied with power Vs2 (i.e., the period during which the second sensor 34 is driven) can be fixed. The time width w can be, for example, 220 [μ seconds].

[0244] With a fixed time width w, the duty cycle of the second sensor 34 during the driving period when the driving interval is the maximum interval of 6.6 [ms] is 1 / 3 compared to when it is the minimum interval of 2.2 [ms].

[0245] Furthermore, the duty cycle is 10% when the time width w is 220 [μ seconds] and the drive interval is the minimum interval of 2.2 [milliseconds].

[0246] Furthermore, after one of the symbol signals Cs and Cc changes, before the other of the symbol signals Cs and Cc changes, sometimes one of the symbol signals Cs and Cc changes again.

[0247] exist Figure 15 (b) and Figure 15 In example (c), after the symbol signal Cs changes from “0” to “1” as shown by reference symbol 100, sometimes the symbol signal Cc does not change from “0” to “1”, but the symbol signal Cs returns to “0” from “1” again.

[0248] Such a phenomenon occurs, for example, when the motor shaft 21 rotates and the signal of one of the symbol signals Cs and Cc changes, and the motor shaft 21 does not rotate more than 90 degrees in the same direction of rotation but rotates in the opposite direction.

[0249] In this case, since the motor shaft 21 does not rotate rapidly, the possibility of missing the sine count CNTs and cosine count CNTc is relatively small, even without significantly shortening the drive interval.

[0250] Therefore, the drive interval changing unit 56b can also be configured such that, after one of the symbol signals Cs and Cc changes, and before the other of the symbol signals Cs and Cc changes, even if one of the symbol signals Cs and Cc changes again, the drive interval indicated by the drive interval indication signal Si will not be shortened.

[0251] For example, when a change in the symbol signal Cs is detected, the drive interval change unit 56b stores the history of the symbol signal Cs change, indicating that the symbol signal Cs has changed.

[0252] When the history of symbol signal Cs changes is stored, the drive interval changing unit 56b does not periodically shorten the drive interval even if a change in symbol signal Cs is detected. Conversely, when the history of symbol signal Cs changes is not stored, the drive interval changing unit 56b shortens the drive interval and stores the history of symbol signal Cs changes when a change in symbol signal Cs is detected.

[0253] Furthermore, when a change in symbol signal Cs is detected while the history of symbol signal Cs is stored, the drive interval changing unit 56b shortens the drive interval and stores the history of symbol signal Cs changes. At this time, the drive interval changing unit 56b resets the history of changes to a state where no change in symbol signal Cs is stored.

[0254] Even if a change in the symbol signal Cc is detected, the drive interval change unit 56b does not periodically shorten the drive interval when the history of changes in the symbol signal Cc is stored.

[0255] Conversely, when a change in symbol signal Cc is detected without storing the history of its changes, the drive interval change unit 56b shortens the drive interval and stores the history of the changes in symbol signal Cc.

[0256] When a change in symbol signal Cc is detected while the history of symbol signal Cc changes, the drive interval changing unit 56b shortens the drive interval and stores the history of symbol signal Cs changes. Then, the history of changes is reset to a state where no change in symbol signal Cc is stored.

[0257] The change history of symbol signals Cs and Cc can be stored, for example, in the case where the drive interval change unit 56b is implemented in hardware by logic circuits, etc., by flip-flop circuits, etc.

[0258] When the drive interval change unit 56b is implemented in software, the change history of symbol signals Cs and Cc can also be stored through flag variables, etc.

[0259] Next, the operation of the drive interval change unit 56b will be explained when the rotation of the motor shaft 21 is not detected during the period when the ignition switch 11 is off.

[0260] As described above, after the drive interval indicated by the drive interval indication signal Si is shortened, the drive interval change unit 56b extends the drive interval indicated by the drive interval indication signal Si to the maximum interval x when the symbol signals Cs and Cc no longer change.

[0261] Specifically, if no change in either of the symbol signals Cs and Cc is detected even when power is intermittently supplied to the second sensor 34 multiple times as specified, the drive interval indicated by the drive interval indication signal Si is extended to the maximum interval x.

[0262] Therefore, the drive interval change unit 56b counts the number of times power is intermittently supplied to the second sensor 34, starting from the last detected change in either the symbol signal Cs or Cc.

[0263] That is, each time power is intermittently supplied to the second sensor 34, the drive interval change unit 56b increases the power supply count CNTr by 1, and when a change in the signal of either the symbol signal Cs or Cc is detected, the power supply count CNTr is reset to 0.

[0264] The drive interval change unit 56b determines whether the power supply count CNTr is above or above a predetermined count threshold Cth. If the power supply count CNTr is above or above the predetermined count threshold Cth, the drive interval change unit 56b extends the drive interval indicated by the drive interval indication signal Si by a predetermined length T2 whenever the power supply count CNTr increases by 1. The predetermined length T2 may be shorter than the predetermined length T1, or it may be the same as the predetermined length T1.

[0265] Furthermore, at this time, the drive interval change unit 56b resets the change history to the state of changes in unstored symbol signals Cs and Cc.

[0266] The drive interval change unit 56b continuously extends the drive interval until the drive interval reaches the maximum interval x. When the drive interval reaches the maximum interval x, the extension of the drive interval stops.

[0267] Reference Figure 16 (a)~ Figure 16 (d) will be described as an example of controlling the drive interval of the second sensor 34 in the case where rotation of the motor shaft 21 is not detected during the period when the ignition switch 11 is off. Figure 16 (a)~ Figure 16 In example (d), the counting threshold Cth is 4, and the specified length T2 is 1.1 [milliseconds].

[0268] Now, as Figure 16 As shown in (a), imagine the case where the drive interval indicated by the initial drive interval indication signal Si is shortened to (x-4.4) [milliseconds].

[0269] When the symbol signal Cs changes as shown by reference symbol 102, the drive interval changing unit 56b resets the power supply count CNTr to 0. Then, when no change in either the symbol signal Cs or Cc is detected, the drive interval changing unit 56b increments the power supply count CNTr one by one as power is intermittently supplied to the second sensor 34.

[0270] The drive interval change unit 56b determines whether the power supply count CNTr is above the count threshold Cth, which is 4 or higher.

[0271] When the power supply count CNTr reaches 4, the drive interval change unit 56b extends the drive interval indicated by the drive interval indication signal Si by a predetermined length T2, i.e., 1.1 [milliseconds]. As a result, the drive interval is extended from (x-4.4) [milliseconds] to (x-3.3) [milliseconds].

[0272] Subsequently, whenever the power supply count CNTr increases by 1, the drive interval change unit 56b extends the drive interval by 1.1 milliseconds.

[0273] Subsequently, when the drive interval indicated by the drive interval indication signal Si extends to the maximum interval x, the drive interval change unit 56b stops extending the drive interval.

[0274] Furthermore, the numerical examples of the specified lengths T1 and T2, the maximum and minimum driving intervals x, and the counting threshold Cth described above are merely illustrative, and the present invention is not limited to the numerical examples described above. The values ​​of the specified length T1, the maximum interval x, and the minimum interval can be appropriately set according to the actual device structure.

[0275] Furthermore, when a change in the symbol signal Cs or Cc is detected, if shortening the drive interval by a predetermined length T1 would make the drive interval shorter than the minimum interval, the drive interval changing unit 56b can shorten the drive interval by a amount shorter than the predetermined length T1. Similarly, if no change in the symbol signal Cs or Cc is detected, if extending the drive interval by a predetermined length T2 would make the drive interval longer than the maximum interval x, the extension of the drive interval can be shorter than the predetermined length T2.

