JP7424243B2 - steering control device - Google Patents

Description

The present invention relates to a steering control device.

Conventionally, control devices related to electric power steering devices (EPS) and steering lock devices for preventing theft during parking are known.

For example, the electric power steering device disclosed in Patent Document 1 detects the torque applied to the steering shaft and drives the EPS motor to reduce the load from the shaft. The lock device control method disclosed in Patent Document 2 reliably achieves locking by automatically rotating the steering column by a certain amount using EPS.

The vehicle steering device disclosed in Patent Document 3 includes an EPS three-phase motor, and three DC motors: a tilt motor, a telescopic motor, and a lock motor. In this vehicle steering system, a three-phase motor and a DC motor share a power conversion circuit.

Japanese Patent Application Publication No. 2014-108661 Special table 2014-505626 publication Patent No. 5614588

In this specification, a "steering assist actuator" including an electric actuator other than a motor is used as a generic term for an EPS motor, that is, a steering assist motor. Similarly, "lock actuator", which includes electrical actuators other than motors, is used as a generic term for steering lock motor. Furthermore, since a steering control device is assumed, the steering lock actuator will be abbreviated as "lock actuator".

In the devices of Patent Documents 1 and 2, power conversion circuits are required for each of the EPS motor and the motor of the locking device, so the installation space increases. On the other hand, the device of Patent Document 3 aims to downsize the power conversion circuit by sharing the power conversion circuit with the three-phase motor and the locking DC motor.

However, in the device of Patent Document 3, the timing at which the DC motor is driven and the timing at which the EPS three-phase motor is driven are different. In other words, this device is not designed to simultaneously drive the locking DC motor and the EPS three-phase motor. Also, due to the circuit configuration, it is not possible to control the current supply to the locking DC motor and the EPS three-phase motor at the same time. Therefore, it is not possible to use the three-phase EPS motor to support locking and unlocking operations in a reliable manner.

The present invention was created in view of these points, and its purpose is to reduce the size of the power conversion circuit in a steering control device that controls the drive of the steering assist actuator and the lock actuator, and to achieve locking by the steering assist actuator. An object of the present invention is to provide a steering control device capable of supporting operation and unlocking operation.

The steering control device of the present invention includes a first circuit (68, 681, 682), a second circuit (67), and a control section (30). The first circuit is a power conversion circuit that energizes a steering assist actuator (800) that electrically assists the driver's steering operation. The second circuit is a power conversion circuit that energizes a lock actuator (710) that drives a locking device (20) that mechanically restricts the rotation of the steering wheel (91) to perform a locking or unlocking operation. The control unit operates the first circuit and the second circuit to control operations of the steering assist actuator and the lock actuator.

The first circuit and the second circuit are provided within the same housing (600). If a set of high-potential side and low-potential side switching elements connected in series in the first circuit and the second circuit are legs, the first circuit and the second circuit share one leg. power conversion circuit (60). The control unit simultaneously operates the steering assist actuator and the lock actuator so as to support the locking operation or unlocking operation of the locking device by rotating the steering wheel.

In the present invention, the first circuit that energizes the steering assist actuator and the second circuit that energizes the lock actuator form an integrated power conversion circuit that shares one leg. Therefore, it is possible to downsize a power conversion circuit that drives a plurality of motors.

Further, in the circuit topology of the present invention, the integrated power conversion circuit is operated by a common control unit, and the steering assist actuator and the lock actuator can be operated simultaneously. Therefore, if there is a problem when locking, the locking operation can be supported by, for example, swinging the steering assist actuator. Alternatively, if there is a problem in unlocking, the unlocking operation can be supported by, for example, rotating the steering assist actuator in one direction. As described above, in the present invention, it is possible to achieve both miniaturization of the power conversion circuit and smooth operation of the steering lock mechanism.

FIG. 1 is a diagram of a column type EPS system to which the steering control device of this embodiment is applied. A diagram of the rack type EPS system same as above. Diagram of the SBW system same as above. The figure which shows the example of a connection structure of a connector. FIG. 2 is a circuit configuration diagram of an integrated power conversion circuit that drives one system of three-phase motors. FIG. 3 is a circuit configuration diagram of an integrated power conversion circuit that drives two systems of three-phase motors. FIG. 1 is a schematic diagram showing the configuration of a three-phase double-winding rotating machine. FIG. 1 is a schematic diagram showing the overall configuration of a locking device. A schematic cross-sectional view taken along the line IX-IX in FIG. 8. FIG. 3 is a diagram of the locking state of the locking device. (a) A diagram illustrating problems during locking, and (b) a diagram illustrating support for locking operation by swinging of the EPS motor. (a) A diagram illustrating a problem at unlocking, and (b) a diagram illustrating support for unlocking operation by retracting rotation of an EPS motor. Flowchart showing the sequence when starting the engine. Flowchart showing the sequence when the engine is stopped. Operation time chart when locked (1). Operation time chart when locked (2). Operation time chart when unlocking (1). Operation time chart when unlocking (2). FIG. 2 is a block diagram showing a control algorithm of the first embodiment (torque control). FIG. 3 is a block diagram illustrating a control algorithm for temporary rotational drive for determining a retraction direction when unlocking. FIG. 3 is a block diagram showing a control algorithm for torque control in a two-system drive configuration. FIG. 3 is a block diagram showing a control algorithm of a second embodiment (position control). FIG. 7 is a block diagram showing a control algorithm of a third embodiment (speed control). FIG. 7 is a block diagram showing a control algorithm of a fourth embodiment (current control). FIG. 7 is a block diagram showing a control algorithm of a fifth embodiment (voltage control). FIG. 3 is a diagram of a modification of the rack type EPS system of FIG. 2;

Hereinafter, a plurality of embodiments of a steering control device of the present invention will be described based on the drawings. The steering control device of each embodiment is applied to a vehicle's electric power steering system (hereinafter referred to as "EPS system") or steer-by-wire system (hereinafter referred to as "SBW system"), and functions as an EPS-ECU or SBW-ECU. Hereinafter, EPS-ECU or SBW-ECU will be collectively referred to as "ECU". In addition, each embodiment described below will be collectively referred to as the "present embodiment". Substantially the same configurations in the plurality of embodiments are given the same reference numerals, and description thereof will be omitted.

[System configuration]
First, with reference to FIGS. 1 to 3, the configuration of a system to which an ECU as a "steering control device" is applied will be described. 1 and 2 show an EPS system 901 in which a steering mechanism and a steering mechanism are mechanically connected. Among them, FIG. 1 shows a column type EPS system 901, and FIG. 2 shows a rack type EPS system 901. To distinguish between them, the column type EPS system is designated by the code 901C, and the rack type EPS system is designated by the code 901R. FIG. 3 shows an SBW system 902 in which the steering mechanism and steering mechanism are mechanically separated. In FIGS. 1 to 3, only one side of the wheel 99 is shown, and illustration of the wheel on the opposite side is omitted.

The EPS system 901 includes an EPS motor 800 as a "steering assist actuator", and the SBW system 902 includes a reaction force motor 800 as a "steering assist actuator". In this specification, the application of reaction force by the SBW system 902 is broadly interpreted as the same concept as the steering assist by the EPS system 901. Furthermore, the EPS system 901 and the SBW system 902 commonly include a steering lock motor (hereinafter referred to as "lock motor") 710 as a "lock actuator".

