Drive control device, drive control system, and state estimation method

A state estimation method for estimating a phase or a speed of a rotor of an Alternating-Current (AC) motor using an estimator provided in a drive control device for controlling drive of the AC motor of which the rotor exhibits a salient pole characteristic in response to application of a high-frequency voltage having a frequency higher than a basic drive frequency,

• wherein there is a relationship Ts=2×Tc=Th, where when Ts represents a control cycle, which is a cycle for performing a process related to sensor-less vector control, Tc is a current detection cycle, and Th is a cycle of a high-frequency voltage to be applied, and
• the state estimation method comprises:
• applying synchronously with the control cycle Ts and the current detection cycle Tc, the high-frequency voltage that has the cycle Th corresponding to a frequency outside an audible range on a γ-axis of a γδ semi-synchronous coordinate system composed of the γ-axis whose phase changes so as to have zero deviation from the phase of the rotor and a δ-axis orthogonal to the γ-axis;
• detecting a stator current including a basic drive frequency component and a high-frequency component at the current detection cycle Tc, time-differentiating two most recent detected values of the stator current on the γδ semi-synchronous coordinate system per the cycle Ts to generate either or both of a γ-axis component signal cγ and a δ-axis component signal sδ, and generating a positive correlation signal pc having a positive correlation with the deviation between the phase of the rotor and the phase of the γ-axis per the cycle Ts by using the axis component signal that is generated, and
• performing signal processing of the positive correlation signal pc such that the positive correlation signal pc becomes zero, to generate an estimated value of the phase or the speed of the rotor.