AC Motor Voltage Phase Control to Suppress Reverse Current Response
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Solution Overview
Problem
Existing AC motor control methods face challenges in achieving high responsiveness while suppressing reverse responses that lead to vibration and overcurrent issues, particularly at high speeds.
Innovation Solution
An AC motor control device that includes a change amount limiting unit to control the voltage phase command, limiting the change amount of the voltage phase angle to prevent reverse responses, thereby enhancing responsiveness and suppressing vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the response speed of voltage phase control is increased, then the responsiveness of the AC motor control is improved, but reverse response occurs causing current to follow command value after responding in opposite direction
Solution Approach 1:
The control device applies preliminary anti-action by detecting when current is at maximum value and preventing reverse response before it occurs. The control amount in the voltage phase direction is restricted during the period when current reaches maximum, thereby counteracting the tendency toward reverse response that would otherwise occur due to fast response characteristics.
Solution Approach 2:
The control device dynamically adjusts the voltage phase command based on real-time current conditions. By making the control amount variable according to the current state (particularly when current reaches maximum value), the system optimizes responsiveness while preventing reverse response under varying operating conditions.
2Object-generated harmful factors
If the voltage phase angle is limited to prevent reverse response, then reverse response is suppressed, but the overall response speed becomes too slow
Solution Approach 1:
Instead of continuously limiting the voltage phase angle, the control device applies restriction only partially - specifically during the period when current reaches maximum value. This selective application of limitation suppresses reverse response only when necessary, while maintaining fast response characteristics during other operating conditions.
Solution Approach 2:
The control device performs preliminary detection of current maximum value and proactively restricts the voltage phase control amount before reverse response can occur. This timing-based preliminary action prevents the harmful effect while preserving overall system responsiveness.
3Use of energy by moving object
If pulse saving control is applied to improve voltage utilization rate in high-speed range, then voltage utilization is improved, but reverse response and overcurrent occur more frequently
Solution Approach 1:
The control device uses feedback from current detection to dynamically adjust the voltage phase control. By detecting when current reaches maximum value and using this feedback to restrict further voltage phase changes, the system prevents overcurrent conditions while maintaining the voltage utilization benefits of pulse saving control.
Data Source
AI summary
Provided is an AC motor control device that controls driving of an AC motor by voltage phase control, the AC motor control device being capable of increasing a response speed as a whole while suppressing a reverse response of a current. The AC motor control device converts DC power into AC power based on a voltage phase command output from a voltage phase control unit and outputs the AC power to an AC motor, and the voltage phase control unit includes a change amount limiting unit that limits a change amount of a voltage phase.