KR101148586B1 - Method for Sensing ?? Mortor Line Fault of Electric Power Steering Apparatus - Google Patents

Abstract

The present invention relates to a DC motor line short circuit detection method of an electric steering apparatus.

According to an aspect of the present invention, there is provided a method for detecting a short circuit between motors of an electric power steering apparatus, the method comprising: (a) receiving current information which is an actual current value of the motor from a current sensor of a driving circuit unit; (b) comparing the received current information with a target current value to determine whether a difference occurs; (c) calculating a cancellation duty ratio for canceling the difference if a difference occurs as a result of the checking in step (b); (d) checking whether the offset duty ratio is less than a preset reference duty ratio; And (e) transmitting a relay-off control signal when the offset duty ratio is less than the reference duty ratio, as a result of the checking of step (d). do.

According to the present invention, by detecting the line short circuit occurring in the motor and turning off the relay of the driving circuit unit, the driver stops the driving of the motor so that the driver can make safer steering. That is, when a short circuit occurs between the motors, the driver feels a heavy handle feeling by stopping the driving of the motor, thereby making it possible to steer to reduce the risk of a safety accident.

Motor, Short Circuit, Sense, Logic, Electric Steering

Description

Method for Sensing Short Circuit Between Motors of Electric Steering System {Method for Sensing DC Mortor Line Fault of Electric Power Steering Apparatus}

1 is a block diagram schematically showing a DC motor line short circuit detection device according to an embodiment of the present invention;

2A is a current flow chart schematically showing a case where a DC type motor is driven clockwise;

2b is a current flow chart schematically showing a case in which the DC type motor is driven counterclockwise;

2C is a current flow chart in the vicinity of a motor schematically showing a case where a line short circuit occurs in a DC type motor;

3 is a flowchart illustrating a DC motor line short circuit detection method according to an exemplary embodiment of the present invention.

Description of the Related Art

110: torque sensor 120: ECU

130: drive circuit portion 140: motor

210: battery 220: H-bridge

230: clockwise current 240: counterclockwise current

The present invention relates to a DC motor line short circuit detection method of an electric steering apparatus. In more detail, current information, which is the actual current value of the motor, is received from the current sensor, and if the current information is different from the target current value, an offset duty ratio for canceling is calculated, and the offset duty ratio is less than a preset reference duty ratio. In this case, the present invention relates to a DC motor line short circuit detection method of an electric steering apparatus in which a line short circuit of a motor is regarded as occurring.

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

Existing hydraulic steering system consumes energy at all times regardless of whether the steering wheel is rotated by the hydraulic pump driven by the engine. Energy-driven motors provide steering assistance. Therefore, when the electric steering apparatus is used, the energy efficiency of the vehicle can be improved compared to the hydraulic steering apparatus.

The conventional electric steering system includes a torque sensor, an ECU, a drive circuit and a motor, and the torque sensor generates an electrical signal by detecting a relative rotational displacement of the input shaft and the output shaft according to the rotation of the steering wheel. It transmits to ECU. The ECU receives a signal from the torque sensor, generates a control signal for controlling the driving of the motor according to the driving state of the vehicle, and transmits it to the driving circuit unit. The driving circuit unit receives the control signal from the ECU to drive the motor. do.

In addition, the conventional electric steering system has a fail-safe logic to determine whether a failure occurs in the signal received from the torque sensor, and if the failure occurs as a result of the operation to stop the operation of the motor.

However, in the case of a conventional electric steering system having fail-safe logic, it is determined whether or not a failure has occurred in a signal received from a torque sensor, but it has a disadvantage in that it is not detected when a short circuit occurs in a motor. . In general, when a short circuit occurs between the motor lines, current flows bypassing the motor, and in the motor, auxiliary power for smooth steering is not generated, and magnetic brakes are caused by self-currents flowing in the closed circuit formed inside the motor by the short circuit between the lines. Magnetic Brake) acts to hinder steering.

For example, when the driver handles, the electric steering system requires auxiliary power for smooth steering with the motor, but the motor does not generate auxiliary power when a short circuit between the motors occurs. The ECU receives a signal from the torque sensor and transmits a motor control signal according to the state of the vehicle to the driving circuit section. The driving circuit section supplies current to control the motor, but in the motor, the current flows bypass the motor due to a short circuit between the motors. This does not occur.

Accordingly, there is a need for an electric steering apparatus having a motor-line short-circuit detection logic that detects the above-described motor line short circuit and stops the operation of the electric steering apparatus, thereby making the driver feel a heavy handle and thereby enables safe steering. One is not yet provided.

In order to solve the above problems, the present invention receives current information that is the actual current value of the motor from the current sensor, calculates an offset duty ratio for canceling the current information if there is a difference from the target current value, the offset duty It is an object of the present invention to provide a DC motor line short circuit detection method of an electric steering apparatus in which a line short circuit of a motor is considered to occur when the ratio is less than a preset reference duty ratio.