[0276] For example, if the length T1 is specified as 2.2 milliseconds and the minimum interval is (x-4.4) milliseconds as described above, imagine a situation where a change in the symbol signal Cs or Cc is detected at a timing of (x-3.3) milliseconds during the extension of the drive interval.

[0277] At this time, if the drive interval is shortened by a specified length T1, the drive interval becomes (x-5.5) [milliseconds], which is shorter than the minimum interval (x-4.4) [milliseconds]. Therefore, the drive interval changing unit 56b shortens the drive interval by 1.1 [milliseconds], which is shorter than the specified length T1 = 2.2 [milliseconds], thereby setting the drive interval to the minimum interval (x-4.4) [milliseconds].

[0278] Reference Figure 17 An example of a method for setting the drive interval indicated by the drive interval indication signal Si will be described.

[0279] In step S1, the sensor power supply determination unit 57 determines whether an increase in the voltage of the second sensor power supply Vs2 is detected. If an increase in the voltage of the second sensor power supply Vs2 is detected (step S1: Yes), the process proceeds to step S2. If no increase in the voltage of the second sensor power supply Vs2 is detected (step S1: No), the process ends. In this case, the drive interval does not change.

[0280] In step S2, the sensor power supply determination unit 57 generates a start signal Sr and outputs it to the rotation count detection unit 58. In the rotation count detection unit 58, which is started by the start signal Sr, the first comparator 58a and the second comparator 58b output the sign signal Cs of the second sine signal sin2 and the sign signal Cc of the second cosine signal cos2.

[0281] The drive interval change unit 56b performs rotation detection processing and determines whether rotation of the motor rotating shaft 21 is detected based on the symbol signals Cs and Cc.

[0282] Reference Figure 18 An example of the rotation detection process in step S2 will be explained.

[0283] In step S20, the drive interval change unit 56b determines whether the symbol signal Cs has changed. If the symbol signal Cs has changed (step S20: Yes), the process proceeds to step S21. If the symbol signal Cs has not changed (step S20: No), the process proceeds to step S25.

[0284] In step S21, the drive interval change unit 56b determines whether there is a change history of the symbol signal Cs indicating that the symbol signal Cs has changed. If there is a change history (step S21: Yes), the process proceeds to step S24. If there is no change history (step S21: No), the process proceeds to step S22.

[0285] In step S22, the drive interval change unit 56b stores the change history of the symbol signal Cs, indicating that the symbol signal Cs has changed. Furthermore, it resets the change history indicating that the symbol signal Cc has changed to a state where no change in the symbol signal Cc is stored.

[0286] In step S23, the drive interval change unit 56b determines that the rotation of the motor rotating shaft 21 has been detected and ends the rotation detection process.

[0287] On the other hand, if it is determined in step S21 that there is no change history (step S21: no), the drive interval change unit 56b determines in step S24 that no rotation of the motor rotating shaft 21 has been detected and ends the rotation detection process.

[0288] If the symbol signal Cs does not change in step S20 (step S20: No), the drive interval change unit 56b determines in step S25 whether the symbol signal Cc has changed.

[0289] If the symbol signal Cc changes (step S25: Yes), the process proceeds to step S26. If the symbol signal Cc does not change (step S25: No), the process proceeds to step S24. In this case, the drive interval change unit 56b determines that no rotation of the motor rotating shaft 21 has been detected and ends the rotation detection process.

[0290] In step S26, the drive interval change unit 56b determines whether there is a history of symbol signal Cs changes indicating that symbol signal Cc has changed.

[0291] If there is a history of changes (step S26: Yes), the process proceeds to step S24. In this case, the drive interval change unit 56b determines that no rotation of the motor shaft 21 has been detected and ends the rotation detection process.

[0292] If there is no change history of the symbol signal Cs (step S26: No), proceed to step S27.

[0293] In step S27, the drive interval change unit 56b stores the change history of the symbol signal Cc, indicating that the symbol signal Cc has changed. Furthermore, it resets the change history indicating that the symbol signal Cs has changed to a state where no change in the symbol signal Cs is stored.

[0294] In step S28, the drive interval change unit 56b determines that the rotation of the motor rotating shaft 21 has been detected and ends the rotation detection process.

[0295] Reference Figure 17 If rotation of the motor shaft 21 is detected (step S3: Yes), the process proceeds to step S4. If rotation of the motor shaft 21 is not detected (step S3: No), the process proceeds to step S7.

[0296] In step S4, the drive interval change unit 56b resets the power supply count CNTr, which counts the number of times power is intermittently supplied to the second sensor 34.

[0297] In step S5, the drive interval change unit 56b determines whether the drive interval indicated by the drive interval indication signal Si is already the minimum interval. If the drive interval is the minimum interval (step S5: Yes), the process ends. In this case, the drive interval does not change.

[0298] If the drive interval is not the minimum interval (step S5: No), proceed to step S6.

[0299] In step S6, the drive interval changing unit 56b shortens the drive interval indicated by the drive interval indication signal Si. Afterwards, the process ends.

[0300] If no rotation of the motor shaft 21 is detected in step S3 (step S3: No), the drive interval change unit 56b determines in step S7 whether the drive interval indicated by the drive interval indication signal Si is the maximum interval x. If the drive interval is the maximum interval x (step S7: Yes), the process ends. In this case, the drive interval does not change.

[0301] If the drive interval is not the maximum interval x (step S7: No), proceed to step S8.

[0302] In step S8, the drive interval change unit 56b determines whether the power supply count CNTr is above the count threshold Cth.

[0303] If the power supply count CNTr is above the count threshold Cth (step S8: Yes), proceed to step S10. If the power supply count CNTr is not above the count threshold Cth (step S8: N), proceed to step S9. In this case, the drive interval does not change.

[0304] In step S9, the drive interval change unit 56b increments the power supply count CNTr by 1. Afterward, the process ends.

[0305] When the power supply count CNTr is above the count threshold Cth in step S8 (step S8: Yes), the drive interval change unit 56b extends the drive interval indicated by the drive interval indication signal Si in step S10.

[0306] In step S11, the drive interval change unit 56b resets the change history to the state where the changes of unstored symbol signals Cs and Cc are not recorded. After that, the process ends after step S9.

[0307] (Effects of the second implementation method)

[0308] (1) The second sensor 34 outputs a second sensor signal containing a sine signal and a cosine signal corresponding to the rotation of the motor rotation shaft 21 of the motor 20. The third power supply unit 54 supplies the second sensor power Vs2 to the second sensor 34. The power control unit 56 controls the third power supply unit 54 so that the second sensor power Vs2 is continuously supplied to the second sensor 34 when the ignition switch 11 is on, and intermittently supplied to the second sensor 34 when the ignition switch 11 is off. The first comparator 58a and the second comparator 58b detect changes in the sine signal and changes in the cosine signal.

[0309] The power control unit 56 intermittently supplies power Vs2 to the second sensor 34 to drive the second sensor 34. The driving interval of the second sensor 34 is set as a first time interval when no change in either the sine or cosine signal is detected, a second time interval shorter than the first time interval when only the signal of either the sine or cosine signal is detected, and a third time interval shorter than the second time interval when a change in the signal of either the sine or cosine signal is detected and then a change in the signal of the other is detected.

[0310] In this way, since the second sensor 34 is driven intermittently when the ignition switch 11 is off, the power consumption during the period when the ignition switch 11, which is a power switch, is off can be reduced.

[0311] Furthermore, since the drive interval of the second sensor 34 is shortened based on the change in the output signal of the second sensor 34, it is possible to prevent the detection of the rotation of the motor rotating shaft 21 from being missed.

[0312] Furthermore, since the drive interval is shortened in stages based on the change in the output signal of the second sensor 34, the increase in power consumption can be suppressed, and the detection of the rotation of the motor shaft 21 can be prevented from being missed.

