JP2002362393A - Control device for electric power steering - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an electric power steering constituted to self-hold a power supply even after the stop of the power supply and to continue temperature estimation so as to be able to continue temperature protection control. SOLUTION: This control device for the electric power steering controls a motor on the basis of a current command value computed from a steering auxiliary command value computed on the basis of steering torque generated to a steering shaft, and the current detected value of a motor for applying steering auxiliary effort to a steering mechanism. The control device is provided with a power self-holding means capable of controlling own power stop after power is inputted, and a temperature estimating means for estimating the temperature of the motor and performing temperature control on the basis of the temperature estimate value. While the temperature estimate value does not become a prescribed value or less even after the input of a power stop signal, the power supply is self-held by the power self-holding means, and steering auxiliary control is suspended, and only the temperature estimation by the temperature estimating means is continued.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an electric power steering apparatus which applies a steering assisting force by a motor to a steering system of an automobile or a vehicle. The present invention relates to a control device for an electric power steering device that continues estimation.

[0002]

2. Description of the Related Art An electric power steering apparatus for energizing a steering apparatus of an automobile or a vehicle with an auxiliary load by the rotational force of a motor transmits a driving force of the motor to a steering shaft by a transmission mechanism such as a gear or a belt through a speed reducer. Alternatively, an auxiliary load is applied to the rack shaft. Such a conventional electric power steering apparatus performs feedback control of a motor current in order to accurately generate an assist torque (a steering assist torque). The feedback control is to adjust the motor applied voltage so that the difference between the current command value and the motor current detected value is small. Generally, the adjustment of the motor applied voltage is performed by PWM (pulse width modulation).
The control is performed by adjusting the duty ratio.

Here, the general structure of an electric power steering apparatus will be described with reference to FIG.
Is connected to a tie rod 6 of a steered wheel via a reduction gear 3, universal joints 4a and 4b, and a pinion rack mechanism 5. The shaft 2 is provided with a torque sensor 10 for detecting a steering torque of the steering wheel 1, and a motor 20 for assisting the steering force of the steering wheel 1 is coupled to the shaft 2 via the reduction gear 3. . The control unit 30 for controlling the power steering device includes:
Power is supplied from the battery 14 via the ignition key 11, and the control unit 30
0 based on the steering torque T detected at 0 and the vehicle speed V detected by the vehicle speed sensor 12.
Is calculated, and the current supplied to the motor 20 is controlled based on the calculated steering assist command value I.

The control unit 30 is mainly composed of a CP
FIG. 5 shows general functions executed by a program inside the CPU.
For example, the phase compensator 31 does not indicate a phase compensator as independent hardware, but indicates a phase compensation function executed by the CPU.

The function and operation of the control unit 30 will be described. The steering torque T detected and input by the torque sensor 10 is phase-compensated by a phase compensator 31 in order to enhance the stability of the steering system. The steering torque TA is input to the steering assist command value calculator 32. Also,
The vehicle speed V detected by the vehicle speed sensor 12 is also input to the steering assist command value calculator 32. The steering assist command value calculator 32 is
Based on the input steering torque TA and vehicle speed V, the motor 2
Steering assist command value I, which is the control target value of the current supplied to 0
To determine. The steering assist command value I is input to a subtractor 30A, and is also input to a feed-forward system differential compensator 34 for increasing the response speed, and the deviation (I-i) of the subtractor 30A is input to a proportional calculator 35. At the same time, it is input to an integration calculator 36 for improving the characteristics of the feedback system. The outputs of the differential compensator 34 and the integral compensator 36 are also added to the adder 30B, and the current control value E, which is the result of the addition in the adder 30B, is input to the motor drive circuit 37 as a motor drive signal.

The motor drive circuit 37 is constituted by an H bridge circuit in which four FETs (field effect transistors) as drive elements are connected in an H-shape. The motor current value i of the motor 20 is detected by the motor current detection circuit 38, and the motor current value i is input to the subtractor 30A and fed back.

