HEV DC/DC Voltage Control to Delay Engine Start for CO2 Reduction
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Solution Overview
Problem
Conventional hybrid-electric vehicle (HEV) systems generate CO2 emissions when the internal combustion engine is used to recharge the high voltage battery system, and there is a need to reduce these emissions.
Innovation Solution
A hybrid electric vehicle (HEV) system that includes an internal combustion engine, an electric traction motor, a belt starter generator (BSG) unit, a low voltage battery system, and a high voltage battery system. A powertrain control system with a controller that adjusts the output voltage setpoints of the DC/DC converter and the BSG unit to reduce high voltage battery power consumption, thereby avoiding or delaying the use of the internal combustion engine and reducing CO2 emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the internal combustion engine is used to recharge the high voltage battery system, then the high voltage battery system is powered and recharged, but CO2 emissions are generated
Solution Approach 1:
The controller dynamically adjusts the output voltage setpoint of the DC/DC converter based on real-time monitoring of the low voltage battery's state of charge (SOC), temperature, and power demand. By changing the voltage parameter adaptively, the system optimizes power flow to recharge the low voltage battery using excess high voltage battery power, thereby reducing the need to run the internal combustion engine for recharging and lowering CO2 emissions.
2Reliability
If the output voltage setpoints of the DC/DC converter and BSG unit are increased to charge the low voltage battery, then the low voltage battery SOC is maintained, but high voltage battery power consumption increases
Solution Approach 1:
The controller continuously monitors the low voltage battery's state of charge (SOC), temperature, and power demand, and uses this feedback to dynamically adjust the DC/DC converter's output voltage setpoint. When the low voltage battery SOC is within an acceptable range and temperature is appropriate, the controller increases the voltage setpoint to accelerate charging and reduce future engine runtime. When SOC is already high or temperature is extreme, the controller reduces the voltage setpoint to conserve high voltage battery power. This closed-loop feedback mechanism balances reliability maintenance with energy conservation.
3Object-generated harmful factors
If the controller dynamically adjusts voltage setpoints to reduce CO2 emissions, then engine runtime is reduced, but control system complexity increases
Solution Approach 1:
The existing DC/DC converter control architecture is extended to include CO2 reduction functionality by adding voltage setpoint adjustment capabilities. The controller integrates multiple functions: traditional DC/DC conversion control, low voltage battery management (SOC, temperature monitoring), and now emissions reduction through dynamic voltage optimization. By making the DC/DC converter controller multi-functional, the system reduces CO2 emissions without requiring entirely separate control systems, thereby limiting the increase in overall system complexity.
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
The system effectively reduces CO2 emissions by minimizing the need to turn on the internal combustion engine, while maintaining the functionality of the HEV powertrain.
Implementation Method 1
A DC/DC converter is configured to convert high voltage from the high voltage battery system into low voltage to charge the low voltage battery and support low voltage loads
Implementation Method 2
a belt starter generator (BSG) unit configured to start the internal combustion engine
Implementation Method 3
a low voltage battery system including a low voltage battery electrically coupled to the BSG unit
Implementation Method 4
a high voltage battery system including a high voltage traction battery configured to power the electric traction motor
Data Source
AI summary
A hybrid electric vehicle (HEV) includes an internal combustion engine, an electric traction motor, a belt starter generator (BSG) unit, a low voltage battery system including a low voltage battery, and a high voltage battery system including a high voltage traction battery. A DC/DC converter is configured to convert high voltage from the high voltage battery system into low voltage to charge the low voltage battery and support low voltage loads. A powertrain control system configured for reducing HEV CO2 emissions includes a controller configured to control an output voltage setpoint of the DC/DC converter and the BSG unit. The controller is configured to selectively increase or decrease the output voltage setpoints of the DC/DC converter and/or the BSG unit to reduce high voltage battery power consumption to thereby avoid or delay turning on the internal combustion engine to reduce CO2 emissions.