[0313] (2) If, during a period when the drive interval is set to be shorter than the first time interval, even if the second sensor power supply Vs2 is provided intermittently more than a specified number of times, and no change in either the sine or cosine signal is detected, the power supply control unit 56 may extend the drive interval to the first time interval in stages.

[0314] In this way, by extending the drive interval when neither sine nor cosine signals are detected, power consumption can be reduced.

[0315] Furthermore, by extending the drive interval in stages, the increase in power consumption can be suppressed, and the detection of the rotation of the motor shaft 21 can be prevented from being missed.

[0316] (3) The power control unit 56 can increase the duty cycle during the period of supplying the second sensor power Vs2 to the second sensor 34 by shortening the drive interval.

[0317] For example, the duty cycle when the drive interval is the third time interval can be 10%.

[0318] Furthermore, for example, the duty cycle when the drive interval is the first time interval can also be 1 / 3 of the duty cycle when the drive interval is the third time interval.

[0319] This reduces power consumption during the period when the ignition switch 11 is off.

[0320] (4) The power control unit 56 can also reduce the voltage of the second sensor power supply Vs2 supplied to the sensor when the ignition switch 11 is off to a lower level than when the ignition switch 11 is on.

[0321] For example, the voltage of the second sensor power supply Vs2 can be 3.3V when the ignition switch 11 is off, and the voltage of the second sensor power supply Vs2 can be 5V when the ignition switch 11 is on.

[0322] This reduces power consumption during the period when the ignition switch 11 is off.

[0323] (5) The first sensor 33 outputs a first sensor signal corresponding to the rotation of the motor rotation shaft 21 of the motor 20. The angle position calculation unit 61 calculates angle position information representing the angle position of the motor rotation shaft 21 based on the first sensor signal. The rotation count detection unit 58 detects the number of rotations of the motor rotation shaft 21 based on the second sensor signal and outputs rotation count information representing the number of rotations. The rotation angle information calculation unit 66 calculates rotation angle information representing the rotation angle of the motor rotation shaft 21 based on the angle position information and the rotation count information.

[0324] The second power supply unit 53, the first power supply unit 52, and the internal power generation unit 55 supply power to the first sensor 33, the angle position calculation unit 61, the rotation count detection unit 58, and the rotation angle information calculation unit 66. The power control unit 56 can control the second power supply unit 53 and the first power supply unit 52 so that when the ignition switch 11 is on, power is supplied to the first sensor 33, the angle position calculation unit 61, and the rotation angle information calculation unit 66, and power is stopped when the ignition switch 11 is off.

[0325] Therefore, during the period when the ignition switch 11 is off, power consumption in the first sensor 33 and the angle position calculation unit 61 and rotation angle information calculation unit 66 that process the output signal of the first sensor 33 can be stopped. Thus, power consumption during the period when the power switch is off can be reduced.

[0326] (Third Implementation)

[0327] Next, the power management unit 50 of the third embodiment will be described. Similar to the second embodiment, the power management unit 50 supplies power Vm to the MPU 60 and the like during the period when the ignition switch 11 is turned on.

[0328] Furthermore, the power management unit 50 provides first sensor power Vs1 and second sensor power Vs2 to the first sensor 33 and the second sensor 34, respectively. During the period when the ignition switch 11 is on, the power management unit 50 provides continuous power as first sensor power Vs1 and second sensor power Vs2. The voltages of first sensor power Vs1 and second sensor power Vs2 during the period when the ignition switch 11 is on can, for example, be the same power supply voltage Vcc1 (e.g., Vcc1 = 5V).

[0329] Furthermore, during the period when the ignition switch 11 is turned on, the power management unit 50 provides an internal power supply Vp as continuous power to the digital logic circuits inside the power management unit 50. For example, the voltage of the internal power supply Vp during the period when the ignition switch 11 is turned on can be the same power supply voltage Vcc1. That is, the voltage of the internal power supply Vp can be the same as the voltage of the second sensor power supply Vs2.

[0330] The continuous power supplied as the second sensor power supply Vs2 and the internal power supply Vp during the period when the ignition switch 11 is turned on is an example of "first power".

[0331] On the other hand, during the period when the ignition switch 11 is off, the power management unit 50 stops supplying the first sensor power Vs1 to the first sensor 33 and the power Vm to the MPU 60, etc.

[0332] Furthermore, during the period when the ignition switch 11 is off, the power management unit 50 provides intermittent power to the second sensor 34 as the second sensor power supply Vs2.

[0333] For example, the voltage of the second sensor power supply Vs2, which is intermittently supplied during the period when the ignition switch 11 is off, can be a power supply voltage Vcc2 that is lower than the power supply voltage Vcc1. For example, the power supply voltage Vcc2 can be 3.3 [V].

[0334] The intermittent power supplied as the power source Vs2 for the second sensor during the period when the ignition switch 11 is off is an example of "second power".

[0335] Figure 19 (a) shows an example waveform of the second sensor power supply Vs2 that is intermittently output during the period when the ignition switch 11 is off.

[0336] When the ignition switch 11 is off, the voltage of the second sensor power supply Vs2 is the power supply voltage Vcc2 during the intermittent output period with a time width Wt corresponding to the arrival of the output cycle T, and is "0" during periods other than the intermittent output period. Similar to the second embodiment, the power management unit 50 can dynamically change the output cycle T. The output cycle T can be, for example, 2.2 milliseconds to 6.6 milliseconds.

[0337] Figure 19 (b) is a graph showing the waveform of a single intermittent output of the second sensor power supply Vs2. The time width Wt during the intermittent output of the second sensor power supply Vs2 is the sum of the standby period Pw, the idle period Pi, and the sampling period Ps.

[0338] The standby period Pw is a period during which sampling of the second sensor signal is prohibited to prevent voltage fluctuations that occur after the intermittent output of the second sensor power supply Vs2 has just begun. The standby period Pw can be a fixed value or any value that can be programmed in the power management unit 50.

[0339] The lengths of the idle period Pi and the sampling period Ps are arbitrary values ​​that can be programmed in the power management unit 50. The sampling period Ps is specified as the period during which the power management unit 50 samples the second sensor signal of the second sensor 34 when the ignition switch 11 is off.

[0340] The duration of the idle period Pi can be programmed to be the start period of the specified sampling period Ps, and the duration of the sampling period Ps can be programmed to be the end period of the specified intermittent output of the second sensor power supply Vs2.

[0341] The duration Wt of the intermittent output of the second sensor power supply Vs2 affects the dark current flowing through the sensor unit 30 and the controller 40 during the period when the ignition switch 11 is off. That is, it affects the power consumption of the sensor unit 30 and the controller 40 during the period when the ignition switch 11 is off. A longer duration Wt results in a larger dark current and greater power consumption, while a shorter duration Wt conserves dark current and power.

[0342] On the other hand, when the idle period Pi and the sampling period Ps are shortened, it is difficult to sample the second sensor signal output from the intermittently driven second sensor 34 with high accuracy.

[0343] For example, when the supply of power Vs2 to the second sensor begins, the voltage of the second sensor signal received by the controller 40 from the second sensor 34 changes from "0" to a value corresponding to the magnetic flux applied to the second sensor 34 with a certain time constant. The time constant of the second sensor signal is determined, for example, by the electrical characteristics of the second sensor 34 itself, the wiring harness 35, the impedance of the input circuit, etc. Therefore, when Pi is too small during the idle period, it is possible to sample a signal smaller than the original second sensor signal.

[0344] Therefore, the duration Wt of the intermittent output of the second sensor power supply Vs2 is preferably set according to the allowable current consumption (dark current) of the sensor unit 30 and the controller 40 during the period when the ignition switch 11 is off. For example, the duration Wt of the intermittent output of the second sensor power supply Vs2 can be less than 220 microseconds.