As shown in FIGS. 1 and 2, the EPS system 901 includes a steering wheel 91 as a "steering", a steering shaft 92, an intermediate shaft 95, a steering rack 97, and the like. The steering shaft 92 is enclosed in a steering column 93, and has one end connected to the steering wheel 91 and the other end connected to an intermediate shaft 95. Note that the "steering" steered by the driver may be a steering stick having a shape other than the ring-shaped steering wheel 91.

A steering rack 97 is provided at the end of the intermediate shaft 95 opposite to the steering wheel 91, which uses a rack and pinion mechanism to convert rotation into reciprocating motion and transmit the same. When the steering rack 97 reciprocates, the wheels 99 are steered via the tie rods 98 and knuckle arms 985. Moreover, universal joints 961 and 962 are provided in the middle of the intermediate shaft 95.

The EPS motor 800 electrically assists the driver in steering. In the column type EPS system 901C shown in FIG. 1, the EPS motor 800 and the locking device 20 are both arranged on the steering column 93. The output torque of the EPS motor 800 is transmitted to the steering shaft 92. The torque sensor 94 is provided in the middle of the steering shaft 92, detects torque based on torsional displacement of the torsion bar, and outputs a torque sensor value T_sns.

In the rack type EPS system 901R shown in FIG. 2, the EPS motor 800 and the locking device 20 are both arranged in the steering rack 97. The reciprocating movement of the steering rack 97 is assisted by the output torque of the EPS motor 800. Torque sensor 94 detects torque transmitted to steering rack 97 and outputs torque sensor value T_sns.

The torque detected by the torque sensor 94 is not limited to the steering torque applied to the steering wheel 91 by the driver. For example, as described in Patent Document 1 (Japanese Unexamined Patent Publication No. 2014-108661), when the wheels 99 are parked in a twisted state, the wheels 99 receive a restoring force from the road surface to reduce the twist. There is. This restoring force is transmitted to the steering rack 97 and the steering shaft 92, and is detected by the torque sensor 94 when the vehicle is parked. The torque sensor value during parking is used for unlocking the locking device 20, as will be described later.

The locking device 20 is disposed closer to the driver than the torque sensor 94, that is, closer to the steering wheel 91, and mechanically restricts rotation of the steering wheel. The lock motor 710 drives the locking device 20 to perform a locking operation or an unlocking operation. The locking operation of the locking device 20 prevents the vehicle from being stolen when the vehicle is parked. Further, when the driver starts driving the vehicle, the locking device 20 performs an unlocking operation, thereby enabling the driver to perform steering operation.

The ECU 10 instructs the lock motor 710 to lock or unlock the lock device 20 based on the ON/OFF signal of the vehicle switch 11. Note that the vehicle switch 11 corresponds to an ignition switch or a push switch of an engine vehicle, a hybrid vehicle, or an electric vehicle. Each signal to the ECU 10 is communicated using CAN, serial communication, etc., or sent as an analog voltage signal.

Next, as shown in FIG. 3, in the SBW system 902 in which the steering mechanism and the turning mechanism are mechanically separated, the intermediate shaft 95 does not exist in the EPS system 901. Driver input information such as the driver's steering torque or the angle of the steering wheel 91 is electrically transmitted to the steering motor 890 via the ECU 10. The rotation of steering motor 890 is converted into reciprocating motion of steering rack 97, and wheels 99 are steered via tie rods 98 and knuckle arms 985. Although not shown in FIG. 3, there is a steering motor ECU that drives the steering motor 890 in response to steering wheel input from the driver.

Furthermore, in the SBW system 902, the driver cannot directly sense reaction force to steering. Therefore, the ECU 10 controls the drive of the reaction force motor 800, rotates the steering wheel 91 so as to apply a reaction force to the steering, and provides an appropriate steering feeling to the driver. In SBW system 902, lock motor 710 is used similarly to column type EPS system 901C of FIG. Hereinafter, in the explanation of the EPS motor or reaction force motor 800 and lock motor 710 by the ECU 10, there is no difference between the EPS system 901 and the SBW system 902. Therefore, the EPS motor 800 will be described as a representative, and the description of the reaction force motor 800 will be omitted.

In this embodiment, the EPS motor 800 is composed of a three-phase motor, and the lock motor 710 is composed of a DC motor. The control unit 30 applies voltage to the EPS motor 800 and the lock motor 710, and supplies current to the EPS motor 800 and the lock motor 710. The three-phase inverter circuit 68 as the "first circuit" is a power conversion circuit that supplies electricity to the EPS motor 800. The H-bridge circuit 67 as a "second circuit" is a power conversion circuit that supplies power to the lock motor 710.

In this embodiment, the three-phase inverter circuit 68 and the H-bridge circuit 67 are provided in the same housing 600 together with the control unit 30. Furthermore, in this embodiment, the EPS motor 800 is provided within the same housing 600 as a "mechanical and electrically integrated" motor. This makes it possible to downsize the ECU 10 and reduce the number of wiring components such as harnesses and connectors. Further, as will be described in detail later with reference to FIGS. 5 and 6, the three-phase inverter circuit 68 and the H-bridge circuit 67 form an "integrated power conversion circuit 60" that shares one leg. In FIGS. 1 to 3, the frames of the three-phase inverter circuit 68 and the H-bridge circuit 67 are illustrated so as to partially overlap, which means that the two circuits share a leg.

The control unit 30 is composed of a microcomputer, a drive circuit, etc., and includes a CPU (not shown), a ROM, a RAM, an I/O, a bus line connecting these components, etc., and a physical memory device such as a ROM (i.e. , a readable non-temporary tangible recording medium) by executing a program stored in advance on a CPU, or control by hardware processing using a dedicated electronic circuit.

The control unit 30 is provided in common to the three-phase inverter circuit 68 and the H-bridge circuit 67, and controls the operations of the EPS motor 800 and the lock motor 710. The control unit 30 operates the three-phase inverter circuit 68 based on the torque sensor value T_sns detected by the torque sensor 94 and the vehicle speed V detected by the vehicle speed sensor 14, and controls the operation of the EPS motor 800. The EPS motor 800 electrically assists the driver in steering. The control unit 30 also operates the H-bridge circuit 67 to control the operation of the lock motor 710.

Next, referring to FIG. 4, an example of a connector connection configuration is shown. The EPS motor 800 of this embodiment is configured as a "mechanically and electrically integrated" brushless three-phase motor in which the ECU 10 is integrally configured on one side in the axial direction. On the other hand, each DC motor functioning as the lock motor 710 is connected to the ECU 10 via a connector.

In this connection configuration, a power system connector 591, a signal system connector 592, and a torque sensor connector 593 are provided separately. A power line (PIG) from a DC power source and a ground line are connected to the power system connector 591. The signal system connector 592 is connected to a control power line (IG), a CAN communication line, an authentication signal, a stop command signal line, and the lock motor 710 wiring. A power line, a signal line, and a ground line of the torque sensor 94 are all connected to the torque sensor connector 593.

Motor wires (M+, M-) are connected to the lock motor 710. Although the motor wires (M+, M-) of the lock motor 710 are power-related, the motor current is smaller than that of the EPS motor 800, so they can be included and connected to the signal-related connector 592. If the current of the lock motor 710 is large, a separate connector may be used, or a common connector may be used as the power system connector 591 for the power line (PIG) from the DC power supply and the ground line. The connector for the lock motor 710 signal may be separated.

