Inverter device and electric motor drive system

摘要

An inverter device according to an embodiment includes a constant power controller. The constant power controller computes and outputs, when a value of a voltage reference to an AC motor exceeds a predetermined threshold value, a d-axis current reference correction value on the basis of the value of the voltage reference and the predetermined threshold value. Moreover, the constant power controller generates the d-axis current reference correction value by using a constant power model determined by a torque reference or a speed reference and a supplied direct voltage at an output switching timing determined based on a winding switching signal and outputs the d-axis current reference correction value for a predetermined time.

主权项

1. An inverter device comprising:
a voltage supply unit that is connected to one end of an armature winding of an AC motor corresponding to each phase and supplies a variable voltage for driving the AC motor to the AC motor; a winding switching signal generator that is connected to each of another end and a halfway portion of the armature winding and outputs a winding switching signal to a winding switching section that changes connection of the armature winding; an output switching signal generator that generates an output switching signal based on the winding switching signal, the output switching signal including a first signal indicating a switching timing from a low-speed mode to a high-speed mode, a second signal indicating a switching timing from the high-speed mode to the low-speed mode, and a third signal indicating timing other than the switching timings; and a constant power controller that outputs one of d-axis current reference correction values in accordance with one of the first to third signals without using feedback values that are detected values, wherein the constant power controller:
computes and outputs, when the output switching signal is the third signal and when a value of a voltage reference to the AC motor exceeds a predetermined threshold value, the d-axis current reference correction value on the basis of the value of the voltage reference and the predetermined threshold value; andgenerates, when the output switching signal is the first signal or the second signal, the d-axis current reference correction value by using constant power models for the low-speed and high-speed modes determined by a torque reference or a speed reference and a supplied direct voltage and outputs the d-axis current reference correction value for a predetermined time.