[0345] Furthermore, the time width Wt of the intermittent output of the second sensor power supply Vs2 is preferably set according to the time constant of the second sensor signal when the intermittent supply of the second sensor power supply Vs2 begins during the period when the ignition switch 11 is off.

[0346] For example, it is realistic to design the system so that the second sensor signal sufficiently increases 100 microseconds after the start of the output of the second sensor power supply Vs2 (e.g., to rise to about 99% of the size of the second sensor signal in the case of continuously supplied second sensor power supply Vs2). Therefore, the time width Wt of one intermittent output of the second sensor power supply Vs2 can be, for example, more than 100 microseconds.

[0347] While the ignition switch 11 is off, the power management unit 50 also provides continuous power as the internal power supply Vp. That is, the power management unit 50 provides continuous power as the internal power supply Vp regardless of whether the ignition switch 11 is on or off.

[0348] However, during the period when the ignition switch 11 is off, the power management unit 50 provides an internal power supply Vp with a voltage lower than that during the period when the ignition switch 11 is on.

[0349] For example, the voltage of the internal power supply Vp during the period when the ignition switch 11 is off can also be equal to the voltage of the second sensor power supply Vs2, i.e., the power supply voltage Vcc2, during the period when the ignition switch 11 is off.

[0350] The continuous power supplied as internal power source Vp during the period when ignition switch 11 is off is an example of "third power".

[0351] Next, refer to Figure 20 An example of the functional structure of the power management unit 50 will be described. Structural elements that are the same as those in the power management unit 50 of the first embodiment will be labeled with the same reference numerals.

[0352] The power control unit 56 generates an operation switching signal Sig based on the ignition switch signal IG, and outputs it to the regulator 51, the first power supply unit 52, the second power supply unit 53, and the third power supply unit 54.

[0353] Furthermore, the power control unit 56 outputs a timing signal St with a period T indicating the start of the intermittent output period of the second sensor power supply Vs2 during the period when the ignition switch 11 is off to the third power supply unit 54 and the rotation count detection unit 58.

[0354] Regulator 51 generates a regulator power supply VR with a specified voltage from the battery power supply Vbat. First power supply unit 52 and second power supply unit 53 generate power supply Vm and first sensor power supply Vs1 from the regulator power supply VR. Furthermore, third power supply unit 54 generates second sensor power supply Vs2 and internal power supply Vp from the regulator power supply VR.

[0355] The regulator 51 switches the voltage of the regulator power supply VR according to the action switching signal Sig.

[0356] For example, the voltage of the regulator power supply VR during the period when the value of the action switching signal Sig is "0" (i.e., the period when the ignition switch 11 is off) can be lower than the voltage of the regulator power supply VR during the period when the value of the action switching signal Sig is "1" (i.e., the period when the ignition switch 11 is on). Therefore, the voltages of the second sensor power supply Vs2 and the internal power supply Vp during the period when the ignition switch 11 is off can be lower than the voltages during the period when the ignition switch 11 is on.

[0357] For example, the voltage of the regulator power supply VR can be 6 [V] during the period when the value of the action switching signal Sig is "1", and the voltage of the regulator power supply VR can be 4 [V] during the period when the value of the action switching signal Sig is "0".

[0358] The first power supply unit 52 provides continuous power to the MPU 60 and the like as power supply Vm during the period when the value of the operation switching signal Sig is "1", and the second power supply unit 53 provides continuous power to the first sensor 33 as the first sensor power supply Vs1.

[0359] Furthermore, during the period when the value of the action switching signal Sig is "1", the third power supply unit 54 provides continuous power to the second sensor 34 and the rotation count detection unit 58 as the second sensor power supply Vs2, and provides continuous power to the rotation count detection unit 58 as the internal power supply Vp.

[0360] As a result, during the period when the ignition switch 11 is turned on, the MPU 60, the first sensor 33, and the second sensor 34 operate continuously. Furthermore, at this time, the voltages of the first sensor power supply Vs1, the second sensor power supply Vs2, and the internal power supply Vp are the power supply voltage Vcc1.

[0361] On the other hand, during the period when the value of the operation switching signal Sig is "0" (i.e., during the period when the ignition switch 11 is off), the first power supply unit 52 and the second power supply unit 53 stop generating power supply Vm and the first sensor power supply Vs1. As a result, the supply of the first sensor power supply Vs1 to the first sensor 33 and the supply of power supply Vm to the MPU 60, etc., stop, and the operation of the first sensor 33 and the MPU 60, etc., stops.

[0362] The third power supply unit 54 outputs intermittent power with power supply voltage Vcc2 as the power supply Vs2 for the second sensor during the period when the value of the operation switching signal Sig is “0”.

[0363] As a result, the power supply Vs2 of the second sensor, which is lower than the power supply voltage Vcc2 of Vcc1, is intermittently supplied to the second sensor 34, and the second sensor 34 operates intermittently.

[0364] The third power supply unit 54 outputs the second sensor power supply Vs2 intermittently based on the timing signal St output from the power control unit 56. Furthermore, the third power supply unit 54 sets the time width Wt of one intermittent output of the second sensor power supply Vs2 according to the standby period Pw and the idle period Pi and sampling period Ps pre-programmed in the power management unit 50.

[0365] Furthermore, the third power supply unit 54 generates continuous power with power supply voltage Vcc2 as internal power supply Vp during the period when the value of the operation switching signal Sig is "0". For example, the third power supply unit 54 may also generate continuous common power with power supply voltage Vcc2 from the regulator power supply VR, and output the common power directly as internal power supply Vp. On the other hand, it switches the common power to generate the second sensor power supply Vs2.

[0366] During the period when the ignition switch 11 is on, the rotation count detection unit 58 generates rotation count information with a predetermined sampling period shorter than the intermittent output period T of the second sensor power supply Vs2. During the period when the ignition switch 11 is off, while the second sensor power supply Vs2 is supplied to the second sensor 34 with an intermittent output period T, the rotation count detection unit 58 intermittently generates rotation count information.

[0367] The first comparator 58a operates using the second sensor power supply Vs2 as its power source, compares the second sinusoidal signal sin2 with the threshold voltage Vr, and generates a sign signal Cs representing the sign of the second sinusoidal signal sin2. The sign signal Cs has a logic value of "1" when the second sinusoidal signal sin2 is above the threshold voltage Vr, and a logic value of "0" when the second sinusoidal signal sin2 is less than the threshold voltage Vr.

[0368] The threshold voltage Vr can be set based on the voltage of the second sensor power supply Vs2. For example, the rotation count detection unit 58 may also have a voltage divider resistor that divides the voltage of the second sensor power supply Vs2 or the regulator power supply VR to generate the threshold voltage Vr.

[0369] For example, when the ignition switch 11 is on and the power supply of the second sensor Vs2 is 5 [V], the threshold voltage Vr is set to 2.5 [V], and when the ignition switch 11 is off and the power supply of the second sensor Vs2 is 3.3 [V], the threshold voltage Vr is set to 1.65 [V].

[0370] The second comparator 58b operates using the second sensor power supply Vs2 as its power source, compares the second cosine signal cos2 with the threshold voltage Vr, and generates a sign signal Cc representing the sign of the second cosine signal cos2. The sign signal Cc has a logic value of "1" when the second cosine signal cos2 is above the threshold voltage Vr, and a logic value of "0" when the second cosine signal cos2 is below the threshold voltage Vr.

