KR20070096362A - Method for compensating gain error of current sensor and electronic control unit therefor - Google Patents

Abstract

A method for compensating a gain error of a current sensor and an electronic control unit therefor are provided to improve a motor control accuracy by minimizing a torque ripple in a current supplied to a motor. An electronic control unit for a motor includes an inverter(140), plural current sensors(150), and an MCU(130). The inverter delivers a supply current to the motor. The current sensors detect the supply current and output the detected results. The MCU receives a generated torque from the torque sensor, calculates a control current according to the generated torque, and controls the inverter to output the supply current. The MCU(Motor Control Unit) receives a sampled current value from the current sensor, calculates gains for the current sensors, and compensates a gain error.

Description

Method for Compensating Gain Error of Current Sensor and Electronic Control Unit Therefor}

1 is a block diagram schematically illustrating an electronic controller for gain error compensation of a current sensor according to an exemplary embodiment of the present invention;

2 is a flowchart illustrating a gain error compensation method of a current sensor according to a preferred embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

110: torque sensor 120: ECU

130: MCU 140: Inverter

150: a-phase current sensor 160: b-phase current sensor

170: motor

The present invention relates to a method for compensating a gain error of a current sensor and an electronic control unit (ECU) for the same. More specifically, a method of minimizing torque ripple of a motor by compensating a gain error by measuring a current gain, that is, a gain in real time, of a current sensor that senses a current flowing in a motor in an ECU of an automobile. It relates to an electronic control device therefor.

Normally, a hydraulic power steering device (Hydraulic Power Steering Apparatus) using the hydraulic pressure of a hydraulic pump is used as a steering device of an automobile, but since the 1990s, an electric power steering device (EPS: Electronic Power Steering Apparatus) has gradually become more common. have. Conventional hydraulic power steering system uses a hydraulic pump, which is the power source to assist the power, is driven by the engine and consumes energy all the time regardless of whether the steering wheel is rotated, whereas the electric steering system generates torque when the steering wheel rotates. A motor driven by electrical energy provides steering assistance power. Therefore, when the electric steering device is used, energy efficiency can be improved compared to the hydraulic power steering device.

In general, the electric steering device uses the generated torque, vehicle speed, steering angle, etc. to grasp the driver's steering intention and the driving condition of the vehicle, and generates steering assistance by comprehensively considering the steering column, rack bar, rack and pinion, etc. This makes it easier for the driver to drive and makes the car run safer.

Electric steering is made up of many mechanical and electronic components, but the most important configuration is the ECU. ECU is the core device of the electric steering device that analyzes the electric signals transmitted from various external sensors to understand the driver's steering intention and the driving situation of the car, and controls the motor using various logics provided. .

In general, the ECU detects the current flowing in the motor to precisely control the motor, and uses the current sensor to determine the current flowing in the motor. That is, if the motor uses a three-phase power source, a current sensor is attached to two phases of three phases (for example, a phase, b phase, and c phase a and b phases) to measure and measure the current of each phase. The current of each phase is used to calculate the current of the other phase.

The ECU calculates ripple, that is, torque ripple, according to the torque generated in the motor and the torque using the current of each phase measured as described above. Torque ripple is caused by a gain error generated on a path for delivering current detected by the current sensor or on an amplifier inside the current sensor, which causes a problem that the control performance of the motor is degraded due to the torque ripple.

Therefore, in order for the ECU to precisely control the motor, torque ripple must be minimized by compensating for the gain error generated by the current sensor. In addition, the gain error generated by the current sensor is continuously generated in the process of controlling the motor due to the surrounding environment and the aging of the current sensor. Therefore, it is required to develop a technology that continuously compensates for the gain error in the process of controlling the motor by the ECU. do.

In order to solve this problem and meet the demands thereof, the present invention provides a method of minimizing torque ripple of a motor by measuring a gain of a current sensor that senses a current flowing in a motor in an ECU of a vehicle in real time, and compensating for a gain error. The purpose is to provide an ECU for him.

In order to achieve the above object, the present invention provides an electronic control unit (ECU) for controlling a motor by detecting a generated torque from a torque sensor, comprising: an inverter for transmitting a supply current to the motor; A plurality of current sensors for sensing and delivering a supply current; And controlling the inverter to supply the supply current by receiving the generated torque from the torque sensor and calculating a control current according to the generated torque, receiving and storing current values sampled from the plurality of current sensors, An electronic control device for gain error compensation of a current sensor, comprising a motor control unit (MCU: Motor Control Unit, hereinafter referred to as MCU) that calculates a gain by calculating a gain). to provide.

In addition, according to another object of the present invention, a method for compensating for the gain error of a plurality of current sensors in an electronic control unit (ECU) for controlling the motor by detecting the generated torque from the torque sensor, (a) motor Checking whether the current control is performed, and measuring and storing a current value by sampling a supply current supplied to the motor using a plurality of current sensors; (b) determining whether to stop the current control and calculating and storing gain errors by calculating gains of the plurality of current sensors using current values; And (c) checking whether the current control is performed to compensate for the gain error.

