CN-113972873-B - Motor drive control system and method

Abstract

A motor drive control system includes an actuator configured to generate a rotational force by driving a current to be connected thereto, a current provider configured to provide a current to the actuator while repeatedly turning on and off the current with a preset period and duty ratio, and a controller configured to estimate a rotational position or a rotational speed of the actuator in a portion where the current of the current provider is turned on or off, and control the current provider to follow a speed command based on the estimated rotational position or rotational speed.

Inventors

• LIU CHANGXI
• JIN ZHUYUAN
• JIN CHENGDAO
• KANG MINXIU

Assignees

• 现代自动车株式会社
• 起亚自动车株式会社

Dates

Publication Date

20260508

Application Date

20201127

Priority Date

20200724

Claims (15)

1. 1. A motor drive control system comprising: an actuator configured to generate a rotational force by driving using the received current; A current provider configured to provide a current to the actuator while repeatedly switching on and off the current at a preset cycle and duty cycle, and A controller configured to estimate a rotational position or rotational speed of the actuator in a portion where the current of the current provider is turned on and off, and control the current provider to follow a speed command based on the estimated rotational position or rotational speed; Wherein the controller estimates the rotational speed of the actuator in the portion where the current of the current provider is disconnected based on the previous rotational speed of the actuator, the damping coefficient, the moment of inertia coefficient, the load torque, and the estimated period of the rotational speed.
2. 2. The motor drive control system according to claim 1, further comprising: a sensor configured to sense a current or voltage applied from the current provider to the actuator, Wherein the controller estimates a back electromotive force generated in the actuator using the current or the voltage sensed by the sensor, and estimates the rotational position or the rotational speed of the actuator based on the back electromotive force in a portion where the current of the current provider is turned on.
3. 3. The motor drive control system according to claim 1, wherein the controller estimates the rotational position or the rotational speed of the actuator based on a motion equation in which a rotational force formed by driving the actuator in a portion where a current of the current provider is disconnected is assumed to be 0.
4. 4. The motor drive control system according to claim 3, wherein the controller estimates the rotational speed of the actuator in a portion where the current of the current provider is turned off using the following equation: Wherein the method comprises the steps of Is the current rotational speed of the motor, Is the previous rotational speed, B is the damping coefficient of the actuator, J is the moment of inertia coefficient of the actuator, Is the load torque of the actuator, and Is an estimated period of the rotational speed.
5. 5. The motor drive control system of claim 4, wherein the load torque of the actuator is estimated as a quadratic function of the rotational speed of the actuator using the following equation: Where α is a second order coefficient and β is a first order coefficient.
6. 6. The motor drive control system according to claim 5, wherein the actuator is a motor installed in a pneumatic section or a hydraulic section, and the second-order coefficient α and the first-order coefficient β are mapped or preset in advance according to the pressure of the pneumatic section or the hydraulic section.
7. 7. The motor drive control system of claim 1, wherein the current provider is a pulse width modulated inverter configured to control current in three phases of the actuator, the three phases being a U-phase, a V-phase, and a W-phase.
8. 8. The motor drive control system according to claim 7, wherein the controller estimates the rotational position or the rotational speed of the actuator at a pulse width modulation period in a portion of the current provider where the current is turned off.
9. 9. The motor drive control system of claim 1, wherein the controller comprises a speed controller configured to generate a current command based on the speed command and the estimated rotational speed, and a current controller configured to generate a voltage command of the current provider based on the current command and the estimated rotational position.
10. 10. A motor drive control method comprising the steps of: providing, by a current provider, a current to an actuator configured to generate a rotational force from the current provider while repeatedly switching the current on and off at a preset period and duty cycle; estimating, by a controller, a rotational position or rotational speed of the actuator in a portion where the current of the current provider is turned on and off, and Controlling, by the controller, the current provider to follow a speed command based on the estimated rotational position or rotational speed; Wherein the controller estimates the rotational speed of the actuator in the portion where the current of the current provider is disconnected based on the previous rotational speed of the actuator, the damping coefficient, the moment of inertia coefficient, the load torque, and the estimated period of the rotational speed.
11. 11. The motor drive control method according to claim 10, further comprising the step of: before estimating the rotational position or the rotational speed, it is checked whether the portion is a portion where the current of the current provider is turned on or a portion where the current is turned off.
12. 12. The motor drive control method according to claim 11, wherein in the inspection, when the portion is a portion in which the current of the current provider is turned off, the step of estimating the rotational position or the rotational speed includes estimating the rotational position or the rotational speed of the actuator based on a motion equation in which a rotational force formed by driving the actuator is assumed to be 0.
13. 13. The motor drive control method according to claim 12, wherein: The actuator being an electric motor mounted in the pneumatic or hydraulic section, and Estimating the rotational position or the rotational speed includes estimating the rotational position or the rotational speed of the actuator using a load torque received by the actuator from the pneumatic section or the hydraulic section based on a previously estimated rotational speed of the actuator.
14. 14. The motor drive control method according to claim 10, wherein the step of providing the current applied to the actuator while repeatedly turning on and off the current includes controlling pulse width modulation of currents in three phases of the actuator, the three phases being a U-phase, a V-phase, and a W-phase.
15. 15. The motor drive control method according to claim 14, wherein estimating the rotational position or the rotational speed includes estimating the rotational position or the rotational speed of the actuator at a pulse width modulation period in a portion where the current of the current provider is turned off.

