Motor Control Apparatus Adaptive Frequency Switching
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Solution Overview
Problem
Existing motor control methods, such as forced commutation control, have high current consumption and result in large speed estimation errors when switching to Sensorless Field Oriented Control (SFOC), leading to prolonged stabilization times.
Innovation Solution
A motor control apparatus that includes a detection unit, an estimation unit, and control units to manage the transition from forced commutation control to SFOC by increasing the execution frequency of current detection and speed estimation immediately after switching, allowing for faster convergence to stable motor speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If forced commutation control is used to drive the motor from activation, then the motor can be driven reliably at low speeds, but current consumption increases and power efficiency deteriorates
Solution Approach 1:
The patent applies dynamics by making the control mode switchable and adaptive. The system transitions from forced commutation control to SFOC based on real-time detection of induced current magnitude, allowing the control strategy to dynamically adapt to changing motor operating conditions. This enables reliable low-speed startup with forced commutation while switching to efficient SFOC when conditions permit.
Solution Approach 2:
The patent changes the control parameter from fixed forced commutation to variable control mode selection. By monitoring the induced current magnitude as a threshold parameter, the system switches between two control modes: forced commutation when induced current is below the threshold, and SFOC when it exceeds the threshold. This parameter-based switching resolves the contradiction between reliability and energy efficiency.
2Use of energy by moving object
If switching is made immediately from forced commutation control to SFOC, then power efficiency is improved, but speed estimation error increases and stabilization time is prolonged
Solution Approach 1:
The patent implements feedback by continuously monitoring the induced current magnitude and using it to determine the appropriate control mode. The detection unit measures the induced current, and this feedback information is used to trigger the switch from forced commutation to SFOC only when the induced current exceeds a predetermined threshold, ensuring accurate speed estimation before transitioning to efficient control.
Solution Approach 2:
The patent applies preliminary action by performing forced commutation control in advance to build up sufficient induced current before switching to SFOC. This preliminary phase ensures that when the switch to SFOC occurs, the motor is already generating adequate induced current for accurate sensorless speed estimation, thereby avoiding large estimation errors while still achieving early transition to efficient control.
3Use of energy by moving object
If SFOC is used immediately at activation, then power efficiency is maintained, but the motor cannot be driven reliably at low speeds where insufficient induced current is generated
Solution Approach 1:
The patent applies this principle by using forced commutation control as a temporary, short-lived solution during the initial activation phase. This mode is used only briefly until sufficient induced current is generated, after which the system transitions to the more efficient SFOC mode. The forced commutation serves as a disposable preliminary measure to enable reliable startup before efficient operation begins.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces speed estimation errors and shortens the activation time while achieving stable motor control by enhancing the frequency of current detection and speed estimation post-switching to SFOC.
Implementation Method 1
to estimate a rotation speed without a sensor, it is necessary for the motor to be rotating at a relatively high rotation speed and for a sufficient induced current to be generated
Data Source
AI summary
In order to shorten an activation time while realizing stable motor control, a motor control apparatus operable to control a motor is provided. The apparatus controls so as to drive the motor by the forced commutation control in a duration from a start of control of the motor until a first time period elapses, and control so as to drive the motor by the vector control after the first time period has elapsed. In addition, the apparatus controls an execution frequency of a current detection and a rotation speed estimation. The apparatus controls so that a first execution frequency in a second time period after a switch is made from driving by the forced commutation control to driving by the vector control is greater than a second execution frequency in a third time period subsequent to the second time period.