In order to achieve the above object, the present invention, in the motor line short circuit detection method of the electric power steering (Electric Power Steering Apparatus), (a) receiving current information that is the actual current value of the motor from the current sensor of the drive circuit unit step; (b) comparing the received current information with a target current value to determine whether a difference occurs; (c) calculating a cancellation duty ratio for canceling the difference if a difference occurs as a result of the checking in step (b); (d) checking whether the offset duty ratio is less than a preset reference duty ratio; And (e) transmitting a relay-off control signal when the offset duty ratio is less than the reference duty ratio, as a result of the checking of step (d). do.

Hereinafter, preferred 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.

1 is a block diagram schematically showing a DC motor line short circuit detection system according to a preferred embodiment of the present invention. The system for detecting the line short circuit of the DC motor according to an exemplary embodiment of the present invention includes a torque sensor 110, an ECU 120, a driving circuit unit 130, and a motor 140.

The torque sensor 110 detects a relative rotational displacement of the input shaft and the output shaft according to the rotation of the steering wheel to generate an electrical signal and transmit the electrical signal to the ECU 120.

Electronic control unit (ECU) 120 according to a preferred embodiment of the present invention includes a motor line short circuit detection logic 122 and receives a signal from the torque sensor 110 to determine the driving state of the vehicle and then the amount of current flowing through the motor. It controls the driving of the motor by adjusting the. In addition, the ECU 120 receives current information, which is the actual current value of the motor, from the current sensor 132 and transmits it to the motor line short circuit detection logic 122 and generates a motor line short circuit from the motor line short circuit detection logic 122. Receive a signal or a normal operating signal. The ECU 120 transmits a control command to turn off the relay 134 to the driving circuit unit 130 when the short circuit occurrence signal between the motors is received, and returns to the normal mode to the driving circuit unit 130 when the normal operation signal is received. Send a working signal.

The motor line short circuit detection logic 122 according to an exemplary embodiment of the present invention compares current information received from the ECU 120 with a target current value (that is, a current value required by the system) to determine whether a difference occurs. If a difference occurs as a result of the check, the short circuit detection logic 122 between the motors calculates an offset duty ratio for canceling the difference between the current information and the target current value, and when the offset duty ratio is less than the preset reference duty ratio, It is determined that a short circuit has occurred between the lines and performs a function of controlling to transmit a relay-off control signal to the ECU 120.

The driving circuit unit 130 according to the preferred embodiment of the present invention includes a current sensor 132 and a relay 134, and receives a motor control signal from the ECU 120 to generate a current for controlling the motor 140. And then transmits to the motor 140. The current sensor 132 transmits current information, which is an actual current value measured from the motor resistance value and the battery voltage value of the driving circuit unit 130, to the ECU 120, and the relay 134 is a motor in the on state. It serves to pass the current to 140 and in the off state serves to block the current to the motor 140.

The motor 140 generates and transmits auxiliary power for smooth steering according to the control current transmitted from the driving circuit unit 130.

2A is a circuit diagram schematically showing a current flow diagram when the DC type motor is driven in a clockwise direction, and FIG. 2B is a circuit diagram schematically showing a current flow diagram when the DC type motor is driven in a counterclockwise direction. A current flow chart schematically showing a case where a line short circuit occurs in a DC type motor.

For convenience of description, FIGS. 2A, 2B, and 2C will be described together. 2A and 2B, a clockwise current 230 or a counterclockwise current 240 flows to drive the motor, where the current passes through the H-bridge 220.

Referring to the duty ratio of the H-bridge 220 in the example of FIGS. 2A and 2B when driving a general motor, the supply voltage of the battery 210 is 12 [V] and the maximum of the motor 140 is shown. If the current value is 50 [A] and the phase resistance value of the motor 140 is assumed to be 0.1 [Ω], the supply voltage of the motor 140 is 50 × 0.1 = 5 [V] since V = I × R. Since the duty ratio of the H-bridge 220 is a motor supply voltage / battery supply voltage (5/12 = 0.42), a duty ratio of at least 42% is required. When the actual motor 140 is driven, the duty ratio may be greater than 42% due to the counter electromotive voltage generated by the motor 140 and the switching effect rate of the H-bridge 220.

In addition, when the duty ratio in the case where a short circuit occurs between the motor lines is taken as an example of FIG. 2C, the motor phase resistance is 0 [Ω] or up to 0.02 [Ω] depending on the short circuit position due to the short circuit between the motor lines. Therefore, when the supply voltage of the battery 210 is 12 [V], the maximum current value of the motor is 50 [A], and the phase resistance of the motor 140 is 0.02 [Ω], the motor 140 Since the supply voltage of V = I × R is 50 × 0.02 = 1 [V], the duty ratio of the H-bridge 220 is the supply voltage of the motor / battery supply voltage (1/12 = 0.08), so the duty ratio Is at least 8%. When the motor is actually driven, the duty ratio will be higher than 8% due to the counter voltage generated from the motor and the switching effect rate of the H-bridge 220. However, the duty ratio is higher than the duty ratio (42%) when the motor is normally operated. It is a small value.

