Methods, systems and apparatus for generating voltage commands used to control operation of a permanent magnet machine

An open loop voltage control system for generating voltage command signals for controlling a permanent magnet machine, the system comprising:

• a voltage command processor module receives inputs comprising a torque command signal (Te*), an angular rotation speed (ωr) of the permanent magnet machine, and a DC input voltage (VDC), and that is configured to generate, based on the inputs, a pair of synchronous reference frame voltage command signals comprising:
• (1) a d-axis voltage command signal (Vd*(kTs1)) and a q-axis voltage command signal (Vq*(kTs1)) in response to a first selection signal, wherein the d-axis voltage command signal (Vd*(kTs1)) and the q-axis voltage command signal (Vq*(kTs1)) are each updated at a first rate;
• and
• (2) a modified d-axis voltage command signal (Vd*(kTs1+mTs0)) and a modified q-axis voltage command signal (Vq*(kTs1+mTs0)) in response to a second selection signal, wherein the modified d-axis voltage command signal (Vd*(kTs1+mTs0)) and the modified q-axis voltage command signal (Vq*(kTs1+mTs0)) are each computed and updated at both the first rate and a second rate, wherein the first rate is a relatively slower rate and the second rate is a relatively faster rate than the first rate.

A method for generating a pair of synchronous reference frame voltage command signals for controlling a permanent magnet machine, the method comprising:

• receiving first inputs comprising:
• a first torque command signal Te*(kTs1), an angular rotation speed (ωr(kTs1)) of (ωr), and a DC input voltage (VDC(kTs1));
• applying the first inputs to a set of voltage command lookup tables to generate a d-axis voltage command signal (Vd*(kTs1)) and a q-axis voltage command signal (Vq*(kTs1)), wherein the d-axis voltage command signal (Vd*(kTs1)) and the q-axis voltage command signal (Vq*(kTs1)) are updated at a first rate that corresponds to a first period (Ts1);
• computing torque transient values (ΔTe*) each representing a difference between a second torque command signal Te*((k+1)Ts1)″ and the first torque command signal Te*(kTs1), and comparing the torque transient values (ΔTe*) to a transient threshold;
• generating a first selection signal whenever one of the torque transient values (ΔTe*) is determined to be less than or equal to the transient threshold;
• and in response to the first selection signal, outputting the d-axis voltage command signal (Vd*(kTs1)) and the q-axis voltage command signal (Vq*(kTs1));
• generating a second selection signal whenever one of the torque transient values (ΔTe*) is determined to be greater than the transient threshold;
• and
• in response to the second selection signal, computing, based on second inputs, a modified d-axis voltage command signal (Vd*(kTs1+mTs0)) and a modified q-axis voltage command signal (Vq*(kTs1+mTs0)), wherein the modified d-axis voltage command signal (Vd*(kTs1+mTs0)) and the modified q-axis voltage command signal (Vq*(kTs1+mTs0)) are computed as a function of and updated at both the first rate and a second rate that corresponds to a second period (Ts0), wherein there are multiple second periods during each first period such that multiple values of the modified d-axis voltage command signal (Vd*(kTs1+mTs0)) and multiple values of the modified q-axis voltage command signal (Vq*(kTs1+mTs0)) are computed during each of the first periods (Ts1).