Direct discrete-time current controller for virtually-translated alternating current machine

A method for controlling an electric drive system having an alternating current (AC) motor connected to a power inverter module (PIM) and to a load, wherein the AC motor is a salient machine, the method comprising:

• determining an operating point of the AC motor;
• selectively modifying an asymmetric time constant of the AC motor at the operating point of the AC motor in control logic of the controller, the control logic including a plant model of the electric drive system, including selectively and independently manipulating a direct axis (d-axis) and quadrature axis (q-axis) inductance and resistance via the controller, such that the asymmetric time constant is virtually translated in the control logic into a symmetric modified time constant by manipulating/adding virtual inductive and virtual resistive terms independently and per operating point of the AC motor;
• and
• controlling the AC motor at the operating point using the symmetric modified time constant.

A motor vehicle comprising:

• a vehicle body;
• one or more road wheels connected to the vehicle body;
• and
• an electric drive system connected to the vehicle body, the electric drive system including:
• a traction battery pack;
• a power inverter module (PIM) connected to the traction battery pack;
• an alternating current (AC) traction motor connected to the PIM and to one or more of the road wheels, wherein the AC traction motor is a salient machine;
• and
• a controller programmed with control logic including a plant model of the electric drive system, wherein the plant model includes an asymmetric time constant of the AC motor, and wherein the controller is configured to:
• determine a torque command and an angular speed of the AC traction motor as an operating point thereof;
• selectively modify the asymmetric time constant at the operating point by selectively and independently manipulating a direct axis (d-axis) and quadrature axis (q-axis) inductance and resistance of the AC traction motor, such that the asymmetric time constant is virtually translated in the control logic into a symmetric modified time constant by manipulating/adding virtual inductive and virtual resistive terms independently and per operating point of the AC motor;
• and
• control the AC traction motor at the operating point using the symmetric modified time constant.