[0371] Furthermore, during the period when the ignition switch 11 is off, within a sampling period Ps that begins from the start period determined by the timing signal St with period T output by the power control unit 56, the standby period Pw, and the idle period Pi pre-programmed in the power management unit 50, the first comparator 58a and the second comparator 58b acquire the second sine signal sin2 and the second cosine signal cos2. Therefore, the first comparator 58a and the second comparator 58b operate intermittently during the period when the ignition switch 11 is off, changing the sign signals Cs and Cc based on the comparison result of the second sine signal sin2 and the second cosine signal cos2 with the threshold voltage Vr.

[0372] The sine counter 58c and cosine counter 58d operate using the internal power supply Vp as their power source, and calculate the sine count value CNTs and the cosine count value CNTc, respectively.

[0373] Similar to the second embodiment, the power management unit 50 can dynamically change the intermittent output period T of the second sensor power supply Vs2 during the period when the ignition switch 11 is off. For example, if the motor shaft 21 rotates during the period when the ignition switch 11 is off, and then the motor shaft 21 rotates even faster, the rotation count detection unit 58 may not be able to accurately detect the rotation of the motor shaft 21. On the other hand, during the period when the motor shaft 21 is continuously stopped, power consumption can be reduced by extending the intermittent output period T.

[0374] Therefore, for example, if the power management unit 50 detects a change in either the second sine signal sin2 or the second cosine signal cos2, it can shorten the intermittent output period T. Furthermore, if the power management unit 50 continues during the period when the second sine signal sin2 and the second cosine signal cos2 remain constant, it can extend the intermittent output period T.

[0375] Additionally, refer to Figure 19 of (a), Figure 19 (b) and Figure 20 The described power management unit 50 has the following structure: a first power supply unit 52 that supplies power Vm to the MPU 60 and the like; and a second power supply unit 53 that supplies first sensor power Vs1 to the first sensor 33. However, the present invention is not limited to this structure. As long as power Vm and first sensor power Vs1 are supplied when the ignition switch 11 is on and stopped when the ignition switch 11 is off, they can also be supplied from structural elements other than the power management unit 50.

[0376] (Effects of the third embodiment)

[0377] (1) The rotation angle detection device of the third embodiment includes: a first sensor 33, which is powered when the ignition switch 11 is turned on, outputs a first sensor signal corresponding to the rotation of the motor rotation shaft 21 of the motor 20, and the power supply is stopped when the ignition switch 11 is turned off; an angle position calculation unit 61, which is powered when the ignition switch 11 is turned on, calculates angle position information representing the angle position of the motor rotation shaft 21 based on the first sensor signal, and the power supply is stopped when the ignition switch 11 is turned off; and a second sensor 34, which outputs a sine signal and a cosine signal corresponding to the rotation of the motor rotation shaft 21. The second sensor signal of the string signal; the power management unit 50, which provides continuous first power to the second sensor 34 when the ignition switch 11 is on, and provides intermittent second power with a voltage smaller than the first power to the second sensor 34 when the ignition switch 11 is off, and outputs rotation number information indicating the number of rotations of the motor shaft based on the second sensor signal; and the rotation angle information calculation unit 66, which is powered when the ignition switch 11 is on, calculates rotation angle information indicating the rotation angle of the motor shaft 21 based on the angle position information and the rotation number information, and stops the power supply when the ignition switch 11 is off.

[0378] The power management unit 50 includes: a third power supply unit 54 that generates a first power and a second power; comparators 58a and 58b that, when the ignition switch 11 is on, operate using the first power supplied by the third power supply unit 54 as power and compare a first reference voltage based on the voltage of the first power with a second sensor signal, and when the ignition switch 11 is off, operate using the second power supplied by the third power supply unit 54 as power and compare a second reference voltage based on the voltage of the second power with a second sensor signal; and counters 58c and 58d that detect the number of rotations of the motor shaft by counting the outputs of the comparators 58a and 58b.

[0379] In this way, the second sensor 34 and comparators 58a and 58b are intermittently driven when the ignition switch 11 is off, and their power supply voltage is reduced, thus reducing the power consumption during the period when the ignition switch 11 is off.

[0380] Furthermore, by providing comparators 58a and 58b in the power management unit 50 that intermittently outputs power to the second sensor 34, which acquire the second sensor signal of the intermittently driven second sensor 34, it is easy to synchronize the operation of comparators 58a and 58b with the intermittent driving of the second sensor 34.

[0381] Furthermore, by driving comparators 58a and 58b and the second sensor 34 with the same power supply, and setting the reference voltage for comparison with the second sensor signal based on the power supply voltage of the second sensor 34, normal output of comparators 58a and 58b can be obtained even if the power supply voltage to the second sensor 34 is switched as the ignition switch 11 is turned on and off.

[0382] (2) The third power supply unit 54 can supply the first power as a power source to the counters 58c and 58d when the ignition switch 11 is turned on, and generate a continuous power, namely the third power, with a voltage equal to the second power when the ignition switch 11 is turned off, and supply it as a power source to the counters 58c and 58d.

[0383] Since the power supply voltage of counters 58c and 58d is reduced when ignition switch 11 is off, the power consumption during the period when ignition switch 11 is off can be reduced.

[0384] (3) The power management unit 50 may have a regulator 51, which generates a continuous power, i.e., a fourth power, with a first regulator voltage from an external power source when the ignition switch 11 is turned on, and generates a continuous power, i.e. a fifth power, with a second regulator voltage lower than the first regulator voltage from an external power source when the ignition switch 11 is turned off. The third power supply unit 54 generates the first power based on the fourth power, and generates the second and third power based on the fifth power.

[0385] Therefore, by switching the output voltage from the regulator 51, the output voltage of the third power supply unit 54 can be switched.

[0386] (4) Alternatively, the comparators 58a, 58b and the third power supply unit 54 can be housed in a single integrated circuit chip.

[0387] Therefore, it is easy to synchronize the operation of comparators 58a and 58b with the intermittent drive of the second sensor 34.

[0388] (5) The duration Wt of the intermittent output of the second power can also be set according to the allowable current consumption of the rotation angle detection device when the ignition switch 11 is off. As a result, the power consumption during the period when the ignition switch 11 is off can be reduced.

[0389] (6) The time width Wt of the intermittent output of the second power can also be set according to the time constant of the second sensor signal when the intermittent second power is provided. This prevents the sampling of a signal smaller than the original second sensor signal due to the time width Wt being too small.

[0390] (7) The duration of one intermittent output of the second power can be, for example, less than 220 microseconds. This reduces the power consumption during the period when the ignition switch 11 is off.

[0391] (Fourth implementation)

[0392] Next, the sensor unit 30 and controller 40 of the fourth embodiment will be described. The power management unit 50 provides intermittent power to the second sensor 34 as the second sensor power supply Vs2 during the period when the ignition switch 11 is off. However, since the sensor unit 30 is formed as a separate unit from the controller 40, when the intermittent second sensor power supply Vs2 is provided to the second sensor 34 via the wiring harness 35, sometimes an overcurrent flows immediately after the initial rise, causing the power supply voltage to become unstable, or it may become a source of electromagnetic noise. Therefore, the second sensor signal obtained from the second sensor 34 may become unstable during the period when the ignition switch 11 is off.

[0393] Therefore, in the sensor unit 30 and controller 40 of the fourth embodiment, a bypass capacitor and a decoupling capacitor are provided on the power line of the second sensor power supply Vs2. The bypass capacitor mainly functions to release higher frequency noise components to the ground, while the decoupling capacitor mainly functions to absorb lower frequency voltage fluctuations to stabilize the power supply system. However, there are also cases where the same capacitor can perform both functions.

[0394] Figure 21 This is a schematic block diagram showing an example of the circuit structure of the sensor unit 30 according to the fourth embodiment. The sensor unit 30 includes a first sensor 33, a second sensor 34, a first amplifier 36, a second amplifier 37, a first offset voltage output circuit 38, a second offset voltage output circuit 39, and voltage divider resistors Rd11, Rd12, Rd21, and Rd22.

