KR101134838B1 - Method and System for Providing Fail-Safe Algorithm for Electronic Power Steering System by Using Current Sensor - Google Patents

Abstract

The present invention relates to a system and method for providing a failsafe algorithm to an electric steering apparatus using a current sensor.

The present invention provides a system for providing a fail-safe algorithm to an electric steering apparatus using a current sensor, the system comprising: a motor for detecting the movement of a steering wheel of a vehicle and providing power to assist the movement of the steering wheel; A current sensor measuring a current value applied to the motor at a predetermined cycle; And store the current value as a sample value, and when the new current value is received from the current sensor, store the stored sample value as the previous sample value and update the sample value with the new current value, and compare the sample value with the previous sample value. Including an electric control unit (ECU) for detecting an abnormality in the motor when the current variation between the sample value and the past sample value exceeds a threshold set by the manufacturer of the electric steering apparatus. The present invention provides a system for providing a failsafe algorithm to an electric steering apparatus using a current sensor.

According to the present invention, a circuit for implementing a fail-safe algorithm by providing a fail-safe algorithm that detects an abnormality of the motor by using a change amount of the current value monitored using a current sensor without a separate voltage input. Simplification reduces the cost, but has the effect of accurately detecting the occurrence of motor abnormalities in real time.

Electric steering, EPS. ECUs, failsafe, fail-safe

Description

Method and System for Providing Fail-Safe Algorithm for Electronic Power Steering System by Using Current Sensor}

1 is a block diagram of an electric steering apparatus of an automobile,

2 is a diagram illustrating a u-phase circuit of an equivalent circuit of a three-phase motor for providing a fail-safe algorithm to an electric steering apparatus using a current sensor according to a preferred embodiment of the present invention;

3 is a flowchart illustrating a process of providing a failsafe algorithm to an electric steering apparatus using a current sensor according to a preferred embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

100: electric steering device 110: input shaft

120: output shaft 130: steering wheel

140: gear unit 150: rack bar

160: electric control unit 170: motor

180: steering angle sensor 200: power

210: current sensor 220: first resistor

222: second resistor 224: third resistor

226: third resistor 230: inductor

The present invention relates to a system and method for providing a failsafe algorithm to an electric steering apparatus using a current sensor. More specifically, the present invention relates to a system and method for installing a current sensor in a motor of an electric steering device and implementing a fail-safe algorithm by sensing a current applied to a resistance and an inductor in the motor.

In general, a steering device of a vehicle is a hydraulic steering device using a hydraulic pressure of a hydraulic pump, but since the 1990s, an electric steering device using an electric motor is gradually becoming common.

In this conventional hydraulic steering system, a hydraulic pump, which is a power source that assists power, is driven by an engine, and energy consumption is always generated regardless of the rotation of the steering wheel. However, the electric steering device is controlled using an ECU (Electronic Control Unit). By rotating the motor driven by electrical energy through the steering wheel assists the power of the steering system. Therefore, when the electric steering device is installed, it is possible to improve the energy efficiency of the vehicle compared to the conventional hydraulic steering device.

1 is a block diagram of an electric steering apparatus of an automobile. As shown in FIG. 1, the electric steering apparatus 100 includes an input shaft 110 and an output shaft 120 connected coaxially with a torsion bar (not shown), and the input shaft 110 and the output shaft 120. Is supported in a rotatable state through a bearing (not shown) installed in the housing (not shown). In addition, the input shaft 110 is connected to the steering wheel 130 of the conventional vehicle is configured to rotate together with the steering wheel 130, the output shaft 120 is a pinion gear unit 140 of one side is a conventional power assisted steering device. Is configured to engage with the rack bar 150. Accordingly, the steering force generated by the driver rotating the steering wheel 130 is transmitted to the input shaft 110, and in the process of transmitting the steering force from the input shaft 110 to the output shaft 120, the torque sensor senses torque and is electric. The control unit (ECU: Electronic Control Unit (ECU) hereinafter referred to as "ECU") (160) and the ECU 160 controls the motor 170 to supply the steering auxiliary power in accordance with the sensed torque.

In the case of the electric steering apparatus 100, unlike the hydraulic steering apparatus, the ECU 160 controls the rotation of the motor 170 to supply steering auxiliary power. Therefore, in the mechanical method, an appropriate steering auxiliary power according to the driver's operation is provided. Can not supply Therefore, a device for measuring the rotational angle of the steering wheel 130 according to the driver's operation and sending it as an electrical signal to the ECU 160 is required. A device having such a function is a steering angle sensor (SAS) 180. )to be.

