Feedforward control of permanent magnet synchronous motor drive under current sensing failure
According to one or more embodiments, an example system includes a motor, and a motor control system that includes a low side current measurement subsystem. The system further includes a processor that switches the motor control system to use feedforward current control in response to detecting a current measurement failure in the low side current measurement subsystem. The processor further identifies a first phase that has a failed current measurement. The processor also computes a current measurement for the first phase, which has the current measurement failure. The processor further uses the computed current measurement to compute a parameter estimate.
1. A system comprising:
a motor; and
a motor control system that comprises a low side current measurement subsystem, and a processor that is configured to:
switch the motor control system to use feedforward current control in response to detecting a current measurement failure in the low side current measurement subsystem;
identify a first phase that has a failed current measurement;
compute a current measurement for the first phase, which has the current measurement failure; and
compute a parameter estimate using the computed current measurement, wherein the parameter estimate is computed in response to a validity flag being set to VALID.
2. The system of claim 1 , wherein the processor uses the feedforward current control to generate an input voltage command for the motor.
3. The system of claim 1 , wherein the current measurement for the first phase is computed using the remaining phases in the motor control system.
4. The system of claim 1 , wherein the parameter estimate is added to a feedforward machine parameter estimate to compute a machine parameter estimate.
5. The system of claim 1 , wherein the validity flag is set based on a modulation index.
6. The system of claim 5 , wherein the validity flag is set based on comparison of the modulation index with a predetermined threshold as:
F
v
=
{
VALID
,
m
<
m
t
INVALID
,
m
≥
m
t
,
wherein F v is the validity flag, m is the modulation index, and m t is the predetermined threshold.
7. A computer implemented method comprising:
switching a current controller to use feedforward current control in response to detecting a current measurement failure in a low side current measurement subsystem of a motor control system;
identifying a first phase that has the current measurement failure;
computing a current measurement for the first phase, which has the current measurement failure; and
computing a parameter estimate of the motor control system using the computed current measurement, wherein the parameter estimate is computed in response to a validity flag being set to VALID.
8. The method of claim 7 , wherein the feedforward current control is used to generate an input voltage command for the motor.
9. The method of claim 7 , wherein the current measurement for the first phase is computed using the remaining phases in the motor control system.
10. The method of claim 7 , further comprising:
computing a machine parameter estimate by adding the parameter estimate to a feedforward machine parameter estimate.
11. The method of claim 7 , wherein the validity flag is set based on a modulation index.
12. The method of claim 11 , wherein the validity flag is set based on comparison of the modulation index with a predetermined threshold as:
F
v
=
{
VALID
,
m
<
m
t
INVALID
,
m
≥
m
t
,
wherein F v is the validity flag, m is the modulation index, and m t is the predetermined threshold.
13. A steering system comprising:
a motor control system that comprises a low side current measurement subsystem, and a processor that is configured to:
switch the motor control system to use feedforward current control in response to detecting a current measurement failure in the low side current measurement subsystem;
identify a first phase that has a failed current measurement;
compute a current measurement for the first phase, which has the current measurement failure; and
compute, in response to a validity flag being set to VALID, a parameter estimate using the computed current measurement.
14. The steering system of claim 13 , wherein the current measurement for the first phase is computed using the remaining phases in the motor control system.
15. The steering system of claim 13 , wherein the parameter estimate is added to a feedforward machine parameter estimate to compute a machine parameter estimate.
16. The steering system of claim 13 , wherein the validity flag is set based on a modulation index.
17. The steering system of claim 16 , wherein the validity flag is set based on comparison of the modulation index with a predetermined threshold as:
F
v
=
{
VALID
,
m
<
m
t
INVALID
,
m
≥
m
t
,
wherein F v is the validity flag, m is the modulation index, and m t is the predetermined threshold.