[0395] The first sensor power supply line VL1 of the first sensor power supply Vs1 and the second sensor power supply line VL2 of the second sensor power supply Vs2 on the sensor unit 30 side are connected to the first sensor power supply line VL1 and the second sensor power supply line VL2 on the wiring harness 35 side, and the first sensor power supply Vs1 and the second sensor power supply Vs2 are respectively supplied from the controller 40. Furthermore, the first sensor ground line GND1 and the second sensor ground line GND2 on the sensor unit 30 side are connected to the ground line (not shown) on the controller 40 side via the ground line GND on the wiring harness 35 side.

[0396] The second sensor 34 has a bridge circuit 34a of magnetoresistive elements Rs21, Rs22, Rs23 and Rs24 and a bridge circuit 34b of magnetoresistive elements Rc21, Rc22, Rc23 and Rc24.

[0397] The magnetization directions of the pin layers of magnetoresistive elements Rs21, Rs22, Rs23 and Rs24 are offset by 90° from the magnetization directions of the pin layers of magnetoresistive elements Rc21, Rc22, Rc23 and Rc24.

[0398] When the second sensor power supply Vs2 is supplied between the connection point of magnetoresistive elements Rs21 and Rs22 connected to the second sensor power line VL2 via power supply terminal V2SIN and the connection point of magnetoresistive elements Rs23 and Rs24 connected to the second sensor ground line GND2 via ground terminal G2SIN, differential sine signals Ss2p and Ss2n representing the sine component corresponding to the rotation of the motor rotating shaft 21 are output from the output terminals SIN2P and SIN2N connected to the midpoint potential point.

[0399] Furthermore, when the second sensor power supply Vs2 is supplied to the connection point of magnetoresistive elements Rc21 and Rc22 connected to the second sensor power line VL2 via power supply terminal V2COS and the connection point of magnetoresistive elements Rc23 and Rc24 connected to the second sensor ground line GND2 via ground terminal G2COS, differential cosine signals Sc2p and Sc2n representing the sine component corresponding to the rotation of the motor rotating shaft 21 are output from the output terminals COS2P and COS2N connected to the midpoint potential point.

[0400] The first sensor 33 has the same structure as the second sensor 34. The power supply terminals V1SIN and V1COS correspond to the power supply terminals V2SIN and V2COS, respectively. The ground terminals G1SIN and G1COS correspond to the ground terminals G2SIN and G2COS, respectively. The output terminals SIN1N, SIN1P, COS1N and COS1P correspond to the output terminals SIN2N, SIN2P, COS2N and COS2P, respectively. The differential sine signals Ss1p and Ss1n correspond to the differential sine signals Ss2p and Ss2n, respectively. The differential cosine signals Sc1p and Sc1n correspond to the differential cosine signals Sc2p and Sc2n, respectively.

[0401] The second amplifier 37 amplifies the differential sinusoidal signals Ss2p and Ss2n and applies an offset voltage Voff2 from the second offset voltage output circuit 39 to output the second sinusoidal signal sin2. Furthermore, it amplifies the differential cosine signals Sc2p and Sc2n and applies an offset voltage Voff2 to output the second cosine signal cos2. The second amplifier 37 includes: a differential amplifier 37a, whose non-inverting input terminal and inverting input terminal are respectively input to the differential sinusoidal signals Ss2p and Ss2n; and a differential amplifier 37b, whose non-inverting input terminal and inverting input terminal are respectively input to the differential cosine signals Sc2p and Sc2n.

[0402] The second offset voltage output circuit 39 applies the offset voltage Voff2 to the non-inverting input terminals of the differential amplifiers 37a and 37b.

[0403] The second offset voltage output circuit 39 can be, for example, a voltage follower circuit having an amplifier 39a. The non-inverting input terminal of the amplifier 39a is input with a divided voltage obtained by dividing the second sensor power supply Vs2 through voltage divider resistors Rd21 and Rd22. For example, the resistance values ​​of the voltage divider resistors Rd21 and Rd22 can be made equal, dividing the second sensor power supply Vs2 in a 1:1 ratio. In this case, the offset voltage Voff2 is half (Vs2 / 2) of the voltage of the second sensor power supply Vs2.

[0404] The first amplifier 36 and the first offset voltage circuit 38 have the same structure as the second amplifier 37 and the second offset voltage circuit 39.

[0405] The first amplifier 36 amplifies the differential sinusoidal signals Ss1p and Ss1n and applies an offset voltage Voff1 to them, which is output from the first offset voltage output circuit 38, to output the first sinusoidal signal sin1. Furthermore, it amplifies the differential cosine signals Sc1p and Sc1n and applies an offset voltage Voff1 to them to output the first cosine signal cos1.

[0406] The first offset voltage output circuit 38 can be, for example, a voltage follower circuit that receives a voltage divided by the first sensor power supply Vs1 through voltage divider resistors Rd11 and Rd12. The offset voltage Voff1 can be, for example, half (Vs1 / 2) of the voltage of the first sensor power supply Vs1.

[0407] The first sine signal sin1, the first cosine signal cos1, the second sine signal sin2, and the second cosine signal cos2 are transmitted to the controller 40 via the wiring harness 35.

[0408] In this invention, in both cases where the ignition switch 11 continuously supplies power to the second sensor Vs2 and when the ignition switch 11 intermittently supplies power to the second sensor Vs2, the following requirements are made: (1) power supply stability on the second sensor 34 side; (2) good EMC (Electromagnetic Compatibility) characteristics; and (3) reduction of dark current when the ignition switch 11 is off.

[0409] From the viewpoint of power supply stability, a large-capacity decoupling capacitor is preferred. On the other hand, when the ignition switch 11, which intermittently supplies power to the second sensor Vs2, is off, a small-capacity bypass capacitor is preferred from the viewpoint of high-speed signal rise and dark current reduction. Furthermore, from the viewpoint of EMC characteristics, a bypass capacitor that functions in the high-frequency region is preferred.

[0410] Through repeated simulations, the inventors discovered that by setting bypass capacitors and decoupling capacitors at the next three locations (1) to (3), a stable second sensor signal can be obtained.

[0411] (1) Input terminal of the second offset voltage output circuit 39

[0412] By setting up a decoupling capacitor C12 in a manner that connects the input terminal of the second offset voltage output circuit 39 to the second sensor ground line GND2 (i.e., by connecting the connection point of voltage divider resistors Rd21 and Rd22 to the second sensor ground line GND2), when the second sensor power supply Vs2 is intermittently supplied, even if the second sensor power supply Vs2 is switched on and off, the voltage fluctuation of the power supply caused by its transient current is blocked by the low-pass filter formed by the voltage divider resistor Rd21 and the decoupling capacitor C12, and the fluctuation of the DC component of the second sensor signal is suppressed. As a result, the stability of the second sensor signal can be improved.

[0413] (2) The position close to the second sensor 34

[0414] By placing bypass capacitors C23 and C24 near the second sensor 34 to connect the power supply line VL2 and the ground line GND2 of the second sensor, the influence of electromagnetic noise generated by the switching of the power supply Vs2 of the second sensor on the second sensor 34 can be suppressed, thereby improving the stability of the second sensor signal.

[0415] (3) Location near the power management unit 50

[0416] A decoupling capacitor C32 (see reference) is installed near the power management section 50 to connect the second sensor power line VL2 of the wiring harness 35 to the ground line GND. Figure 22 This can suppress voltage fluctuations in the power supply that occur when the second sensor power supply Vs2 is switched on and off, thus stabilizing the power supplied by the wiring harness 35. Furthermore, it can reduce noise generated from the wiring harness 35.

