JP2009078741A - Controller for steering apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller for steering apparatus capable of reducing load on main power supply by utilizing auxiliary power supply effectively. <P>SOLUTION: This controller for steering apparatus includes a the main power supply 4 for supplying electric power to a motor 1m of the steering apparatus 1s of a vehicle, the auxiliary power supply 9 for supplying electric power to the motor 1m, and a control circuit 15 for controlling supply of electric power to the motor 1m by the auxiliary power supply 9 based on an electric power value set as a charging and discharging threshold value. The control circuit 15 is constituted to monitor electric power consumption of the motor when parking the vehicle and change the charging and discharging threshold value based on the electric power consumption of the motor. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control device for a steering device. More specifically, the present invention relates to a control device in a steering device that uses the driving force of an electric motor.

  An electric power steering device mounted on a vehicle such as an automobile needs to pass a larger current through the motor as the required steering assist force is larger. Therefore, power is usually supplied to the motor from the in-vehicle battery, which is the main power source. However, when the terminal voltage of the main power source decreases due to an increase in load such as when entering the garage or parking, the auxiliary power previously stored is stored A configuration has been proposed in which power is supplied from a power source to reduce the burden on the main power source (see, for example, Patent Documents 1 and 2).

JP 2003-320942 A JP 2005-287222 A

  In the apparatus provided with the auxiliary power source described above, it is conceivable to determine whether or not the auxiliary power source is used according to the value of electric power required by the motor for assisting steering. Specifically, a threshold value (charge / discharge threshold value) is set in advance, and if the power value is smaller than the charge / discharge threshold value, only the main power source bears the necessary power, while the power value is When it is larger than the charge / discharge threshold, the auxiliary power supply bears necessary power in addition to the main power supply.

  By the way, the amount of energy borne by the auxiliary power source is determined by the integrated value of the electric power exceeding the charge / discharge threshold, but the auxiliary power source has a certain margin in order to prevent the steering performance from deteriorating due to insufficient assist force. It has a capacity. That is, the capacity of the auxiliary power source is set on the basis of the power consumed by a driver unfamiliar with driving at the time of parking that needs the assistance of the auxiliary power source.

  However, since the capacity of the auxiliary power supply is a capacity that allows for the worst condition or a condition close to it, it is an over-specification, that is, an excessive capacity for most drivers. Therefore, for such a driver, even if the charge / discharge threshold is lowered, there is no shortage of power, and since the frequency of use of the auxiliary power increases as the charge / discharge threshold decreases, the power of the auxiliary power is effectively increased. Can be used. As a result, the burden on the main power supply can be reduced, and a margin can be given to the power supplied to electrical components such as coolers and audio other than the electric power steering device.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a control device for a steering device that can effectively use an auxiliary power source to reduce a burden on a main power source.

A control device for a steering device of the present invention (hereinafter also simply referred to as “control device”) includes a main power source that supplies electric power to a motor of a steering device of a vehicle,
An auxiliary power source capable of supplying power to the motor;
A control circuit for controlling power supply to the motor by the auxiliary power source based on a power value set as a charge / discharge threshold,
The control circuit is configured to monitor motor power consumption when the vehicle is parked, and to change the charge / discharge threshold based on the motor power consumption.

  The control device of the present invention is based on the premise that the power consumption for steering assistance during parking performed by reversing the vehicle is the maximum power consumption for steering assistance. The motor power consumption is monitored, and the charge / discharge threshold value that determines whether or not to use the auxiliary power supply is changed based on the motor power consumption. For example, a driver who is skilled in driving has a smooth operation of the steering wheel during parking, and there is no useless movement of the vehicle, so that the motor consumes less electric power to assist steering. Therefore, even if the charge / discharge threshold is lowered and the use of the auxiliary power supply is started from an early stage (a stage where the motor power consumption is low), the total power consumption is originally low, so that there is no power shortage. Since the use frequency of the auxiliary power source increases as the charge / discharge threshold decreases, the power of the auxiliary power source can be used effectively. As a result, the burden on the main power supply can be reduced, and a margin can be given to the power supplied to the electrical components other than the electric power steering device.

  In addition, when the driver of the vehicle is replaced, the charged / discharge threshold value that has been lowered can be increased based on the monitored motor power consumption, and the charge / discharge threshold value can be set according to the driver.

  The control circuit may be configured to store the monitored motor power consumption as the maximum power, and to lower the charge / discharge threshold by a predetermined value when the maximum power is smaller than the set assumed maximum power. In this case, for a driver with low motor power consumption during parking, the charge / discharge threshold can be lowered to increase the frequency of use of the auxiliary power supply, and as a result, the power of the auxiliary power supply can be used effectively.

