Power management of permanent magnet synchronous motor (PMSM) drive using machine current limiting

A motor control system configured to limit supply current and regenerative current, the motor control system comprising:

• a torque control module configured to:
• determine a torque command that is limited to within a maximum torque of a motor;
• perform a maximum torque per ampere (MTPA) calculation using the torque command to determine current commands for motor control;
• and
• perform a maximum torque per voltage (MTPV) calculation that modifies the current commands as needed to satisfy a system voltage constraint;
• and
• a motor current limiting module configured to:
• calculate a motor current value;
• use the current commands from the torque control module for motor control, when the calculated motor current value does not exceed a designated maximum motor phase current limit value;
• and
• when the calculated motor current value exceeds the designated maximum motor phase current limit value, determine updated current commands for motor control based on a selected current angle;
• wherein the selected current angle is determined using a search operation for a motor current angle such that, when the calculated motor current exceeds the designated maximum motor phase current limit value, the magnitude of the calculated motor current is fixed at the designated maximum motor phase limit value and the selected current angle is swept from
• π
• 2
• towards 0 until a modified torque increases and becomes equal to the torque commanded by the torque control module and the voltage is lower than or equal to a designated maximum DC link voltage of the motor.

A method for limiting machine current and voltage in motor control system, comprising:

• determine a torque command that is limited to within a maximum torque of the PMSM for a designated maximum DC link voltage and that does not exceed a designated maximum PMSM current limit value;
• and
• perform a maximum torque per ampere (MTPA) calculation using the torque command to determine current commands for PMSM control;
• calculate a motor current value;
• use the current commands when the calculated motor current value does not exceed a designated maximum motor phase current limit value;
• when the calculated motor current value exceeds a designated maximum motor phase current limit value, determine current commands for motor control based on a selected current angle;
• wherein the selected current angle is determined using a search operation for a motor current angle such that, when the calculated motor current exceeds the designated maximum motor phase current limit value, the magnitude of the calculated motor current is fixed at the designated maximum motor phase limit value and the selected current angle is swept from π/2 towards 0 until a modified torque increases and becomes equal to the torque commanded by the torque control module and the voltage is lower than or equal to a designated maximum DC link voltage of the motor.

A method for limiting supply current and regenerative current, the motor control system comprising:

• determining a torque command that is limited to within a maximum torque of a motor;
• performing a maximum torque per ampere (MTPA) calculation using the torque command to determine current commands for motor control;
• performing a maximum torque per voltage (MTPV) calculation that modifies the current commands as needed to satisfy a system voltage constraint;
• calculating a motor current value;
• using the current commands for motor control when the calculated motor current value does not exceed a designated maximum motor phase current limit value;
• and
• when the calculated motor current value exceeds the designated maximum motor phase current limit value, determining updated current commands for motor control based on a selected current angle;
• wherein the selected current angle is determined using a search operation for a motor current angle such that, when the calculated motor current exceeds the designated maximum motor phase current limit value, the magnitude of the calculated motor current is fixed at the designated maximum motor phase limit value and the selected current angle is swept from π/2 towards 0 until a modified torque increases and becomes equal to the torque commanded by the torque control module and the voltage is lower than or equal to a designated maximum DC link voltage of the motor.