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 addition, in describing the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

FIG. 1 is a block diagram schematically illustrating an electronic control unit (ECU) hereinafter referred to as an ECU for gain error compensation of a current sensor according to an exemplary embodiment of the present invention.

ECU 120 for gain error compensation of the current sensor according to the preferred embodiment of the present invention is connected to the torque sensor 110 and the motor 170, by analyzing the electrical signal input from the torque sensor 110, etc. The driving state is sensed by the driver and a supply current for controlling the driving torque of the motor 190 is output to be suitable for the driving situation.

Here, in FIG. 1, the ECU 120 is illustrated as only connected to the torque sensor 110, but may be actually connected to a plurality of sensors for detecting a driving situation such as a vehicle speed sensor and a steering angle sensor. The motor 170 generates and transmits auxiliary power for smooth steering according to the supply current transmitted from the ECU 120.

In addition, the ECU 120 for gain error compensation of the current sensor according to an embodiment of the present invention is a motor control unit (MCU: Motor Control Unit, hereinafter referred to as 'MCU', 130), inverter (Inverter, 140), It includes a phase current sensor 150 and b phase current sensor 160.

The MCU 130 is connected to the torque sensor 110 to receive the electrical signal from the torque sensor 110 to determine the generated torque, calculate the control current according to the generated torque to control the inverter 140 by the inverter 140 To supply the supply current corresponding to the control current to the motor 170.

MCU 130 according to a preferred embodiment of the present invention is an algorithm for compensating for the gain error of the a-phase current sensor 150 and the b-phase current sensor 160 attached to the connection between the inverter 140 and the motor 170 While the current control of the motor 170 is performed, the current value of a phase and the current value of b phase are sampled at a predetermined time, measured, stored in a provided memory, and the current control of the motor 170 The current value stored in the memory during the absence (eg during Ignition Start Initial Check, during Fail-Safety, during Power Latch, etc.) After calculating the gain error by calculating the gain of the phase, and performing the current control of the motor 170 again, the gain error is compensated by adjusting the gain of each phase current sensor to the value of the preset gain such that the gain of each phase is the same. The ECU 120 controls the supply current of the motor 170 to the value of the gain thus adjusted.

To this end, the MCU 130 calculates a control current according to the generated torque to control the inverter 140 and performs a calculation to compensate for a gain error, software of an algorithm for calculating the control current according to the generated torque, and an inverter. Non-volatile memory, such as the software of the algorithm for controlling the 140, the software of the algorithm for compensating the gain error, and the like EEPROM (Electrically Erasable Program ROM) for storing the sampled current value and the predetermined gain, A volatile memory such as RAM (Random Access Memory) for executing various software stored in the volatile memory and storing temporary data generated by calculation is provided.

The inverter 140 converts a direct current into an alternating current and supplies power to the motor 170. The inverter 140 supplies a supply current to the motor 170 under the control of the MCU 130. That is, the inverter 140 controls the operation of the motor 170 by varying the supply current supplied to the motor 170 by switching the switching element provided according to the control current when the control current is transmitted from the MCU 130. . At this time, since the inverter 140 converts direct current into alternating current and supplies it to the motor 170, the inverter 140 supplies three-phase alternating current power to the motor 170.

The a-phase current sensor 150 and the b-phase current sensor 160 are attached to the a-phase and b-phase connection, respectively, of the three-phase connection between the inverter 140 and the motor 170, and detects the current value of each phase to determine the MCU ( 130 is a current sensor that feeds back.

Torque ripple generated from the supply current supplied to the motor 170 is generated in accordance with the gain of the current sensor of each phase. Hereinafter, the relationship between the gain and the torque ripple of the current sensor will be described through Equations 1 to 3 below.

 If the current in phase a is Ia, the current in phase b is Ib, the current in phase c is Ic, and the gains of phase a and phase b, that is, the gain of phase a and phase b, are respectively k1 and k2. Ic is calculated as in Equation 1.

When the generated torque Te is calculated using the current of each phase calculated as in Equation 1, it is calculated as in Equation 2.

Here, when the torque ripple Tr is calculated using the generated torque, it is calculated as in Equation 3.

As shown in Equation 3, it can be seen that the torque ripple varies depending on the gain k1 of the a-phase current sensor 150 and the gain k2 of the b-phase current sensor 160. In other words, if the values of k1 and k2 are the same, Tr is 0, and if the values of k1 and k2 are the same absolute value and are different from each other in positive and positive values, the torque ripple becomes maximum as in 3D. Accordingly, the torque ripple of the supply current supplied to the motor 170 may be minimized by adjusting the a-phase current sensor 150 and the b-phase current sensor 160 so that the values of k1 and k2 are the same.

Hereinafter, a method of compensating for a gain error of a current sensor by using an ECU for gain error compensation of the current sensor described with reference to FIG. 1 will be described.

2 is a flowchart illustrating a gain error compensation method of a current sensor according to a preferred embodiment of the present invention.

In order to compensate for gain errors of the a-phase current sensor 150 and the b-phase current sensor 160, the ECU 120 checks whether to start the current control of the motor 170 (S210). This is because the current control of the motor 170 must be performed in order to measure the current flowing in the motor 170.