  The control circuit may be configured to store the monitored motor power consumption as the maximum power, and to increase the charge / discharge threshold by a predetermined value when the maximum power is larger than the set assumed maximum power. According to this configuration, for example, when the driver who drives the vehicle is changed, the charge / discharge threshold that has been lowered can be raised based on the monitored motor power consumption, and the charge / discharge threshold corresponding to the driver is set. be able to. In this specification, “assumed maximum power” refers to not only motor power consumption for steering assistance, which is set in advance for a driver who is unfamiliar with driving and is considered to be necessary during parking, but is also monitored. Also included is power that is newly stored as the assumed maximum power instead of the assumed maximum power that has been previously stored (set).

  The control circuit is preferably configured to update the maximum power as an assumed maximum power. Thereby, it becomes possible to always change the charge / discharge threshold according to the monitored motor power consumption.

  According to the control device of the present invention, the burden on the main power source can be reduced by effectively using the auxiliary power source.

Hereinafter, embodiments of a control device of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a circuit diagram of a control device 2 of an electric power steering device 1 according to an embodiment of the present invention. In the figure, a steering assist force is applied to a vehicle steering device 1s by a motor 1m. More specifically, the motor 1m is driven and controlled according to the output (steering torque) of a torque sensor such as a torsion bar type attached to a steering shaft (not shown) of the steering device 1s, and the steering shaft or steering gear (rack) Assist to pinion, rack shaft, etc. The motor drive circuit 3 supplies power to the motor 1m.

  The main power supply 4 is composed of an in-vehicle battery 4b and an alternator 4a, and a diode 6 is provided in the middle of a non-grounded electric circuit 5 that guides the main power supply 4 to the motor drive circuit 3. . A smoothing electrolytic capacitor 8 is provided between the cathode of the diode 6 and the ground side electric circuit 7.

  On the other hand, the auxiliary power source 9 is composed of an electric double layer capacitor (capacitor) and is connected in series to the main power source 4. In addition to the electric double layer capacitor (capacitor), a secondary battery such as a lithium ion battery or a nickel cadmium battery, or a capacitor can be used as the auxiliary power source.

  A power feeding circuit (high potential side circuit) 10 of the auxiliary power source 9 is connected to the motor driving circuit 3 via a discharge control circuit 11. The discharge control circuit 11 includes a MOS-FET 11a and a PWM voltage source 11b. The discharge current can be controlled by PWM controlling the gate voltage. The anode of the diode 13 is connected to the low potential side of the auxiliary power supply 9 via the reactor 12, and the cathode of the diode 13 is connected to the power supply circuit 10 of the auxiliary power supply 9. In addition, a MOS-FET 14 is provided between the anode of the diode 13 and the ground-side electric circuit 7. The protective diode 14d is connected in parallel to or built in the MOS-FET 14. The gate of the MOS-FET 14 is driven by the gate drive circuit 20.

  A current detector 31 that detects a discharge current from the auxiliary power supply 9 is disposed in the power feeding circuit 10. A voltage detector 32 for detecting the voltage between the terminals of the auxiliary power supply 9 is provided. Each signal from the current detector 31 and the voltage detector 32 is transmitted to the control circuit 15.

  The motor drive circuit 3, the discharge control circuit 11 and the gate drive circuit 20 operate in response to a command signal from the control circuit 15. The control circuit 15 is supplied with steering torque of the steering wheel by the driver and vehicle speed information from the vehicle speed sensor 33, and the control circuit 15 provides an appropriate steering assist force according to the information. The motor 1m is driven to generate it.

  When the MOS-FET 14 is in the on state, current flows from the alternator 4a through the reactor 12 and the MOS-FET 14, but when the MOS-FET 14 turns off, a high voltage is applied to the reactor so as to prevent magnetic flux change due to current interruption. Thus, the auxiliary power supply 9 is charged with a voltage obtained by boosting the output of the alternator 4a. In this way, the auxiliary power supply 9 can be charged by repeatedly turning on and off the MOS-FET 14.

  In the above configuration, when the required steering assist force is relatively small (when the motor power consumption is smaller than the charge / discharge threshold), the control circuit 15 turns the discharge control circuit 11 off. Therefore, the voltage of the main power supply 4 is smoothed by the smoothing capacitor 8 and then supplied to the motor drive circuit 3. The motor drive circuit 3 drives the motor 1 m based on the control signal from the control circuit 15. On the other hand, the voltage of the auxiliary power supply 9 is not supplied to the motor drive circuit 3.

  Further, when the required steering assist force is relatively large (the motor power consumption is greater than the charge / discharge threshold) and the main power supply 4 alone cannot be used, the control circuit 15 turns on the discharge control circuit 11. . As a result, the current defined by the discharge control circuit 11 is supplied to the motor drive circuit 3 based on the voltage of the main power supply 4 and the auxiliary power supply 9 in series with each other.