[0007] In such an electric power steering apparatus, the motor 20 is not used when the garage is repeatedly stored for a long time.
When the motor 20 is excessively used such that a large current continues to flow, the motor 20 may be overheated, generating smoke, and the motor 20 may be burned. To solve such a problem, it is easy to arrange a temperature sensor on the motor 20 to perform temperature protection control. However, in an electric power steering device for a passenger car, the motor 20 is easily provided due to cost and layout. Temperature sensor cannot be installed on the machine.

For this reason, conventionally, Japanese Patent Application Laid-Open No. 10-10091
As shown in No. 3, the winding temperature of the motor is estimated, and the temperature protection control of the motor is performed based on the estimated temperature.

[0009]

However, the conventional winding temperature estimation has a problem that the relative accuracy is high, but the absolute accuracy is inferior. That is, if the estimation is started once and the estimation is continued as it is, a relatively stable estimation can be performed. However, if the interruption and the resumption are repeated after the estimation is started, there is a problem that the estimation accuracy is significantly deteriorated.

If this is replaced with the actual use situation, the normal steering is performed after the power is turned on, and if the power is stopped after all the operations are completed, the intended temperature protection control is also performed by estimating the temperature. be able to. However, after turning on the power, it performs steering like frequent parking,
The temperature protection control is activated, and in that state, the power is turned off, the power is turned on, and the steering is performed again, such as entering the garage.Then, the temperature protection control is activated. In such a case, there is a problem that the temperature protection control does not work sufficiently.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electric motor capable of holding its power supply even after the power supply is stopped, continuing temperature estimation, and continuing temperature protection control. An object of the present invention is to provide a control device for a power steering device.

[0012]

According to the present invention, there is provided a steering assist command value calculated based on a steering torque generated on a steering shaft, and a current calculated from a current detection value of a motor for applying a steering assist force to a steering mechanism. The present invention relates to a control device of an electric power steering device adapted to control the motor based on a command value, and an object of the present invention is to provide a power supply self-holding means capable of controlling the stop of the power supply after the power is turned on. And a temperature estimating means for estimating the temperature of the motor and performing temperature control based on the temperature estimated value, and the power supply is provided as long as the temperature estimated value does not fall below a predetermined value even when a power supply stop signal is input. This is achieved by self-holding the power supply by the self-holding means, suspending the steering assist control, and continuing only the temperature estimation by the temperature estimation output means. That.

The present invention also provides a steering assist command value calculated based on a steering torque generated on a steering shaft and a current command value calculated from a current detected value of a motor for applying a steering assist force to a steering mechanism. The present invention relates to a control device for an electric power steering device adapted to control the motor via a control unit provided with a drive element. Power control self-holding means that can be controlled, temperature estimating means for estimating the temperature of the motor and performing temperature control with the temperature estimated value, and a temperature sensor for measuring the temperature of the control unit; When input, the measured temperature of the temperature sensor,
The difference between the temperature estimation values is calculated, and while the difference does not fall within a predetermined value, the power is held by the power supply self-holding means, the steering assist control is stopped, and only the temperature estimation by the temperature estimation output means is continued. Is achieved by doing so.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the power supply is self-held until the estimated temperature value becomes a predetermined value or less, the temperature estimation is continued, and the power supply (signal) in the self-powered power supply is turned on again to perform temperature protection control. To be able to continue. For this reason, after turning on the power, steering such as frequent garage entry is performed, and even if the power is repeatedly turned on / off, the temperature protection control can be prevented from becoming incomplete.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. A control unit (ECU) 40 comprising a CPU and the like for performing overall control includes a power supply circuit from a battery 41 via a key switch 42 and a diode D1. (Stabilization circuit) Power is supplied from 43 and relay contact C
Power supply circuit (stabilization circuit) 4 via RA and diode D2
3 is supplied with power. The motor 50 is controlled by the control unit 40 via the driver 51.
The current of the motor 50 is detected by the current detector 52, and the detected current is input to the control unit 40. And
The control unit 40 has an ON / OF key switch 42 via a key switch input interface 44.
The F signal is input, and the relay CR is connected via a transistor 45 as driving means. The relay CR is driven by the control unit 40 via the transistor 45, and according to the drive / cutoff, the contact C of the relay CR
RA is turned on / off.