[Configuration of integrated power conversion circuit]
Next, an example of the circuit configuration of the integrated power conversion circuit will be described with reference to FIGS. 5 to 7. First, regarding the EPS motor 800 that is driven by the three-phase inverter circuit 68, a unit including a three-phase winding set and a three-phase inverter circuit corresponding to the winding set is referred to as a "system." FIG. 5 shows an example of the circuit configuration of one system, and FIG. 6 shows an example of the circuit configuration of two systems. As shown in FIG. 7, in the two-system configuration, the "first circuit" 68 consists of two three-phase inverter circuits 681 and 682.

A three-phase winding set having a single system configuration includes U-phase, V-phase, and W-phase windings 811, 812, and 813 connected at a neutral point N. A voltage is applied from the three-phase inverter circuit 68 to the windings 811, 812, and 813 of each phase. A back electromotive force proportional to the product of the rotation speed and the sine value of the phase is generated in each phase. The back electromotive force generated in each phase is expressed by, for example, equations (1.1) to (1.3) based on voltage amplitude A, rotation speed ω, and phase θ.

Eu=-Aωsinθ...(1.1)
Ev=-Aωsin(θ-120)...(1.2)
Ew=-Aωsin(θ+120)...(1.3)

The two-system EPS motor 800 has two three-phase winding sets 801 and 802. The three-phase winding set 801 of the first system includes windings 811, 812, and 813 of U1 phase, V1 phase, and W1 phase connected at neutral point N1. A voltage is applied from the first system three-phase inverter circuit 681 to the windings 811, 812, and 813 of each phase of the first system three-phase winding set 801.

The three-phase winding set 802 of the second system is configured by windings 821, 822, and 823 of U2 phase, V2 phase, and W2 phase connected at neutral point N2. A voltage is applied to the windings 821, 822, and 823 of each phase of the three-phase winding set 802 of the second system from the three-phase inverter circuit 682 of the second system.

As shown in FIG. 7, the two-system EPS motor 800 is a double-winding rotating machine in which two three-phase winding sets 801 and 802 are coaxially provided. The two three-phase winding sets 801 and 802 have the same electrical characteristics, and are arranged, for example, on a common stator with an electrical angle of 30[deg] shifted from each other. In that case, the back electromotive force generated in each phase of the first system and the second system is based on the voltage amplitude A, the rotation speed ω, and the phase θ, for example, equations (2.1) to (2.3), (2 .4a) to (2.6a).

Eu1=-Aωsinθ...(2.1)
Ev1=-Aωsin(θ-120)...(2.2)
Ew1=-Aωsin(θ+120)...(2.3)
Eu2=-Aωsin(θ+30)...(2.4a)
Ev2=-Aωsin(θ-90)...(2.5a)
Ew2=-Aωsin(θ+150)...(2.6a)

Note that when the phase relationship of the two systems is reversed, for example, the phase of the U2 phase (θ+30) becomes (θ−30). Furthermore, a phase difference equivalent to 30[deg] is generalized and expressed as (30±60×k)[deg] (k is an integer). Alternatively, the second system may be arranged in the same phase as the first system. In that case, the back electromotive force generated in each phase of the second system is expressed by equations (2.4b) to (2.6b) instead of equations (2.4a) to (2.6a).

Eu2=-Aωsin(θ-30)...(2.4b)
Ev2=-Aωsin(θ+90)...(2.5b)
Ew2=-Aωsin(θ-150)...(2.6b)

A lock motor 710 that is driven by the H-bridge circuit 67 is composed of a winding 714 . When the lock motor 710 is energized, a back electromotive force E1 proportional to the rotational speed ω1 is generated. When the proportionality constant is E, the back electromotive force E1 is expressed by the formula "E1=-Eω1". Further, the direct current applied to the lock motor 710 is denoted as I1.

Next, examples of circuit configurations for one system and two systems will be explained in order. In the circuit configuration example of one system shown in FIG. 5, one leg of the H-bridge circuit 67 is shared with the U-phase leg of the three-phase inverter circuit 68. For convenience of illustration, the symbol "67" appears to refer to the non-shared leg, but in reality it refers to the combined portion of the U-phase leg and the non-shared leg of the three-phase inverter circuit 68. There is.

In this specification, a power conversion circuit configured by sharing one phase (for example, U-phase) leg of the three-phase inverter circuit 68 and one leg of the H-bridge circuit 67 is referred to as an "integrated power conversion circuit". "circuit". In the circuit configuration example of FIG. 5, one system of three-phase inverter circuit 68 and H-bridge circuit 67 constitute an integrated power conversion circuit 60.

The integrated power conversion circuit 60 is connected to the positive electrode of the power source Bt via the high potential line Lp, and connected to the negative electrode of the power source Bt via the low potential line Lg. The power source Bt is, for example, a battery with a reference voltage of 12 [V]. The DC voltage input from the power supply Bt to the integrated power conversion circuit 60 will be referred to as "input voltage Vr."

On the power supply Bt side of the integrated power conversion circuit 60, a capacitor C is provided between the high potential line Lp and the low potential line Lg. In the current path between the power supply Bt and the capacitor C, a power supply relay Pr is connected in series on the power supply Bt side, and a reverse connection protection relay PR is connected in series on the capacitor C side. The power supply relay Pr and the reverse connection protection relay PR are constituted by a semiconductor switching element such as a MOSFET, a mechanical relay, or the like, and can cut off the power supply from the power supply Bt to the integrated power conversion circuit 60 when turned off. The power supply relay Pr interrupts the current flowing in the direction when the electrodes of the power supply Bt are connected in the normal direction. The reverse connection protection relay PR blocks current flowing when the electrodes of the power source Bt are connected in a direction opposite to the normal direction.

The three-phase inverter circuit 68 converts the DC power of the power source Bt into three-phase AC power through the operation of a plurality of bridge-connected high-potential side and low-potential side inverter switching elements IUH, IUL, IVH, IVL, IWH, and IWL. Then, the EPS motor 800 is energized. Specifically, inverter switching elements IUH, IVH, and IWH are upper arm elements provided on the high potential side of U phase, V phase, and W phase, respectively, and inverter switching elements IUL, IVL, and IWL are upper arm elements provided on the high potential side of U phase, V phase, and W phase, respectively. This is a lower arm element provided on the low potential side of the W phase and the W phase. Hereinafter, the upper arm element and lower arm element of the same phase will be collectively referred to as "IUH/L, IVH/L, and IWH/L." Further, a set of switching elements on the high potential side and the low potential side connected in series is referred to as a "leg". "IUH/L" corresponds to the code of the U-phase leg.

Between the lower arm elements IUL, IVL, and IWL of each phase of the three-phase inverter circuit 68 and the low potential line Lg, there are current sensors SAU, SAV, and SAW that detect phase currents Iu, Iv, and Iw flowing through each phase. is set up. The current sensors SAU, SAV, and SAW are composed of shunt resistors, for example.

The non-shared leg of the H-bridge circuit 67 includes a switching element MU1H on the high potential side and a switching element MU1L on the low potential side, which are connected in series via the DC motor terminal M1. Hereinafter, a set of switching elements constituting the non-shared leg will be referred to as a "DC motor switching element." Similar to the inverter switching element, the high-potential side and low-potential side switches are collectively referred to as "MU1H/L" for the DC motor switching element.

The phase inverter switching elements IUH/L, IVH/L, IWH/L and the DC motor switching element MU1H/L of the three-phase inverter circuit 68 are, for example, MOSFETs. In addition, the switching element may be a field effect transistor, IGBT, or the like other than MOSFET. Here, the current flowing through the lock motor 710 is smaller than the phase current flowing through the EPS motor 800. Therefore, a switch having a smaller current capacity than the inverter switching elements IUH/L, IVH/L, and IWH/L may be used as the DC motor switching element MU1H/L. Further, since it is sufficient to be able to lock and release, high-speed switching is not necessary, and a switch or mechanical relay with a slow on time may be used.