When the ECU 120 does not start the current control of the motor 170 as a result of checking in step S310, the ECU 120 checks whether the current control is continuously started, and when the current control starts, the phase A current sensor 150 is connected to the a-phase current sensor 150. Using the b-phase current sensor 160, the current value of the supply current supplied to the motor 170 in each phase is sampled and stored in the provided memory (S220). In this case, in sampling the current value of each phase, the ECU 120 preferably sets a plurality of times in advance and samples the current value to measure the plurality of current values. In other words, as many calculations are taken as the calculation permits, the more current values are measured, the more precisely the gain errors can be minimized.

Therefore, after setting a plurality of sampling time points, the ECU 120 measures the current value of each phase at the corresponding time point and checks whether sampling at all time points is completed (S230).

As a result of confirming in step S230, the ECU 120 proceeds to step S220 to continue sampling if the sampling at all time points is not completed, and to control the current of the motor 170 when the sampling at all time points is completed. Check whether it has stopped (S240). The reason for checking whether the current control is stopped is that an error occurs when the ECU 120 calculates the gain of each current sensor while controlling the current of the motor 170.

If the current control of the motor 170 is not stopped, as a result of checking in step S240, the ECU 120 waits until the current control is stopped to check whether the current control is continuously stopped, and the current control is stopped. In other words, for example, after the initial check for start-up, after fail safety, after power latch, etc., gain error is calculated by calculating the gains of the a-phase current sensor 150 and the b-phase current sensor 160. Calculate and store in the provided memory (S250). Here, since the ECU 120 calculates the gain of each current sensor is a well known technique, a detailed description thereof will be omitted.

The ECU 120 checks whether the current control of the motor 170 is performed again (S260). This is to compensate for gain error while performing current control of the motor 170.

If the ECU 120 does not perform the current control of the motor 170 again as a result of confirming in step S260, the ECU 120 waits until the current control is resumed, and if the current control is performed again, each of the current sensors calculated in the step S250 The gain is compensated by adjusting the preset gain, that is, equal to the preset optimal gain when the ECU 120 is manufactured (so that the gain value of each current sensor is the same) (S270).

As described above, the ECU 120 controls the motor 170 by compensating the gain of each current sensor to minimize torque ripple due to a gain error that may occur from each current sensor, thereby performing more precise motor 170 control. can do.

As a result, when the ECU 120 is manufactured, the gain of each preset current sensor is changed due to the surrounding environment or the aging of the current sensor or other components, so that the gain of each current sensor is different from each other, thereby supplying the supply current to the motor 170. The occurrence of torque ripple can be prevented. That is, the ECU 120 may adjust the gains of the current sensors to be equal to each other and to be equal to the preset gains in real time even after being manufactured, thereby more precisely controlling the motor 170.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes 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, even after the ECU is manufactured, the gains of the supply currents supplied to the motors are adjusted by adjusting the gains of the current sensors that sense the currents supplied to the motors in real time to be equal to each other and the same as the preset gains. Torque ripple can be minimized, allowing more precise motor control.

Claims (8)

In the electronic control unit (ECU: Electronic Control Unit) for detecting the generated torque from the torque sensor to control the motor, An inverter transferring a supply current to the motor; A plurality of current sensors for sensing and delivering the supply current; And Receives the generated torque from the torque sensor and calculates a control current according to the generated torque to control the inverter to supply the supply current, receives and stores current values sampled from the plurality of current sensors, A motor control unit (MCU), which calculates a gain of a current sensor and compensates the gain error, is referred to as an MCU. Electronic control device for the gain error compensation of the current sensor comprising a. The method of claim 1, wherein the MCU, And controlling and storing the current values sampled from the plurality of current sensors while controlling the motor. The method of claim 1, wherein the MCU, The electronic control device for the gain error compensation of the current sensor, characterized in that for calculating the gain of the plurality of current sensors while stopping the control of the motor. The method of claim 1, wherein the MCU, The electronic control device for gain error compensation of the current sensor, characterized in that for compensating for the error of the gain while controlling the motor. The method of claim 1, wherein the MCU, And controlling the gains of the plurality of current sensors in the same manner to compensate for the gain error. A method of compensating for gain errors of a plurality of current sensors in an electronic control unit (ECU) that senses generated torque from a torque sensor to control a motor. (a) checking whether the current control of the motor is performed and sampling and supplying current supplied to the motor by using the plurality of current sensors to measure and store a current value; (b) determining whether to stop the current control and calculating and storing gain errors by calculating gains of the plurality of current sensors using the current values; And (c) checking whether the current control is performed to compensate for the gain error Gain error compensation method of the current sensor comprising a. The method of claim 6, wherein step (a) is (a1) checking whether the current control of the motor is performed and sampling and measuring the supply current using the plurality of current sensors; (a2) checking whether sampling is completed at all preset time points; And (a3) when the sampling is completed at all the time points as a result of confirming the step (a2), storing the current values at all the time points Gain error compensation method of the current sensor comprising a. The method of claim 6, wherein in step (c), The ECU compensates the gain error of the current sensor by adjusting the gains of the plurality of current sensors to be equal to each other.

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