Parallel Converter Control for EV Power Supply Loss Reduction
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Solution Overview
Problem
Existing power supply systems for electric vehicles with multiple power storage devices do not effectively reduce electric power conversion losses, particularly when the required electric power is below the total allowable charge and discharge capacity, leading to inefficiencies in voltage conversion operations.
Innovation Solution
A power supply system with multiple power storage devices, where voltage conversion units are controlled based on detected output voltages or currents to selectively engage and disengage converters, ensuring that only the converter associated with the power storage device having a higher output voltage performs the voltage converting operation when the required electric power is below a threshold, thereby minimizing power conversion losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple voltage conversion units are operated simultaneously to meet high power demand, then the power supply capacity is sufficient, but the electric power conversion loss increases
Solution Approach 1:
The control device dynamically adjusts the operating state of voltage conversion units based on real-time power demand. When power demand is low, some voltage conversion units are stopped to reduce conversion losses. When power demand increases, additional units are activated to meet the required power supply capacity, ensuring optimal system performance across varying operating conditions
Solution Approach 2:
Instead of operating all voltage conversion units continuously, the system activates only the necessary number of units based on current power requirements. This partial action approach prevents excessive conversion operations and reduces energy losses while still meeting the required power supply capacity
2Loss of energy
If voltage conversion units are stopped to reduce conversion loss, then energy efficiency improves, but the power supply capacity decreases
Solution Approach 1:
The control device continuously monitors the power demand from the load device and adjusts the operating state of voltage conversion units accordingly. This feedback mechanism ensures that the system maintains sufficient power supply capacity while minimizing conversion losses by stopping unnecessary voltage conversion operations
3Device complexity
If the power supply voltage difference between parallel-connected power storage devices is small, then the system configuration is simple, but control stability deteriorates due to detection errors
Solution Approach 1:
The system sets the power supply voltage difference between parallel-connected power storage devices to a predetermined value that is sufficiently large compared to detection errors. This parameter change ensures that the voltage difference is always greater than the sum of detection errors, maintaining control stability without requiring complex control mechanisms
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
This approach stabilizes control and reduces electric power conversion losses by optimizing the operation of voltage conversion units, enhancing energy efficiency and fuel consumption efficiency in vehicles equipped with the power supply system.
Implementation Method 1
a plurality of voltage conversion units provided respectively between the plurality of power storage devices and the pair of electric power lines, and each configured to perform a voltage converting operation between the pair of electric power lines and associated one of the power storage devices
Data Source
AI summary
Converters are connected in parallel with each other to a pair of electric power lines. When required electric power required by a drive force generation unit is not more than a threshold value, a converter ECU causes a voltage converting operation of one of the converters that is associated with a power storage device of a higher output voltage to perform voltage converting operation, and causes the voltage converting operation of the other converter to be stopped, based on output voltages of the power storage devices detected by output voltage detection units. The first power storage device and the second power storage device are configured so that one of the power storage devices has a higher power supply voltage by a predetermined value than the power supply voltage of the other power storage device. The predetermined value is defined based on errors which may be included in detected values of the output voltage detection units.