DC-to-DC Converter Loss Optimization via Interpolating Points
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Solution Overview
Problem
DC-to-DC converters in electric and hybrid vehicles face inefficiencies due to fixed control trajectories that do not account for the flexibility to minimize losses within the control system's time constraints, leading to suboptimal performance.
Innovation Solution
The DC converter determines a short-period output trajectory independently, using interpolating points between reference values to reduce losses, by employing a controller that can perform digital control at shorter intervals than the entire control system, allowing for flexible determination of local trajectories between reference values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a fixed control trajectory is used for the DC converter, then the control system is simple to implement, but the converter losses increase due to inability to optimize locally
Solution Approach 1:
The control trajectory is segmented into multiple sections between reference values, allowing independent optimization of each segment. The controller divides the control period into shorter intervals and determines interpolating points for each segment based on loss minimization, rather than using a single fixed trajectory for the entire period.
Solution Approach 2:
The control trajectory is made dynamic by allowing the controller to adjust interpolating points between reference values based on real-time loss calculations. The trajectory adapts to changing operating conditions by dynamically determining optimal intermediate points, transforming the static fixed trajectory into a flexible dynamic path.
2Adaptability or versatility
If the control period of the DC converter is shortened, then the flexibility to determine local output trajectory improves, but the device complexity increases
Solution Approach 1:
The controller performs digital control at periodic intervals shorter than the overall control system period. By using a control period Ts that is a fraction of the system period Ta, the controller can execute multiple control cycles within one system period, enabling flexible local trajectory determination while maintaining manageable complexity through periodic operation.
Solution Approach 2:
The controller pre-calculates and stores loss information for various output trajectories in a lookup table before operation. This preliminary action allows the controller to quickly reference optimal trajectories during operation without performing complex real-time calculations, reducing operational complexity while maintaining adaptability.
3Productivity
If traditional control methods are used, then the control system is simple, but the inductor loss and overall performance are suboptimal
Solution Approach 1:
The controller uses feedback from loss information to adjust the control trajectory. By monitoring inductor current and comparing actual loss against expected loss, the controller can modify interpolating points and trajectory selection to minimize inductor loss, creating a closed-loop system that continuously optimizes efficiency.
Solution Approach 2:
The controller changes operating parameters such as duty cycle and switching frequency by adjusting interpolating points between reference values. By varying these parameters dynamically based on loss considerations, the controller optimizes inductor loss and overall converter efficiency beyond what traditional fixed-parameter control achieves.
Data Source
AI summary
A DC-to-DC, converter that can reduce a loss of the converter is provided. The DC-to-DC converter includes an inductor, a switching transistor connected to the inductor, and a controller that drives the transistor. The controller acquires a next step reference value for the DC-to-DC converter in a sampling time Ta. The next step reference value is expressed by an output voltage of the DC-to-DC converter or a flux linkage of the inductor. The controller determines interpolating points between a current state value that corresponds to the current reference value and the next step reference value in a sampling time Ts that is shorter than the sampling time Ta based on a loss of the DC-to-DC converter while changing from the current state value to the next step reference value. The controller supplies to the switching transistor the PWM signals with a duty that corresponds to each of the interpolating points.