Supply current management under voltage saturated motor current control
View Patent ↗A system and method for improved anti-windup that minimizes supply current draw under voltage saturated current control operation of synchronous motor drives are provided. The system and method use a voltage limiting module configured to receive a pre-limit voltage command and generate a post-limit voltage command when the motor control system reaches configured threshold; and an anti-windup module configured to determine a voltage difference between the post-limit and pre-limit voltage commands, and compute an anti-windup feedback current using the voltage difference and compensation gains selected to minimize supply current. The compensation gains comprise a gain matrix of values selected to move a motor current trajectory toward a null motor current vector, and the anti-windup module multiplies the gain matrix values by the voltage difference. The anti-windup feedback current and an input current command are then added and provided as an input to the controller.
1. A motor control system for preventing controller windup and managing supply current under voltage saturation conditions, the motor control system comprising:
a voltage limiting module configured to receive a pre-limit voltage command and generate a post-limit voltage command when the motor control system reaches a selected voltage limit corresponding to a configured threshold for limiting voltage applied to a motor controlled by the motor control system; and
an anti-windup module configured to determine a voltage difference by subtracting the post-limit voltage command from the pre-limit voltage command, and to compute an anti-windup feedback current using the voltage difference and compensation gains selected to minimize supply current;
wherein the anti-windup feedback current is provided as feedback to an input current command to the motor control system to introduce feedback cross-coupling of the voltage difference to the current error, and the anti-windup feedback current and an input current command are added and provided as an input to an integral controller to generate a voltage command.
2. The motor control system of claim 1 , wherein the compensation gains comprise a gain matrix of values selected to move a motor current trajectory of the motor toward a null motor current vector, and the anti-windup module multiplies the gain matrix values by the voltage difference.
3. The motor control system of claim 1 , wherein the anti-windup module computes the anti-windup feedback current using a calculation comprising scaling the voltage difference using a gain matrix defined as
K
AW
=
[
K
Add
K
Adq
K
A
q
d
K
Aqq
]
,
wherein K Add , K Adq , K Aqd , and K Aqq are anti-windup parameters.
4. The motor control system of claim 1 , wherein the input current command is further modified by adding a second feedback current based on a measured current of the electric motor.
5. The motor control system of claim 1 , wherein the pre-limit voltage command is computed based on a back electromotive force (BEMF) compensation and a feedback based on a measured current of the electric motor.
6. A method for preventing controller windup in an electric motor and managing supply current under voltage saturation conditions, the method comprising:
receiving, by voltage limiting module in a motor control system, a pre-limit voltage command and generating a post-limit voltage command when the motor control system reaches a selected voltage limit corresponding to a configured threshold for limiting voltage applied to a motor controlled by the motor control system;
determining, by an anti-windup module in the motor control system, a voltage difference by subtracting the post-limit voltage command from the pre-limit voltage command, and computing an anti-windup feedback current using the voltage difference and compensation gains selected to minimize supply current;
providing the anti-windup feedback current as feedback to an input current command to the motor control system to introduce feedback cross-coupling of the voltage difference to the current error; and
adding the anti-windup feedback current and the input current command and providing a resulting summed current as an input to an integral controller to generate motor voltage commands.
7. The method of claim 6 , wherein the compensation gains comprise a gain matrix of values selected to move a motor current trajectory of the motor toward a null motor current vector, and further comprising multiplying, by the anti-windup module, the gain matrix values by the voltage difference.
8. The method of claim 6 , wherein computing the anti-windup feedback current comprises using a calculation comprising scaling the voltage difference using a gain matrix defined as
K
AW
=
[
K
Add
K
Adq
K
A
q
d
K
Aqq
]
,
wherein K Add , K Adq , K Aqd , and K Aqq are anti-windup parameters.
9. The method of claim 6 , further comprising modifying the input current command by adding a second feedback current based on a measured current of the electric motor.
10. The method of claim 6 , wherein the pre-limit voltage command is computed based on a back electromotive force (BEMF) compensation and a feedback based on a measured current of the electric motor.
11. A steering system comprising:
an electric motor that generates an amount of torque corresponding to a post-limit voltage command;
a controller that receives an input current command and generates a voltage command for the motor, the controller comprising
a voltage limiting module configured to receive a voltage command corresponding to a pre-limit voltage command and generate post-limit voltage command when the motor control system reaches a selected voltage limit corresponding to a configured threshold for limiting voltage applied to the motor; and
an anti-windup module configured to determine a voltage difference by subtracting the post-limit voltage command from the pre-limit voltage command, and to compute an anti-windup feedback current using the voltage difference and compensation gains selected to minimize supply current;
wherein the anti-windup feedback current is provided as feedback to an input current command to the motor control system to introduce feedback cross-coupling of the voltage difference to the current error, and the anti-windup feedback current, an input current command, and a second feedback current based on a measured current of the motor are added and provided as an input to an integral controller to generate the voltage commands.
12. The steering system of claim 11 , wherein the compensation gains comprise a gain matrix of values selected to move a motor current trajectory of the motor toward a null motor current vector, and the anti-windup module multiplies the gain matrix values by the voltage difference.
13. The steering system of claim 11 , wherein the anti-windup module computes the anti-windup feedback current using a calculation comprising scaling the voltage difference using a gain matrix defined as
K
AW
=
[
K
Add
K
Adq
K
A
q
d
K
Aqq
]
,
wherein K ddd , K Adq , K Aqd , and K Aqq are anti-windup parameters.
14. The steering system of claim 11 , wherein the pre-limit voltage command is computed based on a back electromotive force (BEMF) compensation and a feedback based on a measured current of the electric motor.
15. A motor control system for preventing controller windup and managing supply current under voltage saturation conditions, the motor control system comprising:
a voltage limiting module configured to receive a pre-limit voltage command and generate a post-limit voltage command when the motor control system reaches a selected voltage limit corresponding to a configured threshold for limiting voltage applied to a motor controlled by the motor control system; and
an anti-windup module configured to determine a voltage difference by subtracting the post-limit voltage command from the pre-limit voltage command, and to compute an anti-windup feedback current using the voltage difference and compensation gains selected to minimize supply current, the anti-windup feedback current and an input current command being added and provided as an input to an integral controller to generate a voltage command.