Load Driving Control Apparatus Using Current Slope Adaptation
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Solution Overview
Problem
Existing load driving control apparatuses for inductive loads have low robustness due to the need for gain re-adjustment when inductance values change, such as with aging degradation or specification changes, affecting control precision.
Innovation Solution
A load driving control apparatus that includes a duty ratio setting part with a slope calculating and two calculating parts to calculate duty ratios based on current slopes and actual current values, allowing for adaptive control even when inductance values change, using a combination of PID control and slope-based calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If PID control with predetermined gains is used to calculate duty ratio, then control implementation is simple, but control precision deteriorates when inductance value changes due to aging or specification changes
Solution Approach 1:
The system performs preliminary action by calculating and storing current slopes in advance during a slope calculation period before normal control operation begins. These pre-calculated slopes are then used during normal operation to determine duty ratios, eliminating the need for real-time complex calculations and maintaining precision without increasing operational complexity.
Solution Approach 2:
The system changes parameters by using calculated current slopes (first slope and second slope) as dynamic parameters instead of fixed predetermined gains. This allows the control system to adapt to varying inductance values while maintaining simple implementation, as the slopes automatically reflect the actual electrical characteristics of the load.
2Measurement precision
If gain re-adjustment is performed when inductance value changes, then control precision can be maintained, but system robustness deteriorates due to frequent adjustments
Solution Approach 1:
The system implements feedback by continuously monitoring actual current values and using them to calculate current slopes that reflect the actual electrical characteristics of the load. This feedback mechanism allows the system to automatically adapt to inductance changes without manual intervention, maintaining both precision and robustness through self-adjustment based on real-time measurements.
Solution Approach 2:
The system performs self-service by automatically calculating current slopes and using them to determine appropriate duty ratios without requiring external gain re-adjustment. The control apparatus serves itself by adapting to inductance value changes through internal slope calculations, eliminating the need for manual intervention and thereby maintaining robustness while preserving control precision.
3Speed
If duty ratio is calculated based on difference between target current value and actual current value, then control response is straightforward, but adaptability to inductance changes deteriorates
Solution Approach 1:
The system applies dynamics by transitioning from static predetermined gains to dynamic current slopes that automatically adapt to changing electrical characteristics. The first and second slopes are calculated based on actual current behavior, enabling the control response to remain fast while simultaneously adapting to inductance changes through real-time slope updates.
Solution Approach 2:
The system changes parameters by replacing fixed control gains with dynamically calculated current slopes. This parameter change enables the control system to maintain fast response characteristics while adapting to different inductance values, as the slopes are continuously updated to reflect the actual electrical state of the load.
Data Source
AI summary
A load driving control apparatus calculates current slopes in an on-period and an off-period in one PWM cycle period, respectively, by using actual currents at a start time point and an end time point of the PWM cycle period as well as two sets of data, as data including a duty ratio corresponding to the actual current values. The data is so determined that the actual current data value of predetermined one of the start time point and the end time point is within a learning area. The duty ratio is calculated based on a difference between a target current value and the actual current value until calculation of the current slopes and is completed. The duty ratio is calculated based on the current slopes, the actual current value at start time point and a target current value after the calculation of the current slopes is completed. Since an actual current change characteristic is calculated based on the actual current values and the duty ratio is calculated based on the current change characteristic, robustness is enhanced.