Linear and nonlinear dynamic bus control for AFE applications

A power converter, comprising:

• an AC input, including AC nodes;
• a DC output, including first and second DC nodes;
• a switching circuit coupled with the AC input and with the DC output, the switching circuit including switching devices respectively configured to selectively couple one of the AC nodes with a respective one of the first and second DC nodes according to a respective one of a plurality of switching control signal;
• and
• a controller, including:
• a modulation index controller configured to compute a modulation index according to a bus control input,
• a modulator configured to generate the switching control signals according to the modulation index to cause the switching circuit to control a DC bus voltage at the DC output, and
• a dynamic bus controller configured to generate the bus control input according to the DC bus voltage at the DC output, a direction of power flow at the DC output, and a power at the DC output;
• wherein the dynamic bus controller is configured to:
• for a regenerating direction of power flow at the DC output, limit the power at the DC output at a value computed according to a first non-linear function of the DC bus voltage;
• and
• for a motoring direction of power flow at the DC output, limit the power at the DC output at a value computed according to a second non-linear function of the DC bus voltage.

A method, comprising:

• for a regenerating direction of power flow at a DC output of a rectifier:
• controlling a DC bus voltage at the DC output between first and second regenerating voltage limits, and
• limiting power at the DC output according to a regenerating power limit parameter;
• and
• for a motoring direction of power flow at the DC output:
• controlling the DC bus voltage at the DC output between first and second motoring voltage limits, and
• limiting power at the DC output according to a motoring power limit parameter;
• for the regenerating direction of power flow at the DC output, limiting the power at the DC output at a selected one of an integer number N constant regenerating power limit values in each respective one of N ranges of the DC bus voltage, where N is greater than 1;
• and
• for the motoring direction of power flow at the DC output, limiting the power at the DC output at a selected one of an integer number N constant motoring power limit values in each respective one of the N ranges of the DC bus voltage.

A method, comprising:

• for a regenerating direction of power flow at a DC output of a rectifier:
• controlling a DC bus voltage at the DC output between first and second regenerating voltage limits, and
• limiting power at the DC output according to a regenerating power limit parameter;
• and
• for a motoring direction of power flow at the DC output:
• controlling the DC bus voltage at the DC output between first and second motoring voltage limits, and
• limiting power at the DC output according to a motoring power limit parameter;
• for the regenerating direction of power flow at the DC output, limiting the power at the DC output at a value computed according to a first non-linear function of the DC bus voltage;
• and
• for the motoring direction of power flow at the DC output, limiting the power at the DC output at a value computed according to a second non-linear function of the DC bus voltage.

A non-transitory computer readable medium that stores computer executable instructions, which, when executed by a processor, cause the processor to:

• for a regenerating direction of power flow at a DC output of a rectifier:
• control a DC bus voltage at the DC output between first and second regenerating voltage limits, and
• limit power at the DC output according to a regenerating power limit parameter;
• and
• for a motoring direction of power flow at the DC output:
• control the DC bus voltage at the DC output between first and second motoring voltage limits, and
• limit power at the DC output according to a motoring power limit parameter;
• further comprising computer executable instructions, which, when executed by a processor, cause the processor to:
• for the regenerating direction of power flow at the DC output, limit the power at the DC output at a selected one of an integer number N constant regenerating power limit values in each respective one of N ranges of the DC bus voltage, where N is greater than 1;
• and
• for the motoring direction of power flow at the DC output, limit the power at the DC output at a selected one of an integer number N constant motoring power limit values in each respective one of the N ranges of the DC bus voltage.

A non-transitory computer readable medium that stores computer executable instructions, which, when executed by a processor, cause the processor to:

• for a regenerating direction of power flow at a DC output of a rectifier:
• control a DC bus voltage at the DC output between first and second regenerating voltage limits, and
• limit power at the DC output according to a regenerating power limit parameter;
• and
• for a motoring direction of power flow at the DC output:
• control the DC bus voltage at the DC output between first and second motoring voltage limits, and
• limit power at the DC output according to a motoring power limit parameter;
• further comprising computer executable instructions, which, when executed by a processor, cause the processor to:
• for the regenerating direction of power flow at the DC output, limit the power at the DC output at a value computed according to a first non-linear function of the DC bus voltage;
• and
• for the motoring direction of power flow at the DC output, limit the power at the DC output at a value computed according to a second non-linear function of the DC bus voltage.