A first terminal T1, which is one end of the lock motor 710, is connected to a branch point Ju of the U-phase current path of the three-phase winding set. A second terminal T2, which is the end of the lock motor 710 opposite to the first terminal T1, is connected to a DC motor terminal M1 between the DC motor switches MU1H/L. DC motor switch MU1H/L is connected to U-phase winding 811 via lock motor 710. The "U" in the code "MU1H/L" of the DC motor switch means U phase, and "1" is the number of the DC motor.

With respect to the phase currents Iu, Iv, and Iw flowing through the three-phase inverter circuit 68, the phase currents flowing through the three-phase winding set are denoted as Iu#, Iv#, and Iw#. In the example of FIG. 5, a part of the phase current Iu is separated as a DC motor current I1 at a branch point Ju of the U-phase current path. The relationship between the inverter phase currents Iu, Iv, Iw flowing to the three-phase inverter circuit 68 side of the branch point Ju and the motor phase currents Iu#, Iv#, Iw# flowing to the EPS motor 800 side of the branch point Ju is as follows. It is represented by formulas (3.1) to (3.4).

Iu#=-Iv-Iw...(3.1)
Iv#=Iv...(3.2)
Iw#=Iw...(3.3)
I1=Iu-Iu#...(3.4)

In the lock motor 710, the direction of the current I1 flowing from the first terminal T1 to the second terminal T2 is defined as a positive direction, and the direction of the current I1 flowing from the second terminal T2 toward the first terminal T1 is defined as a negative direction. A voltage Vx is applied between the first terminal T1 and the second terminal T2. The lock motor 710 rotates in the normal direction when it is energized in the positive direction, and rotates in the reverse direction when it is energized in the negative direction. For example, when the lock motor 710 rotates in the normal direction, the lock device 20 is locked, and when the lock motor 710 rotates in the reverse direction, the lock device 20 is unlocked.

The control unit 30 operates the voltage at the neutral point N using the three-phase voltage command value of the EPS motor 800, and outputs a "gate signal" to keep the U-phase voltage command value constant. At the same time, the control unit 30 issues a "lock motor drive command" to turn on one of the DC motor switches MU1H/L and turn off the other, depending on the rotational direction of the lock motor 710. In this way, the control unit 30 operates the EPS motor 800 and the lock motor 710 simultaneously.

In the two-system circuit configuration example shown in FIG. 6, a "first circuit" 68 (see FIG. 7 for the reference numeral) that supplies current to the EPS motor 800 is composed of two three-phase inverter circuits 681 and 682. The first system three-phase inverter circuit 681 is connected to the U1 phase, V1 phase, and W1 phase windings 811, 812, and 813 of the three-phase winding set 801. The second system three-phase inverter circuit 682 is connected to the U2 phase, V2 phase, and W2 phase windings 821, 822, and 823 of the three-phase winding set 802. The symbols of the components of the second system and the symbols of the currents are represented by replacing "1" in the symbols of the components and currents of the first system with "2". Furthermore, the explanation regarding the components of the first system is used for the components of the second system.

The first system three-phase inverter circuit 681 is provided with inverter switching elements IU1H/L, IV1H/L, IW1H/L, and current sensors SAU1, SAV1, and SAW1 that detect phase currents Iu1, Iv1, and Iw1. ing. A capacitor C1 is provided on the power supply Bt side of the three-phase inverter circuit 681. Further, a power supply relay P1r and a reverse connection protection relay P1R are provided between the power supply Bt and the three-phase inverter circuit 681. The DC voltage input from the power supply Bt to the three-phase inverter circuit 681 is referred to as "input voltage Vr1." Phase currents Iu1#, Iv1#, and Iw1# are applied to the three-phase winding set 801.

In the configuration example of FIG. 6, the first system of circuits is configured similarly to the one system of circuits shown in FIG. That is, one end of the lock motor 710 is connected to the branch point Ju of the U1 phase current path of the three-phase winding set 801 of the first system, and the U1 phase leg of the three-phase inverter circuit 681 of the first system is connected to the H bridge circuit. It is shared with one leg of 67. On the other hand, the second system circuit is not directly connected to the lock motor 710 and is used exclusively for driving the EPS motor 800.

In the following description of simultaneous driving of the EPS motor 800 and the lock motor 710, a single system configuration will be basically shown. When the EPS motor 800 has a two-system configuration, the control of the second system may be appropriately added to the control of the first system.

[Mechanical configuration of locking device]
Next, with reference to FIGS. 8 to 12, the mechanical configuration and effects of the locking device 20 will be described. First, FIGS. 8 to 10 show the overall configuration and locked state of the locking device 20. As shown in FIG. 8, the lock device 20 has a movable part 21 and a locked body 25. The movable part 21 is reciprocated by a lock motor 710. The locked body 25 is rotatably provided coaxially with the steering wheel 91, for example.

As shown in FIG. 10, the locked body 25 has one or more convex portions 27 and one or more concave portions 28 disposed in the circumferential direction, and rotates in the Rs direction following the steering wheel 91. The locked body 25 in FIG. 10 is configured as a rotationally symmetrical "gear slot" in which a plurality of convex parts 27 and a plurality of concave parts 28 are arranged at equal intervals in the circumferential direction around a base cylinder part 29. . In the description of the embodiment, the term "gear slot 25" will be used instead of the locked body 25 as appropriate.

As an example of the configuration of the movable part 21, FIGS. 8 and 9 show an example in which the rotation axis Az of the lock motor 710 and the axis Ax of rotation and reciprocating movement of the movable part 21 are disposed orthogonal to each other. The motor output shaft 715 of the lock motor 710 rotates forward and backward in the Rz direction about the rotation axis Az. The motor output shaft 715 and the driven gear section 215 of the movable section 21 constitute a worm gear, and the driven gear section 215 rotates forward and backward in the Rx direction about the rotation axis Ax as the motor output shaft 715 rotates. .

When the driven gear section 215 rotates, the coaxially fixed male threaded section 216 rotates, and the nut section 217 that is screwed into the male threaded section 216 reciprocates in the Lx direction. A rod-shaped lock rod 23 is connected to the distal end side of the nut portion 217. When no external force is applied to the lock rod 23, the lock rod 23 reciprocates in the Lx direction together with the nut portion 217.

The rotation axis O of the gear slot 25 is arranged to be perpendicular to the extension line of the axis Ax of the movable part 21. Depending on the rotational position of the gear slot 25, the radially outer wall of the convex portion 27 or the concave portion 28 faces the distal end surface of the lock rod 23. Here, the movement of the lock rod 23 toward the gear slot 25 is defined as forward movement, and the movement of the lock rod 23 away from the gear slot 25 is defined as movement backward. The control unit 30 energizes the lock motor 710 through the H-bridge circuit 67 to move the lock rod 23 forward or backward relative to the gear slot 25 .

When the locking device 20 is to be locked, the control unit 30 advances the lock rod 23 so that it fits between the adjacent convex portions 27 of the gear slot 25 or into the concave portion 28 . “Between adjacent convex portions 27” and “concave portion 28” have substantially the same meaning, but as will be described later, two expressions are used in consideration of the difference in interpretation of convex portions 27 and concave portions 28. Also listed. At this time, rotation of the steering wheel 91 is mechanically restricted.

