DC-DC Converter Voltage Stabilization for Electrified Vehicles
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Solution Overview
Problem
Conventional electrified vehicles require additional energy storage devices to maintain high voltage bus stability when the main contactor is open, leading to increased weight, cost, and packaging space, due to the slow responsiveness of motor generator units.
Innovation Solution
Implementing a DC-DC converter controlled by a controller that stabilizes the high voltage bus voltage when the main contactor is open, utilizing a DC-DC control circuit, LV control circuit, HV control circuit, and arbitrator circuit to generate error signals and duty cycles, thereby eliminating the need for additional energy storage devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional energy storage devices are implemented to maintain high voltage bus stability when the main contactor is open, then the voltage stability is improved, but the weight, cost, and packaging space increase
Solution Approach 1:
The DC-DC converter is designed to perform multiple functions: it normally converts high voltage to low voltage for the LV battery system, but also serves as a high voltage bus stabilizer when the main contactor is open. This multi-functionality eliminates the need for separate energy storage devices dedicated solely to contactor-open scenarios, reducing overall system weight and cost while maintaining voltage stability.
2Reliability
If the motor generator unit is used to maintain high voltage bus stability when the main contactor is open, then the voltage stability is improved, but the responsiveness is slow and additional energy storage devices are required
Solution Approach 1:
The DC-DC converter is designed to perform multiple functions: it normally converts high voltage to low voltage for the LV battery system, but also serves as a high voltage bus stabilizer when the main contactor is open. This multi-functionality eliminates the need for separate energy storage devices dedicated solely to contactor-open scenarios, reducing overall system weight and cost while maintaining voltage stability.
Solution Approach 2:
The DC-DC converter acts as an intermediary device between the HV battery system and the LV battery system. By controlling the power flow through this intermediary converter, the system can rapidly stabilize the high voltage bus without requiring the MGU to respond directly, thereby achieving faster responsiveness than the MGU alone could provide.
3Reliability
If additional energy storage devices are implemented to maintain high voltage bus stability when the main contactor is open, then the voltage stability is improved, but the packaging space increases
Solution Approach 1:
The DC-DC converter is designed to perform multiple functions: it normally converts high voltage to low voltage for the LV battery system, but also serves as a high voltage bus stabilizer when the main contactor is open. This multi-functionality eliminates the need for separate energy storage devices dedicated solely to contactor-open scenarios, reducing overall system weight and cost while maintaining voltage stability.
4Speed
If a more expensive MGU capable of maximized responsiveness is used, then the responsiveness is improved, but the cost increases
Solution Approach 1:
The DC-DC converter is designed to perform multiple functions: it normally converts high voltage to low voltage for the LV battery system, but also serves as a high voltage bus stabilizer when the main contactor is open. This multi-functionality eliminates the need for separate energy storage devices dedicated solely to contactor-open scenarios, reducing overall system weight and cost while maintaining voltage stability.
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 solution allows for faster voltage control and reduced weight and cost by leveraging the DC-DC converter's capabilities, enabling the use of smaller or no additional energy storage devices to maintain high voltage bus stability.
Implementation Method 1
a direct current to direct current (DC-DC) converter connected to the HV bus and the LV bus
Implementation Method 2
a controller configured to: when the main contactor is open or malfunctioning, control the DC-DC converter to stabilize the HV bus voltage
Data Source
AI summary
A system comprises a high voltage (HV) battery system connected to an HV bus, a motor generator unit (MGU) connected to the HV bus, a main contactor disposed on the HV bus between the MGU and the HV battery system such that, when the main contactor is closed, the HV battery system stabilizes a voltage of the HV bus, a low voltage (LV) battery system connected to an LV bus and configured to stabilize a voltage of the LV bus when the main contactor is open or malfunctioning, a direct current to direct current (DC-DC) converter connected to the HV bus and the LV bus, and a controller configured to (i) when the main contactor is closed, control the DC-DC converter to stabilize the LV bus voltage, and (ii) when the main contactor is open or malfunctioning, control the DC-DC converter to stabilize the HV bus voltage.