System and method for controlling torque of induction motor in electric vehicle
AssigneeLsis Co., Ltd.
InventorsGi Young Choi, Sun Woo Lee
Life of this patent
Estimating the term…
Abstract
Disclosed is a system and a method for controlling torque of induction motor in electric vehicle. The system and method for controlling torque of induction motor in electric vehicle according to the present disclosure has an advantageous effect in that torque control problems caused by saturation of magnetic flux, parameters of induction motor and changes in battery voltages during control of torque in the induction motor can be solved using a look-up table (a type of data table), thereby enhancing accuracy in torque control and improving travel performance and fuel efficiency of the electric vehicle.
Claims7
A system for controlling torque of induction motor in electric vehicle, the system comprising:
- a current command unit outputting d axis and q axis current commands (i*d, i*q) of stationary reference frame from a power command and a rotation speed (ω) of the induction motor using a two dimensional look-up table, and outputting a mutual inductance (Lm) and a rotor torque (Tr) using an one dimensional look-up table based on the outputted d axis current command (i*d);
- a flux/current controller receiving the mutual inductance (Lm) and a rotor torque (Tr) from the current command unit to control a flux of the induction motor and to calculate a slip of a rotor, and based on which, to output d axis and q axis voltage command (V*dq) relative to the d axis and q axis current commands (i*d, i*q) from the current command unit;
- a PWM (Pulse Width Modulation)/gate driver receiving the d axis and q axis current commands (i*d, i*q) from the flux/current controller to modulate a pulse width and output a gate driving voltage of a transistor;
- and an inverter receiving the output from the PWM/gate driver to output an AC voltage for driving the induction motor.
A method for controlling torque of induction motor in electric vehicle including a current command unit, a flux/current controller, a PWM (Pulse Width Modulation)/gate driver and an inverter, the method comprising:
- (a) outputting, by the current command unit, d axis and q axis current commands (i*d, i*q) of stationary reference frame from a power command and a rotation speed of the induction motor using a two dimensional look-up table;
- (b) outputting, by the current command unit, a mutual inductance (Lm) and a rotor torque (Tr) using an one dimensional look-up table based on the outputted d axis current command (i*d);
- (c) receiving, by a flux/current controller, the mutual inductance (Lm) and a rotor torque (Tr) from the current command unit to control a flux of the induction motor and to calculate a slip of a rotor, and based on which, to output d axis and q axis voltage command (V*dq) relative to the d axis and q axis current commands (i*d, i*q) from the current command unit;
- (d) receiving, by a PWM (Pulse Width Modulation)/gate driver, the d axis and q axis current commands (i*d, i*q) from the flux/current controller to modulate a pulse width and output a gate driving voltage of a transistor;
- and (e) receiving, by an inverter, the output from the PWM/gate driver to output an AC voltage for driving the induction motor.
Dependencies are inferred from the claim text.