The power supply self-holding means is constituted by the relay CR, the contact CRA thereof, and the transistor 45, so that once the power supply is turned on, the power supply itself can be stopped. The control unit 40 includes a motor 50.
Temperature estimating means for estimating the temperature of the radiator is provided.

In such a configuration, the operation is shown in FIG.
This will be described with reference to the flowchart of FIG.

First, the entire control system is initialized (step S1), the control unit 40 inputs a steering torque detection signal from a torque sensor (not shown) (step S2), and performs a failure diagnosis based on the steering torque detection signal. (Step S3), input a current detection signal from the current detector 52 (Step S4), perform failure diagnosis based on the current detection signal (Step S5), and calculate a motor control signal based on a predetermined arithmetic expression. Is performed (step S6). Thus, the motor 50 is controlled via the driver 51. At the same time, the temperature estimating means is disclosed in
The motor temperature is estimated by a method as shown in No. -100913 (step S7), and it is determined whether the motor 50 is overheated (step S10). If an overheat occurs, an overheat protection current command value is calculated (step S10). Step S11).

Thereafter, or if it is determined in step S10 that the motor is not overheated, a key switch detection signal is input from the key switch input interface 44 (step S12), and it is determined whether the key switch 42 is OFF. (Step S13), the key switch 42 is turned off
If not F, a motor control signal is output and the motor 50 is driven via the driver 51 (step S14).
The process returns to step S2.

On the other hand, when the OFF of the key switch 42 is detected in step S13, the control unit 40 stops the output of the motor control signal (step S15), and the estimated motor temperature at that time becomes a predetermined value. It is determined whether it is the following (step S16). At this stage, the power supply self-holding means is functioning, that is, the relay CR is driven via the transistor 45, and the contact CRA is ON. Therefore, the power source of the battery 41 is the relay contact CRA, the diode D2 and the power supply circuit 43.
Is supplied to the control unit 40 via When the estimated temperature value of the motor 50 becomes equal to or less than the predetermined value, the relay CR is turned off via the transistor 45.
Then, the power supply from the battery 41 to the control unit 40 is cut off (Step S17), and the control of the electric power steering is stopped (Step S18).

Next, the operation when a temperature sensor for measuring the temperature of the control unit 40 (for example, a drive element (FET or the like)) is provided will be described with reference to the flowchart of FIG.

First, the entire control system is initialized (step S20), the control unit 40 inputs a steering torque detection signal from a torque sensor (not shown) (step S21), and performs a failure diagnosis based on the steering torque detection signal. (Step S22), and then the current detector 52
(Step S23)
A failure diagnosis is performed based on the current detection signal (step S2).
4), a motor control signal is calculated based on a predetermined calculation formula (step S25). Thus, the motor 50 is controlled via the driver 51. At the same time, the temperature estimating means estimates the motor temperature (step S26),
It is determined whether 0 is overheating or not (step S27). If overheating occurs, an overheat protection current command value is calculated (step S2).
8).

Thereafter, or if it is determined in step S27 that the motor is not overheated, the measured temperature from the temperature sensor is input (step S30), and a key switch detection signal is input from the key switch input interface 44 (step S30). S31) It is determined whether or not the key switch 42 is OFF (step S32).
2 is not OFF, a motor control signal is output and the motor 50 is driven via the driver 51 (step S2).
33), and the process returns to step S21.