3 is a flowchart illustrating a DC motor line short circuit detection method according to an exemplary embodiment of the present invention.

The ECU 120 receives the signal from the torque sensor 110 to determine the driving state of the vehicle, generates a control signal for adjusting the amount of current flowing through the motor, and transmits the generated control signal to the driving circuit unit 130. The driving circuit unit 130 receives a control signal from the ECU 120 and supplies a current to the motor 140. At this time, the current sensor 132 of the driving circuit unit 130 measures the current information that is the actual current value (40 [A]) of the motor and transmits it to the ECU 120.

The ECU 120 receives current information from the current sensor 132 of the driving circuit 130 and transmits it to the motor line short circuit detection logic 122 (S310).

The motor line short detection logic 122 compares the received current information with a target current value (that is, a current value required by the system) to determine whether a difference occurs (S320).

For example, assuming that the target current value is 50 [A] and the actual current value (current information) of the motor is 40 [A] for convenience of description of the present invention, the motor line short circuit detection logic 122 is Among the received current information, the actual current value 40 [A] of the motor is compared with the target current value 50 [A] to check whether or not a difference occurs.

If the difference between the received current information and the target current value does not occur as a result of checking in step S320, the short circuit detection logic 122 between the motor lines assumes that a short circuit does not occur between the motor lines and transmits a normal operation signal to the ECU 120. It transmits (S330).

For example, if the target current value is assumed to be 50 [A] and the actual current value (current information) of the motor is assumed to be 50 [A], there is no difference between the current information and the target current value. The short circuit detection logic 122 considers that a short has not occurred between motor lines.

The ECU 120 receiving the normal operation signal transmits the normal operation signal to the driving circuit unit 130.

On the other hand, if the difference between the received current information and the target current value as a result of the check in step S320, the motor short circuit detection logic 122 is the received current information (that is, the actual current value of the motor) and the target current value ( That is, the offset duty ratio for canceling the difference of the current value required by the system is calculated (S330).

For example, assuming that the battery voltage value is 12 [V], the actual current value of the motor is 40 [A], and the motor resistance value is 0.1 [Ω]. = I × R = 40 × 0.1 = 4 [V], and the offset duty ratio is the motor voltage / battery voltage (4/12 = 0.34), so the offset duty ratio is about 34%.

The motor line short detection logic 122 checks whether the offset duty ratio is less than the preset reference duty ratio (S340).

For example, assuming that the battery voltage value is 12 [V], the target current value is 50 [A], and the motor resistance value is 0.1 [Ω], the voltage of the motor is V = I. Since × R is 50 × 0.1 = 5 [V], and the reference duty ratio is the voltage / battery voltage (5/12 = 0.42) of the motor, so the offset duty ratio is about 42%. 122) checks whether the offset duty ratio (about 34%) is less than the reference duty ratio (about 42%).

As a result of checking in step S340, when the offset duty ratio is less than the preset reference duty ratio, the motor line short circuit detection logic 122 considers that a short circuit has occurred between the motor lines and transmits a motor line short circuit generation signal to the ECU 120 (S350). ).

The ECU 120 transmits a relay-off control signal to the driving circuit unit 130 after receiving the short circuit occurrence signal between motor lines, and the driving circuit unit 130 receives the relay-off control signal to turn off the relay 134. By interrupting the current supplied to the motor 140 to stop the operation of the electric steering device.

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 protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

As described above, according to the present invention, by detecting a short circuit occurring in the motor and turning off the relay of the driving circuit unit, the driver stops the driving of the motor, thereby enabling the driver to make safer steering. That is, when a short circuit occurs between the motors, the driver feels a heavy handle feeling by stopping the driving of the motor, thereby making it possible to steer to reduce the risk of a safety accident.

Claims (4)

In the motor line short circuit detection method of the electric power steering (Electric Power Steering Apparatus), (a) receiving current information which is an actual current value of the motor from a current sensor of a driving circuit unit; (b) comparing the received current information with a target current value to determine whether a difference occurs; (c) calculating a cancellation duty ratio for canceling the difference if a difference occurs as a result of the checking in step (b); (d) checking whether the offset duty ratio is less than a preset reference duty ratio; And (e) transmitting a relay-off control signal when the cancellation duty ratio is less than the reference duty ratio as a result of the checking in step (d). Motor line short circuit detection method of the electric steering apparatus comprising a. delete The method of claim 1, wherein step (e) (f) transmitting a normal operation signal when the cancellation duty ratio is equal to or greater than the reference duty ratio as a result of the checking in step (d). Motor line short circuit detection method of the electric steering apparatus comprising a. The method of claim 1, And said reference duty ratio of said step (d) is set on the basis of the duty ratio when said motor operates in a normal state.

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