Transient inductance identifier for motor control

A transient inductance estimator for use with a three phase motor controller in which d and q-axis stator feedback voltages are used for motor control purposes, the estimator comprising:

• (a) a regulator for driving a single phase of the motor by providing a d-axis current component in the stationary frame of reference at an operating frequency where the q-axis current component in the stationary frame of reference is zero;
• (b) a sensor to determine d and q-axis stator feedback voltages in the synchronous frame of reference;
• (c) a resolver to divide the d-axis current component by 2 to produce a forward current signal;
• (d) a multiplier for multiplying the operating frequency by the forward current signal to produce a current-frequency signal;
• and
• (e) a divider for dividing the q-axis voltage feedback signal by the current-frequency signal to produce the transient inductance estimate.

A method to be used for determining a transient inductance estimate for an AC motor, the method to be used with a motor controller in which d and q-axis stator feedback voltages are used for motor control purposes, the method comprising the steps of:

• (a) driving a single phase of the motor with an excitation current at an operating frequency;
• (b) determining a q-axis stator feedback voltage in the synchronous frame of reference;
• (c) dividing the excitation current by 2 to produce a forward current signal;
• and
• (d) mathematically combining the operating frequency, forward current signal, and q-axis stator feedback voltage to produce the transient inductance estimate.