Further, when the locking device 20 is unlocked, the control unit 30 moves the lock rod 23 backward from the state where it is fitted between the adjacent convex portions 27 of the gear slot 25 or into the concave portion 28 . As the lock rod 23 moves backward and separates from the gear slot 25, the steering wheel 91 becomes freely rotatable.

With reference to FIG. 10, the interpretation of the convex portion 27 and the concave portion 28 will be explained. In this specification, from a perspective based on the small virtual circle φi that connects the outer periphery of the base cylinder portion 29, the convex portion 27 is expressed as “relatively projecting in the radial direction from the small virtual circle φi” and “the small virtual circle φi” is used as a reference point. The concave portion 28 formed along the virtual circle φi is relatively concave in the radial direction. In this case, the circumferential side wall 275 connecting the convex portion 27 and the concave portion 28 is considered to be an outer wall of the convex portion 27 . This view will basically be adopted below.

On the other hand, when viewed based on the large imaginary circle φo that connects the radial outer wall 274 of the convex portion 27, it is expressed as ``the recess 28 is recessed in the radial direction relative to the large imaginary circle φo,'' and ``the large imaginary circle It can also be expressed as "the protrusion 27 formed along φo relatively protrudes in the radial direction". In this case, the circumferential side wall 275 connecting the convex portion 27 and the concave portion 28 is considered to be the inner wall of the concave portion 28 .

In this way, generally speaking, the gear-shaped convex portion 27 and the concave portion 28 can be interpreted relative to each other in terms of their radial positional relationship. In interpreting this embodiment, it shall be interpreted not only based on expressions directly used in this specification but also expressions that may be used when viewed from a different perspective.

Next, with reference to FIGS. 11 and 12, problems and solutions in the operation of the locking device 20 having the above configuration will be described. As shown in FIG. 11(a), during locking, depending on the timing at which the lock rod 23 moves forward, the lock rod 23 comes into contact with the radial outer wall 274 of the convex portion 27 and is not fitted into the recess 28, so that the steering lock is not executed. there is a possibility.

Therefore, as shown in FIG. 11(b), the control unit 30 swings the gear slot 25 by swinging the EPS motor 800 in the forward rotation direction and the reverse rotation direction, thereby changing the position of the lock rod 23 and the recess 28. Together they lead to a locked state. That is, the control unit 30 simultaneously operates the EPS motor 800 and the lock motor 710 so as to support the locking operation of the locking device 20 by rotating the steering wheel. The range in which the control unit 30 swings the EPS motor 800 during the locking operation is set to an angular range that is equal to or larger than the gear pitch Δθgr of the gear slot 25. Thereby, the locking operation is reliably performed regardless of the initial position of the gear slot 25.

Further, as shown in FIG. 12(a), for example, when the vehicle is parked with the wheels 99 twisted, torque is transmitted to the gear slot 25 due to the restoring force received from the road surface, and the torque is transmitted from the circumferential side wall 275 of the convex portion 27 to the lock rod 23. There may be a case where a pressing force F is applied. Then, when the lock is released, the lock rod 23 cannot be moved back due to the frictional force.

Therefore, as shown in FIG. 12(b), the control unit 30 rotates the EPS motor 800 in a retracting direction in which the gear slot 25 moves away from the lock rod 23, thereby causing the circumferential side wall 275 of the convex portion 27 to This releases the contact state with the lock and leads to the unlocked state. In other words, the control unit 30 simultaneously operates the EPS motor 800 and the lock motor 710 so as to support the unlock operation of the lock device 20 by rotating the steering wheel. Here, the control unit 30 needs to determine the retraction direction depending on which side of the circumferential side wall 275 of the convex portion 27 the lock rod 23 is in contact with. A method for determining the retraction direction will be described later with reference to FIGS. 17 and 18.

[sequence]
Next, with reference to FIGS. 13 and 14, a sequence regarding steering lock release when the engine is started and steering lock when the engine is stopped will be described. The symbol "S" in the flowchart indicates a step. In the description of the sequence, the description of the symbols of each motor, control unit, etc. will be omitted. Note that the engine ECU, which is the main body of S16 and S26, is not shown.

The engine starting sequence shown in FIG. 13 starts with generation of a start signal based on turning on an IG signal or a wake-up signal. A microcomputer startup sequence is executed in S011, and a microcomputer/ASIC startup sequence is executed in S012. After this, for example, a latch signal of a latch circuit may be turned on to start a self-holding state.

In S02, as an input circuit check (1), it is confirmed whether the power relay can be turned on. In S03, the ASIC shutdown function is checked. In S04, the remaining checks regarding the input circuit are performed as input circuit check (2). In S05, the circuit of the EPS motor is checked, and in S06, the circuit of the lock motor is checked. After each check, in S08, the control unit starts PWM driving and waits for the EPS to start assisting.

The control unit rotates the EPS motor in a retracting manner in S11, and when the unlockable state is reached, the control unit drives the lock motor in the backward direction in S12. If it is determined in S13 that the lock has been released, the control unit stops driving the lock motor in S14. In S16, the engine ECU starts the engine based on the communication information from the EPS-ECU.

The engine stop sequence shown in FIG. 14 starts with generation of a stop signal based on IG signal OFF or the like. The control unit swings the EPS motor in S21 and simultaneously drives the lock motor in the forward direction in S22. If it is determined in S23 that locking is completed, the control unit stops driving the lock motor in S24.

In S25, the control unit stops EPS assist. At this time, the control unit sets the current command for energizing the EPS motor to zero. Legs other than shared legs may stop PWM driving and stand by for calculation. That is, the system waits until the start signal is turned on, the IG is turned on, or the EPS-ECU or motor cools down. In S26, the engine ECU stops the engine based on the communication information from the EPS-ECU.

[Operation time chart]
Next, detailed operations of the EPS motor 800 and the lock motor 710 during locking and unlocking will be described with reference to FIGS. 15 to 18. Also in the explanation of the time chart, the description of the symbols of each motor, control section, etc. will be omitted.

FIGS. 15 and 16 show two patterns of rocking motion during locking, with different means for determining whether locking is complete. In the operation example shown in FIG. 15, the lock motor current is used for lock completion determination. The vertical axis of FIG. 15 shows changes in EPS motor ON/OFF, lock motor ON/OFF, EPS motor rotational position, lock rod position, and lock motor current. Regarding the rotational position of the EPS motor, the rotational position corresponding to the initial steering position at the time of locking is set as the center of oscillation θc, the maximum position on the forward rotation side is θmax, and the minimum position on the reverse rotation side is θmin. The angular range from the minimum position θmin to the maximum position θmax is set to be greater than or equal to the gear pitch Δθgr of the gear slot 25. Regarding the lock rod position, the backward limit corresponds to the release position, and the forward limit corresponds to the lock position.

At the initial stage of locking, the EPS motor is at the swing center θc, and the lock motor is at the release position. At time t1, the EPS motor is turned on in one of the rotation directions (in the example of FIG. 15, the normal rotation direction), and the lock motor is turned on in the normal rotation (forward) direction. The lock rod 23 moves forward toward the gear slot 25, and at time t2, its tip collides with the circumferential outer wall 275 of the convex portion 27 and stops. During the period T1 from time t1 to time t2, the lock motor operates under low load, so a relatively small moving current Ia flows. When the lock rod 23 comes into contact with the gear slot 25 at time t2, a high load state occurs in which forward movement is blocked, and a relatively large block current Ib flows.