[0417] Furthermore, even when the ignition switch 11 is turned on (i.e., when the power supply Vs2 to the second sensor is continuously provided), by connecting the bypass capacitor and the decoupling capacitor at the above three locations (1) to (3), the influence of external noise on the second sensor 34 can be suppressed, thereby improving the stability of the second sensor signal.

[0418] Similar to the second sensor power line VL2 of the second sensor power supply Vs2, a bypass capacitor and a decoupling capacitor can also be provided for the first sensor power line VL1 of the first sensor power supply Vs1. In this embodiment, a decoupling capacitor C11 (see reference) is provided to connect the input terminal of the first offset voltage output circuit 38 and the first sensor ground line GND1. Figure 21 ).

[0419] Furthermore, bypass capacitors C21 and C22 are installed near the first sensor 33 to connect the power supply line VL1 of the first sensor and the ground line GND1 of the first sensor.

[0420] Furthermore, a decoupling capacitor C31 is installed near the power management unit 50 to connect the first sensor power line VL1 of the wiring harness 35 to the ground line GND (see reference). Figure 22 ).

[0421] In addition, bypass capacitor Ce1 and bypass capacitor Ce2 for electrostatic discharge surge (ESD) protection can be provided near the connector connected to wire harness 35. The bypass capacitor Ce1 is connected to the first sensor power line VL1 and the first sensor ground line GND1 on the sensor unit 30 side, and the bypass capacitor Ce2 is connected to the second sensor power line VL2 and the second sensor ground line GND2 on the sensor unit 30 side.

[0422] (Effects of the fourth embodiment)

[0423] (1) The rotation angle detection device of the embodiment includes: a sensor unit 30, which outputs a first sensor signal and a second sensor signal, the first sensor signal including a sine signal and a cosine signal corresponding to the rotation of the motor rotation shaft 21 of the motor 20, and the second sensor signal including a sine signal and a cosine signal corresponding to the rotation of the motor rotation shaft 21; a controller 40, which provides power to the sensor unit 30 and calculates rotation angle information representing the rotation angle of the motor rotation shaft 21 based on the first sensor signal and the second sensor signal; and a wiring harness 35, which connects the controller 40 and the sensor unit 30, transmits power from the controller 40 to the sensor unit 30, and transmits the first sensor signal and the second sensor signal from the sensor unit 30 to the controller 40.

[0424] The sensor unit 30 includes: a first sensor 33, driven by a first sensor power supply Vs1 provided from the controller 40 via a wiring harness 35, which outputs a sine signal and a cosine signal corresponding to the rotation of the motor shaft 21; a first amplifier 36, which amplifies the output signal of the first sensor 33 and outputs it as a first sensor signal; a second sensor 34, driven by a second sensor power supply Vs2 provided from the controller 40 via a wiring harness 35, which outputs a sine signal and a cosine signal corresponding to the rotation of the motor shaft 21; and a second amplifier 37, which amplifies the output signal of the second sensor 34 and outputs it as a second sensor signal. The circuit comprises: first voltage divider resistors Rd11 and Rd12 and second voltage divider resistors Rd21 and Rd22, which divide the voltages of the first sensor power supply Vs1 and the second sensor power supply Vs2 provided from the controller 40 via the wiring harness 35, respectively; a first offset voltage output circuit 38 and a second offset voltage output circuit 39, which are input with divided voltages from the connection point of the first voltage divider resistors Rd11 and Rd12 and the connection point of the second voltage divider resistors Rd21 and Rd22, respectively, to impart offset voltages to the first amplifier 36 and the second amplifier 37; and a decoupling capacitor C12, which is connected to the input terminal of the second offset voltage output circuit 39 and ground.

[0425] The controller 40 has a power management unit 50, which provides continuous power as the first sensor power supply Vs1 and the second sensor power supply Vs2 when the power switch is turned on, and stops providing the first sensor power supply Vs1 and provides intermittent power as the second sensor power supply Vs2 when the power switch is turned off.

[0426] By setting such a decoupling capacitor C12, even when the second sensor power supply Vs2 is intermittently supplied, the voltage fluctuations of the power supply caused by its transient current are blocked by the low-pass filter formed by the voltage divider resistor Rd21 and the decoupling capacitor C12, thus suppressing the fluctuations of the DC component of the second sensor signal. As a result, the stability of the second sensor signal can be improved.

[0427] (2) The sensor unit 30 may also have bypass capacitors C23 and C24 at a position close to the second sensor 34 to connect the power line of the second sensor power supply Vs2 to ground.

[0428] By setting such bypass capacitors C23 and C24, the influence of electromagnetic noise generated by the switching of the second sensor power supply Vs2 on the second sensor 34 can be suppressed, and as a result, the stability of the second sensor signal can be improved.

[0429] (3) The controller 40 may also have a decoupling capacitor C32 at a location close to the power management unit 50, which connects the power line of the second sensor power supply Vs2 of the wiring harness 35 to ground.

[0430] By setting such a decoupling capacitor C32, voltage fluctuations in the power supply generated when the second sensor power supply Vs2 is switched on can be suppressed from entering the wiring harness 35, thereby stabilizing the power supply provided by the wiring harness 35. Furthermore, noise generated from the wiring harness 35 can be reduced.

[0431] (4) The sensor unit 30 may also have bypass capacitors C21 and C22 at a position close to the first sensor 33, which connect the power line of the first sensor power supply Vs1 to ground.

[0432] By setting such bypass capacitors C22 and C22, the influence of electromagnetic noise generated by the switching of the first sensor power supply Vs1 on the first sensor 33 can be suppressed, and as a result, the stability of the first sensor signal can be improved.

[0433] Alternatively, the structures of the first to fourth embodiments described above can be appropriately combined. For example, the power control unit 56 of the power management unit 50 in the third embodiment can also change the driving interval of the second sensor 34 according to the same structure and method as the power control unit 56 in the second embodiment.

[0434] Furthermore, similar to the third embodiment, the comparators 58a and 58b of the second embodiment can operate using the continuous second sensor power supply Vs2 provided by the third power supply unit 54 as power when the ignition switch 11 is turned on, and compare the threshold voltage Vr based on the voltage of the second sensor power supply Vs2 with the second sensor signal. When the ignition switch 11 is turned off, they can operate using the intermittent second sensor power supply Vs2 provided by the third power supply unit 54 as power, and compare the threshold voltage Vr based on the voltage of the second sensor power supply Vs2 with the second sensor signal. The sine counter 58c and cosine counter 58d operate using the internal power supply Vp as power.

[0435] Furthermore, for example, the same bypass capacitors can be provided for the sensor unit 30 and controller 40 in the first to third embodiments as in the fourth embodiment.

[0436] (Modified Example)

[0437] The above description illustrates an example of applying the rotation angle detection device of the present invention to a column-assisted electric power steering system, also known as an upstream-assisted system. However, the rotation angle detection device of the present invention can also be applied to a downstream-assisted electric power steering system. Hereinafter, examples of applying the rotation angle detection device of the present invention to single-pinion-assisted, rack-assisted, and double-pinion-assisted electric power steering systems will be described as examples of downstream-assisted electric power steering systems.

[0438] Furthermore, in the case of downstream auxiliary methods, for waterproofing purposes, the motor 20, sensor unit 30, and controller 40 do not need to be separate units, but rather... Figures 23-25 As shown by the dashed line, it is an integrated MCU (Motor Control Unit). In this case, the sensor ICs, which are the first sensor 33 and the second sensor 34 mentioned above, can be built into the circuit board of the controller 40.