On the other hand, the electric steering apparatus 100 supplies steering auxiliary power by controlling the rotation of the motor 170 under the control of the ECU 160, it is to determine the state of the motor 170 in the electric steering apparatus 100. It is important. The fail-safe algorithm of the motor 170 used in the conventional electric steering apparatus 100 receives the current and the voltage from the circuit in the motor 170 to determine the state of the motor 170. do.

However, the conventional fail-safe algorithm has to input both current and voltage to grasp the state of the motor 170, so that the circuit for implementing the fail-safe algorithm is complicated and the cost of constructing the circuit for implementing the fail-safe algorithm is complicated. There were many problems.

In order to solve this problem, the present invention provides a system and method for installing a current sensor in the motor of the electric steering device, and implementing a fail-safe algorithm by sensing a current applied to a resistance and an inductor inside the motor. It is for that purpose.

In order to achieve this object, according to the first object of the present invention, a system for providing a fail-safe algorithm to an electric steering apparatus using a current sensor, by detecting the movement of the steering wheel of the vehicle steering wheel A motor providing power to assist movement of the motor; A current sensor measuring a current value applied to the motor at a predetermined cycle; And store the current value as a sample value, and when the new current value is received from the current sensor, store the stored sample value as the previous sample value and update the sample value with the new current value, and compare the sample value with the previous sample value. Including an electric control unit (ECU) for detecting an abnormality in the motor when the current variation between the sample value and the past sample value exceeds a threshold set by the manufacturer of the electric steering apparatus. The present invention provides a system for providing a failsafe algorithm to an electric steering apparatus using a current sensor.

According to a second object of the present invention, there is provided a method of providing a fail-safe algorithm to an electric steering apparatus using a current sensor, wherein (a) the current sensor is an electric control unit (ECU). Monitoring the current value applied to the resistance of the motor and the inductor at a predetermined cycle according to the control of “ECU”, and receiving the current value from the current sensor by the ECU at a predetermined cycle; (b) storing the current value as a sample value, and storing the stored sample value as a past sample value and updating the sample value to the received current value when receiving the current value measured at a predetermined period from the current sensor; (c) comparing the sample value with the past sample value to determine whether the amount of change between the sample value and the past sample value has exceeded a threshold value; And (d) informing the motor that the abnormality is detected when it is determined in step (c) that the amount of change between the sample value and the past sample value has exceeded the threshold value, to the electric steering apparatus using the current sensor. It provides a method for providing a failsafe algorithm.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are used as much as possible even if displayed on different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

2 is a diagram illustrating a u-phase circuit of an equivalent circuit of a three-phase motor providing a fail-safe algorithm to an electric steering apparatus using a current sensor according to an exemplary embodiment of the present invention.

The equivalent circuit of the u phase among the u, v, w three phases of the three phase motor providing the failsafe algorithm to the electric steering apparatus using the current sensor according to the preferred embodiment of the present invention may be represented by the connection of the resistor and the inductor. The first resistor 220, the second resistor 222, the third resistor 224, the fourth resistor 226, and the inductor 230 may be represented.

The power source 200 applies power to the motor 170 of the electric steering apparatus 100 so that the u, v and w three-phase circuits inside the motor are driven.

The current sensor 210 is connected between the power source 200 and the motor 170 to monitor in real time the current value applied to the motor 170 in a certain period of the electric control unit (ECU: Electronic Control Unit, hereinafter referred to as "ECU" 160) and transmits the monitored current value.

The resistance of the u-phase circuit has various resistance values and constitutes the circuit in various forms (serial, parallel, or parallel), but in the present invention, the first resistor 220 and the second resistor ( 222, the third resistor 224 and the fourth resistor 226 is represented by a series-parallel connection, the resistance value is set to 100 Ω, respectively.

The inductor 230 is a coil that induces a voltage in proportion to the amount of change in the current, and serves as a filter that prevents a sudden change in the current in the motor 170 and filters out electrical noise.

The electric steering apparatus 100 controls the rotational force of the motor 170 by controlling the current value applied to the motor 170. Therefore, the amount of change in the current value applied to the motor 170 has a continuous value by the inductor 230 unless the resistance in the motor 170 is disconnected or shorted.

However, when the windings in the motor 170 are disconnected or short-circuited and the total resistance value in the motor 170 changes, the current value before the resistor is disconnected or short-circuited and the resistance is disconnected or short-circuited based on the moment when the resistance is disconnected or short-circuited. The current value changes discontinuously.

3 is a flowchart illustrating a process of providing a failsafe algorithm to an electric steering apparatus using a current sensor according to a preferred embodiment of the present invention.