Description

Motor drive control system and method Technical Field The present disclosure relates to a motor drive control system and method, and more particularly, to a system and method for estimating a position and a speed of a motor when a current applied to the motor is controlled to be turned on and off. Background In a fuel cell electric vehicle, under an operation condition in which cooling performance is reduced, such as in a case where the vehicle is driven in a state of high output of the fuel cell stack, for example, when the vehicle is running at high Wen Shangpo, the operation temperature of the fuel cell stack increases, and the humidity of the supplied fuel decreases, so the fuel cell stack is dried and the stack operation voltage decreases. In this case, the heating value of the fuel cell stack increases due to a decrease in the stack operating voltage, thereby creating a negative feedback loop in which the operating temperature of the fuel cell further increases. Recently, in order to prevent a negative feedback loop of an increase in the operating temperature of a fuel cell, a control technique for increasing the relative humidity at an air electrode (cathode) by increasing the pressure of air supplied to the air electrode has been applied to a fuel cell system of a vehicle. Therefore, it is necessary to further increase the compression ratio of the air compressor for supplying air to the air electrodes of the fuel cell stack. Since it is necessary to further increase the compression ratio of air supplied to the air electrode of the fuel cell stack, an air compressor has been designed for achieving a maximum efficiency point at a maximum pressure operation point while further increasing the compression ratio of the air compressor. The problem with this design is that the efficiency of the compressor increases in the portions with high flow and high compression ratio, but decreases in the portions with relatively low flow. Therefore, when the vehicle is traveling in a city (for example, parking and traveling conditions), the power consumption of the air compressor increases in a portion having a low flow rate as a main traveling area, which adversely affects the fuel efficiency of the vehicle. In particular, a pressurized air compressor having a higher air compression ratio than a conventionally used ambient pressure blower is disadvantageous in improving the efficiency of the air compressor due to a difference in motor driving speed between a portion having a low flow rate and a portion having a high flow rate, because the driving speed of the installed motor needs to be further improved. That is, the pressurized air compressor may reduce the inductance of the motor to ensure a sufficient voltage margin in a region where the vehicle travels at a high speed with an increase in the Revolutions Per Minute (RPM) of the motor, and the three-phase ripple current (3-PHASE RIPPLE current) increases, thereby reducing the efficiency of the motor/inverter due to the reduction in the inductance of the motor. In particular, in a portion with a low flow rate requiring a relatively low output, three-phase current is low and current ripple increases, so that efficiency is significantly reduced. That is, the three-phase ripple current is a secondary component and does not contribute to the torque of the motor, and therefore in a portion having a low flow rate and a small motor torque, the amount of the three-phase ripple current is relatively high compared to the three-phase sine wave current component, and therefore the efficiency of the motor/inverter is reduced compared to a portion having a high output. The air foil bearing is applied to the rotation of the motor of the air compressor for high-speed rotation, and the air foil bearing needs to be rotated at a predetermined speed or higher in order to maintain the lifted state. Therefore, when the air foil bearing continuously drives the motor at a speed equal to or less than a reference speed for maintaining the lifted state, there is a problem in that the air foil bearing is damaged due to friction between the air foil bearing and the rotating shaft of the motor. Therefore, in order to prevent damage to the air foil bearing, the air compressor has a minimum driving speed limit, and thus when the vehicle needs to be driven in a state in which the output of the fuel cell is low, by driving the air compressor at the highest driving speed or higher, air is also supplied unnecessarily and excessively, thereby reducing the efficiency of the fuel cell system. Conventionally, a strategy for improving the driving efficiency of an air compressor by repeatedly performing Pulse Width Modulation (PWM) of turning on/off the air compressor in a portion where a vehicle is driven at low power is used. In particular, a position sensor such as a hall sensor is applied to a motor included in an air compressor, and thus the motor is turned on/off by recognizing a rotational speed and