In the example of FIG. 15, there is no point where the lock rod 23 can fit into the recess 28 in the range from the swing center θc to the maximum position on the normal rotation side θmax. Therefore, the control unit switches the EPS motor from normal rotation to reverse rotation at time t3. Then, at time t4 when the EPS motor rotational position exceeds the swing center θc toward the minimum position θmin, the tip of the lock rod 23 separates from the circumferential outer wall 275 of the convex portion 27, and the lock rod 23 can move forward. When the lock rod 23 reaches the lock position at time t5, locking is completed.

During the period T2 from time t4 to time t5, the lock motor operates under low load, so a relatively small moving current Ia flows. The control unit integrates the time during which the moving current Ia flows, and determines that the lock rod 23 has moved a predetermined distance and locking has been completed when the total value (T1+T2) becomes equal to or greater than the determination value. At time t6 when the determination calculation is completed, the control unit stops driving the EPS motor and the lock motor. Note that when the lock rod 23 fits into the recess 28 at the initial rotational position, the integral of the time during which the moving current Ia flows reaches the total value only during the first period T1, and it is determined that the lock is completed.

In the operation example shown in FIG. 16, the sensor signal of the lock rod position sensor is used for lock completion determination. At the bottom of the vertical axis in FIG. 16, a lock rod position sensor signal is shown instead of the lock motor current in FIG. 15. The behavior before time t5 is the same as that shown in FIG. 15. When the lock rod 23 reaches the lock position at time t5, the position sensor signal is turned on and the control section stops driving the EPS motor and the lock motor.

FIGS. 17 and 18 show two patterns with different means for determining the retraction direction regarding the retraction rotation operation at the time of unlocking. In the operation example shown in FIG. 17, the retraction direction is determined based on the increase or decrease in the absolute value of the torque sensor value during temporary rotation. The vertical axis of FIG. 17 shows changes in the torque sensor value, EPS motor ON/OFF, lock motor ON/OFF, and lock rod position. At this time, the torque sensor value represents the torque transmitted to the gear slot 25 of the lock device 20 via the steering rack 97 and the steering shaft 92 due to the restoring force that the wheel 99 receives from the road surface.

As the absolute value of the torque sensor value becomes larger, as shown in FIG. 12A, the pressing force F with which the circumferential side wall 275 of the convex portion 27 of the gear slot 25 presses against the lock rod 23 increases, and unlocking becomes more difficult. Therefore, the control unit first determines, regarding the rotational direction of the EPS motor, the direction in which the torque due to the gear slot 25 pressing the lock rod 23 decreases as the retraction direction. Then, the control unit performs torque control so that the absolute value of the torque sensor value falls within the range of unlockable torque values, and causes the EPS motor to rotate in a retracting manner.

During the lock release operation, the control unit temporarily rotates the EPS motor at time t7 and evaluates an increase or decrease in the absolute value of the torque sensor value. Note that the control algorithm for temporary rotational drive is shown in FIG. 20. In the example shown in Fig. 17, when the EPS motor is tentatively rotated in the forward rotation direction, the absolute value of the torque sensor value increases, so the forward rotation direction is an inappropriate direction that increases the pressing force, and the retraction direction is the reverse direction. It is determined that If the absolute value of the torque sensor value decreases when the EPS motor is tentatively rotated in the normal rotation direction, it is determined that the retraction direction is the normal rotation direction.

When the retraction direction is determined, the control unit starts driving the EPS motor in the reverse direction by torque control at time t8. Note that the control algorithm for torque control will be described later with reference to FIGS. 19 to 21. Due to the retraction rotation, the pressing force with which the circumferential side wall 275 of the convex portion 27 of the gear slot 25 presses the lock rod 23 gradually decreases. Along with this, the absolute value of the torque sensor value approaches zero.

When the absolute value of the torque sensor value becomes approximately 0 at time t9, the control section turns on the lock motor in the reverse (reverse) direction. As a result, the lock rod 23 starts moving backward. Note that driving of the lock motor may be started at a time t9 when the absolute value of the torque sensor value falls below the upper limit of the unlockable torque range. At time t10, when the movement time Tm of the lock rod 23 has elapsed from time t9, the control unit stops driving the lock motor and the EPS motor. Alternatively, the control unit may first stop driving only the EPS motor at the timing when the lock rod 23 comes out of the recess 28, as shown by the broken line.

In the operation example shown in FIG. 18, the steering position information is used to determine the retreat direction. The top row of the vertical axis in FIG. 18 shows the steering position. Assuming that the steering position and the rotational position of the gear slot 25 are correlated, it can be determined from the steering position which circumferential side wall 275 of the convex portion 27 the lock rod 23 is in contact with. Therefore, the control unit determines the retreat direction from the initial steering position information. In the example of FIG. 18, the control unit determines that the retraction direction is the reverse direction, and starts driving the EPS motor in the reverse direction by torque control at time t8. After that, the process is the same as that in FIG.

[EPS motor swing and retraction rotation control algorithm]
Next, with reference to FIGS. 19 to 25, a plurality of embodiments will be described regarding control algorithms for performing rocking of the EPS motor 800 when locking and retraction rotation of the EPS motor 800 when releasing the lock. For the reference numeral of the control unit of each embodiment, the third digit following "30" is assigned the number of the embodiment. These control algorithms are executed in S11 of the flowchart of FIG. 13 and S21 of the flowchart of FIG. 14, and may be different from normal control during EPS assist. Further, for example, the second to fifth embodiments may be used for driving when locking, and the first embodiment may be used for driving when unlocking.

As described above, the EPS motor 800 is a three-phase motor that rotates with a three-phase AC voltage applied to one or more three-phase winding sets 801 and 802 and outputs torque. Except for FIG. 21, a circuit configuration of one system shown in FIG. 5 is assumed as the EPS motor 800 to be driven. The output gate signal is input to each gate of inverter switching elements IUH/L, IVH/L, and IWH/L of one system of three-phase inverter circuit 68.

(First embodiment: Torque control)
The control unit 301 of the first embodiment shown in FIG. 19 performs torque control using the torque sensor value T_sns regarding the torque acting on the gear slot 25. The control unit 301 includes a torque deviation calculator 31, a torque controller 32, and a gain multiplier 39 as common components during locking and unlocking. In addition, the control section 301 includes a retraction direction determining section 33 and a rotation direction switching device 34 as a configuration for unlocking. The configuration when the lock is released will be described later with reference to FIG. 20.

The torque deviation calculator 31 calculates a torque deviation ΔT between the torque command T ^* and the feedback torque sensor value T_sns. The torque controller 32 performs control calculations so that the torque deviation ΔT approaches 0, in other words, the torque sensor value T_sns follows the torque command T ^* . When locked, the gain multiplier 39 multiplies the output of the torque controller 32 by a gain (1/Kt) to calculate the q-axis current command Iq ^* _0 before limitation. When the lock is released, the output of the torque controller 32 is input to the gain multiplier 39 via the rotation direction switch 34.

The control unit 301 also includes a q-axis current limiter 42, a q-axis current deviation calculator 43, a q-axis current controller 44, a d-axis current deviation calculator 45, a d-axis current controller 46, and a dq/three-phase converter 47. , a neutral point voltage operating section 48 and a PWM modulator 49. The q-axis current limiter 42 limits the absolute value of the q-axis current command Iq ^* _0 before limitation, which is the "current command related to energization to the three-phase winding set 801," to be equal to or less than the current limit value, Outputs the limited q-axis current command Iq ^* . In the figure, the block of the q-axis current limiter 42 shows a current limit map symmetrical to the origin, with the horizontal axis as input and the vertical axis as output.

