Feedback Control System with Integration Stop for Motor Drive Stability
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Solution Overview
Problem
Feedback control systems face instability and efficiency reduction when repeatedly turning on/off outputs in short-term periods, particularly at low motor speeds, due to increased ripple current and switching losses, leading to errors in driving current measurement and oscillations.
Innovation Solution
A method and system for feedback-control that involves controlling a current supply unit to repeatedly turn on/off outputs by predetermined periods and duties, incorporating integration control and feed-forward compensation, with the integration control process stopped during output off periods, and using a switching element to manage the output, ensuring the output follows a target value and minimizing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the output is repeatedly turned on/off in a short-term period to save power consumption, then power consumption is reduced, but the integration control process generates large errors and causes severe oscillations in the driving current
Solution Approach 1:
The patent applies periodic action by implementing pulse-width modulation (PWM) control that repeatedly turns the output on and off at high frequency. The switching element operates in periodic cycles with controlled duty ratios, enabling power consumption reduction while maintaining control stability through the periodic nature of the switching action.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the driving current and adjusting the switching element's duty ratio to maintain the current at the target value. The feedback mechanism calculates the difference between actual and target current values, and dynamically adjusts the on/off timing to eliminate errors and prevent oscillations, resolving the stability issue.
2Power
If the motor inductance is reduced to obtain sufficient voltage margin in high-speed operating region, then voltage margin is improved, but three-phase ripple current is increased and efficiency is reduced
Solution Approach 1:
The patent applies dynamics by making the switching element's duty ratio variable rather than fixed. The duty ratio is dynamically adjusted based on real-time feedback of the driving current and operational conditions. This dynamic control enables the system to optimize voltage utilization and minimize ripple current across different operating regions, improving both voltage margin and efficiency.
3Use of energy by moving object
If the driving current is turned off to save power at low speed, then power consumption is reduced, but the measured current value becomes zero and error integral value increases excessively
Solution Approach 1:
The patent applies preliminary action by maintaining a minimal standby current flow through the switching element even when operating at low speed. Rather than completely turning off the current, the system pre-maintains a small current path that allows continuous measurement while consuming minimal power. This preliminary current maintenance prevents the measured value from dropping to zero and avoids excessive error accumulation.
Data Source
AI summary
Disclosed are a method and a system for feedback-controlling including controlling a current supply unit in a controller so that an output applied to a driving unit from the current supply unit is repeatedly turned on/off by predetermined period and duty. The method also includes feedback-controlling of an output value of the controller applied to the current supply unit from the controller so that the output of the current supply unit follows a target value. The feedback-controlling includes an integration control process and stops the integration control process in the period that the current supply unit turns off the output thereof.