The current sensor 210 monitors the resistance of the motor 170 and the current value applied to the inductor 230 under the control of an electronic control unit (ECU) 160 (see FIG. S300).

The ECU 160 receives the current value monitored from the current sensor 210 at a predetermined cycle (S302).

When the ECU 160 stores the current value received from the current sensor 210 as a sample value, and receives the current value from the current sensor 210 at a predetermined period, the ECU 160 stores the stored sample value as a past sample value and then stores the sample value. Update (S304).

The ECU 160 checks whether the difference between the sample value and the past sample value exceeds the threshold set by the manufacturer of the electric steering apparatus 100 by comparing the sample value with the past sample value (S306).

In the present invention, in the case of the resistor present in the circuit in the motor 170, if the disconnection or short-circuit changes the total resistance value, the current value applied to the overall resistance also changes.

For example, as shown in FIG. 2, the first resistor 210 and the second resistor 212 are connected in parallel, the third resistor and the fourth resistor 216 are connected in parallel, and they are connected in series. In a circuit with, the total resistance is 100 Ω. However, when the first resistor 210 is cut off, the total resistance becomes 150 Ω, and when both terminals of the second resistor 212 are disconnected and a situation in which the third resistor and the fourth resistor are connected in parallel occurs, The resistance is about 133 Ω, and the total resistance changes instantaneously.

In the normal case, the change amount of current applied to the motor 170 of the electric steering apparatus 100 has a continuous value by the inductor 230 in the motor 170. However, when the winding in the motor 170 is disconnected or short-circuited as described above, the amount of change in the current applied to the motor 170 changes discontinuously at the moment the resistance is changed.

If it is determined in step S306 that the difference between the sample value and the past sample value exceeds the threshold set by the manufacturer of the electric steering apparatus 100, the ECU 160 issues a warning lamp to inform the motor 170 that an abnormality has been detected. In operation S308, the power source 200 of the motor 170 is cut off to protect the motor 170.

If it is determined in step S306 that the difference between the sample value and the past sample value does not exceed the threshold set by the manufacturer of the electric steering apparatus 100, the ECU 160 continuously performs step S304.

Here, the threshold is most preferably set to such an extent that a disconnection or short circuit occurs to detect an amount of change in current such that an abnormality occurs in the motor 170.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

As described above, according to the present invention, a fail-safe algorithm is provided by providing a fail-safe algorithm that detects an abnormality of a motor by using a change amount of a current value monitored by a current sensor without a separate voltage input. The cost is reduced by simplifying the circuit to implement the circuit, and it is effective to accurately detect the occurrence of an abnormality of the motor in real time.

Claims (4)

A system for providing a fail-safe algorithm to an electric steering apparatus using a current sensor, A motor that detects a movement of a steering wheel of a vehicle and provides power to assist the movement of the steering wheel; A current sensor measuring a current value applied to the motor at a predetermined cycle; And If it is determined that the current applied to the motor is discontinuously changed through the signal received from the current sensor, an electric control unit (ECU: Electronic Control Unit (ECU) hereinafter referred to as an abnormality) of the motor. A system for providing a failsafe algorithm to an electric steering apparatus using a current sensor comprising a. The method of claim 1, wherein the current sensor, And providing a fail-safe algorithm to the electric steering apparatus using a current sensor, by monitoring the current value applied to the motor and transmitting the current value to the ECU at regular intervals. The method of claim 1, wherein the ECU, When a failure is detected in the motor, a warning lamp (Warning Lamp) indicating the abnormality of the motor is turned on, and the fail-safe algorithm is provided to the electric steering apparatus using a current sensor, characterized in that to cut off the power applied to the motor. System. In the method for providing a fail-safe algorithm to the electric steering apparatus using a current sensor, (a) The current sensor monitors the current value applied to the motor at a constant cycle according to the control of an electronic control unit (ECU: hereinafter referred to as 'ECU'), and at the predetermined cycle, the ECU is driven from the current sensor. Receiving the current value; (b) storing the current value as a sample value, and when the current value measured at the predetermined period is received from the current sensor, storing the stored sample value as a past sample value and then receiving the sample value as the current value received. Updating; (c) comparing the sample value with the past sample value to determine whether the amount of change between the sample value and the past sample value has exceeded a threshold value; And (d) informing the motor that an abnormality is detected when it is determined in step (c) that the amount of change between the sample value and the past sample value exceeds the threshold value; Method for providing a fail-safe algorithm to the electric steering apparatus using a current sensor comprising a.

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