The q-axis current deviation calculator 43 calculates a q-axis current deviation ΔIq between the limited q-axis current command Iq ^* and the fed-back q-axis current Iq. The q-axis current controller 44 calculates the q-axis voltage command ^Vq* so that the q-axis current deviation ΔIq approaches 0, in other words, so that the q-axis current Iq follows the q-axis current command Iq ^* . The d-axis current deviation calculator 45 calculates a d-axis current deviation ΔId between the d-axis current command Id ^* and the fed-back d-axis current Id. The d-axis current controller 46 calculates the d-axis voltage command ^Vd* so that the d-axis current deviation ΔId approaches 0, in other words, so that the d-axis current Id follows the d-axis current command Id ^* .

The dq/three-phase converter 47 coordinately transforms the dq-axis voltage commands Vq ^* , Vd ^* into three-phase voltage commands Vu ^* , Vv ^* , Vw ^* . Note that illustration of the motor position (θ) signal input to the dq/three-phase conversion unit 47 for coordinate conversion calculation is omitted. The neutral point voltage operation unit 48 operates the neutral point voltage using the offset voltage Vm ^* so that the U-phase voltage command Vu ^* with which the legs are shared is kept constant. The PWM modulator 49 performs PWM modulation on the three-phase voltage command after the neutral point voltage operation, and generates a gate signal.

FIG. 20 shows a control algorithm for temporary rotational drive for determining the retracting direction at the time of unlocking. The significance of the provisional rotation drive is as described above with reference to the operation time chart of FIG. In the provisional rotation drive, a pulse torque command for rotating the EPS motor 800 in forward and reverse directions for a minute period of time is input to the gain multiplier 39, and the subsequent configuration is the same as that in FIG. 19. The retraction direction determination unit 33, which is the configuration at the time of unlocking in FIG. 19, determines the retraction direction based on the increase or decrease in the absolute value of the torque sensor value T_sns during the temporary rotation. The rotation direction switch 34 multiplies the output of the torque controller 32 by "1" for forward rotation and "-1" for reverse rotation, depending on the determined retraction direction, and outputs the result to the gain multiplier 39.

FIG. 21 shows a torque control algorithm during locking when the EPS motor 800 with a two-system configuration (see FIG. 6) is driven. In the first system and the second system, blocks from the q-axis current limiter 42 to the PWM modulator 49 are provided redundantly. However, the neutral point voltage operation section 48 is not provided in the second system. Regarding the symbols of current and voltage, "1" at the end indicates the value of the first system, and "2" indicates the value of the second system.

The pre-limited q-axis current command Iq ^* _0 is input to the q-axis current limiter 42 of each system, and the post-limited q-axis current commands Iq1 ^* , Iq2 ^* of each system are output. Three-phase voltage commands Vu1 ^* , Vv1 ^* , Vw1 ^* and Vu2 ^* , Vv2 ^{* ,} Vw2 ^* are calculated for the q-axis current commands Iq1 *, Iq2 ^* by current control and coordinate conversion calculation for each system. In the following second to fifth embodiments, the two-system drive control algorithm is configured similarly.

(Second and third embodiments: position control, speed control)
The control unit 302 of the second embodiment shown in FIG. 22 performs position control to control the rotational position of the EPS motor 800. The control unit 302 includes a position deviation calculator 35, a position controller 36, a speed deviation calculator 37, and a speed controller 38 in place of the torque deviation calculator 31 and torque controller 32 of the control unit 301 of the first embodiment. Be prepared. In this configuration, a position sensor for detecting the motor position θ and a differentiator for calculating the motor speed ω by differentiating the detected motor position θ with respect to time are provided, but illustration thereof is omitted. The motor speed ω uses the same symbol as the rotation speed ω described above.

The positional deviation calculator 35 calculates a positional deviation Δθ between the motor position command θ ^* and the fed-back motor position θ. The position controller 36 calculates the motor speed command ω ^* so that the position deviation Δθ approaches 0, in other words, so that the motor position θ follows the motor position command θ ^* .

The speed deviation calculator 37 calculates a speed deviation Δω between the motor speed command ω ^* and the fed-back motor speed ω. The speed controller 38 calculates the torque command T ^* so that the speed deviation Δω approaches 0, in other words, so that the motor speed ω follows the motor speed command ω ^* . The control unit 303 of the third embodiment shown in FIG. 23 performs speed control to control the rotation speed of the EPS motor 800. The control unit 303 has a configuration after the calculation of the motor speed command ω ^* in the control unit 302 of the second embodiment, and calculates the torque command T ^* by speed control.

The configuration after calculation of the torque command T ^* according to the second and third embodiments is the same as that of the control section 301 of the first embodiment. The absolute value of the q-axis current command Iq ^* _0 before limitation is limited by the q-axis current limiter 42, and the q-axis current command Iq ^* after limitation is input to the q-axis current deviation calculator 43. The q-axis current controller 44 calculates the q-axis voltage command Vq ^* so that the q-axis current Iq follows the limited q-axis current command Iq ^* .

(Fourth embodiment: current control)
The control unit 304 of the fourth embodiment shown in FIG. 24 performs current control to control the current related to the torque of the EPS motor 800 (that is, the q-axis current). The control unit 304 includes a configuration subsequent to the q-axis current limiting unit 42 in contrast to the control unit 301 of the first embodiment. The q-axis current controller 44 calculates the q-axis voltage command Vq ^* so that the fed-back q-axis current Iq follows the q-axis current command Iq ^* . In this configuration, the q-axis current command Iq ^* has already been calculated to be equal to or less than the current limit value, so the q-axis current limiter 42 is not necessary.

(Fifth embodiment: voltage control)
The control unit 305 of the fifth embodiment shown in FIG. 25 performs voltage control to command the three-phase AC voltage applied to the three-phase winding set 801. The control unit 305 includes a neutral point voltage operation unit 48 and a PWM modulator 49, and directly issues three-phase voltage commands Vu ^* , Vv ^* , and Vw ^* . For example, when varying the frequency f of three-phase alternating current, "V/f control" may be performed in which the ratio between the output voltage V and the frequency f is kept constant. Although not shown in FIG. 25, the current value converted from the voltage command may be limited to a limit value or less.

[Effects of this embodiment]
In this embodiment, the three-phase inverter circuit 68 that energizes the EPS motor 800 and the H-bridge circuit 67 that energizes the lock motor 710 are connected to one phase leg of the three-phase inverter circuit 68 and one leg of the H-bridge circuit 67. This constitutes an integrated power conversion circuit 60 that shares the following. Therefore, it is possible to downsize a power conversion circuit that drives a plurality of motors.

Further, in the circuit topology of this embodiment, the integrated power conversion circuit 60 is operated by the common control unit 30, and the EPS motor 800 and the lock motor 710 can be operated simultaneously. Therefore, if the lock rod 23 cannot fit into the recess 28 due to the rotational position of the gear slot 25 during locking, the locking operation can be supported by swinging the EPS motor 800. Alternatively, if the lock rod 23 cannot be moved back due to the pressing force of the gear slot 25 at the time of unlocking, the unlocking operation can be supported by rotating the EPS motor 800 in a retracting manner. In this manner, in this embodiment, it is possible to achieve both miniaturization of the power conversion circuit and smooth operation of the steering lock mechanism.