On the other hand, if the OFF of the key switch 42 is detected in step S32, the control unit 40 stops outputting the motor control signal (step S34), and the motor temperature estimated value and the measurement from the temperature sensor are measured. A difference from the temperature is determined (step S35), and it is determined whether the difference is equal to or less than a predetermined value (step S36). At this stage, the power supply self-holding means is functioning, and the relay CR is driven via the transistor 45, and its contact CRA
Is ON. Therefore, the power of the battery 41 is supplied to the control unit 40 via the relay contact CRA, the diode D2, and the power circuit 43. When the difference is equal to or smaller than a predetermined value, the transistor 45
Then, the relay CR is turned off (step S37), the power supply from the battery 41 to the control unit 40 is cut off, and the control of the electric power steering is stopped (step S38).

The present invention can be applied not only to a column type and a pinion type electric power steering device but also to a rack assist type electric power steering device.

[0027]

According to the present invention, the difference between the temperature estimation value and the measured temperature is equal to or smaller than the predetermined value until the temperature estimation value becomes equal to or less than the predetermined value or when a temperature sensor for measuring the temperature of the control unit is provided. The power is self-held until the value becomes equal to or less than the value, the temperature estimation is continued, and the temperature protection control can be continued by turning on the power (signal) in the self-holding power again. Therefore, it is possible to prevent the temperature protection control from being incomplete due to frequent power ON / OFF.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a flowchart showing an operation example of the present invention.

FIG. 3 is a flowchart showing another operation example of the present invention.

FIG. 4 is a diagram illustrating a configuration example of a general power steering device.

FIG. 5 is a block diagram illustrating a configuration example of a control unit.

[Description of Signs] 1 Steering handle 5 Pinion rack mechanism 20, 50 Motor 30, 40 Control unit 31 Phase compensator 32 Steering assist command value calculator 37 Motor drive circuit 38 Motor current detection circuit 41 Battery 42 Key switch 43 Power supply circuit (Stabilizing circuit) 45 Transistor 51 Driver 52 Current detector

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3D032 CC50 DA15 DA23 DA64 DA67 EC21 3D033 CA13 CA16 CA20 CA28 5H571 AA03 BB07 CC04 EE02 FF06 GG03 GG04 HA09 JJ03 JJ04 KK01 LL01 LL22 LL34 LL50 MM16 MM16 MM14

Claims (4)

[Claims] An electric motor, comprising: a steering assist command value calculated based on a steering torque generated on a steering shaft; and a current command value calculated from a current detection value of a motor that applies a steering assist force to a steering mechanism. In the control device of the electric power steering device, the power supply self-holding means capable of controlling the stop of the power supply after the power is turned on, the temperature of the motor is estimated, and the temperature control is performed using the temperature estimated value. The temperature self-holding means self-holds the power while the temperature estimated value does not become less than or equal to the predetermined value even if the power stop signal is input, and suspends the steering assist control. A control device for an electric power steering device, wherein only the temperature estimation by said temperature estimation means is continued. 2. A drive element based on a current command value calculated from a steering assist command value calculated based on a steering torque generated on a steering shaft and a current detection value of a motor that applies a steering assist force to a steering mechanism. In a control device of an electric power steering device adapted to control the motor through a control unit having: a power supply self-holding means capable of controlling the stop of the power supply after the power is turned on, and controlling the temperature of the motor. Estimating, comprising a temperature estimating means for performing temperature control with the temperature estimated value, and a temperature sensor for measuring the temperature of the control unit, when a power stop signal is input, the measured temperature of the temperature sensor, The difference between the estimated temperature values is calculated, and while the difference does not fall within a predetermined value, the power is held by the power self-holding means, and the steering assist Control device for an electric power steering apparatus characterized by to cancel the control was set to be continued only temperature estimated by said temperature estimating detecting means. 3. The control device for an electric power steering device according to claim 2, wherein said temperature sensor measures a temperature of said drive element. 4. An electric power supply having a power supply self-holding circuit capable of controlling the stop of the power supply once the power supply is turned on, estimating the temperature of the motor, and controlling the temperature based on the estimated value. In the control device of the steering device, when the temperature estimation value at the time when the power supply stop signal is input is equal to or more than a predetermined value, the power supply is held for a predetermined time, and only the temperature estimation is continued with the assist control stopped. Control device for an electric power steering device.