Boosting Converter Suspension for Electric Vehicle Efficiency
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Solution Overview
Problem
Conventional electric vehicles face inefficiencies due to the continuous operation of boosting converters, even in no-load states, leading to increased switching losses, which affect drivability and system efficiency.
Innovation Solution
The system suspends the boosting converter operation and adjusts the carrier frequency of inverters to maintain DC high voltage stability, thereby extending the suspension time and reducing energy losses while ensuring drivability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the boosting converter operates continuously to maintain DC high voltage, then the voltage stability is improved, but the switching loss increases
Solution Approach 1:
The boosting converter operates periodically rather than continuously. The control unit suspends the boosting converter when the power generated by the generator balances the power consumed by the motor, and resumes operation when voltage deviation exceeds a threshold, creating a periodic on-off pattern that reduces switching loss while maintaining voltage stability
Solution Approach 2:
The control unit changes the operating parameters of the motor (torque, rotational speed) to compensate for the suspension of the boosting converter. By adjusting motor parameters, the system maintains power balance and DC high voltage stability without continuous boosting converter operation
2Loss of energy
If the boosting converter is suspended to reduce switching loss, then energy efficiency is improved, but the DC high voltage stability deteriorates
Solution Approach 1:
The control unit continuously monitors the DC high voltage and compares it with a target voltage. When the voltage deviation exceeds a predetermined threshold during boosting converter suspension, the control unit resumes boosting converter operation, creating a feedback-based control mechanism that maintains voltage stability
Solution Approach 2:
The control unit adjusts motor operating parameters (torque, rotational speed) in real-time to compensate for the suspension of the boosting converter, maintaining power balance and preventing excessive voltage deviation
3Stability of the object's composition
If the motor torque is corrected to maintain DC high voltage during boosting converter suspension, then voltage stability is improved, but the drivability deteriorates
Solution Approach 1:
The control unit corrects motor torque only to the extent necessary to maintain DC high voltage stability during boosting converter suspension, rather than making excessive corrections that would adversely affect drivability. This partial action approach balances voltage stability with drivability
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 enhances the efficiency of the electric vehicle system by increasing the suspension time of the boosting converter, minimizing energy losses, and maintaining vehicle drivability.
Implementation Method 1
The boosting converter is configured to boost a DC low voltage of a battery to output a DC high voltage by turning on and off switching elements and using energy stored in a reactor
Implementation Method 2
The inverters operate the electric motor by converting the DC power into a three-phase alternating (AC) power for operating the electric motor
Data Source
AI summary
A hybrid vehicle includes a battery, a boosting converter, first and second inverters, a first inverter connected to the first inverter, a second motor generator connected to the second inverter, and a control unit configured to start and suspend the boosting converter. The control unit increases one or both of carrier frequencies Fc1, Fc2 of the first and second inverters as a real boost voltage VHr increases during a suspended state of the boosting converter. The control unit decreases one or both of the carrier frequencies of the first and second inverters as real boost voltage VHr decreases during a suspended state of the boosting converter. System efficiency of an electric vehicle can be improved effectively by increasing the suspension time of the boosting converter, while securing drivability of the vehicle.