(Other embodiments)
(a) FIG. 26 shows a rack type EPS system 901RC corresponding to a modification of FIG. 2. In the EPS system 901RC of FIG. 26, the EPS motor 800 and the torque sensor 94 are arranged at 97 on the steering rack similarly to the EPS system 901R of FIG. On the other hand, the locking device 20 is arranged on the steering column 93.

(b) The EPS motor 800 is not limited to a multi-phase motor such as a three-phase motor, and may be configured with a DC motor or an electric actuator other than a motor. Similarly, the lock motor 710 is not limited to a DC motor, and may be configured with an electric actuator other than a motor, such as a linear cylinder.

(c) A three-phase motor relay or a DC motor relay may be added to the one-system or two-system circuit configuration shown in FIGS. 5 and 6, or an LC filter circuit may be added to the input section. The first circuit and the second circuit may not be connected to a common power source Bt, but may be connected to separate power sources. Further, a DC motor other than the lock motor 710 may be connected to the same phase as the lock motor 710, a different phase of the same system as the lock motor 710, or one or more phases of another system.

(d) The locked body 25 constituting the locking device 20 is not limited to a "rotationally symmetrical gear slot" in which a plurality of convex portions 27 and a plurality of concave portions 28 are arranged at equal intervals in the circumferential direction. For example, it may be a non-rotationally symmetrical gear slot in which the gear pitch differs depending on the circumferential position. Alternatively, it may have a shape in which one convex portion 27 and one concave portion 28 are arranged in the circumferential direction, that is, a shape in which the lock rod 23 can be fitted in only one range out of 360 degrees.

(e) The relative arrangement of the lock motor 710 and the movable part 21 of the lock device 20 and the configuration regarding power transmission are not limited to those illustrated in FIGS. 8 and 9. For example, the motor output shaft of the lock motor 710 and the axis of the movable part 21 of the lock device 20 may be arranged in parallel, and the power may be transmitted by a parallel gear. Alternatively, when the lock motor 710 is configured with a linear actuator, the reciprocating motion output shaft of the lock motor 710 may be directly connected to the shaft of the movable part 21.

(f) The relative arrangement of the lock rod 23 of the movable part 21 and the rotation axis O of the locked body 25 is not limited to that illustrated in FIG. 8 . For example, the axis of the movable part 21 and the rotation axis O of the locked body 25 may be arranged in parallel, and the lock rod 23 may be fitted into the recess 28 from the axial direction to be in the locked state.

(g) The method of determining whether locking is complete at the time of locking is not limited to the method illustrated in FIGS. 15 and 16. For example, if the EPS motor 800 is oscillated in the range from the minimum position θmin to the maximum position θmax as shown by the two-dot chain line in FIGS. 15 and 16, it may be considered that the lock is inevitably completed. .

(h) The method of determining the retraction direction upon unlocking is not limited to the method illustrated in FIGS. 17 and 18. For example, the stress applied to the lock rod 23 may be detected by a strain sensor or the like, and the direction of the pressing force may be determined.

The present invention is not limited to such embodiments, and can be implemented in various forms without departing from the spirit thereof.

The control unit and the method described in the present disclosure are implemented by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. may be done. Alternatively, the controller and techniques described in this disclosure may be implemented by a dedicated computer provided by a processor configured with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described in the present disclosure may be implemented using a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. It may be implemented by one or more dedicated computers configured. The computer program may also be stored as instructions executed by a computer on a computer-readable non-transitory tangible storage medium.

10...ECU (steering control device),
20...Lock device,
30 (301-305)...control unit,
67...H bridge circuit (second circuit),
68 (681, 682)... three-phase inverter circuit (first circuit),
710...lock actuator,
800... Steering assist motor (steering assist actuator),
91...Steering wheel (steering).

Claims (11)

a first circuit (68, 681, 682) that is a power conversion circuit that energizes a steering assist actuator (800) that electrically assists the driver's steering;
A second circuit (67) that is a power conversion circuit that energizes a lock actuator (710) that drives a locking device (20) that mechanically restricts the rotation of the steering wheel (91) to perform a locking or unlocking operation. and,
a control unit (30) that operates the first circuit and the second circuit to control operations of the steering assist actuator and the lock actuator;
A steering control device comprising:
The first circuit and the second circuit are provided in the same housing (600), and the first circuit and the second circuit have a set of high potential side and low potential side connected in series. If the potential side switching element is a leg, the first circuit and the second circuit form an integrated power conversion circuit (60) that shares one leg,
The control unit is a steering control device that simultaneously operates the steering assist actuator and the lock actuator so that rotation of the steering wheel supports a locking operation or an unlocking operation of the locking device. The steering assist actuator and the lock actuator are motors,
The steering control device according to claim 1, wherein the control unit applies a voltage to the steering assist actuator and the lock actuator and supplies current to the steering assist actuator and the lock actuator. The locking device includes:
a lock rod (23) that is reciprocated by the lock actuator;
One or more convex portions (27) relatively protruding in the radial direction and one or more concave portions (28) relatively concave in the radial direction are arranged in the circumferential direction and rotate following the steering wheel. It has a locked body (25),
The control unit includes:
When locking the locking device, the lock rod is moved forward to fit between the adjacent convex portions of the locked object or into the concave portion,
3. The steering control device according to claim 1, wherein when the locking device is operated to unlock, the lock rod is moved back from a state where it is inserted between the adjacent convex portions of the locked object or from a state where it is fitted into the recessed portion. The control unit includes:
When locking the locking device, the steering assist actuator is oscillated in a forward rotation direction and a reverse rotation direction;
4. The steering control device according to claim 3, wherein when the locking device is unlocked, the steering assist actuator is rotated in a retracting direction in which the locked object moves away from the lock rod. The locked body is configured as a gear slot in which a plurality of the convex portions and a plurality of the concave portions are arranged at equal intervals in the circumferential direction,
The steering control device according to claim 4, wherein the range in which the control section swings the steering assist actuator during the locking operation is set to an angular range that is equal to or larger than the gear pitch of the gear slot. The steering assist actuator is a polyphase motor that rotates by a polyphase AC voltage applied to one or more polyphase winding sets (801, 802) and outputs torque,
The control unit includes:
Torque control using a torque sensor value regarding the torque acting on the locked object;
position control for controlling the rotational position of the polyphase motor;
speed control for controlling the rotational speed of the polyphase motor;
current control that controls the current related to the torque of the polyphase motor, or
voltage control for commanding a multiphase AC voltage applied to the multiphase winding set;
The steering control device according to claim 4 or 5, wherein the operation of the polyphase motor is controlled by one of the above. The control unit performs torque control using the torque sensor value,
When the locking device is operated to unlock,
The control unit determines, with respect to the rotational direction of the steering assist actuator, a direction in which torque decreases due to the locked object pressing the lock rod as the retraction direction, and determines that the absolute value of the torque sensor value is locked. The steering control device according to claim 6, wherein the steering assist actuator is retracted and rotated by performing torque control so that the torque value falls within a range of torque values that can be released. The control unit performs any one of the torque control, the position control, the speed control, or the voltage control using the torque sensor value,
8. The steering control device according to claim 6, wherein the absolute value of a current command related to energization of the polyphase winding set is limited to a current limit value or less. The steering control device according to any one of claims 1 to 8, wherein the steering assist actuator and the locking device are both arranged on a steering column (93). The steering control device according to any one of claims 1 to 8, wherein the steering assist actuator and the locking device are both arranged in a steering rack (97). The steering control device according to any one of claims 1 to 8, wherein the steering assist actuator is arranged on a steering rack (97) and the locking device is arranged on a steering column (93).

Images