Reversible DC-DC Converter Control via Power Setpoint Tolerance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The control of voltage-regulated DC-DC converters in powertrains faces challenges, particularly in maintaining power output during battery discharge and input power during charging, while managing singularity issues when currents at the converter's input or output cancel each other out, which complicates energy management and efficiency.
Innovation Solution
A method for controlling a reversible DC-DC converter that determines a voltage setpoint by calculating the difference between the power setpoint and estimated power, using tolerance values to adjust the voltage within allowed deviations, and incorporates a correction loop to improve convergence and handle exogenous inputs, ensuring the voltage setpoint remains within defined limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If voltage regulation control is used for the DC-DC converter, then the converter cost is reduced and control simplicity is improved, but control difficulty increases when current becomes zero (singularity issue)
Solution Approach 1:
The patent changes the control parameter from voltage to power. The controller receives a reference power value and controls the DC-DC converter to output power equal to the reference power, avoiding the singularity issue that occurs in voltage control when current is zero. This parameter change maintains control simplicity while eliminating the operational difficulty.
2Reliability
If power-based control is implemented to avoid singularity, then control reliability is improved, but control complexity increases due to power calculation and tolerance management
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously monitors the actual power output of the DC-DC converter and compares it with the reference power value. Based on this feedback, the controller adjusts the converter's operation to maintain power equality, ensuring reliability while managing complexity through systematic feedback control.
Solution Approach 2:
The patent introduces a power tolerance range around the reference power value. Instead of requiring exact power matching, the controller maintains power within an acceptable tolerance band, simplifying control while ensuring sufficient reliability for practical applications.
3Power
If the voltage setpoint is calculated as power divided by current, then power regulation is achieved, but singularity occurs when current is zero
Solution Approach 1:
The patent performs preliminary checks to detect when current approaches zero before the singularity occurs. When zero current is detected, the controller switches to a alternative control mode or sets the voltage setpoint to zero, preventing the singularity issue from occurring in the first place.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method for controlling a reversible DC-DC converter of a motor vehicle provided with a power train comprising an internal combustion engine (2) mechanically connected to an electric machine (3) powered by an inverter (4), the inverter (4) being electrically connected to at least one battery by way of the reversible DC-DC converter (5), the DC-DC converter (5) furthermore being connected to auxiliary equipment. The method comprises the following steps: the difference between a setpoint and an estimate of the power at the terminals of the DC-DC converter (5) is determined, and a voltage setpoint at the terminals of the DC-DC converter (5) is determined as a function of the difference determined, and of a tolerance value such that the voltage setpoint is able to be determined when the current flowing at the terminals of the DC-DC converter is zero.