Hybrid EV DCDC Voltage Control for Low-Voltage Charging Demand
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Solution Overview
Problem
The challenge in hybrid electric vehicles is optimizing fuel economy and ensuring basic operation by effectively controlling the DCDC output voltage, which is crucial for powering low-voltage loads, as traditional generators are often replaced by hybrid motors and DCDC converters.
Innovation Solution
A DCDC output voltage control method and system that adjusts the output voltage based on the vehicle's operating state and low-voltage load demands, setting the voltage to a normal target when in high power or abnormal engine states, and boosting it when the high-voltage battery has sufficient charge and the load requires it.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the DCDC output voltage is boosted to meet charging demand of low-voltage load, then the charging capability is improved, but the fuel economy of hybrid power assembly system deteriorates
Solution Approach 1:
The patent implements dynamic voltage adjustment by switching between normal voltage mode and voltage boost mode based on real-time detection of vehicle operating conditions (high power output demand, abnormal engine flame-out, and low-voltage load charging demand). This dynamic control allows the system to provide voltage boosting only when necessary, thereby improving charging capability while minimizing fuel consumption penalties.
Solution Approach 2:
The control system changes the output voltage parameter of the DCDC converter based on detected operating conditions. When high power output demand or abnormal engine flame-out is detected, the system switches from normal voltage output to voltage boost output, enabling the low-voltage load to charge while balancing charging needs against fuel economy considerations.
2Use of energy by moving object
If the DCDC output voltage is adjusted frequently to optimize fuel economy, then the fuel efficiency is improved, but the system complexity increases
Solution Approach 1:
The control method segments the operating conditions into distinct categories (normal operation, high power output demand, abnormal engine flame-out, voltage boost demand) and applies different voltage control strategies to each segment. This segmentation simplifies the control logic by providing clear decision boundaries, reducing the overall system complexity while enabling frequent voltage adjustments for fuel economy optimization.
Solution Approach 2:
The system employs feedback control by continuously detecting vehicle operating conditions and adjusting the DCDC output voltage accordingly. The control unit monitors parameters such as high power output demand, abnormal engine flame-out, and low-voltage load charging demand, then feeds this information back to adjust the voltage output, achieving fuel efficiency improvement through a relatively simple feedback mechanism.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Optimizes fuel economy by adjusting DCDC output voltage according to vehicle conditions, ensuring efficient power distribution and reducing power consumption during high demand or abnormal states, thus maintaining vehicle operation.
Implementation Method 1
a DCDC converts high-voltage direct current into low-voltage power required by a low-voltage power supply circuit
Data Source
AI summary
A DCDC output voltage control method and control system for a hybrid electric vehicle are provided. The method includes: when a DCDC converter is in a buck operation mode, determining whether the vehicle is in a high power output demand state or an abnormal engine flame-out state; if so, setting the output voltage of the DCDC converter to a normal target voltage; otherwise, determining whether a low-voltage load has a charging voltage boost demand, and when the low-voltage load has the charging voltage boost demand and the power of a high-voltage battery is greater than a power threshold, setting the output voltage of the DCDC converter according to the voltage level corresponding to the charging voltage boost demand, to meet the charging demand of the low-voltage load. The fuel economy of a hybrid power assembly system can be optimized.