Electric machine torque control system

A vehicle comprising:

• a battery,
• an electric machine configured to propel the vehicle, the electric machine having a stator and a rotor;
• a rotor position sensor;
• an inverter disposed between the battery and the electric machine, configured to convert DC electrical power from the battery into AC electrical power, configured to deliver the AC electrical power to the electric machine, configured to convert AC electrical power from the electric machine into DC electrical power, and configured to deliver the DC electrical power from to the battery;
• and
• a controller programmed to,
• receive a signal from the rotor position sensor that is indicative of an angular position of the rotor,
• responsive to the inverter operating in a first switching mode, control an electric voltage being delivered to the stator relative to the angular position of the rotor to drive a first estimated torque of the electric machine toward a commanded torque,
• calculate a measured torque of the electric machine based on rotational speed of the rotor and a DC electrical power input from the battery to the electric machine via the inverter, and
• responsive to a difference between the commanded torque and the measured torque or to a difference between the commanded torque and the first estimated torque exceeding a threshold, adjust the signal from the rotor position sensor to include a first offset value and control the electric current being delivered to the stator relative to the angular position plus the first offset value to drive the first estimated torque of the electric machine toward the commanded torque.

A vehicle comprising:

• a battery,
• an electric machine configured to propel the vehicle, the electric machine having a stator and a rotor;
• a rotor position sensor;
• an inverter disposed between the battery and the electric machine, configured to convert DC electrical power from the battery into AC electrical power, configured to deliver the AC electrical power to the electric machine, configured to convert AC electrical power from the electric machine into DC electrical power, and configured to deliver the DC electrical power from to the battery;
• and
• a controller programmed to,
• receive a signal from the rotor position sensor that is indicative of an angular position of the rotor,
• responsive to the inverter operating in a first switching mode, control an electric current being delivered to the stator relative to the angular position of the rotor to drive a first estimated torque of the electric machine toward a commanded torque,
• responsive to the inverter operating in a second switching mode, control an electric voltage being delivered to the stator relative to the angular position of the rotor to drive a second estimated torque of the electric machine toward the commanded torque,
• calculate a measured torque of the electric machine based on rotational speed of the rotor and a DC electrical power input from the battery to the electric machine via the inverter circuit,
• responsive to a transition from the first mode to the second mode resulting in a corresponding change in the DC electrical power input exceeding a first threshold and to a difference between the commanded torque and the second estimated torque or a difference between the commanded torque and the measured torque after the transition exceeding a second threshold, adjust the signal from the rotor position sensor to include a first offset value and control the electric voltage being delivered to the stator relative to the angular position plus the first offset value to drive the second estimated torque of the electric machine toward the commanded torque, and
• responsive to a transition from the second mode to the first mode resulting in a corresponding change in the DC electrical power input exceeding a third threshold and the difference between the commanded torque and the second estimated torque or the difference between the commanded torque and the measured torque before the transition exceeding a fourth threshold, adjust the signal from the rotor position sensor to include a second offset value and control the electric current being delivered to the stator relative to the angular position plus the second offset value to drive the first estimated torque of the electric machine toward the commanded torque.