[0439] Figure 23 This diagram illustrates a structural example of the rotation angle detection device of the present invention applied to an electric power steering system with single pinion assist. A column shaft 2 is provided instead of column shafts 2i and 2o and the torsion bar (not shown) connecting them. The steering wheel 1 is connected to a universal joint 4A on one side of the intermediate shaft via the column shaft 2. Furthermore, an input-side shaft 4C with a torsion bar (not shown) is connected to a universal joint 4B on the other side.

[0440] The gear and rack mechanism 5 includes a pinion shaft 5A, a pinion 5B, and a rack rod 5C. The input side shaft 4C and the gear and rack mechanism 5 are connected by a torsion bar (not shown) that twists due to the deviation of the rotation angle between the input side shaft 4C and the gear and rack mechanism 5. The torque sensor 10 electromagnetically measures the torsion angle of the torsion bar as the steering torque Th of the steering wheel 1.

[0441] The motor 20, which provides steering force to the auxiliary steering wheel 1, is connected at the pinion shaft 5A via the reduction gear 3. The sensor unit 30 calculates the rotation angle information of the motor rotation shaft of the motor 20 in the same manner as in the above embodiment.

[0442] Figure 24 This diagram illustrates a structural example of the rotation angle detection device of the present invention applied in a rack-assisted electric power steering system. A helical groove (not shown) is formed on the outer circumferential surface of the rack rod 5C, and a similar helical groove (not shown) is formed on the inner circumferential surface of the nut 7A. A ball screw is formed by arranging multiple rolling elements along the rolling path formed by these helical grooves.

[0443] A belt 7D is wound around a drive pulley 7B connected to the rotating shaft 20a of the motor 20 that provides steering force to the auxiliary steering wheel 1, and a driven pulley 7C connected to a nut 7A. The rotational motion of the rotating shaft 20a is converted into the linear motion of the rack 5C. The sensor unit 30 calculates the rotation angle information of the motor rotating shaft of the motor 20 in the same manner as in the above embodiment.

[0444] Figure 25 This diagram illustrates a structural example of the rotation angle detection device of the present invention applied in an electric power steering system with dual pinion assist. The electric power steering system with dual pinion assist, in addition to having a pinion shaft 5A and a pinion 5B, has a second pinion shaft 8A and a second pinion 8B. The rack rod 5C has a first rack tooth (not shown) meshing with the pinion 5B and a second rack tooth (not shown) meshing with the second pinion 8B.

[0445] The motor 20, which provides steering force to the auxiliary steering wheel 1, is connected to the second pinion shaft 8A via the reduction gear 3. The sensor unit 30 calculates the rotation angle information of the motor rotation shaft of the motor 20 in the same manner as in the above embodiment.

[0446] Label Explanation

[0447] 1: Steering wheel; 2i: Column shaft (input shaft); 2o: Column shaft (output shaft); 3: Reduction gear; 4A, 4B: Universal joint; 5: Gear and rack mechanism; 6: Tie rod; 10: Torque sensor; 11: Ignition switch (power switch); 12: Vehicle speed sensor; 14: Battery; 20: Motor; 30: Sensor unit; 33: First sensor; 34: Second sensor; 35: Wiring harness; 36: First amplifier; 37: Second amplifier; 38: First offset voltage output circuit; 39: Second offset voltage output circuit; 40: Controller; 50: Power management unit; 51: Regulator; 52: First power supply unit; 53: Second power supply unit; 54: Third power supply unit; 55: Internal power generation unit; 56: Power control unit; 57: Sensor power supply determination unit; 58: Rotation count detection unit; 58a: First comparator; 58b: Second comparator; 58c: Sine counter; 58d: Cosine counter; 60: Microprocessor; 61: Angle position calculation unit; 62: Counting unit; 63: Rotation count information correction unit; 63a: First quadrant information calculation unit; 63b: Second quadrant information calculation unit; 63c: Quadrant comparison unit; 63d: Correction unit; 64: Rotation count calculation unit; 65: Angle calculation unit; 66: Rotation angle information calculation unit; 66a, 66c: Multipliers; 66b, 66d: Adders; 67: Diagnostic unit; 68: Auxiliary control unit; C11, C12, C31, C32: Decoupling capacitors; C21~C24, Ce1, Ce2: Bypass capacitors.

Claims

1. A rotation angle detection device, characterized in that, The rotation angle detection device has the following features: The first sensor is powered when the power switch is on, outputs a first sensor signal corresponding to the rotation of the motor's rotating shaft, and the power supply is stopped when the power switch is off. An angle position calculation unit is powered when the power switch is on, calculates angle position information representing the angle position of the motor rotation shaft based on the first sensor signal, and stops power supply when the power switch is off. The second sensor outputs a second sensor signal containing a sine signal and a cosine signal corresponding to the rotation of the motor's rotating shaft; The power management unit provides a first power supply as continuous power to the second sensor when the power switch is turned on, and provides a second power supply as intermittent power with a voltage lower than the first power supply to the second sensor when the power switch is turned off, and outputs rotation number information indicating the number of rotations of the motor shaft based on the signal from the second sensor. as well as The rotation angle calculation unit is powered when the power switch is on, and calculates rotation angle information representing the rotation angle of the motor shaft based on the angular position information and the number of rotation revolutions information. Power supply is stopped when the power switch is off. The power management unit has: A power supply unit that generates the first power and the second power; A comparator that operates using the first power supplied by the power supply unit as power source when the power switch is on, and compares a first reference voltage based on the voltage of the first power source with the second sensor signal; and operates using the second power supplied by the power supply unit as power source when the power switch is off, and compares a second reference voltage based on the voltage of the second power source with the second sensor signal. as well as A counter that detects the number of rotations of the motor shaft by counting the output of the comparator.

2. The rotation angle detection device according to claim 1, characterized in that, The power supply unit provides the first power as a power source to the counter when the power switch is turned on, and generates a third power as a power source to the counter when the power switch is turned off. The third power is a continuous power having a voltage equal to that of the second power.

3. The rotation angle detection device according to claim 2, characterized in that, The power management unit includes a regulator that generates a fourth power source with a first regulator voltage as continuous power from an external power source when the power switch is on, and generates a fifth power source with a second regulator voltage lower than the first regulator voltage as continuous power from the external power source when the power switch is off. The power supply unit generates the first power based on the fourth power, and generates the second power and the third power based on the fifth power.

4. The rotation angle detection device according to any one of claims 1 to 3, characterized in that, The comparator and the power supply unit are housed within a single integrated circuit chip.

5. The rotation angle detection device according to any one of claims 1 to 3, characterized in that, The duration of one intermittent output of the second power is set based on the allowable current consumption of the rotation angle detection device when the power switch is off.

6. The rotation angle detection device according to claim 5, characterized in that, The time width of one intermittent output of the second power is set according to the time constant of the second sensor signal when the intermittent second power is provided.

7. The rotation angle detection device according to claim 5, characterized in that, The duration of one intermittent output of the second power is less than 220 microseconds.

8. An electric power steering device, characterized in that, This electric power steering system has the following features: A torque sensor detects the steering torque applied to the steering shaft based on the torsion angle between the input and output shafts connected via a torsion bar mounted on the steering shaft of the vehicle. A motor, which is connected to the output shaft via a reduction gear and provides steering assistance to the vehicle's steering mechanism; The rotation angle detection device according to any one of claims 1 to 3 calculates the rotation angle information of the motor rotation shaft of the motor; A motor control unit that performs drive control on the motor based on the steering torque; as well as The steering angle calculation unit calculates the steering angle of the input shaft based on the torsion angle, the reduction ratio of the reduction gear, and the rotation angle information.

9. A control method for an electric power steering device, wherein the control method is the control method for the electric power steering device according to claim 8, characterized in that, The steering assist force applied by the motor is controlled based on the steering angle calculated by the steering angle calculation unit.

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