Sensorless AC Motor Phase Switching for Abrupt Load Changes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing motor control systems face challenges in maintaining desired torque when the load on a motor abruptly changes during sensor-less energization, leading to discrepancies between predicted and actual rotation periods, which can result in torque loss and step-out.
Innovation Solution
A motor control device and computer program that calculate the time differential value of a virtual line connecting peak values of phase voltage signals, determine the wavelength of each phase voltage signal, and generate a signal to switch the phase of the alternating-current motor based on the calculated wavelength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If sensor-less energization is used to control motor rotation speed, then the control system complexity is reduced, but the accuracy of rotation period prediction deteriorates when load changes abruptly
Solution Approach 1:
The patent implements feedback by detecting the actual rotation period of the motor and using this information to correct the predicted rotation period in the control system. When load changes cause discrepancies between predicted and actual rotation periods, the system adjusts its predictions based on actual measurements, thereby maintaining control accuracy without increasing overall system complexity.
Solution Approach 2:
The patent replaces mechanical sensors with electrical signal analysis. Instead of using physical sensors to detect rotor position and rotation speed, the system analyzes the electrical characteristics of the motor phases (current or voltage signals) to determine rotation period, eliminating the need for additional sensing hardware while maintaining measurement capability.
2Ease of operation
If the predicted rotation period differs significantly from the actual rotation period, then the control system becomes simpler to operate, but torque generation fails and step-out occurs
Solution Approach 1:
The patent implements dynamic adjustment of the predicted rotation period based on operating conditions. Rather than using a fixed prediction method, the system continuously adapts the rotation period prediction to match actual motor behavior, especially during load transitions. This dynamic approach maintains reliability across varying operating conditions while keeping the control system relatively simple.
Solution Approach 2:
The patent performs preliminary detection and correction of rotation period deviations before they cause torque loss or step-out. By monitoring the discrepancy between predicted and actual rotation periods and adjusting control parameters in advance, the system prevents torque generation failure rather than responding after the problem occurs.
Data Source
AI summary
A motor control device according to the present disclosure is a motor control device configured to control voltage signals of a plurality of phases, the voltage signals being applied to an alternating-current motor, the motor control device including: a differential-value calculation unit configured to calculate the time differential value of a virtual line connecting peak values of each of phase voltage signals that are the voltage signals of the respective phases, the voltage signals being input to the alternating-current motor; a wavelength calculation unit configured to calculate the wavelength of each phase voltage signal input to the alternating-current motor from the time differential value; and a switching-signal generation unit configured to generate, based on the calculated wavelength, a signal that switches the phase of the alternating-current motor to which alternating-current voltage is applied.