  In the present embodiment, the control circuit 15 is configured to monitor the power consumption of the motor 1m when the vehicle is parked and to change the charge / discharge threshold based on the motor power consumption. A driver who is good at driving can operate the steering wheel smoothly when parking, and the vehicle does not move wastefully. Therefore, the motor consumes less power to assist steering. Therefore, even if the charge / discharge threshold is lowered and the use of the auxiliary power supply is started from an early stage (a stage where the motor power consumption is low), the total power consumption is originally low, so that there is no power shortage. Since the use frequency of the auxiliary power source increases as the charge / discharge threshold decreases, the power of the auxiliary power source can be used effectively. As a result, the burden on the main power supply can be reduced, and a margin can be given to the power supplied to the electrical components other than the electric power steering device. In addition, when the driver of the vehicle is replaced, the charge / discharge threshold once lowered can be increased based on the monitored motor power consumption, and the charge / discharge threshold corresponding to the driver can be set.

FIG. 2 is a flowchart showing an example of changing the charge / discharge threshold, and this flowchart is repeatedly executed at regular time intervals.
First, in step S1, the control circuit 15 monitors vehicle speed (vehicle speed), steering speed, and AT (automatic transmission) mode. In step S2, the control circuit 15 determines whether the vehicle speed is 5 km or less, whether the AT mode is reverse, and whether the steering speed is 90 deg / s or more. If the control circuit 15 determines that the vehicle speed is 5 km or less, the AT mode is reverse, and the steering speed is 90 deg / s or more, in step S3, the power consumption of the motor 1m is monitored. On the other hand, if any one of the three determination conditions is “No”, the control circuit 15 advances the process to step S5.

  The three determination conditions are conditions for estimating whether or not the vehicle is performing the parking operation while moving backward. When all three conditions are satisfied, the vehicle performs the parking operation while moving backward. Estimated. Based on the premise that the motor power consumption for steering assistance during parking performed by reversing the vehicle is the maximum power consumption for steering assistance, the motor power consumption during parking of the vehicle is Monitor.

When the motor power consumption is calculated by monitoring, in step S4, the control circuit 15 stores this power consumption as “maximum power” in a storage unit (not shown) included in the control circuit 15.
On the other hand, during normal driving, all three conditions are not satisfied in step S2, and therefore the control circuit 15 proceeds to step S5, and in step S5, the “assumed maximum power” is stored in the storage unit. It is determined whether or not the value obtained by subtracting the “maximum power” is greater than a predetermined value t (t is a positive number).

When the control circuit 15 determines that the value obtained by subtracting the “maximum power” from the “presumed maximum power” is larger than the predetermined value t, in step S6, the control circuit 15 subtracts the predetermined value from the current charge / discharge threshold. Set as a new charge / discharge threshold. This “predetermined value” is a value that varies depending on the difference between the assumed maximum power and the maximum power, and varies depending on the vehicle type, but can be set to, for example, 10 to 30 (W).
Next, in step S7, the control circuit 15 updates the maximum power obtained by monitoring as a new assumed maximum power that replaces the previous assumed maximum power. Thereby, it becomes possible to always change the charge / discharge threshold according to the monitored motor power consumption.

  If “No” in step S5, the control circuit 15 determines that the value obtained by subtracting “estimated maximum power” from “maximum power” stored in the storage unit in step S8 is a predetermined value t (t is a positive number). ) Is determined. When the control circuit 15 determines that the value obtained by subtracting the “estimated maximum power” from the “maximum power” is larger than the predetermined value t, in step S9, a value obtained by adding the predetermined value to the current charge / discharge threshold is newly set. Set as charge / discharge threshold. Also in this case, in step S7, the control circuit 15 updates the maximum power obtained by monitoring as a new assumed maximum power that replaces the previous assumed maximum power.

  Note that the number of auxiliary power supplies is not limited to one, and may be two or more. In this case, a plurality of auxiliary power supplies of the same type may be used, or different types of auxiliary power supplies may be used in combination.

It is a circuit diagram of one embodiment of a control device of the present invention. It is a flowchart which shows the example which changes a charging / discharging threshold value.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric power steering apparatus 1s Steering apparatus 1m Motor 2 Control apparatus 3 Motor drive circuit 4 Main power supply 4a Alternator 4b Car-mounted battery 9 Auxiliary power supply 15 Control circuit 31 Current detector 32 Voltage detector 33 Vehicle speed sensor

Claims (4)

A main power source for supplying electric power to a motor of a vehicle steering device;
An auxiliary power source capable of supplying power to the motor;
A control circuit for controlling power supply to the motor by the auxiliary power source based on a power value set as a charge / discharge threshold,
The control device for a steering apparatus, wherein the control circuit is configured to monitor motor power consumption when the vehicle is parked, and to change the charge / discharge threshold based on the motor power consumption.   The control circuit is configured to store the monitored motor power consumption as a maximum power, and to lower the charge / discharge threshold by a predetermined value when the maximum power is smaller than a set assumed maximum power. The control device for the steering device according to claim 1.   The control circuit is configured to store the monitored motor power consumption as a maximum power, and to increase the charge / discharge threshold by a predetermined value when the maximum power is larger than a set assumed maximum power. The control device for the steering device according to claim 1.   The control device for a steering apparatus according to any one of claims 2 to 3, wherein the control circuit is configured to update the maximum power as an assumed maximum power.

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